Science.gov

Sample records for ans advanced neutron

  1. The advanced neutron source reactor: An overview

    SciTech Connect

    West, C.D.

    1990-01-01

    The Advanced Neutron Source (ANS) will be a new user facility for all kinds of neutron research, including neutron scattering, materials testing, materials analysis, isotope production and nuclear physics experiments. The centerpiece of the facility is to be the world's highest flux beam reactor. There will be beams of hot, cold and thermal neutrons for more than 40 simultaneous scattering and nuclear physics experiments. In addition, there will be irradiation positions and rabbit tubes for in-pile experiments, testing and isotopes production (including transuranium isotopes). To reduce technical risks and to minimize safety issues, the reactor design is based on technology already employed in existing research reactors. The fuel elements are annular assemblies of aluminum clad involute fuel plates, similar to the design of the High Flux Isotope Reactor (HFIR) at Oak Ridge and the Institut Laue-Langevin (ILL) Reactor in Grenoble. As is common with many other research reactors, the core is cooled, moderated and reflected by heavy water. The preferred fuel is U{sub 3}Si{sub 2} - a high-density fuel form developed by Argonne National Laboratory and Babcock and Wilcox that has been extensively tested in reactors in the United States, Europe and Japan. 7 figs., 2 tabs.

  2. Advanced Neutron Source (ANS) Project progress report

    SciTech Connect

    McBee, M.R.; Chance, C.M. ); Selby, D.L.; Harrington, R.M.; Peretz, F.J. )

    1990-04-01

    This report discusses the following topics on the advanced neutron source: quality assurance (QA) program; reactor core development; fuel element specification; corrosion loop tests and analyses; thermal-hydraulic loop tests; reactor control concepts; critical and subcritical experiments; material data, structural tests, and analysis; cold source development; beam tube, guide, and instrument development; hot source development; neutron transport and shielding; I C research and development; facility concepts; design; and safety.

  3. An advanced neutron spectrometer for future manned exploration missions

    NASA Astrophysics Data System (ADS)

    Christl, Mark

    An Advanced Neutron Spectrometer (ANS) is being developed to support future manned exploration missions. This new instrument uses a refined gate and capture technique that significantly improves the identification of neutrons in mixed radiation fields found in spacecraft, habitats and on planetary surfaces. The new instrument is a composite scintillator comprised of PVT loaded with lithium-6 glass scintillators. We will describe the detection concept and show preliminary results from laboratory tests and exposures at particle accelerators.

  4. An Advanced Neutron Spectrometer for Future Manned Exploration Missions

    NASA Technical Reports Server (NTRS)

    Christl, Mark; Apple, Jeffrey A.; Cox, Mark D.; Dietz, Kurtis L.; Dobson, Christopher C.; Gibson, Brian F.; Howard, David E.; Jackson, Amanda C.; Kayatin, Mathew J.; Kuznetsov, Evgeny N.; Norwood, Joseph K.; Merril, Garrick W.; Watts, John W.; Sabra, Mohammad S.; Smith, Dennis A.; Rodriquez-Otero, Miguel A.

    2014-01-01

    An Advanced Neutron Spectrometer (ANS) is being developed to support future manned exploration missions. This new instrument uses a refined gate and capture technique that significantly improves the identification of neutrons in mixed radiation fields found in spacecraft, habitats and on planetary surfaces. The new instrument is a composite scintillator comprised of PVT loaded with litium-6 glass scintillators. We will describe the detection concept and show preliminary results from laboratory tests and exposures at particle accelerators

  5. Review of the Advanced Neutron Source (ANS) materials irradiation facilities

    SciTech Connect

    Goland, A.N. )

    1991-03-01

    The purpose of the workshop was to document as accurately as possible the present and future needs for neutron irradiation capacity and facilities as related to the design of the Advanced Neutron Source (ANS) which will be the next generation steady-state research reactor. The report provides the findings and recommendations of the working group. After introductory and background information is presented, the discussion includes the status of the ANS design, in particular in-core materials irradiation facilities design and important experimental parameters. The summary of workshop discussions describes a survey of irradiation-effects research community and opportunities for ex-core irradiation facilities. 20 refs., 2 figs., 4 tabs. (MHB)

  6. Advanced Neutron Source (ANS) Project progress report, FY 1994

    SciTech Connect

    Campbell, J.H.; King-Jones, K.H.; Selby, D.L.; Harrington, R.M.; Thompson, P.B.

    1995-01-01

    The President`s budget request for FY 1994 included a construction project for the Advanced Neutron Source (ANS). However, the budget that emerged from the Congress did not, and so activities during this reporting period were limited to continued research and development and to advanced conceptual design. A significant effort was devoted to a study, requested by the US Department of Energy (DOE) and led by Brookhaven National Laboratory, of the performance and cost impacts of reducing the uranium fuel enrichment below the baseline design value of 93%. The study also considered alternative core designs that might mitigate those impacts. The ANS Project proposed a modified core design, with three fuel elements instead of two, that would allow operation with only 50% enriched uranium and use existing fuel technology. The performance penalty would be 15--20% loss of thermal neutron flux; the flux would still just meet the minimum design requirement set by the user community. At the time of this writing, DOE has not established an enrichment level for ANS, but two advisory committees have recommended adopting the new core design, provided the minimum flux requirements are still met.

  7. Advanced Neutron Source (ANS) Project Progress report, FY 1991

    SciTech Connect

    Campbell, J.H. ); Selby, D.L.; Harrington, R.M. ); Thompson, P.B. . Engineering Division)

    1992-01-01

    This report discusses the following about the Advanced Neutron Source: Project Management; Research and Development; Fuel Development; Corrosion Loop Tests and Analyses; Thermal-Hydraulic Loop Tests; Reactor Control and Shutdown Concepts; Critical and Subcritical Experiments; Material Data, Structural Tests, and Analysis; Cold-Source Development; Beam Tube, Guide, and Instrument Development; Hot-Source Development; Neutron Transport and Shielding; I C Research and Development; Design; and Safety.

  8. Advanced Neutron Source (ANS) Project Progress report, FY 1991

    SciTech Connect

    Campbell, J.H.; Selby, D.L.; Harrington, R.M.; Thompson, P.B.

    1992-01-01

    This report discusses the following about the Advanced Neutron Source: Project Management; Research and Development; Fuel Development; Corrosion Loop Tests and Analyses; Thermal-Hydraulic Loop Tests; Reactor Control and Shutdown Concepts; Critical and Subcritical Experiments; Material Data, Structural Tests, and Analysis; Cold-Source Development; Beam Tube, Guide, and Instrument Development; Hot-Source Development; Neutron Transport and Shielding; I & C Research and Development; Design; and Safety.

  9. CHARACTERIZATION OF AN ADVANCED GADOLINIUM NEUTRON ABSORBER ALLOY BY MEANS OF NEUTRON TRANSMISSION

    SciTech Connect

    Gregg W. Wachs

    2007-09-01

    Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the alloy at specific gadolinium dopant levels. The new alloy is to be deployed for criticality control of highly enriched DOE SNF. For the transmission experiments, alloy test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using only radiative capture cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium poison and in addition, verified the measured elemental composition of the alloy test samples. The good agreement also indirectly confirmed that the gadolinium was dispersed fairly uniformly in the alloy and the ENDF VII radiative capture cross section data were accurate.

  10. Advanced Neutron Source (ANS) Project: Annual report, April 1987--March 1988

    SciTech Connect

    Selby, D.L.; Harrington, R.M.; Peretz, F.J.; McBee, M.R.

    1989-02-01

    The Advanced Neutron Source (ANS) Project (formerly called the Center for Neutron Research) will provide the world's best facilities for the study of neutron scattering. The ANS high-power density reactor will be fueled with uranium silicide and cooled, moderated, and reflected by deuterium oxide. Peak neutron fluxes in the reflector are expected to be 5 to 10 x 10/sup 19/ neutrons/center dot/m/sup -2//center dot/s/sup -1/ with a power level between 270 and 300 MW. This report describes the status of technical work funded through the ANS Project during the period April 1987 through March 1988. Earlier work is described in Center for Neutron Research Project Status Report and other Oak Ridge National Laboratory reports. 22 refs., 57 figs., 23 tabs.

  11. The Advanced Neutron Source (ANS) project: A world-class research reactor facility

    SciTech Connect

    Thompson, P.B.; Meek, W.E.

    1993-07-01

    This paper provides an overview of the Advanced Neutron Source (ANS), a new research facility being designed at Oak Ridge National Laboratory. The facility is based on a 330 MW, heavy-water cooled and reflected reactor as the neutron source, with a thermal neutron flux of about 7.5{times}10{sup 19}m{sup {minus}2}{center_dot}sec{sup {minus}1}. Within the reflector region will be one hot source which will serve 2 hot neutron beam tubes, two cryogenic cold sources serving fourteen cold neutron beam tubes, two very cold beam tubes, and seven thermal neutron beam tubes. In addition there will be ten positions for materials irradiation experiments, five of them instrumented. The paper touches on the project status, safety concerns, cost estimates and scheduling, a description of the site, the reactor, and the arrangements of the facilities.

  12. Advanced Neutron Source Cross Section Libraries (ANSL-V): ENDF/B-V based multigroup cross-section libraries for advanced neutron source (ANS) reactor studies

    SciTech Connect

    Ford, W.E. III; Arwood, J.W.; Greene, N.M.; Moses, D.L.; Petrie, L.M.; Primm, R.T. III; Slater, C.O.; Westfall, R.M.; Wright, R.Q.

    1990-09-01

    Pseudo-problem-independent, multigroup cross-section libraries were generated to support Advanced Neutron Source (ANS) Reactor design studies. The ANS is a proposed reactor which would be fueled with highly enriched uranium and cooled with heavy water. The libraries, designated ANSL-V (Advanced Neutron Source Cross Section Libraries based on ENDF/B-V), are data bases in AMPX master format for subsequent generation of problem-dependent cross-sections for use with codes such as KENO, ANISN, XSDRNPM, VENTURE, DOT, DORT, TORT, and MORSE. Included in ANSL-V are 99-group and 39-group neutron, 39-neutron-group 44-gamma-ray-group secondary gamma-ray production (SGRP), 44-group gamma-ray interaction (GRI), and coupled, 39-neutron group 44-gamma-ray group (CNG) cross-section libraries. The neutron and SGRP libraries were generated primarily from ENDF/B-V data; the GRI library was generated from DLC-99/HUGO data, which is recognized as the ENDF/B-V photon interaction data. Modules from the AMPX and NJOY systems were used to process the multigroup data. Validity of selected data from the fine- and broad-group neutron libraries was satisfactorily tested in performance parameter calculations.

  13. Radiation transport calculations for the ANS (Advanced Neutron Source) beam tubes

    SciTech Connect

    Engle, W.W., Jr.; Lillie, R.A.; Slater, C.O.

    1988-01-01

    The Advanced Neutron Source facility (ANS) will incorporate a large number of both radial and no-line-of-sight (NLS) beam tubes to provide very large thermal neutron fluxes to experimental facilities. The purpose of this work was to obtain comparisons for the ANS single- and split-core designs of the thermal and damage neutron and gamma-ray scalar fluxes in these beams tubes. For experimental locations far from the reactor cores, angular flux data are required; however, for close-in experimental locations, the scalar fluxes within each beam tube provide a credible estimate of the various signal to noise ratios. In this paper, the coupled two- and three-dimensional radiation transport calculations employed to estimate the scalar neutron and gamma-ray fluxes will be described and the results from these calculations will be discussed. 6 refs., 2 figs.

  14. ORNL contributions to the Advanced Neutron Source (ANS) Project for October 1986-March 1987

    SciTech Connect

    Selby, D.L.; Harrington, R.M.; Peretz, F.J.

    1987-11-01

    The Advanced Neutron Source (ANS) Facility - formerly called the Center for Neutron Research - will provide the world's best facilities for the study of neutron scattering. The ANS high power density reactor will be fueled with uranium silicide and cooled, moderated, and reflected by D/sub 2/O. Peak neutron fluxes in the reflector are expected to be 5 to 10 x 10/sup 19/ neutrons per square meter with a power level between 270 MW and 300 MW. This report describes the status of technical work at ORNL on the ANS Project during the first half of FY 1987. The scope of this report includes Research and Development Tasks; Safety Tasks; Conceptual Design Tasks; and Project Support. The last two areas were only initiated as separate activities during this reporting period. Technical highlights include a better understanding of the relationship among neutron flux, core power, and core volume; preconceptual design work on a cold source for use in a very high gamma and neutron flux environment; identification of the major applicable safety rules and guidelines; and establishment of initial functional objectives for the containment structure.

  15. Advanced Neutron Source (ANS) Project. Progress report FY 1993

    SciTech Connect

    Campbell, J.H.; Selby, D.L.; Harrington, R.M.; Thompson, P.B.

    1994-01-01

    This report covers the progress made in 1993 in the following sections: (1) project management; (2) research and development; (3) design and (4) safety. The section on research and development covers the following: (1) reactor core development; (2) fuel development; (3) corrosion loop tests and analysis; (4) thermal-hydraulic loop tests; (5) reactor control and shutdown concepts; (6) critical and subcritical experiments; (7) material data, structure tests, and analysis; (8) cold source development; (9) beam tube, guide, and instrument development; (10) neutron transport and shielding; (11) I and C research and development; and (12) facility concepts.

  16. An examination of the elastic structural response of the Advanced Neutron Source fuel plates

    SciTech Connect

    Swinson, W.F.; Luttrell, C.R.; Yahr, G.T.

    1994-09-01

    Procedures for evaluating the elastic structural response of the Advanced Neutron Source (ANS) fuel plates to coolant flow and to temperature variations are presented in this report. Calculations are made that predict the maximum deflection and the maximum stress for a representative plate from the upper and from the lower fuel elements.

  17. Wetlands Assessment for site characterization, Advanced Neutron Source (ANS)

    SciTech Connect

    Wade, M.C.; Socolof, M.L.; Rosensteel, B.; Awl, D.

    1994-10-01

    This Wetlands Assessment has been prepared in accordance with the Department of Energy`s (DOE) Code of Federal Regulations (CFR) 10 CFR 1022, Compliance with Floodplain/Wetlands Environmental Review Requirements, which established the policy and procedure for implementing Executive Order 11990, Protection of Wetlands. The proposed action is to conduct characterization activities in or near wetlands at the ANS site. The proposed action will covered under a Categorical Exclusion, therefore this assessment is being prepared as a separate document [10 CFR 1022.12(c)]. The purpose of this Wetlands Assessment is to fulfill the requirements of 10 CFR 1022.12(a) by describing the project, discussing the effects of the proposed action upon the wetlands, and considering alternatives to the proposed action.

  18. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  19. Report of the Advanced Neutron Source (ANS) safety workshop, Knoxville, Tennessee, October 25--26, 1988

    SciTech Connect

    Buchanan, J.R.; Dumont, J.N.; Kendrick, C.M.; Row, T.H.; Thompson, P.B.; West, C.D.; Marchaterre, J.F.; Muhlheim, M.D.; McBee, M.R.

    1988-12-01

    On October 25--26, 1988, about 60 people took part in an Advanced Neutron Source (ANS) Safety Workshop, organized in cooperation with the Oak Ridge Operations (ORO) Office of the Department of Energy (DOE) and held in Knoxville, Tennessee. After a plenary session at which ANS Project staff presented status reports on the ANS design, research and development (R and D), and safety analysis efforts, the workshop broke into three working groups, each covering a different topic: Environmental and Waste Management, Applicable Regulatory Safety Criteria and Goals, and Reactor Concepts. Each group was asked to review the Project's approach to safety-related issues and to provide guidance on future reactor safety needs or directions for the Project. With the help of able chairmen, assisted by reporters and secretarial support, the working groups were extremely successful. Draft reports from each group were prepared before the workshop closed, and the major findings of each group were presented for review and discussion by the entire workshop attendance. This report contains the final version of the group reports, incorporating the results of the overall review by all the workshop participants.

  20. Advanced Neutron Spectrometer

    NASA Technical Reports Server (NTRS)

    Christl, Mark; Dobson, Chris; Norwood, Joseph; Kayatin, Matthew; Apple, Jeff; Gibson, Brian; Dietz, Kurt; Benson, Carl; Smith, Dennis; Howard, David; Rodriquez, Miguel; Watts, John; Sabra, Mohammed; Kuznetsov, Evgeny

    2013-01-01

    Energetic neutron measurements remain a challenge for space science investigations and radiation monitoring for human exploration beyond LEO. We are investigating a new composite scintillator design that uses Li6 glass scintillator embedded in a PVT block. A comparison between Li6 and Boron 10 loaded scintillators are being studied to assess the advantages and shortcomings of these two techniques. We present the details of the new Li6 design and results from the comparison of the B10 and Li6 techniques during exposures in a mixed radiation field produced by high energy protons interacting in a target material.

  1. Advanced Neutron Source (ANS) regulatory requirements and safety-related considerations: August 1988 Draft

    SciTech Connect

    Harrington, R.M.; Flanagan, C.A.

    1988-08-01

    The purpose of this document is to outline the safety-related considerations for Advanced Neutron Source (ANS) and, by so doing, to indicate the regulatory requirements and design considerations that must be addressed by the project in the design and during subsequent operations. As such, this document represents a road map of how the project intends to analyze and document nuclear safety concerns and design considerations that will have to be addressed by the ANS Project. As the project matures and the design becomes better defined and projected performance better understood, the safety-related considerations will also become better defined and interpreted. Appropriate safety-related analyses and documentation will be produced (e.g., preliminary and final safety analysis reports). This document summarizes the sources of applicable regulatory requirements, indicates recent policy guidance from the NRC, provides the NRC general design criteria that must be met, suggests which of the major ANS systems components are likely to be categorized as ''safety related,'' and provides descriptive material that is of safety interest and importance.

  2. Recent Advances in Neutron Physics

    ERIC Educational Resources Information Center

    Feshbach, Herman; Sheldon, Eric

    1977-01-01

    Discusses new studies in neutron physics within the last decade, such as ultracold neutrons, neutron bottles, resonance behavior, subthreshold fission, doubly radiative capture, and neutron stars. (MLH)

  3. Integrating advanced materials simulation techniques into an automated data analysis workflow at the Spallation Neutron Source

    SciTech Connect

    Borreguero Calvo, Jose M; Campbell, Stuart I; Delaire, Olivier A; Doucet, Mathieu; Goswami, Monojoy; Hagen, Mark E; Lynch, Vickie E; Proffen, Thomas E; Ren, Shelly; Savici, Andrei T; Sumpter, Bobby G

    2014-01-01

    This presentation will review developments on the integration of advanced modeling and simulation techniques into the analysis step of experimental data obtained at the Spallation Neutron Source. A workflow framework for the purpose of refining molecular mechanics force-fields against quasi-elastic neutron scattering data is presented. The workflow combines software components to submit model simulations to remote high performance computers, a message broker interface for communications between the optimizer engine and the simulation production step, and tools to convolve the simulated data with the experimental resolution. A test application shows the correction to a popular fixed-charge water model in order to account polarization effects due to the presence of solvated ions. Future enhancements to the refinement workflow are discussed. This work is funded through the DOE Center for Accelerating Materials Modeling.

  4. Operator role definition: An initial step in the human factors engineering design of the advanced neutron source (ANS)

    SciTech Connect

    Knee, H.E.; Spelt, P.F.; Houser, M.M.; Hill, W.E.

    1994-12-31

    The Advanced Neutron Source (ANS) is a new basic and applied research facility sponsored by the U.S. Department of Energy that is proposed for construction. It will provide neutron beams for measurements and experiments in the fields of materials science and engineering, biology, chemistry, materials analysis, and nuclear science. The facility will provide a useful neutron beam flux that is at least five times more than is available at the world`s best existing facilities. It will also provide world-class facilities for isotopes production, materials irradiation testing, materials analysis, and the production of positrons. ANS will be unique in the United States in the extent to which human factors engineering (HFE) principles will be included in its design and construction. Initial HFE accomplishments include the development of a functional analysis, an operating philosophy, and a program plan. In fiscal year 1994, HFE activities are focusing on the role of the ANS control room reactor operator (RO). An operator-centered control room model was used in conjunction with information gathered from existing ANS system design descriptions and other literature to define RO responsibilities. From this list, a survey instrument was developed and administered to ANS design engineers, operations management personnel at Oak Ridge National Laboratory`s High Flux Isotope Reactor (HFIR), and HFIR ROs to detail the nature of the RO position. Initial results indicated that the RO should function as a high-level system supervisor with considerable monitoring, verification, and communication responsibilities. The relatively high level of control automation has resulted in a reshaping of the RO`s traditional safety and investment protection roles.

  5. Analyses of the reflector tank, cold source, and beam tube cooling for ANS reactor. [Advanced Neutron Source (ANS)

    SciTech Connect

    Marland, S. )

    1992-07-01

    This report describes my work as an intern with Martin Marietta Energy Systems, Inc., in the summer of 1991. I was assigned to the Reactor Technology Engineering Department, working on the Advanced Neutron Source (ANS). My first project was to select and analyze sealing systems for the top of the diverter/reflector tank. This involved investigating various metal seals and calculating the forces necessary to maintain an adequate seal. The force calculations led to an analysis of several bolt patterns and lockring concepts that could be used to maintain a seal on the vessel. Another project involved some pressure vessel stress calculations and the calculation of the center of gravity for the cold source assembly. I also completed some sketches of possible cooling channel patterns for the inner vessel of the cold source. In addition, I worked on some thermal design analyses for the reflector tank and beam tubes, including heat transfer calculations and assisting in Patran and Pthermal analyses. To supplement the ANS work, I worked on other projects. I completed some stress/deflection analyses on several different beams. These analyses were done with the aid of CAASE, a beam-analysis software package. An additional project involved bending analysis on a carbon removal system. This study was done to find the deflection of a complex-shaped beam when loaded with a full waste can.

  6. Characterization of core debris/concrete interactions for the Advanced Neutron Source. ANS Severe Accident Analysis Program

    SciTech Connect

    Hyman, C.R.; Taleyarkhan, R.P.

    1992-02-01

    This report provides the results of a recent study conducted to explore the molten core/concrete interaction (MCCI) issue for the Advanced Neutron Source (ANS). The need for such a study arises from the potential threats to reactor system integrity posed by MCCI. These threats include direct attack of the concrete basemat of the containment; generation and release of large quantities of gas that can pressurize the containment; the combustion threat of these gases; and the potential generation, release, and transport of radioactive aerosols to the environment.

  7. A 14-MeV Intense Neutron Source Based on Muon-Catalyzed Fusion - I: An Advanced Design

    SciTech Connect

    Anisimov, Viatcheslav V.; Arkhangel'sky, Vladimir A.; Ganchuk, Nikolay S.; Yukhimchuk, Arkady A.; Cavalleri, Emanuela; Karmanov, Fedor I.; Konobeyev, Alexander Yu.; Slobodtchouk, Victor I.; Latysheva, Lioudmila N.; Pshenichnov, Igor A.; Ponomarev, Leonid I.; Vecchi, Marcello

    2001-03-15

    The results of the design study of an advanced scheme for the 14-MeV intense neutron source based on muon-catalyzed fusion ({mu}CF) are presented. A pion production target (liquid lithium) and a synthesizer [liquid deuterium-tritium (D-T) mixture] are considered. Negative pions are produced inside a 17/7 T magnetic field by an intense (2-GeV,12-mA) deuteron beam interacting with the 150-cm-long, 0.75-cm-radius lithium target. Muons from the pion decay are collected in the backward direction and stopped in the D-T mixture of the synthesizer. The synthesizer has the shape of a 10-cm-radius sphere surrounded by two 0.03-cm-thick titanium shells. At 100 {mu}CF events/muon, it can produce up to 10{sup 17}n/s of 14-MeV neutrons. A quasi-isotropic neutron flux up to 10{sup 14} n/cm{sup 2}.s{sup -1} can be achieved in the test volume of {approx}2.5 l with an irradiated surface of {approx}350 cm{sup 2}. The thermophysical and thermomechanical analyses show that the technological limits are not exceeded.

  8. Oxidation behavior of plasma sintered beryllium-titanium intermetallic compounds as an advanced neutron multiplier

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hwan; Nakamichi, Masaru

    2013-07-01

    Beryllium intermetallic compounds (beryllides) such as Be12Ti are very promising candidates for advanced neutron multiplier materials in a demonstration fusion power reactor (DEMO). However, beryllides are too brittle to be fabricated either into pebble-type or rod-type shapes via conventional methods (i.e. arc melting and hot isostatic pressing). We have proposed a plasma sintering technique as a new method for beryllide fabrication, and our studies on the properties of plasma sintered beryllides are ongoing. In the present work, the oxidation properties of plasma sintered beryllides were investigated at 1273 K for 24 h in a dry air atmosphere to evaluate the high temperature properties of this material. Thermal gravimetry measurements indicate that specimens with larger fractions of Be12Ti phase corresponding to samples that have been sintered for longer time periods, exhibit superior oxidation properties. Our evaluation of the oxidation behavior of each phase in our beryllide samples is as follows: Be12Ti and Be17Ti2 both have good oxidation resistance, owing to the formation of dense and protective scales, while the Be and Be2Ti phases are mainly responsible for thermal-gravimetry (TG) weight gains, which is indicative of severe oxidation. We attribute the degradation in oxidation resistance specifically to Be2Ti that transforms into TiO2, and also find this phase to be the cause of deterioration in the mechanical properties of samples, owing to cracks near Be2Ti phase conglomerates.

  9. Advanced Neutron Sources: Plant Design Requirements

    SciTech Connect

    Not Available

    1990-07-01

    The Advanced Neutron Source (ANS) is a new, world class facility for research using hot, thermal, cold, and ultra-cold neutrons. At the heart of the facility is a 350-MW{sub th}, heavy water cooled and moderated reactor. The reactor is housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides fans out into a large guide hall, housing about 30 neutron research stations. Office, laboratory, and shop facilities are included to provide a complete users facility. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory at the end of the decade. This Plant Design Requirements document defines the plant-level requirements for the design, construction, and operation of the ANS. This document also defines and provides input to the individual System Design Description (SDD) documents. Together, this Plant Design Requirements document and the set of SDD documents will define and control the baseline configuration of the ANS.

  10. Advanced Neutron Source: Plant Design Requirements

    SciTech Connect

    Not Available

    1990-07-01

    The Advanced Neutron Source will be a new world-class facility for research using hot, thermal, cold, and ultra-cold neutrons. The heart of the facility will be a 330-MW (fission), heavy-water cooled and heavy-water moderated reactor. The reactor will be housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides will fan out into a large guide hall, housing about 30 neutron research stations. Appropriate office, laboratory, and shop facilities will be included to provide a complete facility for users. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory early in the next decade. This PDR document defines the plant-level requirements for the design, construction, and operation of ANS. It also defines and provides input to the individual System Design Description (SDD) documents. Together, this PDR document and the set of SDD documents will define and control the baseline configuration of ANS.

  11. Advances in Neutron Capture Therapy

    SciTech Connect

    Soloway, A.H.; Barth, R.F.; Carpenter, D.E.

    1993-12-31

    This volume contains the proceedings of the Fifth International Symposium on Neutron Capture Therapy held September 14--17, 1992 in Columbus, Ohio. Individual papers were separately abstracted and indexed for the database.

  12. 252Cf fission-neutron spectrum using a simplified time-of-flight setup: An advanced teaching laboratory experiment

    NASA Astrophysics Data System (ADS)

    Becchetti, F. D.; Febbraro, M.; Torres-Isea, R.; Ojaruega, M.; Baum, L.

    2013-02-01

    The removal of PuBe and AmBe neutron sources from many university teaching laboratories (due to heightened security issues) has often left a void in teaching various aspects of neutron physics. We have recently replaced such sources with sealed 252Cf oil-well logging sources (nominal 10-100 μCi), and developed several experiments using them as neutron sources. This includes a fission-neutron time-of-flight experiment using plastic scintillators, which utilizes the prompt γ rays emitted in 252Cf spontaneous fission as a fast timing start signal. The experiment can be performed with conventional nuclear instrumentation and a 1-D multi-channel pulse-height analyzer, available in most advanced teaching laboratories. Alternatively, a more sophisticated experiment using liquid scintillators and n/γ pulse-shape discrimination can be performed. Several other experiments using these neutron sources are also feasible. The experiments can introduce students to the problem of detecting the dark matter thought to dominate the universe and to the techniques used to detect contraband fissionable nuclear materials.

  13. Preliminary ANS (Advanced Neutron Source) reactor cold source gain factor calculations for liquid deuterium and liquid nitrogen-15

    SciTech Connect

    Henderson, D.L.

    1988-11-01

    Individual energy group gain factors are computed for liquid nitrogen-15 and liquid deuterium cold source moderators using simple one-dimensional slab and spherical geometry calculational models. The energy spectrum of the neutron source is assumed to be that of a thermalized Maxwellian flux at 20/degree/C. The slab geometry calculations indicate that the optimum thickness for neutron transmission through a slab given an isotropic incident flux is for wavelengths above .6 nm, approximately .20 m for liquid deuterium and between .28 and .32 m for liquid nitrogen-15. The gain factors at .8 nm corresponding to these thicknesses are 15.5 for liquid deuterium and 3.50 for liquid nitrogen-15. The spherical geometry analysis showed that the cold neutron current below 10 MeV of 1.36 n/m/sup 2/-s for the neutron component entering the cavity of a .16 m thick liquid deuterium spherical shell exceeds the neutron leakage current of 1.08 n/cm/sup 2/-s from a .38 m diameter liquid deuterium solid sphere. However, the cold neutron factors for the neutron entering the void region are considerably lower than for the solid sphere case. 15 refs., 24 figs., 7 tabs.

  14. Advanced Neutron Source: The users' perspective

    SciTech Connect

    Peretz, F.J.

    1990-01-01

    User experiments will cover fields such as activation analysis of pollutants, irradiation of materials for the fusion program, and neutron scattering studies of materials as diverse as viruses, aerospace composites, and superconductors. Production capabilities must also be provided for the production of isotopes, especially of transuranic elements. The different ways in which these research areas and their required infrastructure influence the design of the Advanced Neutron Source will be the subject of this paper.

  15. Advanced modeling of prompt fission neutrons

    SciTech Connect

    Talou, Patrick

    2009-01-01

    Theoretical and numerical studies of prompt fission neutrons are presented. The main results of the Los Alamos model often used in nuclear data evaluation work are reviewed briefly, and a preliminary assessment of uncertainties associated with the evaluated prompt fission neutron spectrum for n (0.5 MeV)+{sup 239}Pu is discussed. Advanced modeling of prompt fission neutrons is done by Monte Carlo simulations of the evaporation process of the excited primary fission fragments. The successive emissions of neutrons are followed in the statistical formalism framework, and detailed information, beyond average quantities, can be inferred. This approach is applied to the following reactions: {sup 252}Cf (sf), n{sub th} + {sup 239}Pu, n (0.5 MeV)+{sup 235}U, and {sup 236}Pu (sf). A discussion on the merits and present limitations of this approach concludes this presentation.

  16. Advanced Neutron Source radiological design criteria

    SciTech Connect

    Westbrook, J.L.

    1995-08-01

    The operation of the proposed Advanced Neutron Source (ANS) facility will present a variety of radiological protection problems. Because it is desired to design and operate the ANS according to the applicable licensing standards of the Nuclear Regulatory Commission (NRC), it must be demonstrated that the ANS radiological design basis is consistent not only with state and Department of Energy (DOE) and other usual federal regulations, but also, so far as is practicable, with NRC regulations and with recommendations of such organizations as the Institute of Nuclear Power Operations (INPO) and the Electric Power Research Institute (EPRI). Also, the ANS radiological design basis is in general to be consistent with the recommendations of authoritative professional and scientific organizations, specifically the National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP). As regards radiological protection, the principal goals of DOE regulations and guidance are to keep occupational doses ALARA [as low as (is) reasonably achievable], given the current state of technology, costs, and operations requirements; to control and monitor contained and released radioactivity during normal operation to keep public doses and releases to the environment ALARA; and to limit doses to workers and the public during accident conditions. Meeting these general design objectives requires that principles of dose reduction and of radioactivity control by employed in the design, operation, modification, and decommissioning of the ANS. The purpose of this document is to provide basic radiological criteria for incorporating these principles into the design of the ANS. Operations, modification, and decommissioning will be covered only as they are affected by design.

  17. BNL Activities in Advanced Neutron Source Development: Past and Present

    SciTech Connect

    Hastings, J.B.; Ludewig, H.; Montanez, P.; Todosow, M.; Smith, G.C.; Larese, J.Z.

    1998-06-14

    Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In this report we discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

  18. BNL ACTIVITIES IN ADVANCED NEUTRON SOURCE DEVELOPMENT: PAST AND PRESENT

    SciTech Connect

    HASTINGS,J.B.; LUDEWIG,H.; MONTANEZ,P.; TODOSOW,M.; SMITH,G.C.; LARESE,J.Z.

    1998-06-14

    Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In the sections below the authors discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.

  19. The advanced neutron source research and development plan

    SciTech Connect

    Selby, D.L.

    1995-08-01

    The Advanced Neutron Source (ANS) is being designed as a user-oriented neutron research laboratory centered around the most intense continuous beams of thermal and subthermal neutrons in the world (an order of magnitude more intense than beams available from the most advanced existing reactors). The ANS will be built around a new research reactor of 330-MW fission power, producing an unprecedented peak thermal flux of >7 {center_dot} 10{sup 19} {center_dot} m{sup -2} {center_dot} s{sup -1}. Primarily a research facility, the ANS will accommodate more than 1000 academic, industrial, and government researchers each year. They will conduct basic research in all branches of science as well as applied research leading to better understanding of new materials, including high temperature super conductors, plastics, and thin films. Some 48 neutron beam stations will be set up in the ANS beam rooms and the neutron guide hall for neutron scattering and for fundamental and nuclear physics research. There also will be extensive facilities for materials irradiation, isotope production, and analytical chemistry. The top level work breakdown structure (WBS) for the project. As noted in this figure, one component of the project is a research and development (R&D) program (WBS 1.1). This program interfaces with all of the other project level two WBS activities. Because one of the project guidelines is to meet minimum performance goals without relying on new inventions, this R&D activity is not intended to produce new concepts to allow the project to meet minimum performance goals. Instead, the R&D program will focus on the four objectives described.

  20. Scientific opportunities with advanced facilities for neutron scattering

    SciTech Connect

    Lander, G.H.; Emery, V.J.

    1984-01-01

    The present report documents deliberations of a large group of experts in neutron scattering and fundamental physics on the need for new neutron sources of greater intensity and more sophisticated instrumentation than those currently available. An additional aspect of the Workshop was a comparison between steady-state (reactor) and pulsed (spallation) sources. The main conclusions were: (1) the case for a new higher flux neutron source is extremely strong and such a facility will lead to qualitatively new advances in condensed matter science and fundamental physics; (2) to a large extent the future needs of the scientific community could be met with either a 5 x 10/sup 15/ n cm/sup -2/s/sup -1/ steady state source or a 10/sup 17/ n cm/sup -2/s/sup -1/ peak flux spallation source; and (3) the findings of this Workshop are consistent with the recommendations of the Major Materials Facilities Committee.

  1. The Detector for Advanced Neutron Capture Experiments at LANSCE

    SciTech Connect

    Ullmann, J.L.; Reifarth, R.; Haight, R.C.; Hunt, L.; O'Donnell, J.M.; Rundberg, R.S.; Bredeweg, T.A.; Wilhelmy, J.B.; Fowler, M.M.; Vieira, D.J.; Wouters, J.M.; Strottman, D.D.; Kaeppeler, F.; Heil, M.; Chamberlin, E.P.

    2003-08-26

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4{pi} barium fluoride array designed to study neutron capture on small quantities, 1 mg or less, of radioactive nuclides. It is being built on a 20 m neutron flight path which views the 'upper tier' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center. The detector design is based on Monte Carlo calculations which have suggested ways to minimize backgrounds due to neutron scattering events. A data acquisition system based on fast transient digitizers is being implemented.

  2. Detector for advanced neutron capture experiments at LANSCE

    SciTech Connect

    Ullmann, J. L.; Reifarth, R.; Haight, Robert C.; Hunt, L. F.; O'Donnell, J. M.; Bredeweg, T. A.; Wilhelmy, J. B.; Fowler, Malcolm M.; Vieira, D. J.; Wouters, J. M.; Strottman, D.; Kaeppeler, F.; Heil, M.; Chamberlin, E. P.

    2002-01-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4x barium fluoride array designed to study neutron capture on small quantities, 1 mg or less, of radioactive nuclides. It is being built on a 20 m neutron flight path which views the 'upper tier' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center. The detector design is based on Monte Carlo calculations which have suggested ways to minimize backgrounds due to neutron scattering events. A data acquisition system based on fast transient digitizers is bcing implemented

  3. The Advanced Neutron Source research and development plan

    SciTech Connect

    Selby, D.L.

    1992-11-30

    The Advanced Neutron Source (ANS) is being designed as a user-oriented neutron research laboratory centered around the most intense continuous beams of thermal and subthermal neutrons in the world. The ANS will be built around a new research reactor of {approximately} 330 MW fission power, producing an unprecedented peak thermal flux of > 7 {times} 10{sup 19} M{sup {minus}2} {center_dot} S{sup {minus}1}. Primarily a research facility, the ANS will accommodate more than 1000 academic, industrial, and government researchers each year. They will conduct basic research in all branches of science-as well as applied research-leading to better understanding of new materials, including high temperature super conductors, plastics, and thin films. Some 48 neutron beam stations will be set up in the ANS beam rooms and the neutron guide hall for neutron scattering and for fundamental and nuclear physics research. There also will be extensive facilities for materials irradiation, isotope production, and analytical chemistry. The R&D program will focus on the four objectives: Address feasibility issues; provide analysis support; evaluate options for improvement in performance beyond minimum requirements; and provide prototype demonstrations for unique facilities. The remainder of this report presents (1) the process by which the R&D activities are controlled and (2) a discussion of the individual tasks that have been identified for the R&D program, including their justification, schedule and costs. The activities discussed in this report will be performed by Martin Marietta Energy Systems, Inc. (MMES) through the Oak Ridge National Laboratory (ORNL) and through subcontracts with industry, universities, and other national laboratories. It should be noted that in general a success path has been assumed for all tasks.

  4. The Advanced Neutron Source research and development plan

    SciTech Connect

    Selby, D.L.

    1992-11-30

    The Advanced Neutron Source (ANS) is being designed as a user-oriented neutron research laboratory centered around the most intense continuous beams of thermal and subthermal neutrons in the world. The ANS will be built around a new research reactor of [approximately] 330 MW fission power, producing an unprecedented peak thermal flux of > 7 [times] 10[sup 19] M[sup [minus]2] [center dot] S[sup [minus]1]. Primarily a research facility, the ANS will accommodate more than 1000 academic, industrial, and government researchers each year. They will conduct basic research in all branches of science-as well as applied research-leading to better understanding of new materials, including high temperature super conductors, plastics, and thin films. Some 48 neutron beam stations will be set up in the ANS beam rooms and the neutron guide hall for neutron scattering and for fundamental and nuclear physics research. There also will be extensive facilities for materials irradiation, isotope production, and analytical chemistry. The R D program will focus on the four objectives: Address feasibility issues; provide analysis support; evaluate options for improvement in performance beyond minimum requirements; and provide prototype demonstrations for unique facilities. The remainder of this report presents (1) the process by which the R D activities are controlled and (2) a discussion of the individual tasks that have been identified for the R D program, including their justification, schedule and costs. The activities discussed in this report will be performed by Martin Marietta Energy Systems, Inc. (MMES) through the Oak Ridge National Laboratory (ORNL) and through subcontracts with industry, universities, and other national laboratories. It should be noted that in general a success path has been assumed for all tasks.

  5. Advanced Neutron Source: Plant Design Requirements. Revision 4

    SciTech Connect

    Not Available

    1990-07-01

    The Advanced Neutron Source will be a new world-class facility for research using hot, thermal, cold, and ultra-cold neutrons. The heart of the facility will be a 330-MW (fission), heavy-water cooled and heavy-water moderated reactor. The reactor will be housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides will fan out into a large guide hall, housing about 30 neutron research stations. Appropriate office, laboratory, and shop facilities will be included to provide a complete facility for users. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory early in the next decade. This PDR document defines the plant-level requirements for the design, construction, and operation of ANS. It also defines and provides input to the individual System Design Description (SDD) documents. Together, this PDR document and the set of SDD documents will define and control the baseline configuration of ANS.

  6. Experience with fast neutron therapy for locally advanced sarcomas

    SciTech Connect

    Salinas, R.; Hussey, D.H.; Fletcher, G.H.; Lindberg, R.D.; Martin, R.G.; Peters, L.J.; Sinkovics, J.G.

    1980-03-01

    Between October 1972 and April 1978, 34 patients with locally advanced sarcomas were treated with fast neutrons using the Texas A and M variable energy cyclotron. The clinical material included 29 patients with soft tissue sarcomas, 4 with chondrosarcomas, and one with an osteosarcoma. The best results were achieved for patients with soft tissue sarcomas; 69% (20/29) had local control of their tumor. Only one of 4 patients with chondrosarcomas was classified as having local tumor control, and one patient with osteosarcoma had persistent disease. With most fractionation schedules, local tumor control was superior for patients who received doses greater than 6500 rad/sub eq/ (2100 rad/sub n..gamma../ with 50 MeV/sub d ..-->.. Be/ neutrons). The incidence of major complications was notably increased when maximum radiation doses of 7500 rad/sub eq/ or greater were administered (2400 rad/sub n..gamma../ with 50 MeV/sub d ..-->.. Be/ neutrons). In patients who underwent subsequent surgery, healing was satisfactory if the maximum radiation dose was limited to 4500 to 5500 rad/sub eq/(1450 to 1775 rad/sub n..gamma../ with 50 MeV/sub d ..-->.. Be/ neutrons).

  7. Advanced Neutron Source Reactor thermal analysis of fuel plate defects

    SciTech Connect

    Giles, G.E.

    1995-08-01

    The Advanced Neutron Source Reactor (ANSR) is a research reactor designed to provide the highest continuous neutron beam intensity of any reactor in the world. The present technology for determining safe operations were developed for the High Flux Isotope Reactor (HFIR). These techniques are conservative and provide confidence in the safe operation of HFIR. However, the more intense requirements of ANSR necessitate the development of more accurate, but still conservative, techniques. This report details the development of a Local Analysis Technique (LAT) that provides an appropriate approach. Application of the LAT to two ANSR core designs are presented. New theories of the thermal and nuclear behavior of the U{sub 3}Si{sub 2} fuel are utilized. The implications of lower fuel enrichment and of modifying the inspection procedures are also discussed. Development of the computer codes that enable the automate execution of the LAT is included.

  8. Enhancing the detector for advanced neutron capture experiments

    DOE PAGESBeta

    Couture, A.; Mosby, S.; Baramsai, B.; Bredeweg, T. A.; Jandel, M.; Macon, K.; O’Donnell, J. M.; Rusev, G.; Taddeucci, T. N; Ullmann, J. L.; et al

    2015-05-28

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

  9. Enhancing the Detector for Advanced Neutron Capture Experiments

    NASA Astrophysics Data System (ADS)

    Couture, A.; Mosby, S.; Baramsai, B.; Bredeweg, T. A.; Jandel, M.; Macon, K.; O'Donnell, J. M.; Rusev, G.; Taddeucci, T. N.; Ullmann, J. L.; Walker, C. L.

