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Sample records for kyoto university critical assembly reactor

  1. Positron beam facility at Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Xu, Q.; Sato, K.; Yoshiie, T.; Sano, T.; Kawabe, H.; Nagai, Y.; Nagumo, K.; Inoue, K.; Toyama, T.; Oshima, N.; Kinomura, A.; Shirai, Y.

    2014-04-01

    A positron beam facility is presently under construction at the Kyoto University Research Reactor (KUR), which is a light-water moderated tank-type reactor operated at a rated thermal power of 5 MW. A cadmium (Cd) - tungsten (W) source similar to that used in NEPOMUC was chosen in the KUR because Cd is very efficient at producing γ-rays when exposed to thermal neutron flux, and W is a widely used in converter and moderator materials. High-energy positrons are moderated by a W moderator with a mesh structure. Electrical lenses and a solenoid magnetic field are used to extract the moderated positrons and guide them to a platform outside of the reactor, respectively. Since Japan is an earthquake-prone country, a special attention is paid for the design of the in-pile positron source so as not to damage the reactor in the severe earthquake.

  2. A new materials irradiation facility at the Kyoto university reactor

    NASA Astrophysics Data System (ADS)

    Yoshiie, T.; Hayashi, Y.; Yanagita, S.; Xu, Q.; Satoh, Y.; Tsujimoto, H.; Kozuka, T.; Kamae, K.; Mishima, K.; Shiroya, S.; Kobayashi, K.; Utsuro, M.; Fujita, Y.

    2003-02-01

    A new materials irradiation facility with improved control capabilities has been installed at the Kyoto University Reactor (KUR). Several deficiencies of conventional fission neutron material irradiation systems have been corrected. The specimen temperature is controlled both by an electric heater and by the helium pressure in the irradiation tube without exposure to neutrons at temperatures different from the design test conditions. The neutron spectrum is varied by the irradiation position. Irradiation dose is changed by pulling the irradiation capsule up and down during irradiation. Several characteristics of the irradiation field were measured. The typical irradiation intensity is 9.4×10 12 n/cm 2 s (>0.1 MeV) and the irradiation temperature of specimens is controllable from 363 to 773 K with a precision of ±2 K.

  3. Improvement of low-temperature irradiation facility at Kyoto University Reactor (KUR)

    NASA Astrophysics Data System (ADS)

    Okada, M.; Kanazawa, S.; Nozaki, T.; Nakagawa, M.; Atobe, K.; Kuramoto, E.; Matsumura, K.; Sano, T.

    2001-05-01

    The low-temperature irradiation facility at the Kyoto University Reactor (KUR) has been upgraded. Cryogenic power has been increased from 37 W to about 58 W at 10 K, and irradiation temperature has been reduced from 20 to 12 K at 5 MW reactor operating power. The maximum fast-neutron flux after these improvements is about 4.77×10 11 n/n cm -2 s -1. Therefore, the maximum fluence of fast-neutrons at the KUR facility is about 1.3×10 17 n cm -2 for the maximum operating time of 77 h per week.

  4. Development of a mono-energetic positron beam line at the Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Sato, K.; Xu, Q.; Yoshiie, T.; Sano, T.; Kawabe, H.; Nagai, Y.; Nagumo, K.; Inoue, K.; Toyama, T.; Oshima, N.; Kinomura, A.; Shirai, Y.

    2015-01-01

    Positron beam facilities are widely used for solid state physics and material science studies. A positron beam facility has been constructed at the Kyoto University Research Reactor (KUR) in order to expand its application range. The KUR is a light-water-moderated tank-type reactor operated at a rated thermal power of 5 MW. A positron beam has been transported successfully from the reactor to the irradiation chamber. The total moderated positron rate was greater than 1.4 × 106/s while the reactor operated at a reduced power of 1 MW. Special attention was paid for the design of the in-pile position source to prevent possible damage of the reactor in case of severe earthquakes.

  5. Nickel Mirror And Supermirror Neutron Guide Tubes At The Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Ebisawa, Toru; Akiyoshi, Tsunekazu; Tasaki, Seiji; Kawai, Takeshi; Achiwa, Norio; Utsuro, Masahiko; Okamoto, Sunao

    1989-01-01

    We installed the first nickel mirror neutron guide tube with a characteristic wavelength of 2.85 Å at Kyoto University research reactor(KUR, 5MW, cooled and moderated by light water) in 1973 and a supermirror guide tube with a characteristic wavelength of 1.17 Å in 1984, in order to get more intense thermal neutron beam. Four guide tubes are under construction at a cold neutron source installed in 1986. Two of them are supermirror type with a characteristic wavelength of 3 Å and the others are supermirror and Ni-mirror type with characteristic wavelengths of 6 Å and 23 Å, respectively. Supermirrors are made by automatically controlled vacuum deposition of nickel and titanium metal with electron gun. Their averaging reflectivity for the first supermirror guide tube are the following: The apparent critical wavelength, λ/θ, of reflection is 240 Å in term of wavelength(λ/θ) corresponding to the component of wave number perpendicular to the mirror surface. The reflectivity is 0.65 at the apparent critical wavelength and becomes higher with increasing neutron wavelength up to nearly unity for wavelength longer than 500 Å. Supermirror guide tubes are featured by more available neutrons with larger divergent angles and shorter length of the guide tubes. These features would bring us significant advantages depending on experimental requirements.

  6. Design study of multi-imaging plate system for BNCT irradiation field at Kyoto university reactor.

    PubMed

    Tanaka, Kenichi; Sakurai, Yoshinori; Kajimoto, Tsuyoshi; Tanaka, Hiroki; Takata, Takushi; Endo, Satoru

    2016-09-01

    The converter configuration for a multi-imaging plate system was investigated for the application of quality assurance in the irradiation field profile for boron neutron capture therapy. This was performed by the simulation calculation using the PHITS code in the fields at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. The converter constituents investigated were carbon for gamma rays, and polyethylene with and without LiF at varied (6)Li concentration for thermal, epithermal, and fast neutrons. Consequently, potential combinations of the converters were found for two components, gamma rays and thermal neutrons, for the standard thermal neutron mode and three components of gamma rays, epithermal neutrons, and thermal or fast neutrons, for the standard mixed or epithermal neutron modes, respectively. PMID:27423022

  7. Biomedical irradiation system for boron neutron capture therapy at the Kyoto University Reactor.

    PubMed

    Kobayashi, T; Kanda, K; Ujeno, Y; Ishida, M R

    1990-01-01

    Physics studies related to radiation source, spectroscopy, beam quality, dosimetry, and biomedical applications using the Kyoto University Reactor Heavy Water Facility are described. Also, described are a Nickel Mirror Neutron Guide Tube and a Super Mirror Neutron Guide Tube that are used both for the measurement of boron concentration in phantom and living tissue and for precise measurements of neutron flux in phantom in the presence of both light and heavy water. Discussed are: (1) spectrum measurements using the time of flight technique, (2) the elimination of gamma rays and fast neutrons from a thermal neutron irradiation field, (3) neutron collimation without producing secondary gamma rays, (4) precise neutron flux measurements, dose estimation, and the measurement of boron concentration in tumor and its periphery using guide tubes, (5) the dose estimation of boron-10 for the first melanoma patient, and (6) special-purpose biological irradiation equipment. Other related subjects are also described.

  8. Current Activities of Neutron Imaging Facilities in KUR (Kyoto University Research Reactor)

    NASA Astrophysics Data System (ADS)

    Kawabata, Yuji; Saito, Yasushi

    Kyoto University research Reactor (KUR) restarted in Spring 2010 with low enriched fuel (20%) after 4 years tentative interruption for fuel conversion. There are two facilities for neutron imaging: 1) B4 port at supermirror neutron guide tube (5x107 n/cm2/s at 5 MW, 1 cmx7.5 cm), 2) E2 port (3x105 n/cm2/s at 5 MW, 15 cm dia.). As we have large experimental space at the end of the guide tube and need small shielding because the neutron flux of KUR is not high, we have very large flexibility in the experimental set up. Thus, experiments in B4 should be specialized in the measurements which require large and/or unconventional equipments to accommodate special sample conditions. The E2 port with the low neutron flux is used for experiments which need very long or frequent machine times.

  9. Microdosimetry of neutron field for boron neutron capture therapy at Kyoto university reactor.

    PubMed

    Endo, S; Onizuka, Y; Ishikawa, M; Takada, M; Sakurai, Y; Kobayashi, T; Tanaka, K; Hoshi, M; Shizuma, K

    2004-01-01

    Microdosimetric single event spectrum in a human body simulated by an acrylic phantom has been measured for the clinical BNCT field at the Kyoto University Reactor (KUR). The recoil particles resulting from the initial reaction and subsequent interactions, namely protons, electrons, alpha particles and carbon nuclei are identified in the microdosimetric spectrum. The relative contributions to the neutron dose from proton, alpha particles and carbon are estimated to be about 0.9, 0.07 and 0.3, respectively, four depths between 5 and 41 mm. We estimate that the dose averaged lineal energy, yD decreased with depth from 64 to 46 keV microm(-1). Relative biological effectiveness (RBE) of this neutron field using a response function for the microdosimetric spectrum was estimated to decrease from 3.6 to 2.9 with increasing depth. PMID:15353723

  10. Design study of multi-imaging plate system for BNCT irradiation field at Kyoto university reactor.

    PubMed

    Tanaka, Kenichi; Sakurai, Yoshinori; Kajimoto, Tsuyoshi; Tanaka, Hiroki; Takata, Takushi; Endo, Satoru

    2016-09-01

    The converter configuration for a multi-imaging plate system was investigated for the application of quality assurance in the irradiation field profile for boron neutron capture therapy. This was performed by the simulation calculation using the PHITS code in the fields at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. The converter constituents investigated were carbon for gamma rays, and polyethylene with and without LiF at varied (6)Li concentration for thermal, epithermal, and fast neutrons. Consequently, potential combinations of the converters were found for two components, gamma rays and thermal neutrons, for the standard thermal neutron mode and three components of gamma rays, epithermal neutrons, and thermal or fast neutrons, for the standard mixed or epithermal neutron modes, respectively.

  11. Advances in boron neutron capture therapy (BNCT) at kyoto university - From reactor-based BNCT to accelerator-based BNCT

    NASA Astrophysics Data System (ADS)

    Sakurai, Yoshinori; Tanaka, Hiroki; Takata, Takushi; Fujimoto, Nozomi; Suzuki, Minoru; Masunaga, Shinichiro; Kinashi, Yuko; Kondo, Natsuko; Narabayashi, Masaru; Nakagawa, Yosuke; Watanabe, Tsubasa; Ono, Koji; Maruhashi, Akira

    2015-07-01

    At the Kyoto University Research Reactor Institute (KURRI), a clinical study of boron neutron capture therapy (BNCT) using a neutron irradiation facility installed at the research nuclear reactor has been regularly performed since February 1990. As of November 2014, 510 clinical irradiations were carried out using the reactor-based system. The world's first accelerator-based neutron irradiation system for BNCT clinical irradiation was completed at this institute in early 2009, and the clinical trial using this system was started in 2012. A shift of BCNT from special particle therapy to a general one is now in progress. To promote and support this shift, improvements to the irradiation system, as well as its preparation, and improvements in the physical engineering and the medical physics processes, such as dosimetry systems and quality assurance programs, must be considered. The recent advances in BNCT at KURRI are reported here with a focus on physical engineering and medical physics topics.

  12. Experimental study on the thorium-loaded accelerator-driven system at the Kyoto Univ. critical assembly

    SciTech Connect

    Pyeon, C. H.; Yagi, T.; Lim, J. Y.; Misawa, T.

    2012-07-01

    The experimental study on the thorium-loaded accelerator-driven system (ADS) is conducted in the Kyoto Univ. Critical Assembly (KUCA). The experiments are carried out in both the critical and subcritical states for attaining the reaction rates of the thorium capture and fission reactions. In the critical system, the thorium plate irradiation experiment is carried out for the thorium capture and fission reactions. From the results of the measurements, the thorium fission reactions are obtained apparently in the critical system, and the C/E values of reaction rates show the accuracy of relative difference of about 30%. In the ADS experiments with 14 MeV neutrons and 100 MeV protons, the subcritical experiments are carried out in the thorium-loaded cores to obtain the capture reaction rates through the measurements of {sup 115}In(n, {gamma}){sup 116m}In reactions. The results of the experiments reveal the difference between the reaction rate distributions for the change in not only the neutron spectrum but also the external neutron source. The comparison between the measured and calculated reaction rate distributions demonstrates a discrepancy of the accuracy of reaction rate analyses of thorium capture reactions through the thorium-loaded ADS experiments with 14 MeV neutrons. Hereafter, kinetic experiments are planned to be carried out to deduce the delayed neutron decay constants and subcriticality using the pulsed neutron method. (authors)

  13. Spectrum evaluation at the filter-modified neutron irradiation field for neutron capture therapy in Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Sakurai, Yoshinori; Kobayashi, Tooru

    2004-10-01

    The Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor (KUR-HWNIF) was updated in March 1996, mainly to improve the facility for neutron capture therapy (NCT). In this facility, neutron beams with various energy spectra, from almost pure thermal to epithermal, are available. The evaluation of the neutron energy spectra by multi-activation-foil method was performed as a series of the facility characterization. The spectra at the normal irradiation position were evaluated for the combinations of heavy-water thickness of the spectrum shifter and the open-close condition of the cadmium and boral filters. The initial spectra were made mainly using a two-dimensional transport code, and the final spectra were obtained using an adjusting code. For the verification of the evaluated spectra, simulation calculations using a phantom were performed on the assumption of NCT-clinical-irradiation conditions. It resulted that the calculated data for the depth neutron-flux distributions were in good agreement with the experimental ones.

  14. Controllability of depth dose distribution for neutron capture therapy at the Heavy Water Neutron Irradiation Facility of Kyoto University Research Reactor.

    PubMed

    Sakurai, Yoshinori; Kobayashi, Tooru

    2002-10-01

    The updating construction of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor has been performed from November 1995 to March 1996 mainly for the improvement in neutron capture therapy. On the performance, the neutron irradiation modes with the variable energy spectra from almost pure thermal to epi-thermal neutrons became available by the control of the heavy-water thickness in the spectrum shifter and by the open-and-close of the cadmium and boral thermal neutron filters. The depth distributions of thermal, epi-thermal and fast neutron fluxes were measured by activation method using gold and indium, and the depth distributions of gamma-ray absorbed dose rate were measured using thermo-luminescent dosimeter of beryllium oxide for the several irradiation modes. From these measured data, the controllability of the depth dose distribution using the spectrum shifter and the thermal neutron filters was confirmed.

  15. Reactor physics studies in the GCFR Phase III critical assembly

    SciTech Connect

    Morman, J A

    1980-03-01

    The third phase of the gas cooled fast reactor (GCFR) program, ZPR-9 Assembly 30, is based on a multi-zoned core of PuO/sub 2/-UO/sub 2/ with radial and axial blankets of UO/sub 2/. Studies performed in this assembly will be compared to the previous phases of the GCFR program and will help to define parameters in this power-flattened demonstration plant-type core. Measurements in the Phase III program included small sample reactivity worths of various materials, central reaction rates and reaction rate distributions, absorption-to-fission ratios and the central point conversion ratio and the worth of steam entry into a small central zone. The reactivity change associated with the construction of a central pin zone in the core and axial blanket was measured. Reaction rate and steam entry measurements were repeated in the pin environment. Standard analysis methods using ENDF/B-IV data are described and the results are compared to measurements performed during the program.

  16. Analysis of muon radiography of the Toshiba nuclear critical assembly reactor

    SciTech Connect

    Morris, C. L.; Bacon, Jeffery; Borozdin, Konstantin; Fabritius, J. M.; Perry, John; Ramsey, John; Ban, Yuichiro; Izumi, Mikio; Sano, Yuji; Yoshida, Noriyuki; Miyadera, Haruo; Mizokami, Shinya; Otsuka, Yasuyuki; Yamada, Daichi; Sugita, Tsukasa; Yoshioka, Kenichi

    2014-01-13

    A 1.2 × 1.2 m{sup 2} muon tracker was moved from Los Alamos to the Toshiba facility at Kawasaki, Japan, where it was used to take ∼4 weeks of data radiographing the Toshiba Critical Assembly Reactor with cosmic ray muons. In this paper, we describe the analysis procedure, show results of this experiment, and compare the results to Monte Carlo predictions. The results validate the concept of using cosmic rays to image the damaged cores of the Fukushima Daiichi reactors.

  17. Validation of FSP Reactor Design with Sensitivity Studies of Beryllium-Reflected Critical Assemblies

    SciTech Connect

    John D. Bess; Margaret A. Marshall

    2013-02-01

    The baseline design for space nuclear power is a fission surface power (FSP) system: sodium-potassium (NaK) cooled, fast spectrum reactor with highly-enriched-uranium (HEU)-O2 fuel, stainless steel (SS) cladding, and beryllium reflectors with B4C control drums. Previous studies were performed to evaluate modeling capabilities and quantify uncertainties and biases associated with analysis methods and nuclear data. Comparison of Zero Power Plutonium Reactor (ZPPR)-20 benchmark experiments with the FSP design indicated that further reduction of the total design model uncertainty requires the reduction in uncertainties pertaining to beryllium and uranium cross-section data. Further comparison with three beryllium-reflected HEU-metal benchmark experiments performed at the Oak Ridge Critical Experiments Facility (ORCEF) concluded the requirement that experimental validation data have similar cross section sensitivities to those found in the FSP design. A series of critical experiments was performed at ORCEF in the 1960s to support the Medium Power Reactor Experiment (MPRE) space reactor design. The small, compact critical assembly (SCCA) experiments were graphite- or beryllium-reflected assemblies of SS-clad, HEU-O2 fuel on a vertical lift machine. All five configurations were evaluated as benchmarks. Two of the five configurations were beryllium reflected, and further evaluated using the sensitivity and uncertainty analysis capabilities of SCALE 6.1. Validation of the example FSP design model was successful in reducing the primary uncertainty constituent, the Be(n,n) reaction, from 0.28 %dk/k to 0.0004 %dk/k. Further assessment of additional reactor physics measurements performed on the SCCA experiments may serve to further validate FSP design and operation.

  18. Mechanization of Library Procedures at the Kyoto Sangyo University

    ERIC Educational Resources Information Center

    Araki, Hugo

    1974-01-01

    When the new Kyoto Sangyo University library found itself with a large backlog of uncataloged books it turned to the computer. The library now has computerized cataloging, acquisitions, periodicals processing, circulation, and information retrieval. (LS)

  19. Criticality calculations of the Very High Temperature reactor Critical Assembly benchmark with Serpent and SCALE/KENO-VI

    SciTech Connect

    Bostelmann, Friederike; Hammer, Hans R.; Ortensi, Javier; Strydom, Gerhard; Velkov, Kiril; Zwermann, Winfried

    2015-12-30

    Within the framework of the IAEA Coordinated Research Project on HTGR Uncertainty Analysis in Modeling, criticality calculations of the Very High Temperature Critical Assembly experiment were performed as the validation reference to the prismatic MHTGR-350 lattice calculations. Criticality measurements performed at several temperature points at this Japanese graphite-moderated facility were recently included in the International Handbook of Evaluated Reactor Physics Benchmark Experiments, and represent one of the few data sets available for the validation of HTGR lattice physics. Here, this work compares VHTRC criticality simulations utilizing the Monte Carlo codes Serpent and SCALE/KENO-VI. Reasonable agreement was found between Serpent and KENO-VI, but only the use of the latest ENDF cross section library release, namely the ENDF/B-VII.1 library, led to an improved match with the measured data. Furthermore, the fourth beta release of SCALE 6.2/KENO-VI showed significant improvements from the current SCALE 6.1.2 version, compared to the experimental values and Serpent.

  20. Criticality calculations of the Very High Temperature reactor Critical Assembly benchmark with Serpent and SCALE/KENO-VI

    DOE PAGES

    Bostelmann, Friederike; Hammer, Hans R.; Ortensi, Javier; Strydom, Gerhard; Velkov, Kiril; Zwermann, Winfried

    2015-12-30

    Within the framework of the IAEA Coordinated Research Project on HTGR Uncertainty Analysis in Modeling, criticality calculations of the Very High Temperature Critical Assembly experiment were performed as the validation reference to the prismatic MHTGR-350 lattice calculations. Criticality measurements performed at several temperature points at this Japanese graphite-moderated facility were recently included in the International Handbook of Evaluated Reactor Physics Benchmark Experiments, and represent one of the few data sets available for the validation of HTGR lattice physics. Here, this work compares VHTRC criticality simulations utilizing the Monte Carlo codes Serpent and SCALE/KENO-VI. Reasonable agreement was found between Serpent andmore » KENO-VI, but only the use of the latest ENDF cross section library release, namely the ENDF/B-VII.1 library, led to an improved match with the measured data. Furthermore, the fourth beta release of SCALE 6.2/KENO-VI showed significant improvements from the current SCALE 6.1.2 version, compared to the experimental values and Serpent.« less

  1. Methanation assembly using multiple reactors

    DOEpatents

    Jahnke, Fred C.; Parab, Sanjay C.

    2007-07-24

    A methanation assembly for use with a water supply and a gas supply containing gas to be methanated in which a reactor assembly has a plurality of methanation reactors each for methanating gas input to the assembly and a gas delivery and cooling assembly adapted to deliver gas from the gas supply to each of said methanation reactors and to combine water from the water supply with the output of each methanation reactor being conveyed to a next methanation reactor and carry the mixture to such next methanation reactor.

  2. [Approach to Teaching Kampo Medicine at Kyoto Pharmaceutical University].

    PubMed

    Matsuda, Hisashi

    2016-01-01

    An approach to educating our pharmaceutical students about Kampo medicine in the six-year system of undergraduate pharmacy education at Kyoto Pharmaceutical University is introduced, including the author's opinions. Curriculum revisions have been made in our university for students entering after 2012. In teaching Kampo medicine at present, a medical doctor and an on-site pharmacist share information difficult to give in a lecture with the teaching staff in my laboratory. For example, before the curriculum revision, we conferred with a pharmacist and a doctor in the course "Kampo Medicine A, B" for 4th year students, in which students were presented a basic knowledge of Kampo medicine, the application of important Kampo medicines, combinations of crude drugs, etc. Further, in our "Introduction to Kampo Medicine" for 6th year students, presented after they have practiced in hospitals and community pharmacies, we again lecture on the pharmacological characteristics of Kampo medicines, on "pattern (Sho)", and on evidence-based medicine (EBM) and research studies of important Kampo medicines. After our curriculum revision, "Kampo Medicine A, B" was rearranged into the courses "Kampo and Pharmacognosy" and "Clinical Kampo Medicine". "Kampo and Pharmacognosy" is now provided in the second semester of the 3rd year, and in this course we lecture on the basic knowledge of Kampo medicine. An advanced lecture will be given on "Clinical Kampo Medicine" in the 6th year. We are searching for the best way to interest students in Kampo medicine, and to counteract any misunderstandings about Kampo medicine.

  3. Experimental Equipments for Microwave Power Transmission in Kyoto University

    NASA Astrophysics Data System (ADS)

    Matsumoto, H.; Hashimoto, K.; Shinohara, N.; Mitani, T.

    2004-12-01

    RISH, Research Institute of Sustainable Humanosphere, of Kyoto University is one of the most active research laboratories for a microwave power transmission (MPT) and SSPS (Space Solar Power System) in Japan. Since the first MPT rocket experiment in the ionosphere was conducted in early 1980's by Radio Science Center for Space and Atmosphere (RASC), the former institute of the RISH, the RISH has conducted a variety of theoretical and experimental studies on the MPT and SSPS both in laboratory and field. In the paper, we will show the experimental equipments for the MPT and the SSPS research in the RISH. We have two facilities of METLAB (Microwave Energy Transmission LABoratory) and SPSLAB (SPS LABoratory) for the MPT researches. The METLAB is composed of an anechoic radio wave chamber and an experimental system specially designed for the MPT experiment. The SPSLAB is a facility to promote a systematic research for conceptual, technical and coordinative research with our colleagues in all parts of Japan including the industrial partners. These facilities are now open for inter-universities collaborations. The other available experimental facilities are multiple MPT systems with a phased array transmitter using phase controlled magnetrons (PCMs) at both 2.45 GHz and 5.8 GHz, and a semiconductor-based beam control system and a retrodirective target detecting system. These facilities are named SPORTS (Space POwer Radio Transmission System) 2.45 and SPORTS5.8.

  4. A Code to Produce Cell Averaged Cross Sections for Fast Critical Assemblies and Fast Power Reactors.

    1987-05-14

    Version 00 SLAROM solves the neutron integral transport equations to determine the flux distribution and spectra in a fast reactor lattice and calculates cell averaged effective cross sections. The code uses multigroup data of the type in DLC-111/JFS that use Bondarenko factors for resonance effects.

  5. McCARD for Neutronics Design and Analysis of Research Reactor Cores

    NASA Astrophysics Data System (ADS)

    Shim, Hyung Jin; Park, Ho Jin; Kwon, Soonwoo; Seo, Geon Ho; Hyo Kim, Chang

    2014-06-01

    McCARD is a Monte Carlo (MC) neutron-photon transport simulation code developed exclusively for the neutronics design and analysis of nuclear reactor cores. McCARD is equipped with the hierarchical modeling and scripting functions, the CAD-based geometry processing module, the adjoint-weighted kinetics parameter and source multiplication factor estimation modules as well as the burnup analysis capability for the neutronics design and analysis of both research and power reactor cores. This paper highlights applicability of McCARD for the research reactor core neutronics analysis, as demonstrated for Kyoto University Critical Assembly, HANARO, and YALINA.

  6. FEL Beamline for Wide Tunable Range and Beam Sharing System at Kyoto University

    SciTech Connect

    Bakr, Mahmoud; Yoshida, K.; Higashimura, K.; Ueda, S.; Kinjo, R.; Sonobe, T.; Kii, T.; Masuda, K.; Ohgaki, H.; Zen, H.

    2010-02-03

    A mid-infrared free electron laser (MIR-FEL) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed for developing energy materials in Institute of Advanced Energy (IAE), Kyoto University. The tunable range of KU-FEL was estimated as 5-13.2 {mu}m by numerical calculation to design the MIR-FEL transport line for application purposes. Aiming to increase the number of FEL users with different desires we decided to develop an FEL beam sharing system that is useful for multi-utilization at different end-stations. The transport line and the beam sharing system has been designed and constructed to the user stations. Applications of the MIR-FEL in the renewable energy research at Kyoto University will start as well.

  7. FEL Beamline for Wide Tunable Range and Beam Sharing System at Kyoto University

    NASA Astrophysics Data System (ADS)

    Bakr, Mahmoud; Yoshida, K.; Higashimura, K.; Ueda, S.; Kinjo, R.; Zen, H.; Sonobe, T.; Kii, T.; Masuda, K.; Ohgaki, H.

    2010-02-01

    A mid-infrared free electron laser (MIR-FEL) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed for developing energy materials in Institute of Advanced Energy (IAE), Kyoto University. The tunable range of KU-FEL was estimated as 5-13.2 μm by numerical calculation to design the MIR-FEL transport line for application purposes. Aiming to increase the number of FEL users with different desires we decided to develop an FEL beam sharing system that is useful for multi-utilization at different end-stations. The transport line and the beam sharing system has been designed and constructed to the user stations. Applications of the MIR-FEL in the renewable energy research at Kyoto University will start as well.

  8. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    SciTech Connect

    Kahler, A.; Macfarlane, R E; Mosteller, R D; Kiedrowski, B C; Frankle, S C; Chadwick, M. B.; Mcknight, R D; Lell, R M; Palmiotti, G; Hiruta, h; Herman, Micheal W; Arcilla, r; Mughabghab, S F; Sublet, J C; Trkov, A.; Trumbull, T H; Dunn, Michael E

    2011-01-01

    The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [1]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unrnoderated and uranium reflected (235)U and (239)Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected actinide reaction rates such as (236)U; (238,242)Pu and (241,243)Am capture in fast systems. Other deficiencies, such as the overprediction of Pu solution system critical eigenvalues

  9. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    SciTech Connect

    G. Palmiotti

    2011-12-01

    The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 418 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [1]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected 235U and 239Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected actinide reaction rates such as 236U capture. Other deficiencies, such as the overprediction of Pu solution system critical eigenvalues and a decreasing trend in calculated eigenvalue for

  10. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    SciTech Connect

    Kahler, A.C.; Herman, M.; Kahler,A.C.; MacFarlane,R.E.; Mosteller,R.D.; Kiedrowski,B.C.; Frankle,S.C.; Chadwick,M.B.; McKnight,R.D.; Lell,R.M.; Palmiotti,G.; Hiruta,H.; Herman,M.; Arcilla,R.; Mughabghab,S.F.; Sublet,J.C.; Trkov,A.; Trumbull,T.H.; Dunn,M.

    2011-12-01

    The ENDF/B-VII.1 library is the latest revision to the United States Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [M. B. Chadwick et al., 'ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data,' Nuclear Data Sheets, 112, 2887 (2011)]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected {sup 235}U and {sup 239}Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for

  11. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    NASA Astrophysics Data System (ADS)

    Kahler, A. C.; MacFarlane, R. E.; Mosteller, R. D.; Kiedrowski, B. C.; Frankle, S. C.; Chadwick, M. B.; McKnight, R. D.; Lell, R. M.; Palmiotti, G.; Hiruta, H.; Herman, M.; Arcilla, R.; Mughabghab, S. F.; Sublet, J. C.; Trkov, A.; Trumbull, T. H.; Dunn, M.

    2011-12-01

    The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [M. B. Chadwick et al., "ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data," Nuclear Data Sheets, 112, 2887 (2011)]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected 235U and 239Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected

  12. Criticality of spent reactor fuel

    SciTech Connect

    Harris, D.R.

    1987-01-01

    The storage capacity of spent reactor fuel pools can be greatly increased by consolidation. In this process, the fuel rods are removed from reactor fuel assemblies and are stored in close-packed arrays in a canister or skeleton. An earlier study examined criticality consideration for consolidation of Westinghouse fuel, assumed to be fresh, in canisters at the Millstone-2 spent-fuel pool and in the General Electric IF-300 shipping cask. The conclusions were that the fuel rods in the canister are so deficient in water that they are adequately subcritical, both in normal and in off-normal conditions. One potential accident, the water spill event, remained unresolved in the earlier study. A methodology is developed here for spent-fuel criticality and is applied to the water spill event. The methodology utilizes LEOPARD to compute few-group cross sections for the diffusion code PDQ7, which then is used to compute reactivity. These codes give results for fresh fuel that are in good agreement with KENO IV-NITAWL Monte Carlo results, which themselves are in good agreement with continuous energy Monte Carlo calculations. These methodologies are in reasonable agreement with critical measurements for undepleted fuel.

  13. University Reactor Instrumentation Program

    SciTech Connect

    Vernetson, W.G.

    1992-11-01

    Recognizing that the University Reactor Instrumentation Program was developed in response to widespread needs in the academic community for modernization and improvement of research and training reactors at institutions such as the University of Florida, the items proposed to be supported by this grant over its two year period have been selected as those most likely to reduce foreed outages, to meet regulatory concerns that had been expressed in recent years by Nuclear Regulatory Commission inspectors or to correct other facility problems and limitations. Department of Energy Grant Number DE-FG07-90ER129969 was provided to the University of Florida Training Reactor(UFTR) facility through the US Department of Energy's University Reactor Instrumentation Program. The original proposal submitted in February, 1990 requested support for UFTR facility instrumentation and equipment upgrades for seven items in the amount of $107,530 with $13,800 of this amount to be the subject of cost sharing by the University of Florida and $93,730 requested as support from the Department of Energy. A breakdown of the items requested and total cost for the proposed UFTR facility instrumentation and equipment improvements is presented.

  14. REACTOR NOZZLE ASSEMBLY

    DOEpatents

    Capuder, F.C.; Dearwater, J.R.

    1959-02-10

    An improved nozzle assembly useful in a process for the direct reduction of uranium hexafluoride to uranium tetrafluoride by means of dissociated ammonia in a heated reaction vessel is descrlbed. The nozzle design provides for intimate mixing of the two reactants and at the same time furnishes a layer of dissociated ammonia adjacent to the interior wall of the reaction vessel, thus preventing build-up of the reaction product on the vessel wall.

  15. NRC Targets University Reactors.

    ERIC Educational Resources Information Center

    Marshall, Eliot

    1984-01-01

    The Nuclear Regulatory Commission (NRC) wants universities to convert to low-grade fuel in their research reactions. Researchers claim the conversion, which will bring U.S. reactors in line with a policy the NRC is trying to impress on foreigners, could be financially and scientifically costly. Impact of the policy is considered. (JN)

  16. On the Criticality Safety of Transuranic Sodium Fast Reactor Fuel Transport Casks

    SciTech Connect

    Samuel Bays; Ayodeji Alajo

    2010-05-01

    This work addresses the neutronic performance and criticality safety issues of transport casks for fuel pertaining to low conversion ratio sodium cooled fast reactors, conventionally known as Advanced Burner Reactors. The criticality of a one, three, seven and 19-assembly cask capacity is presented. Both dry “helium” and flooded “water” filled casks are considered. No credit for fuel burnup or fission products was assumed. As many as possible of the conservatisms used in licensing light water reactor universal transport casks were incorporated into this SFR cask criticality design and analysis. It was found that at 7-assemblies or more, adding moderator to the SFR cask increases criticality margin. Also, removal of MAs from the fuel increases criticality margin of dry casks and takes a slight amount of margin away for wet casks. Assuming credit for borated fuel tube liners, this design analysis suggests that as many as 19 assemblies can be loaded in a cask if limited purely by criticality safety. If no credit for boron is assumed, the cask could possibly hold seven assemblies if low conversion ratio fast reactor grade fuel and not breeder reactor grade fuel is assumed. The analysis showed that there is a need for new cask designs for fast reactors spent fuel transportation. There is a potential of modifying existing transportation cask design as the starting point for fast reactor spent fuel transportation.

  17. [Dr. Michiharu Matsuoka, founder of the Department of Orthopaedic Surgery, Kyoto University, and his achievements. Part 4: Prof. M. Matsuoka's lecture to medical and civic communities].

    PubMed

    Hirotani, Hayato

    2010-03-01

    Dr. M. Matsuoka gave many lectures to physicians at the Postdoctoral Course Lectures sponsored by the Kyoto Eisei Kensasho (Kyoto Bacterial and Biochemical Laboratory) run by the Kyoto Medical Association, and the Postdoctoral Course Lectures of the Kyoto Medical School, Kyoto Imperial University. He was also invited to give lectures at several regional medical associations. He also was a speaker at the Kyoto Imperial University Extension course and he lectured at the Enryakuji Temple on Mt. Hiei, sponsored by a newspaper company. It is remarkable that these activities were carried out in addition to his other notable academic work previously reported.

  18. Nuclear reactor composite fuel assembly

    DOEpatents

    Burgess, Donn M.; Marr, Duane R.; Cappiello, Michael W.; Omberg, Ronald P.

    1980-01-01

    A core and composite fuel assembly for a liquid-cooled breeder nuclear reactor including a plurality of elongated coextending driver and breeder fuel elements arranged to form a generally polygonal bundle within a thin-walled duct. The breeder elements are larger in cross section than the driver elements, and each breeder element is laterally bounded by a number of the driver elements. Each driver element further includes structure for spacing the driver elements from adjacent fuel elements and, where adjacent, the thin-walled duct. A core made up of the fuel elements can advantageously include fissile fuel of only one enrichment, while varying the effective enrichment of any given assembly or core region, merely by varying the relative number and size of the driver and breeder elements.

  19. Los Alamos Critical Assemblies Facility

    SciTech Connect

    Malenfant, R.E.

    1981-06-01

    The Critical Assemblies Facility of the Los Alamos National Laboratory has been in existence for thirty-five years. In that period, many thousands of measurements have been made on assemblies of /sup 235/U, /sup 233/U, and /sup 239/Pu in various configurations, including the nitrate, sulfate, fluoride, carbide, and oxide chemical compositions and the solid, liquid, and gaseous states. The present complex of eleven operating machines is described, and typical applications are presented.

  20. Reactivity control assembly for nuclear reactor

    DOEpatents

    Bollinger, Lawrence R.

    1984-01-01

    Reactivity control assembly for nuclear reactor comprises supports stacked above reactor core for holding control rods. Couplers associated with the supports and a vertically movable drive shaft have lugs at their lower ends for engagement with the supports.

  1. University Reactor Sharing Program

    SciTech Connect

    W.D. Reese

    2004-02-24

    Research projects supported by the program include items such as dating geological material and producing high current super conducting magnets. The funding continues to give small colleges and universities the valuable opportunity to use the NSC for teaching courses in nuclear processes; specifically neutron activation analysis and gamma spectroscopy. The Reactor Sharing Program has supported the construction of a Fast Neutron Flux Irradiator for users at New Mexico Institute of Mining and Technology and the University of Houston. This device has been characterized and has been found to have near optimum neutron fluxes for A39/Ar 40 dating. Institution final reports and publications resulting from the use of these funds are on file at the Nuclear Science Center.

  2. NUCLEAR REACTOR FUEL ELEMENT ASSEMBLY

    DOEpatents

    Stengel, F.G.

    1963-12-24

    A method of fabricating nuclear reactor fuel element assemblies having a plurality of longitudinally extending flat fuel elements in spaced parallel relation to each other to form channels is presented. One side of a flat side plate is held contiguous to the ends of the elements and a welding means is passed along the other side of the platertransverse to the direction of the longitudinal extension of the elements. The setting and speed of travel of the welding means is set to cause penetration of the side plate with welds at bridge the gap in each channel between adjacent fuel elements with a weld-through bubble of predetermined size. The fabrication of a high strength, dependable fuel element is provided, and the reduction of distortion and high production costs are facilitated by this method. (AEC)

  3. Lasing at 12 µm Mid-Infrared Free-Electron Laser in Kyoto University

    NASA Astrophysics Data System (ADS)

    Ohgaki, Hideaki; Kii, Toshiteru; Masuda, Kai; Zen, Heishun; Sasaki, Satoshi; Shiiyama, Takumi; Kinjo, Ryota; Yoshikawa, Kiyoshi; Yamazaki, Tetsuo

    2008-10-01

    Laser amplification using a 12 µm mid-infrared free-electron laser (MIR-FEL) was observed at the Institute of Advanced Energy (IAE), Kyoto University. A 25 MeV electron beam of 17 A peak current was used for the lasing experiment. A beam loading compensation method with an RF amplitude control in the thermionic RF gun was used to extend the macropulse duration against the backbombardment effect in the thermionic RF gun. As a result, an electron beam with a 4 µs duration was generated. A laser output with an intensity 50 times as high as the spontaneous emission intensity was observed. FEL gain was estimated to be 16% from the exponential growth of the laser output signal, and a cavity loss of 2.8% was estimated from the decay of the laser output signal. Three-dimensional (3D) FEL simulation was also performed to achieve the gain saturation in our FEL device.

  4. Design studies of IR-FEL system at IAE, Kyoto University

    NASA Astrophysics Data System (ADS)

    Ohgaki, H.; Tometaka, I.; Yamane, K.; Kii, T.; Masuda, K.; Yoshikawa, K.; Yamazaki, T.

    2003-07-01

    An infrared FEL facility for bio/chemical energy research is under construction at the Institute of Advanced Energy, Kyoto University. The electron beam of 25-40 MeV with macropulse duration up to 3 μs will be generated by an S-band linac with a thermionic RF gun. Numerical studies to estimate the electron beam parameters and expected FEL gain of the present system have been performed to settle the goal for the system commissioning and the first operational condition. The results show that the present system can provide lasing in the wavelength from 4 to 13 μm by using a 180° arc. However, the macropulse duration is too short to deliver stable FEL for a practical usage.

  5. Development of IR-FEL facility for energy science in Kyoto University

    NASA Astrophysics Data System (ADS)

    Zen, Heishun; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki; Yamazaki, Tetsuo

    2008-05-01

    A mid-infrared free electron laser (FEL) has been constructed for energy science in the Institute of Advanced Energy, Kyoto University. The FEL system consists of a compact S-band Linac and an undulator to generate 4-13 μm coherent mid-infrared radiations. The Linac consists of a 4.5 cell rf gun with a thermionic cathode and a 3-m traveling-wave-type accelerator tube fed by 10 MW and 20 MW rf power, respectively. We have succeeded to produce 40 MeV, 40 mA and 3 μs electron beams. Last December, the 9.2 μm spontaneous emission from the undulator generated by 29.5 MeV electron beams was observed for the first time. Further optimization parameters of both the electron beam and the optical cavity are being pursued for an FEL lasing in the near future.

  6. Site-specific phase I, II trials of hyperthermia at Kyoto University.

    PubMed

    Hiraoka, M; Nishimura, Y; Nagata, Y; Mitsumori, M; Okuno, Y; Li, P Y; Abe, M; Takahashi, M; Masunaga, S; Akuta, K

    1994-01-01

    Site-specific phase I, II trials of locoregional hyperthermia undertaken at Kyoto University are briefly reviewed. Thermometry analysis demonstrated the usefulness of RF (radiofrequency) capacitive heating equipment in the treatment of various subsurface or deep-seated tumours including locally advanced breast cancers, soft tissue tumours, lung cancers involving the chest wall, liver tumours, unresectable or recurrent colorectal cancers, and invasive urinary bladder cancers. The difficulty in heating whole tumour volume or hypervascular tumours to therapeutic temperatures was also shown. Non-randomized trials for locally advanced breast cancers, unresectable or recurrent colorectal cancers and invasive urinary bladder cancers demonstrated a higher response rate in thermoradiotherapy than in radiotherapy alone. The complications associated with treatment were not generally serious except for chronic bowel damages in a trial for colorectal cancers. These promising phase I, II trials encourage the future phase III trials.

  7. University Reactor Conversion Lessons Learned Workshop for Purdue University Reactor

    SciTech Connect

    Eric C. Woolstenhulme; Dana M. Hewit

    2008-09-01

    The Department of Energy’s Idaho National Laboratory, under its programmatic responsibility for managing the University Research Reactor Conversions, has completed the conversion of the reactor at Purdue University Reactor. With this work completed and in anticipation of other impending conversion projects, the INL convened and engaged the project participants in a structured discussion to capture the lessons learned. The lessons learned process has allowed us to capture gaps, opportunities, and good practices, drawing from the project team’s experiences. These lessons will be used to raise the standard of excellence, effectiveness, and efficiency in all future conversion projects.

  8. Critical Casimir forces for colloidal assembly.

    PubMed

    Nguyen, V D; Dang, M T; Nguyen, T A; Schall, P

    2016-02-01

    Critical Casimir forces attract increasing interest due to their opportunities for reversible particle assembly in soft matter and nano science. These forces provide a thermodynamic analogue of the celebrated quantum mechanical Casimir force that arises from the confinement of vacuum fluctuations of the electromagnetic field. In its thermodynamic analogue, solvent fluctuations, confined between suspended particles, give rise to an attractive or repulsive force between the particles. Due to its unique temperature dependence, this effect allows in situ control of reversible assembly. Both the force magnitude and range vary with the solvent correlation length in a universal manner, adjusting with temperature from fractions of the thermal energy, k B T, and nanometre range to several ten kT and micrometer length scale. Combined with recent breakthroughs in the synthesis of complex particles, critical Casimir forces promise the design and assembly of complex colloidal structures, for fundamental studies of equilibrium and out-of-equilibrium phase behaviour. This review highlights recent developments in this evolving field, with special emphasis on the dynamic interaction control to assemble colloidal structures, in and out of equilibrium. PMID:26750980

  9. Critical Casimir forces for colloidal assembly

    NASA Astrophysics Data System (ADS)

    Nguyen, V. D.; Dang, M. T.; Nguyen, T. A.; Schall, P.

    2016-02-01

    Critical Casimir forces attract increasing interest due to their opportunities for reversible particle assembly in soft matter and nano science. These forces provide a thermodynamic analogue of the celebrated quantum mechanical Casimir force that arises from the confinement of vacuum fluctuations of the electromagnetic field. In its thermodynamic analogue, solvent fluctuations, confined between suspended particles, give rise to an attractive or repulsive force between the particles. Due to its unique temperature dependence, this effect allows in situ control of reversible assembly. Both the force magnitude and range vary with the solvent correlation length in a universal manner, adjusting with temperature from fractions of the thermal energy, k B T, and nanometre range to several ten kT and micrometer length scale. Combined with recent breakthroughs in the synthesis of complex particles, critical Casimir forces promise the design and assembly of complex colloidal structures, for fundamental studies of equilibrium and out-of-equilibrium phase behaviour. This review highlights recent developments in this evolving field, with special emphasis on the dynamic interaction control to assemble colloidal structures, in and out of equilibrium.

  10. Scanning tunneling microscope assembly, reactor, and system

    SciTech Connect

    Tao, Feng; Salmeron, Miquel; Somorjai, Gabor A

    2014-11-18

    An embodiment of a scanning tunneling microscope (STM) reactor includes a pressure vessel, an STM assembly, and three spring coupling objects. The pressure vessel includes a sealable port, an interior, and an exterior. An embodiment of an STM system includes a vacuum chamber, an STM reactor, and three springs. The three springs couple the STM reactor to the vacuum chamber and are operable to suspend the scanning tunneling microscope reactor within the interior of the vacuum chamber during operation of the STM reactor. An embodiment of an STM assembly includes a coarse displacement arrangement, a piezoelectric fine displacement scanning tube coupled to the coarse displacement arrangement, and a receiver. The piezoelectric fine displacement scanning tube is coupled to the coarse displacement arrangement. The receiver is coupled to the piezoelectric scanning tube and is operable to receive a tip holder, and the tip holder is operable to receive a tip.

  11. The Kyoto Tridimensional Spectrograph II on Subaru and the University of Hawaii 88 in Telescopes

    NASA Astrophysics Data System (ADS)

    Sugai, H.; Hattori, T.; Kawai, A.; Ozaki, S.; Hayashi, T.; Ishigaki, T.; Ishii, M.; Ohtani, H.; Shimono, A.; Okita, Y.; Matsubayashi, K.; Kosugi, G.; Sasaki, M.; Takeyama, N.

    2010-01-01

    In order to investigate physical conditions of ionized gas in galaxies, as well as its kinematics, we have developed the Kyoto tridimensional spectrograph II. It is a multimode optical instrument, including integral field spectrograph (IFS) and Fabry-Perot imager modes. We have designed it compact so that we can mount it on 2 m class telescopes as well as on the 8.2 m Subaru telescope. Special care was taken to obtain high-quality calibrations in the IFS mode. In order to remove the chromatic aberration of micropupil images produced by a lenslet array, we have introduced a corrector lens system behind the lenslet array. The internal calibration system simulates the telescope optics so that the system provides micropupil images identical to those produced by the telescope. The rigidness of the instrument provides the positional stability of micropupil images. We have succeeded in test observations of all the modes on Subaru and the University of Hawaii 88 in (UH88) telescopes and have verified the performance of the instrument. This includes the instrument efficiencies as well as the effective sky background subtraction and the minimization of crosstalk effects in the IFS mode. In the IFS mode a spatial resolution of 0.4'' was obtained in good seeing conditions. Each of 37 × 37 lenslets subtends 0.1'' in Subaru's case. This samples the image size well. A wider field of view is emphasized in the case of UH88.

  12. Dismantlement of the TSF-SNAP Reactor Assembly

    SciTech Connect

    Peretz, Fred J

    2009-01-01

    This paper describes the dismantlement of the Tower Shielding Facility (TSF)?Systems for Nuclear Auxiliary Power (SNAP) reactor, a SNAP-10A reactor used to validate radiation source terms and shield performance models at Oak Ridge National Laboratory (ORNL) from 1967 through 1973. After shutdown, it was placed in storage at the Y-12 National Security Complex (Y-12), eventually falling under the auspices of the Highly Enriched Uranium (HEU) Disposition Program. To facilitate downblending of the HEU present in the fuel elements, the TSF-SNAP was moved to ORNL on June 24, 2006. The reactor assembly was removed from its packaging, inspected, and the sodium-potassium (NaK) coolant was drained. A superheated steam process was used to chemically react the residual NaK inside the reactor assembly. The heat exchanger assembly was removed from the top of the reactor vessel, and the criticality safety sleeve was exchanged for a new safety sleeve that allowed for the removal of the vessel lid. A chain-mounted tubing cutter was used to separate the lid from the vessel, and the 36 fuel elements were removed and packaged in four U.S. Department of Transportation 2R/6M containers. The fuel elements were returned to Y-12 on July 13, 2006. The return of the fuel elements and disposal of all other reactor materials accomplished the formal objectives of the dismantlement project. In addition, a project model was established for the handling of a fully fueled liquid-metal?cooled reactor assembly. Current criticality safety codes have been benchmarked against experiments performed by Atomics International in the 1950s and 1960s. Execution of this project provides valuable experience applicable to future projects addressing space and liquid-metal-cooled reactors.

  13. Fuel assembly for nuclear reactors

    DOEpatents

    Creagan, Robert J.; Frisch, Erling

    1977-01-01

    A new and improved fuel assembly is formed to minimize the amount of parasitic structural material wherein a plurality of hollow tubular members are juxtaposed to the fuel elements of the assembly. The tubular members may serve as guide tubes for control elements and are secured to a number of longitudinally spaced grid members along the fuel assembly. The grid members include means thereon engaging each of the fuel elements to laterally position the fuel elements in a predetermined array. Openings in the bottom of each hollow member serve as a shock absorber to cushion shock transmitted to the structure when the control elements are rapidly inserted in their corresponding tubular members.

  14. [Experience of Collaborative Research through Department of Medical Instrumental Research and Technology in Kyoto Prefectural University of Medicine].

    PubMed

    Saitoh, Kensuke

    2016-01-01

    Both of Kyoto Prefectural University of Medicine which offers high, technical and safe medical treatment and Horiba, Ltd. which has small CBC analyzers in a core product established a joint research institute for development of advanced laboratory test analyzer from January 1, 2012 in Kyoto Prefectural University of Medicine as the "advanced treatment hospital" where the Ministry of Health, Labour and Welfare has got approved. Clinical needs about analyzer and reagent for a laboratory test are being investigated to the emergency medical care unit and the intensive care unit as well as the laboratory test part in the affiliated hospital and many medical departments of the pediatrics, the internal medicine and the surgery. Developing the new analyzer based on high technology, evaluating the performance of them and spreading them to a medical examination and treatment site is our main target.

  15. Reactivity control assembly for nuclear reactor. [LMFBR

    DOEpatents

    Bollinger, L.R.

    1982-03-17

    This invention, which resulted from a contact with the United States Department of Energy, relates to a control mechanism for a nuclear reactor and, more particularly, to an assembly for selectively shifting different numbers of reactivity modifying rods into and out of the core of a nuclear reactor. It has been proposed heretofore to control the reactivity of a breeder reactor by varying the depth of insertion of control rods (e.g., rods containing a fertile material such as ThO/sub 2/) in the core of the reactor, thereby varying the amount of neutron-thermalizing coolant and the amount of neutron-capturing material in the core. This invention relates to a mechanism which can advantageously be used in this type of reactor control system.

  16. Lateral restraint assembly for reactor core

    DOEpatents

    Gorholt, Wilhelm; Luci, Raymond K.

    1986-01-01

    A restraint assembly for use in restraining lateral movement of a reactor core relative to a reactor vessel wherein a plurality of restraint assemblies are interposed between the reactor core and the reactor vessel in circumferentially spaced relation about the core. Each lateral restraint assembly includes a face plate urged against the outer periphery of the core by a plurality of compression springs which enable radial preloading of outer reflector blocks about the core and resist low-level lateral motion of the core. A fixed radial key member cooperates with each face plate in a manner enabling vertical movement of the face plate relative to the key member but restraining movement of the face plate transverse to the key member in a plane transverse to the center axis of the core. In this manner, the key members which have their axes transverse to or subtending acute angles with the direction of a high energy force tending to move the core laterally relative to the reactor vessel restrain such lateral movement.

  17. Electromagnetic Near Field Measurements of Two Critical Assemblies

    NASA Astrophysics Data System (ADS)

    Goettee, Jeffrey; Goorley, Tim; Mayo, Douglas; Myers, William; Goda, Joetta; Sage, Frank

    2015-04-01

    Preliminary measurements of the fast metal nuclear reactors at the National Criticality Experiments Research Center (NCERC) and at White Sands Missile Range (WSMR) within the past year characterize the very near field environment of these critical assemblies. Both reactors are fast, highly enriched uranium metal reactors and can be operated in a burst mode above prompt supercritical. Initial measurements of the electric and the magnetic fields within the reactor cell are consistent between the two facilities, and begin to describe the dependance on distance and polarization as might be assumed from initial Monte Carlo modelling of these facilities. The amplitude and time variation of the electric and magnetic fields are consistent with burst time scales. The polarization is consistent with the geometry of the source and with Compton scattering from fission gammas as the dominant ionization mechanism. An overview of the two fast neutron sources and the excursion dynamics, the experimental details, and summary of the modelling calculations will be provided as background.

  18. Beryllium reflected cavity reactor for UF6 critical experiments

    NASA Technical Reports Server (NTRS)

    Jarvis, G. A.; Bernard, W.; Helmick, H. H.; White, R.

    1975-01-01

    Experiments and theoretical studies are being conducted for NASA on critical assemblies with one-meter diam by one-meter long low-density cores surrounded by a thick beryllium reflector. These assemblies make extensive use of existing nuclear propulsion reactor components, facilities, and instrumentation. Due to excessive porosity in the reflector, the initial critical mass was 19 kg U(93.2). Addition of a 17-cm-thick by 89-cm-diam beryllium flux trap in the cavity reduced the critical mass to 7 kg when all the uranium was in the zone just outside the flux trap. A mockup aluminum UF6 container was placed inside the flux trap and fueled with uranium-graphite elements. Fission distributions and reactivity worths of fuel and structural materials are available. These results will be used to guide the design of a prototype plasma core reactor which will test energy removal by optical radiation.

  19. Nuclear reactor shutdown control rod assembly

    DOEpatents

    Bilibin, Konstantin

    1988-01-01

    A temperature responsive, self-actuated nuclear reactor shutdown control rod assembly 10. The upper end 18 of a lower drive line 17 fits within the lower end of an upper drive line 12. The lower end (not shown) of the lower drive line 17 is connected to a neutron absorber. During normal temperature conditions the lower drive line 17 is supported by detent means 22,26. When an overtemperature condition occurs thermal actuation means 34 urges ring 26 upwardly sufficiently to allow balls 22 to move radially outwardly thereby allowing lower drive line 17 to move downwardly toward the core of the nuclear reactor resulting in automatic reduction of the reactor powder.

  20. Spring element for holding down nuclear reactor fuel assembly

    SciTech Connect

    Steinke, A.

    1981-07-14

    Spring element is described for holding down and bracing a fuel assembly against a hold-down plate upwardly limiting the reactor core of a nuclear reactor. Includes a spring-loaded rod-shaped member separately formed independently of the fuel assembly and being slidable axially and form-lockingly into the fuel assembly.

  1. Criticality Safety Evaluation of the LLNL Inherently Safe Subcritical Assembly (ISSA)

    SciTech Connect

    Percher, Catherine

    2012-06-19

    The LLNL Nuclear Criticality Safety Division has developed a training center to illustrate criticality safety and reactor physics concepts through hands-on experimental training. The experimental assembly, the Inherently Safe Subcritical Assembly (ISSA), uses surplus highly enriched research reactor fuel configured in a water tank. The training activities will be conducted by LLNL following the requirements of an Integration Work Sheet (IWS) and associated Safety Plan. Students will be allowed to handle the fissile material under the supervision of LLNL instructors. This report provides the technical criticality safety basis for instructional operations with the ISSA experimental assembly.

  2. Experimental Criticality Benchmarks for SNAP 10A/2 Reactor Cores

    SciTech Connect

    Krass, A.W.

    2005-12-19

    This report describes computational benchmark models for nuclear criticality derived from descriptions of the Systems for Nuclear Auxiliary Power (SNAP) Critical Assembly (SCA)-4B experimental criticality program conducted by Atomics International during the early 1960's. The selected experimental configurations consist of fueled SNAP 10A/2-type reactor cores subject to varied conditions of water immersion and reflection under experimental control to measure neutron multiplication. SNAP 10A/2-type reactor cores are compact volumes fueled and moderated with the hydride of highly enriched uranium-zirconium alloy. Specifications for the materials and geometry needed to describe a given experimental configuration for a model using MCNP5 are provided. The material and geometry specifications are adequate to permit user development of input for alternative nuclear safety codes, such as KENO. A total of 73 distinct experimental configurations are described.

  3. Reactor building assembly and method of operation

    SciTech Connect

    Fennern, L.E.; Caraway, H.A.; Hsu, Li C.

    1993-06-01

    A reactor building assembly is described comprising: a reactor pressure vessel containing a reactor core for generating heat in the form of steam; a containment vessel enclosing said pressure vessel; a first enclosure surrounding said containment vessel and spaced laterally therefrom to define a first chamber there between, and having a top and a bottom; a second enclosure surrounding said first enclosure and spaced laterally therefrom to define a second chamber there between, and having a top and a bottom; a building inlet for receiving into said second chamber fresh air from outside said second enclosure; a building outlet for discharging stale air from said first chamber; a transfer duct disposed through said first enclosure selectively joining in flow communication said first and second chambers; said building inlet being disposed at said second enclosure top, said building outlet being disposed at said first enclosure top, and said transfer duct being disposed adjacent said first enclosure bottom for allowing said fresh air to flow downwardly by gravity through said second chamber and through said transfer duct into said first chamber for cooling said first chamber, said stale air flowing upwardly by natural buoyancy for discharger from said first chamber through said building outlet; an exhaust stack disposed above said building outlet and in flow communication therewith for channeling upwardly said stale air from said first chamber for discharge into the surrounding environs; and a passive first driving means for increasing flow of said stale air from said building outlet comprising: an isolation pool containing isolation water; an isolation condenser disposed in said isolation pool, and joined in flow communication with said reactor pressure vessel for receiving primary steam therefrom, said primary steam being cooled in said isolation condenser for heating said isolation water to generate secondary steam.

  4. Summary reports of activities under visiting research program, 1993

    NASA Astrophysics Data System (ADS)

    1993-10-01

    The summary reports of activities under visiting research program in the Research Reactor Institute, Kyoto University, in fiscal year 1992 are included. In this report, 104 summaries of researches using the Kyoto University Reactor (KUR) and 9 summaries of the researches using the Kyoto University Critical Assembly (KUCA) are collected.

  5. University of Virginia Reactor Facility Decommissioning Results

    SciTech Connect

    Ervin, P. F.; Lundberg, L. A.; Benneche, P. E.; Mulder, R. U.; Steva, D. P.

    2003-02-24

    The University of Virginia Reactor Facility started accelerated decommissioning in 2002. The facility consists of two licensed reactors, the CAVALIER and the UVAR. This paper will describe the progress in 2002, remaining efforts and the unique organizational structure of the project team.

  6. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    SciTech Connect

    Cappiello, C.C.; Butterfield, K.B.; Sanchez, R.G.; Bounds, J.A.; Kimpland, R.H.; Damjanovich, R.P.; Jaegers, P.J.

    1997-08-01

    Experiments were performed to measure a variety of parameters for SHEBA: behavior of the facility during transient and steady-state operation; characteristics of the SHEBA fuel; delayed-critical solution height vs solution temperature; initial reactor period and reactivity vs solution height; calibration of power level vs reactor power instrumentation readings; flux profile in SHEBA; radiation levels and neutron spectra outside the assembly for code verification and criticality alarm and dosimetry purposes; and effect on reactivity of voids in the fuel.

