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Sample records for compact nuclear simulator

  1. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    SciTech Connect

    Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-28

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  2. Mesoscale Simulations of Powder Compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya.; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-01

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  3. Water-compacted Na-bentonite interaction in simulated nuclear fuel disposal conditions: The role of accessory minerals

    SciTech Connect

    Melamed, A.; Pitkaenen, P.

    1994-12-31

    In an earlier laboratory study, ion exchange processes and smectite alteration were investigated through the interaction between compacted Na-bentonite (Volclay MX-80) and simulated granitic groundwater solutions. In the water, a concentration decrease in Ca, Mg and K, and an increase in Na, HCO{sub 3} and SO{sub 4} were recorded. The total amount of Ca available in the water, however, was found insufficient to account for the recorded formation of Ca-smectite, and it is therefore assumed that the accessory Ca-bearing minerals in the bentonite provide the fundamental source of these cations. X-ray powder diffraction analyses and microscope observations of the bentonite samples were re-conducted. Quartz, feldspars, pyrite, calcite and traces of gypsum were revealed as the primary accessories. In reacted samples, goethite and siderite are found as the secondary mineral products in association with corroded pyrite grains, while calcite and gypsum tend to disappear. From these results it is assumed that the oxygen present in the water and bentonite pore space promotes the oxidation of pyrite (dissolved) and the precipitation of goethite. The pore water pH decreases and calcite is partly dissolved. Through the dissolution, the bulk amount of Ca ions in addition to those arising by diffusion from the water is provided. Some of the reaction-released bicarbonate and Fe{sup 2+} re-precipitate in the bentonite as siderite, while the rest (as also SO{sub 4} ions) diffuse into the water. Though the relative oxygen content in the experiment may be considered higher than that of the repository concept for nuclear fuel disposal (interaction in a semi-closed system with high water/bentonite ratio), the near field geochemistry predictions imply limited oxidizing conditions, which will be characterized by the above-described processes in sulphide-bearing bentonite and occur for some time after the sealing of the repository.

  4. Mesoscale simulations of powder compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Antoun, Tarabay; Liu, Benjamin

    2009-06-01

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to experimental match compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show evidence of hard-to-explain reshock states above the single-shock Hugoniot line, which have also been observed in the experiments. We found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations, since 2D results tend to underpredict stress levels for high-porosity powders regardless of material properties. We developed a process to extract macroscale information for the simulation which can be directly used in calibration of continuum model for heterogeneous media.

  5. Mesoscale Simulations of Power Compaction

    SciTech Connect

    Lomov, I; Fujino, D; Antoun, T; Liu, B

    2009-08-06

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

  6. COMB: Compact embedded object simulations

    NASA Astrophysics Data System (ADS)

    McEwen, Jason D.

    2016-06-01

    COMB supports the simulation on the sphere of compact objects embedded in a stochastic background process of specified power spectrum. Support is provided to add additional white noise and convolve with beam functions. Functionality to support functions defined on the sphere is provided by the S2 code (ascl:1606.008); HEALPix (ascl:1107.018) and CFITSIO (ascl:1010.001) are also required.

  7. The Settling and Compaction of Nuclear Waste Slurries

    SciTech Connect

    MACLEAN, G.T.

    1999-11-15

    The settling and compaction of simulated and real nuclear waste slurries were extensively studied. Experiments were carried out with simulated wastes at laboratory and large-scale sizes, and the results compared. A model of settling was derived and a method developed to correlate and scale-up settling data for different slurries and vessel sizes.

  8. Compaction Scale Up and Optimization of Cylindrical Fuel Compacts for the Next Generation Nuclear Plant

    SciTech Connect

    Jeffrey J. Einerson; Jeffrey A. Phillips; Eric L. Shaber; Scott E. Niedzialek; W. Clay Richardson; Scott G. Nagley

    2012-10-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of designed experiments have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel. Results from these experiments are included. The scale-up effort is nearing completion with the process installed and operational using nuclear fuel materials. The process is being certified for manufacture of qualification test fuel compacts for the AGR-5/6/7 experiment at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL).

  9. Vibratory Shock Compaction of Granular Nuclear Waste

    NASA Astrophysics Data System (ADS)

    Amme, Robert C.

    2004-05-01

    Vibratory Shock Compaction (VSC) is a proven means for quickly forming strong, durable solids from a wide variety of granular materials[1]. Calcination of tank and other forms of high level radioactive wastes results in fine granular material that is quite amenable to volume reduction and stabilization. We have employed utilities coal ash as a calcine waste surrogate, blended with a quartz/feldspar-rich sand and 0-20% proportions of a borosilicate glass. The blends were compacted at room temperature and fired so that the glass melt could form an efficient binder. Included in the blend are small quantities of three RCRA metals, chromium, cadmium and lead, to permit testing for heavy metal stability. The VSC process is described and the results presented in terms of the waste form dissolution rates, compressive strengths, elastic moduli as determined from resonant frequency measurements, and heavy metal leach rates from Toxicity Characteristic Leaching Procedure measurements. Vibratory shock compaction employing glass binders appears to be a viable alternative to traditional vitrification processes for granular waste forms. [1] See http://www.resonantshockcompact.com

  10. Nuclear fuel particles and method of making nuclear fuel compacts therefrom

    DOEpatents

    DeVelasco, Rubin I.; Adams, Charles C.

    1991-01-01

    Methods for making nuclear fuel compacts exhibiting low heavy metal contamination and fewer defective coatings following compact fabrication from a mixture of hardenable binder, such as petroleum pitch, and nuclear fuel particles having multiple layer fission-product-retentive coatings, with the dense outermost layer of the fission-product-retentive coating being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.3 g/cm.sup.3. Such particles can be pre-compacted in molds under relatively high pressures and then combined with a fluid binder which is ultimately carbonized to produce carbonaceous nuclear fuel compacts having relatively high fuel loadings.

  11. NET23/STING Promotes Chromatin Compaction from the Nuclear Envelope

    PubMed Central

    de las Heras, Jose I.; Saiz-Ros, Natalia; Makarov, Alexandr A.; Lazou, Vassiliki; Meinke, Peter; Waterfall, Martin; Kelly, David A.; Schirmer, Eric C.

    2014-01-01

    Changes in the peripheral distribution and amount of condensed chromatin are observed in a number of diseases linked to mutations in the lamin A protein of the nuclear envelope. We postulated that lamin A interactions with nuclear envelope transmembrane proteins (NETs) that affect chromatin structure might be altered in these diseases and so screened thirty-one NETs for those that promote chromatin compaction as determined by an increase in the number of chromatin clusters of high pixel intensity. One of these, NET23 (also called STING, MITA, MPYS, ERIS, Tmem173), strongly promoted chromatin compaction. A correlation between chromatin compaction and endogenous levels of NET23/STING was observed for a number of human cell lines, suggesting that NET23/STING may contribute generally to chromatin condensation. NET23/STING has separately been found to be involved in innate immune response signaling. Upon infection cells make a choice to either apoptose or to alter chromatin architecture to support focused expression of interferon genes and other response factors. We postulate that the chromatin compaction induced by NET23/STING may contribute to this choice because the cells expressing NET23/STING eventually apoptose, but the chromatin compaction effect is separate from this as the condensation was still observed when cells were treated with Z-VAD to block apoptosis. NET23/STING-induced compacted chromatin revealed changes in epigenetic marks including changes in histone methylation and acetylation. This indicates a previously uncharacterized nuclear role for NET23/STING potentially in both innate immune signaling and general chromatin architecture. PMID:25386906

  12. NET23/STING promotes chromatin compaction from the nuclear envelope.

    PubMed

    Malik, Poonam; Zuleger, Nikolaj; de las Heras, Jose I; Saiz-Ros, Natalia; Makarov, Alexandr A; Lazou, Vassiliki; Meinke, Peter; Waterfall, Martin; Kelly, David A; Schirmer, Eric C

    2014-01-01

    Changes in the peripheral distribution and amount of condensed chromatin are observed in a number of diseases linked to mutations in the lamin A protein of the nuclear envelope. We postulated that lamin A interactions with nuclear envelope transmembrane proteins (NETs) that affect chromatin structure might be altered in these diseases and so screened thirty-one NETs for those that promote chromatin compaction as determined by an increase in the number of chromatin clusters of high pixel intensity. One of these, NET23 (also called STING, MITA, MPYS, ERIS, Tmem173), strongly promoted chromatin compaction. A correlation between chromatin compaction and endogenous levels of NET23/STING was observed for a number of human cell lines, suggesting that NET23/STING may contribute generally to chromatin condensation. NET23/STING has separately been found to be involved in innate immune response signaling. Upon infection cells make a choice to either apoptose or to alter chromatin architecture to support focused expression of interferon genes and other response factors. We postulate that the chromatin compaction induced by NET23/STING may contribute to this choice because the cells expressing NET23/STING eventually apoptose, but the chromatin compaction effect is separate from this as the condensation was still observed when cells were treated with Z-VAD to block apoptosis. NET23/STING-induced compacted chromatin revealed changes in epigenetic marks including changes in histone methylation and acetylation. This indicates a previously uncharacterized nuclear role for NET23/STING potentially in both innate immune signaling and general chromatin architecture. PMID:25386906

  13. NET23/STING promotes chromatin compaction from the nuclear envelope.

    PubMed

    Malik, Poonam; Zuleger, Nikolaj; de las Heras, Jose I; Saiz-Ros, Natalia; Makarov, Alexandr A; Lazou, Vassiliki; Meinke, Peter; Waterfall, Martin; Kelly, David A; Schirmer, Eric C

    2014-01-01

    Changes in the peripheral distribution and amount of condensed chromatin are observed in a number of diseases linked to mutations in the lamin A protein of the nuclear envelope. We postulated that lamin A interactions with nuclear envelope transmembrane proteins (NETs) that affect chromatin structure might be altered in these diseases and so screened thirty-one NETs for those that promote chromatin compaction as determined by an increase in the number of chromatin clusters of high pixel intensity. One of these, NET23 (also called STING, MITA, MPYS, ERIS, Tmem173), strongly promoted chromatin compaction. A correlation between chromatin compaction and endogenous levels of NET23/STING was observed for a number of human cell lines, suggesting that NET23/STING may contribute generally to chromatin condensation. NET23/STING has separately been found to be involved in innate immune response signaling. Upon infection cells make a choice to either apoptose or to alter chromatin architecture to support focused expression of interferon genes and other response factors. We postulate that the chromatin compaction induced by NET23/STING may contribute to this choice because the cells expressing NET23/STING eventually apoptose, but the chromatin compaction effect is separate from this as the condensation was still observed when cells were treated with Z-VAD to block apoptosis. NET23/STING-induced compacted chromatin revealed changes in epigenetic marks including changes in histone methylation and acetylation. This indicates a previously uncharacterized nuclear role for NET23/STING potentially in both innate immune signaling and general chromatin architecture.

  14. Numerical simulation of the shock compaction of copper powder

    SciTech Connect

    Benson, D.J. ); Nellis, W.J. )

    1994-07-10

    The shock compaction of an aggregate of randomly distributed copper particles with a nonuniform size distribution is simulated using an Eulerian hydrocode. A shock Hugoniot for a copper powder is calculated from a series of shock compaction simulations and compared to experimental results. The powder particles are modeled as rods in two dimensions. The particle size distribution is generated from a representative powder size distribution via a simple Monte-Carlo method and is initially numerically packed to a dense powder compact using the pseudo-gravity method. [copyright] 1994 American Institute of Physics

  15. A compact inflow control device for simulating flight fan noise

    NASA Astrophysics Data System (ADS)

    Homyak, L.; McArdle, J. G.; Heidelberg, L. J.

    Inflow control device (ICD's) of various shapes and sizes have been used to simulate inflight fan tone noise during ground static tests. A small, simple inexpensive ICD design was optimized from previous design and fabrication techniques. This compact two-fan-diameter ICD exhibits satisfactory acoustic performance characteristics without causing noise attenuation or redirection. In addition, it generates no important new noise sources. Design and construction details of the compact ICD are discussed and acoustic performance test results are presented.

  16. A compact inflow control device for simulating flight fan noise

    NASA Astrophysics Data System (ADS)

    Homyak, L.; McArdle, J. G.; Heidelberg, L. J.

    1983-04-01

    Inflow control device (ICD's) of various shapes and sizes have been used to simulate inflight fan tone noise during ground static tests. A small, simple inexpensive ICD design was optimized from previous design and fabrication techniques. This compact two-fan-diameter ICD exhibits satisfactory acoustic performance characteristics without causing noise attenuation or redirection. In addition, it generates no important new noise sources. Design and construction details of the compact ICD are discussed and acoustic performance test results are presented.

  17. A compact inflow control device for simulating flight fan noise

    NASA Technical Reports Server (NTRS)

    Homyak, L.; Mcardle, J. G.; Heidelberg, L. J.

    1983-01-01

    Inflow control device (ICD's) of various shapes and sizes have been used to simulate inflight fan tone noise during ground static tests. A small, simple inexpensive ICD design was optimized from previous design and fabrication techniques. This compact two-fan-diameter ICD exhibits satisfactory acoustic performance characteristics without causing noise attenuation or redirection. In addition, it generates no important new noise sources. Design and construction details of the compact ICD are discussed and acoustic performance test results are presented.

  18. Mechanical compaction of Waste Isolation Pilot Plant simulated waste

    SciTech Connect

    Butcher, B.M. ); Thompson, T.W.; VanBuskirk, R.G.; Patti, N.C. )

    1991-06-01

    The investigation described in this report acquired experimental information about how materials simulating transuranic (TRU) waste compact under axial compressive stress, and used these data to define a model for use in the Waste Isolation Pilot Plant (WIPP) disposal room analyses. The first step was to determine compaction curves for various simultant materials characteristic of TRU waste. Stress-volume compaction curves for various combinations of these materials were than derived to represent the combustible, metallic, and sludge waste categories. Prediction of compaction response in this manner is considered essential for the WIPP program because of the difficulties inherent in working with real (radioactive) waste. Next, full-sized 55-gallon drums of simulated combustible, metallic, and sludge waste were axially compacted. These results provided data that can be directly applied to room consolidation and data for comparison with the predictions obtained in Part 1 of the investigation. Compaction curves, which represent the combustible, metallic, and sludge waste categories, were determined, and a curve for the averaged waste inventory of the entire repository was derived. 9 refs., 31 figs., 12 tabs.

  19. 2nd Iberian Nuclear Astrophysics Meeting on Compact Stars

    NASA Astrophysics Data System (ADS)

    Perez-Garcia, M. Angeles; Pons, Jose; Albertus, C.

    2012-02-01

    ORGANIZING COMMITTEE Dr M Ángeles Pérez-García (Área Física Teórica-Universidad de Salamanca & IUFFYM) Dr J A Miralles (Universidad de Alicante) Dr J Pons (Universidad de Alicante) Dr C Albertus (Área Física Nuclear-Universidad de Salamanca & IUFFYM) Dr F Atrio (Área Física Teórica-Universidad de Salamanca & IUFFYM) PREFACE The second Iberian Nuclear Astrophysics meeting was held at the University of Salamanca, Spain on 22-23 September 2011. This volume contains most of the presentations delivered at this international workshop. This meeting was the second in the series following the previous I Encuentro Ibérico de Compstar, held at the University of Coimbra, Portugal in 2010. The main purpose of this meeting was to strengthen the scientific collaboration between the participants of the Iberian and the rest of the southern European branches of the European Nuclear Astrophysics network, formerly, COMPSTAR. This ESF (European Science Foundation) supported network has been crucial in helping to make a broader audience for the the most interesting and relevant research lines being developed currently in Nuclear Astrophysics, especially related to the physics of neutron stars. It is indeed important to emphasize the need for a collaborative approach to the rest of the scientific communities so that we can reach possible new members in this interdisciplinary area and as outreach for the general public. The program of the meeting was tailored to theoretical descriptions of the physics of neutron stars although some input from experimental observers and other condensed matter and optics areas of interest was also included. The main scientific topics included: Magnetic fields in compact stars Nuclear structure and in-medium effects in nuclear interaction Equation of state: from nuclear matter to quarks Importance of crust in the evolution of neutron stars Computational simulations of collapsing dense objects Observational phenomenology In particular, leading

  20. Compact Gamma-Beam Source for Nuclear Security Technologies

    NASA Astrophysics Data System (ADS)

    Gladkikh, P.; Urakawa, J.

    2015-10-01

    A compact gamma-beam source dedicated to the development of the nuclear security technologies by use of the nuclear resonance fluorescence is described. Besides, such source is a very promising tool for novel technologies of the express cargoes inspection to prevent nuclear terrorism. Gamma-beam with the quanta energies from 0.3MeV to 7.2MeV is generated in the Compton scattering of the "green" laser photons on the electron beam with energies from 90MeV to 430MeV. The characteristic property of the proposed gammabeam source is a narrow spectrum (less than 1%) at high average gamma-yield (of 1013γ/s) due to special operation mode.

  1. 2nd Iberian Nuclear Astrophysics Meeting on Compact Stars

    NASA Astrophysics Data System (ADS)

    Perez-Garcia, M. Angeles; Pons, Jose; Albertus, C.

    2012-02-01

    ORGANIZING COMMITTEE Dr M Ángeles Pérez-García (Área Física Teórica-Universidad de Salamanca & IUFFYM) Dr J A Miralles (Universidad de Alicante) Dr J Pons (Universidad de Alicante) Dr C Albertus (Área Física Nuclear-Universidad de Salamanca & IUFFYM) Dr F Atrio (Área Física Teórica-Universidad de Salamanca & IUFFYM) PREFACE The second Iberian Nuclear Astrophysics meeting was held at the University of Salamanca, Spain on 22-23 September 2011. This volume contains most of the presentations delivered at this international workshop. This meeting was the second in the series following the previous I Encuentro Ibérico de Compstar, held at the University of Coimbra, Portugal in 2010. The main purpose of this meeting was to strengthen the scientific collaboration between the participants of the Iberian and the rest of the southern European branches of the European Nuclear Astrophysics network, formerly, COMPSTAR. This ESF (European Science Foundation) supported network has been crucial in helping to make a broader audience for the the most interesting and relevant research lines being developed currently in Nuclear Astrophysics, especially related to the physics of neutron stars. It is indeed important to emphasize the need for a collaborative approach to the rest of the scientific communities so that we can reach possible new members in this interdisciplinary area and as outreach for the general public. The program of the meeting was tailored to theoretical descriptions of the physics of neutron stars although some input from experimental observers and other condensed matter and optics areas of interest was also included. The main scientific topics included: Magnetic fields in compact stars Nuclear structure and in-medium effects in nuclear interaction Equation of state: from nuclear matter to quarks Importance of crust in the evolution of neutron stars Computational simulations of collapsing dense objects Observational phenomenology In particular, leading

  2. Vibratory compaction method for preparing lunar regolith drilling simulant

    NASA Astrophysics Data System (ADS)

    Chen, Chongbin; Quan, Qiquan; Deng, Zongquan; Jiang, Shengyuan

    2016-07-01

    Drilling and coring is an effective way to acquire lunar regolith samples along the depth direction. To facilitate the modeling and simulation of lunar drilling, ground verification experiments for drilling and coring should be performed using lunar regolith simulant. The simulant should mimic actual lunar regolith, and the distribution of its mechanical properties should vary along the longitudinal direction. Furthermore, an appropriate preparation method is required to ensure that the simulant has consistent mechanical properties so that the experimental results can be repeatable. Vibratory compaction actively changes the relative density of a raw material, making it suitable for building a multilayered drilling simulant. It is necessary to determine the relation between the preparation parameters and the expected mechanical properties of the drilling simulant. A vibratory compaction model based on the ideal elastoplastic theory is built to represent the dynamical properties of the simulant during compaction. Preparation experiments indicated that the preparation method can be used to obtain drilling simulant with the desired mechanical property distribution along the depth direction.

  3. Diffusion Welding of Compact Heat Exchangers for Nuclear Applications

    SciTech Connect

    Denis Clark; Ron Mizia; Dr. Michael V. Glazoff; Mr. Michael W. Patterson

    2012-06-01

    The next-­-generation nuclear plant (NGNP) is designed to be a flexible source of energy, producing various mixes of electrical energy and process heat (for example, for hydrogen generation) on demand. Compact heat exchangers provide an attractive way to move energy from the helium primary reactor coolant to process heat uses. For process heat efficiency, reactor outlet temperatures of 750-­-900°C are desirable. There are minor but deleterious components in the primary coolant; the number of alloys that can handle this environment is small. The present work concentrates on Alloys 800H and 617.

  4. Simulation of Granular Compacts in Two Dimensions

    SciTech Connect

    VIDALES,A.M.; KENKRE,V.M.; HURD,ALAN J.

    2000-07-24

    Simulations of granular packings in 2-D by throwing disks in a rectangular die are performed. Different size distributions as bimodal, uniform and gaussian are used. Once the array of particles is done, a relaxation process is carried on using a large-amplitude, low-frequency vertical shaking. This relaxation is performed a number N of times. Then, the authors measure the density of the package, contact distribution, coordination number distribution, entropy and also the disks size distribution vs. height. The dependence of all these magnitudes on the number N of shakings used to relax the packing and on the size distribution parameters are explored and discussed.

  5. Postanalysis of the CNPS (Compact Nuclear Power Source) critical experiment

    SciTech Connect

    Palmer, R.G.

    1988-01-01

    The Compact Nuclear Power Source (CNPS) was designed to produce electric power for remote sites where fuel logistics and costs would justify a remotely sited nuclear power plant. Since the reactor was of novel design with no appropriate benchmarks, a series of critical experiments was carried out at LANL. This paper describes the methodology and reports the results of the postanalysis that was performed on the critical experiments, which included several distinct critical configurations, the measurement of the isothermal temperature coefficient of reactivity and various material worths. Comparisons with measurements indicate that current methods and cross sections are adequate for calculating at least the beginning of life conditions in low enriched /sup 235/U-graphite cores. 7 refs., 4 figs., 4 tabs.

  6. Simulated and experimental compression of a compact toroid

    SciTech Connect

    Johnson, J N; Hwang, D Q; Horton, R D; Evans, R W; Owen, J M

    2009-05-06

    We present simulation results and experimental data for the compression of a compact toroid by a conducting nozzle without a center electrode. In both simulation and experiment, the flow of the plasma is greatly obstructed by even modest magnetic fields. A simple mechanism for this obstruction is suggested by our simulations. In particular, the configuration of the plasmoid's magnetic field plays a significant role in the success of the experiment. We analyze two types of plasma configurations under compression and demonstrate that the results from the simulations matches those from the experiments, and that the mechanism predicts the different behaviors observed in the two cases.

  7. Nuclear Power Plant Simulation Game.

    ERIC Educational Resources Information Center

    Weiss, Fran

    1979-01-01

    Presents a nuclear power plant simulation game which is designed to involve a class of 30 junior or senior high school students. Scientific, ecological, and social issues covered in the game are also presented. (HM)

  8. Dynamic Simulation Nuclear Power Plants

    1992-03-03

    DSNP (Dynamic Simulator for Nuclear Power-Plants) is a system of programs and data files by which a nuclear power plant, or part thereof, can be simulated. The acronym DSNP is used interchangeably for the DSNP language, the DSNP libraries, the DSNP precompiler, and the DSNP document generator. The DSNP language is a special-purpose, block-oriented, digital-simulation language developed to facilitate the preparation of dynamic simulations of a large variety of nuclear power plants. It is amore » user-oriented language that permits the user to prepare simulation programs directly from power plant block diagrams and flow charts by recognizing the symbolic DSNP statements for the appropriate physical components and listing these statements in a logical sequence according to the flow of physical properties in the simulated power plant. Physical components of nuclear power plants are represented by functional blocks, or modules. Many of the more complex components are represented by several modules. The nuclear reactor, for example, has a kinetic module, a power distribution module, a feedback module, a thermodynamic module, a hydraulic module, and a radioactive heat decay module. These modules are stored in DSNP libraries in the form of a DSNP subroutine or function, a block of statements, a macro, or a combination of the above. Basic functional blocks such as integrators, pipes, function generators, connectors, and many auxiliary functions representing properties of materials used in nuclear power plants are also available. The DSNP precompiler analyzes the DSNP simulation program, performs the appropriate translations, inserts the requested modules from the library, links these modules together, searches necessary data files, and produces a simulation program in FORTRAN.« less

  9. Numerical simulation of compact intracloud discharge and generated electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

    2015-06-01

    Using the concept of the relativistic runaway electron avalanche, numerical simulation of compact intracloud discharge as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-UHF range was conducted. We evaluated the numbers of electrons initiating the avalanche, with which the calculated EMP characteristics are consistent with measured ones. The discharge capable of generating EMPs produces runaway electrons in numbers close to those in the source of terrestrial γ-flashes (TGF) registered in the nearest space, which may be an argument for a joint EMP and TGF source.

  10. Acoustic Characterization of Compact Jet Engine Simulator Units

    NASA Technical Reports Server (NTRS)

    Doty, Michael J.; Haskin, Henry H.

    2013-01-01

    Two dual-stream, heated jet, Compact Jet Engine Simulator (CJES) units are designed for wind tunnel acoustic experiments involving a Hybrid Wing Body (HWB) vehicle. The newly fabricated CJES units are characterized with a series of acoustic and flowfield investigations to ensure successful operation with minimal rig noise. To limit simulator size, consistent with a 5.8% HWB model, the CJES units adapt Ultra Compact Combustor (UCC) technology developed at the Air Force Research Laboratory. Stable and controllable operation of the combustor is demonstrated using passive swirl air injection and backpressuring of the combustion chamber. Combustion instability tones are eliminated using nonuniform flow conditioners in conjunction with upstream screens. Through proper flow conditioning, rig noise is reduced by more than 20 dB over a broad spectral range, but it is not completely eliminated at high frequencies. The low-noise chevron nozzle concept designed for the HWB test shows expected acoustic benefits when installed on the CJES unit, and consistency between CJES units is shown to be within 0.5 dB OASPL.

  11. Special nuclear material simulation device

    DOEpatents

    Leckey, John H.; DeMint, Amy; Gooch, Jack; Hawk, Todd; Pickett, Chris A.; Blessinger, Chris; York, Robbie L.

    2014-08-12

    An apparatus for simulating special nuclear material is provided. The apparatus typically contains a small quantity of special nuclear material (SNM) in a configuration that simulates a much larger quantity of SNM. Generally the apparatus includes a spherical shell that is formed from an alloy containing a small quantity of highly enriched uranium. Also typically provided is a core of depleted uranium. A spacer, typically aluminum, may be used to separate the depleted uranium from the shell of uranium alloy. A cladding, typically made of titanium, is provided to seal the source. Methods are provided to simulate SNM for testing radiation monitoring portals. Typically the methods use at least one primary SNM spectral line and exclude at least one secondary SNM spectral line.

  12. Non-Nuclear Testing of Compact Reactor Technologies at NASA MSFC

    NASA Technical Reports Server (NTRS)

    Houts, Michael G.; Pearson, J. Boise; Godfroy, Thomas J.

    2011-01-01

    Safe, reliable, compact, autonomous, long-life fission systems have numerous potential applications, both terrestrially and in space. Technologies and facilities developed in support of these systems could be useful to a variety of concepts. At moderate power levels, fission systems can be designed to operate for decades without the need for refueling. In addition, fast neutron damage to cladding and structural materials can be maintained at an acceptable level. Nuclear design codes have advanced to the stage where high confidence in the behavior and performance of a system can be achieved prior to initial testing. To help ensure reactor affordability, an optimal strategy must be devised for development and qualification. That strategy typically involves a combination of non-nuclear and nuclear testing. Non-nuclear testing is particularly useful for concepts in which nuclear operating characteristics are well understood and nuclear effects such as burnup and radiation damage are not likely to be significant. To be mass efficient, a SFPS must operate at higher coolant temperatures and use different types of power conversion than typical terrestrial reactors. The primary reason is the difficulty in rejecting excess heat to space. Although many options exist, NASA s current reference SFPS uses a fast spectrum, pumped-NaK cooled reactor coupled to a Stirling power conversion subsystem. The reference system uses technology with significant terrestrial heritage while still providing excellent performance. In addition, technologies from the SFPS system could be applicable to compact terrestrial systems. Recent non-nuclear testing at NASA s Early Flight Fission Test Facility (EFF-TF) has helped assess the viability of the reference SFPS and evaluate methods for system integration. In July, 2011 an Annular Linear Induction Pump (ALIP) provided by Idaho National Laboratory was tested at the EFF-TF to assess performance and verify suitability for use in a10 kWe technology

  13. Non Nuclear NTR Environmental Simulator

    SciTech Connect

    Emrich, William J. Jr.

    2006-01-20

    Nuclear Thermal Rockets or NTR's have been suggested as a propulsion system option for vehicles traveling to the moon or Mars. These engines are capable of providing high thrust at specific impulses at least twice that of today's best chemical engines. The performance constraints on these engines are mainly the result of temperature limitations on the fuel coupled with a limited ability to withstand chemical attack by the hot hydrogen propellant. To operate at maximum efficiency, fuel forms are desired which can withstand the extremely hot, hostile environment characteristic of NTR operation for at least several hours. The simulation of such an environment would require an experimental device which could simultaneously approximate the power, flow, and temperature conditions which a nuclear fuel element (or partial element) would encounter during NTR operation. Such a simulation would allow detailed studies of the fuel behavior and hydrogen flow characteristics under reactor like conditions to be performed. The goal of these simulations would be directed toward expanding the performance envelope of NTR engines over that which was demonstrated during the Rover and NERVA nuclear rocket programs of the 1970's. Current planning calls for such a simulator to be constructed at the Marshall Space Flight Center over the coming year, and it is anticipated that it will be used in the future to evaluate a wide variety of fuel element designs and the materials of which they are constructed. This present work addresses the initial experimental objectives of the NTR simulator with regard to reproducing the fuel degradation patterns previously observed during the NERVA testing.

  14. Numerical analysis corresponding with experiment in compact beam simulator for heavy ion inertial fusion driver

    NASA Astrophysics Data System (ADS)

    Kikuchi, T.; Sakai, Y.; Komori, T.; Sato, T.; Hasegawa, J.; Horioka, K.; Takahashi, K.; Sasaki, T.; Harada, Nob

    2016-05-01

    Tune depression in a compact beam equipment is estimated, and numerical simulation results are compared with an experimental one for the compact beam simulator in a driver of heavy ion inertial fusion. The numerical simulation with multi-particle tracking is carried out, corresponding to the experimental condition, and the result is discussed with the experimental one. It is expected that the numerical simulation developed in this paper is useful tool to investigate the beam dynamics in the experiment with the compact beam simulator.

  15. ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES

    SciTech Connect

    Sampayan, S; Caporaso, G; Chen, Y; Carazo, V; Falabella, S; Guethlein, G; Guse, S; Harris, J R; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Paul, A C; Pearson, D; Poole, B; Schmidt, R; Sanders, D; Selenes, K; Sitaraman, S; Sullivan, J; Wang, L; Watson, J

    2009-06-11

    We report on compact accelerator technology development for potential use as a pulsed neutron source quantitative post verifier. The technology is derived from our on-going compact accelerator technology development program for radiography under the US Department of Energy and for a clinic sized compact proton therapy systems under an industry sponsored Cooperative Research and Development Agreement. The accelerator technique relies on the synchronous discharge of a prompt pulse generating stacked transmission line structure with the beam transit. The goal of this technology is to achieve {approx}10 MV/m gradients for 10s of nanoseconds pulses and to {approx}100 MV/m gradients for {approx}1 ns systems. As a post verifier for supplementing existing x-ray equipment, this system can remain in a charged, stand-by state with little or no energy consumption. We detail the progress of our overall component development effort with the multilayer dielectric wall insulators (i.e., the accelerator wall), compact power supply technology, kHz repetition-rate surface flashover ion sources, and the prompt pulse generation system consisting of wide-bandgap switches and high performance dielectric materials.

  16. Nuclear degraded sperm subpopulation is affected by poor chromatin compaction and nuclease activity.

    PubMed

    Ribas-Maynou, J; García-Peiró, A; Martínez-Heredia, J; Fernández-Encinas, A; Abad, C; Amengual, M J; Navarro, J; Benet, J

    2015-04-01

    There is an interest in the nuclear degraded sperm subpopulation because, although it is present in a low percentage in all semen samples, patient groups such as varicocele and rearranged genome carriers show high levels of these degraded spermatozoa. This study is designed with two objectives in mind: first, incubations of H2 O2 and nuclease on DTT-treated and untreated samples to show the aetiology of this subpopulation and second, assessment of the correlation between the protamine ratio and nuclear degraded spermatozoa. A very high increase in the nuclear degraded subpopulation has been found with nuclease incubation, and it is even higher when it has been merged with nuclear decompaction using DTT. Alternatively, incubation with H2 O2 with and without DTT did not show such a significant increase in nuclear degraded spermatozoa. The protamine ratio correlated with this subpopulation, showing, in patients, that poor nuclear compaction would turn the sperm susceptible to degradation. Then, the assessment of nuclear degraded spermatozoa might not be only a measure of DNA degradation but also an indicator of chromatin compaction in the spermatozoa. Different patient groups would fit this model for sperm nuclear degradation, such as varicocele patients, who show a high percentage of immature spermatozoa and nuclear degraded spermatozoa, and reorganised genome carriers, where reorganisation might also cause poor chromatin compaction on the sperm nucleus.

  17. The standard upwind compact difference schemes for incompressible flow simulations

    NASA Astrophysics Data System (ADS)

    Fan, Ping

    2016-10-01

    Compact difference schemes have been used extensively for solving the incompressible Navier-Stokes equations. However, the earlier formulations of the schemes are of central type (called central compact schemes, CCS), which are dispersive and susceptible to numerical instability. To enhance stability of CCS, the optimal upwind compact schemes (OUCS) are developed recently by adding high order dissipative terms to CCS. In this paper, it is found that OUCS are essentially not of the upwind type because they do not use upwind-biased but central type of stencils. Furthermore, OUCS are not the most optimal since orders of accuracy of OUCS are at least one order lower than the maximum achievable orders. New upwind compact schemes (called standard upwind compact schemes, SUCS) are developed in this paper. In contrast to OUCS, SUCS are constructed based completely on upwind-biased stencils and hence can gain adequate numerical dissipation with no need for introducing optimization calculations. Furthermore, SUCS can achieve the maximum achievable orders of accuracy and hence be more compact than OUCS. More importantly, SUCS have prominent advantages on combining the stable and high resolution properties which are demonstrated from the global spectral analyses and typical numerical experiments.

  18. Teaching About Nuclear Power: A Simulation.

    ERIC Educational Resources Information Center

    Maxey, Phyllis F.

    1980-01-01

    Recommends that simulation games be used to teach high school students in social studies courses about contemporary and controversial issues such as nuclear power. A simulation is described which involves students in deciding whether to build a nuclear power plant in the California desert. Teaching and debriefing tips are also provided. (DB)

  19. Three-dimensional simulations of nanopowder compaction processes by granular dynamics method

    NASA Astrophysics Data System (ADS)

    Boltachev, G. Sh.; Lukyashin, K. E.; Shitov, V. A.; Volkov, N. B.

    2013-07-01

    In order to describe and to study the processes of cold compaction within the discrete element method a three-dimensional model of nanosized powder is developed. The elastic forces of repulsion, the tangential forces of “friction” (Cattaneo-Mindlin), and the dispersion forces of attraction (van der Waals-Hamaker), as well as the formation and destruction of hard bonds between the individual particles are taken into account. The monosized powders with the size of particles in the range 10-40 nm are simulated. The simulation results are compared to the experimental data of the alumina nanopowders compaction. It is shown that the model allows us to reproduce experimental data reliably and, in particular, describes the size effect in the compaction processes. A number of different external loading conditions is used in order to perform the theoretical and experimental researches. The uniaxial compaction (the closed-die compaction), the biaxial (radial) compaction, and the isotropic compaction (the cold isostatic pressing) are studied. The real and computed results are in a good agreement with each other. They reveal a weak sensitivity of the oxide nanopowders to the loading condition (compaction geometry). The application of the continuum theory of the plastically hardening porous body, which is usually used for the description of powders, is discussed.

  20. A Novel Approach to Fabricating Fuel Compacts for the Next Generation Nuclear Plant (NGNP)

    SciTech Connect

    Pappano, Peter J; Burchell, Timothy D; Trammell, Michael P; Hunn, John D

    2008-01-01

    The next generation nuclear plant (NGNP) is a combined complex of a very high temperature reactor (VHTR) and hydrogen production facility. The VHTR can have a prismatic or pebble bed design and is powered by TRISO fuel in the form of a fuel compact (prismatic) or pebble (pebble bed). The US is scheduled to build a demonstration VHTR at the Idaho National Laboratory site by 2020. The first step toward building of this facility is development and qualification of the fuel for the reactor. This paper summarizes the research and development efforts performed at Oak Ridge National Laboratory (ORNL) toward development of a qualified fuel compact for a VHTR.

  1. A novel approach to fabricating fuel compacts for the next generation nuclear plant (NGNP)

    NASA Astrophysics Data System (ADS)

    Pappano, P. J.; Burchell, T. D.; Hunn, J. D.; Trammell, M. P.

    2008-10-01

    The next generation nuclear plant (NGNP) is a combined complex of a very high temperature reactor (VHTR) and hydrogen production facility. The VHTR can have a prismatic or pebble bed design and is powered by TRISO fuel in the form of a fuel compact (prismatic) or pebble (pebble bed). The US is scheduled to build a demonstration VHTR at the Idaho National Laboratory site by 2020. The first step toward building of this facility is development and qualification of the fuel for the reactor. This paper summarizes the research and development efforts performed at Oak Ridge National Laboratory (ORNL) toward development of a qualified fuel compact for a VHTR.

  2. A compact Gas Core Nuclear Rocket for space exploration

    NASA Astrophysics Data System (ADS)

    Kammash, Terry

    1993-06-01

    The open cycle Gas Core Nuclear Rocket (GCR) possesses, in principle, outstanding propulsion characteristics that make it especially attractive for advanced space propulsion. With uranium as fuel and hydrogen as propellant, it can generate several thousand seconds of specific impulse and hundreds of kilonewtons of thrust. In its standard configuration, however, GCR is susceptible to hydrodynamic and acoustic instabilities, which could lead to a significant loss of fuel and severe limitation on its propulsion capabilities. In this paper we examine the potential utilization of americium in place of uranium, and study the effect of such fuel change on the size reduction of the system as well as its impact on the hydrodynamic stability question. We find that the same propulsion performance can be achieved at a comparable fuel density but with a radial size reduction of both core and moderator/reflector of about 70 percent, and a corresponding stabilizing effect on the Kelvin-Helmholtz instability which lies at the heart of turbulent mixing in this device.

  3. Fuel Accident Condition Simulator (FACS) Furnace for Post-Irradiation Heating Tests of VHTR Fuel Compacts

    SciTech Connect

    Paul A Demkowicz; Paul Demkowicz; David V Laug

    2010-10-01

    Abstract –Fuel irradiation testing and post-irradiation examination are currently in progress as part of the Next Generation Nuclear Plant Fuels Development and Qualification Program. The PIE campaign will include extensive accident testing of irradiated very high temperature reactor fuel compacts to verify fission product retention characteristics at high temperatures. This work will be carried out at both the Idaho National Laboratory (INL) and the Oak Ridge National Laboratory, beginning with accident tests on irradiated fuel from the AGR-1 experiment in 2010. A new furnace system has been designed, built, and tested at INL to perform high temperature accident tests. The Fuel Accident Condition Simulator furnace system is designed to heat fuel specimens at temperatures up to 2000°C in helium while monitoring the release of volatile fission metals (e.g. Cs, Ag, Sr, Eu, and I) and fission gases (Kr, Xe). Fission gases released from the fuel to the sweep gas are monitored in real time using dual cryogenic traps fitted with high purity germanium detectors. Condensable fission products are collected on a plate attached to a water-cooled cold finger that can be exchanged periodically without interrupting the test. Analysis of fission products on the condensation plates involves dry gamma counting followed by chemical analysis of selected isotopes. This paper will describe design and operational details of the Fuel Accident Condition Simulator (FACS) furnace system, as well as preliminary system calibration results.

  4. Computational Challenges in Nuclear Weapons Simulation

    SciTech Connect

    McMillain, C F; Adams, T F; McCoy, M G; Christensen, R B; Pudliner, B S; Zika, M R; Brantley, P S; Vetter, J S; May, J M

    2003-08-29

    After a decade of experience, the Stockpile Stewardship Program continues to ensure the safety, security and reliability of the nation's nuclear weapons. The Advanced Simulation and Computing (ASCI) program was established to provide leading edge, high-end simulation capabilities needed to meet the program's assessment and certification requirements. The great challenge of this program lies in developing the tools and resources necessary for the complex, highly coupled, multi-physics calculations required to simulate nuclear weapons. This paper describes the hardware and software environment we have applied to fulfill our nuclear weapons responsibilities. It also presents the characteristics of our algorithms and codes, especially as they relate to supercomputing resource capabilities and requirements. It then addresses impediments to the development and application of nuclear weapon simulation software and hardware and concludes with a summary of observations and recommendations on an approach for working with industry and government agencies to address these impediments.

  5. Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael

    2009-01-01

    A detailed description of the Nuclear Thermal Rocket Element Environmental Simulator (NTREES) is presented. The contents include: 1) Design Requirements; 2) NTREES Layout; 3) Data Acquisition and Control System Schematics; 4) NTREES System Schematic; and 5) NTREES Setup.

  6. Beam dynamics analysis in pulse compression using electron beam compact simulator for Heavy Ion Fusion

    NASA Astrophysics Data System (ADS)

    Kikuchi, Takashi; Horioka, Kazuhiko; Sasaki, Toru; Harada, Nob.

    2013-11-01

    In a final stage of an accelerator system for heavy ion inertial fusion (HIF), pulse shaping and beam current increase by bunch compression are required for effective pellet implosion. A compact simulator with an electron beam was constructed to understand the beam dynamics. In this study, we investigate theoretically and numerically the beam dynamics for the extreme bunch compression in the final stage of HIF accelerator complex. The theoretical and numerical results implied that the compact experimental device simulates the beam dynamics around the stagnation point for initial low temperature condition.

  7. Formulation of Macroscale Compaction Dynamics based on Mesoscale Simulations of Uniaxial Waves in Granular Explosive

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Sunada; Gonthier, Keith A.

    2010-10-01

    A macroscale continuum theory for Deflagration-to-Detonation Transition (DDT) in granular explosive is generalized to account for the simultaneous existence of an arbitrary number of condensed phases. The theory assumes phase separation, and allows for flexible partitioning of dissipation between phases in a thermodynamically consistent manner. The constitutive theory is complex and requires descriptions for dissipation partition functions, relaxation rate functions, and phase-specific parameters that are not well-characterized, particularly for dynamic loading. A key focus of this study is to formulate expressions for phase-specific intergranular stresses and compaction potential energies based on mesoscale simulations of uniaxial compaction waves because of their importance to compaction induced heating and combustion. Predictions will be compared to quasi-static compaction data for granular HMX.

  8. Large Scale Quantum Simulations of Nuclear Pasta

    NASA Astrophysics Data System (ADS)

    Fattoyev, Farrukh J.; Horowitz, Charles J.; Schuetrumpf, Bastian

    2016-03-01

    Complex and exotic nuclear geometries collectively referred to as ``nuclear pasta'' are expected to naturally exist in the crust of neutron stars and in supernovae matter. Using a set of self-consistent microscopic nuclear energy density functionals we present the first results of large scale quantum simulations of pasta phases at baryon densities 0 . 03 < ρ < 0 . 10 fm-3, proton fractions 0 . 05 simulations, in particular, allow us to also study the role and impact of the nuclear symmetry energy on these pasta configurations. This work is supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  9. Modeling and Simulation of Nuclear Fuel Materials

    SciTech Connect

    Devanathan, Ram; Van Brutzel, Laurent; Tikare, Veena; Bartel, Timothy; Besmann, Theodore M; Stan, Marius; Van Uffelen, Paul

    2010-01-01

    We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios and small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

  10. Modeling and Simulation of Nuclear Fuel Materials

    SciTech Connect

    Devanathan, Ramaswami; Van Brutzel, Laurent; Chartier, Alan; Gueneau, Christine; Mattsson, Ann E.; Tikare, Veena; Bartel, Timothy; Besmann, T. M.; Stan, Marius; Van Uffelen, Paul

    2010-10-01

    We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios, and the small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

  11. Formation of compact clusters from high resolution hybrid cosmological simulations

    SciTech Connect

    Richardson, Mark L. A.; Scannapieco, Evan; Gray, William J.

    2013-11-20

    The early universe hosted a large population of small dark matter 'minihalos' that were too small to cool and form stars on their own. These existed as static objects around larger galaxies until acted upon by some outside influence. Outflows, which have been observed around a variety of galaxies, can provide this influence in such a way as to collapse, rather than disperse, the minihalo gas. Gray and Scannapieco performed an investigation in which idealized spherically symmetric minihalos were struck by enriched outflows. Here we perform high-resolution cosmological simulations that form realistic minihalos, which we then extract to perform a large suite of simulations of outflow-minihalo interactions including non-equilibrium chemical reactions. In all models, the shocked minihalo forms molecules through non-equilibrium reaction, and then cools to form dense, chemically homogenous clumps of star-forming gas. The formation of these high-redshift clusters may be observable with the next generation of telescopes and the largest of them should survive to the present-day, having properties similar to halo globular clusters.

  12. Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    SciTech Connect

    Emrich, William J. Jr.

    2008-01-21

    To support a potential future development of a nuclear thermal rocket engine, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The test device simulates the environmental conditions (minus the radiation) to which nuclear rocket fuel components could be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner as to accurately reproduce the temperatures and heat fluxes normally expected to occur as a result of nuclear fission while at the same time being exposed to flowing hydrogen. This project is referred to as the Nuclear Thermal Rocket Element Environment Simulator or NTREES. The NTREES device is located at the Marshall Space flight Center in a laboratory which has been modified to accommodate the high powers required to heat the test articles to the required temperatures and to handle the gaseous hydrogen flow required for the tests. Other modifications to the laboratory include the installation of a nitrogen gas supply system and a cooling water supply system. During the design and construction of the facility, every effort was made to comply with all pertinent regulations to provide assurance that the facility could be operated in a safe and efficient manner. The NTREES system can currently supply up to 50 kW of inductive heating to the fuel test articles, although the facility has been sized to eventually allow test article heating levels of up to several megawatts.

  13. Water migration through compacted bentonite backfills for containment of high-level nuclear waste

    SciTech Connect

    Westsik, J.H.; Hodges, F.N.; Kuhn, W.L.; Myers, T.R.

    1983-01-01

    Tests carried out with compacted sodium and calcium bentonites at room temperature indicate that bentonite backfills will effectively control water movement near a high-level nuclear waste package. Saturation tests indicate that water will rapidly diffuse into a dry bentonite backfill, reaching saturation in times on the order of tens of years. The apparent diffusion coefficient for sodium bentonite (about5 wt% initial water content) compacted to 2.1 g/cm/sup 3/ is 1.7 x 10/sup -6/ cm/sup 2//sec. However, the hydraulic conductivities of saturated bentonites are low, ranging from approximately 10/sup -11/ cm/sec to 10/sup -13/ cm/sec over a density range of 1.5 g/cm/sup 3/ to 2.2 g/cm/sup 3/. The hydraulic conductivities of compacted bentonites are at least several orders of magnitude lower than those of candidate-host silicate rocks, indicating that most flowing groundwater contacting a bentonite backfill would be diverted around the backfill rather than flowing through it. In addition, because of the very low hydraulic conductivities of bentonite backfills, the rate of chemical transport between the containerized waste and the surrounding host rock will be effectively controlled by diffusion through the backfill. The formation of a diffusion barrier by the backfill will significantly reduce the long-term rate of radionuclide release from the waste package, an advantage distinct from the delay in release resulting from the sorptive properties of a bentonite backfill.

  14. Discrete element simulation of powder compaction in cold uniaxial pressing with low pressure

    NASA Astrophysics Data System (ADS)

    Rojek, Jerzy; Nosewicz, Szymon; Jurczak, Kamila; Chmielewski, Marcin; Bochenek, Kamil; Pietrzak, Katarzyna

    2016-11-01

    This paper presents numerical studies of powder compaction in cold uniaxial pressing. The powder compaction in this work is considered as an initial stage of a hot pressing process so it is realized with relatively low pressure (up to 50 MPa). Hence the attention has been focused on the densification mechanisms at this range of pressure and models suitable for these conditions. The discrete element method employing spherical particles has been used in the numerical studies. Numerical simulations have been performed for two different contact models—the elastic Hertz-Mindlin-Deresiewicz model and the plastic Storåkers model. Numerical results have been compared with the results of laboratory tests of the die compaction of the NiAl powder. Comparisons have shown that the discrete element method is capable to represent properly the densification mechanisms by the particle rearrangement and particle deformation.

  15. Fully dynamical simulation of central nuclear collisions.

    PubMed

    van der Schee, Wilke; Romatschke, Paul; Pratt, Scott

    2013-11-27

    We present a fully dynamical simulation of central nuclear collisions around midrapidity at LHC energies. Unlike previous treatments, we simulate all phases of the collision, including the equilibration of the system. For the simulation, we use numerical relativity solutions to anti-de Sitter space/conformal field theory for the preequilibrium stage, viscous hydrodynamics for the plasma equilibrium stage, and kinetic theory for the low-density hadronic stage. Our preequilibrium stage provides initial conditions for hydrodynamics, resulting in sizable radial flow. The resulting light particle spectra reproduce the measurements from the ALICE experiment at all transverse momenta. PMID:24329444

  16. Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction.

    PubMed

    Sant'Anna-Junior, Arnaldo; Guerreiro-Tanomaru, Juliane Maria; Martelo, Roberta Bosso; Silva, Guilherme Ferreira da; Tanomaru Filho, Mário

    2015-01-01

    The aim of this study was to evaluate the ability of gutta-percha and a thermoplastic synthetic polymer (Resilon) to fill simulated lateral canals, using warm vertical compaction. Forty-five single-rooted human teeth were prepared using the rotary crown-down technique. Artificial lateral canals were made at 2, 5, and 8 mm from the working length (WL) in each root. The specimens were divided into three groups (n = 15), according to the filling material: Dentsply gutta-percha (GD), Odous gutta-percha (GO), and Resilon cones (RE). The root canals were obturated using warm vertical compaction, without endodontic sealer. The specimens were subjected to a tooth decalcification and clearing procedure. Filling of the lateral canals was analyzed by digital radiography and digital photographs, using the Image Tool software. The data were subjected to the Kruskal-Wallis and Dunn tests at 5% significance. RE had the best filling ability in all root thirds (p < 0.05), with similar results for GO in the coronal third. In the middle and apical thirds, GD and GO had similar results (p > 0.05). Resilon may be used as an alternative to gutta-percha as a solid core filling material for use with the warm vertical compaction technique. The study findings point to the potential benefit of the warm vertical compaction technique for filling lateral canals, and the study provides further information about using Resilon and gutta-percha as materials for the warm vertical compaction technique.

  17. Classical Molecular Dynamics Simulation of Nuclear Fuel

    SciTech Connect

    Devanathan, Ram; Krack, Matthias; Bertolus, Marjorie

    2015-10-10

    Molecular dynamics simulation is well suited to study primary damage production by irradiation, defect interactions with fission gas atoms, gas bubble nucleation, grain boundary effects on defect and gas bubble evolution in nuclear fuel, and the resulting changes in thermo-mechanical properties. In these simulations, the forces on the ions are dictated by interaction potentials generated by fitting properties of interest to experimental data. The results obtained from the present generation of potentials are qualitatively similar, but quantitatively different. There is a need to refine existing potentials to provide a better representation of the performance of polycrystalline fuel under a variety of operating conditions, and to develop models that are equipped to handle deviations from stoichiometry. In addition to providing insights into fundamental mechanisms governing the behaviour of nuclear fuel, MD simulations can also provide parameters that can be used as inputs for mesoscale models.

  18. Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.

    2008-01-01

    To support the eventual development of a nuclear thermal rocket engine, a state-of-the-art experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The test device simulates the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner as to accurately reproduce the temperatures and heat fluxes normally expected to occur as a result of nuclear fission while at the same time being exposed to flowing hydrogen. This project is referred to as the Nuclear Thermal Rocket Element Environment Simulator or NTREES. The NTREES device is located at the Marshall Space flight Center in a laboratory which has been modified to accommodate the high powers required to heat the test articles to the required temperatures and to handle the gaseous hydrogen flow required for the tests. Other modifications to the laboratory include the installation of a nitrogen gas supply system and a cooling water supply system. During the design and construction of the facility, every effort was made to comply with all pertinent regulations to provide assurance that the facility could be operated in a safe and efficient manner. The NTREES system can currently supply up to 50 kW of inductive heating to the fuel test articles, although the facility has been sized to eventually allow test article heating levels of up to several megawatts.

  19. Simulation of Aluminum Powder in Tube Compaction Using Equal Channel Angular Extrusion

    NASA Astrophysics Data System (ADS)

    Haghighi, Reza Derakhshandeh; Jahromi, Ahmad Jenabali; Jahromi, Behnam Esfandiar

    2012-02-01

    Aluminum powder in tube compaction with a 25 mm front plug through equal channel angular extrusion (ECAE) at room temperature was modeled using the finite element analysis package ABAQUS. The Gurson model was used in modeling this process. 2-D simulations in a 90° angle die showed better consolidation of powder near the inner edge of the die than the outer edge after one pass of ECAE but almost full densification occurs after two passes. The effect of hydrostatic pressure on densification of the powder was investigated by using two plugs varying in length dimension. The results obtained from the simulations were also compared with experiments conducted to compact aluminum powder with mean particle diameter of 45 μm. Optical microscopy, microhardness test, and density measurements confirmed the simulations. The simulations were extended to powder compaction in a 60° and 120° angle die. It was found that one pass of ECAE is sufficient to consolidate the aluminum powder completely and uniformly in a 60° angle die, whereas the material is still porous in a 120° angle die.

  20. Fast surrogate-assisted simulation-driven optimization of compact microwave hybrid couplers

    NASA Astrophysics Data System (ADS)

    Kurgan, Piotr; Koziel, Slawomir

    2016-07-01

    This work presents a robust methodology for expedited simulation-driven design optimization of compact microwave hybrid couplers. The technique relies on problem decomposition, and a bottom-up design strategy, starting from the level of basic building blocks of the coupler, and finishing with a tuning procedure that exploits a fast surrogate model of the entire structure. The latter is constructed by cascading local response surface approximations of coupler elementary elements. The cross-coupling effects within the structure are neglected in the first stage of the design process; however, they are accounted for in the tuning phase by means of space-mapping correction of the surrogate. The proposed approach is demonstrated through the design of a compact rat-race and two branch-line couplers. In all cases, the computational cost of the optimization process is very low and corresponds to just a few high-fidelity electromagnetic simulations of respective structures. Experimental validation is also provided.

  1. The diverse evolutionary paths of simulated high-z massive, compact galaxies to z = 0

    NASA Astrophysics Data System (ADS)

    Wellons, Sarah; Torrey, Paul; Ma, Chung-Pei; Rodriguez-Gomez, Vicente; Pillepich, Annalisa; Nelson, Dylan; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

    2016-02-01

    Massive quiescent galaxies have much smaller physical sizes at high redshift than today. The strong evolution of galaxy size may be caused by progenitor bias, major and minor mergers, adiabatic expansion, and/or renewed star formation, but it is difficult to test these theories observationally. Herein, we select a sample of 35 massive, compact galaxies (M* = 1-3 × 1011 M⊙, M*/R1.5 > 1010.5 M⊙/kpc1.5) at z = 2 in the cosmological hydrodynamical simulation Illustris and trace them forwards to z = 0 to uncover their evolution and identify their descendants. By z = 0, the original factor of 3 difference in stellar mass spreads to a factor of 20. The dark matter halo masses similarly spread from a factor of 5 to 40. The galaxies' evolutionary paths are diverse: about half acquire an ex situ envelope and are the core of a more massive descendant, a third survive undisturbed and gain very little mass, 15 per cent are consumed in a merger with a more massive galaxy, and a small remainder are thoroughly mixed by major mergers. The galaxies grow in size as well as mass, and only ˜10 per cent remain compact by z = 0. The majority of the size growth is driven by the acquisition of ex situ mass. The most massive galaxies at z = 0 are the most likely to have compact progenitors, but this trend possesses significant dispersion which precludes a direct linkage to compact galaxies at z = 2. The compact galaxies' merger rates are influenced by their z = 2 environments, so that isolated or satellite compact galaxies (which are protected from mergers) are the most likely to survive to the present day.

  2. Designing a compact high performance brain PET scanner-simulation study.

    PubMed

    Gong, Kuang; Majewski, Stan; Kinahan, Paul E; Harrison, Robert L; Elston, Brian F; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V; Brefczynski-Lewis, Julie A; Qi, Jinyi

    2016-05-21

    The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér-Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact 'helmet' design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging. PMID

  3. Designing a compact high performance brain PET scanner—simulation study

    NASA Astrophysics Data System (ADS)

    Gong, Kuang; Majewski, Stan; Kinahan, Paul E.; Harrison, Robert L.; Elston, Brian F.; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V.; Brefczynski-Lewis, Julie A.; Qi, Jinyi

    2016-05-01

    The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér–Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact ‘helmet’ design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging.

  4. Designing a compact high performance brain PET scanner—simulation study

    NASA Astrophysics Data System (ADS)

    Gong, Kuang; Majewski, Stan; Kinahan, Paul E.; Harrison, Robert L.; Elston, Brian F.; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V.; Brefczynski-Lewis, Julie A.; Qi, Jinyi

    2016-05-01

    The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér-Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact ‘helmet’ design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging.

  5. Simulation of a marine nuclear reactor

    SciTech Connect

    Kusunoki, Tsuyoshi; Kyouya, Masahiko; Kobayashi, Hideo; Ochiai, Masaaki

    1995-02-01

    A Nuclear-powered ship Engineering Simulation SYstem (NESSY) has been developed by the Japan Atomic Energy Research Institute as an advanced design tool for research and development of future marine reactors. A marine reactor must respond to changing loads and to the ship`s motions because of the ship`s maneuvering and its presence in a marine environment. The NESSY has combined programs for the reactor plant behavior calculations and the ship`s motion calculations. Thus, it can simulate reactor power fluctuations caused by changing loads and the ship`s motions. It can also simulate the behavior of water in the pressurizer and steam generators. This water sloshes in response to the ship`s motions. The performance of NESSY has been verified by comparing the simulation calculations with the measured data obtained by experiments performed using the nuclear ship Mutsu. The effects of changing loads and the ship`s motions on the reactor behavior can be accurately simulated by NESSY.

  6. The spiral-compact galaxy pair AM 2208-251: Computer simulations versus observations

    NASA Astrophysics Data System (ADS)

    Klaric, Mario; Byrd, Gene G.

    1990-11-01

    The system AM2208-251 is a roughly edge-on spiral extending east-west with a smaller round compact E system about 60 arcsec east of the spiral nucleus along the major axis of the spiral. Bertola, Huchtmeier, and Zeilinger (1990) have presented optical spectroscopic as well as single dish 21 cm observations of this system. Their spectroscopic data show, via emission lines lambda lambda 3727-29A, a rising rotation curve near the nucleus. These spectroscopic observations may indicate a tidal interaction in the system. In order to learn more about such pairs, the authors simulated the interaction using the computer model developed by Miller (1976 a,b, 1978) and modified by the authors (Byrd 1986, 1987, 1988). To do the simulation they need an idea of the mutual orbits of the two galaxies. Their computer model is a two-dimensional polar N-body program. It consists of a self-gravitating disk of particles, within an inert axially symmetric stabilizing halo potential. The particles are distributed in a 24(radial) by 36(azimuthal) polar grid. Self consistent calculations can be done only within the grid area. The disk is modeled with a finite Mestel disk, where all the particles initially move in circular orbits with constant tangential velocities (Mestel 1963), resulting in a flat rotation curve. The gas particles in the spiral's disk, which make up 30 percent of its mass, collide in the following manner. The number of particles in each bin of the polar grid is counted every time step. If it is greater than a given critical density, all the particles in the bin collide, obtaining in the result the same velocities, equal to the average for the bin. This process produces clumps of gas particles-the star formation sites. The authors suppress the collision in the inner part of the disk (within the circle r = 6) to represent the hole seen in the gas in the nuclear bulge of spirals. They thus avoid spurious effects due to collisions in that region. They also varied the size of

  7. The spiral-compact galaxy pair AM 2208-251: Computer simulations versus observations

    NASA Technical Reports Server (NTRS)

    Klaric, Mario; Byrd, Gene G.

    1990-01-01

    The system AM2208-251 is a roughly edge-on spiral extending east-west with a smaller round compact E system about 60 arcsec east of the spiral nucleus along the major axis of the spiral. Bertola, Huchtmeier, and Zeilinger (1990) have presented optical spectroscopic as well as single dish 21 cm observations of this system. Their spectroscopic data show, via emission lines lambda lambda 3727-29A, a rising rotation curve near the nucleus. These spectroscopic observations may indicate a tidal interaction in the system. In order to learn more about such pairs, the authors simulated the interaction using the computer model developed by Miller (1976 a,b, 1978) and modified by the authors (Byrd 1986, 1987, 1988). To do the simulation they need an idea of the mutual orbits of the two galaxies. Their computer model is a two-dimensional polar N-body program. It consists of a self-gravitating disk of particles, within an inert axially symmetric stabilizing halo potential. The particles are distributed in a 24(radial) by 36(azimuthal) polar grid. Self consistent calculations can be done only within the grid area. The disk is modeled with a finite Mestel disk, where all the particles initially move in circular orbits with constant tangential velocities (Mestel 1963), resulting in a flat rotation curve. The gas particles in the spiral's disk, which make up 30 percent of its mass, collide in the following manner. The number of particles in each bin of the polar grid is counted every time step. If it is greater than a given critical density, all the particles in the bin collide, obtaining in the result the same velocities, equal to the average for the bin. This process produces clumps of gas particles-the star formation sites. The authors suppress the collision in the inner part of the disk (within the circle r = 6) to represent the hole seen in the gas in the nuclear bulge of spirals. They thus avoid spurious effects due to collisions in that region. They also varied the size of

  8. The role of compact PSPMTs for image quality enhancement in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Cinti, M. N.; Pani, R.; Pellegrini, R.; Garibaldi, F.; Cusanno, F.; Campanini, R.; Lanconelli, N.; Riccardi, A.; Zavattini, G.; Di Domenico, G.; Belcari, N.; Bencivelli, W.; Motta, Alfonso; Vaiano, Angela; Del Guerra, A.

    2003-06-01

    Compact gamma cameras based on arrays of compact Position Sensitive Photomultipliers (PSPMTs) (Hamamatsu R7600-C8/12) were recently developed by several research groups. The previous generation of dedicated gamma cameras (5 in. PSPMT) demonstrated the clinical benefit and general diagnostic value for functional breast imaging in comparison with conventional nuclear medicine technique (Anger Camera prone scintimammography and 99mTc Sestamibi administration). The aim of this paper is to investigate how scintillation material and pixel size of crystal arrays can improve image contrast and tumor SNR values. In this paper we compare tumor Signal-to-Noise Ratio (SNR) results obtained by imagers based on CsI(Tl) and NaI(Tl) array, respectively, by means of a liquid and solid breast phantom. The data collected by NaI(Tl) array show a improvement of SNR values for small tumor size (less than 8 mm). The improvement is also evident in small camera, even though for tumor size less than 6 mm the results are near visibility limit.

  9. A compact breed and burn fast reactor using spent nuclear fuel blanket

    SciTech Connect

    Hartanto, D.; Kim, Y.

    2012-07-01

    A long-life breed-and-burn (B and B) type fast reactor has been investigated from the neutronics points of view. The B and B reactor has the capability to breed the fissile fuels and use the bred fuel in situ in the same reactor. In this work, feasibility of a compact sodium-cooled B and B fast reactor using spent nuclear fuel as blanket material has been studied. In order to derive a compact B and B fast reactor, a tight fuel lattice and relatively large fuel pin are used to achieve high fuel volume fraction. The core is initially loaded with an LEU (Low Enriched Uranium) fuel and a metallic fuel is used in the core. The Monte Carlo depletion has been performed for the core to see the long-term behavior of the B and B reactor. Several important parameters such as reactivity coefficients, delayed neutron fraction, prompt neutron generation lifetime, fission power, and fast neutron fluence, are analyzed through Monte Carlo reactor analysis. Evolution of the core fuel composition is also analyzed as a function of burnup. Although the long-life small B and B fast reactor is found to be feasible from the neutronics point of view, it is characterized to have several challenging technical issues including a very high fast neutron fluence of the structural materials. (authors)

  10. Compact quasi-monoenergetic photon sources from laser-plasma accelerators for nuclear detection and characterization

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron G. R.; Rykovanov, Sergey; Matlis, Nicholas H.; Steinke, Sven; Vay, Jean-Luc; Esarey, Eric H.; Ludewigt, Bernhard; Nakamura, Kei; Quiter, Brian J.; Schroeder, Carl B.; Toth, Csaba; Leemans, Wim P.

    2015-05-01

    Near-monoenergetic photon sources at MeV energies offer improved sensitivity at greatly reduced dose for active interrogation, and new capabilities in treaty verification, nondestructive assay of spent nuclear fuel and emergency response. Thomson (also referred to as Compton) scattering sources are an established method to produce appropriate photon beams. Applications are however restricted by the size of the required high-energy electron linac, scattering (photon production) system, and shielding for disposal of the high energy electron beam. Laser-plasma accelerators (LPAs) produce GeV electron beams in centimeters, using the plasma wave driven by the radiation pressure of an intense laser. Recent LPA experiments are presented which have greatly improved beam quality and efficiency, rendering them appropriate for compact high-quality photon sources based on Thomson scattering. Designs for MeV photon sources utilizing the unique properties of LPAs are presented. It is shown that control of the scattering laser, including plasma guiding, can increase photon production efficiency. This reduces scattering laser size and/or electron beam current requirements to scale compatible with the LPA. Lastly, the plasma structure can decelerate the electron beam after photon production, reducing the size of shielding required for beam disposal. Together, these techniques provide a path to a compact photon source system.

  11. ELECTROMAGNETIC AND THERMAL SIMULATIONS FOR THE SWITCH REGION OF A COMPACT PROTON ACCELERATOR

    SciTech Connect

    Wang, L; Caporaso, G J; Sullivan, J S

    2007-06-15

    A compact proton accelerator for medical applications is being developed at Lawrence Livermore National Laboratory. The accelerator architecture is based on the dielectric wall accelerator (DWA) concept. One critical area to consider is the switch region. Electric field simulations and thermal calculations of the switch area were performed to help determine the operating limits of rmed SiC switches. Different geometries were considered for the field simulation including the shape of the thin Indium solder meniscus between the electrodes and SiC. Electric field simulations were also utilized to demonstrate how the field stress could be reduced. Both transient and steady steady-state thermal simulations were analyzed to find the average power capability of the switches.