    2015-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

  10. Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object

    DOEpatents

    Crane, T.W.

    1983-12-21

    The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

  11. Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object

    DOEpatents

    Crane, Thomas W.

    1986-01-01

    The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

  12. Wireless, in-vessel neutron monitor for initial core-loading of advanced breeder reactors

    NASA Technical Reports Server (NTRS)

    Delorenzo, J. T.; Kennedy, E. J.; Blalock, T. V.; Rochelle, J. M.; Chiles, M. M.; Valentine, K. H.

    1981-01-01

    An experimental wireless, in-vessel neutron monitor was developed to measure the reactivity of an advanced breeder reactor as the core is loaded for the first time to preclude an accidental critically incident. The environment is liquid sodium at a temperature of approx. 220 C, with negligible gamma or neutron radiation. With ultrasonic transmission of neutron data, no fundamental limitation was observed after tests at 230 C for 2000 h. The neutron sensitivity was approx. 1 count/s-nv, and the potential data transmission rate was approx. 10,000 counts/s.

  13. An improved method for estimating the neutron background in measurements of neutron capture reactions

    NASA Astrophysics Data System (ADS)

    Žugec, P.; Bosnar, D.; Colonna, N.; Gunsing, F.

    2016-08-01

    The relation between the neutron background in neutron capture measurements and the neutron sensitivity related to the experimental setup is examined. It is pointed out that a proper estimate of the neutron background may only be obtained by means of dedicated simulations taking into account the full framework of the neutron-induced reactions and their complete temporal evolution. No other presently available method seems to provide reliable results, in particular under the capture resonances. An improved neutron background estimation technique is proposed, the main improvement regarding the treatment of the neutron sensitivity, taking into account the temporal evolution of the neutron-induced reactions. The technique is complemented by an advanced data analysis procedure based on relativistic kinematics of neutron scattering. The analysis procedure allows for the calculation of the neutron background in capture measurements, without requiring the time-consuming simulations to be adapted to each particular sample. A suggestion is made on how to improve the neutron background estimates if neutron background simulations are not available.

  14. Advanced Two-Dimensional Thermal Neutron Detectors for Scattering Studies

    SciTech Connect

    Fried, J.; Harder, J.; Mahler, G.J.; Makowiecki, D.S.; Mead, J.A.; Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B.

    2002-11-18

    Advances in neutron scattering studies will be given a large boost with the advent of new spallation and reactor sources at present under consideration or construction. An important element for future experiments is a commensurate improvement in neutron detection techniques. At Brookhaven, a development program is under way for greatly increasing the angular coverage, rate capability and resolution of detectors for scattering studies. For example, a curved detector with angular coverage of 120{sup o} by 15{sup o} has recently been developed for protein crystallography at a spallation source. Based on neutron detection using {sup 3}He, the detector has the following major, new attributes: eight identical proportional wire segments operating in parallel, a single gas volume with seamless readout at segment boundaries, parallax errors eliminated in the horizontal plane by the detector's appropriate radius of curvature, high-throughput front-end electronics, position decoding based on high performance digital signal processing. The detector has a global rate capability greater than 1 million per second, position resolution less than 1.5 mm FWHM, timing resolution about 1 {micro}s, efficiency of 50% and 90% at 1{angstrom} and 4 {angstrom} respectively, and an active area 1.5 m x 20 cm.

  15. Advanced digital detectors for neutron imaging.

    SciTech Connect

    Doty, F. Patrick

    2003-12-01

    Neutron interrogation provides unique information valuable for Nonproliferation & Materials Control and other important applications including medicine, airport security, protein crystallography, and corrosion detection. Neutrons probe deep inside massive objects to detect small defects and chemical composition, even through high atomic number materials such as lead. However, current detectors are bulky gas-filled tubes or scintillator/PM tubes, which severely limit many applications. Therefore this project was undertaken to develop new semiconductor radiation detection materials to develop the first direct digital imaging detectors for neutrons. The approach relied on new discovery and characterization of new solid-state sensor materials which convert neutrons directly to electronic signals via reactions BlO(n,a)Li7 and Li6(n,a)T.

  16. DIANE: Advanced system for mobile neutron radiology

    NASA Astrophysics Data System (ADS)

    Dance, W. E.; Huriet, J. R.; Cluzeau, S.; Mast, H.-U.; Albisu, F.

    1989-04-01

    Development of a new neutron radiology system, DIANE, is underway which will provide a ten-fold improvement in image-acquisition speed over presently operating mobile systems, insuring greater inspection throughput for production applications. Based on a 10 12 n/s sealed-tube (D-T) neutron generator under development by Sodern, on LTV's neutron moderator/collimator and electronic imaging systems and on robotic and safety systems being developed by IABG and Sener, the DIANE concept is that of a complete facility for on-site neutron radiography or radioscopy. The LTV components, which provide film or electronic imaging, including digital processing of 12-bit images, have been demonstrated in three basic systems now operating with Kaman A-711 neutron generators, including one operating in IABG's facilities. Sodern has fabricated a prototype neutron generator tube, the TN 46, for emission of 10 11 n/s over 1000 to 1500 hours, at 250 kV and 2 mA in the ion beam.

  17. The neutron texture diffractometer at the China Advanced Research Reactor

    NASA Astrophysics Data System (ADS)

    Li, Mei-Juan; Liu, Xiao-Long; Liu, Yun-Tao; Tian, Geng-Fang; Gao, Jian-Bo; Yu, Zhou-Xiang; Li, Yu-Qing; Wu, Li-Qi; Yang, Lin-Feng; Sun, Kai; Wang, Hong-Li; Santisteban, J. r.; Chen, Dong-Feng

    2016-03-01

    The first neutron texture diffractometer in China has been built at the China Advanced Research Reactor, due to strong demand for texture measurement with neutrons from the domestic user community. This neutron texture diffractometer has high neutron intensity, moderate resolution and is mainly applied to study texture in commonly used industrial materials and engineering components. In this paper, the design and characteristics of this instrument are described. The results for calibration with neutrons and quantitative texture analysis of zirconium alloy plate are presented. The comparison of texture measurements with the results obtained in HIPPO at LANSCE and Kowari at ANSTO illustrates the reliability of the texture diffractometer. Supported by National Nature Science Foundation of China (11105231, 11205248, 51327902) and International Atomic Energy Agency-TC program (CPR0012)

  18. Status of neutron diagnostics on the experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Zhong, G. Q.; Hu, L. Q.; Pu, N.; Zhou, R. J.; Xiao, M.; Cao, H. R.; Zhu, Y. B.; Li, K.; Fan, T. S.; Peng, X. Y.; Du, T. F.; Ge, L. J.; Huang, J.; Xu, G. S.; Wan, B. N.

    2016-11-01

    Neutron diagnostics have become a significant means to study energetic particles in high power auxiliary heating plasmas on the Experimental Advanced Superconducting Tokamak (EAST). Several kinds of neutron diagnostic systems have been implemented for time-resolved measurements of D-D neutron flux, fluctuation, emission profile, and spectrum. All detectors have been calibrated in laboratory, and in situ calibration using 252Cf neutron source in EAST is in preparation. A new technology of digitized pulse signal processing is adopted in a wide dynamic range neutron flux monitor, compact recoil proton spectrometer, and time of flight spectrometer. Improvements will be made continuously to the system to achieve better adaptation to the EAST's harsh γ-ray and electro-magnetic radiation environment.

  19. Recent advances in laser-driven neutron sources

    NASA Astrophysics Data System (ADS)

    Alejo, A.; Ahmed, H.; Green, A.; Mirfayzi, S. R.; Borghesi, M.; Kar, S.

    2016-11-01

    Due to the limited number and high cost of large-scale neutron facilities, there has been a growing interest in compact accelerator-driven sources. In this context, several potential schemes of laser-driven neutron sources are being intensively studied employing laser-accelerated electron and ion beams. In addition to the potential of delivering neutron beams with high brilliance, directionality and ultra-short burst duration, a laser-driven neutron source would offer further advantages in terms of cost-effectiveness, compactness and radiation confinement by closed-coupled experiments. Some of the recent advances in this field are discussed, showing improvements in the directionality and flux of the laser-driven neutron beams.

  20. Recent advances in neutron capture therapy (NCT)

    SciTech Connect

    Fairchild, R.G.

    1985-01-01

    The application of the /sup 10/B(n,..cap alpha..)/sup 7/Li reaction to cancer radiotherapy (Neutron Capture therapy, or NCT) has intrigued investigators since the discovery of the neutron. This paper briefly summarizes data describing recently developed boronated compounds with evident tumor specificity and extended biological half-lives. The implication of these compounds to NCT is evaluated in terms of Therapeutic Gain (TG). The optimization of NCT using band-pass filtered beams is described, again in terms of TG, and irradiation times with these less intense beams are estimated. 24 refs., 3 figs., 3 tabs.

  1. Advancing Materials Science using Neutrons at Oak Ridge National Laboratory

    SciTech Connect

    Carpenter, John

    2014-04-24

    Jack Carpenter, pioneer of accelerator-based pulsed spallation neutron sources, talks about neutron science at Oak Ridge National Laboratory (ORNL) and a need for a second target station at the Spallation Neutron Source (SNS). ORNL is the Department of Energy's largest multiprogram science and energy laboratory, and is home to two scientific user facilities serving the neutron science research community: the High Flux Isotope Reactor (HFIR) and SNS. HFIR and SNS provide researchers with unmatched capabilities for understanding the structure and properties of materials, macromolecular and biological systems, and the fundamental physics of the neutron. Neutrons provide a window through which to view materials at a microscopic level that allow researchers to develop better materials and better products. Neutrons enable us to understand materials we use in everyday life. Carpenter explains the need for another station to produce long wavelength neutrons, or cold neutrons, to answer questions that are addressed only with cold neutrons. The second target station is optimized for that purpose. Modern technology depends more and more upon intimate atomic knowledge of materials, and neutrons are an ideal probe.

  2. Advancing Materials Science using Neutrons at Oak Ridge National Laboratory

    ScienceCinema

    Carpenter, John

    2016-07-12

    Jack Carpenter, pioneer of accelerator-based pulsed spallation neutron sources, talks about neutron science at Oak Ridge National Laboratory (ORNL) and a need for a second target station at the Spallation Neutron Source (SNS). ORNL is the Department of Energy's largest multiprogram science and energy laboratory, and is home to two scientific user facilities serving the neutron science research community: the High Flux Isotope Reactor (HFIR) and SNS. HFIR and SNS provide researchers with unmatched capabilities for understanding the structure and properties of materials, macromolecular and biological systems, and the fundamental physics of the neutron. Neutrons provide a window through which to view materials at a microscopic level that allow researchers to develop better materials and better products. Neutrons enable us to understand materials we use in everyday life. Carpenter explains the need for another station to produce long wavelength neutrons, or cold neutrons, to answer questions that are addressed only with cold neutrons. The second target station is optimized for that purpose. Modern technology depends more and more upon intimate atomic knowledge of materials, and neutrons are an ideal probe.

  3. Advances in Neutron Spectroscopy with Deuterated Organic Scintillators

    NASA Astrophysics Data System (ADS)

    Febbraro, Michael; Pain, Steve; Becchetti, Frederick

    2015-10-01

    Deuterated organic scintillators have shown promise as neutron detectors for nuclear science as well as applications in nuclear non-proliferation and safeguards. In particular, they can extract neutron spectra without the use of neutron time-of-flight measurement (n-ToF) utilizing spectrum unfolding techniques. This permits the measure of cross sections of bound and unbound states with high efficiency and angular coverage. In the case of measurements with radioactive ion beams where low beam intensities limit long path n-ToF, short path n-ToF can be used to discriminate neutrons of interest from room return and background neutrons. This presentation will provide recent advances with these types of detectors. Digital pulse-shape discrimination using fast waveform digitizers, spectrum unfolding methods for extraction of neutron spectra, and a new safer deuterated-xylene formulation EJ-301D will be discussed. In addition, experimental results from measurements of discrete and continuous neutron spectra which illustrate the advantage of these detectors for certain applications in nuclear physics research and nuclear security will be shown. This work is supported by NSF and DOE.

  4. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    SciTech Connect

    Franklyn, C. B.

    2011-12-13

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  5. Implementation and Initial Testing of Advanced Processing and Analysis Algorithms for Correlated Neutron Counting

    SciTech Connect

    Santi, Peter Angelo; Cutler, Theresa Elizabeth; Favalli, Andrea; Koehler, Katrina Elizabeth; Henzl, Vladimir; Henzlova, Daniela; Parker, Robert Francis; Croft, Stephen

    2015-12-01

    In order to improve the accuracy and capabilities of neutron multiplicity counting, additional quantifiable information is needed in order to address the assumptions that are present in the point model. Extracting and utilizing higher order moments (Quads and Pents) from the neutron pulse train represents the most direct way of extracting additional information from the measurement data to allow for an improved determination of the physical properties of the item of interest. The extraction of higher order moments from a neutron pulse train required the development of advanced dead time correction algorithms which could correct for dead time effects in all of the measurement moments in a self-consistent manner. In addition, advanced analysis algorithms have been developed to address specific assumptions that are made within the current analysis model, namely that all neutrons are created at a single point within the item of interest, and that all neutrons that are produced within an item are created with the same energy distribution. This report will discuss the current status of implementation and initial testing of the advanced dead time correction and analysis algorithms that have been developed in an attempt to utilize higher order moments to improve the capabilities of correlated neutron measurement techniques.

  6. Assessment of the roles of the Advanced Neutron Source Operators

    SciTech Connect

    Hill, W.E.; Houser, M.M.; Knee, H.E.; Spelt, P.F.

    1995-03-01

    The Advanced Neutron Source (ANS) is unique in the extent to which human factors engineering (HFE) principles are being applied at the conceptual design stage. initial HFE accomplishments include the development of an ANS HFE program plan, operating philosophy, and functional analysis. In FY 1994, HFE activities focused on the role of the ANS control room reactor operator (RO). An operator-centered control room model was used in conjunction with information gathered from existing ANS system design descriptions and other literature to define a list of RO responsibilities. From this list, a survey instrument was developed and administered to ANS design engineers, operations management personnel at Oak Ridge National Laboratory`s High Flux Isotope Reactor (HFIR), and HFIR ROs to detail the nature of the RO position. Initial results indicated that the RO will function as a high-level system supervisor with considerable monitoring, verification, and communication responsibilities. The relatively high level of control automation has resulted in a reshaping of the RO`s traditional safety and investment protection roles.

  7. Advanced neutron source reactor probabilistic flow blockage assessment

    SciTech Connect

    Ramsey, C.T.

    1995-08-01

    The Phase I Level I Probabilistic Risk Assessment (PRA) of the conceptual design of the Advanced Neutron Source (ANS) Reactor identified core flow blockage as the most likely internal event leading to fuel damage. The flow blockage event frequency used in the original ANS PRA was based primarily on the flow blockage work done for the High Flux Isotope Reactor (HFIR) PRA. This report examines potential flow blockage scenarios and calculates an estimate of the likelihood of debris-induced fuel damage. The bulk of the report is based specifically on the conceptual design of ANS with a 93%-enriched, two-element core; insights to the impact of the proposed three-element core are examined in Sect. 5. In addition to providing a probability (uncertainty) distribution for the likelihood of core flow blockage, this ongoing effort will serve to indicate potential areas of concern to be focused on in the preliminary design for elimination or mitigation. It will also serve as a loose-parts management tool.

  8. Advances in associated-particle sealed-tube neutron probe diagnostics for substance detection

    SciTech Connect

    Rhodes, E.; Dickerman, C.E.; Frey, M.

    1995-07-01

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) shows potential to allow the associated-particle diagnostic method to be moved out of the laboratory into field applications. The APSTNG interrogates the inspected object with 14-MeV neutrons generated from the deuterium-tritium reaction and detects the alpha-particle associated with each neutron inside a cone encompassing the region of interest. Gamma-ray spectra of resulting neutron reactions identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles can yield a separate coarse tomographic image of each identified nuclide, from a single orientation. Chemical substances are identified by comparing relative spectral line intensities with ratios of elements in reference compounds. The high-energy neutrons and gamma-rays penetrate large objects and dense materials. Generally no collimators or radiation shielding are needed. Proof-of-concept laboratory experiments have been successfully performed for simulated nuclear, chemical warfare, and conventional munitions. Most recently, inspection applications have been investigated for radioactive waste characterization, presence of cocaine in propane tanks, and uranium and plutonium smuggling. Based on lessons learned with the present APSTNG system, an advanced APSTNG tube (along with improved high voltage supply and control units) is being designed and fabricated that will be transportable and rugged, yield a substantial neutron output increase, and provide sufficiently improved lifetime to allow operation at more than an order of magnitude increase in neutron flux.

  9. Advanced neutron source final preconceptual reference core design

    SciTech Connect

    Copeland, G.L.; Gambill, W.R.; Harrington, R.M.; Johnson, J.A.; Peretz, F.J.; Reutler, H.; Ryskamp, J.M.; Selby, D.L.; West, C.D.; Yoder, G.L.

    1989-08-01

    The preconceptual design phase of the Advanced Neutron Source (ANS) Project ended with the selection of a reference reactor core that will be used to begin conceptual design work. The new reference core consists of two involute fuel elements, of different diameters, aligned axially with a small axial gap between them. The use of different element diameters permits a separate flow of coolant to be provided for each one, thus enhancing the heat removal capability and increasing the thermal-hydraulic margins. The improved cooling allows the elements to be relatively long and thin, so self-shielding is reduced and an acceptable core life can be achieved with a relatively small loading of highly enriched uranium silicide fuel clad in aluminium. The new reference design has a fueled volume 67.4 L, each element having a heated length of 474 mm and a radial fuel thickness of 66 mm. The end-of-cycle peak thermal flux in the large heavy-water reflector tank around the core is estimated to be in the range of 0.8 to 1.0 /times/ 10/sup 20/ m/sup /minus/2/ /center dot/ s/sup /minus/1/. 7 refs., 23 figs., 15 tabs.

  10. Neutron Cross Section Covariances: Recent Workshop and Advanced Reactor Systems

    NASA Astrophysics Data System (ADS)

    Oblozinsky, Pavel

    2008-10-01

    The recent Workshop on Neutron Cross Section Covariances, organized by BNL and attended by more than 50 scientists, responded to demands of many user groups, including advanced reactor systems, for uncertainty and correlation information. These demands can be explained by considerable progress in advanced neutronics simulation that probe covariances and their impact on design and operational margins of nuclear systems. The Workshop addressed evaluation methodology, recent evaluations as well as user's perspective, marking era of revival of covariance development that started some two years ago. We illustrate urgent demand for covariances in the case of advanced reactor systems, including fast actinide burner under GNEP, new generation of power reactors, Gen-IV, and reactors under AFCI. A common feature of many of these systems is presence of large amount of minor actinides and fission products that require improved nuclear data. Advanced simulation codes rely on quality input, to be obtained by adjusting the data library, such as the new ENDF/B-VII.0, by considering integral experiments as currently pursued by GNEP. To this end the nuclear data community is developing covariances for formidable amount of 112 materials (isotopes).

  11. Application of Pixel-cell Detector Technology for Advanced Neutron Beam Monitors

    SciTech Connect

    Kopp, Daniel M.

    2011-01-11

    Application of Pixel-Cell Detector Technology for Advanced Neutron Beam Monitors Specifications of currently available neutron beam detectors limit their usefulness at intense neutron beams of large-scale national user facilities used for the advanced study of materials. A large number of neutron-scattering experiments require beam monitors to operate in an intense neutron beam flux of >10E+7 neutrons per second per square centimeter. For instance, a 4 cm x 4 cm intense beam flux of 6.25 x 10E+7 n/s/cm2 at the Spallation Neutron Source will put a flux of 1.00 x 10E+9 n/s at the beam monitor. Currently available beam monitors with a typical efficiency of 1 x 10E-4 will need to be replaced in less than two years of operation due to wire and gas degradation issues. There is also a need at some instruments for beam position information that are beyond the capabilities of currently available He-3 and BF3 neutron beam monitors. ORDELA, Inc.’s research under USDOE SBIR Grant (DE-FG02-07ER84844) studied the feasibility of using pixel-cell technology for developing a new generation of stable, long-life neutron beam monitors. The research effort has led to the development and commercialization of advanced neutron beam detectors that will directly benefit the Spallation Neutron Source and other intense neutron sources such as the High Flux Isotope Reactor. A prototypical Pixel-Cell Neutron Beam Monitor was designed and constructed during this research effort. This prototype beam monitor was exposed to an intense neutron beam at the HFIR SNS HB-2 test beam site. Initial measurements on efficiency, uniformity across the detector, and position resolution yielded excellent results. The development and test results have provided the required data to initiate the fabrication and commercialization of this next generation of neutron-detector systems. ORDELA, Inc. has (1) identified low-cost design and fabrication strategies, (2) developed and built pixel-cell detectors and

  12. Hardening neutron spectrum for advanced actinide transmutation experiments in the ATR.

    PubMed

    Chang, G S; Ambrosek, R G

    2005-01-01

    The most effective method for transmuting long-lived isotopes contained in spent nuclear fuel into shorter-lived fission products is in a fast neutron spectrum reactor. In the absence of a fast test reactor in the United States, initial irradiation testing of candidate fuels can be performed in a thermal test reactor that has been modified to produce a test region with a hardened neutron spectrum. Such a test facility, with a spectrum similar but somewhat softer than that of the liquid-metal fast breeder reactor (LMFBR), has been constructed in the INEEL's Advanced Test Reactor (ATR). The radial fission power distribution of the actinide fuel pin, which is an important parameter in fission gas release modelling, needs to be accurately predicted and the hardened neutron spectrum in the ATR and the LMFBR fast neutron spectrum is compared. The comparison analyses in this study are performed using MCWO, a well-developed tool that couples the Monte Carlo transport code MCNP with the isotope depletion and build-up code ORIGEN-2. MCWO analysis yields time-dependent and neutron-spectrum-dependent minor actinide and Pu concentrations and detailed radial fission power profile calculations for a typical fast reactor (LMFBR) neutron spectrum and the hardened neutron spectrum test region in the ATR. The MCWO-calculated results indicate that the cadmium basket used in the advanced fuel test assembly in the ATR can effectively depress the linear heat generation rate in the experimental fuels and harden the neutron spectrum in the test region.

  13. Fast neutron irradiation for advanced tumors in the pelvis

    SciTech Connect

    Battermann, J.J.; Breur, K.

    1981-08-01

    Since the end of 1975, fast neutron irradiation has been used in the Antoni van Leeuwenhoek Hospital for the treatment of advanced tumors, which had no prospect of cure by other treatment modalities. Fifty-nine patients were irradiated in the pelvic area, 22 for inoperable bladder cancer, 25 for rectal and 12 for gynecological cancer. Treatments were given 5 times per week with a 14 MeV d + T neutron generator. Persisting complete tumor regression was achieved in 11 of 22 bladded patients, 14 of 25 rectum patients and 6 of 12 gynecological patients. Because of unfavorable beam characteristics, 15 of 59 (25%) treated patients had severe radiation-induced intestinal and skin complications.

  14. Thermal-hydraulic studies of the Advanced Neutron Source cold source

    SciTech Connect

    Williams, P.T.; Lucas, A.T.

    1995-08-01

    The Advanced Neutron Source (ANS), in its conceptual design phase at Oak Ridge National Laboratory, was to be a user-oriented neutron research facility producing the most intense steady-state flux of thermal and cold neutrons in the world. Among its many scientific applications, the production of cold neutrons was a significant research mission for the ANS. The cold neutrons come from two independent cold sources positioned near the reactor core. Contained by an aluminum alloy vessel, each cold source is a 410-mm-diam sphere of liquid deuterium that functions both as a neutron moderator and a cryogenic coolant. With nuclear heating of the containment vessel and internal baffling, steady-state operation requires close control of the liquid deuterium flow near the vessel`s inner surface. Preliminary thermal-hydraulic analyses supporting the cold source design were performed with heat conduction simulations of the vessel walls and multidimensional computational fluid dynamics simulations of the liquid deuterium flow and heat transfer. This report presents the starting phase of a challenging program and describes the cold source conceptual design, the thermal-hydraulic feasibility studies of the containment vessel, and the future computational and experimental studies that were planned to verify the final design.

  15. AND/R: Advanced neutron diffractometer/reflectometer for investigation of thin films and multilayers for the life sciences

    PubMed Central

    Dura, Joseph A.; Pierce, Donald J.; Majkrzak, Charles F.; Maliszewskyj, Nicholas C.; McGillivray, Duncan J.; Lösche, Mathias; O'Donovan, Kevin V.; Mihailescu, Mihaela; Perez-Salas, Ursula; Worcester, David L.; White, Stephen H.

    2011-01-01

    An elastic neutron scattering instrument, the advanced neutron diffractometer/reflectometer (AND/R), has recently been commissioned at the National Institute of Standards and Technology Center for Neutron Research. The AND/R is the centerpiece of the Cold Neutrons for Biology and Technology partnership, which is dedicated to the structural characterization of thin films and multilayers of biological interest. The instrument is capable of measuring both specular and nonspecular reflectivity, as well as crystalline or semicrystalline diffraction at wave-vector transfers up to approximately 2.20 Å−1. A detailed description of this flexible instrument and its performance characteristics in various operating modes are given. PMID:21892232

  16. A new fuel loading design for the Advanced Neutron Source

    SciTech Connect

    Gehin, J.C.; Renier, J.P.; Worley, B.A.

    1994-06-01

    A new fuel loading design has been developed for the Advanced Neutron Source Reactor. In this reactor the combination of a small core volume and high power results in a very high power density. Using a direct optimization procedure the thermal-hydraulic margins for oxide temperature drop, centerline temperature and incipient boiling (and thus critical heat flux) were maximized to increase the limiting thermal power from 298 MW to 346 MW compared to the previous fuel grading, while maintaining the desired peak reflector thermal flux.

  17. Validation of multigroup neutron cross sections for the Advanced Neutron Source against the FOEHN critical experimental measurements

    SciTech Connect

    Smith, L.A.; Gehin, J.C.; Worley, B.A.; Renier, J.P.

    1994-04-01

    The FOEHN critical experiments were analyzed to validate the use of multigroup cross sections in the design of the Advanced Neutron Source. Eleven critical configurations were evaluated using the KENO, DORT, and VENTURE neutronics codes. Eigenvalue and power density profiles were computed and show very good agreement with measured values.

  18. Loss-of-coolant accident analyses of the Advanced Neutron Source Reactor

    SciTech Connect

    Chen, N.C.J.; Yoder, G.L. ); Wendel, M.W. )

    1991-01-01

    Currently in the conceptual design stage, the Advanced Neutron Source Reactor (ANSR) will operate at a high heat flux, a high mass flux, an a high degree of coolant subcooling. Loss-of-coolant accident (LOCA) analyses using RELAP5 have been performed as part of an early evaluation of ANSR safety issues. This paper discusses the RELAP5 ANSR conceptual design system model and preliminary LOCA simulation results. Some previous studies were conducted for the preconceptual design. 12 refs., 7 figs.

  19. ANSL-V: ENDF/B-V based multigroup cross-section libraries for Advanced Neutron Source (ANS) reactor studies. Supplement 1

    SciTech Connect

    Wright, R.Q.; Renier, J.P.; Bucholz, J.A.

    1995-08-01

    The original ANSL-V cross-section libraries (ORNL-6618) were developed over a period of several years for the physics analysis of the ANS reactor, with little thought toward including the materials commonly needed for shielding applications. Materials commonly used for shielding applications include calcium barium, sulfur, phosphorous, and bismuth. These materials, as well as {sup 6}Li, {sup 7}Li, and the naturally occurring isotopes of hafnium, have been added to the ANSL-V libraries. The gamma-ray production and gamma-ray interaction cross sections were completely regenerated for the ANSL-V 99n/44g library which did not exist previously. The MALOCS module was used to collapse the 99n/44g coupled library to the 39n/44g broad- group library. COMET was used to renormalize the two-dimensional (2- D) neutron matrix sums to agree with the one-dimensional (1-D) averaged values. The FRESH module was used to adjust the thermal scattering matrices on the 99n/44g and 39n/44g ANSL-V libraries. PERFUME was used to correct the original XLACS Legendre polynomial fits to produce acceptable distributions. The final ANSL-V 99n/44g and 39n/44g cross-section libraries were both checked by running RADE. The AIM module was used to convert the master cross-section libraries from binary coded decimal to binary format (or vice versa).

  20. Results of fast neutron teletherapy for locally advanced head and neck tumors

    SciTech Connect

    Battermann, J.J.; Breur, K.

    1981-08-01

    An analysis is given of the results of fast neutron therapy for locally advanced tumors of the head and neck region. All patients were treated five times per week with a 14 MeV d + T neutron beam and received dosages of about 19 Gy/sub nadvanced tumors were treated in this pilot study, the survival time is rather short for most patients. Only 8 patients are alive at the time of writing. The results of treatment for inoperable malignancies of the major salivary glands are very promising, as initial complete regression was achieved in over 90% (12/13).

  1. Experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source spectrum of the NBSR reactor at the NIST Center for Neutron Research

    NASA Astrophysics Data System (ADS)

    Cook, J. C.; Barker, J. G.; Rowe, J. M.; Williams, R. E.; Gagnon, C.; Lindstrom, R. M.; Ibberson, R. M.; Neumann, D. A.

    2015-08-01

    The recent expansion of the National Institute of Standards and Technology (NIST) Center for Neutron Research facility has offered a rare opportunity to perform an accurate measurement of the cold neutron spectrum at the exit of a newly-installed neutron guide. Using a combination of a neutron time-of-flight measurement, a gold foil activation measurement, and Monte Carlo simulation of the neutron guide transmission, we obtain the most reliable experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source brightness to date. Time-of-flight measurements were performed at three distinct fuel burnup intervals, including one immediately following reactor startup. Prior to the latter measurement, the hydrogen was maintained in a liquefied state for an extended period in an attempt to observe an initial radiation-induced increase of the ortho (o)-hydrogen fraction. Since para (p)-hydrogen has a small scattering cross-section for neutron energies below 15 meV (neutron wavelengths greater than about 2.3 Å), changes in the o- p hydrogen ratio and in the void distribution in the boiling hydrogen influence the spectral distribution. The nature of such changes is simulated with a continuous-energy, Monte Carlo radiation-transport code using 20 K o and p hydrogen scattering kernels and an estimated hydrogen density distribution derived from an analysis of localized heat loads. A comparison of the transport calculations with the mean brightness function resulting from the three measurements suggests an overall o- p ratio of about 17.5(±1) % o- 82.5% p for neutron energies<15 meV, a significantly lower ortho concentration than previously assumed.

  2. An Accelerator Neutron Source for BNCT

    SciTech Connect

    Blue, Thomas, E

    2006-03-14

    The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were 1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, 2) that the patient treatment time be reasonable, 3) that the proton current required to treat patients in reasonable times be technologially achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally 4) that the treatment be safe for the patients.

  3. Advanced concept proof-of-principle demonstration: Switchable radioactive neutron source

    SciTech Connect

    Rhodes, E.A.; Bowers, D.L.; Boyar, R.E.; Dickerman, C.E.

    1995-10-01

    An advanced concept proof-of-principle demonstration was successfully performed to show the feasibility of a practical switchable radioactive neutron source (SRNS) that can be switched on and off like an accelerator, but without requiring accelerator equipment such as high voltage supply, control unit, etc. This source concept would provide a highly portable neutron source for field radiation measurement applications. Such a source would require minimal, if any, shielding when not in use. The SRNS, previously patented by Argonne staff, provides a means of constructing the alpha-emitting and light-element components of a radioactive neutron source, in such a fashion that these two components can brought together to turn the source ``on`` and then be separated to turn the source ``off``. An SRNS could be used for such field applications as active neutron interrogation of objects to detect fissile materials or to measure their concentration; and to excite gamma-ray emission for detection of specific elements that indicate toxic chemicals, drugs, explosives, etc. The demonstration was performed using Pu-238 as the alpha emitter and Be as the light element, in an air-atmosphere glovebox having no atmosphere purification capability. A stable, thin film of Pu-238 oxide was deposited on a stainless steel planchet. The ``on`` output of the demonstration Pu-238 film was measured to be 2.5 {times} 10{sup 6} neutrons/sec-gram of Pu-238. The measured ``off`` neutron rate was satisfactory, only about 5% of the ``on`` output, after two weeks of exposure to the glovebox atmosphere. After several weeks additional exposure, the ``off`` rate had increased to about 15%. This work demonstrates the feasibility of constructing practical, highly portable SRNS units with very low gamma-ray dose in the ``off`` position.

  4. Phase 1 environmental report for the Advanced Neutron Source at Oak Ridge National Laboratory

    SciTech Connect

    Blasing, T.J.; Brown, R.A.; Cada, G.F.; Easterly, C.; Feldman, D.L.; Hagan, C.W.; Harrington, R.M.; Johnson, R.O.; Ketelle, R.H.; Kroodsma, R.L.; McCold, L.N.; Reich, W.J.; Scofield, P.A.; Socolof, M.L.; Taleyarkhan, R.P.; Van Dyke, J.W.

    1992-02-01

    The US Department of Energy (DOE) has proposed the construction and operation of the Advanced Neutron Source (ANS), a 330-MW(f) reactor, at Oak Ridge National Laboratory (ORNL) to support neutron scattering and nuclear physics experiments. ANS would provide a steady-state source of neutrons that are thermalized to produce sources of hot, cold, and very coal neutrons. The use of these neutrons in ANS experiment facilities would be an essential component of national research efforts in basic materials science. Additionally, ANS capabilities would include production of transplutonium isotopes, irradiation of potential fusion and fission reactor materials, activation analysis, and production of medical and industrial isotopes such as {sup 252}Cf. Although ANS would not require licensing by the US Nuclear Regulatory Commission (NRC), DOE regards the design, construction, and operation of ANS as activities that would produce a licensable facility; that is, DOE is following the regulatory guidelines that NRC would apply if NRC were licensing the facility. Those guidelines include instructions for the preparation of an environmental report (ER), a compilation of available data and preliminary analyses regarding the environmental impacts of nuclear facility construction and operation. The ER, described and outlined in NRC Regulatory Guide 4.2, serves as a background document to facilitate the preparation of environmental impact statements (EISs). Using Regulatory Guide 4.2 as a model, this ANS ER provides analyses and information specific to the ANS site and area that can be adopted (and modified, if necessary) for the ANS EIS. The ER is being prepared in two phases. Phase 1 ER includes many of the data and analyses needed to prepare the EIS but does not include data or analyses of alternate sites or alternate technologies. Phase 2 ER will include the additional data and analyses stipulated by Regulatory Guide 4.2.

  5. Oak Ridge Reservation site evaluation report for the Advanced Neutron Source

    SciTech Connect

    Sigmon, B.; Heitzman, A.C. Jr.; Morrissey, J.

    1990-03-01

    The Advanced Neutron Source (ANS) is a research reactor that is the US Department of Energy (DOE) plans to build for initial service late in this century. The primary purpose of the ANS is to provide a useable neutron flux for scattering experiments 5 to 10 times as a high as that generated by any existing research reactor, secondary purposes include production of a variety of transuranic and other isotopes and irradiation of materials. The ANS is proposed to be located on the DOE Oak Ridge Reservation (ORR) at Oak Ridge, Tennessee, and operated by the Oak Ridge National Laboratory (ORNL). This report documents the evaluation of alternative sites on the ORR and the selection of a site for the ANS.

  6. MCNP speed advances for boron neutron capture therapy

    SciTech Connect

    Goorley, J.T.; McKinney, G.; Adams, K.; Estes, G.

    1998-04-01

    The Boron Neutron Capture Therapy (BNCT) treatment planning process of the Beth Israel Deaconess Medical Center-M.I.T team relies on MCNP to determine dose rates in the subject`s head for various beam orientations. In this time consuming computational process, four or five potential beams are investigated. Of these, one or two final beams are selected and thoroughly evaluated. Recent advances greatly decreased the time needed to do these MCNP calculations. Two modifications to the new MCNP4B source code, lattice tally and tracking enhancements, reduced the wall-clock run times of a typical one million source neutrons run to one hour twenty five minutes on a 200 MHz Pentium Pro computer running Linux and using the GNU FORTRAN compiler. Previously these jobs used a special version of MCNP4AB created by Everett Redmond, which completed in two hours two minutes. In addition to this 30% speedup, the MCNP4B version was adapted for use with Parallel Virtual Machine (PVM) on personal computers running the Linux operating system. MCNP, using PVM, can be run on multiple computers simultaneously, offering a factor of speedup roughly the same as the number of computers used. With two 200 MHz Pentium Pro machines, the run time was reduced to forty five minutes, a 1.9 factor of improvement over the single Linux computer. While the time of a single run was greatly reduced, the advantages associated with PVM derive from using computational power not already used. Four possible beams, currently requiring four separate runs, could be run faster when each is individually run on a single machine under Windows NT, rather than using Linux and PVM to run one after another with each multiprocessed across four computers. It would be advantageous, however, to use PVM to distribute the final two beam orientations over four computers.

  7. Recent advances in fast neutron radiography for cargo inspection

    NASA Astrophysics Data System (ADS)

    Sowerby, B. D.; Tickner, J. R.

    2007-09-01

    Fast neutron radiography techniques are attractive for screening cargo for contraband such as narcotics and explosives. Neutrons have the required penetration, they interact with matter in a manner complementary to X-rays and they can be used to determine elemental composition. Compared to neutron interrogation techniques that measure secondary radiation (neutron or gamma-rays), neutron radiography systems are much more efficient and rapid and they are much more amenable to imaging. However, for neutron techniques to be successfully applied to cargo screening, they must demonstrate significant advantages over well-established X-ray techniques. This paper reviews recent developments and applications of fast neutron radiography for cargo inspection. These developments include a fast neutron and gamma-ray radiography system that utilizes a 14 MeV neutron generator as well as fast neutron resonance radiography systems that use variable energy quasi-monoenergetic neutrons and pulsed broad energy neutron beams. These systems will be discussed and compared with particular emphasis on user requirements, sources, detector systems, imaging ability and performance.

  8. Fuel qualification plan for the Advanced Neutron Source Reactor

    SciTech Connect

    Copeland, G.L.

    1995-07-01

    This report describes the development and qualification plan for the fuel for the Advanced Neutron Source. The reference fuel is U{sub 3}Si{sub 2}, dispersed in aluminum and clad in 6061 aluminum. This report was prepared in May 1994, at which time the reference design was for a two-element core containing highly enriched uranium (93% {sup 235}U) . The reactor was in the process of being redesigned to accommodate lowered uranium enrichment and became a three-element core containing a higher volume fraction of uranium enriched to 50% {sup 235}U. Consequently, this report was not issued at that time and would have been revised to reflect the possibly different requirements of the lower-enrichment, higher-volume fraction fuel. Because the reactor is now being canceled, this unrevised report is being issued for archival purposes. The report describes the fabrication and inspection development plan, the irradiation tests and performance modeling to qualify performance, the transient testing that is part of the safety program, and the interactions and interfaces of the fuel development with other tasks.

  9. Advanced Neutron Source Dynamic Model (ANSDM) code description and user guide

    SciTech Connect

    March-Leuba, J.

    1995-08-01

    A mathematical model is designed that simulates the dynamic behavior of the Advanced Neutron Source (ANS) reactor. Its main objective is to model important characteristics of the ANS systems as they are being designed, updated, and employed; its primary design goal, to aid in the development of safety and control features. During the simulations the model is also found to aid in making design decisions for thermal-hydraulic systems. Model components, empirical correlations, and model parameters are discussed; sample procedures are also given. Modifications are cited, and significant development and application efforts are noted focusing on examination of instrumentation required during and after accidents to ensure adequate monitoring during transient conditions.

  10. A Review of Significant Advances in Neutron Imaging from Conception to the Present

    NASA Astrophysics Data System (ADS)

    Brenizer, J. S.

    This review summarizes the history of neutron imaging with a focus on the significant events and technical advancements in neutron imaging methods, from the first radiograph to more recent imaging methods. A timeline is presented to illustrate the key accomplishments that advanced the neutron imaging technique. Only three years after the discovery of the neutron by English physicist James Chadwick in 1932, neutron imaging began with the work of Hartmut Kallmann and Ernst Kuhn in Berlin, Germany, from 1935-1944. Kallmann and Kuhn were awarded a joint US Patent issued in January 1940. Little progress was made until the mid-1950's when Thewlis utilized a neutron beam from the BEPO reactor at Harwell, marking the beginning of the application of neutron imaging to practical applications. As the film method was improved, imaging moved from a qualitative to a quantitative technique, with applications in industry and in nuclear fuels. Standards were developed to aid in the quantification of the neutron images and the facility's capabilities. The introduction of dynamic neutron imaging (initially called real-time neutron radiography and neutron television) in the late 1970's opened the door to new opportunities and new challenges. As the electronic imaging matured, the introduction of the CCD imaging devices and solid-state light intensifiers helped address some of these challenges. Development of improved imaging devices for the medical community has had a major impact on neutron imaging. Additionally, amorphous silicon sensors provided improvements in temporal resolution, while providing a reasonably large imaging area. The development of new neutron imaging sensors and the development of new neutron imaging techniques in the past decade has advanced the technique's ability to provide insight and understanding of problems that other non-destructive techniques could not provide. This rapid increase in capability and application would not have been possible without the

  11. Parameter estimation of neutron star-black hole binaries using an advanced gravitational-wave detector network: Effects of the full post-Newtonian waveform

    NASA Astrophysics Data System (ADS)

    Tagoshi, Hideyuki; Mishra, Chandra Kant; Pai, Archana; Arun, K. G.

    2014-07-01

    We investigate the effects of using the full waveform (FWF) over the conventional restricted waveform of the inspiral signal from a coalescing compact binary system in extracting the parameters of the source, using a global network of second generation interferometric detectors. We study a hypothetical population of (1.4-10)M⊙ neutron star-black hole binaries (uniformly distributed and oriented in the sky) by employing the full post-Newtonian waveforms, which not only include contributions from various harmonics other than the dominant one (quadrupolar mode) but also the post-Newtonian amplitude corrections associated with each harmonic, of the inspiral signal expected from this system. It is expected that the GW detector network consisting of the two LIGO detectors and a Virgo detector will be joined by KAGRA (a Japanese detector) and by proposed LIGO-India. We study the problem of parameter estimation with all 16 possible detector configurations. Comparing medians of error distributions obtained using FWFs with those obtained using restricted waveforms (which only include contributions from the dominant harmonic with Newtonian amplitude) we find that the measurement accuracies for luminosity distance and the cosine of the inclination angle improve almost by a factor of 1.5-2 depending upon the network under consideration. We find that this improvement can be attributed to the presence of additional inclination angle dependent terms, which appear in the amplitude corrections to various harmonics, which break the strong degeneracy between the luminosity distance and inclination angle. Although the use of FWF does not improve the source localization accuracy much, the global network consisting of five detectors will improve the source localization accuracy by a factor of 4 as compared to the estimates using a three-detector LIGO-Virgo network for the same waveform model.

  12. Characterization of core debris/concrete interactions for the Advanced Neutron Source

    SciTech Connect

    Hyman, C.R.; Taleyarkhan, R.P.