  7. University Reactor Matching Grants Program

    SciTech Connect

    John Valentine; Farzad Rahnema; Said Abdel-Khalik

    2003-02-14

    During the 2002 Fiscal year, funds from the DOE matching grant program, along with matching funds from the industrial sponsors, have been used to support research in the area of thermal-hydraulics. Both experimental and numerical research projects have been performed. Experimental research focused on two areas: (1) Identification of the root cause mechanism for axial offset anomaly in pressurized water reactors under prototypical reactor conditions, and (2) Fluid dynamic aspects of thin liquid film protection schemes for inertial fusion reactor chambers. Numerical research focused on two areas: (1) Multi-fluid modeling of both two-phase and two-component flows for steam conditioning and mist cooling applications, and (2) Modeling of bounded Rayleigh-Taylor instability with interfacial mass transfer and fluid injection through a porous wall simulating the ''wetted wall'' protection scheme in inertial fusion reactor chambers. Details of activities in these areas are given.

  8. University research reactors and Internet communication

    SciTech Connect

    Bobek, L.M.

    1994-12-31

    In July 1993, the U.S. Nuclear Regulatory Commission (NRC) stunned nonprofit U.S. universities by eliminating the historical fee exemption for these entities. The fees would have devastating effects on university reactor operations and university by-product material usage. Faced with the prospect of eliminating their programs, the university research reactor (URR) community made a concerted response to reinstate the exemption. While the effort eventually proved successful, the need for fast and efficient communication became very apparent during the crisis. One outcome was an effort to enhance communications among the university reactors by using electronic mail (E-mail) on the Internet. This paper describes how the fee crisis demonstrated the need for enhanced communications and the results of the effort to provide it.

  9. Nuclear criticality research at the University of New Mexico

    SciTech Connect

    Busch, R.D.

    1997-06-01

    Two projects at the University of New Mexico are briefly described. The university`s Chemical and Nuclear Engineering Department has completed the final draft of a primer for MCNP4A, which it plans to publish soon. The primer was written to help an analyst who has little experience with the MCNP code to perform criticality safety analyses. In addition, the department has carried out a series of approach-to-critical experiments on the SHEBA-II, a UO{sub 2}F{sub 2} solution critical assembly at Los Alamos National Laboratory. The results obtained differed slightly from what was predicted by the TWODANT code.

  10. Nuclear reactor removable radial shielding assembly having a self-bowing feature

    DOEpatents

    Pennell, William E.; Kalinowski, Joseph E.; Waldby, Robert N.; Rylatt, John A.; Swenson, Daniel V.

    1978-01-01

    A removable radial shielding assembly for use in the periphery of the core of a liquid-metal-cooled fast-breeder reactor, for closing interassembly gaps in the reactor core assembly load plane prior to reactor criticality and power operation to prevent positive reactivity insertion. The assembly has a lower nozzle portion for inserting into the core support and a flexible heat-sensitive bimetallic central spine surrounded by blocks of shielding material. At refueling temperature and below the spine is relaxed and in a vertical position so that the tolerances permitted by the interassembly gaps allow removal and replacement of the various reactor core assemblies. During an increase in reactor temperature from refueling to hot standby, the bimetallic spine expands, bowing the assembly toward the core center line, exerting a radially inward gap-closing-force on the above core load plane of the reactor core assembly, closing load plane interassembly gaps throughout the core prior to startup and preventing positive reactivity insertion.

  11. Pre-bomb marine reservoir ages in the western north Pacific: Preliminary result on Kyoto University collection

    NASA Astrophysics Data System (ADS)

    Yoneda, Minoru; Kitagawa, Hiroyuki; van der Plicht, Johannes; Uchida, Masao; Tanaka, Atsushi; Uehiro, Takashi; Shibata, Yasuyuki; Morita, Masatoshi; Ohno, Terufumi

    2000-10-01

    The calibration of radiocarbon dates on marine materials involves a global marine calibration with regional corrections. The marine reservoir ages in the Western North Pacific have not been discussed, while it is quite important to determine the timing of palaeo-environmental changes as well as archaeological interpretation around this region. The lack of adequate collection of the pre-bomb shell from western north Pacific was the biggest problem. Recently we had a chance to examine specimens from an old shell collection stored in Kyoto University, including shell specimens from Japan, Korea, Taiwan and the Micronesia of 1920s and 1930s. We explored the possibility for usage of specimen without clear evidence of live collection by measuring 30 apparent radiocarbon ages of pre-bomb mollusk shells from 18 sites in Western North Pacific. The preliminary results showed several discrepancies with previously reported results and with each other. We have to carefully select the shell specimen that has biological signs such as articulating fulcrum. In order to exploit this big resource of pre-bomb shell collection, the new technique to distinguish fossils from live collected samples should be developed by using chemical and physical methods.

  12. Student research in criticality safety at the University of Arizona

    SciTech Connect

    Hetrick, D.L.

    1997-06-01

    A very brief progress report on four University of Arizona student projects is given. Improvements were made in simulations of power pulses in aqueous solutions, including the TWODANT model. TWODANT calculations were performed to investigate the effect of assembly shape on the expansion coefficient of reactivity for solutions. Preliminary calculations were made of critical heights for the Los Alamos SHEBA assembly. Calculations to support French experiments to measure temperature coefficients of dilute plutonium solutions confirmed feasibility.

  13. Benchmark Evaluation of the Medium-Power Reactor Experiment Program Critical Configurations

    SciTech Connect

    Margaret A. Marshall; John D. Bess

    2013-02-01

    A series of small, compact critical assembly (SCCA) experiments were performed in 1962-1965 at the Oak Ridge National Laboratory Critical Experiments Facility (ORCEF) for the Medium-Power Reactor Experiment (MPRE) program. The MPRE was a stainless-steel clad, highly enriched uranium (HEU)-O2 fuelled, BeO reflected reactor design to provide electrical power to space vehicles. Cooling and heat transfer were to be achieved by boiling potassium in the reactor core and passing vapor directly through a turbine. Graphite- and beryllium-reflected assemblies were constructed at ORCEF to verify the critical mass, power distribution, and other reactor physics measurements needed to validate reactor calculations and reactor physics methods. The experimental series was broken into three parts, with the third portion of the experiments representing the beryllium-reflected measurements. The latter experiments are of interest for validating current reactor design efforts for a fission surface power reactor. The entire series has been evaluated as acceptable benchmark experiments and submitted for publication in the International Handbook of Evaluated Criticality Safety Benchmark Experiments and in the International Handbook of Evaluated Reactor Physics Benchmark Experiments.

  14. Automatic coolant flow control device for a nuclear reactor assembly

    DOEpatents

    Hutter, E.

    1984-01-27

    A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.

  15. SCALE-4 Analysis of LaSalle Unit 1 BWR Commercial Reactor Critical Configurations

    SciTech Connect

    Gauld, I.C.

    2000-03-01

    Five commercial reactor criticals (CRCs) for the LaSalle Unit 1 boiling-water reactor have been analyzed using KENO V.a, the Monte Carlo criticality code of the SCALE 4 code system. The irradiated fuel assembly isotopics for the criticality analyses were provided by the Waste Package Design team at the Yucca Mountain Project in the US, who performed the depletion calculations using the SAS2H sequence of SCALE 4. The reactor critical measurements involved two beginning-of-cycle and three middle-of-cycle configurations. The CRCs involved relatively low-cycle burnups, and therefore contained a relatively high gadolinium poison content in the reactor assemblies. This report summarizes the data and methods used in analyzing the critical configurations and assesses the sensitivity of the results to some of the modeling approximations used to represent the gadolinium poison distribution within the assemblies. The KENO V.a calculations, performed using the SCALE 44GROUPNDF5 ENDF/B-V cross-section library, yield predicted k{sub eff} values within about 1% {Delta}k/k relative to reactor measurements for the five CRCs using general 8-pin and 9-pin heterogeneous gadolinium poison pin assembly models.

  16. SCALE-4 Analysis of LaSalle Unit 1 BWR Commercial Reactor Critical Configuration

    SciTech Connect

    Gauld, I.C.

    2000-03-16

    Five commercial reactor criticals (CRCs) for the LaSalle Unit 1 boiling-water reactor have been analyzed using KENO V.a, the Monte Carlo criticality code of the SCALE 4 code system. The irradiated fuel assembly isotopics for the criticality analyses were provided by the Waste Package Design team at the Yucca Mountain Project in the United States, who performed the depletion calculations using the SAS2H sequence of SCALE 4. The reactor critical measurements involved two beginning-of-cycle and three middle-of-cycle configurations. The CRCs involved relatively low-cycle burnups, and therefore contained a relatively high gadolinium poison content in the reactor assemblies. This report summarizes the data and methods used in analyzing the critical configurations and assesses the sensitivity of the results to some of the modeling approximations used to represent the gadolinium poison distribution within the assemblies. The KENO V.a calculations, performed using the SCALE 44GROUPNDF5 ENDF/B-V cross-section library, yield predicted k{sub eff} values within about 1% {Delta}k/k relative to reactor measurements for the five CRCs using general 8-pin and 9-pin heterogeneous gadolinium poison pin assembly models.

  17. Safety analysis report for the Hanford Critical Mass Laboratory: Supplement No. 2. Experiments with heterogeneous assemblies

    SciTech Connect

    Gore, B.F.; Davenport, L.C.

    1981-04-01

    Factors affecting the safety of criticality experiments using heterogeneous assemblies are described and assessed. It is concluded that there is no substantial change in safety from experiments already being routinely performed at the Critical Mass Laboratory (CML), and that laboratory and personnel safety are adequately provided by the combination of engineered and administrative safety limits enforced at the CML. This conclusion is based on the analysis of operational controls, potential hazards, and the consequences of accidents. Contingencies considered that could affect nuclear criticality include manual changes in fuel loadings, water flooding, fire, explosion, loss of services, earthquake, windstorm, and flood. Other potential hazards considered include radiation exposure to personnel, and potential releases within the Assembly Room and outside to the environment. It is concluded that the Maximum Credible Nuclear Burst of 3 x 10/sup 18/ fissions (which served as the design basis for the CML) is valid for heterogeneous assemblies as well as homogeneous assemblies. This is based upon examination of the results of reactor destructive tests and the results of the SL-1 reactor destructive accident. The production of blast effects which might jeopardize the CML critical assembly room (of thick reinforced concrete) is not considered credible due to the extreme circumstances required to produce blast effects in reactor destructive tests. Consequently, it is concluded that, for experiments with heterogeneous assemblies, the consequences of the Maximum Credible Burst are unchanged from those previously estimated for experiments with homogeneous systems.

  18. Criticality safety analysis on fissile materials in Fukushima reactor cores

    SciTech Connect

    Liu, Xudong; Lemaitre-Xavier, E.; Ahn, Joonhong; Hirano, Fumio

    2013-07-01

    The present study focuses on the criticality analysis for geological disposal of damaged fuels from Fukushima reactor cores. Starting from the basic understanding of behaviors of plutonium and uranium, a scenario sequence for criticality event is considered. Due to the different mobility of plutonium and uranium in geological formations, the criticality safety is considered in two parts: (1) near-field plutonium system and (2) far-field low enriched uranium (LEU) system. For the near-field plutonium system, a mathematical analysis for pure-solute transport was given, assuming a particular buffer material and waste form configuration. With the transport and decay of plutonium accounted, the critical mass of plutonium was compared with the initial load of a single canister. Our calculation leads us to the conclusion that our system with the initial loading being the average mass of plutonium in an assembly just before the accident is very unlikely to become critical over time. For the far-field LEU system, due to the uncertainties in the geological and geochemical conditions, calculations were made in a parametric space that covers the variation of material compositions and different geometries. Results show that the LEU system could not remain sub-critical within the entire parameter space assumed, although in the iron-rich rock, the neutron multiplicity is significantly reduced.

  19. Use of Sensitivity and Uncertainty Analysis in the Design of Reactor Physics and Criticality Benchmark Experiments for Advanced Nuclear Fuel

    SciTech Connect

    Rearden, B.T.; Anderson, W.J.; Harms, G.A.

    2005-08-15

    Framatome ANP, Sandia National Laboratories (SNL), Oak Ridge National Laboratory (ORNL), and the University of Florida are cooperating on the U.S. Department of Energy Nuclear Energy Research Initiative (NERI) project 2001-0124 to design, assemble, execute, analyze, and document a series of critical experiments to validate reactor physics and criticality safety codes for the analysis of commercial power reactor fuels consisting of UO{sub 2} with {sup 235}U enrichments {>=}5 wt%. The experiments will be conducted at the SNL Pulsed Reactor Facility.Framatome ANP and SNL produced two series of conceptual experiment designs based on typical parameters, such as fuel-to-moderator ratios, that meet the programmatic requirements of this project within the given restraints on available materials and facilities. ORNL used the Tools for Sensitivity and Uncertainty Analysis Methodology Implementation (TSUNAMI) to assess, from a detailed physics-based perspective, the similarity of the experiment designs to the commercial systems they are intended to validate. Based on the results of the TSUNAMI analysis, one series of experiments was found to be preferable to the other and will provide significant new data for the validation of reactor physics and criticality safety codes.

  20. University Reactor Conversion Lessons Learned Workshop for Texas A&M University Nuclear Science Center Reactor

    SciTech Connect

    Eric C. Woolstenhulme; Dana M. Meyer

    2007-04-01

    The objectives of this meeting were to capture the observations, insights, issues, concerns, and ideas of those involved in the Texas A&M University Nuclear Science Center (TAMU NSC) TRIGA Reactor Conversion so that future efforts can be conducted with greater effectiveness, efficiency, and with fewer challenges. This workshop was held in conjunction with a similar workshop for the University of Florida Reactor Conversion. Some of the generic lessons from that workshop are included in this report for completeness.

  1. Sharing of the RPI Reactor Critical Facility (RCF). Final summary report, January 1988--September 1995

    SciTech Connect

    Harris, D.R.

    1995-09-01

    Rensselaer Polytechnic Institute (RPI) has participated for a number of years in Sharing of the Reactor Critical Facility (RCF) under the U.S. Department of Energy University Reactor Sharing Program. In September of each year a Sharing invitation is sent to 92 public and private high schools and to 74 colleges and universities within about a 3 hour drive to the RCF (Appendix B). Each year about 10 such educational institutions send groups to share the RCF.

  2. Temperature measuring analysis of the nuclear reactor fuel assembly

    NASA Astrophysics Data System (ADS)

    F., Urban; Ľ., Kučák; Bereznai, J.; Závodný, Z.; Muškát, P.

    2014-08-01

    Study was based on rapid changes of measured temperature values from the thermocouple in the VVER 440 nuclear reactor fuel assembly. Task was to determine origin of fluctuations of the temperature values by experiments on physical model of the fuel assembly. During an experiment, heated water was circulating in the system and cold water inlet through central tube to record sensitivity of the temperature sensor. Two positions of the sensor was used. First, just above the central tube in the physical model fuel assembly axis and second at the position of the thermocouple in the VVER 440 nuclear reactor fuel assembly. Dependency of the temperature values on time are presented in the diagram form in the paper.

  3. Detachable connection for a nuclear reactor fuel assembly

    DOEpatents

    Christiansen, D.W.; Karnesky, R.A.

    1983-08-29

    A locking connection for releasably attaching a handling socket to the duct tube of a fuel assembly for a nuclear reactor. The connection comprises a load pad housing mechanically attached to the duct tube and a handling socket threadably secured within the housing. A retaining ring is interposed between the housing and the handling socket and is formed with a projection and depression engagable within a cavity and groove of the housing and handling socket, respectively, to form a detachable interlocked connection assembly.

  4. Detachable connection for a nuclear reactor fuel assembly

    DOEpatents

    Christiansen, David W.; Karnesky, Richard A.

    1986-01-01

    A locking connection for releasably attaching a handling socket to the duct tube of a fuel assembly for a nuclear reactor. The connection comprises a load pad housing mechanically attached to the duct tube and a handling socket threadably secured within the housing. A retaining ring is interposed between the housing and the handling socket and is formed with a projection and depression engageable within a cavity and groove of the housing and handling socket, respectively, to form a detachable interlocked connection assembly.

  5. TRIPOLI-4 criticality calculations for MOX fuelled SNEAK 7A and 7B fast critical assemblies

    SciTech Connect

    Lee, Y. K.

    2012-07-01

    A prototype Generation IV fast neutron reactor is under design and development in France. The MOX fuel will be introduced into this self-generating core in order to demonstrate low net plutonium production. To support the TRIPOLI-4 Monte Carlo transport code in criticality calculations of fast reactors, the effective delayed neutron fraction {beta}eff estimation and the Probability Tables (PT) option to treat the unresolved resonance region of cross-sections are two essentials. In this study, TRIPOLI-4 calculations have been made using current nuclear data libraries JEFF-3.1.1 and ENDF/B-VII.0 to benchmark the reactor physics parameters of the MOX fuelled SNEAK 7A and 7B fast critical assemblies. TRIPOLI-4 calculated K{sub eff} and {beta}eff of the homogeneous R-Z models and the 3D multi-cell models have been validated against the measured ones. The impact of the PT option on K{sub eff} is 340 {+-} 10 pcm for SNEAK 7A core and 410 {+-} 12 pcm for 7B. Four-group spectra and energy spectral indices, f8/f5, f9/f5, and c8/f5 in the two SNEAK cores have also been calculated with the TRIPOLI-4 mesh tally. Calculated spectrum-hardening index f8/f5 is 0.0418 for SNEAK 7A and 0.0315 for 7B. From this study the SNEAK 3D models have been verified for the next revision of IRPhE (International Handbook of Evaluated Reactor Physics Benchmark Experiments). (authors)

  6. Advanced Plasma Pyrolysis Assembly (PPA) Reactor and Process Development

    NASA Technical Reports Server (NTRS)

    Wheeler, Richard R., Jr.; Hadley, Neal M.; Dahl, Roger W.; Abney, Morgan B.; Greenwood, Zachary; Miller, Lee; Medlen, Amber

    2012-01-01

    Design and development of a second generation Plasma Pyrolysis Assembly (PPA) reactor is currently underway as part of NASA's Atmosphere Revitalization Resource Recovery effort. By recovering up to 75% of the hydrogen currently lost as methane in the Sabatier reactor effluent, the PPA helps to minimize life support resupply costs for extended duration missions. To date, second generation PPA development has demonstrated significant technology advancements over the first generation device by doubling the methane processing rate while, at the same time, more than halving the required power. One development area of particular interest to NASA system engineers is fouling of the PPA reactor with carbonaceous products. As a mitigation plan, NASA MSFC has explored the feasibility of using an oxidative plasma based upon metabolic CO2 to regenerate the reactor window and gas inlet ports. The results and implications of this testing are addressed along with the advanced PPA reactor development.

  7. Universities and Globalization: Critical Perspectives.

    ERIC Educational Resources Information Center

    Currie, Jan, Ed.; Newson, Janice, Ed.

    The 14 papers in this collection examine how a globalizing political economy affects the way universities are governed, discussing practices such as managerialism, accountability, and privatization which represent a shift toward business values and a market agenda. Part 1 gives a theoretical overview of the globalization agenda. Part 2 gives three…

  8. University Rankings in Critical Perspective

    ERIC Educational Resources Information Center

    Pusser, Brian; Marginson, Simon

    2013-01-01

    This article addresses global postsecondary ranking systems by using critical-theoretical perspectives on power. This research suggests rankings are at once a useful lens for studying power in higher education and an important instrument for the exercise of power in service of dominant norms in global higher education. (Contains 1 table and 1…

  9. Reactor cell assembly for use in spectroscopy and microscopy applications

    DOEpatents

    Grindstaff, Quirinus; Stowe, Ashley Clinton; Smyrl, Norm; Powell, Louis; McLane, Sam

    2015-08-04

    The present disclosure provides a reactor cell assembly that utilizes a novel design and that is wholly or partially manufactured from Aluminum, such that reactions involving Hydrogen, for example, including solid-gas reactions and thermal decomposition reactions, are not affected by any degree of Hydrogen outgassing. This reactor cell assembly can be utilized in a wide range of optical and laser spectroscopy applications, as well as optical microscopy applications, including high-temperature and high-pressure applications. The result is that the elucidation of the role of Hydrogen in the reactions studied can be achieved. Various window assemblies can be utilized, such that high temperatures and high pressures can be accommodated and the signals obtained can be optimized.

  10. Sharing of Rensselaer Polytechnic Institute Reactor Critical Facility (RCF)

    SciTech Connect

    1995-11-30

    The RPI Reactor Critical Facility (RCF) operated successfully over the period fall 1994 - fall 1995. During this period, the RCF was used for Critical Reactor Laboratory spring 1995 (12 students); Reactor Operations Training fall 1994 (3 students); Reactor Operations Training spring 1995 (3 students); and Reactor Operations Training fall 1995 (3 students). Thirty-two Instrumentation and Measurement students used the RCF for one class for hands-on experiments with nuclear instruments. In addition, a total of nine credits of PhD thesis work were carried out at the RCF. This document constitutes the 1995 Report of the Rensselaer Polytechnic Institute`s Reactor Critical Facility (RCF) to the USNRC, to the USDOE, and to RPI management.

  11. Critical experiments at Sandia National Laboratories : technical meeting on low-power critical facilities and small reactors.

    SciTech Connect

    Harms, Gary A.; Ford, John T.; Barber, Allison Delo

    2010-11-01

    Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE since the 1960's. Over this period, the research reactor facilities at Sandia have had a primary mission to provide appropriate nuclear radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor III (SPR-III), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The SPR-III is currently defueled. The SPR Facility (SPRF) has hosted a series of critical experiments. A purpose-built critical experiment was first operated at the SPRF in the late 1980's. This experiment, called the Space Nuclear Thermal Propulsion Critical Experiment (CX), was designed to explore the reactor physics of a nuclear thermal rocket motor. This experiment was fueled with highly-enriched uranium carbide fuel in annular water-moderated fuel elements. The experiment program was completed and the fuel for the experiment was moved off-site. A second critical experiment, the Burnup Credit Critical Experiment (BUCCX) was operated at Sandia in 2002. The critical assembly for this experiment was based on the assembly used in the CX modified to accommodate low-enriched pin-type fuel in water moderator. This experiment was designed as a platform in which the reactivity effects of specific fission product poisons could be measured. Experiments were carried out on rhodium, an important fission product poison. The fuel and assembly hardware for the BUCCX remains at Sandia and is available for future experimentation. The critical experiment currently in operation at the SPRF is the Seven Percent Critical Experiment (7uPCX). This experiment is designed to provide benchmark

  12. The World Nuclear University Alumni Assembly

    SciTech Connect

    White-Horton, Jessica L; Lynch, Patrick D; Gilligan, Kimberly V; Garner, James R; Guzzardo, Tyler; Kuhn, Michael J; Rowe, Nathan C

    2014-01-01

    The World Nuclear University Summer Institute was established by the World Nuclear Association in 2005 as a program for future leaders in the nuclear field. Since the Summer Institute s inception in 2005, a total of some 800 fellows from more than 70 countries have participated in the program. In 2012, the World Nuclear University held its first ever alumni event at the IAEA in Vienna, Austria, and at that time, the precedent was set that the reunion would be held biennially. The 2014 alumni assembly was held at Oak Ridge National Laboratory from March 31 April 4, 2014. The event offered three separate areas of opportunities for the participating alumni: professional development, leadership, and peer-to-peer engagement. The professional development consisted of training groups, while the leadership will involve discussions with invited leaders, including members of the Blue Ribbon Commission. The peer-to-peer engagement not only give past fellows a chance to reconnect with their own classmates, but it allowed for further international engagement, between the speakers and alumni, as well as between the classes themselves.

  13. Criticality Analysis of Assembly Misload in a PWR Burnup Credit Cask

    SciTech Connect

    Wagner, J. C.

    2008-01-31

    The Interim Staff Guidance on bumup credit (ISG-8) for spent fuel in storage and transportation casks, issued by the Nuclear Regulatory Commission's Spent Fuel Project Office, recommends a bumup measurement for each assembly to confirm the reactor record and compliance with the assembly bumup value used for loading acceptance. This recommendation is intended to prevent unauthorized loading (misloading) of assemblies due to inaccuracies in reactor burnup records and/or improper assembly identification, thereby ensuring that the appropriate subcritical margin is maintained. This report presents a computational criticality safety analysis of the consequences of misloading fuel assemblies in a highcapacity cask that relies on burnup credit for criticality safety. The purpose of this report is to provide a quantitative understanding of the effects of fuel misloading events on safety margins. A wide variety of fuel-misloading configurations are investigated and results are provided for informational purposes. This report does not address the likelihood of occurrence for any of the misload configurations considered. For representative, qualified bumup-enrichment combinations, with and without fission products included, misloading two assemblies that are underburned by 75% results in an increase in keff of 0.025-0.045, while misloading four assemblies that are underburned by 50% also results in an increase in keff of 0.025-0.045. For the cask and conditions considered, a reduction in bumup of 20% in all assemblies results in an increase in kff of less than 0.035. Misloading a single fresh assembly with 3, 4, or 5 wt% 235U enrichment results in an increase in keffof--0.02, 0.04, or 0.06, respectively. The report concludes with a summary of these and other important findings, as well as a discussion of relevant issues that should be considered when assessing the appropriate role of burnup measurements.

  14. The Assembly on University Goals and Governance. A First Report.

    ERIC Educational Resources Information Center

    American Academy of Arts and Sciences, Boston, MA.

    The Assembly on University Goals and Governance was established by the American Academy of Arts and Sciences in September 1969 to explore, develop, and help implement alternative approaches for resolving certain of the issues affecting colleges and universities today. This report presents the 85 theses that were developed by the Assembly. The…

  15. Physical characteristics of GE (General Electric) BWR (boiling-water reactor) fuel assemblies

    SciTech Connect

    Moore, R.S.; Notz, K.J.

    1989-06-01

    The physical characteristics of fuel assemblies manufactured by the General Electric Company for boiling-water reactors are classified and described. The classification into assembly types is based on the GE reactor product line, the Characteristics Data Base (CDB) assembly class, and the GE fuel design. Thirty production assembly types are identified. Detailed physical data are presented for each assembly type in an appendix. Descriptions of special (nonstandard) fuels are also reported. 52 refs., 1 fig., 6 tabs.

  16. Covariance Applications in Criticality Safety, Light Water Reactor Analysis, and Spent Fuel Characterization

    NASA Astrophysics Data System (ADS)

    Williams, M. L.; Wiarda, D.; Ilas, G.; Marshall, W. J.; Rearden, B. T.

    2015-01-01

    A new covariance data library based on ENDF/B-VII.1 was recently processed for the SCALE nuclear analysis code system. The multigroup covariance data are discussed here, along with testing and application results for critical benchmark experiments. The cross section covariance library, along with covariances for fission product yields and decay data, is used to compute uncertainties in the decay heat produced by a burned reactor fuel assembly.

  17. Covariance Applications in Criticality Safety, Light Water Reactor Analysis, and Spent Fuel Characterization

    DOE PAGES

    Williams, M. L.; Wiarda, D.; Ilas, G.; Marshall, W. J.; Rearden, B. T.

    2014-06-15

    Recently, we processed a new covariance data library based on ENDF/B-VII.1 for the SCALE nuclear analysis code system. The multigroup covariance data are discussed here, along with testing and application results for critical benchmark experiments. Moreover, the cross section covariance library, along with covariances for fission product yields and decay data, is used to compute uncertainties in the decay heat produced by a burned reactor fuel assembly.

  18. Covariance Applications in Criticality Safety, Light Water Reactor Analysis, and Spent Fuel Characterization

    SciTech Connect

    Williams, M.L. Wiarda, D.; Ilas, G.; Marshall, W.J.; Rearden, B.T.

    2015-01-15

    A new covariance data library based on ENDF/B-VII.1 was recently processed for the SCALE nuclear analysis code system. The multigroup covariance data are discussed here, along with testing and application results for critical benchmark experiments. The cross section covariance library, along with covariances for fission product yields and decay data, is used to compute uncertainties in the decay heat produced by a burned reactor fuel assembly.

  19. Neutronics for critical fission reactors and subcritical fission in hybrids

    NASA Astrophysics Data System (ADS)

    Salvatores, Massimo

    2012-06-01

    The requirements of future innovative nuclear fuel cycles will focus on safety, sustainability and radioactive waste minimization. Critical fast neutron reactors and sub-critical, external source driven systems (accelerator driven and fusion-fission hybrids) have a potential role to meet these requirements in view of their physics characteristics. This paper provides a short introduction to these features.

  20. Neutronics for critical fission reactors and subcritical fission in hybrids

    SciTech Connect

    Salvatores, Massimo

    2012-06-19

    The requirements of future innovative nuclear fuel cycles will focus on safety, sustainability and radioactive waste minimization. Critical fast neutron reactors and sub-critical, external source driven systems (accelerator driven and fusion-fission hybrids) have a potential role to meet these requirements in view of their physics characteristics. This paper provides a short introduction to these features.

  1. Passive gamma analysis of the boiling-water-reactor assemblies

    DOE PAGES

    Vo, D.; Favalli, A.; Grogan, B.; Jansson, P.; Liljenfeldt, H.; Mozin, V.; Schwalbach, P.; Sjöland, A.; Tobin, S.; Trellue, H.; et al

    2016-06-04

    This research focused on the analysis of a set of stationary passive gamma measurements taken on the spent nuclear fuel assemblies from a boiling water reactor (BWR) using pulse height analysis data acquisition. The measurements were performed on 25 different BWR assemblies in 2014 at Sweden’s Central Interim Storage Facility for Spent Nuclear Fuel (Clab). This study was performed as part of the Next Generation of Safeguards Initiative–Spent Fuel project to research the application of nondestructive assay (NDA) to spent fuel assemblies. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in themore » past using nondestructive assay (NDA) measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins, (3) estimate the plutonium mass, (4) estimate the decay heat, and (5) determine the reactivity of spent fuel assemblies. The final objective of this project is to quantify the capability of several integrated NDA instruments to meet the aforementioned goals using the combined signatures of neutrons, gamma rays, and heat. This report presents a selection of the measured data and summarizes an analysis of the results. Specifically, trends in the count rates measured for spectral lines from the following isotopes were analyzed as a function of the declared burnup and cooling time: 137Cs, 154Eu, 134Cs, and to a lesser extent, 106Ru and 144Ce. From these measured count rates, predictive algorithms were developed to enable the estimation of the burnup and cooling time. Furthermore, these algorithms were benchmarked on a set of assemblies not included in the standard assemblies set used by this research team.« less

  2. Passive gamma analysis of the boiling-water-reactor assemblies

    NASA Astrophysics Data System (ADS)

    Vo, D.; Favalli, A.; Grogan, B.; Jansson, P.; Liljenfeldt, H.; Mozin, V.; Schwalbach, P.; Sjöland, A.; Tobin, S.; Trellue, H.; Vaccaro, S.

    2016-09-01

    This research focused on the analysis of a set of stationary passive gamma measurements taken on the spent nuclear fuel assemblies from a boiling water reactor (BWR) using pulse height analysis data acquisition. The measurements were performed on 25 different BWR assemblies in 2014 at Sweden's Central Interim Storage Facility for Spent Nuclear Fuel (Clab). This study was performed as part of the Next Generation of Safeguards Initiative-Spent Fuel project to research the application of nondestructive assay (NDA) to spent fuel assemblies. The NGSI-SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay (NDA) measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins, (3) estimate the plutonium mass, (4) estimate the decay heat, and (5) determine the reactivity of spent fuel assemblies. The final objective of this project is to quantify the capability of several integrated NDA instruments to meet the aforementioned goals using the combined signatures of neutrons, gamma rays, and heat. This report presents a selection of the measured data and summarizes an analysis of the results. Specifically, trends in the count rates measured for spectral lines from the following isotopes were analyzed as a function of the declared burnup and cooling time: 137Cs, 154Eu, 134Cs, and to a lesser extent, 106Ru and 144Ce. From these measured count rates, predictive algorithms were developed to enable the estimation of the burnup and cooling time. Furthermore, these algorithms were benchmarked on a set of assemblies not included in the standard assemblies set used by this research team.

  3. Universal entanglement spectra in critical spin chains

    NASA Astrophysics Data System (ADS)

    Lundgren, Rex; Blair, Jonathan; Laurell, Pontus; Regnault, Nicolas; Fiete, Gregory A.; Greiter, Martin; Thomale, Ronny

    2016-08-01

    We advocate that in critical spin chains, and possibly in a larger class of one-dimensional critical models, a gap in the momentum-space entanglement spectrum separates the universal part of the spectrum, which is determined by the associated conformal field theory, from the nonuniversal part, which is specific to the model. To this end, we provide affirmative evidence from multicritical spin chains with low-energy sectors described by the SU(2 ) 2 or the SU(3 ) 1 Wess-Zumino-Witten model.

  4. Individual source positioning mechanism for a nuclear reactor fuel assembly

    SciTech Connect

    Wilson, J.F.; Gjertsen, R.K.; Cerni, S.

    1987-07-07

    A nuclear reactor is described including a fuel assembly, at lest one elongated neutron source rod and an upper core plate. The fuel assembly has top and bottom nozzles with a guide thimbles extending between and interconnecting the nozzles. The upper core plate is positioned adjacent to and above the top nozzle of the fuel assembly and having flow openings to allow passage of coolant from the fuel assembly. At least some of the openings is aligned over respective ones of the guide thimbles with seating means defined about the openings on a lower side of the core plate, a separate mechanism for positioning each individual neutron source rod in a respective guide thimble aligned with one of the openings defined through the upper core plate, comprising: (a) locating means registering against the core plate seating means; and (b) resilient holddown means extending partially into the guide thimble and coupling the source rod with the locating means in a manner which restrains the source rod in a lateral direction and positions the rod in a stationary axial relationship within the guide thimble.

  5. Self-assembled nanoparticle-stabilized photocatalytic reactors

    NASA Astrophysics Data System (ADS)

    Burdyny, Thomas; Riordon, Jason; Dinh, Cao-Thang; Sargent, Edward H.; Sinton, David

    2016-01-01

    The efficiency of nanostructured photocatalysts continues to improve at an impressive pace and is closing in on those needed for commercial applications; however, present-day reactor strategies used to deploy these nanostructures fail to achieve the sufficient areas (>1 m2) needed for solar application. Here we report the Self-assembled Nanoparticle-stabilized Photocatalytic Reactor (SNPR), a fully-scalable reactor strategy comprised only of nanoparticles adsorbed at the fluid-fluid interfaces of oil-in-water emulsions, water-in-oil emulsions, and CO2-in-water foams. We show that SNPRs naturally disperse over open water and need no physical substrate, requiring only photocatalysts and fluid. In environmental applications the SNPR provides more than double the reaction rate of a comparable single-phase reactor. In continuous mode, the SNPR achieves 100% photocatalyst retention and processes 96% of the stream over 20 hours; in contrast, the performance of a comparable aqueous suspension declines to zero over this interval, losing all photocatalyst to the outlet stream. We further characterize the photoactivity of individual photocatalytic droplets, with reactants in both the continuous and dispersed phases. These results demonstrate SNPRs as a robust and flexible reactor strategy and a route-to-scale for nanomaterials.The efficiency of nanostructured photocatalysts continues to improve at an impressive pace and is closing in on those needed for commercial applications; however, present-day reactor strategies used to deploy these nanostructures fail to achieve the sufficient areas (>1 m2) needed for solar application. Here we report the Self-assembled Nanoparticle-stabilized Photocatalytic Reactor (SNPR), a fully-scalable reactor strategy comprised only of nanoparticles adsorbed at the fluid-fluid interfaces of oil-in-water emulsions, water-in-oil emulsions, and CO2-in-water foams. We show that SNPRs naturally disperse over open water and need no physical substrate

  6. 76 FR 14436 - University of Wisconsin, University of Wisconsin Nuclear Reactor; Notice of Issuance of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-16

    ... COMMISSION University of Wisconsin, University of Wisconsin Nuclear Reactor; Notice of Issuance of... Register on September 16, 2010 (75 FR 56597), which informed the public that the U.S. Nuclear Regulatory... which would authorize continued operation of the University of Wisconsin Nuclear Reactor. This action...

  7. Scale-4 Analysis of Pressurized Water Reactor Critical Configurations: Volume 3-Surry Unit 1 Cycle 2

    SciTech Connect

    Bowman, S.M.

    1995-01-01

    The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor criticality safety analyses be validated against experimental measurements. If credit for the negative reactivity of the depleted (or spent) fuel isotopics is desired, it is necessary to benchmark computational methods against spent fuel critical configurations. This report summarizes a portion of the ongoing effort to benchmark away-from-reactor criticality analysis methods using selected critical configurations from commercial pressurized-water reactors. The analysis methodology selected for all the calculations in this report is based on the codes and data provided in the SCALE-4 code system. The isotopic densities for the spent fuel assemblies in the critical configurations were calculated using the SAS2H analytical sequence of the SCALE-4 system. The sources of data and the procedures for deriving SAS2H input parameters are described in detail. The SNIKR code module was used to extract the necessary isotopic densities from the SAS2H results and to provide the data in the format required by the SCALE criticality analysis modules. The CSASN analytical sequence in SCALE-4 was used to perform resonance processing of the cross sections. The KENO V.a module of SCALE-4 was used to calculate the effective multiplication factor (k{sub eff}) of each case. The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides) and ENDF/B-V (fission products) data was used for all the calculations. This volume of the report documents the SCALE system analysis of two reactor critical configurations for Surry Unit 1 Cycle 2. This unit and cycle were chosen for a previous analysis using a different methodology because detailed isotopics from multidimensional reactor calculations were available from the Virginia Power Company. These data permitted a direct comparison of criticality calculations using the utility-calculated isotopics with those using the isotopics generated by the SCALE-4

  8. U.S. Department of Energy University Reactor Instrumentation Program Final Report for 1992-94 Grant for the University of Florida Training Reactor

    SciTech Connect

    Vernetson, William G.

    1999-04-01

    Overall, the instrumentation obtained under the first year 1992-93 University Reactor Instrumentation Program grant assured that the goals of the program were well understood and met as well as possible at the level of support provided for the University of Florida Training Reactor facility. Though the initial grant support of $21,000 provided toward the purchase of $23,865 of proposed instrumentation certainly did not meet many of the facility's needs, the instrumentation items obtained and implemented did meet some critical needs and hence the goals of the Program to support modernization and improvement of reactor facilities such as the UFTR within the academic community. Similarly, the instrumentation obtained under the second year 1993-94 University Reactor Instrumentation Program grant again met some of the critical needs for instrumentation support at the UFTR facility. Again, though the grant support of $32,799 for proposed instrumentation at the same cost projection does not need all of the facility's needs, it does assure continued facility viability and improvement in operations. Certainly, reduction of forced unavailability of the reactor is the most obvious achievement of the University Reactor Instrumentation Program to date at the UFTR. Nevertheless, the ability to close out several expressed-inspection concerns of the Nuclear Regulatory Commission with acquisition of the low level survey meter and the area radiation monitoring system is also very important. Most importantly, with modest cost sharing the facility has been able to continue and even accelerate the improvement and modernization of a facility, especially in the Neutron Activation Analysis Laboratory, that is used by nearly every post-secondary school in the State of Florida and several in other states, by dozens of departments within the University of Florida, and by several dozen high schools around the State of Florida on a regular basis. Better, more reliable service to such a broad

  9. Consistent Pl Analysis of Aqueous Uranium-235 Critical Assemblies

    NASA Technical Reports Server (NTRS)

    Fieno, Daniel

    1961-01-01

    The lethargy-dependent equations of the consistent Pl approximation to the Boltzmann transport equation for slowing down neutrons have been used as the basis of an IBM 704 computer program. Some of the effects included are (1) linearly anisotropic center of mass elastic scattering, (2) heavy element inelastic scattering based on the evaporation model of the nucleus, and (3) optional variation of the buckling with lethargy. The microscopic cross-section data developed for this program covered 473 lethargy points from lethargy u = 0 (10 Mev) to u = 19.8 (0.025 ev). The value of the fission neutron age in water calculated here is 26.5 square centimeters; this value is to be compared with the recent experimental value given as 27.86 square centimeters. The Fourier transform of the slowing-down kernel for water to indium resonance energy calculated here compared well with the Fourier transform of the kernel for water as measured by Hill, Roberts, and Fitch. This method of calculation has been applied to uranyl fluoride - water solution critical assemblies. Theoretical results established for both unreflected and fully reflected critical assemblies have been compared with available experimental data. The theoretical buckling curve derived as a function of the hydrogen to uranium-235 atom concentration for an energy-independent extrapolation distance was successful in predicting the critical heights of various unreflected cylindrical assemblies. The critical dimensions of fully water-reflected cylindrical assemblies were reasonably well predicted using the theoretical buckling curve and reflector savings for equivalent spherical assemblies.

  10. Reactivity effects of void formations in a solution critical assembly

    SciTech Connect

    Walters, S.G.

    1994-01-01

    SHEBA II (Solution High Energy Burst Assembly) was constructed in order to better understand the neutronics of solutions of fissile materials. In order to estimate the effect on criticality from the formation of bubbles, models were devised in MCNP (Monte Carlo Neutron Photon transport code) and THREEDANT (THREE dimensional, Diffusion-Accelerated, Neutral-Particle Transport). It was found that the formation of voids in all but the outside bottom edge of the assembly cylinder tend to act as a negative insertion of reactivity. Also, an experiment has been designed which will verify the results of the codes.

  11. Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods

    SciTech Connect

    Margaret A. Marshall

    2013-03-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s (ORNL’s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study “power plants for the production of electrical power in space vehicles.”(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.”(Reference 1) The experiment studied in this evaluation was the first of the series and had the fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank. Two critical configurations were found by varying the amount of graphite reflector (References 1 and 2). Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, , and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configurations are described in Sections 1.3, 1.4 and 1.7, respectively. Information for this

  12. Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods

    SciTech Connect

    Margaret A. Marshall

    2012-09-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s (ORNL’s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study “power plants for the production of electrical power in space vehicles.”(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.”(Reference 1) The experiment studied in this evaluation was the first of the series and had the fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank. Two critical configurations were found by varying the amount of graphite reflector (References 1 and 2). Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, , and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configurations are described in Sections 1.3, 1.4 and 1.7, respectively. Information for this

  13. Criticality Safety Evaluation of a LLNL Training Assembly for Criticality Safety (TACS)

    SciTech Connect

    Heinrichs, D P

    2006-06-26

    Hands-on experimental training in the physical behavior of multiplying systems is one of ten key areas of training required for practitioners to become qualified in the discipline of criticality safety as identified in DOE-STD-1135-99, ''Guidance for Nuclear Criticality Safety Engineer Training and Qualification''. This document is a criticality safety evaluation of the training activities (or operations) associated with HS-3200, ''Laboratory Class for Criticality Safety''. These activities utilize the Training Assembly for Criticality Safety (TACS). The original intent of HS-3200 was to provide LLNL fissile material handlers with a practical hands-on experience as a supplement to the academic training they receive biennially in HS-3100, ''Fundamentals of Criticality Safety'', as required by ANSI/ANS-8.20-1991, ''Nuclear Criticality Safety Training''. HS-3200 is to be enhanced to also address the training needs of nuclear criticality safety professionals under the auspices of the NNSA Nuclear Criticality Safety Program.

  14. Performance Assessment of ISS Water Processor Assembly Reactor

    NASA Technical Reports Server (NTRS)

    Carter, Layne; Tatara, James; Mason, Rich; OConner, Ed; Bedard, John

    2004-01-01

    Due to modifications to the ISS waste water composition, the concentration of volatile organics has significantly increased in the feed to the Water Processor Assembly (WPA). In parallel, the oxygen supply pressure increased, resulting in a higher flow rate of oxygen to the WPA. Preliminary testing at Hamilton Sund strand indicated that the higher oxygen flow rate would increase the WPA capacity for volatile organics. Following an analysis of the expected waste water composition, personnel at NASA MSFC and Hamilton Sundstrand conducted a test of a flight-like reactor to assess its capacity for the higher organic loads. The results of this test indicate the WPA can accommodate the expected organic load in the ISS waste water with margin.

  15. Spent fuel assembly hardware: Characterization and 10 CFR 61 classification for waste disposal: Volume 3, Calculated activity profiles of spent nuclear fuel assembly hardware for boiling water reactors

    SciTech Connect

    Short, S.M.; Luksic, A.T.; Schutz, M.E.

    1989-06-01

    Consolidation of spent fuel is under active consideration as the US Department of Energy plans to dispose of spent fuel as required by the Nuclear Waste Policy Act of 1982. During consolidation, the fuel pins are removed from an intact fuel assembly and repackaged into a more compact configuration. After repackaging, approximately 30 kg of residual spent fuel assembly hardware per assembly that is also radioactive and required disposal. Understanding the nature of this secondary waste stream is critical to designing a system that will properly handle, package, store, and dispose of the waste. This report presents a methodology for estimating the radionuclide inventory in irradiated spent fuel hardware. Ratios are developed that allow the use of ORIGEN2 computer code calculations to be applied to regions that are outside the fueled region. The ratios are based on the analysis of samples of irradiated hardware from spent fuel assemblies. The results of this research are presented in three volumes. In Volume 1, the development of scaling factors that can be used with ORIGEN2 calculations to estimate activation of spent fuel assembly hardware is documented. The results from laboratory analysis of irradiated spent-fuel hardware samples are also presented in Volume 1. In Volume 2 and 3, the calculated flux profiles of spent nuclear fuel assemblies are presented for pressurized water reactors and boiling water reactors, respectively. The results presented in Volumes 2 and 3 were used to develop the scaling factors documented in Volume 1.

  16. Spent fuel assembly hardware: Characterization and 10 CFR 61 classification for waste disposal: Volume 2, Calculated activity profiles of spent nuclear fuel assembly hardware for pressurized water reactors

    SciTech Connect

    Short, S.M.; Luksic, A.T.; Lotz, T.L.; Schutz, M.E.

    1989-06-01

    Consolidation of spent fuel is under active consideration as the US Department of Energy plans to dispose of spent fuel as required by the Nuclear Waste Policy Act of 1982. During consolidation, the fuel pins are removed from an intact fuel assembly and repackaged into a more compact configuration. After repackaging, approximately 30 kg of residual spent fuel assembly hardware per assembly remains that is also radioactive and requires disposal. Understanding the nature of this secondary waste stream is critical to designing a system that will properly handle, package, store, and dispose of the waste. This report present a methodology for estimating the radionuclide inventory in irradiated spent fuel hardware. Ratios are developed that allow the use of ORIGEN2 computer code calculations to be applied to regions that are outside the fueled region. The ratios are based on the analysis of samples of irradiated hardware from spent fuel assemblies. The results of this research are presented in three volumes. In Volume 1, the development of scaling factors that can be used with ORIGEN2 calculations to estimate activation of spent fuel assembly hardware is documented. The results from Laboratory analysis of irradiated spent-fuel hardware samples are also presented in Volume 1. In Volumes 2 and 3, the calculated flux profiles of spent nuclear fuel assemblies are presented for pressurized water reactors and boiling water reactors, respectively. The results presented in Volumes 2 and 3 were used to develop the scaling factors documented in Volume 1.

  17. Validation of HELIOS Neutron Cross-Section Library for RBMK Reactors Against the Data From the Critical Facility Experiments

    SciTech Connect

    Jasiulevicius, Audrius; Sehgal, Bal Raj

    2002-07-01

    The RBMK reactors are channel type, water-cooled and graphite moderated reactors. The first RBMK type electricity production reactor was put on-line in 1973. Currently there are 13 operating reactors of this type. Two of the RBMK-1500 reactors are at the Ignalina NPP in Lithuania. Experimental Critical Facility for RBMK reactors, located at Kurchatov Institute, Moscow was designed to carry out critical reactivity experiments on assemblies, which imitate parts of the RBMK reactor core. The facility is composed of Control and Protection Rods (CPR's), fuel assemblies with different enrichment in U-235 and other elements, typical for RBMK reactor core loadings, e.g. additional absorber assemblies, CPR imitators, etc. A simulation of a set of the experiments, performed at the Experimental Critical Facility, was carried out at the Royal Institute of Technology (RIT), Nuclear Power Safety Division, using CORETRAN 3-D neutron dynamics code. The neutron cross sections for assemblies were calculated using HELIOS code. The aim of this work was to evaluate capabilities of the HELIOS code to provide correct cross section data for the RBMK reactor. The calculation results were compared to the similar CORETRAN calculations, when employing WIMS-D4 code generated cross section data. For some of the experiments, where calculation results with CASMO-4 code generated cross sections are available, the comparison is also performed against CASMO-4 results. Eleven different experiments were simulated. Experiments differ in size of the facility core (number of assemblies loaded): from simple core loadings, composed only of a few fuel assemblies, to complicated configurations, which represent a part of the RBMK reactor core. Diverse types of measurements were carried out during these experiments: reactivity, neutron flux distributions (both axial and radial), rod reactivity worth and the voiding effects. Results of the reactivity measurements and relative neutron flux distributions were

  18. Test Suite for Nuclear Data I: Deterministic Calculations for Critical Assemblies and Replacement Coefficients

    SciTech Connect

    Pruet, J; Brown, D A; Descalle, M

    2006-05-22

    The authors describe tools developed by the Computational Nuclear Physics group for testing the quality of internally developed nuclear data and the fidelity of translations from ENDF formatted data to ENDL formatted data used by Livermore. These tests include S{sub n} calculations for the effective k value characterizing critical assemblies and for replacement coefficients of different materials embedded in the Godiva and Jezebel critical assemblies. For those assemblies and replacement materials for which reliable experimental information is available, these calculations provide an integral check on the quality of data. Because members of the ENDF and reactor communities use calculations for these same assemblies in their validation process, a comparison between their results with ENDF formatted data and their results with data translated into the ENDL format provides a strong check on the accuracy of translations. As a first application of the test suite they present a study comparing ENDL 99 and ENDF/B-V. They also consider the quality of the ENDF/B-V translation previously done by the Computational Nuclear Physics group. No significant errors are found.

  19. Benchmarking of Graphite Reflected Critical Assemblies of UO2

    SciTech Connect

    Margaret A. Marshall; John D. Bess

    2011-11-01

    A series of experiments were carried out in 1963 at the Oak Ridge National Laboratory Critical Experiments Facility (ORCEF) for use in space reactor research programs. A core containing 93.2% enriched UO2 fuel rods was used in these experiments. The first part of the experimental series consisted of 253 tightly-packed fuel rods (1.27 cm triangular pitch) with graphite reflectors [1], the second part used 253 graphite-reflected fuel rods organized in a 1.506 cm triangular pitch [2], and the final part of the experimental series consisted of 253 beryllium-reflected fuel rods with a 1.506 cm triangular pitch. [3] Fission rate distribution and cadmium ratio measurements were taken for all three parts of the experimental series. Reactivity coefficient measurements were taken for various materials placed in the beryllium reflected core. The first part of this experimental series has been evaluated for inclusion in the International Reactor Physics Experiment Evaluation Project (IRPhEP) [4] and the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbooks, [5] and is discussed below. These experiments are of interest as benchmarks because they support the validation of compact reactor designs with similar characteristics to the design parameters for a space nuclear fission surface power systems. [6

  20. Experimental physics characteristics of a heavy-metal-reflected fast-spectrum critical assembly

    NASA Technical Reports Server (NTRS)

    Heneveld, W. H.; Paschall, R. K.; Springer, T. H.; Swanson, V. A.; Thiele, A. W.; Tuttle, R. J.

    1972-01-01

    A zero-power critical assembly was designed, constructed, and operated for the purpose of conducting a series of benchmark experiments dealing with the physics characteristics of a UN-fueled, Li-cooled, Mo-reflected, drum-controlled compact fast reactor for use with a space-power electric conversion system. The range of the previous experimental investigations has been expanded to include the reactivity effects of:(1) surrounding the reactor with 15.24 cm (6 in.) of polyethylene, (2) reducing the heights of a portion of the upper and lower axial reflectors by factors of 2 and 4, (3) adding 45 kg of W to the core uniformly in two steps, (4) adding 9.54 kg of Ta to the core uniformly, and (5) inserting 2.3 kg of polyethylene into the core proper and determining the effect of a Ta addition on the polyethylene worth.

  1. Unique educational opportunities at the Missouri University research reactor

    SciTech Connect

    Ketring, A.R.; Ross, F.K.; Spate, V.

    1997-12-01

    Since the Missouri University Research Reactor (MURR) went critical in 1966, it has been a center where students from many departments conduct their graduate research. In the past three decades, hundreds of graduate students from the MU departments of chemistry, physics, anthropology, nuclear engineering, etc., have received masters and doctoral degrees based on research using neutrons produced at MURR. More recently, the educational opportunities at MURR have been expanded to include undergraduate students and local high school students. Since 1989 MURR has participated in the National Science Foundation-funded Research Experience for Undergraduates (REU) program. As part of this program, undergraduate students from universities and colleges throughout the United States come to MURR and get hands-on research experience during the summer. Another program, started in 1994 by the Nuclear Analysis Program at MURR, allows students from a local high school to conduct a neutron activation analysis (NAA) experiment. We also conduct tours of the center, where we describe the research and educational programs at MURR to groups of elementary school children, high school science teachers, state legislators, professional organizations, and many other groups.

  2. Howard University Assembles Fund-Raising Juggernaut

    ERIC Educational Resources Information Center

    Masterson, Kathryn

    2008-01-01

    As a dental student 35 years ago, Leo E. Rouse and his Howard University classmates learned to fill cavities and cap teeth by crowding around one faculty member and angling for a clear view of the day's demonstration. Today students at Howard's College of Dentistry, where Dr. Rouse is now the dean, get an unobstructed view of dental procedures…

  3. Critical partnerships: Los Alamos, universities, and industry

    SciTech Connect

    Berger, C.L.

    1997-04-01

    Los Alamos National Laboratory, situated 35 miles northwest of Santa Fe, NM, is one of the Department of Energy`s three Defense Programs laboratories. It encompasses 43 square miles, employees approximately 10,000 people, and has a budget of approximately $1.1B in FY97. Los Alamos has a strong post-cold war mission, that of reducing the nuclear danger. But even with that key role in maintaining the nation`s security, Los Alamos views partnerships with universities and industry as critical to its future well being. Why is that? As the federal budget for R&D comes under continued scrutiny and certain reduction, we believe that the triad of science and technology contributors to the national system of R&D must rely on and leverage each others capabilities. For us this means that we will rely on these partners to help us in 5 key ways: We expect that partnerships will help us maintain and enhance our core competencies. In doing so, we will be able to attract the best scientists and engineers. To keep on the cutting edge of research and development, we have found that partnerships maintain the excellence of staff through new and exciting challenges. Additionally, we find that from our university and corporate partners we often learn and incorporate {open_quotes}best practices{close_quotes} in organizational management and operations. Finally, we believe that a strong national system of R&D will ensure and enhance our ability to generate revenues.

  4. Possible criticality of marine reactors dumped in the Kara Sea

    SciTech Connect

    Warden, J.M.; Mount, M.; Lynn, N.M.

    1997-05-01

    The largest inventory of radioactive materials dumped in the Kara Sea by the former Soviet Union comes from the spent nuclear fuel (SNF) of seven marine reactors. Using corrosion models derived for the International Arctic Seas Assessment Project (IASAP), the possibility of some of the SNF achieving criticality through structural and material changes has been investigated. Although remote, the possibility cannot at this stage be ruled out.

  5. Scale-4 Analysis of Pressurized Water Reactor Critical Configurations: Volume 2-Sequoyah Unit 2 Cycle 3

    SciTech Connect

    Bowman, S.M.

    1995-01-01

    The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor criticality safety analyses be validated against experimental measurements. If credit for the negative reactivity of the depleted (or spent) fuel isotopics is desired, it is necessary to benchmark computational methods against spent fuel critical configurations. This report summarizes a portion of the ongoing effort to benchmark away-from-reactor criticality analysis methods using critical configurations from commercial pressurized-water reactors. The analysis methodology selected for all the calculations reported herein is based on the codes and data provided in the SCALE-4 code system. The isotopic densities for the spent fuel assemblies in the critical configurations were calculated using the SAS2H analytical sequence of the SCALE-4 system. The sources of data and the procedures for deriving SAS2H input parameters are described in detail. The SNIKR code module was used to extract the necessary isotopic densities from the SAS2H results and provide the data in the format required by the SCALE criticality analysis modules. The CSASN analytical sequence in SCALE-4 was used to perform resonance processing of the cross sections. The KENO V.a module of SCALE-4 was used to calculate the effective multiplication factor (k{sub eff}) of each case. The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides) and ENDF/B-V (fission products) data was used for all the calculations. This volume of the report documents the SCALE system analysis of three reactor critical configurations for the Sequoyah Unit 2 Cycle 3. This unit and cycle were chosen because of the relevance in spent fuel benchmark applications: (1) the unit had a significantly long downtime of 2.7 years during the middle of cycle (MOC) 3, and (2) the core consisted entirely of burned fuel at the MOC restart. The first benchmark critical calculation was the MOC restart at hot, full-power (HFP) critical conditions. The

  6. Performance of boiling water reactor fuel lead test assemblies to 35 MWd/kg U

    SciTech Connect

    Rowland, T.C.; Ikemoto, R.N.; Gehl, S.

    1986-01-01

    This joint Electric Power Research Institute/General Electric (EPRI/GE) fuel performance program involved thorough preirradiation characterization of fuel used in lead test assemblies (LTAs), detailed surveillance of their operation, and interim site examinations of the assemblies during reactor outages. The program originally included four GE-5 LTAs operating in the Peach Bottom-2 (PB-2) reactor. The program was later modified to include the pressurized fuel rod test assembly in the Peach Bottom-3 (PB-3) reactor. The program modification also included extending the operation of the PB-2 and PB-3 LTA fuel beyond normal discharge exposures. Results are summarized in the paper.

  7. SHEBA: Modifications to a low-enrichment-solution critical assembly

    SciTech Connect

    Butterfield, K.B.

    1994-09-01

    The SHEBA solution assembly has been modified to operate either in a below-ground crypt to provide radiation shielding or aboveground for dosimetry measurements. Other modifications include better solution depth measurements, improved flow control, and possible burst operation capability. SHEBA uses 5% enriched uranyl fluoride fuel and is controlled with a digital process control system. The current status has the mechanical hardware completed and the approval for operations process started. Water tests are underway, and we are working to develop an ultrasonic-level measurements system that will have 0.1-mm resolution at the critical depth of {approximately} 40 cm.

  8. Experimental physics characteristics of a heavy-metal-reflected fast-spectrum critical assembly

    NASA Technical Reports Server (NTRS)

    Heneveld, W. H.; Paschall, R. K.; Springer, T. H.; Swanson, V. A.; Thiele, A. W.; Tuttle, R. J.

    1971-01-01

    A zero-power critical assembly was designed, constructed, and operated for the purpose of conducting a series of benchmark experiments dealing with the physics characteristics of a UN-fueled, Li-7 cooled, Mo-reflected, drum-controlled compact fast reactor for use with a space-power electric conversion system. The experimental program consisted basically of measuring the differential neutron spectra and the changes in critical mass that accompanied the stepwise addition of (Li-7)3N, Hf, Ta, and W to a basic core fueled with U metal in a pin-type Ta honeycomb structure. In addition, experimental results were obtained on power distributions, control characteristics, neutron lifetime, and reactivity worths of numerous absorber, structural, and scattering materials.

  9. Comparison of KENO-VI and MCNP5 Criticality Analyses for a Lunar Regolith Clustered-Reactor System

    SciTech Connect

    Bess, John Darrell

    2008-01-21

    The Lunar Regolith Clustered-Reactor System design has been presented as an alternative method for providing surface power to a lunar facility using a fast-fission, heatpipe-cooled nuclear reactor. The reactor system is divided into subcritical units that can be safely launched into orbit without risk of inadvertent criticality in the event of a launch accident. The reactor subunits are emplaced into the lunar surface to form a clustered-reactor system, utilizing the regolith as both radiation shielding and neutron-reflector material. Coordinated placement of multiple subunits can provision a critical reactor system proportional to localized lunar surface power demand. Reactor units assembled using proven and tested materials in radiation environments such as UO{sub 2} fuel, stainless-steel cladding and support, and compatible liquid-metal heatpipes promote safety and reliability, with ease of manufacture and testing. Reactor power levels of approximately 100 kWth per subunit significantly reduces the negative effects of elevated temperature and radiation environments associated with single nuclear power reactors operated at higher power levels. The analysis of subunit criticality in various accident scenarios differs by up to 4% ({approx}$6 in reactivity) between results generated using conventional criticality analysis codes, MCNP5 and KENO-VI. A demonstrated trend exists between results of the two criticality codes as accident conditions approach a multiplication factor of one. Code comparison of a tri-cluster system on the lunar surface provides comparable results with calculated system reactivity within 0.5%. Iron concentration is confirmed as the dominant element in the lunar regolith influencing system reactivity.