  12. Simulating compact quantum electrodynamics with ultracold atoms: probing confinement and nonperturbative effects.

    PubMed

    Zohar, Erez; Cirac, J Ignacio; Reznik, Benni

    2012-09-21

    Recently, there has been much interest in simulating quantum field theory effects of matter and gauge fields. In a recent work, a method for simulating compact quantum electrodynamics (CQED) using Bose-Einstein condensates has been suggested. We suggest an alternative approach, which relies on single atoms in an optical lattice, carrying 2l + 1 internal levels, which converges rapidly to CQED as l increases. That enables the simulation of CQED in 2 + 1 dimensions in both the weak and the strong coupling regimes, hence, allowing us to probe confinement as well as other nonperturbative effects of the theory. We provide an explicit construction for the case l = 1 which is sufficient for simulating the effect of confinement between two external static charges.

  13. Comparative analysis of compact heat exchangers for application as the intermediate heat exchanger for advanced nuclear reactors

    SciTech Connect

    Bartel, N.; Chen, M.; Utgikar, V. P.; Sun, X.; Kim, I. -H.; Christensen, R.; Sabharwall, P.

    2015-04-04

    A comparative evaluation of alternative compact heat exchanger designs for use as the intermediate heat exchanger in advanced nuclear reactor systems is presented in this article. Candidate heat exchangers investigated included the Printed circuit heat exchanger (PCHE) and offset strip-fin heat exchanger (OSFHE). Both these heat exchangers offer high surface area to volume ratio (a measure of compactness [m2/m3]), high thermal effectiveness, and overall low pressure drop. Helium–helium heat exchanger designs for different heat exchanger types were developed for a 600 MW thermal advanced nuclear reactor. The wavy channel PCHE with a 15° pitch angle was found to offer optimum combination of heat transfer coefficient, compactness and pressure drop as compared to other alternatives. The principles of the comparative analysis presented here will be useful for heat exchanger evaluations in other applications as well.

  14. Comparative analysis of compact heat exchangers for application as the intermediate heat exchanger for advanced nuclear reactors

    DOE PAGES

    Bartel, N.; Chen, M.; Utgikar, V. P.; Sun, X.; Kim, I. -H.; Christensen, R.; Sabharwall, P.

    2015-04-04

    A comparative evaluation of alternative compact heat exchanger designs for use as the intermediate heat exchanger in advanced nuclear reactor systems is presented in this article. Candidate heat exchangers investigated included the Printed circuit heat exchanger (PCHE) and offset strip-fin heat exchanger (OSFHE). Both these heat exchangers offer high surface area to volume ratio (a measure of compactness [m2/m3]), high thermal effectiveness, and overall low pressure drop. Helium–helium heat exchanger designs for different heat exchanger types were developed for a 600 MW thermal advanced nuclear reactor. The wavy channel PCHE with a 15° pitch angle was found to offer optimummore » combination of heat transfer coefficient, compactness and pressure drop as compared to other alternatives. The principles of the comparative analysis presented here will be useful for heat exchanger evaluations in other applications as well.« less

  15. Diagenetic compaction of simulated anhydrite fault gouge under static conditions and implications for fault healing behaviour

    NASA Astrophysics Data System (ADS)

    Pluymakers, A.; Peach, C. J.; Spiers, C. J.

    2013-12-01

    For geological storage of CO2 in depleted oil and gas reservoirs to be effective, the stored gas must remain isolated from the atmosphere for thousands of years. Faults that cut the reservoir/seal system are considered one of the most likely leakage pathways, especially if fault reactivation leads to fault dilation. However, when fault movement ceases, newly formed fault gouge will heal as a function of time. To estimate the time scale on which such healing occurs, an understanding of the deformation mechanisms that control fault (gouge) compaction is needed. Anhydrite is a common caprock in many oil and gas fields around the world and in the Netherlands in particular, where anhydrite-capped reservoirs present several options for CO2 storage. For this reason, we performed uniaxial compaction experiments on simulated anhydrite fault gouge to investigate the deformation and healing processes that operate under simulated post-slip conditions, i.e. static conditions. The gouge was prepared by crushing and sieving nearly pure anhydrite (>95wt%) derived from exploration boreholes in the north of the Netherlands. Constant stress (5-12 MPa) and stress stepping experiments (5/7.5/10 MPa) were conducted at 80°C on fault gouge samples of different initial grain size (20-500μm), under both wet and dry conditions. We also performed preliminary experiments to determine the effect of CO2 on the healing behaviour of anhydrite gouge. Dry samples showed little or no compaction creep, whereas wet samples (i.e. samples flooded with saturated CaSO4 solution) showed compaction at easily measureable rates. In the case of wet samples, our mechanical data and microstructural observations showed that, for fine grain sizes and low stresses, the rate of gouge compaction is controlled by pressure solution under diffusion-control. With increasing grain size and stress, however, fluid-assisted subcritical microcracking becomes the dominant deformation mechanism. Pressurizing the pore fluid

  16. Compact Short-Pulsed Electron Linac Based Neutron Sources for Precise Nuclear Material Analysis

    NASA Astrophysics Data System (ADS)

    Uesaka, M.; Tagi, K.; Matsuyama, D.; Fujiwara, T.; Dobashi, K.; Yamamoto, M.; Harada, H.

    2015-10-01

    An X-band (11.424GHz) electron linac as a neutron source for nuclear data study for the melted fuel debris analysis and nuclear security in Fukushima is under development. Originally we developed the linac for Compton scattering X-ray source. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, etc., especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to modify and install the linac in the core space of the experimental nuclear reactor "Yayoi" which is now under the decommission procedure. Due to the compactness of the X-band linac, an electron gun, accelerating tube and other components can be installed in a small space in the core. First we plan to perform the time-of-flight (TOF) transmission measurement for study of total cross sections of the nuclei for 0.1-10 eV energy neutrons. Therefore, if we adopt a TOF line of less than 10m, the o-pulse length of generated neutrons should be shorter than 100 ns. Electronenergy, o-pulse length, power, and neutron yield are ~30 MeV, 100 ns - 1 micros, ~0.4 kW, and ~1011 n/s (~103 n/cm2/s at samples), respectively. Optimization of the design of a neutron target (Ta, W, 238U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. We are upgrading the electron gun and a buncher to realize higher current and beam power with a reasonable beam size in order to avoid damage of the neutron target. Although the neutron flux is limited in case of the X-band electron linac based source, we take advantage of its short pulse aspect and availability for nuclear data measurement with a short TOF system. First, we form a tentative configuration in the current experimental room for Compton scattering in 2014. Then, after the decommissioning has been finished, we move it to the "Yayoi" room and perform

  17. SUSEE: A Compact, Lightweight Space Nuclear Power System Using Present Water Reactor Technology

    SciTech Connect

    Maise, George; Powell, James; Paniagua, John

    2006-01-20

    The SUSEE space reactor system uses existing nuclear fuels and the standard steam cycle to generate electrical and thermal power for a wide range of in-space and surface applications, including manned bases, sub-surface mobile probes to explore thick ice deposits on Mars and the Jovian moons, and mobile rovers. SUSEE cycle efficiency, thermal to electric, ranges from {approx}20 to 24%, depending on operating parameters. Rejection of waste heat is by a lightweight condensing radiator that can be launched as a compact rolled-up package and deployed into flat panels when appropriate. The 50 centimeter diameter SUSEE reactor can provide power over the range of 10 kW(e) to 1 MW(e) for a period of 10 years. Higher power outputs are possible using slightly larger reactors. System specific weight (reactor, turbine, generator, piping, and radiator) is {approx}3 kg/kW(e). Two SUSEE reactor options are described, based on the existing Zr/O2 cermet and the UH3/ZrH2 TRIGA nuclear fuels.

  18. Effect of the Compaction and the Size of DNA on the Nuclear Transfer Efficiency after Microinjection in Synchronized Cells

    PubMed Central

    Akita, Hidetaka; Kurihara, Dai; Schmeer, Marco; Schleef, Martin; Harashima, Hideyoshi

    2015-01-01

    The nuclear transfer process is one of the critical rate-limiting processes in transgene expression. In the present study, we report on the effect of compaction and the size of the DNA molecule on nuclear transfer efficiency by microinjection. A DNA/protamine complex- or variously-sized naked DNA molecules were injected into the cytoplasm or nucleus of synchronized HeLa cells. To evaluate the nuclear transfer process, a nuclear transfer score (NT score), calculated based on transgene expression after cytoplasmic microinjection divided by that after nuclear microinjection, was employed. The compaction of DNA with protamine decreased the NT score in comparison with the injection of naked DNA when the N/P ratio was increased to >2.0. Moreover, when naked DNA was microinjected, gene expression increased in parallel with the size of the DNA in the following order: minicircle DNA (MC07.CMV-EGFP; 2257 bp) > middle-sized plasmid DNA (pBS-EGFP; 3992 bp) > conventional plasmid DNA (pcDNA3.1-EGFP; 6172 bp), while the level of gene expression was quite comparable among them when the DNAs were injected into the nucleus. The above findings suggest that the intrinsic size of the DNA molecule is a major determinant for nuclear entry and that minicircle DNA has a great advantage in nuclear transfer. PMID:26066769

  19. Reservoir simulation in a North Sea reservoir experiencing significant compaction drive

    SciTech Connect

    Cook, C.C.; Jewell, S.

    1995-12-31

    The Valhall field in the Norwegian North Sea is a high porosity chalk reservoir undergoing primary pressure depletion. Over the last ten years there have been a number of computer modeling studies of the field which have all assumed an original oil-in-place of approximately 2,000 MMSTB (318.0{times}10{sup 6}m{sup 3}) to the present due to the addition of wells and the optimization of completion techniques. However, the single most important and unique feature influencing Valhall long term production performance is reservoir rock compaction. This paper describes the mathematical model used to simulate reservoir performance in a compacting reservoir with specific discussion regarding the proportion of oil produced by each physical recovery process. An understanding of the recovery mechanisms and their relative importance is critical for the successful management of the field. This paper also presents an alternative method for evaluating the various recovery processes using a simple solution to the material balance equation. This is used to substantiate the magnitude of the various recovery mechanisms identified in the simulation model.

  20. Compact, high-power nuclear reactor systems based on small diameter particulate fuel

    NASA Astrophysics Data System (ADS)

    Powell, J. R.; Botts, T. E.

    Two compact, high-power nuclear reactor concepts are discussed. Both are gas-cooled cavity-type reactors which utilize particulate fuel of the type now used in HTGR reactors. Unshielded reactor volumes are on the order of one cubic meter. The Fixed Bed Reactor operating temperature is limited to 2500 K and the output power to 250 MW(e). In the Rotating Bed Reactor fuel is held within a rotating porous metal drum as a rotating fluidized bed. Rotating Bed Reactor outlet temperatures up to 3000 K and output power levels up to 1000 MW(e) are achievable. Both reactors can be brought up from stand by to full power in times on the order of a few seconds, due primarily to the short thermal time constant for the fuel particles. Turbine and MHD Brayton are the power conversion cycles of choice. Open cycle operation is generally favored for applications operating at less than 1000 sec of equivalent integrated full power. At power levels above 1 MW(e), the liquid droplet radiator is the favored means of heat rejection. Power system specific power levels of 10 kW(e)/kg (not including shield) appears to be quite feasible.

  1. ARC: A compact, high-field, disassemblable fusion nuclear science facility and demonstration power plant

    NASA Astrophysics Data System (ADS)

    Sorbom, Brandon; Ball, Justin; Palmer, Timothy; Mangiarotti, Franco; Sierchio, Jennifer; Bonoli, Paul; Kasten, Cale; Sutherland, Derek; Barnard, Harold; Haakonsen, Christian; Goh, Jon; Sung, Choongki; Whyte, Dennis

    2014-10-01

    The Affordable, Robust, Compact (ARC) reactor conceptual design aims to reduce the size, cost, and complexity of a combined Fusion Nuclear Science Facility (FNSF) and demonstration fusion pilot power plant. ARC is a 270 MWe tokamak reactor with a major radius of 3.3 m, a minor radius of 1.1 m, and an on-axis magnetic field of 9.2 T. ARC has Rare Earth Barium Copper Oxide (REBCO) superconducting toroidal field coils with joints to allow disassembly, allowing for removal and replacement of the vacuum vessel as a single component. Inboard-launched current drive of 25 MW LHRF power and 13.6 MW ICRF power is used to provide a robust, steady state core plasma far from disruptive limits. ARC uses an all-liquid blanket, consisting of low pressure, slowly flowing Fluorine Lithium Beryllium (FLiBe) molten salt. The liquid blanket acts as a working fluid, coolant, and tritium breeder, and minimizes the solid material that can become activated. The large temperature range over which FLiBe is liquid permits blanket operation at 800-900 K with single phase fluid cooling and allows use of a high-efficiency Brayton cycle for electricity production in the secondary coolant loop.

  2. Investigating runoff generation on compacted subsoil using a field rainfall simulator

    NASA Astrophysics Data System (ADS)

    Strouhal, Luděk; Zumr, David; Kavka, Petr

    2016-04-01

    Identifying and understanding the dominant runoff processes is vital for both hydrologic and soil erosion research and modelling. Although lateral subsurface stormflow and consecutive topsoil saturation are well known to be rather frequent, majority of the models still favour Hortonian runoff. Such results, especially on sloping arable land with compacted subsoil, often leads to incorrect conclusions. Within this contribution we present the results of field rainfall simulations at the experimental field in Bykovicky stream catchment and numerical simulations that quantitatively evaluate the effect of the subsurface runoff. At CTU in Prague a field rainfall simulator covering 16 m2 experimental plots has been used for erosion and hydrologic research since 2012. As the compacted subsoil layer was identified during the early experiments, the setup was extended to monitor also the shallow subsurface flow. Eight sprinkling experiments of various rainfall intensities and durations ranging from 23 to 162 mm/hour and 60 to 155 minutes respectively were conducted under various topsoil and vegetation conditions. The subsurface flow, surface runoff and soil moisture in three depths were monitored. While surface runoff did not form at lower intensities, subsurface flow was observed in every simulation and started quickly, in average 20-30 minutes after the start of the rainfall. The subsurface runoff made up a third or more of the total runoff, depending on rainfall intensity and duration. Selected scenarios were numerically modelled. Both experimental and model results support the conceptual model of runoff formation on this particular site and suggest the need of considering the lateral flow also on similar locations. This research has been supported by the research grants GP13-20388P, SGS14/180/OHK1/3T/11 and QJ1520265.

  3. Variations of the ISM Compactness Across the Main Sequence of Star Forming Galaxies: Observations and Simulations

    NASA Astrophysics Data System (ADS)

    Martínez-Galarza, J. R.; Smith, H. A.; Lanz, L.; Hayward, Christopher C.; Zezas, A.; Rosenthal, L.; Weiner, A.; Hung, C.; Ashby, M. L. N.; Groves, B.

    2016-01-01

    The majority of star-forming galaxies follow a simple empirical correlation in the star formation rate (SFR) versus stellar mass (M*) plane, of the form {{SFR}}\\propto {M}*α , usually referred to as the star formation main sequence (MS). The physics that sets the properties of the MS is currently a subject of debate, and no consensus has been reached regarding the fundamental difference between members of the sequence and its outliers. Here we combine a set of hydro-dynamical simulations of interacting galactic disks with state-of-the-art radiative transfer codes to analyze how the evolution of mergers is reflected upon the properties of the MS. We present Chiburst, a Markov Chain Monte Carlo spectral energy distribution (SED) code that fits the multi-wavelength, broad-band photometry of galaxies and derives stellar masses, SFRs, and geometrical properties of the dust distribution. We apply this tool to the SEDs of simulated mergers and compare the derived results with the reference output from the simulations. Our results indicate that changes in the SEDs of mergers as they approach coalescence and depart from the MS are related to an evolution of dust geometry in scales larger than a few hundred parsecs. This is reflected in a correlation between the specific star formation rate, and the compactness parameter { C }, that parametrizes this geometry and hence the evolution of dust temperature ({T}{{dust}}) with time. As mergers approach coalescence, they depart from the MS and increase their compactness, which implies that moderate outliers of the MS are consistent with late-type mergers. By further applying our method to real observations of luminous infrared galaxies (LIRGs), we show that the merger scenario is unable to explain these extreme outliers of the MS. Only by significantly increasing the gas fraction in the simulations are we able to reproduce the SEDs of LIRGs.

  4. Sea level static calibration of a compact multimission aircraft propulsion simulator with inlet flow distortion

    NASA Technical Reports Server (NTRS)

    Won, Mark J.

    1990-01-01

    Wind tunnel tests of propulsion-integrated aircraft models have identified inlet flow distortion as a major source of compressor airflow measurement error in turbine-powered propulsion simulators. Consequently, two Compact Multimission Aircraft Propulsion Simulator (CMAPS) units were statically tested at sea level ambient conditions to establish simulator operating performance characteristics and to calibrate the compressor airflow against an accurate bellmouth flowmeter in the presence of inlet flow distortions. The distortions were generated using various-shaped wire mesh screens placed upstream of the compressor. CMAPS operating maps and performance envelopes were obtained for inlet total pressure distortions (ratio of the difference between the maximum and minimum total pressures to the average total pressure) up to 35 percent, and were compared to baseline simulator operating characteristics for a uniform inlet. Deviations from CMAPS baseline performance were attributed to the coupled variation of both compressor inlet-flow distortion and Reynolds number index throughout the simulator operating envelope for each screen configuration. Four independent methods were used to determine CMAPS compressor airflow; direct compressor inlet and discharge measurements, an entering/exiting flow-balance relationships, and a correlation between the mixer pressure and the corrected compressor airflow. Of the four methods, the last yielded the least scatter in the compressor flow coefficient, approximately + or - 3 percent over the range of flow distortions.

  5. Electric heater for nuclear fuel rod simulators

    SciTech Connect

    Dial, R.E.; Mcculloch, R.W.; Morgan, C.S.

    1982-04-20

    The present invention is directed to an electric cartridge-type heater for use as a simulator for a nuclear fuel pin in reactor studies. The heater comprises an elongated cylindrical housing containing a longitudinally extending helically wound heating element with the heating element radially inwardly separated from the housing. Crushed cold-pressed preforms of boron nitride electrically insulate the heating element from the housing while providing good thermal conductivity. Crushed cold-pressed preforms of magnesia or a magnesia-15 percent boron nitride mixture are disposed in the cavity of the helical heating element. The coefficient of thermal expansion of the magnesia or the magnesia-boron nitride mixture is higher than that of the boron nitride disposed about the heating element for urging the boron nitride radially outwardly against the housing during elevated temperatures to assure adequate thermal contact between the housing and the boron nitride.

  6. Electric heater for nuclear fuel rod simulators

    DOEpatents

    McCulloch, Reginald W.; Morgan, Jr., Chester S.; Dial, Ralph E.

    1982-01-01

    The present invention is directed to an electric cartridge-type heater for use as a simulator for a nuclear fuel pin in reactor studies. The heater comprises an elongated cylindrical housing containing a longitudinally extending helically wound heating element with the heating element radially inwardly separated from the housing. Crushed cold-pressed preforms of boron nitride electrically insulate the heating element from the housing while providing good thermal conductivity. Crushed cold-pressed preforms of magnesia or a magnesia-15 percent boron nitride mixture are disposed in the cavity of the helical heating element. The coefficient of thermal expansion of the magnesia or the magnesia-boron nitride mixture is higher than that of the boron nitride disposed about the heating element for urging the boron nitride radially outwardly against the housing during elevated temperatures to assure adequate thermal contact between the housing and the boron nitride.

  7. Nuclear Thermal Rocket Simulation in NPSS

    NASA Technical Reports Server (NTRS)

    Belair, Michael L.; Sarmiento, Charles J.; Lavelle, Thomas M.

    2013-01-01

    Four nuclear thermal rocket (NTR) models have been created in the Numerical Propulsion System Simulation (NPSS) framework. The models are divided into two categories. One set is based upon the ZrC-graphite composite fuel element and tie tube-style reactor developed during the Nuclear Engine for Rocket Vehicle Application (NERVA) project in the late 1960s and early 1970s. The other reactor set is based upon a W-UO2 ceramic-metallic (CERMET) fuel element. Within each category, a small and a large thrust engine are modeled. The small engine models utilize RL-10 turbomachinery performance maps and have a thrust of approximately 33.4 kN (7,500 lbf ). The large engine models utilize scaled RL-60 turbomachinery performance maps and have a thrust of approximately 111.2 kN (25,000 lbf ). Power deposition profiles for each reactor were obtained from a detailed Monte Carlo N-Particle (MCNP5) model of the reactor cores. Performance factors such as thermodynamic state points, thrust, specific impulse, reactor power level, and maximum fuel temperature are analyzed for each engine design.

  8. Nuclear Thermal Rocket Simulation in NPSS

    NASA Technical Reports Server (NTRS)

    Belair, Michael L.; Sarmiento, Charles J.; Lavelle, Thomas L.

    2013-01-01

    Four nuclear thermal rocket (NTR) models have been created in the Numerical Propulsion System Simulation (NPSS) framework. The models are divided into two categories. One set is based upon the ZrC-graphite composite fuel element and tie tube-style reactor developed during the Nuclear Engine for Rocket Vehicle Application (NERVA) project in the late 1960s and early 1970s. The other reactor set is based upon a W-UO2 ceramic- metallic (CERMET) fuel element. Within each category, a small and a large thrust engine are modeled. The small engine models utilize RL-10 turbomachinery performance maps and have a thrust of approximately 33.4 kN (7,500 lbf ). The large engine models utilize scaled RL-60 turbomachinery performance maps and have a thrust of approximately 111.2 kN (25,000 lbf ). Power deposition profiles for each reactor were obtained from a detailed Monte Carlo N-Particle (MCNP5) model of the reactor cores. Performance factors such as thermodynamic state points, thrust, specific impulse, reactor power level, and maximum fuel temperature are analyzed for each engine design.

  9. Multi-physics nuclear reactor simulator for advanced nuclear engineering education

    SciTech Connect

    Yamamoto, A.

    2012-07-01

    Multi-physics nuclear reactor simulator, which aims to utilize for advanced nuclear engineering education, is being introduced to Nagoya Univ.. The simulator consists of the 'macroscopic' physics simulator and the 'microscopic' physics simulator. The former performs real time simulation of a whole nuclear power plant. The latter is responsible to more detail numerical simulations based on the sophisticated and precise numerical models, while taking into account the plant conditions obtained in the macroscopic physics simulator. Steady-state and kinetics core analyses, fuel mechanical analysis, fluid dynamics analysis, and sub-channel analysis can be carried out in the microscopic physics simulator. Simulation calculations are carried out through dedicated graphical user interface and the simulation results, i.e., spatial and temporal behaviors of major plant parameters are graphically shown. The simulator will provide a bridge between the 'theories' studied with textbooks and the 'physical behaviors' of actual nuclear power plants. (authors)

  10. Multidimensional multiphysics simulation of nuclear fuel behavior

    NASA Astrophysics Data System (ADS)

    Williamson, R. L.; Hales, J. D.; Novascone, S. R.; Tonks, M. R.; Gaston, D. R.; Permann, C. J.; Andrs, D.; Martineau, R. C.

    2012-04-01

    Nuclear fuel operates in an environment that induces complex multiphysics phenomena, occurring over distances ranging from inter-atomic spacing to meters, and times scales ranging from microseconds to years. This multiphysics behavior is often tightly coupled and many important aspects are inherently multidimensional. Most current fuel modeling codes employ loose multiphysics coupling and are restricted to 2D axisymmetric or 1.5D approximations. This paper describes a new modeling tool able to simulate coupled multiphysics and multiscale fuel behavior, for either 2D axisymmetric or 3D geometries. Specific fuel analysis capabilities currently implemented in this tool are described, followed by a set of demonstration problems which include a 10-pellet light water reactor fuel rodlet, three-dimensional analysis of pellet clad mechanical interaction in the vicinity of a defective fuel pellet, coupled heat transfer and fission product diffusion in a TRISO-coated fuel particle, a demonstration of the ability to couple to lower-length scale models to account for material property variation with microstructural evolution, and a demonstration of the tool's ability to efficiently solve very large and complex problems using massively-parallel computing. A final section describes an early validation exercise, comparing simulation results to a light water reactor fuel rod experiment.

  11. Numerical simulations of axisymmetric hydrodynamical Bondi-Hoyle accretion on to a compact object

    NASA Astrophysics Data System (ADS)

    El Mellah, I.; Casse, F.

    2015-12-01

    Bondi-Hoyle accretion configurations occur as soon as a gravitating body is immersed in an ambient medium with a supersonic relative velocity. From wind-accreting X-ray binaries to runaway neutron stars, such a regime has been witnessed many times and is believed to account for shock formation, the properties of which can be only marginally derived analytically. In this paper, we present the first results of the numerical characterization of the stationary flow structure of Bondi-Hoyle accretion on to a compact object, from the large-scale accretion radius down to the vicinity of the compact body. For different Mach numbers, we study the associated bow shock. It turns out that those simulations confirm the analytical prediction by Foglizzo & Ruffert concerning the topology of the inner sonic surface with an adiabatic index of 5/3. They also enable us to derive the related mass accretion rates, the position and the temperature of the bow shock, as function of the flow parameters, along with the transverse density and temperature profiles in the wake.

  12. Ideal magnetohydrodynamic simulations of low beta compact toroid injection into a hot strongly magnetized plasma

    SciTech Connect

    Liu, Wei; Hsu, Scott; Li, Hui

    2009-01-01

    We present results from three-dimensional ideal magnetohydrodynamic simulations of low {beta} compact toroid (CT) injection into a hot strongly magnetized plasma, with the aim of providing insight into CT fueling of a tokamak with parameters relevant for ITER (International Thermonuclear Experimental Reactor). A regime is identified in terms of CT injection speed and CT-to-background magnetic field ratio that appears promising for precise core fueling. Shock-dominated regimes, which are probably unfavorable for tokamak fueling, are also identified. The CT penetration depth is proportional to the CT injection speed and density. The entire CT evolution can be divided into three stages: (1) initial penetration, (2) compression in the direction of propagation and reconnection, and (3) coming to rest and spreading in the direction perpendicular to injection. Tilting of the CT is not observed due to the fast transit time of the CT across the background plasma.

  13. Monte Carlo simulations of compact gamma cameras based on avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Després, Philippe; Funk, Tobias; Shah, Kanai S.; Hasegawa, Bruce H.

    2007-06-01

    Avalanche photodiodes (APDs), and in particular position-sensitive avalanche photodiodes (PSAPDs), are an attractive alternative to photomultiplier tubes (PMTs) for reading out scintillators for PET and SPECT. These solid-state devices offer high gain and quantum efficiency, and can potentially lead to more compact and robust imaging systems with improved spatial and energy resolution. In order to evaluate this performance improvement, we have conducted Monte Carlo simulations of gamma cameras based on avalanche photodiodes. Specifically, we investigated the relative merit of discrete and PSAPDs in a simple continuous crystal gamma camera. The simulated camera was composed of either a 4 × 4 array of four channels 8 × 8 mm2 PSAPDs or an 8 × 8 array of 4 × 4 mm2 discrete APDs. These configurations, requiring 64 channels readout each, were used to read the scintillation light from a 6 mm thick continuous CsI:Tl crystal covering the entire 3.6 × 3.6 cm2 photodiode array. The simulations, conducted with GEANT4, accounted for the optical properties of the materials, the noise characteristics of the photodiodes and the nonlinear charge division in PSAPDs. The performance of the simulated camera was evaluated in terms of spatial resolution, energy resolution and spatial uniformity at 99mTc (140 keV) and 125I (ap30 keV) energies. Intrinsic spatial resolutions of 1.0 and 0.9 mm were obtained for the APD- and PSAPD-based cameras respectively for 99mTc, and corresponding values of 1.2 and 1.3 mm FWHM for 125I. The simulations yielded maximal energy resolutions of 7% and 23% for 99mTc and 125I, respectively. PSAPDs also provided better spatial uniformity than APDs in the simple system studied. These results suggest that APDs constitute an attractive technology especially suitable to build compact, small field of view gamma cameras dedicated, for example, to small animal or organ imaging.

  14. NTP system simulation and detailed nuclear engine modeling

    NASA Technical Reports Server (NTRS)

    Anghaie, Samim

    1993-01-01

    The topics are presented in viewgraph form and include the following: nuclear thermal propulsion (NTP) & detailed nuclear engine modeling; modeling and engineering simulation of nuclear thermal rocket systems; nuclear thermal rocket simulation system; INSPI-NTVR core axial flow profiles; INSPI-NTRV core axial flow profiles; specific impulse vs. chamber pressure; turbine pressure ratio vs. chamber pressure; NERVA core axial flow profiles; P&W XNR2000 core axial flow profiles; pump pressure rise vs. chamber pressure; streamline of jet-induced flow in cylindrical chamber; flow pattern of a jet-induced flow in a chamber; and radiative heat transfer models.

  15. Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method

    NASA Astrophysics Data System (ADS)

    Liu, Chun; Pollard, David D.; Gu, Kai; Shi, Bin

    2015-12-01

    Wiggly compaction bands in porous aeolian sandstone vary from chevron shape to wavy shape to nearly straight. In some outcrops these variations occur along a single band. A bonded close-packed discrete element model is used to investigate what mechanical properties control the formation of wiggly compaction bands (CBs). To simulate the volumetric yielding failure of porous sandstone, a discrete element shrinks when the force state of one of its bonds reaches the yielding cap defined by the failure force and the aspect ratio (k) of the yielding ellipse. A Matlab code "MatDEM3D" has been developed on the basis of this enhanced discrete element method. Mechanical parameters of elements are chosen according to the elastic properties and the strengths of porous sandstone. In numerical simulations, the failure angle between the band segment and maximum principle stress decreases from 90° to approximately 45° as k increases from 0.5 to 2, and compaction bands vary from straight to chevron shape. With increasing strain, subsequent compaction occurs inside or beside compacted elements, which leads to further compaction and thickening of bands. The simulations indicate that a greater yielding stress promotes chevron CBs, and a greater cement strength promotes straight CBs. Combined with the microscopic analysis introduced in the companion paper, we conclude that the shape of wiggly CBs is controlled by the mechanical properties of sandstone, including the aspect ratio of the yielding ellipse, the critical yielding stress, and the cement strength, which are determined primarily by petrophysical attributes, e.g., grain sorting, porosity, and cementation.

  16. Molecular dynamics simulation of the acidic compact state of apomyoglobin from yellowfin tuna.

    PubMed

    Bismuto, Ettore; Di Maggio, Emiddio; Pleus, Stefan; Sikor, Martin; Röcker, Carlheinz; Nienhaus, G Ulrich; Lamb, Don C

    2009-02-01

    A molecular model of the acidic compact state of apomyoglobin (A-state) from yellowfin tuna was obtained using molecular dynamics simulations (MD) by calculating multiple trajectories. To cause partial unfolding within a reasonable amount of CPU time, both an acidic environment (pH 3 and 0.15M NaCl) and a temperature jump to 500 K were needed. Twenty-five acidic structures of apomyoglobin were generated by MD, 10 of them can be clustered by RMSD in an average structure having a common hydrophobic core as was reported for acidic sperm whale apomyoglobin, with shortened helices A,G,E, and H (the helix A appears to be translated along the sequence). Prolonging the MD runs at 500 K did not cause further substantial unfolding, suggesting that the ensemble of generated structures is indicative of a region of the conformational space accessible to the apoprotein at acidic pH corresponding to a local energy minimum. The comparison of experimentally determined values of specific spectroscopic properties of the apomyoglobin in acidic salt conditions with the expected ones on the basis of the MD generated structures shows a reasonable agreement considering the characteristic uncertainties of both experimental and simulation techniques. We used frequency domain fluorometry, acrylamide fluorescence quenching, and fluorescence correlation spectroscopy together with far UV circular dichroism to estimate the helical content, the Stern-Volmer quenching constant and the radius of gyration of the protein. Tuna apomyoglobin is a single tryptophan protein and thus, interpretation of its intrinsic fluorescence is simpler than for other proteins. The high sensitivity of the applied fluorescence techniques enabled experiments to be performed under very dilute conditions, that is, at concentrations of subnanomolar for the FCS measurements and 6 muM for the other fluorescence measurements. As high concentrations of proteins can strongly affect the association equilibrium among partially

  17. Simulating Compact Elliptical Galaxy Formation by Tidal Stripping for Comparison to the RESOLVE Survey

    NASA Astrophysics Data System (ADS)

    Ray, Christine; Snyder, Elaine M.; Kannappan, Sheila; Sinha, Manodeep; RESOLVE Team

    2016-01-01

    Observations of compact elliptical galaxies (cEs) have uncovered abnormally high velocity dispersions and surface brightnesses for objects of their mass. These properties indicate that they may be the tidally stripped remnants of larger disk galaxies. We test this tidal stripping scenario using N-body simulations of cE formation with the Gadget-2 code. We track the velocity dispersions of stellar particles within the half-light radius throughout our simulations, which allows us to compare our simulated galaxies with velocity dispersion data for cEs in the RESOLVE survey. We first consider initial conditions similar to published work, which report stripping of a large spiral galaxy (stellar mass ~ 10^11 solar masses) to cE size in a cluster potential. We find that the density of the disk galaxy is too high to allow it to lose particles to the less dense cluster. We argue that the initial position of the galaxy with respect to the cluster as well as the large size of the cluster particles in comparison to the size of the galaxy particles artificially heightened the stripping percentages reported in previous work. We hypothesize that only a dwarf galaxy with a shallower density profile can be stripped to cE size, and we present initial efforts to test this idea. We simulate a dwarf galaxy based on a real system in the RESOLVE survey, with stellar mass 10^9 solar masses and half-light radius 1.15 kpc. Within ~700 pc our dwarf is denser than our cluster, suggesting the stripped remnant should be close to the size of RESOLVE cEs. This radius contains approximately 13% of the total stellar mass of the galaxy, or ~2 x 10^8 solar masses. We therefore expect our stripped remnant to be at least this massive, although the impact parameter of the orbit will determine how much mass is actually removed. We discuss the position of our simulated galaxies compared to RESOLVE cEs in the velocity dispersion vs. mass plane. This research has been supported by National Science

  18. Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Upgrade Activities

    NASA Technical Reports Server (NTRS)

    Emrich, William J. Jr.; Moran, Robert P.; Pearson, J. Boise

    2012-01-01

    To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission and would be exposed to flowing hydrogen. Initial testing of a somewhat prototypical fuel element has been successfully performed in NTREES and the facility has now been shutdown to allow for an extensive reconfiguration of the facility which will result in a significant upgrade in its capabilities

  19. Investigation of Flow Conditioners for Compact Jet Engine Simulator Rig Noise Reduction

    NASA Technical Reports Server (NTRS)

    Doty, Michael J.; Haskin, Henry H.

    2011-01-01

    The design requirements for two new Compact Jet Engine Simulator (CJES) units for upcoming wind tunnel testing lead to the distinct possibility of rig noise contamination. The acoustic and aerodynamic properties of several flow conditioner devices are investigated over a range of operating conditions relevant to the CJES units to mitigate the risk of rig noise. An impinging jet broadband noise source is placed in the upstream plenum of the test facility permitting measurements of not only flow conditioner self-noise, but also noise attenuation characteristics. Several perforated plate and honeycomb samples of high porosity show minimal self-noise but also minimal attenuation capability. Conversely, low porosity perforated plate and sintered wire mesh conditioners exhibit noticeable attenuation but also unacceptable self-noise. One fine wire mesh sample (DP450661) shows minimal selfnoise and reasonable attenuation, particularly when combined in series with a 15.6 percent open area (POA) perforated plate upstream. This configuration is the preferred flow conditioner system for the CJES, providing up to 20 dB of broadband attenuation capability with minimal self-noise.

  20. Hydraulic performance of compacted clay liners under simulated daily thermal cycles.

    PubMed

    Aldaeef, A A; Rayhani, M T

    2015-10-01

    Compacted clay liners (CCLs) are commonly used as hydraulic barriers in several landfill applications to isolate contaminants from the surrounding environment and minimize the escape of leachate from the landfill. Prior to waste placement in landfills, CCLs are often exposed to temperature fluctuations which can affect the hydraulic performance of the liner. Experimental research was carried out to evaluate the effects of daily thermal cycles on the hydraulic performance of CCLs under simulated landfill conditions. Hydraulic conductivity tests were conducted on different soil specimens after being exposed to various thermal and dehydration cycles. An increase in the CCL hydraulic conductivity of up to one order of magnitude was recorded after 30 thermal cycles for soils with low plasticity index (PI = 9.5%). However, medium (PI = 25%) and high (PI = 37.2%) plasticity soils did not show significant hydraulic deviation due to their self-healing potential. Overlaying the CCL with a cover layer minimized the effects of daily thermal cycles, and maintained stable hydraulic performance in the CCLs even after exposure to 60 thermal cycles. Wet-dry cycles had a significant impact on the hydraulic aspect of low plasticity CCLs. However, medium and high plasticity CCLs maintained constant hydraulic performance throughout the test intervals. The study underscores the importance of protecting the CCL from exposure to atmosphere through covering it by a layer of geomembrane or an interim soil layer.

  1. Hydraulic performance of compacted clay liners under simulated daily thermal cycles.

    PubMed

    Aldaeef, A A; Rayhani, M T

    2015-10-01

    Compacted clay liners (CCLs) are commonly used as hydraulic barriers in several landfill applications to isolate contaminants from the surrounding environment and minimize the escape of leachate from the landfill. Prior to waste placement in landfills, CCLs are often exposed to temperature fluctuations which can affect the hydraulic performance of the liner. Experimental research was carried out to evaluate the effects of daily thermal cycles on the hydraulic performance of CCLs under simulated landfill conditions. Hydraulic conductivity tests were conducted on different soil specimens after being exposed to various thermal and dehydration cycles. An increase in the CCL hydraulic conductivity of up to one order of magnitude was recorded after 30 thermal cycles for soils with low plasticity index (PI = 9.5%). However, medium (PI = 25%) and high (PI = 37.2%) plasticity soils did not show significant hydraulic deviation due to their self-healing potential. Overlaying the CCL with a cover layer minimized the effects of daily thermal cycles, and maintained stable hydraulic performance in the CCLs even after exposure to 60 thermal cycles. Wet-dry cycles had a significant impact on the hydraulic aspect of low plasticity CCLs. However, medium and high plasticity CCLs maintained constant hydraulic performance throughout the test intervals. The study underscores the importance of protecting the CCL from exposure to atmosphere through covering it by a layer of geomembrane or an interim soil layer. PMID:26241932

  2. MHD Simulations of Spherical Tori and Compact Stellarators Using M3D

    NASA Astrophysics Data System (ADS)

    Strauss, H. R.; Park, W.; Tang, X.; Fu, G. Y.; Sugiyama, L.

    1999-11-01

    The M3D++ unstructured mesh version of the M3D code is being applied to low aspect ratio spherical torus disruption simulations. In addition to spherical tokamaks (ST), similar to NSTX, we also study spherical pinches (SP). It is possible to produce SP equilibria with 1 > q > 1/2, and toroidal current decreasing to zero at the wall. These SP equilibria have reverse magnetic shear except in a narrow layer near the wall. The equilibria are free of the global m=1 modes that plague low q pinches such as RFPs. However there can be unstable (m,n) = (2,3) modes. The M3D++ code has been extended to have the capability of using a 3D mesh in configuration space, suitable for stellarator equilibrium, stability, and nonlinear studies, including resistive effects. Equilibria can be initialized with VMEC output or generated from initial data. Applications to compact stellarator configurations such as the PPPL quasi axisymmetric design will be presented.

  3. Pasta nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium

    NASA Astrophysics Data System (ADS)

    Caplan, M. E.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K.

    2015-06-01

    Background: Exotic nonspherical nuclear pasta shapes are expected in nuclear matter at just below saturation density because of competition between short-range nuclear attraction and long-range Coulomb repulsion. Purpose: We explore the impact nuclear pasta may have on nucleosynthesis during neutron star mergers when cold dense nuclear matter is ejected and decompressed. Methods: We use a hybrid CPU/GPU molecular dynamics (MD) code to perform decompression simulations of cold dense matter with 51 200 and 409 600 nucleons from 0.080 fm-3 down to 0.00125 fm-3 . Simulations are run for proton fractions YP= 0.05, 0.10, 0.20, 0.30, and 0.40 at temperatures T = 0.5, 0.75, and 1.0 MeV. The final composition of each simulation is obtained using a cluster algorithm and compared to a constant density run. Results: Size of nuclei in the final state of decompression runs are in good agreement with nuclear statistical equilibrium (NSE) models for temperatures of 1 MeV while constant density runs produce nuclei smaller than the ones obtained with NSE. Our MD simulations produces unphysical results with large rod-like nuclei in the final state of T =0.5 MeV runs. Conclusions: Our MD model is valid at higher densities than simple nuclear statistical equilibrium models and may help determine the initial temperatures and proton fractions of matter ejected in mergers.

  4. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis.

    PubMed

    Ghassoun, J; Mostacci, D

    2011-08-01

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of (252)Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5).

  5. Towards automated mapping of lake ice using RADARSAT-2 and simulated RCM compact polarimetric data

    NASA Astrophysics Data System (ADS)

    Duguay, Claude

    2016-04-01

    The Canadian Ice Service (CIS) produces a weekly ice fraction product (a text file with a single lake-wide ice fraction value, in tenth, estimated for about 140 large lakes across Canada and northern United States) created from the visual interpretation of RADARSAT-2 ScanSAR dual-polarization (HH and HV) imagery, complemented by optical satellite imagery (AVHRR, MODIS and VIIRS). The weekly ice product is generated in support of the Canadian Meteorological Centre (CMC) needs for lake ice coverage in their operational numerical weather prediction model. CIS is interested in moving from its current (manual) way of generating the ice fraction product to a largely automated process. With support from the Canadian Space Agency, a project was recently initiated to assess the potential of polarimetric SAR data for lake ice cover mapping in light of the upcoming RADARSAT Constellation Mission (to be launched in 2018). The main objectives of the project are to evaluate: 1) state-of-the-art image segmentation algorithms and 2) RADARSAT-2 polarimetric and simulated RADARSAT Constellation Mission (RCM) compact polarimetric SAR data for ice/open water discrimination. The goal is to identify the best segmentation algorithm and non-polarimetric/polarimetric parameters for automated lake ice monitoring at CIS. In this talk, we will present the background and context of the study as well as initial results from the analysis of RADARSAT-2 Standard Quad-Pol data acquired during the break-up and freeze-up periods of 2015 on Great Bear Lake, Northwest Territories.

  6. The impact of compaction and leachate recirculation on waste degradation in simulated landfills.

    PubMed

    Ko, Jae Hac; Yang, Fan; Xu, Qiyong

    2016-07-01

    This study investigated the impact of compaction and leachate recirculation on anaerobic degradation of municipal solid waste (MSW) at different methane formation phases. Two stainless steel lysimeters, C1 and C2, were constructed by equipping a hydraulic cylinder to apply pressure load (42kPs) on the MSW. When MSW started to produce methane, C1 was compacted, but C2 was compacted when the methane production rate declined from the peak generation rate. Methane production of C1was inhibited by the compaction and resulted in producing a total of 106L methane (44L/kgVS). However, the compaction in C2 promoted MSW degradation resulting in producing a total of 298L methane (125L/kgVS). The concentrations of volatile fatty acids and chemical oxygen demand showed temporary increases, when pressure load was applied. It was considered that the increased substrate accessibility within MSW by compaction could cause either the inhibition or the enhancement of methane production, depending the tolerability of methanogens on the acidic inhibition. Leachate recirculation also gave positive effects on methane generation from wet waste in the decelerated methanogenic phase by increasing mass transfer and the concentrations of volatile fatty acids. PMID:27003792

  7. Finite size effects in neutron star and nuclear matter simulations

    NASA Astrophysics Data System (ADS)

    Giménez Molinelli, P. A.; Dorso, C. O.

    2015-01-01

    In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called "finite size effects", unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the "nuclear pasta" phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations-for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities.

  8. Compact groups from the Millennium Simulations - I. Their nature and the completeness of the Hickson sample

    NASA Astrophysics Data System (ADS)

    Díaz-Giménez, Eugenia; Mamon, Gary A.

    2010-12-01

    We identify compact groups of galaxies (CGs) within mock galaxy catalogues from the Millennium Simulation at z= 0 with the semi-analytic models (SAMs) of galaxy formation of Bower et al., Croton et al. and De Lucia & Blaizot. CGs are identified using the same 2D criteria as those visually applied by Hickson (1982) to his CGs (HCGs), but with a brightest galaxy magnitude limit, and we also add the important effect of observers blending close projected pairs. Half of the mock CGs identified in projection contain at least four accordant velocities (mvCGs), versus 70 per cent for HCGs. In comparison to mvCGs, the HCGs are only 8 per cent complete at distances <9000 km s-1, missing the CGs with small angular sizes, a strongly dominant galaxy, and (for the second SAM) the mvCGs that are fainter and those with lower surface brightness. 10 per cent of the mock mvCGs are identical to the parent virialized group, meaning that they are isolated, while the remainder are embedded in their parent virialized groups. We explore different ways to determine the fraction of physically dense groups given the data from the simulations. Binding energy criteria turn out to be inapplicable given the segregation between galaxies and dark matter particles. We rely instead on the combination of the three-dimensional length of the CGs (maximum real space galaxy separation) and their elongation along the line of sight (ratio of maximum line-of-sight to maximum projected separations), restricting ourselves in both cases to the smallest quartets within the CGs. We find that between 64 and 80 per cent (depending on the SAM) of the mvCGs have 3D lengths shorter than 200 h-1 kpc, between 71 and 80 per cent have line-of-sight elongations less than 2, while between 59 and 76 per cent have either 3D lengths shorter than 100 h-1 kpc or both lengths shorter than 200 h-1 kpc and elongations smaller than 2. Therefore, chance alignments (CAs) of galaxies concern at most 40 per cent of the mvCGs. These CAs

  9. Compaction of granular materials: numerical simulation of "elastic" compression and pressure solution creep

    NASA Astrophysics Data System (ADS)

    Bernabe, Y.; Evans, J.

    2012-12-01

    In a previous work we investigated stress transfer in a pair of grain contacts undergoing pressure solution (PS) creep, showed that stress transfer resulted in a significant decrease in overall strain rate, and concluded that PS creep rates of a randomly packed granular aggregate should be affected by packing evolution and the formation of new contacts during creep. To test these conclusions further, we are numerically simulating the "elastic" hydrostatic compression of a random pack of spheres, using a numerical method similar to that of Cundall and Strack [1979]. We assumed that the spheres were frictionless (i.e., spheres in contact only interacted through normal forces) and that the contact forces obeyed the non-linear Digby [1981] model. In order to determine the PS creep compression of the sphere pack subjected to a constant confining pressure pc, we calculated the thicknesses of the dissolved layers at each individual grain contact during a small time increment and, from these, the overall deformation of the sphere pack. We used an analytical expression discussed in our previous paper and originating from Lehner and Leroy [2004]. During these simulations, we also computed the mean coordination number of the grain contact z, the effective bulk modulus K of the sphere pack and others parameters characterizing the topological and mechanical properties of the sphere assembly. Our results show strong non-linear increase of z and K with pc during "elastic" compression and, with time, during PS creep. The packing rearrangements associated with PS creep produce complex time dependence of the overall deformation ɛ(t). We observed a regular transition from ɛ∝t^3/4 at early times (i.e., less than 0.1 years) and ɛ∝t^1/3 at late times (i.e., more than 1000 years). Cundall, P.A., and O.D.L. Strack (1979), A discrete numerical model for granular assemblies, Geotech., 29, 47-65. Digby, P.J. (1981), The effective elastic moduli of porous rocks, J. Appl. Mech., 48, 803

  10. Hyperthermal Environments Simulator for Nuclear Rocket Engine Development

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Foote, John P.; Clifton, W. B.; Hickman, Robert R.; Wang, Ten-See; Dobson, Christopher C.

    2011-01-01

    An arc-heater driven hyperthermal convective environments simulator was recently developed and commissioned for long duration hot hydrogen exposure of nuclear thermal rocket materials. This newly established non-nuclear testing capability uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce hightemperature pressurized hydrogen flows representative of nuclear reactor core environments, excepting radiation effects, and is intended to serve as a low-cost facility for supporting non-nuclear developmental testing of hightemperature fissile fuels and structural materials. The resulting reactor environments simulator represents a valuable addition to the available inventory of non-nuclear test facilities and is uniquely capable of investigating and characterizing candidate fuel/structural materials, improving associated processing/fabrication techniques, and simulating reactor thermal hydraulics. This paper summarizes facility design and engineering development efforts and reports baseline operational characteristics as determined from a series of performance mapping and long duration capability demonstration tests. Potential follow-on developmental strategies are also suggested in view of the technical and policy challenges ahead. Keywords: Nuclear Rocket Engine, Reactor Environments, Non-Nuclear Testing, Fissile Fuel Development.

  11. An efficient compact fourth order FD method for simulating 3-D mantle convection at high Rayleigh number

    NASA Astrophysics Data System (ADS)

    Wright, G. B.; Barnett, G. A.; Yuen, D. A.

    2009-12-01

    We present an efficient method based on fourth order compact finite-differences for simulating three dimensional mantle convection (i.e. Rayleigh-Bénard convection in the infinite Prandtl number limit) with constant viscosity in a rectangular box. In the high Rayleigh number regime, this thermal convection model has recently been shown to exhibit many of the features of turbulent flow that are typically identified with high Reynolds number flow [1]. High order compact finite schemes are known to be particularly good for simulating turbulent flows because of their spectral like resolution [2], which ameliorates dispersion and anisotropy errors. They have also been shown to be much less susceptible than second order schemes to spurious oscillations for transient convection diffusion equations at large Péclet number (as occurs for the temperature equation in the mantle convection model at high Rayleigh number). Finally, high order schemes have been shown to be more efficient than low order methods in terms of degrees of freedom required to attain a specified error level, which is important for reducing memory requirements so simulations can be performed on emerging low-cost high performance computational platforms like graphics processing units (GPUs). We demonstrate the capabilities of our compact fourth order scheme at accurately capturing such phenomena as transient periods of double layered convection[3] (see Figure 1) and flow reversals using far fewer degrees of freedom than required for traditional second order methods. Finally, we discuss the computational cost of the scheme and its efficient implementation on GPUs. References: [1] M. Breuer and U. Hansen, Turbulent convection in the zero Reynolds number limit, EPL, 86, 24004, 2009. [2] S. K. Lele, Compact finite difference schemes with spectral-like resolution, J. Comput. Phys., 103, 16, 1992. [3] A. P. Boss and I. S. Sacks, Time-dependent models of single- and double-layer mantle convection, Nature, 308

  12. Simulations of nuclear resonance fluorescence in GEANT4

    NASA Astrophysics Data System (ADS)

    Lakshmanan, Manu N.; Harrawood, Brian P.; Rusev, Gencho; Agasthya, Greeshma A.; Kapadia, Anuj J.

    2014-11-01

    The nuclear resonance fluorescence (NRF) technique has been used effectively to identify isotopes based on their nuclear energy levels. Specific examples of its modern-day applications include detecting spent nuclear waste and cargo scanning for homeland security. The experimental designs for these NRF applications can be more efficiently optimized using Monte Carlo simulations before the experiment is implemented. One of the most widely used Monte Carlo physics simulations is the open-source toolkit GEANT4. However, NRF physics has not been incorporated into the GEANT4 simulation toolkit in publicly available software. Here we describe the development and testing of an NRF simulation in GEANT4. We describe in depth the development and architecture of this software for the simulation of NRF in any isotope in GEANT4; as well as verification and validation testing of the simulation for NRF in boron. In the verification testing, the simulation showed agreement with the analytical model to be within 0.6% difference for boron and iron. In the validation testing, the simulation showed agreement to be within 20.5% difference with the experimental measurements for boron, with the percent difference likely due to small uncertainties in beam polarization, energy distribution, and detector composition.

  13. Hydrodynamical Simulations of Nuclear Rings in Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Shen, Juntai; Kim, Woong-Tae

    2015-08-01

    Dust lanes, nuclear rings, and nuclear spirals are typical gas structures in the inner region of barred galaxies. Their shapes and properties are linked to the physical parameters of the host galaxy. We use high-resolution hydrodynamical simulations to study 2D gas flows in simple barred galaxy models. The nuclear rings formed in our simulations can be divided into two groups: one group is nearly round and the other is highly elongated. We find that roundish rings may not form when the bar pattern speed is too high or the bulge central density is too low. We also study the periodic orbits in our galaxy models, and find that the concept of inner Lindblad resonance (ILR) may be generalized by the extent of x2 orbits. All roundish nuclear rings in our simulations settle in the range of x2 orbits (or ILRs). However, knowing the resonances is insufficient to pin down the exact location of these nuclear rings. We suggest that the backbone of round nuclear rings is the x2 orbital family, i.e. round nuclear rings are allowed only in the radial range of x2 orbits. A round nuclear ring forms exactly at the radius where the residual angular momentum of infalling gas balances the centrifugal force, which can be described by a parameter f_ring measured from the rotation curve. We find an empirical relation between the bar parameters and f_ring, and apply it to measure bar pattern speed in a sample of barred galaxies with nuclear rings.

  14. Hydrodynamical Simulations of Nuclear Rings in Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Shen, Juntai; Kim, Woong-Tae

    2015-06-01

    Dust lanes, nuclear rings, and nuclear spirals are typical gas structures in the inner region of barred galaxies. Their shapes and properties are linked to the physical parameters of the host galaxy. We use high-resolution hydrodynamical simulations to study 2D gas flows in simple barred galaxy models. The nuclear rings formed in our simulations can be divided into two groups: one group is nearly round and the other is highly elongated. We find that roundish rings may not form when the bar pattern speed is too high or the bulge central density is too low. We also study the periodic orbits in our galaxy models, and find that the concept of inner Lindblad resonance (ILR) may be generalized by the extent of {x}2 orbits. All roundish nuclear rings in our simulations settle in the range of {x}2 orbits (or ILRs). However, knowing the resonances is insufficient to pin down the exact location of these nuclear rings. We suggest that the backbone of round nuclear rings is the {x}2 orbital family, i.e., round nuclear rings are allowed only in the radial range of {x}2 orbits. A round nuclear ring forms exactly at the radius where the residual angular momentum of infalling gas balances the centrifugal force, which can be described by a parameter {f}{ring} measured from the rotation curve. The gravitational torque on gas in high pattern speed models is larger, leading to a smaller ring size than in the low pattern speed models. Our result may have important implications for using nuclear rings to measure the parameters of real barred galaxies with 2D gas kinematics.

  15. Gaining insight into effective metrology height through the use of a compact CDSEM model for lithography simulation

    NASA Astrophysics Data System (ADS)

    Fang, Chao; Graves, Trey; Vaglio Pret, Alessandro; Robertson, Stewart; Smith, Mark

    2016-03-01

    Computer simulation of lithographic performance, including resist CD, film thickness, sidewall angle and profile has been extensively studied during the past three decades. Lithography simulation has been widely adopted as an enabling technology for high-volume chip manufacturing. However, measurement artifacts arising from CD-SEM metrology are typically ignored in simulation, due to the difficulty of accurately modeling the effect of the CD-SEM at acceptable computational speed. In this paper, we demonstrate how CD measurements can be improved by including a fast, compact CD-SEM model. For example, the variation in effective resist metrology height along contour lines extracted from a simulated CD-SEM image is characterized for a range of structures through focus. We also demonstrate how SEM settings affect the shape of extracted SEM contour and metrology height at contour edge. The Edge Placement Error (EPE) caused by SEM artifact is carefully studied.

  16. Requirements for advanced simulation of nuclear reactor and chemicalseparation plants.

    SciTech Connect

    Palmiotti, G.; Cahalan, J.; Pfeiffer, P.; Sofu, T.; Taiwo, T.; Wei,T.; Yacout, A.; Yang, W.; Siegel, A.; Insepov, Z.; Anitescu, M.; Hovland,P.; Pereira, C.; Regalbuto, M.; Copple, J.; Willamson, M.

    2006-12-11

    This report presents requirements for advanced simulation of nuclear reactor and chemical processing plants that are of interest to the Global Nuclear Energy Partnership (GNEP) initiative. Justification for advanced simulation and some examples of grand challenges that will benefit from it are provided. An integrated software tool that has its main components, whenever possible based on first principles, is proposed as possible future approach for dealing with the complex problems linked to the simulation of nuclear reactor and chemical processing plants. The main benefits that are associated with a better integrated simulation have been identified as: a reduction of design margins, a decrease of the number of experiments in support of the design process, a shortening of the developmental design cycle, and a better understanding of the physical phenomena and the related underlying fundamental processes. For each component of the proposed integrated software tool, background information, functional requirements, current tools and approach, and proposed future approaches have been provided. Whenever possible, current uncertainties have been quoted and existing limitations have been presented. Desired target accuracies with associated benefits to the different aspects of the nuclear reactor and chemical processing plants were also given. In many cases the possible gains associated with a better simulation have been identified, quantified, and translated into economical benefits.

  17. Parallelization and automatic data distribution for nuclear reactor simulations

    SciTech Connect

    Liebrock, L.M.

    1997-07-01

    Detailed attempts at realistic nuclear reactor simulations currently take many times real time to execute on high performance workstations. Even the fastest sequential machine can not run these simulations fast enough to ensure that the best corrective measure is used during a nuclear accident to prevent a minor malfunction from becoming a major catastrophe. Since sequential computers have nearly reached the speed of light barrier, these simulations will have to be run in parallel to make significant improvements in speed. In physical reactor plants, parallelism abounds. Fluids flow, controls change, and reactions occur in parallel with only adjacent components directly affecting each other. These do not occur in the sequentialized manner, with global instantaneous effects, that is often used in simulators. Development of parallel algorithms that more closely approximate the real-world operation of a reactor may, in addition to speeding up the simulations, actually improve the accuracy and reliability of the predictions generated. Three types of parallel architecture (shared memory machines, distributed memory multicomputers, and distributed networks) are briefly reviewed as targets for parallelization of nuclear reactor simulation. Various parallelization models (loop-based model, shared memory model, functional model, data parallel model, and a combined functional and data parallel model) are discussed along with their advantages and disadvantages for nuclear reactor simulation. A variety of tools are introduced for each of the models. Emphasis is placed on the data parallel model as the primary focus for two-phase flow simulation. Tools to support data parallel programming for multiple component applications and special parallelization considerations are also discussed.

  18. Hyperthermal Environments Simulator for Nuclear Rocket Engine Development

    NASA Astrophysics Data System (ADS)

    Litchford, R. J.; Foote, J. P.; Clifton, W. B.; Hickman, R. R.; Wang, T.-S.; Dobson, C. C.

    An arc-heater driven hyperthermal convective environments simulator was recently developed and commissioned for long duration hot hydrogen exposure of nuclear thermal rocket materials. This newly established non-nuclear testing capability uses a high-power, multi-gas, wall-stabilised constricted arc-heater to produce high-temperature pressurised hydrogen flows representative of nuclear reactor core environments, excepting radiation effects, and is intended to serve as a low-cost facility for supporting non-nuclear developmental testing of high-temperature fissile fuels and structural materials. The resulting reactor environments simulator represents a valuable addition to the available inventory of non-nuclear test facilities and is uniquely capable of investigating and characterising candidate fuel/structural materials, improving associated processing/ fabrication techniques, and simulating reactor thermal hydraulics. This paper summarizes facility design and engineering development efforts and reports baseline operational characteristics as determined from a series of performance mapping and long duration capability demonstration tests. Potential follow-on developmental strategies are also suggested in view of the technical and policy challenges ahead.

  19. Simulating Nuclear and Electronic Quantum Effects in Enzymes.

    PubMed

    Wang, L; Isborn, C M; Markland, T E

    2016-01-01

    An accurate treatment of the structures and dynamics that lead to enhanced chemical reactivity in enzymes requires explicit treatment of both electronic and nuclear quantum effects. The former can be captured in ab initio molecular dynamics (AIMD) simulations, while the latter can be included by performing ab initio path integral molecular dynamics (AI-PIMD) simulations. Both AIMD and AI-PIMD simulations have traditionally been computationally prohibitive for large enzymatic systems. Recent developments in streaming computer architectures and new algorithms to accelerate path integral simulations now make these simulations practical for biological systems, allowing elucidation of enzymatic reactions in unprecedented detail. In this chapter, we summarize these recent developments and discuss practical considerations for applying AIMD and AI-PIMD simulations to enzymes. PMID:27498646

  20. Pasta Elasticity: Molecular dynamics simulations of nuclear pasta deformations

    NASA Astrophysics Data System (ADS)

    Caplan, M. E.; Horowitz, C. J.; Berry, D. K.

    2015-04-01

    Nuclear pasta is expected in the inner crust of neutron stars at densities near the nuclear saturation density. In this work, the elastic properties of pasta are calculated from large scale molecular dynamics simulations by deforming the simulation volume. Our model uses a semi-classical two-nucleon potential that reproduces nuclear saturation. We report the shear modulus and breaking strain of a variety of pasta phases for different temperatures, densities, and proton fractions. The presence of pasta in neutron stars could have significant effects on crustal oscillations and could be inferred from observations of soft-gamma repeaters. Additionally, these elastic parameters will enable us to improve estimates of the maximum size and lifetime of ``mountains'' on the crust, which could efficiently radiate gravitational waves.

  1. Reactor Subsystem Simulation for Nuclear Hybrid Energy Systems

    SciTech Connect

    Shannon Bragg-Sitton; J. Michael Doster; Alan Rominger

    2012-09-01

    Preliminary system models have been developed by Idaho National Laboratory researchers and are currently being enhanced to assess integrated system performance given multiple sources (e.g., nuclear + wind) and multiple applications (i.e., electricity + process heat). Initial efforts to integrate a Fortran-based simulation of a small modular reactor (SMR) with the balance of plant model have been completed in FY12. This initial effort takes advantage of an existing SMR model developed at North Carolina State University to provide initial integrated system simulation for a relatively low cost. The SMR subsystem simulation details are discussed in this report.

  2. Physical processes of compaction companion report 1 to simulation of geothermal subsidence

    SciTech Connect

    Miller, I.; Dershowitz, W.; Jones, K.; Myer, L.; Roman, K.; Schauer, M.

    1980-03-01

    There are a variety of theories, techniques, and parameters in the subsidence literature. Biot's theory, Terzaghi's theory, and the theory of interacting continua (TINC) are used to explain solid-fluid interaction; stress-strain theories range from linear elastic to e-log p to plasticity and pore-collapse theories. Parameters are numerous: void ratio,, permeability, compaction coefficient, pore compressibility, Young's modulus, bulk modulus, shear modulus, Poisson's ratio, Lame coefficients, coefficient of consolidation, and storage coefficient. The physical processes which govern compaction and deformation in geothermal systems are reviewed. The review is an attempt to provide a reasonably coherent general structure for the theories and parameters which were referred to above. The materials presented is a compendium of existing published work.

  3. Extension of PENELOPE to protons: Simulation of nuclear reactions and benchmark with Geant4

    SciTech Connect

    Sterpin, E.; Sorriaux, J.; Vynckier, S.

    2013-11-15

    Purpose: Describing the implementation of nuclear reactions in the extension of the Monte Carlo code (MC) PENELOPE to protons (PENH) and benchmarking with Geant4.Methods: PENH is based on mixed-simulation mechanics for both elastic and inelastic electromagnetic collisions (EM). The adopted differential cross sections for EM elastic collisions are calculated using the eikonal approximation with the Dirac–Hartree–Fock–Slater atomic potential. Cross sections for EM inelastic collisions are computed within the relativistic Born approximation, using the Sternheimer–Liljequist model of the generalized oscillator strength. Nuclear elastic and inelastic collisions were simulated using explicitly the scattering analysis interactive dialin database for {sup 1}H and ICRU 63 data for {sup 12}C, {sup 14}N, {sup 16}O, {sup 31}P, and {sup 40}Ca. Secondary protons, alphas, and deuterons were all simulated as protons, with the energy adapted to ensure consistent range. Prompt gamma emission can also be simulated upon user request. Simulations were performed in a water phantom with nuclear interactions switched off or on and integral depth–dose distributions were compared. Binary-cascade and precompound models were used for Geant4. Initial energies of 100 and 250 MeV were considered. For cases with no nuclear interactions simulated, additional simulations in a water phantom with tight resolution (1 mm in all directions) were performed with FLUKA. Finally, integral depth–dose distributions for a 250 MeV energy were computed with Geant4 and PENH in a homogeneous phantom with, first, ICRU striated muscle and, second, ICRU compact bone.Results: For simulations with EM collisions only, integral depth–dose distributions were within 1%/1 mm for doses higher than 10% of the Bragg-peak dose. For central-axis depth–dose and lateral profiles in a phantom with tight resolution, there are significant deviations between Geant4 and PENH (up to 60%/1 cm for depth

  4. Numerical simulations of axisymmetric Bondi-Hoyle accretion onto a compact object

    NASA Astrophysics Data System (ADS)

    El Mellah, I.; Casse, F.

    2015-12-01

    Compact bodies which are not at rest compare to an homogeneous ambient environment are believed to undergo Bondi-Hoyle axisymmetric accretion as soon as their relative velocity reaches supersonic levels. Contrary to its spherical counterpart, B-H accretion presents flow structures difficult to analytically derive, hence the need for numerical investigations. The broad dynamics at stake when a tiny compact object engulfs surrounding material at a much larger scale has made numerical consistency a polemical issue as it has prevented both scales to be grasped for reasonable wind velocities. We designed a numerical setup which reconciliates the requirement for finite size accretor with steady states properties of the Bondi-Hoyle flow independent of the size of the inner boundary. The robustness of this setup is evaluated accordingly to predictions concerning the mass accretion rate evolution with the Mach number at infinity and the topology of the sonic surface as determined by te{Foglizzo1996}. It provides an estimation of the mass accretion rates and thus, of the expected X-ray luminosity for an idealized B-H configuration which might not be too far off for isolated compact objects like runaway neutron stars or hyper-luminous X-ray sources.