    1992-02-01

    This report provides the results of a recent study conducted to explore the molten core/concrete interaction (MCCI) issue for the Advanced Neutron Source (ANS). The need for such a study arises from the potential threats to reactor system integrity posed by MCCI. These threats include direct attack of the concrete basemat of the containment; generation and release of large quantities of gas that can pressurize the containment; the combustion threat of these gases; and the potential generation, release, and transport of radioactive aerosols to the environment.

  13. Design of the cold neutron triple-axis spectrometer at the China Advanced Research Reactor

    NASA Astrophysics Data System (ADS)

    Cheng, P.; Zhang, Hongxia; Bao, W.; Schneidewind, A.; Link, P.; Grünwald, A. T. D.; Georgii, R.; Hao, L. J.; Liu, Y. T.

    2016-06-01

    The design of the first cold neutron triple-axis spectrometer at the China Advanced Research Reactor is presented. Based on the Monte Carlo simulations using neutron ray-tracing program McStas, the parameters of major neutron optics in this instrument are optimized. The neutron flux at sample position is estimated to be 5.6 ×107 n/cm2/s at neutron incident energy Ei=5 meV when the reactor operates normally at the designed 60 MW power. The performances of several neutron supermirror polarizing devices are compared and their critical parameters are optimized for this spectrometer. The polarization analysis will be realized with a flexible switch from the unpolarized experimental mode.

  14. Advanced Microstructured Semiconductor Neutron Detectors: Design, Fabrication, and Performance

    NASA Astrophysics Data System (ADS)

    Bellinger, Steven Lawrence

    The microstructured semiconductor neutron detector (MSND) was investigated and previous designs were improved and optimized. In the present work, fabrication techniques have been refined and improved to produce three-dimensional microstructured semiconductor neutron detectors with reduced leakage current, reduced capacitance, highly anisotropic deep etched trenches, and increased signal-to-noise ratios. As a result of these improvements, new MSND detection systems function with better gamma-ray discrimination and are easier to fabricate than previous designs. In addition to the microstructured diode fabrication improvement, a superior batch processing backfill-method for 6LiF neutron reactive material, resulting in a nearly-solid backfill, was developed. This method incorporates a LiF nano-sizing process and a centrifugal batch process for backfilling the nanoparticle LiF material. To better transition the MSND detector to commercialization, the fabrication process was studied and enhanced to better facilitate low cost and batch process MSND production. The research and development of the MSND technology described in this work includes fabrication of variant microstructured diode designs, which have been simulated through MSND physics models to predict performance and neutron detection efficiency, and testing the operational performance of these designs in regards to neutron detection efficiency, gamma-ray rejection, and silicon fabrication methodology. The highest thermal-neutron detection efficiency reported to date for a solid-state semiconductor detector is presented in this work. MSNDs show excellent neutron to gamma-ray (n/γ) rejection ratios, which are on the order of 106, without significant loss in thermal-neutron detection efficiency. Individually, the MSND is intrinsically highly sensitive to thermal neutrons, but not extrinsically sensitive because of their small size. To improve upon this, individual MSNDs were tiled together into a 6x6-element array

  15. Advancements in the development of a directional-position sensing fast neutron detector using acoustically tensioned metastable fluids

    NASA Astrophysics Data System (ADS)

    Archambault, Brian C.; Webster, Jeffrey A.; Grimes, Thomas F.; Fischer, Kevin F.; Hagen, Alex R.; Taleyakhan, Rusi P.

    2015-06-01

    Advancements in the development of a direction and position sensing fast neutron detector which utilizes the directional acoustic tensioned metastable fluid detector (D-ATMFD) are described. The resulting D-ATMFD sensor is capable of determining the direction of neutron radiation with a single compact detector versus use of arrays of detectors in conventional directional systems. Directional neutron detection and source positioning offer enhanced detection speeds in comparison to traditional proximity searching; including enabling determination of the neutron source shape, size, and strength in near real time. This paper discusses advancements that provide the accuracy and precision of ascertaining directionality and source localization information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and on-demand enlargement capability of the detector sensitive volume. These advancements were accomplished utilizing experimentation and theoretical modeling. Benchmarking and qualifications studies were successfully conducted with random and fission based special nuclear material (SNM) neutron sources (239Pu-Be and 252Cf). These results of assessments have indicated that the D-ATMFD compares well in technical performance with banks of competing directional fast neutron detector technologies under development worldwide, but it does so with a single detector unit, an unlimited field of view, and at a significant reduction in both cost and size while remaining completely blind to common background (e.g., beta-gamma) radiation. Rapid and direct SNM neutron source imaging with two D-ATMFD sensors was experimentally demonstrated, and furthermore, validated via multidimensional nuclear particle transport simulations utilizing MCNP-PoliMi. Characterization of a scaled D-ATMFD based radiation portal monitor (RPM) as a cost-effective and efficient 3He sensor replacement was performed utilizing MCNP-PoliMi simulations, the results of which

  16. An Improved Neutron Transport Algorithm for HZETRN

    NASA Technical Reports Server (NTRS)

    Slaba, Tony C.; Blattnig, Steve R.; Clowdsley, Martha S.; Walker, Steven A.; Badavi, Francis F.

    2010-01-01

    Long term human presence in space requires the inclusion of radiation constraints in mission planning and the design of shielding materials, structures, and vehicles. In this paper, the numerical error associated with energy discretization in HZETRN is addressed. An inadequate numerical integration scheme in the transport algorithm is shown to produce large errors in the low energy portion of the neutron and light ion fluence spectra. It is further shown that the errors result from the narrow energy domain of the neutron elastic cross section spectral distributions, and that an extremely fine energy grid is required to resolve the problem under the current formulation. Two numerical methods are developed to provide adequate resolution in the energy domain and more accurately resolve the neutron elastic interactions. Convergence testing is completed by running the code for various environments and shielding materials with various energy grids to ensure stability of the newly implemented method.

  17. Initial global 2-D shielding analysis for the Advanced Neutron Source core and reflector

    SciTech Connect

    Bucholz, J.A.

    1995-08-01

    This document describes the initial global 2-D shielding analyses for the Advanced Neutron Source (ANS) reactor, the D{sub 2}O reflector, the reflector vessel, and the first 200 mm of light water beyond the reflector vessel. Flux files generated here will later serve as source terms in subsequent shielding analyses. In addition to reporting fluxes and other data at key points of interest, a major objective of this report was to document how these analyses were performed, the phenomena that were included, and checks that were made to verify that these phenomena were properly modeled. In these shielding analyses, the fixed neutron source distribution in the core was based on the `lifetime-averaged` spatial power distribution. Secondary gamma production cross sections in the fuel were modified so as to account intrinsically for delayed fission gammas in the fuel as well as prompt fission gammas. In and near the fuel, this increased the low-energy gamma fluxes by 50 to 250%, but out near the reflector vessel, these same fluxes changed by only a few percent. Sensitivity studies with respect to mesh size were performed, and a new 2-D mesh distribution developed after some problems were discovered with respect to the use of numerous elongated mesh cells in the reflector. All of the shielding analyses were performed sing the ANSL-V 39n/44g coupled library with 25 thermal neutron groups in order to obtain a rigorous representation of the thermal neutron spectrum throughout the reflector. Because of upscatter in the heavy water, convergence was very slow. Ultimately, the fission cross section in the various materials had to be artificially modified in order to solve this fixed source problem as an eigenvalue problem and invoke the Vondy error-mode extrapolation technique which greatly accelerated convergence in the large 2-D RZ DORT analyses. While this was quite effective, 150 outer iterations (over energy) were still required.

  18. Coded aperture Fast Neutron Analysis: Latest design advances

    NASA Astrophysics Data System (ADS)

    Accorsi, Roberto; Lanza, Richard C.

    2001-07-01

    Past studies have showed that materials of concern like explosives or narcotics can be identified in bulk from their atomic composition. Fast Neutron Analysis (FNA) is a nuclear method capable of providing this information even when considerable penetration is needed. Unfortunately, the cross sections of the nuclear phenomena and the solid angles involved are typically small, so that it is difficult to obtain high signal-to-noise ratios in short inspection times. CAFNAaims at combining the compound specificity of FNA with the potentially high SNR of Coded Apertures, an imaging method successfully used in far-field 2D applications. The transition to a near-field, 3D and high-energy problem prevents a straightforward application of Coded Apertures and demands a thorough optimization of the system. In this paper, the considerations involved in the design of a practical CAFNA system for contraband inspection, its conclusions, and an estimate of the performance of such a system are presented as the evolution of the ideas presented in previous expositions of the CAFNA concept.

  19. Final LDRD report : advanced plastic scintillators for neutron detection.

    SciTech Connect

    Vance, Andrew L.; Mascarenhas, Nicholas; O'Bryan, Greg; Mrowka, Stanley

    2010-09-01

    This report summarizes the results of a one-year, feasibility-scale LDRD project that was conducted with the goal of developing new plastic scintillators capable of pulse shape discrimination (PSD) for neutron detection. Copolymers composed of matrix materials such as poly(methyl methacrylate) (PMMA) and blocks containing trans-stilbene (tSB) as the scintillator component were prepared and tested for gamma/neutron response. Block copolymer synthesis utilizing tSBMA proved unsuccessful so random copolymers containing up to 30% tSB were prepared. These copolymers were found to function as scintillators upon exposure to gamma radiation; however, they did not exhibit PSD when exposed to a neutron source. This project, while falling short of its ultimate goal, demonstrated the possible utility of single-component, undoped plastics as scintillators for applications that do not require PSD.

  20. Global shielding analysis for the three-element core advanced neutron source reactor under normal operating conditions

    SciTech Connect

    Slater, C.O.; Bucholz, J.A.

    1995-08-01

    Two-dimensional discrete ordinates radiation transport calculations were performed for a model of the three-element core Advanced Neutron Source reactor design under normal operating conditions. The core consists of two concentric upper elements and a lower element radially centered in the annulus between the upper elements. The initial radiation transport calculations were performed with the DORT two-dimensional discrete ordinates radiation transport code using the 39-neutron-group/44-gamma-ray-group ANSL-V cross-section library, an S{sub 6} quadrature, and a P{sub 1} Legendre polynomial expansion of the cross sections to determine the fission neutron source distribution in the core fuel elements. These calculations were limited to neutron groups only. The final radiation transport calculations, also performed with DORT using the 39-neutron-group/44-gamma-ray-group ANSL-V cross-section library, an S{sub l0} quadrature, and a P{sub 3} Legendre polynomial expansion of the cross sections, produced neutron and gamma-ray fluxes over the full extent of the geometry model. Responses (or activities) at various locations in the model were then obtained by folding the appropriate response functions with the fluxes at those locations. Some comparisons were made with VENTURE-calculated (diffusion theory) 20-group neutron fluxes that were summed into four broad groups. Tne results were in reasonably good agreement when the effects of photoneutrons were not included, thus verifying the physics model upon which the shielding model was based. Photoneutrons increased the fast-neutron flux levels deep within the D{sub 2}0 several orders of magnitude. Results are presented as tables of activity values for selected radial and axial traverses, plots of the radial and axial traverse data, and activity contours superimposed on the calculational geometry model.

  1. Reactor physics analyses of the advanced neutron source three-element core

    SciTech Connect

    Gehin, J.C.

    1995-08-01

    A reactor physics analysis was performed for the Advanced Neutron Source reactor with a three-element core configuration. The analysis was performed with a two-dimensional r-z 20-energy-group finite-difference diffusion theory model of the 17-d fuel cycle. The model included equivalent r-z geometry representations of the central control rods, the irradiation and production targets, and reflector components. Calculated quantities include fuel cycle parameters, fuel element power distributions, unperturbed neutron fluxes in the reflector and target regions, reactivity perturbations, and neutron kinetics parameters.

  2. Neutronics investigation of advanced self-cooled liquid blanket systems in the helical reactor

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Sagara, A.; Muroga, T.; Youssef, M. Z.

    2008-03-01

    Neutronics investigations have been conducted in the design activity of the helical-type reactor Force Free Helical Reactor (FFHR2) adopting Flibe-cooled and Li-cooled advanced liquid blanket systems. In this study, comprehensive investigations and geometry modifications related to the tritium breeding ratios (TBRs), neutron shielding performance and neutron wall loading on the first walls in FFHR2 have been performed by improving the three-dimensional (3D) neutronics calculation system developed for non-axisymmetric helical designs. The total TBRs obtained after modifying the blanket dimensions indicated that all the advanced blanket systems proposed for FFHR2 would achieve adequate tritium self-sufficiency by dimension adjustment and optimization of structures in the breeder layers. However, it appeared that the most important neutronics issue in the present helical blanket configuration was suppression of neutron streaming through the divertor pumping areas and reflection from support structures for protection of poloidal and helical coils. Evaluation of neutron wall loading on the first walls indicated that the peaking factor would be moderated as low as 1.2 by the toroidal and helical effect of the helical-shaped plasma distribution in the helical reactor.

  3. New generation of cryogen free advanced superconducting magnets for neutron scattering experiments

    NASA Astrophysics Data System (ADS)

    Kirichek, O.; Brown, J.; Adroja, D. T.; Manuel, P.; Kouzmenko, G.; Bewley, R. I.; Wotherspoon, R.

    2012-12-01

    Recent advances in superconducting technology and cryocooler refrigeration have resulted in a new generation of advanced superconducting magnets for neutron beam applications. These magnets have outstanding parameters such as high homogeneity and stability at highest magnetic fields possible, a reasonably small stray field, low neutron scattering background and larger exposure to neutron detectors. At the same time the pulse tube refrigeration technology provides a complete re-condensing regime which allows to minimise the requirements for cryogens without introducing additional noise and mechanical vibrations. The magnets can be used with dilution refrigerator insert which expands the temperature range from 20mK to 300K. Here we are going to present design, test results and the operational data of the 14T magnet for neutron diffraction and the 9T wide angle chopper magnet for neutron spectroscopy developed by Oxford Instruments in collaboration with ISIS neutron source. First scientific results obtained from the neutron scattering experiments with these magnets are also going to be discussed.

  4. Neutron radiography as a non-destructive method for diagnosing neutron converters for advanced thermal neutron detectors

    NASA Astrophysics Data System (ADS)

    Muraro, A.; Albani, G.; Perelli Cippo, E.; Croci, G.; Angella, G.; Birch, J.; Cazzaniga, C.; Caniello, R.; Dell'Era, F.; Ghezzi, F.; Grosso, G.; Hall-Wilton, R.; Höglund, C.; Hultman, L.; Schimdt, S.; Robinson, L.; Rebai, M.; Salvato, G.; Tresoldi, D.; Vasi, C.; Tardocchi, M.

    2016-03-01

    Due to the well-known problem of 3He shortage, a series of different thermal neutron detectors alternative to helium tubes are being developed, with the goal to find valid candidates for detection systems for the future spallation neutron sources such as the European Spallation Source (ESS). A possible 3He-free detector candidate is a charged particle detector equipped with a three dimensional neutron converter cathode (3D-C). The 3D-C currently under development is composed by a series of alumina (Al2O3) lamellas coated by 1 μ m of 10B enriched boron carbide (B4C). In order to obtain a good characterization in terms of detector efficiency and uniformity it is crucial to know the thickness, the uniformity and the atomic composition of the B4C neutron converter coating. In this work a non-destructive technique for the characterization of the lamellas that will compose the 3D-C was performed using neutron radiography. The results of these measurements show that the lamellas that will be used have coating uniformity suitable for detector applications. This technique (compared with SEM, EDX, ERDA, XPS) has the advantage of being global (i.e. non point-like) and non-destructive, thus it is suitable as a check method for mass production of the 3D-C elements.

  5. Neutron radiography of thick hydrogenous materials with use of an imaging plate neutron detector

    NASA Astrophysics Data System (ADS)

    Kato, Kazuo; Matsumoto, Gen'ichi; Karasawa, Yuuko; Niimura, Nobuo; Matsubayashi, Masahito; Tsuruno, Akira

    1996-02-01

    The value of the neutron mass attenuation coefficient of hydrogen being very high, it is extremely difficult to image normal size, living animals with neutron radiography. However, the authors suggest the possibility of applying neutron radiography for biomedical specimens. The organs in the breast, bones and cartilages in the extremities, and the tail of mice and rats were clearly imaged by neutron radiography with Gd foils as neutron converters and X-ray films. However, no contours of the organs in the mouse abdomen were visible with neutron radiography with an exposure time of 200 s. By adding Gd or Li compounds as neutron converters to imaging X-ray plates, imaging plates have been developed for neutron detectors. A trial using these imaging plates for neutron radiography of water-filled containers and the abdomen of mice was completed. The roundness of a 100 ml-beaker was imaged with a neutron exposure of 180 s. Obscure contours of the liver and kidneys of the mouse were imaged with a neutron exposure of 100 s.

  6. The ion beam sputtering facility at KURRI: Coatings for advanced neutron optical devices

    NASA Astrophysics Data System (ADS)

    Hino, Masahiro; Oda, Tatsuro; Kitaguchi, Masaaki; Yamada, Norifumi L.; Tasaki, Seiji; Kawabata, Yuji

    2015-10-01

    We describe a film coating facility for the development of multilayer mirrors for use in neutron optical devices that handle slow neutron beams. Recently, we succeeded in fabricating a large neutron supermirror with high reflectivity using an ion beam sputtering system (KUR-IBS), as well as all neutron supermirrors in two neutron guide tubes at BL06 at J-PARC/MLF. We also realized a large flexible self-standing m=5 NiC/Ti supermirror and very small d-spacing (d=1.65 nm) multilayer sheets. In this paper, we present an overview of the performance and utility of non-magnetic neutron multilayer mirrors fabricated with the KUR-IBS

  7. Modeling and analysis of hydrogen detonation events in the Advanced Neutron Source reactor containment

    SciTech Connect

    Taleyarkhan, R.P.; Georgevich, V.; Kim, S.H.; Valenti, S.N.; Simpson, D.B.; Sawruk, W.

    1994-07-01

    This paper describes salient aspects of the modeling, analyses, and evaluations for hydrogen detonation in selected regions of the Advanced Neutron Source (ANS) containment during hypothetical severe accident conditions. Shock wave generation and transport modeling and analyses were conducted for two stratified configurations in the dome region of the high bay. Principal tools utilized for these purposes were the CTH and CET89 computer codes. Dynamic pressure loading functions were generated for key locations and used for evaluating structural response behavior for which a finite-element model was developed using the ANSYS code. For the range of conditions analyzed in the two critical dome regions, it was revealed that the ANS containment would be able to withstand detonation loads without failure.

  8. In-Pile Experiment of a New Hafnium Aluminide Composite Material to Enable Fast Neutron Testing in the Advanced Test Reactor

    SciTech Connect

    Donna Post Guillen; Douglas L. Porter; James R. Parry; Heng Ban

    2010-06-01

    A new hafnium aluminide composite material is being developed as a key component in a Boosted Fast Flux Loop (BFFL) system designed to provide fast neutron flux test capability in the Advanced Test Reactor. An absorber block comprised of hafnium aluminide (Al3Hf) particles (~23% by volume) dispersed in an aluminum matrix can absorb thermal neutrons and transfer heat from the experiment to pressurized water cooling channels. However, the thermophysical properties, such as thermal conductivity, of this material and the effect of irradiation are not known. This paper describes the design of an in-pile experiment to obtain such data to enable design and optimization of the BFFL neutron filter.

  9. An Evaluation of Grazing-Incidence Optics for Neutron Imaging

    NASA Technical Reports Server (NTRS)

    Gubarev, M. V.; Ramsey, B. D.; Engelhaupt, D. E.; Burgess, J.; Mildner, D. F. R.

    2007-01-01

    The focusing capabilities of neutron imaging optic based on the Wolter-1 geometry have been successfully demonstrated with a beam of long wavelength neutrons with low angular divergence.. A test mirror was fabricated using an electroformed nickel replication process at Marshall Space Flight Center. The neutron current density gain at the focal spot of the mirror is found to be at least 8 for neutron wavelengths in the range from 6 to 20 A. Possible applications of the optics are briefly discussed.

  10. Improved computational neutronics methods and validation protocols for the advanced test reactor

    SciTech Connect

    Nigg, D. W.; Nielsen, J. W.; Chase, B. M.; Murray, R. K.; Steuhm, K. A.; Unruh, T.

    2012-07-01

    The Idaho National Laboratory (INL) is in the process of updating the various reactor physics modeling and simulation tools used to support operation and safety assurance of the Advanced Test Reactor (ATR). Key accomplishments so far have encompassed both computational as well as experimental work. A new suite of stochastic and deterministic transport theory based reactor physics codes and their supporting nuclear data libraries (HELIOS, KENO6/SCALE, NEWT/SCALE, ATTILA, and an extended implementation of MCNP5) has been installed at the INL. Corresponding models of the ATR and ATRC are now operational with all five codes, demonstrating the basic feasibility of the new code packages for their intended purposes. On the experimental side of the project, new hardware was fabricated, measurement protocols were finalized, and the first four of six planned physics code validation experiments based on neutron activation spectrometry have been conducted at the ATRC facility. Data analysis for the first three experiments, focused on characterization of the neutron spectrum in one of the ATR flux traps, has been completed. The six experiments will ultimately form the basis for flexible and repeatable ATR physics code validation protocols that are consistent with applicable national standards. (authors)

  11. IMPROVED COMPUTATIONAL NEUTRONICS METHODS AND VALIDATION PROTOCOLS FOR THE ADVANCED TEST REACTOR

    SciTech Connect

    David W. Nigg; Joseph W. Nielsen; Benjamin M. Chase; Ronnie K. Murray; Kevin A. Steuhm

    2012-04-01

    The Idaho National Laboratory (INL) is in the process of modernizing the various reactor physics modeling and simulation tools used to support operation and safety assurance of the Advanced Test Reactor (ATR). Key accomplishments so far have encompassed both computational as well as experimental work. A new suite of stochastic and deterministic transport theory based reactor physics codes and their supporting nuclear data libraries (HELIOS, KENO6/SCALE, NEWT/SCALE, ATTILA, and an extended implementation of MCNP5) has been installed at the INL. Corresponding models of the ATR and ATRC are now operational with all five codes, demonstrating the basic feasibility of the new code packages for their intended purpose. Of particular importance, a set of as-run core depletion HELIOS calculations for all ATR cycles since August 2009 was successfully completed during 2011. This demonstration supported a decision late in the year to proceed with the phased incorporation of the HELIOS methodology into the ATR fuel cycle management process beginning in 2012. On the experimental side of the project, new hardware was fabricated, measurement protocols were finalized, and the first four of six planned physics code validation experiments based on neutron activation spectrometry were conducted at the ATRC facility. Data analysis for the first three experiments, focused on characterization of the neutron spectrum in one of the ATR flux traps, has been completed. The six experiments will ultimately form the basis for a flexible, easily-repeatable ATR physics code validation protocol that is consistent with applicable ASTM standards.

  12. Review and Assessment of Neutron Cross Section and Nubar Covariances for Advanced Reactor Systems

    SciTech Connect

    Maslov,V.M.; Oblozinsky, P.; Herman, M.

    2008-12-01

    In January 2007, the National Nuclear Data Center (NNDC) produced a set of preliminary neutron covariance data for the international project 'Nuclear Data Needs for Advanced Reactor Systems'. The project was sponsored by the OECD Nuclear Energy Agency (NEA), Paris, under the Subgroup 26 of the International Working Party on Evaluation Cooperation (WPEC). These preliminary covariances are described in two recent BNL reports. The NNDC used a simplified version of the method developed by BNL and LANL that combines the recent Atlas of Neutron Resonances, the nuclear reaction model code EMPIRE and the Bayesian code KALMAN with the experimental data used as guidance. There are numerous issues involved in these estimates of covariances and it was decided to perform an independent review and assessment of these results so that better covariances can be produced for the revised version in future. Reviewed and assessed are uncertainties for fission, capture, elastic scattering, inelastic scattering and (n,2n) cross sections as well as prompt nubars for 15 minor actinides ({sup 233,234,236}U, {sup 237}Np, {sup 238,240,241,242}Pu, {sup 241,242m,243}Am and {sup 242,243,244,245}Cm) and 4 major actinides ({sup 232}Th, {sup 235,238}U and {sup 239}Pu). We examined available evaluations, performed comparison with experimental data, taken into account uncertainties in model parameterization and made use state-of-the-art nuclear reaction theory to produce the uncertainty assessment.

  13. Conceptual design of an RFQ accelerator-based neutron source for boron neutron-capture therapy

    SciTech Connect

    Wangler, T.P.; Stovall, J.E.; Bhatia, T.S.; Wang, C.K.; Blue, T.E.; Gahbauer, R.A.

    1989-01-01

    We present a conceptual design of a low-energy neutron generator for treatment of brain tumors by boron neutron capture theory (BNCT). The concept is based on a 2.5-MeV proton beam from a radio-frequency quadrupole (RFQ) linac, and the neutrons are produced by the /sup 7/Li(p,n)/sup 7/Be reaction. A liquid lithium target and modulator assembly are designed to provide a high flux of epithermal neutrons. The patient is administered a tumor-specific /sup 10/Be-enriched compound and is irradiated by the neutrons to create a highly localized dose from the reaction /sup 10/B(n,..cap alpha..)/sup 7/Li. An RFQ accelerator-based neutron source for BNCT is compact, which makes it practical to site the facility within a hospital. 11 refs., 5 figs., 1 tab.

  14. Development of Advanced Multi-Modality Radiation Treatment Planning Software for Neutron Radiotherapy and Beyond

    SciTech Connect

    Nigg, D; Wessol, D; Wemple, C; Harkin, G; Hartmann-Siantar, C

    2002-08-20

    The Idaho National Engineering and Environmental Laboratory (INEEL) has long been active in development of advanced Monte-Carlo based computational dosimetry and treatment planning methods and software for advanced radiotherapy, with a particular focus on Neutron Capture Therapy (NCT) and, to a somewhat lesser extent, Fast-Neutron Therapy. The most recent INEEL software system of this type is known as SERA, Simulation Environment for Radiotherapy Applications. As a logical next step in the development of modern radiotherapy planning tools to support the most advanced research, INEEL and Lawrence Livermore National Laboratory (LLNL), the developers of the PEREGRTNE computational engine for radiotherapy treatment planning applications, have recently launched a new project to collaborate in the development of a ''next-generation'' multi-modality treatment planning software system that will be useful for all modern forms of radiotherapy.

  15. An in-phantom comparison of neutron fields for BNCT

    SciTech Connect

    Woollard, J.E.; Blue, T.E.; Capala, J.

    1998-01-01

    Previously, the authors have developed the in-phantom neutron field assessment parameters T and D (Tumor) for the evaluation of epithermal neutron fields for use in BNCT. These parameters are based on an energy-spectrum-dependent neutron normal-tissue RBE and the treatment planning methodology of Gahbauer and his co-workers, which includes the effects of dose fractionation. In this paper, these neutron field assessment parameters were applied to The Ohio State University (OSU) design of an Accelerator Based Neutron Source (ABNS) (hereafter called the OSU-ABNS) and the Brookhaven Medical Research Reactor (BMRR) epithermal neutron beam (hereafter called the BMRR-ENB), in order to judge the suitability of the OSU-ABNS for BNCT. The BMRR-ENB was chosen as the basis for comparison because it is presently being used in human clinical trials of BNCT and because it is the standard to which other neutron beams are most often compared.

  16. Neutron and X-Ray Studies of Advanced Materials V: CENTENNIAL

    SciTech Connect

    Spanos, George

    2012-05-01

    In 2012 the diffraction community will celebrate 100 years since the prediction of X-ray diffraction by M. Laue, and following his suggestion the first beautiful diffraction experiment by W. Friedrich and P. Knipping. The significance of techniques based on the analysis of the diffraction of X-rays, neutrons, electrons and Mossbauer photons discovered later, has continued to increase in the past 100 years. The aim of this symposium is to provide a forum for discussion of using state-of-the-art neutron and X-ray scattering techniques for probing advanced materials. These techniques have been widely used to characterize materials structures across all length scales, from atomic to nano, meso, and macroscopic scales. With the development of sample environments, in-situ experiments, e.g., at temperatures and applied mechanical load, are becoming routine. The development of ultra-brilliant third-generation synchrotron X-ray sources, together with advances in X-ray optics, has created intense X-ray microbeams, which provide the best opportunities for in-depth understanding of mechanical behavior in a broad spectrum of materials. Important applications include ultra-sensitive elemental detection by X-ray fluorescence/absorption and microdiffraction to identify phase and strain with submicrometer spatial resolution. X-ray microdiffraction is a particularly exciting application compared with alternative probes of crystalline structure, orientation and strain. X-ray microdiffraction is non-destructive with good strain resolution, competitive or superior spatial resolution in thick samples, and with the ability to probe below the sample surface. Advances in neutron sources and instrumentation also bring new opportunities in neutron scattering research. In addition to characterizing the structures, neutrons are also a great tool for elucidating the dynamics of materials. Because neutrons are highly penetrating, neutrons have been used to map stress in engineering systems

  17. Cadmium Depletion Impacts on Hardening Neutron6 Spectrum for Advanced Fuel Testing in ATR

    SciTech Connect

    Gray S. Chang

    2011-05-01

    For transmuting long-lived isotopes contained in spent nuclear fuel into shorter-lived fission products effectively is in a fast neutron spectrum reactor. In the absence of a fast spectrum test reactor in the United States of America (USA), initial irradiation testing of candidate fuels can be performed in a thermal test reactor that has been modified to produce a test region with a hardened neutron spectrum. A test region is achieved with a Cadmium (Cd) filter which can harden the neutron spectrum to a spectrum similar (although still somewhat softer) to that of the liquid metal fast breeder reactor (LMFBR). A fuel test loop with a Cd-filter has been installed within the East Flux Trap (EFT) of the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL). A detailed comparison analyses between the cadmium (Cd) filter hardened neutron spectrum in the ATR and the LMFBR fast neutron spectrum have been performed using MCWO. MCWO is a set of scripting tools that are used to couple the Monte Carlo transport code MCNP with the isotope depletion and buildup code ORIGEN-2.2. The MCWO-calculated results indicate that the Cd-filter can effectively flatten the Rim-Effect and reduce the linear heat rate (LHGR) to meet the advanced fuel testing project requirements at the beginning of irradiation (BOI). However, the filtering characteristics of Cd as a strong absorber quickly depletes over time, and the Cd-filter must be replaced for every two typical operating cycles within the EFT of the ATR. The designed Cd-filter can effectively depress the LHGR in experimental fuels and harden the neutron spectrum enough to adequately flatten the Rim Effect in the test region.

  18. An Analysis Technique for Active Neutron Multiplicity Measurements Based on First Principles

    SciTech Connect

    Evans, Louise G; Goddard, Braden; Charlton, William S; Peerani, Paolo

    2012-08-13

    Passive neutron multiplicity counting is commonly used to quantify the total mass of plutonium in a sample, without prior knowledge of the sample geometry. However, passive neutron counting is less applicable to uranium measurements due to the low spontaneous fission rates of uranium. Active neutron multiplicity measurements are therefore used to determine the {sup 235}U mass in a sample. Unfortunately, there are still additional challenges to overcome for uranium measurements, such as the coupling of the active source and the uranium sample. Techniques, such as the coupling method, have been developed to help reduce the dependence of calibration curves for active measurements on uranium samples; although, they still require similar geometry known standards. An advanced active neutron multiplicity measurement method is being developed by Texas A&M University, in collaboration with Los Alamos National Laboratory (LANL) in an attempt to overcome the calibration curve requirements. This method can be used to quantify the {sup 235}U mass in a sample containing uranium without using calibration curves. Furthermore, this method is based on existing detectors and nondestructive assay (NDA) systems, such as the LANL Epithermal Neutron Multiplicity Counter (ENMC). This method uses an inexpensive boron carbide liner to shield the uranium sample from thermal and epithermal neutrons while allowing fast neutrons to reach the sample. Due to the relatively low and constant fission and absorption energy dependent cross-sections at high neutron energies for uranium isotopes, fast neutrons can penetrate the sample without significant attenuation. Fast neutron interrogation therefore creates a homogeneous fission rate in the sample, allowing for first principle methods to be used to determine the {sup 235}U mass in the sample. This paper discusses the measurement method concept and development, including measurements and simulations performed to date, as well as the potential

  19. Neutron diffractometer for bio-crystallography (BIX) with an imaging plate neutron detector

    SciTech Connect

    Niimura, Nobuo

    1994-12-31

    We have constructed a dedicated diffractometer for neutron crystallography in biology (BIX) on the JRR-3M reactor at JAERI (Japan Atomic Energy Research Institute). The diffraction intensity from a protein crystal is weaker than that from most inorganic materials. In order to overcome the intensity problem, an elastically bent silicon monochromator and a large area detector system were specially designed. A preliminary result of diffraction experiment using BIX has been reported. An imaging plate neutron detector has been developed and a feasibility experiment was carried out on BIX. Results are reported. An imaging plate neutron detector has been developed and a feasibility test was carried out using BIX.

  20. Innovative and Advanced Coupled Neutron Transport and Thermal Hydraulic Method (Tool) for the Design, Analysis and Optimization of VHTR/NGNP Prismatic Reactors

    SciTech Connect

    Rahnema, Farzad; Garimeela, Srinivas; Ougouag, Abderrafi; Zhang, Dingkang

    2013-11-29

    This project will develop a 3D, advanced coarse mesh transport method (COMET-Hex) for steady- state and transient analyses in advanced very high-temperature reactors (VHTRs). The project will lead to a coupled neutronics and thermal hydraulic (T/H) core simulation tool with fuel depletion capability. The computational tool will be developed in hexagonal geometry, based solely on transport theory without (spatial) homogenization in complicated 3D geometries. In addition to the hexagonal geometry extension, collaborators will concurrently develop three additional capabilities to increase the code’s versatility as an advanced and robust core simulator for VHTRs. First, the project team will develop and implement a depletion method within the core simulator. Second, the team will develop an elementary (proof-of-concept) 1D time-dependent transport method for efficient transient analyses. The third capability will be a thermal hydraulic method coupled to the neutronics transport module for VHTRs. Current advancements in reactor core design are pushing VHTRs toward greater core and fuel heterogeneity to pursue higher burn-ups, efficiently transmute used fuel, maximize energy production, and improve plant economics and safety. As a result, an accurate and efficient neutron transport, with capabilities to treat heterogeneous burnable poison effects, is highly desirable for predicting VHTR neutronics performance. This research project’s primary objective is to advance the state of the art for reactor analysis.

  1. 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

  2. High Neutron Fluence Survivability Testing of Advanced Fiber Bragg Grating Sensors

    NASA Astrophysics Data System (ADS)

    Fielder, Robert S.; Klemer, Daniel; Stinson-Bagby, Kelly L.

    2004-02-01

    The motivation for the reported research was to support NASA space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. The purpose of the high-neutron fluence testing was to demonstrate the survivability of fiber Bragg grating (FBG) sensors in a fission reactor environment. 520 FBGs were installed in the Ford reactor at the University of Michigan. The reactor was operated for 1012 effective full power hours resulting in a maximum neutron fluence of approximately 5×1019 n/cm2, and a maximum gamma dose of 2×103 MGy gamma. This work is significant in that, to the knowledge of the authors, the exposure levels obtained are approximately 1000 times higher than for any previously published experiment. Four different fiber compositions were evaluated. An 87% survival rate was observed for fiber Bragg gratings located at the fuel centerline. Optical Frequency Domain Reflectometry (OFDR), originally developed at the NASA Langley Research Center, can be used to interrogate several thousand low-reflectivity FBG strain and/or temperature sensors along a single optical fiber. A key advantage of the OFDR sensor technology for space nuclear power is the extremely low mass of the sensor, which consists of only a silica fiber 125μm in diameter. The sensors produced using this technology will fill applications in nuclear power for current reactor plants, emerging Generation-IV reactors, and for space nuclear power. The reported research was conducted by Luna Innovations and was funded through a Small Business Innovative Research (SBIR) contract with the NASA Glenn Research Center.

  3. High Neutron Fluence Survivability Testing of Advanced Fiber Bragg Grating Sensors

    SciTech Connect

    Fielder, Robert S.; Klemer, Daniel; Stinson-Bagby, Kelly L.

    2004-02-04

    The motivation for the reported research was to support NASA space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. The purpose of the high-neutron fluence testing was to demonstrate the survivability of fiber Bragg grating (FBG) sensors in a fission reactor environment. 520 FBGs were installed in the Ford reactor at the University of Michigan. The reactor was operated for 1012 effective full power hours resulting in a maximum neutron fluence of approximately 5x1019 n/cm2, and a maximum gamma dose of 2x103 MGy gamma. This work is significant in that, to the knowledge of the authors, the exposure levels obtained are approximately 1000 times higher than for any previously published experiment. Four different fiber compositions were evaluated. An 87% survival rate was observed for fiber Bragg gratings located at the fuel centerline. Optical Frequency Domain Reflectometry (OFDR), originally developed at the NASA Langley Research Center, can be used to interrogate several thousand low-reflectivity FBG strain and/or temperature sensors along a single optical fiber. A key advantage of the OFDR sensor technology for space nuclear power is the extremely low mass of the sensor, which consists of only a silica fiber 125{mu}m in diameter. The sensors produced using this technology will fill applications in nuclear power for current reactor plants, emerging Generation-IV reactors, and for space nuclear power. The reported research was conducted by Luna Innovations and was funded through a Small Business Innovative Research (SBIR) contract with the NASA Glenn Research Center.

  4. Recent advances in polarized 3 He based neutron spin filter development

    NASA Astrophysics Data System (ADS)

    Chen, Wangchun; Gentile, Thomas; Erwin, Ross; Watson, Shannon; Krycka, Kathryn; Ye, Qiang; NCNR NIST Team; University of Maryland Team

    2015-04-01

    Polarized 3 He neutron spin filters (NSFs) are based on the strong spin-dependence of the neutron absorption cross section by 3 He. NSFs can polarize large area, widely divergent, and broadband neutron beams effectively and allow for combining a neutron polarizer and a spin flipper into a single polarizing device. The last capability utilizes 3 He spin inversion based on the adiabatic fast passage (AFP) nuclear magnetic resonance technique. Polarized 3 He NSFs are significantly expanding the polarized neutron measurement capabilities at the NIST Center for Neutron Research (NCNR). Here we present an overview of 3 He NSF applications to small-angle neutron scattering, thermal triple axis spectrometry, and wide-angle polarization analysis. We discuss a recent upgrade of our spin-exchange optical pumping (SEOP) systems that utilize chirped volume holographic gratings for spectral narrowing. The new capability allows us to polarize rubidium/potassium hybrid SEOP cells over a liter in volume within a day, with 3 He polarizations up to 88%, Finally we discuss how we can achieve nearly lossless 3 He polarization inversion with AFP.

  5. Preliminary fracture analysis of the core pressure boundary tube for the Advanced Neutron Source Research Reactor

    SciTech Connect

    Schulz, K.C.; Yahr, G.T.

    1995-08-01

    The outer core pressure boundary tube (CPBT) of the Advanced neutron Source (ANS) reactor being designed at Oak Ridge National Laboratory is currently specified as being composed of 6061-T6 aluminum. ASME Boiler and Pressure Vessel Code fracture analysis rules for nuclear components are based on the use of ferritic steels; the expressions, tables, charts and equations were all developed from tests and analyses conducted for ferritic steels. Because of the nature of the Code, design with thin aluminum requires analytical approaches that do not directly follow the Code. The intent of this report is to present a methodology comparable to the ASME Code for ensuring the prevention of nonductile fracture of the CPBT in the ANS reactor. 6061-T6 aluminum is known to be a relatively brittle material; the linear elastic fracture mechanics (LEFM) approach is utilized to determine allowable flaw sizes for the CPBT. A J-analysis following the procedure developed by the Electric Power Research Institute was conducted as a check; the results matched those for the LEFM analysis for the cases analyzed. Since 6061-T6 is known to embrittle when irradiated, the reduction in K{sub Q} due to irradiation is considered in the analysis. In anticipation of probable requirements regarding maximum allowable flaw size, a survey of nondestructive inspection capabilities is also presented. A discussion of probabilistic fracture mechanics approaches, principally Monte Carlo techniques, is included in this report as an introduction to what quantifying the probability of nonductile failure of the CPBT may entail.

  6. High Conduction Neutron Absorber to Simulate Fast Reactor Environment in an Existing Test Reactor

    SciTech Connect

    Guillen, Donna; Greenwood, Lawrence R.; Parry, James

    2014-06-22

    A need was determined for a thermal neutron absorbing material that could be cooled in a gas reactor environment without using large amounts of a coolant that would thermalize the neutron flux. A new neutron absorbing material was developed that provided high conduction so a small amount of water would be sufficient for cooling thereby thermalizing the flux as little as possible. An irradiation experiment was performed to assess the effects of radiation and the performance of a new neutron absorbing material. Neutron fluence monitors were placed inside specially fabricated holders within a set of drop-in capsules and irradiated for up to four cycles in the Advanced Test Reactor. Following irradiation, the neutron fluence monitor wires were analyzed by gamma and x-ray spectrometry to determine the activities of the activation products. The adjusted neutron fluences were calculated and grouped into three bins – thermal, epithermal and fast to evaluate the spectral shift created by the new material. Fluence monitors were evaluated after four different irradiation periods to evaluate the effects of burn-up in the absorbing material. Additionally, activities of the three highest activity isotopes present in the specimens are given.

  7. Neutron matter, symmetry energy and neutron stars

    SciTech Connect

    Stefano, Gandolfi; Steiner, Andrew W

    2016-01-01

    Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

  8. Fluence and dose measurements for an accelerator neutron beam

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Byun, S. H.; McNeill, F. E.; Mothersill, C. E.; Seymour, C. B.; Prestwich, W. V.

    2007-10-01

    The 3 MV Van de Graaff accelerator at McMaster University accelerator laboratory is extended to a neutron irradiation facility for low-dose bystander effects research. A long counter and an Anderson-Braun type neutron monitor have been used as monitors for the determination of the total fluence. Activation foils were used to determine the thermal neutron fluence rate (around 106 neutrons s-1). Meanwhile, the interactions of neutrons with the monitors have been simulated using a Monte Carlo N Particle (MCNP) code. Bystander effects, i.e. damage occurring in cells that were not traversed by radiation but were in the same radiation environment, have been well observed following both alpha and gamma irradiation of many cell lines. Since neutron radiation involves mixed field (including gamma and neutron radiations), we need to differentiate the doses for the bystander effects from the two radiations. A tissue equivalent proportional counter (TEPC) filled with propane based tissue equivalent gas simulating a 2 μm diameter tissue sphere has been investigated to estimate the neutron and gamma absorbed doses. A photon dose contamination of the neutron beam is less than 3%. The axial dose distribution follows the inverse square law and lateral and vertical dose distributions are relatively uniform over the irradiation area required by the biological study.

  9. Thermal neutron imaging in an active interrogation environment

    SciTech Connect

    Vanier,P.E.; Forman, L., and Norman, D.R.

    2009-03-10

    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

  10. Design of a magnetic shielding system for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Cui, Z. Q.; Chen, Z. J.; Xie, X. F.; Peng, X. Y.; Hu, Z. M.; Du, T. F.; Ge, L. J.; Zhang, X.; Yuan, X.; Fan, T. S.; Chen, J. X.; Li, X. Q. E-mail: guohuizhang@pku.edu.cn; Zhang, G. H. E-mail: guohuizhang@pku.edu.cn; Xia, Z. W.; Hu, L. Q.; Zhong, G. Q.; Lin, S. Y.; Wan, B. N.