  10. Comparison of KENO-VI and MCNP5 Criticality Analyses for a Lunar Regolith Clustered-Reactor System

    NASA Astrophysics Data System (ADS)

    Bess, John Darrell

    2008-01-01

    The Lunar Regolith Clustered-Reactor System design has been presented as an alternative method for providing surface power to a lunar facility using a fast-fission, heatpipe-cooled nuclear reactor. The reactor system is divided into subcritical units that can be safely launched into orbit without risk of inadvertent criticality in the event of a launch accident. The reactor subunits are emplaced into the lunar surface to form a clustered-reactor system, utilizing the regolith as both radiation shielding and neutron-reflector material. Coordinated placement of multiple subunits can provision a critical reactor system proportional to localized lunar surface power demand. Reactor units assembled using proven and tested materials in radiation environments such as UO2 fuel, stainless-steel cladding and support, and compatible liquid-metal heatpipes promote safety and reliability, with ease of manufacture and testing. Reactor power levels of approximately 100 kWth per subunit significantly reduces the negative effects of elevated temperature and radiation environments associated with single nuclear power reactors operated at higher power levels. The analysis of subunit criticality in various accident scenarios differs by up to 4% (~$6 in reactivity) between results generated using conventional criticality analysis codes, MCNP5 and KENO-VI. A demonstrated trend exists between results of the two criticality codes as accident conditions approach a multiplication factor of one. Code comparison of a tri-cluster system on the lunar surface provides comparable results with calculated system reactivity within 0.5%. Iron concentration is confirmed as the dominant element in the lunar regolith influencing system reactivity.

  11. An integrated approach for the verification of fresh mixed oxide fuel (MOX) assemblies at light water reactor MOX recycle reactors

    SciTech Connect

    Menlove, Howard O; Lee, Sang - Yoon

    2009-01-01

    This paper presents an integrated approach for the verification of mixed oxide (MOX) fuel assemblies prior to their being loaded into the reactor. There is a coupling of the verification approach that starts at the fuel fabrication plant and stops with the transfer of the assemblies into the thermal reactor. The key measurement points are at the output of the fuel fabrication plant, the receipt at the reactor site, and the storage in the water pool as fresh fuel. The IAEA currently has the capability to measure the MOX fuel assemblies at the output of the fuel fabrication plants using a passive neutron coincidence counting systems of the passive neutron collar (PNCL) type. Also. at the MOX reactor pool, the underwater coincidence counter (UWCC) has been developed to measure the MOX assemblies in the water. The UWCC measurement requires that the fuel assembly be lifted about two meters up in the storage rack to avoid interference from the fuel that is stored in the rack. This paper presents a new method to verify the MOX fuel assemblies that are in the storage rack without the necessity of moving the fuel. The detector system is called the Underwater MOX Verification System (UMVS). The integration and relationship of the three measurements systems is described.

  12. Intrinsic universality and the computational power of self-assembly.

    PubMed

    Woods, Damien

    2015-07-28

    Molecular self-assembly, the formation of large structures by small pieces of matter sticking together according to simple local interactions, is a ubiquitous phenomenon. A challenging engineering goal is to design a few molecules so that large numbers of them can self-assemble into desired complicated target objects. Indeed, we would like to understand the ultimate capabilities and limitations of this bottom-up fabrication process. We look to theoretical models of algorithmic self-assembly, where small square tiles stick together according to simple local rules in order to carry out a crystal growth process. In this survey, we focus on the use of simulation between such models to classify and separate their computational and expressive powers. Roughly speaking, one model simulates another if they grow the same structures, via the same dynamical growth processes. Our journey begins with the result that there is a single intrinsically universal tile set that, with appropriate initialization and spatial scaling, simulates any instance of Winfree's abstract Tile Assembly Model. This universal tile set exhibits something stronger than Turing universality: it captures the geometry and dynamics of any simulated system in a very direct way. From there we find that there is no such tile set in the more restrictive non-cooperative model, proving it weaker than the full Tile Assembly Model. In the two-handed model, where large structures can bind together in one step, we encounter an infinite set of infinite hierarchies of strictly increasing simulation power. Towards the end of our trip, we find one tile to rule them all: a single rotatable flipable polygonal tile that simulates any tile assembly system. We find another tile that aperiodically tiles the plane (but with small gaps). These and other recent results show that simulation is giving rise to a kind of computational complexity theory for self-assembly. It seems this could be the beginning of a much longer journey

  13. The Promotion of Peace Education through Guides in Peace Museums. A Case Study of the Kyoto Museum for World Peace, Ritsumeikan University

    ERIC Educational Resources Information Center

    Tanigawa, Yoshiko

    2015-01-01

    This paper focuses on how peace education at a peace museum is promoted by a volunteer guide service for visitors. Peace museums are places where many materials related to war and peace history are on display. To support the learning experience of museum visitors, many peace museums in Japan provide a volunteer guide service. The Kyoto Museum for…

  14. University Reactor Instrumentation Program. Final report, 1990--1992

    SciTech Connect

    Vernetson, W.G.

    1992-11-01

    Recognizing that the University Reactor Instrumentation Program was developed in response to widespread needs in the academic community for modernization and improvement of research and training reactors at institutions such as the University of Florida, the items proposed to be supported by this grant over its two year period have been selected as those most likely to reduce foreed outages, to meet regulatory concerns that had been expressed in recent years by Nuclear Regulatory Commission inspectors or to correct other facility problems and limitations. Department of Energy Grant Number DE-FG07-90ER129969 was provided to the University of Florida Training Reactor(UFTR) facility through the US Department of Energy`s University Reactor Instrumentation Program. The original proposal submitted in February, 1990 requested support for UFTR facility instrumentation and equipment upgrades for seven items in the amount of $107,530 with $13,800 of this amount to be the subject of cost sharing by the University of Florida and $93,730 requested as support from the Department of Energy. A breakdown of the items requested and total cost for the proposed UFTR facility instrumentation and equipment improvements is presented.

  15. 76 FR 69296 - University of Utah, University of Utah TRIGA Nuclear Reactor, Notice of Issuance of Renewed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ... COMMISSION University of Utah, University of Utah TRIGA Nuclear Reactor, Notice of Issuance of Renewed... Test Reactor Licensing Branch, Division of Policy and Rulemaking, Office of Nuclear Reactor Regulation... University of Utah (UU, the licensee), which authorizes continued operation of the UU TRIGA Nuclear...

  16. An ultracold neutron source at the NC State University PULSTAR reactor

    NASA Astrophysics Data System (ADS)

    Korobkina, E.; Wehring, B. W.; Hawari, A. I.; Young, A. R.; Huffman, P. R.; Golub, R.; Xu, Y.; Palmquist, G.

    2007-08-01

    Research and development is being completed for an ultracold neutron (UCN) source to be installed at the PULSTAR reactor on the campus of North Carolina State University (NCSU). The objective is to establish a university-based UCN facility with sufficient UCN intensity to allow world-class fundamental and applied research with UCN. To maximize the UCN yield, a solid ortho-D 2 converter will be implemented coupled to two moderators, D 2O at room temperature, to thermalize reactor neutrons, and solid CH 4, to moderate the thermal neutrons to cold-neutron energies. The source assembly will be located in a tank of D 2O in the space previously occupied by the thermal column of the PULSTAR reactor. Neutrons leaving a bare face of the reactor core enter the D 2O tank through a 45×45 cm cross-sectional area void between the reactor core and the D 2O tank. Liquid He will cool the disk-shaped UCN converter to below 5 K. Independently, He gas will cool the cup-shaped CH 4 cold-neutron moderator to an optimum temperature between 20 and 40 K. The UCN will be transported from the converter to experiments by a guide with an inside diameter of 16 cm. Research areas being considered for the PULSTAR UCN source include time-reversal violation in neutron beta decay, neutron lifetime determination, support measurements for a neutron electric-dipole-moment search, and nanoscience applications.

  17. Characterization of a New Continuous Air Monitoring System For the University of Massachusetts Lowell Research Reactor

    NASA Astrophysics Data System (ADS)

    Alqahtani, Mohammad Saad

    A continuous air monitor (CAM) is a critical piece of equipment to support radiation safety in nuclear facilities where the generation of airborne radioactivity is a possibility for either normal operations or accident scenarios. The University of Massachusetts Lowell Research Reactor is planning to install a new CAM system manufactured by Canberra Industries for monitoring airborne radioactive particulates. In this study, the new CAM was evaluated to determine 1) baseline response, 2) response to high exposure rates, 3) appropriate background compensation, 4) detection limits, and 5) alarm settings. The results of this study will help to properly integrate the new CAM into the reactor radiation monitoring system.

  18. Critical Issues for Particle-Bed Reactor Fuels

    NASA Astrophysics Data System (ADS)

    Evans, Robert S.; Husser, Dewayne L.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    Particle-Bed Reactors (PBRs) potentially offer performance advantages for nuclear thermal propulsion, including very high power densities, thrust-to-weight ratios, and specific impulses. A key factor in achieving all of these is the development of a very-high-temperature fuel. The critical issues for all such PBR fuels are uranium loading, thermomechanical and thermochemical stability, compatibility with contacting materials, fission product retention, manufacturability, and operational tolerance for particle failures. Each issue is discussed with respect to its importance to PBR operation, its status among current fuels, and additional development needs. Mixed-carbide-based fuels are recommended for further development to support high-performance PBRs.

  19. Iterative methods for solving nonlinear problems of nuclear reactor criticality

    SciTech Connect

    Kuz'min, A. M.

    2012-12-15

    The paper presents iterative methods for calculating the neutron flux distribution in nonlinear problems of nuclear reactor criticality. Algorithms for solving equations for variations in the neutron flux are considered. Convergence of the iterative processes is studied for two nonlinear problems in which macroscopic interaction cross sections are functionals of the spatial neutron distribution. In the first problem, the neutron flux distribution depends on the water coolant density, and in the second one, it depends on the fuel temperature. Simple relationships connecting the vapor content and the temperature with the neutron flux are used.

  20. Disposition of fuel elements from the Aberdeen and Sandia pulse reactor (SPR-II) assemblies

    SciTech Connect

    Mckerley, Bill; Bustamante, Jacqueline M; Costa, David A; Drypolcher, Anthony F; Hickey, Joseph

    2010-01-01

    We describe the disposition of fuel from the Aberdeen (APR) and the Sandia Pulse Reactors (SPR-II) which were used to provide intense neutron bursts for radiation effects testing. The enriched Uranium - 10% Molybdenum fuel from these reactors was shipped to the Los Alamos National Laboratory (LANL) for size reduction prior to shipment to the Savannah River Site (SRS) for final disposition in the H Canyon facility. The Shipper/Receiver Agreements (SRA), intra-DOE interfaces, criticality safety evaluations, safety and quality requirements and key materials management issues required for the successful completion of this project will be presented. This work is in support of the DOE Consolidation and Disposition program. Sandia National Laboratories (SNL) has operated pulse nuclear reactor research facilities for the Department of Energy since 1961. The Sandia Pulse Reactor (SPR-II) was a bare metal Godiva-type reactor. The reactor facilities have been used for research and development of nuclear and non-nuclear weapon systems, advanced nuclear reactors, reactor safety, simulation sources and energy related programs. The SPR-II was a fast burst reactor, designed and constructed by SNL that became operational in 1967. The SPR-ll core was a solid-metal fuel enriched to 93% {sup 235}U. The uranium was alloyed with 10 weight percent molybdenum to ensure the phase stabilization of the fuel. The core consisted of six fuel plates divided into two assemblies of three plates each. Figure 1 shows a cutaway diagram of the SPR-II Reactor with its decoupling shroud. NNSA charged Sandia with removing its category 1 and 2 special nuclear material by the end of 2008. The main impetus for this activity was based on NNSA Administrator Tom D'Agostino's six focus areas to reenergize NNSA's nuclear material consolidation and disposition efforts. For example, the removal of SPR-II from SNL to DAF was part of this undertaking. This project was in support of NNSA's efforts to consolidate the

  1. Investigation of radiation fields outside the Sub-critical Assembly in Dubna.

    PubMed

    Seltbor, P; Lopatkin, A; Gudowski, W; Shvetsov, V; Polanski, A

    2005-01-01

    The radiation fields outside the planned experimental Sub-critical Assembly in Dubna (SAD) have been studied in order to provide a basis for the design of the concrete shielding that cover the reactor core. The effective doses around the reactor, induced by leakage of neutrons and photons through the shielding, have been determined for a shielding thickness varying from 100 to 200 cm. It was shown that the neutron flux and the effective dose is higher above the shielding than at the side of it, owing to the higher fraction of high-energy spallation neutrons emitted in the direction of the incident beam protons. At the top, the effective dose was found to be -150 microSv s(-1) for a concrete thickness of 100 cm, while -2.5 microSv s(-1) for a concrete thickness of 200 cm. It was also shown that the high-energy neutrons (> 10 MeV), which are created in the proton-induced spallation interactions in the target, contribute for the major part of the effective doses outside the reactor. PMID:16604676

  2. Scale-4 Analysis of Pressurized Water Reactor Critical Configurations: Volume 1-Summary

    SciTech Connect

    DeHart, M.D.

    1995-01-01

    The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor criticality safety analyses be validated against experimental measurements. If credit is to be taken for the reduced reactivity of burned or spent fuel relative to its original ''fresh'' composition, it is necessary to benchmark computational methods used in determining such reactivity worth against spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to benchmark away-from-reactor criticality analysis methods using critical configurations from commercial pressurized- water reactors (PWR). The analysis methodology utilized for all calculations in this report is based on the modules and data associated with the SCALE-4 code system. Isotopic densities for spent fuel assemblies in the core were calculated using the SAS2H analytical sequence in SCALE-4. The sources of data and the procedures for deriving SAS2H input parameters are described in detail. The SNIKR code sequence was used to extract the necessary isotopic densities from SAS2H results and to provide the data in the format required for SCALE-4 criticality analysis modules. The CSASN analytical sequence in SCALE-4 was used to perform resonance processing of cross sections. The KENO V.a module of SCALE-4 was used to calculate the effective multiplication factor (k{sub eff}) for the critical configuration. The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides) and ENDF/B-V (fission products) data was used for analysis of each critical configuration. Each of the five volumes comprising this report provides an overview of the methodology applied. Subsequent volumes also describe in detail the approach taken in performing criticality calculations for these PWR configurations: Volume 2 describes criticality calculations for the Tennessee Valley Authority's Sequoyah Unit 2 reactor for Cycle 3; Volume 3 documents the analysis of Virginia Power's Surry Unit 1 reactor for the

  3. Computer modeling of the dynamic processes in the Maryland University Training Reactor - (MUTR)

    SciTech Connect

    White, Bernard H. IV; Ebert, David

    1988-07-01

    The simulator described in this paper models the behaviour of the Maryland University Training Reactor (MUTR). The reactor is a 250 kW, TRIGA reactor. The computer model is based on a system of five primary equations and eight auxiliary equations. The primary equations consist of the prompt jump approximation, a heat balance equation for the fuel and the moderator, and iodine and xenon buildup equations. For the comparison with the computer program, data from the reactor was acquired by using a personal computer (pc) which contained a Strawberry Tree data acquisition Card, connected to the reactor. The systems monitored by the pc were: two neutron detectors, fuel temperature, water temperature, three control rod positions and the period meter. The time differenced equations were programmed in the basic language. It has been shown by this paper, that the MUTR power rise from low power critical to high power, can be modelled by a relatively simple computer program. The program yields accurate agreement considering the simplicity of the program. The steady state error between the reactor and computer power is 4.4%. The difference in steady state temperatures, 112 deg. C and 117 deg. C, of the reactor and computer program, respectively, also yields a 4.5% error. Further fine tuning of the coefficients will yield higher accuracies.

  4. Development of neutron radiography facility for boiling two-phase flow experiment in Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Sekimoto, S.; Hino, M.; Kawabata, Y.

    2011-09-01

    To visualize boiling two-phase flow at high heat flux by using neutron radiography, a new neutron radiography facility was developed in the B-4 beam hole of KUR. The B-4 beam hole is equipped with a supermirror neutron guide tube with a characteristic wavelength of 1.2 Å, whose geometrical parameters of the guide tube are: 11.7 m total length and 10 mm wide ×74 mm high beam cross-section. The total neutron flux obtained from the KUR supermirror guide tube is about 5×10 7 n/cm 2 s with a nominal thermal output of 5 MW of KUR, which is about 100 times what is obtainable with the conventional KUR neutron radiography facility (E-2 beam hole). In this study a new imaging device, an electric power supply (1200 A, 20 V), and a thermal hydraulic loop were installed. The neutron source, the beam tube, and the radiography rooms are described in detail and the preliminary images obtained at the developed facility are shown.

  5. The Secular University and Its Critics

    ERIC Educational Resources Information Center

    Jobani, Yuval

    2016-01-01

    Universities in the USA have become bastions of secularity in a distinctly religious society. As such, they are subjected to a variety of robust and rigorous religious critiques. In this paper I do not seek to engage in the debate between the supporters of the secular university and its opponents. Furthermore, I do not claim to summarize the…

  6. Perelman's Universal Audience as Critical Tool.

    ERIC Educational Resources Information Center

    Corgan, Verna C.

    1987-01-01

    Argues that all rhetoric has an ethical dimension and analyzes legal arguments using criteria for "universal" argumentation from C. Perelman. Suggests: (1) practical success can result from universal argumentation; (2) specificity of the law, precedent, and legal status of conflicting values affect preferences for arguments; and (3) universal…

  7. Consolidated fuel reprocessing program: Criticality experiments with fast test reactor fuel pins in an organic moderator

    SciTech Connect

    Bierman, S.R.

    1986-12-01

    The results obtained in a series of criticality experiments performed as part of a joint program on criticality data development between the United States Department of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan are presented in this report along with a complete description of the experiments. The experiments involved lattices of Fast Test Reactor (FTR) fuel pins in an organic moderator mixture similar to that used in the solvent extraction stage of fuel reprocessing. The experiments are designed to provide data for direct comparison with previously performed experimental measurements with water moderated lattices of FTR fuel pins. The same lattice arrangements and FTR fuel pin types are used in these organic moderated experimental assemblies as were used in the water moderated experiments. The organic moderator is a mixture of 38 wt % tributylphosphate in a normal paraffin hydrocarbon mixture of C{sub 11}H{sub 24} to C{sub 15}H{sub 32} molecules. Critical sizes of 1054.8, 599.2, 301.8, 199.5 and 165.3 fuel pins were obtained respectively for organic moderated lattices having 0.761 cm, 0.968 cm, 1.242 cm, 1.537 cm and 1.935 cm square lattice pitches as compared to 1046.9, 571.9, 293.9, 199.7 and 165.1 fuel pins for the same lattices water moderated.

  8. University Reactor Conversion Lessons Learned Workshop for the University of Florida

    SciTech Connect

    Eric C. Woolstenhulme; Dana M. Meyer

    2007-04-01

    The Department of Energy’s (DOE) Idaho National Laboratory (INL), under its programmatic responsibility for managing the University Research Reactor Conversions, has completed the conversion of the reactor at the University of Florida. This project was successfully completed through an integrated and collaborative effort involving the INL, Argonne National Laboratory (ANL), DOE (Headquarters and Field Office), the Nuclear Regulatory Commission, the Universities, and contractors involved in analyses, fuel design and fabrication, and SNF shipping and disposition. With the work completed with these two universities, and in anticipation of other impending conversion projects, INL convened and engaged the project participants in a structured discussion to capture lessons learned. The objectives of this meeting were to capture the observations, insights, issues, concerns, and ideas of those involved in the reactor conversions so that future efforts can be conducted with greater effectiveness, efficiency, and with fewer challenges.

  9. Adapting the Critical Thinking Assessment Test for Palestinian Universities

    ERIC Educational Resources Information Center

    Basha, Sami; Drane, Denise; Light, Gregory

    2016-01-01

    Critical thinking is a key learning outcome for Palestinian students. However, there are no validated critical thinking tests in Arabic. Suitability of the US developed Critical Thinking Assessment Test (CAT) for use in Palestine was assessed. The test was piloted with university students in English (n = 30) and 4 questions were piloted in Arabic…

  10. Electromagnetic Near Field Measurements of Two Critical Assemblies

    SciTech Connect

    Goettee, Jeffrey David

    2015-11-03

    The reactors employed, Godiva IV and WSMR Fast Burst Reactor, are described first. Then the point reactor kinetics model, electromagnetic potential, and the measurement of kinetics quantities are successively discussed. In summary, reactor power produces measurable electric energy. The electric signal mimics power curve for prompt burst operations - features in logarithmic derivatives match. The electric signature should be dependent on the power and not the derivative; therefore, steady-state modes should be measurable.

  11. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

  12. Radioisotope research, production, and processing at the University of Missouri Research Reactor

    SciTech Connect

    Ehrhardt, G.J.; Ketring, A.R.; Ja, Wei; Ma, D.; Zinn, K.; Lanigan, J.

    1995-12-31

    The University of Missouri Research Reactor (MURR) is a 10 MW, light-water-cooled and moderated research reactor which first achieved criticality in 1996 and is currently the highest powered university-owned research reactor in the U.S. For many years a major supplier of reactor-produced isotopes for research and commercial purposes, in the last 15 years MURR has concentrated on development of reactor-produced beta-particle emitters for experimental use in nuclear medicine therapy of cancer and rheumatoid arthritis. MURR has played a major role in the development of bone cancer pain palliation with the agents {sup 153}Sm EDTMP and {sup 186}Re/{sup 188}Re HEDP, as well as in the use of {sup 186}Re, {sup 177}Lu, {sup 166}Ho, and {sup 105}Rh for radioimmunotherapy and receptor-agent-guided radiotherapy. MURR is also responsible for the development of therapeutic, {sup 90}Y-labeled glass microspheres for the treatment of liver tumors, a product ({sup 90}Y Therasphere{trademark}) which is currently an approved drug in Canada. MURR has also pioneered the development of {sup 188}W/{sup 188}Re and {sup 99}Mo/{sup 99m}Tc gel generators, which make the use of low specific activity {sup 188}W and {sup 99}Mo practical for such isotope generators.

  13. Critical Casimir interactions and colloidal self-assembly in near-critical solvents.

    PubMed

    Tasios, Nikos; Edison, John R; van Roij, René; Evans, Robert; Dijkstra, Marjolein

    2016-08-28

    A binary solvent mixture close to critical demixing experiences fluctuations whose correlation length, ξ, diverges as the critical point is approached. The solvent-mediated (SM) interaction that arises between a pair of colloids immersed in such a near-critical solvent can be long-ranged and this so-called critical Casimir interaction is well-studied. How a (dense) suspension of colloids will self-assemble under these conditions is poorly understood. Using a two-dimensional lattice model for the solvent and hard disks to represent the colloids, we perform extensive Monte Carlo simulations to investigate the phase behaviour of this model colloidal suspension as a function of colloid size and wettability under conditions where the solvent reservoir is supercritical. Unlike most other approaches, where the solvent is modelled as an implicit background, our model employs an explicit solvent and treats the suspension as a ternary mixture. This enables us to capture important features, including the pronounced fractionation of the solvent in the coexisting colloidal phases, of this complex system. We also present results for the partial structure factors; these shed light on the critical behaviour in the ternary mixture. The degree to which an effective two-body pair potential description can describe the phase behaviour and structure of the colloidal suspension is discussed briefly. PMID:27586941

  14. [Dr. Michiharu Matsuoka, founder of the Department of Orthopaedic Surgery, Kyoto University, and his achievements (Part 6: Studying abroad of Dr. Matsuoka and opening to public, reputation and achievement of the department)].

    PubMed

    Hirotani, Hayato

    2011-03-01

    Dr. Michiharu Matsuoka studied orthopaedic surgery in Germany, Austria and other countries during the period from August, 1902 to May, 1906. He visited many university pathological institutes and surgical and orthopaedic clinics to study pathology and to learn the practice of orthopaedic surgery. After that, he started his practice at the newly established Department of Orthopaedic Surgery in the Medical School of Kyoto Imperial University in June, 1906. The department was opened in 1907 and in 1911 it was opened to all citizens and practical doctors in Kyoto City and exhibited many orthopaedic specimens and instruments. In particular, the x-ray apparatus of the Department was so well equipped that a German radiologist who visited the Department admired it in his article that was published in the journal of radiology in 1911. The Department was not surpassed by others for the number of patients with the dislocation of the hip and tuberculous spondylitis as well as the advanced quality and variety of roentgenological and pathological researches on these diseases. PMID:21797054

  15. [Dr. Michiharu Matsuoka, founder of the Department of Orthopaedic Surgery, Kyoto University, and his achievements (Part 6: Studying abroad of Dr. Matsuoka and opening to public, reputation and achievement of the department)].

    PubMed

    Hirotani, Hayato

    2011-03-01

    Dr. Michiharu Matsuoka studied orthopaedic surgery in Germany, Austria and other countries during the period from August, 1902 to May, 1906. He visited many university pathological institutes and surgical and orthopaedic clinics to study pathology and to learn the practice of orthopaedic surgery. After that, he started his practice at the newly established Department of Orthopaedic Surgery in the Medical School of Kyoto Imperial University in June, 1906. The department was opened in 1907 and in 1911 it was opened to all citizens and practical doctors in Kyoto City and exhibited many orthopaedic specimens and instruments. In particular, the x-ray apparatus of the Department was so well equipped that a German radiologist who visited the Department admired it in his article that was published in the journal of radiology in 1911. The Department was not surpassed by others for the number of patients with the dislocation of the hip and tuberculous spondylitis as well as the advanced quality and variety of roentgenological and pathological researches on these diseases.

  16. Reactor Accident Analysis Methodology for the Advanced Test Reactor Critical Facility Documented Safety Analysis Upgrade

    SciTech Connect

    Gregg L. Sharp; R. T. McCracken

    2003-06-01

    The regulatory requirement to develop an upgraded safety basis for a DOE nuclear facility was realized in January 2001 by issuance of a revision to Title 10 of the Code of Federal Regulations Section 830 (10 CFR 830).1 Subpart B of 10 CFR 830, “Safety Basis Requirements,” requires a contractor responsible for a DOE Hazard Category 1, 2, or 3 nuclear facility to either submit by April 9, 2001 the existing safety basis which already meets the requirements of Subpart B, or to submit by April 10, 2003 an upgraded facility safety basis that meets the revised requirements.1 10 CFR 830 identifies Nuclear Regulatory Commission (NRC) Regulatory Guide 1.70, “Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants”2 as a safe harbor methodology for preparation of a DOE reactor documented safety analysis (DSA). The regulation also allows for use of a graded approach. This report presents the methodology that was developed for preparing the reactor accident analysis portion of the Advanced Test Reactor Critical Facility (ATRC) upgraded DSA. The methodology was approved by DOE for developing the ATRC safety basis as an appropriate application of a graded approach to the requirements of 10 CFR 830.

  17. Reactor Accident Analysis Methodology for the Advanced Test Reactor Critical Facility Documented Safety Analysis Upgrade

    SciTech Connect

    Sharp, G.L.; McCracken, R.T.

    2003-05-13

    The regulatory requirement to develop an upgraded safety basis for a DOE Nuclear Facility was realized in January 2001 by issuance of a revision to Title 10 of the Code of Federal Regulations Section 830 (10 CFR 830). Subpart B of 10 CFR 830, ''Safety Basis Requirements,'' requires a contractor responsible for a DOE Hazard Category 1, 2, or 3 nuclear facility to either submit by April 9, 2001 the existing safety basis which already meets the requirements of Subpart B, or to submit by April 10, 2003 an upgraded facility safety basis that meets the revised requirements. 10 CFR 830 identifies Nuclear Regulatory Commission (NRC) Regulatory Guide 1.70, ''Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants'' as a safe harbor methodology for preparation of a DOE reactor documented safety analysis (DSA). The regulation also allows for use of a graded approach. This report presents the methodology that was developed for preparing the reactor accident analysis portion of the Advanced Test Reactor Critical Facility (ATRC) upgraded DSA. The methodology was approved by DOE for developing the ATRC safety basis as an appropriate application of a graded approach to the requirements of 10 CFR 830.

  18. Weightless experiments to probe universality of fluid critical behavior.

    PubMed

    Lecoutre, C; Guillaument, R; Marre, S; Garrabos, Y; Beysens, D; Hahn, I

    2015-06-01

    Near the critical point of fluids, critical opalescence results in light attenuation, or turbidity increase, that can be used to probe the universality of critical behavior. Turbidity measurements in SF6 under weightlessness conditions on board the International Space Station are performed to appraise such behavior in terms of both temperature and density distances from the critical point. Data are obtained in a temperature range, far (1 K) from and extremely close (a few μK) to the phase transition, unattainable from previous experiments on Earth. Data are analyzed with renormalization-group matching classical-to-critical crossover models of the universal equation of state. It results that the data in the unexplored region, which is a minute deviant from the critical density value, still show adverse effects for testing the true asymptotic nature of the critical point phenomena.

  19. Weightless experiments to probe universality of fluid critical behavior

    NASA Astrophysics Data System (ADS)

    Lecoutre, C.; Guillaument, R.; Marre, S.; Garrabos, Y.; Beysens, D.; Hahn, I.

    2015-06-01

    Near the critical point of fluids, critical opalescence results in light attenuation, or turbidity increase, that can be used to probe the universality of critical behavior. Turbidity measurements in SF6 under weightlessness conditions on board the International Space Station are performed to appraise such behavior in terms of both temperature and density distances from the critical point. Data are obtained in a temperature range, far (1 K) from and extremely close (a few μ K ) to the phase transition, unattainable from previous experiments on Earth. Data are analyzed with renormalization-group matching classical-to-critical crossover models of the universal equation of state. It results that the data in the unexplored region, which is a minute deviant from the critical density value, still show adverse effects for testing the true asymptotic nature of the critical point phenomena.

  20. Critical Path Modeling: University Planning in an Urban Context.

    ERIC Educational Resources Information Center

    Vasse, William W.; And Others

    1983-01-01

    The experiences of the University of Michigan in developing its Flint campus since the mid-1970s and the use of the Critical Path Method are described. The usefulness of the method during several phases of development is highlighted. (MSE)

  1. Continuity and Change: Kyoto Chefs Engage with Science.

    PubMed

    de St Maurice, Greg

    2015-01-01

    Kyoto's chefs have reacted proactively to changes brought about by the most recent phase of globalization, hoping to ensure the continued existence and resonance of Kyoto cuisine by using science to adapt it to contemporary circumstances. These chefs are breaking new ground in their pursuit of a scientific understanding of how Kyoto cuisine works. They meet once a month in a kitchen laboratory at Kyoto University to present and analyze culinary experiments in keeping with a predetermined theme. They use their acquired knowledge to more precisely hone their culinary skills and to explain Kyoto cuisine to a global audience. Chefs visit local elementary schools, appear on national television, and welcome chefs from abroad into their kitchens so that people across the world will better understand what authentic Kyoto cuisine consists of. Although these chefs' efforts are groundbreaking, there is also remarkable continuity to their approach. Not only has Kyoto cuisine always been in a steady state of transformation, but the chefs in the Laboratory are engaging with science and a global audience specifically so that they can ascertain Kyoto cuisine's continued existence and importance. Though their means of understanding and articulating what Kyoto cuisine is differs from that of their predecessors, concepts like shun (seasonality) and hin (refinement) still guide chefs today. Ultimately, then, based on interviews and participant observation conducted in and outside of the Japanese Cuisine Laboratory in 2012 and 2013, I argue that by engaging with contemporary food science, Kyoto's chefs achieve a strategic balance of protecting their culinary heritage while adapting it to contemporary circumstances.

  2. Continuity and Change: Kyoto Chefs Engage with Science.

    PubMed

    de St Maurice, Greg

    2015-01-01

    Kyoto's chefs have reacted proactively to changes brought about by the most recent phase of globalization, hoping to ensure the continued existence and resonance of Kyoto cuisine by using science to adapt it to contemporary circumstances. These chefs are breaking new ground in their pursuit of a scientific understanding of how Kyoto cuisine works. They meet once a month in a kitchen laboratory at Kyoto University to present and analyze culinary experiments in keeping with a predetermined theme. They use their acquired knowledge to more precisely hone their culinary skills and to explain Kyoto cuisine to a global audience. Chefs visit local elementary schools, appear on national television, and welcome chefs from abroad into their kitchens so that people across the world will better understand what authentic Kyoto cuisine consists of. Although these chefs' efforts are groundbreaking, there is also remarkable continuity to their approach. Not only has Kyoto cuisine always been in a steady state of transformation, but the chefs in the Laboratory are engaging with science and a global audience specifically so that they can ascertain Kyoto cuisine's continued existence and importance. Though their means of understanding and articulating what Kyoto cuisine is differs from that of their predecessors, concepts like shun (seasonality) and hin (refinement) still guide chefs today. Ultimately, then, based on interviews and participant observation conducted in and outside of the Japanese Cuisine Laboratory in 2012 and 2013, I argue that by engaging with contemporary food science, Kyoto's chefs achieve a strategic balance of protecting their culinary heritage while adapting it to contemporary circumstances. PMID:26598840

  3. The Call for an African University: A Critical Reflection

    ERIC Educational Resources Information Center

    van Wyk, Berte; Higgs, Philip

    2007-01-01

    In this paper, we draw on philosophy (particularly African philosophy) to analyse the call for an African university. The call for an African university may be viewed as a call that insists that all critical and transformative educators in Africa embrace an indigenous African worldview and root their nation's educational paradigms in an indigenous…

  4. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON RHIC SPIN PHYSICS III AND IV, POLARIZED PARTONS AT HIGH Q2 REGION, AUGUST 3, 2000 AT BNL, OCTOBER 14, 2000 AT KYOTO UNIVERSITY.

    SciTech Connect

    BUNCE, G.; VIGDOR, S.

    2001-03-15

    International workshop on II Polarized Partons at High Q2 region 11 was held at the Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan on October 13-14, 2000, as a satellite of the international conference ''SPIN 2000'' (Osaka, Japan, October 16-21,2000). This workshop was supported by RIKEN (The Institute of Physical and Chemical Research) and by Yukawa Institute. The scientific program was focused on the upcoming polarized collider RHIC. The workshop was also an annual meeting of RHIC Spin Collaboration (RSC). The number of participants was 55, including 28 foreign visitors and 8 foreign-resident Japanese participants, reflecting the international nature of the RHIC spin program. At the workshop there were 25 oral presentations in four sessions, (1) RHIC Spin Commissioning, (2) Polarized Partons, Present and Future, (3) New Ideas on Polarization Phenomena, (4) Strategy for the Coming Spin Running. In (1) the successful polarized proton commissioning and the readiness of the accelerator for the physics program impressed us. In (2) and (3) active discussions were made on the new structure function to be firstly measured at RHIC, and several new theoretical ideas were presented. In session (4) we have established a plan for the beam time requirement toward the first collision of polarized protons. These proceedings include the transparencies presented at the workshop. The discussion on ''Strategy for the Coming Spin Running'' was summarized by the chairman of the session, S. Vigdor and G. Bunce.

  5. Nondestructive verification with minimal movement of irradiated light-water-reactor fuel assemblies

    SciTech Connect

    Phillips, J.R.; Bosler, G.E.; Halbig, J.K.; Klosterbuer, S.F.; Menlove, H.O.

    1982-10-01

    Nondestructive verification of irradiated light-water reactor fuel assemblies can be performed rapidly and precisely by measuring their gross gamma-ray and neutron signatures. A portable system measured fuel assemblies with exposures ranging from 18.4 to 40.6 GWd/tU and with cooling times ranging from 1575 to 2638 days. Differences in the measured results for side or corner measurements are discussed. 25 figures, 20 tables.

  6. Fuel assembly for the production of tritium in light water reactors

    DOEpatents

    Cawley, William E.; Trapp, Turner J.

    1985-01-01

    A nuclear fuel assembly is described for producing tritium in a light water moderated reactor. The assembly consists of two intermeshing arrays of subassemblies. The first subassemblies comprise concentric annular elements of an outer containment tube, an annular target element, an annular fuel element, and an inner neutron spectrums shifting rod. The second subassemblies comprise an outer containment tube and an inner rod of either fuel, target, or neutron spectrum shifting neutral.

  7. Analysis of assembly serial number usage in domestic light-water reactors

    SciTech Connect

    Reich, W.J. ); Moore, R.S. )

    1991-05-01

    Domestic light-water reactor (LWR) fuel assemblies are identified by a serial number that is placed on each assembly. These serial numbers are used as identifiers throughout the life of the fuel. The uniqueness of assembly serial numbers is important in determining their effectiveness as unambiguous identifiers. The purpose of this study is to determine what serial numbering schemes are used, the effectiveness of these schemes, and to quantify how many duplicate serial numbers occur on domestic LWR fuel assemblies. The serial numbering scheme adopted by the American National Standards Institute (ANSI) ensures uniqueness of assembly serial numbers. The latest numbering scheme adopted by General Electric (GE), was also found to be unique. Analysis of 70,971 fuel assembly serial numbers from permanently discharged fuel identified 11,948 serial number duplicates. Three duplicate serial numbers were found when analysis focused on duplication within the individual fuel inventory at each reactor site, but these were traced back to data entry errors and will be corrected by the Energy Information Administration (EIA). There were also three instances where the serial numbers used to identify assemblies used for hot cell studies differed from the serial numbers reported to the EIA. It is recommended that fuel fabricators and utilities adhere to the ANSI serial numbering scheme to ensure serial number uniqueness. In addition, organizations collecting serial number information, should request that all known serial numbers physically attached or associated with each assembly be reported and identified by the corresponding number scheme. 10 refs., 5 tabs.

  8. Criticality experiments and analysis of molybdenum reflected cylindrical uranyl fluoride water solution reactors

    NASA Technical Reports Server (NTRS)

    Fieno, D.; Fox, T.; Mueller, R.

    1972-01-01

    Clean criticality data were obtained from molybdenum-reflected cylindrical uranyl-fluoride-water solution reactors. Using ENDF/B molybdenum cross sections, a nine energy group two-dimensional transport calculation of a reflected reactor configuration predicted criticality to within 7 cents of the experimental value. For these reactors, it was necessary to compute the reflector resonance integral by a detailed transport calculation at the core-reflector interface volume in the energy region of the two dominant resonances of natural molybdenum.

  9. Experiments on small-size fast critical fuel assemblies at the AKSAMIT facility and their use for development of computational models

    NASA Astrophysics Data System (ADS)

    Glushkov, E. S.; Glushkov, A. E.; Gomin, E. A.; Daneliya, S. B.; Zimin, A. A.; Kalugin, M. A.; Kapitonova, A. V.; Kompaniets, G. V.; Moroz, N. P.; Nosov, V. I.; Petrushenko, R. P.; Smirnov, O. N.

    2013-12-01

    Small-size fast critical assemblies with highly enriched fuel at the AKSAMIT facility are described in detail. Computational models of the critical assemblies at room temperature are given. The calculation results for the critical parameters are compared with the experimental data. A good agreement between the calculations and the experimental data is shown. The physical models developed for the critical assemblies, as well as the experimental results, can be applied to verify various codes intended for calculation of the neutronic characteristics of small-size fast nuclear reactors. For these experiments, the results computed using the codes of the MCU family show a high quality of the neutron data and of the physical models used.

  10. Critical Issues on Materials for Gen-IV Reactors

    SciTech Connect

    Caro, M; Marian, J; Martinez, E; Erhart, P

    2009-02-27

    Within the LDRD on 'Critical Issues on Materials for Gen-IV Reactors' basic thermodynamics of the Fe-Cr alloy and accurate atomistic modeling were used to help develop the capability to predict hardening, swelling and embrittlement using the paradigm of Multiscale Materials Modeling. Approaches at atomistic and mesoscale levels were linked to build-up the first steps in an integrated modeling platform that seeks to relate in a near-term effort dislocation dynamics to polycrystal plasticity. The requirements originated in the reactor systems under consideration today for future sources of nuclear energy. These requirements are beyond the present day performance of nuclear materials and calls for the development of new, high temperature, radiation resistant materials. Fe-Cr alloys with 9-12% Cr content are the base matrix of advanced ferritic/martensitic (FM) steels envisaged as fuel cladding and structural components of Gen-IV reactors. Predictive tools are needed to calculate structural and mechanical properties of these steels. This project represents a contribution in that direction. The synergy between the continuous progress of parallel computing and the spectacular advances in the theoretical framework that describes materials have lead to a significant advance in our comprehension of materials properties and their mechanical behavior. We took this progress to our advantage and within this LDRD were able to provide a detailed physical understanding of iron-chromium alloys microstructural behavior. By combining ab-initio simulations, many-body interatomic potential development, and mesoscale dislocation dynamics we were able to describe their microstructure evolution. For the first time in the case of Fe-Cr alloys, atomistic and mesoscale were merged and the first steps taken towards incorporating ordering and precipitation effects into dislocation dynamics (DD) simulations. Molecular dynamics (MD) studies of the transport of self-interstitial, vacancy and

  11. A fuel for sub-critical fast reactor

    SciTech Connect

    Moiseenko, V. E.; Chernitskiy, S. V.; Agren, O.; Noack, K.

    2012-06-19

    Along with the problem of the nuclear waste transmutation, the problem of minimization of waste production is of current interest. It is not possible to eliminate production of waste at a nuclear power plant, but, as is shown in this report, it is in principle possible to arrange a fuel composition with no net production of transuranic elements. The idea is to find the transuranic elements composition to which the depleted uranium is continuously supplied during frequent reprocessing, and amount of each other transuranic fuel component remains unchanged in time. For each transuranic component, the balance is achieved by equating burnup and production rates. The production is due to neutron capture by the neighboring lighter isotope and subsequent beta-decay. The burnup includes fission, neutron capture and decays. For the calculations a simplified burnup model which accounts for 9 isotopes of uranium, neptunium, plutonium and americium is used. The calculated fuel composition consists mainly of uranium with minority of plutonium isotopes. Such a fuel, after usage in a sub-critical fast reactor, should be reprocessed. The fission product content increases during burnup, representing a net production of waste, while the transuranic elements and {sup 238}U should be recycled into a new fuel. For such a fuel cycle, the net consumption is only for 238U, and the net waste production is just fission products.

  12. A fuel for sub-critical fast reactor

    NASA Astrophysics Data System (ADS)

    Moiseenko, V. E.; Chernitskiy, S. V.; Ågren, O.; Noack, K.

    2012-06-01

    Along with the problem of the nuclear waste transmutation, the problem of minimization of waste production is of current interest. It is not possible to eliminate production of waste at a nuclear power plant, but, as is shown in this report, it is in principle possible to arrange a fuel composition with no net production of transuranic elements. The idea is to find the transuranic elements composition to which the depleted uranium is continuously supplied during frequent reprocessing, and amount of each other transuranic fuel component remains unchanged in time. For each transuranic component, the balance is achieved by equating burnup and production rates. The production is due to neutron capture by the neighboring lighter isotope and subsequent beta-decay. The burnup includes fission, neutron capture and decays. For the calculations a simplified burnup model which accounts for 9 isotopes of uranium, neptunium, plutonium and americium is used. The calculated fuel composition consists mainly of uranium with minority of plutonium isotopes. Such a fuel, after usage in a sub-critical fast reactor, should be reprocessed. The fission product content increases during burnup, representing a net production of waste, while the transuranic elements and 238U should be recycled into a new fuel. For such a fuel cycle, the net consumption is only for 238U, and the net waste production is just fission products.

  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. Silicon carbide composite for light water reactor fuel assembly applications

    NASA Astrophysics Data System (ADS)

    Yueh, Ken; Terrani, Kurt A.

    2014-05-01

    The feasibility of using SiCf-SiCm composites in light water reactor (LWR) fuel designs was evaluated. The evaluation was motivated by the desire to improve fuel performance under normal and accident conditions. The Fukushima accident once again highlighted the need for improved fuel materials that can maintain fuel integrity to higher temperatures for longer periods of time. The review identified many benefits as well as issues in using the material. Issues perceived as presenting the biggest challenges to the concept were identified to be flux gradient induced differential volumetric swelling, fragmentation and thermal shock resistance. The oxidation of silicon and its release into the coolant as silica has been identified as an issue because existing plant systems have limited ability for its removal. Detailed evaluation using available literature data and testing as part of this evaluation effort have eliminated most of the major concerns. The evaluation identified Boiling Water Reactor (BWR) channel, BWR fuel water tube, and Pressurized Water Reactor (PWR) guide tube as feasible applications for SiC composite. A program has been initiated to resolve some of the remaining issues and to generate physical property data to support the design of commercial fuel components.

  15. PBF Reactor Building (PER620). Detail of fuel test assembly in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PBF Reactor Building (PER-620). Detail of fuel test assembly in preparation for test. When complete, it will fit into in-pile tube. The maximum outside diameter of which must be about 8.25 inches. Date: 1982. INEEL negative no. 82-4908 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  16. Research reactors

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    There are currently 284 research reactors in operation, and 12 under construction around the world. Of the operating reactors, nearly two-thirds are used exclusively for research, and the rest for a variety of purposes, including training, testing, and critical assembly. For more than 50 years, research reactor programs have contributed greatly to the scientific and educational communities. Today, six of the world`s research reactors are being shut down, three of which are in the USA. With government budget constraints and the growing proliferation concerns surrounding the use of highly enriched uranium in some of these reactors, the future of nuclear research could be impacted.

  17. Summary Report of Commercial reactor Criticality Data for Three Mile Island Unit 1

    SciTech Connect

    Larry B. Wimmer

    2001-08-29

    The objective of the ''Summary Report of Commercial Reactor Criticality Data for Three Mile Island Unit I'' is to present the CRC data for the TMI-1 reactor. Results from the CRC evaluations will support the development and validation of the neutronics models used for criticality analyses involving commercial spent nuclear fuel. These models and their validation are discussed in the ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2000).

  18. Temperature actuated shutdown assembly for a nuclear reactor

    DOEpatents

    Sowa, Edmund S.

    1976-01-01

    Three identical bimetallic disks, each shaped as a spherical cap with its convex side composed of a layer of metal such as molybdenum and its concave side composed of a metal of a relatively higher coefficient of thermal expansion such as stainless steel, are retained within flanges attached to three sides of an inner hexagonal tube containing a neutron absorber to be inserted into a nuclear reactor core. Each disk holds a metal ball against its normally convex side so that the ball projects partially through a hole in the tube located concentrically with the center of each disk; at a predetermined temperature an imbalance of thermally induced stresses in at least one of the disks will cause its convex side to become concave and its concave side to become convex, thus pulling the ball from the hole in which it is located. The absorber has a conical bottom supported by the three balls and is small enough in relation to the internal dimensions of the tube to allow it to slip toward the removed ball or balls, thus clearing the unremoved balls or ball so that it will fall into the reactor core.

  19. Scale-4 Analysis of Pressurized Water Reactor Critical Configurations: Volume 5 - North Anna Unit 1 Cycle 5

    SciTech Connect

    Bowman, S.M.

    1993-01-01

    The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor (AFR) criticality safety analyses be validated against experimental measurements. If credit for the negative reactivity of the depleted (or spent) fuel isotopics is desired, it is necessary to benchmark computational methods against spent fuel critical configurations. This report summarizes a portion of the ongoing effort to benchmark AFR criticality analysis methods using selected critical configurations from commercial pressurized-water reactors (PWR). The analysis methodology selected for all calculations reported herein was the codes and data provided in the SCALE-4 code system. The isotopic densities for the spent fuel assemblies in the critical configurations were calculated using the SAS2H analytical sequence of the SCALE-4 system. The sources of data and the procedures for deriving SAS2H input parameters are described in detail. The SNIKR code module was used to extract the necessary isotopic densities from the SAS2H results and to provide the data in the format required by the SCALE criticality analysis modules. The CSASN analytical sequence in SCALE-4 was used to perform resonance processing of the cross sections. The KENO V.a module of SCALE-4 was used to calculate the effective multiplication factor (k{sub eff}) of each case. The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides) and ENDF/B-V (fission products) data was used for all the calculations. This volume of the report documents the SCALE system analysis of one reactor critical configuration for North Anna Unit 1 Cycle 5. This unit and cycle were chosen for a previous analysis using a different methodology because detailed isotopics from multidimensional reactor calculations were available from the Virginia Power Company. These data permitted comparison of criticality calculations directly using the utility-calculated isotopics to those using the isotopics generated by the SCALE-4 SAS2H

  20. Planar ceramic membrane assembly and oxidation reactor system

    DOEpatents

    Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohm, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, deceased, Paul Nigel

    2007-10-09

    Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

  1. Planar ceramic membrane assembly and oxidation reactor system

    DOEpatents

    Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohrn, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, Paul Nigel

    2009-04-07

    Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

  2. REACTOR

    DOEpatents

    Szilard, L.

    1963-09-10

    A breeder reactor is described, including a mass of fissionable material that is less than critical with respect to unmoderated neutrons and greater than critical with respect to neutrons of average energies substantially greater than thermal, a coolant selected from sodium or sodium--potassium alloys, a control liquid selected from lead or lead--bismuth alloys, and means for varying the quantity of control liquid in the reactor. (AEC)

  3. Metallosupramolecular self-assembly of a universal 3-ravel.

    PubMed

    Li, Feng; Clegg, Jack K; Lindoy, Leonard F; Macquart, René B; Meehan, George V

    2011-02-22

    In the realm of supramolecular chemistry, a small number of intricately interwoven structures that bridge the boundaries between art and science have been reported. These motifs, which typically form on the nanometre scale, display both considerable beauty and complexity. However, the generation of new topologies of this type has remained a very significant synthetic challenge. Here, we describe the synthesis of a discrete highly intertwined metallosupramolecular assembly based on a universal 3-ravel motif-a topology as yet unprecedented in supramolecular chemistry. The exotic, 20-component, [Fe(8)L(12)] ravel entanglement may be considered as a 'branched knot', with individual molecules displaying either left- or right-handed chirality. The formation of this cluster was demonstrated by single-crystal and powder X-ray diffraction. The arrangement is stabilized by a favourable combination of π-π interactions and Nature's tendency to minimize voids in molecular architectures.

  4. Inverted rank distributions: Macroscopic statistics, universality classes, and critical exponents

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo; Cohen, Morrel H.

    2014-01-01

    An inverted rank distribution is an infinite sequence of positive sizes ordered in a monotone increasing fashion. Interlacing together Lorenzian and oligarchic asymptotic analyses, we establish a macroscopic classification of inverted rank distributions into five “socioeconomic” universality classes: communism, socialism, criticality, feudalism, and absolute monarchy. We further establish that: (i) communism and socialism are analogous to a “disordered phase”, feudalism and absolute monarchy are analogous to an “ordered phase”, and criticality is the “phase transition” between order and disorder; (ii) the universality classes are characterized by two critical exponents, one governing the ordered phase, and the other governing the disordered phase; (iii) communism, criticality, and absolute monarchy are characterized by sharp exponent values, and are inherently deterministic; (iv) socialism is characterized by a continuous exponent range, is inherently stochastic, and is universally governed by continuous power-law statistics; (v) feudalism is characterized by a continuous exponent range, is inherently stochastic, and is universally governed by discrete exponential statistics. The results presented in this paper yield a universal macroscopic socioeconophysical perspective of inverted rank distributions.

  5. Black holes and universality classes of critical points.

    PubMed

    Kovtun, Pavel; Ritz, Adam

    2008-05-01

    We argue that there exists an infinite class of conformal field theories in diverse dimensions having a universal ratio of the central charge c to the normalized entropy density c. The universality class includes all conformal theories which possess a classical gravity dual according to the AdS/CFT correspondence. From the practical point of view, the universality of c/c provides an explicit test which can be applied to determine whether a given critical point may admit a dual description in terms of classical gravity.

  6. Physical characteristics of non-fuel assembly reactor components

    SciTech Connect

    Hawkes, E.C.

    1994-09-01

    The primary objective of this report is to enhance the utility of the Characteristics Data Base (CDB). This has been accomplished by providing a pictorial representation of the principal non-fuel assembly (NFA) components along with a tabular summary of key information about each type of component. This report is intended for use as an adjunct to the CDB. Toward this end, the report may be used either as a complement to the detailed descriptions in the CDB, or as a stand-alone document that acts as an illustrated abstract of the CDB. Line drawings of major NFA components are included. Data not provided in the CDB are also included. Summary descriptions of each component are given in tabular format.

  7. A Theoretical Investigation of Oxidation Efficiency of a Volatile Removal Assembly Reactor Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Guo, Boyun

    2005-01-01

    Volatile Removal Assembly (VRA) is a subsystem of the Closed Environment Life Support System (CELSS) installed in the International Space Station. It is used for removing contaminants (volatile organics) in the wastewater produced by the space station crews. The major contaminants are formic acid, ethanol, and propylene glycol. The VRA contains a slim packbed reactor (3.5 cm diameter and four 28 cm long tubes in series) to perform catalyst oxidation of wastewater at elevated pressure and temperature under microgravity conditions. In the reactor, the contaminants are burned with oxygen gas (O2) to form water and carbon dioxide (CO2) that dissolves in the water stream. Optimal design of the reactor requires a thorough understanding about how the reactor performs under microgravity conditions. The objective of this study was to develop a mathematical model to interpret experimental data obtained from normal and microgravity conditions, and to predict the performance of VRA reactor under microgravity conditions. Catalyst oxidation kinetics and the total oxygen-water contact area control the efficiency of catalyst oxidation for mass transfer, which depends on oxygen gas holdup and distribution in the reactor. The process involves bubbly flow in porous media with chemical reactions in microgravity environment. This presents a unique problem in fluid dynamics that has not been studied. Guo et al. (2004) developed a mathematical model that predicts oxygen holdup in the VRA reactor. No mathematical model has been found in the literature that can be used to predict the efficiency of catalyst oxidation under microgravity conditions.

  8. Three-dimensional discrete ordinates reactor assembly calculations on GPUs

    SciTech Connect

    Evans, Thomas M; Joubert, Wayne; Hamilton, Steven P; Johnson, Seth R; Turner, John A; Davidson, Gregory G; Pandya, Tara M

    2015-01-01

    In this paper we describe and demonstrate a discrete ordinates sweep algorithm on GPUs. This sweep algorithm is nested within a multilevel comunication-based decomposition based on energy. We demonstrated the effectiveness of this algorithm on detailed three-dimensional critical experiments and PWR lattice problems. For these problems we show improvement factors of 4 6 over conventional communication-based, CPU-only sweeps. These sweep kernel speedups resulted in a factor of 2 total time-to-solution improvement.

  9. Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods (1.506-cm Pitch)

    SciTech Connect

    Margaret A. Marshall

    2013-03-01

    A series of critical experiments were completed from 1962–1965 at Oak Ridge National Laboratory’s (ORNL’s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study “power plants for the production of electrical power in space vehicles.”(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967.a The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were performed to determine critical reflector arrangements, relative fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector” (see Reference 1). The experiment studied in this evaluation was the second of the series and had the fuel rods in a 1.506-cm-triangular pitch. One critical configuration was found (see Reference 3). Once the critical configuration had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U,bc and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configuration are described in Sections 1.3, 1.4, and 1.7, respectively.

  10. Kyoto Tridimensional Spectrograph II

    NASA Astrophysics Data System (ADS)

    Sugai, Hajime; Ohtani, Hiroshi; Ishigaki, Tsuyoshi; Hayashi, Tadashi; Ozaki, Shinobu; Hattori, Takashi; Ishii, M.; Sasaki, Minoru; Takeyama, Norihide

    1998-07-01

    We are building the second version of the Kyoto Tridimensional Spectrograph (Ohtani et al., this symposium). This will be mounted on the MAGNUM, a 2-m telescope under construction at Haleakala, and also on the SUBARU. The spectrograph has four observational modes: Fabry-Perot imager, integral field spectrograph (IFS) with a microlens array, long-slit spectrograph, and filter-imaging modes. The new spectrograph is significantly better than the first version in several ways. The IFS has as many as 37 X 37 microlenses, each of which subtends 0' .39 at the MAGNUM. The optics is designed to be used in wide wavelength ranges from 360 nm to 900 nm. The transmission at any wavelength between 370 and 900 nm is designed to exceed 50% for the collimator plus camera system, and to reach almost 40% even at 360 nm. In order to achieve high efficiency at short wavelengths, we use an anti- reflection coated backside-illuminated 2K X 2K CCD. We are also planning a further improvement by using multi-layer anti- reflection coatings for lenses, in collaboration with National Astronomical Observatory, Japan. In order to assure good image quality under a severe weight limit of 150 kg for this instrument, we have carried out mechanical design by calculating the flexure of the instrument for all telescope attitudes with finite element analysis, and succeeded in limiting the maximum flexure to 30 micrometer. This does not degrade image quality. The movements on the CCD of the light from the center of the focal plane have also been simulated, depending on the telescope attitudes. This is important to obtain not only a good image, but also a correct flat field and wavelength calibration in the IFS mode. The movements are expected to be confined almost within one pixel for an attitude, which is considered to be small enough.

  11. Waterproofed photomultiplier tube assemblies for the Daya Bay reactor neutrino experiment

    NASA Astrophysics Data System (ADS)

    Chow, Ken; Cummings, John; Edwards, Emily; Edwards, William; Ely, Ry; Hoff, Matthew; Lebanowski, Logan; Li, Bo; Li, Piyi; Lin, Shih-Kai; Liu, Dawei; Liu, Jinchang; Luk, Kam-Biu; Miao, Jiayuan; Napolitano, Jim; Ochoa-Ricoux, Juan Pedro; Peng, Jen-Chieh; Qi, Ming; Steiner, Herbert; Stoler, Paul; Stuart, Mary; Wang, Lingyu; Yang, Changgen; Zhong, Weili

    2015-09-01

    In the Daya Bay Reactor Neutrino Experiment 960 20-cm-diameter waterproof photomultiplier tubes are used to instrument three water pools as Cherenkov detectors for detecting cosmic-ray muons. Of these 960 photomultiplier tubes, 341 are recycled from the MACRO experiment. A systematic program was undertaken to refurbish them as waterproof assemblies. In the context of passing the water leakage check, a success rate better than 97% was achieved. Details of the design, fabrication, testing, operation, and performance of these waterproofed photomultiplier-tube assemblies are presented.

  12. Spectroscopic critical dimension technology (SCD) for directed self assembly

    NASA Astrophysics Data System (ADS)

    Nishibe, Senichi; Dziura, Thaddeus; Nagaswami, Venkat; Gronheid, Roel

    2014-04-01

    Directed self-assembly (DSA) is being actively investigated as a potential patterning solution for future generation devices. While SEM based CD measurement is currently used in research and development, scatterometry-based techniques like spectroscopic CD (SCD) are preferred for high volume manufacturing. SCD can offer information about sub-surface features that are not available from CD-SEM measurement. Besides, SCD is a non-destructive, high throughput technique already adopted in HVM in several advanced nodes. The directed self assembly CD measurement can be challenging because of small dimensions and extremely thin layers in the DSA stack. In this study, the SCD technology was investigated for a 14 nm resolution PS-b-PMMA chemical epitaxy UW process optimized by imec. The DSA stack involves new materials such as cross-linkable polysterene (XPS) of thickness approximately 5 nm, ArF immersion resist (subsequently removed), -OH terminated neutral brush layer, and BCP material (Polystyrene-blockmethyl methacrylate of thickness roughly 20 to 30 nm). The mask contains a large CD and pitch matrix, for studying the quality of self-assembly as a function of the guide pattern dimensions. We report on the ability of SCD to characterize the dimensional variation in these targets and hence provide a viable process control solution.

  13. The Ohio State University Reactor Sharing Program [August 15, 2000 - May 31, 2001

    SciTech Connect

    Myser, Richard D.

    2002-01-04

    During the period from August 15, 2000 through may 31, 2001 the Ohio State University (OSU) Research Reactor participated in the Reactor Sharing Program by providing services to nine colleges and universities and four secondary school organizations. A total of about 17 faculty and 170 students utilized their facilities. The staff of the OSU Research Reactor is generally involved in four types of experiments at the Nuclear Reactor Laboratory. Included are introductions to nuclear research, neutron activation analysis, material irradiation, and classes that measure various reactor parameters.