  5. MITEE-B: A Compact Ultra Lightweight Bi-Modal Nuclear Propulsion Engine for Robotic Planetary Science Missions

    NASA Astrophysics Data System (ADS)

    Powell, James; Maise, George; Paniagua, John; Borowski, Stanley

    2003-01-01

    Nuclear thermal propulsion (NTP) enables unique new robotic planetary science missions that are impossible with chemical or nuclear electric propulsion systems. A compact and ultra lightweight bi-modal nuclear engine, termed MITEE-B (MInature ReacTor EnginE - Bi-Modal) can deliver 1000's of kilograms of propulsive thrust when it operates in the NTP mode, and many kilowatts of continuous electric power when it operates in the electric generation mode. The high propulsive thrust NTP mode enables spacecraft to land and takeoff from the surface of a planet or moon, to hop to multiple widely separated sites on the surface, and virtually unlimited flight in planetary atmospheres. The continuous electric generation mode enables a spacecraft to replenish its propellant by processing in-situ resources, provide power for controls, instruments, and communications while in space and on the surface, and operate electric propulsion units. Six examples of unique and important missions enabled by the MITEE-B engine are described, including: (1) Pluto lander and sample return; (2) Europa lander and ocean explorer; (3) Mars Hopper; (4) Jupiter atmospheric flyer; (5) SunBurn hypervelocity spacecraft; and (6) He3 mining from Uranus. Many additional important missions are enabled by MITEE-B. A strong technology base for MITEE-B already exists. With a vigorous development program, it could be ready for initial robotic science and exploration missions by 2010 AD. Potential mission benefits include much shorter in-space times, reduced IMLEO requirements, and replenishment of supplies from in-situ resources.

  6. Radio-optical scrutiny of compact AGN: correlations between properties of pc-scale jets and optical nuclear emission

    NASA Astrophysics Data System (ADS)

    Arshakian, T. G.; Torrealba, J.; Chavushyan, V. H.; Ros, E.; Lister, M. L.; Cruz-González, I.; Zensus, J. A.

    2010-09-01

    Aims: We study the correlations between the VLBA (Very Long Baseline Array) radio emission at 15 GHz, extended emission at 151 MHz, and optical nuclear emission at 5100 Å for a complete sample of 135 compact jets. Methods: We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical nuclear luminosities of host active galactic nuclei (AGN). Results: We find a significant positive correlation for 99 quasars between optical nuclear luminosities and total radio (VLBA) luminosities of unresolved cores at 15 GHz originated at milliarcseconds scales. For 18 BL Lacs, the optical continuum emission correlates with the radio emission of the jet at 15 GHz. We suggest that the radio and optical emission are beamed and originate in the innermost part of the sub-parsec-scale jet in quasars. Analysis of the relation between the apparent speed of the jet and the optical nuclear luminosity at 5100 Å supports the relativistic beaming model for the optical emission generated in the jet, and allows the peak values of the intrinsic optical luminosity of the jet and its Lorentz factor to be estimated for the populations of quasars (2×1020 W Hz-1 and γ = 52), BL Lacs (9×1021 W Hz-1 and γ = 20), and radio galaxies (1.5×1021 W Hz-1 and γ = 9). The radio-loudness of quasars (the ratio of 15 GHz flux density and optical nuclear flux at 5100 Å) is found to increase at high redshifts, which is interpreted as progressively higher Doppler factors in radio regime compared to those in optical. A strong positive correlation is found between the intrinsic kinetic power of the jet (measured from the flux density at 151 MHz) and the apparent luminosities of the total and the unresolved core emission of the jet at 15 GHz. This correlation is interpreted in terms of an intrinsically more luminous parsec-scale jet producing more luminous extended structure, which is detectable at low radio frequencies, 151 MHz. A possibility

  7. Compact Detection System for High Sensitivity Hydrogen Profiling of Materials by Nuclear Reaction Analysis

    SciTech Connect

    Marble, Daniel Keith; Urban, Ben; Pacheco, Jose

    2009-03-10

    Hydrogen is a ubiquitous contaminant that is known to have dramatic effects on the electrical, chemical, and mechanical properties of many types of materials in even minute quantities. Thus, the detection of hydrogen in materials is of major importance. Nuclear Reaction Analysis (NRA) is a powerful technique for nondestructive profiling hydrogen in materials. However, NRA has found only limited use in many applications because of poor sensitivity due to cosmic ray background (CSRB). Most attempts to eliminate CSRB to achieve ppm detection levels using higher energy nuclear reactions or tons of passive shielding are not compatible with commercial ion beam analysis space and equipment requirements Zimmerman, et al. have previously reported upon a coincidence detector that meets IBA space requirements and reduces the cosmic ray background, but the detector suffers from lower detection efficiency and small sample size. We have replaced the BGO well detector in the Zimmerman coincidence detection scheme with a larger Nal well detector and used faster timing electronics to produce a detector that can handle larger samples with higher detection efficiency, and still eliminate cosmic ray background.

  8. Soundtracks to Accompany Visualizations of Nuclear Pasta Simulations

    NASA Astrophysics Data System (ADS)

    Clark, Emily

    2014-09-01

    Nuclear pasta is a substance found in neutron stars and core-collapse supernovae, arising at the extreme densities near nuclear saturation, when the attractive nuclear and repulsive coulomb forces mold the dense sea of protons and neutrons into shapes such as spheres, tubes, and slabs, which somewhat resemble different types of pasta. The structures are analyzed using molecular dynamical simulations for different proton fractions, temperatures, densities, and number of nucleons. The system is stressed by stretching it, squeezing it, or subjecting it to some outside force. In order to obtain a more complete representation of how the nuclear pasta responds, sound tracks were produced to accompany videos of stretching simulations. The audio tracks were made by assuming sound waves are produced from changes in the nucleon density. This density was calculated within a small region at frequent time intervals during the run. The resulting sound track was then synced with a video of the run in order to emphasize the development of the system as the pasta moves and breaks. Nuclear pasta is a substance found in neutron stars and core-collapse supernovae, arising at the extreme densities near nuclear saturation, when the attractive nuclear and repulsive coulomb forces mold the dense sea of protons and neutrons into shapes such as spheres, tubes, and slabs, which somewhat resemble different types of pasta. The structures are analyzed using molecular dynamical simulations for different proton fractions, temperatures, densities, and number of nucleons. The system is stressed by stretching it, squeezing it, or subjecting it to some outside force. In order to obtain a more complete representation of how the nuclear pasta responds, sound tracks were produced to accompany videos of stretching simulations. The audio tracks were made by assuming sound waves are produced from changes in the nucleon density. This density was calculated within a small region at frequent time intervals

  9. Retrieval of the thickness of undeformed sea ice from simulated C-band compact polarimetric SAR images

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Dierking, Wolfgang; Zhang, Jie; Meng, Junmin; Lang, Haitao

    2016-07-01

    In this paper we introduce a parameter for the retrieval of the thickness of undeformed first-year sea ice that is specifically adapted to compact polarimetric (CP) synthetic aperture radar (SAR) images. The parameter is denoted as the "CP ratio". In model simulations we investigated the sensitivity of the CP ratio to the dielectric constant, ice thickness, ice surface roughness, and radar incidence angle. From the results of the simulations we deduced optimal sea ice conditions and radar incidence angles for the ice thickness retrieval. C-band SAR data acquired over the Labrador Sea in circular transmit and linear receive (CTLR) mode were generated from RADARSAT-2 quad-polarization images. In comparison with results from helicopter-borne measurements, we tested different empirical equations for the retrieval of ice thickness. An exponential fit between the CP ratio and ice thickness provides the most reliable results. Based on a validation using other compact polarimetric SAR images from the same region, we found a root mean square (rms) error of 8 cm and a maximum correlation coefficient of 0.94 for the retrieval procedure when applying it to level ice between 0.1 and 0.8 m thick.

  10. Leaching and migration of neptunium in a simulated engineered barrier system consisting of HLW glass and compacted bentonite

    NASA Astrophysics Data System (ADS)

    Inagaki, Y.; Furuya, H.; Idemitsu, K.; Arima, T.; Osako, H.; Banba, T.; Maeda, T.; Matsumoto, S.; Nomura, I.; Kikkawa, S.; Saito, M.; Okamoto, H.

    2001-09-01

    In a simulated engineered barrier system consisting of a simulated HLW glass doped with 237Np, a compacted bentonite and water under reducing conditions, leaching of Np from the glass and diffusion of the leached Np through the bentonite were measured systematically. The following results were obtained: (1) The concentration of dissolved species of Np in the leachate is 10 -7-10 -8 M, which indicates that Np(IV) is the dominant oxidation state in the system and the concentration may be controlled by solubility of NpO2xH2O ( am) . (2) The presence of compacted bentonite facilitates reduction of Np(V) to Np(IV) in the system. (3) The apparent diffusion coefficient of the leached Np through the bentonite is evaluated to be lower than 1.5×10 -13 m2/ s, showing that the diffusivity of Np(IV) is more than one order of magnitude lower than that of Np(V).

  11. Interactive Simulation of Nuclear Materials Safeguards and Security

    SciTech Connect

    Stanbro, William D.

    1994-03-14

    THIEF is an interactive computer simulation or computer game of the safeguards and security (S&S) systems of a nuclear facility. The user is placed in the role of a non-violent insider attempting to remove special nuclear material from the facility. All portions of the S&S system that are relevant to the non-violent insider threat are included. The computer operates the S&S systems and attempts to detect the loss of the nuclear material. Both the physical protection system and the materials control and accounting system are modeled. The description of the facility and its S&S systems are defined by the user with the aid of an input module. All aspects of the facility description are provided by the user. The program has a custom graphical user interface to facilitate its use by people with limited computer experience. The custom interface also allows it to run on relatively small computer systems.

  12. Nuclear Engine System Simulation (NESS) version 2.0

    NASA Technical Reports Server (NTRS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman J.

    1993-01-01

    The topics are presented in viewgraph form and include the following; nuclear thermal propulsion (NTP) engine system analysis program development; nuclear thermal propulsion engine analysis capability requirements; team resources used to support NESS development; expanded liquid engine simulations (ELES) computer model; ELES verification examples; NESS program development evolution; past NTP ELES analysis code modifications and verifications; general NTP engine system features modeled by NESS; representative NTP expander, gas generator, and bleed engine system cycles modeled by NESS; NESS program overview; NESS program flow logic; enabler (NERVA type) nuclear thermal rocket engine; prismatic fuel elements and supports; reactor fuel and support element parameters; reactor parameters as a function of thrust level; internal shield sizing; and reactor thermal model.

  13. Dynamic Simulation and Optimization of Nuclear Hydrogen Production Systems

    SciTech Connect

    Paul I. Barton; Mujid S. Kaximi; Georgios Bollas; Patricio Ramirez Munoz

    2009-07-31

    This project is part of a research effort to design a hydrogen plant and its interface with a nuclear reactor. This project developed a dynamic modeling, simulation and optimization environment for nuclear hydrogen production systems. A hybrid discrete/continuous model captures both the continuous dynamics of the nuclear plant, the hydrogen plant, and their interface, along with discrete events such as major upsets. This hybrid model makes us of accurate thermodynamic sub-models for the description of phase and reaction equilibria in the thermochemical reactor. Use of the detailed thermodynamic models will allow researchers to examine the process in detail and have confidence in the accurary of the property package they use.

  14. Material flow simulation in a nuclear chemical process

    SciTech Connect

    Mahgerefteh, M.

    1984-01-01

    At a nuclear fuel reprocessing plant the special nuclear materials (SNM) are received as constituents of spent fuel assemblies, are converted to liquid form, and undergo a series of chemical processes. Uncertainties in measurements of SNM at each stage of reprocessing limit the accuracy of simple material balance accounting as a safeguards method. To be effective, a formal safeguards program must take into account all sources of measurement error yet detect any diversion of SNM. An analytical method for assessing the accountability of selected constituent SNM is demonstrated. A combined discrete-continuous, time-dependent model using the GASP IV simulation language is developed to simulate mass flow, material accountability and measurement error at each stage of the reprocessing plant.

  15. Modeling and Simulation of a Nuclear Fuel Element Test Section

    NASA Technical Reports Server (NTRS)

    Moran, Robert P.; Emrich, William

    2011-01-01

    "The Nuclear Thermal Rocket Element Environmental Simulator" test section closely simulates the internal operating conditions of a thermal nuclear rocket. The purpose of testing is to determine the ideal fuel rod characteristics for optimum thermal heat transfer to their hydrogen cooling/working fluid while still maintaining fuel rod structural integrity. Working fluid exhaust temperatures of up to 5,000 degrees Fahrenheit can be encountered. The exhaust gas is rendered inert and massively reduced in temperature for analysis using a combination of water cooling channels and cool N2 gas injectors in the H2-N2 mixer portion of the test section. An extensive thermal fluid analysis was performed in support of the engineering design of the H2-N2 mixer in order to determine the maximum "mass flow rate"-"operating temperature" curve of the fuel elements hydrogen exhaust gas based on the test facilities available cooling N2 mass flow rate as the limiting factor.

  16. COMPACT STELLAR BINARY ASSEMBLY IN THE FIRST NUCLEAR STAR CLUSTERS AND r-PROCESS SYNTHESIS IN THE EARLY UNIVERSE

    SciTech Connect

    Ramirez-Ruiz, Enrico; MacLeod, Morgan; Trenti, Michele; Roberts, Luke F.; Lee, William H.; Saladino-Rosas, Martha I.

    2015-04-01

    Investigations of elemental abundances in the ancient and most metal deficient stars are extremely important because they serve as tests of variable nucleosynthesis pathways and can provide critical inferences of the type of stars that lived and died before them. The presence of r-process elements in a handful of carbon-enhanced metal-poor (CEMP-r) stars, which are assumed to be closely connected to the chemical yield from the first stars, is hard to reconcile with standard neutron star mergers. Here we show that the production rate of dynamically assembled compact binaries in high-z nuclear star clusters can attain a sufficient high value to be a potential viable source of heavy r-process material in CEMP-r stars. The predicted frequency of such events in the early Galaxy, much lower than the frequency of Type II supernovae but with significantly higher mass ejected per event, can naturally lead to a high level of scatter of Eu as observed in CEMP-r stars.

  17. Adaptive Sampling Algorithms for Probabilistic Risk Assessment of Nuclear Simulations

    SciTech Connect

    Diego Mandelli; Dan Maljovec; Bei Wang; Valerio Pascucci; Peer-Timo Bremer

    2013-09-01

    Nuclear simulations are often computationally expensive, time-consuming, and high-dimensional with respect to the number of input parameters. Thus exploring the space of all possible simulation outcomes is infeasible using finite computing resources. During simulation-based probabilistic risk analysis, it is important to discover the relationship between a potentially large number of input parameters and the output of a simulation using as few simulation trials as possible. This is a typical context for performing adaptive sampling where a few observations are obtained from the simulation, a surrogate model is built to represent the simulation space, and new samples are selected based on the model constructed. The surrogate model is then updated based on the simulation results of the sampled points. In this way, we attempt to gain the most information possible with a small number of carefully selected sampled points, limiting the number of expensive trials needed to understand features of the simulation space. We analyze the specific use case of identifying the limit surface, i.e., the boundaries in the simulation space between system failure and system success. In this study, we explore several techniques for adaptively sampling the parameter space in order to reconstruct the limit surface. We focus on several adaptive sampling schemes. First, we seek to learn a global model of the entire simulation space using prediction models or neighborhood graphs and extract the limit surface as an iso-surface of the global model. Second, we estimate the limit surface by sampling in the neighborhood of the current estimate based on topological segmentations obtained locally. Our techniques draw inspirations from topological structure known as the Morse-Smale complex. We highlight the advantages and disadvantages of using a global prediction model versus local topological view of the simulation space, comparing several different strategies for adaptive sampling in both

  18. INJECTOR PARTICLE SIMULATION AND BEAM TRANSPORT IN A COMPACT LINEAR PROTON ACCELERATOR

    SciTech Connect

    Blackfield, D T; Chen, Y J; Harris, J; Nelson, S; Paul, A; Poole, B

    2007-06-18

    A compact Dielectric Wall Accelerator (DWA), with field gradient up to 100 MW/m is being developed to accelerate proton bunches for use in cancer therapy treatment. The injector must create a proton pulse up to several hundred picoseconds, which is then shaped and accelerated with energies up to 250 MeV. The Particle-In-Cell (PIC) code LSP is used to model several aspects of this design. First, we use LSP to obtain the voltage waveform in the A-K gap that will produce a proton bunch with the requisite charge. We then model pulse compression and shaping in the section between the A-K gap and the DWA. We finally use LSP to model the beam transport through the DWA.

  19. Higher-Order Compact Schemes for Numerical Simulation of Incompressible Flows

    NASA Technical Reports Server (NTRS)

    Wilson, Robert V.; Demuren, Ayodeji O.; Carpenter, Mark

    1998-01-01

    A higher order accurate numerical procedure has been developed for solving incompressible Navier-Stokes equations for 2D or 3D fluid flow problems. It is based on low-storage Runge-Kutta schemes for temporal discretization and fourth and sixth order compact finite-difference schemes for spatial discretization. The particular difficulty of satisfying the divergence-free velocity field required in incompressible fluid flow is resolved by solving a Poisson equation for pressure. It is demonstrated that for consistent global accuracy, it is necessary to employ the same order of accuracy in the discretization of the Poisson equation. Special care is also required to achieve the formal temporal accuracy of the Runge-Kutta schemes. The accuracy of the present procedure is demonstrated by application to several pertinent benchmark problems.

  20. Quantum simulations of nuclei and nuclear pasta with the multiresolution adaptive numerical environment for scientific simulations

    NASA Astrophysics Data System (ADS)

    Sagert, I.; Fann, G. I.; Fattoyev, F. J.; Postnikov, S.; Horowitz, C. J.

    2016-05-01

    Background: Neutron star and supernova matter at densities just below the nuclear matter saturation density is expected to form a lattice of exotic shapes. These so-called nuclear pasta phases are caused by Coulomb frustration. Their elastic and transport properties are believed to play an important role for thermal and magnetic field evolution, rotation, and oscillation of neutron stars. Furthermore, they can impact neutrino opacities in core-collapse supernovae. Purpose: In this work, we present proof-of-principle three-dimensional (3D) Skyrme Hartree-Fock (SHF) simulations of nuclear pasta with the Multi-resolution ADaptive Numerical Environment for Scientific Simulations (MADNESS). Methods: We perform benchmark studies of 16O, 208Pb, and 238U nuclear ground states and calculate binding energies via 3D SHF simulations. Results are compared with experimentally measured binding energies as well as with theoretically predicted values from an established SHF code. The nuclear pasta simulation is initialized in the so-called waffle geometry as obtained by the Indiana University Molecular Dynamics (IUMD) code. The size of the unit cell is 24 fm with an average density of about ρ =0.05 fm-3 , proton fraction of Yp=0.3 , and temperature of T =0 MeV. Results: Our calculations reproduce the binding energies and shapes of light and heavy nuclei with different geometries. For the pasta simulation, we find that the final geometry is very similar to the initial waffle state. We compare calculations with and without spin-orbit forces. We find that while subtle differences are present, the pasta phase remains in the waffle geometry. Conclusions: Within the MADNESS framework, we can successfully perform calculations of inhomogeneous nuclear matter. By using pasta configurations from IUMD it is possible to explore different geometries and test the impact of self-consistent calculations on the latter.

  1. Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model

    USGS Publications Warehouse

    Leake, S.A.; Prudic, David E.

    1991-01-01

    Removal of ground water by pumping from aquifers may result in compaction of compressible fine-grained beds that are within or adjacent to the aquifers. Compaction of the sediments and resulting land subsidence may be permanent if the head declines result in vertical stresses beyond the previous maximum stress. The process of permanent compaction is not routinely included in simulations of ground-water flow. To simulate storage changes from both elastic and inelastic compaction, a computer program was written for use with the U.S. Geological Survey modular finite-difference ground- water flow model. The new program, the Interbed-Storage Package, is designed to be incorporated into this model. In the Interbed-Storage Package, elastic compaction or expansion is assumed to be proportional to change in head. The constant of proportionality is the product of the skeletal component of elastic specific storage and the thickness of the sediments. Similarly, inelastic compaction is assumed to be proportional to decline in head. The constant of proportionality is the product of the skeletal component of inelastic specific storage and the thickness of the sediments. Storage changes are incorporated into the ground-water flow model by adding an additional term to the right-hand side of the flow equation. Within a model time step, the package appropriately apportions storage changes between elastic and inelastic components on the basis of the relation of simulated head to the previous minimum (preconsolidation) head. Two tests were performed to verify that the package works correctly. The first test compared model-calculated storage and compaction changes to hand-calculated values for a three-dimensional simulation. Model and hand-calculated values were essentially equal. The second test was performed to compare the results of the Interbed-Storage Package with results of the one-dimensional Helm compaction model. This test problem simulated compaction in doubly draining

  2. Compact, self-contained enhanced-vision system (EVS) sensor simulator

    NASA Astrophysics Data System (ADS)

    Tiana, Carlo

    2007-04-01

    We describe the model SIM-100 PC-based simulator, for imaging sensors used, or planned for use, in Enhanced Vision System (EVS) applications. Typically housed in a small-form-factor PC, it can be easily integrated into existing out-the-window visual simulators for fixed-wing or rotorcraft, to add realistic sensor imagery to the simulator cockpit. Multiple bands of infrared (short-wave, midwave, extended-midwave and longwave) as well as active millimeter-wave RADAR systems can all be simulated in real time. Various aspects of physical and electronic image formation and processing in the sensor are accurately (and optionally) simulated, including sensor random and fixed pattern noise, dead pixels, blooming, B-C scope transformation (MMWR). The effects of various obscurants (fog, rain, etc.) on the sensor imagery are faithfully represented and can be selected by an operator remotely and in real-time. The images generated by the system are ideally suited for many applications, ranging from sensor development engineering tradeoffs (Field Of View, resolution, etc.), to pilot familiarization and operational training, and certification support. The realistic appearance of the simulated images goes well beyond that of currently deployed systems, and beyond that required by certification authorities; this level of realism will become necessary as operational experience with EVS systems grows.

  3. Aquifer-System Compaction and Land Subsidence: Measurements, Analyses, and Simulations-the Holly Site, Edwards Air Force Base, Antelope Valley, California

    USGS Publications Warehouse

    Sneed, Michelle; Galloway, Devin L.

    2000-01-01

    Land subsidence resulting from ground-water-level declines has long been recognized as a problem in Antelope Valley, California. At Edwards Air Force Base (EAFB), ground-water extractions have caused more than 150 feet of water-level decline, resulting in nearly 4 feet of subsidence. Differential land subsidence has caused sinklike depressions and earth fissures and has accelerated erosion of the playa lakebed surface of Rogers Lake at EAFB, adversely affecting the runways on the lakebed which are used for landing aircraft such as the space shuttles. Since 1990, about 0.4 foot of aquifer-system compaction has been measured at a deep (840 feet) borehole extensometer (Holly site) at EAFB. More than 7 years of paired ground-water-level and aquifer-system compaction measurements made at the Holly site were analyzed for this study. Annually, seasonal water-level fluctuations correspond to steplike variations in aquifer-system compaction; summer water-level drawdowns are associated with larger rates of compaction, and winter water-level recoveries are associated with smaller rates of compaction. The absence of aquifer-system expansion during recovery is consistent with the delayed drainage and resultant delayed, or residual, compaction of thick aquitards. A numerical one-dimensional MODFLOW model of aquitard drainage was used to refine estimates of aquifer-system hydraulic parameters that control compaction and to predict potential future compaction at the Holly site. The analyses and simulations of aquifer-system compaction are based on established theories of aquitard drainage. Historical ground-water-level and land-subsidence data collected near the Holly site were used to constrain simulations of aquifer-system compaction and land subsidence at the site for the period 1908?90, and ground-water-level and aquifer- system compaction measurements collected at the Holly site were used to constrain the model for the period 1990?97. Model results indicate that two thick

  4. Simulating narrow nonlinear resonance features for magnetometry in compact cold atom systems

    NASA Astrophysics Data System (ADS)

    Meyer, David; Robinson, Jenn; Kunz, Paul; Quraishi, Qudsia

    2015-05-01

    We are investigating cold atom magnetometry applications and have developed a numeric model of Electromagnetically Induced Absorption (EIA) and Nonlinear Magneto-Optical Rotation (NMOR) for degenerate two-level systems. While most EIA and NMOR research is done in warm vapors, cold atoms avoid Doppler broadening and better isolate the various optical pumping mechanisms involved. Our model focuses on the effect of transverse magnetic fields on both EIA and NMOR features and shows that critical points of both yield quantitative measures of the magnitude and direction of the transverse field. This dependence reveals the underlying optical pumping mechanisms and makes possible a single, in-situ measurement of the background magnetic field zero to the sub-milligauss level, reducing background fields to enhance sub-Doppler cooling and collectively-enhanced neutral-atom quantum memory lifetimes. Separately, we are pursuing experimental measurements on the relationship between EIA and NMOR in a compact cold atom apparatus. To improve the system's capabilities we are designing our next-generation atom chip to reduce system size and employ versatile geometries enabling multi-site trapping.

  5. A Large-Particle Monte Carlo Code for Simulating Non-Linear High-Energy Processes Near Compact Objects

    NASA Technical Reports Server (NTRS)

    Stern, Boris E.; Svensson, Roland; Begelman, Mitchell C.; Sikora, Marek

    1995-01-01

    High-energy radiation processes in compact cosmic objects are often expected to have a strongly non-linear behavior. Such behavior is shown, for example, by electron-positron pair cascades and the time evolution of relativistic proton distributions in dense radiation fields. Three independent techniques have been developed to simulate these non-linear problems: the kinetic equation approach; the phase-space density (PSD) Monte Carlo method; and the large-particle (LP) Monte Carlo method. In this paper, we present the latest version of the LP method and compare it with the other methods. The efficiency of the method in treating geometrically complex problems is illustrated by showing results of simulations of 1D, 2D and 3D systems. The method is shown to be powerful enough to treat non-spherical geometries, including such effects as bulk motion of the background plasma, reflection of radiation from cold matter, and anisotropic distributions of radiating particles. It can therefore be applied to simulate high-energy processes in such astrophysical systems as accretion discs with coronae, relativistic jets, pulsar magnetospheres and gamma-ray bursts.

  6. Vitamin C supplementation enhances compact morulae formation but reduces the hatching blastocyst rate of bovine somatic cell nuclear transfer embryos.

    PubMed

    Li, Qian; Wang, Yong-Sheng; Wang, Li-Jun; Zhang, Hui; Li, Rui-Zhe; Cui, Chen-Chen; Li, Wen-Zhe; Zhang, Yong; Jin, Ya-Ping

    2014-08-01

    Vitamin C, an antioxidant that reduces reactive oxygen species (ROS) in cells, is capable of significantly improving the developmental competence of porcine and mouse somatic cell nuclear transfer (SCNT) embryos, both in vitro and in vivo. In the present study, the effects of vitamin C on the developmental competence of bovine SCNT embryos were investigated. The results indicated that vitamin C (40 μg/mL) positively affected the scavenging of intracellular ROS, cleavage rate at 24 h (76.67 vs. 68.26%, p<0.05), compact morulae formation (60.83 vs. 51.30%, p<0.05), and the blastomere apoptosis index (3.70 ± 1.41 vs. 4.43% ± 1.65, p<0.05) of bovine SCNT embryos. However, vitamin C supplementation did not significantly affect the blastocyst formation rate and proportion of inner cell mass over total cells per blastocyst on day 7. Moreover, vitamin C supplementation obviously impaired the total cell numbers per blastocyst (97.20 ± 11.35 vs. 88.57 ± 10.43, p<0.05) on day 7 and the hatching blastocysts formation rate on day 9 (26.51 vs. 50.65%, p<0.05) compared with that of the untreated group. Vitamin C supplementation preferentially improved the viability of bovine SCNT embryos prior to the blastocyst stage, but did not enhance the formation and quality of blastocysts in vitro. In conclusion, the effect of vitamin C on the development of bovine SCNT embryos is complex, and vitamin C is not a suitable antioxidant chemical for the in vitro culture of bovine SCNT embryos.

  7. A Compact Code for Simulations of Quantum Error Correction in Classical Computers

    SciTech Connect

    Nyman, Peter

    2009-03-10

    This study considers implementations of error correction in a simulation language on a classical computer. Error correction will be necessarily in quantum computing and quantum information. We will give some examples of the implementations of some error correction codes. These implementations will be made in a more general quantum simulation language on a classical computer in the language Mathematica. The intention of this research is to develop a programming language that is able to make simulations of all quantum algorithms and error corrections in the same framework. The program code implemented on a classical computer will provide a connection between the mathematical formulation of quantum mechanics and computational methods. This gives us a clear uncomplicated language for the implementations of algorithms.

  8. Upgrades to the NESS (Nuclear Engine System Simulation) Code

    NASA Technical Reports Server (NTRS)

    Fittje, James E.

    2007-01-01

    In support of the President's Vision for Space Exploration, the Nuclear Thermal Rocket (NTR) concept is being evaluated as a potential propulsion technology for human expeditions to the moon and Mars. The need for exceptional propulsion system performance in these missions has been documented in numerous studies, and was the primary focus of a considerable effort undertaken during the 1960's and 1970's. The NASA Glenn Research Center is leveraging this past NTR investment in their vehicle concepts and mission analysis studies with the aid of the Nuclear Engine System Simulation (NESS) code. This paper presents the additional capabilities and upgrades made to this code in order to perform higher fidelity NTR propulsion system analysis and design.

  9. Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Upgrade Activities

    NASA Technical Reports Server (NTRS)

    Emrich, William

    2013-01-01

    A key technology element in Nuclear Thermal Propulsion is the development of fuel materials and components which can withstand extremely high temperatures while being exposed to flowing hydrogen. NTREES provides a cost effective method for rapidly screening of candidate fuel components with regard to their viability for use in NTR systems. The NTREES is designed to mimic the conditions (minus the radiation) to which nuclear rocket fuel elements and other components would be subjected to during reactor operation. The NTREES consists of a water cooled ASME code stamped pressure vessel and its associated control hardware and instrumentation coupled with inductive heaters to simulate the heat provided by the fission process. The NTREES has been designed to safely allow hydrogen gas to be injected into internal flow passages of an inductively heated test article mounted in the chamber.

  10. Used nuclear fuel separations process simulation and testing

    SciTech Connect

    Pereira, C.; Krebs, J.F.; Copple, J.M.; Frey, K.E.; Maggos, L.E.; Figueroa, J.; Willit, J.L.; Papadias, D.D.

    2013-07-01

    Recent efforts in separations process simulation at Argonne have expanded from the traditional focus on solvent extraction flowsheet design in order to capture process dynamics and to simulate other components, processing and systems of a used nuclear fuel reprocessing plant. For example, the Argonne Model for Universal Solvent Extraction (AMUSE) code has been enhanced to make it both more portable and more readily extensible. Moving away from a spreadsheet environment makes the addition of new species and processes simpler for the expert user, which should enable more rapid implementation of chemical models that simulate evolving processes. The dyAMUSE (dynamic AMUSE) version allows the simulation of transient behavior across an extractor. Electrochemical separations have now been modeled using spreadsheet codes that simulate the electrochemical recycle of fast reactor fuel. The user can follow the evolution of the salt, products, and waste compositions in the electro-refiner, cathode processors, and drawdown as a function of fuel batches treated. To further expand capabilities in integrating multiple unit operations, a platform for linking mathematical models representing the different operations that comprise a reprocessing facility was adapted to enable systems-level analysis and optimization of facility functions. (authors)

  11. NUCLEAR DATA RESOURCES FOR ADVANCED ANALYSIS AND SIMULATION.

    SciTech Connect

    PRITYCHENKO, B.

    2006-06-05

    The mission of the National Nuclear Data Center (NNDC) includes collection, evaluation, and dissemination of nuclear physics data for basic nuclear research and applied nuclear technologies. In 2004, to answer the needs of nuclear data users, NNDC completed a project to modernize storage and management of its databases and began offering new nuclear data Web services. Examples of nuclear reaction, nuclear structure and decay database applications along with a number of nuclear science codes are also presented.

  12. Verilog-A implementation of a double-gate junctionless compact model for DC circuit simulations

    NASA Astrophysics Data System (ADS)

    Alvarado, J.; Flores, P.; Romero, S.; Ávila-Herrera, F.; González, V.; Soto-Cruz, B. S.; Cerdeira, A.

    2016-07-01

    A physically based model of the double-gate juntionless transistor which is capable of describing accumulation and depletion regions is implemented in Verilog-A in order to perform DC circuit simulations. Analytical description of the difference of potentials between the center and the surface of the silicon layer allows the determination of the mobile charges. Furthermore, mobility degradation, series resistance, as well as threshold voltage roll-off, drain saturation voltage, channel shortening and velocity saturation are also considered. In order to provide this model to all of the community, the implementation of this model is performed in Ngspice, which is a free circuit simulation with an ADMS interface to integrate Verilog-A models. Validation of the model implementation is done through 2D numerical simulations of transistors with 1 μ {{m}} and 40 {{nm}} silicon channel length and 1 × 1019 or 5× {10}18 {{{cm}}}-3 doping concentration of the silicon layer with 10 and 15 {{nm}} silicon thickness. Good agreement between the numerical simulated behavior and model implementation is obtained, where only eight model parameters are used.

  13. Nuclear power plant simulators: their use in operator training and requalification

    SciTech Connect

    Jones, D.W.; Baer, D.K.; Francis, C.C.

    1980-07-01

    This report presents the results of a study performed for the Nuclear Regulatory Commission to evaluate the capabilities and use of nuclear power plant simulators either built or being built by the US nuclear power industry; to determine the adequacy of existing standards for simulator design and for the training of power plant operators on simulators; and to assess the issues about simulator training programs raised by the March 28, 1979, accident at Three Mile Island Unit 2.

  14. Compact electrostatic beam optics for multi-element focused ion beams: simulation and experiments.

    PubMed

    Mathew, Jose V; Bhattacharjee, Sudeep

    2011-01-01

    Electrostatic beam optics for a multi-element focused ion beam (MEFIB) system comprising of a microwave multicusp plasma (ion) source is designed with the help of two widely known and commercially available beam simulation codes: AXCEL-INP and SIMION. The input parameters to the simulations are obtained from experiments carried out in the system. A single and a double Einzel lens system (ELS) with and without beam limiting apertures (S) have been investigated. For a 1 mm beam at the plasma electrode aperture, the rms emittance of the focused ion beam is found to reduce from ∼0.9 mm mrad for single ELS to ∼0.5 mm mrad for a double ELS, when S of 0.5 mm aperture size is employed. The emittance can be further improved to ∼0.1 mm mrad by maintaining S at ground potential, leading to reduction in beam spot size (∼10 μm). The double ELS design is optimized for different electrode geometrical parameters with tolerances of ±1 mm in electrode thickness, electrode aperture, inter electrode distance, and ±1° in electrode angle, providing a robust design. Experimental results obtained with the double ELS for the focused beam current and spot size, agree reasonably well with the simulations.

  15. Compact electrostatic beam optics for multi-element focused ion beams: Simulation and experiments

    SciTech Connect

    Mathew, Jose V.; Bhattacharjee, Sudeep

    2011-01-15

    Electrostatic beam optics for a multi-element focused ion beam (MEFIB) system comprising of a microwave multicusp plasma (ion) source is designed with the help of two widely known and commercially available beam simulation codes: AXCEL-INP and SIMION. The input parameters to the simulations are obtained from experiments carried out in the system. A single and a double Einzel lens system (ELS) with and without beam limiting apertures (S) have been investigated. For a 1 mm beam at the plasma electrode aperture, the rms emittance of the focused ion beam is found to reduce from {approx}0.9 mm mrad for single ELS to {approx}0.5 mm mrad for a double ELS, when S of 0.5 mm aperture size is employed. The emittance can be further improved to {approx}0.1 mm mrad by maintaining S at ground potential, leading to reduction in beam spot size ({approx}10 {mu}m). The double ELS design is optimized for different electrode geometrical parameters with tolerances of {+-}1 mm in electrode thickness, electrode aperture, inter electrode distance, and {+-}1{sup o} in electrode angle, providing a robust design. Experimental results obtained with the double ELS for the focused beam current and spot size, agree reasonably well with the simulations.

  16. Release of boron and cesium or uranium from simulated borosilicate waste glasses through a compacted Ca-bentonite layer

    NASA Astrophysics Data System (ADS)

    Chun, K. S.; Kim, S. S.; Kang, C. H.

    2001-09-01

    The long-term release behavior of some elements from simulated borosilicate waste glasses (S-, K- and A-glass) in contact with a domestic compacted Ca-bentonite block and synthetic granitic groundwater at 80°C under argon atmosphere has been studied by dynamic leach tests since 1997 at KAERI. S- and K-glass differ mainly in their aluminum content, and A-glass contains 19.35 wt% UO 2 instead of fission product elements. Up to the present, the mass loss is almost the same as the normalized boron loss. This means that boron is an indicator on the dissolution of borosilicate waste glass. The leach rates of boron from K- and S-glasses after 861 days were approximately 3.1×10 -2 and 3.0×10 -2 g/ m2 day, respectively. However, the release rates of cesium through the bentonite block from K- and S-glasses were about 1/10th of the release rate of boron, which were almost the same around 2.5×10 -3 g/ m2 day. This may be due to their adsorption on the bentonite. The leach rate of boron from the A-glass was about 5.4×10 -2, but the leach rate of uranium from the A-glass specimen was quite low, below 4×10 -7 g/ m2 day. The low concentration of uranium in the leachates suggests that it hardly moves in a compacted bentonite block. By the EPMA, a yellowish uranium compound was deposited on the surface of the bentonite in contact with the A-glass specimen. The species of this phase should be identified to understand the release mechanism of uranium.

  17. Interactive Simulation of Nuclear Materials Safeguards and Security

    1994-03-14

    THIEF is an interactive computer simulation or computer game of the safeguards and security (S&S) systems of a nuclear facility. The user is placed in the role of a non-violent insider attempting to remove special nuclear material from the facility. All portions of the S&S system that are relevant to the non-violent insider threat are included. The computer operates the S&S systems and attempts to detect the loss of the nuclear material. Both the physicalmore » protection system and the materials control and accounting system are modeled. The description of the facility and its S&S systems are defined by the user with the aid of an input module. All aspects of the facility description are provided by the user. The program has a custom graphical user interface to facilitate its use by people with limited computer experience. The custom interface also allows it to run on relatively small computer systems.« less

  18. Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model

    USGS Publications Warehouse

    Leake, S.A.; Prudic, David E.

    1988-01-01

    The process of permanent compaction is not routinely included in simulations of groundwater flow. To simulate storage changes from both elastic and inelastic compaction, a computer program was written for use with the U. S. Geological Survey modular finite-difference groundwater flow model. The new program is called the Interbed-Storage Package. In the Interbed-Storage Package, elastic compaction or expansion is assumed to be proportional to change in head. The constant of proportionality is the product of skeletal component of elastic specific storage and thickness of the sediments. Similarly, inelastic compaction is assumed to be proportional to decline in head. The constant of proportionality is the product of the skeletal component of inelastic specific storage and the thickness of the sediments. Storage changes are incorporated into the groundwater flow model by adding an additional term to the flow equation. Within a model time step, the package appropriately apportions storage changes between elastic and inelastic components on the basis of the relation of simulated head to the previous minimum head. Another package that allows for a time-varying specified-head boundary is also documented. This package was written to reduce the data requirements for test simulations of the Interbed-Storage Package. (USGS)

  19. THIEF: An interactive simulation of nuclear materials safeguards

    SciTech Connect

    Stanbro, W. D.

    1990-01-01

    The safeguards community is facing an era in which it will be called upon to tighten protection of nuclear material. At the same time, it is probable that safeguards will face more competition for available resources from other activities such as environmental cleanup. To exist in this era, it will be necessary to understand and coordinate all aspects of the safeguards system. Because of the complexity of the interactions involved, this process puts a severe burden on designers and operators of safeguards systems. This paper presents a simulation tool developed at the Los Alamos National Laboratory to allow users to examine the interactions among safeguards elements as they apply to combating the insider threat. The tool consists of a microcomputer-based simulation in which the user takes the role of the insider trying to remove nuclear material from a facility. The safeguards system is run by the computer and consists of both physical protection and MC A computer elements. All data elements describing a scenario can be altered by the user. The program can aid in training, as well as in developing threat scenarios. 4 refs.

  20. VISION - Verifiable Fuel Cycle Simulation of Nuclear Fuel Cycle Dynamics

    SciTech Connect

    Steven J. Piet; A. M. Yacout; J. J. Jacobson; C. Laws; G. E. Matthern; D. E. Shropshire

    2006-02-01

    The U.S. DOE Advanced Fuel Cycle Initiative’s (AFCI) fundamental objective is to provide technology options that - if implemented - would enable long-term growth of nuclear power while improving sustainability and energy security. The AFCI organization structure consists of four areas; Systems Analysis, Fuels, Separations and Transmutations. The Systems Analysis Working Group is tasked with bridging the program technical areas and providing the models, tools, and analyses required to assess the feasibility of design and deployment options and inform key decision makers. An integral part of the Systems Analysis tool set is the development of a system level model that can be used to examine the implications of the different mixes of reactors, implications of fuel reprocessing, impact of deployment technologies, as well as potential "exit" or "off ramp" approaches to phase out technologies, waste management issues and long-term repository needs. The Verifiable Fuel Cycle Simulation Model (VISION) is a computer-based simulation model that allows performing dynamic simulations of fuel cycles to quantify infrastructure requirements and identify key trade-offs between alternatives. It is based on the current AFCI system analysis tool "DYMOND-US" functionalities in addition to economics, isotopic decay, and other new functionalities. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI and Generation IV reactor development studies.

  1. Three Dimensional Simulation of the Baneberry Nuclear Event

    SciTech Connect

    Lomov, I

    2003-07-16

    Baneberry, a 10-kiloton nuclear event, was detonated at a depth of 278 m at the Nevada Test Site on December 18, 1970. Shortly after detonation, radioactive gases emanating from the cavity were released into the atmosphere through a shock-induced fissure near surface ground zero. Extensive geophysical investigations, coupled with a series of 1D and 2D computational studies were used to reconstruct the sequence of events that led to the catastrophic failure. However, the geological profile of the Baneberry site is complex and inherently three-dimensional, which meant that some geological features had to be simplified or ignored in the 2D simulations. This left open the possibility that features unaccounted for in the 2D simulations could have had an important influence on the eventual containment failure of the Baneberry event. This paper presents results from a high-fidelity 3D Baneberry simulation based on the most accurate geologic and geophysical data available. The results are compared with available data, and contrasted against the results of the previous 2D computational studies.

  2. HYDRODYNAMICAL SIMULATIONS OF A COMPACT SOURCE SCENARIO FOR THE GALACTIC CENTER CLOUD G2

    SciTech Connect

    Ballone, A.; Schartmann, M.; Burkert, A.; Gillessen, S.; Genzel, R.; Fritz, T. K.; Eisenhauer, F.; Pfuhl, O.; Ott, T.

    2013-10-10

    The origin of the dense gas cloud G2 discovered in the Galactic Center is still a debated puzzle. G2 might be a diffuse cloud or the result of an outflow from an invisible star embedded in it. We present hydrodynamical simulations of the evolution of different spherically symmetric winds of a stellar object embedded in G2. We find that the interaction with the ambient medium and the extreme gravitational field of the supermassive black hole in the Galactic Center must be taken into account in such a source scenario. The thermal pressure of the hot and dense atmosphere confines the wind, while its ram pressure shapes it via stripping along the orbit, with the details depending on the wind parameters. Tidal forces squeeze the wind near pericenter, reducing it to a thin and elongated filament. We also find that in this scenario most of the Brγ luminosity is expected to come from the densest part of the wind, which has a highly filamentary structure with a low filling factor. For our assumed atmosphere, the observations can be best matched by a mass outflow rate of M-dot{sub w}=8.8×10{sup -8} M{sub sun} yr{sup -1} and a wind velocity of v{sub w} = 50 km s{sup –1}. These values are comparable with those of a young T Tauri star wind, as already suggested by Scoville and Burkert.

  3. Initial Operation of the Nuclear Thermal Rocket Element Environmental Simulator

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.; Pearson, J. Boise; Schoenfeld, Michael P.

    2015-01-01

    The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) facility is designed to perform realistic non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and fuel materials. Although the NTREES facility cannot mimic the neutron and gamma environment of an operating NTR, it can simulate the thermal hydraulic environment within an NTR fuel element to provide critical information on material performance and compatibility. The NTREES facility has recently been upgraded such that the power capabilities of the facility have been increased significantly. At its present 1.2 MW power level, more prototypical fuel element temperatures nay now be reached. The new 1.2 MW induction heater consists of three physical units consisting of a transformer, rectifier, and inverter. This multiunit arrangement facilitated increasing the flexibility of the induction heater by more easily allowing variable frequency operation. Frequency ranges between 20 and 60 kHz can accommodated in the new induction heater allowing more representative power distributions to be generated within the test elements. The water cooling system was also upgraded to so as to be capable of removing 100% of the heat generated during testing In this new higher power configuration, NTREES will be capable of testing fuel elements and fuel materials at near-prototypic power densities. As checkout testing progressed and as higher power levels were achieved, several design deficiencies were discovered and fixed. Most of these design deficiencies were related to stray RF energy causing various components to encounter unexpected heating. Copper shielding around these components largely eliminated these problems. Other problems encountered involved unexpected movement in the coil due to electromagnetic forces and electrical arcing between the coil and a dummy test article. The coil movement and arcing which were encountered during the checkout testing effectively destroyed the induction coil in use at

  4. Chavir: Virtual reality simulation for interventions in nuclear installations

    SciTech Connect

    Thevenon, J. B.; Tirel, O.; Lopez, L.; Chodorge, L.; Desbats, P.

    2006-07-01

    Companies involved in the nuclear industry have to prepare for interventions by precisely analyzing the radiological risks and rapidly evaluating the consequences of their operational choices. They also need to consolidate the experiences gained in the field with greater responsiveness and lower costs. This paper brings out the advantages of using virtual reality technology to meet the demands in the industry. The CHAVIR software allows the operators to prepare (and repeat) all the operations they would have to do in a safe virtual world, before performing the actual work inside the facilities. Since the decommissioning or maintenance work is carried out in an environment where there is radiation, the amount of radiation that the operator would be exposed to is calculated and integrated into the simulator. (authors)

  5. Chemical durability of simulated nuclear glasses containing water

    SciTech Connect

    Li, H.; Tomozawa, M.

    1995-04-01

    The chemical durability of simulated nuclear waste glasses having different water contents was studied. Results from the product consistency test (PCT) showed that glass dissolution increased with water content in the glass. This trend was not observed during MCC-1 testing. This difference was attributed to the differences in reactions between glass and water. In the PCT, the glass network dissolution controlled the elemental releases, and water in the glass accelerated the reaction rate. On the other hand, alkali ion exchange with hydronium played an important role in the MCC-1. For the latter, the amount of water introduced into a leached layer from ion-exchange was found to be much greater than that of initially incorporated water in the glass. Hence, the initial water content has no effect on glass dissolution as measured by the MCC-1 test.

  6. Adaptive low Mach number simulations of nuclear flame microphysics

    SciTech Connect

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.A.

    2003-03-20

    We introduce a numerical model for the simulation of nuclear flames in Type Ia supernovae. This model is based on a low Mach number formulation that analytically removes acoustic wave propagation while retaining the compressibility effects resulting from nuclear burning. The formulation presented here generalizes low Mach number models used in combustion that are based on an ideal gas approximation to the arbitrary equations of state such as those describing the degenerate matter found in stellar material. The low Mach number formulation permits time steps that are controlled by the advective time scales resulting in a substantial improvement in computational efficiency compared to a compressible formulation. We briefly discuss the basic discretization methodology for the low Mach number equations and their implementation in an adaptive projection framework. We present validation computations in which the computational results from the low Mach number model are compared to a compressible code and present an application of the methodology to the Landau-Darrieus instability of a carbon flame.

  7. Ester-linked hen egg white lysozyme shows a compact fold in a molecular dynamics simulation - possible causes and sensitivity of experimentally observable quantities to structural changes maintaining this compact fold.

    PubMed

    Eichenberger, Andreas P; Smith, Lorna J; van Gunsteren, Wilfred F

    2012-01-01

    Prediction and understanding of the folding and stability of the 3D structure of proteins is still a challenge. The different atomic interactions, such as non polar contacts and hydrogen bonding, are known but their exact relative weights and roles when contributing to protein folding and stability are not identified. Initiated by a previous molecular dynamics simulation of fully ester-linked hen egg white lysozyme (HEWL), which showed a more compact fold of the ester-linked molecule compared to the native one, three variants of this protein are analyzed in the present study. These are 129-residue native HEWL, partly ester-linked HEWL, in which only 34 peptide linkages that are not involved in the helical or β-strand parts of native HEWL were replaced by ester linkages, and fully (126 residues) ester-linked HEWL. Native and partly ester-linked HEWL showed comparable behaviour, whereas fully ester-linked HEWL could not maintain the native secondary structure of HEWL in the simulation and adopted a more compact fold. The conformational changes were analyzed by comparing simulation averaged values of quantities that can be measured by NMR, such as (1)H-(15)N backbone order parameters, residual dipolar couplings, proton-proton NOE distances and (3)J-couplings with the corresponding values derived from experimental NMR data for native HEWL. The information content of the latter appeared to be insufficient to detect the local conformational rearrangements upon esterification of the loop regions of the protein. For fully ester-linked HEWL, a significantly reduced agreement was observed. Upon esterification, the backbone-side chain and side chain-side chain hydrogen-bonding pattern of HEWL changes to maintain its compactness and thus the structural stability of the ester-linked lysozymes. PMID:22093234

  8. Analysis by simulation of the disposition of nuclear fuel waste

    SciTech Connect

    Turek, J.L.

    1980-09-01

    A descriptive simulation model is developed which includes all aspects of nuclear waste disposition. The model is comprised of two systems, the second system orchestrated by GASP IV. A spent fuel generation prediction module is interfaced with the AFR Program Management Information System and a repository scheduling information module. The user is permitted a wide range of options with which to tailor the simulation to any desired storage scenario. The model projects storage requirements through the year 2020. The outputs are evaluations of the impact that alternative decision policies and milestone date changes have on the demand for, the availability of, and the utilization of spent fuel storage capacities. Both graphs and detailed listings are available. These outputs give a comprehensive view of the particular scenario under observation, including the tracking, by year, of each discharge from every reactor. Included within the work is a review of the status of spent fuel disposition based on input data accurate as of August 1980. The results indicate that some temporary storage techniques (e.g., transshipment of fuel and/or additional at-reactor storage pools) must be utilized to prevent reactor shutdowns. These techniques will be required until the 1990's when several AFR facilities, and possibly one repository, can become operational.

  9. Recent Improvement of Measurement Instrumentation to Supervise Nuclear Operations and to Contribute Input Data to 3D Simulation Code - 13289

    SciTech Connect

    Mahe, Charly; Chabal, Caroline

    2013-07-01

    The CEA has developed many compact characterization tools to follow sensitive operations in a nuclear environment. Usually, these devices are made to carry out radiological inventories, to prepare nuclear interventions or to supervise some special operations. These in situ measurement techniques mainly take place at different stages of clean-up operations and decommissioning projects, but they are also in use to supervise sensitive operations when the nuclear plant is still operating. In addition to this, such tools are often associated with robots to access very highly radioactive areas, and thus can be used in accident situations. Last but not least, the radiological data collected can be entered in 3D calculation codes used to simulate the doses absorbed by workers in real time during operations in a nuclear environment. Faced with these ever-greater needs, nuclear measurement instrumentation always has to involve on-going improvement processes. Firstly, this paper will describe the latest developments and results obtained in both gamma and alpha imaging techniques. The gamma camera has been used by the CEA since the 1990's and several changes have made this device more sensitive, more compact and more competitive for nuclear plant operations. It is used to quickly identify hot spots, locating irradiating sources from 50 keV to 1500 keV. Several examples from a wide field of applications will be presented, together with the very latest developments. The alpha camera is a new camera used to see invisible alpha contamination on several kinds of surfaces. The latest results obtained allow real time supervision of a glove box cleaning operation (for {sup 241}Am contamination). The detection principle as well as the main trials and results obtained will be presented. Secondly, this paper will focus on in situ gamma spectrometry methods developed by the CEA with compact gamma spectrometry probes (CdZnTe, LaBr{sub 3}, NaI, etc.). The radiological data collected is used

  10. Sub-saturation matter in compact stars: Nuclear modelling in the framework of the extended Thomas-Fermi theory

    SciTech Connect

    Aymard, François; Gulminelli, Francesca; Margueron, Jérôme

    2015-02-24

    A recently introduced analytical model for the nuclear density profile [1] is implemented in the Extended Thomas-Fermi (ETF) energy density functional. This allows to (i) shed a new light on the issue of the sign of surface symmetry energy in nuclear mass formulas, as well as to (ii) show the importance of the in-medium corrections to the nuclear cluster energies in thermodynamic conditions relevant for the description of core-collapse supernovae and (proto)-neutron star crust.

  11. High-Fidelity Space-Time Adaptive Multiphysics Simulations in Nuclear Engineering

    SciTech Connect

    Solin, Pavel; Ragusa, Jean

    2014-03-09

    We delivered a series of fundamentally new computational technologies that have the potential to significantly advance the state-of-the-art of computer simulations of transient multiphysics nuclear reactor processes. These methods were implemented in the form of a C++ library, and applied to a number of multiphysics coupled problems relevant to nuclear reactor simulations.

  12. Nuclear Engine System Simulation (NESS). Volume 1: Program user's guide

    NASA Technical Reports Server (NTRS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman J.

    1993-01-01

    A Nuclear Thermal Propulsion (NTP) engine system design analysis tool is required to support current and future Space Exploration Initiative (SEI) propulsion and vehicle design studies. Currently available NTP engine design models are those developed during the NERVA program in the 1960's and early 1970's and are highly unique to that design or are modifications of current liquid propulsion system design models. To date, NTP engine-based liquid design models lack integrated design of key NTP engine design features in the areas of reactor, shielding, multi-propellant capability, and multi-redundant pump feed fuel systems. Additionally, since the SEI effort is in the initial development stage, a robust, verified NTP analysis design tool could be of great use to the community. This effort developed an NTP engine system design analysis program (tool), known as the Nuclear Engine System Simulation (NESS) program, to support ongoing and future engine system and stage design study efforts. In this effort, Science Applications International Corporation's (SAIC) NTP version of the Expanded Liquid Engine Simulation (ELES) program was modified extensively to include Westinghouse Electric Corporation's near-term solid-core reactor design model. The ELES program has extensive capability to conduct preliminary system design analysis of liquid rocket systems and vehicles. The program is modular in nature and is versatile in terms of modeling state-of-the-art component and system options as discussed. The Westinghouse reactor design model, which was integrated in the NESS program, is based on the near-term solid-core ENABLER NTP reactor design concept. This program is now capable of accurately modeling (characterizing) a complete near-term solid-core NTP engine system in great detail, for a number of design options, in an efficient manner. The following discussion summarizes the overall analysis methodology, key assumptions, and capabilities associated with the NESS presents an

  13. MCNP Simulations of Measurement of Insulation Compaction in the Cryogenic Rocket Fuel Tanks at Kennedy Space Center by Fast/Thermal Neutron Techniques

    NASA Technical Reports Server (NTRS)

    Livingston, R. A.; Schweitzer, J. S.; Parsons, A. M.; Arens, E. E.

    2010-01-01

    MCNP simulations have been run to evaluate the feasibility of using a combination of fast and thermal neutrons as a nondestructive method to measure of the compaction of the perlite insulation in the liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC). Perlite is a feldspathic volcanic rock made up of the major elements Si, AI, Na, K and 0 along with some water. When heated it expands from four to twenty times its original volume which makes it very useful for thermal insulation. The cryogenic tanks at Kennedy Space Center are spherical with outer diameters of 69-70 feet and lined with a layer of expanded perlite with thicknesses on the order of 120 cm. There is evidence that some of the perlite has compacted over time since the tanks were built 1965, affecting the thermal properties and possibly also the structural integrity of the tanks. With commercially available portable neutron generators it is possible to produce simultaneously fluxes of neutrons in two energy ranges: fast (14 Me V) and thermal (25 me V). The two energy ranges produce complementary information. Fast neutrons produce gamma rays by inelastic scattering, which is sensitive to Fe and O. Thermal neutrons produce gamma rays by prompt gamma neutron activation (PGNA) and this is sensitive to Si, Al, Na, K and H. The compaction of the perlite can be measured by the change in gamma ray signal strength which is proportional to the atomic number densities of the constituent elements. The MCNP simulations were made to determine the magnitude of this change. The tank wall was approximated by a I-dimensional slab geometry with an 11/16" outer carbon steel wall, an inner stainless wall and 120 cm thick perlite zone. Runs were made for cases with expanded perlite, compacted perlite or with various void fractions. Runs were also made to simulate the effect of adding a moderator. Tallies were made for decay-time analysis from t=0 to 10 ms; total detected gamma

  14. Separation of technetium from nuclear waste stream simulants. Final report

    SciTech Connect

    Strauss, S.H.

    1995-09-11

    The author studied liquid anion exchangers, such as Aliquat-336 nitrate, various pyridinium nitrates, and related salts, so that they may be applied toward a specific process for extracting (partitioning) and recovering {sup 99}TcO{sub 4}{sup {minus}} from nuclear waste streams. Many of the waste streams are caustic and contain a variety of other ions. For this reason, the author studied waste stream simulants that are caustic and contain appropriate concentrations of selected, relevant ions. Methods of measuring the performance of the exchangers and extractant systems included contact experiments. Batch contact experiments were used to determine the forward and reverse extraction parameters as a function of temperature, contact time, phase ratio, concentration, solvent (diluent), and other physical properties. They were also used for stability and competition studies. Specifically, the author investigated the solvent extraction behavior of salts of perrhenate (ReO{sub 4}{sup {minus}}), a stable (non-radioactive) chemical surrogate for {sup 99}TcO{sub 4}{sup {minus}}. Results are discussed for alternate organic solvents; metalloporphyrins, ferrocenes, and N-cetyl pyridium nitrate as alternate extractant salts; electroactive polymers; and recovery of ReO{sub 4}{sup {minus}} and TcO{sub 4}{sup {minus}}.

  15. Compaction properties of isomalt.

    PubMed

    Bolhuis, Gerad K; Engelhart, Jeffrey J P; Eissens, Anko C

    2009-08-01

    Although other polyols have been described extensively as filler-binders in direct compaction of tablets, the polyol isomalt is rather unknown as pharmaceutical excipient, in spite of its description in all the main pharmacopoeias. In this paper the compaction properties of different types of ispomalt were studied. The types used were the standard product sieved isomalt, milled isomalt and two types of agglomerated isomalt with a different ratio between 6-O-alpha-d-glucopyranosyl-d-sorbitol (GPS) and 1-O-alpha-d-glucopyranosyl-d-mannitol dihydrate (GPM). Powder flow properties, specific surface area and densities of the different types were investigated. Compactibility was investigated by compression of the tablets on a compaction simulator, simulating the compression on high-speed tabletting machines. Lubricant sensitivity was measured by compressing unlubricated tablets and tablets lubricated with 1% magnesium stearate on an instrumented hydraulic press. Sieved isomalt had excellent flow properties but the compactibility was found to be poor whereas the lubricant sensitivity was high. Milling resulted in both a strong increase in compactibility as an effect of the higher surface area for bonding and a decrease in lubricant sensitivity as an effect of the higher surface area to be coated with magnesium stearate. However, the flow properties of milled isomalt were too bad for use as filler-binder in direct compaction. Just as could be expected, agglomeration of milled isomalt by fluid bed agglomeration improved flowability. The good compaction properties and the low lubricant sensitivity were maintained. This effect is caused by an early fragmentation of the agglomerated material during the compaction process, producing clean, lubricant-free particles and a high surface for bonding. The different GPS/GPM ratios of the agglomerated isomalt types studied had no significant effect on the compaction properties. PMID:19327398

  16. Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Upgrade Activities

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.

    2014-01-01

    Over the past year the Nuclear Thermal Rocket Element Environmental Simulator (NTREES) has been undergoing a significant upgrade beyond its initial configuration. The NTREES facility is designed to perform realistic non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and fuel materials. Although the NTREES facility cannot mimic the neutron and gamma environment of an operating NTR, it can simulate the thermal hydraulic environment within an NTR fuel element to provide critical information on material performance and compatibility. The first phase of the upgrade activities which was completed in 2012 in part consisted of an extensive modification to the hydrogen system to permit computer controlled operations outside the building through the use of pneumatically operated variable position valves. This setup also allows the hydrogen flow rate to be increased to over 200 g/sec and reduced the operation complexity of the system. The second stage of modifications to NTREES which has just been completed expands the capabilities of the facility significantly. In particular, the previous 50 kW induction power supply has been replaced with a 1.2 MW unit which should allow more prototypical fuel element temperatures to be reached. The water cooling system was also upgraded to so as to be capable of removing 100% of the heat generated during. This new setup required that the NTREES vessel be raised onto a platform along with most of its associated gas and vent lines. In this arrangement, the induction heater and water systems are now located underneath the platform. In this new configuration, the 1.2 MW NTREES induction heater will be capable of testing fuel elements and fuel materials in flowing hydrogen at pressures up to 1000 psi at temperatures up to and beyond 3000 K and at near-prototypic reactor channel power densities. NTREES is also capable of testing potential fuel elements with a variety of propellants, including hydrogen with additives to inhibit

  17. Compact Reactor

    SciTech Connect

    Williams, Pharis E.

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  18. Thermal Simulator Development: Non-Nuclear Testing of Space Fission Systems

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Dickens, Ricky E.

    2006-01-01

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power system. At the NASA MSFC Early Flight Fission Test Facility (EFF-TF), highly designed electric heaters are used to simulate the heat from nuclear fuel to test space fission power and propulsion systems. To allow early utilization, nuclear system designs must be relatively simple, easy to fabricate, and easy to test using non-nuclear heaters to closely mimic heat from fission. In this test strategy, highly designed electric heaters are used to simulate the heat from nuclear fuel, allowing one to develop a significant understanding of individual components and integrated system operation without the cost, time and safety concerns associated with nuclear testing.

  19. Compact ultradense matter impactors.

    PubMed

    Rafelski, Johann; Labun, Lance; Birrell, Jeremiah

    2013-03-15

    We study interactions of meteorlike compact ultradense objects (CUDO), having nuclear or greater density, with Earth and other rocky bodies in the Solar System as a possible source of information about novel forms of matter. We study the energy loss in CUDO puncture of the body and discuss differences between regular matter and CUDO impacts.

  20. Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon; Dickens, Ricky; Dixon, David

    2007-01-01

    This viewgraph presentation reviews the development of a simulator for non-nuclear tests for the development of a space nuclear power system. The development of the Instrumented Thermal Simulator is to assist in developing an understanding of individual components and integrated system operation without the cost, time, safety concerns associated with nuclear testing. The presentation shows the design, the electrical integration, the hardware, and the assembly of the simulators. There are slides that show the test plan, the analysis, and the initial results.

  1. Searching for gravitational-waves from compact binary coalescences while dealing with challenges of real data and simulated waveforms

    NASA Astrophysics Data System (ADS)

    Dayanga, Waduthanthree Thilina

    Albert Einstein's general theory of relativity predicts the existence of gravitational waves (GWs). Direct detection of GWs will provide enormous amount of new information about physics, astronomy and cosmology. Scientists around the world are currently working towards the first direct detection of GWs. The global network of ground-based GW detectors are currently preparing for their first advanced detector Science runs. In this thesis we focus on detection of GWs from compact binary coalescence (CBC) systems. Ability to accurately model CBC GW waveforms makes them the most promising source for the first direct detection of GWs. In this thesis we try to address several challenges associated with detecting CBC signals buried in ground-based GW detector data for past and future searches. Data analysis techniques we employ to detect GW signals assume detector noise is Gaussian and stationary. However, in reality, detector data is neither Gaussian nor stationary. To estimate the performance loss due to these features, we compare the efficiencies of detecting CBC signals in simulated Gaussian and real data. Additionally, we also demonstrate the effectiveness of multi-detector signal based consistency tests such ad null-stream. Despite, non-Gaussian and non-stationary features of real detector data, with effective data quality studies and signal-based vetoes we can approach the performance of Gaussian and stationary data. As we are moving towards advanced detector era, it is important to be prepared for future CBC searches. In this thesis we investigate the performances of non-spinning binary black hole (BBH) searches in simulated Gaussian using advanced detector noise curves predicted for 2015--2016. In the same study, we analyze the GW detection probabilities of latest pN-NR hybrid waveforms submitted to second version of Numerical Injection Analysis (NINJA-2) project. The main motivation for this study is to understand the ability to detect realistic BBH signals of

  2. High Fidelity Thermal Simulators for Non-Nuclear Testing: Analysis and Initial Results

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David

    2007-01-01

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power system, providing system characterization data and allowing one to work through various fabrication, assembly and integration issues without the cost and time associated with a full ground nuclear test. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Testing with non-optimized heater elements allows one to assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. High fidelity thermal simulators that match both the static and the dynamic fuel pin performance that would be observed in an operating, fueled nuclear reactor can vastly increase the value of non-nuclear test results. With optimized simulators, the integration of thermal hydraulic hardware tests with simulated neutronie response provides a bridge between electrically heated testing and fueled nuclear testing, providing a better assessment of system integration issues, characterization of integrated system response times and response characteristics, and assessment of potential design improvements' at a relatively small fiscal investment. Initial conceptual thermal simulator designs are determined by simple one-dimensional analysis at a single axial location and at steady state conditions; feasible concepts are then input into a detailed three-dimensional model for comparison to expected fuel pin performance. Static and dynamic fuel pin performance for a proposed reactor design is determined using SINDA/FLUINT thermal analysis software, and comparison is made between the expected nuclear performance and the performance of conceptual thermal simulator designs. Through a series of iterative analyses, a conceptual high fidelity design can developed. Test results presented in this paper correspond to a "first cut" simulator design for a potential

  3. VIBRATION COMPACTION

    DOEpatents

    Hauth, J.J.

    1962-07-01

    A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

  4. Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, S. M.; Farmer, J.; Dixon, D.; Kapernick, R.; Dickens, R.; Adams, M.

    2007-01-01

    Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Work at the NASA Marshall Space Flight Center seeks to develop high fidelity thermal simulators that not only match the static power profile that would be observed in an operating, fueled nuclear reactor, but to also match the dynamic fuel pin performance during feasible transients. Comparison between the fuel pins and thermal simulators is made at the fuel clad surface, which corresponds to the sheath surface in the thermal simulator. Static and dynamic fuel pin performance was determined using SINDA-FLUINT analysis, and the performance of conceptual thermal simulator designs was compared to the expected nuclear performance. Through a series of iterative analysis, a conceptual high fidelity design will be developed, followed by engineering design, fabrication, and testing to validate the overall design process. Although the resulting thermal simulator will be designed for a specific reactor concept, establishing this rigorous design process will assist in streamlining the thermal simulator development for other reactor concepts.

  5. Initial Operation and Shakedown of the Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Emrich, William J., Jr.

    2014-01-01

    To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Prototypical fuel elements mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission in addition to being exposed to flowing hydrogen. Recent upgrades to NTREES now allow power levels 24 times greater than those achievable in the previous facility configuration. This higher power operation will allow near prototypical power densities and flows to finally be achieved in most prototypical fuel elements.