    2014-11-15

    The novel neutron spectrometer TOFED (Time of Flight Enhanced Diagnostics), comprising 90 individual photomultiplier tubes coupled with 85 plastic scintillation detectors through light guides, has been constructed and installed at Experimental Advanced Superconducting Tokamak. A dedicated magnetic shielding system has been constructed for TOFED, and is designed to guarantee the normal operation of photomultiplier tubes in the stray magnetic field leaking from the tokamak device. Experimental measurements and numerical simulations carried out employing the finite element method are combined to optimize the design of the magnetic shielding system. The system allows detectors to work properly in an external magnetic field of 200 G.

  11. Design of a magnetic shielding system for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak.

    PubMed

    Cui, Z Q; Chen, Z J; Xie, X F; Peng, X Y; Hu, Z M; Du, T F; Ge, L J; Zhang, X; Yuan, X; Xia, Z W; Hu, L Q; Zhong, G Q; Lin, S Y; Wan, B N; Fan, T S; Chen, J X; Li, X Q; Zhang, G H

    2014-11-01

    The novel neutron spectrometer TOFED (Time of Flight Enhanced Diagnostics), comprising 90 individual photomultiplier tubes coupled with 85 plastic scintillation detectors through light guides, has been constructed and installed at Experimental Advanced Superconducting Tokamak. A dedicated magnetic shielding system has been constructed for TOFED, and is designed to guarantee the normal operation of photomultiplier tubes in the stray magnetic field leaking from the tokamak device. Experimental measurements and numerical simulations carried out employing the finite element method are combined to optimize the design of the magnetic shielding system. The system allows detectors to work properly in an external magnetic field of 200 G.

  12. The Detector for Advanced Neutron Capture Experiments: A 4{pi} BaF2 Detector for Neutron Capture Measurements at LANSCE

    SciTech Connect

    Ullmann, J.L.; Esch, E.-I.; Haight, R.C.; Hunt, L.; O'Donnell, J.M.; Reifarth, R.; Agvaanluvsan, U.; Alpizar, A.; Hatarik, R.; Bond, E.M.; Bredeweg, T.A.; Kronenberg, A.; Rundberg, R.S.; Vieira, D.J.; Wilhelmy, J.B.; Folden, C.M.; Hoffman, D.C.; Greife, U.; Schwantes, J.M.; Strottman, D.D.

    2005-05-24

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 162-element 4{pi} BaF2 array designed to make neutron capture cross-section measurements on rare or radioactive targets with masses as little as one milligram. Accurate capture cross sections are needed in many research areas, including stellar nucleosynthesis, advanced nuclear fuel cycles, waste transmutation, and other applied programs. These cross sections are difficult to calculate accurately and must be measured. The design and initial performance results of DANCE is discussed.

  13. Tagging fast neutrons from an (241)Am/(9)Be source.

    PubMed

    Scherzinger, J; Annand, J R M; Davatz, G; Fissum, K G; Gendotti, U; Hall-Wilton, R; Håkansson, E; Jebali, R; Kanaki, K; Lundin, M; Nilsson, B; Rosborge, A; Svensson, H

    2015-04-01

    Shielding, coincidence, and time-of-flight measurement techniques are employed to tag fast neutrons emitted from an (241)Am/(9)Be source resulting in a continuous polychromatic energy-tagged beam of neutrons with energies up to 7MeV. The measured energy structure of the beam agrees qualitatively with both previous measurements and theoretical calculations. PMID:25644080

  14. Tagging fast neutrons from an (241)Am/(9)Be source.

    PubMed

    Scherzinger, J; Annand, J R M; Davatz, G; Fissum, K G; Gendotti, U; Hall-Wilton, R; Håkansson, E; Jebali, R; Kanaki, K; Lundin, M; Nilsson, B; Rosborge, A; Svensson, H

    2015-04-01

    Shielding, coincidence, and time-of-flight measurement techniques are employed to tag fast neutrons emitted from an (241)Am/(9)Be source resulting in a continuous polychromatic energy-tagged beam of neutrons with energies up to 7MeV. The measured energy structure of the beam agrees qualitatively with both previous measurements and theoretical calculations.

  15. From the similarities between neutrons and radon to advanced radon-detection and improved cold fusion neutron-measurements

    NASA Astrophysics Data System (ADS)

    Tommasino, L.; Espinosa, G.

    2014-07-01

    Neutrons and radon are both ubiquitous in the earth's crust. The neutrons of terrestrial origin are strongly related to radon since they originate mainly from the interactions between the alpha particles from the decays of radioactive-gas (namely Radon and Thoron) and the light nuclei. Since the early studies in the field of neutrons, the radon gas was used to produce neutrons by (α, n) reactions in beryllium. Another important similarity between radon and neutrons is that they can be detected only through the radiations produced respectively by decays or by nuclear reactions. These charged particles from the two distinct nuclear processes are often the same (namely alpha-particles). A typical neutron detector is based on a radiator facing a alpha-particle detector, such as in the case of a neutron film badge. Based on the similarity between neutrons and radon, a film badge for radon has been recently proposed. The radon film badge, in addition to be similar, may be even identical to the neutron film badge. For these reasons, neutron measurements can be easily affected by the presence of unpredictable large radon concentration. In several cold fusion experiments, the CR-39 plastic films (typically used in radon and neutron film-badges), have been the detectors of choice for measuring neutrons. In this paper, attempts will be made to prove that most of these neutron-measurements might have been affected by the presence of large radon concentrations.

  16. Studies of D-Li neutron source: An overview

    NASA Astrophysics Data System (ADS)

    Gomes, I.; Smith, D. L.

    1994-06-01

    The construction of a neutron source facility able to reproduce the radiation environment predicted for a fusion reactor can be considered a very important milestone for the fusion program. Such a neutron source should allow materials testing over a wide range of neutron flux and neutron fluence. To date, none of the existing facilities reproduce the neutron flux with the energy spectrum of a fusion reactor. As a result, the major part of the required material database is obtained by extrapolations which may not be as reliable as needed to predict the real performance of those materials under fusion reactor conditions. As an example, the effect of the gas production, transmutation, atomic displacement, and other nuclear responses on the ductility and swelling and perhaps other properties as well must be analyzed in samples which have undergone reactor conditions environment. This study is focused on the neutronics analysis of a D-Li neutron source. Neutron induced nuclear responses and neutron transport are calculated with the aim at defining the expected performance of a D-Li neutron source. The first section describes the differences in the magnitude of the neutron flux when material is present or not inside the test cell. The second section deals with nuclear responses such as DPA, helium production, and nuclear heating. In the third section, calculations of the available volume above a threshold DPA value are presented. Section four presents results for the gamma-ray flux distribution. A brief discussion about tritium generation in the lithium jet is given in section flive, and the conclusions are summarized in section six.

  17. Validation of multigroup neutron cross sections and calculational methods for the advanced neutron source against the FOEHN critical experiments measurements

    SciTech Connect

    Smith, L.A.; Gallmeier, F.X.; Gehin, J.C.

    1995-05-01

    The FOEHN critical experiment was analyzed to validate the use of multigroup cross sections and Oak Ridge National Laboratory neutronics computer codes in the design of the Advanced Neutron Source. The ANSL-V 99-group master cross section library was used for all the calculations. Three different critical configurations were evaluated using the multigroup KENO Monte Carlo transport code, the multigroup DORT discrete ordinates transport code, and the multigroup diffusion theory code VENTURE. The simple configuration consists of only the fuel and control elements with the heavy water reflector. The intermediate configuration includes boron endplates at the upper and lower edges of the fuel element. The complex configuration includes both the boron endplates and components in the reflector. Cross sections were processed using modules from the AMPX system. Both 99-group and 20-group cross sections were created and used in two-dimensional models of the FOEHN experiment. KENO calculations were performed using both 99-group and 20-group cross sections. The DORT and VENTURE calculations were performed using 20-group cross sections. Because the simple and intermediate configurations are azimuthally symmetric, these configurations can be explicitly modeled in R-Z geometry. Since the reflector components cannot be modeled explicitly using the current versions of these codes, three reflector component homogenization schemes were developed and evaluated for the complex configuration. Power density distributions were calculated with KENO using 99-group cross sections and with DORT and VENTURE using 20-group cross sections. The average differences between the measured values and the values calculated with the different computer codes range from 2.45 to 5.74%. The maximum differences between the measured and calculated thermal flux values for the simple and intermediate configurations are {approx} 13%, while the average differences are < 8%.

  18. Design of Real-time Neutron Radiography at China Advanced Research Reactor

    NASA Astrophysics Data System (ADS)

    He, Linfeng; Han, Songbai; Wang, Hongli; Hao, Lijie; Wu, Meimei; Wei, Guohai; Wang, Yu; Liu, Yuntao; Sun, Kai; Chen, Dongfeng

    A real-time detector system for neutron radiography based on CMOS camera has been designed for the thermal neutron imaging facility under construction at China Advanced Research Reactor (CARR). This system is equipped with a new scientific CMOS camera with 5.5 million pixels and speed up to 100 fps at full frame. The readout noise is below 2.4 e/pixel. It is capable of providing images with much higher resolution and sensitivity at high frame rate. With optimized optical design and custom-built lens, the capture of quantitative information may be greatly enhanced. The maximum photon received by detector is calculated to be 2.1 × 103/pixel, while the camera resolution is 0.2 mm at 30 fps according to the expected flux (5 × 107 n/cm2/s) at the sample position.

  19. TIME-RESOLVED ANALYSES OF MICROSTRUCTURE IN ADVANCED MATERIALS UNDER MAGNETIC FIELDS AT ELEVATED TEMPERATURES USING NEUTRONS

    SciTech Connect

    Ludtka, Gerard Michael; Klose, Frank Richard; Kisner, Roger A; Fernandez-Baca, Jaime A; Ludtka, Gail Mackiewicz-; Wilgen, John B; Jaramillo, Roger A; Santodonato, Louis J; Wang, Xun-Li; Hubbard, Camden R; Tang, Fei

    2007-01-01

    Fundamental science breakthroughs are being facilitated by high magnetic field studies in a broad spectrum of research disciplines. Furthermore, processing of materials under high magnetic fields is a novel technique with very high science and technological potential. However, currently the capability does not exist to do in-situ time-resolved quantitative analyses at high magnetic field strengths and elevated temperatures. Therefore, most measurements are performed ex situ and do not capture the microstructural evolution of the samples during high field exposure. To address this deficiency, we are developing high field magnet processing and analyses systems at the High Flux Isotope Reactor and the Spallation Neutron Source at the Oak Ridge National Laboratory which will link the analytical capabilities inherent in neutron science to the needs of magnetic processing research. Our goal is to apply advanced neutron scattering techniques to explore time-resolved characterizations of magnetically driven alloy phase transformations under transient conditions. This paper will provide an overview of the current status of this research endeavor with preliminary results obtained on ferrous alloys.

  20. Secondary Neutron Production from Space Radiation Interactions: Advances in Model and Experimental Data Base Development

    NASA Technical Reports Server (NTRS)

    Heilbronn, Lawrence H.; Townsend, Lawrence W.; Braley, G. Scott; Iwata, Yoshiyuki; Iwase, Hiroshi; Nakamura, Takashi; Ronningen, Reginald M.; Cucinotta, Francis A.

    2003-01-01

    For humans engaged in long-duration missions in deep space or near-Earth orbit, the risk from exposure to galactic and solar cosmic rays is an important factor in the design of spacecraft, spacesuits, and planetary bases. As cosmic rays are transported through shielding materials and human tissue components, a secondary radiation field is produced. Neutrons are an important component of that secondary field, especially in thickly-shielded environments. Calculations predict that 50% of the dose-equivalent in a lunar or Martian base comes from neutrons, and a recent workshop held at the Johnson Space Center concluded that as much as 30% of the dose in the International Space Station may come from secondary neutrons. Accelerator facilities provide a means for measuring the effectiveness of various materials in their ability to limit neutron production, using beams and energies that are present in cosmic radiation. The nearly limitless range of beams, energies, and target materials that are present in space, however, means that accelerator-based experiments will not provide a complete database of cross sections and thick-target yields that are necessary to plan and design long-duration missions. As such, accurate nuclear models of neutron production are needed, as well as data sets that can be used to compare with, and verify, the predictions from such models. Improvements in a model of secondary neutron production from heavy-ion interactions are presented here, along with the results from recent accelerator-based measurements of neutron-production cross sections. An analytical knockout-ablation model capable of predicting neutron production from high-energy hadron-hadron interactions (both nucleon-nucleus and nucleus-nucleus collisions) has been previously developed. In the knockout stage, the collision between two nuclei result in the emission of one or more nucleons from the projectile and/or target. The resulting projectile and target remnants, referred to as

  1. An instability in neutron stars at birth

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Fryxell, Bruce A.

    1992-01-01

    Calculations with a two-dimensional hydrodynamic simulation show that a generic Raleigh-Taylor-like instability occurs in the mantles of nascent neutron stars, that it is possibly violent, and that the standard spherically symmetric models of neutron star birth and supernova explosion may be inadequate. Whether this 'convective' instability is pivotal to the supernova mechanism, pulsar nagnetic fields, or a host of other important issues that attend stellar collapse remains to be seen, but its existence promises to modify all questions concerning this most energetic of astronomical phenomena.

  2. Circular arc fuel plate stability experiments and analyses for the advanced neutron source

    SciTech Connect

    Swinson, W.F.; Battiste, R.L.; Yahr, G.T.

    1995-08-01

    The thin fuel plates planned for the Advanced Neutron Source are to be cooled by forcing heavy water at high velocity, 25 m/s, through thin cooling channels on each side of each plate. Because the potential for structural failure of the plates is a design concern, considerable effort has been expended in assessing this potential. As part of this effort, experimental flow tests and analyses to evaluate the structural response of circular arc plates have been conducted, and the results are given in this report.

  3. Delayed neutron detection with an integrated differential die-away and delayed neutron instrument

    SciTech Connect

    Blanc, Pauline; Tobin, Stephen J; Lee, Taehoon; Hu, Jianwei S; Hendricks, John; Croft, Stephen

    2010-01-01

    The Next Generation Safeguards Initiative (NGSI) of the U.S. Department of Energy (DOE) has funded a multilab/university collaboration to quantify the plutonium (Pu) mass and detect the diversion of pins from spent nuclear fuel. The first two years of this NGSI effort was focused on quantifying the capability of a range of nondestructive assay (NDA) techniques with Monte Carlo (MCNPX) modeling and the second current phase involves measuring Spent Fuel. One of the techniques of interest in this paper involves measuring delayed neutrons. A delayed neutron instrument using 36 fission chambers and a 14 MeV neutron generator so called DT generator (Deuterium + Tritium) surrounding the fuel was previously studied as part of the NGSI effort. This paper will quantify the capability of a standalone delayed neutron instrument using 4 {sup 3}He gas filled tubes and a DT generator with significant spectrum tailoring, located far from the fuel. So that future research can assess how well a delayed neutron instrument will function as part of an integrated NDA system. A new design is going to be used to respond to the need of the techniques. This design has been modeled for a water media and is currently being optimized for borated water and air media as part of ongoing research. This new design was selected in order to minimize the fission of {sup 238}U, to use a more realistic neutron generator design in the model, to reduce cost and facilitate the integration of a delayed neutron (DN) with a differential die-away (DDA) instrument. Since this paper will focus on delayed neutron detection, the goal is to quantify the signal from {sup 235}U, {sup 239}Pu and {sup 241}Pu, which are the isotopes present in Spent Fuel that respond significantly to a neutron interrogation. This report will quantify the capability of this new delayed neutron design to measure the combined mass of {sup 235}U, {sup 239}Pu and {sup 241}Pu for 16 of the 64 assemblies of the NGSI Spent Fuel library in one

  4. Advanced Neutron Detection Methods: new Tools for Countering Nuclear Terrorism (412th Brookhaven Lecture)

    SciTech Connect

    Vanier, Peter

    2006-02-15

    Acts of terrorism have become almost daily occurrences in the international news. Yet one of the most feared types of terrorism — nuclear terrorism — has not yet happened. One important way of preventing nuclear terrorism is to safeguard nuclear materials, and many people worldwide work continuously to achieve that goal. A second, vital defense is being developed: greatly improved methods of detecting material that a nuclear terrorist would need so that timely discovery of the material could become more probable. Special nuclear materials can emit neutrons, either spontaneously or when excited by a source of high-energy gamma rays, such as an electron accelerator. Traditional neutron detectors can sense these neutrons, but not the direction from which the neutrons come, or their energy. The odds against finding smuggled nuclear materials using conventional detectors are great. However, innovative designs of detectors are producing images that show the locations and even the shapes of man-made neutron sources, which stand out against the uniform background produced by cosmic rays. With the new detectors, finding needles in haystacks — or smuggled nuclear materials in a huge container among thousands of others in a busy port — suddenly becomes possible.

  5. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reactions by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  6. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reaction by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  7. Innovative concept for an advanced hadron facility based on a 2 GeV H/sup -/ linac

    SciTech Connect

    Thiessen, H.A.

    1987-01-01

    This report presents parameters for an innovative new concept for the design of an advanced hadron facility. We propose combining a cold neutron source with a kaon factory. We also discuss the possibility of a shared target for neutron and neutrino experiments. An initial cost estimate is presented.

  8. Elucidation of Advanced Function by Combined High-Resolution Neutron and X-ray Analysis

    NASA Astrophysics Data System (ADS)

    Tamada, Taro; Kuroki, Ryota; Kinoshita, Takayoshi; Tada, Toshiji

    To help resolve long-standing questions regarding the catalytic activity of the serine proteases the structure of porcine pancreatic elastase has been analyzed by high-resolution neutron (1.65 Å resolution) and X-ray (0.94 Å resolution) crystallography. In order to mimic the tetrahedral transition intermediate, a peptidic inhibitor was used. The neutron and X-ray data show that the hydrogen bond between His57 and Asp102 is not consistent with a low-barrier hydrogen which is predicted to have the hydrogen midway between the donor and acceptor atom. The neutron analysis also shows that the oxygen of the oxopropyl group of the inhibitor is present as an oxygen anion rather than a hydroxyl group, supporting the role of the “oxyanion hole” in stabilizing the tetrahedral intermediate in catalysis.

  9. Development of advanced tritium breeders and neutron multipliers for DEMO solid breeder blankets

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Hoshino, T.; Kawamura, H.; Mishima, Y.; Yoshida, N.; Terai, T.; Tanaka, S.; Munakata, K.; Kato, S.; Uchida, M.; Nakamichi, M.; Yamada, H.; Yamaki, D.; Hayashi, K.

    2007-09-01

    In efforts to develop advanced tritium breeders, the effects of additives to lithium titanate (Li2TiO3) have been investigated, and good prospects have been obtained by using oxide additives such as TiO2, CaO and Li2O. As for the neutron multiplier, the development of a real-size electrode fabrication technique and the characterization of beryllium-based intermetallic compounds such as Be-Ti and Be-V have been performed. Properties of Be-Ti alloys have been found to be better than those of beryllium metal. In particular, steam interaction of a Be-Ti alloy was about 1/1000 as small as that of beryllium metal. These activities have led to bright prospects for the realization of the water-cooled DEMO breeder blanket by application of these advanced materials.

  10. Advances in explosives analysis—part II: photon and neutron methods

    DOE PAGESBeta

    Brown, Kathryn E.; Greenfield, Margo T.; McGrane, Shawn D.; Moore, David S.

    2015-10-07

    The number and capability of explosives detection and analysis methods have increased dramatically since publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis [Moore DS, Goodpaster JV, Anal Bioanal Chem 395:245–246, 2009]. Here we review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. Our review consists of two parts. Part I discussed methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers,more » electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. In Part II, we review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.« less

  11. Advances in explosives analysis—part II: photon and neutron methods

    SciTech Connect

    Brown, Kathryn E.; Greenfield, Margo T.; McGrane, Shawn D.; Moore, David S.

    2015-10-07

    The number and capability of explosives detection and analysis methods have increased dramatically since publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis [Moore DS, Goodpaster JV, Anal Bioanal Chem 395:245–246, 2009]. Here we review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. Our review consists of two parts. Part I discussed methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers, electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. In Part II, we review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.

  12. RELAP5 analyses of two hypothetical flow reversal events for the advanced neutron source reactor

    SciTech Connect

    Chen, N.C.J.; Wendel, M.W.; Yoder, G.L. Jr.

    1995-09-01

    This paper presents RELAP5 results of two hypothetical, low flow transients analyzed as part of the Advanced Neutron Source Reactor safety program. The reactor design features four independent coolant loops (three active and one in standby), each containing a main curculation pump (with battery powered pony motor), heat exchanger, an accumulator, and a check valve. The first transient assumes one of these pumps fails, and additionally, that the check valve in that loop remains stuck in the open position. This accident is considered extremely unlikely. Flow reverses in this loop, reducing the core flow because much of the coolant is diverted from the intact loops back through the failed loop. The second transient examines a 102-mm-diam instantaneous pipe break near the core inlet (the worst break location). A break is assumed to occur 90 s after a total loss-of-offsite power. Core flow reversal occurs because accumulator injection overpowers the diminishing pump flow. Safety margins are evaluated against four thermal limits: T{sub wall}=T{sub sat}, incipient boiling, onset of significant void, and critical heat flux. For the first transient, the results show that these limits are not exceeded (at a 95% non-exceedance probability level) if the pony motor battery lasts 30 minutes (the present design value). For the second transient, the results show that the closest approach of the fuel surface temperature to the local saturation temperature during core flow reversal is about 39{degrees}C. Therefore the fuel remains cool during this transient. Although this work is done specifically for the ANSR geometry and operating conditions, the general conclusions may be applicable to other highly subcooled reactor systems.

  13. SNM Detection with an Optimized Water Cherenkov Neutron Detector

    DOE PAGESBeta

    Dazeley, S.; Sweany, M.; Bernstein, A.

    2012-07-23

    Special Nuclear Material (SNM) can either spontaneously fission or be induced to do so: either case results in neutron emission. For this reason, neutron detection performs a crucial role in the functionality of Radiation Portal Monitoring (RPM) devices. Since neutrons are highly penetrating and difficult to shield, they could potentially be detected escaping even a well-shielded cargo container. If the shielding were sophisticated, detecting escaping neutrons would require a highly efficient detector with close to full solid angle coverage. In 2008, we reported the successful detection of neutrons with a 250 liter (l) gadolinium doped water Cherenkov prototype—a technology thatmore » could potentially be employed cost effectively with full solid angle coverage. More recently we have built and tested both 1-kl and 3.5-kl versions, demonstrating that very large, cost effective, non-flammable and environmentally benign neutron detectors can be operated efficiently without being overwhelmed by background. In our paper, we present a new design for a modular system of water-based neutron detectors that could be deployed as a real RPM. The modules contain a number of optimizations that have not previously been combined within a single system. We present simulations of the new system, based on the performance of our previous detectors. These simulations indicate that an optimized system such as is presented here could achieve SNM sensitivity competitive with a large 3He-based system. Moreover, the realization of large, cost effective neutron detectors could, for the first time, enable the detection of multiple neutrons per fission from within a large object such as a cargo container. Such a signal would provide a robust indication of the presence of fissioning material, reducing the frequency of false alarms while increasing sensitivity.« less

  14. SNM Detection with an Optimized Water Cherenkov Neutron Detector

    SciTech Connect

    Dazeley, S.; Sweany, M.; Bernstein, A.

    2012-07-23

    Special Nuclear Material (SNM) can either spontaneously fission or be induced to do so: either case results in neutron emission. For this reason, neutron detection performs a crucial role in the functionality of Radiation Portal Monitoring (RPM) devices. Since neutrons are highly penetrating and difficult to shield, they could potentially be detected escaping even a well-shielded cargo container. If the shielding were sophisticated, detecting escaping neutrons would require a highly efficient detector with close to full solid angle coverage. In 2008, we reported the successful detection of neutrons with a 250 liter (l) gadolinium doped water Cherenkov prototype—a technology that could potentially be employed cost effectively with full solid angle coverage. More recently we have built and tested both 1-kl and 3.5-kl versions, demonstrating that very large, cost effective, non-flammable and environmentally benign neutron detectors can be operated efficiently without being overwhelmed by background. In our paper, we present a new design for a modular system of water-based neutron detectors that could be deployed as a real RPM. The modules contain a number of optimizations that have not previously been combined within a single system. We present simulations of the new system, based on the performance of our previous detectors. These simulations indicate that an optimized system such as is presented here could achieve SNM sensitivity competitive with a large 3He-based system. Moreover, the realization of large, cost effective neutron detectors could, for the first time, enable the detection of multiple neutrons per fission from within a large object such as a cargo container. Such a signal would provide a robust indication of the presence of fissioning material, reducing the frequency of false alarms while increasing sensitivity.

  15. An application of the neutron television fluoroscopic system to neutron computed tomography

    NASA Astrophysics Data System (ADS)

    Fujine, Shigenori; Yoneda, Kenji; Kanda, Keiji

    1984-10-01

    Recently the real-time neutron radiography system of the Kyoto University Reactor (KUR) has been developed and practically applied to penetrating the side plates of the MTR type reactor fuels and investigation of moving objects. In this paper an application of the KUR neutron TV system to neutron computed tomography (NCT) is described. By using the NTV system, projection data can be acquired in a single measurement and simultaneously the projection image can be observed on a CRT monitor. The Fourier-convolution technique is used to produce the reconstructed image and its image has a good enough quality for revealing water in a small hole of 1.5 mm in diameter.

  16. An ultracold neutron storage bottle for UCN density measurements

    NASA Astrophysics Data System (ADS)

    Bison, G.; Burri, F.; Daum, M.; Kirch, K.; Krempel, J.; Lauss, B.; Meier, M.; Ries, D.; Schmidt-Wellenburg, P.; Zsigmond, G.

    2016-09-01

    We have developed a storage bottle for ultracold neutrons (UCNs) in order to measure the UCN density at the beamports of the Paul Scherrer Institute's (PSI) UCN source. This paper describes the design, construction and commissioning of the robust and mobile storage bottle with a volume comparable to typical storage experiments (32 L) e.g. searching for an electric dipole moment of the neutron.

  17. A Neutron Burst Associated with an Extensive Air Shower?

    NASA Astrophysics Data System (ADS)

    Alves, Mauro; Martin, Inacio; Shkevov, Rumen; Gusev, Anatoly; De Abreu, Alessandro

    2016-07-01

    A portable and compact system based on a He-3 tube (LND, USA; model 25311) with an area of approximately 250 cm² and is used to record neutron count rates at ground level in the energy range of 0.025 eV to 10 MeV, in São José dos Campos, SP, Brazil (23° 12' 45" S, 45° 52' 00" W; altitude, 660m). The detector, power supply, digitizer and other hardware are housed in an air-conditioned room. The detector power supply and digitizer are not connected to the main electricity network; a high-capacity 12-V battery is used to power the detector and digitizer. Neutron counts are accumulated at 1-minute intervals continuously. The data are stored in a PC for further analysis. In February 8, 2015, at 12 h 22 min (local time) during a period of fair weather with minimal cloud cover (< 1 okta) the neutron detector recorded a sharp (count rate = 27 neutrons/min) and brief (< 1 min) increase in the count rate. In the days before and after this event, the neutron count rate has oscillated between 0 and 3 neutrons/min. Since the occurrence of this event is not related with spurious signals, malfunctioning equipment, oscillations in the mains voltage, etc. we are led to believe that the sharp increase was caused by a physical source such as a an extensive air shower that occurred over the detector.

  18. PREFACE: Exploring surfaces and buried interfaces of functional materials by advanced x-ray and neutron techniques Exploring surfaces and buried interfaces of functional materials by advanced x-ray and neutron techniques

    NASA Astrophysics Data System (ADS)

    Sakurai, Kenji

    2010-12-01

    updates on recent progress and global trends in the field. We planned to cover quite a wide area of surface and buried interface science with x-rays and neutrons. Following a great deal of discussion during the editing process, we have decided to change direction. As we intend to publish similar special issues on a frequent basis, we will not insist on editing this issue as systematic and complete collections of research. Many authors decided to write an ordinary research paper rather than an article including systematic accounts. Due to this change in policy, some authors declined to contribute, and the number of papers is now just 12. However, readers will find that the special issue gives an interesting collection of new original research in surface and buried interface studies with x-rays and neutrons. The 12 papers cover the following research topics: (1) polymer analysis by diffuse scattering; (2) discussion of the electrochemical solid--liquid interface by synchrotron x-ray diffraction; (3) analysis of capped nanodots by grazing incidence small-angle x-ray scattering (GISAXS); (4) discussion of the strain distribution in silicon by high-resolution x-ray diffraction; (5) study of mesoporous structures by a combination of x-ray reflectivity and GISAXS; (6) discussion of energy-dispersive x-ray reflectometry and its applications; (7) neutron reflectivity studies on hydrogen terminated silicon interface; (8) the fabrication and performance of a special mirror for water windows; (9) depth selective analysis by total-reflection x-ray diffraction; (10) nanoparticle thin films prepared by a gas deposition technique; (11) discussion of crystal truncation rod (CTR) scattering of semiconductor nanostructures; (12) magnetic structure analysis of thin films by polarized neutron reflectivity. While not discussed in the present special issue, x-ray and neutron techniques have made great progress. The most important steps forward have been in 2D/3D real-space imaging, and realtime

  19. Neutron response characterization for an EJ299-33 plastic scintillation detector

    SciTech Connect

    Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.; Flaska, Marek; Becchetti, F. D.; Pozzi, Sara A.

    2014-05-10

    Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for both detectors. A Continuous spectrum neutron source, obtained via the bombardment of Al-27 with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals. (C) 2014 Elsevier B.V. All rights reserved. Keywords

  20. Neutron response characterization for an EJ299-33 plastic scintillation detector

    DOE PAGESBeta

    Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.; Flaska, Marek; Becchetti, F. D.; Pozzi, Sara A.

    2014-05-10

    Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for both detectors. A Continuousmore » spectrum neutron source, obtained via the bombardment of Al-27 with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals. (C) 2014 Elsevier B.V. All rights reserved. Keywords« less

  1. Neutron response characterization for an EJ299-33 plastic scintillation detector

    NASA Astrophysics Data System (ADS)

    Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.; Flaska, Marek; Becchetti, F. D.; Pozzi, Sara A.

    2014-09-01

    Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland-security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much-expanded range of deployment relative to liquids and crystals. Here, we present a full characterization of pulse-height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light-output relations, energy resolutions, and response matrices are presented for both detectors. A continuous-spectrum neutron source, obtained via the bombardment of 27Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light-output relation on the ability to detect low-energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Nevertheless the EJ299 is likely to bring a modest PSD capability into a array of field applications that are not accessible to liquids or crystals.

  2. Basic parameter estimation of binary neutron star systems by the advanced LIGO/Vigro network

    SciTech Connect

    Rodriguez, Carl L.; Farr, Benjamin; Raymond, Vivien; Farr, Will M.; Littenberg, Tyson B.; Fazi, Diego; Kalogera, Vicky

    2014-04-01

    Within the next five years, it is expected that the Advanced LIGO/Virgo network will have reached a sensitivity sufficient to enable the routine detection of gravitational waves. Beyond the initial detection, the scientific promise of these instruments relies on the effectiveness of our physical parameter estimation capabilities. A major part of this effort has been toward the detection and characterization of gravitational waves from compact binary coalescence, e.g., the coalescence of binary neutron stars. While several previous studies have investigated the accuracy of parameter estimation with advanced detectors, the majority have relied on approximation techniques such as the Fisher Matrix which are insensitive to the non-Gaussian nature of the gravitational wave posterior distribution function. Here we report average statistical uncertainties that will be achievable for strong detection candidates (S/N = 20) over a comprehensive sample of source parameters. We use the Markov Chain Monte Carlo based parameter estimation software developed by the LIGO/Virgo Collaboration with the goal of updating the previously quoted Fisher Matrix bounds. We find the recovery of the individual masses to be fractionally within 9% (15%) at the 68% (95%) credible intervals for equal-mass systems, and within 1.9% (3.7%) for unequal-mass systems. We also find that the Advanced LIGO/Virgo network will constrain the locations of binary neutron star mergers to a median uncertainty of 5.1 deg{sup 2} (13.5 deg{sup 2}) on the sky. This region is improved to 2.3 deg{sup 2} (6 deg{sup 2}) with the addition of the proposed LIGO India detector to the network. We also report the average uncertainties on the luminosity distances and orbital inclinations of strong detections that can be achieved by different network configurations.

  3. Advances in implosion physics, alternative targets design, and neutron effects on heavy ion fusion reactors

    NASA Astrophysics Data System (ADS)

    Velarde, G.; Perlado, J. M.; Alonso, E.; Alonso, M.; Domínguez, E.; Rubiano, J. G.; Gil, J. M.; Gómez del Rio, J.; Lodi, D.; Malerba, L.; Marian, J.; Martel, P.; Martínez-Val, J. M.; Mínguez, E.; Piera, M.; Ogando, F.; Reyes, S.; Salvador, M.; Sanz, J.; Sauvan, P.; Velarde, M.; Velarde, P.

    2001-05-01

    The coupling of a new radiation transport (RT) solver with an existing multimaterial fluid dynamics code (ARWEN) using Adaptive Mesh Refinement named DAFNE, has been completed. In addition, improvements were made to ARWEN in order to work properly with the RT code, and to make it user-friendlier, including new treatment of Equations of State, and graphical tools for visualization. The evaluation of the code has been performed, comparing it with other existing RT codes (including the one used in DAFNE, but in the single-grid version). These comparisons consist in problems with real input parameters (mainly opacities and geometry parameters). Important advances in Atomic Physics, Opacity calculations and NLTE atomic physics calculations, with participation in significant experiments in this area, have been obtained. Early published calculations showed that a DT x fuel with a small tritium initial content ( x<3%) could work in a catalytic regime in Inertial Fusion Targets, at very high burning temperatures (≫100 keV). Otherwise, the cross-section of DT remains much higher than that of DD and no internal breeding of tritium can take place. Improvements in the calculation model allow to properly simulate the effect of inverse Compton scattering which tends to lower Te and to enhance radiation losses, reducing the plasma temperature, Ti. The neutron activation of all natural elements in First Structural Wall (FSW) component of an Inertial Fusion Energy (IFE) reactor for waste management, and the analysis of activation of target debris in NIF-type facilities has been completed. Using an original efficient modeling for pulse activation, the FSW behavior in inertial fusion has been studied. A radiological dose library coupled to the ACAB code is being generated for assessing impact of environmental releases, and atmospheric dispersion analysis from HIF reactors indicate the uncertainty in tritium release parameters. The first recognition of recombination barriers in Si

  4. Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced fission reactions on Pu239

    NASA Astrophysics Data System (ADS)

    Talou, P.; Becker, B.; Kawano, T.; Chadwick, M. B.; Danon, Y.

    2011-06-01

    Prompt fission neutrons following the thermal and 0.5 MeV neutron-induced fission reaction of Pu239 are calculated using a Monte Carlo approach to the evaporation of the excited fission fragments. Exclusive data such as the multiplicity distribution P(ν), the average multiplicity as a function of fragment mass ν¯(A), and many others are inferred in addition to the most used average prompt fission neutron spectrum χ(Ein,Eout), as well as average neutron multiplicity ν¯. Experimental information on these more exclusive data help constrain the Monte Carlo model parameters. The calculated average total neutron multiplicity is ν¯c=2.871 in very close agreement with the evaluated value ν¯e=2.8725 present in the ENDF/B-VII.0 library. The neutron multiplicity distribution P(ν) is in very good agreement with the evaluation by Holden and Zucker. The calculated average spectrum differs in shape from the ENDF/B-VII.0 spectrum, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail of the spectrum (below about 300 keV) than the Madland-Nix calculations, casting some doubts on how much scission neutrons contribute to the shape of the low-energy tail of the spectrum. The spectrum high-energy tail is very sensitive to the total kinetic energy distribution of the fragments as well as to the total excitation energy sharing at scission. Present experimental uncertainties on measured spectra above 6 MeV are too large to distinguish between various theoretical hypotheses. Finally, comparisons of the Monte Carlo results with experimental data on ν¯(A) indicate that more neutrons are emitted from the light fragments than the heavy ones, in agreement with previous works.

  5. Comparison of the 3-D Deterministic Neutron Transport Code Attila® To Measure Data, MCNP And MCNPX For The Advanced Test Reactor

    SciTech Connect

    D. Scott Lucas; D. S. Lucas

    2005-09-01

    An LDRD (Laboratory Directed Research and Development) project is underway at the Idaho National Laboratory (INL) to apply the three-dimensional multi-group deterministic neutron transport code (Attila®) to criticality, flux and depletion calculations of the Advanced Test Reactor (ATR). This paper discusses the development of Attila models for ATR, capabilities of Attila, the generation and use of different cross-section libraries, and comparisons to ATR data, MCNP, MCNPX and future applications.

  6. Prototyping an Active Neutron Veto for SuperCDMS

    SciTech Connect

    Calkins, Robert; Loer, Ben

    2015-08-17

    Neutrons, originating cosmogenically or from radioactive decays, can produce signals in dark matter detectors that are indistinguishable from Weakly Interacting Massive Particles (WIMPs). To combat this background for the SuperCDMS SNOLAB experiment, we are investigating designs for an active neutron veto within the constrained space of the compact SuperCDMS passive shielding. The current design employs an organic liquid scintillator mixed with an agent to enhance thermal neutron captures, with the scintillation light collected using wavelength-shifting fibers and read out by silicon photo-multipliers. We will describe the proposed veto and its predicted efficiency in detail and give some recent results from our R&D and prototyping efforts.

  7. Prototyping an active neutron veto for SuperCDMS

    SciTech Connect

    Calkins, Robert; Loer, Ben

    2015-08-17

    Neutrons, originating cosmogenically or from radioactive decays, can produce signals in dark matter detectors that are indistinguishable from Weakly Interacting Massive Particles (WIMPs). To combat this background for the SuperCDMS SNOLAB experiment, we are investigating designs for an active neutron veto within the constrained space of the compact SuperCDMS passive shielding. The current design employs an organic liquid scintillator mixed with an agent to enhance thermal neutron captures, with the scintillation light collected using wavelength-shifting fibers and read out by silicon photo-multipliers. We will describe the proposed veto and its predicted efficiency in detail and give some recent results from our R&D and prototyping efforts.

  8. Prototyping an active neutron veto for SuperCDMS

    NASA Astrophysics Data System (ADS)

    Calkins, Robert; Loer, Ben

    2015-08-01

    Neutrons, originating cosmogenically or from radioactive decays, can produce signals in dark matter detectors that are indistinguishable from Weakly Interacting Massive Particles (WIMPs). To combat this background for the SuperCDMS SNOLAB experiment, we are investigating designs for an active neutron veto within the constrained space of the compact SuperCDMS passive shielding. The current design employs an organic liquid scintillator mixed with an agent to enhance thermal neutron captures, with the scintillation light collected using wavelength-shifting fibers and read out by silicon photo-multipliers. We will describe the proposed veto and its predicted efficiency in detail and give some recent results from our R&D and prototyping efforts.

  9. Advancement Planning: An Objectives View.

    ERIC Educational Resources Information Center

    Druck, Kalman B.

    1986-01-01

    Planning must revolve around objectives related to students, faculty, money, and political support. When it is understood that all of the institution's advancement activity should help produce these four things, planning is easy. (MLW)

  10. A High Temperature-Tolerant and Radiation-Resistant In-Core Neutron Sensor for Advanced Reactors. Final report

    SciTech Connect

    Cao, Lei; Miller, Don

    2015-01-23

    The objectives of this project are to develop a small and reliable gallium nitride (GaN) neutron sensor that is capable of withstanding high neutron fluence and high temperature, isolating gamma background, and operating in a wide dynamic range. The first objective will be the understanding of the fundamental materials properties and electronic response of a GaN semiconductor materials and device in an environment of high temperature and intense neutron field. To achieve such goal, an in-situ study of electronic properties of GaN device such as I-V, leakage current, and charge collection efficiency (CCE) in high temperature using an external neutron beam will be designed and implemented. We will also perform in-core irradiation of GaN up to the highest yet fast neutron fluence and an off-line performance evaluation.

  11. An ultra-cold neutron source at the MLNSC

    SciTech Connect

    Bowles, T.J.; Brun, T.; Hill, R.; Morris, C.; Seestrom, S.J.; Crow, L.; Serebrov, A.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have carried out the research and development of an Ultra-Cold Neutron (UCN) source at the Manuel Lujan Neutron Scattering Center (MLNSC). A first generation source was constructed to test the feasibility of a rotor source. The source performed well with an UCN production rate reasonably consistent with that expected. This source can now provide the basis for further development work directed at using UCN in fundamental physics research as well as possible applications in materials science.

  12. Development and testing of an active area neutron dosemeter.

    PubMed

    Brushwood, J M; Gow, J P D; Beeley, P A; Spyrou, N M

    2004-01-01

    This paper describes the design, development and testing of an active area neutron dosemeter (AAND). The classic moderator and central detector is retained but in AAND this arrangement is augmented by small thermal neutron detectors positioned within the moderating body. The outputs from these detectors are combined using an appropriately weighted linear superposition to fit both the ambient dose equivalent and the radiation weighting factor. Experimental verifications of both the modelled detector energy reponses and the overall AAND response are given. In the relatively soft D2O moderated 252Cf spectra, the AAND determined both the H*(10) and mean radiation weighting factor to better than +10%.

  13. Development and applications of methodologies for the neutronic design of the Pebble Bed Advanced High Temperature Reactor (PB-AHTR)

    NASA Astrophysics Data System (ADS)

    Fratoni, Massimiliano

    This study investigated the neutronic characteristics of the Pebble Bed Advanced High Temperature Reactor (PB-AHTR), a novel nuclear reactor concept that combines liquid salt (7LiF-BeF2---flibe) cooling and TRISO coated-particle fuel technology. The use of flibe enables operation at high power density and atmospheric pressure and improves passive decay-heat removal capabilities, but flibe, unlike conventional helium coolant, is not transparent to neutrons. The flibe occupies 40% of the PB-AHTR core volume and absorbs ˜8% of the neutrons, but also acts as an effective neutron moderator. Two novel methodologies were developed for calculating the time dependent and equilibrium core composition: (1) a simplified single pebble model that is relatively fast; (2) a full 3D core model that is accurate and flexible but computationally intensive. A parametric analysis was performed spanning a wide range of fuel kernel diameters and graphite-to-heavy metal atom ratios to determine the attainable burnup and reactivity coefficients. Using 10% enriched uranium ˜130 GWd/tHM burnup was found to be attainable, when the graphite-to-heavy metal atom ratio (C/HM) is in the range of 300 to 400. At this or smaller C/HM ratio all reactivity coefficients examined---coolant temperature, coolant small and full void, fuel temperature, and moderator temperature, were found to be negative. The PB-AHTR performance was compared to that of alternative options for HTRs, including the helium-cooled pebble-bed reactor and prismatic fuel reactors, both gas-cooled and flibe-cooled. The attainable burnup of all designs was found to be similar. The PB-AHTR generates at least 30% more energy per pebble than the He-cooled pebble-bed reactor. Compared to LWRs the PB-AHTR requires 30% less natural uranium and 20% less separative work per unit of electricity generated. For deep burn TRU fuel made from recycled LWR spent fuel, it was found that in a single pass through the core ˜66% of the TRU can be

  14. 6.3 MeV fast neutrons in the treatment of patients with locally advanced and locally recurrent breast cancer

    NASA Astrophysics Data System (ADS)

    Velikaya, V. V.; Musabaeva, L. I.; Lisin, V. A.; Startseva, Zh. A.