  14. Nuclear reactor fuel assembly duct-tube-to-inlet-nozzle attachment system

    DOEpatents

    Christiansen, David W.; Smith, Bob G.

    1982-01-01

    A reusable system for removably attaching the lower end 21 of a nuclear reactor fuel assembly duct tube to an upper end 11 of a nuclear reactor fuel assembly inlet nozzle. The duct tube's lower end 21 has sides terminating in locking tabs 22 which end in inwardly-extending flanges 23. The flanges 23 engage recesses 13 in the top section 12 of the inlet nozzle's upper end 11. A retaining collar 30 slides over the inlet nozzle's upper end 11 to restrain the flanges 23 in the recesses 13. A locking nut 40 has an inside threaded portion 41 which engages an outside threaded portion 15 of the inlet nozzle's upper end 11 to secure the retaining collar 30 against protrusions 24 on the duct tube's sides.

  15. Assemblies and methods for mitigating effects of reactor pressure vessel expansion

    DOEpatents

    Challberg, Roy C.; Gou, Perng-Fei; Chu, Cherk Lam; Oliver, Robert P.

    1999-01-01

    Support assemblies for allowing RPV radial expansion while simultaneously limiting horizontal, vertical, and azimuthal movement of the RPV within a nuclear reactor are described. In one embodiment, the support assembly includes a support block and a guide block. The support block includes a first portion and a second portion, and the first portion is rigidly coupled to the RPV adjacent the first portion. The guide block is rigidly coupled to a reactor pressure vessel support structure and includes a channel sized to receive the second portion of the support block. The second portion of the support block is positioned in the guide block channel to movably couple the guide block to the support block.

  16. Assemblies and methods for mitigating effects of reactor pressure vessel expansion

    DOEpatents

    Challberg, R.C.; Gou, P.F.; Chu, C.L.; Oliver, R.P.

    1999-07-27

    Support assemblies for allowing RPV radial expansion while simultaneously limiting horizontal, vertical, and azimuthal movement of the RPV within a nuclear reactor are described. In one embodiment, the support assembly includes a support block and a guide block. The support block includes a first portion and a second portion, and the first portion is rigidly coupled to the RPV adjacent the first portion. The guide block is rigidly coupled to a reactor pressure vessel support structure and includes a channel sized to receive the second portion of the support block. The second portion of the support block is positioned in the guide block channel to movably couple the guide block to the support block. 6 figs.

  17. Universal quantum correlation close to quantum critical phenomena

    PubMed Central

    Qin, Meng; Ren, Zhong-Zhou; Zhang, Xin

    2016-01-01

    We study the ground state quantum correlation of Ising model in a transverse field (ITF) by implementing the quantum renormalization group (QRG) theory. It is shown that various quantum correlation measures and the Clauser-Horne-Shimony-Holt inequality will highlight the critical point related with quantum phase transitions, and demonstrate nonanalytic phenomena and scaling behavior when the size of the systems becomes large. Our results also indicate a universal behavior of the critical exponent of ITF under QRG theory that the critical exponent of different measures is identical, even when the quantities vary from entanglement measures to quantum correlation measures. This means that the two kinds of quantum correlation criterion including the entanglement-separability paradigm and the information-theoretic paradigm have some connections between them. These remarkable behaviors may have important implications on condensed matter physics because the critical exponent directly associates with the correlation length exponent. PMID:27189504

  18. A universal mechanism of extreme events and critical phenomena

    PubMed Central

    Wu, J. H.; Jia, Q.

    2016-01-01

    The occurrence of extreme events and critical phenomena is of importance because they can have inquisitive scientific impact and profound socio-economic consequences. Here we show a universal mechanism describing extreme events along with critical phenomena and derive a general expression of the probability distribution without concerning the physical details of individual events or critical properties. The general probability distribution unifies most important distributions in the field and demonstrates improved performance. The shape and symmetry of the general distribution is determined by the parameters of the fluctuations. Our work sheds judicious insights into the dynamical processes of complex systems with practical significance and provides a general approach of studying extreme and critical episodes in a combined and multidisciplinary scheme. PMID:26880219

  19. Universal quantum correlation close to quantum critical phenomena.

    PubMed

    Qin, Meng; Ren, Zhong-Zhou; Zhang, Xin

    2016-05-18

    We study the ground state quantum correlation of Ising model in a transverse field (ITF) by implementing the quantum renormalization group (QRG) theory. It is shown that various quantum correlation measures and the Clauser-Horne-Shimony-Holt inequality will highlight the critical point related with quantum phase transitions, and demonstrate nonanalytic phenomena and scaling behavior when the size of the systems becomes large. Our results also indicate a universal behavior of the critical exponent of ITF under QRG theory that the critical exponent of different measures is identical, even when the quantities vary from entanglement measures to quantum correlation measures. This means that the two kinds of quantum correlation criterion including the entanglement-separability paradigm and the information-theoretic paradigm have some connections between them. These remarkable behaviors may have important implications on condensed matter physics because the critical exponent directly associates with the correlation length exponent.

  20. Fission reactor neutron sources for neutron capture therapy--a critical review.

    PubMed

    Harling, Otto K; Riley, Kent J

    2003-01-01

    The status of fission reactor-based neutron beams for neutron capture therapy (NCT) is reviewed critically. Epithermal neutron beams, which are favored for treatment of deep-seated tumors, have been constructed or are under construction at a number of reactors worldwide. Some of the most recently constructed epithermal neutron beams approach the theoretical optimum for beam purity. Of these higher quality beams, at least one is suitable for use in high through-put routine therapy. It is concluded that reactor-based epithermal neutron beams with near optimum characteristics are currently available and more can be constructed at existing reactors. Suitable reactors include relatively low power reactors using the core directly as a source of neutrons or a fission converter if core neutrons are difficult to access. Thermal neutron beams for NCT studies with small animals or for shallow tumor treatments, with near optimum properties have been available at reactors for many years. Additional high quality thermal beams can also be constructed at existing reactors or at new, small reactors. Furthermore, it should be possible to design and construct new low power reactors specifically for NCT, which meet all requirements for routine therapy and which are based on proven and highly safe reactor technology.

  1. 77 FR 27487 - License Amendment Request From The State University of New York, University of Buffalo Reactor...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-10

    ... accordance with the NRC E-Filing rule (72 FR 49139, August 28, 2007). The E-Filing process requires... COMMISSION License Amendment Request From The State University of New York, University of Buffalo Reactor....resource@nrc.gov . The University of Buffalo Decommissioning Plan and License Amendment Request...

  2. A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES

    SciTech Connect

    Kurt D. Hamman; Ray A. Berry

    2008-09-01

    A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly “benchmark” geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k-e and SST (Menter) k-? were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need for wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.

  3. Reactor Physics and Criticality Benchmark Evaluations for Advanced Nuclear Fuel - Final Technical Report

    SciTech Connect

    William Anderson; James Tulenko; Bradley Rearden; Gary Harms

    2008-09-11

    The nuclear industry interest in advanced fuel and reactor design often drives towards fuel with uranium enrichments greater than 5 wt% 235U. Unfortunately, little data exists, in the form of reactor physics and criticality benchmarks, for uranium enrichments ranging between 5 and 10 wt% 235U. The primary purpose of this project is to provide benchmarks for fuel similar to what may be required for advanced light water reactors (LWRs). These experiments will ultimately provide additional information for application to the criticality-safety bases for commercial fuel facilities handling greater than 5 wt% 235U fuel.

  4. Partial Defect Verification of the Pressurized Water Reactor Spent Fuel Assemblies

    SciTech Connect

    Ham, Y S; Sitaraman, S

    2010-02-05

    The International Atomic Energy Agency (IAEA) has the responsibility to carry out independent inspections of all nuclear material and facilities subject to safeguards agreements in order to verify compliance with non-proliferation commitments. New technologies have been continuously explored by the IAEA and Member States to improve the verification measures to account for declared inventory of nuclear material and detect clandestine diversion and production of nuclear materials. Even with these efforts, a technical safeguards challenge has remained for decades for the case of developing a method in identifying possible diversion of nuclear fuel pins from the Light Water Reactor (LWR) spent fuel assemblies. We had embarked on this challenging task and successfully developed a novel methodology in detecting partial removal of fuel from pressurized water reactor spent fuel assemblies. The methodology uses multiple tiny neutron and gamma detectors in the form of a cluster and a high precision driving system to obtain underwater radiation measurements inside a Pressurized Water Reactor (PWR) spent fuel assembly without any movement of the fuel. The data obtained in such a manner can provide spatial distribution of neutron and gamma flux within a spent fuel assembly. The combined information of gamma and neutron signature is used to produce base signatures and they are principally dependent on the geometry of the detector locations, and exhibit little sensitivity to initial enrichment, burn-up or cooling time. A small variation in the fuel bundle such as a few missing pins changes the shape of the signature to enable detection. This resulted in a breakthrough method which can be used to detect pin diversion without relying on the nuclear power plant operator's declared operation data. Presented are the results of various Monte Carlo simulation studies and experiments from actual commercial PWR spent fuel assemblies.

  5. Preliminary study on new configuration with LEU fuel assemblies for the Dalat nuclear research reactor

    SciTech Connect

    Van Lam Pham; Vinh Vinh Le; Ton Nghiem Huynh; Ba Vien Luong; Kien Cuong Nguyen

    2008-07-15

    The fuel conversion of the Dalat Nuclear Research Reactor (DNRR) is being realized. The DNRR is a pool type research reactor which was reconstructed from the 250 kW TRIGA- MARK II reactor. The reconstructed reactor attained its nominal power of 500 kW in February 1984. According to the results of design and safety analyses performed by the joint study between RERTR Program at Argonne National Laboratory (ANL) and Vietnam Atomic Energy Commission (VAEC) the mixed core of irradiated HEU and new LEU WWR-M2 fuel assemblies will be created soon. This paper presents the results of preliminary study on new configuration with only LEU fuel assemblies for the DNRR. The codes MCNP, REBUS and VARI3D are used to calculate neutron flux performance in irradiation positions and kinetics parameters. The idea of change of Beryllium rod reloading enables to get working configuration assured shutdown margin, thermal-hydraulic safety and increase in thermal neutron flux in neutron trap at the center of DNRR active core. (author)

  6. Critical factors for assembling a high volume of DNA barcodes

    PubMed Central

    Hajibabaei, Mehrdad; deWaard, Jeremy R; Ivanova, Natalia V; Ratnasingham, Sujeevan; Dooh, Robert T; Kirk, Stephanie L; Mackie, Paula M; Hebert, Paul D.N

    2005-01-01

    Large-scale DNA barcoding projects are now moving toward activation while the creation of a comprehensive barcode library for eukaryotes will ultimately require the acquisition of some 100 million barcodes. To satisfy this need, analytical facilities must adopt protocols that can support the rapid, cost-effective assembly of barcodes. In this paper we discuss the prospects for establishing high volume DNA barcoding facilities by evaluating key steps in the analytical chain from specimens to barcodes. Alliances with members of the taxonomic community represent the most effective strategy for provisioning the analytical chain with specimens. The optimal protocols for DNA extraction and subsequent PCR amplification of the barcode region depend strongly on their condition, but production targets of 100K barcode records per year are now feasible for facilities working with compliant specimens. The analysis of museum collections is currently challenging, but PCR cocktails that combine polymerases with repair enzyme(s) promise future success. Barcode analysis is already a cost-effective option for species identification in some situations and this will increasingly be the case as reference libraries are assembled and analytical protocols are simplified. PMID:16214753

  7. Analysis on burnup step effect for evaluating reactor criticality and fuel breeding ratio

    SciTech Connect

    Saputra, Geby; Purnama, Aditya Rizki; Permana, Sidik; Suzuki, Mitsutoshi

    2014-09-30

    Criticality condition of the reactors is one of the important factors for evaluating reactor operation and nuclear fuel breeding ratio is another factor to show nuclear fuel sustainability. This study analyzes the effect of burnup steps and cycle operation step for evaluating the criticality condition of the reactor as well as the performance of nuclear fuel breeding or breeding ratio (BR). Burnup step is performed based on a day step analysis which is varied from 10 days up to 800 days and for cycle operation from 1 cycle up to 8 cycles reactor operations. In addition, calculation efficiency based on the variation of computer processors to run the analysis in term of time (time efficiency in the calculation) have been also investigated. Optimization method for reactor design analysis which is used a large fast breeder reactor type as a reference case was performed by adopting an established reactor design code of JOINT-FR. The results show a criticality condition becomes higher for smaller burnup step (day) and for breeding ratio becomes less for smaller burnup step (day). Some nuclides contribute to make better criticality when smaller burnup step due to individul nuclide half-live. Calculation time for different burnup step shows a correlation with the time consuming requirement for more details step calculation, although the consuming time is not directly equivalent with the how many time the burnup time step is divided.

  8. Criticality safety research at the University of Tennessee-Knoxville

    SciTech Connect

    Dodds, H.L.

    1997-06-01

    A list of seven research projects in nuclear criticality safety being conducted at the University of Tennessee is given. One of the projects is very briefly described. The study of space-dependent kinetics analysis of a hypothetical criticality accident involving an array of bottles containing UO{sub 2}F{sub 2} is being conducted for the US DOE, Oak Ridge National Laboratory, K-25 plant. Preliminary results for power versus time are presented, which indicate that space-time effects are significant after approximately 70 seconds. 2 refs., 1 fig.

  9. REACTOR

    DOEpatents

    Christy, R.F.

    1961-07-25

    A means is described for co-relating the essential physical requirements of a fission chain reaction in order that practical, compact, and easily controllable reactors can be built. These objects are obtained by employing a composition of fissionsble isotope and moderator in fluid form in which the amount of fissionsble isotcpe present governs the reaction. The size of the reactor is no longer a critical factor, the new criterion being the concentration of the fissionable isotope.

  10. Scale-4 Analysis of Pressurized Water Reactor Critical Configurations: Volume 4-Three Mile Island Unit 1 Cycle 5

    SciTech Connect

    DeHart, M.D.

    1995-01-01

    The requirements of ANSI/ANS-8.1 specify that calculational methods for away-from-reactor criticality safety analyses be validated against experimental measurements. If credit is to be taken for the reduced reactivity of burned or spent fuel relative to its original ''fresh'' composition, it is necessary to benchmark computational methods used in determining such reactivity worth against spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to benchmark away-from-reactor criticality analysis methods using relevant and well-documented critical configurations from commercial pressurized water reactors. The analysis methodology utilized for all calculations in this report is based on the modules and data associated with the SCALE-4 code system. Isotopic densities for spent fuel assemblies in the core were calculated using the SCALE-4 SAS2H analytical sequence. The sources of data and the procedures for deriving SAS2H input parameters are described in detail. The SNIKR code family was used to extract the necessary isotopic densities from SAS2H results and to provide the data in the format required for SCALE criticality analysis modules. The CSASN analytical sequence in SCALE-4 was used to perform resonance processing of cross sections. The KENO V.a module of SCALE-4 was used to calculate the effective multiplication factor (k{sub eff}) for the critical configuration. The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides) and ENDF/B-V (fission products) data was used for all calculations. This volume of the report documents a reactor critical calculation for GPU Nuclear Corporation's Three Mile Island Unit 1 (TMI-1) during hot, zero-power startup testing for the beginning of cycle 5. This unit and cycle were selected because of their relevance in spent fuel benchmark applications: (1) cycle 5 startup occurred after an especially long downtime of 6.6 years; and (2) the core consisted primarily (75%) of burned fuel, with

  11. Critical Configuration and Physics Mesaurements for Graphite Reflected Assemblies of U(93.15)O2 Fuel Rods (1.27-CM Pitch)

    SciTech Connect

    Margaret A. Marshall

    2011-09-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory's Critical Experiments Facility in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950's efforts were made to study 'power plants for the production of electrical power in space vehicles'. The MPRE program was a part of those efforts and studied the feasibility of a stainless steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in FY 1964, 1965, and 1966. A summary of the program's effort was compiled in 1967. The delayed critical experiments served as a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated 253 stainless steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. 'The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.' The experiment studied within this evaluation was the first of the series and had the 253 fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank. Two critical configurations were found by varying the amount of graphite reflector (References 1 and 2). Information for this evaluation was compiled from Reference 1 and 2, reports on subsequent experiments in the series, and the experimental logbook as well as from communication with the experimenter, John T. Mihalczo.

  12. Guidelines for preparing criticality safety evaluations at Department of Energy non-reactor nuclear facilities

    SciTech Connect

    Not Available

    1993-11-01

    This document contains guidelines that should be followed when preparing Criticality Safety Evaluations that will be used to demonstrate the safety of operations performed at DOE non-reactor nuclear facilities. Adherence to these guidelines will provide consistency and uniformity in criticality safety evaluations (CSEs) across the complex and will document compliance with the requirements of DOE Order 5480.24.

  13. Modular assembly for supporting, straining, and directing flow to a core in a nuclear reactor

    DOEpatents

    Pennell, William E.

    1977-01-01

    A reactor core support arrangement for supporting, straining, and providing fluid flow to the core and periphery of a nuclear reactor during normal operation. A plurality of removable inlet modular units are contained within permanent liners in the lower supporting plate of the reactor vessel lower internals. During normal operation (1) each inlet modular unit directs main coolant flow to a plurality of core assemblies, the latter being removably supported in receptacles in the upper portion of the modular unit and (2) each inlet modular unit may direct bypass flow to a low pressure annular region of the reactor vessel. Each inlet modular unit may include special fluid seals interposed between mating surfaces of the inlet modular units and the core assemblies and between the inlet modular units and the liners, to minimize leakage and achieve an hydraulic balance. Utilizing the hydraulic balance, the modular units are held in the liners and the assemblies are held in the modular unit receptacles by their own respective weight. Included as part of the permanent liners below the horizontal support plate are generally hexagonal axial debris barriers. The axial debris barriers collectively form a bottom boundary of a secondary high pressure plenum, the upper boundary of which is the bottom surface of the horizontal support plate. Peripheral liners include radial debris barriers which collectively form a barrier against debris entry radially. During normal operation primary coolant inlet openings in the liner, below the axial debris barriers, pass a large amount of coolant into the inlet modular units, and secondary coolant inlet openings in the portion of the liners within the secondary plenum pass a small amount of coolant into the inlet modular units. The secondary coolant inlet openings also provide alternative coolant inlet flow paths in the unlikely event of blockage of the primary inlet openings. The primary inlet openings have characteristics which limit the

  14. Independent Confirmatory Survey Report for the University of Arizona Nuclear Reactor Laboratory, Tucson, Arizona

    SciTech Connect

    Nick A. Altic

    2011-11-11

    The University of Arizona (University) research reactor is a TRIGA swimming pool type reactor designed by General Atomics and constructed at the University in 1958. The reactor first went into operation in December of 1958 under U.S. Nuclear Regulatory Commission (NRC) license R-52 until final shut down on May 18, 2010. Initial site characterization activities were conducted in February 2009 during ongoing reactor operations to assess the radiological status of the Nuclear Reactor Laboratory (NRL) excluding the reactor tank, associated components, and operating systems. Additional post-shutdown characterization activities were performed to complete characterization activities as well as verify assumptions made in the Decommissioning Plan (DP) that were based on a separate activation analysis (ESI 2009 and WMG 2009). Final status survey (FSS) activities began shortly after the issuance of the FSS plan in May 2011. The contractor completed measurement and sampling activities during the week of August 29, 2011.

  15. Reactor Testing and Qualification: Prioritized High-level Criticality Testing Needs

    SciTech Connect

    S. Bragg-Sitton; J. Bess; J. Werner; G. Harms; S. Bailey

    2011-09-01

    Researchers at the Idaho National Laboratory (INL) were tasked with reviewing possible criticality testing needs to support development of the fission surface power system reactor design. Reactor physics testing can provide significant information to aid in development of technologies associated with small, fast spectrum reactors that could be applied for non-terrestrial power systems, leading to eventual system qualification. Several studies have been conducted in recent years to assess the data and analyses required to design and build a space fission power system with high confidence that the system will perform as designed [Marcille, 2004a, 2004b; Weaver, 2007; Parry et al., 2008]. This report will provide a summary of previous critical tests and physics measurements that are potentially applicable to the current reactor design (both those that have been benchmarked and those not yet benchmarked), summarize recent studies of potential nuclear testing needs for space reactor development and their applicability to the current baseline fission surface power (FSP) system design, and provide an overview of a suite of tests (separate effects, sub-critical or critical) that could fill in the information database to improve the accuracy of physics modeling efforts as the FSP design is refined. Some recommendations for tasks that could be completed in the near term are also included. Specific recommendations on critical test configurations will be reserved until after the sensitivity analyses being conducted by Los Alamos National Laboratory (LANL) are completed (due August 2011).

  16. Agreement between University of Hawaii Professional Assembly and the Board of Regents of the University of Hawaii, 1987-1989.

    ERIC Educational Resources Information Center

    National Education Association, Washington, DC.

    The collective bargaining agreement between University of Hawaii Professional Assembly and the Board of Regents of the University of Hawaii for the period 1987-1989 is presented. Items covered in the agreement include: unit recognition, outside employment, exemption from tuition, duty period, paid and unpaid leaves of absence, sabbatical leaves,…

  17. Conceptual studies for pressurised water reactor cores employing plutonium erbium zirconium oxide inert matrix fuel assemblies

    NASA Astrophysics Data System (ADS)

    Stanculescu, A.; Kasemeyer, U.; Paratte, J.-M.; Chawla, R.

    1999-08-01

    The most efficient way to enhance plutonium consumption in light water reactors is to eliminate the production of plutonium all together. This requirement leads to fuel concepts in which the uranium is replaced by an inert matrix. At PSI, studies have focused on employing ZrO 2 as inert matrix. Adding a burnable poison to such a fuel proves to be necessary. As a result of scoping studies, Er 2O 3 was identified as the most suitable burnable poison material. The results of whole-core three-dimensional neutronics analyses indicated, for a present-day 1000 MW e pressurised water reactor (PWR), the feasibility of an asymptotic equilibrium four-batch cycle fuelled solely with the proposed PuO 2-Er 2O 3-ZrO 2 inert matrix fuel (IMF). The present paper presents the results of more recent investigations related to `real-life' situations, which call for transition configurations in which mixed IMF and UO 2 assembly loadings must be considered. To determine the influence of the introduction of IMF assemblies on the characteristics of a UO 2-fuelled core, three-dimensional full-core calculations have been performed for a present-day 1000 MW e PWR containing up to 12 optimised IMF assemblies.

  18. Analysis of Critical Reactor Response for TOPAZ-II Water Immersion Scenarios

    NASA Astrophysics Data System (ADS)

    Ponomarev-Stepnoi, Nikolai N.; Glushkov, Yevgeny S.; Yermoshin, Mikhail Y.; Skorlygin, Vladimir V.

    1994-07-01

    The unmodified TOPAZ-II water immersion event leading to surrounding the reactor with water and filling with water all internal core cavities (including TFE NaK channels) may hypothetically result in criticality. This paper presents results of preliminary studies of such an accident. Possible scenarios have been analyzed as well as reactivity effects involving the water presence in internal core cavities. A preliminary coupled model has been developed to describe accident transients in the reactor and TFE. The model is based on assumptions that result in overestimating possible consequences. The numerical simulations results point at the TOPAZ-II reactor capability to quench effectively possible power bursts and predict stable periodic oscillations as a final system state, wherein steaming and then refilling up some internal core cavities occurs. That may be considered to be demonstration of the TOPAZ-II reactor self-control capability if its criticality involves water immersion event.

  19. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies

    NASA Astrophysics Data System (ADS)

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M.; Keten, Sinan

    2016-03-01

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale Lsc governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length Lpc is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale LTc corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters.Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale

  20. Analysis of a boron-carbide-drum-controlled critical reactor experiment

    NASA Technical Reports Server (NTRS)

    Mayo, W. T.

    1972-01-01

    In order to validate methods and cross sections used in the neutronic design of compact fast-spectrum reactors for generating electric power in space, an analysis of a boron-carbide-drum-controlled critical reactor was made. For this reactor the transport analysis gave generally satisfactory results. The calculated multiplication factor for the most detailed calculation was only 0.7-percent Delta k too high. Calculated reactivity worth of the control drums was $11.61 compared to measurements of $11.58 by the inverse kinetics methods and $11.98 by the inverse counting method. Calculated radial and axial power distributions were in good agreement with experiment.

  1. Testing universality in critical exponents: The case of rainfall

    NASA Astrophysics Data System (ADS)

    Deluca, Anna; Puig, Pedro; Corral, Álvaro

    2016-04-01

    One of the key clues to consider rainfall as a self-organized critical phenomenon is the existence of power-law distributions for rain-event sizes. We have studied the problem of universality in the exponents of these distributions by means of a suitable statistic whose distribution is inferred by several variations of a permutational test. In contrast to more common approaches, our procedure does not suffer from the difficulties of multiple testing and does not require the precise knowledge of the uncertainties associated to the power-law exponents. When applied to seven sites monitored by the Atmospheric Radiation Measurement Program the tests lead to the rejection of the universality hypothesis, despite the fact that the exponents are rather close to each other. We discuss the reasons of the rejection.

  2. Human factors and safety issues associated with actinide retrieval from spent light water reactor fuel assemblies

    SciTech Connect

    Spelt, P.F.

    1992-01-01

    A major problem in environmental restoration and waste management is the disposition of used fuel assemblies from the many light water reactors in the United States, which present a radiation hazard to those whose job is to dispose of them, with a similar threat to the general environment associated with long-term storage in fuel repositories around the country. Actinides resident in the fuel pins as a result of their use in reactor cores constitute a significant component of this hazard. Recently, the Department of Energy has initiated an Actinide Recycle Program to study the feasibility of using pyrochemical (molten salt) processes to recover actinides from the spent fuel assemblies of commercial reactors. This project concerns the application of robotics technology to the operation and maintenance functions of a plant whose objective is to recover actinides from spent fuel assemblies, and to dispose of the resulting hardware and chemical components from this process. Such a procedure involves a number of safety and human factors issues. The purpose of the project is to explore the use of robotics and artificial intelligence to facilitate accomplishment of the program goals while maintaining the safety of the humans doing the work and the integrity of the environment. This project will result in a graphic simulation on a Silicon Graphics workstation as a proof of principle demonstration of the feasibility of using robotics along with an intelligent operator interface. A major component of the operator-system interface is a hybrid artificial intelligence system developed at Oak Ridge National Laboratory, which combines artificial neural networks and an expert system into a hybrid, self-improving computer-based system interface. 10 refs.

  3. Human factors and safety issues associated with actinide retrieval from spent light water reactor fuel assemblies

    SciTech Connect

    Spelt, P.F.

    1992-08-01

    A major problem in environmental restoration and waste management is the disposition of used fuel assemblies from the many light water reactors in the United States, which present a radiation hazard to those whose job is to dispose of them, with a similar threat to the general environment associated with long-term storage in fuel repositories around the country. Actinides resident in the fuel pins as a result of their use in reactor cores constitute a significant component of this hazard. Recently, the Department of Energy has initiated an Actinide Recycle Program to study the feasibility of using pyrochemical (molten salt) processes to recover actinides from the spent fuel assemblies of commercial reactors. This project concerns the application of robotics technology to the operation and maintenance functions of a plant whose objective is to recover actinides from spent fuel assemblies, and to dispose of the resulting hardware and chemical components from this process. Such a procedure involves a number of safety and human factors issues. The purpose of the project is to explore the use of robotics and artificial intelligence to facilitate accomplishment of the program goals while maintaining the safety of the humans doing the work and the integrity of the environment. This project will result in a graphic simulation on a Silicon Graphics workstation as a proof of principle demonstration of the feasibility of using robotics along with an intelligent operator interface. A major component of the operator-system interface is a hybrid artificial intelligence system developed at Oak Ridge National Laboratory, which combines artificial neural networks and an expert system into a hybrid, self-improving computer-based system interface. 10 refs.

  4. Criticality and universality in a generalized earthquake model

    SciTech Connect

    Boulter, C.J.; Miller, G.

    2005-01-01

    We propose that an appropriate prototype for modeling self-organized criticality in dissipative systems is a generalized version of the two-variable cellular automata model introduced by Hergarten and Neugebauer [Phys. Rev. E 61, 2382 (2000)]. We show that the model predicts exponents for the event size distribution which are consistent with physically observed results for dissipative phenomena such as earthquakes. In addition we provide evidence that the model is critical based on both scaling analyses and direct observation of the distribution and behavior of the two variables in the interior of the lattice. We further argue that for reasonably large lattices the results are universal for all dissipative choices of the model parameters.

  5. Universal quantum criticality in Hubbard models with massless Dirac dispersion

    NASA Astrophysics Data System (ADS)

    Otsuka, Yuichi; Yunoki, Seiji; Sorella, Sandro

    We investigate the metal-insulator transition of two-dimensional interacting electrons with massless Dirac-like dispersion, describe by the Hubbard models on two geometrically different lattices: honeycomb and π-flux square lattices. By performing large-scale quantum Monte Carlo simulations followed by careful finite-size scaling analyses, we find that the transition from semi-metallic to antiferromagnetic insulating phases is continuous and evaluate the critical exponents with a high degree of accuracy for the corresponding universality class, which is described in the continuous limit by the Gross-Neveu model. We furthermore discuss the fate of the quasiparticle weight and the Fermi velocity across this transition.

  6. Conversion and standardization of US university reactor fuels using LEU, status 1989

    SciTech Connect

    Brown, K.R.; Matos, J.E.; Argonne National Lab., IL )

    1989-01-01

    In 1986, the US Department of Energy initiated a program to change the fuel used in most of the US university research reactors using HEU (93%) to LEU({lt}20{percent}) in order to minimize the risk of theft or diversion of this weapons-useable material. An important consideration in the LEU conversion planning process has been the desire to standardize the fuels that are used and to enhance the performance and utilization of the reactors. This paper describes the current status of this conversion process and the plans and schedules to complete an orderly transition from HEU to LEU fuel in most of these reactors. To date, three university reactors have been converted to LEU fuel, completed safety documentation for three reactors is being evaluated by the USNRC, and work on the safety documentation for six reactors is in progress. 13 refs., 9 tabs.

  7. Final report. U.S. Department of Energy University Reactor Sharing Program

    SciTech Connect

    Bernard, John A

    2003-01-21

    Activities supported at the MIT Nuclear Reactor Laboratory under the U.S. DOE University Reactor Sharing Program are reported for Grant DE FG02-95NE38121 (September 16, 1995 through May 31, 2002). These activities fell under four subcategories: support for research at thesis and post-doctoral levels, support for college-level laboratory exercises, support for reactor tours/lectures on nuclear energy, and support for science fair participants.

  8. Beyond conservatism and the boundaries of a medical discipline: a short history of the department of neurosurgery at kyoto university graduate school of medicine.

    PubMed

    Hashimoto, Nobuo; Handa, Hajime; Kikuchi, Haruhiko

    2002-10-01

    CONSTANT CHANGE AND the occasional fusion of two different entities can result in the creation of masterpieces, not only in art but also in neurosurgery. Chisato Araki is one of the pioneers of neurosurgery in Japan; his 2-year sojourn in the United States and Europe provided him with an extraordinary amount of experience. He traveled throughout the world at a time when it took 30 days to journey from Yokohama to New York, and he visited with most of the leading contemporary neurosurgeons and observed their operations, never abandoning his highly honed critical insights. Driven by passion and a deep sense of duty to pass on his knowledge and perspective, he became a beacon of hope and encouragement for young physicians working in a country devastated by war. His successor, Hajime Handa, established neurosurgery as one of the branches of neuroscience and fostered the collaborations and exchanges among different disciplines that have become a tradition and hallmark of our Department of Neurosurgery. Through anecdotes and glimpses of the evolution of neurosurgery at our institution, we offer insights into the unique nature of Japanese neurosurgery that may illuminate the path toward the resolution of some of the recent and enduring problems encountered in our specialty.

  9. Experimental and simulated dosimetry of the university of Utah TRIGA reactor

    NASA Astrophysics Data System (ADS)

    Marble, Benjamin James

    Simulated neutron and gamma transport enable the gamma dose to be estimated at the surface of the University of Utah TRIGA Reactor UUTR pool. These results are benchmarked against experimental results for model verification. This model is useful for future licensing and possible reactor power upgrades. MCNP5 was utilized for the UUTR simulation and comparison with thermoluminescent detectors TLDs.

  10. As Universities Close Their Reactors, Energy Dept. Considers a Policy Shift.

    ERIC Educational Resources Information Center

    Southwick, Ron

    2001-01-01

    Discusses how, as many universities shut down their nuclear reactors used for research and training, the Energy Department considers moving its support to regional facilities, a change that might lead to more shutdowns. (EV)

  11. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies.

    PubMed

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M; Keten, Sinan

    2016-03-28

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale L(C)(S) governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length L(C)(P) is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale L(C)(T) corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters. PMID:26935048

  12. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies.

    PubMed

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M; Keten, Sinan

    2016-03-28

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale L(C)(S) governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length L(C)(P) is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale L(C)(T) corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters.

  13. Mixed enrichment core design for the NC State University PULSTAR Reactor

    SciTech Connect

    Mayo, C.W.; Verghese, K.; Huo, Y.G.

    1997-12-01

    The North Carolina State University PULSTAR Reactor license was renewed for an additional 20 years of operation on April 30, 1997. The relicensing period added additional years to the facility operating time through the end of the second license period, increasing the excess reactivity needs as projected in 1988. In 1995, the Nuclear Reactor Program developed a strategic plan that addressed the future maintenance, development, and utilization of the facility. Goals resulting from this plan included increased academic utilization of the facility in accordance with its role as a university research facility, and increased industrial service use in accordance with the mission of a land grant university. The strategic plan was accepted, and it is the intent of the College of Engineering to operate the PULSTAR Reactor as a going concern through at least the end of the current license period. In order to reach the next relicensing review without prejudice due to low excess reactivity, it is desired to maintain sufficient excess reactivity so that, if relicensed again, the facility could continue to operate without affecting users until new fuel assistance was provided. During the NC State University license renewal, the operation of the PULSTAR Reactor at the State University of New York at Buffalo (SUNY Buffalo) was terminated. At that time, the SUNY Buffalo facility had about 240 unused PULSTAR Reactor fuel pins with 6% enrichment. The objective of the work reported here was to develop a mixed enrichment core design for the NC State University PULSTAR reactor which would: (1) demonstrate that 6% enriched SUNY buffalo fuel could be used in the NC State University PULSTAR Reactor within the existing technical specification safety limits for core physics parameters; (2) show that use of this fuel could permit operating the NC State University PULSTAR Reactor to 2017 with increased utilization; and (3) assure that the decision whether or not to relicense the facility would

  14. Two distinct domains of protein 4.1 critical for assembly of functional nuclei in vitro.

    PubMed

    Krauss, Sharon Wald; Heald, Rebecca; Lee, Gloria; Nunomura, Wataru; Gimm, J Aura; Mohandas, Narla; Chasis, Joel Anne

    2002-11-15

    Protein 4.1R, a multifunctional structural protein, acts as an adaptor in mature red cell membrane skeletons linking spectrin-actin complexes to plasma membrane-associated proteins. In nucleated cells protein 4.1 is not associated exclusively with plasma membrane but is also detected at several important subcellular locations crucial for cell division. To identify 4.1 domains having critical functions in nuclear assembly, 4.1 domain peptides were added to Xenopus egg extract nuclear reconstitution reactions. Morphologically disorganized, replication deficient nuclei assembled when spectrin-actin-binding domain or NuMA-binding C-terminal domain peptides were present. However, control variant spectrin-actin-binding domain peptides incapable of binding actin or mutant C-terminal domain peptides with reduced NuMA binding had no deleterious effects on nuclear reconstitution. To test whether 4.1 is required for proper nuclear assembly, 4.1 isoforms were depleted with spectrin-actin binding or C-terminal domain-specific antibodies. Nuclei assembled in the depleted extracts were deranged. However, nuclear assembly could be rescued by the addition of recombinant 4.1R. Our data establish that protein 4.1 is essential for nuclear assembly and identify two distinct 4.1 domains, initially characterized in cytoskeletal interactions, that have crucial and versatile functions in nuclear assembly.

  15. Guidelines for preparing criticality safety evaluations at Department of Energy non-reactor nuclear facilities

    SciTech Connect

    1998-09-01

    This Department of Energy (DOE) is approved for use by all components of DOE. It contains guidelines that should be followed when preparing Criticality Safety Evaluations that will be used to demonstrate the safety of operations performed at DOE Non-Reactor Nuclear Facilities. Adherence with these guidelines will provide consistency and uniformity in Criticality Safety Evaluations (CSEs) across the complex and will document compliance with DOE Order 5480.24 requirements as they pertain to CSEs.

  16. The reactor facility that was built at Columbia University but never used.

    PubMed

    Hamawy, George

    2002-05-01

    A large and heavy experimental plasma vessel is located on the second floor of the Engineering Building at Columbia University. It sits atop the concrete shell of the old nuclear reactor facility. The reactor facility was built many years ago but no nuclear fuel was ever loaded into it. It was designed to contain a 250 kW reactor core. However, due to certain circumstances, it was never fueled or operated. This paper describes the events leading to the decision to not put the reactor into operation.

  17. Final report for U.S. Department of Energy Grant DE-FG02-95NE38118-5 University Reactor Sharing Program [Purdue University

    SciTech Connect

    Bean, R.S.

    2001-06-01

    Under the Reactor Sharing Program, a total of 350 high school students participated in the neutron activation experiment and 484 high school and university students and members of the general public participated in reactor tours.

  18. Analysis and evaluation of ZPPR (Zero Power Physics Reactor) critical experiments for a 100 kilowatt-electric space reactor

    SciTech Connect

    McFarlane, H.F.; Collins, P.J.; Carpenter, S.G.; Olsen, D.N.; Smith, D.M.; Schaefer, R.W. ); Doncals, R.A.; Andre, S.V.; Porter, C.A. ); Cowan, C.L; Stewart, S.L.; Protsik, R. . Astro Space Div.)

    1990-01-01

    ZPPR critical experiments were used for physics testing the reactor design of the SP-100, a 100-kW thermoelectric LMR that is being developed to provide electrical power for space applications. These tests validated all key physics characteristics of the design, including the ultimate safety in the event of a launch or re-entry accident. Both the experiments and the analysis required the use of techniques not previously applied to fast reactor designs. A few significant discrepancies between the experimental and calculated results leave opportunities for further optimization. An initial investigation has been made into application of the ZPPR-20 results, along with those of other relevant integral data, to the SP-100 design. 13 refs., 5 figs., 7 tabs.

  19. Development of reactivity feedback effect measurement techniques under sub-critical condition in fast reactors

    SciTech Connect

    Kitano, A.; Nishi, H.; Suzuki, T.; Okajima, S.; Kanemoto, S.

    2012-07-01

    The first-of-a-kind reactor has been licensed by a safety examination of the plant design based on the measured data in precedent mock-up experiments. The validity of the safety design can be confirmed without a mock-up experiment, if the reactor feed-back characteristics can be measured before operation, with the constructed reactor itself. The 'Synthesis Method', a systematic and sophisticated method of sub-criticality measurement, is proposed in this work to ensure the safety margin before operation. The 'Synthesis Method' is based on the modified source multiplication method (MSM) combined with the noise analysis method to measure the reference sub-criticality level for MSM. A numerical simulation for the control-rod reactivity worth and the isothermal feed-back reactivity was conducted for typical fast reactors of 100 MWe-size, 300 MWe-size, 750 MWe-size, and 1500 MWe-size to investigate the applicability of Synthesis Method. The number of neutron detectors and their positions necessary for the measurement were investigated for both methods of MSM and the noise analysis by a series of parametric survey calculations. As a result, it was suggested that a neutron detector located above the core center and three or more neutron detectors located above the radial blanket region enable the measurement of sub-criticality within 10% uncertainty from -$0.5 to -$2 and within 15% uncertainty for the deeper sub-criticality. (authors)

  20. Destruction of plutonium using non-uranium fuels in pressurized water reactor peripheral assemblies

    SciTech Connect

    Chodak, P. III

    1996-05-01

    This thesis examines and confirms the feasibility of using non-uranium fuel in a pressurized water reactor (PWR) radial blanket to eliminate plutonium of both weapons and civilian origin. In the equilibrium cycle, the periphery of the PWR is loaded with alternating fresh and once burned non-uranium fuel assemblies, with the interior of the core comprised of conventional three batch UO{sub 2} assemblies. Plutonium throughput is such that there is no net plutonium production: production in the interior is offset by destruction in the periphery. Using this approach a 50 MT WGPu inventory could be eliminated in approximately 400 reactor years of operation. Assuming all other existing constraints were removed, the 72 operating US PWRs could disposition 50 MT of WGPu in 5.6 years. Use of a low fissile loading plutonium-erbium inert-oxide-matrix composition in the peripheral assemblies essentially destroys 100% of the {sup 239}Pu and {ge}90% {sub total}Pu over two 18 month fuel cycles. Core radial power peaking, reactivity vs EFPD profiles and core average reactivity coefficients were found to be comparable to standard PWR values. Hence, minimal impact on reload licensing is anticipated. Examination of potential candidate fuel matrices based on the existing experience base and thermo-physical properties resulted in the recommendation of three inert fuel matrix compositions for further study: zirconia, alumina and TRISO particle fuels. Objective metrics for quantifying the inherent proliferation resistance of plutonium host waste and fuel forms are proposed and were applied to compare the proposed spent WGPu non-uranium fuel to spent WGPu MOX fuels and WGPu borosilicate glass logs. The elimination disposition option spent non-uranium fuel product was found to present significantly greater barriers to proliferation than other plutonium disposal products.

  1. Multiple lead seal assembly for a liquid-metal-cooled fast-breeder nuclear reactor

    DOEpatents

    Hutter, Ernest; Pardini, John A.

    1977-03-15

    A reusable multiple lead seal assembly provides leak-free passage of stainless-steel-clad instrument leads through the cover on the primary tank of a liquid-metal-cooled fast-breeder nuclear reactor. The seal isolates radioactive argon cover gas and sodium vapor within the primary tank from the exterior atmosphere and permits reuse of the assembly and the stainless-steel-clad instrument leads. Leads are placed in flutes in a seal body, and a seal shell is then placed around the seal body. Circumferential channels in the body and inner surface of the shell are contiguous and together form a conduit which intersects each of the flutes, placing them in communication with a port through the wall of the seal shell. Liquid silicone rubber sealant is injected into the flutes through the port and conduit; the sealant fills the space in the flutes not occupied by the leads themselves and dries to a rubbery hardness. A nut, threaded onto a portion of the seal body not covered by the seal shell, jacks the body out of the shell and shears the sealant without damage to the body, shell, or leads. The leads may then be removed from the body. The sheared sealant is cleaned from the body, leads, and shell and the assembly may then be reused with the same or different leads.

  2. THERMAL ANALYSIS OF A PROPOSED TRANSPORT CASK FOR THREE ADVANCED BURNER REACTOR USED FUEL ASSEMBLIES

    SciTech Connect

    T. Bullard; M. Greiner; M. Dennis; S. Bays; R. Weiner

    2010-09-01

    Preliminary studies of used fuel generated in the US Department of Energy’s Advanced Fuel Cycle Initiative have indicated that current used fuel transport casks may be insufficient for the transportation of said fuel. This work considers transport of three 5-year-cooled oxide Advanced Burner Reactor used fuel assemblies with a burn-up of 160 MWD/kg. A transport cask designed to carry these assemblies is proposed. This design employs a 7-cm-thick lead gamma shield and a 20-cm-thick NS-4-FR composite neutron shield. The temperature profile within the cask, from its center to its exterior surface, is determined by two dimensional computational fluid dynamics simulations of conduction, convection, and radiation within the cask. Simulations are performed for a cask with a smooth external surface and various neutron shield thicknesses. Separate simulations are performed for a cask with a corrugated external surface and a neutron shield thickness that satisfies shielding constraints. Resulting temperature profiles indicate that a three-assembly cask with a smooth external surface will meet fuel cladding temperature requirements but will cause outer surface temperatures to exceed the regulatory limit. A cask with a corrugated external surface will not exceed the limits for both the fuel cladding and outer surface temperatures.

  3. Comments on the critical issues for a high-density gas-embedded Z-pinch CTR reactor concept

    NASA Astrophysics Data System (ADS)

    Ekdahl, C. A.

    1981-02-01

    The issues considered critical for the realization of a CTR reactor are discussed for the high density gas embedded z pinch concept. A simple model of the pinch reactor is presented that gives estimates for Q in substantial agreement with elaborate computer studies. An attempt is made to identify such critical points that are amenable to exploratory experiments. There appears to be no fatal flaw in the issues covered that would preclude a viable reactor based on this concept.

  4. Development of numerical simulation system for thermal-hydraulic analysis in fuel assembly of sodium-cooled fast reactor

    NASA Astrophysics Data System (ADS)

    Ohshima, Hiroyuki; Uwaba, Tomoyuki; Hashimoto, Akihiko; Imai, Yasutomo; Ito, Masahiro

    2015-12-01

    A numerical simulation system, which consists of a deformation analysis program and three kinds of thermal-hydraulics analysis programs, is being developed in Japan Atomic Energy Agency in order to offer methodologies to clarify thermal-hydraulic phenomena in fuel assemblies of sodium-cooled fast reactors under various operating conditions. This paper gives the outline of the system and its applications to fuel assembly analyses as a validation study.

  5. Development of numerical simulation system for thermal-hydraulic analysis in fuel assembly of sodium-cooled fast reactor

    SciTech Connect

    Ohshima, Hiroyuki; Uwaba, Tomoyuki; Hashimoto, Akihiko; Imai, Yasutomo; Ito, Masahiro

    2015-12-31

    A numerical simulation system, which consists of a deformation analysis program and three kinds of thermal-hydraulics analysis programs, is being developed in Japan Atomic Energy Agency in order to offer methodologies to clarify thermal-hydraulic phenomena in fuel assemblies of sodium-cooled fast reactors under various operating conditions. This paper gives the outline of the system and its applications to fuel assembly analyses as a validation study.

  6. Shielding calculation and criticality safety analysis of spent fuel transportation cask in research reactors.

    PubMed

    Mohammadi, A; Hassanzadeh, M; Gharib, M

    2016-02-01

    In this study, shielding calculation and criticality safety analysis were carried out for general material testing reactor (MTR) research reactors interim storage and relevant transportation cask. During these processes, three major terms were considered: source term, shielding, and criticality calculations. The Monte Carlo transport code MCNP5 was used for shielding calculation and criticality safety analysis and ORIGEN2.1 code for source term calculation. According to the results obtained, a cylindrical cask with body, top, and bottom thicknesses of 18, 13, and 13 cm, respectively, was accepted as the dual-purpose cask. Furthermore, it is shown that the total dose rates are below the normal transport criteria that meet the standards specified. PMID:26720262

  7. Shielding calculation and criticality safety analysis of spent fuel transportation cask in research reactors.

    PubMed

    Mohammadi, A; Hassanzadeh, M; Gharib, M

    2016-02-01

    In this study, shielding calculation and criticality safety analysis were carried out for general material testing reactor (MTR) research reactors interim storage and relevant transportation cask. During these processes, three major terms were considered: source term, shielding, and criticality calculations. The Monte Carlo transport code MCNP5 was used for shielding calculation and criticality safety analysis and ORIGEN2.1 code for source term calculation. According to the results obtained, a cylindrical cask with body, top, and bottom thicknesses of 18, 13, and 13 cm, respectively, was accepted as the dual-purpose cask. Furthermore, it is shown that the total dose rates are below the normal transport criteria that meet the standards specified.

  8. GROWTH OF THE INTERNATIONAL CRITICALITY SAFETY AND REACTOR PHYSICS EXPERIMENT EVALUATION PROJECTS

    SciTech Connect

    J. Blair Briggs; John D. Bess; Jim Gulliford

    2011-09-01

    Since the International Conference on Nuclear Criticality Safety (ICNC) 2007, the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Experiment Evaluation Project (IRPhEP) have continued to expand their efforts and broaden their scope. Eighteen countries participated on the ICSBEP in 2007. Now, there are 20, with recent contributions from Sweden and Argentina. The IRPhEP has also expanded from eight contributing countries in 2007 to 16 in 2011. Since ICNC 2007, the contents of the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments1' have increased from 442 evaluations (38000 pages), containing benchmark specifications for 3955 critical or subcritical configurations to 516 evaluations (nearly 55000 pages), containing benchmark specifications for 4405 critical or subcritical configurations in the 2010 Edition of the ICSBEP Handbook. The contents of the Handbook have also increased from 21 to 24 criticality-alarm-placement/shielding configurations with multiple dose points for each, and from 20 to 200 configurations categorized as fundamental physics measurements relevant to criticality safety applications. Approximately 25 new evaluations and 150 additional configurations are expected to be added to the 2011 edition of the Handbook. Since ICNC 2007, the contents of the 'International Handbook of Evaluated Reactor Physics Benchmark Experiments2' have increased from 16 different experimental series that were performed at 12 different reactor facilities to 53 experimental series that were performed at 30 different reactor facilities in the 2011 edition of the Handbook. Considerable effort has also been made to improve the functionality of the searchable database, DICE (Database for the International Criticality Benchmark Evaluation Project) and verify the accuracy of the data contained therein. DICE will be discussed in separate papers at ICNC 2011. The status of the ICSBEP and the IRPh

  9. Nuclear reactors built, being built, or planned, 1991

    SciTech Connect

    Simpson, B.

    1992-07-01

    This document contains unclassified information about facilities built, being built, or planned in the United States for domestic use or export as of December 31, 1991. The book is divided into three major sections: Section 1 consists of a reactor locator map and reactor tables; Section 2 includes nuclear reactors that are operating, being built, or planned; and Section 3 includes reactors that have been shut down permanently or dismantled. Sections 2 and 3 contain the following classification of reactors: Civilian, Production, Military, Export, and Critical Assembly. Export reactor refers to a reactor for which the principal nuclear contractor is an American company -- working either independently or in cooperation with a foreign company (Part 4, in each section). Critical assembly refers to an assembly of fuel and assembly of fuel and moderator that requires an external source of neutrons to initiate and maintain fission. A critical assembly is used for experimental measurements (Part 5).

  10. Off-line life tests of Topaz-2 system reactor unit assembly units

    NASA Astrophysics Data System (ADS)

    Oglobin, Boris G.; Proshin, Yuriy F.; Shalaev, Anatoliy I.

    1995-01-01

    Experimental trials of the Topaz-2 nuclear power system (NPS) have been carried out according to the Integrated Experimental Trials Program (IETP). This program involved ground off-line tests of the reactor unit assembly units and their integrated tests as components of the prototype systems. Scopes of tests performed and major results of integrated and off-line tests were presented in the paper by Vladimir P. Nikitin et al. (1993). This paper considers major results of off-line life tests of the cesium unit, automatic control drive, ionization chamber suspension and dry friction pairs. These tests have been carried out in the Central Design Bureau for Machine Building (CDBMB) between 1982 and April, 1994.

  11. Control rod reactivity measurement by rod-drop method at a fast critical assembly

    SciTech Connect

    Song, L.; Yin, Y.; Lian, X.; Zheng, C.

    2012-07-01

    Rod-drop experiments were carried out to estimate the reactivity of the control rod of a fast critical assembly operated by CAEP. Two power monitor systems were used to obtain the power level and integration method was used to process the data. Three experiments were performed. The experimental results of the reactivity from the two power monitor systems were consistent and showed a reasonable range of reactivity compared to results from positive period method. (authors)

  12. 76 FR 11291 - University of New Mexico AGN-201M Reactor Notice of Issuance of Renewed Facility Operating...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-01

    ... COMMISSION University of New Mexico AGN-201M Reactor Notice of Issuance of Renewed Facility Operating License... No. R-102, held by the University of New Mexico (the licensee), which authorizes continued operation of the University of New Mexico AGN-201M Reactor (UNMR), located in Albuquerque, Bernalillo...

  13. A critical assembly designed to measure neutronic benchmarks in support of the Space Nuclear Thermal Propulsion program

    NASA Astrophysics Data System (ADS)

    Parma, E. J.; Ball, R. M.; Hoovler, G. S.; Selcow, E. C.; Cerbone, R. J.

    1992-10-01

    A reactor designed to perform criticality experiments in support of the Space Nuclear Thermal Propulsion program is currently in operation at the Sandia National Laboratories' reactor facility. The reactor is a small, water-moderated system that uses highly enriched uranium particle fuel in a 19-element configuration. Its purpose is to obtain neutronic measurements under a variety of experimental conditions that are subsequently used to benchmark reactor-design computer codes. Brookhaven National Laboratory, Babcock & Wilcox, and Sandia National Laboratories participated in determining the reactor's performance requirements, design, follow on experimentation, and in obtaining the licensing approvals. Brookhaven National Laboratory is primarily responsible for the analytical support, Babcock & Wilcox the hardware design, and Sandia National Laboratories the operational safety. All of the team members participate in determining the experimentation requirements, performance, and data reduction. Initial criticality was achieved in October 1989. An over-all description of the reactor is presented along with key design features and safety-related aspects.

  14. CRITICAL CONFIGURATION FOR BERYLLIUM REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH AND 7-TUBE CLUSTERS)

    SciTech Connect

    Margaret A. Marshall

    2012-05-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s Critical Experiments Facility in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950’s efforts were made to study “power plants for the production of electrical power in space vehicles”. The MPRE program was a part of those efforts and studied the feasibility of a stainless steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of 253 unmoderated stainless steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.” The first two experiments in the series were evaluated in HEU-COMP-FAST-001 (SCCA-FUND-EXP-001) and HEU-COMP-FAST-002 (SCCA-FUND-EXP-002). The first experiment had the 253 fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank (References 1 and 2). The second experiment in the series, performed in early 1963, had the 253 fuel tubes at a 1.506-cm triangular lattice in a 25.96 cm OD core tank and graphite reflectors on all sides. The third set of experiments in the series, performed in mid-1963, which is studied in this evaluation, used beryllium reflectors. The beryllium reflected system was the preferred reactor configuration for this application because of the small thickness of the reflector. The two core configurations had the 253 fuel tubes

  15. Nuclear reactor fuel assembly duct-tube-to-handling-socket attachment system

    DOEpatents

    Christiansen, David W.; Smith, Bob G.

    1982-01-01

    A reusable system for removably attaching the upper end 10of a nuclear reactor duct tube to the lower end 30 of a nuclear reactor fuel assembly handling socket. A transition ring 20, fixed to the duct tube's upper end 10, has an interior-threaded section 22 with a first locking hole segment 24. An adaptor ring 40, fixed to the handling socket's lower end 30 has an outside-threaded section 42 with a second locking hole segment 44. The inside 22 and outside 42 threaded sections match and can be joined so that the first 24 and second 44 locking hole segments can be aligned to form a locking hole. A locking ring 50, with a locking pin 52, slides over the adaptor ring 40 so that the locking pin 52 fits in the locking hole. A swage lock 60 or a cantilever finger lock 70 is formed from the locking cup collar 26 to fit in a matching groove 54 or 56 in the locking ring 50 to prevent the locking ring's locking pin 52 from backing out of the locking hole.

  16. Graphite and Beryllium Reflector Critical Assemblies of UO2 (Benchmark Experiments 2 and 3)

    SciTech Connect

    Margaret A. Marshall; John D. Bess

    2012-11-01

    INTRODUCTION A series of experiments was carried out in 1962-65 at the Oak Ridge National Laboratory Critical Experiments Facility (ORCEF) for use in space reactor research programs. A core containing 93.2 wt% enriched UO2 fuel rods was used in these experiments. The first part of the experimental series consisted of 252 tightly-packed fuel rods (1.27-cm triangular pitch) with graphite reflectors [1], the second part used 252 graphite-reflected fuel rods organized in a 1.506-cm triangular-pitch array [2], and the final part of the experimental series consisted of 253 beryllium-reflected fuel rods in a 1.506-cm-triangular-pitch configuration and in a 7-tube-cluster configuration [3]. Fission rate distribution and cadmium ratio measurements were taken for all three parts of the experimental series. Reactivity coefficient measurements were taken for various materials placed in the beryllium reflected core. All three experiments in the series have been evaluated for inclusion in the International Reactor Physics Experiment Evaluation Project (IRPhEP) [4] and the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbooks, [5]. The evaluation of the first experiment in the series was discussed at the 2011 ANS Winter meeting [6]. The evaluations of the second and third experiments are discussed below. These experiments are of interest as benchmarks because they support the validation of compact reactor designs with similar characteristics to the design parameters for a space nuclear fission surface power systems [7].

  17. The Problematic Potential of Universities to Advance Critical Urban Politics

    ERIC Educational Resources Information Center

    Pendras, Mark; Dierwechter, Yonn

    2012-01-01

    Recent research has explored the connections between universities and the cities/places in which they are located. Increasingly, emphasis is placed on the economic role of the university and on universities as urban stabilizers that can mobilize investment and advance development goals. This article explores a different charge for the university:…

  18. Faculty Perceptions of Critical Thinking at a Health Sciences University

    ERIC Educational Resources Information Center

    Rowles, Joie; Morgan, Christine; Burns, Shari; Merchant, Christine

    2013-01-01

    The fostering of critical thinking skills has become an expectation of faculty, especially those teaching in the health sciences. The manner in which critical thinking is defined by faculty impacts how they will address the challenge to promote critical thinking among their students. This study reports the perceptions of critical thinking held by…

  19. A Re-Analysis of Historical Los Alamos Critical Assembly Reaction Rate Measurements

    NASA Astrophysics Data System (ADS)

    Kahler, A. C.; MacInnes, M.; Chadwick, M. B.

    2016-02-01

    Starting in the 1950s and continuing into the early 1970s, a number of foil irradiations and fission chamber measurements were made in a variety of Fast critical assemblies at Los Alamos National Laboratory. These include (i) Godiva, a bare HEU spherical assembly; (ii) Flattop-25, a spherical assembly consisting of an HEU core and a natural uranium reflector; (iii) Jezebel, a bare 239Pu assembly; and (iv) Flattop-Pu, a spherical assembly consisting of a 239Pu core and a natural uranium reflector. In most instances the irradiations occur at or near the center of the assembly, but in selected instances data were obtained for a radial traverse extending into the Flattop reflector region. Measurements were made for a number of threshold reactions, including 45Sc(n,2n)44mSc, 51V(n,α)48Sc, 75As(n,2n)74As, 89Y(n,2n)88Y, 90Zr(n,2n)89Zr, 103Rh(n,2n)102gRh, 107Ag(n,2n)106mAg, 169Tm(n,2n)168Tm, 175Lu(n,2n)174Lu, 191Ir(n,2n)190Ir, 197Au(n,2n)196Au, 203Tl(n,2n)202Tl, 204Pb(n,2n)203Pb and 238U(n,2n)237U. Fission ratio data for 238U(n,f)/235U(n,f) and 239Pu(n,f)/235U(n,f) were also obtained. We report C/E values from MCNP6 calculations using ENDF/B-VII.1 and IRDFF-v1.03 cross section data.

  20. Scale-4 analysis of pressurized water reactor critical configurations: Volume 5, North Anna Unit 1 Cycle 5

    SciTech Connect

    Bowman, S.M.; Suto, T. |

    1996-10-01

    ANSI/ANS 8.1 requires that calculational methods for away-from- reactor (AFR) criticality safety analyses be validated against experiment. This report summarizes part of the ongoing effort to benchmark AFR criticality analysis methods using selected critical configurations from commercial PWRs. Codes and data in the SCALE-4 code system were used. This volume documents the SCALE system analysis of one reactor critical configuration for North Anna Unit 1 Cycle 5. The KENO V.a criticality calculations for the North Anna 1 Cycle 5 beginning-of-cycle model yielded a value for k{sub eff} of 1. 0040{+-}0.0005.

  1. Critical assembly: A technical history of Los Alamos during the Oppenheimer years, 1943--1945

    SciTech Connect

    Hoddeson, L.; Henriksen, P.W.; Meade, R.A.; Westfall, C.