  6. Redox of Simulated Nuclear Waste Glass Forming Melts

    SciTech Connect

    Vick, Sara C.; Sundaram, S. K.

    2001-12-01

    Glasses are found in most reduction-oxidation (redox) items that are used everyday; from automobiles to planes. With stability of most glasses, they are being used to store hazardous waste materials. Many elements have different oxidation states and are found in multiple states in glasses. Redox of glasses has significant effect on processing of waste glass melts in melters as well as properties of the waste forms. Nuclear waste glasses generally have complex chemistry (including several redox ions) and form corrosive melts. Basic objective: study the redox of the glasses containing Fe and Ni with square wave voltammetry. A basic simulated frit glass was used for vitrification. The frit composition used was 57.90% SiO2, 17.70% Na2O, 14.70% B2O3, 5.70% Li2O, 2.00% MgO, 1.00% TiO2, 0.50% ZrO2, and 0.50% La2O3. Batch glasses were synthesized and then dopants of Fe2O3 , NiO, and a combination of Fe2O3-NiO were added in 1-wt % amounts. The glass was melted at 1150 C and held for 24 hours. It was poured to the top of a medium sized Pt/Rh crucible and placed in a furnace at 1150 C. The glass powder was allowed to melt for five minutes before the testing apparatus was placed in the melt. The testing apparatus was composed of a Pt/Rh working electrode, Pt/Rh counter electrode, and a Zr/Al reference electrode. The counter electrode is placed in the melt until it is touching the bottom of the crucible creating a closed circuit. Both the reference electrode and working electrode are located half way down the counter electrode. The test showed that melt resistivity was high indicating the amount of conductivity in the melt. Sample melt volume and area of the working electrode were high. Adjusting the crucible size and sizing other electrodes will improve the measurements. Future work: testing NiO glass and Fe2O3-NiO glass to see the interaction between the Fe and the Ni and synthesis of 2 wt %, 3 wt %, and 5-wt % Fe2O3 doped glasses to study effects of Fe concentration.

  7. NASTRAN Analysis Comparison to Shock Tube Tests Used to Simulate Nuclear Overpressures

    NASA Technical Reports Server (NTRS)

    Wheless, T. K.

    1985-01-01

    This report presents a study of the effectiveness of the NASTRAN computer code for predicting structural response to nuclear blast overpressures. NASTRAN's effectiveness is determined by comparing results against shock tube tests used to simulate nuclear overpressures. Seven panels of various configurations are compared in this study. Panel deflections are the criteria used to measure NASTRAN's effectiveness. This study is a result of needed improvements in the survivability/vulnerability analyses subjected to nuclear blast.

  8. Design and characterization of a compact multi-detector gamma spectrometer for studies of triggered energy release from nuclear isomers

    NASA Astrophysics Data System (ADS)

    Ugorowski, Philip; Propri, Ronald J.; Caldwell, Nathan; Lazich, Joseph; Carroll, James J.

    2004-10-01

    Nuclear Isomers are long-lived nuclear excited states, with lifetimes ranging up to decades or longer. Recently, attention has focused on the second isomeric state of 178-Hf (31-year natural half-life). The spontaneous decay takes the form of a cascade of gamma photons, totaling 2.45 MeV of energy per nucleus and corresponding to an energy density of 1.3 GigaJoules/gram. Since the ground state is stable, there is no radioactive residue and the 2.4 MeV therefore represents a ``clean'' release of energy. It has been suggested that isomers like this could be used for applications and that would require some means of causing an energy release upon demand. Thus, experiments have been performed to determine the cross-sections for x-ray induced decay, if it occurs. Positive indications by one group have been plagued by poor statistical accuracy in looking for triggered increases in the numbers of photons that correspond to the natural decay cascades. A refined technique based on calorimetry of gamma cascades has been devised to avoid these problems and a portable multi-detector array has been constructed for this purpose. This talk will discuss the design and characterization of this system.

  9. Digital Full-Scope Simulation of a Conventional Nuclear Power Plant Control Room, Phase 2: Installation of a Reconfigurable Simulator to Support Nuclear Plant Sustainability

    SciTech Connect

    Ronald L. Boring; Vivek Agarwal; Kirk Fitzgerald; Jacques Hugo; Bruce Hallbert

    2013-03-01

    The U.S. Department of Energy’s Light Water Reactor Sustainability program has developed a control room simulator in support of control room modernization at nuclear power plants in the U.S. This report highlights the recent completion of this reconfigurable, full-scale, full-scope control room simulator buildout at the Idaho National Laboratory. The simulator is fully reconfigurable, meaning it supports multiple plant models developed by different simulator vendors. The simulator is full-scale, using glasstop virtual panels to display the analog control boards found at current plants. The present installation features 15 glasstop panels, uniquely achieving a complete control room representation. The simulator is also full-scope, meaning it uses the same plant models used for training simulators at actual plants. Unlike in the plant training simulators, the deployment on glasstop panels allows a high degree of customization of the panels, allowing the simulator to be used for research on the design of new digital control systems for control room modernization. This report includes separate sections discussing the glasstop panels, their layout to mimic control rooms at actual plants, technical details on creating a multi-plant and multi-vendor reconfigurable simulator, and current efforts to support control room modernization at U.S. utilities. The glasstop simulator provides an ideal testbed for prototyping and validating new control room concepts. Equally importantly, it is helping create a standardized and vetted human factors engineering process that can be used across the nuclear industry to ensure control room upgrades maintain and even improve current reliability and safety.

  10. Spin and Isospin Dependent Interactions in Classical Molecular Simulations of Dense Nuclear Matter

    NASA Astrophysics Data System (ADS)

    Amason, Charlee; Caplan, Matt; Horowitz, Cj

    2015-10-01

    A neutron star is the hot, incredibly dense remnant of a massive star gone supernova. Extreme conditions on neutron stars allow for the formation of exotically shaped nuclear matter, known colloquially as ``nuclear pasta.'' Competition between the strong nuclear force and the repulsive Coulomb force results in frustration of the neutron star crust, ultimately resulting in these pasta shapes. Previous work at Indiana University has used classical molecular dynamic simulations to model the formation of this pasta. For this project, we introduce a similar model with a new spin dependent interaction. Using this model, we perform molecular dynamics simulations of both symmetric nuclear matter and pure neutron matter with 400 particles. The energies found are similar to those in chiral effective field theory calculations. When we include Coulomb interactions, the model produces pasta shapes. Future work will incorporate this spin potential into larger pasta simulations. Supported by the National Science Foundation REU at Indiana University.

  11. Modeling Choices in Nuclear Warfighting: Two Classroom Simulations on Escalation and Retaliation

    ERIC Educational Resources Information Center

    Schofield, Julian

    2013-01-01

    Two classroom simulations--"Superpower Confrontation" and "Multipolar Asian Simulation"--are used to teach and test various aspects of the Borden versus Brodie debate on the Schelling versus Lanchester approach to nuclear conflict modeling and resolution. The author applies a Schelling test to segregate high from low empathic students, and assigns…

  12. Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

    SciTech Connect

    Bragg-Sitton, Shannon M.; Dickens, Ricky; Adams, Mike; Davis, Joe; Kapernick, Richard

    2007-01-30

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Work at the NASA Marshall Space Flight Center seeks to develop high fidelity thermal simulators that not only match the static power profile that would be observed in an operating, fueled nuclear reactor, but also match the dynamic fuel pin performance during feasible transients. Comparison between the fuel pins and thermal simulators is made at the outer fuel clad surface, which corresponds to the outer sheath surface in the thermal simulator. The thermal simulators that are currently being developed are designed to meet the geometric and power requirements of a proposed surface power reactor design, accommodate testing of various axial power profiles, and incorporate imbedded instrumentation. Static and dynamic fuel pin performances for a proposed reactor design have been determined using SINDA/FLUINT thermal analysis software, and initial comparison has been made between the expected nuclear performance and the performance of conceptual thermal simulator designs. Through a series of iterative analysis, a conceptual high fidelity design will be developed, followed by engineering design, fabrication, and testing to validate the overall design process. Although the resulting thermal simulator will be designed for a specific reactor concept, establishing this rigorous design process will assist in streamlining the thermal simulator development for other reactor concepts. This paper presents the current status of high fidelity thermal simulator design relative to a SNAP derivative reactor design that could be applied for Lunar surface power.

  13. Approaching the Post-Newtonian Regime with Numerical Relativity: A Compact-Object Binary Simulation Spanning 350 Gravitational-Wave Cycles.

    PubMed

    Szilágyi, Béla; Blackman, Jonathan; Buonanno, Alessandra; Taracchini, Andrea; Pfeiffer, Harald P; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Pan, Yi

    2015-07-17

    We present the first numerical-relativity simulation of a compact-object binary whose gravitational waveform is long enough to cover the entire frequency band of advanced gravitational-wave detectors, such as LIGO, Virgo, and KAGRA, for mass ratio 7 and total mass as low as 45.5M_{⊙}. We find that effective-one-body models, either uncalibrated or calibrated against substantially shorter numerical-relativity waveforms at smaller mass ratios, reproduce our new waveform remarkably well, with a negligible loss in detection rate due to modeling error. In contrast, post-Newtonian inspiral waveforms and existing calibrated phenomenological inspiral-merger-ringdown waveforms display greater disagreement with our new simulation. The disagreement varies substantially depending on the specific post-Newtonian approximant used. PMID:26230780

  14. Approaching the Post-Newtonian Regime with Numerical Relativity: A Compact-Object Binary Simulation Spanning 350 Gravitational-Wave Cycles.

    PubMed

    Szilágyi, Béla; Blackman, Jonathan; Buonanno, Alessandra; Taracchini, Andrea; Pfeiffer, Harald P; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Pan, Yi

    2015-07-17

    We present the first numerical-relativity simulation of a compact-object binary whose gravitational waveform is long enough to cover the entire frequency band of advanced gravitational-wave detectors, such as LIGO, Virgo, and KAGRA, for mass ratio 7 and total mass as low as 45.5M_{⊙}. We find that effective-one-body models, either uncalibrated or calibrated against substantially shorter numerical-relativity waveforms at smaller mass ratios, reproduce our new waveform remarkably well, with a negligible loss in detection rate due to modeling error. In contrast, post-Newtonian inspiral waveforms and existing calibrated phenomenological inspiral-merger-ringdown waveforms display greater disagreement with our new simulation. The disagreement varies substantially depending on the specific post-Newtonian approximant used.

  15. Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

    NASA Astrophysics Data System (ADS)

    Horton, W.; Ditmire, T.; Zakharov, Yu. P.

    2010-06-01

    Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

  16. Compost improves compacted urban soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urban construction sites usually result in compacted soils that limit infiltration and root growth. The purpose of this study was to determine if compost, aeration, and/or prairie grasses can remediate a site setup as a simulated post-construction site (compacted). Five years after establishing the ...

  17. Physically detached 'compact groups'

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars; Katz, Neal; Weinberg, David H.

    1995-01-01

    A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

  18. Comments on ``Use of conditional simulation in nuclear waste site performance assessment`` by Carol Gotway

    SciTech Connect

    Downing, D.J.

    1993-10-01

    This paper discusses Carol Gotway`s paper, ``The Use of Conditional Simulation in Nuclear Waste Site Performance Assessment.`` The paper centers on the use of conditional simulation and the use of geostatistical methods to simulate an entire field of values for subsequent use in a complex computer model. The issues of sampling designs for geostatistics, semivariogram estimation and anisotropy, turning bands method for random field generation, and estimation of the comulative distribution function are brought out.

  19. Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Phase II Upgrade Activities

    NASA Technical Reports Server (NTRS)

    Emrich, William J.; Moran, Robert P.; Pearson, J. Bose

    2013-01-01

    To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission and would be exposed to flowing hydrogen. Initial testing of a somewhat prototypical fuel element has been successfully performed in NTREES and the facility has now been shutdown to allow for an extensive reconfiguration of the facility which will result in a significant upgrade in its capabilities. Keywords: Nuclear Thermal Propulsion, Simulator

  20. Compact power reactor

    DOEpatents

    Wetch, Joseph R.; Dieckamp, Herman M.; Wilson, Lewis A.

    1978-01-01

    There is disclosed a small compact nuclear reactor operating in the epithermal neutron energy range for supplying power at remote locations, as for a satellite. The core contains fuel moderator elements of Zr hydride with 7 w/o of 93% enriched uranium alloy. The core has a radial beryllium reflector and is cooled by liquid metal coolant such as NaK. The reactor is controlled and shut down by moving portions of the reflector.

  1. KEYNOTE: Simulation, computation, and the Global Nuclear Energy Partnership

    NASA Astrophysics Data System (ADS)

    Reis, Victor, Dr.

    2006-01-01

    Dr. Victor Reis delivered the keynote talk at the closing session of the conference. The talk was forward looking and focused on the importance of advanced computing for large-scale nuclear energy goals such as Global Nuclear Energy Partnership (GNEP). Dr. Reis discussed the important connections of GNEP to the Scientific Discovery through Advanced Computing (SciDAC) program and the SciDAC research portfolio. In the context of GNEP, Dr. Reis talked about possible fuel leasing configurations, strategies for their implementation, and typical fuel cycle flow sheets. A major portion of the talk addressed lessons learnt from ‘Science Based Stockpile Stewardship’ and the Accelerated Strategic Computing Initiative (ASCI) initiative and how they can provide guidance for advancing GNEP and SciDAC goals. Dr. Reis’s colorful and informative presentation included international proverbs, quotes and comments, in tune with the international flavor that is part of the GNEP philosophy and plan. He concluded with a positive and motivating outlook for peaceful nuclear energy and its potential to solve global problems. An interview with Dr. Reis, addressing some of the above issues, is the cover story of Issue 2 of the SciDAC Review and available at http://www.scidacreview.org This summary of Dr. Reis’s PowerPoint presentation was prepared by Institute of Physics Publishing, the complete PowerPoint version of Dr. Reis’s talk at SciDAC 2006 is given as a multimedia attachment to this summary.

  2. Deflection Measurements of a Thermally Simulated Nuclear Core Using a High-Resolution CCD-Camera

    NASA Technical Reports Server (NTRS)

    Stanojev, B. J.; Houts, M.

    2004-01-01

    Space fission systems under consideration for near-term missions all use compact. fast-spectrum reactor cores. Reactor dimensional change with increasing temperature, which affects neutron leakage. is the dominant source of reactivity feedback in these systems. Accurately measuring core dimensional changes during realistic non-nuclear testing is therefore necessary in predicting the system nuclear equivalent behavior. This paper discusses one key technique being evaluated for measuring such changes. The proposed technique is to use a Charged Couple Device (CCD) sensor to obtain deformation readings of electrically heated prototypic reactor core geometry. This paper introduces a technique by which a single high spatial resolution CCD camera is used to measure core deformation in Real-Time (RT). Initial system checkout results are presented along with a discussion on how additional cameras could be used to achieve a three- dimensional deformation profile of the core during test.

  3. A performance-based method for calculating the design thickness of compacted clay liners exposed to high strength leachate under simulated landfill conditions.

    PubMed

    Safari, Edwin; Jalili Ghazizade, Mahdi; Abdoli, Mohammad Ali

    2012-09-01

    Compacted clay liners (CCLs) when feasible, are preferred to composite geosynthetic liners. The thickness of CCLs is typically prescribed by each country's environmental protection regulations. However, considering the fact that construction of CCLs represents a significant portion of overall landfill construction costs; a performance based design of liner thickness would be preferable to 'one size fits all' prescriptive standards. In this study researchers analyzed the hydraulic behaviour of a compacted clayey soil in three laboratory pilot scale columns exposed to high strength leachate under simulated landfill conditions. The temperature of the simulated CCL at the surface was maintained at 40 ± 2 °C and a vertical pressure of 250 kPa was applied to the soil through a gravel layer on top of the 50 cm thick CCL where high strength fresh leachate was circulated at heads of 15 and 30 cm simulating the flow over the CCL. Inverse modelling using HYDRUS-1D indicated that the hydraulic conductivity after 180 days was decreased about three orders of magnitude in comparison with the values measured prior to the experiment. A number of scenarios of different leachate heads and persistence time were considered and saturation depth of the CCL was predicted through modelling. Under a typical leachate head of 30 cm, the saturation depth was predicted to be less than 60 cm for a persistence time of 3 years. This approach can be generalized to estimate an effective thickness of a CCL instead of using prescribed values, which may be conservatively overdesigned and thus unduly costly. PMID:22617473

  4. A performance-based method for calculating the design thickness of compacted clay liners exposed to high strength leachate under simulated landfill conditions.

    PubMed

    Safari, Edwin; Jalili Ghazizade, Mahdi; Abdoli, Mohammad Ali

    2012-09-01

    Compacted clay liners (CCLs) when feasible, are preferred to composite geosynthetic liners. The thickness of CCLs is typically prescribed by each country's environmental protection regulations. However, considering the fact that construction of CCLs represents a significant portion of overall landfill construction costs; a performance based design of liner thickness would be preferable to 'one size fits all' prescriptive standards. In this study researchers analyzed the hydraulic behaviour of a compacted clayey soil in three laboratory pilot scale columns exposed to high strength leachate under simulated landfill conditions. The temperature of the simulated CCL at the surface was maintained at 40 ± 2 °C and a vertical pressure of 250 kPa was applied to the soil through a gravel layer on top of the 50 cm thick CCL where high strength fresh leachate was circulated at heads of 15 and 30 cm simulating the flow over the CCL. Inverse modelling using HYDRUS-1D indicated that the hydraulic conductivity after 180 days was decreased about three orders of magnitude in comparison with the values measured prior to the experiment. A number of scenarios of different leachate heads and persistence time were considered and saturation depth of the CCL was predicted through modelling. Under a typical leachate head of 30 cm, the saturation depth was predicted to be less than 60 cm for a persistence time of 3 years. This approach can be generalized to estimate an effective thickness of a CCL instead of using prescribed values, which may be conservatively overdesigned and thus unduly costly.

  5. Ureilite compaction

    NASA Astrophysics Data System (ADS)

    Walker, D.; Agee, C. B.

    1988-03-01

    Ureilite meteorites show the simple mineralogy and compact recrystallized textures of adcumulate rock or melting residues. A certain amount of controversy exists about whether they are in fact adcumulate rocks or melting residues and about the nature of the precursor liquid or solid assemblage. The authors undertook a limited experimental study which made possible the evaluation of the potential of the thermal migration mechanism (diffusion on a saturation gradient) for forming ureilite-like aggregates from carbonaceous chondrite precursors. They find that the process can produce compact recrystallized aggregates of silicate crystals which do resemble the ureilities and other interstitial-liquid-free adcumulate rocks in texture.

  6. Simulations of Globular Clusters Merging in Galactic Nuclear Regions

    NASA Astrophysics Data System (ADS)

    Miocchi, P.; Dolcetta, R. Capuzzo; Matteo, P. Di

    We present the results of detailed N-body simulations regarding the interaction of four massive globular clusters in the central region of a triaxial galaxy. The systems undergo a full merging event, producing a sort of `Super Star Cluster' (SSC) whose features are close to those of a superposition of the individual initial mergers. In contrast with other similar simulations, the resulting SSC structural parameters are located along the observed scaling relations of globular clusters. These findings seem to support the idea that a massive SSC may have formed in early phases of the mother galaxy evolution and contributed to the growth of a massive nucleus.

  7. Short-term nuclear annual power production simulation documentation (SNAPPS). Task 15

    SciTech Connect

    Andress, D.

    1985-09-01

    Short-Term Nuclear Annual Power Production Simulation (SNAPPS) is a FORTRAN computer program that projects the short-term monthly and annual generation of electricity by the nation's nuclear reactors. SNAPPS develops a power supply curve (histograms) for each individual reactor and then tallies its monthly and annual electricity production. The SNAPPS input requirements include reactor characteristics, cycle parameters, and scheduled outage data. This report contains the documentation for the program.

  8. Use of computer simulations for the early introduction of nuclear engineering concepts

    SciTech Connect

    Ougouag, A.M.; Zerguini, T.H.

    1985-11-01

    A sophomore level nuclear engineering (NE) course is being introduced at the University of Illinois. Via computer simulations, this course presents materials covering the most important aspects of the field. It is noted that computer simulations in nuclear engineering are cheaper and safer than experiments yet they provide an effective teaching tool for the early introduction of advanced concepts. The new course material can be used as a tutorial and for remedial learning. The use of computer simulation motivates learning since students associate computer activities with games. Such a course can help in the dissemination of the proper information to students from different fields, including liberal arts, and eventually increase undergraduate student enrollment in nuclear engineering.

  9. OVERVIEW OF A RECONFIGURABLE SIMULATOR FOR MAIN CONTROL ROOM UPGRADES IN NUCLEAR POWER PLANTS

    SciTech Connect

    Ronald L. Boring

    2012-10-01

    This paper provides background on a reconfigurable control room simulator for nuclear power plants. The main control rooms in current nuclear power plants feature analog technology that is growing obsolete. The need to upgrade control rooms serves the practical need of maintainability as well as the opportunity to implement newer digital technologies with added functionality. There currently exists no dedicated research simulator for use in human factors design and evaluation activities for nuclear power plant modernization in the U.S. The new research simulator discussed in this paper provides a test bed in which operator performance on new control room concepts can be benchmarked against existing control rooms and in which new technologies can be validated for safety and usability prior to deployment.

  10. Photon energy absorption coefficients for nuclear track detectors using Geant4 Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Medhat, M. E.; Badiger, N. M.

    2015-01-01

    Geant4 Monte Carlo code simulations were used to solve experimental and theoretical complications for calculation of mass energy-absorption coefficients of elements, air, and compounds. The mass energy-absorption coefficients for nuclear track detectors were computed first time using Geant4 Monte Carlo code for energy 1 keV-20 MeV. Very good agreements for simulated results of mass energy-absorption coefficients for carbon, nitrogen, silicon, sodium iodide and nuclear track detectors were observed on comparison with the values reported in the literatures. Kerma relative to air for energy 1 keV-20 MeV and energy absorption buildup factors for energy 50 keV-10 MeV up to 10 mfp penetration depths of the selected nuclear track detectors were also calculated to evaluate the absorption of the gamma photons. Geant4 simulation can be utilized for estimation of mass energy-absorption coefficients in elements and composite materials.

  11. Simulation of two-phase liquid-vapor flows using a high-order compact finite-difference lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Hejranfar, Kazem; Ezzatneshan, Eslam

    2015-11-01

    A high-order compact finite-difference lattice Boltzmann method (CFDLBM) is extended and applied to accurately simulate two-phase liquid-vapor flows with high density ratios. Herein, the He-Shan-Doolen-type lattice Boltzmann multiphase model is used and the spatial derivatives in the resulting equations are discretized by using the fourth-order compact finite-difference scheme and the temporal term is discretized with the fourth-order Runge-Kutta scheme to provide an accurate and efficient two-phase flow solver. A high-order spectral-type low-pass compact nonlinear filter is used to regularize the numerical solution and remove spurious waves generated by flow nonlinearities in smooth regions and at the same time to remove the numerical oscillations in the interfacial region between the two phases. Three discontinuity-detecting sensors for properly switching between a second-order and a higher-order filter are applied and assessed. It is shown that the filtering technique used can be conveniently adopted to reduce the spurious numerical effects and improve the numerical stability of the CFDLBM implemented. A sensitivity study is also conducted to evaluate the effects of grid size and the filtering procedure implemented on the accuracy and performance of the solution. The accuracy and efficiency of the proposed solution procedure based on the compact finite-difference LBM are examined by solving different two-phase systems. Five test cases considered herein for validating the results of the two-phase flows are an equilibrium state of a planar interface in a liquid-vapor system, a droplet suspended in the gaseous phase, a liquid droplet located between two parallel wettable surfaces, the coalescence of two droplets, and a phase separation in a liquid-vapor system at different conditions. Numerical results are also presented for the coexistence curve and the verification of the Laplace law. Results obtained are in good agreement with the analytical solutions and also

  12. CAD-based Monte Carlo Program for Integrated Simulation of Nuclear System SuperMC

    NASA Astrophysics Data System (ADS)

    Wu, Yican; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Long, Pengcheng; Hu, Liqin

    2014-06-01

    Monte Carlo (MC) method has distinct advantages to simulate complicated nuclear systems and is envisioned as routine method for nuclear design and analysis in the future. High fidelity simulation with MC method coupled with multi-physical phenomenon simulation has significant impact on safety, economy and sustainability of nuclear systems. However, great challenges to current MC methods and codes prevent its application in real engineering project. SuperMC is a CAD-based Monte Carlo program for integrated simulation of nuclear system developed by FDS Team, China, making use of hybrid MC-deterministic method and advanced computer technologies. The design aim, architecture and main methodology of SuperMC were presented in this paper. SuperMC2.1, the latest version for neutron, photon and coupled neutron and photon transport calculation, has been developed and validated by using a series of benchmarking cases such as the fusion reactor ITER model and the fast reactor BN-600 model. SuperMC is still in its evolution process toward a general and routine tool for nuclear system. Warning, no authors found for 2014snam.conf06023.

  13. Numerical simulations of compact intracloud discharges as the Relativistic Runaway Electron Avalanche-Extensive Air Shower process

    NASA Astrophysics Data System (ADS)

    Arabshahi, S.; Dwyer, J. R.; Nag, A.; Rakov, V. A.; Rassoul, H. K.

    2014-01-01

    Compact intracloud discharges (CIDs) are sources of the powerful, often isolated radio pulses emitted by thunderstorms. The VLF-LF radio pulses are called narrow bipolar pulses (NBPs). It is still not clear how CIDs are produced, but two categories of theoretical models that have previously been considered are the Transmission Line (TL) model and the Relativistic Runaway Electron Avalanche-Extensive Air Showers (RREA-EAS) model. In this paper, we perform numerical calculations of RREA-EASs for various electric field configurations inside thunderstorms. The results of these calculations are compared to results from the other models and to the experimental data. Our analysis shows that different theoretical models predict different fundamental characteristics for CIDs. Therefore, many previously published properties of CIDs are highly model dependent. This is because of the fact that measurements of the radiation field usually provide information about the current moment of the source, and different physical models with different discharge currents could have the same current moment. We have also found that although the RREA-EAS model could explain the current moments of CIDs, the required electric fields in the thundercloud are rather large and may not be realistic. Furthermore, the production of NBPs from RREA-EAS requires very energetic primary cosmic ray particles, not observed in nature. If such ultrahigh-energy particles were responsible for NBPs, then they should be far less frequent than is actually observed.

  14. Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)

    SciTech Connect

    Kimberlyn C. Mousseau

    2011-10-01

    The Nuclear Energy Computational Fluid Dynamics Advanced Modeling and Simulation (NE-CAMS) system is being developed at the Idaho National Laboratory (INL) in collaboration with Bettis Laboratory, Sandia National Laboratory (SNL), Argonne National Laboratory (ANL), Utah State University (USU), and other interested parties with the objective of developing and implementing a comprehensive and readily accessible data and information management system for computational fluid dynamics (CFD) verification and validation (V&V) in support of nuclear energy systems design and safety analysis. The two key objectives of the NE-CAMS effort are to identify, collect, assess, store and maintain high resolution and high quality experimental data and related expert knowledge (metadata) for use in CFD V&V assessments specific to the nuclear energy field and to establish a working relationship with the U.S. Nuclear Regulatory Commission (NRC) to develop a CFD V&V database, including benchmark cases, that addresses and supports the associated NRC regulations and policies on the use of CFD analysis. In particular, the NE-CAMS system will support the Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program, which aims to develop and deploy advanced modeling and simulation methods and computational tools for reliable numerical simulation of nuclear reactor systems for design and safety analysis. Primary NE-CAMS Elements There are four primary elements of the NE-CAMS knowledge base designed to support computer modeling and simulation in the nuclear energy arena as listed below. Element 1. The database will contain experimental data that can be used for CFD validation that is relevant to nuclear reactor and plant processes, particularly those important to the nuclear industry and the NRC. Element 2. Qualification standards for data evaluation and classification will be incorporated and applied such that validation data sets will result in well

  15. New exclusive CHIPS-TPT algorithms for simulation of neutron-nuclear reactions

    NASA Astrophysics Data System (ADS)

    Kosov, M.; Savin, D.

    2015-05-01

    The CHIPS-TPT physics library for simulation of neutron-nuclear reactions on the new exclusive level is being developed in CFAR VNIIA. The exclusive modeling conserves energy, momentum and quantum numbers in each neutron-nuclear interaction. The CHIPS-TPT algorithms are based on the exclusive CHIPS library, which is compatible with Geant4. Special CHIPS-TPT physics lists in the Geant4 format are provided. The calculation time for an exclusive CHIPS-TPT simulation is comparable to the time of the corresponding Geant4- HP simulation. In addition to the reduction of the deposited energy fluctuations, which is a consequence of the energy conservation, the CHIPS-TPT libraries provide a possibility of simulation of the secondary particles correlation, e.g. secondary gammas, and of the Doppler broadening of gamma lines in the spectrum, which can be measured by germanium detectors.

  16. Microwave Processing of Simulated Advanced Nuclear Fuel Pellets

    SciTech Connect

    D.E. Clark; D.C. Folz

    2010-08-29

    Throughout the three-year project funded by the Department of Energy (DOE) and lead by Virginia Tech (VT), project tasks were modified by consensus to fit the changing needs of the DOE with respect to developing new inert matrix fuel processing techniques. The focus throughout the project was on the use of microwave energy to sinter fully stabilized zirconia pellets using microwave energy and to evaluate the effectiveness of techniques that were developed. Additionally, the research team was to propose fundamental concepts as to processing radioactive fuels based on the effectiveness of the microwave process in sintering the simulated matrix material.

  17. The use of conditional simulation in nuclear-waste-site performance assessment

    SciTech Connect

    Gotway, C.A.

    1994-05-01

    Stochastic simulation methodology is becoming an important tool for evaluating the performance of potential nuclear-waste repositories. This article presents an overview of such methodology as it is currently used in many waste-management applications. Details involved with the statistical and geostatistical analyses of relevant hydrogeologic variables are provided in a simulation study of groundwater travel time through an aquifer overlying the Waste Isolation Pilot Plant repository in southeastern New Mexico.

  18. Input visualization for the Cyclus nuclear fuel cycle simulator: CYClus Input Control

    SciTech Connect

    Flanagan, R.; Schneider, E.

    2013-07-01

    This paper discusses and demonstrates the methods used for the graphical user interface for the Cyclus fuel cycle simulator being developed at the University of Wisconsin-Madison. Cyclus Input Control (CYCIC) is currently being designed with nuclear engineers in mind, but future updates to the program will be made to allow even non-technical users to quickly and efficiently simulate fuel cycles to answer the questions important to them. (authors)

  19. A MULTIDIMENSIONAL AND MULTIPHYSICS APPROACH TO NUCLEAR FUEL BEHAVIOR SIMULATION

    SciTech Connect

    R. L. Williamson; J. D. Hales; S. R. Novascone; M. R. Tonks; D. R. Gaston; C. J. Permann; D. Andrs; R. C. Martineau

    2012-04-01

    Important aspects of fuel rod behavior, for example pellet-clad mechanical interaction (PCMI), fuel fracture, oxide formation, non-axisymmetric cooling, and response to fuel manufacturing defects, are inherently multidimensional in addition to being complicated multiphysics problems. Many current modeling tools are strictly 2D axisymmetric or even 1.5D. This paper outlines the capabilities of a new fuel modeling tool able to analyze either 2D axisymmetric or fully 3D models. These capabilities include temperature-dependent thermal conductivity of fuel; swelling and densification; fuel creep; pellet fracture; fission gas release; cladding creep; irradiation growth; and gap mechanics (contact and gap heat transfer). The need for multiphysics, multidimensional modeling is then demonstrated through a discussion of results for a set of example problems. The first, a 10-pellet rodlet, demonstrates the viability of the solution method employed. This example highlights the effect of our smeared cracking model and also shows the multidimensional nature of discrete fuel pellet modeling. The second example relies on our the multidimensional, multiphysics approach to analyze a missing pellet surface problem. As a final example, we show a lower-length-scale simulation coupled to a continuum-scale simulation.

  20. Corrosion of steel in simulated nuclear waste solutions

    SciTech Connect

    Mickalonis, J.I.

    1993-12-01

    Processing of inhibited nuclear waste to forms for long-term storage will cause waste tank environments to have dynamic conditions. During processing compositional changes in the waste may produce a corrosive environment for the plain carbon steel tanks. Large concentrations of nitrates which corrode steel are contained in the waste. Nitrite and hydroxides are added to inhibit any corrosion. Concentration changes of nitrate and nitrite were investigated to identify corrosion regimes that may occur during processing. Corrosion testing was performed with cyclic potentiodynamic polarization and linear polarization resistance. Test samples were plain carbon steel which was similar to the material of construction of the waste tanks. The corrosion morphology of test samples was investigated by visual evaluation and scanning electron microscopy. Qualitative chemical analysis was also performed using energy dispersive spectroscopy. The corrosion mechanism changed as a function of the nitrate concentration. As the nitrate concentration was increased the steel transitioned from a passive state to general attack, and finally pitting and crevice corrosion. The nitrate anion appeared to destabilize the surface oxide. Nitrite countered the oxide breakdown, although the exact mechanism was not determined.

  1. Photoassisted Biodegradation of Irradiated Organics in Simulated Nuclear Wastewater.

    PubMed

    Makgato, Stanford S; Nkhalambayausi-Chirwa, Evans M

    2015-05-01

    The extent of dehalogenation and degradation of toxic aromatic compounds in a nuclear wastewater was evaluated using a two-stage system consisting of a photolytic reactor followed by a biological reactor. Experiments were performed by varying the initial 4-chlorophenol (4-CP) concentration from 50 to 1000 mg/L. The UV pretreatment stage improved the overall efficiency of biodegradation of the recalcitrant compound by facilitating degradability in the biological stage. Removal efficiencies greater than 98% were achieved at 4-CP feed concentrations < 50 mg/L. Adding an H2O2 dose of 0.1 mg/L as an oxidant further improved biodegradation under optimum operating conditions for the entire system. Some known aromatic compound degraders such as Pseudomonas aeruginosa and Pseudomonas mendocina were detected in the consortium using the 16S rRNA genetic fingerprint technique. To the authors' knowledge, this is the first study on biodegradation of halogenated aromatic compounds that are copollutants of metallic radionuclides in radioactive wastewater.

  2. Photoassisted Biodegradation of Irradiated Organics in Simulated Nuclear Wastewater.

    PubMed

    Makgato, Stanford S; Nkhalambayausi-Chirwa, Evans M

    2015-05-01

    The extent of dehalogenation and degradation of toxic aromatic compounds in a nuclear wastewater was evaluated using a two-stage system consisting of a photolytic reactor followed by a biological reactor. Experiments were performed by varying the initial 4-chlorophenol (4-CP) concentration from 50 to 1000 mg/L. The UV pretreatment stage improved the overall efficiency of biodegradation of the recalcitrant compound by facilitating degradability in the biological stage. Removal efficiencies greater than 98% were achieved at 4-CP feed concentrations < 50 mg/L. Adding an H2O2 dose of 0.1 mg/L as an oxidant further improved biodegradation under optimum operating conditions for the entire system. Some known aromatic compound degraders such as Pseudomonas aeruginosa and Pseudomonas mendocina were detected in the consortium using the 16S rRNA genetic fingerprint technique. To the authors' knowledge, this is the first study on biodegradation of halogenated aromatic compounds that are copollutants of metallic radionuclides in radioactive wastewater. PMID:26460459

  3. Look at nuclear artillery yield options using JANUS, a wargame simulation code

    SciTech Connect

    Andre, C.G.

    1982-06-15

    JANUS, a two-sided, interactive wargame simulation code, was used to explore how using each of several different yield options in a nuclear artillery shell might affect a tactical battlefield simulation. In a general sense, the results or outcomes of these simulations support the results or outcomes of previous studies. In these simulations the Red player knew of the anticipated nuclear capability of the Blue player. Neither side experienced a decisive win over the other, and both continued fighting and experienced losses that, under most historical circumstances, would have been termed unacceptable - that is, something else would have happened (the attack would have been called off). During play, each side had only fragmentary knowledge of the remaining resources on the other side - thus each side desired to continue fighting on the basis of known information. We found that the anticipated use of nuclear weapons by either side affects the character of a game significantly and that, if the employment of nuclear weapons is to have a decided effect on the progress and outcome of a battle, each side will have to have an adequate number of nuclear weapons. In almost all the simulations we ran using JANUS, enhanced radiation (ER) weapons were more effective than 1-kt fission weapons in imposing overall losses on Red. The typical visibility in the JANUS simulation limited each side's ability to acquire units deep into enemy territory and so the 10-kt fission weapon was not useful against enemy tanks that were not engaged in battle. (Troop safety constraints limited its use on tanks that were engaged in direct fire with the enemy).

  4. Compact accelerator

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  5. Fundamental Science-Based Simulation of Nuclear Waste Forms

    SciTech Connect

    Devanathan, Ramaswami; Gao, Fei; Sun, Xin; Khaleel, Mohammad A.

    2010-10-04

    This report presents a hierarchical multiscale modeling scheme based on two-way information exchange. To account for all essential phenomena in waste forms over geological time scales, the models have to span length scales from nanometer to kilometer and time scales from picoseconds to millenia. A single model cannot cover this wide range and a multi-scale approach that integrates a number of different at-scale models is called for. The approach outlined here involves integration of quantum mechanical calculations, classical molecular dynamics simulations, kinetic Monte Carlo and phase field methods at the mesoscale, and continuum models. The ultimate aim is to provide science-based input in the form of constitutive equations to integrated codes. The atomistic component of this scheme is demonstrated in the promising waste form xenotime. Density functional theory calculations have yielded valuable information about defect formation energies. This data can be used to develop interatomic potentials for molecular dynamics simulations of radiation damage. Potentials developed in the present work show a good match for the equilibrium lattice constants, elastic constants and thermal expansion of xenotime. In novel waste forms, such as xenotime, a considerable amount of data needed to validate the models is not available. Integration of multiscale modeling with experimental work is essential to generate missing data needed to validate the modeling scheme and the individual models. Density functional theory can also be used to fill knowledge gaps. Key challenges lie in the areas of uncertainty quantification, verification and validation, which must be performed at each level of the multiscale model and across scales. The approach used to exchange information between different levels must also be rigorously validated. The outlook for multiscale modeling of wasteforms is quite promising.

  6. Design of a Resistively Heated Thermal Hydraulic Simulator for Nuclear Rocket Reactor Cores

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Foote, John P.; Ramachandran, Narayanan; Wang, Ten-See; Anghaie, Samim

    2007-01-01

    A preliminary design study is presented for a non-nuclear test facility which uses ohmic heating to replicate the thermal hydraulic characteristics of solid core nuclear reactor fuel element passages. The basis for this testing capability is a recently commissioned nuclear thermal rocket environments simulator, which uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce high-temperature pressurized hydrogen flows representative of reactor core environments, excepting radiation effects. Initially, the baseline test fixture for this non-nuclear environments simulator was configured for long duration hot hydrogen exposure of small cylindrical material specimens as a low cost means of evaluating material compatibility. It became evident, however, that additional functionality enhancements were needed to permit a critical examination of thermal hydraulic effects in fuel element passages. Thus, a design configuration was conceived whereby a short tubular material specimen, representing a fuel element passage segment, is surrounded by a backside resistive tungsten heater element and mounted within a self-contained module that inserts directly into the baseline test fixture assembly. With this configuration, it becomes possible to create an inward directed radial thermal gradient within the tubular material specimen such that the wall-to-gas heat flux characteristics of a typical fuel element passage are effectively simulated. The results of a preliminary engineering study for this innovative concept are fully summarized, including high-fidelity multi-physics thermal hydraulic simulations and detailed design features.

  7. USNRC's Nuclear Plant Analyzer: Engineering simulation capabilities into the 1990's

    SciTech Connect

    Laats, E.T.

    1987-01-01

    The Nuclear Plant Analyzer (NPA) is the US Nuclear Regulatory Commission's (NRC's) state-of-the-art nuclear reactor simulation capability. This computer software package integrates high fidelity nuclear reactor simulation codes such as the TRAC and RELAP5 series of codes with color graphics display techniques and advanced workstation hardware. The NPA first became operational at the Idaho National Engineering Laboratory (INEL) in 1983. Since then, the NPA system has been used for a number of key reactor safety-related tasks ranging from plant operator guidelines evaluation to emergency preparedness training. The NPA system is seen by the NRC as their vehicle to maintain modern, state-of-the-art simulation capabilities for use into the 1990s. System advancements are envisioned in two areas: first, software improvements to existing and evolving plant simulation codes utilized by the NPA through the use of such techniques as parallel and vector processing and artificial intelligence expert systems, and second, advanced hardware implementations using combinations of super-, minisuper-, supermini-, and supermicrocomputer system and satellite data communications networks for high flexibilty and greatly increased NPA system performance. 23 refs., 2 figs.

  8. TOWARD END-TO-END MODELING FOR NUCLEAR EXPLOSION MONITORING: SIMULATION OF UNDERGROUND NUCLEAR EXPLOSIONS AND EARTHQUAKES USING HYDRODYNAMIC AND ANELASTIC SIMULATIONS, HIGH-PERFORMANCE COMPUTING AND THREE-DIMENSIONAL EARTH MODELS

    SciTech Connect

    Rodgers, A; Vorobiev, O; Petersson, A; Sjogreen, B

    2009-07-06

    This paper describes new research being performed to improve understanding of seismic waves generated by underground nuclear explosions (UNE) by using full waveform simulation, high-performance computing and three-dimensional (3D) earth models. The goal of this effort is to develop an end-to-end modeling capability to cover the range of wave propagation required for nuclear explosion monitoring (NEM) from the buried nuclear device to the seismic sensor. The goal of this work is to improve understanding of the physical basis and prediction capabilities of seismic observables for NEM including source and path-propagation effects. We are pursuing research along three main thrusts. Firstly, we are modeling the non-linear hydrodynamic response of geologic materials to underground explosions in order to better understand how source emplacement conditions impact the seismic waves that emerge from the source region and are ultimately observed hundreds or thousands of kilometers away. Empirical evidence shows that the amplitudes and frequency content of seismic waves at all distances are strongly impacted by the physical properties of the source region (e.g. density, strength, porosity). To model the near-source shock-wave motions of an UNE, we use GEODYN, an Eulerian Godunov (finite volume) code incorporating thermodynamically consistent non-linear constitutive relations, including cavity formation, yielding, porous compaction, tensile failure, bulking and damage. In order to propagate motions to seismic distances we are developing a one-way coupling method to pass motions to WPP (a Cartesian anelastic finite difference code). Preliminary investigations of UNE's in canonical materials (granite, tuff and alluvium) confirm that emplacement conditions have a strong effect on seismic amplitudes and the generation of shear waves. Specifically, we find that motions from an explosion in high-strength, low-porosity granite have high compressional wave amplitudes and weak shear

  9. Raman study of aluminum speciation in simulated alkaline nuclear waste.

    PubMed

    Johnston, Cliff T; Agnew, Stephen F; Schoonover, Jon R; Kenney, John W; Page, Bobbi; Osborn, Jill; Corbin, Rob

    2002-06-01

    The chemistry of concentrated sodium aluminate solutions stored in many of the large, underground storage tanks containing high-level waste (HLW) at the Hanford and Savannah River Nuclear Reservations is an area of recent research interest. Not only is the presence of aluminate in solution important for continued safe storage of these wastes, the nature of both solid and solution aluminum oxyhydroxides is important for waste pretreatment. Moreover, for many tanks that have leaked high aluminum waste in the past, little is known about the speciation of Al in the soil. In this study, Raman spectroscopy has been used to investigate the speciation of the aqueous species in the Al2O3-Na2O-H2O system over a wide range of solution compositions and hydration. A ternary phase diagram has been used to correlate the observed changes in the spectra with the composition of the solution and with dimerization of aluminate that occurs at elevated aluminate concentrations (>1.5 M). Dimerization is evidenced by growth of new Al-O stretching bands at 535 and 695 cm(-1) at the expense of the aluminate monomer band at 620 cm(-1). The spectrum of water was strongly influenced by the high concentrations of Na+ and OH- (>17 M). Upon increasing the concentration of NaOH in solution, the delta-(H-O-H) bending band of water (v2 mode) increased in frequency to 1663 cm(-1), indicating that the water contained in the concentrated caustic solution was more strongly hydrogen bonded at the higher base content. In addition, the sharp, well-resolved band at 3610 cm(-1), assigned to the v(O-H) of free OH-, increased in intensity with increasing NaOH. Analysis of the v(O-H) bands in the 3800-2600 cm(-1) region supported the overall increase in hydrogen bonding as evidenced by the increase in relative intensity of a strongly hydrated water band at 3118 cm(-1). Taking into consideration the activity of water, the molar concentrations of the monomeric and dimeric aluminate species were estimated using

  10. Three new renal simulators for use in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Dullius, Marcos; Fonseca, Mateus; Botelho, Marcelo; Cunha, Clêdison; Souza, Divanízia

    2014-03-01

    Renal scintigraphy is useful to provide both functional and anatomic information of renal flow of cortical functions and evaluation of pathological collecting system. The objective of this study was develop and evaluate the performance of three renal phantoms: Two anthropomorphic static and another dynamic. The static images of the anthropomorphic phantoms were used for comparison with static renal scintigraphy with 99mTc-DMSA in different concentrations. These static phantoms were manufactured in two ways: one was made of acrylic using as mold a human kidney preserved in formaldehyde and the second was built with ABS (acrylonitrile butadiene styrene) in a 3D printer. The dynamic renal phantom was constructed of acrylic to simulate renal dynamics in scintigraphy with 99mTc-DTPA. These phantoms were scanned with static and dynamic protocols and compared with clinical data. Using these phantoms it is possible to acquire similar renal images as in the clinical scintigraphy. Therefore, these new renal phantoms can be very effective for use in the quality control of renal scintigraphy, and image processing systems.

  11. Toward Improved Nuclear Explosion Monitoring With Complete Waveform Simulations Using Three-Dimensional Models and Parallel Computing

    NASA Astrophysics Data System (ADS)

    Vorobiev, O.; Antoun, T.; Rodgers, A.; Matzel, E.; Myers, S.; Walter, W.; Petersson, A.; Bono, C.; Sjogreen, B.

    2008-12-01

    Next generation methods for lowering seismic monitoring thresholds and reducing uncertainties will likely rely on complete waveform simulations using three-dimensional (3D) earth models. Recent advances in numerical methods for both non-linear (shock wave) and linear (anelastic, seismic wave) propagation, improved 3D models and the steady growth of parallel computing promise to improve the accuracy and efficiency of explosion simulations. These methods implemented in new computer codes can advance physics-based understanding of nuclear explosions as well as the propagation effects caused by path-dependent earth structure. This presentation will summarize new 3D modeling capabilities developed to improve understanding of the seismic waves emerging from an explosion. Specifically we are working in three thrust areas: 1) computation of regional distance intermediate-period (50-10 seconds) synthetic seismograms in 3D earth models to assess the ability of these models to predict observed seismograms from well-characterized events; 2) coupling of non-linear hydrodynamic simulations of explosion shock waves with an anelastic finite difference code for modeling the dependence of seismic wave observables on explosion emplacement conditions and near-source heterogeneity; and 3) implementation of surface topography in our anelastic finite difference code to include scattering and mode-conversion due to a non-planar free surface. Current 3D continental-to-global scale seismic models represent long-wavelength (greater than 100 km) heterogeneity. We are investigating the efficacy of current 3D models to predict complete intermediate (50- 10 seconds) waveforms for well-characterized events (mostly earthquakes) using the spectral element code, SPECFEM3D. Intermediate period seismograms for crustal events at regional distance are strongly impacted by path propagation effects due to laterally variable crustal and upper mantle structure. We are also modeling shock wave propagation

  12. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    SciTech Connect

    Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

    2015-04-29

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder’s intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties’ absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

  13. Prototyping and validating requirements of radiation and nuclear emergency plan simulator

    NASA Astrophysics Data System (ADS)

    Hamid, AHA.; Rozan, MZA.; Ibrahim, R.; Deris, S.; Selamat, A.

    2015-04-01

    Organizational incapability in developing unrealistic, impractical, inadequate and ambiguous mechanisms of radiological and nuclear emergency preparedness and response plan (EPR) causing emergency plan disorder and severe disasters. These situations resulting from 65.6% of poor definition and unidentified roles and duties of the disaster coordinator. Those unexpected conditions brought huge aftermath to the first responders, operators, workers, patients and community at large. Hence, in this report, we discuss prototyping and validating of Malaysia radiation and nuclear emergency preparedness and response plan simulation model (EPRM). A prototyping technique was required to formalize the simulation model requirements. Prototyping as systems requirements validation was carried on to endorse the correctness of the model itself against the stakeholder's intensions in resolving those organizational incapability. We have made assumptions for the proposed emergency preparedness and response model (EPRM) through the simulation software. Those assumptions provided a twofold of expected mechanisms, planning and handling of the respective emergency plan as well as in bringing off the hazard involved. This model called RANEPF (Radiation and Nuclear Emergency Planning Framework) simulator demonstrated the training emergency response perquisites rather than the intervention principles alone. The demonstrations involved the determination of the casualties' absorbed dose range screening and the coordination of the capacity planning of the expected trauma triage. Through user-centred design and sociotechnical approach, RANEPF simulator was strategized and simplified, though certainly it is equally complex.

  14. Modeling and Testing of Non-Nuclear, Highpower Simulated Nuclear Thermal Rocket Reactor Elements

    NASA Technical Reports Server (NTRS)

    Kirk, Daniel R.

    2005-01-01

    When the President offered his new vision for space exploration in January of 2004, he said, "Our third goal is to return to the moon by 2020, as the launching point for missions beyond," and, "With the experience and knowledge gained on the moon, we will then be ready to take the next steps of space exploration: human missions to Mars and to worlds beyond." A human mission to Mars implies the need to move large payloads as rapidly as possible, in an efficient and cost-effective manner. Furthermore, with the scientific advancements possible with Project Prometheus and its Jupiter Icy Moons Orbiter (JIMO), (these use electric propulsion), there is a renewed interest in deep space exploration propulsion systems. According to many mission analyses, nuclear thermal propulsion (NTP), with its relatively high thrust and high specific impulse, is a serious candidate for such missions. Nuclear rockets utilize fission energy to heat a reactor core to very high temperatures. Hydrogen gas flowing through the core then becomes superheated and exits the engine at very high exhaust velocities. The combination of temperature and low molecular weight results in an engine with specific impulses above 900 seconds. This is almost twice the performance of the LOX/LH2 space shuttle engines, and the impact of this performance would be to reduce the trip time of a manned Mars mission from the 2.5 years, possible with chemical engines, to about 12-14 months.

  15. An assessment of coupling algorithms for nuclear reactor core physics simulations

    DOE PAGES

    Hamilton, Steven; Berrill, Mark; Clarno, Kevin; Pawlowski, Roger; Toth, Alex; Kelley, C. T.; Evans, Thomas; Philip, Bobby

    2016-04-01

    Here we evaluate the performance of multiphysics coupling algorithms applied to a light water nuclear reactor core simulation. The simulation couples the k-eigenvalue form of the neutron transport equation with heat conduction and subchannel flow equations. We compare Picard iteration (block Gauss–Seidel) to Anderson acceleration and multiple variants of preconditioned Jacobian-free Newton–Krylov (JFNK). The performance of the methods are evaluated over a range of energy group structures and core power levels. A novel physics-based approximation to a Jacobian-vector product was developed to mitigate the impact of expensive on-line cross section processing steps. Numerical simulations demonstrating the efficiency of JFNK andmore » Anderson acceleration relative to standard Picard iteration are performed on a 3D model of a nuclear fuel assembly. Finally, both criticality (k-eigenvalue) and critical boron search problems are considered.« less

  16. An assessment of coupling algorithms for nuclear reactor core physics simulations

    NASA Astrophysics Data System (ADS)

    Hamilton, Steven; Berrill, Mark; Clarno, Kevin; Pawlowski, Roger; Toth, Alex; Kelley, C. T.; Evans, Thomas; Philip, Bobby

    2016-04-01

    This paper evaluates the performance of multiphysics coupling algorithms applied to a light water nuclear reactor core simulation. The simulation couples the k-eigenvalue form of the neutron transport equation with heat conduction and subchannel flow equations. We compare Picard iteration (block Gauss-Seidel) to Anderson acceleration and multiple variants of preconditioned Jacobian-free Newton-Krylov (JFNK). The performance of the methods are evaluated over a range of energy group structures and core power levels. A novel physics-based approximation to a Jacobian-vector product has been developed to mitigate the impact of expensive on-line cross section processing steps. Numerical simulations demonstrating the efficiency of JFNK and Anderson acceleration relative to standard Picard iteration are performed on a 3D model of a nuclear fuel assembly. Both criticality (k-eigenvalue) and critical boron search problems are considered.

  17. NPTool: a simulation and analysis framework for low-energy nuclear physics experiments

    NASA Astrophysics Data System (ADS)

    Matta, A.; Morfouace, P.; de Séréville, N.; Flavigny, F.; Labiche, M.; Shearman, R.

    2016-08-01

    The Nuclear Physics Tool (NPTool) is an open source data analysis and Monte Carlo simulation framework that has been developed for low-energy nuclear physics experiments with an emphasis on radioactive beam experiments. The NPTool offers a unified framework for designing, preparing and analyzing complex experiments employing multiple detectors, each of which may comprise some hundreds of channels. The framework has been successfully used for the analysis and simulation of experiments at facilities including GANIL, RIKEN, ALTO and TRIUMF, using both stable and radioactive beams. This paper details the NPTool philosophy together with an overview of the workflow. The framework has been benchmarked through the comparison of simulated and experimental data for a variety of detectors used in charged particle and gamma-ray spectroscopy.

  18. Research approach and first results on agglomerate compaction in protoplanetary dust simulation in the Cloud Manipulation System

    NASA Astrophysics Data System (ADS)

    Vedernikov, Andrei; Blum, Jurgen; Ingo Von Borstel, Olaf; Schraepler, Rainer; Balapanov, Daniyar; Cecere, Anselmo

    2016-07-01

    Nanometre and micrometre-sized solid particles are ubiquitous in space and on Earth - from galaxies, interstellar space, protoplanetary and debris disks to planetary rings and atmospheres, planetary surfaces, comets, interplanetary space, Earth's atmosphere. Apparently, the most intriguing problem in the picture of the formation of planets is the transition from individual microscopic dust grains to kilometre-sized planetesimals. Revealing the mechanisms of this transition is one of the main tasks of the European Space Agency's project Interaction in Cosmic and Atmospheric Particle Systems (ICAPS). It was found that Brownian motion driven agglomeration could not provide the transition within reasonable time scale. As a result, at this stage top scientific goals shifted towards forced agglomeration and concentration of particles, targeting revealing the onset of compaction, experimental study of the evolution of fractal dimensions, size and mass distribution, occurrence of bouncing. The main tasks comprise 1) development of the rapid agglomeration model 2) development of the experimental facilities creating big fractal-type agglomerates from 10 to 1000 μm from a cloud of micrometre-size grains; 3) experimental realization of the rapid agglomeration in microgravity and ground conditions; and 4) in situ investigation of the morphology, mobility, mechanical and optical properties of the free-floating agglomerates, including investigation of thermophoresis, photophoresis of the agglomerates and of the two-phase flow phenomena. To solve the experimental part of the tasks we developed a Cloud Manipulation System, realized as a breadboard (CMS BB) for long duration microgravity platforms and a simplified laboratory version (CMS LV) mostly oriented on short duration microgravity and ground tests. The new system is based on the use of thermophoresis, most favourable for cloud manipulation without creating additional particle-particle forces in the cloud with a possibility

  19. Compact magnetograph

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Gillespie, B. A.; Mosher, J. W.

    1982-01-01

    A compact magnetograph system based on solid Fabry-Perot interferometers as the spectral isolation elements was studied. The theory of operation of several Fabry-Perot systems, the suitability of various magnetic lines, signal levels expected for different modes of operation, and the optimal detector systems were investigated. The requirements that the lack of a polarization modulator placed upon the electronic signal chain was emphasized. The PLZT modulator was chosen as a satisfactory component with both high reliability and elatively low voltage requirements. Thermal control, line centering and velocity offset problems were solved by a Fabry-Perot configuration.

  20. Monte Carlo Simulation Study of a Differential Calorimeter Measuring the Nuclear Heating in Material Testing Reactors

    NASA Astrophysics Data System (ADS)

    Amharrak, H.; Reynard-Carette, C.; Lyoussi, A.; Carette, M.; Brun, J.; De Vita, C.; Fourmentel, D.; Villard, J.-F.; Guimbal, P.

    2016-02-01

    The nuclear heating measurements in Material Testing Reactors (MTRs) are crucial for the study of nuclear materials and fuels under irradiation. The reference measurements of this nuclear heating are especially performed by a differential calorimeter including a graphite sample material. Then these measurements are used for other materials, other geometries, or other experimental conditions in order to predict the nuclear heating and thermal conditions induced in the irradiation devices. This paper will present new simulations with MCNP Monte-Carlo transport code to determine the gamma heating profile inside the calorimeter. The whole complex geometry of the sensor has been considered. We use as an input source in the model, the photon spectra calculated in various positions of CARMEN-1 irradiation program in OSIRIS reactor. After a description of the differential calorimeter device, the MCNP modeling used for the calculations of radial profile of nuclear heating inside the calorimeter elements will be introduced. The obtained results of different simulations will be detailed and discussed in this paper. The charged particle equilibrium inside the calorimeter elements will be studied. Then we will focus on parametric studies of the various components of the calorimeter. The influence of source type will be also took into account. Moreover the influence of the material used for the sample will be described.

  1. TH-C-12A-08: New Compact 10 MV S-Band Linear Accelerator: 3D Finite-Element Design and Monte Carlo Dose Simulations

    SciTech Connect

    Baillie, D; St Aubin, J; Fallone, B; Steciw, S

    2014-06-15

    Purpose: To design a new compact S-band linac waveguide capable of producing a 10 MV x-ray beam, while maintaining the length (27.5 cm) of current 6 MV waveguides. This will allow higher x-ray energies to be used in our linac-MRI systems with the same footprint. Methods: Finite element software COMSOL Multiphysics was used to design an accelerator cavity matching one published in an experiment breakdown study, to ensure that our modeled cavities do not exceed the threshold electric fields published. This cavity was used as the basis for designing an accelerator waveguide, where each cavity of the full waveguide was tuned to resonate at 2.997 GHz by adjusting the cavity diameter. The RF field solution within the waveguide was calculated, and together with an electron-gun phase space generated using Opera3D/SCALA, were input into electron tracking software PARMELA to compute the electron phase space striking the x-ray target. This target phase space was then used in BEAM Monte Carlo simulations to generate percent depth doses curves for this new linac, which were then used to re-optimize the waveguide geometry. Results: The shunt impedance, Q-factor, and peak-to-mean electric field ratio were matched to those published for the breakdown study to within 0.1% error. After tuning the full waveguide, the peak surface fields are calculated to be 207 MV/m, 13% below the breakdown threshold, and a d-max depth of 2.42 cm, a D10/20 value of 1.59, compared to 2.45 cm and 1.59, respectively, for the simulated Varian 10 MV linac and brehmsstrahlung production efficiency 20% lower than a simulated Varian 10 MV linac. Conclusion: This work demonstrates the design of a functional 27.5 cm waveguide producing 10 MV photons with characteristics similar to a Varian 10 MV linac.

  2. Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)

    SciTech Connect

    Rich Johnson; Kimberlyn C. Mousseau; Hyung Lee

    2011-09-01

    NE-KAMS knowledge base will assist computational analysts, physics model developers, experimentalists, nuclear reactor designers, and federal regulators by: (1) Establishing accepted standards, requirements and best practices for V&V and UQ of computational models and simulations, (2) Establishing accepted standards and procedures for qualifying and classifying experimental and numerical benchmark data, (3) Providing readily accessible databases for nuclear energy related experimental and numerical benchmark data that can be used in V&V assessments and computational methods development, (4) Providing a searchable knowledge base of information, documents and data on V&V and UQ, and (5) Providing web-enabled applications, tools and utilities for V&V and UQ activities, data assessment and processing, and information and data searches. From its inception, NE-KAMS will directly support nuclear energy research, development and demonstration programs within the U.S. Department of Energy (DOE), including the Consortium for Advanced Simulation of Light Water Reactors (CASL), the Nuclear Energy Advanced Modeling and Simulation (NEAMS), the Light Water Reactor Sustainability (LWRS), the Small Modular Reactors (SMR), and the Next Generation Nuclear Power Plant (NGNP) programs. These programs all involve computational modeling and simulation (M&S) of nuclear reactor systems, components and processes, and it is envisioned that NE-KAMS will help to coordinate and facilitate collaboration and sharing of resources and expertise for V&V and UQ across these programs. In addition, from the outset, NE-KAMS will support the use of computational M&S in the nuclear industry by developing guidelines and recommended practices aimed at quantifying the uncertainty and assessing the applicability of existing analysis models and methods. The NE-KAMS effort will initially focus on supporting the use of computational fluid dynamics (CFD) and thermal hydraulics (T/H) analysis for M&S of nuclear

  3. Exclusive CHIPS-TPT algorithms for simulation of neutron-nuclear reactions

    NASA Astrophysics Data System (ADS)

    Kosov, Mikhail; Savin, Dmitriy

    2016-09-01

    The CHIPS-TPT physics library for simulation of neutron-nuclear reactions on the new exclusive level is being developed in CFAR VNIIA. The exclusive modeling conserves energy, momentum and quantum numbers in each neutron-nuclear interaction. The CHIPS-TPT algorithms are based on the exclusive CHIPS library, which is compatible with Geant4. Special CHIPS-TPT physics lists in the Geant4 format are provided. The calculation time for an exclusive CHIPS-TPT simulation is comparable to the time of the corresponding inclusive Geant4-HP simulation and much faster for mono-isotopic simulations. In addition to the reduction of the deposited energy fluctuations, which is a consequence of the energy conservation, the CHIPS-TPT libraries provide a possibility of simulation of the secondary particles correlation, e.g. secondary gammas or n-γ correlations, and of the Doppler broadening of the γ-lines in the simulated spectra, which can be measured by germanium detectors.

  4. Effect of Particle Size Distribution on Slurry Rheology: Nuclear Waste Simulant Slurries

    SciTech Connect

    Chun, Jaehun; Oh, Takkeun; Luna, Maria L.; Schweiger, Michael J.

    2011-07-05

    Controlling the rheological properties of slurries has been of great interest in various industries such as cosmetics, ceramic processing, and nuclear waste treatment. Many physicochemical parameters, such as particle size, pH, ionic strength, and mass/volume fraction of particles, can influence the rheological properties of slurry. Among such parameters, the particle size distribution of slurry would be especially important for nuclear waste treatment because most nuclear waste slurries show a broad particle size distribution. We studied the rheological properties of several different low activity waste nuclear simulant slurries having different particle size distributions under high salt and high pH conditions. Using rheological and particle size analysis, it was found that the percentage of colloid-sized particles in slurry appears to be a key factor for rheological characteristics and the efficiency of rheological modifiers. This behavior was shown to be coupled with an existing electrostatic interaction between particles under a low salt concentration. Our study suggests that one may need to implement the particle size distribution as a critical factor to understand and control rheological properties in nuclear waste treatment plants, such as the U.S. Department of Energy’s Hanford and Savannah River sites, because the particle size distributions significantly vary over different types of nuclear waste slurries.

  5. Design Considerations for the Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

    NASA Technical Reports Server (NTRS)

    Emrich, Bill; Kirk, Daniel

    2006-01-01

    Nuclear Thermal Rockets or NTR's have been suggested as a propulsion system option for vehicles traveling to the moon or Mars. These engines are capable of providing high thrust at specific impulses at least twice that of today s best chemical engines. The performance constraints on these engines are mainly the result of temperature limitations on the fuel coupled with a limited ability to withstand chemical attack by the hot hydrogen propellant. To operate at maximum efficiency, fuel forms are desired which can withstand the extremely hot, hostile environment characteristic of NTR operation for at least several hours. The simulation of such an environment would require an experimental device which could simultaneously approximate the power, flow, and temperature conditions which a nuclear fuel element (or partial element) would encounter during NTR operation. Such a simulation would allow detailed studies of the fuel behavior and hydrogen flow characteristics under reactor like conditions to be performed. The goal of these simulations would be directed toward expanding the performance envelope of NTR engines over that which was demonstrated during the Rover and NERVA nuclear rocket programs of the 1970's. Currently, such a simulator is nearing completion at the Marshall Space Flight Center, and will shortly be used in the future to evaluate a wide variety of he1 element designs and the materials of which they are constructed. This present work addresses the initial experimental objectives of the Nuclear Thermal Rocket Element Environmental Simulator or NTREES and some of the design considerations which were considered prior to and during its construction.

  6. Finite-difference time-domain simulation of compact acousto-optic filters based on multireflection beam expanding

    SciTech Connect

    Tsarev, Andrei V

    2007-04-30

    The results of numerical simulation of acousto-optic (AO) tunable filters of a new type based on multireflection beam expanding in waveguide structures are discussed. Planar waveguide filters based on thin chalcogenide (As{sub 2}S{sub 3}) films of lithium niobate (LiNbO{sub 3}) are considered. The operation of filters is analysed by the finite-difference time-domain (FDTD) method by using the license FullWAVE software package (RSoft Design Group, Inc.). It is shown that AO filters have very good dispersion properties and AO filters of extremely small size provide a narrow filtration line within the tuning range of more than 100 nm (at a wavelength of 1.54 {mu}m). It is important that the normalised linewidth (measured in units of the reciprocal filter length) is an order of magnitude smaller than the theoretical limit for AO filters produced from the same material in the conventional way, without the use of multireflection beam expanding. (acoustooptics)

  7. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    SciTech Connect

    Clarno, Kevin T; Hamilton, Steven P; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth; Pugmire, Dave; Dilts, Gary; Banfield, James E

    2012-02-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms and boundary conditions of traditional (single-pin) nuclear fuel performance simulation, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. In addition, a new nuclear fuel-specific preconditioner was developed to account for the high aspect ratio of each fuel pin (12 feet axially, but 1 4 inches in diameter) with many individual fuel regions (pellets). With this novel capability, AMPFuel was used to model an entire 17 17 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins; the 25 guide tubes; the top and bottom structural regions; and the upper and lower (neutron) reflector regions. The final, full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 162

  8. Evaluation of Recent Upgrades to the NESS (Nuclear Engine System Simulation) Code

    NASA Technical Reports Server (NTRS)

    Fittje, James E.; Schnitzler, Bruce G.