    2016-08-01

    The study included 135 breast cancer patients (70 patients with locally recurrent breast cancer and 65 patients with locally advanced breast cancer with unfavorable prognostic factors) who received the neutron therapy alone or in combination with the photon therapy. The neutron therapy was shown to be effective in multimodality treatment of patients with locally advanced and locally recurrent breast cancer. The 8-year survival rate in patients without repeated breast cancer recurrence was 87.6 ± 8.7% after the neutron and neutron-photon therapy and 54.3 ± 9.2% after the electron beam therapy.

  15. A Complex-Geometry Validation Experiment for Advanced Neutron Transport Codes

    SciTech Connect

    David W. Nigg; Anthony W. LaPorta; Joseph W. Nielsen; James Parry; Mark D. DeHart; Samuel E. Bays; William F. Skerjanc

    2013-11-01

    The Idaho National Laboratory (INL) has initiated a focused effort to upgrade legacy computational reactor physics software tools and protocols used for support of core fuel management and experiment management in the Advanced Test Reactor (ATR) and its companion critical facility (ATRC) at the INL.. This will be accomplished through the introduction of modern high-fidelity computational software and protocols, with appropriate new Verification and Validation (V&V) protocols, over the next 12-18 months. Stochastic and deterministic transport theory based reactor physics codes and nuclear data packages that support this effort include MCNP5[1], SCALE/KENO6[2], HELIOS[3], SCALE/NEWT[2], and ATTILA[4]. Furthermore, a capability for sensitivity analysis and uncertainty quantification based on the TSUNAMI[5] system has also been implemented. Finally, we are also evaluating the Serpent[6] and MC21[7] codes, as additional verification tools in the near term as well as for possible applications to full three-dimensional Monte Carlo based fuel management modeling in the longer term. On the experimental side, several new benchmark-quality code validation measurements based on neutron activation spectrometry have been conducted using the ATRC. Results for the first four experiments, focused on neutron spectrum measurements within the Northwest Large In-Pile Tube (NW LIPT) and in the core fuel elements surrounding the NW LIPT and the diametrically opposite Southeast IPT have been reported [8,9]. A fifth, very recent, experiment focused on detailed measurements of the element-to-element core power distribution is summarized here and examples of the use of the measured data for validation of corresponding MCNP5, HELIOS, NEWT, and Serpent computational models using modern least-square adjustment methods are provided.

  16. Development of advanced materials for spallation neutron sources and radiation damage simulation based on multi-scale models

    NASA Astrophysics Data System (ADS)

    Kawai, Masayoshi; Kurishita, Hiroaki; Kokawa, Hiroyuki; Watanabe, Seiichi; Sakaguchi, Norihito; Kikuchi, Kenji; Saito, Shigeru; Yoshiie, Toshimasa; Iwase, Hiroshi; Ito, Takahiro; Hashimoto, Satoshi; Kaneko, Yoshihisa; Futakawa, Masatoshi; Ishino, Shiori; JSPS Grant Team

    2012-12-01

    This report describes the status review of the JSPS Grant Team to develop advanced materials for the spallation neutron sources and modeling of radiation damage. One of the advanced materials is a toughness enhanced, fine-grained tungsten material (W-TiC) having four-times larger fracture toughness than ordinary tungsten and appreciable RT ductility in the recrystallized state. The other is an intergranular crack (IGC)-resistant austenitic stainless steel which was processed by the grain-boundary engineering (GBE). The experimental results are devoted to corrosion in a lead-bismuth eutectic, arrest of corrosion of weld-decay, radiation damage and creep rupture as well as new technique of GBE using a laser and annealing procedure. New technique seems to be applicable to large or complicated-shaped components. A series of the multi-scale models is built up from nuclear reaction between incident particles and medium nuclei to material property change due to radiation damage. Sample calculation is made on 3 mm-thick nickel bombarded by 3 GeV protons.

  17. Advanced liquid and solid extraction procedures for ultratrace determination of rhenium by radiochemical neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Mizera, J.; Kučera, J.; Řanda, Z.; Lučaníková, M.

    2006-01-01

    Radiochemical neutron activation analysis (RNAA) procedures for determination of Re at the ultratrace level based on use of liquid-liquid extraction (LLE) and extraction chromatography (EXC) have been developed. Two different LLE procedures were used depending on the way of sample decomposition using either 2-butanone or tetraphenylarsonium chloride in CHCl3. EXC employed new solid extractant materials prepared by incorporation of the liquid trioctyl-methyl-ammonium chloride into an inert polyacrylonitrile matrix. The RNAA procedures presented have been compared and applied for Re determination in several biological and environmental reference materials.

  18. 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.

  19. A debris disk around an isolated young neutron star.

    PubMed

    Wang, Zhongxiang; Chakrabarty, Deepto; Kaplan, David L

    2006-04-01

    Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star or it may possess sufficient angular momentum to form a disk. Such 'fallback' is both a general prediction of current supernova models and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation. Fallback disks could dramatically affect the early evolution of pulsars, yet there are few observational constraints on whether significant fallback occurs or even the actual existence of such disks. Here we report the discovery of mid-infrared emission from a cool disk around an isolated young X-ray pulsar. The disk does not power the pulsar's X-ray emission but is passively illuminated by these X-rays. The estimated mass of the disk is of the order of 10 Earth masses, and its lifetime (> or = 10(6) years) significantly exceeds the spin-down age of the pulsar, supporting a supernova fallback origin. The disk resembles protoplanetary disks seen around ordinary young stars, suggesting the possibility of planet formation around young neutron stars.

  20. A debris disk around an isolated young neutron star.

    PubMed

    Wang, Zhongxiang; Chakrabarty, Deepto; Kaplan, David L

    2006-04-01

    Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star or it may possess sufficient angular momentum to form a disk. Such 'fallback' is both a general prediction of current supernova models and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation. Fallback disks could dramatically affect the early evolution of pulsars, yet there are few observational constraints on whether significant fallback occurs or even the actual existence of such disks. Here we report the discovery of mid-infrared emission from a cool disk around an isolated young X-ray pulsar. The disk does not power the pulsar's X-ray emission but is passively illuminated by these X-rays. The estimated mass of the disk is of the order of 10 Earth masses, and its lifetime (> or = 10(6) years) significantly exceeds the spin-down age of the pulsar, supporting a supernova fallback origin. The disk resembles protoplanetary disks seen around ordinary young stars, suggesting the possibility of planet formation around young neutron stars. PMID:16598251

  1. Neutron sources and applications

    SciTech Connect

    Price, D.L.; Rush, J.J.

    1994-01-01

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

  2. Preparation of a one-curie 171Tm target for the Detector for Advanced Neutron Capture Experiments (DANCE)

    SciTech Connect

    Schwantes, Jon M.; Taylor, Wayne A.; Rundberg, Robert S.; Vieira, David J.

    2008-05-15

    Roughly one curie of 171Tm (t1/2=1.92a) has been produced and purified for the purpose of making a nuclear target for the first measurements of its neutron capture cross section. Target preparation consisted of three key steps: (1) material production; (2) separation and purification; and (3) electrodeposition onto a suitable backing material. Approximately 1.5 mg of the target material (at the time of separation) was produced by irradiating roughly 250 mg of its stable enriched 170Er lanthanide neighbor with neutrons at the ILL reactor in France. This production method resulted in a “difficult-to-separate” 1:167 mixture of near-neighboring lanthanides, Tm and Er. Separation and purification was accomplished using high-performance liquid chromatorgraphy (HPLC), with a proprietary cation exchange column (Dionex, CS-3) and alpha-hydroxyisobutyric acid (a-HIB) eluent. This technique yielded a final product of ~95% purity with respect to Tm. A portion (20 ug) of the Tm was electrodeposited on thin Be foil and delivered to the Los Alamos Neutron Science CEnter (LANSCE) for preliminary analysis of its neutron capture cross section using the Detector for Advanced Neutron Capture Experiments (DANCE). This paper discusses the major hurdles associated with the separation and purification step including, scale-up issues related to the use of HPLC for material separation and purification of the target material from a-HIB and 4-(2-pyridylazo)resorcinol (PAR) colorant.

  3. 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.

  4. Steam-explosion safety considerations for the Advanced Neutron Source Reactor at the Oak Ridge National Laboratory

    SciTech Connect

    Taleyarkhan, R.

    1990-02-01

    This report provides a perspective on steam-explosion safety and design issues for the Advanced Neutron Source (ANS) reactor being designed at the Oak Ridge National Laboratory. A historical background along with a description of experiments and analytical work performed to date has been provided. Preliminary analyses (for the ANS) have been conducted to evaluate steam-explosion pressure- pulse loadings, the effects of reactor coolant system (RCS) overpressurization, and slug energetics. The method used for pressure-pulse magnitude evaluation was benchmarked with previous calculations, an aluminum-water steam-explosion experiment, and test reactor steam explosion data with good agreement. Predicted pressure-pulse magnitudes evaluated were found to be several orders of magnitude lower than corresponding values evaluated by correlating available energies with shock-wave pressures from equivalent chemical detonations. The preliminary best estimate, as well as conservative estimates for RCS volume-pressurization failure and slug energetics for RCS volume-pressurization failure and slug energetics, indicated that (1) steam explosions in the ANS have significant damage potential, and (2) steam-explosion issues must be considered during the design phase of the ANS Project. Recommendations are made for efficiently addressing this important safety and design issue. 38 refs., 17 figs., 11 tabs.

  5. Principle and Uncertainty Quantification of an Experiment Designed to Infer Actinide Neutron Capture Cross-Sections

    SciTech Connect

    G. Youinou; G. Palmiotti; M. Salvatorre; G. Imel; R. Pardo; F. Kondev; M. Paul

    2010-01-01

    An integral reactor physics experiment devoted to infer higher actinide (Am, Cm, Bk, Cf) neutron cross sections will take place in the US. This report presents the principle of the planned experiment as well as a first exercise aiming at quantifying the uncertainties related to the inferred quantities. It has been funded in part by the DOE Office of Science in the framework of the Recovery Act and has been given the name MANTRA for Measurement of Actinides Neutron TRAnsmutation. The principle is to irradiate different pure actinide samples in a test reactor like INL’s Advanced Test Reactor, and, after a given time, determine the amount of the different transmutation products. The precise characterization of the nuclide densities before and after neutron irradiation allows the energy integrated neutron cross-sections to be inferred since the relation between the two are the well-known neutron-induced transmutation equations. This approach has been used in the past and the principal novelty of this experiment is that the atom densities of the different transmutation products will be determined with the Accelerator Mass Spectroscopy (AMS) facility located at ANL. While AMS facilities traditionally have been limited to the assay of low-to-medium atomic mass materials, i.e., A < 100, there has been recent progress in extending AMS to heavier isotopes – even to A > 200. The detection limit of AMS being orders of magnitude lower than that of standard mass spectroscopy techniques, more transmutation products could be measured and, potentially, more cross-sections could be inferred from the irradiation of a single sample. Furthermore, measurements will be carried out at the INL using more standard methods in order to have another set of totally uncorrelated information.

  6. The quest for an electric dipole moment of the neutron

    NASA Astrophysics Data System (ADS)

    Schmidt-Wellenburg, P.

    2016-07-01

    To date no electric dipole moment of the neutron (nEDM) has been observed. Why it is so vanishing small, escaping detection in the last 50 years, is not easy to explain. In general it is considered as the most sensitive probe for the violation of the combined symmetry of charge and parity (CP). A discovery could shed light on the poorly understood matter/anti-matter asymmetry of the universe. The neutron might one day help to distinguish different sources of CP-violation in combination with measurements of the electron and diamagnetic EDMs. This proceedings article presents an overview of the most important concepts in searches for an nEDM and presents a brief overview of the world wide efforts.

  7. Study on severe accident fuel dispersion behavior in the Advanced Neutron Source reactor at Oak Ridge National Laboratory

    SciTech Connect

    Kim, S.H.; Taleyarkhan, R.P.; Navarro-Valenti, S.; Georgevich, V.; Xiang, J.Y.

    1995-12-31

    Core flow blockage events are a leading contributor to core damage initiation risk in the Advanced Neutron Source (ANS) reactor. During such an accident, insufficient cooling of the fuel could result in core heatup and melting under full coolant flow condition. Coolant inertia forces acting on the melt surface would likely break up the melt into small particles. Under thermal-hydraulic conditions of ANS coolant channel, micro-fine melt particles are expected. Heat transfer between melt particle and coolant, which affects particle breakup, was studied. The study indicates that the thermal effect on melt fragmentation seems to be negligible because the time corresponding to the breakup due to hydrodynamic forces is much shorter than the time for the melt surface to solidify. The study included modeling and analyses to predict transient behavior and transport of debris particles throughout the coolant system. The transient model accounts for the surface forces acting on the particle that results from the pressure variation on the surface, inertia, virtual mass, viscous force due to relative motion of particle in the coolant, gravitation, and resistance due to inhomogenous coolant velocity radially across piping due to possible turbulent coolant motions. Results indicate that debris particles would reside longest in heat exchangers because of lower coolant velocity there. Also core debris tends to move together upon melting and entrainment.

  8. The AN neutron transport by nodal diffusion

    SciTech Connect

    Barbarino, A.; Tomatis, D.

    2013-07-01

    The two group diffusion model combined to a nodal approach in space is the preferred scheme for the industrial simulation of nuclear water reactors. The main selling point is the speed of computation, allowing a large number of parametric studies. Anyway, the drawbacks of the underlying diffusion equation may arise with highly heterogeneous interfaces, often encountered in modern UO{sub 2} and MO{sub x} fuel loading patterns, and boron less controlled systems. This paper aims at showing how the simplified AN transport model, equivalent to the well known SPN, can be implemented in standard diffusion codes with minor modifications. Some numerical results are illustrated. (authors)

  9. Neutron capture cross section of 136 Xe

    NASA Astrophysics Data System (ADS)

    Daugherty, Sean; Albert, Joshua; Johnson, Tessa; O'Conner, Thomasina; Kaufman, Lisa

    2015-04-01

    136 Xe is an important 0 νββ candidate, studied in experiments such as EXO-200 and, in the future, nEXO. These experiments require a precise study of neutron capture for their background models. The neutron capture cross section of 136 Xe has been measured at the Detector for Advanced Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. A neutron beam ranging from thermal energy to 100 keV was incident on a gas cell filled with isotopically pure 136 Xe . We will discuss the measurement of partial neutron capture cross sections at thermal and first neutron resonance energies along with corresponding capture gamma cascades.

  10. A feasibility study of [sup 252]Cf neutron brachytherapy, cisplatin + 5-FU chemo-adjuvant and accelerated hyperfractionated radiotherapy for advanced cervical cancer

    SciTech Connect

    Murayama, Y.; Wierzbicki, J. Univ. of Kentucky Medical Center, Lexington, KY ); Bowen, M.G.; Van Nagell, J.R.; Gallion, H.H.; DePriest, P. )

    1994-06-15

    The purpose was to evaluate the feasibility and toxicity of [sup 252]Cf neutron brachytherapy combined with hyperaccelerated chemoradiotherapy for Stage III and IV cervical cancers. Eleven patients with advanced Stage IIIB-IVA cervical cancers were treated with [sup 252]Cf neutron brachytherapy in an up-front schedule followed by cisplatin (CDDP; 50 mg/m[sup 2]) chemotherapy and hyperfractionated accelerated (1.2 Gy bid) radiotherapy given concurrently with intravenous infusion of 5-Fluorouracil (5-FU) (1000 mg/m[sup 2]/day [times] 4 days) in weeks 1 and 4 with conventional radiation (weeks 2, 3, 5, and 6). Total dose at a paracervical point A isodose surface was 80-85 Gy-eq by external and intracavitary therapy and 60 Gy at the pelvic sidewalls. Patients tolerated the protocol well. There was 91% compliance with the chemotherapy and full compliance with the [sup 252]Cf brachytherapy and the external beam radiotherapy. There were no problems with acute chemo or radiation toxicity. One patient developed a rectovaginal fistula (Grade 3-4 RTOG criteria) but no other patients developed significant late cystitis, proctitis or enteritis. There was complete response (CR) observed in all cases. With mean follow-up to 26 months, local control has been achieved with 90% actuarial 3-year survival with no evidence of disease (NED). [sup 252]Cf neutrons can be combined with cisplatin and 5-FU infusion chemotherapy plus hyperaccelerated chemoradiotherapy without unusual side effects or toxicity and with a high local response and tumor control rate. Further study of [sup 252]Cf neutron-chemoradiotherapy for advanced and bulky cervical cancer are indicated. The authors found chemotherapy was more effective with the improved local tumor control. 18 refs., 2 tabs.

  11. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    SciTech Connect

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  12. Neutron cross-sections for advanced nuclear systems: the n_TOF project at CERN

    NASA Astrophysics Data System (ADS)

    Barbagallo, M.; Mastromarco, M.; Colonna, N.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Hernández-Prieto, A.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Krtička, M.; Kroll, J.; Lampoudis, C.; Langer, C.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P. F.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondalaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Rubbia, C.; Sabaté-Gilarte, M.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.; Žugec, P.

    2014-12-01

    The study of neutron-induced reactions is of high relevance in a wide variety of fields, ranging from stellar nucleosynthesis and fundamental nuclear physics to applications of nuclear technology. In nuclear energy, high accuracy neutron data are needed for the development of Generation IV fast reactors and accelerator driven systems, these last aimed specifically at nuclear waste incineration, as well as for research on innovative fuel cycles. In this context, a high luminosity Neutron Time Of Flight facility, n_TOF, is operating at CERN since more than a decade, with the aim of providing new, high accuracy and high resolution neutron cross-sections. Thanks to the features of the neutron beam, a rich experimental program relevant to nuclear technology has been carried out so far. The program will be further expanded in the near future, thanks in particular to a new high-flux experimental area, now under construction.

  13. Neutron-proton correlations in an exactly solvable model

    SciTech Connect

    Engel, J.; Pittel, S.; Stoitsov, M.; Vogel, P.; Dukelsky, J.

    1997-04-01

    We examine isovector and isoscalar neutron-proton correlations in an exactly solvable model based on the algebra SO(8). We look particularly closely at Gamow-Teller strength and double {beta} decay, both to isolate the effects of the two kinds of pairing and to test two approximation schemes: the renormalized neutron-proton quasiparticle random phase approximation (QRPA) and generalized BCS theory. When isoscalar pairing correlations become strong enough a phase transition occurs and the dependence of the Gamow-Teller {beta}{sup +} strength on isospin changes in a dramatic and unfamiliar way, actually increasing as neutrons are added to an N=Z core. Renormalization eliminates the well-known instabilities that plague the QRPA as the phase transition is approached, but only by unnaturally suppressing the isoscalar correlations. Generalized BCS theory, on the other hand, reproduces the Gamow-Teller strength more accurately in the isoscalar phase than in the usual isovector phase, even though its predictions for energies are equally good everywhere. It also mixes T=0 and T=1 pairing, but only on the isoscalar side of the phase transition. {copyright} {ital 1997} {ital The American Physical Society}

  14. An Improved Neutron Transport Algorithm for Space Radiation

    NASA Technical Reports Server (NTRS)

    Heinbockel, John H.; Clowdsley, Martha S.; Wilson, John W.

    2000-01-01

    A low-energy neutron transport algorithm for use in space radiation protection is developed. The algorithm is based upon a multigroup analysis of the straight-ahead Boltzmann equation by using a mean value theorem for integrals. This analysis is accomplished by solving a realistic but simplified neutron transport test problem. The test problem is analyzed by using numerical and analytical procedures to obtain an accurate solution within specified error bounds. Results from the test problem are then used for determining mean values associated with rescattering terms that are associated with a multigroup solution of the straight-ahead Boltzmann equation. The algorithm is then coupled to the Langley HZETRN code through the evaporation source term. Evaluation of the neutron fluence generated by the solar particle event of February 23, 1956, for a water and an aluminum-water shield-target configuration is then compared with LAHET and MCNPX Monte Carlo code calculations for the same shield-target configuration. The algorithm developed showed a great improvement in results over the unmodified HZETRN solution. In addition, a two-directional solution of the evaporation source showed even further improvement of the fluence near the front of the water target where diffusion from the front surface is important.

  15. Boron neutron capture therapy applied to advanced breast cancers: Engineering simulation and feasibility study of the radiation treatment protocol

    NASA Astrophysics Data System (ADS)

    Sztejnberg Goncalves-Carralves, Manuel Leonardo

    This dissertation describes a novel Boron Neutron Capture Therapy (BNCT) application for the treatment of human epidermal growth factor receptor type 2 positive (HER2+) breast cancers. The original contribution of the dissertation is the development of the engineering simulation and the feasibility study of the radiation treatment protocol for this novel combination of BNCT and HER2+ breast cancer treatment. This new concept of BNCT, representing a radiation binary targeted treatment, consists of the combination of two approaches never used in a synergism before. This combination may offer realistic hope for relapsed and/or metastasized breast cancers. This treatment assumes that the boronated anti-HER2 monoclonal antibodies (MABs) are administrated to the patient and accumulate preferentially in the tumor. Then the tumor is destroyed when is exposed to neutron irradiation. Since the use of anti-HER2 MABs yields good and promising results, the proposed concept is expected to amplify the known effect and be considered as a possible additional treatment approach to the most severe breast cancers for patients with metastasized cancer for which the current protocol is not successful and for patients refusing to have the standard treatment protocol. This dissertation makes an original contribution with an integral numerical approach and proves feasible the combination of the aforementioned therapy and disease. With these goals, the dissertation describes the theoretical analysis of the proposed concept providing an integral engineering simulation study of the treatment protocol. An extensive analysis of the potential limitations, capabilities and optimization factors are well studied using simplified models, models based on real CT patients' images, cellular models, and Monte Carlo (MCNP5/X) transport codes. One of the outcomes of the integral dosimetry assessment originally developed for the proposed treatment of advanced breast cancers is the implementation of BNCT

  16. A new shipping container for an intense neutron emitter

    SciTech Connect

    Bigelow, J.E.; Alexander, C.W.; Pace, J.V. III; Simmons, C.M.

    1994-06-01

    Californium-252 is an intense neutron emitter (2.34 {times} 10{sup 12} n/s{center_dot}g) used in medicine, research, and industry. The western world`s sole source of this rare radioisotope is the Californium Facility at Oak Ridge National Laboratory`s Radiochemical Engineering Development Center (REDC). A project has been initiated at the REDC to design a new Type B Californium Shipping Container. This effort is essential for future transportation of californium to meet the needs of users all over the world. The shipping container must meet all requirements for transport by motor freight, air, vessel, and rail, both domestic and foreign. There are unique problems in the design, fabrication, and licensing of a new Type B shipping container that will accommodate up to 60 milligrams of californium-252. One of the first challenges in the design phase of the project is the selection of a material to shield the high neutron flux. The more stringent safety precautions of today`s world impel us to consider more exotic materials for such a purpose. The candidate materials must be examined not just for their neutron shielding properties, but also in conjunction with other properties such as thermal and structural requirements to withstand the hypothetical accident conditions. The design and building of such a container is a formidable task requiring much planning. The licensing process, with the complex, interactive federal codes, is a special challenge and may be the biggest on the project in terms of time and money.

  17. An Improved Neutron Transport Algorithm for HZETRN2006

    NASA Astrophysics Data System (ADS)

    Slaba, Tony

    NASA's new space exploration initiative includes plans for long term human presence in space thereby placing new emphasis on space radiation analyses. In particular, a systematic effort of verification, validation and uncertainty quantification of the tools commonly used for radiation analysis for vehicle design and mission planning has begun. In this paper, the numerical error associated with energy discretization in HZETRN2006 is addressed; large errors in the low-energy portion of the neutron fluence spectrum are produced due to a numerical truncation error in the transport algorithm. It is shown that the truncation error results from the narrow energy domain of the neutron elastic spectral distributions, and that an extremely fine energy grid is required in order to adequately resolve the problem under the current formulation. Since adding a sufficient number of energy points will render the code computationally inefficient, we revisit the light-ion transport theory developed for HZETRN2006 and focus on neutron elastic interactions. The new approach that is developed numerically integrates with adequate resolution in the energy domain without affecting the run-time of the code and is easily incorporated into the current code. Efforts were also made to optimize the computational efficiency of the light-ion propagator; a brief discussion of the efforts is given along with run-time comparisons between the original and updated codes. Convergence testing is then completed by running the code for various environments and shielding materials with many different energy grids to ensure stability of the proposed method.

  18. Secondary neutron dose measurement for proton eye treatment using an eye snout with a borated neutron absorber

    PubMed Central

    2013-01-01

    Background We measured and assessed ways to reduce the secondary neutron dose from a system for proton eye treatment. Methods Proton beams of 60.30 MeV were delivered through an eye-treatment snout in passive scattering mode. Allyl diglycol carbonate (CR-39) etch detectors were used to measure the neutron dose in the external field at 0.00, 1.64, and 6.00 cm depths in a water phantom. Secondary neutron doses were measured and compared between those with and without a high-hydrogen–boron-containing block. In addition, the neutron energy and vertices distribution were obtained by using a Geant4 Monte Carlo simulation. Results The ratio of the maximum neutron dose equivalent to the proton absorbed dose (H(10)/D) at 2.00 cm from the beam field edge was 8.79 ± 1.28 mSv/Gy. The ratio of the neutron dose equivalent to the proton absorbed dose with and without a high hydrogen-boron containing block was 0.63 ± 0.06 to 1.15 ± 0.13 mSv/Gy at 2.00 cm from the edge of the field at depths of 0.00, 1.64, and 6.00 cm. Conclusions We found that the out-of-field secondary neutron dose in proton eye treatment with an eye snout is relatively small, and it can be further reduced by installing a borated neutron absorbing material. PMID:23866307

  19. Broad Energy Range Neutron Spectroscopy using a Liquid Scintillator and a Proportional Counter: Application to a Neutron Spectrum Similar to that from an Improvised Nuclear Device

    PubMed Central

    Randers-Pehrson, Gerhard; Marino, Stephen A.; Garty, Guy; Harken, Andrew; Brenner, David J.

    2015-01-01

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n)3He and D(d,n)3He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima. PMID:26273118

  20. Passive and Active Fast-Neutron Imaging in Support of Advanced Fuel Cycle Initiative Safeguards Campaign

    SciTech Connect

    Blackston, Matthew A; Hausladen, Paul

    2010-04-01

    Results from safeguards-related passive and active coded-aperture fast-neutron imaging measurements of plutonium and highly enriched uranium (HEU) material configurations performed at Idaho National Laboratory s Zero Power Physics Reactor facility are presented. The imaging measurements indicate that it is feasible to use fast neutron imaging in a variety of safeguards-related tasks, such as monitoring storage, evaluating holdup deposits in situ, or identifying individual leached hulls still containing fuel. The present work also presents the first demonstration of imaging of differential die away fast neutrons.

  1. EPR: an Advanced Evolutionary Design

    SciTech Connect

    Czech, Juergen; Bouteille, Francois; Hudson, Greg

    2004-07-01

    This paper presents the main features of the EPR, an evolutionary design product that builds on French N4 plants (Chooz and Civaux) and Konvoi, the most recent reactor series built in Germany. This Franco-German project was driven by a common French and German desire to cooperate in several areas. In January 2001, Framatome SA and Siemens AG merged their nuclear activities to form Framatome ANP with three regional entities in France, Germany and the USA. The recent decision of Teollisuuden Voima Oy (TVO) to select the EPR for construction in Olkiluoto of the fifth Nuclear Power Plant in Finland gave a new impetus to the project. Framatome ANP is committed to put the FOAK EPR in commercial operation on May 1, 2009. This challenging time schedule will set a new reference for 'Generation III +' LWR's. (authors)

  2. Plasma Heating: An Advanced Technology

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The Mercury and Apollo spacecraft shields were designed to protect astronauts from high friction temperatures (well over 2,000 degrees Fahrenheit) when re-entering the Earth's atmosphere. It was necessary to test and verify the heat shield materials on Earth before space flight. After exhaustive research and testing, NASA decided to use plasma heating as a heat source. This technique involves passing a strong electric current through a rarefied gas to create a plasma (ionized gas) that produces an intensely hot flame. Although NASA did not invent the concept, its work expanded the market for commercial plasma heating systems. One company, Plasma Technology Corporation (PTC), was founded by a member of the team that developed the Re-entry Heating Simulator at Ames Research Center (ARC). Dr. Camacho, President of PTC, believes the technology has significant environmental applications. These include toxic waste disposal, hydrocarbon, decomposition, medical waste disposal, asbestos waste destruction, and chemical and radioactive waste disposal.

  3. Neutron and gamma detector using an ionization chamber with an integrated body and moderator

    DOEpatents

    Ianakiev, Kiril D.; Swinhoe, Martyn T.; Lestone, John Paul

    2006-07-18

    A detector for detecting neutrons and gamma radiation includes a cathode that defines an interior surface and an interior volume. A conductive neutron-capturing layer is disposed on the interior surface of the cathode and a plastic housing surrounds the cathode. A plastic lid is attached to the housing and encloses the interior volume of the cathode forming an ionization chamber, into the center of which an anode extends from the plastic lid. A working gas is disposed within the ionization chamber and a high biasing voltage is connected to the cathode. Processing electronics are coupled to the anode and process current pulses which are converted into Gaussian pulses, which are either counted as neutrons or integrated as gammas, in response to whether pulse amplitude crosses a neutron threshold. The detector according to the invention may be readily fabricated into single or multilayer detector arrays.

  4. Monte Carlo calculation of skyshine'' neutron dose from ALS (Advanced Light Source)

    SciTech Connect

    Moin-Vasiri, M.

    1990-06-01

    This report discusses the following topics on skyshine'' neutron dose from ALS: Sources of radiation; ALS modeling for skyshine calculations; MORSE Monte-Carlo; Implementation of MORSE; Results of skyshine calculations from storage ring; and Comparison of MORSE shielding calculations.

  5. Thermal neutron detection system

    DOEpatents

    Peurrung, Anthony J.; Stromswold, David C.

    2000-01-01

    According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

  6. Advanced sample environments for in situ neutron diffraction studies of nuclear materials

    NASA Astrophysics Data System (ADS)

    Reiche, Helmut Matthias

    Generation IV nuclear reactor concepts, such as the supercritical-water-cooled nuclear reactor (SCWR), are actively researched internationally. Operating conditions above the critical point of water (374°C, 22.1 MPa) and fuel core temperature that potentially exceed 1850°C put a high demand on the surrounding materials. For their safe application, it is essential to characterize and understand the material properties on an atomic scale such as crystal structure and grain orientation (texture) changes as a function of temperature and stress. This permits the refinement of models predicting the macroscopic behavior of the material. Neutron diffraction is a powerful tool in characterizing such crystallographic properties due to their deep penetration depth into condensed matter. This leads to the ability to study bulk material properties, as opposed to surface effects, and allows for complex sample environments to study e.g. the individual contributions of thermo-mechanical processing steps during manufacturing, operating or accident scenarios. I present three sample environments for in situ neutron diffraction studies that provide such crystallographic information and have been successfully commissioned and integrated into the user program of the High Pressure -- Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron Science Center (LANSCE) user facility. I adapted a sample changer for reliable and fast automated texture measurements of multiple specimens. I built a creep furnace combining a 2700 N load frame with a resistive vanadium furnace, capable of temperatures up to 1000°C, and manipulated by a pair of synchronized rotation stages. This combination allows following deformation and temperature dependent texture and strain evolutions in situ. Utilizing the presented sample changer and creep furnace we studied pressure tubes made of Zr-2.5wt%Nb currently employed in CANDURTM nuclear reactors and proposed for future SCWRs, acting as the primary

  7. ATR neutron spectral characterization

    SciTech Connect

    Rogers, J.W.; Anderl, R.A.

    1995-11-01

    The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix.

  8. Systematic neutron guide misalignment for an accelerator-driven spallation neutron source

    NASA Astrophysics Data System (ADS)

    Zendler, C.; Bentley, P. M.

    2016-08-01

    The European Spallation Source (ESS) is a long pulse spallation neutron source that is currently under construction in Lund, Sweden. A considerable fraction of the 22 planned instruments extend as far as 75-150 m from the source. In such long beam lines, misalignment between neutron guide segments can decrease the neutron transmission significantly. In addition to a random misalignment from installation tolerances, the ground on which ESS is built can be expected to sink with time, and thus shift the neutron guide segments further away from the ideal alignment axis in a systematic way. These systematic errors are correlated to the ground structure, position of buildings and shielding installation. Since the largest deformation is expected close to the target, even short instruments might be noticeably affected. In this study, the effect of this systematic misalignment on short and long ESS beam lines is analyzed, and a possible mitigation by overillumination of subsequent guide sections investigated.

  9. Development of Mechanistic Modeling Capabilities for Local Neutronically-Coupled Flow-Induced Instabilities in Advanced Water-Cooled Reactors

    SciTech Connect

    Michael Podowski

    2009-11-30

    The major research objectives of this project included the formulation of flow and heat transfer modeling framework for the analysis of flow-induced instabilities in advanced light water nuclear reactors such as boiling water reactors. General multifield model of two-phase flow, including the necessary closure laws. Development of neurton kinetics models compatible with the proposed models of heated channel dynamics. Formulation and encoding of complete coupled neutronics/thermal-hydraulics models for the analysis of spatially-dependent local core instabilities. Computer simulations aimed at testing and validating the new models of reactor dynamics.

  10. Characterisation of an accelerator-based neutron source for BNCT versus beam energy

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Curzio, G.; d'Errico, F.; Nath, R.; Tinti, R.

    2002-01-01

    Neutron capture in 10B produces energetic alpha particles that have a high linear energy transfer in tissue. This results in higher cell killing and a higher relative biological effectiveness compared to photons. Using suitably designed boron compounds which preferentially localize in cancerous cells instead of healthy tissues, boron neutron capture therapy (BNCT) has the potential of providing a higher tumor cure rate within minimal toxicity to normal tissues. This clinical approach requires a thermal neutron source, generally a nuclear reactor, with a fluence rate sufficient to deliver tumorcidal doses within a reasonable treatment time (minutes). Thermal neutrons do not penetrate deeply in tissue, therefore BNCT is limited to lesions which are either superficial or otherwise accessible. In this work, we investigate the feasibility of an accelerator-based thermal neutron source for the BNCT of skin melanomas. The source was designed via MCNP Monte Carlo simulations of the thermalization of a fast neutron beam, generated by 7 MeV deuterons impinging on a thick target of beryllium. The neutron field was characterized at several deuteron energies (3.0-6.5 MeV) in an experimental structure installed at the Van De Graaff accelerator of the Laboratori Nazionali di Legnaro, in Italy. Thermal and epithermal neutron fluences were measured with activation techniques and fast neutron spectra were determined with superheated drop detectors (SDD). These neutron spectrometry and dosimetry studies indicated that the fast neutron dose is unacceptably high in the current design. Modifications to the current design to overcome this problem are presented.

  11. Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC

    NASA Astrophysics Data System (ADS)

    Magee, R. M.; Clary, R.; Korepanov, S.; Jauregui, F.; Allfrey, I.; Garate, E.; Valentine, T.; Smirnov, A.

    2016-11-01

    In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 107 n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.

  12. Monte Carlo simulation of a Bonner sphere spectrometer for application to the determination of neutron field in the Experimental Advanced Superconducting Tokamak experimental hall

    SciTech Connect

    Hu, Z. M.; Xie, X. F.; Chen, Z. J.; Peng, X. Y.; Du, T. F.; Cui, Z. Q.; Ge, L. J.; Li, T.; Yuan, X.; Zhang, X.; Li, X. Q.; Zhang, G. H.; Chen, J. X.; Fan, T. S.; Hu, L. Q.; Zhong, G. Q.; Lin, S. Y.; Wan, B. N.; Gorini, G.

    2014-11-15

    To assess the neutron energy spectra and the neutron dose for different positions around the Experimental Advanced Superconducting Tokamak (EAST) device, a Bonner Sphere Spectrometer (BSS) was developed at Peking University, with totally nine polyethylene spheres and a SP9 {sup 3}He counter. The response functions of the BSS were calculated by the Monte Carlo codes MCNP and GEANT4 with dedicated models, and good agreement was found between these two codes. A feasibility study was carried out with a simulated neutron energy spectrum around EAST, and the simulated “experimental” result of each sphere was obtained by calculating the response with MCNP, which used the simulated neutron energy spectrum as the input spectrum. With the deconvolution of the “experimental” measurement, the neutron energy spectrum was retrieved and compared with the preset one. Good consistence was found which offers confidence for the application of the BSS system for dose and spectrum measurements around a fusion device.

  13. Monte Carlo simulation of a Bonner sphere spectrometer for application to the determination of neutron field in the Experimental Advanced Superconducting Tokamak experimental hall.

    PubMed

    Hu, Z M; Xie, X F; Chen, Z J; Peng, X Y; Du, T F; Cui, Z Q; Ge, L J; Li, T; Yuan, X; Zhang, X; Hu, L Q; Zhong, G Q; Lin, S Y; Wan, B N; Gorini, G; Li, X Q; Zhang, G H; Chen, J X; Fan, T S

    2014-11-01

    To assess the neutron energy spectra and the neutron dose for different positions around the Experimental Advanced Superconducting Tokamak (EAST) device, a Bonner Sphere Spectrometer (BSS) was developed at Peking University, with totally nine polyethylene spheres and a SP9 (3)He counter. The response functions of the BSS were calculated by the Monte Carlo codes MCNP and GEANT4 with dedicated models, and good agreement was found between these two codes. A feasibility study was carried out with a simulated neutron energy spectrum around EAST, and the simulated "experimental" result of each sphere was obtained by calculating the response with MCNP, which used the simulated neutron energy spectrum as the input spectrum. With the deconvolution of the "experimental" measurement, the neutron energy spectrum was retrieved and compared with the preset one. Good consistence was found which offers confidence for the application of the BSS system for dose and spectrum measurements around a fusion device.

  14. An advanced ISOL facility based on ATLAS.

    SciTech Connect

    Nolen, J. A.

    1999-02-24

    The Argonne concept for an accelerator complex for efficiently producing high-quality radioactive beams from ion source energy up to 6-15 MeV/u is described. The Isotope-Separator-On-Line (ISOL) method is used. A high-power driver accelerator produces radionuclides in a target that is closely coupled to an ion source and mass separator. By using a driver accelerator which can deliver a variety of beams and energies the radionuclide production mechanisms can be chosen to optimize yields for the species of interest. To effectively utilize the high beam power of the driver two-step target/ion source geometries are proposed (1) Neutron production with intermediate energy deuterons on a primary target to produce neutron-rich fission products in a secondary {sup 238}U target, and (2) Fragmentation of neutron-rich heavy ion rich fission products in a secondary beams such as {sup 18}O in a target/catcher geometry. Heavy ion beams with total energies in the 1-10 GcV range are also available for radionuclide production via high-energy spallation reactions. At the present time R and D is in progress to develop superconducting resonator structures for a driver linac to cover the energy range up to 100 MeV per nucleon for heavy ions and 200 MeV for protons. The post accelerator scheme is based on using existing ISOL-type 1+ ion source technology followed by CW Radio Frequency Quadruple (RFQ) accelerators and superconducting linacs including the present ATLAS accelerator. A full-scale prototype of the first-stage RFQ has been successfully tested with RF at full design voltage and tests with ion beams are in progress. A benchmark beam, {sup 132}Sn {at} 7 MeV/u, requires two stripping stages, one a gas stripper at very low velocity after the first RFQ section, and one a foil stripper at higher velocity after a superconducting-linac injector.

  15. Advanced Aircraft Structures program: an overview

    NASA Astrophysics Data System (ADS)

    Becker, Juergen; Schroeder, H. W.; Dittrich, Kay W.; Bauer, E. J.; Zippold, H.

    1999-07-01

    Requirements of future military aircraft structures are constantly increasing with advancing technological progress. While performance is still the main focus, costs have become a major issue in military aircraft procurement.In order to efficiently support its technological base oriented on the future demands of the market Daimler Chrysler Aerospace/Military Aircraft Division has inaugurated the Advanced Aircraft Structures Program, a collaborative research effort together with the German Aerospace Center and Daimler Chrysler Research and Technology, the corporate research division of Daimler Benz. The two key technologies to be pursued within the framework of this program are cost- effective composite structures and smart materials. This paper will give an overview of the Advanced Aircraft Structures Program with particular emphasis on smart structures technology as applied to active vibration damping, vibration isolation of equipment and composite health monitoring.

  16. An approach of reducing the background induced by neutrons

    NASA Technical Reports Server (NTRS)

    Shen, C.; Gu, Y.; Sun, Y.; Ma, Y.; Dai, C.; Fan, Z.

    1985-01-01

    The background induced by interactions of neutrons with detector material (and shield material) is difficult to be rejected. It is one of the most important factors to affect the sensitivity of a balloon-borne gamma-ray astronomical telescope. The main component of neutron flux at the major detector of the telescope is incident neutrons, that consists of atmospheric neutrons and neutrons locally produced in the balloon platform. Therefore, shielding the detector from incident neutrons is a possible way to reduce the background. NaI (T1) crystal is very widely used in gamma-ray astronomical telescopes. Through balloon-borne experiment it is shown that up 6 LiF shield is effective to reduce the background in NaI crystal.

  17. The Advancement Value Chain: An Exploratory Model

    ERIC Educational Resources Information Center

    Leonard, Edward F., III

    2005-01-01

    Since the introduction of the value chain concept in 1985, several varying, yet virtually similar, value chains have been developed for the business enterprise. Shifting to higher education, can a value chain be found that links together the various activities of advancement so that an institution's leaders can actually look at the philanthropic…

  18. PROTON RADIOGRAPHY FOR AN ADVANCED HYDROTEST FACILITY

    SciTech Connect

    C. MORRIS

    2000-11-01

    Analysis of data from BNL experiment 933 is presented. Results demonstrate that proton radiography can meet many of the requirements for an Advanced Hydrotest Facility (AHF). Results for background, position resolution, metrology, quantitative radiography, material identification, and edge resolution are presented.

  19. An Advance Organizer for Teaching Bacterial Metabolism

    ERIC Educational Resources Information Center

    Barbosa, Heloiza R.; Marques, Marilis V.; Torres, Bayardo B.

    2005-01-01

    The metabolic versatility of bacteria is a source of learning difficulty for students in classical microbiology courses. To facilitate the learning process, the authors developed an advance organizer. It consists of a set of six diagrams of metabolic pathways describing the basic living requirements of several types of bacteria: energy, carbon…

  20. Assessing an Advanced Level Introductory Sociology Course

    ERIC Educational Resources Information Center

    Keesler, Venessa A.; Fermin, Baranda J.; Schneider, Barbara

    2008-01-01

    In 2001, the governing council of the American Sociological Association (ASA) appointed Professor Caroline Persell of New York University to launch a task force with the goal of creating an advanced high school sociology curriculum that would also be a model for introductory sociology courses in colleges and universities. The principle goal of the…

  1. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device

    PubMed Central

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C.; Marino, Stephen A.; Geard, Charles R.; Brenner, David J.; Garty, Guy

    2015-01-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  2. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  3. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields.

  4. Validation and verification of RELAP5 for Advanced Neutron Source accident analysis: Part I, comparisons to ANSDM and PRSDYN codes

    SciTech Connect

    Chen, N.C.J.; Ibn-Khayat, M.; March-Leuba, J.A.; Wendel, M.W.