    1993-11-01

    This volume treats the technical research that led to the first atomic bombs. The authors explore how the ``critical assembly`` of scientists, engineers, and military Personnel at Los Alamos collaborated during World War II, blending their traditions to create a new approach to large-scale research. The research was characterized by strong mission orientation, multidisciplinary teamwork, expansion of the scientists` traditional methodology with engineering techniques, and a trail-and-error methodology responding to wartime deadlines. The book opens with an introduction laying out major themes. After a synopsis of the prehistory of the bomb project, from the discovery of nuclear fission to the start of the Manhattan Engineer District, and an overview of the early materials program, the book examines the establishment of the Los Alamos Laboratory, the implosion and gun assembly programs, nuclear physics research, chemistry and metallurgy, explosives, uranium and plutonium development, confirmation of spontaneous fission in pile-produced plutonium, the thermonuclear bomb, critical assemblies, the Trinity test, and delivery of the combat weapons.

  2. Modular Pebble Bed Reactor Project, University Research Consortium Annual Report

    SciTech Connect

    Petti, David Andrew

    2000-07-01

    This project is developing a fundamental conceptual design for a gas-cooled, modular, pebble bed reactor. Key technology areas associated with this design are being investigated which intend to address issues concerning fuel performance, safety, core neutronics and proliferation resistance, economics and waste disposal. Research has been initiated in the following areas: · Improved fuel particle performance · Reactor physics · Economics · Proliferation resistance · Power conversion system modeling · Safety analysis · Regulatory and licensing strategy Recent accomplishments include: · Developed four conceptual models for fuel particle failures that are currently being evaluated by a series of ABAQUS analyses. Analytical fits to the results are being performed over a range of important parameters using statistical/factorial tools. The fits will be used in a Monte Carlo fuel performance code, which is under development. · A fracture mechanics approach has been used to develop a failure probability model for the fuel particle, which has resulted in significant improvement over earlier models. · Investigation of fuel particle physio-chemical behavior has been initiated which includes the development of a fission gas release model, particle temperature distributions, internal particle pressure, migration of fission products, and chemical attack of fuel particle layers. · A balance of plant, steady-state thermal hydraulics model has been developed to represent all major components of a MPBR. Component models are being refined to accurately reflect transient performance. · A comparison between air and helium for use in the energy-conversion cycle of the MPBR has been completed and formed the basis of a master’s degree thesis. · Safety issues associated with air ingress are being evaluated. · Post shutdown, reactor heat removal characteristics are being evaluated by the Heating-7 code. · PEBBED, a fast deterministic neutronic code package suitable for

  3. Exploratory Learning through Critical Inquiry: Survey of Critical Inquiry Programs at Mid-Sized U.S. Universities

    ERIC Educational Resources Information Center

    Foote, Stephanie M.; Harrison, David S.; Ritchie, C. Michael; Dyer, Andrew

    2012-01-01

    Many alternatives exist for setting the delivery, content, direction, tone, and priorities for a Critical Inquiry/Thinking general education program. Review of our university's overall general education program indicated the need, and overwhelming faculty approval, for a program to improve critical thinking skills, to specifically include…

  4. CRITICAL CONFIGURATION AND PHYSICS MEASUREMENTS FOR GRAPHITE REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH)

    SciTech Connect

    Margaret A. Marshall

    2012-03-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s Critical Experiments Facility in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950’s efforts were made to study “power plants for the production of electrical power in space vehicles”. The MPRE program was a part of those efforts and studied the feasibility of a stainless steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of 253 unmoderated stainless steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.” The first experiment in the series was evaluated in HEU-COMP-FAST-001. It had the 253 fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank (References 1 and 2). The second experiment in the series, performed in early 1963, which is studied in this evaluation, had the 253 fuel tubes at a 1.506-cm triangular lattice in a 25.96 cm OD core tank and graphite reflectors on all sides. The experiment has been determined to represent an acceptable benchmark experiment. Information for this evaluation was compiled from published reports on all three parts of the experimental series (Reference 1-5) and the experimental logbook as

  5. [Climate change and Kyoto protocol].

    PubMed

    Ergasti, G; Pippia, V; Murzilli, G; De Luca D'Alessandro, E

    2009-01-01

    Due to industrial revolution and the heavy use of fossil fuels, the concentration of greenhouse gases in the atmosphere has increased dramatically during the last hundred years, and this has lead to an increase in mean global temperature. The environmental consequences of this are: the melting of the ice caps, an increase in mean sea-levels, catastrophic events such as floodings, hurricanes and earthquakes, changes to the animal and vegetable kingdoms, a growth in vectors and bacteria in water thus increasing the risk of infectious diseases and damage to agriculture. The toxic effects of the pollution on human health are both acute and chronic. The Kyoto Protocol is an important step in the campaign against climatic changes but it is not sufficient. A possible solution might be for the States which produce the most of pollution to adopt a better political stance for the environment and to use renewable resources for the production of energy.

  6. A critical assembly designed to measure neutronic benchmarks in support of the space nuclear thermal propulsion program

    NASA Astrophysics Data System (ADS)

    Parma, Edward J.; Ball, Russell M.; Hoovler, Gary S.; Selcow, Elizabeth C.; Cerbone, Ralph J.

    1993-01-01

    A reactor designed to perform criticality experiments in support of the Space Nuclear Thermal Propulsion program is currently in operation at the Sandia National Laboratories' reactor facility. The reactor is a small, water-moderated system that uses highly enriched uranium particle fuel in a 19-element configuration. Its purpose is to obtain neutronic measurements under a variety of experimental conditions that are subsequently used to benchmark rector-design computer codes. Brookhaven National Laboratory, Babcock & Wilcox, and Sandia National Laboratories participated in determining the reactor's performance requirements, design, follow-on experimentation, and in obtaining the licensing approvals. Brookhaven National Laboratory is primarily responsible for the analytical support, Babcock & Wilcox the hardware design, and Sandia National Laboratories the operational safety. All of the team members participate in determining the experimentation requirements, performance, and data reduction. Initial criticality was achieved in October 1989. An overall description of the reactor is presented along with key design features and safety-related aspects.

  7. Heidelberg-Kyoto partnership bridges life and materials sciences, strengthens bilateral ties.

    PubMed

    Iijima, Yutaka; Kornhauser, David H; Nakatsuji, Norio

    2012-06-01

    Coinciding with the 150(th) anniversary of German-Japanese friendship, Kyoto University and Heidelberg University, two universities replete with history and tradition strengthened their close ties at a joint meeting in Heidelberg, Germany, forming the core of a broad collaborative effort between the two countries. This forum article provides a background and overview of the collaborations.

  8. Modeling the effect in of criticality from changes in key parameters for small High Temperature Nuclear Reactor (U-BatteryTM) using MCNP4C

    NASA Astrophysics Data System (ADS)

    Pauzi, A. M.

    2013-06-01

    The neutron transport code, Monte Carlo N-Particle (MCNP) which was wellkown as the gold standard in predicting nuclear reaction was used to model the small nuclear reactor core called "U-batteryTM", which was develop by the University of Manchester and Delft Institute of Technology. The paper introduces on the concept of modeling the small reactor core, a high temperature reactor (HTR) type with small coated TRISO fuel particle in graphite matrix using the MCNPv4C software. The criticality of the core were calculated using the software and analysed by changing key parameters such coolant type, fuel type and enrichment levels, cladding materials, and control rod type. The criticality results from the simulation were validated using the SCALE 5.1 software by [1] M Ding and J L Kloosterman, 2010. The data produced from these analyses would be used as part of the process of proposing initial core layout and a provisional list of materials for newly design reactor core. In the future, the criticality study would be continued with different core configurations and geometries.

  9. Simulating the Effect on Criticality of Simultaneous Matrix Degradation and Assembly Collapse for the 21 PWR Waste Package

    SciTech Connect

    A.A. Alsaed

    1999-09-23

    The purpose of this calculation is to evaluate the effects of fission products loss on the reactivity of commercial pressurized water reactor (PWR) spent nuclear fuel (SNF) in 21 PWR waste packages (WPs) in the event of simultaneous fuel matrix degradation and assembly collapse.

  10. Criticality Safety Evaluation for the Advanced Test Reactor U-Mo Demonstration Elements

    SciTech Connect

    Leland M. Montierth

    2010-12-01

    The Reduced Enrichment Research Test Reactors (RERTR) fuel development program is developing a high uranium density fuel based on a (LEU) uranium-molybdenum alloy. Testing of prototypic RERTR fuel elements is necessary to demonstrate integrated fuel performance behavior and scale-up of fabrication techniques. Two RERTR-Full Size Demonstration fuel elements based on the ATR-Reduced YA elements (all but one plate fueled) are to be fabricated for testing in the Advanced Test Reactor (ATR). The two fuel elements will be irradiated in alternating cycles such that only one element is loaded in the reactor at a time. Existing criticality analyses have analyzed Standard (HEU) ATR elements (all plates fueled) from which controls have been derived. This criticality safety evaluation (CSE) documents analysis that determines the reactivity of the Demonstration fuel elements relative to HEU ATR elements and shows that the Demonstration elements are bound by the Standard HEU ATR elements and existing HEU ATR element controls are applicable to the Demonstration elements.

  11. N-Reactor (U-metal) Fuel Characteristics for Disposal Criticality Analysis

    SciTech Connect

    Taylor, Larry Lorin

    2000-05-01

    DOE-owned spent nuclear fuels encompass many fuel types. In an effort to facilitate criticality analysis for these various fuel types, they were categorized into nine characteristic fuel groups with emphasis on fuel matrix composition. Out of each fuel group, a representative fuel type was chosen for analysis as a bounding case within that fuel group. Generally, burnup data, fissile enrichments, and total fuel and fissile mass govern the selection of the representative or candidate fuel within that group. Additionally, the criticality analysis will also require data to support design of the canister internals, thermal, and radiation shielding. The purpose of this report is to consolidate and provide in a concise format, material and information/data needed to perform supporting analyses to qualify N-Reactor fuels for acceptance into the designated repository. The N Reactor fuels incorporate zirconium cladding and uranium metal with unique fabrication details in terms of physical size, and method of construction. The fuel construction and post-irradiation handling have created attendant issues relative to cladding failure in the underwater storage environment. These fuels were comprised of low-enriched metal (0.947 to 1.25 wt% 235U) that were originally intended to generate weapons-grade plutonium for national defense. Modifications in subsequent fuel design and changes in the mode of reactor operation in later years were focused more toward power production.

  12. Supplementary neutron-flux calculations for the ORNL Pool Critical Assembly Pressure Vessel Facility

    SciTech Connect

    Maudlin, P.J.; Maerker, R.E.

    1982-01-01

    A three-dimensional Monte Carlo calculation using the MORSE code was performed to validate a procedure previously adopted in the ORNL discrete ordinate analysis of measurements made in the ORNL Pool Critical Assembly Pressure Vessel Facility. The results of these flux calculations agree, within statistical undertainties of about 5%, with those obtained from a discrete ordinate analysis employing the same procedure. This study therefore concludes that the procedure for combining several one- and two-dimensional discrete ordinate calculations into a three-dimensional flux is sufficiently accurate that it does not account for the existing discrepancies observed between calculations and measurements in this facility.

  13. A Critical Appraisal of RAFT-Mediated Polymerization-Induced Self-Assembly

    PubMed Central

    2016-01-01

    Recently, polymerization-induced self-assembly (PISA) has become widely recognized as a robust and efficient route to produce block copolymer nanoparticles of controlled size, morphology, and surface chemistry. Several reviews of this field have been published since 2012, but a substantial number of new papers have been published in the last three years. In this Perspective, we provide a critical appraisal of the various advantages offered by this approach, while also pointing out some of its current drawbacks. Promising future research directions as well as remaining technical challenges and unresolved problems are briefly highlighted. PMID:27019522

  14. University Reactor Instrumentation grant program. Final report, September 7, 1990--August 31, 1995

    SciTech Connect

    Talnagi, J.W.

    1998-06-17

    The Ohio State University Nuclear Reactor Laboratory (OSU NRL) participated in the Department of Energy (DOE) grant program commonly denoted as the University Reactor Instrumentation (URI) program from the period September 1990 through August 1995, after which funding was terminated on a programmatic basis by DOE. This program provided funding support for acquisition of capital equipment targeted for facility upgrades and improvements, including modernizing reactor systems and instrumentation, improvements in research and instructional capabilities, and infrastructure enhancements. The staff of the OSU NRL submitted five grant applications during this period, all of which were funded either partially or in their entirety. This report will provide an overview of the activities carried out under these grants and assess their impact on the OSU NRL facilities.

  15. CO2 Reduction Assembly Prototype Using Microlith-Based Sabatier Reactor for Ground Demonstration

    NASA Technical Reports Server (NTRS)

    Junaedi, Christian; Hawley, Kyle; Walsh, Dennis; Roychoudhury, Subir; Abney, Morgan B.; Perry, Jay L.

    2014-01-01

    The utilization of CO2 to produce life support consumables, such as O2 and H2O, via the Sabatier reaction is an important aspect of NASA's cabin Atmosphere Revitalization System (ARS) and In-Situ Resource Utilization (ISRU) architectures for both low-earth orbit and long-term manned space missions. Carbon dioxide can be reacted with H2, obtained from the electrolysis of water, via Sabatier reaction to produce methane and H2O. Methane can be stored and utilized as propellant while H2O can be either stored or electrolyzed to produce oxygen and regain the hydrogen atoms. Depending on the application, O2 can be used to replenish the atmosphere in human-crewed missions or as an oxidant for robotic and return missions. Precision Combustion, Inc. (PCI), with support from NASA, has previously developed an efficient and compact Sabatier reactor based on its Microlith® catalytic technology and demonstrated the capability to achieve high CO2 conversion and CH4 selectivity (i.e., =90% of the thermodynamic equilibrium values) at high space velocities and low operating temperatures. This was made possible through the use of high-heat-transfer and high-surface-area Microlith catalytic substrates. Using this Sabatier reactor, PCI designed, developed, and demonstrated a stand-alone CO2 Reduction Assembly (CRA) test system for ground demonstration and performance validation. The Sabatier reactor was integrated with the necessary balance-of-plant components and controls system, allowing an automated, single "push-button" start-up and shutdown. Additionally, the versatility of the test system prototype was demonstrated by operating it under H2-rich (H2/CO2 of >4), stoichiometric (ratio of 4), and CO2-rich conditions (ratio of <4) without affecting its performance and meeting the equilibrium-predicted water recovery rates. In this paper, the development of the CRA test system for ground demonstration will be discussed. Additionally, the performance results from testing the system at

  16. 78 FR 5840 - Notice of License Termination for University of Illinois Advanced TRIGA Reactor, License No. R-115

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-28

    ... COMMISSION Notice of License Termination for University of Illinois Advanced TRIGA Reactor, License No. R-115... No. R-115, for the University of Illinois Advanced TRIGA Reactor (ATR). The NRC has terminated the..., Facility Operating License No. R-115 is terminated. The above referenced documents may be examined,...

  17. The development of a universal diagnostic probe system for Tokamak fusion test reactor

    NASA Technical Reports Server (NTRS)

    Mastronardi, R.; Cabral, R.; Manos, D.

    1982-01-01

    The Tokamak Fusion Test Reactor (TFTR), the largest such facility in the U.S., is discussed with respect to instrumentation in general and mechanisms in particular. The design philosophy and detailed implementation of a universal probe mechanism for TFTR is discussed.

  18. Removal plan for Shippingport pressurized water reactor core 2 blanket fuel assemblies form T plant to the canister storage building

    SciTech Connect

    Lata

    1996-09-26

    This document presents the current strategy and path forward for removal of the Shippingport Pressurized Water Reactor Core 2 blanket fuel assemblies from their existing storage configuration (wet storage within the T Plant canyon) and transport to the Canister Storage Building (designed and managed by the Spent Nuclear Fuel. Division). The removal plan identifies all processes, equipment, facility interfaces, and documentation (safety, permitting, procedures, etc.) required to facilitate the PWR Core 2 assembly removal (from T Plant), transport (to the Canister storage Building), and storage to the Canister Storage Building. The plan also provides schedules, associated milestones, and cost estimates for all handling activities.

  19. Analysis of Np-237 ENDF for the theortical interpretation of critical assembly experiments.

    SciTech Connect

    Mihaila, B.; Chadwick, M. B.; MacFarlane, R. E.; Kawano, T.

    2004-01-01

    We report on the present status of our effort toward an improved Np-237 evaluated nuclear data file (ENDF). The aim here is to bridge the gap between calculated and observed k-eff values, as measured at the Np-U critical assembly at LANL, TA-18. As such, we perform a critical analysis of the existing body of experimental data and recommended evaluations. We are targeting in principal the fission nu-bar and cross section in Np-237, as well as the inelastic scattering which is particularly important since Np-237 is a threshold fissioner. This analysis will be employed in a future sensitivity study of the calculated k-eff with respect to variations of the afore mentioned nuclear data.

  20. Bottom head to shell junction assembly for a boiling water nuclear reactor

    DOEpatents

    Fife, Alex Blair; Ballas, Gary J.

    1998-01-01

    A bottom head to shell junction assembly which, in one embodiment, includes an annular forging having an integrally formed pump deck and shroud support is described. In the one embodiment, the annular forging also includes a top, cylindrical shaped end configured to be welded to one end of the pressure vessel cylindrical shell and a bottom, conical shaped end configured to be welded to the disk shaped bottom head. Reactor internal pump nozzles also are integrally formed in the annular forging. The nozzles do not include any internal or external projections. Stubs are formed in each nozzle opening to facilitate welding a pump housing to the forging. Also, an upper portion of each nozzle opening is configured to receive a portion of a diffuser coupled to a pump shaft which extends through the nozzle opening. Diffuser openings are formed in the integral pump deck to provide additional support for the pump impellers. The diffuser opening is sized so that a pump impeller can extend at least partially therethrough. The pump impeller is connected to the pump shaft which extends through the nozzle opening.

  1. Innovative technologies on fuel assemblies cleaning for sodium fast reactors: First considerations on cleaning process

    SciTech Connect

    Simon, N.; Lorcet, H.; Beauchamp, F.; Guigues, E.; Lovera, P.; Fleche, J. L.; Lacroix, M.; Carra, O.; Prele, G.

    2012-07-01

    Within the framework of Sodium Fast Reactor development, innovative fuel assembly cleaning operations are investigated to meet the GEN IV goals of safety and of process development. One of the challenges is to mitigate the Sodium Water Reaction currently used in these processes. The potential applications of aqueous solutions of mineral salts (including the possibility of using redox chemical reactions) to mitigate the Sodium Water Reaction are considered in a first part and a new experimental bench, dedicated to this study, is described. Anhydrous alternative options based on Na/CO{sub 2} interaction are also presented. Then, in a second part, a functional study conducted on the cleaning pit is proposed. Based on experimental feedback, some calculations are carried out to estimate the sodium inventory on the fuel elements, and physical methods like hot inert gas sweeping to reduce this inventory are also presented. Finally, the implementation of these innovative solutions in cleaning pits is studied in regard to the expected performances. (authors)

  2. Assembly for facilitating inservice inspection of a reactor coolant pump rotor

    DOEpatents

    Veronesi, Luciano

    1990-01-01

    A reactor coolant pump has an outer casing with an internal cavity holding a coolant and a rotor rotatably mounted in the cavity within the coolant. An assembly for permitting inservice inspection of the pump rotor without first draining the coolant from the casing cavity is attached to an end of the pump. A cylindrical bore is defined through the casing in axial alignment with an end of pump rotor and opening into the internal cavity. An extension attached on the rotor end and rotatable therewith has a cylindrical coupler member extending into the bore. An outer end of the coupler member has an element configured to receive a tool for performance of inservice rotor inspection. A hollow cylindrical member is disposed in the bore and surrounds the coupler member. The cylindrical member is slidably movable relative to the coupler member along the bore between a retracted position wherein the cylindrical member is stored for normal pump operation and an extended position wherein the cylindrical member is extended for permitting inservice rotor inspection. A cover member is detachably and sealably attached to the casing across the bore for closing the bore and retaining the cylindrical member at its retracted position for normal pump operation. Upon detachment of the cover member, the cylindrical member can be extended to permit inservice rotor inspection.

  3. Bottom head to shell junction assembly for a boiling water nuclear reactor

    DOEpatents

    Fife, A.B.; Ballas, G.J.

    1998-02-24

    A bottom head to shell junction assembly which, in one embodiment, includes an annular forging having an integrally formed pump deck and shroud support is described. In the one embodiment, the annular forging also includes a top, cylindrical shaped end configured to be welded to one end of the pressure vessel cylindrical shell and a bottom, conical shaped end configured to be welded to the disk shaped bottom head. Reactor internal pump nozzles also are integrally formed in the annular forging. The nozzles do not include any internal or external projections. Stubs are formed in each nozzle opening to facilitate welding a pump housing to the forging. Also, an upper portion of each nozzle opening is configured to receive a portion of a diffuser coupled to a pump shaft which extends through the nozzle opening. Diffuser openings are formed in the integral pump deck to provide additional support for the pump impellers. The diffuser opening is sized so that a pump impeller can extend at least partially therethrough. The pump impeller is connected to the pump shaft which extends through the nozzle opening. 5 figs.

  4. Critical role of wettability in assembly of zirconia nanoparticles on a self-assembled monolayer-patterned substrate

    NASA Astrophysics Data System (ADS)

    Yang, Mi-Sun; Lee, Seung-Hoon; Moon, Byung Kee; Yoo, Seung Ryul; Hwang, Seongpil; Jang, Jae-Won

    2016-08-01

    This study investigated which factors decisively influence colloidal nanoparticle (NP) assembly on a self-assembled monolayer (SAM)-patterned substrate. Zirconia (ZrO2) NP assembly on a poly(dimethylsiloxane) (PDMS)-stamped SAM-patterned Au substrate was carried out while the size and surface charge state of the NPs and the substrate wettability were altered. ZrO2 particles with diameters of 350 nm, 560 nm, and 1100 nm were employed to examine the effect of NP size on the assembly. Bare ZrO2 NPs with a negatively charged surface and ZrO2 NPs with a positively charged surface through 3-aminopropyltriethoxysilane encapsulation were prepared for the NP assembly. Moreover, the substrate wettability effect on the NP assembly was evaluated by comparing the assembly on substrates with the PDMS-patterned SAMs of thiols with polar and non-polar functional groups. From the characterization of the number of NPs in a pattern and the effective area of assembled NPs (Aeff), positively charged ZrO2 NP assembly on negatively charged patterns showed the highest number density of particles in a pattern compared with the other combinations in both 350-nm and 560-nm ZrO2 NPs. This observation can be attributed to negatively charged 16-mercaptohexadecanoic acid SAMs having greater polarity (more polar groups) than positively charged 11-amino-1-undecanethiol SAMs within the condition of the colloidal ZrO2 NP assembly.

  5. Remote Sensing and the Kyoto Protocol: A Workshop Summary

    NASA Technical Reports Server (NTRS)

    Rosenqvist, Ake; Imhoff, Marc; Milne, Anthony; Dobson, Craig

    2000-01-01

    The Kyoto Protocol to the United Nations Framework Convention on Climate Change contains quantified, legally binding commitments to limit or reduce greenhouse gas emissions to 1990 levels and allows carbon emissions to be balanced by carbon sinks represented by vegetation. The issue of using vegetation cover as an emission offset raises a debate about the adequacy of current remote sensing systems and data archives to both assess carbon stocks/sinks at 1990 levels, and monitor the current and future global status of those stocks. These concerns and the potential ratification of the Protocol among participating countries is stimulating policy debates and underscoring a need for the exchange of information between the international legal community and the remote sensing community. On October 20-22 1999, two working groups of the International Society for Photogrammetry and Remote Sensing (ISPRS) joined with the University of Michigan (Michigan, USA) to convene discussions on how remote sensing technology could contribute to the information requirements raised by implementation of, and compliance with, the Kyoto Protocol. The meeting originated as a joint effort between the Global Monitoring Working Group and the Radar Applications Working Group in Commission VII of the ISPRS, co-sponsored by the University of Michigan. Tile meeting was attended by representatives from national government agencies and international organizations and academic institutions. Some of the key themes addressed were: (1) legal aspects of transnational remote sensing in the context of the Kyoto Protocol; (2) a review of the current and future and remote sensing technologies that could be applied to the Kyoto Protocol; (3) identification of areas where additional research is needed in order to advance and align remote sensing technology with the requirements and expectations of the Protocol; and 94) the bureaucratic and research management approaches needed to align the remote sensing

  6. Universal Pragmatics: A Critical Approach to Image Ethics.

    ERIC Educational Resources Information Center

    Craig, Robert L.

    Visual criticism is a major component of the new visual communication. Visual communication has changed through the advent of new technology which allows images to be combined and manipulated with relative ease. Visual criticism analyzes the forms and practices of image production and examines the roles of images in society creating a new dialogue…

  7. Creative Writing and Critical Response in the University Literature Class

    ERIC Educational Resources Information Center

    Wilson, Peter

    2011-01-01

    Concerns about the relation between critical and creative writing are reviewed in the context of encouraging students to engage in both kinds of writing as a response to literature in undergraduate degree courses. In particular the paper seeks to illustrate and promote good practice in the integration of creative and critical written responses to…

  8. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    SciTech Connect

    Cappiello, C.C.; Butterfield, K.B.; Sanchez, R.G.

    1997-10-01

    The Solution High-Energy Burst Assembly (SHEBA) was originally constructed during 1980 and was designed to be a clean free-field geometry, right-circular, cylindrically symmetric critical assembly employing U(5%)O{sub 2}F{sub 2} solution as fuel. A second version of SHEBA, employing the same fuel but equipped with a fuel pump and shielding pit, was commissioned in 1993. This report includes data and operating experience for the 1993 SHEBA only. Solution-fueled benchmark work focused on the development of experimental measurements of the characterization of SHEBA; a summary of the results are given. A description of the system and the experimental results are given in some detail in the report. Experiments were designed to: (1) study the behavior of nuclear excursions in a low-enrichment solution, (2) evaluate accidental criticality alarm detectors for fuel-processing facilities, (3) provide radiation spectra and dose measurements to benchmark radiation transport calculations on a low-enrichment solution system similar to centrifuge enrichment plants, and (4) provide radiation fields to calibrate personnel dosimetry. 15 refs., 37 figs., 10 tabs.

  9. Monte Carlo testing of unresolved resonance treatment for fast and intermediate critical assemblies

    SciTech Connect

    Weinman, J.P.

    1998-10-01

    The purpose of this study is to investigate the eigenvalue sensitivity to changes in unresolved resonance treatment by comparing RACER Monte Carlo calculations for several fast and intermediate spectrum critical experiments. Calculations performed using smooth, dilute-average, tabulated cross sections were compared with calculations using the probability table method to produce stochastically generated resonance cross sections in the unresolved resonance region. The use of the probability table method is superior to the dilute-average cross section method for representing the unresolved resonance region because the table method properly accounts for resonance self shielding; thereby, reducing the effectiveness of the cross sections in the region. The unresolved resonance region is typically found in the intermediate and fast energy range. Eleven benchmark critical assemblies that span a range of {sup 235}U enrichments (93.8 to 10.2%) and four highly enriched {sup 239}Pu and {sup 233}U assemblies were analyzed. These benchmarks were chosen to accentuate the reactivity importance of the unresolved resonance range.

  10. PREFACE: Beyond Kyoto - the necessary road

    NASA Astrophysics Data System (ADS)

    Margrethe Basse, Ellen

    2009-03-01

    The Beyond Kyoto conference in Aarhus March 2009 was organised in collaboration with other knowledge institutions, businesses and authorities. It brought together leading scientists, policy-makers, authorities, intergovernmental organisations, NGO's, business stakeholders and business organisations. The conference was a joint interdisciplinary project involving many academic areas and disciplines. These conference proceedings are organised in central and recurring themes that cut across many debates on climate change, the climatic challenges as well as the solutions. In the front there is a short presentation of the conference concept. Part I of the proceedings focuses on issues related to the society - covering climate policy, law, market based instruments, financial structure, behaviour and consumption, public participation, media communication and response from indigenous peoples etc. Part II of the proceedings concerns the scientific knowledge base on climate related issues - covering climate change processes per se, the potential impacts of projected climate change on biodiversity and adaptation possibilities, the interplay between climate, agriculture and biodiversity, emissions, agricultural systems, increasing pressure on the functioning of agriculture and natural areas, vulnerability to extreme weather events and risks in respect to sea-level rise etc. The conference proceedings committee consists of four professors from Aarhus University: Jens-Christian Svenning, Jørgen E Olesen, Mads Forchhammer and Ellen Margrethe Basse. Aarhus University's Climate Secretariat has had the overall responsibility for coordinating the many presentations, as well as the practical side of arranging the conference and supporting the publication of papers. As Head of the Climate Secretariat and Chair of Aarhus University's Climate Panel, I would like to thank everyone for their contribution. This applies both to the scientific and the practical efforts. Special thanks to

  11. Experimental study of the effect of spacer grid on the flow structure in fuel assemblies of the AES 2006 reactor

    NASA Astrophysics Data System (ADS)

    Kashinskii, O. N.; Lobanov, P. D.; Pribaturin, N. A.; Kurdyumov, A. S.; Volkov, S. E.

    2013-01-01

    Results from an experimental study of the local hydrodynamic structure of liquid flow in a 37-cell model simulating a fuel assembly used in the AES-2006 reactor are presented. Special attention is paid to the effect of spacer grid on flow hydrodynamics. Data on variations of the local and integral values of the liquid axial velocity and friction stress on the fuel rod simulator's wall with distance from the grid are given.

  12. Critical Role of the Fusion Protein Cytoplasmic Tail Sequence in Parainfluenza Virus Assembly

    PubMed Central

    Stone, Raychel; Takimoto, Toru

    2013-01-01

    Interactions between viral glycoproteins, matrix protein and nucleocapsid sustain assembly of parainfluenza viruses at the plasma membrane. Although the protein interactions required for virion formation are considered to be highly specific, virions lacking envelope glycoprotein(s) can be produced, thus the molecular interactions driving viral assembly and production are still unclear. Sendai virus (SeV) and human parainfluenza virus type 1 (hPIV1) are highly similar in structure, however, the cytoplasmic tail sequences of the envelope glycoproteins (HN and F) are relatively less conserved. To unveil the specific role of the envelope glycoproteins in viral assembly, we created chimeric SeVs whose HN (rSeVhHN) or HN and F (rSeVh(HN+F)) were replaced with those of hPIV1. rSeVhHN grew as efficiently as wt SeV or hPIV1, suggesting that the sequence difference in HN does not have a significant impact on SeV replication and virion production. In sharp contrast, the growth of rSeVh(HN+F) was significantly impaired compared to rSeVhHN. rSeVh(HN+Fstail) which expresses a chimeric hPIV1 F with the SeV cytoplasmic tail sequence grew similar to wt SeV or rSeVhHN. Further analysis indicated that the F cytoplasmic tail plays a critical role in cell surface expression/accumulation of HN and F, as well as NP and M association at the plasma membrane. Trafficking of nucelocapsids in infected cells was not significantly affected by the origin of F, suggesting that F cytoplasmic tail is not involved in intracellular movement. These results demonstrate the role of the F cytoplasmic tail in accumulation of structural components at the plasma membrane assembly sites. PMID:23593451

  13. Innovation for Transformation in Nigeria University Education: Implications for the Production of Critical and Creative Thinkers

    ERIC Educational Resources Information Center

    Onu, V. C.; Eskay, M. K.; Obiyo, N. O.; Igbo, J. N.; Ezeanwu, A. B.

    2012-01-01

    This descriptive survey research studied innovation for transformation in Nigeria university education: implications for the production of critical and creative thinkers. Thus, students' perception of knowledge generation and dissemination by university lecturers were elicited. From a population of registered students in a Nigerian university, 200…

  14. The Internationalisation Agenda: A Critical Examination of Internationalisation Strategies in Public Universities in Ghana

    ERIC Educational Resources Information Center

    Gyamera, Gifty Oforiwaa

    2015-01-01

    Recently, various strategies have been adopted and adapted by universities in Ghana to re/position themselves in the international arena. Utilising postcolonial and neoliberal theories, this paper critically examines the internationalisation strategies of three public universities in Ghana. Although all the universities have adopted strategies to…

  15. [Dr. Michiharu Matsuoka, founder of the Department of Orthopaedic Surgery, Kyoto University, and his achievements. (Part 7: The academic carrier of Dr. Michiharu Matsuoka--from elementary school to the graduate school, Imperial University of Tokyo)].

    PubMed

    Hirotani, Hayato

    2011-12-01

    The background of the higher education of Dr. Michiharu Matsuoka shown on the official resume was disclosed by Dr. Kazuo Naito in 1986, but the courses of the elementary and secondary schools were not described in it. In regard to his lower educational courses, the author referred to the laws and regulations issued by the Ministry of Education of the Japan Government and the Yamaguchi Prefectural Office. Those were often revised with times. The author presumed the elementary school (Murozumi Primary School [the first established primary school at the birthplace; Murozumi, Hikari-City, Yamaguchi Prefecture]) and middle schools (Prefectural Yamaguchi Middle School and Yamaguchi High School) to which he had been admitted. These presumptions were made to explain his whole educational course without unreasonableness. After finishing the first school year of the Yamaguchi High School, he was transferred to the Preparatory Course of the Yamaguchi Higher School (Yamaguchi Kotô Chugakkô, Yoka), because of the amendment of the educational system. Then he was transferred to the Preparatory Course of the Daisan Higher School (Daisan Kotô Chugakkô, Yoka), and to the Preparatory Course of Daiichi Higher School (Daiichi Kotô Chugakkô, Yoka). After his graduation from the Regular Course of the Daiichi Higher School (Daiichi Kotô Chugakkô, Honka), he was admitted to the Medical College of the Imperial University from which he graduated in 1897. In addition, he was a medical student of the Graduate School of the Imperial University of Tokyo just before he left Japan for studying abroad. The whole academic carrier of Dr. Matsuoka is not only clearly clarified, but it is also indicated that he was one of the successful examples of the educational system proposed by Yamaguchi Prefecture in Meiji era which articulated the local primary and middle schools with the Imperial University of Tokyo. PMID:22586890

  16. Agreement between the University of Hawaii Professional Assembly and the Board of Regents of the University of Hawaii, 1983-1985.

    ERIC Educational Resources Information Center

    American Association of Univ. Professors, Washington, DC.

    The collective bargaining agreement between the University of Hawaii Board of Regents and the University of Hawaii Professional Assembly covering the period July 1, 1983-June 30, 1985 is presented. The American Association of University Professors affiliated union has 2,810 members. Items covered in the agreement include: unit recognition,…

  17. NUCLEAR REACTOR

    DOEpatents

    Sherman, J.; Sharbaugh, J.E.; Fauth, W.L. Jr.; Palladino, N.J.; DeHuff, P.G.

    1962-10-23

    A nuclear reactor incorporating seed and blanket assemblies is designed. Means are provided for obtaining samples of the coolant from the blanket assemblies and for varying the flow of coolant through the blanket assemblies. (AEC)

  18. Criticality benchmark guide for light-water-reactor fuel in transportation and storage packages

    SciTech Connect

    Lichtenwalter, J.J.; Bowman, S.M.; DeHart, M.D.; Hopper, C.M.

    1997-03-01

    This report is designed as a guide for performing criticality benchmark calculations for light-water-reactor (LWR) fuel applications. The guide provides documentation of 180 criticality experiments with geometries, materials, and neutron interaction characteristics representative of transportation packages containing LWR fuel or uranium oxide pellets or powder. These experiments should benefit the U.S. Nuclear Regulatory Commission (NRC) staff and licensees in validation of computational methods used in LWR fuel storage and transportation concerns. The experiments are classified by key parameters such as enrichment, water/fuel volume, hydrogen-to-fissile ratio (H/X), and lattice pitch. Groups of experiments with common features such as separator plates, shielding walls, and soluble boron are also identified. In addition, a sample validation using these experiments and a statistical analysis of the results are provided. Recommendations for selecting suitable experiments and determination of calculational bias and uncertainty are presented as part of this benchmark guide.

  19. Summary of experimental data for critical arrays of water moderated Fast Test Reactor fuel

    SciTech Connect

    Durst, B.M.; Bierman, S.R.; Clayton, E.D.; Mincey, J.F.; Primm, R.T. III

    1981-05-01

    A research program, funded by the Consolidated Fuel Reprocessing Program (CFRP) of Oak Ridge National Laboratory (ORNL), was initiated at Battelle Pacific Northwest Laboratory (PNL) to acquire experimental data on heterogeneous water moderated arrays of Fast Test Reactor (FTR) fuel pins. The objective of this program is to provide critical experiment data for validating calculational techniques used in criticality assessments of reprocessing equipment containing FTR-type fuels. Consequently, the experiments were designed to permit accurate definition in Monte Carlo computer codes currently used in these assessments. Square and triangular pitched lattices of fuel have been constructed under a variety of conditions covering the range from undermoderated to overmoderated arrays. Experiments were conducted composed of arrays which were water reflected, partially concrete reflected, and arrays with interspersed solid neutron absorbers. The absorbers utilized were Boral, and cadmium plates and gadolinium cylindrical rods. Data from non-CFRP sponsored subcritical experiments (previously performed at Hanford) also are included.

  20. 75 FR 56597 - University of Wisconsin; University of Wisconsin Nuclear Reactor Environmental Assessment and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-16

    ... or crawl space below the Reactor Laboratory floor. The walls are concrete and brick. The ceiling is a... meters (8 feet) wide, 3.7 meters (12 feet) long, and 8.5 meters (27.5 feet) deep. Light water acts as...

  1. Universal relations in the self-assembly of proteins and RNA

    NASA Astrophysics Data System (ADS)

    Thirumalai, D.

    2014-10-01

    Concepts rooted in physics are becoming increasingly important in biology as we transition to an era in which quantitative descriptions of all processes from molecular to cellular level are needed. In this perspective I discuss two unexpected findings of universal behavior, uncommon in biology, in the self-assembly of proteins and RNA. These findings, which are surprising, reveal that physics ideas applied to biological problems, ranging from folding to gene expression to cellular movement and communication between cells, might lead to discovery of universal principles operating in adoptable living systems.

  2. Young Children Demystifying and Remaking the University through Critical Play

    ERIC Educational Resources Information Center

    Campano, Gerald; Ngo, Lan; Low, David E.; Bartow Jacobs, Katrina

    2016-01-01

    This article, part of a four-year research partnership with a multilingual faith community and its school, explores what happened when we invited young children in an aftercare program to inquire into the university from their perspectives. Through a sociocultural literacy framework and realist theories of identity and experience, we examine the…

  3. Creativity and Critical Thinking in the Globalised University

    ERIC Educational Resources Information Center

    Clegg, Phil

    2008-01-01

    This paper outlines the dynamic life of the university in the era of neo-liberal globalisation, and within this context, discusses the nature of "creativity" as a life force or power, similar to the Ancient Greek idea of "Eros". This power is contrasted with functionalist and bureaucratic notions of creativity, and a disjuncture is identified…

  4. Critical Factors in the Use of Evaluation in Italian Universities

    ERIC Educational Resources Information Center

    Rebora, Gianfranco; Turri, Matteo

    2011-01-01

    The use made of evaluation output is crucial for understanding the position and effectiveness of evaluation systems. This article examines the development of evaluation in the Italian university system from the 1990s onwards where serious problems have been and continue to be addressed in the use of evaluation output to improve academic activities…

  5. Building Technology Transfer Capacity in Turkish Universities: A Critical Analysis

    ERIC Educational Resources Information Center

    Ranga, Marina; Temel, Serdal; Ar, Ilker Murat; Yesilay, Rustem Baris; Sukan, Fazilet Vardar

    2016-01-01

    University technology transfer has been receiving significant government funding since 2012. Results of this major investment are now expected by the Turkish government and society, not only in terms of better teaching and research performance, but also of new jobs, new products and services, enhanced regional development and contribution to…

  6. The Potential of Critical Race Theory in Decolonizing University Curricula

    ERIC Educational Resources Information Center

    McLaughlin, Juliana; Whatman, Susan

    2011-01-01

    This paper critiques our experiences as non-Indigenous Australian educators of working with numerous embedding Indigenous perspectives curricular projects at an Australian university. Reporting on these project outcomes alone, while useful in identifying limitations, does not illustrate ways in which future embedding and decolonizing projects can…

  7. Modeling of Coolant Flow in the Fuel Assembly of the Reactor of a Floating Nuclear Power Plant Using the Logos CFD Program

    NASA Astrophysics Data System (ADS)

    Dmitriev, S. M.; Dobrov, A. A.; Legchanov, M. A.; Khrobostov, A. E.

    2015-09-01

    Results of computer modeling of coolant flow in the fuel assembly of the reactor of a floating nuclear power plant using the LOGOS CFD programs have been given. The possibility of using the obtained results to improve models built into the engineering programs of thermohydraulic calculation of nuclear-reactor cores has been considered.

  8. Thermally Simulated 32kW Direct-Drive Gas-Cooled Reactor: Design, Assembly, and Test

    NASA Astrophysics Data System (ADS)

    Godfroy, Thomas J.; Kapernick, Richard J.; Bragg-Sitton, Shannon M.

    2004-02-01

    One of the power systems under consideration for nuclear electric propulsion is a direct-drive gas-cooled reactor coupled to a Brayton cycle. In this system, power is transferred from the reactor to the Brayton system via a circulated closed loop gas. To allow early utilization, system designs must be relatively simple, easy to fabricate, and easy to test using non-nuclear heaters to closely mimic heat from fission. This combination of attributes will allow pre-prototypic systems to be designed, fabricated, and tested quickly and affordably. The ability to build and test units is key to the success of a nuclear program, especially if an early flight is desired. The ability to perform very realistic non-nuclear testing increases the success probability of the system. In addition, the technologies required by a concept will substantially impact the cost, time, and resources required to develop a successful space reactor power system. This paper describes design features, assembly, and test matrix for the testing of a thermally simulated 32kW direct-drive gas-cooled reactor in the Early Flight Fission - Test Facility (EFF-TF) at Marshall Space Flight Center. The reactor design and test matrix are provided by Los Alamos National Laboratories.

  9. Thermally Simulated 32kW Direct-Drive Gas-Cooled Reactor: Design, Assembly, and Test

    SciTech Connect

    Godfroy, Thomas J.; Bragg-Sitton, Shannon M.; Kapernick, Richard J.

    2004-02-04

    One of the power systems under consideration for nuclear electric propulsion is a direct-drive gas-cooled reactor coupled to a Brayton cycle. In this system, power is transferred from the reactor to the Brayton system via a circulated closed loop gas. To allow early utilization, system designs must be relatively simple, easy to fabricate, and easy to test using non-nuclear heaters to closely mimic heat from fission. This combination of attributes will allow pre-prototypic systems to be designed, fabricated, and tested quickly and affordably. The ability to build and test units is key to the success of a nuclear program, especially if an early flight is desired. The ability to perform very realistic non-nuclear testing increases the success probability of the system. In addition, the technologies required by a concept will substantially impact the cost, time, and resources required to develop a successful space reactor power system. This paper describes design features, assembly, and test matrix for the testing of a thermally simulated 32kW direct-drive gas-cooled reactor in the Early Flight Fission - Test Facility (EFF-TF) at Marshall Space Flight Center. The reactor design and test matrix are provided by Los Alamos National Laboratories.

  10. ENDF/B-VII.0 Data Testing for Three Fast Critical Assemblies

    SciTech Connect

    Cullen, D E; Blomquist, R N; Brown, P N; Dean, C J; Dunn, M E; Lee, Y; Lent, E; MacFarlane, R; McKinley, S; Plechaty, E F; Sublet, J C

    2007-07-27

    In this report we consider three fast critical assemblies, each assembly is dominated by a different nuclear fuel: Godiva (U235), Jezebel (Pu239) and Jezebel23 (U233) [1]. We first show the improvement in results when using the new ENDF/B-VII.0 data [2], rather than the older, now frozen, ENDF/B-VI.8 data [3]. We do this using what we call a one code/ multiple library approach, where results from one code (MCNP) are compared using two different data libraries (ENDF/B-VII.0 and VI.8). Next we show that MCNP results are not specific to this one code by using what we call a one data library/multiple code approach; for this purpose we invited many codes to submit results using the ENDF/B-VII.0 data; the most detailed results presented in this report compare MCNP and TART. The bottom line is that we have shown that using the new ENDF/B-VII.0 data library with a variety of transport codes, for the first time we are able to reproduce the expected K-eff values for all three assemblies to within the quoted accuracy of the models, namely 1.0 +/- 0.001. This is a BIG improvement compared to the results obtained using the older ENDF/B-VI.8 data library. Another important result of this study is that we have demonstrated that currently there are many computer codes that can accurately use the new ENDF/B-VII.0 data.

  11. Study of neutron noise from reflected, metal assemblies with criticality safety applications in mind

    SciTech Connect

    Barnett, C.S.

    1985-08-20

    The author studied the statistics of detected neutrons that leaked from four subcritical reflected, enriched-uranium assemblies, to explore the feasibility of developing a criticality warning system based on neutron noise analysis. The calculated multiplication factors of the assemblies are 0.59, 0.74, 0.82, and 0.92. The author studied three possible discriminators, i.e., three signatures that might be used to discriminate among assemblies of various multiplications. They are: (1) variance-to-mean ratio of the counts in a time bin (V/M); (2) covariance-to-mean ratio of the counts in a common time bin from two different detectors (C/M); and (3) covariance-to-mean ratio of the counts from a single detector in two adjacent time bins of equal length, which the author calls the serial-covariance-to-mean ratio (SC/M). The performances of the three discriminators were not greatly different, but a hierarchy did emerge: SC/M greater than or equal to V/M greater than or equal to C/M. An example of some results: in the neighborhood of k = 0.6 the ..delta..k required for satisfactory discrimination varies from about 3% to 7% as detector solid angle varies from 19% to 5%. In the neighborhood of k = 0.8 the corresponding ..delta..ks are 1% and 2%. The noise analysis techniques studied performed well enough in deeply subcritical situations to deserve testing in an applications environment. They have a good chance of detecting changes in reactivity that are potentially dangerous. One can expect sharpest results when doing comparisons, i.e., when comparing two records, one taken in the past under circumstances known to be normal and one taken now to search for change.

  12. Reactor Meltdown: Critical Zone Processes In Siliciclastics Unlikely To Be Directly Transferable To Carbonates

    NASA Astrophysics Data System (ADS)

    Gulley, J. D.; Cohen, M. J.; Kramer, M. G.; Martin, J. B.; Graham, W. D.

    2013-12-01

    Carbonate terrains cover 20% of Earth's ice-free land and are modified through interactions between rocks, water and biota that couple ecosystems processes to weathering reactions within the critical zone. Weathering in carbonate systems differs from the Critical Zone Reactor model developed for siliciclastic systems because reactions in siliciclastic critical zones largely consist of incongruent weathering (e.g., feldspar to secondary clay minerals) that typically occur in the soil zone within a few meters of the land surface. These incongruent reactions create regolith, which is removed by physical transport mechanisms that drive landscape denudation. In contrast, carbonate critical zones are mostly composed of homogeneous and soluble minerals, which dissolve congruently with the weathering products exported in solution, limiting regolith in the soil mantle to small amounts of insoluble residues. These reactions can extend to depths greater than 2 km below the surface. As water at the land surface drains preferentially through vertical joints and horizontal bedding planes of the carbonate critical zones, it is 'charged' with biologically-derived carbon dioxide, which decreases pH, dissolves carbonate rock, and enlarges subsurface flowpaths through feedbacks between flow and dissolution. Caves are extreme end products of this process and are key morphological features of carbonate critical zones. Caves link surface processes to the deep subsurface and serve as efficient delivery agents for oxygen, carbon and nutrients to zones within the critical zone that are deficient in all three, interrupting vertical and horizontal chemical gradients that would exist if caves were not present. We present select data from air and water-filled caves in the upper Floridan aquifer, Florida, USA, that demonstrate how caves, acting as very large preferential flow paths, alter processes in carbonate relative to siliciclastic critical zones. While caves represent an extreme end

  13. Sulfur activation at the Little Boy-Comet Critical Assembly: a replica of the Hiroshima bomb

    SciTech Connect

    Kerr, G.D.; Emery, J.F.; Pace, J.V. III

    1985-04-01

    Studies have been completed on the activation of sulfur by fast neutrons from the Little Boy-Comet Critical Assembly which replicates the general features of the Hiroshima bomb. The complex effects of the bomb's design and construction on leakage of sulfur-activation neutrons were investigated both experimentally and theoretically. Our sulfur activation studies were performed as part of a larger program to provide benchmark data for testing of methods used in recent source-term calculations for the Hiroshima bomb. Source neutrons capable of activating sulfur play an important role in determining neutron doses in Hiroshima at a kilometer or more from the point of explosion. 37 refs., 5 figs., 6 tabs.

  14. University of Florida--US Department of Energy 1994-1995 reactor sharing program

    SciTech Connect

    Vernetson, W.G.

    1996-06-01

    The grant support of $24,250 (1994-95?) was well used by the University of Florida as host institution to support various educational institutions in the use of UFTR Reactor. All users and uses were screened to assure the usage was for educational institutions eligible for participation in the Reactor Sharing Program; where research activities were involved, care was taken to assure the research was not funded by grants for contract funding from outside sources. Over 12 years, the program has been a key catalyst for renewing utilization of UFTR both by external users around the State of Florida and the Southeast and by various faculty members within the University of Florida. Tables provide basic information about the 1994-95 program and utilization of UFTR.

  15. University of Virginia {open_quotes}virtual{close_quotes} reactor facility tours

    SciTech Connect

    Krause, D.R.; Mulder, R.U.

    1995-12-31

    An electronic information and tour book has been constructed for the University of Virginia reactor (UVAR) facility. Utilizing the global Internet, the document resides on the University of Virginia World Wide Web (WWW or W) server within the UVAR Homepage at http://www.virginia. edu/{approximately}reactor/. It is quickly accessible wherever an Internet connection exists. The UVAR Homepage files are accessed with the hypertext transfer protocol (http) prefix. The files are written in hypertext markup language (HTML), a very simple method of preparing ASCII text for W3 presentation. The HTML allows use of various hierarchies of headers, indentation, fonts, and the linking of words and/or pictures to other addresses-uniform resource locators. The linking of texts, pictures, sounds, and server addresses is known as hypermedia.

  16. Critical limits (alert values) for physician notification: universal or medical center specific limits?

    PubMed

    Lum, G

    1998-01-01

    The concept of critical limits (alert values), defined as an imminent life threatening laboratory result requiring immediate physician notification, has been widely adopted as a standard of good laboratory practice. Although virtually all laboratories have tests with critical limits, surveys have shown that there is no universal alert value list. Recently, nine VA medical centers in the New England region, which now constitute one consolidated entity, were surveyed with the objective of summarizing critical limits. Universal (100 percent) critical limit tests for clinical chemistry were: Calcium; mean low/high, 6.5/12.4 mg/dL: Glucose 48/432 mg/dL: Potassium 2.8/6.1 mmol/L: Sodium 121/159 mmol/L. Universal hematology tests included: Hematocrit 22.2/59.7 percent: Platelet count 61K/983K: white blood count 1.9K/29K. Although there was universal agreement that abnormal coagulation tests (PT, PTT) should be included on the hematology critical limit list, there was wide variation in the reporting of coagulation tests (seconds and INR) and patient therapeutic status (anticoagulant or no-anticoagulant). Universal alert values for microbiology were: Positive blood culture: Positive cerebral spinal fluid (CSF) culture: Positive CSF Gram stain. There was no universal agreement regarding critically high (potentially toxic) therapeutic drugs, with two medical centers declining to notify physicians of any abnormally high therapeutic drug level. No other qualitative critical limits for other laboratory sections, such as physician notification of an unexpected malignancy (surgical pathology) were universal. Medical center specific critical limits, designed to meet the clinical needs of each facility, are the norm in the nine medical centers. Laboratories do need periodically to review their critical limit lists with appropriate clinical input to avoid including critical limits for laboratory tests not required for urgent physician notification and patient evaluation and treatment.

  17. Power Distribution Analysis for the ORNL High Flux Isotope Reactor Critical Experiment 3

    SciTech Connect

    Chandler, David; Primm, Trent; Maldonado, G Ivan

    2010-01-01

    The mission of the Reduced Enrichment for Research and Test Reactors Program is to minimize and, to the extent possible, eliminate the use of highly enriched uranium (HEU) in civilian nuclear applications by working to convert research and test reactors, as well as radioisotope production processes, to low-enriched uranium (LEU) fuel and targets. Oak Ridge National Laboratory (ORNL) is currently reviewing the design bases and key operating criteria including fuel operating parameters, enrichment-related safety analyses, fuel performance, and fuel fabrication in regard to converting the fuel of the High Flux Isotope Reactor (HFIR) from HEU to LEU. The purpose of this study is to validate Monte Carlo methods currently in use for conversion analyses. The methods have been validated for the prediction offlux values in the reactor target, reflector, and beam tubes, but this study focuses on the prediction of the power density profile in the core. Power distributions were calculated in the fuel elements of the HFIR, a research reactor at ORNL, via MCNP and were compared to experimentally obtained data. This study was performed to validate Monte Carlo methods for power density calculations and to observe biases. A current three-dimensional MCNP model was modified to replicate the 1965 HFIR Critical Experiment 3 (HFIRCE-3). In this experiment, the power profile was determined by counting the gamma activity at selected locations in the core. 'Foils' (chunks of fuel meat and clad) were punched out of the fuel elements in HFIRCE-3 following irradiation, and experimental relative power densities were obtained by measuring the activity of these foils and comparing each foil's activity to the activity of a normalizing foil. This analysis consisted of calculating corresponding activities by inserting volume tallies into the modified MCNP model to represent the punchings. The average fission density was calculated for each foil location and then normalized to the reference foil

  18. Design of a weapons-grade plutonium assembly for optimal burnup in a standard pressurized water reactor

    NASA Astrophysics Data System (ADS)

    Alonso-Vargas, Gustavo

    We created a new MOX fuel assembly design that can be used in standard Westinghouse pressurized water reactors (PWR) to maximize the plutonium throughput while introducing the lowest perturbation possible to the control and safety systems of the reactor. Our assembly design, which is called MIX-33, appears to be a good option for the disposition of weapons-grade plutonium (WG-Pu), increasing the plutonium disposition rate by 8% compared to a previous Westinghouse design. It is based in two novel ideas: the use of both uranium and plutonium fuel pins in the same assembly, and the increase of the moderation ratio of the assembly. We replaced 8 fuel pins by water holes to increase the moderation ratio. We can transition smoothly from a full LEU core to a full MIX-33 core meeting the operational and safety regulations of a standard PWR. Given a MOX supply interruption scenario we can transition smoothly to full LEU meeting the safety regulations and using standard LEU assemblies with uniform enriched pin-wise distribution. If the MOX supply is interrupted for only one cycle, we are able to transition back to full MIX-33 core. However, in this case we probably need to de-rate the power by a few percent for a few weeks at the beginning of the cycle (BOC) to accommodate high peaking. For comparison we created another assembly design without extra water holes, which we called "MIX-25". It behaves in all the conditions analyzed in a similar way to the MIX-33 but it does present minor control problems. These can be solved by making small modifications to the control and safety systems, namely by enriching the boron-10 content of some boron absorbers. Thus, the addition of water holes replacing fuel pins helps to improve the MIX-33 performance and eliminate the difficulties seen in the MIX-25 design. We also performed a benchmarking analysis to test the code CASMO-3 to analyze WG-Pu assemblies, using the code MCNP-4A to compare. We found good agreement between CASMO-3 and

  19. Burst wait time simulation of CALIBAN reactor at delayed super-critical state

    SciTech Connect

    Humbert, P.; Authier, N.; Richard, B.; Grivot, P.; Casoli, P.

    2012-07-01

    In the past, the super prompt critical wait time probability distribution was measured on CALIBAN fast burst reactor [4]. Afterwards, these experiments were simulated with a very good agreement by solving the non-extinction probability equation [5]. Recently, the burst wait time probability distribution has been measured at CEA-Valduc on CALIBAN at different delayed super-critical states [6]. However, in the delayed super-critical case the non-extinction probability does not give access to the wait time distribution. In this case it is necessary to compute the time dependent evolution of the full neutron count number probability distribution. In this paper we present the point model deterministic method used to calculate the probability distribution of the wait time before a prescribed count level taking into account prompt neutrons and delayed neutron precursors. This method is based on the solution of the time dependent adjoint Kolmogorov master equations for the number of detections using the generating function methodology [8,9,10] and inverse discrete Fourier transforms. The obtained results are then compared to the measurements and Monte-Carlo calculations based on the algorithm presented in [7]. (authors)

  20. Universities and Regional Development: A Critical Assessment of Tensions and Contradictions. International Studies in Higher Education

    ERIC Educational Resources Information Center

    Pinheiro, Romulo, Ed.; Benneworth, Paul, Ed.; Jones, Glen A., Ed.

    2012-01-01

    Universities are under increasing pressure to help promote socio-economic growth in their local communities. However until now, no systematic, critical attention has been paid to the factors and mechanisms that currently make this process so daunting. In Universities and Regional Development, scholars from Europe, the Americas, Africa, and Asia…

  1. Adapting, Not Adopting: Barriers Affecting Teaching for Critical Thinking at Two Rwandan Universities

    ERIC Educational Resources Information Center

    Schendel, Rebecca

    2016-01-01

    A recent study of student learning at three of Rwanda's most prestigious public universities has suggested that Rwandan students are not improving in their critical thinking ability during their time at university. This article reports on a series of faculty-level case studies, which were conducted at two of the participating institutions in order…

  2. University-School-Community Partnership as Vehicle for Leadership, Service, and Change: A Critical Brokerage Perspective

    ERIC Educational Resources Information Center

    Hopson, Rodney; Miller, Peter; Lovelace, Temple S.

    2016-01-01

    Using a critical brokerage perspective to advance theoretical insights in the development of a community university partnership and understanding of the organizational embeddedness of a community empowerment agency in Pittsburgh, PA, USA, this article suggests that partnerships between American universities and communities are perfect vehicles for…

  3. Analyzing the thermionic reactor critical experiments. [thermal spectrum of uranium 235 core

    NASA Technical Reports Server (NTRS)

    Niederauer, G. F.

    1973-01-01

    The Thermionic Reactor Critical Experiments (TRCE) consisted of fast spectrum highly enriched U-235 cores reflected by different thicknesses of beryllium or beryllium oxide with a transition zone of stainless steel between the core and reflector. The mixed fast-thermal spectrum at the core reflector interface region poses a difficult neutron transport calculation. Calculations of TRCE using ENDF/B fast spectrum data and GATHER library thermal spectrum data agreed within about 1 percent for the multiplication factor and within 6 to 8 percent for the power peaks. Use of GAM library fast spectrum data yielded larger deviations. The results were obtained from DOT R Theta calculations with leakage cross sections, by region and by group, extracted from DOT RZ calculations. Delineation of the power peaks required extraordinarily fine mesh size at the core reflector interface.

  4. Critical Thinking in the University Curriculum--The Impact on Engineering Education

    ERIC Educational Resources Information Center

    Ahern, A.; O'Connor, T.; McRuairc, G.; McNamara, M.; O'Donnell, D.

    2012-01-01

    Critical thinking is a graduate attribute that many courses, including engineering courses, claim to produce in students. As a graduate attribute it is seen by academics as a particularly desirable outcome of student learning and is said by researchers to be a defining characteristic of university education. However, how critical thinking is…

  5. White Students at the Historically Black University: Toward Developing a Critical Consciousness

    ERIC Educational Resources Information Center

    Henry, Wilma J.; Closson, Rosemary B.