    2008-01-01

    The Nuclear Thermal Rocket (NTR) concept is being evaluated as a potential propulsion technology for exploratory expeditions to the moon, Mars, and beyond. The need for exceptional propulsion system performance in these missions has been documented in numerous studies, and was the primary focus of a considerable effort undertaken during the Rover/NERVA program from 1955 to 1973. The NASA Glenn Research Center is leveraging this past NTR investment in their vehicle concepts and mission analysis studies with the aid of the Nuclear Engine System Simulation (NESS) code. This paper presents the additional capabilities and upgrades made to this code in order to perform higher fidelity NTR propulsion system analysis and design, and a comparison of its results to the Small Nuclear Rocket Engine (SNRE) design.

  9. SNM-DAT: Simulation of a heterogeneous network for nuclear border security

    NASA Astrophysics Data System (ADS)

    Nemzek, R.; Kenyon, G.; Koehler, A.; Lee, D. M.; Priedhorsky, W.; Raby, E. Y.

    2007-08-01

    We approach the problem of detecting Special Nuclear Material (SNM) smuggling across open borders by modeling a heterogeneous sensor network using an agent-based simulation. Our simulation SNM Data Analysis Tool (SNM-DAT) combines fixed seismic, metal, and radiation detectors with a mobile gamma spectrometer. Decision making within the simulation determines threat levels by combined signatures. The spectrometer is a limited-availability asset, and is only deployed for substantial threats. "Crossers" can be benign or carrying shielded SNM. Signatures and sensors are physics based, allowing us to model realistic sensor networks. The heterogeneous network provides great gains in detection efficiency compared to a radiation-only system. We can improve the simulation through better sensor and terrain models, additional signatures, and crossers that mimic actual trans-border traffic. We expect further gains in our ability to design sensor networks as we learn the emergent properties of heterogeneous detection, and potential adversary responses.

  10. Review of Methods Related to Assessing Human Performance in Nuclear Power Plant Control Room Simulations

    SciTech Connect

    Katya L Le Blanc; Ronald L Boring; David I Gertman

    2001-11-01

    With the increased use of digital systems in Nuclear Power Plant (NPP) control rooms comes a need to thoroughly understand the human performance issues associated with digital systems. A common way to evaluate human performance is to test operators and crews in NPP control room simulators. However, it is often challenging to characterize human performance in meaningful ways when measuring performance in NPP control room simulations. A review of the literature in NPP simulator studies reveals a variety of ways to measure human performance in NPP control room simulations including direct observation, automated computer logging, recordings from physiological equipment, self-report techniques, protocol analysis and structured debriefs, and application of model-based evaluation. These methods and the particular measures used are summarized and evaluated.

  11. Nuclear subsurface explosion modeling and hydrodynamic fragmentation simulation of hazardous asteroids

    NASA Astrophysics Data System (ADS)

    Premaratne, Pavithra Dhanuka

    Disruption and fragmentation of an asteroid using nuclear explosive devices (NEDs) is a highly complex yet a practical solution to mitigating the impact threat of asteroids with short warning time. A Hypervelocity Asteroid Intercept Vehicle (HAIV) concept, developed at the Asteroid Deflection Research Center (ADRC), consists of a primary vehicle that acts as kinetic impactor and a secondary vehicle that houses NEDs. The kinetic impactor (lead vehicle) strikes the asteroid creating a crater. The secondary vehicle will immediately enter the crater and detonate its nuclear payload creating a blast wave powerful enough to fragment the asteroid. The nuclear subsurface explosion modeling and hydrodynamic simulation has been a challenging research goal that paves the way an array of mission critical information. A mesh-free hydrodynamic simulation method, Smoothed Particle Hydrodynamics (SPH) was utilized to obtain both qualitative and quantitative solutions for explosion efficiency. Commercial fluid dynamics packages such as AUTODYN along with the in-house GPU accelerated SPH algorithms were used to validate and optimize high-energy explosion dynamics for a variety of test cases. Energy coupling from the NED to the target body was also examined to determine the effectiveness of nuclear subsurface explosions. Success of a disruption mission also depends on the survivability of the nuclear payload when the secondary vehicle approaches the newly formed crater at a velocity of 10 km/s or higher. The vehicle may come into contact with debris ejecting the crater which required the conceptual development of a Whipple shield. As the vehicle closes on the crater, its skin may also experience extreme temperatures due to heat radiated from the crater bottom. In order to address this thermal problem, a simple metallic thermal shield design was implemented utilizing a radiative heat transfer algorithm and nodal solutions obtained from hydrodynamic simulations.

  12. Simulation of differential die-away instrument’s response to asymmetrically burned spent nuclear fuel

    SciTech Connect

    Martinik, Tomas; Henzl, Vladimir; Grape, Sophie; Svard, Staffan Jacobsson; Jansson, Peter; Swinhoe, Martyn T.; Tobin, Stephen J.

    2015-03-04

    Here, previous simulation studies of Differential Die–Away (DDA) instrument’s response to active interrogation of spent nuclear fuel from a pressurized water reactor (PWR) yielded promising results in terms of its capability to accurately measure or estimate basic spent fuel assembly (SFA) characteristics, such as multiplication, initial enrichment (IE) and burn-up (BU) as well as the total plutonium content. These studies were however performed only for a subset of idealized SFAs with a symmetric BU with respect to its longitudinal axis. Therefore, to complement the previous results, additional simulations have been performed of the DDA instrument’s response to interrogation of asymmetrically burned spent nuclear fuel in order to determine whether detailed assay of SFAs from all 4 sides will be necessary in real life applications or whether a cost and time saving single sided assay could be used to achieve results of similar quality as previously reported in case of symmetrically burned SFAs.

  13. 1H nuclear spin relaxation of liquid water from molecular dynamics simulations.

    PubMed

    Calero, C; Martí, J; Guàrdia, E

    2015-02-01

    We have investigated the nuclear spin relaxation properties of (1)H in liquid water with the help of molecular dynamics simulations. We have computed the (1)H nuclear spin relaxation times T1 and T2 and determined the contribution of the different interactions to the relaxation at different temperatures and for different classical water models (SPC/E, TIP3P, TIP4P, and TIP4P/2005). Among the water models considered, the TIP4P/2005 model exhibits the best agreement with the experiment. The same analysis was performed with Car-Parrinello ab initio molecular dynamics simulations of bulk water at T = 330 K, which provided results close to the experimental values at room temperature. To complete the study, we have successfully accounted for the temperature-dependence of T1 and T2 in terms of a simplified model, which considers the reorientation in finite angle jumps and the diffusive translation of water molecules.

  14. Simulation of the dispersion of nuclear contamination using an adaptive Eulerian grid model.

    PubMed

    Lagzi, I; Kármán, D; Turányi, T; Tomlin, A S; Haszpra, L

    2004-01-01

    Application of an Eulerian model using layered adaptive unstructured grids coupled to a meso-scale meteorological model is presented for modelling the dispersion of nuclear contamination following the accidental release from a single but strong source to the atmosphere. The model automatically places a finer resolution grid, adaptively in time, in regions were high spatial numerical error is expected. The high-resolution grid region follows the movement of the contaminated air over time. Using this method, grid resolutions of the order of 6 km can be achieved in a computationally effective way. The concept is illustrated by the simulation of hypothetical nuclear accidents at the Paks NPP, in Central Hungary. The paper demonstrates that the adaptive model can achieve accuracy comparable to that of a high-resolution Eulerian model using significantly less grid points and computer simulation time. PMID:15149762

  15. Simulation modeling of nuclear steam generator water level process--a case study

    PubMed

    Zhao; Ou; Du

    2000-01-01

    Simulation modeling of the nuclear steam generator (SG) water level process in Qinshan Nuclear Power Plant (QNPP) is described in this paper. A practical methodology was adopted so that the model is both simple and accurate for control engineering implementation. The structure of the model is in the form of a transfer function, which was determined based on first-principles analysis and expert experience. The parameters of the model were obtained by taking advantage of the recorded historical response curves under the existing closed-loop control system. The results of process dimensional data verification and experimental tests demonstrate that the simulation model depicts the main dynamic characteristics of the SG water level process and is in accordance with the field recorded response curves. The model has been successfully applied to the design and test of an advanced digital feedwater control system in QNPP. PMID:10871210

  16. Dependence of simulated positron emitter yields in ion beam cancer therapy on modeling nuclear fragmentation.

    PubMed

    Lühr, Armin; Priegnitz, Marlen; Fiedler, Fine; Sobolevsky, Nikolai; Bassler, Niels

    2014-01-01

    In ion beam cancer therapy, range verification in patients using positron emission tomography (PET) requires the comparison of measured with simulated positron emitter yields. We found that (1) changes in modeling nuclear interactions strongly affected the positron emitter yields and that (2) Monte Carlo simulations with SHIELD-HIT10Areasonably matched the most abundant PET isotopes (11)C and (15)O. We observed an ion-energy (i.e., depth) dependence of the agreement between SHIELD-HIT10Aand measurement. Improved modeling requires more accurate measurements of cross-section values.

  17. Designing a Component-Based Architecture for the Modeling and Simulation of Nuclear Fuels and Reactors

    SciTech Connect

    Billings, Jay Jay; Elwasif, Wael R; Hively, Lee M; Bernholdt, David E; Hetrick III, John M; Bohn, Tim T

    2009-01-01

    Concerns over the environment and energy security have recently prompted renewed interest in the U.S. in nuclear energy. Recognizing this, the U.S. Dept. of Energy has launched an initiative to revamp and modernize the role that modeling and simulation plays in the development and operation of nuclear facilities. This Nuclear Energy Advanced Modeling and Simulation (NEAMS) program represents a major investment in the development of new software, with one or more large multi-scale multi-physics capabilities in each of four technical areas associated with the nuclear fuel cycle, as well as additional supporting developments. In conjunction with this, we are designing a software architecture, computational environment, and component framework to integrate the NEAMS technical capabilities and make them more accessible to users. In this report of work very much in progress, we lay out the 'problem' we are addressing, describe the model-driven system design approach we are using, and compare them with several large-scale technical software initiatives from the past. We discuss how component technology may be uniquely positioned to address the software integration challenges of the NEAMS program, outline the capabilities planned for the NEAMS computational environment and framework, and describe some initial prototyping activities.

  18. Integrated nuclear and conventional theater warfare simulation (inwars) documentation. Part I. Synopsis. Final report

    SciTech Connect

    Aldrich, J.R.; Gilmer, J.B.

    1980-02-08

    This volume constitutes the Synopsis Component of the Integrated Nuclear and Conventional Theater Warfare Simulation (INWARS) documentation. It provides an overview of the simulation in terms of unique features, inputs and outputs, and modes of application. The INWARS representation of theater warfare and its software implementation are then synopsized. INWARS has been developed to provide a tool for investigating interactions among conventional, nuclear, and chemical operations in the context of a theater-level conflict situation. INWARS is also distinguished by its focus on upper-echelon command, control, and intelligence (C22I) processes. In particular, INWARS contains explicit, fully-automated representation of the C2I activities involved in: (1) developing, and executing operations to achieve assigned objectives; (2) considering the employment of conventional, nuclear, or chemical weapons in support of those operations; and, (3) adapting ongoing activities to the perceived threat of enemy nuclear or chemical attacks. Since these activities are driven by generalized doctrines and policies supplied as user-inputs, INWARS can support investigations of alternative doctrinal approaches.

  19. An End-To-End Test of A Simulated Nuclear Electric Propulsion System

    NASA Technical Reports Server (NTRS)

    VanDyke, Melissa; Hrbud, Ivana; Goddfellow, Keith; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    The Safe Affordable Fission Engine (SAFE) test series addresses Phase I Space Fission Systems issues in it particular non-nuclear testing and system integration issues leading to the testing and non-nuclear demonstration of a 400-kW fully integrated flight unit. The first part of the SAFE 30 test series demonstrated operation of the simulated nuclear core and heat pipe system. Experimental data acquired in a number of different test scenarios will validate existing computational models, demonstrated system flexibility (fast start-ups, multiple start-ups/shut downs), simulate predictable failure modes and operating environments. The objective of the second part is to demonstrate an integrated propulsion system consisting of a core, conversion system and a thruster where the system converts thermal heat into jet power. This end-to-end system demonstration sets a precedent for ground testing of nuclear electric propulsion systems. The paper describes the SAFE 30 end-to-end system demonstration and its subsystems.

  20. Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

    SciTech Connect

    Hamilton, Steven P; Clarno, Kevin T; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth

    2012-01-01

    The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms, such as neutron flux distribution, coolant conditions and assembly mechanical stresses, of traditional (single-pin) nuclear fuel performance simulation. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. With this novel capability, AMPFuel was used to model an entire 1717 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics). A full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 160 billion degrees of freedom for 10 loading steps. The single radiation transport calculation required about 50% of the time required to solve the thermo-mechanics with a single loading step, which demonstrates that it is feasible to incorporate, in a single code, a high-fidelity radiation transport capability with a high-fidelity nuclear fuel thermo-mechanics capability and anticipate acceptable computational requirements. The

  1. A Poisson resampling method for simulating reduced counts in nuclear medicine images.

    PubMed

    White, Duncan; Lawson, Richard S

    2015-05-01

    Nuclear medicine computers now commonly offer resolution recovery and other software techniques which have been developed to improve image quality for images with low counts. These techniques potentially mean that these images can give equivalent clinical information to a full-count image. Reducing the number of counts in nuclear medicine images has the benefits of either allowing reduced activity to be administered or reducing acquisition times. However, because acquisition and processing parameters vary, each user should ideally evaluate the use of images with reduced counts within their own department, and this is best done by simulating reduced-count images from the original data. Reducing the counts in an image by division and rounding off to the nearest integer value, even if additional Poisson noise is added, is inadequate because it gives incorrect counting statistics. This technical note describes how, by applying Poisson resampling to the original raw data, simulated reduced-count images can be obtained while maintaining appropriate counting statistics. The authors have developed manufacturer independent software that can retrospectively generate simulated data with reduced counts from any acquired nuclear medicine image. PMID:25880881

  2. A Poisson resampling method for simulating reduced counts in nuclear medicine images.

    PubMed

    White, Duncan; Lawson, Richard S

    2015-05-01

    Nuclear medicine computers now commonly offer resolution recovery and other software techniques which have been developed to improve image quality for images with low counts. These techniques potentially mean that these images can give equivalent clinical information to a full-count image. Reducing the number of counts in nuclear medicine images has the benefits of either allowing reduced activity to be administered or reducing acquisition times. However, because acquisition and processing parameters vary, each user should ideally evaluate the use of images with reduced counts within their own department, and this is best done by simulating reduced-count images from the original data. Reducing the counts in an image by division and rounding off to the nearest integer value, even if additional Poisson noise is added, is inadequate because it gives incorrect counting statistics. This technical note describes how, by applying Poisson resampling to the original raw data, simulated reduced-count images can be obtained while maintaining appropriate counting statistics. The authors have developed manufacturer independent software that can retrospectively generate simulated data with reduced counts from any acquired nuclear medicine image.

  3. Seismic Source Characteristics of Nuclear and Chemical Explosions in Granite from Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Xu, Heming; Rodgers, Arthur J.; Lomov, Ilya N.; Vorobiev, Oleg Y.

    2014-03-01

    Seismic source characteristics of low-yield (0.5-5 kt) underground explosions are inferred from hydrodynamic simulations using a granite material model on high-performance (parallel) computers. We use a non-linear rheological model for granite calibrated to historical near-field nuclear test data. Equivalent elastic P-wave source spectra are derived from the simulated hydrodynamic response using reduced velocity potentials. Source spectra and parameters are compared with the models of M ueller and M urphy (Bull Seism Soc Am 61:1675-1692, 1971, hereafter MM71) and D enny and J ohnson (Explosion source phenomenology, pp 1-24, 1991, hereafter DJ91). The source spectra inferred from the simulations of different yields at normal scaled depth-of-burial (SDOB) match the MM71 spectra reasonably well. For normally buried nuclear explosions, seismic moments are larger for the hydrodynamic simulations than MM71 (by 25 %) and for DJ91 (by over a factor of 2), however, the scaling of moment with yield across this low-yield range is consistent for our calculations and the two models. Spectra from our simulations show higher corner frequencies at the lower end of the 0.5-5.0 kt yield range and stronger variation with yield than the MM71 and DJ91 models predict. The spectra from our simulations have additional energy above the corner frequency, probably related to non-linear near-source effects, but at high frequencies the spectral slopes agree with the f -2 predictions of MM71. Simulations of nuclear explosions for a range of SDOB from 0.5 to 3.9 show stronger variations in the seismic moment than predicted by the MM71 and DJ91 models. Chemical explosions are found to generate higher moments by a factor of about two compared to nuclear explosions of the same yield in granite and at normal depth-of-burial, broadly consistent with comparisons of nuclear and chemical shots at the US Nevada Test Site (D enny, Proceeding of symposium on the non-proliferation experiment, Rockville

  4. Nuclear sensor signal processing circuit

    DOEpatents

    Kallenbach, Gene A.; Noda, Frank T.; Mitchell, Dean J.; Etzkin, Joshua L.

    2007-02-20

    An apparatus and method are disclosed for a compact and temperature-insensitive nuclear sensor that can be calibrated with a non-hazardous radioactive sample. The nuclear sensor includes a gamma ray sensor that generates tail pulses from radioactive samples. An analog conditioning circuit conditions the tail-pulse signals from the gamma ray sensor, and a tail-pulse simulator circuit generates a plurality of simulated tail-pulse signals. A computer system processes the tail pulses from the gamma ray sensor and the simulated tail pulses from the tail-pulse simulator circuit. The nuclear sensor is calibrated under the control of the computer. The offset is adjusted using the simulated tail pulses. Since the offset is set to zero or near zero, the sensor gain can be adjusted with a non-hazardous radioactive source such as, for example, naturally occurring radiation and potassium chloride.

  5. Results from tight and loose coupled multiphysics in nuclear fuels performance simulations using BISON

    SciTech Connect

    Novascone, S. R.; Spencer, B. W.; Andrs, D.; Williamson, R. L.; Hales, J. D.; Perez, D. M.

    2013-07-01

    The behavior of nuclear fuel in the reactor environment is affected by multiple physics, most notably heat conduction and solid mechanics, which can have a strong influence on each other. To provide credible solutions, a fuel performance simulation code must have the ability to obtain solutions for each of the physics, including coupling between them. Solution strategies for solving systems of coupled equations can be categorized as loosely-coupled, where the individual physics are solved separately, keeping the solutions for the other physics fixed at each iteration, or tightly coupled, where the nonlinear solver simultaneously drives down the residual for each physics, taking into account the coupling between the physics in each nonlinear iteration. In this paper, we compare the performance of loosely and tightly coupled solution algorithms for thermomechanical problems involving coupled thermal and mechanical contact, which is a primary source of interdependence between thermal and mechanical solutions in fuel performance models. The results indicate that loosely-coupled simulations require significantly more nonlinear iterations, and may lead to convergence trouble when the thermal conductivity of the gap is too small. We also apply the tightly coupled solution strategy to a nuclear fuel simulation of an experiment in a test reactor. Studying the results from these simulations indicates that perhaps convergence for either approach may be problem dependent, i.e., there may be problems for which a loose coupled approach converges, where tightly coupled won't converge and vice versa. (authors)

  6. Results from Tight and Loose Coupled Multiphysics in Nuclear Fuels Performance Simulations using BISON

    SciTech Connect

    S. R. Novascone; B. W. Spencer; D. Andrs; R. L. Williamson; J. D. Hales; D. M. Perez

    2013-05-01

    The behavior of nuclear fuel in the reactor environment is affected by multiple physics, most notably heat conduction and solid mechanics, which can have a strong influence on each other. To provide credible solutions, a fuel performance simulation code must have the ability to obtain solutions for each of the physics, including coupling between them. Solution strategies for solving systems of coupled equations can be categorized as loosely-coupled, where the individual physics are solved separately, keeping the solutions for the other physics fixed at each iteration, or tightly coupled, where the nonlinear solver simultaneously drives down the residual for each physics, taking into account the coupling between the physics in each nonlinear iteration. In this paper, we compare the performance of loosely and tightly coupled solution algorithms for thermomechanical problems involving coupled thermal and mechanical contact, which is a primary source of interdependence between thermal and mechanical solutions in fuel performance models. The results indicate that loosely-coupled simulations require significantly more nonlinear iterations, and may lead to convergence trouble when the thermal conductivity of the gap is too small. We also apply the tightly coupled solution strategy to a nuclear fuel simulation of an experiment in a test reactor. Studying the results from these simulations indicates that perhaps convergence for either approach may be problem dependent, i.e., there may be problems for which a loose coupled approach converges, where tightly coupled won’t converge and vice versa.

  7. Compact Process Development at Babcock & Wilcox

    SciTech Connect

    Eric Shaber; Jeffrey Phillips

    2012-03-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of compaction trials have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel at packing fractions exceeding 46% by volume. Results from these trials are included. The scale-up effort is nearing completion with the process installed and operable using nuclear fuel materials. Final process testing is in progress to certify the process for manufacture of qualification test fuel compacts in 2012.

  8. Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.

    PubMed

    Szőke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K

    2014-06-01

    This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors. PMID:24727389

  9. Compact LINAC for deuterons

    SciTech Connect

    Kurennoy, S S; O' Hara, J F; Rybarcyk, L J

    2008-01-01

    We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

  10. Ceramic powder compaction

    SciTech Connect

    Glass, S.J.; Ewsuk, K.G.; Mahoney, F.M.

    1995-12-31

    With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.

  11. A Perspective on Coupled Multiscale Simulation and Validation in Nuclear Materials

    SciTech Connect

    M. P. Short; D. Gaston; C. R. Stanek; S. Yip

    2014-01-01

    The field of nuclear materials encompasses numerous opportunities to address and ultimately solve longstanding industrial problems by improving the fundamental understanding of materials through the integration of experiments with multiscale modeling and high-performance simulation. A particularly noteworthy example is an ongoing study of axial power distortions in a nuclear reactor induced by corrosion deposits, known as CRUD (Chalk River unidentified deposits). We describe how progress is being made toward achieving scientific advances and technological solutions on two fronts. Specifically, the study of thermal conductivity of CRUD phases has augmented missing data as well as revealed new mechanisms. Additionally, the development of a multiscale simulation framework shows potential for the validation of a new capability to predict the power distribution of a reactor, in effect direct evidence of technological impact. The material- and system-level challenges identified in the study of CRUD are similar to other well-known vexing problems in nuclear materials, such as irradiation accelerated corrosion, stress corrosion cracking, and void swelling; they all involve connecting materials science fundamentals at the atomistic- and mesoscales to technology challenges at the macroscale.

  12. Uncertainty analysis of atmospheric deposition simulation of radiocesium and radioiodine from Fukushima Daiichi Nuclear Power Plant

    NASA Astrophysics Data System (ADS)

    Morino, Yu; Ohara, Toshimasa; Yumimoto, Keiya

    2014-05-01

    Chemical transport models (CTM) played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant (FDNPP) after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. In this study, we assessed uncertainties of atmospheric simulation by comparing observed and simulated deposition of radiocesium (137Cs) and radioiodine (131I). Airborne monitoring survey data were used to assess the model performance of 137Cs deposition patterns. We found that simulation using emissions estimated with a regional-scale (~500 km) CTM better reproduced the observed 137Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (~50 km) or global-scale CTM. In addition, we estimated the emission amount of 137Cs from FDNPP by combining a CTM, a priori source term, and observed deposition data. This is the first use of airborne survey data of 137Cs deposition (more than 16,000 data points) as the observational constraints in inverse modeling. The model simulation driven by a posteriori source term achieved better agreements with 137Cs depositions measured by aircraft survey and at in-situ stations over eastern Japan. Wet deposition module was also evaluated. Simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed 137Cs deposition rates in high-deposition areas (≥10 kBq m-2) within one order of magnitude. Recently, 131I deposition map was released and helped to evaluate model performance of 131I deposition patterns. Observed 131I/137Cs deposition ratio is higher in areas southwest of FDNPP than northwest of FDNPP, and this behavior was roughly reproduced by a CTM if we assume that released 131I is more in gas phase

  13. Computer simulation of the Sequential Probability Ratio Test for nuclear safeguards

    SciTech Connect

    Coop, K.L.

    1985-07-01

    A Fortran IV computer program called SPRTEST is used to simulate the Sequential Probability Ratio Test (SPRT). The program provides considerably more information than one can obtain from the approximate SPRT theory of Wald. For nuclear safeguards applications SPRTEST permits the equipment designer to optimize the input test parameters and, indeed, to determine whether the SPRT is the statistical test of choice. Using Monte Carlo techniques, SPRTEST simulates the use of the SPRT in a radiation monitor. The accumulation of monitoring data from a normal distribution is simulated by repeated sampling of a random number generator. In this way, SPRTEST determines the expected false-positive (..cap alpha..) and false-negative (..beta..) detection probabilities and the average step number (ASN) for a particular SPRT. The report describes SPRTEST, provides a Fortran listing, and demonstrates SPRTEST applications. The report also compares results with those expected from the single-interval test (SIT) on which the SPRT is based; generally, the SPRT provides better detection probabilities for a wide range of source strengths and, at bakcground levels, it takes less time, on average, to make decisions. To obtain optimal results with the SPRT, it must have the capability to detain the counting subject for longer than the SIT time. The SPRTEST program should be useful in choosing the best statistical test for a wide variety of applications, including safeguards, health physics monitoring, and general nuclear detection. 14 refs., 11 figs., 15 tabs.

  14. Compact orthogonal NMR field sensor

    SciTech Connect

    Gerald, II, Rex E.; Rathke, Jerome W.

    2009-02-03

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  15. Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors

    SciTech Connect

    Bakosi, J.; Christon, M. A.; Lowrie, R. B.; Pritchett-Sheats, L. A.; Nourgaliev, R. R.

    2013-07-12

    The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3 × 3 and 5 × 5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carried out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the singlephase incompressible Navier-Stokes equations. The simulations explicitly resolve the large scale motions of the turbulent flow field using first principles and rely on a monotonicity-preserving numerical technique to represent the unresolved scales. Each series of simulations for the 3 × 3 and 5 × 5 rod-bundle geometries is an analysis of the flow field statistics combined with a mesh-refinement study and validation with available experimental data. Our primary focus is the time history and statistics of the forces loading the fuel rods. These hydrodynamic forces are believed to be the key player resulting in rod vibration and GTRF wear, one of the leading causes for leaking nuclear fuel which costs power utilities millions of dollars in preventive measures. As a result, we demonstrate that implicit large-eddy simulation of rod-bundle flows is a viable way to calculate the excitation forces for the GTRF problem.

  16. Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors

    DOE PAGES

    Bakosi, J.; Christon, M. A.; Lowrie, R. B.; Pritchett-Sheats, L. A.; Nourgaliev, R. R.

    2013-07-12

    The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3 × 3 and 5 × 5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carriedmore » out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the singlephase incompressible Navier-Stokes equations. The simulations explicitly resolve the large scale motions of the turbulent flow field using first principles and rely on a monotonicity-preserving numerical technique to represent the unresolved scales. Each series of simulations for the 3 × 3 and 5 × 5 rod-bundle geometries is an analysis of the flow field statistics combined with a mesh-refinement study and validation with available experimental data. Our primary focus is the time history and statistics of the forces loading the fuel rods. These hydrodynamic forces are believed to be the key player resulting in rod vibration and GTRF wear, one of the leading causes for leaking nuclear fuel which costs power utilities millions of dollars in preventive measures. As a result, we demonstrate that implicit large-eddy simulation of rod-bundle flows is a viable way to calculate the excitation forces for the GTRF problem.« less

  17. Analysis by simulation of the disposition of nuclear-fuel waste

    SciTech Connect

    Turek, J.L.

    1980-09-01

    To achieve the non-proliferation objectives of the United States, the reprocessing of spent nuclear fuel was discontinued in 1977. Since current at-reactor storage capacity is based upon a nuclear fuel cycle which includes reprocessing, this halt in reprocessing is causing large quantities of non-storable spent fuel. Permanent nuclear waste storage repositories will not be available until the end of the century. Present Department of Energy policy calls for sufficient interim Away-From-Reactor (AFR) Storage capacity to insure that no commercial reactor has to shutdown due to inadequate storage space for discharged spent fuel. A descriptive simulation model is developed which includes all aspects of nuclear waste disposition. The model is comprised of two systems, the second system orchestrated by GASP IV. A spent fuel generation prediction module is interfaced with the AFR Program Management Information System and a repository scheduling information module. The user is permitted a wide range of options with which to tailor the simulation to any desired storage scenario. The model projects storage requirements through the year 2020. The outputs are evaluations of the impact that alternative decision policies and milestone date changes have on the demand for, the availability of, and the utilization of spent fuel storage capacities. Both graphs and detailed listings are available. These outputs give a comprehensive view of the particular scenario under observation, including the tracking, by year, of each discharge from every reactor. Included within the work is a review of the status of spent fuel disposition based on input data accurate as of August 1980.

  18. Durabiliy of two simulated nuclear waste glasses, a frit glass, and tektite in aqueous solutions: Final report, Volume I

    SciTech Connect

    Hagen, D.A.; Altstetter, C.J.; Brown, S.D.

    1988-05-01

    High level nuclear waste is commonly incorporated into glass for disposal. Therefore the long term aqueous durability of the waste glass is important. The leaching behavior of three simulated nuclear waste glasses (AH10, AH165, and Frit 165) and a natural glass (tektite) were examined using nuclear reaction analysis, leachate solution analysis, and microscopy. The three simulated waste glasses developed hydrated layers which increased in thickness by t/sup /1/2//. The hydrated layer in Frit 165 reached a constant thickness of about one micron. Alkali were preferentially removed from the Frit 165 and AH10. The tektite corroded by slow uniform dissolution. 94 refs., 68 figs., 13 tabs.

  19. Measurement of leaching from simulated nuclear-waste glass using radiotracers

    SciTech Connect

    Bates, J.K.; Jardine, L.J.; Steindler, M.J.

    1982-09-01

    The use of radiotracer spiking as a method of measuring the leaching from simulated nuclear-waste glass is shown to give results comparable with other analytical detection methods. The leaching behavior of /sup 85/Sr, /sup 106/Ru, /sup 133/Ba, /sup 137/Cs, /sup 141/Ce, /sup 152/Eu, and other isotopes is measured for several defense waste glasses. These tests show that radiotracer spiking is a sensitive, multielement technique that can provide leaching data, for actual waste elements, that are difficult to obtain by other methods. Additionally, a detailed procedure is described that allows spiked glass to be prepared with a suitable distribution of radionuclides.

  20. Measuring Human Performance in Simulated Nuclear Power Plant Control Rooms Using Eye Tracking

    SciTech Connect

    Kovesdi, Casey Robert; Rice, Brandon Charles; Bower, Gordon Ross; Spielman, Zachary Alexander; Hill, Rachael Ann; LeBlanc, Katya Lee

    2015-11-01

    Control room modernization will be an important part of life extension for the existing light water reactor fleet. As part of modernization efforts, personnel will need to gain a full understanding of how control room technologies affect performance of human operators. Recent advances in technology enables the use of eye tracking technology to continuously measure an operator’s eye movement, which correlates with a variety of human performance constructs such as situation awareness and workload. This report describes eye tracking metrics in the context of how they will be used in nuclear power plant control room simulator studies.

  1. A numerical simulation package for analysis of neutronics and thermal fluids of space nuclear power and propulsion systems

    SciTech Connect

    Anghaie, S.; Feller, G.J. ); Peery, S.D.; Parsley, R.C. )

    1993-01-20

    A system of computer codes for engineering simulation and in-depth analysis of nuclear and thermal fluid design of nuclear thermal rockets is developed. The computational system includes a neutronic solver package, a thermal fluid solver package and a propellant and materials property package. The Rocket Engine Transient Simulation (ROCETS) system code is incorporated with computational modules specific to nuclear powered engines. ROCETS features a component based performance architecture that interfaces component modules into the user designed configuration, interprets user commands, creates an executable FORTRAN computer program, and executes the program to provide output to the user. Basic design features of the Pratt Whitney XNR2000 nuclear rocket concept and its operational performance are analyzed and simulated.

  2. System Simulation of Nuclear Power Plant by Coupling RELAP5 and Matlab/Simulink

    SciTech Connect

    Meng Lin; Dong Hou; Zhihong Xu; Yanhua Yang; Ronghua Zhang

    2006-07-01

    Since RELAP5 code has general and advanced features in thermal-hydraulic computation, it has been widely used in transient and accident safety analysis, experiment planning analysis, and system simulation, etc. So we wish to design, analyze, verify a new Instrumentation And Control (I and C) system of Nuclear Power Plant (NPP) based on the best-estimated code, and even develop our engineering simulator. But because of limited function of simulating control and protection system in RELAP5, it is necessary to expand the function for high efficient, accurate, flexible design and simulation of I and C system. Matlab/Simulink, a scientific computation software, just can compensate the limitation, which is a powerful tool in research and simulation of plant process control. The software is selected as I and C part to be coupled with RELAP5 code to realize system simulation of NPPs. There are two key techniques to be solved. One is the dynamic data exchange, by which Matlab/Simulink receives plant parameters and returns control results. Database is used to communicate the two codes. Accordingly, Dynamic Link Library (DLL) is applied to link database in RELAP5, while DLL and S-Function is applied in Matlab/Simulink. The other problem is synchronization between the two codes for ensuring consistency in global simulation time. Because Matlab/Simulink always computes faster than RELAP5, the simulation time is sent by RELAP5 and received by Matlab/Simulink. A time control subroutine is added into the simulation procedure of Matlab/Simulink to control its simulation advancement. Through these ways, Matlab/Simulink is dynamically coupled with RELAP5. Thus, in Matlab/Simulink, we can freely design control and protection logic of NPPs and test it with best-estimated plant model feedback. A test will be shown to illuminate that results of coupling calculation are nearly the same with one of single RELAP5 with control logic. In practice, a real Pressurized Water Reactor (PWR) is

  3. Monte Carlo simulation of a clearance box monitor used for nuclear power plant decommissioning.

    PubMed

    Bochud, François O; Laedermann, Jean-Pascal; Bailat, Claude J; Schuler, Christoph

    2009-05-01

    When decommissioning a nuclear facility it is important to be able to estimate activity levels of potentially radioactive samples and compare with clearance values defined by regulatory authorities. This paper presents a method of calibrating a clearance box monitor based on practical experimental measurements and Monte Carlo simulations. Adjusting the simulation for experimental data obtained using a simple point source permits the computation of absolute calibration factors for more complex geometries with an accuracy of a bit more than 20%. The uncertainty of the calibration factor can be improved to about 10% when the simulation is used relatively, in direct comparison with a measurement performed in the same geometry but with another nuclide. The simulation can also be used to validate the experimental calibration procedure when the sample is supposed to be homogeneous but the calibration factor is derived from a plate phantom. For more realistic geometries, like a small gravel dumpster, Monte Carlo simulation shows that the calibration factor obtained with a larger homogeneous phantom is correct within about 20%, if sample density is taken as the influencing parameter. Finally, simulation can be used to estimate the effect of a contamination hotspot. The research supporting this paper shows that activity could be largely underestimated in the event of a centrally-located hotspot and overestimated for a peripherally-located hotspot if the sample is assumed to be homogeneously contaminated. This demonstrates the usefulness of being able to complement experimental methods with Monte Carlo simulations in order to estimate calibration factors that cannot be directly measured because of a lack of available material or specific geometries. PMID:19359851

  4. Simulations of Failure via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels

    SciTech Connect

    Lu, Hongbing; Bukkapatnam, Satish; Harimkar, Sandip; Singh, Raman; Bardenhagen, Scott

    2014-01-09

    Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear

  5. Integrated nuclear and conventional theater warfare simulation (INWARS) documentation. Part IV. User's manual component. Volume I. Introduction. Final report

    SciTech Connect

    Aldrich, J.R.; Gilmer, J.B.

    1980-02-08

    This is Volume I of the User's Manual Component of the Interpreted Nuclear and Conventional Theater Warfare Simulation (INWARS) documentation. It introduces the User's Manual Component by reviewing the utilization of INWARS and surveying the inputs and outputs of the simulation.

  6. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations.

    PubMed

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells. PMID:25999971

  7. Fission product partitioning in aerosol release from simulated spent nuclear fuel

    NASA Astrophysics Data System (ADS)

    Di Lemma, F. G.; Colle, J. Y.; Rasmussen, G.; Konings, R. J. M.

    2015-10-01

    Aerosols created by the vaporization of simulated spent nuclear fuel (simfuel) were produced by laser heating techniques and characterised by a wide range of post-analyses. In particular attention has been focused on determining the fission product behaviour in the aerosols, in order to improve the evaluation of the source term and consequently the risk associated with release from spent fuel sabotage or accidents. Different simulated spent fuels were tested with burn-up up to 8 at. %. The results from the aerosol characterisation were compared with studies of the vaporization process by Knudsen Effusion Mass Spectrometry and thermochemical equilibrium calculations. These studies permit an understanding of the aerosol gaseous precursors and the gaseous reactions taking place during the aerosol formation process.

  8. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations

    PubMed Central

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells. PMID:25999971

  9. Numerical Simulations of Single Flow Element in a Nuclear Thermal Thrust Chamber

    NASA Technical Reports Server (NTRS)

    Cheng, Gary; Ito, Yasushi; Ross, Doug; Chen, Yen-Sen; Wang, Ten-See

    2007-01-01

    The objective of this effort is to develop an efficient and accurate computational methodology to predict both detailed and global thermo-fluid environments of a single now element in a hypothetical solid-core nuclear thermal thrust chamber assembly, Several numerical and multi-physics thermo-fluid models, such as chemical reactions, turbulence, conjugate heat transfer, porosity, and power generation, were incorporated into an unstructured-grid, pressure-based computational fluid dynamics solver. The numerical simulations of a single now element provide a detailed thermo-fluid environment for thermal stress estimation and insight for possible occurrence of mid-section corrosion. In addition, detailed conjugate heat transfer simulations were employed to develop the porosity models for efficient pressure drop and thermal load calculations.

  10. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations.

    PubMed

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells.

  11. Transient analysis and startup simulation of a thermionic space nuclear reactor system

    SciTech Connect

    El-Genk, M.S.; Xue, Huimin; Paramonov, D. . Dept. of Chemical and Nuclear Engineering)

    1994-01-01

    The thermionic transient analysis model is used to simulate the startup of the TOPAZ-2 space nuclear power system in orbit. The simulated startup procedures are assumed for the purpose of demonstrating the capabilities of the model and may not represent an accurate account of the actual startup procedures of the TOPAZ-2 system. The temperature reactivity feedback effects of the moderator, UO[sub 2] fuel, electrodes, coolant, and other components in the core are calculated, and their effects on the thermal and criticality conditions of the reactor are investigated. Also, estimates of the time constants of the temperature reactivity feedback for the UO[sub 2] fuel and the ZrH moderator during startup, as well as of the total temperature reactivity feedback as a function of the reactor steady-state thermal power, are obtained.

  12. Start-up simulation of a thermionic space nuclear reactor system

    SciTech Connect

    El-Genk, M.S.; Xue, H.; Paramonov, D. )

    1993-01-15

    The Thermionic Transient Analysis Model (TITAM) is used in this paper to simulate the start-up of the TOPAZ-II space nuclear power system in orbit. The start-up procedures simulated herein are assumed for the purpose of demonstrating the capabilities of the model and may not represent an accurate account of the actual start-up procedures of the TOPAZ-II system. The temperature reactivity feedback effects of the moderator, UO[sub 2] fuel, electrodes, coolant, and other components in the core are calculated and their effects on the thermal and criticality conditions of the reactor are investigated. Also, estimates of the time constants of the temperature reactivity feedback for the UO[sub 2] fuel and the ZrH moderator during start-up, as well as of the total temperature reactivity feedback as a function of the reactor steady-state thermal power, are obtained.

  13. Multicomponent leach tests in Standard Canadian Shield Saline Solution on glasses containing simulated nuclear waste

    SciTech Connect

    Heimann, R.B.; Wood, D.D.; Hamon, R.F.

    1984-01-01

    Leaching experiments on borosilicate glass frit and simulated nuclear waste glasses were performed as a preliminary to leaching experiments on glasses incorporating radioactive waste. The experimental design included (1) simulated waste glass, (2) ASTM Grade-2 titanium container material, (3) clay buffer material, (4) Standard Canadian Shield Saline Solution, and (5) granitic rock. Cumulative fractions of release for boron were determined, as well as the solution concentrations of silicon, iron, strontium and cesium. The leach rates for boron after 28 d were approximately 5 x 10/sup -6/ kg x m/sup -2/ x s/sup -1/ in Hastelloy vessels. There is an apparently strong relationship between the clay/groundwater ratio, the concentration of iron in the solution, and the concentrations of silicon, strontium, and cesium.

  14. Corrosion Behavior of Alloy 625 in Simulated Nuclear High-Level Waste Medium

    NASA Astrophysics Data System (ADS)

    Girija, S.; Nandakumar, T.; Mudali, U. Kamachi

    2015-11-01

    The present investigation aims to study the effect of various ions present in nuclear high-level waste (HLW) (acidic) medium on the corrosion resistance of Alloy 625, with solution-annealed and sensitized microstructure. The heat-affected zones are prone to sensitization during welding of components and subsequent exposure to acidic waste during service could result in intergranular corrosion in these regions and hence it was attempted to study the corrosion behavior of the alloy under sensitized conditions. Double loop electrochemical potentiokinetic reactivation test was carried out to obtain the extent of chromium depletion. Potentiodynamic anodic polarization and electrochemical noise investigations were carried out on Alloy 625 in 3 M nitric acid and simulated nuclear HLW medium (prepared in 3 M nitric acid) at 298 K and 323 K. The study showed that the alloy possess good corrosion resistance in 3 M nitric acid and simulated HLW medium. However, a marginal decrease in the corrosion resistance occurred in simulated HLW when compared to the plain acid, as observed from an increase in passivation current density, decrease in transpassive potentials, and decrease in electrochemical noise resistance. Increase in temperature of the medium and change in microstructure from solution-annealed to sensitized state further decreased the corrosion resistance of Alloy 625. Electrochemical noise time records obtained at open circuit conditions showed a stable passive film for 22 h of immersion of the alloy in 3 M nitric acid and simulated HLW. However, the amplitude of current fluctuations was higher for the sensitized microstructure when compared to the solution-annealed microstructure.

  15. A Numerical Simulation of Star Formation in Nuclear Rings of Barred-Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Seo, Woo-Young; Kim, W.

    2014-01-01

    We use grid-based hydrodynamic simulations to study star formation history in nuclear rings of barred-spiral galaxies. We assume infinitesimally thin, isothermal, and unmagnetized gaseous disk. To investigate effects of spiral arm potential, we calculate both models with and without spiral. We find that star formation rate (SFR) in a nuclear ring is determined by the mass inflow rate to the ring rather than the total gas mass in the ring. In case of models without spiral arms, the SFR shows a strong primary burst at early time, and declines to small values after after that. The primary burst is caused by the rapid gas infall to the ring due to the bar growth. On the other hand, models with spiral arms show multiple star bursts at late time caused by additional gas inflow from outside bar region. When the SFR is low, ages of young star clusters exhibit a bipolar azimuthal gradient along the ring since star formation occurs near the contact points between dust lanes and the nuclear ring. When the SFR is large, there are no age gradient of star clusters since star formation sites are widely distributed throughout the whole ring region.

  16. Nuclear EMP simulation for large-scale urban environments. FDTD for electrically large problems.

    SciTech Connect

    Smith, William S.; Bull, Jeffrey S.; Wilcox, Trevor; Bos, Randall J.; Shao, Xuan-Min; Goorley, John T.; Costigan, Keeley R.

    2012-08-13

    In case of a terrorist nuclear attack in a metropolitan area, EMP measurement could provide: (1) a prompt confirmation of the nature of the explosion (chemical or nuclear) for emergency response; and (2) and characterization parameters of the device (reaction history, yield) for technical forensics. However, urban environment could affect the fidelity of the prompt EMP measurement (as well as all other types of prompt measurement): (1) Nuclear EMP wavefront would no longer be coherent, due to incoherent production, attenuation, and propagation of gamma and electrons; and (2) EMP propagation from source region outward would undergo complicated transmission, reflection, and diffraction processes. EMP simulation for electrically-large urban environment: (1) Coupled MCNP/FDTD (Finite-difference time domain Maxwell solver) approach; and (2) FDTD tends to be limited to problems that are not 'too' large compared to the wavelengths of interest because of numerical dispersion and anisotropy. We use a higher-order low-dispersion, isotropic FDTD algorithm for EMP propagation.

  17. Nuclear Energy Advanced Modeling and Simulation Waste Integrated Performance and Safety Codes (NEAMS Waste IPSC).

    SciTech Connect

    Schultz, Peter Andrew

    2011-12-01

    The objective of the U.S. Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation Waste Integrated Performance and Safety Codes (NEAMS Waste IPSC) is to provide an integrated suite of computational modeling and simulation (M&S) capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive-waste storage facility or disposal repository. Achieving the objective of modeling the performance of a disposal scenario requires describing processes involved in waste form degradation and radionuclide release at the subcontinuum scale, beginning with mechanistic descriptions of chemical reactions and chemical kinetics at the atomic scale, and upscaling into effective, validated constitutive models for input to high-fidelity continuum scale codes for coupled multiphysics simulations of release and transport. Verification and validation (V&V) is required throughout the system to establish evidence-based metrics for the level of confidence in M&S codes and capabilities, including at the subcontiunuum scale and the constitutive models they inform or generate. This Report outlines the nature of the V&V challenge at the subcontinuum scale, an approach to incorporate V&V concepts into subcontinuum scale modeling and simulation (M&S), and a plan to incrementally incorporate effective V&V into subcontinuum scale M&S destined for use in the NEAMS Waste IPSC work flow to meet requirements of quantitative confidence in the constitutive models informed by subcontinuum scale phenomena.

  18. Physics-based multiscale coupling for full core nuclear reactor simulation

    SciTech Connect

    Gaston, Derek R.; Permann, Cody J.; Peterson, John W.; Slaughter, Andrew E.; Andrš, David; Wang, Yaqi; Short, Michael P.; Perez, Danielle M.; Tonks, Michael R.; Ortensi, Javier; Zou, Ling; Martineau, Richard C.

    2015-10-01

    Numerical simulation of nuclear reactors is a key technology in the quest for improvements in efficiency, safety, and reliability of both existing and future reactor designs. Historically, simulation of an entire reactor was accomplished by linking together multiple existing codes that each simulated a subset of the relevant multiphysics phenomena. Recent advances in the MOOSE (Multiphysics Object Oriented Simulation Environment) framework have enabled a new approach: multiple domain-specific applications, all built on the same software framework, are efficiently linked to create a cohesive application. This is accomplished with a flexible coupling capability that allows for a variety of different data exchanges to occur simultaneously on high performance parallel computational hardware. Examples based on the KAIST-3A benchmark core, as well as a simplified Westinghouse AP-1000 configuration, demonstrate the power of this new framework for tackling—in a coupled, multiscale manner—crucial reactor phenomena such as CRUD-induced power shift and fuel shuffle. 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-SA license

  19. Physics-based multiscale coupling for full core nuclear reactor simulation

    DOE PAGES

    Gaston, Derek R.; Permann, Cody J.; Peterson, John W.; Slaughter, Andrew E.; Andrš, David; Wang, Yaqi; Short, Michael P.; Perez, Danielle M.; Tonks, Michael R.; Ortensi, Javier; et al

    2015-10-01

    Numerical simulation of nuclear reactors is a key technology in the quest for improvements in efficiency, safety, and reliability of both existing and future reactor designs. Historically, simulation of an entire reactor was accomplished by linking together multiple existing codes that each simulated a subset of the relevant multiphysics phenomena. Recent advances in the MOOSE (Multiphysics Object Oriented Simulation Environment) framework have enabled a new approach: multiple domain-specific applications, all built on the same software framework, are efficiently linked to create a cohesive application. This is accomplished with a flexible coupling capability that allows for a variety of different datamore » exchanges to occur simultaneously on high performance parallel computational hardware. Examples based on the KAIST-3A benchmark core, as well as a simplified Westinghouse AP-1000 configuration, demonstrate the power of this new framework for tackling—in a coupled, multiscale manner—crucial reactor phenomena such as CRUD-induced power shift and fuel shuffle. 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-SA license« less

  20. Nuclear fuel cycle system simulation tool based on high-fidelity component modeling

    SciTech Connect

    Ames, David E.

    2014-02-01

    The DOE is currently directing extensive research into developing fuel cycle technologies that will enable the safe, secure, economic, and sustainable expansion of nuclear energy. The task is formidable considering the numerous fuel cycle options, the large dynamic systems that each represent, and the necessity to accurately predict their behavior. The path to successfully develop and implement an advanced fuel cycle is highly dependent on the modeling capabilities and simulation tools available for performing useful relevant analysis to assist stakeholders in decision making. Therefore a high-fidelity fuel cycle simulation tool that performs system analysis, including uncertainty quantification and optimization was developed. The resulting simulator also includes the capability to calculate environmental impact measures for individual components and the system. An integrated system method and analysis approach that provides consistent and comprehensive evaluations of advanced fuel cycles was developed. A general approach was utilized allowing for the system to be modified in order to provide analysis for other systems with similar attributes. By utilizing this approach, the framework for simulating many different fuel cycle options is provided. Two example fuel cycle configurations were developed to take advantage of used fuel recycling and transmutation capabilities in waste management scenarios leading to minimized waste inventories.

  1. Simulation of beta radiator handling procedures in nuclear medicine by means of a movable hand phantom.

    PubMed

    Blunck, Ch; Becker, F; Urban, M

    2011-03-01

    In nuclear medicine therapies, people working with beta radiators such as (90)Y may be exposed to non-negligible partial body doses. For radiation protection, it is important to know the characteristics of the radiation field and possible dose exposures at relevant positions in the working area. Besides extensive measurements, simulations can provide these data. For this purpose, a movable hand phantom for Monte Carlo simulations was developed. Specific beta radiator handling scenarios can be modelled interactively with forward kinematics or automatically with an inverse kinematics procedure. As a first investigation, the dose distribution on a medical doctor's hand injecting a (90)Y solution was measured and simulated with the phantom. Modelling was done with the interactive method based on five consecutive frames from a video recorded during the injection. Owing to the use of only one camera, not each detail of the radiation scenario is visible in the video. In spite of systematic uncertainties, the measured and simulated dose values are in good agreement.

  2. Reducing numerical costs for core wide nuclear reactor CFD simulations by the Coarse-Grid-CFD

    NASA Astrophysics Data System (ADS)

    Viellieber, Mathias; Class, Andreas G.

    2013-11-01

    Traditionally complete nuclear reactor core simulations are performed with subchannel analysis codes, that rely on experimental and empirical input. The Coarse-Grid-CFD (CGCFD) intends to replace the experimental or empirical input with CFD data. The reactor core consists of repetitive flow patterns, allowing the general approach of creating a parametrized model for one segment and composing many of those to obtain the entire reactor simulation. The method is based on a detailed and well-resolved CFD simulation of one representative segment. From this simulation we extract so-called parametrized volumetric forces which close, an otherwise strongly under resolved, coarsely-meshed model of a complete reactor setup. While the formulation so far accounts for forces created internally in the fluid others e.g. obstruction and flow deviation through spacers and wire wraps, still need to be accounted for if the geometric details are not represented in the coarse mesh. These are modelled with an Anisotropic Porosity Formulation (APF). This work focuses on the application of the CGCFD to a complete reactor core setup and the accomplishment of the parametrization of the volumetric forces.

  3. A virtual control room with an embedded, interactive nuclear reactor simulator

    SciTech Connect

    Markidis, S.; Rizwan, U.

    2006-07-01

    The use of virtual nuclear control room can be an effective and powerful tool for training personnel working in the nuclear power plants. Operators could experience and simulate the functioning of the plant, even in critical situations, without being in a real power plant or running any risk. 3D models can be exported to Virtual Reality formats and then displayed in the Virtual Reality environment providing an immersive 3D experience. However, two major limitations of this approach are that 3D models exhibit static textures, and they are not fully interactive and therefore cannot be used effectively in training personnel. In this paper we first describe a possible solution for embedding the output of a computer application in a 3D virtual scene, coupling real-world applications and VR systems. The VR system reported here grabs the output of an application running on an X server; creates a texture with the output and then displays it on a screen or a wall in the virtual reality environment. We then propose a simple model for providing interaction between the user in the VR system and the running simulator. This approach is based on the use of internet-based application that can be commanded by a laptop or tablet-pc added to the virtual environment. (authors)

  4. Comparison of chemical and nuclear explosions: Numerical simulations of the Non-Proliferation Experiment

    SciTech Connect

    Kamm, J.R.; Bos, R.J.

    1995-06-01

    In this paper the authors discuss numerical simulations of the Non-Proliferation Experiment (NPE), which was an underground explosion conducted in September 1993 in the volcanic tuff of the Nevada Test Site. The NPE source consisted of 1.29 {times} 10{sup 6} kg of ANFO-emulsion blasting agent, with the approximate energy of 1.1 kt, emplaced 389 m beneath the surface of Rainier Mesa. The authors compare detailed numerical simulations of the NPE with data collected from that experiment, and with calculations of an equally energetic nuclear explosion in identical geology. Calculated waveforms, at ranges out to approximately 1 km, agree moderately well in the time domain with free-field data, and are in qualitative agreement with free-surface records. Comparison of computed waveforms for equally energetic chemical and nuclear sources reveals relatively minor differences beyond the immediate near-source region, with the chemical source having an {approximately}25% greater seismic moment but otherwise indistinguishable (close-in) seismic source properties. 41 refs., 67 figs., 7 tabs.

  5. Simulation of differential die-away instrument’s response to asymmetrically burned spent nuclear fuel

    DOE PAGES

    Martinik, Tomas; Henzl, Vladimir; Grape, Sophie; Svard, Staffan Jacobsson; Jansson, Peter; Swinhoe, Martyn T.; Tobin, Stephen J.

    2015-03-04

    Here, previous simulation studies of Differential Die–Away (DDA) instrument’s response to active interrogation of spent nuclear fuel from a pressurized water reactor (PWR) yielded promising results in terms of its capability to accurately measure or estimate basic spent fuel assembly (SFA) characteristics, such as multiplication, initial enrichment (IE) and burn-up (BU) as well as the total plutonium content. These studies were however performed only for a subset of idealized SFAs with a symmetric BU with respect to its longitudinal axis. Therefore, to complement the previous results, additional simulations have been performed of the DDA instrument’s response to interrogation of asymmetricallymore » burned spent nuclear fuel in order to determine whether detailed assay of SFAs from all 4 sides will be necessary in real life applications or whether a cost and time saving single sided assay could be used to achieve results of similar quality as previously reported in case of symmetrically burned SFAs.« less

  6. Thermal striping in nuclear reactors: POD analysis of LES simulations and experiment

    NASA Astrophysics Data System (ADS)

    Merzari, Elia; Alvarez, Andres; Marin, Oana; Obabko, Aleksandr; Lomperski, Steve; Aithal, Shashi

    2015-11-01

    Thermal fatigue caused due to thermal striping impacts design and analyses of a wide-range of industrial apparatus. This phenomena is of particular significance in nuclear reactor applications, primarily in sodium cooled fast reactors. In order to conduct systematic analyses of the thermal striping phenomena a simplified experimental set-up was designed and built at Argonne National Laboratory. In this set-up two turbulent jets with a temperature difference of about 20K were mixed in a rectangular tank. The jets entered the tank via 2 hexagonal inlets. Two different inlet geometries were studied, both experimentally and via high-fidelity LES simulations. Proper Orthogonal Decomposition (POD) was performed on the turbulent velocity field in the tank to identify the most dominant energetic modes. The POD analyses of the experimental data in both inlet geometrical configurations were compared with LES simulations. Detailed POD analyses are presented to highlight the impact of geometry on the velocity and thermal fields. These can be correlated with experimental and numerical data to assess the impact of thermal striping on the design of the upper plenum of sodium-cooled nuclear reactors. ALCF.

  7. LWR spent fuel reduction by the removal of U and the compact storage of Pu with FP for long-term nuclear sustainability

    SciTech Connect

    Fukasawa, T.; Hoshino, K.; Takano, M.; Sato, S.; Shimazu, Y.

    2013-07-01

    Fast breeder reactors (FBR) nuclear fuel cycle is needed for long-term nuclear sustainability while preventing global warming and maximum utilizing the limited uranium (U) resources. The 'Framework for Nuclear Energy Policy' by the Japanese government on October 2005 stated that commercial FBR deployment will start around 2050 under its suitable conditions by the successive replacement of light water reactors (LWR) to FBR. Even after Fukushima Daiichi Nuclear Power Plant accident which made Japanese tendency slow down the nuclear power generation activities, Japan should have various options for energy resources including nuclear, and also consider the delay of FBR deployment and increase of LWR spent fuel (LWR-SF) storage amounts. As plutonium (Pu) for FBR deployment will be supplied from LWR-SF reprocessing and Japan will not possess surplus Pu, the authors have developed the flexible fuel cycle initiative (FFCI) for the transition from LWR to FBR. The FFCI system is based on the possibility to stored recycled materials (U, Pu)temporarily for a suitable period according to the FBR deployment rate to control the Pu demand/supply balance. This FFCI system is also effective after the Fukushima accident for the reduction of LWR-SF and future LWR-to-FBR transition. (authors)

  8. High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing: Analysis and Initial Test Results

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David; Kapernick, Richard

    2007-01-01

    Non-nuclear testing can be a valuable tool in the development of a space nuclear power system, providing system characterization data and allowing one to work through various fabrication, assembly and integration issues without the cost and time associated with a full ground nuclear test. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Testing with non-optimized heater elements allows one to assess thermal, heat transfer. and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. High fidelity thermal simulators that match both the static and the dynamic fuel pin performance that would be observed in an operating, fueled nuclear reactor can vastly increase the value of non-nuclear test results. With optimized simulators, the integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and fueled nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics and assess potential design improvements at relatively small fiscal investment. Initial conceptual thermal simulator designs are determined by simple one-dimensional analysis at a single axial location and at steady state conditions; feasible concepts are then input into a detailed three-dimensional model for comparison to expected fuel pin performance. Static and dynamic fuel pin performance for a proposed reactor design is determined using SINDA/FLUINT thermal analysis software, and comparison is made between the expected nuclear performance and the performance of conceptual thermal simulator designs. Through a series of iterative analyses, a conceptual high fidelity design is developed

  9. High Level Requirements for the Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)

    SciTech Connect

    Rich Johnson; Hyung Lee; Kimberlyn C. Mousseau

    2011-09-01

    The US Department of Energy, Office of Nuclear Energy (DOE-NE), has been tasked with the important mission of ensuring that nuclear energy remains a compelling and viable energy source in the U.S. The motivations behind this mission include cost-effectively meeting the expected increases in the power needs of the country, reducing carbon emissions and reducing dependence on foreign energy sources. In the near term, to ensure that nuclear power remains a key element of U.S. energy strategy and portfolio, the DOE-NE will be working with the nuclear industry to support safe and efficient operations of existing nuclear power plants. In the long term, to meet the increasing energy needs of the U.S., the DOE-NE will be investing in research and development (R&D) and working in concert with the nuclear industry to build and deploy new, safer and more efficient nuclear power plants. The safe and efficient operations of existing nuclear power plants and designing, licensing and deploying new reactor designs, however, will require focused R&D programs as well as the extensive use and leveraging of advanced modeling and simulation (M&S). M&S will play a key role in ensuring safe and efficient operations of existing and new nuclear reactors. The DOE-NE has been actively developing and promoting the use of advanced M&S in reactor design and analysis through its R&D programs, e.g., the Nuclear Energy Advanced Modeling and Simulation (NEAMS) and Consortium for Advanced Simulation of Light Water Reactors (CASL) programs. Also, nuclear reactor vendors are already using CFD and CSM, for design, analysis, and licensing. However, these M&S tools cannot be used with confidence for nuclear reactor applications unless accompanied and supported by verification and validation (V&V) and uncertainty quantification (UQ) processes and procedures which provide quantitative measures of uncertainty for specific applications. The Nuclear Energy Knowledge base for Advanced Modeling and Simulation

  10. Coupled thermochemical, isotopic evolution and heat transfer simulations in highly irradiated UO2 nuclear fuel

    NASA Astrophysics Data System (ADS)

    Piro, M. H. A.; Banfield, J.; Clarno, K. T.; Simunovic, S.; Besmann, T. M.; Lewis, B. J.; Thompson, W. T.

    2013-10-01

    Predictive capabilities for simulating irradiated nuclear fuel behavior are enhanced in the current work by coupling thermochemistry, isotopic evolution and heat transfer. Thermodynamic models that are incorporated into this framework not only predict the departure from stoichiometry of UO2, but also consider dissolved fission and activation products in the fluorite oxide phase, noble metal inclusions, secondary oxides including uranates, zirconates, molybdates and the gas phase. Thermochemical computations utilize the spatial and temporal evolution of the fission and activation product inventory in the pellet, which is typically neglected in nuclear fuel performance simulations. Isotopic computations encompass the depletion, decay and transmutation of more than 2000 isotopes that are calculated at every point in space and time. These computations take into consideration neutron flux depression and the increased production of fissile plutonium near the fuel pellet periphery (i.e., the so-called “rim effect”). Thermochemical and isotopic predictions are in very good agreement with reported experimental measurements of highly irradiated UO2 fuel with an average burnup of 102 GW d t(U)-1. Simulation results demonstrate that predictions are considerably enhanced when coupling thermochemical and isotopic computations in comparison to empirical correlations. Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  11. Atomistic Simulations of Mass and Thermal Transport in Oxide Nuclear Fuels

    SciTech Connect

    Andersson, Anders D.; Uberuaga, Blas P.; Du, Shiyu; Liu, Xiang-Yang; Nerikar, Pankaj; Stanek, Christopher R.; Tonks, Michael; Millet, Paul; Biner, Bulent

    2012-06-04

    In this talk we discuss simulations of the mass and thermal transport in oxide nuclear fuels. Redistribution of fission gases such as Xe is closely coupled to nuclear fuel performance. Most fission gases have low solubility in the fuel matrix, specifically the insolubility is most pronounced for large fission gas atoms such as Xe, and as a result there is a significant driving force for segregation of gas atoms to grain boundaries or dislocations and subsequently for nucleation of gas bubbles at these sinks. The first step of the fission gas redistribution is diffusion of individual gas atoms through the fuel matrix to existing sinks, which is governed by the activation energy for bulk diffusion. Fission gas bubbles are then formed by either separate nucleation events or by filling voids that were nucleated at a prior stage; in both cases their formation and latter growth is coupled to vacancy dynamics and thus linked to the production of vacancies via irradiation or thermal events. In order to better understand bulk Xe behavior (diffusion mechanisms) in UO{sub 2{+-}x} we first calculate the relevant activation energies using density functional theory (DFT) techniques. By analyzing a combination of Xe solution thermodynamics, migration barriers and the interaction of dissolved Xe atoms with U, we demonstrate that Xe diffusion predominantly occurs via a vacancy-mediated mechanism, though other alternatives may exist in high irradiation fields. Since Xe transport is closely related to diffusion of U vacancies, we have also studied the activation energy for this process. In order to explain the low value of 2.4 eV found for U migration from independent damage experiments (not thermal equilibrium) the presence of vacancy clusters must be included in the analysis. Next a continuum transport model for Xe and U is formulated based on the diffusion mechanisms established from DFT. After combining this model with descriptions of the interaction between Xe and grain

  12. Nuclear reaction measurements on tissue-equivalent materials and GEANT4 Monte Carlo simulations for hadrontherapy

    NASA Astrophysics Data System (ADS)

    De Napoli, M.; Romano, F.; D'Urso, D.; Licciardello, T.; Agodi, C.; Candiano, G.; Cappuzzello, F.; Cirrone, G. A. P.; Cuttone, G.; Musumarra, A.; Pandola, L.; Scuderi, V.

    2014-12-01

    When a carbon beam interacts with human tissues, many secondary fragments are produced into the tumor region and the surrounding healthy tissues. Therefore, in hadrontherapy precise dose calculations require Monte Carlo tools equipped with complex nuclear reaction models. To get realistic predictions, however, simulation codes must be validated against experimental results; the wider the dataset is, the more the models are finely tuned. Since no fragmentation data for tissue-equivalent materials at Fermi energies are available in literature, we measured secondary fragments produced by the interaction of a 55.6 MeV u-1 12C beam with thick muscle and cortical bone targets. Three reaction models used by the Geant4 Monte Carlo code, the Binary Light Ions Cascade, the Quantum Molecular Dynamic and the Liege Intranuclear Cascade, have been benchmarked against the collected data. In this work we present the experimental results and we discuss the predictive power of the above mentioned models.

  13. The study of ionization by electron impact of a substance simulating spent nuclear fuel components

    NASA Astrophysics Data System (ADS)

    Antonov, N. N.; Bochkarev, E. I.; Gavrikov, A. V.; Samokhin, A. A.; Smirnov, V. P.

    2015-11-01

    Plasma sources of model substances are necessary to solve problems associated with development of the spent nuclear fuel (SNF) plasma separation method. Lead was chosen to simulate kinetic and dynamic properties of the heavy SNF components. In this paper we present the results of a study of a lead vapor discharge with a lead concentration of 1012-1013 cm-3. Ionization was carried out by an electron beam (with energy of up to 500 eV per electron) inside a centimeter gap between planar electrodes. The discharge was numerically modeled using the hydrodynamic and single-particle approximation. Current-voltage characteristics and single ionization efficiency were obtained as functions of the vapors concentration and thermoelectric current. An ion current of hundreds of microamperes at the ionization efficiency near tenths of a percent was experimentally obtained. These results are in good agreement with our model.

  14. Nuclear Reaction Models Responsible for Simulation of Neutron-induced Soft Errors in Microelectronics

    SciTech Connect

    Watanabe, Y. Abe, S.

    2014-06-15

    Terrestrial neutron-induced soft errors in MOSFETs from a 65 nm down to a 25 nm design rule are analyzed by means of multi-scale Monte Carlo simulation using the PHITS-HyENEXSS code system. Nuclear reaction models implemented in PHITS code are validated by comparisons with experimental data. From the analysis of calculated soft error rates, it is clarified that secondary He and H ions provide a major impact on soft errors with decreasing critical charge. It is also found that the high energy component from 10 MeV up to several hundreds of MeV in secondary cosmic-ray neutrons has the most significant source of soft errors regardless of design rule.