    1993-12-01

    As part of verification and validation, the Advanced Neutron Source reactor RELAP5 system model was benchmarked by the Advanced Neutron Source dynamic model (ANSDM) and PRSDYN models. RELAP5 is a one-dimensional, two-phase transient code, developed by the Idaho National Engineering Laboratory for reactor safety analysis. Both the ANSDM and PRSDYN models use a simplified single-phase equation set to predict transient thermal-hydraulic performance. Brief descriptions of each of the codes, models, and model limitations were included. Even though comparisons were limited to single-phase conditions, a broad spectrum of accidents was benchmarked: a small loss-of-coolant-accident (LOCA), a large LOCA, a station blackout, and a reactivity insertion accident. The overall conclusion is that the three models yield similar results if the input parameters are the same. However, ANSDM does not capture pressure wave propagation through the coolant system. This difference is significant in very rapid pipe break events. Recommendations are provided for further model improvements.

  5. Layered shielding design for an active neutron interrogation system

    NASA Astrophysics Data System (ADS)

    Whetstone, Zachary D.; Kearfott, Kimberlee J.

    2016-08-01

    The use of source and detector shields in active neutron interrogation can improve detector signal. In simulations, a shielded detector with a source rotated π/3 rad relative to the opening decreased neutron flux roughly three orders of magnitude. Several realistic source and detector shield configurations were simulated. A layered design reduced neutron and secondary photon flux in the detector by approximately one order of magnitude for a deuterium-tritium source. The shield arrangement can be adapted for a portable, modular design.

  6. Advanced in-situ measurement of soil carbon content using inelastic neutron scattering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measurement and mapping of natural and anthropogenic variations in soil carbon stores is a critical component of any soil resource evaluation process. Emerging modalities for soil carbon analysis in the field is the registration of gamma rays from soil under neutron irradiation. The inelastic neutro...

  7. DOD's advanced thermionics program an overview

    SciTech Connect

    Drake, T.R.

    1998-07-01

    The Defense Special Weapons Agency (DSWA) manages a congressionally mandated program in advanced thermionics research. Guided by congressional language to advance the state-of-the-art in the US and support the Integrated Solar Upper Stage (ISUS) program, DSWA efforts concentrate on four areas: an electrically testable design of a high-performance, in-core thermionic fuel element (TFE), the ISUS program, a microminiature thermionic converter and several modeling efforts. The DSWA domestic program is augmented by several small contracts with Russian institutes, awarded under the former TOPAZ International Program that the Ballistic Missile Defense Organization transferred to DSWA. The design effort at General Atomics will result in an electrically testable, multi-cell TFE for in-core conversion, involving system design and advanced collector and emitter technologies. For the ISUS program, DSWA funded a portion of the engine ground demonstration, including development of the power management system and the planar diodes. Current efforts supporting ISUS include continued diode testing and developing an advanced planar diode. The MTC program seeks to design a mass producable, close-spaced thermionic converter using integrated circuit technologies. Modeling and analysis at DSWA involves development of the Reactor System Mass with Thermionics estimation model (RSMASS-T), developing a new thermionic theory, and reviewing applications for the MTC technology. The Russian deliverables include several reports and associated hardware that describe many of its state-of-the-art thermionic technologies and processes.

  8. Towards an optimal search strategy of optical and gravitational wave emissions from binary neutron star coalescence

    NASA Astrophysics Data System (ADS)

    Coward, D. M.; Gendre, B.; Sutton, P. J.; Howell, E. J.; Regimbau, T.; Laas-Bourez, M.; Klotz, A.; Boër, M.; Branchesi, M.

    2011-07-01

    Observations of an optical source coincident with gravitational wave emission detected from a binary neutron star coalescence will improve the confidence of detection, provide host galaxy localization and test models for the progenitors of short gamma-ray bursts. We employ optical observations of three short gamma-ray bursts, 050724, 050709 and 051221, to estimate the detection rate of a coordinated optical and gravitational wave search of neutron star mergers. Model R-band optical afterglow light curves of these bursts that include a jet-break are extrapolated for these sources at the sensitivity horizon of an Advanced LIGO/Virgo network. Using optical sensitivity limits of three telescopes, namely TAROT (m = 18), Zadko (m = 21) and an 8-10 m class telescope (m = 26), we approximate detection rates and cadence times for imaging. We find a median coincident detection rate of 4 yr-1 for the three bursts. GRB 050724 like bursts, with wide opening jet angles, offer the most optimistic rate of 13 coincident detections per year, and would be detectable by Zadko up to 5 d after the trigger. Late-time imaging to m = 26 could detect off-axis afterglows for GRB 051221 like bursts several months after the trigger. For a broad distribution of beaming angles, the optimal strategy for identifying the optical emissions triggered by gravitational wave detectors is rapid response searches with robotic telescopes followed by deeper imaging at later times if an afterglow is not detected within several days of the trigger.

  9. Neutron Transport Characteristics of a Nuclear Reactor Based Dynamic Neutron Imaging System

    SciTech Connect

    Khaial, Anas M.; Harvel, Glenn D.; Chang, Jen-Shih

    2006-07-01

    An advanced dynamic neutron imaging system has been constructed in the McMaster Nuclear Reactor (MNR) for nondestructive testing and multi-phase flow studies in energy and environmental applications. A high quality neutron beam is required with a thermal neutron flux greater than 5.0 x 10{sup 6} n/cm{sup 2}-s and a collimation ratio of 120 at image plane to promote high-speed neutron imaging up to 2000 frames per second. Neutron source strength and neutron transport have been experimentally and numerically investigated. Neutron source strength at the beam tube entrance was evaluated experimentally by measuring the thermal and fast neutron fluxes, and simple analytical neutron transport calculations were performed based upon these measured neutron fluxes to predict facility components in accordance with high-speed dynamic neutron imaging and operation safety requirements. Monte-Carlo simulations (using MCNP-4B code) with multiple neutron energy groups have also been used to validate neutron beam parameters and to ensure shielding capabilities of facility shutter and cave walls. Neutron flux distributions at the image plane and the neutron beam characteristics were experimentally measured by irradiating a two-dimensional array of Copper foils and using a real-time neutron radiography system. The neutron image characteristics -- such as neutron flux, image size, beam quality -- measured experimentally and predicted numerically for beam tube, beam shutter and radiography cave are compared and discussed in detail in this paper. The experimental results show that thermal neutron flux at image plane is nearly uniform over an imaging area of 20.0-cm diameter and its magnitude ranges from 8.0 x 10{sup 6} - 1.0 x 10{sup 7} n/cm{sup 2}-sec while the neutron-to-gamma ratio is 6.0 x 10{sup 5} n/cm{sup 2}-{mu}Sv. (authors)

  10. Experiment Design and Analysis Guide - Neutronics & Physics

    SciTech Connect

    Misti A Lillo

    2014-06-01

    The purpose of this guide is to provide a consistent, standardized approach to performing neutronics/physics analysis for experiments inserted into the Advanced Test Reactor (ATR). This document provides neutronics/physics analysis guidance to support experiment design and analysis needs for experiments irradiated in the ATR. This guide addresses neutronics/physics analysis in support of experiment design, experiment safety, and experiment program objectives and goals. The intent of this guide is to provide a standardized approach for performing typical neutronics/physics analyses. Deviation from this guide is allowed provided that neutronics/physics analysis details are properly documented in an analysis report.

  11. Characterization of an accelerator neutron source based on the Be(d,n) reaction

    SciTech Connect

    Meadows, J.W.; Smith, D.L.

    1992-01-01

    Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.

  12. Characterization of an accelerator neutron source based on the Be(d,n) reaction

    SciTech Connect

    Meadows, J.W.; Smith, D.L.

    1992-07-01

    Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.

  13. Study of the neutron field in the vicinity of an unshielded PET cyclotron.

    PubMed

    Méndez, R; Iñiguez, M P; Martí-Climent, J M; Peñuelas, I; Vega-Carrillo, H R; Barquero, R

    2005-11-01

    The neutron field in the proximity of an unshielded PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Thermoluminescent detector (TLD) models TLD600 and TLD700 as well as Bonner moderating spheres were irradiated at different positions inside the vault room where the cyclotron is located to determine the thermal neutron flux, neutron spectrum and dose equivalent. Furthermore, from a combination of measurements and Monte Carlo simulations the neutron source intensity at the target was estimated. The resulting intensity is in good agreement with the IAEA recommendations. Neutron doses derived from the measured spectra were found to vary between 7 and 320 mSv per 1 microA h of proton-integrated current. Finally, gamma doses were determined from TLD700 readings and amounted to around 10% of the neutron doses.

  14. Gadolinium as an element for neutron capture therapy

    SciTech Connect

    Brugger, R.M.; Liu, H.B.; Laster, B.H.; Gordon, C.R.; Greenberg, D.D.; Warkentien, L.S.

    1992-01-01

    At BNL, preparations are being made to test in vitro compounds containing Gd and compare their response to the response of GD-DTPA to determine if one or several compounds can be located that enter the cells and enhance the Auger effect. Two similar rotators with positions for cell vials that have been constructed for these tests. The first rotator is made of only paraffin which simulates healthy tissue and provides control curves. The second rotator has 135 ppM of Gd-157 in the paraffin to simulate a Gd loaded tumor. Cells are irradiated in vials in the paraffin rotator and in the Gd-paraffin rotator at the epithermal beam of the Brookhaven Medical Research Reactor (BMRR). This produces an irradiation similar to what a patient would receive In an actual treatment. A combination of irradiations are made with both rotators; with no Gd compound or IdUrd In the cell media, with only Gd compound in the cell media and with both Gd compound and IdUrd in the cell media. The first set shows the effects of gamma rays from the H(n,gamma) reaction and the prompt gamma rays from capture of neutrons by Gd. The second set shows if there is any effect of Gd being in the cell media or inside the cells, i.e., an Auger effect. The third set shows the effect of enhancement by the IdUrd produced by the gamma rays from neutrons captured by either H or Gd. The fourth set combines all of the reactions and enhancements. Preliminary calculations and physical measurements of the doses that the cells will receive In these rotators have been made.

  15. Gadolinium as an element for neutron capture therapy

    SciTech Connect

    Brugger, R.M.; Liu, H.B.; Laster, B.H.; Gordon, C.R.; Greenberg, D.D.; Warkentien, L.S.

    1992-12-31

    At BNL, preparations are being made to test in vitro compounds containing Gd and compare their response to the response of GD-DTPA to determine if one or several compounds can be located that enter the cells and enhance the Auger effect. Two similar rotators with positions for cell vials that have been constructed for these tests. The first rotator is made of only paraffin which simulates healthy tissue and provides control curves. The second rotator has 135 ppM of Gd-157 in the paraffin to simulate a Gd loaded tumor. Cells are irradiated in vials in the paraffin rotator and in the Gd-paraffin rotator at the epithermal beam of the Brookhaven Medical Research Reactor (BMRR). This produces an irradiation similar to what a patient would receive In an actual treatment. A combination of irradiations are made with both rotators; with no Gd compound or IdUrd In the cell media, with only Gd compound in the cell media and with both Gd compound and IdUrd in the cell media. The first set shows the effects of gamma rays from the H(n,gamma) reaction and the prompt gamma rays from capture of neutrons by Gd. The second set shows if there is any effect of Gd being in the cell media or inside the cells, i.e., an Auger effect. The third set shows the effect of enhancement by the IdUrd produced by the gamma rays from neutrons captured by either H or Gd. The fourth set combines all of the reactions and enhancements. Preliminary calculations and physical measurements of the doses that the cells will receive In these rotators have been made.

  16. Advances in Ecological Speciation: an integrative approach.

    PubMed

    Faria, Rui; Renaut, Sebastien; Galindo, Juan; Pinho, Catarina; Melo-Ferreira, José; Melo, Martim; Jones, Felicity; Salzburger, Walter; Schluter, Dolph; Butlin, Roger

    2014-02-01

    The role of natural selection in promoting reproductive isolation has received substantial renewed interest within the last two decades. As a consequence, the study of ecological speciation has become an extremely productive research area in modern evolutionary biology. Recent innovations in sequencing technologies offer an unprecedented opportunity to study the mechanisms involved in ecological speciation. Genome scans provide significant insights but have some important limitations; efforts are needed to integrate them with other approaches to make full use of the sequencing data deluge. An international conference 'Advances in Ecological Speciation' organized by the University of Porto (Portugal) aimed to review current progress in ecological speciation. Using some of the examples presented at the conference, we highlight the benefits of integrating ecological and genomic data and discuss different mechanisms of parallel evolution. Finally, future avenues of research are suggested to advance our knowledge concerning the role of natural selection in the establishment of reproductive isolation during ecological speciation.

  17. Review of pipe-break probability assessment methods and data for applicability to the advanced neutron source project for Oak Ridge National Laboratory

    SciTech Connect

    Fullwood, R.R.

    1989-04-01

    The Advanced Neutron Source (ANS) (Difilippo, 1986; Gamble, 1986; West, 1986; Selby, 1987) will be the world's best facility for low energy neutron research. This performance requires the highest flux density of all non-pulsed reactors with concomitant low thermal inertial and fast response to upset conditions. One of the primary concerns is that a flow cessation of the order of a second may result in fuel damage. Such a flow stoppage could be the result of break in the primary piping. This report is a review of methods for assessing pipe break probabilities based on historical operating experience in power reactors, scaling methods, fracture mechanics and fracture growth models. The goal of this work is to develop parametric guidance for the ANS design to make the event highly unlikely. It is also to review and select methods that may be used in an interactive IBM-PC model providing fast and reasonably accurate models to aid the ANS designers in achieving the safety requirements. 80 refs., 7 figs.

  18. An angular dependent neutron effective-dose-equivalent dosimeter

    NASA Astrophysics Data System (ADS)

    Veinot, Kenneth Guy

    The effective-dose-equivalent (EDE) is a strong function of angular orientation in a radiation field. Detection systems that attempt to measure the EDE directly would be desirable. Historically, dosimeters have been designed to respond as isotropically as possible in a radiation field. However, since the EDE is strongly dependent upon the incident angle of the radiation, past designs are no longer desirable for personal radiation dosimetry. In addition, the EDE is a function of incident neutron energy. CR-39 foils are commonly used neutron detectors. Neutrons produce tracks in CR-39 (allyl diglycol polycarbonate) detectors over a wide energy range. Through chemical or electrochemical etching, these tracks can be enlarged and counted. From this track count, the fluence of neutrons incident on the CR-39 foils may be inferred. Thermoluminescent dosimeters (TLDs) are another method of neutron detection. Both of these detectors have angular response properties. In the present work, calculations of EDE were compared to calculations and measurements of the angular responses of CR-39 and TLD neutron dosimeters. The measurements used a variety of neutron sources, each with its own characteristic energy spectrum. This research resulted in a neutron personal dosimeter prototype whose angular response properties resembled the angular response of EDE.

  19. Inspection of an artificial heart by the neutron radiography technique

    NASA Astrophysics Data System (ADS)

    Pugliesi, R.; Geraldo, L. P.; Andrade, M. L. G.; Menezes, M. O.,; Pereira, M. A. S.; Maizato, M. J. S.

    1999-11-01

    The neutron radiography technique was employed to inspect an artificial heart prototype which is being developed to provide blood circulation for patients expecting heart transplant surgery. The radiographs have been obtained by the direct method with a gadolinium converter screen along with the double coated Kodak-AA emulsion film. The artificial heart consists of a flexible plastic membrane located inside a welded metallic cavity, which is employed for blood pumping purposes. The main objective of the present inspection was to identify possible damages in this plastic membrane, produced during the welding process of the metallic cavity. The obtained radiographs were digitized as well as analysed in a PC and the improved images clearly identify several damages in the plastic membrane, suggesting changes in the welding process.

  20. Recent advancements of wide-angle polarization analysis with 3He neutron spin filters

    NASA Astrophysics Data System (ADS)

    Chen, W. C.; Gentile, T. R.; Ye, Q.; Kirchhoff, A.; Watson, S. M.; Rodriguez-Rivera, J. A.; Qiu, Y.; Broholm, C.

    2016-09-01

    Wide-angle polarization analysis with polarized 3He based neutron spin filters (NSFs) has recently been employed on the Multi-Axis Crystal Spectrometer (MACS) at the National Institute of Standards and Technology Center for Neutron Research (NCNR). Over the past several years, the apparatus has undergone many upgrades to address the fundamental requirements for wide angle polarization analysis using spin exchange optical pumping based 3He NSFs. In this paper, we report substantial improvements in the on-beam-line performance of the apparatus and progress toward routine user capability. We discuss new standard samples used for 3He NSF characterization and the flipping ratio measurement on MACS. We further discuss the management of stray magnetic fields produced by operation of superconducting magnets on the MACS instrument, which can significantly reduce the 3He polarization relaxation time. Finally, we present the results of recent development of horseshoe-shaped wide angle cells.

  1. 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.

  2. Terahertz, X-ray and neutron computed tomography of an Eighteenth Dynasty Egyptian sealed pottery

    NASA Astrophysics Data System (ADS)

    Abraham, E.; Bessou, M.; Ziéglé, A.; Hervé, M.-C.; Szentmiklósi, L.; Kasztovszky, Z. S.; Kis, Z.; Menu, M.

    2014-09-01

    An Eighteenth Dynasty Egyptian sealed pottery stored at the Museum of Aquitaine (Bordeaux, France) has been investigated using terahertz radiation, X-rays and neutrons. THz computed tomography revealed nondestructively the presence of content, whereas X-rays and neutrons analyzed more precisely the fabrication process and conservation of the pottery together with the nature of this content owing to higher spatial resolution and contrast. With neutron tomography, we determined the method used to seal the jar as well as the finer structure of the inner content. Neutron-induced prompt gamma spectroscopy was finally applied to measure the elemental composition of the content, which is supposed to consist of dried germinated seeds.

  3. Lightweight concrete with enhanced neutron shielding

    DOEpatents

    Brindza, Paul Daniel; Metzger, Bert Clayton

    2016-09-13

    A lightweight concrete containing polyethylene terephthalate in an amount of 20% by total volume. The concrete is enriched with hydrogen and is therefore highly effective at thermalizing neutrons. The concrete can be used independently or as a component of an advanced neutron radiation shielding system.

  4. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  5. Atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

    1979-01-01

    Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

  6. Neutron dosimetry

    DOEpatents

    Quinby, Thomas C.

    1976-07-27

    A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

  7. Advanced neutron source reactor conceptual safety analysis report, three-element-core design: Chapter 15, accident analysis

    SciTech Connect

    Chen, N.C.J.; Wendel, M.W.; Yoder, G.L.; Harrington, R.M.

    1996-02-01

    In order to utilize reduced enrichment fuel, the three-element-core design for the Advanced Neutron Source has been proposed. The proposed core configuration consists of inner, middle, and outer elements, with the middle element offset axially beneath the inner and outer elements, which are axially aligned. The three-element-core RELAP5 model assumes that the reactor hardware is changed only within the core region, so that the loop piping, heat exchangers, and pumps remain as assumed for the two-element-core configuration. To assess the impact of changes in the core region configuration and the thermal-hydraulic steady-state conditions, the safety analysis has been updated. This report gives the safety margins for the loss-of-off-site power and pressure-boundary fault accidents based on the RELAP5 results. AU margins are greater for the three-element-core simulations than those calculated for the two-element core.

  8. Total parenteral nutrition, An important therapeutic advance.

    PubMed

    Hodges, R E

    1979-03-01

    Total parenteral nutrition (TPN) is a potent form of therapy. It is particularly useful in patients who must undergo surgery or those with conditions that preclude normal feeding. The procedure is not without risk, but better understanding of the basic principles involved, refinements in technique, and experience with its use in different situations have combined to improve the results of therapy over those first obtained. TPN represents an important therapeutic advance and emphasizes the need for an undertanding of nutritional principles by physicians and for a team approach to the management of complicated conditions.

  9. Dosimetry measurements of x-ray and neutron radiation levels near the shuttle and end beam dump at the advanced test accelerator: Beam Research Program

    SciTech Connect

    Gibson, T.A. Jr.; Struve, K.W.; Lindgren, R.A.

    1987-01-01

    Electron beams as a source of directed energy are under study at the Lawrence Livermore National Laboratory (LLNL). An intense 10-kA, 50-MeV, 50-ns full-width half-maximum, pulsed electron beam is generated by the prototype Advanced Test Accelerator (ATA) at the Laboratory's Site 300. Whenever the electron beam is stopped in materials, intense radiation is generated. Estimates based on available data in the literature show that for materials such as lead, photon radiation (x ray, gamma, bremsstrahlung) levels can be as large as 10/sup 4/ roentgens per pulse at 1 m in the zero-degree direction (i.e., the electron-beam direction). Neutrons, which are emitted isotropically, are produced at a level of 10/sup 13/ n/m/sup 2/ per pulse. Depending upon the number of pulses and the shielding geometry, the accumulated dose is potentially lethal to personnel and potentially damaging to instrumentation that may be used for diagnostics. To provide shielding for minimizing the risk of exposure to personnel and radiation damage to instrumentation, it is important to determine the x-ray and neutron radiation environment near beamline components such as the beam shuttle dump and beam stop. Photon and neutron dosimetry measurements were performed around the beam shuttle dump on January 9, 1985, and near the carbon beam stop at the end of the beamline before the entrance to the diagnostic tunnel on April 12 and December 23, 1985. These measurements together with simple rule-of-thumb estimates and Monte Carlo electron-photon shower calculations of the absorbed dose are presented in this report. 17 refs., 14 figs., 13 tabs.

  10. Plan for the future of neutron research on condensed matter: an Argonne National Laboratory report prepared in response to the Report of the Review Panel on Neutron Scattering

    SciTech Connect

    1981-01-27

    The Review Panel on Neutron Scattering has recommended an expanded budget to allow systematic development of the field. An alternative plan for the future of neutron research on condensed matter is presented here, in case it is not possible to fund the expanded budget. This plan leads, in a rational and logical way, to a world-class neutron source that will ensure the vitality of the field and exploit the many benefits that state-of-the-art neutron facilities can bring to programs in the materials and biological sciences. 2 tables. (RWR)

  11. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    SciTech Connect

    Mitchell, H.E.

    1996-04-01

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10{sup 7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF{sub 3} composite and a stacked Al/Teflon design) at various incident electron energies.

  12. An evaluated neutronic data file for elemental cobalt

    SciTech Connect

    Guenther, P.; Lawson, R.; Meadows, J.; Sugimoto, M.; Smith, A.; Smith, D.; Howerton, R.

    1988-08-01

    A comprehensive evaluated neutronic data file for elemental cobalt is described. The experimental data base, the calculational methods, the evaluation techniques and judgments, and the physical content are outlined. The file contains: neutron total and scattering cross sections and associated properties, (n,2n) and (n,3n) processes, neutron radiative capture processes, charged-particle-emission processes, and photon-production processes. The file extends from 10/sup /minus/5/ eV to 20 MeV, and is presented in the ENDF/B-VI format. Detailed attention is given to the uncertainties and correlations associated with the prominent neutron-induced processes. The numerical contents of the file have been transmitted to the National Nuclear Data Center, Brookhaven National Laboratory. 143 refs., 16 figs., 5 tabs.

  13. Nuclear and dosimetric features of an isotopic neutron source

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, H. R.; Hernández-Dávila, V. M.; Rivera, T.; Sánchez, A.

    2014-02-01

    A multisphere neutron spectrometer was used to determine the features of a 239PuBe neutron source that is used to operate the ESFM-IPN Subcritical Reactor. To determine the source main features it was located a 100 cm from the spectrometer which was a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter polyethylene spheres. Count rates obtained with the spectrometer were unfolded using the NSDUAZ code and neutron spectrum, total fluence, and ambient dose equivalent were determined. A Monte Carlo calculation was carried out to estimate the spectrum and integral features being less than values obtained experimentally due to the presence of 241Pu in the Pu used to fabricate the source. Actual neutron yield and the mass fraction of 241Pu was estimated.

  14. Neutron Energy Measurements in Radiological Emergency Response Applications

    SciTech Connect

    Sanjoy Mukhopadhyay, Paul Guss, Michael Hornish, Scott Wilde, Tom Stampahar, Michael Reed

    2009-04-30

    We present significant results in recent advances in the determination of neutron energy. Neutron energy measurements are a small but very significant part of radiological emergency response applications. Mission critical information can be obtained by analyzing the neutron energy given off from radioactive materials. In the case of searching for special nuclear materials, neutron energy information from an unknown source can be of paramount importance.

  15. Studies on the properties of an epithermal-neutron hydrogen analyzer.

    PubMed

    Papp, A; Csikai, J

    2010-09-01

    Systematic investigations have proved the advantages of the Epithermal Neutron Analyzer (ETNA) for bulk hydrogen analysis as compared to the thermal neutron techniques. Results can contribute, for example, to the design and construction of instruments needed for the detection and identification of plastic anti-personnel landmines, explosives hidden in airline baggage and cargo containers via hydrogen contents as an indicator of their presence.

  16. Technological Advances in Psychiatric Nursing: An update.

    PubMed

    Bostrom, Andrea C

    2016-06-01

    Understanding and treating mental illness has improved in many ways as a result of the fast pace of technological advances. The technologies that have the greatest potential impact are those that (1) increase the knowledge of how the brain functions and changes based on interventions, (2) have the potential to personalize interventions based on understanding genetic factors of drug metabolism and pharmacodynamics, and (3) use information technology to provide treatment in the absence of an adequate mental health workforce. Technologies are explored for psychiatric nurses to consider. Psychiatric nurses are encouraged to consider the experiences of psychiatric patients, including poor health, stigmatization, and suffering.

  17. Advances in neural networks research: an introduction.

    PubMed

    Kozma, Robert; Bressler, Steven; Perlovsky, Leonid; Venayagamoorthy, Ganesh Kumar

    2009-01-01

    The present Special Issue "Advances in Neural Networks Research: IJCNN2009" provides a state-of-art overview of the field of neural networks. It includes 39 papers from selected areas of the 2009 International Joint Conference on Neural Networks (IJCNN2009). IJCNN2009 took place on June 14-19, 2009 in Atlanta, Georgia, USA, and it represents an exemplary collaboration between the International Neural Networks Society and the IEEE Computational Intelligence Society. Topics in this issue include neuroscience and cognitive science, computational intelligence and machine learning, hybrid techniques, nonlinear dynamics and chaos, various soft computing technologies, intelligent signal processing and pattern recognition, bioinformatics and biomedicine, and engineering applications. PMID:19632811

  18. Advances in neural networks research: an introduction.

    PubMed

    Kozma, Robert; Bressler, Steven; Perlovsky, Leonid; Venayagamoorthy, Ganesh Kumar

    2009-01-01

    The present Special Issue "Advances in Neural Networks Research: IJCNN2009" provides a state-of-art overview of the field of neural networks. It includes 39 papers from selected areas of the 2009 International Joint Conference on Neural Networks (IJCNN2009). IJCNN2009 took place on June 14-19, 2009 in Atlanta, Georgia, USA, and it represents an exemplary collaboration between the International Neural Networks Society and the IEEE Computational Intelligence Society. Topics in this issue include neuroscience and cognitive science, computational intelligence and machine learning, hybrid techniques, nonlinear dynamics and chaos, various soft computing technologies, intelligent signal processing and pattern recognition, bioinformatics and biomedicine, and engineering applications.

  19. Technology advancement of an oxygen generation subsystem

    NASA Technical Reports Server (NTRS)

    Lee, M. K.; Burke, K. A.; Schubert, F. H.; Wynveen, R. A.

    1979-01-01

    An oxygen generation subsystem based on water electrolysis was developed and tested to further advance the concept and technology of the spacecraft air revitalization system. Emphasis was placed on demonstrating the subsystem integration concept and hardware maturity at a subsystem level. The integration concept of the air revitalization system was found to be feasible. Hardware and technology of the oxygen generation subsystem was demonstrated to be close to the preprototype level. Continued development of the oxygen generation technology is recommended to further reduce the total weight penalties of the oxygen generation subsystem through optimization.

  20. NEUTRON ACTIVATION ANALYSIS APPLICATIONS AT THE SAVANNAH RIVER SITE USING AN ISOTOPIC NEUTRON SOURCE

    SciTech Connect

    Diprete, D; C Diprete, C; Raymond Sigg, R

    2006-08-14

    NAA using {sup 252}Cf is used to address important areas of applied interest at SRS. Sensitivity needs for many of the applications are not severe; analyses are accomplished using a 21 mg {sup 252}Cf NAA facility. Because NAA allows analysis of bulk samples, it offers strong advantages for samples in difficult-to-digest matrices when its sensitivity is sufficient. Following radiochemical separation with stable carrier addition, chemical yields for a number methods are determined by neutron activation of the stable carrier. In some of the cases where no suitable stable carriers exist, the source has been used to generate radioactive tracers to yield separations.

  1. Development of an advanced electromagnetic gun barrel

    NASA Astrophysics Data System (ADS)

    Hurn, T. W.; D'Aoust, J.; Sevier, L.; Johnson, R.; Wesley, J.

    1993-01-01

    An advanced EM gun (AEMG) barrel was developed for the USAF Wright Laboratory to repetitively accelerate large-mass projectiles. The AEMG barrel employed 5-m rails, had a 50 mm square bore, and was designed to operate at a peak current of 1.5 MA (bore pressure 25 ksi). Key technical achievements included (1) an efficient barrel containment structure that weighs approximately 25 percent of a similarly rated clamped barrel, (2) an insulator material that retains surface resistivity after repeated firings, and (3) a high-velocity water cooling system designed to remove a peak heat flux of 5 MJ/sq m per shot. The AEMG barrel's thermal management system employed a 500 psi blowdown system that generated high velocity coolant flow rates in five axial coolant channels within each rail. Innovative fabrication processes were used to develop the barrel. A 2-m prototype of the AEMG barrel was tested in the General Atomics 4 MJ EM launcher test facility.

  2. Low-level measuring techniques for neutrons: High accuracy neutron source strength determination and fluence rate measurement at an underground laboratory

    SciTech Connect

    Zimbal, Andreas; Reginatto, Marcel; Schuhmacher, Helmut; Wiegel, Burkhard; Degering, Detlev; Zuber, Kai

    2013-08-08

    We report on measuring techniques for neutrons that have been developed at the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. PTB has characterized radioactive sources used in the BOREXINO and XENON100 experiments. For the BOREXINO experiment, a {sup 228}Th gamma radiation source was required which would not emit more than 10 neutrons per second. The determination of the neutron emission rate of this specially designed {sup 228}Th source was challenging due to the low neutron emission rate and because the ratio of neutron to gamma radiation was expected to be extremely low, of the order of 10{sup −6}. For the XENON100 detector, PTB carried out a high accuracy measurement of the neutron emission rate of an AmBe source. PTB has also done measurements in underground laboratories. A two month measurement campaign with a set of {sup 3}He-filled proportional counters was carried out in PTB's former UDO underground laboratory at the Asse salt mine. The aim of the campaign was to determine the intrinsic background of detectors, which is needed for the analysis of data taken in lowintensity neutron fields. At a later time, PTB did a preliminary measurement of the neutron fluence rate at the underground laboratory Felsenkeller operated by VKTA. By taking into account data from UDO, Felsenkeller, and detector calibrations made at the PTB facility, it was possible to estimate the neutron fluence rate at the Felsenkeller underground laboratory.

  3. Thermal and Cold Neutron Computed Tomography at the Los Alamos Neutron Scattering Center Using an Amorphous Silicon Detector Array

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Farnum, E.H.; McDonald, T.E.; Summa, D.A.; Sheats, M.J.; Stupin, D.M.; Sievers, W.L.

    1998-07-19

    The use of the EG and G-Heimann RTM 128 or dpiX FS20 amorphous silicon (a-Si) detector array for thermal neutron radiography/computed tomography has proven to be a quick and efficient means of producing high quality digital radiographic images. The resolution, although not as good as film, is about 750 pm with the RTM and 127 pm with the dpiX array with a dynamic range in excess of 2,800. In many respects using an amorphous silicon detector is an improvement over other techniques such as imaging with a CCD camera, using a storage phosphor plate or film radiography. Unlike a CCD camera, which is highly susceptible to radiation damage, a-Si detectors can be placed in the beam directly behind the object under examination and do not require any special optics or turning mirrors. The amorphous silicon detector also allows enough data to be acquired to construct a digital image in just a few seconds (minimum gate time 40 ms) whereas film or storage plate exposures can take many minutes and then need to be digitized with a scanner. The flat panel can therefore acquire a complete 3D computed tomography data set in just a few tens of minutes. While a-Si detectors have been proposed for use in imaging neutron beams, this is the first reported implementation of such a detector for neutron imaging.

  4. MCViNE- An object oriented Monte Carlo neutron ray tracing simulation package

    DOE PAGESBeta

    Lin, J. Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry L.; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2015-11-28

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiplemore » scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. As a result, with simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.« less

  5. MCViNE - An object oriented Monte Carlo neutron ray tracing simulation package

    NASA Astrophysics Data System (ADS)

    Lin, Jiao Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2016-02-01

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. With simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.

  6. MCViNE- An object oriented Monte Carlo neutron ray tracing simulation package

    SciTech Connect

    Lin, J. Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry L.; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2015-11-28

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. As a result, with simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.

  7. Requirements for an Advanced Ocean Radiometer

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard; McClain, Charles R.; Ahmad, Ziauddin; Bailey, Sean W.; Barnes, Robert A.; Brown, Steven; Eplee, Robert E.; Franz, Bryan; Holmes, Alan; Monosmith, W. Bryan; Patt, Frederick S.; Stumpf, Richard P.; Turpie, Kevin R.; Werdell, P. Jeremy

    2011-01-01

    This document suggests requirements for an advanced ocean radiometer, such as e.g. the ACE (Aerosol/Cloud/Ecosystem) ocean radiometer. The ACE ocean biology mission objectives have been defined in the ACE Ocean Biology white paper. The general requirements presented therein were chosen as the basis for the requirements provided in this document, which have been transformed into specific, testable requirements. The overall accuracy goal for the advanced ocean radiometer is that the total radiometric uncertainties are 0.5% or smaller for all bands. Specific mission requirements of SeaWiFS, MODIS, and VIIRS were often used as a model for the requirements presented here, which are in most cases more demanding than the heritage requirements. Experience with on-orbit performance and calibration (from SeaWiFS and MODIS) and prelaunch testing (from SeaWiFS, MODIS, and VIIRS) were important considerations when formulating the requirements. This document describes requirements in terms of the science data products, with a focus on qualities that can be verified by prelaunch radiometric characterization. It is expected that a more comprehensive requirements document will be developed during mission formulation

  8. Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced fission reactions on {sup 239}Pu

    SciTech Connect

    Talou, P.; Kawano, T.; Becker, B.; Danon, Y.; Chadwick, M. B.

    2011-06-15

    Prompt fission neutrons following the thermal and 0.5 MeV neutron-induced fission reaction of {sup 239}Pu are calculated using a Monte Carlo approach to the evaporation of the excited fission fragments. Exclusive data such as the multiplicity distribution P({nu}), the average multiplicity as a function of fragment mass {nu}-bar(A), and many others are inferred in addition to the most used average prompt fission neutron spectrum {chi}(E{sub in},E{sub out}), as well as average neutron multiplicity {nu}-bar. Experimental information on these more exclusive data help constrain the Monte Carlo model parameters. The calculated average total neutron multiplicity is {nu}-bar{sub c}=2.871 in very close agreement with the evaluated value {nu}-bar{sub e}=2.8725 present in the ENDF/B-VII.0 library. The neutron multiplicity distribution P({nu}) is in very good agreement with the evaluation by Holden and Zucker. The calculated average spectrum differs in shape from the ENDF/B-VII.0 spectrum, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail of the spectrum (below about 300 keV) than the Madland-Nix calculations, casting some doubts on how much scission neutrons contribute to the shape of the low-energy tail of the spectrum. The spectrum high-energy tail is very sensitive to the total kinetic energy distribution of the fragments as well as to the total excitation energy sharing at scission. Present experimental uncertainties on measured spectra above 6 MeV are too large to distinguish between various theoretical hypotheses. Finally, comparisons of the Monte Carlo results with experimental data on {nu}-bar(A) indicate that more neutrons are emitted from the light fragments than the heavy ones, in agreement with previous works.

  9. Hypersonic characteristics of an advanced aerospace plane

    NASA Technical Reports Server (NTRS)

    Mccandless, R. S.; Cruz, C. I.

    1985-01-01

    A series of hypersonic wind-tunnel tests have been conducted in the NASA Langley Hypersonic Facilities Complex to obtain the static longitudinal and lateral-directional aerodynamic characteristics of an advanced aerospace plane. Data were obtained at 0 to 20 deg angles of attack and -3 to 3 deg angles of sideslip at Mach numbers of 6 and 10 in air and 20 in helium. Results show that stable trim capability exists at angles of attack near maximum lift-drag ratio (L/D). Both performance and stability exhibited some Mach number dependency. The vehicle was longitudinally unstable at low angles of attack but stable at angles of attack near and above maximum L/D. It was directionally unstable with positive dihedral effect. The rudder showed an inability to provide lateral-directional control, and removing the vertical tail resulted in increased directional instability. Analytical predictions of the static longitudinal aerodynamic coefficients gave relatively good comparisons with the experimental data.

  10. An advanced terrain modeler for an autonomous planetary rover

    NASA Technical Reports Server (NTRS)

    Hunter, E. L.

    1980-01-01

    A roving vehicle capable of autonomously exploring the surface of an alien world is under development and an advanced terrain modeler to characterize the possible paths of the rover as hazardous or safe is presented. This advanced terrain modeler has several improvements over the Troiani modeler that include: a crosspath analysis, better determination of hazards on slopes, and methods for dealing with missing returns at the extremities of the sensor field. The results from a package of programs to simulate the roving vehicle are then examined and compared to results from the Troiani modeler.

  11. Neutron reflecting supermirror structure

    DOEpatents

    Wood, J.L.

    1992-12-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

  12. Neutron reflecting supermirror structure

    DOEpatents

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

  13. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    PubMed Central

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources. PMID:25589504

  14. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy.

    PubMed

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-03-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 10(5) n/cm(2)/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources.

  15. Characterization and quantification of an in-core neutron irradiation facility at a TRIGA II research reactor

    NASA Astrophysics Data System (ADS)

    Aghara, Sukesh; Charlton, William

    2006-07-01

    Experiments have been performed to characterize the neutron environment at an in-core TRIGA type nuclear research reactor. Steady-state thermal and epithermal neutron environment testing is important for many applications including, materials, electronics and biological cells. A well characterized neutron environment at a research reactor, including energy spectrum and spatial distribution, can be useful to many research communities and for educational research. This paper describes the characterization process and an application of exposing electronics to high neutron fluence.

  16. Some properties of an advanced boron fiber

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.

    1979-01-01

    An advanced coreless boron fiber has exhibited tensile strengths which are more than twice that of the normal CVD B/W fibers. The coreless fiber is made by the chemical removal of the tungsten boride core exposed by splitting the as-grown fiber. The easily splittable fiber is made by the chemical vapor deposition of boron on a larger than usual tungsten substrate. It is expected that the ease of splitting is related to residual stresses in these fibers. Measurements of the axial residual stresses in both the normal and the splittable fibers are presented and the results compared. Differences in these stresses are discussed in connection with the ease of splitting in the splittable fibers.

  17. An advanced domestic satellite communications system

    NASA Technical Reports Server (NTRS)

    1980-01-01

    An updated traffic projection for U.S. domestic satellite communications service covering a period of 15 years; mid-1980 to mid-1995 was prepared. This model takes into account expected technology advances and reductions in transmission costs, legislative and regulatory changes permitting increased competition, and rising energy costs which will encourage more extensive substitution of telecommunications for travel. The historical development and current status of satellite systems are discussed as well as the characteristics of follow-on systems. Orbital arc utilization, spacecraft configuration for single shuttle launch, Earth station configuration, and system costs are examined. Areas which require technology development include multiple beam frequency reuse antennas, on-board switching, intersatellite links, and ka-band operation. Packing and deployment schemes for enclosing the satellite within the shuttle orbiter bay must also be devised.

  18. An advanced arc track resistant airframe wire

    NASA Astrophysics Data System (ADS)

    Beatty, J.

    1995-11-01

    Tensolite, a custom cable manufacturer specializing in high temperature materials as the dielectric medium, develops an advance arc track resistant airframe wire called Tufflite 2000. Tufflite 2000 has the following advantages over the other traditional wires: lighter weight and smaller in diameter; excellent wet and dry arc track resistance; superior dynamic cut-through performance even at elevated temperatures; flight proven performance on Boeing 737 and 757 airplanes; and true 260 C performance by utilizing Nickel plated copper conductors. This paper reports the different tests performed on Tufflite 2000: accelerated aging, arc resistance (wet and dry), dynamic cut through, humidity resistance, wire-to-wire abrasion, flammability, smoke, weight, notch sensitivity, flexibility, and markability. It particularly focuses on the BSI (British Standards Institute) dry arc resistance test and BSI wet arc tracking.

  19. An advanced arc track resistant airframe wire

    NASA Technical Reports Server (NTRS)

    Beatty, J.

    1995-01-01

    Tensolite, a custom cable manufacturer specializing in high temperature materials as the dielectric medium, develops an advance arc track resistant airframe wire called Tufflite 2000. Tufflite 2000 has the following advantages over the other traditional wires: lighter weight and smaller in diameter; excellent wet and dry arc track resistance; superior dynamic cut-through performance even at elevated temperatures; flight proven performance on Boeing 737 and 757 airplanes; and true 260 C performance by utilizing Nickel plated copper conductors. This paper reports the different tests performed on Tufflite 2000: accelerated aging, arc resistance (wet and dry), dynamic cut through, humidity resistance, wire-to-wire abrasion, flammability, smoke, weight, notch sensitivity, flexibility, and markability. It particularly focuses on the BSI (British Standards Institute) dry arc resistance test and BSI wet arc tracking.

  20. Implementation of an Analytical Model for Leakage Neutron Equivalent Dose in a Proton Radiotherapy Planning System

    PubMed Central

    Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

    2015-01-01

    Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects. PMID:25768061

  1. Characterization of an explosively bonded aluminum proton beam window for the Spallation Neutron Source

    SciTech Connect

    McClintock, David A; Janney, Jim G; Parish, Chad M

    2014-01-01

    An effort is underway at the Spallation Neutron Source (SNS) to change the design of the 1st Generation high-nickel alloy proton beam window (PBW) to one that utilizes aluminum for the window material. One of the key challenges to implementation of an aluminum PBW at the SNS was selection of an appropriate joining method to bond an aluminum window to the stainless steel bulk shielding of the PBW assembly. An explosively formed bond was selected as the most promising joining method for the aluminum PBW design. A testing campaign was conducted to evaluate the strength and efficacy of explosively formed bonds that were produced using two different interlayer materials: niobium and titanium. The characterization methods reported here include tensile testing, thermal-shock leak testing, optical microscopy, and advanced scanning electron microscopy. All tensile specimens examined failed in the aluminum interlayer and measured tensile strengths were all slightly greater than the native properties of the aluminum interlayer, while elongation values were all slightly lower. A leak developed in the test vessel with a niobium interlayer joint after repeated thermal-shock cycles, and was attributed to an extensive crack network that formed in a layer of niobium-rich intermetallics located on the bond interfaces of the niobium interlayer; the test vessel with a titanium interlayer did not develop a leak under the conditions tested. Due to the experience gained from these characterizations, the explosively formed bond with a titanium interlayer was selected for the aluminum PBW design at the SNS.