    2010-01-01

    The purpose of this article is to examine the potential of historically Black colleges and universities (HBCUs) to facilitate the development of a critical consciousness among their White students. It discusses philosophical views regarding the process of unveiling "Whiteness," including White critical studies and White identity development…

  6. Critical Discourse Analysis of Moderated Discussion Board of Virtual University of Pakistan

    ERIC Educational Resources Information Center

    Perveen, Ayesha

    2015-01-01

    The paper critically evaluated the discursive practices on the Moderated Discussion Board (MDB) of Virtual University of Pakistan (VUP). The paramount objective of the study was to conduct a critical discourse analysis (CDA) of the MDB on the Learning Management System (LMS) of VUP. For this purpose, the academic power relations of the students…

  7. Teaching and Learning Critical Reading with Transnational Texts at a Mexican University: An Emergentist Case Study

    ERIC Educational Resources Information Center

    Perales Escudero, Moises Damian

    2011-01-01

    This dissertation project examines the implementation of a critical reading intervention in a Mexican university, and the emergence of target critical reading processes in Mexican college-level EFL readers. It uses a Complexity Theory-inspired, qualitative methodology. Orienting the selection and design of materials is a deep view of culture that…

  8. Older Adult Education in a Maltese University of the Third Age: A Critical Perspective.

    ERIC Educational Resources Information Center

    Formosa, Marvin

    2000-01-01

    Research using Freire's critical pedagogy and critical educational gerontology revealed that a Maltese University of the Third Age uses traditional one-way models of educational practice that fail to engage learners in transformative learning. Overemphasis on adult participation neglects the question of the purpose of learning. (Contains 72…

  9. The problems of mass transfer and formation of deposits of corrosion products on fuel assemblies of a VVER-1200 reactor

    NASA Astrophysics Data System (ADS)

    Rodionov, Yu. A.; Kritskii, V. G.; Berezina, I. G.; Gavrilov, A. V.

    2014-03-01

    On the basis of examination of materials published both in Russia and abroad, as well as their own investigations, the authors explain the reasons for the occurrence of such effects as AOA (Axial Offset Anomalies) and an increase in the coolant pressure difference in the core of nuclear reactors of the VVER type. To detect the occurrence of the AOA effect, the authors suggest using the specific activity of 58Co in the coolant. In the VVER-1200 design the thermohydraulic regime for fuel assemblies in the first year of their service life involves slight boiling of the coolant in the upper part of the core, which may induce the occurrence of the AOA effect, intensification of corrosion of fuel claddings, and abnormal increase in deposition of corrosion products. Radiolysis of the water coolant in the boiling section (boiling in pores of deposits) may intensify not only general corrosion but also a localized (nodular) one. As a result of intensification of the corrosion processes and growth of deposits, deterioration of the radiation situation in the rooms of the primary circuit of a VVER-1200 reactor as compared to that at nuclear power plants equipped with reactors of the VVER-1000 type is possible. Recommendations for preventing the AOA effect at nuclear power plants with VVER-1200 reactors on the matter of the direction of further investigations are made.

  10. Neutronic assessment of stringer fuel assembly design for liquid-salt-cooledvery high temperature reactor (LS-VHTR).

    SciTech Connect

    Szakaly, F. J.; Kim, T. K.; Taiwo, T. A.

    2006-09-15

    Neutronic studies of 18-pin and 36-pin stringer fuel assemblies have been performed to ascertain that core design requirements for the Liquid-Salt Cooled Very High Temperature Reactor (LS-VHTR) can be met. Parametric studies were performed to determine core characteristics required to achieve a target core cycle length of 18 months and fuel discharge burnup greater than 100 GWd/t under the constraint that the uranium enrichment be less than 20% in order to support non-proliferation goals. The studies were done using the WIMS9 lattice code and the linear reactivity model to estimate the core reactivity balance, fuel composition, and discharge burnup. The results show that the design goals can be met using a 1-batch fuel management scheme, uranium enrichment of 15% and a fuel packing fraction of 30% or greater for the 36-pin stringer fuel assembly design.

  11. Neutronics, steady-state, and transient analyses for the Poland MARIA reactor for irradiation testing of LEU lead test fuel assemblies from CERCA : ANL independent verification results.

    SciTech Connect

    Garner, P. L.; Hanan, N. A.

    2011-06-07

    The MARIA reactor at the Institute of Atomic Energy (IAE) in Swierk (30 km SE of Warsaw) in the Republic of Poland is considering conversion from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel assemblies (FA). The FA design in MARIA is rather unique; a suitable LEU FA has never been designed or tested. IAE has contracted with CERCA (the fuel supply portion of AREVA in France) to supply 2 lead test assemblies (LTA). The LTAs will be irradiated in MARIA to burnup level of at least 40% for both LTAs and to 60% for one LTA. IAE may decide to purchase additional LEU FAs for a full core conversion after the test irradiation. The Reactor Safety Committee within IAE and the National Atomic Energy Agency in Poland (PAA) must approve the LTA irradiation process. The approval will be based, in part, on IAE submitting revisions to portions of the Safety Analysis Report (SAR) which are affected by the insertion of the LTAs. (A similar process will be required for the full core conversion to LEU fuel.) The analysis required was established during working meetings between Argonne National Laboratory (ANL) and IAE staff during August 2006, subsequent email correspondence, and subsequent staff visits. The analysis needs to consider the current high-enriched uranium (HEU) core and 4 core configurations containing 1 and 2 LEU LTAs in various core positions. Calculations have been performed at ANL in support of the LTA irradiation. These calculations are summarized in this report and include criticality, burn-up, neutronics parameters, steady-state thermal hydraulics, and postulated transients. These calculations have been performed at the request of the IAE staff, who are performing similar calculations to be used in their SAR amendment submittal to the PAA. The ANL analysis has been performed independently from that being performed by IAE and should only be used as one step in the verification process.

  12. Critical thinking, nurse education and universities: some thoughts on current issues and implications for nursing practice.

    PubMed

    Morrall, Peter; Goodman, Benny

    2013-09-01

    When in the latter part of the 20th century nurse 'training' in the UK left the old schools of nursing (based within the health delivery system) and entered universities, the promise was not just a change of focus from training to education but an embracement of 'higher' education. Specifically, nurses were to be exposed to the demands of thinking rather than just doing - and critical thinking at that. However, despite a history of critical perspectives informing nursing theory, that promise may be turning sour. The insidious saturation of the university system in bureaucracy and managerialism has, we argue, undermined critical thinking. A major funding restructuring of higher education in the UK, coinciding with public concern about the state of nursing practice, is undermining further the viability of critical thinking in nursing and potentially the acceptability of university education for nurses. Nevertheless, while critical thinking in universities has decayed, there is no obvious educational alternative that can provide this core attribute, one that is even more necessary to understand health and promote competent nursing practice in an increasingly complex and globalising world. We propose that nurse academics and their colleagues from many other academic and professional disciplines engage in collegiate 'moral action' to re-establish critical thinking in UK universities.

  13. The Kyoto Protocol: A business perspective

    SciTech Connect

    Malin, C.B.

    1998-01-19

    Governments have made a tentative start in responding to climate change. In marathon negotiating sessions that extended into an extra day Dec. 1--11 in Kyoto, Japan, representatives from more than 160 governments hammered out the Kyoto Protocol to the United Nations Framework Convention on Climate Change (FCCC). The protocol calls for developed countries to reduce emissions of greenhouse gases (GHGs) on averaged by 5.2% below 1990 levels by the years 2008--2012. Developing countries have no new obligations. The paper discusses the agreement, ratification, future questions, business role, and the challenge.

  14. SpRoUTS (Space Robot Universal Truss System): Reversible Robotic Assembly of Deployable Truss Structures of Reconfigurable Length

    NASA Technical Reports Server (NTRS)

    Jenett, Benjamin; Cellucci, Daniel; Cheung, Kenneth

    2015-01-01

    Automatic deployment of structures has been a focus of much academic and industrial work on infrastructure applications and robotics in general. This paper presents a robotic truss assembler designed for space applications - the Space Robot Universal Truss System (SpRoUTS) - that reversibly assembles a truss from a feedstock of hinged andflat-packed components, by folding the sides of each component up and locking onto the assembled structure. We describe the design and implementation of the robot and show that the assembled truss compares favorably with prior truss deployment systems.

  15. Correlations of Nucleate Boiling Heat Transfer and Critical Heat Flux for External Reactor Vessel Cooling

    SciTech Connect

    J. Yang; F. B. Cheung; J. L. Rempe; K. Y. Suh; S. B. Kim

    2005-07-01

    Four types of steady-state boiling experiments were conducted to investigate the efficacy of two distinctly different heat transfer enhancement methods for external reactor vessel cooling under severe accident conditions. One method involved the use of a thin vessel coating and the other involved the use of an enhanced insulation structure. By comparing the results obtained in the four types of experiments, the separate and integral effect of vessel coating and insulation structure were determined. Correlation equations were obtained for the nucleate boiling heat transfer and the critical heat flux. It was found that both enhancement methods were quite effective. Depending on the angular location, the local critical heat flux could be enhanced by 1.4 to 2.5 times using vessel coating alone whereas it could be enhanced by 1.8 to 3.0 times using an enhanced insulation structure alone. When both vessel coating and insulation structure were used simultaneously, the integral effect on the enhancement was found much less than the product of the two separate effects, indicating possible competing mechanisms (i.e., interference) between the two enhancement methods.

  16. Participation in the United States Department of Energy University Reactor Instrumentation Program. Final report, September 1990--August 1993

    SciTech Connect

    Mulder, R.U.; Benneche, P.E.; Hosticka, B.

    1993-10-01

    The University of Virginia Reactor Facility is an integral part of the Department of Mechanical, Aerospace and Nuclear Engineering and is used to support educational programs in engineering and science at the University of Virginia and at other area colleges and universities. The University of Virginia Research Reactor (UVAR) is the highest power (two megawatts thermal power) and one of the most utilized university research reactor in the mid-Atlantic states. A major objective of this facility is to support educational programs in the region. The University of Virginia has received support under the U.S. Department of Energy (DOE) University Reactor Instrumentation Program every year since 1990. The monies from this program have been used to purchase new equipment to replace outdated or inadequate safety-related instrumentation used in conjunction with reactor operations. This report documents the equipment purchased and the status of the installation and use of this equipment from September 1990 through August 1993. This report constitutes the final report for this project period.

  17. Assemblies with both target and fuel pins in an isotope-production reactor

    DOEpatents

    Cawley, W.E.; Omberg, R.P.

    1982-08-19

    A method is described for producing tritium in a fast breeder reactor cooled with liquid metal. Lithium target material is placed in pins adjacent to fuel pins in order to increase the tritium production rate.

  18. Measurement of the ^235mU Production Cross Section Using a Critical Assembly*

    NASA Astrophysics Data System (ADS)

    Macri, Robert; Authier, Nicolas; Becker, John; Belier, Gilbert; Bond, Evelyn; Bredeweg, Todd; Glover, S.; Meot, Vincent; Rundberg, Robert; Vieira, David; Wilhelmy, Jerry

    2006-10-01

    Measurements of the creation and destruction cross sections for actinide nuclei constitute an important experimental effort in support of Stockpile Stewardship. In this talk I will give a progress report on the effort to measure the production cross section of the ^235mU isomer integrated over a fission neutron spectrum. This ongoing experiment is fielded at CEA in Valduc, France, taking advantage of the CALIBAN critical assembly. This effort is performed in collaboration with LANL, LLNL, Bruyeres le Chatel, and Valduc staff. This experiment utilizes a technique to measure internal conversion electrons from the ^235mU isomer with the French BIII detector (Bruyeres le Chatel), and involves a substantial chemistry effort (LANL) to prepare targets for irradiation and counting, as well as to remove fission fragments after irradiation. Experimental techniques will be discussed and preliminary data presented. *Work performed under the auspices of the U.S. Department of Energy by Los Alamos National Laboratory (W-7405-ENG-36) and Lawrence Livermore National Laboratory (W-7405-ENG-48), and CEA-DAM under CEA-DAM NNSA-DOE agreement.

  19. Optical critical dimension metrology for directed self-assembly assisted contact hole shrink

    NASA Astrophysics Data System (ADS)

    Dixit, Dhairya; Green, Avery; Hosler, Erik R.; Kamineni, Vimal; Preil, Moshe E.; Keller, Nick; Race, Joseph; Chun, Jun Sung; O'Sullivan, Michael; Khare, Prasanna; Montgomery, Warren; Diebold, Alain C.

    2016-01-01

    Directed self-assembly (DSA) is a potential patterning solution for future generations of integrated circuits. Its main advantages are high pattern resolution (˜10 nm), high throughput, no requirement of high-resolution mask, and compatibility with standard fab-equipment and processes. The application of Mueller matrix (MM) spectroscopic ellipsometry-based scatterometry to optically characterize DSA patterned contact hole structures fabricated with phase-separated polystyrene-b-polymethylmethacrylate (PS-b-PMMA) is described. A regression-based approach is used to calculate the guide critical dimension (CD), DSA CD, height of the PS column, thicknesses of underlying layers, and contact edge roughness of the post PMMA etch DSA contact hole sample. Scanning electron microscopy and imaging analysis is conducted as a comparative metric for scatterometry. In addition, optical model-based simulations are used to investigate MM elements' sensitivity to various DSA-based contact hole structures, predict sensitivity to dimensional changes, and its limits to characterize DSA-induced defects, such as hole placement inaccuracy, missing vias, and profile inaccuracy of the PMMA cylinder.

  20. Climate change. Managing forests after Kyoto.

    PubMed

    Schulze, D E; Wirth, C; Heimann, M

    2000-09-22

    The Kyoto protocol aims to reduce carbon emissions into the atmosphere. Part of the strategy is the active management of terrestrial carbon sinks, principally through afforestation and reforestation. In their Perspective, Schulze et al. argue that the preservation of old-growth forests may have a larger positive effect on the carbon cycle than promotion of regrowth.

  1. Combined numerical and experimental investigations of local hydrodynamics and coolant flow mass transfer in Kvadrat-type fuel assemblies of PWR reactors with mixing grids

    NASA Astrophysics Data System (ADS)

    Dmitriev, S. M.; Samoilov, O. B.; Khrobostov, A. E.; Varentsov, A. V.; Dobrov, A. A.; Doronkov, D. V.; Sorokin, V. D.

    2014-08-01

    Results of research works on studying local hydrodynamics and mass transfer for coolant flow in the characteristic zones of PWR reactor fuel assemblies in case of using belts of mixing spacer grids are presented. The investigations were carried out on an aerodynamic rig using the admixture diffusion method (the tracer-gas method). Certain specific features pertinent to coolant flow in the fuel rod bundles of Kvadrat-type fuel assemblies were revealed during the experiments. The obtained study results were included in the database for verifying computation fluid dynamics computer codes and detailed cell-wise calculations of reactor cores with Kvadrat-type fuel assemblies. The obtained results can also be used for more exact determination of local coolant flow hydrodynamic and mass transfer characteristics in assessing thermal reliability of PWR reactor cores.

  2. BRAIN ACONITASE ACTIVITY IN SPONTANEOUSLY HYPERTENSIVE (SHR) AND WISTAR-KYOTO (WKY) RATS.

    EPA Science Inventory

    Animal models of susceptibility are critical for human health risk assessment. Previous studies indicate that spontaneously hypertensive (SHR) rats are more sensitive than Wistar-Kyoto (WKY) rats to the cholinesterase (ChE) inhibitors such as carbaryl and chlorpyrifos. This diffe...

  3. 239Pu Prompt Fission Neutron Spectra Impact on a Set of Criticality and Experimental Reactor Benchmarks

    NASA Astrophysics Data System (ADS)

    Peneliau, Y.; Litaize, O.; Archier, P.; De Saint Jean, C.

    2014-04-01

    A large set of nuclear data are investigated to improve the calculation predictions of the new neutron transport simulation codes. With the next generation of nuclear power plants (GEN IV projects), one expects to reduce the calculated uncertainties which are mainly coming from nuclear data and are still very important, before taking into account integral information in the adjustment process. In France, future nuclear power plant concepts will probably use MOX fuel, either in Sodium Fast Reactors or in Gas Cooled Fast Reactors. Consequently, the knowledge of 239Pu cross sections and other nuclear data is crucial issue in order to reduce these sources of uncertainty. The Prompt Fission Neutron Spectra (PFNS) for 239Pu are part of these relevant data (an IAEA working group is even dedicated to PFNS) and the work presented here deals with this particular topic. The main international data files (i.e. JEFF-3.1.1, ENDF/B-VII.0, JENDL-4.0, BRC-2009) have been considered and compared with two different spectra, coming from the works of Maslov and Kornilov respectively. The spectra are first compared by calculating their mathematical moments in order to characterize them. Then, a reference calculation using the whole JEFF-3.1.1 evaluation file is performed and compared with another calculation performed with a new evaluation file, in which the data block containing the fission spectra (MF=5, MT=18) is replaced by the investigated spectra (one for each evaluation). A set of benchmarks is used to analyze the effects of PFNS, covering criticality cases and mock-up cases in various neutron flux spectra (thermal, intermediate, and fast flux spectra). Data coming from many ICSBEP experiments are used (PU-SOL-THERM, PU-MET-FAST, PU-MET-INTER and PU-MET-MIXED) and French mock-up experiments are also investigated (EOLE for thermal neutron flux spectrum and MASURCA for fast neutron flux spectrum). This study shows that many experiments and neutron parameters are very sensitive to

  4. On the evaluation of pebble bed reactor critical experiments using the PEBBED code

    SciTech Connect

    Hans D. Gougar; R. Sonat Sen

    2001-10-01

    The PEBBED pebble bed reactor fuel management code under development at the Idaho National Laboratory is designed for rapid design and analysis of pebble bed high temperature reactors (PBRs). Embedded within the code are the THERMIX-KONVEK thermal fluid solver and the COMBINE-7 spectrum generation code for inline cross section homogenization. Because 1D symmetry can be found at each stage of core heterogeneity; spherical at TRISO and pebble levels, and cylindrical at the control rod and core levels, the 1-D transport capability of ANISN is assumed to be sufficient in most cases for generating flux solutions for cross section homogenization. Furthermore, it is fast enough to be executed during the analysis or the equilibrium core. Multi-group diffusion-based design codes such as PEBBED and VSOP are not expected to yield the accuracy and resolution of continuous energy Monte Carlo codes for evaluation of critical experiments. Nonetheless, if the preparation of multigroup cross sections can adequately capture the physics of the mixing of PBR fuel elements and leakage from the core, reasonable results may be obtained. In this paper, results of the application of PEBBED to two critical experiments (HTR Proteus and HTR-10) and associated computational models are presented. The embedded 1-D transport solver is shown to capture the double heterogeneity of the pebble fuel in unit cell calculations. Eigenvalue calculations of a whole core are more challenging, particularly if the boron concentration is uncertain. The sensitivity of major safety parameters to variations in modeling assumptions, however, is shown to be minimal. The embedded transport solver can also be used to obtain control rod worths but only with adjustment of the local spectrum. Results are compared to those of other codes as well as Core 4 of the HTR-Proteus experiment which contains partially inserted rods. They indicate the need for a reference solution to adjust the radius of the graphite in the

  5. Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies

    SciTech Connect

    Rothe, R.E.

    1997-12-01

    Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments.

  6. University Multilingualism: A Critical Narrative from the University of the Western Cape, South Africa

    ERIC Educational Resources Information Center

    Antia, Bassey E.

    2015-01-01

    This article offers a narrative of the University of the Western Cape, South Africa, from the prism of the duality of language as a co-modality (with people, protest, policy and practices) for constituting the institution in whole or in part and as a reflection of its co-modalities. For its framing, the narrative eclectically draws on language…

  7. Critical Heat Flux Experiments on the Reactor Vessel Wall Using 2-D Slice Test Section

    SciTech Connect

    Jeong, Yong Hoon; Chang, Soon Heung; Baek, Won-Pil

    2005-11-15

    The critical heat flux (CHF) on the reactor vessel outer wall was measured using the two-dimensional slice test section. The radius and the channel area of the test section were 2.5 m and 10 cm x 15 cm, respectively. The flow channel area and the heater width were smaller than those of the ULPU experiments, but the radius was greater than that of the ULPU. The CHF data under the inlet subcooling of 2 to 25 deg. C and the mass flux 0 to 300 kg/m{sup 2}.s had been acquired. The measured CHF value was generally slightly lower than that of the ULPU. The difference possibly comes from the difference of the test section material and the thickness. However, the general trend of CHF according to the mass flux was similar with that of the ULPU. The experimental CHF data were compared with the predicted values by SULTAN correlation. The SULTAN correlation predicted well this study's data only for the mass flux higher than 200 kg/m{sup 2}.s, and for the exit quality lower than 0.05. The local condition-based correlation was developed, and it showed good prediction capability for broad quality (-0.01 to 0.5) and mass flux (<300 kg/m{sup 2}.s) conditions with a root-mean-square error of 2.4%. There were increases in the CHF with trisodium phosphate-added water.

  8. Critical heat flux in natural convection cooled TRIGA reactors with hexagonal bundle

    SciTech Connect

    Yang, J.; Avery, M.; De Angelis, M.; Anderson, M.; Corradini, M.; Feldman, E. E.; Dunn, F. E.; Matos, J. E.

    2012-07-01

    A three-rod bundle Critical Heat Flux (CHF) study at low flow, low pressure, and natural convection condition has been conducted, simulating TRIGA reactors with the hexagonally configured core. The test section is a custom-made trefoil shape tube with three identical fuel pin heater rods located symmetrically inside. The full scale fuel rod is electrically heated with a chopped-cosine axial power profile. CHF experiments were carried out with the following conditions: inlet water subcooling from 30 K to 95 K; pressure from 110 kPa to 230 kPa; mass flux up to 150 kg/m{sup 2}s. About 50 CHF data points were collected and compared with a few existing CHF correlations whose application ranges are close to the testing conditions. Some tests were performed with the forced convection to identify the potential difference between the CHF under the natural convection and forced convection. The relevance of the CHF to test parameters is investigated. (authors)

  9. Criticality accident dosimetry systems: an international intercomparison at the SILENE reactor in 2002.

    PubMed

    Médioni, R; Asselineau, B; Verrey, B; Trompier, F; Itié, C; Texier, C; Muller, H; Pelcot, G; Clairand, I; Jacquet, X; Pochat, J L

    2004-01-01

    In criticality accident dosimetry and more generally for high dose measurements, special techniques are used to measure separately the gamma ray and neutron components of the dose. To improve these techniques and to check their dosimetry systems (physical and/or biological), a total of 60 laboratories from 29 countries (America, Europe, Asia) participated in an international intercomparaison, which took place in France from 9 to 21 June 2002, at the SILENE reactor in Valduc and at a pure gamma source in Fontenay-aux-Roses. This intercomparison was jointly organised by the IRSN and the CEA with the help of the NEA/OCDE and was partly supported by the European Communities. This paper describes the aim of this intercomparison, the techniques used by the participants and the two radiation sources and their characteristics. The experimental arrangements of the dosemeters for the irradiations in free air or on phantoms are given. Then the dosimetric quantities measured and reported by the participants are summarised, analysed and compared with the reference values. The present paper concerns only the physical dosimetry and essentially experiments performed on the SILENE facility. The results obtained with the biological dosimetry are published in two other papers of this issue.

  10. Conversion of the University of Virginia reactor to low-enrichment fuel

    SciTech Connect

    Rydin, R.A.; Freeman, D.W.; Fehr, M.K.

    1989-01-01

    The University of Virginia is using the LEOPARD-LINX-TWODB computational package to assist in converting the 2-MW(thermal) University of Virginia Reactor (UVAR) to low-enrichment uranium fuel (LEU). Recent efforts have been focused on designing an upgraded LEU replacement core. The UVAR is unique in that anywhere from 16 to 27 fuel elements have been used over the years in a variety of geometrical arrangements. However, a compact and fixed core arrangement offers significant operational and experimental advantages over past practice, including a higher and more temporally constant thermal flux. The authors have concentrated on relative burnup comparisons between representative 4 {times} 4, 4 {times} 5, and 5 {times} 5 cores using 18 curved-plant/element HEU (HEU-18) and 18 and 22 flat-plate/element LEU (LEU-18 and LEU-22) fuel. It is concluded that the UVAR should be supplied with LEU-22 fuel. The authors have also explored the reactivity and power-peaking effects of separately varying the reflector compositions on various reactor faces from light water to heavy water to graphite. Thermal-hydraulic behavior has also been analyzed with a combination of the PARET and THERHYD codes, which indicates the LEU cores will be acceptable with only small modifications in UVAR safety system settings.

  11. Self-Assembled Superparamagnetic Iron Oxide Nanoclusters for Universal Cell Labeling and MRI

    NASA Astrophysics Data System (ADS)

    Chen, Shuzhen; Zhang, Jun; Jiang, Shengwei; Lin, Gan; Luo, Bing; Yao, Huan; Lin, Yuchun; He, Chengyong; Liu, Gang; Lin, Zhongning

    2016-05-01

    Superparamagnetic iron oxide (SPIO) nanoparticles have been widely used in a variety of biomedical applications, especially as contrast agents for magnetic resonance imaging (MRI) and cell labeling. In this study, SPIO nanoparticles were stabilized with amphiphilic low molecular weight polyethylenimine (PEI) in an aqueous phase to form monodispersed nanocomposites with a controlled clustering structure. The iron-based nanoclusters with a size of 115.3 ± 40.23 nm showed excellent performance on cellular uptake and cell labeling in different types of cells, moreover, which could be tracked by MRI with high sensitivity. The SPIO nanoclusters presented negligible cytotoxicity in various types of cells as detected using MTS, LDH, and flow cytometry assays. Significantly, we found that ferritin protein played an essential role in protecting stress from SPIO nanoclusters. Taken together, the self-assembly of SPIO nanoclusters with good magnetic properties provides a safe and efficient method for universal cell labeling with noninvasive MRI monitoring capability.

  12. The NASA Constellation University Institutes Project: Thrust Chamber Assembly Virtual Institute

    NASA Technical Reports Server (NTRS)

    Tucker, P. Kevin; Rybak, Jeffry A.; Hulka, James R.; Jones, Gregg W.; Nesman, Tomas; West, Jeffrey S.

    2006-01-01

    This paper documents key aspects of the Constellation University Institutes Project (CUIP) Thrust Chamber Assembly (TCA) Virtual Institute (VI). Specifically, the paper details the TCA VI organizational and functional aspects relative to providing support for Constellation Systems. The TCA VI vision is put forth and discussed in detail. The vision provides the objective and approach for improving thrust chamber assembly design methodologies by replacing the current empirical tools with verified and validated CFD codes. The vision also sets out ignition, performance, thermal environments and combustion stability as focus areas where application of these improved tools is required. Flow physics and a study of the Space Shuttle Main Engine development program are used to conclude that the injector is the key to robust TCA design. Requirements are set out in terms of fidelity, robustness and demonstrated accuracy of the design tool. Lack of demonstrated accuracy is noted as the most significant obstacle to realizing the potential of CFD to be widely used as an injector design tool. A hierarchical decomposition process is outlined to facilitate the validation process. A simulation readiness level tool used to gauge progress toward the goal is described. Finally, there is a description of the current efforts in each focus area. The background of each focus area is discussed. The state of the art in each focus area is noted along with the TCA VI research focus in the area. Brief highlights of work in the area are also included.

  13. The assembly of galaxy halo within cosmic web: primordial anisotropy and its universality

    NASA Astrophysics Data System (ADS)

    Kang, Xi

    2015-08-01

    Observations in the past few years have found two interesting facts. One is that satellite galaxies are not randomly distributed around the central galaxies. The other is that galaxies spin are well correlated with the large scales structures, with dependence on galaxy type. Existed theoretical studies have difficult to explain the two observations. In fact they can be understood in the context of galaxy halo assembly with its relation to the cosmic web. Using N-body simulation, we investigate the assembly history of dark matter halo. It is found that satellite galaxy (or subhaloes) are accreted mostly along the cosmic filament, and the current anisotropy of satellites are already set at high-redshift universe at accretion. However, we find that for low-mass haloes ( or spiral galaxy) at z=0, the accretion of their massive progenitors are preferentially be perpendicular to the filament, not like the progenitors of elliptical galaxies. This finding well explains the puzzle that the observed spins of spiral galaxies are aligned with cosmic filament, but that of elliptical galaxies (or their short axes) are perpendicular to filament.

  14. Exposing Ideology within University Policies: A Critical Discourse Analysis of Faculty Hiring, Promotion and Remuneration Practices

    ERIC Educational Resources Information Center

    Uzuner-Smith, Sedef; Englander, Karen

    2015-01-01

    Using critical discourse analysis (CDA), this paper exposes the neoliberal ideology of the knowledge-based economy embedded within university policies, specifically those that regulate faculty hiring, promotion, and remuneration in two national contexts: Turkey and Mexico. The paper follows four stages of CDA: (1) focus upon a social wrong in its…

  15. Building Social Inclusion through Critical Arts-Based Pedagogies in University Classroom Communities

    ERIC Educational Resources Information Center

    Chappell, Sharon Verner; Chappell, Drew

    2016-01-01

    In humanities and education university classrooms, the authors facilitated counter-narrative arts-based inquiry projects in order to build critical thought and social inclusion. The first author examines public performance installations created by graduate students in elementary and bilingual education on needs-based and dignity-based rights of…

  16. Critical Resource Effects on America's Universities: What's behind the Growing Entrepreneurial Orientation?

    ERIC Educational Resources Information Center

    Powers, Joshua B.

    The purpose of this study was to investigate the effects of critical resource flows on technology transfer activity. The investigation focused on the impact on a university's licensing orientation of four sources of research and development (R&D) revenues: federal, state, industry, and institutional. By licensing orientation is meant the number of…

  17. International Students' Critical Thinking-Related Problem Areas: UK University Teachers' Perspectives

    ERIC Educational Resources Information Center

    Shaheen, Nisbah

    2016-01-01

    This qualitative study aims to understand the areas of international students' critical thinking-related initial difficulties, in order to facilitate their academic experiences in UK universities. Using a sample of 14 British teachers, the findings reveal that students from culturally and linguistically diverse traditions are very different in…

  18. Learning to "Walk the Talk": A Critical Tale of the Micropolitics at a Total Quality University.

    ERIC Educational Resources Information Center

    Wendt, Ronald F.

    1994-01-01

    Describes a case study of a major university implementing a total quality management (TQM) program. Finds that TQM hegemony has a potential to privilege passive, bounded, regimented, and efficiency-focused thinking over critical, self-reflective, strategic, and creative thinking; and to replace experimentation, the inherent value of ideas, and…

  19. Universal Design for Learning: Critical Need Areas for People with Learning Disabilities

    ERIC Educational Resources Information Center

    Strobel, Wendy; Arthanat, Sajay; Bauer, Stephen; Flagg, Jennifer

    2007-01-01

    The primary market research outlined in this paper was conducted by the Rehabilitation Engineering Research Center on Technology Transfer to identify critical technology needs for people with learning disabilities. Based on the research conducted, the underlying context of these technology needs is Universal Design for Learning (UDL). The paper…

  20. Critical Success Factors in Crafting Strategic Architecture for E-Learning at HP University

    ERIC Educational Resources Information Center

    Sharma, Kunal; Pandit, Pallvi; Pandit, Parul

    2011-01-01

    Purpose: The purpose of this paper is to outline the critical success factors for crafting a strategic architecture for e-learning at HP University. Design/methodology/approach: A descriptive survey type of research design was used. An empirical study was conducted on students enrolled with the International Centre for Distance and Open Learning…

  1. Increasing use of yellow colors in Kyoto

    NASA Astrophysics Data System (ADS)

    Akita, Munehira; Nara, Iwao

    2002-06-01

    Colors used for commercial signboards, displayed outdoors as well as indoors through windows, such as a store sign, an advertising sign, a sky sign, a poster, a placard, and a billboard were extensively surveyed in Kyoto City, Japan, in 1998. The survey showed that various kinds of yellow painted signs have increased rapidly and invaded a center area and suburbs of the city. Vivid yellow, what we called it the Y98 virus, is specially considered a color unpleasantly matched to the city image of Kyoto which was the capital of Japan for nearly 1000 years (794 to 1868) and is endowed with cultural and historic heritage. Discussions trying to find out what we could do to prevent the rapid spread of a big commercial display painted with vivid yellows what we called 'the Y98 virus' over the city will be summarized in a main text.

  2. Experimental studies of local coolant hydrodynamics using a scaled model of cassette-type fuel assembly of a KLT-40S reactor

    NASA Astrophysics Data System (ADS)

    Dmitriev, S. M.; Barinov, A. A.; Varentsov, A. V.; Doronkov, D. V.; Solntsev, D. N.; Khrobostov, A. E.

    2016-08-01

    The results of experimental studies of local hydrodynamic and mass exchange characteristics of the coolant flow behind the spacer grid in the fuel assembly of a KLT-40S reactor are presented. The experiments were aimed at the investigation of representative domains of the fuel assembly with three tracer injection regions. The studies were performed at the aerodynamic test facility using the tracer gas diffusion method. According to the theory of hydrodynamic similarity, the obtained experimental results can be transferred to full-scale coolant flow conditions in standard fuel assemblies. The analysis of the tracer concentration propagation made it possible to determine in detail the flow pattern and find the main regularities and specific features of the coolant flow behind the plate spacer grid of KLT-40S fuel assembly. The hydraulic resistance coefficient of the spacer grid was experimentally determined. The coefficients of mass exchange between cells for representative cells of the displacer region in the KLT-40S fuel assembly were calculated for the first time; these results are presented in the form of the "mixing matrix." The results of studies of local coolant flow hydrodynamics in the KLT-40S fuel assembly are used at AO Afrikantov OKBM for estimation of thermotechnical reliability of active cores for reactors of floating nuclear power stations. The experimental data on hydrodynamic and mass exchange characteristics are included in the database for verification of CDF codes and detailed cell-wise calculation of the active core for KLT-40S reactor installation. The results of these studies can be used at FSUE RFNC-VNIIEF for testing and verification of domestic three-dimensional hydrodynamic CFD codes ("Logos") that are applied for substantiation of newly designed reactor installations. Practical recommendations on the application of the obtained results in thermohydraulic calculations of the active core for the KLT-40S reactor will be worked out. Proposals

  3. Micro-Pocket Fission Detectors (MPFD) For Fuel Assembly Analysis

    SciTech Connect

    Troy Unruh; Michael Reichenberger; Phillip Ugorowski

    2013-09-01

    Neutron sensors capable of real-time measurement of thermal flux, fast flux, and temperature in a single miniaturized probe are needed in irradiation tests required to demonstrate the performance of candidate new fuels, and cladding materials. In-core ceramic-based miniature neutron detectors or “Micro-Pocket Fission Detectors” (MPFDs) have been studied at Kansas State University (KSU). The first MPFD prototypes were tested in various neutron fields at the KSU TRIGA research reactor with successful results. Currently, a United States Department of Energy-sponsored joint KSU/Idaho National Laboratory (INL) effort is underway to develop a high-temperature, high-pressure version of the MPFD using radiation-resistant, high temperature materials, which would be capable of withstanding irradiation test conditions in high performance material and test reactors (MTRs). Ultimately, this more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, existing and advanced reactor designs, high performance MTRs, and transient test reactors has the potential to lead to higher accuracy and resolution data from irradiation testing, more detailed core flux measurements and enhanced fuel assembly processing. Prior evaluations by KSU indicate that these sensors could also be used to monitor burn-up of nuclear fuel. If integrated into nuclear fuel assemblies, MPFDs offer several advantages to current spent fuel management systems.

  4. Feasibility assessment of burnup credit in the criticality analysis of shipping casks with boiling water reactor spent fuel

    SciTech Connect

    Broadhead, B.L.

    1991-08-01

    Considerable interest in the allowance of reactivity credit for the exposure history of power reactor fuel currently exists. This burnup credit'' issue has the potential to greatly reduce risk and cost when applied to the design and certification of spent fuel casks used for transportation and storage. Recently, analyses have demonstrated the technical feasibility and estimated the risk and economic incentives for allowing burnup credit in pressurized water reactor (PWR) spent fuel shipping cask applications. This report summarizes the extension of the previous PWR technical feasibility assessment to boiling water reactor (BWR) fuel. This feasibility analysis aims to apply simple methods that adequately characterize the time-dependent isotopic compositions of typical BWR fuel. An initial analysis objective was to identify a simple and reliable method for characterizing BWR spent fuel. Two different aspects of fuel characterization were considered:l first, the generation of burn- up dependent material interaction probabilities; second, the prediction of material inventories over time (depletion). After characterizing the spent fuel at various stages of exposure and decay, three dimensional (3-D) models for an infinite array of assemblies and, in several cases, infinite arrays of assemblies in a typical shipping cask basket were analyzed. Results for assemblies without a basket provide reactivity control requirements as a function of burnup and decay, while results including the basket allow assessment of typical basket configurations to provide sufficient reactivity control for spent BWR fuel. Resulting basket worths and reactivity trends over time are then evaluated to determine whether burnup credit is needed and feasible in BWR applications.

  5. U.S. Department of Energy University Reactor Sharing Program at the University of Florida. Final report for period August 15, 2000 - May 31, 2001

    SciTech Connect

    Vernetson, William G.

    2002-01-01

    Department of Energy Grant Number DE-FG02-96NE38152 was supplied to the University of Florida Training Reactor (UFTR) facility through the U.S. Department of Energy's University Reactor Sharing Program. The renewal proposal submitted in January 2000 originally requested over $73,000 to support various external educational institutions using the UFTR facilities in academic year 2000-01. The actual Reactor Sharing Grant was only in the amount of $40,000, all of which has been well used by the University of Florida as host institution to support various educational institutions in the use of our reactor and associated facilities as indicated in the proposal. These various educational institutions are located primarily within the State of Florida. However, when the 600-mile distance from Pensacola to Miami is considered, it is obvious that this Grant provides access to reactor utilization for a broad geographical region and a diverse set of user institutions serving over fourteen million inhabitants throughout the State of Florida and still others throughout the Southeast.

  6. Promoting University Students' Critical Thinking Skills through Peer Feedback Activity in an Online Discussion Forum

    ERIC Educational Resources Information Center

    Ekahitanond, Visara

    2013-01-01

    This study investigated the impact of the critical inquiry model through peer feedback strategies in an online environment on university students' critical thinking skills and examined their attitudes towards learning through the critical inquiry model and peer feedback strategies. Pre-and post-tests were employed to measure critical thinking…

  7. Maintaining a Critical Spectra within Monteburns for a Gas-Cooled Reactor Array by Way of Control Rod Manipulation

    DOE PAGES

    Adigun, Babatunde John; Fensin, Michael Lorne; Galloway, Jack D.; Trellue, Holly Renee

    2016-06-07

    Our burnup study examined the effect of a predicted critical control rod position on the nuclide predictability of several axial and radial locations within a 4×4 graphite moderated gas cooled reactor fuel cluster geometry. To achieve this, a control rod position estimator (CRPE) tool was developed within the framework of the linkage code Monteburns between the transport code MCNP and depletion code CINDER90, and four methodologies were proposed within the tool for maintaining criticality. Two of the proposed methods used an inverse multiplication approach - where the amount of fissile material in a set configuration is slowly altered until criticalitymore » is attained - in estimating the critical control rod position. Another method carried out several MCNP criticality calculations at different control rod positions, then used a linear fit to estimate the critical rod position. The final method used a second-order polynomial fit of several MCNP criticality calculations at different control rod positions to guess the critical rod position. The results showed that consistency in prediction of power densities as well as uranium and plutonium isotopics was mutual among methods within the CRPE tool that predicted critical position consistently well. Finall, while the CRPE tool is currently limited to manipulating a single control rod, future work could be geared toward implementing additional criticality search methodologies along with additional features.« less

  8. The Proper Splicing of RNAi Factors Is Critical for Pericentric Heterochromatin Assembly in Fission Yeast

    PubMed Central

    Kallgren, Scott P.; Moresco, James J.; Tu, Patricia G.; Yates, John R.; Nagy, Peter L.; Jia, Songtao

    2014-01-01

    Heterochromatin preferentially assembles at repetitive DNA elements, playing roles in transcriptional silencing, recombination suppression, and chromosome segregation. The RNAi machinery is required for heterochromatin assembly in a diverse range of organisms. In fission yeast, RNA splicing factors are also required for pericentric heterochromatin assembly, and a prevailing model is that splicing factors provide a platform for siRNA generation independently of their splicing activity. Here, by screening the fission yeast deletion library, we discovered four novel splicing factors that are required for pericentric heterochromatin assembly. Sequencing total cellular RNAs from the strongest of these mutants, cwf14Δ, showed intron retention in mRNAs of several RNAi factors. Moreover, introducing cDNA versions of RNAi factors significantly restored pericentric heterochromatin in splicing mutants. We also found that mutations of splicing factors resulted in defective telomeric heterochromatin assembly and mis-splicing the mRNA of shelterin component Tpz1, and that replacement of tpz1+ with its cDNA partially rescued heterochromatin defects at telomeres in splicing mutants. Thus, proper splicing of RNAi and shelterin factors contributes to heterochromatin assembly at pericentric regions and telomeres. PMID:24874881

  9. Characterization of Carbon Particulates in the Exit Flow of a Plasma Pyrolysis Assembly (PPA) Reactor

    NASA Technical Reports Server (NTRS)

    Green, Robert D.; Meyer, Marit E.; Agui, Juan H.; Berger, Gordon M.; Vijayakumar, R.; Abney, Morgan B.; Greenwood, Zachary

    2015-01-01

    The ISS presently recovers oxygen from crew respiration via a Carbon Dioxide Reduction Assembly (CRA) that utilizes the Sabatier chemical process to reduce captured carbon dioxide to methane (CH4) and water. In order to recover more of the hydrogen from the methane and increase oxygen recovery, NASA Marshall Space Flight Center (MSFC) is investigating a technology, plasma pyrolysis, to convert the methane to acetylene. The Plasma Pyrolysis Assembly (or PPA), achieves 90% or greater conversion efficiency, but a small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. In this work, we present the experimental results of an initial characterization of the carbon particulates in the PPA exit gas stream. We also present several potential options to remove these carbon particulates via carbon traps and filters to minimize resupply mass and required downtime for regeneration.

  10. REACTOR

    DOEpatents

    Roman, W.G.

    1961-06-27

    A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

  11. LOSS-OF-COOLANT ACIDENT SIMULATIONS IN THE NATIONAL RESEARCH UNIVERSAL REACTOR

    SciTech Connect

    Bennett, W D; Goodman, R L; Heaberlin, S W; Hesson, G M; Nealley, C; Kirg, L L; Marshall, R K; McNair, G W; Meitzler, W D; Neally, G W; Parchen, L J; Pilger, J P; Rausch, W N; Russcher, G E; Schreiber, R E; Wildung, N J; Wilson, C L

    1981-02-01

    Pressurized water reactor loss-of-coolant accident (LOCA) phenomena are being simulated with a series of experiments in the U-2 loop of the National Research Universal Reactor at Chalk River, Ontario, Canada. The first of these experiments includes up to 45 parametric thermal-hydraulic tests to establish the relationship among the reflood delay time of emergency coolant, the reflooding rate, and the resultant fuel rod cladding peak temperature. Subsequent experiments establish the fuel rod failure characteristics at selected peak cladding temperatures. Fuel rod cladding pressurization simulates high burnup fission gas pressure levels of modern PWRs. This document contains both an experiment overview of the LOCA simulation program and a review of the safety analyses performed by Pacific Northwest Laboratory (PNL) to define the expected operating conditions as well as to evaluate the worst case operating conditions. The primary intent of this document is to supply safety information required by the Chalk River Nuclear Laboratories (CRNL), to establish readiness to proceed from one test phase to the next and to establish the overall safety of the experiment. A hazards review summarizes safety issues, normal operation and three worst case accidents that have been addressed during the development of the experiment plan.

  12. Criticality Model Report

    SciTech Connect

    J.M. Scaglione

    2003-03-12

    The purpose of the ''Criticality Model Report'' is to validate the MCNP (CRWMS M&O 1998h) code's ability to accurately predict the effective neutron multiplication factor (k{sub eff}) for a range of conditions spanned by various critical configurations representative of the potential configurations commercial reactor assemblies stored in a waste package may take. Results of this work are an indication of the accuracy of MCNP for calculating eigenvalues, which will be used as input for criticality analyses for spent nuclear fuel (SNF) storage at the proposed Monitored Geologic Repository. The scope of this report is to document the development and validation of the criticality model. The scope of the criticality model is only applicable to commercial pressurized water reactor fuel. Valid ranges are established as part of the validation of the criticality model. This model activity follows the description in BSC (2002a).

  13. A universal molecular translator for non-nucleic acid targets that enables dynamic DNA assemblies and logic operations.

    PubMed

    Tang, Wei; Hu, Shichao; Wang, Huaming; Zhao, Yan; Li, Na; Liu, Feng

    2014-11-28

    A universal molecular translator based on the target-triggered DNA strand displacement was developed, which was able to convert various kinds of non-nucleic acid targets into a unique output DNA. This translation strategy was successfully applied in directing dynamic DNA assemblies and in realizing three-input logic gate operations. PMID:25295484

  14. Universal critical behavior of the two-dimensional Ising spin glass

    NASA Astrophysics Data System (ADS)

    Fernandez, L. A.; Marinari, E.; Martin-Mayor, V.; Parisi, G.; Ruiz-Lorenzo, J. J.

    2016-07-01

    We use finite size scaling to study Ising spin glasses in two spatial dimensions. The issue of universality is addressed by comparing discrete and continuous probability distributions for the quenched random couplings. The sophisticated temperature dependency of the scaling fields is identified as the major obstacle that has impeded a complete analysis. Once temperature is relinquished in favor of the correlation length as the basic variable, we obtain a reliable estimation of the anomalous dimension and of the thermal critical exponent. Universality among binary and Gaussian couplings is confirmed to a high numerical accuracy.

  15. Universal free-energy distribution in the critical point of a random Ising ferromagnet

    NASA Astrophysics Data System (ADS)

    Dotsenko, Victor; Holovatch, Yurij

    2014-11-01

    We discuss the non-self-averaging phenomena in the critical point of weakly disordered Ising ferromagnet. In terms of the renormalized replica Ginzburg-Landau Hamiltonian in dimensions D <4 , we derive an explicit expression for the probability distribution function (PDF) of the critical free-energy fluctuations. In particular, using known fixed-point values for the renormalized coupling parameters, we obtain the universal curve for such PDF in the dimension D =3 . It is demonstrated that this function is strongly asymmetric: its left tail is much slower than the right one.

  16. Final report on the University of Florida U.S. Department of Energy 1995--96 Reactor Sharing Program

    SciTech Connect

    Vernetson, W.G.

    1996-11-01

    Grant support has been well used by the University of Florida as host institution to support various educational institutions in the use of the reactor and associated facilities as indicated in the proposal. These various educational institutions are located primarily within Florida. However, when the 600-mile distance from Pensacola to Miami is considered, it is obvious that this Grant provides access to reactor utilization for a broad geographical region and a diverse set of user institutions serving over twelve million inhabitants throughout the State of Florida and still others throughout the nation. All users and uses were carefully screened to assure the usage was for educational institutions eligible for participation in the Reactor Sharing Program; where research activities were involved, care was taken to assure the research activities were not funded by grants for contract funding from outside sources. In some cases external grant funding is limited or is used up, in which case the Reactor Sharing Grant and frequent cost sharing by the UFTR facility and the University of Florida provide the necessary support to complete a project or to provide more results to make a complete project even better. In some cases this latter usage has aided renewal of external funding. The role of the Reactor Sharing Program, though relatively small in dollars, has been the single most important occurrence in assuring the rebirth and continued high utilization of the UFTR in a time when many better equipped and better placed facilities have ceased operations. Through dedicated and effective advertising efforts, the UFTR has seen nearly every four-year college and university in Florida make substantive use of the facility under the Reactor Sharing Program with many now regular users. Some have even been able to support usage from outside grants where the Reactor Sharing Grant has served as seed money; still others have been assisted when external grants were depleted.

  17. History of critical experiments at Pajarito Site

    SciTech Connect

    Paxton, H.C.

    1983-03-01

    This account describes critical and subcritical assemblies operated remotely at the Pajarito Canyon Site at the Los Alamos National Laboratory. Earliest assemblies, directed exclusively toward the nuclear weapons program, were for safety tests. Other weapon-related assemblies provided neutronic information to check detailed weapon calculations. Topsy, the first of these critical assemblies, was followed by Lady Godiva, Jezebel, Flattop, and ultimately Big Ten. As reactor programs came to Los Alamos, design studies and mockups were tested at Pajarito Site. For example, nearly all 16 Rover reactors intended for Nevada tests were preceded by zero-power mockups and proof tests at Pajarito Site. Expanded interest and capability led to fast-pulse assemblies, culminating in Godiva IV and Skua, and to the Kinglet and Sheba solution assemblies.

  18. Study of neutron physics: conversion of the University of Missouri-Rolla reactor to low-enriched fuel

    SciTech Connect

    Straka, M.; Covington, L.

    1987-01-01

    A detailed study of a fuel conversion (using LEU) has been undertaken for the University of Missouri-Rolla reactor. Results achieved with the available code package have been compared with the measured data whenever possible. The neutronic codes LEOPARD and 2DB-UM provided adequate results in most cases examined.

  19. Universal critical behavior and the transition temperature in (2+1)-flavor QCD

    SciTech Connect

    Schmidt, Christian

    2011-05-23

    We discuss the universal critical behavior in (2+1)-flavor QCD by analyzing lattice data from improved staggered fermions generated by the HotQCD Collaboration. We present recent results from two different lattice discretizations and various lattice spacings (N{sub {tau}} = 6,8,12) at fixed physical strange quark mass (m{sub s}) but varying light quark mass (m{sub l}). We find that the chiral order-parameter, i.e. the chiral condensate, shows the expected universal scaling that is associated with the critical point in the chiral limit already for light quark masses m{sub l}/m{sub s} < or approx. 0.05. From an analysis of the disconnected chiral susceptibility we estimate a preliminary value of the QCD transition temperature.

  20. Monte Carlo testing of new cross section data sets for thermal and intermediate highly enriched uranium critical assemblies

    SciTech Connect

    Weinman, J.P.

    1998-06-01

    The purpose of this study is to investigate the eigenvalue sensitivity to new {sup 235}U, hydrogen, and oxygen cross section data sets by comparing RACER Monte Carlo calculations for several thermal and intermediate spectrum critical experiments. The new {sup 235}U library (Version 107) was derived by L. Leal and H. Derrien by fitting differential experimental data for {sup 235}U while constraining the fit to match experimental capture and fission resonance integrals and Maxwellian averaged thermal K1 (v fission minus absorption). The new hydrogen library (Version 45) consists of the ENDF/B-VI release 3 data with a 332.0 mb 2,200 m/s cross section which replaces the value of 332.6 mb in the current library. The new oxygen library (Version 39) is based on a recent evaluation of {sup 16}O by E. Caro. Nineteen Oak Ridge and Rocky Flats thermal solution benchmark critical assemblies that span a range of hydrogen-to-{sup 235}U (H/U) concentrations (2,052 to 27.1) and above-thermal neutron leakage fractions (0.555 to 0.011) were analyzed. In addition, three intermediate spectrum critical assemblies (UH3-UR, UH3-NI, and HISS-HUG) were studied.

  1. C2cd3 is critical for centriolar distal appendage assembly and ciliary vesicle docking in mammals.

    PubMed

    Ye, Xuan; Zeng, Huiqing; Ning, Gang; Reiter, Jeremy F; Liu, Aimin

    2014-02-11

    The primary cilium plays critical roles in vertebrate development and physiology, but the mechanisms underlying its biogenesis remain poorly understood. We investigated the molecular function of C2 calcium-dependent domain containing 3 (C2cd3), an essential regulator of primary cilium biogenesis. We show that C2cd3 is localized to the centriolar satellites in a microtubule- and Pcm1-dependent manner; however, C2cd3 is dispensable for centriolar satellite integrity. C2cd3 is also localized to the distal ends of both mother and daughter centrioles and is required for the recruitment of five centriolar distal appendage proteins: Sclt1, Ccdc41, Cep89, Fbf1, and Cep164. Furthermore, loss of C2cd3 results in failure in the recruitment of Ttbk2 to the ciliary basal body as well as the removal of Cp110 from the ciliary basal body, two critical steps in initiating ciliogenesis. C2cd3 is also required for recruiting the intraflagellar transport proteins Ift88 and Ift52 to the mother centriole. Consistent with a role in distal appendage assembly, C2cd3 is essential for ciliary vesicle docking to the mother centriole. Our results suggest that C2cd3 regulates cilium biogenesis by promoting the assembly of centriolar distal appendages critical for docking ciliary vesicles and recruiting other essential ciliogenic proteins. PMID:24469809

  2. The University of the Third Age in the UK: An Interpretive and Critical Study

    ERIC Educational Resources Information Center

    Huang, Chin-Shan

    2006-01-01

    The idea of the University of the Third Age (U3A) in the UK was originated from France. However, the British formed their own model of U3As, which is different from that of French U3As. What are the reasons that the British U3As developed in a different way? The purpose of this article is to interpret and criticize in-depth the reasons why British…

  3. In Brief: Kyoto Protocol moves forward

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2004-10-01

    The Russian cabinet's 30 September endorsement of the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) likely clears the way for the treaty's ratification by that country's parliament and for its entry into force. The protocol enters into force when not less than 55 Parties to the Convention, including industrialized countries (so called ``Annex I Parties'') which accounted in total for at least 55 % of the total carbon dioxide emissions for 1990 from that group, officially have agreed to the treaty.

  4. Low enrichment fuel conversion for Iowa State University

    SciTech Connect

    Rohach, A.F.

    1992-08-01

    This report discusses the UTR-10 reactor at Iowa State University which went critical on low enriched uranium (LEU) fuel on August 14, 1991. However, subsequent to the criticality experiments the fuel plates started to discolor. In addition, roll pins used to lift the fuel assemblies were discovered to be cracked. It was determined that these problems were due to chemical agents in the primary coolant water. The roll pins were replaced by solid stainless steel pins. The primary coolant was replaced and the reactor is currently in operation. Surveillance specimens will be used to monitor any possible future discoloration. The high enriched fuel (HEU) is being prepared for eventual shipment to a high enriched fuel receiving facility.

  5. INTEGRAL BENCHMARKS AVAILABLE THROUGH THE INTERNATIONAL REACTOR PHYSICS EXPERIMENT EVALUATION PROJECT AND THE INTERNATIONAL CRITICALITY SAFETY BENCHMARK EVALUATION PROJECT

    SciTech Connect

    J. Blair Briggs; Lori Scott; Enrico Sartori; Yolanda Rugama

    2008-09-01

    Interest in high-quality integral benchmark data is increasing as efforts to quantify and reduce calculational uncertainties accelerate to meet the demands of next generation reactor and advanced fuel cycle concepts. The International Reactor Physics Experiment Evaluation Project (IRPhEP) and the International Criticality Safety Benchmark Evaluation Project (ICSBEP) continue to expand their efforts and broaden their scope to identify, evaluate, and provide integral benchmark data for method and data validation. Benchmark model specifications provided by these two projects are used heavily by the international reactor physics, nuclear data, and criticality safety communities. Thus far, 14 countries have contributed to the IRPhEP, and 20 have contributed to the ICSBEP. The status of the IRPhEP and ICSBEP is discussed in this paper, and the future of the two projects is outlined and discussed. Selected benchmarks that have been added to the IRPhEP and ICSBEP handbooks since PHYSOR’06 are highlighted, and the future of the two projects is discussed.

  6. Workshops on Enhancing the Impact of University Research on Critical Technologies. Final report

    SciTech Connect

    Eisenberger, Peter M.

    1998-12-01

    This proposal was designed to initiate a series of workshops in which participants from universities, government and industry would look strategically at selected areas of technological and societal importance. One of these workshops, dedicated to the discussion of how materials modeling can solve critical problems in industry, held at the Institute for Theoretical Physics, University of California Santa Barbara, January 7 through 11, 1996. ''Modeling of Industrial Materials: Connecting Atomistic and Continuum Scales'' was the first of a coordinated series of workshops, spanning over two years, being organized by a group of academic scientists at UCSB, MIT, and the Swiss Federal Institute of Technology Zurich (ETH). On the premise that materials research focused on technology also presents fundamental scientific challenges, the Workshop sought to identify specific areas of industrial needs and opportunities for materials modeling, interpreted as theory and simulation across all the relevant length scales, and to stimulate meaningful university-industry partnerships.

  7. Self-Assembled Superparamagnetic Iron Oxide Nanoclusters for Universal Cell Labeling and MRI.

    PubMed

    Chen, Shuzhen; Zhang, Jun; Jiang, Shengwei; Lin, Gan; Luo, Bing; Yao, Huan; Lin, Yuchun; He, Chengyong; Liu, Gang; Lin, Zhongning

    2016-12-01

    Superparamagnetic iron oxide (SPIO) nanoparticles have been widely used in a variety of biomedical applications, especially as contrast agents for magnetic resonance imaging (MRI) and cell labeling. In this study, SPIO nanoparticles were stabilized with amphiphilic low molecular weight polyethylenimine (PEI) in an aqueous phase to form monodispersed nanocomposites with a controlled clustering structure. The iron-based nanoclusters with a size of 115.3 ± 40.23 nm showed excellent performance on cellular uptake and cell labeling in different types of cells, moreover, which could be tracked by MRI with high sensitivity. The SPIO nanoclusters presented negligible cytotoxicity in various types of cells as detected using MTS, LDH, and flow cytometry assays. Significantly, we found that ferritin protein played an essential role in protecting stress from SPIO nanoclusters. Taken together, the self-assembly of SPIO nanoclusters with good magnetic properties provides a safe and efficient method for universal cell labeling with noninvasive MRI monitoring capability. PMID:27216601

  8. Universal Critical Power for Nonlinear Schroedinger Equations with a Symmetric Double Well Potential

    SciTech Connect

    Sacchetti, Andrea

    2009-11-06

    Here we consider stationary states for nonlinear Schroedinger equations in any spatial dimension n with symmetric double well potentials. These states may bifurcate as the strength of the nonlinear term increases and we observe two different pictures depending on the value of the nonlinearity power: a supercritical pitchfork bifurcation, and a subcritical pitchfork bifurcation with two asymmetric branches occurring as the result of saddle-node bifurcations. We show that in the semiclassical limit, or for a large barrier between the two wells, the first kind of bifurcation always occurs when the nonlinearity power is less than a critical value; in contrast, when the nonlinearity power is larger than such a critical value then we always observe the second scenario. The remarkable fact is that such a critical value is a universal constant in the sense that it does not depend on the shape of the double well potential and on the dimension n.

  9. Does Higher Education Foster Critical and Creative Learners? An Exploration of Two Universities in South Korea and the USA

    ERIC Educational Resources Information Center

    Lee, Hye-Jung; Lee, Jihyun; Makara, Kara A.; Fishman, Barry J.; Hong, Young-Il

    2015-01-01

    This paper describes two studies that explore students' beliefs about critical and creative learning at two universities, and considers the implications of those beliefs in comparison to the universities' stated education goals. One is a mixed method study of students at a top university in Korea, and the second is a comparative study…

  10. The Prompt Fission Neutron Spectrum: From Experiment to the Evaluated Data and its Impact on Critical Assemblies

    SciTech Connect

    Rising, Michael Evan

    2015-06-10

    After a brief introduction concerning nuclear data, prompt fission neutron spectrum (PFNS) evaluations and the limited PFNS covariance data in the ENDF/B-VII library, and the important fact that cross section uncertainties ~ PFNS uncertainties, the author presents background information on the PFNS (experimental data, theoretical models, data evaluation, uncertainty quantification) and discusses the impact on certain well-known critical assemblies with regard to integral quantities, sensitivity analysis, and uncertainty propagation. He sketches recent and ongoing research and concludes with some final thoughts.