  15. Three dimensional coupled simulation of thermomechanics, heat, and oxygen diffusion in UO2 nuclear fuel rods

    SciTech Connect

    Chris Newman; Glen Hansen; Derek Gaston

    2009-07-01

    The simulation of nuclear reactor fuel performance involves complex thermomechanical processes between fuel pellets, made of fissile material, and the protective cladding barrier that surrounds the pellets. This paper examines asubset of phenomena that are important in the development of a predictive capability for fuel performance calculations, focusing on thermomechanics and diffusion within UO2 fuel pellets. In this study, correlations from the literature are used for thermal conductivity, specific heat, and oxygen diffusion. This study develops a three dimensional thermomechanical model fully-coupled to an oxygen diffusion model. Both steady state and transient results are examined to compare this three dimensional model with the literature. Further, this equation system is solved in a parallel, fully-coupled, fully-implicit manner using a preconditioned Jacobian-free Newton Krylov method. Numerical results are presented to explore the efficacy of this approach for examining selected fuel performance problems. INL’s BISON fuels performance code is used to perform this analysis.

  16. The Nuclear Energy Advanced Modeling and Simulation Enabling Computational Technologies FY09 Report

    SciTech Connect

    Diachin, L F; Garaizar, F X; Henson, V E; Pope, G

    2009-10-12

    In this document we report on the status of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Enabling Computational Technologies (ECT) effort. In particular, we provide the context for ECT In the broader NEAMS program and describe the three pillars of the ECT effort, namely, (1) tools and libraries, (2) software quality assurance, and (3) computational facility (computers, storage, etc) needs. We report on our FY09 deliverables to determine the needs of the integrated performance and safety codes (IPSCs) in these three areas and lay out the general plan for software quality assurance to meet the requirements of DOE and the DOE Advanced Fuel Cycle Initiative (AFCI). We conclude with a brief description of our interactions with the Idaho National Laboratory computer center to determine what is needed to expand their role as a NEAMS user facility.

  17. New approach to creation of geometrical module for nuclear reactor neutron transport computer simulation analysis

    SciTech Connect

    Poveschenko, T.; Poveschenko, O.

    2012-07-01

    This paper presents the new approach to creation of geometrical module for nuclear reactor neutron transport computer simulation analysis so called the differential cross method. It is elaborated for detecting boards between physical zones. It is proposed to use GMSH open source mesh editor extended by some features: a special option and a special kind of mesh (cubic background mesh).This method is aimed into Monte Carlo Method as well as for deterministic neutron transport methods. Special attention is attended for reactor core composed of a set of material zones with complicate geometrical boundaries. The idea of this approach is described. In general case method works for 3-D space. Algorithm of creation of the geometrical module is given. 2-D neutron transport benchmark-test for RBMK reactor cluster cell is described. It demonstrates the ability of this approach to provide flexible definition of geometrical meshing with preservation of curved surface or any level of heterogeneity. (authors)

  18. Description of an aircraft lightning and simulated nuclear electromagnetic pulse (NEMP) threat based on experimental data

    NASA Technical Reports Server (NTRS)

    Rustan, Pedro L., Jr.

    1987-01-01

    Lightning data obtained by measuring the surface electromagnetic fields on a CV-580 research aircraft during 48 lightning strikes between 1500 and 18,000 feet in central Florida during the summers of 1984 and 1985, and nuclear electromagnetic pulse (NEMP) data obtained by surface electromagnetic field measurements using a 1:74 CV-580 scale model, are presented. From one lightning event, maximum values of 3750 T/s for the time rate of change of the surface magnetic flux density, and 4.7 kA for the peak current, were obtained. From the simulated NEMP test, maximum values of 40,000 T/s for the time rate of change of the surface magnetic flux density, and 90 A/sq m for the total normal current density, were found. The data have application to the development of a military aircraft lightning/NEMP standard.

  19. Verifiable Fuel Cycle Simulation Model (VISION): A Tool for Analyzing Nuclear Fuel Cycle Futures

    SciTech Connect

    Jacob J. Jacobson; Steven J. Piet; Gretchen E. Matthern; David E. Shropshire; Robert F. Jeffers; A. M. Yacout; Tyler Schweitzer

    2010-11-01

    The nuclear fuel cycle consists of a set of complex components that are intended to work together. To support the nuclear renaissance, it is necessary to understand the impacts of changes and timing of events in any part of the fuel cycle system such as how the system would respond to each technological change, a series of which moves the fuel cycle from where it is to a postulated future state. The system analysis working group of the United States research program on advanced fuel cycles (formerly called the Advanced Fuel Cycle Initiative) is developing a dynamic simulation model, VISION, to capture the relationships, timing, and changes in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model components and some examples of how to use VISION. For example, VISION users can now change yearly the selection of separation or reactor technologies, the performance characteristics of those technologies, and/or the routing of material among separation and reactor types - with the model still operating on a PC in <5 min.

  20. Evaluation and Numerical Simulation of Tsunami for Coastal Nuclear Power Plants of India

    SciTech Connect

    Sharma, Pavan K.; Singh, R.K.; Ghosh, A.K.; Kushwaha, H.S.

    2006-07-01

    Recent tsunami generated on December 26, 2004 due to Sumatra earthquake of magnitude 9.3 resulted in inundation at the various coastal sites of India. The site selection and design of Indian nuclear power plants demand the evaluation of run up and the structural barriers for the coastal plants: Besides it is also desirable to evaluate the early warning system for tsunami-genic earthquakes. The tsunamis originate from submarine faults, underwater volcanic activities, sub-aerial landslides impinging on the sea and submarine landslides. In case of a submarine earthquake-induced tsunami the wave is generated in the fluid domain due to displacement of the seabed. There are three phases of tsunami: generation, propagation, and run-up. Reactor Safety Division (RSD) of Bhabha Atomic Research Centre (BARC), Trombay has initiated computational simulation for all the three phases of tsunami source generation, its propagation and finally run up evaluation for the protection of public life, property and various industrial infrastructures located on the coastal regions of India. These studies could be effectively utilized for design and implementation of early warning system for coastal region of the country apart from catering to the needs of Indian nuclear installations. This paper presents some results of tsunami waves based on different analytical/numerical approaches with shallow water wave theory. (authors)

  1. Nuclear Engine System Simulation (NESS). Version 2.0: Program user's guide

    NASA Technical Reports Server (NTRS)

    Pelaccio, Dennis G.; Scheil, Christine M.; Petrosky, Lyman

    1993-01-01

    This Program User's Guide discusses the Nuclear Thermal Propulsion (NTP) engine system design features and capabilities modeled in the Nuclear Engine System Simulation (NESS): Version 2.0 program (referred to as NESS throughout the remainder of this document), as well as its operation. NESS was upgraded to include many new modeling capabilities not available in the original version delivered to NASA LeRC in Dec. 1991, NESS's new features include the following: (1) an improved input format; (2) an advanced solid-core NERVA-type reactor system model (ENABLER 2); (3) a bleed-cycle engine system option; (4) an axial-turbopump design option; (5) an automated pump-out turbopump assembly sizing option; (6) an off-design gas generator engine cycle design option; (7) updated hydrogen properties; (8) an improved output format; and (9) personal computer operation capability. Sample design cases are presented in the user's guide that demonstrate many of the new features associated with this upgraded version of NESS, as well as design modeling features associated with the original version of NESS.

  2. Simulation of differential die-away instrument's response to asymmetrically burned spent nuclear fuel

    NASA Astrophysics Data System (ADS)

    Martinik, Tomas; Henzl, Vladimir; Grape, Sophie; Svärd, Staffan Jacobsson; Jansson, Peter; Swinhoe, Martyn T.; Tobin, Stephen J.

    2015-07-01

    Previous simulation studies of Differential Die-Away (DDA) instrument's response to active interrogation of spent nuclear fuel from a pressurized water reactor (PWR) yielded promising results in terms of its capability to accurately measure or estimate basic spent fuel assembly (SFA) characteristics, such as multiplication, initial enrichment (IE) and burn-up (BU) as well as the total plutonium content. These studies were however performed only for a subset of idealized SFAs with a symmetric BU with respect to its longitudinal axis. Therefore, to complement the previous results, additional simulations have been performed of the DDA instrument's response to interrogation of asymmetrically burned spent nuclear fuel in order to determine whether detailed assay of SFAs from all 4 sides will be necessary in real life applications or whether a cost and time saving single sided assay could be used to achieve results of similar quality as previously reported in case of symmetrically burned SFAs. The results of this study suggest that DDA instrument response depends on the position of the individual neutron detectors and in fact can be split in two modes. The first mode, measured by the back detectors, is not significantly sensitive to the spatial distribution of fissile isotopes and neutron absorbers, but rather reflects the total amount of both contributors as in the cases of symmetrically burned SFAs. In contrary, the second mode, measured by the front detectors, yields certain sensitivity to the orientation of the asymmetrically burned SFA inside the assaying instrument. This study thus provides evidence that the DDA instrument can potentially be utilized as necessary in both ways, i.e. a quick determination of the average SFA characteristics in a single assay, as well as a more detailed characterization involving several DDA observables through assay of the SFA from all of its four sides that can possibly map the burn-up distribution and/or identify diversion or

  3. The Nuclear Energy Advanced Modeling and Simulation Safeguards and Separations Reprocessing Plant Toolkit

    SciTech Connect

    McCaskey, Alex; Billings, Jay Jay; de Almeida, Valmor F

    2011-08-01

    This report details the progress made in the development of the Reprocessing Plant Toolkit (RPTk) for the DOE Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. RPTk is an ongoing development effort intended to provide users with an extensible, integrated, and scalable software framework for the modeling and simulation of spent nuclear fuel reprocessing plants by enabling the insertion and coupling of user-developed physicochemical modules of variable fidelity. The NEAMS Safeguards and Separations IPSC (SafeSeps) and the Enabling Computational Technologies (ECT) supporting program element have partnered to release an initial version of the RPTk with a focus on software usability and utility. RPTk implements a data flow architecture that is the source of the system's extensibility and scalability. Data flows through physicochemical modules sequentially, with each module importing data, evolving it, and exporting the updated data to the next downstream module. This is accomplished through various architectural abstractions designed to give RPTk true plug-and-play capabilities. A simple application of this architecture, as well as RPTk data flow and evolution, is demonstrated in Section 6 with an application consisting of two coupled physicochemical modules. The remaining sections describe this ongoing work in full, from system vision and design inception to full implementation. Section 3 describes the relevant software development processes used by the RPTk development team. These processes allow the team to manage system complexity and ensure stakeholder satisfaction. This section also details the work done on the RPTk ``black box'' and ``white box'' models, with a special focus on the separation of concerns between the RPTk user interface and application runtime. Section 4 and 5 discuss that application runtime component in more detail, and describe the dependencies, behavior, and rigorous testing of its constituent components.

  4. Compact Laser-Compton X-ray Source Development

    NASA Astrophysics Data System (ADS)

    Yeh, Po-Chun

    The state-of-the-art X-ray source based on inverse-Compton scattering between a high-brightness, relativistic electron beam produced by an X-band RF accelerator and a high-intensity laser pulse generated by chirped-pulse amplification (CPA) has been carried out by our research team at Lawrence Livermore National Laboratory. This system is called "Compact Laser-Compton X-ray Source". The applications include nuclear resonance fluorescence, medical imaging and therapy, and nuclear waste imaging and assay. One of the key factors in this system is how we know the interaction happened in the vacuum chamber, which is the spectrometer of electron beams. The other key factor is the interaction after the spectrometer, which is the outgoing X-ray. In this thesis, the work in the simulation for the result of the interaction between electrons and the laser, the calibration of spectrometer, and laser focus characterization are discussed.

  5. Users manual for Aerospace Nuclear Safety Program six-degree-of-freedom reentry simulation (TMAGRA6C)

    SciTech Connect

    Sharbaugh, R.C.

    1990-02-01

    This report documents the updated six-degree-of-freedom reentry simulation TMAGRA6C used in the Aerospace Nuclear Safety Program, ANSP. The simulation provides for the inclusion of the effects of ablation on the aerodynamic stability and drag of reentry bodies, specifically the General Purpose Heat Source, GPHS. The existing six-degree-of-freedom reentry body simulations (TMAGRA6A and TMAGRA6B) used in the JHU/APL Nuclear Safety Program do not include aerodynamic effects resulting from geometric changes to the configuration due to ablation from reentry flights. A wind tunnel test was conducted in 1989 to obtain the effects of ablation on the hypersonic aerodynamics of the GPHS module. The analyzed data were used to form data sets which are included herein in tabular form. These are used as incremental aerodynamic inputs in the new TMAGRA6C six-degree-of-freedom reentry simulation. 20 refs., 13 figs., 2 tabs.

  6. Development of the simulation system {open_quotes}IMPACT{close_quotes} for analysis of nuclear power plant severe accidents

    SciTech Connect

    Naitoh, Masanori; Ujita, Hiroshi; Nagumo, Hiroichi

    1997-07-01

    The Nuclear Power Engineering Corporation (NUPEC) has initiated a long-term program to develop the simulation system {open_quotes}IMPACT{close_quotes} for analysis of hypothetical severe accidents in nuclear power plants. IMPACT employs advanced methods of physical modeling and numerical computation, and can simulate a wide spectrum of senarios ranging from normal operation to hypothetical, beyond-design-basis-accident events. Designed as a large-scale system of interconnected, hierarchical modules, IMPACT`s distinguishing features include mechanistic models based on first principles and high speed simulation on parallel processing computers. The present plan is a ten-year program starting from 1993, consisting of the initial one-year of preparatory work followed by three technical phases: Phase-1 for development of a prototype system; Phase-2 for completion of the simulation system, incorporating new achievements from basic studies; and Phase-3 for refinement through extensive verification and validation against test results and available real plant data.

  7. Self-optimizing Monte Carlo method for nuclear well logging simulation

    NASA Astrophysics Data System (ADS)

    Liu, Lianyan

    1997-09-01

    In order to increase the efficiency of Monte Carlo simulation for nuclear well logging problems, a new method has been developed for variance reduction. With this method, an importance map is generated in the regular Monte Carlo calculation as a by-product, and the importance map is later used to conduct the splitting and Russian roulette for particle population control. By adopting a spatial mesh system, which is independent of physical geometrical configuration, the method allows superior user-friendliness. This new method is incorporated into the general purpose Monte Carlo code MCNP4A through a patch file. Two nuclear well logging problems, a neutron porosity tool and a gamma-ray lithology density tool are used to test the performance of this new method. The calculations are sped up over analog simulation by 120 and 2600 times, for the neutron porosity tool and for the gamma-ray lithology density log, respectively. The new method enjoys better performance by a factor of 4~6 times than that of MCNP's cell-based weight window, as per the converged figure-of-merits. An indirect comparison indicates that the new method also outperforms the AVATAR process for gamma-ray density tool problems. Even though it takes quite some time to generate a reasonable importance map from an analog run, a good initial map can create significant CPU time savings. This makes the method especially suitable for nuclear well logging problems, since one or several reference importance maps are usually available for a given tool. Study shows that the spatial mesh sizes should be chosen according to the mean-free-path. The overhead of the importance map generator is 6% and 14% for neutron and gamma-ray cases. The learning ability towards a correct importance map is also demonstrated. Although false-learning may happen, physical judgement can help diagnose with contributon maps. Calibration and analysis are performed for the neutron tool and the gamma-ray tool. Due to the fact that a very

  8. Analysis of space reactor system components: Investigation through simulation and non-nuclear testing

    NASA Astrophysics Data System (ADS)

    Bragg-Sitton, Shannon M.

    The use of fission energy in space power and propulsion systems offers considerable advantages over chemical propulsion. Fission provides over six orders of magnitude higher energy density, which translates to higher vehicle specific impulse and lower specific mass. These characteristics enable ambitious space exploration missions. The natural space radiation environment provides an external source of protons and high energy, high Z particles that can result in the production of secondary neutrons through interactions in reactor structures. Applying the approximate proton source in geosynchronous orbit during a solar particle event, investigation using MCNPX 2.5.b for proton transport through the SAFE-400 heat pipe cooled reactor indicates an incoming secondary neutron current of (1.16 +/- 0.03) x 107 n/s at the core-reflector interface. This neutron current may affect reactor operation during low power maneuvers (e.g., start-up) and may provide a sufficient reactor start-up source. It is important that a reactor control system be designed to automatically adjust to changes in reactor power levels, maintaining nominal operation without user intervention. A robust, autonomous control system is developed and analyzed for application during reactor start-up, accounting for fluctuations in the radiation environment that result from changes in vehicle location or to temporal variations in the radiation field. Development of a nuclear reactor for space applications requires a significant amount of testing prior to deployment of a flight unit. High confidence in fission system performance can be obtained through relatively inexpensive non-nuclear tests performed in relevant environments, with the heat from nuclear fission simulated using electric resistance heaters. A series of non-nuclear experiments was performed to characterize various aspects of reactor operation. This work includes measurement of reactor core deformation due to material thermal expansion and

  9. Information Theory and Undersampling Diagnostics for Monte Carlo Simulation of Nuclear Criticality

    SciTech Connect

    Ueki, Taro

    2005-11-15

    The criterion of information-theoretic stationarity diagnostics for the Monte Carlo simulation of nuclear criticality has been extended to undersampling diagnostics. Here, undersampling diagnostics means the posterior checking of the number of neutron histories per cycle. A statistically sound criterion using Shannon and relative entropies is defined based on the inequality with a penalty term for the minimum descriptive length of instantaneously decodable encoding. An alternative criterion based on a large sample property of particle population is defined within the information-theoretic framework of the asymptotic equipartition property and the method of types. An auxiliary criterion is proposed using the concave property of Shannon entropy. Numerical results are presented for the 'k-effective of the world' problem by Whitesides. The results indicate that the estimation bias of the neutron effective multiplication factor will be reduced to a practically negligible level if these criteria are satisfied. It can be concluded that equilibrium is a stronger condition than stationarity concerning the source distribution in the Monte Carlo simulation.

  10. Oxidative Alkaline leaching of Americium from simulated high-level nuclear waste sludges

    SciTech Connect

    Reed, Wendy A.; Garnov, Alexander Yu.; Rao, Linfeng; Nash, Kenneth L.; Bond, Andrew H.

    2004-01-23

    Oxidative alkaline leaching has been proposed to pre-treat the high-level nuclear waste sludges to remove some of the problematic (e.g., Cr) and/or non-radioactive (e.g., Na, Al) constituents before vitrification. It is critical to understand the behavior of actinides, americium and plutonium in particular, in oxidative alkaline leaching. We have studied the leaching behavior of americium from four different sludge simulants (BiPO{sub 4}, BiPO{sub 4 modified}, Redox, PUREX) using potassium permanganate and potassium persulfate in alkaline solutions. Up to 60% of americium sorbed onto the simulants is leached from the sludges by alkaline persulfate and permanganate. The percentage of americium leached increases with [NaOH] (between 1.0 and 5.0 M). The initial rate of americium leaching by potassium persulfate increases in the order BiPO{sub 4} sludge < Redox sludge < PUREX sludge. The data are most consistent with oxidation of Am{sup 3+} in the sludge to either AmO{sub 2}{sup +} or AmO{sub 2}{sup 2+} in solution. Though neither of these species is expected to exhibit long-term stability in solution, the potential for mobilization of americium from sludge samples would have to be accommodated in the design of any oxidative leaching process for real sludge samples.

  11. Numerical Simulation of Water Flow through the Bottom End Piece of a Nuclear Fuel Assembly

    NASA Astrophysics Data System (ADS)

    Navarro, Moysés A.; Santos, André A. C. Dos

    An experimental and numerical study was conducted on the pressure loss of flows through the bottom end piece of a nuclear fuel assembly. To determine an optimized numerical methodology using the commercial CFD code, CFX 10.0, a series of preliminary simulations of water flows through perforated plates in a square ducts were performed. A perforated plate is a predominant geometry of the bottom end piece, responsible for the majority of the flow's pressure drop. The numerical pressure loss applying an optimized mesh and the k-ɛ turbulence model showed good agreement when compared with a conventional methodology (Idelchik). Numerical results for the standard bottom end piece were obtained applying the previously determined mesh criteria and the k-ɛ turbulence model with some geometric simplifications. The agreement between the numerical simulations and experimental results can be considered satisfactory but suggests further numerical investigations with the bottom piece under real conditions of the experiment, without the geometric simplifications and with a gap between the piece and the wall of the flow channel. Additionally, other turbulence models should be appraised for this complex geometry.

  12. Geant4 models for simulation of hadron/ion nuclear interactions at moderate and low energies.

    NASA Astrophysics Data System (ADS)

    Ivantchenko, Anton; Ivanchenko, Vladimir; Quesada, Jose-Manuel; Wright, Dennis

    The Geant4 toolkit is intended for Monte Carlo simulation of particle transport in media. It was initially designed for High Energy Physics purposes such as experiments at the Large Hadron Collider (LHC) at CERN. The toolkit offers a set of models allowing effective simulation of cosmic ray interactions with different materials. For moderate and low energy hadron/ion interactions with nuclei there are a number of competitive models: Binary and Bertini intra-nuclear cascade models, quantum molecular dynamic model (QMD), INCL/ABLA cascade model, and Chiral Invariant Phase Space Decay model (CHIPS). We report the status of these models for the recent version of Geant4 (release 9.3, December 2009). The Bertini cascade in-ternal cross sections were upgraded. The native Geant4 precompound and deexcitation models were used in the Binary cascade and QMD. They were significantly improved including emis-sion of light fragments, the Fermi break-up model, the General Evaporation Model (GEM), the multi-fragmentation model, and the fission model. Comparisons between model predictions and data for thin target experiments for neutron, proton, light ions, and isotope production are presented and discussed. The focus of these validations is concentrated on target materials important for space missions.

  13. DESIGN AND LAYOUT CONCEPTS FOR COMPACT, FACTORY-PRODUCED, TRANSPORTABLE, GENERATION IV REACTOR SYSTEMS

    SciTech Connect

    Mynatt Fred R.; Townsend, L.W.; Williamson, Martin; Williams, Wesley; Miller, Laurence W.; Khan, M. Khurram; McConn, Joe; Kadak, Andrew C.; Berte, Marc V.; Sawhney, Rapinder; Fife, Jacob; Sedler, Todd L.; Conway, Larry E.; Felde, Dave K.

    2003-11-12

    The purpose of this research project is to develop compact (100 to 400 MWe) Generation IV nuclear power plant design and layout concepts that maximize the benefits of factory-based fabrication and optimal packaging, transportation and siting. The reactor concepts selected were compact designs under development in the 2000 to 2001 period. This interdisciplinary project was comprised of three university-led nuclear engineering teams identified by reactor coolant type (water, gas, and liquid metal) and a fourth Industrial Engineering team. The reactors included a Modular Pebble Bed helium-cooled concept being developed at MIT, the IRIS water-cooled concept being developed by a team led by Westinghouse Electric Company, and a Lead-Bismuth-cooled concept developed by UT. In addition to the design and layout concepts this report includes a section on heat exchanger manufacturing simulations and a section on construction and cost impacts of proposed modular designs.

  14. Mouse Embryo Compaction.

    PubMed

    White, M D; Bissiere, S; Alvarez, Y D; Plachta, N

    2016-01-01

    Compaction is a critical first morphological event in the preimplantation development of the mammalian embryo. Characterized by the transformation of the embryo from a loose cluster of spherical cells into a tightly packed mass, compaction is a key step in the establishment of the first tissue-like structures of the embryo. Although early investigation of the mechanisms driving compaction implicated changes in cell-cell adhesion, recent work has identified essential roles for cortical tension and a compaction-specific class of filopodia. During the transition from 8 to 16 cells, as the embryo is compacting, it must also make fundamental decisions regarding cell position, polarity, and fate. Understanding how these and other processes are integrated with compaction requires further investigation. Emerging imaging-based techniques that enable quantitative analysis from the level of cell-cell interactions down to the level of individual regulatory molecules will provide a greater understanding of how compaction shapes the early mammalian embryo. PMID:27475854

  15. Application of laboratory data from small-scale simulators to human performance issues in the nuclear industry

    SciTech Connect

    Spettell, C.M.

    1986-01-01

    Laboratory analogs of nuclear power plant tasks were simulated on personal computers in two experimental studies. Human performance data were collected during each experimental study. The goal of the first experiment was to validate a quantitative model of dependence among human errors during testing, calibration, and maintenance activities. This model, the Multiple Sequential Failure (MSF) model (NUREG/CR-2211) has been used to quantify dependent human error failure probabilities for human reliability analyses in Probabilistic Risk Assessments (PRAs). The goal of the second experiment was to examine the relationship among psychological and behavioral characteristics of individuals and their performance at controlling a simulated nuclear power plant. These studies demonstrated the usefulness of the experimental psychology approach for validating models of human performance at nuclear power plant tasks.

  16. Development and investigations of compact heat-transfer equipment for a nuclear power station equipped with a high-temperature gas-cooled reactor

    NASA Astrophysics Data System (ADS)

    Golovko, V. F.; Dmitrieva, I. V.; Kodochigov, N. G.; Bykh, O. A.

    2013-07-01

    The project of a nuclear power station the reactor coolant system of which includes a high-temperature gas-cooled reactor combined with a gas-turbine energy conversion unit supposes the use of high-efficient gas-cycle-based heat-transfer equipment. An analysis aimed at selecting the optimal heat-transfer surfaces is presented together with the results from their calculated and experimental investigation. The design features of recuperators arranged integrally with end and intermediate coolers and placed in a vertical sealed high-pressure vessel of limited sizes are considered.

  17. Study of components and statistical reaction mechanism in simulation of nuclear process for optimized production of {sup 64}Cu and {sup 67}Ga medical radioisotopes using TALYS, EMPIRE and LISE++ nuclear reaction and evaporation codes

    SciTech Connect

    Nasrabadi, M. N. Sepiani, M.

    2015-03-30

    Production of medical radioisotopes is one of the most important tasks in the field of nuclear technology. These radioactive isotopes are mainly produced through variety nuclear process. In this research, excitation functions and nuclear reaction mechanisms are studied for simulation of production of these radioisotopes in the TALYS, EMPIRE and LISE++ reaction codes, then parameters and different models of nuclear level density as one of the most important components in statistical reaction models are adjusted for optimum production of desired radioactive yields.

  18. Reversible DNA compaction.

    PubMed

    González-Pérez, Alfredo

    2014-01-01

    In this review we summarize and discuss the different methods we can use to achieve reversible DNA compaction in vitro. Reversible DNA compaction is a natural process that occurs in living cells and viruses. As a result these process long sequences of DNA can be concentrated in a small volume (compacted) to be decompacted only when the information carried by the DNA is needed. In the current work we review the main artificial compacting agents looking at their suitability for decompaction. The different approaches used for decompaction are strongly influenced by the nature of the compacting agent that determines the mechanism of compaction. We focus our discussion on two main artificial compacting agents: multivalent cations and cationic surfactants that are the best known compacting agents. The reversibility of the process can be achieved by adding chemicals like divalent cations, alcohols, anionic surfactants, cyclodextrins or by changing the chemical nature of the compacting agents via pH modifications, light induced conformation changes or by redox-reactions. We stress the relevance of electrostatic interactions and self-assembly as a main approach in order to tune up the DNA conformation in order to create an on-off switch allowing a transition between coil and compact states. The recent advances to control DNA conformation in vitro, by means of molecular self-assembly, result in a better understanding of the fundamental aspects involved in the DNA behavior in vivo and serve of invaluable inspiration for the development of potential biomedical applications. PMID:24444152

  19. Thermodynamic analysis of compact formation; compaction, unloading, and ejection. I. Design and development of a compaction calorimeter and mechanical and thermal energy determinations of powder compaction.

    PubMed

    DeCrosta, M T; Schwartz, J B; Wigent, R J; Marshall, K

    2000-03-30

    The aim of this investigation was to determine and evaluate the thermodynamic properties, i.e. heat, work, and internal energy change, of the compaction process by developing a 'Compaction Calorimeter'. Compaction of common excipients and acetaminophen was performed by a double-ended, constant-strain tableting waveform utilizing an instrumented 'Compaction Simulator.' A constant-strain waveform provides a specific quantity of applied compaction work. A calorimeter, built around the dies, used a metal oxide thermistor to measure the temperature of the system. A resolution of 0.0001 degrees C with a sampling time of 5 s was used to monitor the temperature. An aluminum die within a plastic insulating die, in conjunction with fiberglass punches, comprised the calorimeter. Mechanical (work) and thermal (heat) calibrations of the elastic punch deformation were performed. An energy correction method was outlined to account for system heat effects and mechanical work of the punches. Compaction simulator transducers measured upper and lower punch forces and displacements. Measurements of the effective heat capacity of the samples were performed utilizing an electrical resistance heater. Specific heat capacities of the samples were determined by differential scanning calorimetry. The calibration techniques were utilized to determine heat, work, and the change in internal energies of powder compaction. Future publications will address the thermodynamic evaluation of the tablet sub-processes of unloading and ejection. PMID:10722955

  20. Specification and verification of nuclear-power-plant training-simulator response characteristics. Part II. Conclusions and recommendations

    SciTech Connect

    Haas, P M; Selby, D L; Kerlin, T W; Felkins, L

    1982-05-01

    The nuclear industry should adopt and NRC regulatory and research actions should support the systems approach to training as a structured framework for development and validation of personnel training systems. Potential exists for improving the ability to assess simulator fidelity. Systems Identification Technology offers a potential framework for model validation. Installation of the data collection/recording equipment required by NUREG-0696 could provide a vastly improved source of data for simulator fidelity assessment. The NRC needs to continue its post-TMI actions to involve itself more rigorously and more formally in the entire process of NPP personnel training system development. However, this involvement should be a participative one with industry. The existing similator standards and guidelines should be reorganized to support the use of systems approach to training. The standards should require and support a holistic approach to training system development that recognizes simulators and simulator training as only parts of the complete training program and full-scope, high-fidelity, site-specific simulators as only one useful training device. Some recommendations for adapting the SAT/ISD process to the nuclear industry are: The formation of an NRC/industry planning/coordination group, a program planning study to develop a programmatic plan, development of a user's guide and NRC/industry workshops to establish common terminology and practice, and a pilot study applying the adopted SAT/ISD methodology to an actual nuclear industry training program.

  1. Compact Neutron Sources for Energy and Security

    NASA Astrophysics Data System (ADS)

    Uesaka, Mitsuru; Kobayashi, Hitoshi

    We choose nuclear data and nuclear material inspection for energy application, and nondestructive testing of explosive and hidden nuclear materials for security application. Low energy (˜100keV) electrostatic accelerators of deuterium are commercially available for nondestructive testing. For nuclear data measurement, electrostatic ion accelerators and L-band (1.428GHz) and S-band (2.856GHz) electron linear accelerators (linacs) are used for the neutron source. Compact or mobile X-band (9.3, 11.424GHz) electron linac neutron sources are under development. A compact proton linac neutron source is used for nondestructive testing, especially water in solids. Several efforts for more neutron intensity using proton and deuteron accelerators are also introduced.

  2. Compact Neutron Sources for Energy and Security

    NASA Astrophysics Data System (ADS)

    Uesaka, Mitsuru; Kobayashi, Hitoshi

    We choose nuclear data and nuclear material inspection for energy application, and nondestructive testing of explosive and hidden nuclear materials for security application. Low energy (~100 keV) electrostatic accelerators of deuterium are commercially available for nondestructive testing. For nuclear data measurement, electrostatic ion accelerators and L-band (1.428GHz) and S-band (2.856GHz) electron linear accelerators (linacs) are used for the neutron source. Compact or mobile X-band (9.3, 11.424GHz) electron linac neutron sources are under development. A compact proton linac neutron source is used for nondestructive testing, especially water in solids. Several efforts for more neutron intensity using proton and deuteron accelerators are also introduced.

  3. Numerical simulations of cloud rise phenomena associated with nuclear bursts: compressible and low Mach approaches

    NASA Astrophysics Data System (ADS)

    Kanarska, Y.; Lomov, I.; Antoun, T.

    2008-12-01

    The nuclear cloud rise is a two stage phenomenon. The initial phase (fireball expansion) of the cloud formation is dominated by compressible flow effects and propagation of shock waves. At the later stage, shock waves become weak, the Mach number decreases and the time steps required by an explicit code to model the acoustic waves make simulation of the late time cloud dynamics with a compressible code very expensive. The buoyant cloud rise at this stage can be efficiently simulated by low Mach-number approximation. In this approach acoustic waves are removed analytically, compressible effects are included as a non-zero divergence constraint due to background stratification and the system of equations is solved implicitly using pressure projection methods. Our numerical approach includes fluid mechanical models that are able to simulate both compressible, incompressible and low Mach regimes. Compressible dynamics is simulated with the explicit high order Eulerian code GEODYN (Lomov et al., 2001). It is based on the second-order Godunov method of Colella and Woodward (1984) that is extended for multiple dimensions using operator-splitting. The code includes the material interface tracking based on a volume-of-fluid (VOF) approach of Miller and Puckett (1996). The code we use for the low Mach approximation (LMC) is based on the incompressible solver of Bell et al., (2003). An unsplit second-order Godunov method and the MAC projection method (Bell et al., 2003) are used. An algebraic slip multiphase model is implemented to describe fallout of dust particles. Both codes incorporate adaptive mesh refinement (AMR). Additionally, the codes are explicitly coupled via input/output files. First, we compared solutions for an idealized buoyant bubble rise problem, that is characterized by low Mach numbers, in GEODYN and LMC codes. While the cloud evolution process is reproduced in both codes, some differences are found in the cloud rise speed and the cloud interface structure

  4. Occurrence and identification of microorganisms in compacted clay-based buffer material designed for use in a nuclear fuel waste disposal vault.

    PubMed

    Stroes-Gascoyne, S; Pedersen, K; Haveman, S A; Dekeyser, K; Arlinger, J; Daumas, S; Ekendahl, S; Hallbeck, L; Hamon, C J; Jahromi, N; Delaney, T L

    1997-12-01

    A full-scale nuclear fuel waste disposal container experiment was carried out 240 m below ground in an underground granitic rock research laboratory in Canada. An electric heater was surrounded by buffer material composed of sand and bentonite clay and provided heat equivalent to what is anticipated in a Canadian nuclear fuel waste repository. During the experiment, the heat caused a mass transport of water and moisture content gradients developed in the buffer ranging from 13% closest to the heater to 23% at the rock wall of the deposition hole. Upon decommissioning after 2.5 years, microorganisms could be cultured from all samples having a moisture content above 15% but not from samples with a moisture content below 15%. Heterotrophic aerobic and anaerobic bacteria were found in numbers ranging from 10(1) to 10(6) cells/g dry weight buffer. Approximately 10(2), or less, sulphate-reducing bacteria and methanogens per gram of dry weight buffer were also found. Identification of buffer population members was performed using Analytical Profile Index (API) strips for isolated bacteria and 16S rRNA gene sequencing for in situ samples. A total of 79 isolates from five buffer layers were identified with API strips as representing the beta, gamma and delta groups of Proteobacteria and Gram-positive bacteria. Sixty-seven 16S rRNA clones that were obtained from three buffer layers were classified into 21 clone groups representing alpha and gamma groups of Proteobacteria, Gram-positive bacteria, and a yeast. Approximately 20% of the population comprised Gram-positive bacteria. Members of the genera Amycolatopsis, Bacillus, and Nocardia predominated. Among Gram-negative bacteria, the genera Acinetobacter and Pseudomonas predominated. Analysis of lipid biomarker signatures and in situ leucine uptake demonstrated that the buffer population was viable. The results suggest that a nuclear fuel waste buffer will be populated by active microorganisms only if the moisture content is

  5. Occurrence and identification of microorganisms in compacted clay-based buffer material designed for use in a nuclear fuel waste disposal vault.

    PubMed

    Stroes-Gascoyne, S; Pedersen, K; Haveman, S A; Dekeyser, K; Arlinger, J; Daumas, S; Ekendahl, S; Hallbeck, L; Hamon, C J; Jahromi, N; Delaney, T L

    1997-12-01

    A full-scale nuclear fuel waste disposal container experiment was carried out 240 m below ground in an underground granitic rock research laboratory in Canada. An electric heater was surrounded by buffer material composed of sand and bentonite clay and provided heat equivalent to what is anticipated in a Canadian nuclear fuel waste repository. During the experiment, the heat caused a mass transport of water and moisture content gradients developed in the buffer ranging from 13% closest to the heater to 23% at the rock wall of the deposition hole. Upon decommissioning after 2.5 years, microorganisms could be cultured from all samples having a moisture content above 15% but not from samples with a moisture content below 15%. Heterotrophic aerobic and anaerobic bacteria were found in numbers ranging from 10(1) to 10(6) cells/g dry weight buffer. Approximately 10(2), or less, sulphate-reducing bacteria and methanogens per gram of dry weight buffer were also found. Identification of buffer population members was performed using Analytical Profile Index (API) strips for isolated bacteria and 16S rRNA gene sequencing for in situ samples. A total of 79 isolates from five buffer layers were identified with API strips as representing the beta, gamma and delta groups of Proteobacteria and Gram-positive bacteria. Sixty-seven 16S rRNA clones that were obtained from three buffer layers were classified into 21 clone groups representing alpha and gamma groups of Proteobacteria, Gram-positive bacteria, and a yeast. Approximately 20% of the population comprised Gram-positive bacteria. Members of the genera Amycolatopsis, Bacillus, and Nocardia predominated. Among Gram-negative bacteria, the genera Acinetobacter and Pseudomonas predominated. Analysis of lipid biomarker signatures and in situ leucine uptake demonstrated that the buffer population was viable. The results suggest that a nuclear fuel waste buffer will be populated by active microorganisms only if the moisture content is

  6. Large-eddy simulation of turbulent winds during the Fukushima Daiichi Nuclear Power Plant accident by coupling with a meso-scale meteorological simulation model

    NASA Astrophysics Data System (ADS)

    Nakayama, H.; Takemi, T.; Nagai, H.

    2015-06-01

    A significant amount of radioactive material was accidentally discharged into the atmosphere from the Fukushima Dai-ichi Nuclear Power Plant from 12 March 2011, which produced high contaminated areas over a wide region in Japan. In conducting regional-scale atmospheric dispersion simulations, the computer-based nuclear emergency response system WSPEEDI-II developed by Japan Atomic Energy Agency was used. Because this system is driven by a meso-scale meteorological (MM) model, it is difficult to reproduce small-scale wind fluctuations due to the effects of local terrain variability and buildings within a nuclear facility that are not explicitly represented in MM models. In this study, we propose a computational approach to couple an LES-based CFD model with a MM model for detailed simulations of turbulent winds with buoyancy effects under real meteorological conditions using turbulent inflow technique. Compared to the simple measurement data, especially, the 10 min averaged wind directions of the LES differ by more than 30 degrees during some period of time. However, distribution patterns of wind speeds, directions, and potential temperature are similar to the MM data. This implies that our coupling technique has potential performance to provide detailed data on contaminated area in the nuclear accidents.

  7. SQUIDs vs. Faraday coils for ultlra-low field nuclear magnetic resonance: experimental and simulation comparison

    SciTech Connect

    Matlashov, Andrei N; Espy, Michelle A; Kraus, Robert H; Sayukov, Igor M; Schultz, Larry J; Urbaitis, Algis V; Volegov, Petr L; Wurden, Caroline J

    2010-01-01

    Nuclear magnetic resonance (NMR) methods are widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging or MRI. Recently it has become possible to perform NMR and MRI in ultra-low field (ULF) regime that requires measurement field strengths only of the order of 1 Gauss. These techniques exploit the advantages offered by superconducting quantum interference devices or SQUIDs. Our group at LANL has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airports security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification and security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers provide enough sensitivity in the 3-10 kHz range and can be used for fast liquid explosives detection based on ULF NMR/MRI technique. We describe an experimental and computer simulation comparison of the world's first multichannel SQUID based and Faraday coils based instruments that are capable of performing ULF MRI for liquids identification.

  8. Ceramic Coatings for Corrosion Resistant Nuclear Waste Container Evaluated in Simulated Ground Water at 90?C

    SciTech Connect

    Haslam, J J; Farmer, J C

    2004-03-31

    Ceramic materials have been considered as corrosion resistant coatings for nuclear waste containers. Their suitability can be derived from the fully oxidized state for selected metal oxides. Several types of ceramic coatings applied to plain carbon steel substrates by thermal spray techniques have been exposed to 90 C simulated ground water for nearly 6 years. In some cases no apparent macroscopic damage such as coating spallation was observed in coatings. Thermal spray processes examined in this work included plasma spray, High Velocity Oxy Fuel (HVOF), and Detonation Gun. Some thermal spray coatings have demonstrated superior corrosion protection for the plain carbon steel substrate. In particular the HVOF and Detonation Gun thermal spray processes produced coatings with low connected porosity, which limited the growth rate of corrosion products. It was also demonstrated that these coatings resisted spallation of the coating even when an intentional flaw (which allowed for corrosion of the carbon steel substrate underneath the ceramic coating) was placed in the coating. A model for prediction of the corrosion protection provided by ceramic coatings is presented. The model includes the effect of the morphology and amount of the porosity within the thermal spray coating and provides a prediction of the exposure time needed to produce a crack in the ceramic coating.

  9. Evaluation of effective-stress-function algorithm for nuclear fuel simulation

    SciTech Connect

    Kim, H. C.; Yang, Y. S.; Koo, Y. H.

    2013-07-01

    In a pressurized water reactor (PWR), the mechanical integrity of nuclear fuel is the most critical issue as it is an important barrier for fission products released into the environment. The integrity of zirconium cladding that surrounds uranium oxide can be threatened during off-normal operation owing to a pellet-cladding mechanical interaction (PCMI). To analyze the fuel and cladding behavior during off-operation, the fuel performance code should calculate an inelastic analysis in two - or three-dimensional calculations. In this paper, the effective stress function (ESF) algorithm based on a two-dimensional FE module has been implemented to simulate the inelastic behavior of the cladding with stability and accuracy. The ESF algorithm solves the governing equations of the inelastic constitutive behavior by calculating the zero of the appropriate effective-stress-function. To verify the accuracy of the ESF algorithm for an inelastic analysis, a code-to-code benchmark was performed using the commercial FE code, ANSYS 13.0. To demonstrate the stability and convergence of the implemented algorithm, the number of iterations in the ESF algorithm was compared with that in a sequential algorithm in the case of an inelastic problem. Consequently, the evaluation results demonstrate that the implemented ESF algorithm improves the efficiency of the computation without a loss of accuracy for an inelastic analysis. (authors)

  10. SQUIDs vs. Induction Coils for Ultra-Low Field Nuclear Magnetic Resonance: Experimental and Simulation Comparison.

    PubMed

    Matlashov, Andrei N; Schultz, Larry J; Espy, Michelle A; Kraus, Robert H; Savukov, Igor M; Volegov, Petr L; Wurden, Caroline J

    2011-01-01

    Nuclear magnetic resonance (NMR) is widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging (MRI). Recently it has become possible to perform NMR and MRI in the ultra-low field (ULF) regime requiring measurement field strengths of the order of only 1 Gauss. This technique exploits the advantages offered by superconducting quantum interference devices or SQUIDs. Our group has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airport security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification and security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers may provide enough sensitivity in the 3-10 kHz range and can be used for fast liquid explosives detection based on ULF NMR technique. We describe experimental and computer-simulation results comparing multichannel SQUID based and induction coils based instruments that are capable of performing ULF MRI for liquid identification. PMID:21747638

  11. Geothermal reservoir simulation to enhance confidence in predictions for nuclear waste disposal

    SciTech Connect

    Kneafsey, Timothy J.; Pruess, Karsten; O'Sullivan, Michael J.; Bodvarsson, Gudmundur S.

    2002-06-15

    Numerical simulation of geothermal reservoirs is useful and necessary in understanding and evaluating reservoir structure and behavior, designing field development, and predicting performance. Models vary in complexity depending on processes considered, heterogeneity, data availability, and study objectives. They are evaluated using computer codes written and tested to study single and multiphase flow and transport under nonisothermal conditions. Many flow and heat transfer processes modeled in geothermal reservoirs are expected to occur in anthropogenic thermal (AT) systems created by geologic disposal of heat-generating nuclear waste. We examine and compare geothermal systems and the AT system expected at Yucca Mountain, Nevada, and their modeling. Time frames and spatial scales are similar in both systems, but increased precision is necessary for modeling the AT system, because flow through specific repository locations will affect long-term ability radionuclide retention. Geothermal modeling experience has generated a methodology, used in the AT modeling for Yucca Mountain, yielding good predictive results if sufficient reliable data are available and an experienced modeler is involved. Codes used in geothermal and AT modeling have been tested extensively and successfully on a variety of analytical and laboratory problems.

  12. FTIR spectra and properties of iron borophosphate glasses containing simulated nuclear wastes

    NASA Astrophysics Data System (ADS)

    Liao, Qilong; Wang, Fu; Chen, Kuiru; Pan, Sheqi; Zhu, Hanzhen; Lu, Mingwei; Qin, Jianfa

    2015-07-01

    30 wt.% simulated nuclear wastes were successfully immobilized by B2O3-doped iron phosphate base glasses. The structure and thermal stability of the prepared wasteforms were characterized by Fourier transform infrared spectroscopy and differential thermal analysis, respectively. The subtle structural variations attributed to different B2O3 doping modes have been discussed in detail. The results show that the thermal stability and glass forming tendency of the iron borophosphate glass wasteforms are faintly affected by different B2O3 doping modes. The main structural networks of iron borophosphate glass wasteforms are PO43-, P2O74-, [BO4] groups. Furthermore, for the wasteform prepared by using 10B2O3-36Fe2O3-54P2O5 as base glass, the distributions of Fe-O-P bonds, [BO4], PO43- and P2O74- groups are optimal. In general, the dissolution rate (DR) values of the studied iron borophosphate wasteforms are about 10-8 g cm-2 min-1. The obtained conclusions can offer some useful information for the disposal of high-level radioactive wastes using boron contained phosphate glasses.

  13. Mechanics of tissue compaction.

    PubMed

    Turlier, Hervé; Maître, Jean-Léon

    2015-12-01

    During embryonic development, tissues deform by a succession and combination of morphogenetic processes. Tissue compaction is the morphogenetic process by which a tissue adopts a tighter structure. Recent studies characterized the respective roles of cells' adhesive and contractile properties in tissue compaction. In this review, we formalize the mechanical and molecular principles of tissue compaction and we analyze through the prism of this framework several morphogenetic events: the compaction of the early mouse embryo, the formation of the fly retina, the segmentation of somites and the separation of germ layers during gastrulation.

  14. Verification of the Prediction Accuracy of Annual Energy Output at Noma Wind Park by the Non-Stationary and Non-Linear Wind Synopsis Simulator, RIAM-COMPACT

    NASA Astrophysics Data System (ADS)

    Uchida, Takanori; Ohya, Yuji

    In the present study, the hub-height wind speed ratios for 16 individual wind directional groups were estimated by the RIAM-COMPACT for Noma Wind Park, Kagoshima Prefecture. The validity of the proposed estimation technique for the actual wind was examined. For this procedure, field observational data from the one year period between April, 2004 and March, 2005 were studied. In this case, the relative error on the prediction accuracy was less than 10% and less than 5% for the monthly and annual average wind speeds, respectively. Similar to the results for the annual average wind speed, the difference in the selected reference points (Wind Turbines #4 and #6) had little difference in the relative error on the prediction accuracy of the annual energy output. For both reference points, the relative error was within 10%.

  15. Simulation of irradiation hardening of Zircaloy within plate-type dispersion nuclear fuel elements

    NASA Astrophysics Data System (ADS)

    Jiang, Yijie; Wang, Qiming; Cui, Yi; Huo, Yongzhong; Ding, Shurong

    2011-06-01

    Within plate-type dispersion nuclear fuel elements, the metal matrix and cladding attacked continuously by fast neutrons undergo irradiation hardening, which might have remarkable effects upon the mechanical behaviors within fuel elements. In this paper, with the irradiation hardening effect of metal materials mainly considered together with irradiation growth effect of the cladding, the three-dimensional large-deformation constitutive relations for the metal matrix and cladding are developed. The method of virtual temperature increase in the previous studies is further developed to model the irradiation swelling of fuel particles; the method of anisotropic thermal expansion is introduced to model irradiation growth of the cladding; and a method of multi-step-temperature loading is proposed to simulate the coupling features of irradiation-induced swelling of the fuel particles together with irradiation growth of the cladding. Above all, based on the developed relationship between irradiation growth at certain burnup and the loaded virtual temperatures, with considering that certain burnup corresponds to certain fast neutron fluence, the time-dependent constitutive relation due to irradiation hardening effect is replaced by the virtual-temperature-dependent one which is introduced into the commercial software to simulate the irradiation hardening effects of the matrix and cladding. Numerical simulations of the irradiation-induced mechanical behaviors are implemented with the finite element method in consideration of the micro-structure of the fuel meat. The obtained results indicate that when the irradiation hardening effects are introduced into the constitutive relations of the metal matrix and cladding: (1) higher maximum Mises stresses for certain burnup at the matrix exist with the equivalent plastic strains remaining almost the same at lower burnups; (2) the maximum Mises stresses for certain burnup at the cladding are enhanced while the maximum equivalent

  16. Numerical Simulation of the Seismic Response for the Recent North Korean Nuclear Tests (Invited)

    NASA Astrophysics Data System (ADS)

    Rodgers, A. J.; Vorobiev, O.; Petersson, A.; Sjogreen, B.; Matzel, E.

    2009-12-01

    We performed a series of numerical simulations of the 2006 and 2009 North Korean nuclear tests to model the observed seismic data and gain insight into the wave propagation phenomena that may impact source estimates of these events, such as the waveform shapes and amplitudes of direct P-waves, the generation of S-waves, high-frequency P/S ratios. Simulations span the hydrodynamic (near-field, non-linear), local and regional distance ranges, although seismic data are only available for regional and teleseismic distances. Firstly, we modeled the response of the immediate near-field assuming emplacement in granite for small explosions (yields 0.5-3 kiloton) with GEODYN, an Eulerian finite-volume hydrodynamics code. This is a rather hard material that results in an impulsive short duration source time function and small cavity. Secondly, we modeled the elastic response of simple earth models including free surface topography with WPP (an anelastic finite difference code) for a domain ~20 km around the sources. Topographic relief is significant at the test site, with elevations rising from 300 m to 2000 m over short distances. We found that the inclusion of topography has a strong impact on the wavefield, causing azimuthal dependence of both the P-wave scattering and S-wave generation. Furthermore, the scattering by the rough free-surface causes decorrelation of the emerging P-waves for the 2006 and 2009 events, spaced only ~4 km apart. Thirdly, we simulated seismic wave propagation to regional distances (< 2000 km) using three-dimensional (3D) wavespeed models and SPECFEM3D, a spectral element code, and compared results with the available long-period waveforms. We used the source models of Dreger et al. (manuscript submitted) and find that the synthetics for 3D models and an isotropic source predict some features of the observed waveforms. The one-dimensional (1D) iasp91 (Kennett and Engdahl, 1991) model performs surprisingly well for the vertical and radial component

  17. Rapid compaction during RNA folding

    NASA Astrophysics Data System (ADS)

    Russell, Rick; Millett, Ian S.; Tate, Mark W.; Kwok, Lisa W.; Nakatani, Bradley; Gruner, Sol M.; Mochrie, Simon G. J.; Pande, Vijay; Doniach, Sebastian; Herschlag, Daniel; Pollack, Lois

    2002-04-01

    We have used small angle x-ray scattering and computer simulations with a coarse-grained model to provide a time-resolved picture of the global folding process of the Tetrahymena group I RNA over a time window of more than five orders of magnitude. A substantial phase of compaction is observed on the low millisecond timescale, and the overall compaction and global shape changes are largely complete within one second, earlier than any known tertiary contacts are formed. This finding indicates that the RNA forms a nonspecifically collapsed intermediate and then searches for its tertiary contacts within a highly restricted subset of conformational space. The collapsed intermediate early in folding of this RNA is grossly akin to molten globule intermediates in protein folding.

  18. Compact torus studies: Final report

    SciTech Connect

    Morse, E.C.

    1987-06-01

    The compact torus (CT) device has been proposed for use in some applications which are of interest in Laboratory programs in the areas of pulsed power and inertial confinement fusion. These applications involve compression and acceleration of CT plasmas. The RACE (Ring Accelerator Experiment) experimental program at Livermore has been initiated to study these applications. The work reported here involves studies of plasma physics and other aspects of these compact torus applications. The studies conducted identify specific problem areas associated with the CT device and examine these areas in some detail. This report contains studies of three particular problem areas of the CT applications. These three areas are: the general nonlinear properties of the CT as a magnetohydrodynamic (MHD) equilibrium, particle simulation of the compression of the CT, with a focus on the non-MHD effects, and nonlinear RF interaction problems in the CT.

  19. Degradation and failure susceptibility of carbon steels in simulated Yucca Mountain nuclear repository environments

    NASA Astrophysics Data System (ADS)

    Yilmaz, Ahmet

    Environmental degradation and cracking of medium carbon steel (MCS) rock bolts and low carbon steel (LCS) I-beam have been investigated by experimental methods such as linear polarization, impedance spectroscopy, weight loss measurements, and electro-mechanical dynamic slow strain rate tensile (SSRT) tests, along with potentiostatic in-situ potential-current monitoring techniques. The experiments were conducted in concentrated aqueous environments of various temperatures, which simulated the conditions at the Yucca Mountain (YM) nuclear waste repository site, where the candidate structural materials introduced above, will be used for supporting the waste repository tunnels. MCS corroded at medium general rates approximately around 40 mum/year to 200 mum/year in de-aerated simulated YM waters of various temperatures and concentrations. Increased temperatures increased the corrosion rates in the all de-aerated waters. Increased concentrations of overall species in the simulated waters also increased the corrosion rates, but only slightly. Impedance spectroscopy revealed similar trends for temperature and concentration effects on the rates in both aerated and deaerated environments. Aeration increased corrosion rates significantly in dilute (1X) and ten times concentrated (10X) waters at all temperatures. However, inhibitive precipitates on the specimens formed by oxygen-environment reactions at higher temperatures (up to 85°C) in hundred times concentrated (100X) waters decreased corrosion rates drastically, resulting some localized corrosion and pitting. The average rates were determined to be between approximately 100 mu/year and 1000 mu/year in the entire concentration and temperature range tested. Electrochemical results showed slightly higher rates compared to the other tests because of their much shorter testing period, therefore in general they should be taken as conservative upper bounds. SSRT on LCS under various imposed metal-electrolyte interface

  20. Ground-water flow near two radioactive-waste-disposal areas at the Western New York Nuclear Service Center, Cattaraugus County, New York; results of flow simulation

    USGS Publications Warehouse

    Bergeron, M.P.; Bugliosi, E.F.

    1988-01-01

    Two adjacent burial areas were excavated in a clay-rich till at a radioactive waste disposal site near West Valley in Cattaraugus County, N.Y.: (1) which contains mainly low-level radioactive wastes generated onsite by a nuclear fuel reprocessing plant, has been in operation since 1966; and (2) which contains commercial low-level radioactive wastes, was operated during 1963-75. Groundwater below the upper 3 meters of till generally moves downward through a 20- to 30-meter thick sequence of tills underlain by lacustrine and kame-delta deposits of fine sand and silt. Groundwater in the weathered, upper 3 meters of till can move laterally for several meters before either moving downward into the kame-delta deposits or discharging to the land surface. A two-dimensional finite-element model that simulates two vertical sections was used to evaluate hydrologic factors that control groundwater flow in the till. Conditions observed during March 1983 were reproduced accurately in steady-state simulations that used four isotropic units of differing hydraulic conductivity to represent two fractured and weathered till units near land surfaces, an intermediate group of isolated till zones that contain significant amounts of fine sand and silt, and a sequence of till units at depths that have been consolidated by overburden pressure. Recharge rates used in the best-fit simulation ranged from 1.4 cm/yr along smooth, sloping or compacted surfaces to 3.8 cm/yr near swampy areas. Values of hydraulic conductivity and infiltration used in the calibrated best-fit model were nearly identical to values used in a previous model analysis of the nearby commercial-waste burial area. Results of the model simulations of a burial pit assumed to be filled with water indicate that water near the bottom of the burial pit would migrate laterally in the shallow, weathered till for 5 to 6 meters before moving downward into the unweathered till, and water near the top of the pit would move laterally

  1. MC 93 - Proceedings of the International Conference on Monte Carlo Simulation in High Energy and Nuclear Physics

    NASA Astrophysics Data System (ADS)

    Dragovitsch, Peter; Linn, Stephan L.; Burbank, Mimi

    1994-01-01

    The Table of Contents for the book is as follows: * Preface * Heavy Fragment Production for Hadronic Cascade Codes * Monte Carlo Simulations of Space Radiation Environments * Merging Parton Showers with Higher Order QCD Monte Carlos * An Order-αs Two-Photon Background Study for the Intermediate Mass Higgs Boson * GEANT Simulation of Hall C Detector at CEBAF * Monte Carlo Simulations in Radioecology: Chernobyl Experience * UNIMOD2: Monte Carlo Code for Simulation of High Energy Physics Experiments; Some Special Features * Geometrical Efficiency Analysis for the Gamma-Neutron and Gamma-Proton Reactions * GISMO: An Object-Oriented Approach to Particle Transport and Detector Modeling * Role of MPP Granularity in Optimizing Monte Carlo Programming * Status and Future Trends of the GEANT System * The Binary Sectioning Geometry for Monte Carlo Detector Simulation * A Combined HETC-FLUKA Intranuclear Cascade Event Generator * The HARP Nucleon Polarimeter * Simulation and Data Analysis Software for CLAS * TRAP -- An Optical Ray Tracing Program * Solutions of Inverse and Optimization Problems in High Energy and Nuclear Physics Using Inverse Monte Carlo * FLUKA: Hadronic Benchmarks and Applications * Electron-Photon Transport: Always so Good as We Think? Experience with FLUKA * Simulation of Nuclear Effects in High Energy Hadron-Nucleus Collisions * Monte Carlo Simulations of Medium Energy Detectors at COSY Jülich * Complex-Valued Monte Carlo Method and Path Integrals in the Quantum Theory of Localization in Disordered Systems of Scatterers * Radiation Levels at the SSCL Experimental Halls as Obtained Using the CLOR89 Code System * Overview of Matrix Element Methods in Event Generation * Fast Electromagnetic Showers * GEANT Simulation of the RMC Detector at TRIUMF and Neutrino Beams for KAON * Event Display for the CLAS Detector * Monte Carlo Simulation of High Energy Electrons in Toroidal Geometry * GEANT 3.14 vs. EGS4: A Comparison Using the DØ Uranium/Liquid Argon

  2. Simulated alteration tests on non-radioactive SON 68 nuclear glass in the presence of corrosion products and environmental materials

    NASA Astrophysics Data System (ADS)

    Jollivet, Patrick; Minet, Yves; Nicolas, Michèle; Vernaz, Étienne

    2000-10-01

    Alteration tests with non-radioactive French SON 68 (R7T7-type) nuclear glass in the presence of simulated metal canister corrosion products (CP) or environmental materials (EM) were simulated using the LIXIVER2 computer code. The code incorporates hypotheses concerning glass alteration in aqueous media based on the first-order kinetic law for total silicon with variable silicon retention in the gel and silicon diffusion in the gel interstitial water, coupled with silicon adsorption and diffusion in the materials in contact with the glass. The canister CP are considered as a localized medium with a mass adsorption capacity Rad, while the EM are considered as a porous medium with a diffusion coefficient Dp and a distribution coefficient Kd. L IXIVER2 simulates these media in one-dimensional Cartesian geometry. The Kd values determined by simulating alteration tests logically increase with the aggressiveness of the materials with respect to the glass.

  3. Numerical simulation of free evolution in solid-state nuclear magnetic resonance using low-order correlations in Liouville space

    NASA Astrophysics Data System (ADS)

    Dumez, Jean-Nicolas; Butler, Mark C.; Emsley, Lyndon

    2010-12-01

    The design of simulations of free evolution in dipolar-coupled nuclear-spin systems using low-order correlations in Liouville space (LCL) is discussed, and a computational scheme relying on the Suzuki-Trotter algorithm and involving minimal memory requirements is described. The unusual nature of the approximation introduced by Liouville-space reduction in a spinning solid is highlighted by considering the accuracy of LCL simulations at different spinning frequencies, the quasiequilibria achieved by spin systems in LCL simulations, and the growth of high-order coherences in the exact dynamics. In particular, it is shown that accurate LCL simulations of proton spin diffusion occur in a regime where the reduced space excludes the coherences that make the dominant contribution to Vert σ Vert ^2, the norm-squared of the density matrix.

  4. Surface studies on aluminized and thermally oxidized superalloy 690 substrates interacted with simulated nuclear waste and sodium borosilicate melt

    SciTech Connect

    Yusufali, C. Sengupta, P.; Dutta, R. S.; Dey, G. K.; Kshirsagar, R. J.; Mishra, R. K.; Kaushik, C. P.

    2014-04-24

    Aluminized and thermally oxidized Ni-Cr-Fe based superalloy 690 substrates with Al{sub 2}O{sub 3} layer on top have been exposed in nitrate based environment (simulated high level nuclear liquid waste) at 373 K for 216 hours and sodium borosilicate melt at 1248 K for 192 hours. The surfaces of exposed samples have been characterized by using Electron probe micro-analyzer (EPMA). Elemental X-ray mapping on coated specimen that exposed in simulated nuclear waste solution revealed that the surface is enriched with Ni, Cr and Al. X-ray mapping on surface of the specimen that interacted with sodium borosilicate melt indicated that the surface is composed of Al, Fe, Ni and Cr.

  5. Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach

    SciTech Connect

    Hyeon-Deuk, Kim; Ando, Koji

    2014-05-07

    Liquid para-hydrogen (p-H{sub 2}) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H{sub 2}. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H{sub 2} liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.

  6. Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach.

    PubMed

    Hyeon-Deuk, Kim; Ando, Koji

    2014-05-01

    Liquid para-hydrogen (p-H2) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H2. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H2 liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.

  7. Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach

    NASA Astrophysics Data System (ADS)

    Hyeon-Deuk, Kim; Ando, Koji

    2014-05-01

    Liquid para-hydrogen (p-H2) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H2. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H2 liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.

  8. Surface studies on aluminized and thermally oxidized superalloy 690 substrates interacted with simulated nuclear waste and sodium borosilicate melt

    NASA Astrophysics Data System (ADS)

    Yusufali, C.; Kshirsagar, R. J.; Mishra, R. K.; Kaushik, C. P.; Sengupta, P.; Dutta, R. S.; Dey, G. K.

    2014-04-01

    Aluminized and thermally oxidized Ni-Cr-Fe based superalloy 690 substrates with Al2O3 layer on top have been exposed in nitrate based environment (simulated high level nuclear liquid waste) at 373 K for 216 hours and sodium borosilicate melt at 1248 K for 192 hours. The surfaces of exposed samples have been characterized by using Electron probe micro-analyzer (EPMA). Elemental X-ray mapping on coated specimen that exposed in simulated nuclear waste solution revealed that the surface is enriched with Ni, Cr and Al. X-ray mapping on surface of the specimen that interacted with sodium borosilicate melt indicated that the surface is composed of Al, Fe, Ni and Cr.

  9. Stabilization of compactible waste

    SciTech Connect

    Franz, E.M.; Heiser, J.H. III; Colombo, P.

    1990-09-01

    This report summarizes the results of series of experiments performed to determine the feasibility of stabilizing compacted or compactible waste with polymers. The need for this work arose from problems encountered at disposal sites attributed to the instability of this waste in disposal. These studies are part of an experimental program conducted at Brookhaven National Laboratory (BNL) investigating methods for the improved solidification/stabilization of DOE low-level wastes. The approach taken in this study was to perform a series of survey type experiments using various polymerization systems to find the most economical and practical method for further in-depth studies. Compactible dry bulk waste was stabilized with two different monomer systems: styrene-trimethylolpropane trimethacrylate (TMPTMA) and polyester-styrene, in laboratory-scale experiments. Stabilization was accomplished by wetting or soaking compactible waste (before or after compaction) with monomers, which were subsequently polymerized. Three stabilization methods are described. One involves the in-situ treatment of compacted waste with monomers in which a vacuum technique is used to introduce the binder into the waste. The second method involves the alternate placement and compaction of waste and binder into a disposal container. In the third method, the waste is treated before compaction by wetting the waste with the binder using a spraying technique. A series of samples stabilized at various binder-to-waste ratios were evaluated through water immersion and compression testing. Full-scale studies were conducted by stabilizing two 55-gallon drums of real compacted waste. The results of this preliminary study indicate that the integrity of compacted waste forms can be readily improved to ensure their long-term durability in disposal environments. 9 refs., 10 figs., 2 tabs.

  10. HIGH-TEMPERATURE ELECTROLYSIS FOR LARGE-SCALE HYDROGEN AND SYNGAS PRODUCTION FROM NUCLEAR ENERGY – SYSTEM SIMULATION AND ECONOMICS

    SciTech Connect

    J. E. O'Brien; M. G. McKellar; E. A. Harvego; C. M. Stoots

    2009-05-01

    A research and development program is under way at the Idaho National Laboratory (INL) to assess the technological and scale-up issues associated with the implementation of solid-oxide electrolysis cell technology for efficient high-temperature hydrogen production from steam. This work is supported by the US Department of Energy, Office of Nuclear Energy, under the Nuclear Hydrogen Initiative. This paper will provide an overview of large-scale system modeling results and economic analyses that have been completed to date. System analysis results have been obtained using the commercial code UniSim, augmented with a custom high-temperature electrolyzer module. Economic analysis results were based on the DOE H2A analysis methodology. The process flow diagrams for the system simulations include an advanced nuclear reactor as a source of high-temperature process heat, a power cycle and a coupled steam electrolysis loop. Several reactor types and power cycles have been considered, over a range of reactor outlet temperatures. Pure steam electrolysis for hydrogen production as well as coelectrolysis for syngas production from steam/carbon dioxide mixtures have both been considered. In addition, the feasibility of coupling the high-temperature electrolysis process to biomass and coal-based synthetic fuels production has been considered. These simulations demonstrate that the addition of supplementary nuclear hydrogen to synthetic fuels production from any carbon source minimizes emissions of carbon dioxide during the production process.

  11. MCNPX simulations of the silicon carbide semiconductor detector response to fast neutrons from D-T nuclear reaction

    NASA Astrophysics Data System (ADS)

    Sedlačková, Katarína; Šagátová, Andrea; Zat'ko, Bohumír; Nečas, Vladimír; Solar, Michael; Granja, Carlos

    2016-09-01

    Silicon Carbide (SiC) has been long recognized as a suitable semiconductor material for use in nuclear radiation detectors of high-energy charged particles, gamma rays, X-rays and neutrons. The nuclear interactions occurring in the semiconductor are complex and can be quantified using a Monte Carlo-based computer code. In this work, the MCNPX (Monte Carlo N-Particle eXtended) code was employed to support detector design and analysis. MCNPX is widely used to simulate interaction of radiation with matter and supports the transport of 34 particle types including heavy ions in broad energy ranges. The code also supports complex 3D geometries and both nuclear data tables and physics models. In our model, monoenergetic neutrons from D-T nuclear reaction were assumed as a source of fast neutrons. Their energy varied between 16 and 18.2 MeV, according to the accelerating voltage of the deuterons participating in D-T reaction. First, the simulations were used to calculate the optimum thickness of the reactive film composed of High Density PolyEthylene (HDPE), which converts neutral particles to charged particles and thusly enhancing detection efficiency. The dependency of the optimal thickness of the HDPE layer on the energy of the incident neutrons has been shown for the inspected energy range. Further, from the energy deposited by secondary charged particles and recoiled ions, the detector response was modeled and the effect of the conversion layer on detector response was demonstrated. The results from the simulations were compared with experimental data obtained for a detector covered by a 600 and 1300 μm thick conversion layer. Some limitations of the simulations using MCNPX code are also discussed.