  2. Advanced optics in an interdisciplinary graduate program

    NASA Astrophysics Data System (ADS)

    Nic Chormaic, S.

    2014-07-01

    The Okinawa Institute of Science and Technology Graduate University, established in November 2011, provides a 5- year interdisciplinary PhD program, through English, within Japan. International and Japanese students entering the program undertake coursework and laboratory rotations across a range of topics, including neuroscience, molecular science, physics, chemistry, marine science and mathematics, regardless of previous educational background. To facilitate interdisciplinarity, the university has no departments, ensuring seamless interactions between researchers from all sectors. As part of the PhD program a course in Advanced Optics has been developed to provide PhD students with the practical and theoretical skills to enable them to use optics tools in any research environment. The theoretical aspect of the course introduces students to procedures for complex beam generation (e.g. Laguerre-Gaussian), optical trapping, beam analysis and photon optics, and is supported through a practical program covering introductory interference/diffraction experiments through to more applied fiber optics. It is hoped that, through early exposure to optics handling and measurement techniques, students will be able to develop and utilize optics tools regardless of research field. In addition to the formal course in Advanced Optics, a selection of students also undertakes 13 week laboratory rotations in the Light-Matter Interactions research laboratory, where they work side-by-side with physicists in developing optics tools for laser cooling, photonics or bio-applications. While currently in the first year, conclusive results about the success of such an interdisciplinary PhD training are speculative. However, initial observations indicate a rich cross-fertilization of ideas stemming from the diverse backgrounds of all participants.

  3. An apparatus for studying spallation neutrons in the Aberdeen Tunnel laboratory

    NASA Astrophysics Data System (ADS)

    Blyth, S. C.; Chan, Y. L.; Chen, X. C.; Chu, M. C.; Hahn, R. L.; Ho, T. H.; Hsiung, Y. B.; Hu, B. Z.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Lau, Y. P.; Lee, K. P.; Leung, J. K. C.; Leung, K. Y.; Lin, G. L.; Lin, Y. C.; Luk, K. B.; Luk, W. H.; Ngai, H. Y.; Ngan, S. Y.; Pun, C. S. J.; Shih, K.; Tam, Y. H.; Tsang, R. H. M.; Wang, C. H.; Wong, C. M.; Wong, H. L.; Wong, H. H. C.; Wong, K. K.; Yeh, M.

    2013-09-01

    In this paper, we describe the design, construction and performance of an apparatus installed in the Aberdeen Tunnel laboratory in Hong Kong for studying spallation neutrons induced by cosmic-ray muons under a vertical rock overburden of 611 m water equivalent (m.w.e.). The apparatus comprises six horizontal layers of plastic-scintillator hodoscopes for determining the direction and position of the incident cosmic-ray muons. Sandwiched between the hodoscope planes is a neutron detector filled with 650 kg of liquid scintillator doped with about 0.06% of Gadolinium by weight for improving the efficiency of detecting the spallation neutrons. Performance of the apparatus is also presented.

  4. Cold neutron prompt gamma-ray activation analysis at NIST - an overview

    SciTech Connect

    Paul, R.L.; Lindstrom, R.M.

    1994-12-31

    An instrument for cold neutron capture prompt gamma-ray activation analysis (CNPGAA), located in the cold neutron research facility (CNRF) at the National Institute of Standards and Technology (NIST) has proven useful for the analysis of hydrogen and other elements in a wide variety of materials. The intent of this paper is to provide an overview of the instrument, focusing on recent improvements and the impact of these improvement on measurements.

  5. Spallation Neutron Source reaches megawatt power

    SciTech Connect

    Dr. William F. Brinkman

    2009-09-30

    The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

  6. Spallation Neutron Source reaches megawatt power

    ScienceCinema

    Dr. William F. Brinkman

    2016-07-12

    The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

  7. An epithermal neutron source for BNCT based on an ESQ-accelerator

    SciTech Connect

    Ludewigt, B.A.; Chu, W.T.; Donahue, R.J.; Kwan, J.; Phillips, T.L.; Reginato, L.L.; Wells, R.P.

    1997-07-01

    An accelerator-based BNCT facility is under development at the Lawrence Berkeley National Laboratory. Neutrons will be produced via the {sup 7}Li(p,n) reaction at proton energies of about 2.5 MeV with subsequent moderation and filtering for shaping epithermal neutron beams for BNCT. Moderator, filter, and shielding assemblies have been modeled using MCNP. Head-phantom dose distributions have been calculated using the treatment planning software BNCT{_}RTPE. The simulation studies have shown that a proton beam current of {approximately} 20 mA is required to deliver high quality brain treatments in about 40 minutes. The results also indicate that significantly higher doses can be delivered to deep-seated tumors in comparison to the Brookhaven Medical Research Reactor beam. An electrostatic quadrupole (ESQ) accelerator is ideally suited to provide the high beam currents desired. A novel power supply utilizing the air-coupled transformer concept is under development. It will enable the ESQ-accelerator to deliver proton beam currents exceeding 50 mA. A lithium target has been designed which consists of a thin layer of lithium on an aluminum backing. Closely spaced, narrow coolant passages cut into the aluminum allow the removal of a 50kW heat-load by convective water cooling. The system under development is suitable for hospital installation and has the potential for providing neutron beams superior to reactor sources.

  8. An Advanced Buffet Load Alleviation System

    NASA Technical Reports Server (NTRS)

    Burnham, Jay K.; Pitt, Dale M.; White, Edward V.; Henderson, Douglas A.; Moses, Robert W.

    2001-01-01

    This paper describes the development of an advanced buffet load alleviation (BLA) system that utilizes distributed piezoelectric actuators in conjunction with an active rudder to reduce the structural dynamic response of the F/A-18 aircraft vertical tails to buffet loads. The BLA system was defined analytically with a detailed finite-element-model of the tail structure and piezoelectric actuators. Oscillatory aerodynamics were included along with a buffet forcing function to complete the aeroservoelastic model of the tail with rudder control surface. Two single-input-single-output (SISO) controllers were designed, one for the active rudder and one for the active piezoelectric actuators. The results from the analytical open and closed loop simulations were used to predict the system performance. The objective of this BLA system is to extend the life of vertical tail structures and decrease their life-cycle costs. This system can be applied to other aircraft designs to address suppression of structural vibrations on military and commercial aircraft.

  9. Plans for an Ultra Cold Neutron source at Los Alamos

    SciTech Connect

    Seestrom, S.J.; Bowles, T.J.; Hill, R.; Greene, G.L.

    1996-10-01

    Ultra Cold Neutrons (UCN) can be produced at spallation sources using a variety of techniques. To date the technique used has been to Bragg scatter and Doppler shift cold neutrons into UCN from a moving crystal. This is particularly applicable to short-pulse spallation sources. We are presently constructing a UCN source at LANSCE using this method. In addition, large gains in UCN density should be possible using cryogenic UCN sources. Research is under way at Gatchina to demonstrate technical feasibility of a frozen deuterium source. If successful, a source of this type could be implemented at future spallation source, such as the long pulse source being planned at Los Alamos, with a UCN density that may be two orders of magnitude higher than that presently available at reactors.

  10. Development of an ultra cold neutron source at MLNSC

    SciTech Connect

    Seestrom, S.J.; Bowles, T.J.; Hill, R.; Greene, G.L.; Morris, C.L.

    1996-09-01

    Ultra Cold Neutrons (UCN) can be produced at spallation sources using a variety of techniques. To date the technique used has been to Bragg scatter and Doppler shift cold neutrons into UCN from a moving crystal. This is particularly applicable to short-pulse spallation sources. We are presently constructing a UCN source at LANSCE using this method. In addition, large gains in UCN density should be possible using cryogenic UCN sources. Research is under way at Gatchina to demonstrate technical feasibility of a frozen deuterium source. If successful, a source of this type could be implemented at future spallation sources, such as the long pulse source being planned at Los Alamos, with a UCN density that may be two orders of magnitude higher than that presently available at reactors.

  11. Benchmarking of activation reaction distribution in an intermediate energy neutron field.

    PubMed

    Ogawa, Tatsuhiko; Morev, Mikhail N; Hirota, Masahiro; Abe, Takuya; Koike, Yuya; Iwai, Satoshi; Iimoto, Takeshi; Kosako, Toshiso

    2011-07-01

    Neutron-induced reaction rate depth profiles inside concrete shield irradiated by intermediate energy neutron were calculated using a Monte-Carlo code and compared with an experiment. An irradiation field of intermediate neutron produced in the forward direction from a thick (stopping length) target bombarded by 400 MeV nucleon(-1) carbon ions was arranged at the heavy ion medical accelerator in Chiba. Ordinary concrete shield of 90 cm thickness was installed 50 cm downstream the iron target. Activation detectors of aluminum, gold and gold covered with cadmium were inserted at various depths. Irradiated samples were extracted after exposure and gamma-ray spectrometry was performed for each sample. Comparison of experimental and calculated shows good agreement for both low- and high-energy neutron-induced reaction except for (27)Al(n,X)(24)Na reaction at the surface. PMID:21515619

  12. Study on void fraction distribution in the moderator cell of Cold Neutron Source systems in China Advanced Research Reactor

    NASA Astrophysics Data System (ADS)

    Li, Liangxing; Li, Huixiong; Hu, Jinfeng; Bi, Qincheng; Chen, Tingkuan

    2007-04-01

    A physical model is developed for analyzing and evaluating the void fraction profiles in the moderator cell of the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR), which is now constructing in the China Institute of Atomic Energy (CIAE). The results derived from the model are compared with the related experimental data and its propriety is verified. The model is then used to explore the influence of various factors, including the diameter of boiling vapor bubbles, liquid density, liquid viscosity and the total heating power acted on the moderator cell, on the void fraction profiles in the cell. The results calculated with the present model indicate that the void fraction in the moderator cell increases linearly with heating power, and increases with the liquid viscosity, but decreases as the size of bubbles increases, and increases linearly with heating power. For the case where hydrogen is being used as a moderator, calculation results show that the void fraction in the moderator cell may be less than 30%, which is the maximum void fraction permitted from the nuclear physics point of view. The model and the calculation results will help to obtain insight of the mechanism that controls the void fraction distribution in the moderator cell, and provide theoretical supports for the moderator cell design.

  13. Advanced Neutron Source Reactor (ANSR) phenomena identification and ranking (PIR) for large break loss of coolant accidents (LBLOCA)

    SciTech Connect

    Ruggles, A. E.; Cheng, L. Y.; Dimenna, R. A.; Griffith, P.; Wilson, G. E.

    1994-06-01

    A team of experts in reactor analysis conducted a phenomena identification and ranking (PIR) exercise for a large break loss-of-coolant accident (LBLOCA) in the Advanced Neutron source Reactor (ANSR). The LBLOCA transient is broken into two separate parts for the PIR exercise. The first part considers the initial depressurization of the system that follows the opening of the break. The second part of the transient includes long-term decay heat removal after the reactor is shut down and the system is depressurized. A PIR is developed for each part of the LBLOCA. The ranking results are reviewed to establish if models in the RELAP5-MOD3 thermalhydraulic code are adequate for use in ANSR LBLOCA simulations. Deficiencies in the RELAP5-MOD3 code are identified and existing data or models are recommended to improve the code for this application. Experiments were also suggested to establish models for situations judged to be beyond current knowledge. The applicability of the ANSR PIR results is reviewed for the entire set of transients important to the ANSR safety analysis.

  14. Advancing an Information Model for Environmental Observations

    NASA Astrophysics Data System (ADS)

    Horsburgh, J. S.; Aufdenkampe, A. K.; Hooper, R. P.; Lehnert, K. A.; Schreuders, K.; Tarboton, D. G.; Valentine, D. W.; Zaslavsky, I.

    2011-12-01

    Observational data are fundamental to hydrology and water resources, and the way they are organized, described, and shared either enables or inhibits the analyses that can be performed using the data. The CUAHSI Hydrologic Information System (HIS) project is developing cyberinfrastructure to support hydrologic science by enabling better access to hydrologic data. HIS is composed of three major components. HydroServer is a software stack for publishing time series of hydrologic observations on the Internet as well as geospatial data using standards-based web feature, map, and coverage services. HydroCatalog is a centralized facility that catalogs the data contents of individual HydroServers and enables search across them. HydroDesktop is a client application that interacts with both HydroServer and HydroCatalog to discover, download, visualize, and analyze hydrologic observations published on one or more HydroServers. All three components of HIS are founded upon an information model for hydrologic observations at stationary points that specifies the entities, relationships, constraints, rules, and semantics of the observational data and that supports its data services. Within this information model, observations are described with ancillary information (metadata) about the observations to allow them to be unambiguously interpreted and used, and to provide traceable heritage from raw measurements to useable information. Physical implementations of this information model include the Observations Data Model (ODM) for storing hydrologic observations, Water Markup Language (WaterML) for encoding observations for transmittal over the Internet, the HydroCatalog metadata catalog database, and the HydroDesktop data cache database. The CUAHSI HIS and this information model have now been in use for several years, and have been deployed across many different academic institutions as well as across several national agency data repositories. Additionally, components of the HIS

  15. Studies on the properties of an epithermal-neutron hydrogen analyzer.

    PubMed

    Papp, A; Csikai, J

    2010-09-01

    Systematic investigations have proved the advantages of the Epithermal Neutron Analyzer (ETNA) for bulk hydrogen analysis as compared to the thermal neutron techniques. Results can contribute, for example, to the design and construction of instruments needed for the detection and identification of plastic anti-personnel landmines, explosives hidden in airline baggage and cargo containers via hydrogen contents as an indicator of their presence. PMID:20434349

  16. Solutions of Boltzmann`s Equation for Mono-energetic Neutrons in an Infinite Homogeneous Medium

    DOE R&D Accomplishments Database

    Wigner, E. P.

    1943-11-30

    Boltzman's equation is solved for the case of monoenergetic neutrons created by a plane or point source in an infinite medium which has spherically symmetric scattering. The customary solution of the diffusion equation appears to be multiplied by a constant factor which is smaller than 1. In addition to this term the total neutron density contains another term which is important in the neighborhood of the source. It varies as 1/r{sup 2} in the neighborhood of a point source. (auth)

  17. An integrated mobile system for non-destructive analysis with tagged neutrons

    NASA Astrophysics Data System (ADS)

    Cester, D.; Nebbia, G.; Stevanato, L.; Viesti, G.; Neri, F.; Petrucci, S.; Selmi, S.; Tintori, C.

    2013-04-01

    An integrated mobile system for port security is presented. The system is designed to perform active investigations by using the tagged neutron inspection technique of suspect dangerous materials as well as passive measurements of neutrons and gamma rays to search and identify radioactive and special nuclear materials. The system has been employed in detection tests of special nuclear material as well as in a seaport demonstration.

  18. Suitability of Chinese oil well loggers for an epidemiologic study of the carcinogenic effects of neutrons.

    PubMed

    Inskip, P D; Wang, Z Y; Fen, Y S

    1991-11-01

    Neutron exposures to 191 well loggers at four oil fields in China were measured over a 3-mo period using CR-39 polycarbonate dosimeters. Doses (96% less than 0.02 mGy) were slightly lower than literature values for well loggers in North America, possibly because of differences in drilling activity. Because doses are so low, an epidemiologic study of cancer among Chinese well loggers is unlikely to be informative about the carcinogenicity of neutrons relative to sparsely ionizing radiation.

  19. Developing an Advanced Environment for Collaborative Computing

    NASA Technical Reports Server (NTRS)

    Becerra-Fernandez, Irma; Stewart, Helen; DelAlto, Martha; DelAlto, Martha; Knight, Chris

    1999-01-01

    Knowledge management in general tries to organize and make available important know-how, whenever and where ever is needed. Today, organizations rely on decision-makers to produce "mission critical" decisions that am based on inputs from multiple domains. The ideal decision-maker has a profound understanding of specific domains that influence the decision-making process coupled with the experience that allows them to act quickly and decisively on the information. In addition, learning companies benefit by not repeating costly mistakes, and by reducing time-to-market in Research & Development projects. Group-decision making tools can help companies make better decisions by capturing the knowledge from groups of experts. Furthermore, companies that capture their customers preferences can improve their customer service, which translates to larger profits. Therefore collaborative computing provides a common communication space, improves sharing of knowledge, provides a mechanism for real-time feedback on the tasks being performed, helps to optimize processes, and results in a centralized knowledge warehouse. This paper presents the research directions. of a project which seeks to augment an advanced collaborative web-based environment called Postdoc, with workflow capabilities. Postdoc is a "government-off-the-shelf" document management software developed at NASA-Ames Research Center (ARC).

  20. Elementary quantum mechanics of the neutron with an electric dipole moment.

    PubMed

    Baym, Gordon; Beck, D H

    2016-07-01

    The neutron, in addition to possibly having a permanent electric dipole moment as a consequence of violation of time-reversal invariance, develops an induced electric dipole moment in the presence of an external electric field. We present here a unified nonrelativistic description of these two phenomena, in which the dipole moment operator, [Formula: see text], is not constrained to lie along the spin operator. Although the expectation value of [Formula: see text] in the neutron is less than [Formula: see text] of the neutron radius, [Formula: see text], the expectation value of [Formula: see text] is of order [Formula: see text] We determine the spin motion in external electric and magnetic fields, as used in past and future searches for a permanent dipole moment, and show that the neutron electric polarizability, although entering the neutron energy in an external electric field, does not affect the spin motion. In a simple nonrelativistic model we show that the expectation value of the permanent dipole is, to lowest order, proportional to the product of the time-reversal-violating coupling strength and the electric polarizability of the neutron.

  1. Development of a small scintillation detector with an optical fiber for fast neutrons.

    PubMed

    Yagi, T; Unesaki, H; Misawa, T; Pyeon, C H; Shiroya, S; Matsumoto, T; Harano, H

    2011-02-01

    To investigate the characteristics of a reactor and a neutron generator, a small scintillation detector with an optical fiber with ThO(2) has been developed to measure fast neutrons. However, experimental facilities where (232)Th can be used are limited by regulations, and S/N ratio is low because the background counts of this detector are increase by alpha decay of (232)Th. The purpose of this study is to develop a new optical fiber detector for measuring fast neutrons that does not use nuclear material such as (232)Th. From the measured and calculated results, the new optical fiber detector which uses ZnS(Ag) as a converter material together with a scintillator have the highest detection efficiency among several developed detectors. It is applied for the measurement of reaction rates generated from fast neutrons; furthermore, the absolute detection efficiency of this detector was obtained experimentally.

  2. An intercomparison of neutron measurments for a 25 MV x-ray radiotherapy accelerator.

    PubMed

    Nath, R; Price, K W; Holeman, G R

    1980-01-01

    High-energy x-ray radiotherapy machines produce neutrons by photonuclear reactions which present a potential radiation hazard to the personnel and patient. A series of measurements of the neutron flux from a 25 MV x-ray linear accelerator, inside and outside the treatment room, have been performed using a multisphere spectrometer, Nemo dosimeter, and activation detectors. These results are compared with other mixed photon-neutron field measurements for the same machine performed using an argon/propane ionization chamber, silicon diode, track-etching detectors, and Monte Carlo calculations. It is found that these measurements agree with each other within a factor of two except for silicon diode measurements in the photon beam. Measured neutron spectra at various locations in the treatment room are also compared with the results of Monte Carlo transport calculations.

  3. Method of using deuterium-cluster foils for an intense pulsed neutron source

    DOEpatents

    Miley, George H.; Yang, Xiaoling

    2013-09-03

    A method is provided for producing neutrons, comprising: providing a converter foil comprising deuterium clusters; focusing a laser on the foil with power and energy sufficient to cause deuteron ions to separate from the foil; and striking a surface of a target with the deuteron ions from the converter foil with energy sufficient to cause neutron production by a reaction selected from the group consisting of D-D fusion, D-T fusion, D-metal nuclear spallation, and p-metal. A further method is provided for assembling a plurality of target assemblies for a target injector to be used in the previously mentioned manner. A further method is provided for producing neutrons, comprising: splitting a laser beam into a first beam and a second beam; striking a first surface of a target with the first beam, and an opposite second surface of the target with the second beam with energy sufficient to cause neutron production.

  4. Design of the radiation shielding for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Du, T. F.; Chen, Z. J.; Peng, X. Y.; Yuan, X.; Zhang, X.; Hu, Z. M.; Cui, Z. Q.; Xie, X. F.; Ge, L. J.; Li, X. Q.; Zhang, G. H.; Chen, J. X.; Fan, T. S.; Gorini, G.; Nocente, M.; Tardocchi, M.; Hu, L. Q.; Zhong, G. Q.; Lin, S. Y.; Wan, B. N.

    2014-11-15

    A radiation shielding has been designed to reduce scattered neutrons and background gamma-rays for the new double-ring Time Of Flight Enhanced Diagnostics (TOFED). The shielding was designed based on simulation with the Monte Carlo code MCNP5. Dedicated model of the EAST tokamak has been developed together with the emission neutron source profile and spectrum; the latter were simulated with the Nubeam and GENESIS codes. Significant reduction of background radiation at the detector can be achieved and this satisfies the requirement of TOFED. The intensities of the scattered and direct neutrons in the line of sight of the TOFED neutron spectrometer at EAST are studied for future data interpretation.

  5. Design of the radiation shielding for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak.

    PubMed

    Du, T F; Chen, Z J; Peng, X Y; Yuan, X; Zhang, X; Gorini, G; Nocente, M; Tardocchi, M; Hu, Z M; Cui, Z Q; Xie, X F; Ge, L J; Hu, L Q; Zhong, G Q; Lin, S Y; Wan, B N; Li, X Q; Zhang, G H; Chen, J X; Fan, T S

    2014-11-01

    A radiation shielding has been designed to reduce scattered neutrons and background gamma-rays for the new double-ring Time Of Flight Enhanced Diagnostics (TOFED). The shielding was designed based on simulation with the Monte Carlo code MCNP5. Dedicated model of the EAST tokamak has been developed together with the emission neutron source profile and spectrum; the latter were simulated with the Nubeam and GENESIS codes. Significant reduction of background radiation at the detector can be achieved and this satisfies the requirement of TOFED. The intensities of the scattered and direct neutrons in the line of sight of the TOFED neutron spectrometer at EAST are studied for future data interpretation.

  6. Neutron detector

    DOEpatents

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  7. Neutron detector

    SciTech Connect

    Stephan, Andrew C; Jardret, Vincent D

    2009-04-07

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  8. PRODUCTION AND APPLICATIONS OF NEUTRONS USING PARTICLE ACCELERATORS

    SciTech Connect

    David L. Chichester

    2009-11-01

    Advances in neutron science have gone hand in hand with the development and of particle accelerators from the beginning of both fields of study. Early accelerator systems were developed simply to produce neutrons, allowing scientists to study their properties and how neutrons interact in matter, but people quickly realized that more tangible uses existed too. Today the diversity of applications for industrial accelerator-based neutron sources is high and so to is the actual number of instruments in daily use is high, and they serve important roles in the fields where they're used. This chapter presents a technical introduction to the different ways particle accelerators are used to produce neutrons, an historical overview of the early development of neutron-producing particle accelerators, a description of some current industrial accelerator systems, narratives of the fields where neutron-producing particle accelerators are used today, and comments on future trends in the industrial uses of neutron producing particle accelerators.

  9. Neutron activation analysis of an Egyptian monazite ore sample

    NASA Astrophysics Data System (ADS)

    Eissa, E. A.; Rofail, N. B.; Ashmawy, L. S.; Hassan, A. M.

    1999-01-01

    The absolute sensitivity of a gamma-ray line following thermal or epithermal neutron activation is expressed as a product of four terms, namely, the intrinsic, irradiation, decay and measurement factors. The total absolute sensitivity is the sum of the absolute sensitivities due to thermal and epithermal activation. A. FORTRAN computer program was prepared on the TANDY 3000 NL PCA to calculate the total absolute sensitivity of the intensive gamma-ray lines from the thermal and epithermal neutron activation of all the naturally occurring nuclides. Another program was prepared for the determination of the total absolute sensitivity for gammarays emitted by radioactive daughters such as233Pa from233Th and239Np from239U. Long time irradiation periods (about 48 hours) for specimens of the monazite ore sample were carried out at the (ET-RR-1) reactor core periphery. The monazite ore sample was separated from the associating minerals in the sand of Abou-Khashaba of Rashied (Rosetta) area on the Mediterranean (North of Egypt). The separated monazite ore sample was provided by the Nuclear Material Authority of Egypt. The cadmium difference method was applied to thin gold foils for absolute thermal and epithermal neutron flux determination. The gamma-ray spectra were measured using a spectrometer with a HPGe coaxial detector. The evaluated absolute sensitivity tables were helpful in identifying the radioisotopes contributing to the gamma- ray spectra and in evaluating the elemental concentration of the monazite constitutents. Most of the rare earth elements were observed and their concentrations are reported. La, Ce, Nd, Sd and Th were found as major elements, U, Tb, Hf and Eu as minor elements.

  10. Plan for an Advanced Turbine Systems Program

    SciTech Connect

    Bajura, R.A.; Webb, H.A.; Parks, W.P.

    1993-03-01

    A draft version of this paper was presented at the Clemson Clean, affordable, and reliable natural gas utilization technologies will play a growing role in meeting future power generation needs in the United States. The US Department of Energy`s (DOE) National Energy Strategy projected that total demand for natural gas will rise from 18.5 trillion cubic feet (tcf) in 1990 to 24.2 tcf by the year 2000. Much of this increase is attributed to the increased use of natural gas as a fuel for electric power generation. Candidate technologies for gas fired power generation include gas turbine and fuel cell systems. The first workshop on research needs for advanced gas turbine systems for power generation was held on April 8-10, 1991 in Greenville, South Carolina. The goals of the Clemson-I Workshop were to identify research needs which would accelerate the development of advanced gas turbines and to consider new approaches to implement this research. The Clemson-I Workshop focused on advanced gas turbine systems which would have a lower cost of electricity or better environmental performance than systems currently under development. The workshop was cosponsored by the DOE`s Morgantown Energy Technology Center (METC), Clemson University, and the South Carolina Energy Research and Development Center. The proceedings from the workshop have been published. The 75 participants in the Clemson-I Workshop represented a broad spectrum of the gas turbine Research & Development (R&D) community as well as potential users of advanced gas turbines. Gas turbine manufacturers, the electric utility industry, the university community, as well as government and private sector R&D sponsors were represented. Participants in the Clemson-I Workshop concluded that it is technically feasible to develop advanced turbine systems and that Government participation would accelerate the developmental effort. Advanced turbine systems could be operated on natural gas or adapted to coal or biomass firing.

  11. Plan for an Advanced Turbine Systems Program

    SciTech Connect

    Bajura, R.A.; Webb, H.A. ); Parks, W.P. )

    1993-01-01

    A draft version of this paper was presented at the Clemson Clean, affordable, and reliable natural gas utilization technologies will play a growing role in meeting future power generation needs in the United States. The US Department of Energy's (DOE) National Energy Strategy projected that total demand for natural gas will rise from 18.5 trillion cubic feet (tcf) in 1990 to 24.2 tcf by the year 2000. Much of this increase is attributed to the increased use of natural gas as a fuel for electric power generation. Candidate technologies for gas fired power generation include gas turbine and fuel cell systems. The first workshop on research needs for advanced gas turbine systems for power generation was held on April 8-10, 1991 in Greenville, South Carolina. The goals of the Clemson-I Workshop were to identify research needs which would accelerate the development of advanced gas turbines and to consider new approaches to implement this research. The Clemson-I Workshop focused on advanced gas turbine systems which would have a lower cost of electricity or better environmental performance than systems currently under development. The workshop was cosponsored by the DOE's Morgantown Energy Technology Center (METC), Clemson University, and the South Carolina Energy Research and Development Center. The proceedings from the workshop have been published. The 75 participants in the Clemson-I Workshop represented a broad spectrum of the gas turbine Research Development (R D) community as well as potential users of advanced gas turbines. Gas turbine manufacturers, the electric utility industry, the university community, as well as government and private sector R D sponsors were represented. Participants in the Clemson-I Workshop concluded that it is technically feasible to develop advanced turbine systems and that Government participation would accelerate the developmental effort. Advanced turbine systems could be operated on natural gas or adapted to coal or biomass firing.

  12. Engine health monitoring: An advanced system

    NASA Technical Reports Server (NTRS)

    Dyson, R. J. E.

    1981-01-01

    The advanced propulsion monitoring system is described. The system was developed in order to fulfill a growing need for effective engine health monitoring. This need is generated by military requirements for increased performance and efficiency in more complex propulsion systems, while maintaining or improving the cost to operate. This program represents a vital technological step in the advancement of the state of the art for monitoring systems in terms of reliability, flexibility, accuracy, and provision of user oriented results. It draws heavily on the technology and control theory developed for modern, complex, electronically controlled engines and utilizes engine information which is a by-product of such a system.

  13. An overview of DANCE: a 4II BaF[2] detector for neutron capture measurements at LANSCE.

    SciTech Connect

    Ullmann, J. L.

    2004-01-01

    The Detector for Advanced Neutron Capture experiments (DANCE) is a 162-element, 4{pi} BaF{sub 2} array designed to make neutron capture cross-section measurements on rare or radioactive targets with masses as little as 1 mg. Accurate capture cross sections are needed in many research areas, including stellar nucleosynthesis, advanced nuclear fuel cycles, waste transmutation, and other applied programs. These cross sections are difficult to calculate accurately and must be measured. Up to now, except for a few long-lived nuclides there are essentially no differential capture measurements on radioactive nuclei. The DANCE array is located at the Lujan Neutron Scattering Center at LANSCE, which is a continuous-spectrum neutron source with useable energies from below thermal to about 100 keV. Data acquisition is done with 320 fast waveform digitizers. The design and initial performance results, including background minimization, will be discussed.

  14. AFDM: An Advanced Fluid-Dynamics Model

    SciTech Connect

    Bohl, W.R.; Parker, F.R. ); Wilhelm, D. . Inst. fuer Neutronenphysik und Reaktortechnik); Berthier, J. ); Goutagny, L. . Inst. de Protection et de Surete Nucleaire); Ninokata,

    1990-09-01

    AFDM, or the Advanced Fluid-Dynamics Model, is a computer code that investigates new approaches simulating the multiphase-flow fluid-dynamics aspects of severe accidents in fast reactors. The AFDM formalism starts with differential equations similar to those in the SIMMER-II code. These equations are modified to treat three velocity fields and supplemented with a variety of new models. The AFDM code has 12 topologies describing what material contacts are possible depending on the presence or absence of a given material in a computational cell, on the dominant liquid, and on the continuous phase. Single-phase, bubbly, churn-turbulent, cellular, and dispersed flow regimes are permitted for the pool situations modeled. Virtual mass terms are included for vapor in liquid-continuous flow. Interfacial areas between the continuous and discontinuous phases are convected to allow some tracking of phenomenological histories. Interfacial areas are also modified by models of nucleation, dynamic forces, turbulence, flashing, coalescence, and mass transfer. Heat transfer is generally treated using engineering correlations. Liquid-vapor phase transitions are handled with the nonequilibrium, heat-transfer-limited model, whereas melting and freezing processes are based on equilibrium considerations. Convection is treated using a fractional-step method of time integration, including a semi-implicit pressure iteration. A higher-order differencing option is provided to control numerical diffusion. The Los Alamos SESAME equation-of-state has been implemented using densities and temperatures as the independent variables. AFDM programming has vectorized all computational loops consistent with the objective of producing an exportable code. 24 refs., 4 figs.

  15. Analysis of containment performance and radiological consequences under severe accident conditions for the Advanced Neutron Source Reactor at the Oak Ridge National Laboratory

    SciTech Connect

    Kim, S.H.; Taleyarkhan, R.P.

    1994-01-01

    A severe accident study was conducted to evaluate conservatively scoped source terms and radiological consequences to support the Advanced Neutron Source (ANS) Conceptual Safety Analysis Report (CSAR). Three different types of severe accident scenarios were postulated with a view of evaluating conservatively scoped source terms. The first scenario evaluates maximum possible steaming loads and associated radionuclide transport, whereas the next scenario is geared towards evaluating conservative containment loads from releases of radionuclide vapors and aerosols with associated generation of combustible gases. The third scenario follows the prescriptions given by the 10 CFR 100 guidelines. It was included in the CSAR for demonstrating site-suitability characteristics of the ANS. Various containment configurations are considered for the study of thermal-hydraulic and radiological behaviors of the ANS containment. Severe accident mitigative design features such as the use of rupture disks were accounted for. This report describes the postulated severe accident scenarios, methodology for analysis, modeling assumptions, modeling of several severe accident phenomena, and evaluation of the resulting source term and radiological consequences.

  16. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  17. Report of the ANS Project Feasibility Workshop for a High Flux Isotope Reactor-Center for Neutron Research Facility

    SciTech Connect

    Peretz, F.J.; Booth, R.S.

    1995-07-01

    The Advanced Neutron Source (ANS) Conceptual Design Report (CDR) and its subsequent updates provided definitive design, cost, and schedule estimates for the entire ANS Project. A recent update to this estimate of the total project cost for this facility was $2.9 billion, as specified in the FY 1996 Congressional data sheet, reflecting a line-item start in FY 1995. In December 1994, ANS management decided to prepare a significantly lower-cost option for a research facility based on ANS which could be considered during FY 1997 budget deliberations if DOE or Congressional planners wished. A cost reduction for ANS of about $1 billion was desired for this new option. It was decided that such a cost reduction could be achieved only by a significant reduction in the ANS research scope and by maximum, cost-effective use of existing High Flux Isotope Reactor (HFIR) and ORNL facilities to minimize the need for new buildings. However, two central missions of the ANS -- neutron scattering research and isotope production-were to be retained. The title selected for this new option was High Flux Isotope Reactor-Center for Neutron Research (HFIR-CNR) because of the project`s maximum use of existing HFIR facilities and retention of selected, central ANS missions. Assuming this shared-facility requirement would necessitate construction work near HFIR, it was specified that HFIR-CNR construction should not disrupt normal operation of HFIR. Additional objectives of the study were that it be highly credible and that any material that might be needed for US Department of Energy (DOE) and Congressional deliberations be produced quickly using minimum project resources. This requirement made it necessary to rely heavily on the ANS design, cost, and schedule baselines. A workshop methodology was selected because assessment of each cost and/or scope-reduction idea required nearly continuous communication among project personnel to ensure that all ramifications of propsed changes.

  18. Boron neutron capture therapy for malignant melanoma: An experimental approach

    SciTech Connect

    Larsson, B.S.; Larsson, B.; Roberto, A. )

    1989-07-01

    Previous studies have shown that some thioamides, e.g., thiouracil, are incorporated as false precursors into melanin during its synthesis. If boronated analogs of the thioamides share this property, the melanin of melanotic melanomas offers a possibility for specific tumoural uptake and retention of boron as a basis for neutron capture therapy. We report on the synthesis of boronated 1H-1,2,4-triazole-3-thiol (B-TZT), boronated 5-carboxy-2-thiouracil (B-CTU), and boronated 5-diethylaminomethyl-2-thiouracil (B-DEAMTU) and the localization of these substances in melanotic melanomas transplanted to mice. The distribution in the mice was studied by boron neutron capture radiography. B-TZT and B-CTU showed the highest tumour:normal tissue concentration ratios, with tumour:liver ratios of about 4 and tumour:muscle ratios of about 14; B-DEAMTU showed corresponding ratios of 1.4 and 5, respectively. The absolute concentration of boron in the tumours, however, was more than three times higher in the mice injected with B-TZT, compared with B-CTU. The results suggest that B-TZT may be the most promising compound of the three tested with regard to possible therapy of melanotic melanomas.

  19. An economic study of an advanced technology supersonic cruise vehicle

    NASA Technical Reports Server (NTRS)

    Smith, C. L.; Williams, L. J.

    1975-01-01

    A description is given of the methods used and the results of an economic study of an advanced technology supersonic cruise vehicle. This vehicle was designed for a maximum range of 4000 n.mi. at a cruise speed of Mach 2.7 and carrying 292 passengers. The economic study includes the estimation of aircraft unit cost, operating cost, and idealized cash flow and discounted cash flow return on investment. In addition, it includes a sensitivity study on the effects of unit cost, manufacturing cost, production quantity, average trip length, fuel cost, load factor, and fare on the aircraft's economic feasibility.

  20. MANTA. An Integral Reactor Physics Experiment to Infer the Neutron Capture Cross Sections of Actinides and Fission Products in Fast and Epithermal Spectra

    SciTech Connect

    Youinou, Gilles Jean-Michel

    2015-10-01

    Neutron cross-sections characterize the way neutrons interact with matter. They are essential to most nuclear engineering projects and, even though theoretical progress has been made as far as the predictability of neutron cross-section models, measurements are still indispensable to meet tight design requirements for reduced uncertainties. Within the field of fission reactor technology, one can identify the following specializations that rely on the availability of accurate neutron cross-sections: (1) fission reactor design, (2) nuclear fuel cycles, (3) nuclear safety, (4) nuclear safeguards, (5) reactor monitoring and neutron fluence determination and (6) waste disposal and transmutation. In particular, the assessment of advanced fuel cycles requires an extensive knowledge of transuranics cross sections. Plutonium isotopes, but also americium, curium and up to californium isotope data are required with a small uncertainty in order to optimize significant features of the fuel cycle that have an impact on feasibility studies (e.g. neutron doses at fuel fabrication, decay heat in a repository, etc.). Different techniques are available to determine neutron cross sections experimentally, with the common denominator that a source of neutrons is necessary. It can either come from an accelerator that produces neutrons as a result of interactions between charged particles and a target, or it can come from a nuclear reactor. When the measurements are performed with an accelerator, they are referred to as differential since the analysis of the data provides the cross-sections for different discrete energies, i.e. σ(Ei), and for the diffusion cross sections for different discrete angles. Another approach is to irradiate a very pure sample in a test reactor such as the Advanced Test Reactor (ATR) at INL and, after a given time, determine the amount of the different transmutation products. The precise characterization of the nuclide densities before and after

  1. Fuel, Structural Material and Coolant for an Advanced Fast Micro-Reactor

    NASA Astrophysics Data System (ADS)

    Do Nascimento, J. A.; Duimarães, L. N. F.; Ono, S.

    The use of nuclear reactors in space, seabed or other Earth hostile environment in the future is a vision that some Brazilian nuclear researchers share. Currently, the USA, a leader in space exploration, has as long-term objectives the establishment of a permanent Moon base and to launch a manned mission to Mars. A nuclear micro-reactor is the power source chosen to provide energy for life support, electricity for systems, in these missions. A strategy to develop an advanced micro-reactor technologies may consider the current fast reactor technologies as back-up and the development of advanced fuel, structural and coolant materials. The next generation reactors (GEN-IV) for terrestrial applications will operate with high output temperature to allow advanced conversion cycle, such as Brayton, and hydrogen production, among others. The development of an advanced fast micro-reactor may create a synergy between the GEN-IV and space reactor technologies. Considering a set of basic requirements and materials properties this paper discusses the choice of advanced fuel, structural and coolant materials for a fast micro-reactor. The chosen candidate materials are: nitride, oxide as back-up, for fuel, lead, tin and gallium for coolant, ferritic MA-ODS and Mo alloys for core structures. The next step will be the neutronic and burnup evaluation of core concepts with this set of materials.

  2. Neutrons, X rays, and gamma rays: Imaging detectors, material characterization techniques, and applications; Proceedings of the Meeting, San Diego, CA, July 21, 22, 1992

    NASA Astrophysics Data System (ADS)

    Carpenter, John M.; Cline, David B.; Lanza, Richard; Mildner, David F. R.

    1993-02-01

    Topics addressed include scintillating fiber technology and applications; materials characterization techniques using gamma-rays, X-rays, and neutrons; survey of principles; systems in operation; new detection systems; and applications and sources of neutrons. Also discussed are a directional fast neutron detector using scintillating fibers and electrooptics; a dark-matter detector, a novel light counter, and the ICARUS project; the major problems of MeV and GeV gamma-ray astrophysics; a compact, tunable source of monochromatic highly-directional X-rays; recent advances in neutron tomography; tailoring neutron spectra for fast neutron spectroscopy; area detectors for neutron protein crystallography; features of microstrip proportional counters; thermal neutron imaging using microchannel plates; an image plate neutron detector; a characterization of an accelerator neutron source based on the Be(d,n) reaction; and tailoring neutron spectra for fast neutron spectroscopy. (No individual items are abstracted in this volume)

  3. Postirradiation evaluations of capsules HANS-1 and HANS-2 irradiated in the HFIR target region in support of fuel development for the advanced neutron source

    SciTech Connect

    Hofman, G.L.; Snelgrove, J.L.; Copeland, G.L.

    1995-08-01

    This report describes the design, fabrication, irradiation, and evaluation of two capsule tests containing U{sub 3}Si{sub 2} fuel particles in contact with aluminum. The tests were in support of fuel qualification for the Advanced Neutron Source (ANS) reactor, a high-powered research reactor that was planned for the Oak Ridge National Laboratory. At the time of these tests, the fuel consisted of U{sub 3}Si{sub 2}, containing highly enriched uranium dispersed in aluminum at a volume fraction of {approximately}0.15. The extremely high thermal flux in the target region of the High Flux Isotope Reactor provided up to 90% burnup in one 23-d cycle. Temperatures up to 450{degrees}C were maintained by gamma heating. Passive SiC temperature monitors were employed. The very small specimen size allowed only microstructural examination of the fuel particles but also allowed many specimens to be tested at a range of temperatures. The determination of fission gas bubble morphology by microstructural examination has been beneficial in developing a fuel performance model that allows prediction of fuel performance under these extreme conditions. The results indicate that performance of the reference fuel would be satisfactory under the ANS conditions. In addition to U{sub 3}Si{sub 2}, particles of U{sub 3}Si, UAl{sub 2}, UAl{sub x}, and U{sub 3}O{sub 8} were tested.

  4. Virtual Experiments on the Neutron Science TeraGrid Gateway

    NASA Astrophysics Data System (ADS)

    Lynch, V. E.; Cobb, J. W.; Farhi, E.; Miller, S. D.; Taylor, M.

    The TeraGrid's outreach effort to the neutron science community is creating an environment that is encouraging the exploration of advanced cyberinfrastructure being incorporated into facility operations in a way that leverages facility operations to multiply the scientific output of its users, including many NSF supported scientists in many disciplines. The Neutron Science TeraGrid Gateway serves as an exploratory incubator for several TeraGrid projects. Virtual neutron scattering experiments from one exploratory project will be highlighted.

  5. Development of an Advanced Annular Combustor

    NASA Technical Reports Server (NTRS)

    Rusnak, J. P.; Shadowen, J. H.

    1969-01-01

    The objective of the effort described in this report was to determine the structural durability of a full-scale advanced annular turbojet combustor using ASTM A-1 type fuel and operating at conditions typical of advanced supersonic aircraft. A full-scale annular combustor of the ram-induction type was fabricated and subjected to a 325-hour cyclic endurance test at conditions representative of operation in a Mach 3.0 aircraft. The combustor exhibited extensive cracking and scoop burning at the end of the test program. But these defects had no appreciable effect on combustor performance, as performance remained at a high level throughout the endurance program. Most performance goals were achieved with pressure loss values near 6% and 8%, and temperature rise variation ratio (deltaTVR) values near 1.25 and l.22 at takeoff and cruise conditions, respectively. Combustion efficiencies approached l004 and the exit radial temperature profiles were approximately as desired.