  11. UNFINISHED BUSINESS: The Economics of The Kyoto Protocol

    SciTech Connect

    JA Edmonds; CN MacCracken; RD Sands; SH Kim

    2000-07-06

    The Kyoto Protocol to the Framework Convention on Climate Change (FCCC) was completed on the morning of December 11, 1997, following over two years of negotiations. The product of these deliberations is a complex and incomplete document knitting together the diversity of interests and perspectives represented by the more than 150 delegations. Because the document is complex, its implications are not immediately obvious. If it enters into force, the Kyoto Protocol will have far-reaching implications for all nations--both nations with obligations under the Protocol and those without obligations. National energy systems, and the world's energy system, could be forever changed. In this paper the authors develop an assessment of the energy and economic implications of achieving the goals of the Kyoto Protocol. They find that many of the details of the Protocol that remain to be worked out introduce critical uncertainties affecting the cost of compliance. There are also a variety of uncertainties that further complicate the analysis. These include future non-CO{sub 2} greenhouse gas emissions and the cost of their mitigation. Other uncertainties include the resolution of negotiations to establish rules for determining and allocating land-use emissions rights, mechanisms for Annex 1 trading, and participation by non-Annex 1 members in the Clean Development Mechanism. In addition, there are economic uncertainties, such as the behavior of Eastern Europe and the former Soviet Union in supplying emissions credits under Annex 1 trading. These uncertainties in turn could affect private sector investments in anticipation of the Protocol's entrance into force. The longer the nature of future obligations remains unclear, the less able decision makers will be to incorporate these rules into their investment decisions. They find that the cost of implementing the Protocol in the US can vary by more than an order of magnitude. The marginal cost could be as low as $26 per tonne of

  12. Designing a model for critical thinking development in AJA University of Medical Sciences

    PubMed Central

    MAFAKHERI LALEH, MAHYAR; MOHAMMADIMEHR, MOJGAN; ZARGAR BALAYE JAME, SANAZ

    2016-01-01

    Introduction: In the new concept of medical education, creativity development is an important goal. The aim of this research was to identify a model for developing critical thinking among students with the special focus on learning environment and learning style. Methods: This applied and cross-sectional study was conducted among all students studying in undergraduate and professional doctorate programs in Fall Semester 2013-2014 in AJA University of Medical Sciences (N=777). The sample consisted of 257 students selected based on the proportional stratified random sampling method. To collect data, three questionnaires including Critical Thinking, Perception of Learning Environment and Learning Style were employed. The data were analyzed using Pearson's correlation statistical test, and one-sample t-test. The Structural Equation Model (SEM) was used to test the research model. SPSS software, version 14 and the LISREL software were used for data analysis. Results: The results showed that students had significantly assessed the teaching-learning environment and two components of "perception of teachers" and "perception of emotional-psychological climate" at the desirable level (p<0.05). Also learning style and two components of "the study method" and "motivation for studying" were considered significantly desirable (p<0.05). The level of critical thinking among students in terms of components of "commitment", "creativity" and "cognitive maturity" was at the relatively desirable level (p<0.05). In addition, perception of the learning environment can impact the critical thinking through learning style. Conclusion: One of the factors which can significantly impact the quality improvement of the teaching and learning process in AJA University of Medical Sciences is to develop critical thinking among learners. This issue requires providing the proper situation for teaching and learning critical thinking in the educational environment. PMID:27795968

  13. Critical review of the reactor-safety study radiological health effects model. Final report

    SciTech Connect

    Cooper, D.W.; Evans, J.S.; Jacob, N.; Kase, K.R.; Maletskos, C.J.; Robertson, J.B.; Smith, D.G.

    1983-03-01

    This review of the radiological health effects models originally presented in the Reactor Safety Study (RSS) and currently used by the US Nuclear Regulatory Commission (NRC) was undertaken to assist the NRC in determining whether or not to revise the models and to aid in the revision, if undertaken. The models as presented in the RSS and as implemented in the CRAC (Calculations of Reactor Accident Consequences) Code are described and critiqued. The major elements analyzed are those concerning dosimetry, early effects, and late effects. The published comments on the models are summarized, as are the important findings since the publication of the RSS.

  14. Thoughts on Sensitivity Analysis and Uncertainty Propagation Methods with Respect to the Prompt Fission Neutron Spectrum Impact on Critical Assemblies

    SciTech Connect

    Rising, M.E.

    2015-01-15

    The prompt fission neutron spectrum (PFNS) uncertainties in the n+{sup 239}Pu fission reaction are used to study the impact on several fast critical assemblies modeled in the MCNP6.1 code. The newly developed sensitivity capability in MCNP6.1 is used to compute the k{sub eff} sensitivity coefficients with respect to the PFNS. In comparison, the covariance matrix given in the ENDF/B-VII.1 library is decomposed and randomly sampled realizations of the PFNS are propagated through the criticality calculation, preserving the PFNS covariance matrix. The information gathered from both approaches, including the overall k{sub eff} uncertainty, is statistically analyzed. Overall, the forward and backward approaches agree as expected. The results from a new method appear to be limited by the process used to evaluate the PFNS and is not necessarily a flaw of the method itself. Final thoughts and directions for future work are suggested.

  15. Critical residues in the PMEL/Pmel17 N-terminus direct the hierarchical assembly of melanosomal fibrils

    PubMed Central

    Leonhardt, Ralf M.; Vigneron, Nathalie; Hee, Jia Shee; Graham, Morven; Cresswell, Peter

    2013-01-01

    PMEL (also called Pmel17 or gp100) is a melanocyte/melanoma-specific glycoprotein that plays a critical role in melanosome development by forming a fibrillar amyloid matrix in the organelle for melanin deposition. Although ultimately not a component of mature fibrils, the PMEL N-terminal region (NTR) is essential for their formation. By mutational analysis we establish a high-resolution map of this domain in which sequence elements and functionally critical residues are assigned. We show that the NTR functions in cis to drive the aggregation of the downstream polycystic kidney disease (PKD) domain into a melanosomal core matrix. This is essential to promote in trans the stabilization and terminal proteolytic maturation of the repeat (RPT) domain–containing MαC units, precursors of the second fibrillogenic fragment. We conclude that during melanosome biogenesis the NTR controls the hierarchical assembly of melanosomal fibrils. PMID:23389629

  16. A high converter concept for fuel management with blanket fuel assemblies in boiling water reactors

    SciTech Connect

    Martinez-Frances, N.; Timm, W.; Rossbach, D.

    2012-07-01

    Studies on the natural Uranium saving and waste reduction potential of a multiple-plant BWR system were performed. The BWR High Converter system should enable a multiple recycling of MOX fuel in current BWR plants by introducing blanket fuel assemblies and burning Uranium and MOX fuel separately. The feasibility of Uranium cores with blankets and full-MOX cores with Plutonium qualities as low as 40% were studied. The power concentration due to blanket insertion is manageable with modern fuel and acceptable values for the thermal limits and reactivity coefficients were obtained. While challenges remain, full-MOX cores also complied with the main design criteria. The combination of Uranium and Plutonium burners in appropriate proportions could enable obtaining as much as 40% more energy out of Uranium ore. Moreover, a proper adjustment of blanket average stay and Plutonium qualities could lead to a system with nearly no Plutonium left for final disposal. The achievement of such goals with current light water technology makes the BWR HC concept an attractive option to improve the fuel cycle until Gen-IV designs are mature. (authors)

  17. Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review.

    PubMed

    Martínez-Huitle, Carlos A; Rodrigo, Manuel A; Sirés, Ignasi; Scialdone, Onofrio

    2015-12-23

    Traditional physicochemical and biological techniques, as well as advanced oxidation processes (AOPs), are often inadequate, ineffective, or expensive for industrial water reclamation. Within this context, the electrochemical technologies have found a niche where they can become dominant in the near future, especially for the abatement of biorefractory substances. In this critical review, some of the most promising electrochemical tools for the treatment of wastewater contaminated by organic pollutants are discussed in detail with the following goals: (1) to present the fundamental aspects of the selected processes; (2) to discuss the effect of both the main operating parameters and the reactor design on their performance; (3) to critically evaluate their advantages and disadvantages; and (4) to forecast the prospect of their utilization on an applicable scale by identifying the key points to be further investigated. The review is focused on the direct electrochemical oxidation, the indirect electrochemical oxidation mediated by electrogenerated active chlorine, and the coupling between anodic and cathodic processes. The last part of the review is devoted to the critical assessment of the reactors that can be used to put these technologies into practice. PMID:26654466

  18. Sensitivity Analysis of Fuel Centerline Temperatures in SuperCritical Water-cooled Reactors (SCWRs)

    NASA Astrophysics Data System (ADS)

    Abdalla, Ayman

    SuperCritical Water-cooled Reactors (SCWRs) are one of the six nuclear-reactor concepts currently being developed under the Generation-IV International Forum (GIF). A main advantage of SCW Nuclear Power Plants (NPPs) is that they offer higher thermal efficiencies compared to those of current conventional NPPs. Unlike today's conventional NPPs, which have thermal efficiencies between 30 - 35%, SCW NPPs will have thermal efficiencies within a range of 45 - 50%, owing to high operating temperatures and pressures (i.e., coolant temperatures as high as 625°C at 25 MPa pressure). The use of current fuel bundles with UO2 fuel at the high operating parameters of SCWRs may cause high fuel centerline temperatures, which could lead to fuel failure and fission gas release. Studies have shown that when the Variant-20 (43-element) fuel bundle was examined at SCW conditions, the fuel centerline temperature industry limit of 1850°C for UO2 and the sheath temperature design limit of 850°C might be exceeded. Therefore, new fuel-bundle designs, which comply with the design requirements, are required for future use in SCWRs. The main objective of this study to conduct a sensitivity analysis in order to identify the main factors that leads to fuel centerline temperature reduction. Therefore, a 54-element fuel bundle with smaller diameter of fuel elements compared to that of the 43-element bundle was designed and various nuclear fuels are examined for future use in a generic Pressure Tube (PT) SCWR. The 54-element bundle consists of 53 heated fuel elements with an outer diameter of 9.5 mm and one central unheated element of 20-mm outer diameter which contains burnable poison. The 54-element fuel bundle has an outer diameter of 103.45 mm, which is the same as the outer diameter of the 43-element fuel bundle. After developing the 54-element fuel bundle, one-dimensional heat-transfer analysis was conducted using MATLAB and NIST REFPROP programs. As a result, the Heat Transfer

  19. Thermodynamic signature of quantum criticality: universally diverging Grüneisen ratio

    NASA Astrophysics Data System (ADS)

    Zhu, Lijun

    2005-03-01

    At a generic quantum critical point where pressure acts as (or couples to) the zero-temperature control parameter, the Grüneisen ratio γ (the ratio of thermal expansion to specific heat) is divergent[1]. This property provides a novel probe to quantum criticality from thermodynamics. When scaling applies, γ˜1/T^x at the critical pressure p=pc, where the exponent x measures the scaling dimension of the most singular operator coupled to pressure; in the alternative limit T ->0 and p !=pc, γ= Gr/(p-pc), where Gr is a universal combination of critical exponents. The predicted divergence has been observed near the quantum critical points of several heavy fermion metals[2]. Analyses based on specific models relevant to these experiments are also presented. [1] L. Zhu, M. Garst, A. Rosch, and Q. Si, Phys. Rev. Lett. 91, 066404 (2003). [2] R. Küchler et al., Phys. Rev. Lett. 91, 066405 (2003); ibid. 93, 096402 (2004).

  20. Universal scaling for a quantum discontinuity critical point and quantum quenches

    NASA Astrophysics Data System (ADS)

    Suzuki, Sei; Dutta, Amit

    2015-08-01

    We introduce the notion of a quantum version of a discontinuity critical point (DCP) in the context of a first-order quantum phase transition referred to as a quantum DCP (QDCP). We evaluate the critical exponents associated with such a QDCP using the appropriate scaling relations focusing mainly on a QDCP that is located at the boundary between a gapped phase and a gapless critical line as observed in a spin-1/2 XXZ chain while we also touch upon the conventional Ising case. We then study temporal and spatial quenches in the vicinity of the QDCP associated with the XXZ chain and propose the scaling relation for the defect density and the residual energy characterized by associated critical exponents. These predictions are numerically verified for quenches of the XXZ chain to the QDCP (or across it), thereby establishing the existence of a Kibble-Zurek scaling for such quenches given in terms of appropriate critical exponents. Finally, in the Appendix we consider a generic situation which reduces to the case when the QDCP separates two gapped phases and also to that occurring in the XXZ chain, and present detail analysis of the universality and scaling relations concerning quantum quenches.

  1. Georgia Tech Studies of Sub-Critical Advanced Burner Reactors with a D-T Fusion Tokamak Neutron Source for the Transmutation of Spent Nuclear Fuel

    NASA Astrophysics Data System (ADS)

    Stacey, W. M.

    2009-09-01

    The possibility that a tokamak D-T fusion neutron source, based on ITER physics and technology, could be used to drive sub-critical, fast-spectrum nuclear reactors fueled with the transuranics (TRU) in spent nuclear fuel discharged from conventional nuclear reactors has been investigated at Georgia Tech in a series of studies which are summarized in this paper. It is found that sub-critical operation of such fast transmutation reactors is advantageous in allowing longer fuel residence time, hence greater TRU burnup between fuel reprocessing stages, and in allowing higher TRU loading without compromising safety, relative to what could be achieved in a similar critical transmutation reactor. The required plasma and fusion technology operating parameter range of the fusion neutron source is generally within the anticipated operational range of ITER. The implications of these results for fusion development policy, if they hold up under more extensive and detailed analysis, is that a D-T fusion tokamak neutron source for a sub-critical transmutation reactor, built on the basis of the ITER operating experience, could possibly be a logical next step after ITER on the path to fusion electrical power reactors. At the same time, such an application would allow fusion to contribute to meeting the nation's energy needs at an earlier stage by helping to close the fission reactor nuclear fuel cycle.

  2. Studying the vibration and random hydrodynamic loads on the fuel rods bundles in the fuel assemblies of the reactor installations used at nuclear power stations equipped with VVER reactors

    NASA Astrophysics Data System (ADS)

    Solonin, V. I.; Perevezentsev, V. V.

    2012-05-01

    Random hydrodynamic loads causing vibration of fuel rod bundles in a turbulent flow of coolant are obtained from the results of pressure pulsation measurements carried out over the perimeter of the external row of fuel rods in the bundle of a full-scale mockup of a fuel assembly used in a second-generation VVER-440 reactor. It is shown that the turbulent flow structure is a factor determining the parameters of random hydrodynamic loads and the vibration of fuel rod bundles excited by these loads. The results from a calculation of random hydrodynamic loads are used for estimating the vibration levels of fuel rod bundles used in prospective designs of fuel assemblies for VVER reactors.

  3. The National Criticality Experiments Research Center at the Device Assembly Facility, Nevada National Security Site: Status and Capabilities, Summary Report

    SciTech Connect

    S. Bragg-Sitton; J. Bess; J. Werner

    2011-09-01

    The National Criticality Experiments Research Center (NCERC) was officially opened on August 29, 2011. Located within the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS), the NCERC has become a consolidation facility within the United States for critical configuration testing, particularly those involving highly enriched uranium (HEU). The DAF is a Department of Energy (DOE) owned facility that is operated by the National Nuclear Security Agency/Nevada Site Office (NNSA/NSO). User laboratories include the Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL). Personnel bring their home lab qualifications and procedures with them to the DAF, such that non-site specific training need not be repeated to conduct work at DAF. The NNSS Management and Operating contractor is National Security Technologies, LLC (NSTec) and the NNSS Safeguards and Security contractor is Wackenhut Services. The complete report provides an overview and status of the available laboratories and test bays at NCERC, available test materials and test support configurations, and test requirements and limitations for performing sub-critical and critical tests. The current summary provides a brief summary of the facility status and the method by which experiments may be introduced to NCERC.

  4. Universal Fermi liquid crossover and quantum criticality in a mesoscopic system.

    PubMed

    Keller, A J; Peeters, L; Moca, C P; Weymann, I; Mahalu, D; Umansky, V; Zaránd, G; Goldhaber-Gordon, D

    2015-10-01

    Quantum critical systems derive their finite-temperature properties from the influence of a zero-temperature quantum phase transition. The paradigm is essential for understanding unconventional high-Tc superconductors and the non-Fermi liquid properties of heavy fermion compounds. However, the microscopic origins of quantum phase transitions in complex materials are often debated. Here we demonstrate experimentally, with support from numerical renormalization group calculations, a universal crossover from quantum critical non-Fermi liquid behaviour to distinct Fermi liquid ground states in a highly controllable quantum dot device. Our device realizes the non-Fermi liquid two-channel Kondo state, based on a spin-1/2 impurity exchange-coupled equally to two independent electronic reservoirs. On detuning the exchange couplings we observe the Fermi liquid scale T*, at energies below which the spin is screened conventionally by the more strongly coupled channel. We extract a quadratic dependence of T* on gate voltage close to criticality, and validate an asymptotically exact description of the universal crossover between strongly correlated non-Fermi liquid and Fermi liquid states. PMID:26450057

  5. Noninvasive Reactor Imaging Using Cosmic-Ray Muons

    NASA Astrophysics Data System (ADS)

    Miyadera, H.; Fujita, K.; Karino, Y.; Kume, N.; Nakayama, K.; Sano, Y.; Sugita, T.; Yoshioka, K.; Morris, C. L.; Bacon, J. D.; Borozdin, K. N.; Perry, J. O.; Mizokami, S.; Otsuka, Y.; Yamada, D.

    2015-10-01

    Cosmic-ray-muon imaging is proposed to assess the damages to the Fukushima Daiichi reactors. Simulation studies showed capability of muon imaging to reveal the core conditions.The muon-imaging technique was demonstrated at Toshiba Nuclear Critical Assembly, where the uranium-dioxide fuel assembly was imaged with 3-cm spatial resolution after 1 month of measurement.

  6. Reactor Physics and Criticality Benchmark Evaluations for Advanced Nuclear Fuel, Progress Report for Work through August 31, 2002, First Annual/4th Quarterly Report

    SciTech Connect

    Anderson, William J.; Ake, Timothy N.; Punatar, Mahendra; Pitts, Michelle L.; Harms, Gary A.; Rearden, Bradley T.; Parks, Cecil V.; Tulenko, James S.; Dugan, Edward; Smith, Robert M.

    2002-09-23

    OAK B204 The objective of this Nuclear Energy Research Initiative (NERI) project is to design, perform, and analyze critical benchmark experiments for validating reactor physics methods and models for fuel enrichments greater than 5-wt% 235U. These experiments will also provide additional information for application to the criticality-safety bases for commercial fuel facilities handling greater than 5-wt% 235U fuel. These experiments are designed as reactor physics benchmarks, to include measurements of critical boron concentration, burnable absorber worth, relative pin powers, and relative average powers.The first year focused primarily on designing the experiments using available fuel, preparing the necessary plans, procedures and authorization basis for performing the experiments, and preparing for the transportation, receipt and storage of the Pathfinder fuel currently stored at Pennsylvania State University.Framatome ANP, Inc. leads the project with the collaboration of Oak Ridge National Laboratory (ORNL), Sandia National Laboratories (SNL), and the University of Florida (UF). The project is organized into 5 tasks:Task 1: Framatome ANP, Inc., ORNL, and SNL will design the specific experiments, establish the safety authorization, and obtain approvals to perform these experiments at the SNL facility. ORNL will apply their sensitivity/uncertainty methodology to verify the need for particular experiments and the parameters that these experiments need to explore.Task 2: Framatome ANP, Inc., ORNL, and UF will analyze the proposed experiments using a variety of reactor-physics methods employed in the nuclear industry. These analyses will support the operation of the experiments by predicting the expected experimental values for the criticality and physics parameters.Task 3: This task encompasses the experiments to be performed. The Pathfinder fuel will be transported from Penn State to SNL for use in the experiments. The experiments will be performed and the

  7. WESTINGHOUSE 17X17 MOX PWR ASSEMBLY - WASTE PACKAGE CRITICALITY ANALYSIS (SCPB: N/A)

    SciTech Connect

    J.W. Davis

    1996-07-15

    This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development Department (WPDD) to compare the criticality potential of Westinghouse 17 x 17 mixed oxide (MOX) PWR fuel with the Design Basis spent nuclear fuel (SNF) analyzed previously (Ref. 5.1, 5.2). The basis of comparison will be the conceptual design Multi-Purpose Canister (MPC) PWR waste package concepts. The objectives of this evaluation are to show that the criticality potential of the MOX fuel is equal to or lower than the DBF or, if necessary, indicate what additional measures are required to make it so.

  8. Filtered fast neutron irradiation system using Texas A&M University Nuclear Science Center Reactor

    NASA Astrophysics Data System (ADS)

    Jang, S. Y.; Kim, C. H.; Reece, W. D.; Braby, L. A.

    2004-09-01

    A heavily filtered fast neutron irradiation system (FNIS) was developed for a variety of applications, including the study of long-term health effects of fast neutrons by evaluating the biological mechanisms of damage in cultured cells and living animals such as rats or mice. This irradiation system includes an exposure cave made with a lead-bismuth alloy, a cave positioning system, a gamma and neutron monitoring system, a sample transfer system, and interchangeable filters. This system was installed in the irradiation cell of the Texas A&M University Nuclear Science Center Reactor (NSCR). For a realistic modeling of the NSCR, the irradiation cell, and the FNIS, this study used the Monte Carlo N-Particle (MCNP) code and a set of high-temperature ENDF/B-VI continuous neutron cross-section data. Sensitivity analysis was performed to find the characteristics of the FNIS as a function of the thickness of the lead-bismuth alloy. A paired ion chamber system was constructed with a tissue-equivalent plastic (A-150) and propane gas for total dose monitoring and with graphite and argon for gamma dose monitoring. This study, in addition, tested the Monte Carlo modeling of the FNIS system, as well as the performance of the system by comparing the calculated results with experimental measurements using activation foils and paired ion chambers.

  9. Production of 37Ar in The University of Texas TRIGA reactor facility

    SciTech Connect

    Egnatuk, Christine M.; Lowrey, Justin; Biegalski, S.; Bowyer, Ted W.; Haas, Derek A.; Orrell, John L.; Woods, Vincent T.; Keillor, Martin E.

    2011-06-19

    The detection of {sup 37}Ar is important for on-site inspections for the Comprehensive Nuclear-Test-Ban Treaty monitoring. In an underground nuclear explosion this radionuclide is produced by {sup 40}Ca(n,{alpha}){sup 37}Ar reaction in surrounding soil and rock. With a half-life of 35 days, {sup 37}Ar provides a signal useful for confirming the location of an underground nuclear event. An ultra-low-background proportional counter developed by Pacific Northwest National Laboratory is used to detect {sup 37}Ar, which decays via electron capture. The irradiation of Ar gas at natural enrichment in the 3L facility within the Mark II TRIGA reactor facility at The University of Texas at Austin provides a source of {sup 37}Ar for the calibration of the detector. The {sup 41}Ar activity is measured by the gamma activity using an HPGe detector after the sample is removed from the core. Using the {sup 41}Ar/{sup 37}Ar production ratio and the {sup 41}Ar activity, the amount of {sup 37}Ar created is calculated. The {sup 41}Ar decays quickly (half-life of 109.34 minutes) leaving a radioactive sample of high purity {sup 37}Ar and only trace levels of {sup 39}Ar.

  10. Reactor

    DOEpatents

    Evans, Robert M.

    1976-10-05

    1. A neutronic reactor having a moderator, coolant tubes traversing the moderator from an inlet end to an outlet end, bodies of material fissionable by neutrons of thermal energy disposed within the coolant tubes, and means for circulating water through said coolant tubes characterized by the improved construction wherein the coolant tubes are constructed of aluminum having an outer diameter of 1.729 inches and a wall thickness of 0.059 inch, and the means for circulating a liquid coolant through the tubes includes a source of water at a pressure of approximately 350 pounds per square inch connected to the inlet end of the tubes, and said construction including a pressure reducing orifice disposed at the inlet ends of the tubes reducing the pressure of the water by approximately 150 pounds per square inch.

  11. Optimization study for an epithermal neutron beam for boron neutron capture therapy at the University of Virginia Research Reactor

    SciTech Connect

    Burns, T.D. Jr.

    1995-05-01

    The non-surgical brain cancer treatment modality, Boron Neutron Capture Therapy (BNCT), requires the use of an epithermal neutron beam. This purpose of this thesis was to design an epithermal neutron beam at the University of Virginia Research Reactor (UVAR) suitable for BNCT applications. A suitable epithermal neutron beam for BNCT must have minimal fast neutron and gamma radiation contamination, and yet retain an appreciable intensity. The low power of the UVAR core makes reaching a balance between beam quality and intensity a very challenging design endeavor. The MCNP monte carlo neutron transport code was used to develop an equivalent core radiation source, and to perform the subsequent neutron transport calculations necessary for beam model analysis and development. The code accuracy was validated by benchmarking output against experimental criticality measurements. An epithermal beam was designed for the UVAR, with performance characteristics comparable to beams at facilities with cores of higher power. The epithermal neutron intensity of this beam is 2.2 {times} 10{sup 8} n/cm{sup 2} {center_dot} s. The fast neutron and gamma radiation KERMA factors are 10 {times} 10{sup {minus}11}cGy{center_dot}cm{sup 2}/n{sub epi} and 20 {times} 10{sup {minus}11} cGy{center_dot}cm{sup 2}/n{sub epi}, respectively, and the current-to-flux ratio is 0.85. This thesis has shown that the UVAR has the capability to provide BNCT treatments, however the performance characteristics of the final beam of this study were limited by the low core power.

  12. The ENEA criticality accident dosimetry system: a contribution to the 2002 international intercomparison at the SILENE reactor.

    PubMed

    Gualdrini, G; Bedogni, R; Fantuzzi, E; Mariotti, F

    2004-01-01

    The present paper summarises the activity carried out at the ENEA Radiation Protection Institute for updating the methodologies employed for the evaluation of the neutron and photon dose to the exposed workers in case of a criticality accident, in the framework of the 'International Intercomparison of Criticality Accident Dosimetry Systems' (Silène reactor, IRSN-CEA-Valduc June 2002). The evaluation of the neutron spectra and the neutron dosimetric quantities relies on activation detectors and on unfolding algorithms. Thermoluminescent detectors are employed for the gamma dose measurement. The work is aimed at accurately characterising the measurement system and, at the same time, testing the algorithms. Useful spectral information were included, based on Monte Carlo simulations, to take into account the potential accident scenarios of practical interest. All along this exercise intercomparison a particular attention was devoted to the 'traceability' of all the experimental and computational parameters and therefore, aimed at an easy treatment by the user.

  13. Development of a One-Dimensional Small-Angle Neutron Scattering Instrument at the University of Illinois TRIGA Reactor Laboratory

    NASA Astrophysics Data System (ADS)

    Monti, D. A.; Guillermo, N. R.; Hulin, M. J.; Heuser, B. J.; Toreja, A.; Moschetti, T. L.

    1996-03-01

    A small-angle neutron scattering instrument with slit-smeared geometry (1-D SANS) has been constructed at the University of Illinois 1.5 MWatt TRIGA reactor. This facility falls under the general heading of "low-flux research reactors" which typically are not used for neutron scattering research. Low-flux reactors can support neutron scattering research under certain conditions, however. 1-D SANS using elastically-bent crystal optics is one such example [Popovici, et al. (1995). J. Phys. Chem. Solids 56, 1425-1431]. Our instrument uses a pyrolytic graphite pre-monochromator and two elastically-bent Si wafers, all in a (+,+,-) configuration. Instrumental performance including low-angle resolution, on-sample intensity, resolution variability, and cross-section measurement capability will be presented.

  14. Critical Issues Facing America's Community Colleges: A Summary of the Community Colleges Futures Assembly 2006

    ERIC Educational Resources Information Center

    Campbell, Dale F.; Basham, Matthew J.

    2007-01-01

    Three focus groups consisting of 42 board of trustee members, community college presidents, senior administrators, and faculty members developed critical issues facing community colleges with respect to instructional planning and services; planning, governance, finance; and workforce development. Thereafter, the delegation of more than 200 voted…

  15. Monte Carlo cross section testing for thermal and intermediate {sup 235}U/{sup 238}U critical assemblies, ENDF/B-V vs ENDF/B-VI

    SciTech Connect

    Weinman, J.P.

    1997-06-01

    The purpose of this study is to investigate the eigenvalue sensitivity to changes in ENDF/B-V and ENDF/B-VI cross section data sets by comparing RACER vectorized Monte Carlo calculations for several thermal and intermediate spectrum critical experiments. Nineteen Oak Ridge and Rocky Flats thermal solution benchmark critical assemblies that span a range of hydrogen-to-{sup 235}U (H/U) concentrations (2052 to 27.1) and above-thermal neutron leakage fractions (0.555 to 0.011) were analyzed. In addition, three intermediate spectrum critical assemblies (UH3-UR, UH3-NI, and HISS-HUG) were studied.

  16. Conversion Analyses for the VR-1 Reactor, part I and II.

    SciTech Connect

    Hannan, N. A.; Matos, J. E.; Stillman, J. A.; Olson, A. P.; Garner, P.L.

    2005-11-14

    At the request of the Czech Technical University (CTU) in Prague, ANL has performed independent verification calculations using the MCNP Monte Carlo code for three core configurations of the VR-1 reactor: a current core configuration B1 with HEU (36%) IRT-3M fuel assemblies and planned core configurations C1 and C2 with LEU (19.7%) IRT-4M fuel assemblies. Details of these configurations were provided to ANL by CTU. For core configuration B1, criticality calculations were performed for two sets of control rod positions provided to ANL by CTU. Fore core configurations C1 and C2, criticality calculations were done for cases with all control rods at the top positions, all control rods at the bottom positions, and two critical states of the reactor for different control rod positions. In addition, sensitivity studies for variation of the {sup 235}U mass in each fuel assembly and variation of the fuel meat and cladding thicknesses in each of the fuel tubes were doe for the C1 core configuration. The reactivity worth of the individual control rods was calculated for the B1, C1, and C2 core configurations. Finally, the reactivity feedback coefficients, the prompt neutron lifetime, and the total effective delay neutron fraction were calculated for each of the three cores.

  17. Universal Pulse Oximetry Screening for Early Detection of Critical Congenital Heart Disease

    PubMed Central

    Kumar, Praveen

    2016-01-01

    Critical congenital heart disease (CCHD) is a major cause of infant death and morbidity worldwide. An early diagnosis and timely intervention can significantly reduce the likelihood of an adverse outcome. However, studies from the United States and other developed countries have shown that as many as 30%–50% of infants with CCHD are discharged after birth without being identified. This diagnostic gap is likely to be even higher in low-resource countries. Several large randomized trials have shown that the use of universal pulse-oximetry screening (POS) at the time of discharge from birth hospital can help in early diagnosis of these infants. The objective of this review is to share data to show that the use of POS for early detection of CCHD meets the criteria necessary for inclusion to the universal newborn screening panel and could be adopted worldwide. PMID:27279759

  18. LBE water interaction in sub-critical reactors: First experimental and modelling results

    NASA Astrophysics Data System (ADS)

    Ciampichetti, A.; Agostini, P.; Benamati, G.; Bandini, G.; Pellini, D.; Forgione, N.; Oriolo, F.; Ambrosini, W.

    2008-06-01

    This paper concerns the study of the phenomena involved in the interaction between LBE and pressurised water which could occur in some hypothetical accidents in accelerator driven system type reactors. The LIFUS 5 facility was designed and built at ENEA-Brasimone to reproduce this kind of interaction in a wide range of conditions. The first test of the experimental program was carried out injecting water at 70 bar and 235 °C in a reaction vessel containing LBE at 1 bar and 350 °C. A pressurisation up to 80 bar was observed in the test section during the considered transient. The SIMMER III code was used to simulate the performed test. The calculated data agree in a satisfactory way with the experimental results giving confidence in the possibility to use this code for safety analyses of heavy liquid metal cooled reactors.

  19. Investigation of applications for high-power, self-critical fissioning uranium plasma reactors

    NASA Technical Reports Server (NTRS)

    Rodgers, R. J.; Latham, T. S.; Krascella, N. L.

    1976-01-01

    Analytical studies were conducted to investigate potentially attractive applications for gaseous nuclear cavity reactors fueled by uranium hexafluoride and its decomposition products at temperatures of 2000 to 6000 K and total pressures of a few hundred atmospheres. Approximate operating conditions and performance levels for a class of nuclear reactors in which fission energy removal is accomplished principally by radiant heat transfer from the high temperature gaseous nuclear fuel to surrounding absorbing media were determined. The results show the radiant energy deposited in the absorbing media may be efficiently utilized in energy conversion system applications which include (1) a primary energy source for high thrust, high specific impulse space propulsion, (2) an energy source for highly efficient generation of electricity, and (3) a source of high intensity photon flux for heating working fluid gases for hydrogen production or MHD power extraction.

  20. Universal conductivity in a two-dimensional superfluid-to-insulator quantum critical system.

    PubMed

    Chen, Kun; Liu, Longxiang; Deng, Youjin; Pollet, Lode; Prokof'ev, Nikolay

    2014-01-24

    We compute the universal conductivity of the (2+1)-dimensional XY universality class, which is realized for a superfluid-to-Mott insulator quantum phase transition at constant density. Based on large-scale Monte Carlo simulations of the classical (2+1)-dimensional J-current model and the two-dimensional Bose-Hubbard model, we can precisely determine the conductivity on the quantum critical plateau, σ(∞) = 0.359(4)σQ with σQ the conductivity quantum. The universal conductivity curve is the standard example with the lowest number of components where the bottoms-up AdS/CFT correspondence from string theory can be tested and made to use [R. C. Myers, S. Sachdev, and A. Singh, Phys. Rev. D 83, 066017 (2011)]. For the first time, the shape of the σ(iω(n)) - σ(∞) function in the Matsubara representation is accurate enough for a conclusive comparison and establishes the particlelike nature of charge transport. We find that the holographic gauge-gravity duality theory for transport properties can be made compatible with the data if temperature of the horizon of the black brane is different from the temperature of the conformal field theory. The requirements for measuring the universal conductivity in a cold gas experiment are also determined by our calculation. PMID:24484123

  1. Universal conductivity in a two-dimensional superfluid-to-insulator quantum critical system.

    PubMed

    Chen, Kun; Liu, Longxiang; Deng, Youjin; Pollet, Lode; Prokof'ev, Nikolay

    2014-01-24

    We compute the universal conductivity of the (2+1)-dimensional XY universality class, which is realized for a superfluid-to-Mott insulator quantum phase transition at constant density. Based on large-scale Monte Carlo simulations of the classical (2+1)-dimensional J-current model and the two-dimensional Bose-Hubbard model, we can precisely determine the conductivity on the quantum critical plateau, σ(∞) = 0.359(4)σQ with σQ the conductivity quantum. The universal conductivity curve is the standard example with the lowest number of components where the bottoms-up AdS/CFT correspondence from string theory can be tested and made to use [R. C. Myers, S. Sachdev, and A. Singh, Phys. Rev. D 83, 066017 (2011)]. For the first time, the shape of the σ(iω(n)) - σ(∞) function in the Matsubara representation is accurate enough for a conclusive comparison and establishes the particlelike nature of charge transport. We find that the holographic gauge-gravity duality theory for transport properties can be made compatible with the data if temperature of the horizon of the black brane is different from the temperature of the conformal field theory. The requirements for measuring the universal conductivity in a cold gas experiment are also determined by our calculation.

  2. Conformal perturbation of off-critical correlators in the 3D Ising universality class

    NASA Astrophysics Data System (ADS)

    Caselle, M.; Costagliola, G.; Magnoli, N.

    2016-07-01

    Thanks to the impressive progress of conformal bootstrap methods we have now very precise estimates of both scaling dimensions and operator product expansion coefficients for several 3D universality classes. We show how to use this information to obtain similarly precise estimates for off-critical correlators using conformal perturbation. We discuss in particular the ⟨σ (r )σ (0 )⟩ , ⟨ɛ (r )ɛ (0 )⟩ and ⟨σ (r )ɛ (0 )⟩ two-point functions in the high and low temperature regimes of the 3D Ising model and evaluate the leading and next to leading terms in the s =trΔt expansion, where t is the reduced temperature. Our results for ⟨σ (r )σ (0 )⟩ agree both with Monte Carlo simulations and with a set of experimental estimates of the critical scattering function.

  3. The Caenorhabditis elegans protein SAS-5 forms large oligomeric assemblies critical for centriole formation.

    PubMed

    Rogala, Kacper B; Dynes, Nicola J; Hatzopoulos, Georgios N; Yan, Jun; Pong, Sheng Kai; Robinson, Carol V; Deane, Charlotte M; Gönczy, Pierre; Vakonakis, Ioannis

    2015-05-29

    Centrioles are microtubule-based organelles crucial for cell division, sensing and motility. In Caenorhabditis elegans, the onset of centriole formation requires notably the proteins SAS-5 and SAS-6, which have functional equivalents across eukaryotic evolution. Whereas the molecular architecture of SAS-6 and its role in initiating centriole formation are well understood, the mechanisms by which SAS-5 and its relatives function is unclear. Here, we combine biophysical and structural analysis to uncover the architecture of SAS-5 and examine its functional implications in vivo. Our work reveals that two distinct self-associating domains are necessary to form higher-order oligomers of SAS-5: a trimeric coiled coil and a novel globular dimeric Implico domain. Disruption of either domain leads to centriole duplication failure in worm embryos, indicating that large SAS-5 assemblies are necessary for function in vivo.

  4. The Caenorhabditis elegans protein SAS-5 forms large oligomeric assemblies critical for centriole formation

    PubMed Central

    Rogala, Kacper B; Dynes, Nicola J; Hatzopoulos, Georgios N; Yan, Jun; Pong, Sheng Kai; Robinson, Carol V; Deane, Charlotte M; Gönczy, Pierre; Vakonakis, Ioannis

    2015-01-01

    Centrioles are microtubule-based organelles crucial for cell division, sensing and motility. In Caenorhabditis elegans, the onset of centriole formation requires notably the proteins SAS-5 and SAS-6, which have functional equivalents across eukaryotic evolution. Whereas the molecular architecture of SAS-6 and its role in initiating centriole formation are well understood, the mechanisms by which SAS-5 and its relatives function is unclear. Here, we combine biophysical and structural analysis to uncover the architecture of SAS-5 and examine its functional implications in vivo. Our work reveals that two distinct self-associating domains are necessary to form higher-order oligomers of SAS-5: a trimeric coiled coil and a novel globular dimeric Implico domain. Disruption of either domain leads to centriole duplication failure in worm embryos, indicating that large SAS-5 assemblies are necessary for function in vivo. DOI: http://dx.doi.org/10.7554/eLife.07410.001 PMID:26023830

  5. Comparison of measured and calculated concrete and rebar specific activity during decommissioning of the Dalhousie SLOWPOKE-2 reactor.

    PubMed

    Smith, Philip G; Everall, Dave; Ariani, Imelda; Tsang, Kwok

    2013-07-01

    Following the defuelling and dismantling of the Dalhousie University SLOWPOKE-2 Reactor (DUSR) in 2011, the reactor pool concrete and rebar were sampled to support the unconditional free release of the material such that the facility could be classified for unrestricted use. A detailed MCNP5 model of the critical core assembly was simulated to calculate the thermal, intermediate and fast neutron flux profile below the reactor pool floor. The neutron fluxes were used to calculate the specific activity of significant radionuclides in the concrete and rebar. The calculated specific activity and consequently the calculated neutron fluxes were validated at a number of sample locations. The calculated concrete and rebar specific activity were found to be in good agreement with the measured specific activity at the sample locations. The unrestricted use of the facility was granted through the approval of the licence to abandon the facility in August 2011.

  6. Comparison of measured and calculated concrete and rebar specific activity during decommissioning of the Dalhousie SLOWPOKE-2 reactor.

    PubMed

    Smith, Philip G; Everall, Dave; Ariani, Imelda; Tsang, Kwok

    2013-07-01

    Following the defuelling and dismantling of the Dalhousie University SLOWPOKE-2 Reactor (DUSR) in 2011, the reactor pool concrete and rebar were sampled to support the unconditional free release of the material such that the facility could be classified for unrestricted use. A detailed MCNP5 model of the critical core assembly was simulated to calculate the thermal, intermediate and fast neutron flux profile below the reactor pool floor. The neutron fluxes were used to calculate the specific activity of significant radionuclides in the concrete and rebar. The calculated specific activity and consequently the calculated neutron fluxes were validated at a number of sample locations. The calculated concrete and rebar specific activity were found to be in good agreement with the measured specific activity at the sample locations. The unrestricted use of the facility was granted through the approval of the licence to abandon the facility in August 2011. PMID:23658212

  7. Terminal short arm domains of basement membrane laminin are critical for its self-assembly

    PubMed Central

    1990-01-01

    Laminin self-assembles into large polymers by a cooperative two-step calcium-dependent mechanism (Yurchenco, P. D., E. C. Tsilibary, A. S. Charonis, and H. Furthmayr. 1985. J. Biol. Chem. 260:7636-7644). The domain specificity of this process was investigated using defined proteolytically generated fragments corresponding to the NH2-terminal globule and adjacent stem of the short arm of the B1 chain (E4), a complex of the two short arms of the A and B2 chains attached to the proximal stem of a third short arm (E1'), a similar complex lacking the globular domains (P1'), and the distal half of the long arm attached to the adjacent portion of the large globule (E8). Polymerization, followed by an increase of turbidity at 360 nm in neutral isotonic TBS containing CaCl2 at 35 degrees C, was quantitatively inhibited in a concentration-dependent manner with laminin fragments E4 and E1' but not with fragments E8 and P1'. Affinity retardation chromatography was used for further characterization of the binding of laminin domains. The migration of fragment E4, but not of fragments E8 and P1', was retarded in a temperature- and calcium-dependent fashion on a laminin affinity column but not on a similar BSA column. These data are evidence that laminin fragments E4 and E1' possess essential terminal binding domains for the self-aggregation of laminin, while fragments E8 and P1' do not. Furthermore, the individual domain-specific interactions that contribute to assembly are calcium dependent and of low affinity. PMID:2307709

  8. Criticality safety considerations in the geologic disposal of spent nuclear fuel assemblies

    SciTech Connect

    Gore, B.F.; McNair, G.W.; Heaberlin, S.W.

    1980-05-01

    Features of geologic disposal which hamper the demonstration that criticality cannot occur therein include possible changes of shape and form, intrusion of water as a neutron moderator, and selective leaching of spent fuel constituents. If the criticality safety of spent fuel disposal depends on burnup, independent measurements verifying the burnup should be performed prior to disposal. The status of nondestructive analysis method which might provide such verification is discussed. Calculations were performed to assess the potential for increasing the allowed size of a spent fuel disposal canister if potential water intrusion were limited by close-packing the enclosed rods. Several factors were identified which severely limited the potential of this application. The theoretical limit of hexagonal close-packing cannot be achieved due to fuel rod bowing. It is concluded that disposal canisters should be sized on the basis of assumed optimum moderation. Several topics for additional research were identified during this limited study.

  9. Neutron Activation and Thermoluminescent Detector Responses to a Bare Pulse of the CEA Valduc SILENE Critical Assembly

    SciTech Connect

    Miller, Thomas Martin; Celik, Cihangir; McMahan, Kimberly L.; Lee, Yi-kang; Gagnier, Emmanuel; Authier, Nicolas; Piot, Jerome; Jacquet, Xavier; Rousseau, Guillaume; Reynolds, Kevin H.

    2015-09-01

    This benchmark experiment was conducted as a joint venture between the US Department of Energy (DOE) and the French Commissariat à l'Energie Atomique (CEA). Staff at the Oak Ridge National Laboratory (ORNL) in the US and the Centre de Valduc in France planned this experiment. The experiment was conducted on October 11, 2010 in the SILENE critical assembly facility at Valduc. Several other organizations contributed to this experiment and the subsequent evaluation, including CEA Saclay, Lawrence Livermore National Laboratory (LLNL), the Y-12 National Security Complex (NSC), Babcock International Group in the United Kingdom, and Los Alamos National Laboratory (LANL). The goal of this experiment was to measure neutron activation and thermoluminescent dosimeter (TLD) doses from a source similar to a fissile solution critical excursion. The resulting benchmark can be used for validation of computer codes and nuclear data libraries as required when performing analysis of criticality accident alarm systems (CAASs). A secondary goal of this experiment was to qualitatively test performance of two CAAS detectors similar to those currently and formerly in use in some US DOE facilities. The detectors tested were the CIDAS MkX and the Rocky Flats NCD-91. These detectors were being evaluated to determine whether they would alarm, so they were not expected to generate benchmark quality data.

  10. Nuclear reactors built, being built, or planned: 1995

    SciTech Connect

    1996-08-01

    This report contains unclassified information about facilities built, being built, or planned in the US for domestic use or export as of December 31, 1995. The Office of Scientific and Technical Information, US Department of Energy, gathers this information annually from Washington headquarters and field offices of DOE; from the US Nuclear Regulatory Commission (NRC); from the US reactor manufacturers who are the principal nuclear contractors for foreign reactor locations; from US and foreign embassies; and from foreign governmental nuclear departments. The book consists of three divisions, as follows: (1) a commercial reactor locator map and tables of the characteristic and statistical data that follow; a table of abbreviations; (2) tables of data for reactors operating, being built, or planned; and (3) tables of data for reactors that have been shut down permanently or dismantled. The reactors are subdivided into the following parts: Civilian, Production, Military, Export, and Critical Assembly. Export reactor refers to a reactor for which the principal nuclear contractor is a US company--working either independently or in cooperation with a foreign company (Part 4). Critical assembly refers to an assembly of fuel and moderator that requires an external source of neutrons to initiate and maintain fission. A critical assembly is used for experimental measurements (Part 5).

  11. Nuclear reactors built, being built, or planned, 1994

    SciTech Connect

    1995-07-01

    This document contains unclassified information about facilities built, being built, or planned in the United States for domestic use or export as of December 31, 1994. The Office of Scientific and Technical Information, US Department of Energy, gathers this information annually from Washington headquarters and field offices of DOE; from the US Nuclear Regulatory Commission (NRC); from the US reactor manufacturers who are the principal nuclear contractors for foreign reactor locations; from US and foreign embassies; and from foreign governmental nuclear departments. The book consists of three divisions, as follows: a commercial reactor locator map and tables of the characteristic and statistical data that follow; a table of abbreviations; tables of data for reactors operating, being built, or planned; and tables of data for reactors that have been shut down permanently or dismantled. The reactors are subdivided into the following parts: Civilian, Production, Military, Export, and Critical Assembly. Export reactor refers to a reactor for which the principal nuclear contractor is a US company -- working either independently or in cooperation with a foreign company (Part 4). Critical assembly refers to an assembly of fuel and moderator that requires an external source of neutrons to initiate and maintain fission. A critical assembly is used for experimental measurements (Part 5).

  12. Performance Test of gPhone (#123, #126, and #127) in Kyoto and ITB Jatinangor

    NASA Astrophysics Data System (ADS)

    Wahyudi, E. J.; Fukuda, Y.; Nishijima, J.; Itakura, M.

    2016-08-01

    Gravity team of ITB, Kyoto University, and Kyushu University plan to carry out super hybrid measurement to monitor Carbon Capture Storage (CCS) injection in Gundih. During preparation stage and baseline survey before injection phase, gravity team analyze gPhone performance. Performance test of gPhone gravimeters in 2014 conducted in Kyoto and Jatinangor (three gPhone (#123, #126, and #127) placed in the same location). The tidal analysis program BAYTAP-G was used to decompose the gravity data into four components (tidal, trend, irregular, and response for auxiliary data). Response component in Kyoto relatively has lower frequency compare to Jatinangor, due to differences of the two measurement location. Response component from the longest time recording data (gPhone #123) give similiar pattern as gPhone #126, while gPhone #127 slightly different. Average standard deviation of the response component of three gPhone (#123, #126, and #127) respectively were 0.8, 1.0, and 1.9 μGal. Best drift achieved from this test show possibility to reach -4 to 5 pGal/day. Although gPhone #126 records different trend, but from tidal analysis comparison shows similiarity with gPhone #123.

  13. Theoretical estimation of the critical packing parameter of amphiphilic self-assembled aggregates

    NASA Astrophysics Data System (ADS)

    Khalil, Rabah A.; Zarari, Al-hakam A.

    2014-11-01

    The estimating of critical packing parameter (p) of amphiphilic compounds is considered as a hypothetical rather than an empirical. Consequently, an attempt has been made for determining such a dimensionless parameter for homologous series of sodium p-n-alkyl benzoates (n = 0-8) hydrotropes using quantum mechanical calculations that depend on density functional theory (DFT). The calculations were based on the following well-defined model, p = v/a0lc, where v is the volume of the hydrotrope tail, a0 is the effective head group area and lc is the length of the extended hydrotrope tail. It was found that the magnitude of both v and lc parameters can be estimated directly from quantum mechanical calculations. While the investigations found that the a0 parameter is parallel to the Connolly solvent accessible surface area (Csa) which could also be determined through theoretical computations. The obtained results were in good agreement with published data using small angle neutron scattering (SANS) technique. Hence, the theoretical model for predicting p of amphiphilic at critical micelle- or aggregation-concentration (cmc or cac) is p = v/Csalc. An apparent success was observed through applying this simple model to some randomly selected surfactants. It has been concluded that the theoretical calculations that based on quantum mechanical (DFT) method can be considered as a powerful tool for estimating the critical packing parameter of amphiphilic molecules. Finally, the results strongly suggest the employment of the presented model for estimating p of amphiphilic molecules at cmc or cac by computational chemistry software.

  14. Criticality-safety analyses of compacted and water-flooded. SP-100 reactors

    SciTech Connect

    Brandon, D.I.; Sapir, J.L.

    1986-01-01

    Reactivity calculations were performed to determine the sensitivity of three liquid metal-cooled, fast reactor designs to various accident environments. The concepts, proposed for the SP-100 Space Nuclear Power Program, included one thermionic and two fuel-pin designs. Numerous models of each core were developed to analyze the effect of core compaction and of water-flooded lattice spreading. Results indicate that those designs incorporating in-core control are least affected by core compaction and that the thermonic concept can best withstand expansion of the flooded fuel element array.

  15. Technical basis in support of the conversion of the University of Missouri Research Reactor (MURR) core from highly-enriched to low-enriched uranium - core neutron physics

    SciTech Connect

    Stillman, J.; Feldman, E.; Foyto, L; Kutikkad, K; McKibben, J C; Peters, N.; Stevens, J.

    2012-09-01

    This report contains the results of reactor design and performance for conversion of the University of Missouri Research Reactor (MURR) from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL) and the MURR Facility. The core conversion to LEU is being performed with financial support of the U. S. government.

  16. ExSPAnder: a universal repeat resolver for DNA fragment assembly

    PubMed Central

    Prjibelski, Andrey D.; Vasilinetc, Irina; Bankevich, Anton; Gurevich, Alexey; Krivosheeva, Tatiana; Nurk, Sergey; Pham, Son; Korobeynikov, Anton; Lapidus, Alla; Pevzner, Pavel A.

    2014-01-01

    Next-generation sequencing (NGS) technologies have raised a challenging de novo genome assembly problem that is further amplified in recently emerged single-cell sequencing projects. While various NGS assemblers can use information from several libraries of read-pairs, most of them were originally developed for a single library and do not fully benefit from multiple libraries. Moreover, most assemblers assume uniform read coverage, condition that does not hold for single-cell projects where utilization of read-pairs is even more challenging. We have developed an exSPAnder algorithm that accurately resolves repeats in the case of both single and multiple libraries of read-pairs in both standard and single-cell assembly projects. Availability and implementation: http://bioinf.spbau.ru/en/spades Contact: ap@bioinf.spbau.ru PMID:24931996

  17. Thermal-hydraulic modeling of the Pennsylvania State University Breazeale Nuclear Reactor (PSBR)

    NASA Astrophysics Data System (ADS)

    Chang, Jong E.

    2005-11-01

    Earlier experiments determined that the Pennsylvania State University Breazeale Nuclear Reactor (PSBR) core is cooled, not by an axial flow, but rather by a strong cross flow due to the thermal expansion of the coolant. To further complicate the flow field, a nitrogen-16 (N-16) pump was installed above the PSBR core to mix the exiting core buoyant thermal plume in order to delay the rapid release of radioactive N-16 to the PSBR pool surface. Thus, the interaction between the N-16 jet flow and the buoyancy driven flow complicates the analysis of the flow distribution in the PSBR pool. The main objectives of this study is to model the thermal-hydraulic behavior of the PSBR core and pool. During this study four major things were performed including the Computational Fluid Dynamics (CFD) model for the PSBR pool, the stand-alone fuel rod model for a PSBR fuel rod, the velocity measurements in and around the PSBR core, and the temperature measurements in the PSBR pool. Once the flow field was predicted by the CFD model, the measurement devices were manufactured and calibrated based on the CFD results. The major contribution of this study is to understand and to explain the flow behavior in the PSBR subchannels and pool using the FLOW3D model. The stand-alone dynamic fuel rod model was developed to determine the temperature distribution inside a PSBR fuel rod. The stand-alone fuel rod model was coupled to the FLOW3D model and used to predict the temperature behavior during steady-state and pulsing. The heat transfer models in the stand-alone fuel rod code are used in order to overcome the disadvantage of the CFD code, which does not calculate the mechanical stress, the gap conductance, and the two phase heat transfer. (Abstract shortened by UMI.)

  18. Developing a University Learning Community of Critical Readers and Writers: The Story of a Liberal Arts and IEP Partnership

    ERIC Educational Resources Information Center

    Ernst, Beth Kozbial; Wonder, Kelly; Adler, Julie

    2016-01-01

    Integrating English language learners into the academic mainstream is a critically important goal. For students who are learning content in their second or third language as well as negotiating the university's social context, integrating into the mainstream academic environment can be challenging. Instructors at a public university intensive…

  19. Mindfulness as an Alternative for Supporting University Student Mental Health: Cognitive-Emotional and Depressive Self-Criticism Measures

    ERIC Educational Resources Information Center

    Azam, Muhammad Abid; Mongrain, Myriam; Vora, Khushboo; Pirbaglou, Meysam; Azargive, Saam; Changoor, Tina; Wayne, Noah; Guglietti, Crissa; Macpherson, Alison; Irvine, Jane; Rotondi, Michael; Smith, Dawn; Perez, Daniel; Ritvo, Paul

    2016-01-01

    Increases in university-based mental health problems require alternative mental health programs, applicable to students with elevated psychological risks due to personality traits. This study examined the cognitive-emotional outcomes of a university mindfulness meditation (MM) program and their relationship with Self-Criticism (SC), a personality…

  20. PREFACE: MEM05: The 3rd International Workshop on Mechano-Electromagnetic Properties of Composite Superconductors (Kyoto, Japan, 17 20 July 2005)

    NASA Astrophysics Data System (ADS)

    Osamura, Kozo; Hampshire, Damian

    2005-12-01

    One of the important challenges facing the international scientific community at the beginning of the third millennium is how to manage the world's energy resources properly. Superconductivity will provide one of the strategies employed to avoid an energy crisis. Of course the ITER Fusion Tokomak that is to be built in France provides an exciting focus for the whole superconductivity community. In parallel, we can expect that other key technologies for superconductivity such as large capacity transmission cables, energy storage systems, and generators and motors will have a real impact in technologically advanced countries. There is broadly a consensus that the prototype stage for high-current high-field superconducting applications is largely completed, and the required performance has been demonstrated. However, before we move to full industrialization of large-scale superconducting technologies, feasibility studies suggest there are two types of problem that remain. The first is the development of high performance and low cost materials which are fully optimized in terms of critical current, low ac loss and high strength. The second is the establishment of optimal procedures for system design accompanying scale up. As the system design is dependent on material development, there is a critical need to study the key issues for developing high performance superconducting materials. Under the activities of the NEDO Grant Project (Applied Superconductivity), MEM05 was organized by Professor Osamura (Kyoto University), Professor Itoh (NIMS), Professor Hojo (Kyoto University) and Professor Matsumoto (Kyoto University) and held in Kyoto, Japan. The focus for the workshop was the elimination of grain boundary weak links, the creation of strong flux pinning sites, the optimal arrangement of filaments and barriers for reducing ac losses, and the design of high strength strain tolerant composite conductors. Five subsessions were held at MEM05. • Mechanical properties of

  1. Correlation between Knowledge, Experience and Common Sense, with Critical Thinking Capability of Medical Faculty's Students at Indonesia Christian University

    ERIC Educational Resources Information Center

    Nadeak, Bernadetha

    2015-01-01

    This research discusses correlation between knowledge, experience and common sense with critical thinking of Medical Faculty's Student. As to the objective of this research is to find the correlation between knowledge, experience and common sense with critical thinking of Medical Faculty's Students at Christian University of Indonesia. It is…

  2. Universal Scaling in the Fan of an Unconventional Quantum Critical Point

    SciTech Connect

    Melko, Roger G; Kaul, Ribhu

    2008-01-01

    We present the results of extensive finite-temperature Quantum Monte Carlo simulati ons on a SU(2) symmetric, $S=1/2$ quantum antiferromagnet with a frustrating four-s pin interaction -- the so-called 'JQ' model~[Sandvik, Phys. Rev. Lett. {\\bf 98}, 22 7202 (2007)]. Our simulations, which are unbiased, free of the sign-problem and car ried out on lattice sizes containing in excess of $1.6\\times 10^4$ spins, indicate that N\\'eel order is destroyed through a continuous quantum transition at a critica l value of the frustrating interaction. At larger values of this coupling the param agnetic state obtained has valence-bond solid order. The scaling behavior in the 'q uantum critical fan' above the putative critical point confirms a $z=1$ quantum pha se transition that is not in the conventional $O(3)$ universality class. Our result s are consistent with the predictions of the 'deconfined quantum criticality' scena rio.

  3. Universal self-field critical current for thin-film superconductors

    PubMed Central

    Talantsev, E. F.; Tallon, J. L.

    2015-01-01

    For any practical superconductor the magnitude of the critical current density, Jc, is crucially important. It sets the upper limit for current in the conductor. Usually Jc falls rapidly with increasing external magnetic field, but even in zero external field the current flowing in the conductor generates a self-field that limits Jc. Here we show for thin films of thickness less than the London penetration depth, λ, this limiting Jc adopts a universal value for all superconductors—metals, oxides, cuprates, pnictides, borocarbides and heavy Fermions. For type-I superconductors, it is Hc/λ where Hc is the thermodynamic critical field. But surprisingly for type-II superconductors, we find the self-field Jc is Hc1/λ where Hc1 is the lower critical field. Jc is thus fundamentally determined and this provides a simple means to extract absolute values of λ(T) and, from its temperature dependence, the symmetry and magnitude of the superconducting gap. PMID:26240014

  4. Universal self-field critical current for thin-film superconductors.

    PubMed

    Talantsev, E F; Tallon, J L

    2015-01-01

    For any practical superconductor the magnitude of the critical current density, Jc, is crucially important. It sets the upper limit for current in the conductor. Usually Jc falls rapidly with increasing external magnetic field, but even in zero external field the current flowing in the conductor generates a self-field that limits Jc. Here we show for thin films of thickness less than the London penetration depth, λ, this limiting Jc adopts a universal value for all superconductors-metals, oxides, cuprates, pnictides, borocarbides and heavy Fermions. For type-I superconductors, it is Hc/λ where Hc is the thermodynamic critical field. But surprisingly for type-II superconductors, we find the self-field Jc is Hc1/λ where Hc1 is the lower critical field. Jc is thus fundamentally determined and this provides a simple means to extract absolute values of λ(T) and, from its temperature dependence, the symmetry and magnitude of the superconducting gap. PMID:26240014

  5. Summer Freezing Resistance: A Critical Filter for Plant Community Assemblies in Mediterranean High Mountains.

    PubMed

    Pescador, David S; Sierra-Almeida, Ángela; Torres, Pablo J; Escudero, Adrián

    2016-01-01

    Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain) by measuring their ice nucleation temperature, freezing point (FP), and low-temperature damage (LT50), as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance). The community response to freezing was estimated for each plot as community weighted means (CWMs) and functional diversity (FD), and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content (LDMC), and seed mass). There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the FD of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only leaf dry matter content was negatively correlated with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower FD of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to be a general prerequisite for plants

  6. Summer Freezing Resistance: A Critical Filter for Plant Community Assemblies in Mediterranean High Mountains.

    PubMed

    Pescador, David S; Sierra-Almeida, Ángela; Torres, Pablo J; Escudero, Adrián

    2016-01-01

    Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain) by measuring their ice nucleation temperature, freezing point (FP), and low-temperature damage (LT50), as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance). The community response to freezing was estimated for each plot as community weighted means (CWMs) and functional diversity (FD), and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content (LDMC), and seed mass). There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the FD of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only leaf dry matter content was negatively correlated with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower FD of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to be a general prerequisite for plants

  7. Summer Freezing Resistance: A Critical Filter for Plant Community Assemblies in Mediterranean High Mountains

    PubMed Central

    Pescador, David S.; Sierra-Almeida, Ángela; Torres, Pablo J.; Escudero, Adrián

    2016-01-01

    Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain) by measuring their ice nucleation temperature, freezing point (FP), and low-temperature damage (LT50), as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance). The community response to freezing was estimated for each plot as community weighted means (CWMs) and functional diversity (FD), and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content (LDMC), and seed mass). There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the FD of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only leaf dry matter content was negatively correlated with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower FD of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to be a general prerequisite for plants

  8. Critical Behavior of CP{sup 1} at {theta}={pi}, Haldane's Conjecture, and the Relevant Universality Class

    SciTech Connect

    Azcoiti, Vicente; Di Carlo, Giuseppe; Galante, Angelo

    2007-06-22

    Using an approach to analyze the {theta} dependence of systems with a {theta} term we recently proposed, the critical behavior of CP{sup 1} at {theta}={pi} is studied. We find a region outside the strong coupling regime where Haldane's conjecture is verified. The critical line, however, does not belong to the universality class of the Wess-Zumino-Novikov-Witten model at topological coupling k=1 since it shows continuously varying critical exponents.