  12. Thermally Simulated Testing of a Direct-Drive Gas-Cooled Nuclear Reactor

    NASA Technical Reports Server (NTRS)

    Godfroy, Thomas; Bragg-Sitton, Shannon; VanDyke, Melissa

    2003-01-01

    This paper describes the concept and preliminary component testing of a gas-cooled, UN-fueled, pin-type reactor which uses He/Xe gas that goes directly into a recuperated Brayton system to produce electricity for nuclear electric propulsion. This Direct-Drive Gas-Cooled Reactor (DDG) is designed to be subcritical under water or wet-sand immersion in case of a launch accident. Because the gas-cooled reactor can directly drive the Brayton turbomachinery, it is possible to configure the system such that there are no external surfaces or pressure boundaries that are refractory metal, even though the gas delivered to the turbine is 1144 K. The He/Xe gas mixture is a good heat transport medium when flowing, and a good insulator when stagnant. Judicious use of stagnant cavities as insulating regions allows transport of the 1144-K gas while keeping all external surfaces below 900 K. At this temperature super-alloys (Hastelloy or Inconel) can be used instead of refractory metals. Super-alloys reduce the technology risk because they are easier to fabricate than refractory metals, we have a much more extensive knowledge base on their characteristics, and, because they have a greater resistance to oxidation, system testing is eased. The system is also relatively simple in its design: no additional coolant pumps, heat exchanger, or freeze-thaw systems are required. Key to success of this concept is a good knowledge of the heat transfer between the fuel pins and the gas, as well as the pressure drop through the system. This paper describes preliminary testing to obtain this key information, as well as experience in demonstrating electrical thermal simulation of reactor components and concepts.

  13. Dynamic Compaction Modeling of Porous Silica Powder

    NASA Astrophysics Data System (ADS)

    Borg, John P.; Schwalbe, Larry; Cogar, John; Chapman, D. J.; Tsembelis, K.; Ward, Aaron; Lloyd, Andrew

    2006-07-01

    A computational analysis of the dynamic compaction of porous silica is presented and compared with experimental measurements. The experiments were conducted at Cambridge University's one-dimensional flyer plate facility. The experiments shock loaded samples of silica dust of various initial porous densities up to a pressure of 2.25 GPa. The computational simulations utilized a linear Us-Up Hugoniot. The compaction events were modeled with CTH, a 3D Eulerian hydrocode developed at Sandia National Laboratory. Simulated pressures at two test locations are presented and compared with measurements.

  14. Geoelectrical monitoring of simulated subsurface leakage to support high-hazard nuclear decommissioning at the Sellafield Site, UK.

    PubMed

    Kuras, Oliver; Wilkinson, Paul B; Meldrum, Philip I; Oxby, Lucy S; Uhlemann, Sebastian; Chambers, Jonathan E; Binley, Andrew; Graham, James; Smith, Nicholas T; Atherton, Nick

    2016-10-01

    A full-scale field experiment applying 4D (3D time-lapse) cross-borehole Electrical Resistivity Tomography (ERT) to the monitoring of simulated subsurface leakage was undertaken at a legacy nuclear waste silo at the Sellafield Site, UK. The experiment constituted the first application of geoelectrical monitoring in support of decommissioning work at a UK nuclear licensed site. Images of resistivity changes occurring since a baseline date prior to the simulated leaks revealed likely preferential pathways of silo liquor simulant flow in the vadose zone and upper groundwater system. Geophysical evidence was found to be compatible with historic contamination detected in permeable facies in sediment cores retrieved from the ERT boreholes. Results indicate that laterally discontinuous till units forming localized hydraulic barriers substantially affect flow patterns and contaminant transport in the shallow subsurface at Sellafield. We conclude that only geophysical imaging of the kind presented here has the potential to provide the detailed spatial and temporal information at the (sub-)meter scale needed to reduce the uncertainty in models of subsurface processes at nuclear sites.

  15. Geoelectrical monitoring of simulated subsurface leakage to support high-hazard nuclear decommissioning at the Sellafield Site, UK.

    PubMed

    Kuras, Oliver; Wilkinson, Paul B; Meldrum, Philip I; Oxby, Lucy S; Uhlemann, Sebastian; Chambers, Jonathan E; Binley, Andrew; Graham, James; Smith, Nicholas T; Atherton, Nick

    2016-10-01

    A full-scale field experiment applying 4D (3D time-lapse) cross-borehole Electrical Resistivity Tomography (ERT) to the monitoring of simulated subsurface leakage was undertaken at a legacy nuclear waste silo at the Sellafield Site, UK. The experiment constituted the first application of geoelectrical monitoring in support of decommissioning work at a UK nuclear licensed site. Images of resistivity changes occurring since a baseline date prior to the simulated leaks revealed likely preferential pathways of silo liquor simulant flow in the vadose zone and upper groundwater system. Geophysical evidence was found to be compatible with historic contamination detected in permeable facies in sediment cores retrieved from the ERT boreholes. Results indicate that laterally discontinuous till units forming localized hydraulic barriers substantially affect flow patterns and contaminant transport in the shallow subsurface at Sellafield. We conclude that only geophysical imaging of the kind presented here has the potential to provide the detailed spatial and temporal information at the (sub-)meter scale needed to reduce the uncertainty in models of subsurface processes at nuclear sites. PMID:27228305

  16. Numerical analysis of applied magnetic field dependence in Malmberg-Penning Trap for compact simulator of energy driver in heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Sato, T.; Park, Y.; Soga, Y.; Takahashi, K.; Sasaki, T.; Kikuchi, T.; Harada, Nob

    2016-05-01

    To simulate a pulse compression process of space charge dominated beams in heavy ion fusion, we have demonstrated a multi-particle numerical simulation as an equivalent beam using the Malmberg-Penning trap device. The results show that both transverse and longitudinal velocities as a function of external magnetic field strength are increasing during the longitudinal compression. The influence of space-charge effect, which is related to the external magnetic field, was observed as the increase of high velocity particles at the weak external magnetic field.

  17. Compaction Waves in Granular HMX

    SciTech Connect

    E. Kober; R. Menikoff

    1999-01-01

    Piston driven compaction waves in granular HMX are simulated with a two-dimensional continuum mechanics code in which individual grains are resolved. The constitutive properties of the grains are modeled with a hydrostatic pressure and a simple elastic-plastic model for the shear stress. Parameters are chosen to correspond to inert HMX. For a tightly packed random grain distribution (with initial porosity of 19%) we varied the piston velocity to obtain weak partly compacted waves and stronger fully compacted waves. The average stress and wave speed are compatible with the porous Hugoniot locus for uni- axial strain. However, the heterogeneities give rise to stress concentrations, which lead to localized plastic flow. For weak waves, plastic deformation is the dominant dissipative mechanism and leads to dispersed waves that spread out in time. In addition to dispersion, the granular heterogeneities give rise to subgrain spatial variation in the thermodynamic variables. The peaks in the temperature fluctuations, known as hot spots, are in the range such that they are the critical factor for initiation sensitivity.

  18. Compaction of North-sea chalk

    NASA Astrophysics Data System (ADS)

    Keszthelyi, Dániel; Dysthe, Dag Kristian; Jamtveit, Bjørn

    2014-05-01

    The Ekofisk field is the largest petroleum field in the Norwegian North Sea territory where oil is produced from chalk formations. Early stage of oil production caused considerable changes in pore fluid pressure which led to a reservoir compaction. Pore collapse mechanism caused by the dramatic increase of effective stress, which in turn was caused by the pressure reduction by hydrocarbon depletion, was early identified as a principal reason for the reservoir compaction (Sulak et al. 1991). There have been several attempts to model this compaction. They performed with variable success on predicting the Ekofisk subsidence. However, the most of these models are based on empirical relations and do not investigate in detail the phenomena involved in the compaction. In sake of predicting the Ekofisk subsidence while using only independently measurable variables we used a chalk compaction model valid on geological time-scales (Japsen et al. 2011) assuming plastic pore-collapse mechanism at a threshold effective stress level. We identified the phenomena involved in the pore collapse. By putting them in a sequential order we created a simple statistical analytical model. We also investigated the time-dependence of the phenomena involved and by assuming that one of the phenomena is rate-limiting we could make estimations of the compaction rate at smaller length-scales. By carefully investigating the nature of pressure propagation we could upscale our model to reservoir scale. We found that the predicted compaction rates are close enough to the measured rates. We believe that we could further increase accuracy by refining our model. Sulak, R. M., Thomas, L. K., Boade R. R. (1991) 3D reservoir simulation of Ekofisk compaction drive. Journal of Petroleum Technology, 43(10):1272-1278, 1991. Japsen, P., Dysthe, D. K., Hartz, E. H., Stipp, S. L. S., Yarushina, V. M., Jamtveit. (2011) A compaction front in North Sea chalk. Journal of Geophysical Research: Solid Earth (1978

  19. An analysis of nuclear fuel burnup in the AGR-1 TRISO fuel experiment using gamma spectrometry, mass spectrometry, and computational simulation techniques

    DOE PAGES

    Harp, Jason M.; Demkowicz, Paul A.; Winston, Philip L.; Sterbentz, James W.

    2014-09-03

    AGR 1 was the first in a series of experiments designed to test US TRISO fuel under high temperature gas-cooled reactor irradiation conditions. This experiment was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and is currently undergoing post irradiation examination (PIE) at INL and Oak Ridge National Laboratory. One component of the AGR 1 PIE is the experimental evaluation of the burnup of the fuel by two separate techniques. Gamma spectrometry was used to non destructively evaluate the burnup of all 72 of the TRISO fuel compacts that comprised the AGR 1 experiment. Two methodsmore » for evaluating burnup by gamma spectrometry were developed, one based on the Cs 137 activity and the other based on the ratio of Cs 134 and Cs 137 activities. Burnup values determined from both methods compared well with the values predicted from simulations. The highest measured burnup was 20.1% FIMA for the direct method and 20.0% FIMA for the ratio method (compared to 19.56% FIMA from simulations). An advantage of the ratio method is that the burnup of the cylindrical fuel compacts can determined in small (2.5 mm) axial increments and an axial burnup profile can be produced. Destructive chemical analysis by inductively coupled mass spectrometry (ICP MS) was then performed on selected compacts that were representative of the expected range of fuel burnups in the experiment to compare with the burnup values determined by gamma spectrometry. The compacts analyzed by mass spectrometry had a burnup range of 19.3% FIMA to 10.7% FIMA. The mass spectrometry evaluation of burnup for the four compacts agreed well with the gamma spectrometry burnup evaluations and the expected burnup from simulation. For all four compacts analyzed by mass spectrometry, the maximum range in the three experimentally determined values and the predicted value was 6% or less. Furthermore, the results confirm the accuracy of the nondestructive burnup evaluation from gamma

  20. An analysis of nuclear fuel burnup in the AGR-1 TRISO fuel experiment using gamma spectrometry, mass spectrometry, and computational simulation techniques

    SciTech Connect

    Harp, Jason M.; Demkowicz, Paul A.; Winston, Philip L.; Sterbentz, James W.

    2014-09-03

    AGR 1 was the first in a series of experiments designed to test US TRISO fuel under high temperature gas-cooled reactor irradiation conditions. This experiment was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and is currently undergoing post irradiation examination (PIE) at INL and Oak Ridge National Laboratory. One component of the AGR 1 PIE is the experimental evaluation of the burnup of the fuel by two separate techniques. Gamma spectrometry was used to non destructively evaluate the burnup of all 72 of the TRISO fuel compacts that comprised the AGR 1 experiment. Two methods for evaluating burnup by gamma spectrometry were developed, one based on the Cs 137 activity and the other based on the ratio of Cs 134 and Cs 137 activities. Burnup values determined from both methods compared well with the values predicted from simulations. The highest measured burnup was 20.1% FIMA for the direct method and 20.0% FIMA for the ratio method (compared to 19.56% FIMA from simulations). An advantage of the ratio method is that the burnup of the cylindrical fuel compacts can determined in small (2.5 mm) axial increments and an axial burnup profile can be produced. Destructive chemical analysis by inductively coupled mass spectrometry (ICP MS) was then performed on selected compacts that were representative of the expected range of fuel burnups in the experiment to compare with the burnup values determined by gamma spectrometry. The compacts analyzed by mass spectrometry had a burnup range of 19.3% FIMA to 10.7% FIMA. The mass spectrometry evaluation of burnup for the four compacts agreed well with the gamma spectrometry burnup evaluations and the expected burnup from simulation. For all four compacts analyzed by mass spectrometry, the maximum range in the three experimentally determined values and the predicted value was 6% or less. Furthermore, the results confirm the accuracy of the nondestructive burnup evaluation from gamma spectrometry

  1. Nuclear-effects model embedded stochastically in simulation (NEMESIS) summary report. Technical paper

    SciTech Connect

    Youngren, M.A.

    1989-11-01

    An analytic probability model of tactical nuclear warfare in the theater is presented in this paper. The model addresses major problems associated with representing nuclear warfare in the theater. Current theater representations of a potential nuclear battlefield are developed in context of low-resolution, theater-level models or scenarios. These models or scenarios provide insufficient resolution in time and space for modeling a nuclear exchange. The model presented in this paper handles the spatial uncertainty in potentially targeted unit locations by proposing two-dimensional multivariate probability models for the actual and perceived locations of units subordinate to the major (division-level) units represented in theater scenarios. The temporal uncertainty in the activities of interest represented in our theater-level Force Evaluation Model (FORCEM) is handled through probability models of the acquisition and movement of potential nuclear target units.

  2. Assessing the Sensitivity of Satellite-Derived Estimates of Ice Sheet Mass Balance to Regional Climate Model Simulations of Snow Accumulation and Firn Compaction

    NASA Astrophysics Data System (ADS)

    Briggs, K.; Shepherd, A.; Horwath, M.; Horvath, A.; Nagler, T.; Wuite, J.; Muir, A.; Gilbert, L.; Mouginot, J.

    2015-12-01

    Surface mass balance (SMB) estimates from Regional Climate Models (RCMs) are fundamental for assessing and understanding ice sheet mass trends. Mass budget and altimetry assessments rely on RCMs both directly for estimates of the SMB contribution to the total mass trend, and indirectly for ancillary data in the form of firn compaction corrections. As such, mass balance assessments can be highly sensitive to RCM outputs and therefore their accuracy. Here we assess the extent to which geodetic measurements of mass balance are sensitive to RCM model outputs at different resolutions. We achieve this by comparing SMB dependent estimates of mass balance from the mass budget method and altimetry, with those from satellite gravimetry that are independent of SMB estimates. Using the outputs of the RACMO/ANT 2.3 model at 5.5 km and 27 km horizontal spatial resolution, we generate estimates of mass balance using the mass budget method and altimetry for the Western Palmer Land region of the Antarctic Peninsula between 2003 and 2014. We find a 19% increase in the long-term (1980 to 2014) mean annual SMB for the region when enhancing the model resolution to 5.5 km. This translates into an approximate 50% reduction in the total mass loss from 2003 to 2014 calculated with the mass budget method and a 15% increase in the altimetry estimate. The use of the enhanced resolution product leads to consistency between the estimates of mass loss from the altimetry and the mass budget method that is not observed with the coarser resolution product, in which estimates of cumulative mass fall beyond the relative errors. Critically, when using the 5.5 km product, we find excellent agreement, both in pattern and magnitude, with the independent estimate derived from gravimetry. Our results point toward the crucial need for high resolution SMB products from RCMs for mass balance assessments, particularly in regions of high mass turnover and complex terrain as found over the Antarctic Peninsula.

  3. Dynamic magnetic compaction of porous materials

    SciTech Connect

    1998-10-29

    IAP Research began development of the Dynamic Magnetic Compaction (DMC) process three years before the CRADA was established. IAP Research had experimentally demonstrated the feasibility of the process, and conducted a basic market survey. IAP identified and opened discussions with industrial partners and established the basic commercial cost structure. The purpose of this CRADA project was to predict and verify optimum pressure vs. time history for the compaction of porous copper and tungsten. LLNL modeled the rapid compaction of powdered material from an initial density of about 30% theoretical maximum to more than 90% theoretical maximum. The compaction simulations were benchmarked against existing data and new data was acquired by IAP Research. The modeling was used to perform parameter studies on the pressure loading time history, initial porosity and temperature. LLNL ran simulations using codes CALE or NITO and compared the simulations with published compaction data and equation of state (EOS) data. This project did not involve the development or modification of software code. CALE and NITO were existing software programs at LLNL. No modification of these programs occurred within the scope of the CRADA effort.

  4. PARTNERSHIP FOR THE DEVELOPMENT OF NEXT GENERATION SIMULATION TOOLS TO EVALUATE CEMENTITIOUS BARRIERS AND MATERIALS USED IN NUCLEAR APPLICATION - 8388

    SciTech Connect

    Langton, C; Richard Dimenna, R

    2008-01-29

    The US DOE has initiated a multidisciplinary cross cutting project to develop a reasonable and credible set of tools to predict the structural, hydraulic and chemical performance of cement barriers used in nuclear applications over extended time frames (e.g., > 100 years for operating facilities and > 1000 years for waste management). A partnership that combines DOE, NRC, academia, private sector, and international expertise has been formed to accomplish the project objectives by integrating existing information and realizing advancements where necessary. The set of simulation tools and data developed under this project will be used to evaluate and predict the behavior of cementitious barriers used in near surface engineered waste disposal systems, e.g., waste forms, containment structures, entombments and environmental remediation, including decontamination and decommissioning (D&D) activities. The simulation tools will also support analysis of structural concrete components of nuclear facilities (spent fuel pools, dry spent fuel storage units, and recycling facilities, e.g., fuel fabrication, separations processes). Simulation parameters will be obtained from prior literature and will be experimentally measured under this project, as necessary, to demonstrate application of the simulation tools for three prototype applications (waste form in concrete vault, high level waste tank grouting, and spent fuel pool). Test methods and data needs to support use of the simulation tools for future applications will be defined. This is a national issue that affects all waste disposal sites that use cementitious waste forms and structures, decontamination and decommissioning activities, service life determination of existing structures, and design of future public and private nuclear facilities. The problem is difficult because it requires projecting conditions and responses over extremely long times. Current performance assessment analyses show that engineered barriers are

  5. Simulation of ground-water flow near the nuclear-fuel reprocessing facility at the Western New York Nuclear Service Center, Cattaraugus County, New York

    USGS Publications Warehouse

    Yager, R.M.

    1987-01-01

    A two-dimensional finite-difference model was developed to simulate groundwater flow in a surficial sand and gravel deposit underlying the nuclear fuel reprocessing facility at Western New York Nuclear Service Center near West Valley, N.Y. The sand and gravel deposit overlies a till plateau that abuts an upland area of siltstone and shale on its west side, and is bounded on the other three sides by deeply incised stream channels that drain to Buttermilk Creek, a tributary to Cattaraugus Creek. Radioactive materials are stored within the reprocessing plant and are also buried within a till deposit at the facility. Tritiated water is stored in a lagoon system near the plant and released under permit to Franks Creek, a tributary to Buttermilk Creek. Groundwater levels predicted by steady-state simulations closely matched those measured in 23 observation wells, with an average error of 0.5 meter. Simulated groundwater discharges to two stream channels and a subsurface drain were within 5% of recorded values. Steady-state simulations used an average annual recharge rate of 46 cm/yr; predicted evapotranspiration loss from the ground was 20 cm/yr. The lateral range in hydraulic conductivity obtained through model calibration was 0.6 to 10 m/day. Model simulations indicated that 33% of the groundwater discharged from the sand and gravel unit (2.6 L/sec) is lost by evapotranspiration, 3% (3.0 L/sec) flows to seepage faces at the periphery of the plateau, 20% (1.6 L/sec) discharges to stream channels that drain a large wetland area near the center of the plateau, and the remaining 8% (0.6 L/sec) discharges to a subsurface french drain and to a wastewater treatment system. Groundwater levels computed by a transient-state simulation of an annual climatic cycle, including seasonal variation in recharge and evapotranspiration, closely matched water levels measured in eight observation wells. The model predicted that the subsurface drain and the stream channel that drains the

  6. Discrete Element Model for Simulations of Early-Life Thermal Fracturing Behaviors in Ceramic Nuclear Fuel Pellets

    SciTech Connect

    Hai Huang; Ben Spencer; Jason Hales

    2014-10-01

    A discrete element Model (DEM) representation of coupled solid mechanics/fracturing and heat conduction processes has been developed and applied to explicitly simulate the random initiations and subsequent propagations of interacting thermal cracks in a ceramic nuclear fuel pellet during initial rise to power and during power cycles. The DEM model clearly predicts realistic early-life crack patterns including both radial cracks and circumferential cracks. Simulation results clearly demonstrate the formation of radial cracks during the initial power rise, and formation of circumferential cracks as the power is ramped down. In these simulations, additional early-life power cycles do not lead to the formation of new thermal cracks. They do, however clearly indicate changes in the apertures of thermal cracks during later power cycles due to thermal expansion and shrinkage. The number of radial cracks increases with increasing power, which is consistent with the experimental observations.

  7. User's guide and history of ANFO (ammonium nitrate/fuel oil) as a nuclear weapons effect simulation explosive. Technical report

    SciTech Connect

    Petes, J.; Miller, R.; McMullan, F.

    1983-03-31

    The history of the development and use of ANFO as a nuclear-weapons blast, cratering, and ground-shock simulation source, is traced from 1966 to 1976 when the first full-scale target-testing operation was conducted on DICE THROW with a 600-ton ANFO charge. The results of the development tests, of DICE THROW, and of subsequent tests with ANFO through PRE-DIRECT COURSE in 1982, are given and analyzed in terms of explosive-charge performance. The results indicate that ANFO is a safe, economical, and reliable explosive source for effects simulation purposes. The details presented serve as a guide for utilization of ANFO for future similar and more-demanding simulation purposes.

  8. Interrogating Heterogeneous Compaction of Meteoritic Material at the Mesoscale Using Analog Experiments and Numerical Models

    NASA Astrophysics Data System (ADS)

    Derrick, J. G.; Rutherford, M. E.; Davison, T. M.; Eakins, D. E.; Collins, G. S.

    2016-08-01

    We compare experimental results and simulations of mesoscale shock compaction, as potential analogs to the shock metamorphism of meteoritic material. Qualitative agreement suggests the experiments are useful analogs to study meteoritic compaction.

  9. Multi-physics simulation and fabrication of a compact 128 × 128 micro-electro-mechanical system Fabry-Perot cavity tunable filter array for infrared hyperspectral imager.

    PubMed

    Meng, Qinghua; Chen, Sihai; Lai, Jianjun; Huang, Ying; Sun, Zhenjun

    2015-08-01

    This paper demonstrates the design and fabrication of a 128×128 micro-electro-mechanical systems Fabry-Perot (F-P) cavity filter array, which can be applied for the hyperspectral imager. To obtain better mechanical performance of the filters, F-P cavity supporting structures are analyzed by multi-physics finite element modeling. The simulation results indicate that Z-arm is the key component of the structure. The F-P cavity array with Z-arm structures was also fabricated. The experimental results show excellent parallelism of the bridge deck, which agree with the simulation results. A conclusion is drawn that Z-arm supporting structures are important to hyperspectral imaging system, which can achieve a large tuning range and high fill factor compared to straight arm structures. The filter arrays have the potential to replace the traditional dispersive element.

  10. Compact microchannel system

    DOEpatents

    Griffiths, Stewart

    2003-09-30

    The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.

  11. Compact turbidity meter

    NASA Technical Reports Server (NTRS)

    Hirschberg, J. G.

    1979-01-01

    Proposed monitor that detects back-reflected infrared radiation makes in situ turbidity measurements of lakes, streams, and other bodies of water. Monitor is compact, works well in daylight as at night, and is easily operated in rough seas.

  12. Integrated nuclear and conventional theater warfare simulation (INWARS) documentation. Part IV. User's manual component. Volume II. Combat interactions input. Final report

    SciTech Connect

    Aldrich, J.R.; Gilmer, J.B.

    1980-02-08

    This is Volume II of the User's Manual Component of the Integrated Nuclear and Conventional Theater Warfare Simulation (INWARS) documentation. It presents the content and format of user inputs to the INWARS treatment of combat interactions.

  13. Numerical simulation of gas dynamics and heat exchange tasks in fuel assemblies of the nuclear reactors

    SciTech Connect

    Zhuchenko, S. V.

    2014-11-12

    This report presents a PC-based program for solution gas dynamics and heat exchange mathematical tasks in fuel assemblies of the fast-neutron nuclear reactors. A fuel assembly consisting of bulk heat-generating elements, which are integrated together by the system of supply and pressure manifolds, is examined. Spherical heat-generating microelements, which contain nuclear fuel, are pulled into the heat-generating elements. Gaseous coolant proceed from supply manifolds to heat-generating elements, where it withdraws the nuclear reaction heat and assembles in pressure manifolds.

  14. Impacts by Compact Ultra Dense Objects

    NASA Astrophysics Data System (ADS)

    Birrell, Jeremey; Labun, Lance; Rafelski, Johann

    2012-03-01

    We propose to search for nuclear density or greater compact ultra dense objects (CUDOs), which could constitute a significant fraction of the dark matter [1]. Considering their high density, the gravitational tidal forces are significant and atomic-density matter cannot stop an impacting CUDO, which punctures the surface of the target body, pulverizing, heating and entraining material near its trajectory through the target [2]. Because impact features endure over geologic timescales, the Earth, Moon, Mars, Mercury and large asteroids are well-suited to act as time-integrating CUDO detectors. There are several potential candidates for CUDO structure such as strangelet fragments or more generally dark matter if mechanisms exist for it to form compact objects. [4pt] [1] B. J. Carr, K. Kohri, Y. Sendouda, & J.'i. Yokoyama, Phys. Rev. D81, 104019 (2010). [0pt] [2] L. Labun, J. Birrell, J. Rafelski, Solar System Signatures of Impacts by Compact Ultra Dense Objects, arXiv:1104.4572.

  15. Biosorption of strontium from simulated nuclear wastewater by Scenedesmus spinosus under culture conditions: adsorption and bioaccumulation processes and models.

    PubMed

    Liu, Mingxue; Dong, Faqin; Kang, Wu; Sun, Shiyong; Wei, Hongfu; Zhang, Wei; Nie, Xiaoqin; Guo, Yuting; Huang, Ting; Liu, Yuanyuan

    2014-06-01

    Algae biosorption is an ideal wastewater treatment method when coupled with algae growth and biosorption. The adsorption and bioaccumulation of strontium from simulated nuclear wastewater by Scenedesmus spinosus were investigated in this research. One hundred mL of cultured S. spinosus cells with a dry weight of 1.0 mg in simulated nuclear wastewater were used to analyze the effects on S. spinosus cell growth as well as the adsorption and bioaccumulation characters under conditions of 25 ± 1 °C with approximately 3,000 lux illumination. The results showed that S. spinosus had a highly selective biosorption capacity for strontium, with a maximum bioremoval ratio of 76%. The adsorbed strontium ion on cell walls was approximately 90% of the total adsorbed amount; the bioaccumulation in the cytoplasm varied by approximately 10%. The adsorption quantity could be described with an equilibrium isotherm. The pseudo-second-order kinetic model suggested that adsorption was the rate-limiting step of the biosorption process. A new bioaccumulation model with three parameters was proposed and could give a good fit with the experiment data. The results suggested that S. spinosus may be a potential biosorbent for the treatment of nuclear wastewater in culture conditions.

  16. Nuclear Winter.

    ERIC Educational Resources Information Center

    Ehrlich, Anne

    1984-01-01

    "Nuclear Winter" was recently coined to describe the climatic and biological effects of a nuclear war. These effects are discussed based on models, simulations, scenarios, and projections. Effects on human populations are also considered. (JN)

  17. Simulated microgravity inhibits osteogenic differentiation of mesenchymal stem cells via depolymerizing F-actin to impede TAZ nuclear translocation.

    PubMed

    Chen, Zhe; Luo, Qing; Lin, Chuanchuan; Kuang, Dongdong; Song, Guanbin

    2016-01-01

    Microgravity induces observed bone loss in space flight, and reduced osteogenesis of bone mesenchymal stem cells (BMSCs) partly contributes to this phenomenon. Abnormal regulation or functioning of the actin cytoskeleton induced by microgravity may cause the inhibited osteogenesis of BMSCs, but the underlying mechanism remains obscure. In this study, we demonstrated that actin cytoskeletal changes regulate nuclear aggregation of the transcriptional coactivator with PDZ-binding motif (TAZ), which is indispensable for osteogenesis of bone mesenchymal stem cells (BMSCs). Moreover, we utilized a clinostat to model simulated microgravity (SMG) and demonstrated that SMG obviously depolymerized F-actin and hindered TAZ nuclear translocation. Interestingly, stabilizing the actin cytoskeleton induced by Jasplakinolide (Jasp) significantly rescued TAZ nuclear translocation and recovered the osteogenic differentiation of BMSCs in SMG, independently of large tumor suppressor 1(LATS1, an upstream kinase of TAZ). Furthermore, lysophosphatidic acid (LPA) also significantly recovered the osteogenic differentiation of BMSCs in SMG through the F-actin-TAZ pathway. Taken together, we propose that the depolymerized actin cytoskeleton inhibits osteogenic differentiation of BMSCs through impeding nuclear aggregation of TAZ, which provides a novel connection between F-actin cytoskeleton and osteogenesis of BMSCs and has important implications in bone loss caused by microgravity. PMID:27444891

  18. Simulated microgravity inhibits osteogenic differentiation of mesenchymal stem cells via depolymerizing F-actin to impede TAZ nuclear translocation

    PubMed Central

    Chen, Zhe; Luo, Qing; Lin, Chuanchuan; Kuang, Dongdong; Song, Guanbin

    2016-01-01

    Microgravity induces observed bone loss in space flight, and reduced osteogenesis of bone mesenchymal stem cells (BMSCs) partly contributes to this phenomenon. Abnormal regulation or functioning of the actin cytoskeleton induced by microgravity may cause the inhibited osteogenesis of BMSCs, but the underlying mechanism remains obscure. In this study, we demonstrated that actin cytoskeletal changes regulate nuclear aggregation of the transcriptional coactivator with PDZ-binding motif (TAZ), which is indispensable for osteogenesis of bone mesenchymal stem cells (BMSCs). Moreover, we utilized a clinostat to model simulated microgravity (SMG) and demonstrated that SMG obviously depolymerized F-actin and hindered TAZ nuclear translocation. Interestingly, stabilizing the actin cytoskeleton induced by Jasplakinolide (Jasp) significantly rescued TAZ nuclear translocation and recovered the osteogenic differentiation of BMSCs in SMG, independently of large tumor suppressor 1(LATS1, an upstream kinase of TAZ). Furthermore, lysophosphatidic acid (LPA) also significantly recovered the osteogenic differentiation of BMSCs in SMG through the F-actin-TAZ pathway. Taken together, we propose that the depolymerized actin cytoskeleton inhibits osteogenic differentiation of BMSCs through impeding nuclear aggregation of TAZ, which provides a novel connection between F-actin cytoskeleton and osteogenesis of BMSCs and has important implications in bone loss caused by microgravity. PMID:27444891

  19. Influence of solar heating and precipitation scavenging on the simulated lifetime of post-nuclear war smoke

    NASA Technical Reports Server (NTRS)

    Malone, R. C.; Auer, L. H.; Glatzmaier, G. A.; Wood, M. C.; Toon, O. B.

    1985-01-01

    The behavior of smoke injected into the atmosphere by massive fires that might follow a nuclear war was simulated. Studies with a three-dimensional global atmospheric circulation model showed that heating of the smoke by sunlight would be important and might produce several effects that would decrease the efficiency with which precipitation removes smoke from the atmosphere. The heating gives rise to vertical motions that carry smoke well above the original injection height. Heating of the smoke also causes the tropopause, which is initially above the smoke, to reform below the heated smoke layer. Smoke above the tropopause is physically isolated from precipitation below. Consequently, the atmospheric residence time of the remaining smoke is greatly increased over the prescribed residence times used in previous models of nuclear winter.

  20. Flow Components in a NaK Test Loop Designed to Simulate Conditions in a Nuclear Surface Power Reactor

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Godfroy, Thomas J.

    2008-01-01

    A test loop using NaK as the working fluid is presently in use to study material compatibility effects on various components that comprise a possible nuclear reactor design for use on the lunar surface. A DC electromagnetic (EM) pump has been designed and implemented as a means of actively controlling the NaK flow rate through the system and an EM flow sensor is employed to monitor the developed flow rate. These components allow for the matching of the flow rate conditions in test loops with those that would be found in a full-scale surface-power reactor. The design and operating characteristics of the EM pump and flow sensor are presented. In the EM pump, current is applied to a set of electrodes to produce a Lorentz body force in the fluid. A measurement of the induced voltage (back-EMF) in the flow sensor provides the means of monitoring flow rate. Both components are compact, employing high magnetic field strength neodymium magnets thermally coupled to a water-cooled housing. A vacuum gap limits the heat transferred from the high temperature NaK tube to the magnets and a magnetically-permeable material completes the magnetic circuit. The pump is designed to produce a pressure rise of 5 psi, and the flow sensor's predicted output is roughly 20 mV at the loop's nominal flow rate of 0.5 GPM.

  1. Flow Components in a NaK Test Loop Designed to Simulate Conditions in a Nuclear Surface Power Reactor

    SciTech Connect

    Polzin, Kurt A.; Godfroy, Thomas J.

    2008-01-21

    A test loop using NaK as the working fluid is presently in use to study material compatibility effects on various components that comprise a possible nuclear reactor design for use on the lunar surface. A DC electromagnetic (EM) pump has been designed and implemented as a means of actively controlling the NaK flow rate through the system and an EM flow sensor is employed to monitor the developed flow rate. These components allow for the matching of the flow rate conditions in test loops with those that would be found in a full-scale surface-power reactor. The design and operating characteristics of the EM pump and flow sensor are presented. In the EM pump, current is applied to a set of electrodes to produce a Lorentz body force in the fluid. A measurement of the induced voltage (back-EMF) in the flow sensor provides the means of monitoring flow rate. Both components are compact, employing high magnetic field strength neodymium magnets thermally coupled to a water-cooled housing. A vacuum gap limits the heat transferred from the high temperature NaK tube to the magnets and a magnetically-permeable material completes the magnetic circuit. The pump is designed to produce a pressure rise of 34.5 kPa, and the flow sensor's predicted output is roughly 20 mV at the loop's nominal flow rate of 0.114 m{sup 3}/hr.

  2. Dirt depreciation of compact fluorescent lamp downlights

    SciTech Connect

    Siminovitch, M.; Hamilton, A.; Zhang, Chin; Verderber, R.

    1993-08-01

    An experimental protocol and apparatus was developed to assess the relative differences in dirt depreciation between vented and unvented compact fluorescent recessed downlights under simulated conditions. A simulated plenum/ceiling chamber is designed to expose both vented and unvented fixtures simultaneously to a controlled dust environment over an extended period of time. Experimental data shows that the unvented fixture depreciated faster over time due to dust exposure than the vented fixture.

  3. Activation of nuclear transcription factor-kappaB in mouse brain induced by a simulated microgravity environment

    NASA Technical Reports Server (NTRS)

    Wise, Kimberly C.; Manna, Sunil K.; Yamauchi, Keiko; Ramesh, Vani; Wilson, Bobby L.; Thomas, Renard L.; Sarkar, Shubhashish; Kulkarni, Anil D.; Pellis, Neil R.; Ramesh, Govindarajan T.

    2005-01-01

    Microgravity induces inflammatory responses and modulates immune functions that may increase oxidative stress. Exposure to a microgravity environment induces adverse neurological effects; however, there is little research exploring the etiology of these effects resulting from exposure to such an environment. It is also known that spaceflight is associated with increase in oxidative stress; however, this phenomenon has not been reproduced in land-based simulated microgravity models. In this study, an attempt has been made to show the induction of reactive oxygen species (ROS) in mice brain, using ground-based microgravity simulator. Increased ROS was observed in brain stem and frontal cortex with concomitant decrease in glutathione, on exposing mice to simulated microgravity for 7 d. Oxidative stress-induced activation of nuclear factor-kappaB was observed in all the regions of the brain. Moreover, mitogen-activated protein kinase kinase was phosphorylated equally in all regions of the brain exposed to simulated microgravity. These results suggest that exposure of brain to simulated microgravity can induce expression of certain transcription factors, and these have been earlier argued to be oxidative stress dependent.

  4. Development of a dynamic model to evaluate economic recovery following a nuclear attack. Volume 1. Description and simulations. Final report

    SciTech Connect

    Peterson, D.W.; Silverman, W.S.; Weil, H.B.; Willard, S.

    1980-11-01

    A highly-robust, dynamic simulation model of the US economy has been constructed to evaluate the likely economic response after various nuclear attacks or other severe disruptions, under various policies and assumptions. The model consists of a large system of nonlinear, recursive, time-difference equations. The solution-interval of the model is adjustable, with a maximum value of three weeks. The model represents the economy in thirteen sectors. Each sector contains a detailed representation of production, distribution, supply constraints, finance, employment, pricing, and wages. Also included are a full input-output representation of the interconnections among the sectors, and the psychological responses of corporate planners, consumers, and the labor force. The model's equations are formulated to remain consistent and realistic for all values of the variables, including the most extreme conditions. Therefore, the model can realistically simulate any degree or time sequence of nuclear attacks, pre-attack surges, mobilization, or policy shifts. Simulation experiments with the model suggest that the economy is highly vulnerable to nuclear attack, and that recovery requires extensive preparation, including psychological readiness, technology maintenance, special financial policies, and (if possible) maintenance of foreign trade. Civil defense policies must be adaptive (contingent on the nature of the damage) and must strive for balance among sectors, rather than maximum survival. This volume includes two appendices. Appendix A defines the aggregation of the model. Appendix B outlines the range of attack scenarios, pre-attack civil defense policies, and post-attack civil defense policies that can be evaluated with the model, including the model variables applicable to implementing those policies.

  5. Monte Carlo simulation of the nuclear-electromagnetic cascade development and the energy response of ionization spectrometers

    NASA Technical Reports Server (NTRS)

    Jones, W. V.

    1973-01-01

    Modifications to the basic computer program for performing the simulations are reported. The major changes include: (1) extension of the calculations to include the development of cascades initiated by heavy nuclei, (2) improved treatment of the nuclear disintegrations which occur during the interactions of hadrons in heavy absorbers, (3) incorporation of accurate multi-pion final-state cross sections for various interactions at accelerator energies, (4) restructuring of the program logic so that calculations can be made for sandwich-type detectors, and (5) logic modifications related to execution of the program.

  6. The behavior of ANGRA 2 nuclear power plant core for a small break LOCA simulated with RELAP5 code

    SciTech Connect

    Sabundjian, Gaiane; Andrade, Delvonei A.; Belchior, Antonio Jr.; Silva Rocha, Marcelo da; Conti, Thadeu N.; Torres, Walmir M.; Macedo, Luiz A.; Umbehaun, Pedro E.; Mesquita, Roberto N.; Masotti, Paulo H. F.; Souza Lima, Ana Cecilia de

    2013-05-06

    This work discusses the behavior of Angra 2 nuclear power plant core, for a postulate Loss of Coolant Accident (LOCA) in the primary circuit for Small Break Loss Of Coolant Accident (SBLOCA). A pipe break of the hot leg Emergency Core Cooling System (ECCS) was simulated with RELAP 5 code. The considered rupture area is 380 cm{sup 2}, which represents 100% of the ECCS pipe flow area. Results showed that the cooling is enough to guarantee the integrity of the reactor core.

  7. Science based integrated approach to advanced nuclear fuel development - integrated multi-scale multi-physics hierarchical modeling and simulation framework Part III: cladding

    SciTech Connect

    Tome, Carlos N; Caro, J A; Lebensohn, R A; Unal, Cetin; Arsenlis, A; Marian, J; Pasamehmetoglu, K

    2010-01-01

    Advancing the performance of Light Water Reactors, Advanced Nuclear Fuel Cycles, and Advanced Reactors, such as the Next Generation Nuclear Power Plants, requires enhancing our fundamental understanding of fuel and materials behavior under irradiation. The capability to accurately model the nuclear fuel systems to develop predictive tools is critical. Not only are fabrication and performance models needed to understand specific aspects of the nuclear fuel, fully coupled fuel simulation codes are required to achieve licensing of specific nuclear fuel designs for operation. The backbone of these codes, models, and simulations is a fundamental understanding and predictive capability for simulating the phase and microstructural behavior of the nuclear fuel system materials and matrices. In this paper we review the current status of the advanced modeling and simulation of nuclear reactor cladding, with emphasis on what is available and what is to be developed in each scale of the project, how we propose to pass information from one scale to the next, and what experimental information is required for benchmarking and advancing the modeling at each scale level.

  8. Development of a test system for verification and validation of nuclear transport simulations

    SciTech Connect

    White, Morgan C; Triplett, Brian S; Anghaie, Samim

    2008-01-01

    Verification and validation of nuclear data is critical to the accuracy of both stochastic and deterministic particle transport codes. In order to effectively test a set of nuclear data, the data must be applied to a wide variety of transport problems. Performing this task in a timely, efficient manner is tedious. The nuclear data team at Los Alamos National laboratory in collaboration with the University of Florida has developed a methodology to automate the process of nuclear data verification and validation (V and V). This automated V and V process can efficiently test a number of data libraries using well defined benchmark experiments, such as those in the International Criticality Safety Benchmark Experiment Project (ICSBEP). The process is implemented through an integrated set of Pyton scripts. Material and geometry data are read from an existing medium or given directly by the user to generate a benchmark experiment template file. The user specifies the choice of benchmark templates, codes, and libraries to form a V and V project. The Python scripts generate input decks for multiple transport codes from the templates, run and monitor individual jobs, and parse the relevant output automatically. The output can then be used to generate reports directly or can be stored into a database for later analysis. This methodology eases the burden on the user by reducing the amount of time and effort required for obtaining and compiling calculation results. The resource savings by using this automated methodology could potentially be an enabling technology for more sophisticated data studies, such as nuclear data uncertainty quantification. Once deployed, this tool will allow the nuclear data community to more thoroughly test data libraries leading to higher fidelity data in the future.

  9. The dynamic ejecta of compact object mergers and eccentric collisions.

    PubMed

    Rosswog, Stephan

    2013-06-13

    Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the 'heavy' (A>130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta ('macronovae'), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium. PMID:23630377

  10. Fully coupled analysis of reservoir compaction and subsidence

    SciTech Connect

    Gutierrez, M.; Hansteen, H.

    1994-12-31

    This paper discusses the differences between fully-coupled and uncoupled formulations of models of production and subsidence. For highly compacting hydrocarbon reservoirs, production can cause compaction of the reservoir and subsidence of the overburden, and in turn, compaction and subsidence can affect the productivity of the reservoir by increasing the reservoir pressure. Intuitively, analyses of production and subsidence should be done in a fully-coupled fashion. However, most, if not all, of the analyses done so far on compacting reservoirs are uncoupled where production and subsidence are calculated in a staggered manner. The results of the numerical analyses using an uncoupled reservoir simulation, and a fully-coupled finite element simulation based on Biot`s formulation of a typical compacting reservoir are presented and compared. Different pore pressure response were obtained depending on whether an uncoupled or a fully-coupled analysis was performed, and also depending on whether there is arching of the overburden or not. The results of fully-coupled analyses of compaction and subsidence showed that the generation of additional pore pressure due to compaction cannot be correctly analyzed by simply adjusting the rock compressibilities in reservoir simulation. The most pronounced effect of coupling, obtained from the numerical simulations, is on the possibility of pore pressure increase close to the reservoir flanks even during production. The implications of the differences in the results of fully-coupled and uncoupled simulations are discussed.

  11. Hollow fibers for compact infrared gas sensors

    NASA Astrophysics Data System (ADS)

    Lambrecht, A.; Hartwig, S.; Herbst, J.; Wöllenstein, J.

    2008-02-01

    Hollow fibers can be used for compact infrared gas sensors. The guided light is absorbed by the gas introduced into the hollow core. High sensitivity and a very small sampling volume can be achieved depending on fiber parameters i.e. attenuation, flexibility, and gas exchange rates. Different types of infrared hollow fibers including photonic bandgap fibers were characterized using quantum cascade lasers and thermal radiation sources. Obtained data are compared with available product specifications. Measurements with a compact fiber based ethanol sensor are compared with a system simulation. First results on the detection of trace amounts of the explosive material TATP using hollow fibers and QCL will be shown.

  12. A survey of non-U.S. nuclear electromagnetic pulse (EMP) simulators

    SciTech Connect

    Giles, J.C.

    1997-12-01

    This paper, an update of papers presented in 1984 and 1995, describes the large number and diverse variety of EMP simulators that exist outside the US. The end of the Cold War has provided the opportunity to learn of new simulators and to compare their characteristics as well as the test methods employed in them. While similarities exist with EMP simulators developed in the US and other western countries, in some cases the simulators developed by researchers of the former Soviet Union and other Warsaw Pact nations provide some very interesting differences in approach. As is the case with US EMP simulators, no one perfect EMP simulator exists. Baum has classified non-source region EMP simulators in three categories: (1) guided wave, (2) dipole, and (3) hybrid. This paper describes several examples that fall into these three categories as well as a unique source region simulator in Russia that does not. All designs have inherent limitations; thus the large variety that exists. Some analysis and extrapolation of results must always be done. The ideal of a simple zap test to prove a system hard to EMP is just that--an unachievable ideal.

  13. Discrete-event simulation of nuclear-waste transport in geologic sites subject to disruptive events. Final report

    SciTech Connect

    Aggarwal, S.; Ryland, S.; Peck, R.

    1980-06-19

    This report outlines a methodology to study the effects of disruptive events on nuclear waste material in stable geologic sites. The methodology is based upon developing a discrete events model that can be simulated on the computer. This methodology allows a natural development of simulation models that use computer resources in an efficient manner. Accurate modeling in this area depends in large part upon accurate modeling of ion transport behavior in the storage media. Unfortunately, developments in this area are not at a stage where there is any consensus on proper models for such transport. Consequently, our work is directed primarily towards showing how disruptive events can be properly incorporated in such a model, rather than as a predictive tool at this stage. When and if proper geologic parameters can be determined, then it would be possible to use this as a predictive model. Assumptions and their bases are discussed, and the mathematical and computer model are described.

  14. Multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories

    SciTech Connect

    Rutqvist, J.; Backstrom, A.; Chijimatsu, M.; Feng, X.-T.; Pan, P.-Z.; Hudson, J.; Jing, L.; Kobayashi, A.; Koyama, T.; Lee, H.-S.; Huang, X.-H.; Rinne, M.; Shen, B.

    2008-10-23

    This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elastoplastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such time-dependency is insignificant after peak temperature, because decreasing thermal stress.

  15. Numerical Simulation of Plasma Behavior in a Magnetic Nozzle of a Laser-plasma Driven Nuclear Electric Propulsion System

    SciTech Connect

    Kajimura, Y.; Matsuda, N.; Hayashida, K.; Maeno, A.; Nakashima, H.

    2008-12-31

    Numerical simulations of plasma behavior in a magnetic nozzle of a Laser-Plasma Driven Nuclear Electric Propulsion System are conducted. The propellant is heated and accelerated by the laser and expanded isotropically. The magnetic nozzle is a combination of solenoidal coils and used to collimate and guide the plasma to produce thrust. Simulation calculations by a three-dimensional hybrid code are conducted to examine the plasma behaviors in the nozzle and to estimate the thrust efficiency. We also estimate a fraction ({alpha}) of plasma particles leaking in the forward (spacecraft) direction. By a combination of a few coils, we could decrease {alpha} value without degrading the thrust efficiency. Finally, the shaped propellant is proposed to increase the thrust efficiency.

  16. Panel sees limited interest in compact nukes

    SciTech Connect

    Not Available

    1983-11-01

    Participants in the Joint Power Generation conference thought compact (200- to 300-MW) nuclear reactors would be useful to developing countries, but only the Canadians showed interest in becoming suppliers. Others said they would simply downsize existing designs. A 300-MW mini-Candu that can be built in 48 months will use proven components and have the same price tag as a full-sized unit. A market may develop in the future in the US and other industrialized countries for low-temperature heat sources. Another 5 to 10 developing countries would likely join the 7 now using nuclear power. (DCK)

  17. Green strength of zirconium sponge and uranium dioxide powder compacts

    SciTech Connect

    Balakrishna, Palanki Murty, B. Narasimha; Sahoo, P.K.; Gopalakrishna, T.

    2008-07-15

    Zirconium metal sponge is compacted into rectangular or cylindrical shapes using hydraulic presses. These shapes are stacked and electron beam welded to form a long electrode suitable for vacuum arc melting and casting into solid ingots. The compact electrodes should be sufficiently strong to prevent breakage in handling as well as during vacuum arc melting. Usually, the welds are strong and the electrode strength is limited by the green strength of the compacts, which constitute the electrode. Green strength is also required in uranium dioxide (UO{sub 2}) powder compacts, to withstand stresses during de-tensioning after compaction as well as during ejection from the die and for subsequent handling by man and machine. The strengths of zirconium sponge and UO{sub 2} powder compacts have been determined by bending and crushing respectively, and Weibul moduli evaluated. The green density of coarse sponge compact was found to be larger than that from finer sponge. The green density of compacts from lightly attrited UO{sub 2} powder was higher than that from unattrited category, accompanied by an improvement in UO{sub 2} green crushing strength. The factors governing green strength have been examined in the light of published literature and experimental evidence. The methodology and results provide a basis for quality control in metal sponge and ceramic powder compaction in the manufacture of nuclear fuel.

  18. Corrosion Resistance of Various High Chromium Alloys in Simulated Chemical Processing Nuclear Plant Waste Solutions

    SciTech Connect

    Anderson, P.A.; Agarwal, D.C.

    1997-12-31

    High chromium nickel alloys were tested at the Idaho Chemical Processing Plant (ICPP) to determine their corrosion performance in the high temperature aggressive chemical environments of liquid waste evaporators used in the chemical reprocessing of irradiated nuclear fuels. The results of these tests, which included a variety of base metal alloys I weld filler material combinations, are presented and discussed.

  19. Discussion [of ``The use of conditional simulation in nuclear-waste-site performance assessment`` by Carol A. Gotway

    SciTech Connect

    Downing, D.J.

    1994-05-01

    EPA 40 CFR 191.16 (EPA 1985) states in part that the disposal systems should be designed to provide reasonable expectation that for 1,000 years after disposal, undisturbed performance of the disposal system shall not cause radionuclide concentrations to exceed specified limits. The question is how can one, with the tools that one has today, establish with some degree of confidence that a requirement like that just given will be achieved? Over the last several years, this has been demonstrated through the use of simulation analysis of the system being studied. An example of such a study on nuclear reactor criticality is described. Then the author discusses Carol Gotway`s study on WIPP. The author believes that work on computer simulation models is extremely important. These are primary tools one has for investigating many complex problems--for example, groundwater contamination, molecular dynamics, climate modeling, and nuclear-reactor accidents. Many of these models are being investigated at the national laboratories but unfortunately often without any help from statisticians. The article by Gotway shows another example of how statistics can be applied to a complicated process to yield practical results.

  20. The effects of host galaxy properties on merging compact binaries detectable by LIGO

    NASA Astrophysics Data System (ADS)

    O'shaughnessy, R.; Bellovary, J. M.; Brooks, A.; Shen, S.; Governato, F.; Christensen, C. R.

    2016-10-01

    Cosmological simulations of galaxy formation can produce present-day galaxies with a large range of assembly and star formation histories. A detailed study of the metallicity evolution and star formation history of such simulations can assist in predicting LIGO-detectable compact object binary mergers. Recent simulations of compact binary evolution suggest the compact object merger rate depends sensitively on the progenitor's metallicity. Rare low-metallicity star formation during galaxy assembly can produce more detected compact binaries than typical star formation. Using detailed simulations of galaxy and chemical evolution, we determine how sensitively the compact binary populations of galaxies with similar present-day appearance depend on the details of their assembly. We also demonstrate by concrete example the extent to which dwarf galaxies overabundantly produce compact binary mergers, particularly binary black holes, relative to more massive galaxies. We discuss the implications for transient multimessenger astronomy with compact binary sources.

  1. On-the-fly nuclear data processing methods for Monte Carlo simulations of fast spectrum systems

    SciTech Connect

    Walsh, Jon

    2015-08-31

    The presentation summarizes work performed over summer 2015 related to Monte Carlo simulations. A flexible probability table interpolation scheme has been implemented and tested with results comparing favorably to the continuous phase-space on-the-fly approach.

  2. The Molecular Mechanism of Bisphenol A (BPA) as an Endocrine Disruptor by Interacting with Nuclear Receptors: Insights from Molecular Dynamics (MD) Simulations

    PubMed Central

    Li, Lanlan; Wang, Qianqian; Zhang, Yan; Niu, Yuzhen; Yao, Xiaojun; Liu, Huanxiang

    2015-01-01

    Bisphenol A (BPA) can interact with nuclear receptors and affect the normal function of nuclear receptors in very low doses, which causes BPA to be one of the most controversial endocrine disruptors. However, the detailed molecular mechanism about how BPA interferes the normal function of nuclear receptors is still undiscovered. Herein, molecular dynamics simulations were performed to explore the detailed interaction mechanism between BPA with three typical nuclear receptors, including hERα, hERRγ and hPPARγ. The simulation results and calculated binding free energies indicate that BPA can bind to these three nuclear receptors. The binding affinities of BPA were slightly lower than that of E2 to these three receptors. The simulation results proved that the binding process was mainly driven by direct hydrogen bond and hydrophobic interactions. In addition, structural analysis suggested that BPA could interact with these nuclear receptors by mimicking the action of natural hormone and keeping the nuclear receptors in active conformations. The present work provided the structural evidence to recognize BPA as an endocrine disruptor and would be important guidance for seeking safer substitutions of BPA. PMID:25799048

  3. The molecular mechanism of bisphenol A (BPA) as an endocrine disruptor by interacting with nuclear receptors: insights from molecular dynamics (MD) simulations.

    PubMed

    Li, Lanlan; Wang, Qianqian; Zhang, Yan; Niu, Yuzhen; Yao, Xiaojun; Liu, Huanxiang

    2015-01-01

    Bisphenol A (BPA) can interact with nuclear receptors and affect the normal function of nuclear receptors in very low doses, which causes BPA to be one of the most controversial endocrine disruptors. However, the detailed molecular mechanism about how BPA interferes the normal function of nuclear receptors is still undiscovered. Herein, molecular dynamics simulations were performed to explore the detailed interaction mechanism between BPA with three typical nuclear receptors, including hERα, hERRγ and hPPARγ. The simulation results and calculated binding free energies indicate that BPA can bind to these three nuclear receptors. The binding affinities of BPA were slightly lower than that of E2 to these three receptors. The simulation results proved that the binding process was mainly driven by direct hydrogen bond and hydrophobic interactions. In addition, structural analysis suggested that BPA could interact with these nuclear receptors by mimicking the action of natural hormone and keeping the nuclear receptors in active conformations. The present work provided the structural evidence to recognize BPA as an endocrine disruptor and would be important guidance for seeking safer substitutions of BPA.

  4. Compact, Integrated Photoelectron Linacs

    NASA Astrophysics Data System (ADS)

    Yu, David

    2000-12-01

    The innovative compact high energy iniector which has been developed by DULY Research Inc., will have wide scientific industrial and medical applications. The new photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injector and the linac. By focusing the beam with solenoid or permanent magnets, and producing high current with low emittance, extremely high brightness is achieved. In addition to providing a small footprint and improved beam quality in an integrated structure, the compact system considerably simplifies external subsystems required to operate the photoelectron linac, including rf power transport, beam focusing, vacuum and cooling. The photoelectron linac employs an innovative Plane-Wave-Transformer (PWT) design, which provides strong cell-to-cell coupling, relaxes manufacturing tolerance and facilitates the attachment of external ports to the compact structure with minimal field interference. DULY Research Inc. under the support of the DOE Small Business Innovation Research (SBIR) program, has developed, constructed and installed a 20-MeV, S-band compact electron source at UCLA. DULY Research is also presently engaged in the development of an X-band photoelectron linear accelerator in another SBIR project. The higher frequency structure when completed will be approximately three times smaller, and capable of a beam brightness ten times higher than the S-band structure.

  5. COMPACT SCHOOL AND $$ SAVINGS.

    ERIC Educational Resources Information Center

    BAIR, W.G.

    A REVIEW OF THE CRITERIA FOR CONSIDERING THE USE OF A TOTAL ENERGY SYSTEM WITHIN A SCHOOL BUILDING STATES THE WINDOWLESS, COMPACT SCHOOL OFFERS MORE EFFICIENT SPACE UTILIZATION WITH LESS AREA REQUIRED FOR GIVEN STUDENT POPULATION AND LOWER OPERATION COSTS. THE AUTHOR RECOMMENDS THAT THESE BUILDINGS BE WINDOWLESS TO REDUCE HEAT COSTS, HOWEVER, AT…

  6. Compact optical transconductance varistor

    SciTech Connect

    Sampayan, Stephen

    2015-09-22

    A compact radiation-modulated transconductance varistor device having both a radiation source and a photoconductive wide bandgap semiconductor material (PWBSM) integrally formed on a substrate so that a single interface is formed between the radiation source and PWBSM for transmitting PWBSM activation radiation directly from the radiation source to the PWBSM.

  7. FAULT DIAGNOSIS WITH MULTI-STATE ALARMS IN A NUCLEAR POWER CONTROL SIMULATOR

    SciTech Connect

    Austin Ragsdale; Roger Lew; Brian P. Dyre; Ronald L. Boring

    2012-10-01

    This research addresses how alarm systems can increase operator performance within nuclear power plant operations. The experiment examined the effect of two types of alarm systems (two-state and three-state alarms) on alarm compliance and diagnosis for two types of faults differing in complexity. We hypothesized three-state alarms would improve performance in alarm recognition and fault diagnoses over that of two-state alarms. We used sensitivity and criterion based on Signal Detection Theory to measure performance. We further hypothesized that operator trust would be highest when using three-state alarms. The findings from this research showed participants performed better and had more trust in three-state alarms compared to two-state alarms. Furthermore, these findings have significant theoretical implications and practical applications as they apply to improving the efficiency and effectiveness of nuclear power plant operations.

  8. Fault Diagnosis with Multi-State Alarms in a Nuclear Power Control Simulation

    SciTech Connect

    Stuart A. Ragsdale; Roger Lew; Ronald L. Boring

    2014-09-01

    This research addresses how alarm systems can increase operator performance within nuclear power plant operations. The experiment examined the effects of two types of alarm systems (two-state and three-state alarms) on alarm compliance and diagnosis for two types of faults differing in complexity. We hypothesized the use of three-state alarms would improve performance in alarm recognition and fault diagnoses over that of two-state alarms. Sensitivity and criterion based on the Signal Detection Theory were used to measure performance. We further hypothesized that operator trust would be highest when using three-state alarms. The findings from this research showed participants performed better and had more trust in three-state alarms compared to two-state alarms. Furthermore, these findings have significant theoretical implications and practical applications as they apply to improving the efficiency and effectiveness of nuclear power plant operations.

  9. Nuclear Energy Advanced Modeling and Simulation (NEAMS) waste Integrated Performance and Safety Codes (IPSC) : gap analysis for high fidelity and performance assessment code development.

    SciTech Connect

    Lee, Joon H.; Siegel, Malcolm Dean; Arguello, Jose Guadalupe, Jr.; Webb, Stephen Walter; Dewers, Thomas A.; Mariner, Paul E.; Edwards, Harold Carter; Fuller, Timothy J.; Freeze, Geoffrey A.; Jove-Colon, Carlos F.; Wang, Yifeng

    2011-03-01

    This report describes a gap analysis performed in the process of developing the Waste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The goal of the Waste IPSC is to develop an integrated suite of computational modeling and simulation capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive waste storage or disposal system. The Waste IPSC will provide this simulation capability (1) for a range of disposal concepts, waste form types, engineered repository designs, and geologic settings, (2) for a range of time scales and distances, (3) with appropriate consideration of the inherent uncertainties, and (4) in accordance with rigorous verification, validation, and software quality requirements. The gap analyses documented in this report were are performed during an initial gap analysis to identify candidate codes and tools to support the development and integration of the Waste IPSC, and during follow-on activities that delved into more detailed assessments of the various codes that were acquired, studied, and tested. The current Waste IPSC strategy is to acquire and integrate the necessary Waste IPSC capabilities wherever feasible, and develop only those capabilities that cannot be acquired or suitably integrated, verified, or validated. The gap analysis indicates that significant capabilities may already exist in the existing THC codes although there is no single code able to fully account for all physical and chemical processes involved in a waste disposal system. Large gaps exist in modeling chemical processes and their couplings with other processes. The coupling of chemical processes with flow transport and mechanical deformation remains challenging. The data for extreme environments (e.g., for elevated temperature and high ionic strength media) that are

  10. Simulating Effects of Non-Isothermal Flow on Reactive Transport of Radionuclides Originating from an Underground Nuclear Test

    SciTech Connect

    Carle, S F; Zavarin, M; Shumaker, D E; Tompson, A B; Maxwell, R M; Pawloski, G A

    2006-03-06

    Temperature can significantly affect radionuclide transport behavior. In simulation of radionuclide transport originating from an underground nuclear test, temperature effects from residual test heat include non-isothermal groundwater flow behavior (e.g. convection cells), increased dissolution rates of melt glass containing refractory radionuclides, changes in water chemistry, and, in turn, changes in radionuclide sorption behavior. The low-yield (0.75 kiloton) Cambric underground nuclear test situated in alluvium below the water table offers unique perspectives on radionuclide transport in groundwater. The Cambric test was followed by extensive post-test characterization of the radionuclide source term and a 16-year pumping-induced radionuclide migration experiment that captured more mobile radionuclides in groundwater. Discharge of pumped groundwater caused inadvertent recirculation of radionuclides through a 220-m thick vadose zone to the water table and below, including partial re-capture in the pumping well. Non-isothermal flow simulations indicate test-related heat persists at Cambric for about 10 years and induces limited thermal convection of groundwater. The test heat has relatively little impact on mobilizing radionuclides compared to subsequent pumping effects. However, our reactive transport models indicate test-related heat can raise melt glass dissolution rates up to 10{sup 4} faster than at ambient temperatures depending on pH and species activities. Non-isothermal flow simulations indicate that these elevated glass dissolution rates largely decrease within 1 year. Thermally-induced increases in fluid velocity may also significantly increase rates of melt glass dissolution by changing the fluid chemistry in contact with the dissolving glass.

  11. Simulated Verification of Fuel Element Inventory in a Small Reactor Core Using the Nuclear Materials Identification System (NMIS)

    SciTech Connect

    Grogan, Brandon R; Mihalczo, John T

    2009-01-01

    The International Panel on Climate Change projects that by 2050 the world energy demand may double. Although the primary focus for new nuclear power plants in industrialized nations is on large plants in the 1000-1600 MWe range, there is an increasing demand for small and medium reactors (SMRs). About half of the innovative SMR concepts are for small (<300 MWe) reactors with a 5-30 year life without on-site refueling. This type of reactor is also known as a battery-type reactor. These reactors are particularly attractive to countries with small power grids and for non-electrical purposes such as heating, hydrogen production, and seawater desalination. Traditionally, this type of reactor has been used in a nautical propulsion role. This type of reactor is designed as a permanently sealed unit to prevent the diversion of the uranium in the core by the user. However, after initial fabrication it will be necessary to verify that the newly fabricated reactor core contains the quantity of uranium that initially entered the fuel fabrication plant. In most instances, traditional inspection techniques can be used to perform this verification, but in certain situations the core design will be considered sensitive. Non-intrusive verification techniques must be utilized in these situations. The Nuclear Materials Identification System (NMIS) with imaging uses active interrogation and a fast time correlation processor to characterize fissile material. The MCNP-PoliMi computer code was used to simulate NMIS measurements of a small, sealed reactor core. Because most battery-type reactor designs are still in the early design phase, a more traditional design based on a Russian icebreaker core was used in the simulations. These simulations show how the radiography capabilities of the NMIS could be used to detect the diversion of fissile material by detecting void areas in the assembled core where fuel elements have been removed.

  12. Use of simulation to examine operational scenarios in a lathe glovebox for the processing of nuclear materials.

    SciTech Connect

    McQueen, M.; Ashok, P.; Cox, D. J.; Pittman, P. C.; Turner, C. J.; Hollen, R. M.

    2001-06-01

    In the process of dispositioning nuclear materials into storage, the use of a robot eliminates the safety risks to humans and increases productivity. The current process of processing typically uses humans to handle the hazardous material using gloves through glove-ports. This process is not only dangerous, but also costly, because humans can only be subjected to limited exposure to nuclear materials due to the actual Occupational Radiation Exposure (ORE) and thus have a fixed amount of dedicated workload per unit time. Use of robotics reduces ORE to humans and increases productivity. The Robotics Research Group at the University of Texas at Austin has created a simulation model of a conceptual application that uses a robot inside the glovebox to handle hazardous materials for lathe machining process operations in cooperation with Los Alamos National Laboratories (LANL). The actions of the robot include preparing the parts for entry into the box, weighing the parts, positioning the parts into the headstock chuck of the lathe, handling the subsequent processed parts, changing and replacing the lathe tools and chuck assemblies are necessary to process the material. The full three-dimensional geometric model of the simulation demonstrates the normal expected operation from beginning to end and verifies the path plans for the robot. The emphasis of this paper is to report additional findings from the simulation model, which is currently being expanded to include failure mode analysis, error recovery, and other what-if scenarios involved in unexpected, or unplanned, operation of the robot and lathe process inside of the glovebox.

  13. A Compact Wakefield Measurement Facility

    NASA Astrophysics Data System (ADS)

    Power, J. G.; Gai, W.

    2015-10-01

    The conceptual design of a compact, photoinjector-based, facility for high precision measurements of wakefields is presented. This work is motivated by the need for a thorough understanding of beam induced wakefield effects for any future linear collider. We propose to use a high brightness photoinjector to generate (approximately) a 2 nC, 2 mm-mrad drive beam at 20 MeV to excite wakefields and a second photoinjector to generate a 5 MeV, variably delayed, trailing witness beam to probe both the longitudinal and transverse wakefields in the structure under test. Initial estimates show that we can detect a minimum measurable dipole transverse wake function of 0.1 V/pC/m/mm and a minimum measurable monopole longitudinal wake function of 2.5 V/pC/m. Simulations results for the high brightness photoinjector, calculations of the facility's wakefield measurement resolution, and the facility layout are presented.