  9. Evaluated Iridium, Yttrium, and Thulium Cross Sections and Integral Validation Against Critical Assembly and Bethe Sphere Measurements

    SciTech Connect

    Chadwick, M.B. Frankle, S.; Trellue, H.; Talou, P.; Kawano, T.; Young, P.G.; MacFarlane, R.E.; Wilkerson, C.W.

    2007-12-15

    We describe new dosimetry (radiochemical) ENDF evaluations for yttrium, iridium, and thulium. These LANL2006 evaluations were based upon measured data and on nuclear model cross section calculations. In the case of iridium and yttrium, new measurements using the GEANIE gamma-ray detector at LANSCE were used to infer (n,xn) cross sections, the measurements being augmented by nuclear model calculations using the GNASH code. The thulium isotope evaluations were based on GNASH calculations and older measurements. The evaluated cross section data are tested through comparisons of simulations with measurements of reaction rates in critical assemblies and in Bethe sphere (sometimes called Wyman sphere) integral experiments. Two types of Bethe sphere experiments were studied - a LiD experiment that had a significant component of 14 MeV neutrons, and a LiD-U experiment that additionally had varying amounts of fission neutrons depending upon the location. These simulations were performed with the MCNP code using continuous energy Monte Carlo, and because the neutron fluences can be modeled fairly accurately by MCNP at different locations in these assemblies, the comparisons provide a valuable validation test of the accuracy of the evaluated cross sections and their energy dependencies. The MCNP integral reaction rate validation testing for the three detectors yttrium, iridium, and thulium, in the LANL2006 database is summarized as follows: (1) (n,2n)near 14 MeV: In 14 MeV-dominated locations (the LiD Bethe spheres and the outer regions of the LiD-U Bethe spheres), the (n,2n) products are modeled very well for all three detectors, suggesting that the evaluated {sup 89}Y(n,2n), {sup 191}Ir(n,2n), and {sup 169}Tm(n,2n) cross sections are accurate to better than about 5% near 14 MeV; (2) (n,2n)near threshold: In locations that have a significant number of fission spectrum neutrons or downscattered neutrons from 14 MeV inelastic scattering (the central regions of the Li

  10. Determination of the relative power density distribution in a heterogeneous reactor from the results of measurements of the reactivity effects and the neutron importance function

    NASA Astrophysics Data System (ADS)

    Bobrov, A. A.; Glushkov, E. S.; Zimin, A. A.; Kapitonova, A. V.; Kompaniets, G. V.; Nosov, V. I.; Petrushenko, R. P.; Smirnov, O. N.

    2012-12-01

    A method for experimental determination of the relative power density distribution in a heterogeneous reactor based on measurements of fuel reactivity effects and importance of neutrons from a californium source is proposed. The method was perfected on two critical assembly configurations at the NARCISS facility of the Kurchatov Institute, which simulated a small-size heterogeneous nuclear reactor. The neutron importance measurements were performed on subcritical and critical assemblies. It is shown that, along with traditionally used activation methods, the developed method can be applied to experimental studies of special features of the power density distribution in critical assemblies and reactors.

  11. Determination of the relative power density distribution in a heterogeneous reactor from the results of measurements of the reactivity effects and the neutron importance function

    SciTech Connect

    Bobrov, A. A.; Glushkov, E. S.; Zimin, A. A.; Kapitonova, A. V.; Kompaniets, G. V.; Nosov, V. I. Petrushenko, R. P.; Smirnov, O. N.

    2012-12-15

    A method for experimental determination of the relative power density distribution in a heterogeneous reactor based on measurements of fuel reactivity effects and importance of neutrons from a californium source is proposed. The method was perfected on two critical assembly configurations at the NARCISS facility of the Kurchatov Institute, which simulated a small-size heterogeneous nuclear reactor. The neutron importance measurements were performed on subcritical and critical assemblies. It is shown that, along with traditionally used activation methods, the developed method can be applied to experimental studies of special features of the power density distribution in critical assemblies and reactors.

  12. KEGG: Kyoto Encyclopedia of Genes and Genomes.

    PubMed

    Ogata, H; Goto, S; Sato, K; Fujibuchi, W; Bono, H; Kanehisa, M

    1999-01-01

    Kyoto Encyclopedia of Genes and Genomes (KEGG) is a knowledge base for systematic analysis of gene functions in terms of the networks of genes and molecules. The major component of KEGG is the PATHWAY database that consists of graphical diagrams of biochemical pathways including most of the known metabolic pathways and some of the known regulatory pathways. The pathway information is also represented by the ortholog group tables summarizing orthologous and paralogous gene groups among different organisms. KEGG maintains the GENES database for the gene catalogs of all organisms with complete genomes and selected organisms with partial genomes, which are continuously re-annotated, as well as the LIGAND database for chemical compounds and enzymes. Each gene catalog is associated with the graphical genome map for chromosomal locations that is represented by Java applet. In addition to the data collection efforts, KEGG develops and provides various computational tools, such as for reconstructing biochemical pathways from the complete genome sequence and for predicting gene regulatory networks from the gene expression profiles. The KEGG databases are daily updated and made freely available (http://www.genome.ad.jp/kegg/).

  13. KEGG: kyoto encyclopedia of genes and genomes.

    PubMed

    Kanehisa, M; Goto, S

    2000-01-01

    KEGG (Kyoto Encyclopedia of Genes and Genomes) is a knowledge base for systematic analysis of gene functions, linking genomic information with higher order functional information. The genomic information is stored in the GENES database, which is a collection of gene catalogs for all the completely sequenced genomes and some partial genomes with up-to-date annotation of gene functions. The higher order functional information is stored in the PATHWAY database, which contains graphical representations of cellular processes, such as metabolism, membrane transport, signal transduction and cell cycle. The PATHWAY database is supplemented by a set of ortholog group tables for the information about conserved subpathways (pathway motifs), which are often encoded by positionally coupled genes on the chromosome and which are especially useful in predicting gene functions. A third database in KEGG is LIGAND for the information about chemical compounds, enzyme molecules and enzymatic reactions. KEGG provides Java graphics tools for browsing genome maps, comparing two genome maps and manipulating expression maps, as well as computational tools for sequence comparison, graph comparison and path computation. The KEGG databases are daily updated and made freely available (http://www. genome.ad.jp/kegg/).

  14. Feasibility study of the University of Utah TRIGA reactor power upgrade in respect to control rod system

    NASA Astrophysics Data System (ADS)

    Cutic, Avdo

    The objectives of this thesis are twofold: to determine the highest achievable power levels of the current University of Utah TRIG Reactor (UUTR) core configuration with the existing three control rods, and to design the core for higher reactor power by optimizing the control rod worth. For the current core configuration, the maximum reactor power, eigenvalue keff, shutdown margin, and excess reactivity have been measured and calculated. These calculated estimates resulted from thermal power calibrations, and the control rod worth measurements at various power levels. The results were then used as a benchmark to verify the MCNP5 core simulations for the current core and then to design a core for higher reactor power. This study showed that the maximum achievable power with the current core configuration and control rod system is 150kW, which is 50kW higher than the licensed power of the UUTR. The maximum achievable UUTR core power with the existing fuel is determined by optimizing the core configuration and control rod worth, showing that a power upgrade of 500 kW is achievable. However, it requires a new control rod system consisting of a total of four control rods. The cost of such an upgrade is $115,000.

  15. Low enrichment fuel conversion for Iowa State University. Progress report, August 1, 1991--July 31, 1992

    SciTech Connect

    Rohach, A.F.

    1992-08-01

    This report discusses the UTR-10 reactor at Iowa State University which went critical on low enriched uranium (LEU) fuel on August 14, 1991. However, subsequent to the criticality experiments the fuel plates started to discolor. In addition, roll pins used to lift the fuel assemblies were discovered to be cracked. It was determined that these problems were due to chemical agents in the primary coolant water. The roll pins were replaced by solid stainless steel pins. The primary coolant was replaced and the reactor is currently in operation. Surveillance specimens will be used to monitor any possible future discoloration. The high enriched fuel (HEU) is being prepared for eventual shipment to a high enriched fuel receiving facility.

  16. Critical exponents of dynamical conductivity in 2D percolative superconductor-insulator transitions: three universality classes.

    PubMed

    Karki, Pragalv; Loh, Yen Lee

    2016-11-01

    We simulate three types of random inductor-capacitor (LC) networks on [Formula: see text] square lattices. We calculate the dynamical conductivity using an equation-of-motion method in which timestep error is eliminated and windowing error is minimized. We extract the critical exponent a such that [Formula: see text] at low frequencies. The results suggest that there are three different universality classes. The [Formula: see text] model, with capacitances from each site to ground, has a  =  0.314(4). The [Formula: see text] model, with capacitances along bonds, has a  =  0. The [Formula: see text] model, with both types of capacitances, has a  =  0.304(1). This implies that classical percolative 2D superconductor-insulator transitions (SITs) generically have [Formula: see text] as [Formula: see text]. Therefore, any experiments that give a constant conductivity as [Formula: see text] must be explained in terms of quantum effects.

  17. Higher Criticism and Higher Education at the University of Chicago: William Rainey Harper's Vision of Religion in the Research University

    ERIC Educational Resources Information Center

    Lee, Michael

    2008-01-01

    In the 1890s, the Board of Trustees of the not-yet-built University of Chicago had just elected Rainey Harper to be its first president, and later, he would formally accept the position. Harper left a secure position at Yale University to accept the presidency of a university that was nothing more than an idea, a board of trustees, and the…

  18. Reactor performances and microbial communities of biogas reactors: effects of inoculum sources.

    PubMed

    Han, Sheng; Liu, Yafeng; Zhang, Shicheng; Luo, Gang

    2016-01-01

    Anaerobic digestion is a very complex process that is mediated by various microorganisms, and the understanding of the microbial community assembly and its corresponding function is critical in order to better control the anaerobic process. The present study investigated the effect of different inocula on the microbial community assembly in biogas reactors treating cellulose with various inocula, and three parallel biogas reactors with the same inoculum were also operated in order to reveal the reproducibility of both microbial communities and functions of the biogas reactors. The results showed that the biogas production, volatile fatty acid (VFA) concentrations, and pH were different for the biogas reactors with different inocula, and different steady-state microbial community patterns were also obtained in different biogas reactors as reflected by Bray-Curtis similarity matrices and taxonomic classification. It indicated that inoculum played an important role in shaping the microbial communities of biogas reactor in the present study, and the microbial community assembly in biogas reactor did not follow the niche-based ecology theory. Furthermore, it was found that the microbial communities and reactor performances of parallel biogas reactors with the same inoculum were different, which could be explained by the neutral-based ecology theory and stochastic factors should played important roles in the microbial community assembly in the biogas reactors. The Bray-Curtis similarity matrices analysis suggested that inoculum affected more on the microbial community assembly compared to stochastic factors, since the samples with different inocula had lower similarity (10-20 %) compared to the samples from the parallel biogas reactors (30 %).

  19. Advanced neutron irradiation system using Texas A&M University Nuclear Science Center Reactor

    NASA Astrophysics Data System (ADS)

    Jang, Si Young

    A heavily filtered fast neutron irradiation system (FNIS) was developed for a variety of applications, including the study of long-term health effects of fast neutrons by evaluating the biological mechanisms of damage in cultured cells and living animals such as rats or mice. This irradiation system includes an exposure cave made with a lead-bismuth alloy, a cave positioning system, a gamma and neutron monitoring system, a sample transfer system, and interchangeable filters. This system was installed in the irradiation cell of the Texas A&M University Nuclear Science Center Reactor (NSCR). By increasing the thickness of the lead-bismuth alloy, the neutron spectra were shifted into lower energies by the scattering interactions of fast neutrons with the alloy. It is possible, therefore, by changing the alloy thickness, to produce distinctly different dose weighted neutron spectra inside the exposure cave of the FNIS. The calculated neutron spectra showed close agreement with the results of activation foil measurements, unfolded by SAND-II close to the cell window. However, there was a considerable less agreement for locations far away from the cell window. Even though the magnitude of values such as neutron flux and tissue kerma rates in air differed, the weighted average neutron energies showed close agreement between the MCNP and SAND-II since the normalized neutron spectra were in a good agreement each other. A paired ion chamber system was constructed, one with a tissue equivalent plastic (A-150) and propane gas for total dose monitoring, and another with graphite and argon for photon dose monitoring. Using the pair of detectors, the neutron to gamma ratio can be inferred. With the 20 cm-thick FNIS, the absorbed dose rates of neutrons measured with the paired ion chamber method and calculated with the SAND-II results were 13.7 +/- 0.02 Gy/min and 15.5 Gy/min, respectively. The absorbed dose rate of photons and the gamma contribution to total dose were 6.7 x 10

  20. Critical experiments with mixed oxide fuel

    SciTech Connect

    Harris, D.R.

    1997-06-01

    This paper very briefly outlines technical considerations in performing critical experiments on weapons-grade plutonium mixed oxide fuel assemblies. The experiments proposed would use weapons-grade plutonium and Er{sub 2}O{sub 3} at various dissolved boron levels, and for specific fuel assemblies such as the ABBCE fuel assembly with five large water holes. Technical considerations described include the core, the measurements, safety, security, radiological matters, and licensing. It is concluded that the experiments are feasible at the Rensselaer Polytechnic Institute Reactor Critical Facility. 9 refs.

  1. A universal approach to fabricate ordered colloidal crystals arrays based on electrostatic self-assembly.

    PubMed

    Zhang, Xun; Zhang, Junhu; Zhu, Difu; Li, Xiao; Zhang, Xuemin; Wang, Tieqiang; Yang, Bai

    2010-12-01

    We present a novel and simple method to fabricate two-dimensional (2D) poly(styrene sulfate) (PSS, negatively charged) colloidal crystals on a positively charged substrate. Our strategy contains two separate steps: one is the three-dimensional (3D) assembly of PSS particles in ethanol, and the other is electrostatic adsorption in water. First, 3D assembly in ethanol phase eliminates electrostatic attractions between colloids and the substrate. As a result, high-quality colloidal crystals are easily generated, for electrostatic attractions are unfavorable for the movement of colloidal particles during convective self-assembly. Subsequently, top layers of colloidal spheres are washed away in the water phase, whereas well-packed PSS colloids that are in contact with the substrate are tightly linked due to electrostatic interactions, resulting in the formation of ordered arrays of 2D colloidal spheres. Cycling these processes leads to the layer-by-layer assembly of 3D colloidal crystals with controllable layers. In addition, this strategy can be extended to the fabrication of patterned 2D colloidal crystals on patterned polyelectrolyte surfaces, not only on planar substrates but also on nonplanar substrates. This straightforward method may open up new possibilities for practical use of colloidal crystals of excellent quality, various patterns, and controllable fashions.

  2. Universal critical phenomena of the cloud --> crystal phase transition in the Paul trap: Powerlaws

    NASA Astrophysics Data System (ADS)

    Weiss, Daniel; Nam, Yunseong; Blümel, Reinhold

    N charged particles, simultaneously stored in a radio-frequency (rf) Paul trap, exhibit deterministic heating. Depending on the damping (γ) imparted to the system, these particles can exist in multiple phases, the most commonly found being the cloud and crystal phases. With a small γ, the particles exhibit gas-like behavior, where the heating and cooling equilibrate and a stable cloud results. For larger γ, the damping overcomes the heating and the particles are forced into the crystalline state. We explore the cloud --> crystal transition as a critical phenomenon. We find that the transition occurs at a critical value γc of the damping constant γ. We find that as a function of N, γc scales approximately like an iterated log law. We also present a universal power law, τm ~(γ -γc) - β , γ >γc , β > 0 , independent of both N and the Paul trap parameter a, depending only on the Paul trap parameter q, that describes the number of cycles necessary for the system to crystallize as a function of γ -γc .

  3. Universal Quantum Criticality in the Metal-Insulator Transition of Two-Dimensional Interacting Dirac Electrons

    NASA Astrophysics Data System (ADS)

    Otsuka, Yuichi; Yunoki, Seiji; Sorella, Sandro

    2016-01-01

    The metal-insulator transition has been a subject of intense research since Mott first proposed that the metallic behavior of interacting electrons could turn to an insulating one as electron correlations increase. Here, we consider electrons with massless Dirac-like dispersion in two spatial dimensions, described by the Hubbard models on two geometrically different lattices, and perform numerically exact calculations on unprecedentedly large systems that, combined with a careful finite-size scaling analysis, allow us to explore the quantum critical behavior in the vicinity of the interaction-driven metal-insulator transition. Thereby, we find that the transition is continuous, and we determine the quantum criticality for the corresponding universality class, which is described in the continuous limit by the Gross-Neveu model, a model extensively studied in quantum field theory. Furthermore, we discuss a fluctuation-driven scenario for the metal-insulator transition in the interacting Dirac electrons: The metal-insulator transition is triggered only by the vanishing of the quasiparticle weight, not by the Dirac Fermi velocity, which instead remains finite near the transition. This important feature cannot be captured by a simple mean-field or Gutzwiller-type approximate picture but is rather consistent with the low-energy behavior of the Gross-Neveu model.

  4. Universality in the Self Organized Critical behavior of a cellular model of superconducting vortex dynamics

    NASA Astrophysics Data System (ADS)

    Sun, Yudong; Vadakkan, Tegy; Bassler, Kevin

    2007-03-01

    We study the universality and robustness of variants of the simple model of superconducting vortex dynamics first introduced by Bassler and Paczuski in Phys. Rev. Lett. 81, 3761 (1998). The model is a coarse-grained model that captures the essential features of the plastic vortex motion. It accounts for the repulsive interaction between vortices, the pining of vortices at quenched disordered locations in the material, and the over-damped dynamics of the vortices that leads to tearing of the flux line lattice. We report the results of extensive simulations of the critical ``Bean state" dynamics of the model. We find a phase diagram containing four distinct phases of dynamical behavior, including two phases with distinct Self Organized Critical (SOC) behavior. Exponents describing the avalanche scaling behavior in the two SOC phases are determined using finite-size scaling. The exponents are found to be robust within each phase and for different variants of the model. The difference of the scaling behavior in the two phases is also observed in the morphology of the avalanches.

  5. Nuclear Criticality Control and Safety of Plutonium-Uranium Fuel Mixtures Outside Reactors

    SciTech Connect

    Biswas, D; Mennerdahl, D

    2008-06-23

    The ANSI/ANS 8.12 standard was first approved in July 1978. At that time, this edition was applicable to operations with plutonium-uranium oxide (MOX) fuel mixtures outside reactors and was limited to subcritical limits for homogeneous systems. The next major revision, ANSI/ANS-8.12-1987, included the addition of subcritical limits for heterogeneous systems. The standard was subsequently reaffirmed in February 1993. During late 1990s, substantial work was done by the ANS 8.12 Standard Working Group to re-examine the technical data presented in the standard using the latest codes and cross section sets. Calculations performed showed good agreement with the values published in the standard. This effort resulted in the reaffirmation of the standard in March 2002. The standard is currently in a maintenance mode. After 2002, activities included discussions to determine the future direction of the standard and to follow the MOX standard development by the International Standard Organization (ISO). In 2007, the Working Group decided to revise the standard to extend the areas of applicability by providing a wider range of subcritical data. The intent is to cover a wider domain of MOX fuel fabrication and operations. It was also decided to follow the ISO MOX standard specifications (related to MOX density and isotopics) and develop a new set of subcritical limits for homogeneous systems. This has resulted in the submittal (and subsequent approval) of the project initiation notification system form (PINS) in 2007.

  6. A Temporospatial Map That Defines Specific Steps at Which Critical Surfaces in the Gag MA and CA Domains Act during Immature HIV-1 Capsid Assembly in Cells

    PubMed Central

    Robinson, Bridget A.; Reed, Jonathan C.; Geary, Clair D.; Swain, J. Victor

    2014-01-01

    ABSTRACT During HIV-1 assembly, Gag polypeptides target to the plasma membrane, where they multimerize to form immature capsids that undergo budding and maturation. Previous mutational analyses identified residues within the Gag matrix (MA) and capsid (CA) domains that are required for immature capsid assembly, and structural studies showed that these residues are clustered on four exposed surfaces in Gag. Exactly when and where the three critical surfaces in CA function during assembly are not known. Here, we analyzed how mutations in these four critical surfaces affect the formation and stability of assembly intermediates in cells expressing the HIV-1 provirus. The resulting temporospatial map reveals that critical MA residues act during membrane targeting, residues in the C-terminal CA subdomain (CA-CTD) dimer interface are needed for the stability of the first membrane-bound assembly intermediate, CA-CTD base residues are necessary for progression past the first membrane-bound intermediate, and residues in the N-terminal CA subdomain (CA-NTD) stabilize the last membrane-bound intermediate. Importantly, we found that all four critical surfaces act while Gag is associated with the cellular facilitators of assembly ABCE1 and DDX6. When correlated with existing structural data, our findings suggest the following model: Gag dimerizes via the CA-CTD dimer interface just before or during membrane targeting, individual CA-CTD hexamers form soon after membrane targeting, and the CA-NTD hexameric lattice forms just prior to capsid release. This model adds an important new dimension to current structural models by proposing the potential order in which key contacts within the immature capsid lattice are made during assembly in cells. IMPORTANCE While much is known about the structure of the completed HIV-1 immature capsid and domains of its component Gag proteins, less is known about the sequence of events leading to formation of the HIV-1 immature capsid. Here we used

  7. NUCLEAR REACTORS

    DOEpatents

    Koch, L.J.; Rice, R.E. Jr.; Denst, A.A.; Rogers, A.J.; Novick, M.

    1961-12-01

    An active portion assembly for a fast neutron reactor is described wherein physical distortions resulting in adverse changes in the volume-to-mass ratio are minimized. A radially expandable locking device is disposed within a cylindrical tube within each fuel subassembly within the active portion assembly, and clamping devices expandable toward the center of the active portion assembly are disposed around the periphery thereof. (AEC)

  8. IVA cloning: A single-tube universal cloning system exploiting bacterial In Vivo Assembly.

    PubMed

    García-Nafría, Javier; Watson, Jake F; Greger, Ingo H

    2016-06-06

    In vivo homologous recombination holds the potential for optimal molecular cloning, however, current strategies require specialised bacterial strains or laborious protocols. Here, we exploit a recA-independent recombination pathway, present in widespread laboratory E.coli strains, to develop IVA (In Vivo Assembly) cloning. This system eliminates the need for enzymatic assembly and reduces all molecular cloning procedures to a single-tube, single-step PCR, performed in <2 hours from setup to transformation. Unlike other methods, IVA is a complete system, and offers significant advantages over alternative methods for all cloning procedures (insertions, deletions, site-directed mutagenesis and sub-cloning). Significantly, IVA allows unprecedented simplification of complex cloning procedures: five simultaneous modifications of any kind, multi-fragment assembly and library construction are performed in approximately half the time of current protocols, still in a single-step fashion. This system is efficient, seamless and sequence-independent, and requires no special kits, enzymes or proprietary bacteria, which will allow its immediate adoption by the academic and industrial molecular biology community.

  9. IVA cloning: A single-tube universal cloning system exploiting bacterial In Vivo Assembly

    PubMed Central

    García-Nafría, Javier; Watson, Jake F.; Greger, Ingo H.

    2016-01-01

    In vivo homologous recombination holds the potential for optimal molecular cloning, however, current strategies require specialised bacterial strains or laborious protocols. Here, we exploit a recA-independent recombination pathway, present in widespread laboratory E.coli strains, to develop IVA (In Vivo Assembly) cloning. This system eliminates the need for enzymatic assembly and reduces all molecular cloning procedures to a single-tube, single-step PCR, performed in <2 hours from setup to transformation. Unlike other methods, IVA is a complete system, and offers significant advantages over alternative methods for all cloning procedures (insertions, deletions, site-directed mutagenesis and sub-cloning). Significantly, IVA allows unprecedented simplification of complex cloning procedures: five simultaneous modifications of any kind, multi-fragment assembly and library construction are performed in approximately half the time of current protocols, still in a single-step fashion. This system is efficient, seamless and sequence-independent, and requires no special kits, enzymes or proprietary bacteria, which will allow its immediate adoption by the academic and industrial molecular biology community. PMID:27264908

  10. IVA cloning: A single-tube universal cloning system exploiting bacterial In Vivo Assembly.

    PubMed

    García-Nafría, Javier; Watson, Jake F; Greger, Ingo H

    2016-01-01

    In vivo homologous recombination holds the potential for optimal molecular cloning, however, current strategies require specialised bacterial strains or laborious protocols. Here, we exploit a recA-independent recombination pathway, present in widespread laboratory E.coli strains, to develop IVA (In Vivo Assembly) cloning. This system eliminates the need for enzymatic assembly and reduces all molecular cloning procedures to a single-tube, single-step PCR, performed in <2 hours from setup to transformation. Unlike other methods, IVA is a complete system, and offers significant advantages over alternative methods for all cloning procedures (insertions, deletions, site-directed mutagenesis and sub-cloning). Significantly, IVA allows unprecedented simplification of complex cloning procedures: five simultaneous modifications of any kind, multi-fragment assembly and library construction are performed in approximately half the time of current protocols, still in a single-step fashion. This system is efficient, seamless and sequence-independent, and requires no special kits, enzymes or proprietary bacteria, which will allow its immediate adoption by the academic and industrial molecular biology community. PMID:27264908

  11. Deployment of a three-dimensional array of Micro-Pocket Fission Detector triads (MPFD3) for real-time, in-core neutron flux measurements in the Kansas State University TRIGA Mark-II Nuclear Reactor

    NASA Astrophysics Data System (ADS)

    Ohmes, Martin Francis

    A Micro-Pocket Fission Detector (MPFD) is a miniaturized type of fission chamber developed for use inside a nuclear reactor. Their unique design allows them to be located between or even inside fuel pins while being built from materials which give them an operational lifetime comparable to or exceeding the life of the fuel. While other types of neutron detectors have been made for use inside a nuclear reactor, the MPFD is the first neutron detector which can survive sustained use inside a nuclear reactor while providing a real-time measurement of the neutron flux. This dissertation covers the deployment of MPFDs as a large three-dimensional array inside the Kansas State University TRIGA Mark-II Nuclear Reactor for real-time neutron flux measurements. This entails advancements in the design, construction, and packaging of the Micro-Pocket Fission Detector Triads with incorporated Thermocouple, or MPFD3-T. Specialized electronics and software also had to be designed and built in order to make a functional system capable of collecting real-time data from up to 60 MPFD3-Ts, or 180 individual MPFDs and 60 thermocouples. Design of the electronics required the development of detailed simulations and analysis for determining the theoretical response of the detectors and determination of their size. The results of this research shows that MPFDs can operate for extended times inside a nuclear reactor and can be utilized toward the use as distributed neutron detector arrays for advanced reactor control systems and power mapping. These functions are critical for continued gains in efficiency of nuclear power reactors while also improving safety through relatively inexpensive redundancy.

  12. Avalanches in Self-Organized Critical Neural Networks: A Minimal Model for the Neural SOC Universality Class

    PubMed Central

    Rybarsch, Matthias; Bornholdt, Stefan

    2014-01-01

    The brain keeps its overall dynamics in a corridor of intermediate activity and it has been a long standing question what possible mechanism could achieve this task. Mechanisms from the field of statistical physics have long been suggesting that this homeostasis of brain activity could occur even without a central regulator, via self-organization on the level of neurons and their interactions, alone. Such physical mechanisms from the class of self-organized criticality exhibit characteristic dynamical signatures, similar to seismic activity related to earthquakes. Measurements of cortex rest activity showed first signs of dynamical signatures potentially pointing to self-organized critical dynamics in the brain. Indeed, recent more accurate measurements allowed for a detailed comparison with scaling theory of non-equilibrium critical phenomena, proving the existence of criticality in cortex dynamics. We here compare this new evaluation of cortex activity data to the predictions of the earliest physics spin model of self-organized critical neural networks. We find that the model matches with the recent experimental data and its interpretation in terms of dynamical signatures for criticality in the brain. The combination of signatures for criticality, power law distributions of avalanche sizes and durations, as well as a specific scaling relationship between anomalous exponents, defines a universality class characteristic of the particular critical phenomenon observed in the neural experiments. Thus the model is a candidate for a minimal model of a self-organized critical adaptive network for the universality class of neural criticality. As a prototype model, it provides the background for models that may include more biological details, yet share the same universality class characteristic of the homeostasis of activity in the brain. PMID:24743324

  13. Avalanches in self-organized critical neural networks: a minimal model for the neural SOC universality class.

    PubMed

    Rybarsch, Matthias; Bornholdt, Stefan

    2014-01-01

    The brain keeps its overall dynamics in a corridor of intermediate activity and it has been a long standing question what possible mechanism could achieve this task. Mechanisms from the field of statistical physics have long been suggesting that this homeostasis of brain activity could occur even without a central regulator, via self-organization on the level of neurons and their interactions, alone. Such physical mechanisms from the class of self-organized criticality exhibit characteristic dynamical signatures, similar to seismic activity related to earthquakes. Measurements of cortex rest activity showed first signs of dynamical signatures potentially pointing to self-organized critical dynamics in the brain. Indeed, recent more accurate measurements allowed for a detailed comparison with scaling theory of non-equilibrium critical phenomena, proving the existence of criticality in cortex dynamics. We here compare this new evaluation of cortex activity data to the predictions of the earliest physics spin model of self-organized critical neural networks. We find that the model matches with the recent experimental data and its interpretation in terms of dynamical signatures for criticality in the brain. The combination of signatures for criticality, power law distributions of avalanche sizes and durations, as well as a specific scaling relationship between anomalous exponents, defines a universality class characteristic of the particular critical phenomenon observed in the neural experiments. Thus the model is a candidate for a minimal model of a self-organized critical adaptive network for the universality class of neural criticality. As a prototype model, it provides the background for models that may include more biological details, yet share the same universality class characteristic of the homeostasis of activity in the brain.

  14. Osteogenesis of peripheral blood mesenchymal stem cells in self assembling peptide nanofiber for healing critical size calvarial bony defect.

    PubMed

    Wu, Guofeng; Pan, Mengjie; Wang, Xianghai; Wen, Jinkun; Cao, Shangtao; Li, Zhenlin; Li, Yuanyuan; Qian, Changhui; Liu, Zhongying; Wu, Wutian; Zhu, Lixin; Guo, Jiasong

    2015-11-16

    Peripheral blood mesenchymal stem cells (PBMSCs) may be easily harvested from patients, permitting autologous grafts for bone tissue engineering in the future. However, the PBMSC's capabilities of survival, osteogenesis and production of new bone matrix in the defect area are still unclear. Herein, PBMSCs were seeded into a nanofiber scaffold of self-assembling peptide (SAP) and cultured in osteogenic medium. The results indicated SAP can serve as a promising scaffold for PBMSCs survival and osteogenic differentiation in 3D conditions. Furthermore, the SAP seeded with the induced PBMSCs was splinted by two membranes of poly(lactic)-glycolic acid (PLGA) to fabricate a composited scaffold which was then used to repair a critical-size calvarial bone defect model in rat. Twelve weeks later the defect healing and mineralization were assessed by H&E staining and microcomputerized tomography (micro-CT). The osteogenesis and new bone formation of grafted cells in the scaffold were evaluated by immunohistochemistry. To our knowledge this is the first report with solid evidence demonstrating PBMSCs can survive in the bone defect area and directly contribute to new bone formation. Moreover, the present data also indicated the tissue engineering with PBMSCs/SAP/PLGA scaffold can serve as a novel prospective strategy for healing large size cranial defects.

  15. Osteogenesis of peripheral blood mesenchymal stem cells in self assembling peptide nanofiber for healing critical size calvarial bony defect

    PubMed Central

    Wu, Guofeng; Pan, Mengjie; Wang, Xianghai; Wen, Jinkun; Cao, Shangtao; Li, Zhenlin; Li, Yuanyuan; Qian, Changhui; Liu, Zhongying; Wu, Wutian; Zhu, Lixin; Guo, Jiasong

    2015-01-01

    Peripheral blood mesenchymal stem cells (PBMSCs) may be easily harvested from patients, permitting autologous grafts for bone tissue engineering in the future. However, the PBMSC’s capabilities of survival, osteogenesis and production of new bone matrix in the defect area are still unclear. Herein, PBMSCs were seeded into a nanofiber scaffold of self-assembling peptide (SAP) and cultured in osteogenic medium. The results indicated SAP can serve as a promising scaffold for PBMSCs survival and osteogenic differentiation in 3D conditions. Furthermore, the SAP seeded with the induced PBMSCs was splinted by two membranes of poly(lactic)-glycolic acid (PLGA) to fabricate a composited scaffold which was then used to repair a critical-size calvarial bone defect model in rat. Twelve weeks later the defect healing and mineralization were assessed by H&E staining and microcomputerized tomography (micro-CT). The osteogenesis and new bone formation of grafted cells in the scaffold were evaluated by immunohistochemistry. To our knowledge this is the first report with solid evidence demonstrating PBMSCs can survive in the bone defect area and directly contribute to new bone formation. Moreover, the present data also indicated the tissue engineering with PBMSCs/SAP/PLGA scaffold can serve as a novel prospective strategy for healing large size cranial defects. PMID:26568114

  16. Safety evaluation report related to the renewal of the operating license for the research reactor at North Carolina State University

    SciTech Connect

    1997-04-01

    This safety evaluation report (SER) summarizes the findings of a safety review conducted by the staff of the U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Reactor Regulation (NRR). The staff conducted this review in response to a timely application filed by North Carolina State University (the licensee or NCSU) for a 20-year renewal of Facility Operating License R-120 to continue to operate the NCSU PULSTAR research reactor. The facility is located in the Burlington Engineering Laboratory complex on the NCSU campus in Raleigh, North Carolina. In its safety review, the staff considered information submitted by the licensee (including past operating history recorded in the licensee`s annual reports to the NRC), as well as inspection reports prepared by NRC Region H personnel and first-hand observations. On the basis of this review, the staff concludes that NCSU can continue to operate the PULSTAR research reactor, in accordance with its application, without endangering the health and safety of the public. 16 refs., 31 figs., 7 tabs.

  17. Nuclear reactor

    DOEpatents

    Pennell, William E.; Rowan, William J.

    1977-01-01

    A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

  18. Identification of residues in the hepatitis C virus core protein that are critical for capsid assembly in a cell-free system.

    PubMed

    Klein, Kevin C; Dellos, Sheri R; Lingappa, Jaisri R

    2005-06-01

    Significant advances have been made in understanding hepatitis C virus (HCV) replication through development of replicon systems. However, neither replicon systems nor standard cell culture systems support significant assembly of HCV capsids, leaving a large gap in our knowledge of HCV virion formation. Recently, we established a cell-free system in which over 60% of full-length HCV core protein synthesized de novo in cell extracts assembles into HCV capsids by biochemical and morphological criteria. Here we used mutational analysis to identify residues in HCV core that are important for capsid assembly in this highly reproducible cell-free system. We found that basic residues present in two clusters within the N-terminal 68 amino acids of HCV core played a critical role, while the uncharged linker domain between them was not. Furthermore, the aspartate at position 111, the region spanning amino acids 82 to 102, and three serines that are thought to be sites of phosphorylation do not appear to be critical for HCV capsid formation in this system. Mutation of prolines important for targeting of core to lipid droplets also failed to alter HCV capsid assembly in the cell-free system. In addition, wild-type HCV core did not rescue assembly-defective mutants. These data constitute the first systematic and quantitative analysis of the roles of specific residues and domains of HCV core in capsid formation. PMID:15890921

  19. Critical Design Issues of Tokamak Cooling Water System of ITER's Fusion Reactor

    SciTech Connect

    Kim, Seokho H; Berry, Jan

    2011-01-01

    U.S. ITER is responsible for the design, engineering, and procurement of the Tokamak Cooling Water System (TCWS). The TCWS transfers heat generated in the Tokamak to cooling water during nominal pulsed operation 850 MW at up to 150 C and 4.2 MPa water pressure. This water contains radionuclides because impurities (e.g., tritium) diffuse from in-vessel components and the vacuum vessel by water baking at 200 240 C at up to 4.4MPa, and corrosion products become activated by neutron bombardment. The system is designated as safety important class (SIC) and will be fabricated to comply with the French Order concerning nuclear pressure equipment (December 2005) and the EU Pressure Equipment Directive using ASME Section VIII, Div 2 design codes. The complexity of the TCWS design and fabrication presents unique challenges. Conceptual design of this one-of-a-kind cooling system has been completed with several issues that need to be resolved to move to next stage of the design. Those issues include flow balancing between over hundreds of branch pipelines in parallel to supply cooling water to blankets, determination of optimum flow velocity while minimizing the potential for cavitation damage, design for freezing protection for cooling water flowing through cryostat (freezing) environment, requirements for high-energy piping design, and electromagnetic impact to piping and components. Although the TCWS consists of standard commercial components such as piping with valves and fittings, heat exchangers, and pumps, complex requirements present interesting design challenges. This paper presents a brief description of TCWS conceptual design and critical design issues that need to be resolved.

  20. Universal Behavior of the BEC Critical Temperature for a Multi-slab Ideal Bose Gas

    NASA Astrophysics Data System (ADS)

    Rodríguez, O. A.; Solís, M. A.

    2016-05-01

    For an ideal Bose gas within a multi-slab periodic structure, we discuss the effect of the spatial distribution of the gas on its Bose-Einstein condensation critical temperature T_c, as well as on the origin of its dimensional crossover observed in the specific heat. The multi-slabs structure is generated by applying a Kronig-Penney potential to the gas in the perpendicular direction to the slabs of width b and separated by a distance a, and allowing the particles to move freely in the other two directions. We found that T_c decreases continuously as the potential barrier height increases, becoming inversely proportional to the square root of the barrier height when it is large enough. This behavior is universal as it is independent of the width and spacing of the barriers. The specific heat at constant volume shows a crossover from 3D to 2D when the height of the potential or the barrier width increases, in addition to the well-known peak related to the Bose-Einstein condensation. These features are due to the trapping of the bosons by the potential barriers and can be characterized by the energy difference between the energy bands below the potential height.

  1. Universal critical-like scaling of dynamic properties in symmetry-selected glass formers

    NASA Astrophysics Data System (ADS)

    Drozd-Rzoska, Aleksandra; Rzoska, Sylwester J.; Paluch, Marian

    2008-11-01

    Evidence for a possible general validity of the critical-like behavior of dielectric relaxation time or viscosity τ,η∝(T-TC)-ϕ with ϕ →9 and TCuniversal behavior is found in various systems where the vitrification is dominated by a selected element of symmetry. The supporting evidence was obtained on the basis of the distortion-sensitive, derivative-based analysis of τ(T ) data for a rodlike liquid crystalline compound (E7), orientationally disordered crystals (plastic crystals), a colloidal nanofluid system, polymer melt (polystyrene), oligomeric liquid (EPON 828), and low molecular weight glass formers (glycerol, threitol, sorbitol, and 1-propanol). Results presented explain the puzzling experimental artifacts supporting the dynamical scaling model [R. H. Colby, Phys. Rev. E 61, 1783 (2000); B. M. Erwin, R. H. Colby, J. Non-Cryst. Solids 307-310, 225 (2002)]. It is suggested that spin-glass-like systems may be linked to the discussed pattern.

  2. Critical exponents of dynamical conductivity in 2D percolative superconductor-insulator transitions: three universality classes

    NASA Astrophysics Data System (ADS)

    Karki, Pragalv; Loh, Yen Lee

    2016-11-01

    We simulate three types of random inductor-capacitor (LC) networks on 6000× 6000 square lattices. We calculate the dynamical conductivity using an equation-of-motion method in which timestep error is eliminated and windowing error is minimized. We extract the critical exponent a such that σ ≤ft(ω \\right)\\propto {ω-a} at low frequencies. The results suggest that there are three different universality classes. The {{L}ij}{{C}i} model, with capacitances from each site to ground, has a  =  0.314(4). The {{L}ij}{{C}ij} model, with capacitances along bonds, has a  =  0. The {{L}ij}{{C}i}{{C}ij} model, with both types of capacitances, has a  =  0.304(1). This implies that classical percolative 2D superconductor-insulator transitions (SITs) generically have σ ≤ft(ω \\right)\\to ∞ as ω \\to 0 . Therefore, any experiments that give a constant conductivity as ω \\to 0 must be explained in terms of quantum effects.

  3. SU (2) lattice gauge theory in 2 + 1 dimensions: Critical couplings from twisted boundary conditions and universality

    NASA Astrophysics Data System (ADS)

    Edwards, Sam R.; von Smekal, Lorenz

    2009-11-01

    We present a precision determination of the critical coupling βc for the deconfinement transition in pure SU (2) gauge theory in 2 + 1 dimensions. This is possible from universality, by intersecting the center vortex free energy as a function of the lattice coupling β with the exactly known value of the interface free energy in the 2D Ising model at criticality. The method allows us to find critical couplings with unprecedented numerical accuracy. Results for lattices with different numbers of sites Nt along the Euclidean time direction are used to determine how β varies with temperature for a given Nt around the deconfinement transition.

  4. The Effect of Stochastic Perturbation of Fuel Distribution on the Criticality of a One Speed Reactor and the Development of Multi-Material Multinomial Line Statistics

    NASA Technical Reports Server (NTRS)

    Jahshan, S. N.; Singleterry, R. C.

    2001-01-01

    The effect of random fuel redistribution on the eigenvalue of a one-speed reactor is investigated. An ensemble of such reactors that are identical to a homogeneous reference critical reactor except for the fissile isotope density distribution is constructed such that it meets a set of well-posed redistribution requirements. The average eigenvalue, , is evaluated when the total fissile loading per ensemble element, or realization, is conserved. The perturbation is proven to increase the reactor criticality on average when it is uniformly distributed. The various causes of the change in reactivity, and their relative effects are identified and ranked. From this, a path towards identifying the causes. and relative effects of reactivity fluctuations for the energy dependent problem is pointed to. The perturbation method of using multinomial distributions for representing the perturbed reactor is developed. This method has some advantages that can be of use in other stochastic problems. Finally, some of the features of this perturbation problem are related to other techniques that have been used for addressing similar problems.

  5. Carbon Sequestered, Carbon Displaced and the Kyoto Context

    SciTech Connect

    Marland, G.; Schlamadinger, B.

    1999-04-18

    The integrated system that embraces forest management, forest products, and land-use change impacts the global carbon cycle - and hence the net emission of the greenhouse gas carbon dioxide - in four fundamental ways. Carbon is stored in living and dead biomass, carbon is stored in wood products and landfills, forest products substitute in the market place for products made from other materials, and forest harvests can be used wholly or partially to displace fossil fuels in the energy sector. Implementation of the Kyoto Protocol to the United Nations Framework Convention on Climate Change would result in the creation of international markets for carbon dioxide emissions credits, but the current Kyoto text does not treat all carbon identically. We have developed a carbon accounting model, GORCAM, to examine a variety of scenarios for land management and the production of forest products. In this paper we explore, for two simple scenarios of forest management, the carbon flows that occur and how these might be accounted for under the Kyoto text. The Kyoto protocol raises questions about what activities can result in emissions credits, which carbon reservoirs will be counted, who will receive the credits, and how much credit will be available? The Kyoto Protocol would sometimes give credits for carbon sequestered, but it would always give credits when fossil-fuel carbon dioxide emissions are displaced.

  6. Magnetic latch trigger for inherent shutdown assembly

    DOEpatents

    Sowa, Edmund S.

    1976-01-01

    An inherent shutdown assembly for a nuclear reactor is provided. A neutron absorber is held ready to be inserted into the reactor core by a magnetic latch. The latch includes a magnet whose lines of force are linked by a yoke of material whose Curie point is at the critical temperature of the reactor at which the neutron absorber is to be inserted into the reactor core. The yoke is in contact with the core coolant or fissionable material so that when the coolant or the fissionable material increase in temperature above the Curie point the yoke loses its magnetic susceptibility and the magnetic link is broken, thereby causing the absorber to be released into the reactor core.

  7. Verification of the MCU precision code and ROSFOND neutron data in application to the calculations of criticality of fast reactors with highly enriched uranium

    SciTech Connect

    Alekseev, N. I.; Kalugin, M. A.; Kulakov, A. S.; Novosel’tsev, A. P.; Sergeev, G. S.; Shkarovskiy, D. A.; Yudkevich, M. S.

    2014-12-15

    Calculation of 335 critical assemblies (benchmark experiments) with the core of highly enriched uranium and reflectors of various materials is performed. The statistical analysis of the results shows that, for all 16 materials studied, the absolute value of the most probable deviation of the calculated value of K{sub eff} from the experimental one does not exceed 0.005.

  8. Predicting Critical Thinking Skills of University Students through Metacognitive Self-Regulation Skills and Chemistry Self-Efficacy

    ERIC Educational Resources Information Center

    Uzuntiryaki-Kondakci, Esen; Capa-Aydin, Yesim

    2013-01-01

    This study aimed at examining the extent to which metacognitive self-regulation and chemistry self-efficacy predicted critical thinking. Three hundred sixty-five university students participated in the study. Data were collected using appropriate dimensions of Motivated Strategies for Learning Questionnaire and College Chemistry Self-Efficacy…

  9. Why Most American Universities Have Given up on Human Purpose and Meaning: A Critical Exploration of the Historical Story

    ERIC Educational Resources Information Center

    Glanzer, Perry L.; Hill, Jonathan P.

    2013-01-01

    Recent scholarship claims that American colleges and universities give less and less attention to the meaning of life. In this article we critically evaluate the historical arguments for this claim, focusing primarily on the account given by Anthony Kronman. We argue that Kronman's history proves particularly problematic if one wants to…

  10. Critical Success Factors in the Curriculum Alignment Process: The Case of the College of Business at Abu Dhabi University

    ERIC Educational Resources Information Center

    Camba, Pitzel; Krotov, Vlad

    2015-01-01

    The main goals of this article are to (a) assist business schools in understanding the curriculum alignment process, and (b) uncover critical success factors in curriculum alignment. Based on a case study conducted at the College of Business at Abu Dhabi University, a detailed curriculum alignment process description is provided. The process…

  11. Water/sand flooded and immersed critical experiment and analysis performed in support of the TOPAZ-II Safety Program

    SciTech Connect

    Glushkov, E.S.; Ponomarev-Stepnoi, N.N.; Bubelev, V.G.; Garin, V.P.; Gomin, E.A.; Kompanietz, G.V.; Krutoy, A.M.; Lobynstev, V.A.; Maiorov, L.V.; Polyakov, D.N.

    1994-11-01

    Presented is a brief description of the Narciss-M2 critical assemblies, which simulate accidental water/wet-sand immersion of the TOPAZ-II reactor as well as water-flooding of core cavities. Experimental results obtained from these critical assemblies, including experiments with several fuel elements removed from the core, are shown. These configurations with several extracted fuel elements simulate a proposed fuel-out anticriticality-device modification to the TOPAZ-II reactor. Preliminary computational analysis of these experiments using the Monte Carlo neutron-transport method is outlined. Nuclear criticality safety of the TOPAZ-II reactor with an incorporated anticriticality unit is demonstrated.

  12. Accident Analyses for Conversion of the University of Missouri Research Reactor (MURR) from Highly-Enriched to Low-Enriched Uranium

    SciTech Connect

    Stillman, J. A.; Feldman, E. E.; Wilson, E. H.; Foyto, L. P.; Kutikkad, K.; McKibben, J. C.; Peters, N. J.; Cowherd, W. M.; Rickman, B.

    2014-12-01

    This report contains the results of reactor accident analyses for the University of Missouri Research Reactor (MURR). The calculations were performed as part of the conversion from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL), the MURR Facility, and the Nuclear Engineering Program – College of Engineering, University of Missouri-Columbia. The core conversion to LEU is being performed with financial support from the U. S. government. This report contains the results of reactor accident analyses for the University of Missouri Research Reactor (MURR). The calculations were performed as part of the conversion from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL), the MURR Facility, and the Nuclear Engineering Program – College of Engineering, University of Missouri-Columbia. The core conversion to LEU is being performed with financial support from the U. S. government. In the framework of non-proliferation policies, the international community presently aims to minimize the amount of nuclear material available that could be used for nuclear weapons. In this geopolitical context most research and test reactors, both domestic and international, have started a program of conversion to the use of LEU fuel. A new type of LEU fuel based on an alloy of uranium and molybdenum (U-Mo) is expected to allow the conversion of U.S. domestic high performance reactors like MURR. This report presents the results of a study of core behavior under a set of accident conditions for MURR cores fueled with HEU U-Alx dispersion fuel or LEU monolithic U-Mo alloy fuel with 10 wt% Mo

  13. Renormalization group calculation of the universal critical exponents of a polymer molecule

    NASA Astrophysics Data System (ADS)

    Belohorec, Peter

    In this work the excluded volume problem of a linear flexible polymer molecule in a solution was investigated using a new method. The Domb-Joyce (DJ) lattice model (Domb C. and Joyce G. S. (1972). J. Phys. C: Solid State Phys. 5 956) was used to describe the polymer chain with a varying excluded volume parameterramateur w and bond number N. Monte Carlo (MC) generated data for the mean square end-to-end distance Rsbsp{N}{2} and the second virial coefficient Asb{2,N} were analyzed by a renormalization group technique that is a generalization of the one-parameter recursion model (Nickel B. G. (1991). Macromolecules 24, 1358). By defining the effective exponents nusb{R}(N,psi) and nusb{A}(N,psi ) using 2sp{2nusb{R}} = Rsbsp{2N}{2}/Rsbsp{N}{2} and 2sp{3nusb{A}} = Asb{2,2N}/Asb{2,N} where psi = {1/4}({6/pi})sp{3/2}{{Asb{2,N}}/{Rsbsp{N}{3}}} is the interpenetration function, the corrections varying as Nsp{-Delta} were eliminated from nusb{R}(N,psi) and nusb{A}(N,psi) and both universal critical exponents nu and Delta of the expected long chain behaviors Rsbsp{N}{2}~ asb{R}Nsp{2nu}(1 + bsb{R}Nsp{-Delta} +\\...) and Asb{2,N}~ asb{A}Nsp{3nu}(1 + bsb{A}Nsp{-Delta} +\\...) were determined very accurately. The problems encountered by standard methods when extracting the values of the leading exponent nu and the correction to scaling exponent Delta from the finite chain data were eliminated by the simultaneous use of many models (i.e., w in the range of 0 < omega ≤ 1) and by the use of the effective exponent transformation. Other universal quantities such as the asymptotic value psi* of the interpenetration function proportional to the dimensionless ratio of leading scaling amplitudes asb{A}/asbsp{R}{3/2} as well as the ratio of correction to scaling amplitudes bsb{A}/bsb{R} were also calculated with a very good precision. The results are nu = 0.58756(5),\\ Delta = 0.5310(33), psi* = 0.23221(11) and bsb{A}/bsb{R} = -.0.9028(132). The numerical solution of the DJ model

  14. Criticality Calculations of Fresh LEU and MOX Assemblies for Transport and Storage at the Balakovo Nuclear Power Plant

    SciTech Connect

    Goluoglu, S.

    2001-01-11

    Transportation of low-enriched uranium (LEU) and mixed-oxide (MOX) assemblies to and within the VVER-1000-type Balakovo Nuclear Power Plant is investigated. Effective multiplication factors for fresh fuel assemblies on the railroad platform, fresh fuel assemblies in the fuel transportation vehicle, and fresh fuel assemblies in the spent fuel storage pool are calculated. If there is no absorber between the units, the configurations with all MOX assemblies result in higher effective multiplication factors than the configurations with all LEU assemblies when the system is dry. When the system is flooded, the configurations with all LEU assemblies result in higher effective multiplication factors. For normal operating conditions, effective multiplication factors for all configurations are below the presumed upper subcritical limit of 0.95. For an accident condition of a fully loaded fuel transportation vehicle that is flooded with low-density water (possibly from a fire suppression system), the presumed upper subcritical limit is exceeded by configurations containing LEU assemblies.

  15. The Governance of University Knowledge Transfer: A Critical Review of the Literature

    ERIC Educational Resources Information Center

    Geuna, Aldo; Muscio, Alessandro

    2009-01-01

    Universities have long been involved in knowledge transfer activities. Yet the last 30 years have seen major changes in the governance of university-industry interactions. Knowledge transfer has become a strategic issue: as a source of funding for university research and (rightly or wrongly) as a policy tool for economic development. Universities…

  16. Scientific design of Purdue University Multi-Dimensional Integral Test Assembly (PUMA) for GE SBWR

    SciTech Connect

    Ishii, M.; Ravankar, S.T.; Dowlati, R.

    1996-04-01

    The scaled facility design was based on the three level scaling method; the first level is based on the well established approach obtained from the integral response function, namely integral scaling. This level insures that the stead-state as well as dynamic characteristics of the loops are scaled properly. The second level scaling is for the boundary flow of mass and energy between components; this insures that the flow and inventory are scaled correctly. The third level is focused on key local phenomena and constitutive relations. The facility has 1/4 height and 1/100 area ratio scaling; this corresponds to the volume scale of 1/400. Power scaling is 1/200 based on the integral scaling. The time will run twice faster in the model as predicted by the present scaling method. PUMA is scaled for full pressure and is intended to operate at and below 150 psia following scram. The facility models all the major components of SBWR (Simplified Boiling Water Reactor), safety and non-safety systems of importance to the transients. The model component designs and detailed instrumentations are presented in this report.

  17. Critical field of two-dimensional superconducting Sn{sub 1-x}/Si{sub x} bimetallic composite cluster assembled films with energetic cluster impact deposition

    SciTech Connect

    Kurokawa, Yuichiro; Hihara, Takehiko; Ichinose, Ikuo

    2013-05-07

    Sn{sub 1-x}/Si{sub x} cluster assembled films have been prepared by an energetic cluster impact deposition using a plasma-gas-condensation cluster beam deposition apparatus. Transmission electron microscope images indicated that individual clusters have composite morphologies, where Sn and Si were separated from each other. The superconducting critical magnetic fields, H{sub c}, of Sn{sub 1-x}/Si{sub x} cluster assembled films were measured and found to be much higher than the critical magnetic field of the bulk Sn. We estimated the H{sub c} values by using a theory of the superconducting thin film. The estimated values are in good agreement with the experiments, indicating that the Sn{sub 1-x}/Si{sub x} cluster assembled films can be regarded as a two-dimensional system although thickness, t, of Sn{sub 1-x}/Si{sub x} cluster assembled films (t Almost-Equal-To 1000 nm) is thicker than conventional superconducting thin film (t < 100 nm).

  18. Ultracold neutron source at the PULSTAR reactor: Engineering design and cryogenic testing

    NASA Astrophysics Data System (ADS)

    Korobkina, E.; Medlin, G.; Wehring, B.; Hawari, A. I.; Huffman, P. R.; Young, A. R.; Beaumont, B.; Palmquist, G.

    2014-12-01

    Construction is completed and commissioning is in progress for an ultracold neutron (UCN) source at the PULSTAR reactor on the campus of North Carolina State University. The source utilizes two stages of neutron moderation, one in heavy water at room temperature and the other in solid methane at ~ 40 K, followed by a converter stage, solid deuterium at 5 K, that allows a single down scattering of cold neutrons to provide UCN. The UCN source rolls into the thermal column enclosure of the PULSTAR reactor, where neutrons will be delivered from a bare face of the reactor core by streaming through a graphite-lined assembly. The source infrastructure, i.e., graphite-lined assembly, heavy-water system, gas handling system, and helium liquefier cooling system, has been tested and all systems operate as predicted. The research program being considered for the PULSTAR UCN source includes the physics of UCN production, fundamental particle physics, and material surface studies of nanolayers containing hydrogen. In the present paper we report details of the engineering and cryogenic design of the facility as well as results of critical commissioning tests without neutrons.

  19. Status of reduced enrichment programs for research reactors in Japan

    SciTech Connect

    Kanda, Keiji; Nishihara, Hedeaki; Shirai, Eiji; Oyamada, Rokuro; Sanokawa, Konomo

    1997-08-01

    The reduced enrichment programs for the JRR-2, JRR-3, JRR-4 and JMTR of Japan Atomic Energy Research Institute (JAERI), and the KUR of Kyoto University Research Reactor Institute (KURRI) have been partially completed and are mostly still in progress under the Joint Study Programs with Argonne National Laboratory (ANL). The JMTR and JRR-2 have been already converted to use MEU aluminide fuels in 1986 and 1987, respectively. The operation of the upgraded JRR-3(JRR-3M) has started in March 1990 with the LEU aluminide fuels. Since May 1992, the two elements have been inserted in the KUR. The safety review application for the full core conversion to use LEU silicide in the JMTR was approved in February 1992 and the conversion has been done in January 1994. The Japanese Government approved a cancellation of the KUHFR Project in February 1991, and in April 1994 the U.S. Government gave an approval to utilize HEU in the KUR instead of the KUHFR. Therefore, the KUR will be operated with HEU fuel until 2001. Since March 1994, Kyoto University is continuing negotiation with UKAEA Dounreay on spent fuel reprocessing and blending down of recovered uranium, in addition to that with USDOE.

  20. Development of a Safeguards Verification Method and Instrument to Detect Pin Diversion from Pressurized Water Reactor (PWR) Spent Fuel Assemblies Phase I Study

    SciTech Connect

    Ham, Y S; Sitaraman, S

    2008-12-24

    A novel methodology to detect diversion of spent fuel from Pressurized Water Reactors (PWR) has been developed in order to address a long unsolved safeguards verification problem for international safeguards community such as International Atomic Energy Agency (IAEA) or European Atomic Energy Community (EURATOM). The concept involves inserting tiny neutron and gamma detectors into the guide tubes of a spent fuel assembly and measuring the signals. The guide tubes form a quadrant symmetric pattern in the various PWR fuel product lines and the neutron and gamma signals from these various locations are processed to obtain a unique signature for an undisturbed fuel assembly. Signatures based on the neutron and gamma signals individually or in a combination can be developed. Removal of fuel pins from the assembly will cause the signatures to be visibly perturbed thus enabling the detection of diversion. All of the required signal processing to obtain signatures can be performed on standard laptop computers. Monte Carlo simulation studies and a set of controlled experiments with actual commercial PWR spent fuel assemblies were performed and validated this novel methodology. Based on the simulation studies and benchmarking measurements, the methodology developed promises to be a powerful and practical way to detect partial defects that constitute 10% or more of the total active fuel pins. This far exceeds the detection threshold of 50% missing pins from a spent fuel assembly, a threshold defined by the IAEA Safeguards Criteria. The methodology does not rely on any operator provided data like burnup or cooling time and does not require movement of the fuel assembly from the storage rack in the spent fuel pool. A concept was developed to build a practical field device, Partial Defect Detector (PDET), which will be completely portable and will use standard radiation measuring devices already in use at the IAEA. The use of the device will not require any information provided