  14. WE-D-BRF-01: FEATURED PRESENTATION - Investigating Particle Track Structures Using Fluorescent Nuclear Track Detectors and Monte Carlo Simulations

    SciTech Connect

    Dowdell, S; Paganetti, H; Schuemann, J; Greilich, S; Zimmerman, F; Evans, C

    2014-06-15

    Purpose: To report on the efforts funded by the AAPM seed funding grant to develop the basis for fluorescent nuclear track detector (FNTD) based radiobiological experiments in combination with dedicated Monte Carlo simulations (MCS) on the nanometer scale. Methods: Two confocal microscopes were utilized in this study. Two FNTD samples were used to find the optimal microscope settings, one FNTD irradiated with 11.1 MeV/u Gold ions and one irradiated with 428.77 MeV/u Carbon ions. The first sample provided a brightly luminescent central track while the latter is used to test the capabilities to observe secondary electrons. MCS were performed using TOPAS beta9 version, layered on top of Geant4.9.6p02. Two sets of simulations were performed, one with the Geant4-DNA physics list and approximating the FNTDs by water, a second set using the Penelope physics list in a water-approximated FNTD and a aluminum-oxide FNTD. Results: Within the first half of the funding period, we have successfully established readout capabilities of FNTDs at our institute. Due to technical limitations, our microscope setup is significantly different from the approach implemented at the DKFZ, Germany. However, we can clearly reconstruct Carbon tracks in 3D with electron track resolution of 200 nm. A second microscope with superior readout capabilities will be tested in the second half of the funding period, we expect an improvement in signal to background ratio with the same the resolution.We have successfully simulated tracks in FNTDs. The more accurate Geant4-DNA track simulations can be used to reconstruct the track energy from the size and brightness of the observed tracks. Conclusion: We have achieved the goals set in the seed funding proposal: the setup of FNTD readout and simulation capabilities. We will work on improving the readout resolution to validate our MCS track structures down to the nanometer scales.

  15. Methodology for testing infrared focal plane arrays in simulated nuclear radiation environments

    NASA Astrophysics Data System (ADS)

    Divita, E. L.; Mills, R. E.; Koch, T. L.; Gordon, M. J.; Wilcox, R. A.; Williams, R. E.

    1992-07-01

    This paper summarizes test methodology for focal plane array (FPA) testing that can be used for benign (clear) and radiation environments, and describes the use of custom dewars and integrated test equipment in an example environment. The test methodology, consistent with American Society for Testing Materials (ASTM) standards, is presented for the total accumulated gamma dose, transient dose rate, gamma flux, and neutron fluence environments. The merits and limitations of using Cobalt 60 for gamma environment simulations and of using various fast-neutron reactors and neutron sources for neutron simulations are presented. Test result examples are presented to demonstrate test data acquisition and FPA parameter performance under different measurement conditions and environmental simulations.

  16. A code to simulate nuclear reactor inventories and associated gamma-ray spectra.

    PubMed

    Cresswell, A J; Allyson, J D; Sanderson, D C

    2001-01-01

    A computer code has been developed to simulate the gamma-ray spectra that would be measured by airborne gamma spectrometry (AGS) systems from sources containing short-lived fission products. The code uses simple numerical methods to simulate the production and decay of fission products and generates spectra for sodium iodide (NaI) detectors using Monte Carlo codes. A new Monte Carlo code using a virtual array of detectors to reduce simulation times for airborne geometries is described. Spectra generated for a short irradiation and laboratory geometry have been compared with an experimental data set. The agreement is good. Spectra have also been generated for airborne geometries and longer irradiation periods. The application of this code to generate AGS spectra for accident scenarios and their uses in the development and evaluation of spectral analysis methods for such situations are discussed.

  17. Actinide extraction from simulated and irradiated spent nuclear fuel using TBP solutions in HFC-134a

    SciTech Connect

    Shadrin, A.; Babain, V.; Kamachev, V.; Murzin, A.; Shafikov, D.; Dormidonova, A.

    2008-07-01

    It was demonstrated that solutions of TBP-nitric acid adduct in liquid Freon HFC-134a (1.2 MPa, 25 deg. C) allowed for recovery of uranium with nearly the same effectiveness as supercritical CO{sub 2} at 30 MPa. At nearly quantitative recovery of U and Pu, a DF of ca. 10 can be attained on dissolution and extraction of simulated SNF samples. The possibility of recovery of actinides contained in cakes produced by oxide conversion of simulated and irradiated SNF with solutions of TBP and DBE in Freon HFC-134a was shown. (authors)

  18. Experimental investigation to simulate propellant heating in the nuclear light bulb engine.

    NASA Technical Reports Server (NTRS)

    Klein, J. F.

    1971-01-01

    Experiments to heat a simulated propellant to high bulk temperatures by the absorption of thermal radiation are discussed. Argon seeded with micron-sized carbon particles was used as the simulated propellant; a 500 kw d-c arc was used as the radiant energy source. Bulk temperatures up to 3860 K were obtained with greater than 95% of the incident radiation absorbed. The arc radiation source, seed dispersal equipment, techniques used to prevent transparent wall coating by the seeds, and calorimetric measurement of bulk temperature are also discussed.

  19. Progress in Compact Toroid Experiments

    SciTech Connect

    Dolan, Thomas James

    2002-09-01

    The term "compact toroids" as used here means spherical tokamaks, spheromaks, and field reversed configurations, but not reversed field pinches. There are about 17 compact toroid experiments under construction or operating, with approximate parameters listed in Table 1.

  20. Nuclear Energy Advanced Modeling and Simulation (NEAMS) Waste Integrated Performance and Safety Codes (IPSC) : FY10 development and integration.

    SciTech Connect

    Criscenti, Louise Jacqueline; Sassani, David Carl; Arguello, Jose Guadalupe, Jr.; Dewers, Thomas A.; Bouchard, Julie F.; Edwards, Harold Carter; Freeze, Geoffrey A.; Wang, Yifeng; Schultz, Peter Andrew

    2011-02-01

    This report describes the progress in fiscal year 2010 in developing the Waste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The goal of the Waste IPSC is to develop an integrated suite of computational modeling and simulation capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive waste storage or disposal system. The Waste IPSC will provide this simulation capability (1) for a range of disposal concepts, waste form types, engineered repository designs, and geologic settings, (2) for a range of time scales and distances, (3) with appropriate consideration of the inherent uncertainties, and (4) in accordance with robust verification, validation, and software quality requirements. Waste IPSC activities in fiscal year 2010 focused on specifying a challenge problem to demonstrate proof of concept, developing a verification and validation plan, and performing an initial gap analyses to identify candidate codes and tools to support the development and integration of the Waste IPSC. The current Waste IPSC strategy is to acquire and integrate the necessary Waste IPSC capabilities wherever feasible, and develop only those capabilities that cannot be acquired or suitably integrated, verified, or validated. This year-end progress report documents the FY10 status of acquisition, development, and integration of thermal-hydrologic-chemical-mechanical (THCM) code capabilities, frameworks, and enabling tools and infrastructure.

  1. The effect of chromium oxide on the properties of simulated nuclear waste glasses

    SciTech Connect

    Vojtech, O.; Sussmilch, J.; Urbanec, Z.

    1996-02-01

    A study of the effect of chromium on the properties of selected glasses was performed in the frame of a Contract between Battelle, Pacific Northwest Laboratories and Nuclear Research Institute, ReZ. In the period from July 1994 to June 1995 two borosilicate glasses of special composition were prepared according to the PNL procedure and their physical and structural characteristics of glasses were studied. This Final Report contains a vast documentation on the properties of all glasses studied. For the preparation of the respective technology more detailed study of physico-chemical properties and crystallinity of investigated systems would be desirable.

  2. General Relativity&Compact Stars

    SciTech Connect

    Glendenning, Norman K.

    2005-08-16

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

  3. The Development of Models to Optimize Selection of Nuclear Fuels through Atomic-Level Simulation

    SciTech Connect

    Prof. Simon Phillpot; Prof. Susan B. Sinnott; Prof. Hans Seifert; Prog. James Tulenko

    2009-01-26

    Demonstrated that FRAPCON can be modified to accept data generated from first principles studies, and that the result obtained from the modified FRAPCON make sense in terms of the inputs. Determined the temperature dependence of the thermal conductivity of single crystal UO2 from atomistic simulation.

  4. Compact Spreader Schemes

    SciTech Connect

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  5. Compact torsatron reactors

    SciTech Connect

    Lyon, J.F.; Carreras, B.A.; Lynch, V.E.; Tolliver, J.S.; Sviatoslavsky, I.N.

    1988-05-01

    Low-aspect-ratio torsatron configurations could lead to compact stellarator reactors with R/sub 0/ = 8--11m, roughly one-half to one-third the size of more conventional stellarator reactor designs. Minimum-size torsatron reactors are found using various assumptions. Their size is relatively insensitive to the choice of the conductor parameters and depends mostly on geometrical constraints. The smallest size is obtained by eliminating the tritium breeding blanket under the helical winding on the inboard side and by reducing the radial depth of the superconducting coil. Engineering design issues and reactor performance are examined for three examples to illustrate the feasibility of this approach for compact reactors and for a medium-size (R/sub 0/ approx. = 4 m,/bar a/ /approx lt/ 1 m) copper-coil ignition experiment. 26 refs., 11 figs., 7 tabs.

  6. Compact spreader schemes

    NASA Astrophysics Data System (ADS)

    Placidi, M.; Jung, J.-Y.; Ratti, A.; Sun, C.

    2014-12-01

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  7. Super-Compact Laser

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Microcosm, Inc. produced the portable Farfield-2 laser for field applications that require high power pulsed illumination. The compact design was conceived through research at Goddard Space Flight Center on laser instruments for space missions to carry out geoscience studies of Earth. An exclusive license to the key NASA patent for the compact laser design was assigned to Microcosm. The FarField-2 is ideal for field applications, has low power consumption, does not need water cooling or gas supplies, and produces nearly ideal beam quality. The properties of the laser also make it effective over long distances, which is one reason why NASA developed the technology for laser altimeters that can be toted aboard spacecraft. Applications for the FarField-2 include medicine, biology, and materials science and processing, as well as diamond marking, semiconductor line-cutting, chromosome surgery, and fluorescence microscopy.

  8. Corrigendum to "Coupled thermochemical, isotopic evolution and heat transfer simulations in highly irradiated UO2 nuclear fuel"

    NASA Astrophysics Data System (ADS)

    Piro, M. H. A.; Banfield, J.; Clarno, K.; Simunovic, S.; Besmann, T. M.; Lewis, B. J.; Thompson, W. T.

    2016-09-01

    Figs. 7-9 in "Coupled thermochemical, isotopic evolution and heat transfer simulations in highly irradiated UO2 nuclear fuel" [1] have a consistent error corresponding to the relative proportions of iodine. Reported concentrations of iodine in the original manuscript are approximately ten times higher than expected, and are comparable in atomic proportions to cesium. One would expect that the amount of cesium would be about one order of magnitude greater than iodine based on the difference in fission yields of 235U and 239Pu. A practical consequence of this error would affect the predicted quantity and chemical composition of iodine on the fuel surface, which is related to iodine-induced stress corrosion cracking [2].

  9. A predictive model of nuclear power plant crew decision-making and performance in a dynamic simulation environment

    NASA Astrophysics Data System (ADS)

    Coyne, Kevin Anthony

    The safe operation of complex systems such as nuclear power plants requires close coordination between the human operators and plant systems. In order to maintain an adequate level of safety following an accident or other off-normal event, the operators often are called upon to perform complex tasks during dynamic situations with incomplete information. The safety of such complex systems can be greatly improved if the conditions that could lead operators to make poor decisions and commit erroneous actions during these situations can be predicted and mitigated. The primary goal of this research project was the development and validation of a cognitive model capable of simulating nuclear plant operator decision-making during accident conditions. Dynamic probabilistic risk assessment methods can improve the prediction of human error events by providing rich contextual information and an explicit consideration of feedback arising from man-machine interactions. The Accident Dynamics Simulator paired with the Information, Decision, and Action in a Crew context cognitive model (ADS-IDAC) shows promise for predicting situational contexts that might lead to human error events, particularly knowledge driven errors of commission. ADS-IDAC generates a discrete dynamic event tree (DDET) by applying simple branching rules that reflect variations in crew responses to plant events and system status changes. Branches can be generated to simulate slow or fast procedure execution speed, skipping of procedure steps, reliance on memorized information, activation of mental beliefs, variations in control inputs, and equipment failures. Complex operator mental models of plant behavior that guide crew actions can be represented within the ADS-IDAC mental belief framework and used to identify situational contexts that may lead to human error events. This research increased the capabilities of ADS-IDAC in several key areas. The ADS-IDAC computer code was improved to support additional

  10. Accuracy and convergence of coupled finite-volume/Monte Carlo codes for plasma edge simulations of nuclear fusion reactors

    NASA Astrophysics Data System (ADS)

    Ghoos, K.; Dekeyser, W.; Samaey, G.; Börner, P.; Baelmans, M.

    2016-10-01

    The plasma and neutral transport in the plasma edge of a nuclear fusion reactor is usually simulated using coupled finite volume (FV)/Monte Carlo (MC) codes. However, under conditions of future reactors like ITER and DEMO, convergence issues become apparent. This paper examines the convergence behaviour and the numerical error contributions with a simplified FV/MC model for three coupling techniques: Correlated Sampling, Random Noise and Robbins Monro. Also, practical procedures to estimate the errors in complex codes are proposed. Moreover, first results with more complex models show that an order of magnitude speedup can be achieved without any loss in accuracy by making use of averaging in the Random Noise coupling technique.

  11. Discussion of the paper ``the use of conditional simulation in nuclear waste site performance assessment,`` by Carol A. Gotway

    SciTech Connect

    Gilbert, R.O.; Doctor, P.G.

    1993-08-01

    First, we applaud Dr. Gotway for seeking via her paper to expose a wider audience of statisticians to the many interesting and challenging modeling and statistical problems in the environmental area. This well-written paper effective explains the WIPP and the context of the analysis. Dr. Gotway`s paper describes a geostatistical conditional simulation approach combined with deterministic modeling to estimate the cumulative distribution function (cdf) of groundwater travel time (GWTT), information that is needed for estimating the cumulative release of nuclear waste from the repository. We begin our discussion with comments and questions on modeling aspects of Dr. Gotway`s paper. Then we discuss uncertainty and sensitivity analyses and some of the problems inherent with implementing those techniques including correlations, elicitation of expert opinion, and planning to achieve specified Data Quality Objectives (DQOs).

  12. Performance of a PADC personal neutron dosemeter at simulated and real workplace fields of the nuclear industry.

    PubMed

    Fiechtner, A; Boschung, M; Wernli, C

    2007-01-01

    In the framework of the EVIDOS (Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields) project, funded by the EC, measurements with PADC personal neutron dosemeters were carried out at several workplace fields of the nuclear industry and at simulated workplace fields. The measured personal neutron dose equivalents of the PADC personal neutron dosemeter are compared with values that were assessed within the EVIDOS project by other partners. The detection limits for different spectra types are given. In cases were the neutron dose was too low to be measured by the PADC personal neutron dosemeter, the response is estimated by convoluting the responses to monoenergetic neutrons with the dose energy distribution measured within EVIDOS. The advantages and limitations of the PADC personal neutron dosemeter are discussed. PMID:17578876

  13. 13C Nuclear magnetic resonance studies of kerogen from Cretaceous black shales thermally altered by basaltic intrusions and laboratory simulations

    USGS Publications Warehouse

    Dennis, L.W.; Maciel, G.E.; Hatcher, P.G.; Simoneit, B.R.T.

    1982-01-01

    Cretaceous black shales from DSDP Leg 41, Site 368 in the Eastern Atlantic Ocean were thermally altered during the Miocene by an intrusive basalt. The sediments overlying and underlying the intrusive body were subjected to high temperatures (up to ~ 500??C) and, as a result, their kerogen was significantly altered. The extent of this alteration has been determined by examination by means of 13C nuclear magnetic resonance, using cross polarization/magic-angle spinning (CP/MAS). Results indicate that the kerogen becomes progressively more aromatic in the vicinity of the intrusive body. Laboratory heating experiments, simulating the thermal effects of the basaltic intrusion, produced similar results on unaltered shale from the drill core. The 13C CP/MAS results appear to provide a good measure of thermal alteration. ?? 1982.

  14. Simulation of Carbon-14 Migration Through a Thick Unsaturated Alluvial Basin Resulting from an Underground Nuclear Explosion

    NASA Astrophysics Data System (ADS)

    Martian, P.; Larentzos, J.

    2008-12-01

    Yucca Flat is one of several areas on the Nevada Test Site that was used for underground nuclear testing. Extensive testing performed in the unsaturated and saturated zones have resulted in groundwater contamination and surface subsidence craters in the vicinity of the underground test areas. Simulation of multiphase 14C transport through the thick Yucca Flat alluvial basin was performed to estimate the magnitude of radionuclide attenuation occurring within the unsaturated zone. Parameterization of the 14C transport in the multiphase flow and transport simulator (FEHM) was verified with experimental data collected from a large unsaturated soil column experiment. The experimental data included 14C as a radio-labeled bicarbonate solution, SF6 gas, and lithium bromide solution breakthroughs. Two representative simulation cases with working points located at shallow and deep depths relative to the water table were created to investigate the impact of subsidence crater-enhanced recharge, crater-playa areal extent, gas-phase partitioning, solid-phase partitioning, and a reduced permeability/porosity compressed zone created during the explosion on 14C transport. The representative shallow test had a detonation point located 175 m below land surface, and the deep test had a working point 435 m below land surface in a 500 m deep unsaturated zone. Carbon-14 transport is influenced by gas-phase diffusion and sorption within the alluvium. Gas-phase diffusion is an attenuation mechanism that transports 14C gas as 14CO2 throughout the unsaturated zone and exposes it to a large amount of soil moisture, resulting in dilute concentrations. The simulations indicated that the majority of the 14C inventory remains in the unsaturated zone over a 1,000-year time period after detonation because gas-phase diffusion moves the bulk of the 14C away from the higher recharge occurring in crater playas. Retardation also plays a role in slowing advective aqueous phase transport to the water

  15. Comment on: ‘A Poisson resampling method for simulating reduced counts in nuclear medicine images’

    NASA Astrophysics Data System (ADS)

    de Nijs, Robin

    2015-07-01

    In order to be able to calculate half-count images from already acquired data, White and Lawson published their method based on Poisson resampling. They verified their method experimentally by measurements with a Co-57 flood source. In this comment their results are reproduced and confirmed by a direct numerical simulation in Matlab. Not only Poisson resampling, but also two direct redrawing methods were investigated. Redrawing methods were based on a Poisson and a Gaussian distribution. Mean, standard deviation, skewness and excess kurtosis half-count/full-count ratios were determined for all methods, and compared to the theoretical values for a Poisson distribution. Statistical parameters showed the same behavior as in the original note and showed the superiority of the Poisson resampling method. Rounding off before saving of the half count image had a severe impact on counting statistics for counts below 100. Only Poisson resampling was not affected by this, while Gaussian redrawing was less affected by it than Poisson redrawing. Poisson resampling is the method of choice, when simulating half-count (or less) images from full-count images. It simulates correctly the statistical properties, also in the case of rounding off of the images.

  16. The solution conformation of the antibacterial peptide cecropin A: A nuclear magnetic resonance and dynamical simulated annealing study

    SciTech Connect

    Holak, T.A.; Gronenborn, A.M.; Clore, G.M. ); Engstroem, A.; Kraulis, P.J.; Lindeberg, G.; Bennich, H.; Jones, T.A. )

    1988-10-04

    The solution conformation of the antibacterial polypeptide cecropin A from the Cecropia moth is investigated by nuclear magnetic resonance (NMR) spectroscopy under conditions where it adopts a fully ordered structure, as judged by previous circular dichroism studies. By use of a combination of two-dimensional NMR techniques the {sup 1}H NMR spectrum of cecropin A is completely assigned. A set of 243 approximate interproton distance restraints is derived from nuclear Overhauser enhancement (NOE) measurements. These, together with 32 restraints for the 16 intrahelical hydrogen bonds identified on the basis of the pattern of short-range NOEs, form the basis of a three-dimensional structure determination by dynamical simulated annealing. The calculations are carried out starting from three initial structures, an {alpha}-helix, an extended {beta}-strand, and a mixed {alpha}/{beta} structure. Seven independent structures are computed from each starting structure by using a different random number seeds for the assignments of the initial velocities. Analysis of the 21 converged structure indicates that there are two helical regions extending from residues 5 to 21 and from residues 24 to 37 which are very well defined in terms of both atomic root mean square differences and backbone torsion angles. The long axes of the two helices lie in two planes, which are at an angle of 70-100{degree} to each other. The orientation of the helices within these planes, however, cannot be determined due to the paucity of NOEs between the two helices.

  17. Laser-driven coupled electron-nuclear dynamics: Quantum mechanical simulation of molecular photodesorption from metal films

    NASA Astrophysics Data System (ADS)

    Klamroth, Tillmann; Kröner, Dominik; Saalfrank, Peter

    2005-11-01

    In this paper we report dynamical simulations of laser-driven, coupled nuclear-electron dynamics for a molecule-surface system. Specifically, the laser desorption of a small molecule (NO) from a metal slab (Pt) in the so-called DIET limit (Desorption Induced by Electronic Transitions), is studied. The excitation of the metal electrons by a laser pulse followed by the formation of a negative ion resonance, its subsequent decay, and the simultaneous desorption of the molecule are all treated within a single quantum mechanical model. This model is based on an earlier theory of Harris and others [S. M. Harris, S. Holloway, and G. R. Darling, J. Chem. Phys. 102, 8235 (1995)], according to which a nuclear degree of freedom is coupled to an electronic one, both propagated on a single non-Born-Oppenheimer potential energy surface. The goals of the present contribution are (i) to make a conceptual connection of this model to the frequently adopted nonadiabatic “multi-state” models of photodesorption, (ii) to understand details of the desorption mechanism, (iii) to explicitly account for the laser pulse, and (iv) to study the photodesorption as a function of the thickness of the metal film, and the laser parameters. As an important methodological aspect we also present a highly efficient numerical scheme to propagate the wave packet in a problem-adapted diabatic basis.

  18. Simulation of 13C nuclear magnetic resonance spectra for isodon terpenoid

    NASA Astrophysics Data System (ADS)

    Yang, Guochen; Tong, Jianbo; Liu, Shuling

    2008-11-01

    A quantitative structure spectroscopy relationship (QSSR) model of 13C nuclear magnetic resonance (NMR) of 7000 carbon atoms in 350 isodon terpenoid compounds has been developed using atomic electronegativity distance vector (AEDV) and atomic hybridization state index (AHSI). The prediction correlation coefficient ( R) value of the QSSR model based on multiple linear regression analysis was 0.9542. The stability and prediction capacity of the QSSR model have been tested using the leave-one-out cross-validation and test sets methodology. The correlation coefficients R obtained were 0.9540 and 0.9556, respectively, which showed that the predictive potential of the proposed models has good modeling stability and prediction ability.

  19. QUANTUM SIMULATION. Localization-delocalization transition in the dynamics of dipolar-coupled nuclear spins.

    PubMed

    Álvarez, Gonzalo A; Suter, Dieter; Kaiser, Robin

    2015-08-21

    Nonequilibrium dynamics of many-body systems are important in many scientific fields. Here, we report the experimental observation of a phase transition of the quantum coherent dynamics of a three-dimensional many-spin system with dipolar interactions. Using nuclear magnetic resonance (NMR) on a solid-state system of spins at room-temperature, we quench the interaction Hamiltonian to drive the evolution of the system. Depending on the quench strength, we then observe either localized or extended dynamics of the system coherence. We extract the critical exponents for the localized cluster size of correlated spins and diffusion coefficient around the phase transition separating the localized from the delocalized dynamical regime. These results show that NMR techniques are well suited to studying the nonequilibrium dynamics of complex many-body systems. PMID:26293957

  20. The effect of friction on simulated containment of underground nuclear explosions

    SciTech Connect

    Attia, A.V.

    1990-11-01

    The strength of the residual stress field is used as an important indicator in assessing the containment of underground nuclear explosions. Containment analysis using the COTTAGE geology shows considerable cracking in the hard Paleozoic layer, just below the cavity. The coefficient of friction is the ratio of total shear stress applied to a closed fracture surface to normal applied compressive total stress. Without any friction, the Paleozoic residual stress field is weakest. As the friction coefficient is increased from 0 to 0.5, the Paleozoic residual stress field is strengthened. A further increase of the friction coefficient from 0.5 to 0.8 shows strengthened where cracks are closed and weakening where cracks remain open. 4 refs., 4 figs., 1 tab.

  1. Low-temperature lithium diffusion in simulated high-level boroaluminosilicate nuclear waste glasses

    SciTech Connect

    Neeway, James J.; Kerisit, Sebastien N.; Gin, Stephane; Wang, Zhaoying; Zhu, Zihua; Ryan, Joseph V.

    2014-12-01

    Ion exchange is recognized as an integral, if underrepresented, mechanism influencing glass corrosion. However, due to the formation of various alteration layers in the presence of water, it is difficult to conclusively deconvolute the mechanisms of ion exchange from other processes occurring simultaneously during corrosion. In this work, an operationally inert non-aqueous solution was used as an alkali source material to isolate ion exchange and study the solid-state diffusion of lithium. Specifically, the experiments involved contacting glass coupons relevant to the immobilization of high-level nuclear waste, SON68 and CJ-6, which contained Li in natural isotope abundance, with a non-aqueous solution of 6LiCl dissolved in dimethyl sulfoxide at 90 °C for various time periods. The depth profiles of major elements in the glass coupons were measured using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Lithium interdiffusion coefficients, DLi, were then calculated based on the measured depth profiles. The results indicate that the penetration of 6Li is rapid in both glasses with the simplified CJ-6 glass (D6Li ≈ 4.0-8.0 × 10-21 m2/s) exhibiting faster exchange than the more complex SON68 glass (DLi ≈ 2.0-4.0 × 10-21 m2/s). Additionally, sodium ions present in the glass were observed to participate in ion exchange reactions; however, different diffusion coefficients were necessary to fit the diffusion profiles of the two alkali ions. Implications of the diffusion coefficients obtained in the absence of alteration layers to the long-term performance of nuclear waste glasses in a geological repository system are also discussed.

  2. Hydraulic conductivity of compacted zeolites.

    PubMed

    Oren, A Hakan; Ozdamar, Tuğçe

    2013-06-01

    Hydraulic conductivities of compacted zeolites were investigated as a function of compaction water content and zeolite particle size. Initially, the compaction characteristics of zeolites were determined. The compaction test results showed that maximum dry unit weight (γ(dmax)) of fine zeolite was greater than that of granular zeolites. The γ(dmax) of compacted zeolites was between 1.01 and 1.17 Mg m(-3) and optimum water content (w(opt)) was between 38% and 53%. Regardless of zeolite particle size, compacted zeolites had low γ(dmax) and high w(opt) when compared with compacted natural soils. Then, hydraulic conductivity tests were run on compacted zeolites. The hydraulic conductivity values were within the range of 2.0 × 10(-3) cm s(-1) to 1.1 × 10(-7) cm s(-1). Hydraulic conductivity of all compacted zeolites decreased almost 50 times as the water content increased. It is noteworthy that hydraulic conductivity of compacted zeolite was strongly dependent on the zeolite particle size. The hydraulic conductivity decreased almost three orders of magnitude up to 39% fine content; then, it remained almost unchanged beyond 39%. Only one report was found in the literature on the hydraulic conductivity of compacted zeolite, which is in agreement with the findings of this study.

  3. Simulation Of Ion Implantation Into Nuclear Materials And Comparison With Experiment

    NASA Astrophysics Data System (ADS)

    Insepov, Z.; Yun, D.; Ye, B.; Rest, J.; Starikov, S.; Yacout, A. M.

    2011-06-01

    A new many-body potential is proposed for pure molybdenum that consists of using ab initio and atomistic MD simulation methods verified against existing surface erosion experimental data. Mo is an important material for metallic U-Mo alloys for using them in low-enriched fuels. Several new Xe-Mo potentials were also parameterized by comparing the calculated sputtering yield of a Mo-surface bombarded with Xe ions with experimental data. Calculated results were also compared with defect distributions in CeO2 crystals obtained from experiments by 500 keV Xe implantation at the doses of 1×1017 ions/cm2 at several temperatures.

  4. Structure of amorphous oxide ceramics by nuclear magnetic resonance spectroscopy and molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Diefenbacher, Jason Ross

    Molecular dynamics (MD) simulations have been used to study the structure and dynamics of sodium tetrasilicate (Na2Si4O9 ) liquid as a function of pressure, ranging from I atmosphere to 100 GPa, at a temperature of 6000 K. The calculated self-diffusivity of the ions increases with increasing pressure, up to a maximum of approximately 10--15 GPa. Above this pressure, the O2- diffusivity decreases slightly with increasing pressure. The results of the simulations allow the distinction of two different mechanisms for the pressure-induced coordination change of silicon. The first, occurring at lower pressures, involves the formation of V-coordinated silicon, via reaction with non-bridging oxygens. The high pressure mechanism involves a reaction of bridging oxygens, which results in the formation of III-coordinated oxygen. MD simulations were carried out in order to investigate the structure and transport properties of boron oxide melt, as a function of pressure. The simulations show a rapid initial increase in the diffusion coefficients of boron and oxygen ions to ˜5--7 GPa, followed by a slower increase from 7--14 GPa. The increase in ion diffusivities is correlated with an increase in the proportion of BO4 to BO3 units. These results can be used to help rationalize an increase in growth rate of boron suboxide (B6O) crystals, observed from B2O3-B 6O melts in the 0--4 GPa pressure range. Structural characterization has also been carried out on a decomposed alumina ceramic precursor material, which is synthesized via thermal decomposition of an aluminum nitrate, nanohydrate [Al(NO3)3·9H 2O] salt to yield an x-ray amorphous, water-soluble precursor. Characterization of the solid precursor is presented, along with an in-depth study on the aluminum speciation in solution. Although the solid precursor contains entirely VI-coordinated aluminum, the solution phase contains IV-, V-, and VI-coordinated aluminum, whose relative abundance does not change with increasing thermal

  5. Nuclear spectroscopy for in situ soil elemental analysis: Monte Carlo simulations

    SciTech Connect

    Wielopolski L.; Doron, O.

    2012-07-01

    We developed a model to simulate a novel inelastic neutron scattering (INS) system for in situ non-destructive analysis of soil using standard Monte Carlo Neutron Photon (MCNP5a) transport code. The volumes from which 90%, 95%, and 99% of the total signal are detected were estimated to be 0.23 m{sup 3}, 0.37 m{sup 3}, and 0.79 m{sup 3}, respectively. Similarly, we assessed the instrument's sampling footprint and depths. In addition we discuss the impact of the carbon's depth distribution on sampled depth.

  6. Computer program TRACK_VISION for simulating optical appearance of etched tracks in CR-39 nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Nikezic, D.; Yu, K. N.

    2008-04-01

    optical appearances of etched tracks. Solution method: A computer program is prepared to study the optical characteristics of tracks in the CR-39 nuclear track detector using the ray tracing method. Based on geometrical optics, light propagation through the tracks is simulated and the brightness of all grid elements in the track wall is calculated. Additional comments: The program distribution file contains an executable which enables the program to be run on a Windows machine. The source code is also provided, but in order to build an executable the MSFLIB must be available. Running time: Running time depends mainly on the resolution (number of grid elements in the track wall) required by the user. Running time is normally less than 1 min.

  7. Adaptation of the C.H.A.D. computer library to nuclear simulations

    NASA Astrophysics Data System (ADS)

    Rock, Daniel Thomas

    The Computational Hydrodynamics for Automotive Design computer program, CHAD, is a modern, three-dimensional computational fluid dynamics code that holds promise for fulfilling a need in the nuclear industry and academia. Because CHAD may be freely distributed to non export controlled countries, it offers a cheap and customizable CFD capability. Several modifications were made to CHAD to make it more usable to those in industry and academia. A first order up-winding scheme for momentum and enthalpy and a reformulated continuity equation were migrated from a historical version of CHAD developed at Argonne National Laboratory. The Portable, Extensible Toolkit for Scientific Computing, PETSc, was also added as an optional solver package for the original and reformulated continuity equations. PETSc's highly optimized parallel solvers can be activated from either CHAD's input file or the command line. Solution times for PETSc based calculations depend in large part on convergence criteria provided, however improvements in CPU time of approximately one-third have been observed. CHAD was further extended by adding a capability to monitor solution progress by specifying a coordinate in space, as well as monitoring the residuals in the problem. The ability to model incompressible fluids was also added to the code. Incompressible fluid comparisons were made using several test cases against the commercial CFD code Fluent and found to agree well. A major limitation of CHAD in the academic environment is a limited mesh generation capability. A tool for CHAD was developed that translates Gambit based neutral mesh files into a CHAD usable format. This tool was used to translate a large mesh representing a simplified cooling jacket of a BWR control rod drive. This model serves as a practical, demonstration application of a nuclear application for CHAD and PETSc. Both CHAD with PETSc and Fluent were used to obtain solutions to this problem. The overall agreement between the two

  8. Thermal Analysis of Surrogate Simulated Molten Salts with Metal Chloride Impurities for Electrorefining Used Nuclear Fuel

    SciTech Connect

    Toni Y. Gutknecht; Guy L. Fredrickson; Vivek Utgikar

    2012-04-01

    This project is a fundamental study to measure thermal properties (liquidus, solidus, phase transformation, and enthalpy) of molten salt systems of interest to electrorefining operations, which are used in both the fuel cycle research & development mission and the spent fuel treatment mission of the Department of Energy. During electrorefining operations the electrolyte accumulates elements more active than uranium (transuranics, fission products and bond sodium). The accumulation needs to be closely monitored because the thermal properties of the electrolyte will change as the concentration of the impurities increases. During electrorefining (processing techniques used at the Idaho National Laboratory to separate uranium from spent nuclear fuel) it is important for the electrolyte to remain in a homogeneous liquid phase for operational safeguard and criticality reasons. The phase stability of molten salts in an electrorefiner may be adversely affected by the buildup of fission products in the electrolyte. Potential situations that need to be avoided are: (i) build up of fissile elements in the salt approaching the criticality limits specified for the vessel (ii) freezing of the salts due to change in the liquidus temperature and (iii) phase separation (non-homogenous solution) of elements. The stability (and homogeneity) of the phases can potentially be monitored through the thermal characterization of the salts, which can be a function of impurity concentration. This work describes the experimental results of typical salts compositions, consisting of chlorides of strontium, samarium, praseodymium, lanthanum, barium, cerium, cesium, neodymium, sodium and gadolinium (as a surrogate for both uranium and plutonium), used in the processing of used nuclear fuels. Differential scanning calorimetry was used to analyze numerous salt samples providing results on the thermal properties. The property of most interest to pyroprocessing is the liquidus temperature. It was

  9. Simulation-based diagnostics and control for nuclear power plants. Final report, April 15, 1992--April 14, 1995

    SciTech Connect

    Lee, J.C.

    1995-07-01

    The objective of the project was to develop and test a simulation-based diagnostics and control guidance system that can be used to diagnose and manage off-normal transient events in nuclear power plants. The research has focused on developing two diagnostic approaches suitable for detection and identification of faults involving multiple components, subject to uncertainties in system modeling and observations. The first approach is based on a fuzzy logic framework that can diagnose binary failures using a single-failure diagnostic knowledge base. Construction of the binary-failure knowledge base is accomplished through the use of macroscopic conservation relationships and a fuzzy inference structure is developed to determine the magnitude of faults and the associated certainty. In the second diagnostic approach, an adaptive Kalman filter algorithm is derived to yield information on the type and magnitude of feasible component transitions that can account for system observations. To obtain the likelihood of feasible component failures or degradations, a general probabilistic formulation is developed where statistical distributions associated with component reliability data are explicitly represented. Testing of the diagnostic algorithms has been performed through the analysis of simulated transient events for light water reactor systems. Preliminary studies have been conducted to develop Monte Carlo algorithms for flexible control of transient events.

  10. Results From an International Simulation Study on Couples Thermal, Hydrological, and Mechanical (THM) Processes Near Geological Nuclear Waste Repositories

    SciTech Connect

    J. Rutqvist; D. Barr; J.T. Birkholzer; M. Chijimatsu; O. Kolditz; Q. Liu; Y. Oda; W. Wang; C. Zhang

    2006-08-02

    As part of the ongoing international DECOVALEX project, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near waste emplacement drifts of geological nuclear waste repositories. The simulations were conducted for two generic repository types, one with open and the other with back-filled repository drifts, under higher and lower postclosure temperatures, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses is currently being resolved. In particular, good agreement in the basic thermal-mechanical responses was achieved for both repository types, even though some teams used relatively simplified thermal-elastic heat-conduction models that neglected complex near-field thermal-hydrological processes. The good agreement between the complex and simplified process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level.

  11. CFD Simulations of a Flow Mixing and Heat Transfer Enhancement in an Advanced LWR Nuclear Fuel Assembly

    SciTech Connect

    In, Wang-Kee; Chun, Tae-Hyun; Shin, Chang-Hwan; Oh, Dong-Seok

    2007-07-01

    A computational fluid dynamics (CFD) analysis has been performed to investigate a flow-mixing and heat-transfer enhancement caused by a mixing-vane spacer in a LWR fuel assembly which is a rod bundle. This paper presents the CFD simulations of a flow mixing and heat transfer in a fully heated 5x5 array of a rod bundle with a split-vane and hybrid-vane spacer. The CFD prediction at a low Reynolds number of 42,000 showed a reasonably good agreement of the initial heat transfer enhancement with the measured one for a partially heated experiment using a similar spacer structure. The CFD simulation also predicted the decay rate of a normalized Nusselt number downstream of the split-vane spacer which agrees fairly well with those of the experiment and the correlation. The CFD calculations for the split vane and hybrid vane at the LWR operating conditions(Re = 500,000) predicted hot fuel spots in a streaky structure downstream of the spacer, which occurs due to the secondary flow occurring in an opposite direction near the fuel rod. However, the split-vane and hybrid-vane spacers are predicted to significantly enhance the overall heat transfer of a LWR nuclear fuel assembly. (authors)

  12. Simulated acid rain reduces the susceptibility of the European pine sawfly (Neodiprion sertifer) to its nuclear polyhedrosis virus.

    PubMed

    Neuvonen, S; Saikkonen, K; Haukioja, E

    1990-06-01

    The study dealt with the effect of simulated acid rain (both H(2)SO(4) and HNO(3); acidities of pH 4 and pH 3) on the susceptibility of the larvae of Neodiprion sertifer to its nuclear polyhedrosis virus. Scots pines growing in a subarctic area with low ambient pollution levels were irrigated with simulated acid rain during two summers. Neodiprion larvae fed with foliage from the experimental trees were infected with a dilute virus suspension. The acid treatment of host trees had a significant effect on the proportion of virus-treated larvae alive 16 days after the virus application: there were almost no differences between the controls and the pH 4 irrigation group, but on the needles of pH 3-treated trees larval survival was twice as high as with other treatments. The direct spraying of acid water on the needles before they were fed to the larvae did not significantly affect the survival of virus infected larvae. Our results suggest that acid rain may reduce the susceptibility of Neodiprion larvae to virus disease via changes in the quality of pine foliage.

  13. A comparative simulation study of coupled THM processes and their effect on fractured rock permeability around nuclear waste repositories

    SciTech Connect

    Rutqvist, Jonny; Barr, Deborah; Birkholzer, Jens T.; Fujisaki, Kiyoshi; Kolditz, Olf; Liu, Quan-Shen; Fujita, tomoo; Wang, Wenqing; Zhang, Cheng-Yuan

    2008-10-23

    This paper presents an international, multiple-code, simulation study of coupled thermal, hydrological, and mechanical (THM) processes and their effect on permeability and fluid flow in fractured rock around heated underground nuclear waste emplacement drifts. Simulations were conducted considering two types of repository settings: (a) open emplacement drifts in relatively shallow unsaturated volcanic rock, and (b) backfilled emplacement drifts in deeper saturated crystalline rock. The results showed that for the two assumed repository settings, the dominant mechanism of changes in rock permeability was thermal-mechanically-induced closure (reduced aperture) of vertical fractures, caused by thermal stress resulting from repository-wide heating of the rock mass. The magnitude of thermal-mechanically-induced changes in permeability was more substantial in the case of an emplacement drift located in a relatively shallow, low-stress environment where the rock is more compliant, allowing more substantial fracture closure during thermal stressing. However, in both of the assumed repository settings in this study, the thermal-mechanically-induced changes in permeability caused relatively small changes in the flow field, with most changes occurring in the vicinity of the emplacement drifts.

  14. A nuclear training simulator implementing a capability for multiple, concurrent-training sessions

    SciTech Connect

    Groeneveld, B.J.; Nannister, D.G.; Estes, K.R.; Johnsen, M.R.

    1996-02-01

    The Advanced Test Reactor (ATR) Simulator at the Test Reactor Area of the Idaho National Engineering Laboratory (INEL) has recently been upgraded to reflect plant installation of a distributed control system (DCS). The ATR Simulator re-design implements traditional needs for software extensibility and plant installation prototyping, but the driving force behind its new design was an instruction requirement for multiple, concurrent-training sessions. Support is provided for up to three concurrent, independent or interacting, training sessions of reactor, balance of plant, and experiment loop operators. This capability has been achieved by modifying the existing design to consistently apply client-server, parent-child, and peer-to-peer processing technologies, and then to encapsulate concurrency software into all interfaces. When the resulting component-oriented design is linked with build and runtime flexibility in a distributed computing environment, traditional needs for extensibility and parallel software and scenario development are satisfied with minimal additional effort. Sensible configuration management practices coupled with the ability to perform piecewise system builds also greatly facilitate prototyping of plant changes prior to installation.

  15. FORMATION OF ULTRA-COMPACT BLUE DWARF GALAXIES AND THEIR EVOLUTION INTO NUCLEATED DWARFS

    SciTech Connect

    Bekki, Kenji

    2015-10-10

    We propose that there is an evolutionary link between ultra-compact blue dwarf galaxies (UCBDs) with active star formation and nucleated dwarfs based on the results of numerical simulations of dwarf–dwarf merging. We consider the observational fact that low-mass dwarfs can be very gas-rich, and thereby investigate the dynamical and chemical evolution of very gas-rich, dissipative dwarf–dwarf mergers. We find that the remnants of dwarf–dwarf mergers can be dominated by new stellar populations formed from the triggered starbursts and consequently can have blue colors and higher metallicities (Z ∼ [0.2–1]Z{sub ⊙}). We also find that the remnants of these mergers can have rather high mass densities (10{sup 4} M{sub ⊙} pc{sup −3}) within the central 10 pc and small half-light radii (40−100 pc). The radial stellar structures of some merger remnants are similar to those of nucleated dwarfs. Star formation can continue in nuclear gas disks (R < 100 pc) surrounding stellar galactic nuclei (SGNs) so that the SGNs can finally have multiple stellar populations with different ages and metallicities. These very compact blue remnants can be identified as UCBDs soon after merging and as nucleated dwarfs after the young stars fade. We discuss these results in the context of the origins of metal-rich ultra-compact dwarfs and SGNs.

  16. Nuclear power: Fourth edition

    SciTech Connect

    Deutsch, R.W.

    1986-01-01

    This book describes the basics of nuclear power generation, explaining both the benefits and the real and imagined risks of nuclear power. It includes a discussion of the Three Mile Island accident and its effects. Nuclear Power has been used in the public information programs of more than 100 utilities. The contents discussed are: Nuclear Power and People; Why Nuclear Power. Electricity produced by coal; Electricity produced by nuclear fuel; Nuclear plant sites in the United States; Short History of Commercial Nuclear Power; U.S. nuclear submarines, Regulation of Nuclear Power Plants; Licensing process, Nuclear Power Plant Operator Training; Nuclear power plant simulator, Are Nuclear Plants Safe.; Containment structure, Nuclear Power Plant Insurance; Is Radiation Dangerous.; Man-made radiation, What is Nuclear Fuel.; Fuel cycle for commercial nuclear power plants; Warm Water Discharge; Cooling tower; Protection of Radioactive Materials; Plutonium and Proliferation; Disposal of Radioactive Wastes; Are Alternate Energy Sources Available.; Nuclear Opposition; and Nuclear Power in the Future.

  17. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device

    PubMed Central

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C.; Marino, Stephen A.; Geard, Charles R.; Brenner, David J.; Garty, Guy

    2015-01-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  18. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  19. Fretting wear behaviors of a dual-cooled nuclear fuel rod under a simulated rod vibration

    SciTech Connect

    Lee, Young-Ho; Kim, Hyung-Kyu; Kang, Heung-Seok; Yoon, Kyung-Ho; Kim, Jae-Yong; Lee, Kang-Hee

    2012-06-06

    Recently, a dual-cooled fuel (i.e., annular fuel) that is compatible with current operating PWR plants has been proposed in order to realize both a considerable amount of power uprating and an increase of safety margins. As the design concept should be compatible with current operating PWR plants, however, it shows a narrow gap between the fuel rods when compared with current solid nuclear fuel arrays and needs to modify the spacer grid shapes and their positions. In this study, fretting wear tests have been performed to evaluate the wear resistance of a dual-cooled fuel by using a proposed spring and dimple of spacer grids that have a cantilever type and hemispherical shape, respectively. As a result, the wear volume of the spring specimen gradually increases as the contact condition is changed from a certain gap, just contact to positive force. However, in the dimple specimen, just contact condition shows a large wear volume. In addition, a circular rod motion at upper region of contact surface is gradually increased and its diametric size depends on the wear depth increase. Based on the test results, the fretting wear resistance of the proposed spring and dimple is analyzed by comparing the wear measurement results and rod motion in detail.

  20. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields.

  1. Fretting wear behaviors of a dual-cooled nuclear fuel rod under a simulated rod vibration

    NASA Astrophysics Data System (ADS)

    Lee, Young-Ho; Kim, Hyung-Kyu; Kang, Heung-Seok; Yoon, Kyung-Ho; Kim, Jae-Yong; Lee, Kang-Hee

    2012-06-01

    Recently, a dual-cooled fuel (i.e., annular fuel) that is compatible with current operating PWR plants has been proposed in order to realize both a considerable amount of power uprating and an increase of safety margins. As the design concept should be compatible with current operating PWR plants, however, it shows a narrow gap between the fuel rods when compared with current solid nuclear fuel arrays and needs to modify the spacer grid shapes and their positions. In this study, fretting wear tests have been performed to evaluate the wear resistance of a dual-cooled fuel by using a proposed spring and dimple of spacer grids that have a cantilever type and hemispherical shape, respectively. As a result, the wear volume of the spring specimen gradually increases as the contact condition is changed from a certain gap, just contact to positive force. However, in the dimple specimen, just contact condition shows a large wear volume. In addition, a circular rod motion at upper region of contact surface is gradually increased and its diametric size depends on the wear depth increase. Based on the test results, the fretting wear resistance of the proposed spring and dimple is analyzed by comparing the wear measurement results and rod motion in detail.

  2. Nuclear and particle astrophysics

    SciTech Connect

    Glendenning, N.K.

    1990-10-31

    We discuss the physics of matter that is relevant to the structure of compact stars. This includes nuclear, neutron star matter and quark matter and phase transitions between them. Many aspects of neutron star structure and its dependance on a number of physical assumptions about nuclear matter properties and hyperon couplings are investigated. We also discuss the prospects for obtaining constraints on the equation of state from astrophysical sources. Neuron star masses although few are known at present, provide a very direct constraint in as much as the connection to the equation of state involves only the assumption that Einstein's general of theory of relativity is correct at the macroscopic scale. Supernovae simulations involve such a plethora of physical processes including those involved in the evolution of the precollapse configuration, not all of them known or understood, that they provide no constraint at the present time. Indeed the prompt explosion, from which a constraint had been thought to follow, is now believed not to be mechanism by which most, if any stars, explode. In any case the nuclear equation of state is but one of a multitude on uncertain factors, and possibly one of the least important. The rapid rotation of pulsars is also discussed. It is shown that for periods below a certain limit it becomes increasingly difficult to reconcile them with neutron stars. Strange stars are possible if strange matter is the absolute ground state. We discuss such stars and their compatibility with observation. 112 refs., 37 figs., 6 tabs.

  3. Effect of Callovo-Oxfordian clay rock on the dissolution rate of the SON68 simulated nuclear waste glass

    NASA Astrophysics Data System (ADS)

    Neeway, James J.; Abdelouas, Abdesselam; Ribet, Solange; El Mendili, Yassine; Schumacher, Stéphan; Grambow, Bernd

    2015-04-01

    Long-term storage of high-level nuclear waste glass in France is expected to occur in an engineered barrier system (EBS) located in a subsurface Callovo-Oxfordian (COx) clay rock formation in the Paris Basin in northeastern France. Understanding the behavior of glass dissolution in the complex system is critical to be able to reliably model the performance of the glass in this complex environment. To simulate this multi-barrier repository scenario in the laboratory, several tests have been performed to measure glass dissolution rates of the simulated high-level nuclear waste glass, SON68, in the presence of COx claystone at 90 °C. Experiments utilized a High-Performance Liquid Chromatography (HPLC) pump to pass simulated Bure site COx pore water through a reaction cell containing SON68 placed between two COx claystone cores for durations up to 200 days. Silicon concentrations at the outlet were similar in all experiments, even the blank experiment with only the COx claystone (∼4 mg/L at 25 °C and ∼15 mg/L at 90 °C). The steady-state pH of the effluent, measured at room temperature, was roughly 7.1 for the blank and 7.3-7.6 for the glass-containing experiments demonstrating the pH buffering capacity of the COx claystone. Dissolution rates for SON68 in the presence of the claystone were elevated compared to those obtained from flow-through experiments conducted with SON68 without claystone in silica-saturated solutions at the same temperature and similar pH values. Additionally, through surface examination of the monoliths, the side of the monolith in direct contact with the claystone was seen to have a corrosion thickness 2.5× greater than the side in contact with the bulk glass powder. Results from one experiment containing 32Si-doped SON68 also suggest that the movement of Si through the claystone is controlled by a chemically coupled transport with a Si retention factor, Kd, of 900 mL/g.

  4. Status on the Development of a Modeling and Simulation Framework for the Economic Assessment of Nuclear Hybrid Energy Systems

    SciTech Connect

    Bragg-Sitton, Shannon Michelle; Rabiti, Cristian; Kinoshita, Robert Arthur; Kim, Jong Suk; Deason, Wesley Ray; Boardman, Richard Doin; Garcia, Humberto E.

    2015-09-01

    An effort to design and build a modeling and simulation framework to assess the economic viability of Nuclear Hybrid Energy Systems (NHES) was undertaken in fiscal year 2015 (FY15). The purpose of this report is to document the various tasks associated with the development of such a framework and to provide a status on its progress. Several tasks have been accomplished. First, starting from a simulation strategy, a rigorous mathematical formulation has been achieved in which the economic optimization of a Nuclear Hybrid Energy System is presented as a constrained robust (under uncertainty) optimization problem. Some possible algorithms for the solution of the optimization problem are presented. A variation of the Simultaneous Perturbation Stochastic Approximation algorithm has been implemented in RAVEN and preliminary tests have been performed. The development of the software infrastructure to support the simulation of the whole NHES has also moved forward. The coupling between RAVEN and an implementation of the Modelica language (OpenModelica) has been implemented, migrated under several operating systems and tested using an adapted model of a desalination plant. In particular, this exercise was focused on testing the coupling of the different code systems; testing parallel, computationally expensive simulations on the INL cluster; and providing a proof of concept for the possibility of using surrogate models to represent the different NHES subsystems. Another important step was the porting of the RAVEN code under the Windows™ operating system. This accomplishment makes RAVEN compatible with the development environment that is being used for dynamic simulation of NHES components. A very simplified model of a NHES on the electric market has been built in RAVEN to confirm expectations on the analysis capability of RAVEN to provide insight into system economics and to test the capability of RAVEN to identify limit surfaces even for stochastic constraints. This

  5. Removal of pertechnetate from simulated nuclear waste streams using supported zerovalent iron

    SciTech Connect

    Darab, John; Amonette, Alexandra; Burke, Deborah; Orr, Robert; Ponder, Sherman; Schrick, Bettina; Mallouk, Thomas; Lukens, Wayne; Caulder, Dana; Shuh, David

    2007-07-11

    The application of nanoparticles of predominantly zerovalent iron (nanoiron), either unsupported or supported, to the separation and reduction of pertechnetate anions (TcO4-) from complex waste mixtures was investigated as an alternative approach to current waste-processing schemes. Although applicable to pertechnetate-containing waste streams in general, the research discussed here was directed at two specific potential applications at the U.S. Department of Energy's Hanford Site: (1) the direct removal of pertechnetate from highly alkaline solutions, typical of those found in Hanford tank waste, and (2) the removal of dilute pertechnetate from near-neutral solutions, typical of the eluate streams from commercial organic ion-exchange resins that may be used to remediate Hanford tank wastes. It was envisioned that both applications would involve the subsequent encapsulation of the loaded sorbent material into a separate waste form. A high surface area (>200 M2/g) base-stable, nanocrystalline zirconia was used as a support for nanoiron for tests with highly alkaline solutions, while a silica gel support was used for tests with near-neutral solutions. It was shown that after 24 h of contact time, the high surface area zirconia supported nanoiron sorbent removed about 50percent (K-d = 370 L/kg) of the pertechnetate from a pH 14 tank waste simulant containing 0.51 mM TCO4- and large concentrations of Na+, OH-, NO3-, and CO32- for a phase ratio of 360 L simulant per kg of sorbent. It was also shown that after 18 h of contact time, the silica-supported nanoiron removed>95percent pertechnetate from a neutral pH eluate simulant containing 0.076 mM TcO4_ for a phase ratio of 290 L/kg. It was determined that in all cases, nanoiron reduced the Tc(VII) to Tc(IV), or possibly to Tc(V), through a redox reaction. Finally, it was demonstrated that a mixture of 20 mass percent of the solid reaction products obtained from contacting zirconia- supported nanoiron with an alkaline

  6. Challenge problem and milestones for : Nuclear Energy Advanced Modeling and Simulation (NEAMS) waste Integrated Performance and Safety Codes (IPSC).

    SciTech Connect

    Freeze, Geoffrey A.; Wang, Yifeng; Howard, Robert; McNeish, Jerry A.; Schultz, Peter Andrew; Arguello, Jose Guadalupe, Jr.

    2010-09-01

    This report describes the specification of a challenge problem and associated challenge milestones for the Waste Integrated Performance and Safety Codes (IPSC) supporting the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The NEAMS challenge problems are designed to demonstrate proof of concept and progress towards IPSC goals. The goal of the Waste IPSC is to develop an integrated suite of modeling and simulation capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive waste storage or disposal system. The Waste IPSC will provide this simulation capability (1) for a range of disposal concepts, waste form types, engineered repository designs, and geologic settings, (2) for a range of time scales and distances, (3) with appropriate consideration of the inherent uncertainties, and (4) in accordance with robust verification, validation, and software quality requirements. To demonstrate proof of concept and progress towards these goals and requirements, a Waste IPSC challenge problem is specified that includes coupled thermal-hydrologic-chemical-mechanical (THCM) processes that describe (1) the degradation of a borosilicate glass waste form and the corresponding mobilization of radionuclides (i.e., the processes that produce the radionuclide source term), (2) the associated near-field physical and chemical environment for waste emplacement within a salt formation, and (3) radionuclide transport in the near field (i.e., through the engineered components - waste form, waste package, and backfill - and the immediately adjacent salt). The initial details of a set of challenge milestones that collectively comprise the full challenge problem are also specified.

  7. Mitotic chromosome compaction via active loop extrusion

    NASA Astrophysics Data System (ADS)

    Goloborodko, Anton; Imakaev, Maxim; Marko, John; Mirny, Leonid; MIT-Northwestern Team

    During cell division, two copies of each chromosome are segregated from each other and compacted more than hundred-fold into the canonical X-shaped structures. According to earlier microscopic observations and the recent Hi-C study, chromosomes are compacted into arrays of consecutive loops of ~100 kilobases. Mechanisms that lead to formation of such loop arrays are largely unknown. Here we propose that, during cell division, chromosomes can be compacted by enzymes that extrude loops on chromatin fibers. First, we use computer simulations and analytical modeling to show that a system of loop-extruding enzymes on a chromatin fiber self-organizes into an array of consecutive dynamic loops. Second, we model the process of loop extrusion in 3D and show that, coupled with the topo II strand-passing activity, it leads to robust compaction and segregation of sister chromatids. This mechanism of chromosomal condensation and segregation does not require additional proteins or specific DNA markup and is robust against variations in the number and properties of such loop extruding enzymes. Work at NU was supported by the NSF through Grants DMR-1206868 and MCB-1022117, and by the NIH through Grants GM105847 and CA193419. Work at MIT was supported by the NIH through Grants GM114190 R01HG003143.

  8. Compact gate valve

    DOEpatents

    Bobo, Gerald E.

    1977-01-01

    This invention relates to a double-disc gate valve which is compact, comparatively simple to construct, and capable of maintaining high closing pressures on the valve discs with low frictional forces. The valve casing includes axially aligned ports. Mounted in the casing is a sealed chamber which is pivotable transversely of the axis of the ports. The chamber contains the levers for moving the valve discs axially, and an actuator for the levers. When an external drive means pivots the chamber to a position where the discs are between the ports and axially aligned therewith, the actuator for the levers is energized to move the discs into sealing engagement with the ports.

  9. COMPACT CASCADE IMPACTS

    DOEpatents

    Lippmann, M.

    1964-04-01

    A cascade particle impactor capable of collecting particles and distributing them according to size is described. In addition the device is capable of collecting on a pair of slides a series of different samples so that less time is required for the changing of slides. Other features of the device are its compactness and its ruggedness making it useful under field conditions. Essentially the unit consists of a main body with a series of transverse jets discharging on a pair of parallel, spaced glass plates. The plates are capable of being moved incremental in steps to obtain the multiple samples. (AEC)

  10. Compact laser amplifier system

    DOEpatents

    Carr, R.B.

    1974-02-26

    A compact laser amplifier system is described in which a plurality of face-pumped annular disks, aligned along a common axis, independently radially amplify a stimulating light pulse. Partially reflective or lasing means, coaxially positioned at the center of each annualar disk, radially deflects a stimulating light directed down the common axis uniformly into each disk for amplification, such that the light is amplified by the disks in a parallel manner. Circumferential reflecting means coaxially disposed around each disk directs amplified light emission, either toward a common point or in a common direction. (Official Gazette)

  11. Compact Q-balls

    NASA Astrophysics Data System (ADS)

    Bazeia, D.; Losano, L.; Marques, M. A.; Menezes, R.; da Rocha, R.

    2016-07-01

    In this work we deal with non-topological solutions of the Q-ball type in two space-time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  12. Compact Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2004-01-01

    A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

  13. High-altitude-nuclear electromagnetic pulse (HEMP) environment simulation public health and safety considerations. Technical report, 1 Oct 89-31 May 91

    SciTech Connect

    Casey, K.

    1992-03-01

    The existence of electromagnetic fields external to the working volumes of high-altitude nuclear electromagnetic pulse (HEMP) environment simulators has raised both environmental and public-health concerns regarding the safety of HEMP environment simulator operations. This report contains a review of what HEMP is, what its effects on defense systems are, and why and how HEMP environment simulation testing is conducted. The state of present knowledge concerning the external simulator fields and their possible effects on biological and electronic systems is summarized. Research initiatives are identified to aid in answering the most important questions regarding the continued environmental safety of HEMP simulator operations. These initiatives are intended to support (1) development of options for modification and/or relocation of HEMP environment simulator facilities and (2) determination of safe exposure levels for biological and electronic systems. Recommendations for specific DoD actions are given.

  14. Molecular Dynamics Simulations of Aqueous and Confined Systems Relevant to the Supercritical Water Cooled Nuclear Reactor

    NASA Astrophysics Data System (ADS)

    Kallikragas, Dimitrios Theofanis

    Supercritical water (SCW) is the intended heat transfer fluid and potential neutron moderator in the proposed GEN-IV Supercritical Water Cooled Reactor (SCWR). The oxidative environment poses challenges in choosing appropriate design materials, and the behaviour of SCW within crevices of the passivation layer is needed for developing a corrosion control strategy to minimize corrosion. Molecular Dynamics simulations have been employed to obtain diffusion coefficients, coordination number and surface density characteristics, of water and chloride in nanometer-spaced iron hydroxide surfaces. Diffusion models for hydrazine are evaluated along with hydration data. Results demonstrate that water is more likely to accumulate on the surface at low density conditions. The effect of confinement on the water structure diminishes as the gap size increases. The diffusion coefficient of chloride decreases with larger surface spacing. Clustering of water at the surface implies that the SCWR will be most susceptible to pitting corrosion and stress corrosion cracking.

  15. A Global Approach to the Physics Validation of Simulation Codes for Future Nuclear Systems

    SciTech Connect

    Giuseppe Palmiotti; Massimo Salvatores; Gerardo Aliberti; Hikarui Hiruta; R. McKnight; P. Oblozinsky; W. S. Yang

    2008-09-01

    This paper presents a global approach to the validation of the parameters that enter into the neutronics simulation tools for advanced fast reactors with the objective to reduce the uncertainties associated to crucial design parameters. This global approach makes use of sensitivity/uncertainty methods; statistical data adjustments; integral experiment selection, analysis and “representativity” quantification with respect to a reference system; scientifically based cross section covariance data and appropriate methods for their use in multigroup calculations. This global approach has been applied to the uncertainty reduction on the criticality of the Advanced Burner Reactor, (both metal and oxide core versions) presently investigated in the frame of the GNEP initiative. The results obtained are very encouraging and allow to indicate some possible improvements of the ENDF/B-VII data file.

  16. Extension of the CENTAR system simulation code to thermionic space nuclear reactors

    NASA Astrophysics Data System (ADS)

    Nassersharif, Bahram; Gaeta, Michael J.; Berge, Francoise; Guffee, Laura; Williams, Ken

    The Code for Extended Nonlinear Transient Analysis of Extraterrestial Reactors (CENTAR) is a general-purpose reactor system simulation code capable of modeling coupled heat transfer, fluid flow, neutronic, and control in an arbitrary reactor system (or subsystem) configuration. CENTAR 4.0 has been enhanced to support thermionic solid-core systems as well as liquid-metal systems. Several new models have been added. The fuel model has been enhanced to support two-dimensional heat transfer with multiple material gap interfaces. Gaps may contain thermionic converters. A quasi-steady-state heat-pipe component model has been added to predict operating limits. The thermoelectric/electromagnetic (TEM) pump model in CENTAR has been extended to also model electromagnetic pumps. A thermionic energy conversion model has been added. Numerous other enhancements to code architecture, user interface, and I/O have also been added in version 4.0.

  17. Simulation study into the identification of nuclear materials in cargo containers using cosmic rays

    NASA Astrophysics Data System (ADS)

    Blackwell, T. B.; Kudryavtsev, V. A.

    2015-04-01

    Muon tomography represents a new type of imaging technique that can be used in detecting high-Z materials. Monte Carlo simulations for muon scattering in different types of target materials are presented. The dependence of the detector capability to identify high-Z targets on spatial resolution has been studied. Muon tracks are reconstructed using a basic point of closest approach (PoCA) algorithm. In this article we report the development of a secondary analysis algorithm that is applied to the reconstructed PoCA points. This algorithm efficiently ascertains clusters of voxels with high average scattering angles to identify `areas of interest' within the inspected volume. Using this approach the effect of other parameters, such as the distance between detectors and the number of detectors per set, on material identification is also presented. Finally, false positive and false negative rates for detecting shielded HEU in realistic scenarios with low-Z clutter are presented.

  18. Folded Compact Range Development and Coherent Change Detection Measurement Project

    SciTech Connect

    Sorensen, K.W.

    1995-03-01

    A novel, folded compact range configuration has been developed at the Sandia National Laboratories compact range antenna and radar cross section measurement facility, operated by the Radar/Antenna Department 2343, as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) coherent change detection (CCD) measurements. This report describes the development of the folded compact range configuration, as well as the initial set of coherent change detection measurements made with the system. These measurements have been highly successful, and have demonstrated the viability of the folded compact range concept in simulating SAR CCD measurements. It is felt that follow-on measurements have the potential of contributing significantly to the body of knowledge available to the scientific community involved in CCD image generation and processing, and that this tool will be a significant aid in the research and development of change detection methodologies.

  19. Simulating consciousness in a bilateral neural network: "nuclear" and "fringe" awareness.

    PubMed

    Cook, N D

    1999-03-01

    A technique for the bilateral activation of neural nets that leads to a functional asymmetry of two simulated "cerebral hemispheres" is described. The simulation is designed to perform object recognition, while exhibiting characteristics typical of human consciousness-specifically, the unitary nature of conscious attention, together with a dual awareness corresponding to the "nucleus" and "fringe" described by William James (1890). Sensory neural nets self-organize on the basis of five sensory features. The system is then taught arbitrary symbolic labels for a small number of similar stimuli. Finally, the trained network is exposed to nonverbal stimuli for object recognition, leading to Gaussian activation of the "sensory" maps-with a peak at the location most closely related to the features of the external stimulus. "Verbal" maps are activated most strongly at the labeled location that lies closest to the peak on homologous sensory maps. On the verbal maps activation is characterized by both excitatory and inhibitory Gaussians (a Mexican hat), the parameters of which are determined by the relative locations of the verbal labels. Mutual homotopic inhibition across the "corpus callosum" then produces functional cerebral asymmetries, i.e., complementary activation of homologous "association" and "frontal" maps within a common focus of attention-a nucleus in the left hemisphere and a fringe in the right hemisphere. An object is recognized as corresponding to a known label when the total activation of both hemispheres (nucleus plus fringe) is strongest for that label. The functional dualities of the cerebral hemispheres are discussed in light of the nucleus/fringe asymmetry.

  20. SGC tests for influence of material composition on compaction characteristic of asphalt mixtures.

    PubMed

    Chen, Qun; Li, Yuzhi

    2013-01-01

    Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture) was studied using Superpave gyratory compactor (SGC) simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is an optimal amount of fine aggregates for optimal compaction and that an appropriate amount of mineral powder will improve workability of mixtures, but overmuch mineral powder will make mixtures dry and hard. Conclusions based on SGC tests can provide basis for how to adjust material composition for improving compaction performance of asphalt mixtures, and for the designed asphalt mixture, its compaction performance can be predicted through these conclusions, which also contributes to the choice of compaction schemes. PMID:23818830