  6. An inelastic neutron scattering study of dietary phenolic acids.

    PubMed

    Marques, M Paula M; Batista de Carvalho, Luís A E; Valero, Rosendo; Machado, Nelson F L; Parker, Stewart F

    2014-04-28

    The conformational preferences and hydrogen-bonding motifs of several potential chemopreventive hydroxycinnamic derivatives were determined by inelastic neutron scattering spectroscopy. The aim is to understand their recognized beneficial activity and establish reliable structure-activity relationships for these types of dietary phytochemicals. A series of phenolic acids with different hydroxyl/methoxyl ring substitution patterns were studied: trans-cinnamic, p-coumaric, m-coumaric, trans-caffeic and ferulic acids. Their INS spectra were completely assigned by theoretical calculations performed at the Density Functional Theory level, for the isolated molecule, dimeric centrosymmetric species and the solid (using plane-wave expansion approaches). Access to the low energy vibrational region of the spectra enabled the identification of particular modes associated with intermolecular hydrogen-bonding interactions, which are the determinants of the main conformational preferences and antioxidant capacity of these systems.

  7. Neutron supermirrors: an accurate theory for layer thickness computation

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    2001-11-01

    We present a new theory for the computation of Super-Mirror stacks, using accurate formulas derived from the classical optics field. Approximations are introduced into the computation, but at a later stage than existing theories, providing a more rigorous treatment of the problem. The final result is a continuous thickness stack, whose properties can be determined at the outset of the design. We find that the well-known fourth power dependence of number of layers versus maximum angle is (of course) asymptotically correct. We find a formula giving directly the relation between desired reflectance, maximum angle, and number of layers (for a given pair of materials). Note: The author of this article, a classical opticist, has limited knowledge of the Neutron world, and begs forgiveness for any shortcomings, erroneous assumptions and/or misinterpretation of previous authors' work on the subject.

  8. Neutron induced damage in reactor pressure vessel steel: An X-ray absorption fine structure study

    NASA Astrophysics Data System (ADS)

    Kuri, G.; Cammelli, S.; Degueldre, C.; Bertsch, J.; Gavillet, D.

    2009-03-01

    The radiation damage produced in reactor pressure vessel (RPV) steels during neutron irradiation is a long-standing problem of considerable practical interest. In this study, an extended X-ray absorption fine structure (EXAFS) spectroscopy has been applied at Cu, Ni and Mn K-edges to systematically investigate neutron induced radiation damage to the metal-site bcc structure of RPV steels, irradiated with neutrons in the fluence range from 0.85 to 5.0 × 1019 cm-2. An overall similarity of Cu, Ni and Mn atomic environment in the iron matrix is observed. The radial distribution functions (RDFs), derived from EXAFS data have been found to evolve continuously as a function of neutron fluence describing the atomic-scale structural modifications in RPVs by neutron irradiations. From the pristine data, long range order beyond the first- and second-shell is apparent in the RDF spectra. In the irradiated specimens, all near-neighbour peaks are greatly reduced in magnitude, typical of damaged material. Prolonged annealing leads annihilation of point defects to give rise to an increase in the coordination numbers of near-neighbour atomic shells approaching values close to that of non-irradiated material, but does not suppress the formation of nano-sized Cu and/or Ni-rich-precipitates. Total amount of radiation damage under a given irradiation condition has been determined. The average structural parameters estimated from the EXAFS data are presented and discussed.

  9. Tritium Removal System for Airtight Room in High-flux Advanced Neutron Application Reactor (HANARO) - 12110

    SciTech Connect

    Yim, Sung Paal; Lee, Jung Hee; Kim, Hyung-Kyoo; Jung, Hoan Sung; Lee, Cheo Kyung; Yoo, Sun Kyun

    2012-07-01

    An Airtight room was installed to prevent the diffusion of tritium from the instrument room to other areas in HANARO. It was isolated by a robust structure and the inside was closed tightly. A Tritium removal system located outside the instrument room was connected to the airtight room to lower the tritium concentration when the workers enter the room for maintenance of the instruments. The tritium concentration and the dew point in the airtight room were continuously measured during the operation of the tritium removal system. The data were analyzed by using a model. There was a difference between the measured tritium concentration and the one obtained by the model. It is believed that the difference is due to the change of the generation rate of tritium which would increase as the dew point becomes lower. Based on this assumption, the previous equation was revised to better express the performance of the tritium removal system. It was re-estimated that the change of tritium concentration in an airtight room could be predicted well by using a model and equation proposed in the previous study. It was confirmed that there was a definite difference between the measured tritium concentration and the one obtained by equation from the model. It is believed that the difference is due to the change of the generation rate of tritium which would increase as the dew point becomes lower. Based on this assumption, the generation rate of tritium was controlled to have higher value and the change of tritium concentration in airtight room could be more correctly predicted. By using the revised equation, the tritium removal system would be operated more effectively. (authors)

  10. SEU In An Advanced Bipolar Integrated Circuit

    NASA Technical Reports Server (NTRS)

    Zoutendyk, John A.; Secrest, Elaine C.; Berndt, Dale F.

    1989-01-01

    Report summarizes investigation of single-event upsets (SEU) in bipolar integrated-circuit set of flip-flops (memory cells). Device tested made by advanced digital bipolar silicon process of Honeywell, Inc. Circuit chip contained 4 cells. Construction enabled study of effect of size on SEU behavior. Each cell externally biased so effect of bias current on SEU behavior. Results of study provides important information for optimal design of devices fabricated using buried-layer bipolar process operating in heavy-ion SEU environments. Designers use information to provide required levels of suppression of SEU in specific applications via combinations of size and/or cell-current scaling.

  11. DANCE (Detector for Advanced Neutron Capture Experiments) is a 4π array of BaF2 crystals installed at LANSCE, Lujan Center. Neutron capture measurements on ^157Gd and ^89Y nuclei were conducted using this facility.

    NASA Astrophysics Data System (ADS)

    Chyzh, A.; Mitchell, G.; Vieira, D.; Bredeweg, T.; Ullmann, J.; Jandel, M.; Couture, A.; Keksis, A.; Rundberg, R.; Wilhelmy, J.; O'Donnell, J.; Baramsai, B.; Haight, R.; Wouters, J.; Krticka, M.; Parker, W.; Becker, J.; Agvaanlusan, U.

    2009-10-01

    DANCE (Detector for Advanced Neutron Capture Experiments) is a 4π array of BaF2 crystals installed at LANSCE, Lujan Center. Neutron capture measurements on ^157Gd and ^89Y nuclei were conducted using this facility. The absolute cross sections of the ^89Y(n,γ) reaction was measured for the first time ever in the neutron energy range of 10 eV -- 10 keV and improvements were made in the 10 -- 300 keV range. The error bars were significantly reduced and number of cross section points was increased since the past ^89Y(n,γ) experiments. The ^157Gd(n,γ) cross section was determined at En = 20 eV -- 300 keV by normalizing the experimental DANCE data to a well known resonance taken from the ENDF/B-VII library. Computer simulations of the ^157Gd(n,γ) cascades and DANCE pulse height function were made using DICEBOX and GEANT4 codes and simulated Esum and Eγ spectra are compared to the experimental DANCE data. Values of spin and photon strength function (PSF) of the ^157Gd(n,γ) resonances are provided in the range of En = 2 -- 300 eV using spin dependence upon a γ-ray multiplicity.

  12. RELAP5 analyses of two hypothetical flow reversal events for the Advanced Neutron Source Reactor

    SciTech Connect

    Chen, N.C.J.; Wendel, M.W.; Yoder, G.L. Jr.

    1995-12-31

    The reactor design features 4 independent cooling loops (3 active, 1 standby), each containing a main circulation pump (with battery powered pony motor), heat exchanger, an accumulator, and a check valve. The first transient assumes one of these pumps fails, and also that the check valve in that loop remains stuck open. This accident is considered extremely unlikely. Flow reverses in this loop, reducing core flow because much of the coolant is diverted from the intact loops back through the failed loop. The second transient examines a 102-mm-dia instantaneous pipe break near the core inlet (worst break location). A break is assumed to occur 90 s after a total loss-of-offsite power. Core flow reversal occurs because accumulator injection overpowers the diminishing pump flow. Safety margins are evaluated against 4 thermal limits: T{sub wall} = T{sub sat}, incipient boiling, onset of significant void, and critical heat flux. For the first transient, results show that these limits are not exceeded (at 95% non-exceedance probability level) if the pony motor battery lasts 30 minutes (present design value). For the second transient, the closest approach of the fuel surface temperature to local saturation temperature during core flow reversal is about 39 C, so the fuel remains cool during this transient. Although this work is for the ANSR geometry and operating conditions, the general conclusion may be applicable to other highly subcooled reactor systems.

  13. Atmospheres around Neutron Stars

    NASA Astrophysics Data System (ADS)

    Fryer, Chris L.; Benz, Willy

    1994-12-01

    Interest in the behavior of atmospheres around neutron stars has grown astronomically in the past few years. Some of this interest arrived in the wake of the explosion of Supernova 1987A and its elusive remnant; spawning renewed interest in a method to insure material ``fall-back'' onto the adolescent neutron star in an effort to transform it into a silent black hole. However, the bulk of the activity with atmospheres around neutron stars is concentrated in stellar models with neutron star, rather than white dwarf, cores; otherwise known as Thorne-Zytkow objects. First a mere seed in the imagination of theorists, Thorne-Zytkow objects have grown into an observational reality with an ever-increasing list of formation scenarios and observational prospects. Unfortunately, the analytic work of Chevalier on supernova fall-back implies that, except for a few cases, the stellar simulations of Thorne-Zytkow objects are missing an important aspect of physics: neutrinos. Neutrino cooling removes the pressure support of these atmospheres, allowing accretion beyond the canonical Eddington rate for these objects. We present here the results of detailed hydrodynamical simulations in one and two dimensions with the additional physical effects of neutrinos, advanced equations of state, and relativity over a range of parameters for our atmosphere including entropy and chemical composition as well as a range in the neutron star size. In agreement with Chevalier, we find, under the current list of formation scenarios, that the creature envisioned by Thorne and Zytkow will not survive the enormous appetite of a neutron star. However, neutrino heating (a physical effect not considered in Chevalier's analysis) can play an important role in creating instabilities in some formation schemes, leading to an expulsion of matter rather than rapid accretion. By placing scrutiny upon the formation methods, we can determine the observational prospects for each.

  14. Thermal Analysis and Design of an Advanced Space Suit

    NASA Technical Reports Server (NTRS)

    Lin, Chin H.; Campbell, Anthony B.; French, Jonathan D.; French, D.; Nair, Satish S.; Miles, John B.

    2000-01-01

    The thermal dynamics and design of an Advanced Space Suit are considered. A transient model of the Advanced Space Suit has been developed and implemented using MATLAB/Simulink to help with sizing, with design evaluation, and with the development of an automatic thermal comfort control strategy. The model is described and the thermal characteristics of the Advanced Space suit are investigated including various parametric design studies. The steady state performance envelope for the Advanced Space Suit is defined in terms of the thermal environment and human metabolic rate and the transient response of the human-suit-MPLSS system is analyzed.

  15. An examination of the effects of drilling mud filter cakes on compensated neutron measurements using Monte Carlo

    SciTech Connect

    Gilchrist, W.A. Jr.; Mickael, M.W.; Towsley, C.W. )

    1992-01-01

    Compensated thermal neutron measurements from well bores are a commonly used nuclear measurement in geophysical applications. Typically, fast neutrons from an americium-beryllium source at one point in the instrument enter the rock formation and are slowed to thermal equilibrium. Hydrogen nuclei usually play the most crucial role in this process. Count rates from two thermal neutron detectors at different positions along the device are measured, and a ratio of these is converted into an indicator of formation porosity.

  16. Advanced Subcritical Assistance Radioisotope Thermoelectric Generator: An Imperative Solution for the Future of NASA Exploration

    NASA Astrophysics Data System (ADS)

    Arias, F. J.

    A new generation of radioisotope thermoelectrical generator is proposed for very long space exploration missions. The Advanced Subcritical Assistance Radioisotope Thermoelectric Generator (ASA-RTG) amplify the power from natural decay of pu-238 by a small subcritical multiplication produced from the small neutron background generated from (α, n) reactions between the α particles from Pu-238 and beryllium, lithium or other low-Z isotope, extracting the maximum advantage and performance from the precious α disintegration, and then of the very scarce pu-238. The process is self controlled by the natural decay of Pu-238 with the progressive reduction of the power output (RTG) and additionally and simultaneously compensate by the natural decay of a neutronic poisson which increase simultaneously the subcritical multiplication resulting in a contrary effect, i.e., causing an increase in the power. ASA-RTG is not in conflict with previous RTG, and could fit within the type of Radioisotope Thermoelectric Generator developed for NASA space missions as the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and the Advanced Stirling Radioisotope Generator (ASRG).

  17. Fission-fusion neutron source

    NASA Astrophysics Data System (ADS)

    Yu, Jinnan; Yu, Gang

    2009-04-01

    In order to meet the requirements of fusion power reactors and nuclear waste treatment, a concept of fission-fusion neutron source is proposed, which consists of a LiD assembly located in the heavy water region of the China Advanced Research Reactor. This assembly of LiD fuel rods will be irradiated with slow neutrons and will produce fusion neutrons in the central hole via the reaction 6Li(n, α). More precisely, tritium ions with a high energy of 2.739 MeV will be produced in LiD by the impinging slow neutrons. The tritium ions will in turn bombard the deuterium ions present in the LiD assembly, which will induce fusion reaction and then the production of 14 MeV neutrons. The fusion reaction rate will increase with the accumulation of tritium in LiD by the reaction between tritium and deuteron recoils produced by the 14 MeV neutrons. When the concentration of tritium reaches 0.5 · 10 22 and the fraction of fusion reactions between tritium and deuteron recoils approaches 1, the 14 MeV neutron flux is doubled and redoubled, an so forth, approaching saturation in which the tritium produced at a time t is exhausted by the fusion reactions to keep constant the tritium concentration in LiD.

  18. a Dosimetry Assessment for the Core Restraint of AN Advanced Gas Cooled Reactor

    NASA Astrophysics Data System (ADS)

    Thornton, D. A.; Allen, D. A.; Tyrrell, R. J.; Meese, T. C.; Huggon, A. P.; Whiley, G. S.; Mossop, J. R.

    2009-08-01

    This paper describes calculations of neutron damage rates within the core restraint structures of Advanced Gas Cooled Reactors (AGRs). Using advanced features of the Monte Carlo radiation transport code MCBEND, and neutron source data from core follow calculations performed with the reactor physics code PANTHER, a detailed model of the reactor cores of two of British Energy's AGR power plants has been developed for this purpose. Because there are no relevant neutron fluence measurements directly supporting this assessment, results of benchmark comparisons and successful validation of MCBEND for Magnox reactors have been used to estimate systematic and random uncertainties on the predictions. In particular, it has been necessary to address the known under-prediction of lower energy fast neutron responses associated with the penetration of large thicknesses of graphite.

  19. Preliminary design studies of an advanced general aviation aircraft

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Preliminary design studies are presented for an advanced general aviation aircraft. Advanced guidance and display concepts, laminar flow, smart structures, fuselage and wing structural design and manufacturing, and preliminary configuration design are discussed. This project was conducted as a graduate level design class under the auspices of the KU/NASA/USRA Advanced Design Program in Aeronautics. The results obtained during the fall semester of 1990 (Phase 1) and the spring semester of 1991 (Phase 2) are presented.

  20. A toroidal vortex field as an origin of the narrow mass spectrum of neutron stars

    NASA Astrophysics Data System (ADS)

    Kontorovich, V. M.

    2016-03-01

    The evolution and collapse of a gaseous, self-gravitating sphere in the presence of an internal massive toroidal vortex analogous to the vortex created by the toroidal magnetic field of the Sun is considered. When thermal pressure is taken into account, for sufficiently high masses, the instability is preserved even for a polytropic index γ < 4/3. In the case of a degenerate gas, the evolution of the electrons and neutrons differs appreciably. In the ultrarelativistic limit, an interval of stablemasses arises in a neutron gas, between a minimum mass that depends on the circulation velocity in the vortex and the critical mass for the formation of a black hole. This suggests toroidal vortex fields as a possible physical origin for the observed narrow spectrum of neutron-star masses.

  1. METHOD OF INITIATING AND SUSTAINING AN ENERGETIC PLASMA FOR NEUTRON PRODUCTION

    DOEpatents

    Bell, P.R.; Mackin, R.J. Jr.; Simon, A.

    1961-08-22

    A method for producing an energetic plasma for neutron production and for faeling this plasma once it is formed is described. The plasma is initially fonmed as set forth in U. S. Patent No. 2,969,308. After the plasma is formed, cold neutral particles with an energy of at least 1 Kev are injected in a radial directinn and transverse to the axis of the device. These cold particles are substituted for the molecular ion injection and are used for fueling the plasma device on a continuous regulated basis in order to maintain a reaction temperature of about 60 Kev for producing neutrons. (AE C)

  2. Neutron tubes

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  3. An example of neutronic penalizations in reactivity transient analysis using 3D coupled chain HEMERA

    SciTech Connect

    Dubois, F.; Normand, B.; Sargeni, A.

    2012-07-01

    HEMERA (Highly Evolutionary Methods for Extensive Reactor Analyses), is a fully coupled 3D computational chain developed jointly by IRSN and CEA. It is composed of CRONOS2 (core neutronics, cross sections library from APOLLO2), FLICA4 (core thermal-hydraulics) and the system code CATHARE. Multi-level and multi-dimensional models are developed to account for neutronics, core thermal-hydraulics, fuel thermal analysis and system thermal-hydraulics, dedicated to best-estimate, conservative simulations and sensitivity analysis. In IRSN, the HEMERA chain is widely used to study several types of reactivity accidents and for sensitivity studies. Just as an example of the HEMERA possibilities, we present here two types of neutronic penalizations and their impact on a power transient due to a REA (Rod Ejection Accident): in the first one, we studied a bum-up distribution modification and in the second one, a delayed-neutron fraction modification. Both modifications are applied to the whole core or localized in a few assemblies. Results show that it is possible to use global or local changes but 1) in case of bum-up modification, the total core power can increase when assembly peak power decrease so, care has to be taken if the goal is to maximize a local power peak and 2) for delayed-neutron fraction, a local modification can have the same effect as the one on the whole core, provided that it is large enough. (authors)

  4. High conduction neutron absorber to simulate fast reactor environment in an existing test reactor

    SciTech Connect

    Donna Post Guillen; Larry R. Greenwood; James R. Parry

    2014-06-22

    A new metal matrix composite material has been developed to serve as a thermal neutron absorber for testing fast reactor fuels and materials in an existing pressurized water reactor. The performance of this material was evaluated by placing neutron fluence monitors within shrouded and unshrouded holders and irradiating for up to four cycles. The monitor wires were analyzed by gamma and X-ray spectrometry to determine the activities of the activation products. Adjusted neutron fluences were calculated and grouped into three bins—thermal, epithermal, and fast—to evaluate the spectral shift created by the new material. A comparison of shrouded and unshrouded fluence monitors shows a thermal fluence decrease of ~11 % for the shielded monitors. Radioisotope activity and mass for each of the major activation products is given to provide insight into the evolution of thermal absorption cross-section during irradiation. The thermal neutron absorption capability of the composite material appears to diminish at total neutron fluence levels of ~8 × 1025 n/m2. Calculated values for dpa in excess of 2.0 were obtained for two common structural materials (iron and nickel) of interest for future fast flux experiments.

  5. Neutrons as Party Animals: An Analogy for Understanding Heavy-Element Fissility

    NASA Astrophysics Data System (ADS)

    Reed, B. Cameron

    2012-12-01

    I teach a general education class on the history of nuclear physics and the Manhattan Project. About halfway through the course we come to the discovery of fission and Niels Bohr's insight that it is the rare isotope of uranium, U-235, which fissions under slow-neutron bombardment as opposed to the much more common U-238 isotope. As an "explanation" of the differing responses of the two isotopes to bombarding neutrons, I use the known (measured) masses of the various isotopes involved to compute the energies released upon neutron capture and then compare them to the fission barriers of the "compound" nuclei so formed (U-236 and U-239). The energy released in the (neutron + U-235) reaction exceeds the fission barrier by about one million electron-volts (1 MeV), while that for the (neutron + U-238) case falls about 1.6 MeV short. (The fission barriers are respectively about 5.7 and 6.5 MeV.)

  6. Bis(pinacolato)diboron as an additive for the detection of thermal neutrons in plastic scintillators

    NASA Astrophysics Data System (ADS)

    Mahl, Adam; Yemam, Henok A.; Stuntz, John; Remedes, Tyler; Sellinger, Alan; Greife, Uwe

    2016-04-01

    A readily available and inexpensive boron compound was tested as an additive for the detection of thermal neutrons in plastic scintillators. Bis(pinacolato)diboron (B2Pin2) was determined to be a compatible boron source (8.51 wt% boron, 1.70 wt% 10B) in poly(vinyltoluene) based matrices. Plastic scintillator blends of 1-20 wt% 2,5-diphenyloxazole (PPO), 0.1 wt% 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP) and 1-15 wt% B2Pin2 were prepared that provided optical clarity, good mechanical properties, and the capability of thermal neutron detection. Independent of B2Pin2 concentration, strong 10B neutron capture signals around 90 keVee were observed at essentially constant light output. Increasing PPO concentration allowed for the use of pulse shape discrimination (PSD) in both fast and thermal neutron detection. High PPO concentrations appear to cause additional alpha quenching that affected the 10B neutron capture signal. Aging effects after storage in air for several months were observed, which led to degradation of performance and in some samples of mechanical stability.

  7. An Evaluation of Monte Carlo Simulations of Neutron Multiplicity Measurements of Plutonium Metal

    SciTech Connect

    Mattingly, John; Miller, Eric; Solomon, Clell J. Jr.; Dennis, Ben; Meldrum, Amy; Clarke, Shaun; Pozzi, Sara

    2012-06-21

    In January 2009, Sandia National Laboratories conducted neutron multiplicity measurements of a polyethylene-reflected plutonium metal sphere. Over the past 3 years, those experiments have been collaboratively analyzed using Monte Carlo simulations conducted by University of Michigan (UM), Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and North Carolina State University (NCSU). Monte Carlo simulations of the experiments consistently overpredict the mean and variance of the measured neutron multiplicity distribution. This paper presents a sensitivity study conducted to evaluate the potential sources of the observed errors. MCNPX-PoliMi simulations of plutonium neutron multiplicity measurements exhibited systematic over-prediction of the neutron multiplicity distribution. The over-prediction tended to increase with increasing multiplication. MCNPX-PoliMi had previously been validated against only very low multiplication benchmarks. We conducted sensitivity studies to try to identify the cause(s) of the simulation errors; we eliminated the potential causes we identified, except for Pu-239 {bar {nu}}. A very small change (-1.1%) in the Pu-239 {bar {nu}} dramatically improved the accuracy of the MCNPX-PoliMi simulation for all 6 measurements. This observation is consistent with the trend observed in the bias exhibited by the MCNPX-PoliMi simulations: a very small error in {bar {nu}} is 'magnified' by increasing multiplication. We applied a scalar adjustment to Pu-239 {bar {nu}} (independent of neutron energy); an adjustment that depends on energy is probably more appropriate.

  8. Implementation of an enhanced, permanently installed neutron activation diagnostic hardware for NIF

    NASA Astrophysics Data System (ADS)

    Jedlovec, Donald R.; Edwards, Ellen R.; Carrera, Jorge A.; Yeamans, Charles B.

    2015-08-01

    Neutron activation diagnostics are commonly employed as baseline neutron yield and relative spatial flux measurement instruments. Much insight into implosion performance has been gained by deployment of up to 19 identical activation diagnostic samples distributed around the target chamber at unique angular locations. Their relative simplicity and traceability provide neutron facilities with a diagnostic platform that is easy to implement and verify. However, the current National Ignition Facility (NIF) implementation relies on removable activation samples, creating a 1-2 week data turn-around time and considerable labor costs. The system described here utilizes a commercially-available lanthanum bromide (cerium-doped) scintillator with an integrated MCA emulator as the counting system and a machined zirconium-702 cap as the activation medium. The device is installed within the target bay and monitored remotely. Additionally, this system allows the placement of any activation medium tailored to the specific measurement needs. We discuss the design and function of a stand-alone and permanently installed neutron activation detector unit to measure the yield and average energy of a nominal 14 MeV neutron source with a pulse length less than one nanosecond.

  9. Neutron attenuation in the laser ducts of an inertial-confinement fusion reactor

    NASA Astrophysics Data System (ADS)

    Augustine, F., Jr.

    1981-11-01

    Neutron streaming through the laser beam ducts of an inertial confinement fusion power plant is discussed. The neutron flux through these ducts must be attenuated by a factor of 10(12) to meet radiological safety limits. Mirrors are used to bend the path of the laser beam while cutting off a line of sight path for neutrons. The Monte Carlo Code MCNP was used to analyze the two mirror SOLASE design, which only attenuated the neutron flux by a factor of 10(3). The Westinghouse design, attenuated the neutron flux by 10(4) per mirror bend, and three mirror bends were needed. It is also revealed that the large length/diameter ratio of the ducts and the thinner mirror design are crucial to the large attenuation. It is suggested that a two mirror system can be developed, at 10(6) attenuation per mirror bend by utilizing point cross overs, a second flux trap, and acute column to column angles.

  10. An Upgrade for the Advanced Light Source

    SciTech Connect

    Chemla, Daniel S.; Feinberg, Benedict; Hussain, Zahid; Kirz, Janos; Krebs, Gary F.; Padmore, Howard A.; Robin, David S.; Robinson, Arthur L.; Smith, Neville V.

    2004-09-01

    One of the first third-generation synchrotron light sources, the ALS, has been operating for almost a decade at Berkeley Lab, where experimenters have been exploiting its high brightness for forefront science. However, accelerator and insertion-device technology have significantly changed since the ALS was designed. As a result, the performance of the ALS is in danger of being eclipsed by that of newer, more advanced sources. The ALS upgrade that we are planning includes full-energy, top-off injection with higher storage-ring current and the replacement of five first-generation insertion devices with nine state-of-the art insertion devices and four new application-specific beamlines now being identified in a strategic planning process. The upgrade will help keep the ALS at the forefront of soft x-ray synchrotron light sources for the next two decades.

  11. Analysis of an advanced technology subsonic turbofan incorporating revolutionary materials

    NASA Technical Reports Server (NTRS)

    Knip, Gerald, Jr.

    1987-01-01

    Successful implementation of revolutionary composite materials in an advanced turbofan offers the possibility of further improvements in engine performance and thrust-to-weight ratio relative to current metallic materials. The present analysis determines the approximate engine cycle and configuration for an early 21st century subsonic turbofan incorporating all composite materials. The advanced engine is evaluated relative to a current technology baseline engine in terms of its potential fuel savings for an intercontinental quadjet having a design range of 5500 nmi and a payload of 500 passengers. The resultant near optimum, uncooled, two-spool, advanced engine has an overall pressure ratio of 87, a bypass ratio of 18, a geared fan, and a turbine rotor inlet temperature of 3085 R. Improvements result in a 33-percent fuel saving for the specified misssion. Various advanced composite materials are used throughout the engine. For example, advanced polymer composite materials are used for the fan and the low pressure compressor (LPC).

  12. An aerial radiological survey of the neutron products company and surrounding area

    SciTech Connect

    Vojtech, R.J.

    1994-12-01

    An aerial radiological survey was conducted from November 1-10, 1993, over the Neutron Products Company and neighboring areas. The company, located in Dickerson, Maryland, has two major operations involving the radioisotope cobalt-60 ({sup 60}Co)-the manufacture of commercial {sup 60}Co sources and the sterilization of medical products by exposure to radiation. The sterilization facility consists of two {sup 60}Co sources with activities of approximately 500,000 and 1,500,000 Ci, respectively. The purpose of the aerial survey was to detect and document any anomalous gamma-emitting radionuclides in the environment which may have resulted from operations of the Neutron Products Company. The survey covered two areas: the first was a 6.5- by 6.5-kilometer area centered over the Neutron Products facility; the second area was a 2- by 2.5-kilometer region surrounding a waste pumping station on Muddy Branch in Gaithersburg, Maryland. This site is approximately fifteen kilometers southeast of the Neutron Products facility and was included because sanitary and other liquid waste materials from the plant site are being disposed of at the pumping station. Contour maps showing gamma radiation exposure rates at 1 meter above ground level, overlaid on an aerial photo of the area, were constructed from the data measured during the flights. The exposure rates measured within the survey regions were generally uniform and typical of rates resulting from natural background radiation. Only one area showed an enhanced exposure rate not attributable to natural background. This area, located directly over the Neutron Products facility, was analyzed and identified as {sup 60}Co, the radioisotope used in the irradiation and source production operations conducted at the Neutron Products Company. The measurements over the Muddy Branch area in Gaithersburg were typical of natural background radiation and showed no evidence of {sup 60}Co or any other man-made radionuclide.

  13. Neutron diffraction investigation of an in-plane biaxial fatigued stainless steel sample of cruciform geometry

    NASA Astrophysics Data System (ADS)

    Taran, Yu V.; Balagurov, A. M.; Sheverev, S. G.; Schreiber, J.; Korsunsky, A. M.; Vorster, W. J. J.; Bomas, H.; Stoeberl, C.

    2008-03-01

    Fatigue and fracture under multiaxial stresses are among the most important current research topics aimed at ensuring improved reliability of industrial components. An ex situ in-plane biaxial low cycle fatigued sample of cruciform geometry from austenitic stainless steel AISI 321 H was investigated on the FSD stress-diffractometer at the IBR-2 pulsed nuclear reactor by using the neutron strain scanner and the uniaxial stress rig. The phase composition of fatigued material was determined and the residual macrostresses and phase microstresses were measured. To the best of our knowledge, no neutron diffraction investigations of materials subjected to biaxial loading have been previously carried out. The first results of the neutron diffraction experiment are presented and discussed.

  14. Suitability of Chinese oil well loggers for an epidemiologic study of the carcinogenic effects of neutrons.

    PubMed

    Inskip, P D; Wang, Z Y; Fen, Y S

    1991-11-01

    Neutron exposures to 191 well loggers at four oil fields in China were measured over a 3-mo period using CR-39 polycarbonate dosimeters. Doses (96% less than 0.02 mGy) were slightly lower than literature values for well loggers in North America, possibly because of differences in drilling activity. Because doses are so low, an epidemiologic study of cancer among Chinese well loggers is unlikely to be informative about the carcinogenicity of neutrons relative to sparsely ionizing radiation. PMID:1752747

  15. Measurement and calculation of the emission anisotropy of an X1 252Cf neutron source.

    PubMed

    Hawkes, N P; Freedman, R; Tagziria, H; Thomas, D J

    2007-01-01

    The authors have measured the emission anisotropy from a (252)Cf spontaneous fission neutron source in an X1 encapsulation. The measurements were made in a large low-scatter laboratory using a long counter, and data were taken at angles varying in 10 degrees steps from 0 degrees to 180 degrees relative to the cylindrical axis of the source. Corrections were made for room scatter, loss of neutrons due to air scatter and detector dead time. Calculations corresponding to these measurements were subsequently carried out using the two Monte Carlo codes MCNP and MCBEND, and the results are compared with the measurements and with each other.

  16. Investigating the Scope of an Advance Organizer for Compiler Concepts.

    ERIC Educational Resources Information Center

    Levine, Lawrence H.; Loerinc, Beatrice M.

    1985-01-01

    Investigates effectiveness of advance organizers for teaching functioning and use of compilers to undergraduate students in computer science courses. Two experimental groups used the advance organizer while two control groups did not. Findings indicate that an explicitly concept-directed organizer is effective in providing a framework for…

  17. Application of an MWD propagation resistivity and neutron tool

    SciTech Connect

    Logan, R. )

    1990-05-01

    Today, measurement-while-drilling (MWD) has become a successful drilling and formation evaluation tool for geologists and drilling engineers. However, in several situations and field examples, anomalous MWD formation responses have left many unanswered questions for formation log analysts. Many of us assumed that MWD measurements should have easily recognizable patterns that are able to be compared to the standards of wireline measurements. In many cases this is true; however, the authors look at MWD formation measurements with caution. They are impressed when these measurements agree with the standard wireline measurements and suspicious of MWD tool responses when they do not agree with these standards. MWD has the advantage of measuring the formation within minutes after the formation has been drilled and exposed to drilling fluids. This time of measurement is a dynamic period when invasion is taking place, mud cake is being built, borehole diameter is changing, etc. The time since drilled factor allows us to take advantage of good hole conditions and provide additional drilling and formation information. Also, the ability to transmit real-time data (mud pulsing) for surface monitoring allows us to make timely rig-site decisions and to provide downhole memory data for detail formation analysis. These advantages have made the resistivity and neutron combination a valuable MWD tool today. Log examples show various formation examples and interpretations. Also useful are examples of well-site quick-look interpretations using the drilling parameters and MWD measurements for hydrocarbon identification, pore pressure analysis, formation identification, and correlation and log analyses.

  18. Neutron reflecting supermirror structure

    DOEpatents

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

  19. An ultraluminous X-ray source powered by an accreting neutron star.

    PubMed

    Bachetti, M; Harrison, F A; Walton, D J; Grefenstette, B W; Chakrabarty, D; Fürst, F; Barret, D; Beloborodov, A; Boggs, S E; Christensen, F E; Craig, W W; Fabian, A C; Hailey, C J; Hornschemeier, A; Kaspi, V; Kulkarni, S R; Maccarone, T; Miller, J M; Rana, V; Stern, D; Tendulkar, S P; Tomsick, J; Webb, N A; Zhang, W W

    2014-10-01

    The majority of ultraluminous X-ray sources are point sources that are spatially offset from the nuclei of nearby galaxies and whose X-ray luminosities exceed the theoretical maximum for spherical infall (the Eddington limit) onto stellar-mass black holes. Their X-ray luminosities in the 0.5-10 kiloelectronvolt energy band range from 10(39) to 10(41) ergs per second. Because higher masses imply less extreme ratios of the luminosity to the isotropic Eddington limit, theoretical models have focused on black hole rather than neutron star systems. The most challenging sources to explain are those at the luminous end of the range (more than 10(40) ergs per second), which require black hole masses of 50-100 times the solar value or significant departures from the standard thin disk accretion that powers bright Galactic X-ray binaries, or both. Here we report broadband X-ray observations of the nuclear region of the galaxy M82 that reveal pulsations with an average period of 1.37 seconds and a 2.5-day sinusoidal modulation. The pulsations result from the rotation of a magnetized neutron star, and the modulation arises from its binary orbit. The pulsed flux alone corresponds to an X-ray luminosity in the 3-30 kiloelectronvolt range of 4.9 × 10(39) ergs per second. The pulsating source is spatially coincident with a variable source that can reach an X-ray luminosity in the 0.3-10 kiloelectronvolt range of 1.8 × 10(40) ergs per second. This association implies a luminosity of about 100 times the Eddington limit for a 1.4-solar-mass object, or more than ten times brighter than any known accreting pulsar. This implies that neutron stars may not be rare in the ultraluminous X-ray population, and it challenges physical models for the accretion of matter onto magnetized compact objects. PMID:25297433

  20. An ultraluminous X-ray source powered by an accreting neutron star.

    PubMed

    Bachetti, M; Harrison, F A; Walton, D J; Grefenstette, B W; Chakrabarty, D; Fürst, F; Barret, D; Beloborodov, A; Boggs, S E; Christensen, F E; Craig, W W; Fabian, A C; Hailey, C J; Hornschemeier, A; Kaspi, V; Kulkarni, S R; Maccarone, T; Miller, J M; Rana, V; Stern, D; Tendulkar, S P; Tomsick, J; Webb, N A; Zhang, W W

    2014-10-01

    The majority of ultraluminous X-ray sources are point sources that are spatially offset from the nuclei of nearby galaxies and whose X-ray luminosities exceed the theoretical maximum for spherical infall (the Eddington limit) onto stellar-mass black holes. Their X-ray luminosities in the 0.5-10 kiloelectronvolt energy band range from 10(39) to 10(41) ergs per second. Because higher masses imply less extreme ratios of the luminosity to the isotropic Eddington limit, theoretical models have focused on black hole rather than neutron star systems. The most challenging sources to explain are those at the luminous end of the range (more than 10(40) ergs per second), which require black hole masses of 50-100 times the solar value or significant departures from the standard thin disk accretion that powers bright Galactic X-ray binaries, or both. Here we report broadband X-ray observations of the nuclear region of the galaxy M82 that reveal pulsations with an average period of 1.37 seconds and a 2.5-day sinusoidal modulation. The pulsations result from the rotation of a magnetized neutron star, and the modulation arises from its binary orbit. The pulsed flux alone corresponds to an X-ray luminosity in the 3-30 kiloelectronvolt range of 4.9 × 10(39) ergs per second. The pulsating source is spatially coincident with a variable source that can reach an X-ray luminosity in the 0.3-10 kiloelectronvolt range of 1.8 × 10(40) ergs per second. This association implies a luminosity of about 100 times the Eddington limit for a 1.4-solar-mass object, or more than ten times brighter than any known accreting pulsar. This implies that neutron stars may not be rare in the ultraluminous X-ray population, and it challenges physical models for the accretion of matter onto magnetized compact objects.

  1. The development of an optimized neutron proportional counter for fission spectra

    NASA Astrophysics Data System (ADS)

    Millett, Marshall Geary

    Some of the materials used to make a nuclear weapon (isotopes of uranium and plutonium) are inherently unstable and undergo radioactive decay, including spontaneous fission. This spontaneous fission results in the generation of high energy neutrons that will likely escape the nuclear device. Since neutrons in the fission energy range are not common in the environment and are relatively difficult to shield, the detection of fission neutrons is useful for arms control applications such as illicit material detection or nuclear weapon treaty verification. Although neutron detectors are currently available (and utilized) for such applications, they either are excessively heavy or have low counting efficiency. This research effort comprises the development of an optimized neutron detector and is unique in that both weight and counting efficiency have been optimized for the detection of fission neutrons. The difficulty of this optimization process lies in the fact that detector weight and counting efficiency are mutually dependent. This dissertation presents the research and conclusions that lead to the optimized design, including calculations, computer modeling, model validation, and laboratory verification. Computer modeling was conducted using the MCNP (Monte Carlo N Particle) neutron transport code. For model validation and laboratory verification, a special cylindrical detector was built, called the "USNA detector," which allowed for the changing of fill gas composition and pressure as well as moderator thickness. Using this detector, experimental data were collected in order to test the effectiveness of various fill gas combinations and to provide a benchmark for the computer code. After validating computer generated results, the development of an optimized detector design proceeded by use of computer modeling. This dissertation first presents background information and initial design considerations used to determine detector and moderator candidates. The

  2. Observation of an intermediate phase in dysprosium near the Neel point by neutron diffraction

    SciTech Connect

    Bessergenev, V.G.; Gogava, V.V.; Kovalevskaya, Y.A.; Mandzhavidze, A.G.; Fedorov, V.M.; Shilo, S.I.

    1985-11-25

    The magnetic structure of dysprosium near the point of magnetic disordering has been studied as a function of the thermal history of the sample by neutron diffraction. An intermediate vortex phase appears during cooling from the paramagnetic phase and then converts into a helicoidal phase.

  3. China Advanced Research Reactor (CARR): A new reactor to be built in China for neutron scattering studies

    NASA Astrophysics Data System (ADS)

    Ye, Chuntang

    This paper outlines the main features of the CARR, a 60 MW tank-in-pool inverse neutron trap-type research reactor, which will soon be built at China Institute of Atomic Energy in Beijing to meet the increasing demands of neutron scattering research as well as isotope production in China. According to the design, slightly pressurized light water will be used both as the moderator and the primary cooling water. The undermoderated core will be surrounded by heavy water reflector, where the maximum unperturbed thermal neutron flux would be expected to be 8 × 10 14n/s cm 2 at 60 MW. Nine tangent horizontal beam tubes and some vertical tubes will be installed in the reflector. A cold source, a hot source and a 30 × 50 m 2 guide tube hall will be equipped. The CARR is due to come critical in the year of 2004.

  4. Science Opportunities at ORNL Neutron Sources

    SciTech Connect

    Anderson, Ian

    2010-02-03

    The Neutron Sciences Directorate at Oak Ridge National Laboratory (ORNL) operates two of the most advanced neutron scattering research facilities in the world: the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). Our vision is to provide unprecedented capabilities for understanding structure and properties across the spectrum of biology, chemistry, physics, and engineering, and to stay at the leading edge of neutron science by developing new instruments, tools, and services. This talk will provide an update on the operations of the two research facilities and highlight the significant research that is emerging. For example, scientists from ORNL are at the forefront of research on a new class of iron-based superconductors based on experiments performed at the Triple-Axis Spectrometer at HFIR and ARCS at SNS. The complementary nature of neutron and x-ray techniques will be discussed to spark discussion among attendees.

  5. NEUTRON SOURCE

    DOEpatents

    Bernander, N.K. et al.

    1960-10-18

    An apparatus is described for producing neutrons through target bombardment with deuterons. Deuterium gas is ionized by electron bombardment and the deuteron ions are accelerated through a magnetic field to collimate them into a continuous high intensity beam. The ion beam is directed against a deuteron pervious metal target of substantially the same nnaterial throughout to embed the deuterous therein and react them to produce neutrons. A large quantity of neutrons is produced in this manner due to the increased energy and quantity of ions bombarding the target.

  6. NEUTRONIC REACTOR

    DOEpatents

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  7. NEUTRONIC REACTOR

    DOEpatents

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  8. UCN sources at external beams of thermal neutrons. An example of PIK reactor

    NASA Astrophysics Data System (ADS)

    Lychagin, E. V.; Mityukhlyaev, V. A.; Muzychka, A. Yu.; Nekhaev, G. V.; Nesvizhevsky, V. V.; Onegin, M. S.; Sharapov, E. I.; Strelkov, A. V.

    2016-07-01

    We consider ultracold neutron (UCN) sources based on a new method of UCN production in superfluid helium (4He). The PIK reactor is chosen as a perspective example of application of this idea, which consists of installing 4He UCN source in the beam of thermal or cold neutrons and surrounding the source with moderator-reflector, which plays the role of cold neutron (CN) source feeding the UCN source. CN flux in the source can be several times larger than the incident flux, due to multiple neutron reflections from the moderator-reflector. We show that such a source at the PIK reactor would provide an order of magnitude larger density and production rate than an analogous source at the ILL reactor. We estimate parameters of 4He source with solid methane (CH4) or/and liquid deuterium (D2) moderator-reflector. We show that such a source with CH4 moderator-reflector at the PIK reactor would provide the UCN density of ~1·105 cm-3, and the UCN production rate of ~2·107 s-1. These values are respectively 1000 and 20 times larger than those for the most intense UCN user source. The UCN density in a source with D2 moderator-reflector would reach the value of ~2·105 cm-3, and the UCN production rate would be equal ~8·107 s-1. Installation of such a source in a beam of CNs would slightly increase the density and production rate.

  9. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    DOEpatents

    Bowman, Charles D.

    1992-01-01

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  10. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    DOEpatents

    Bowman, C.D.

    1992-11-03

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  11. Measurement of neutron dose with an organic liquid scintillator coupled with a spectrum weight function.

    PubMed

    Kim, E; Endo, A; Yamaguchi, Y; Yoshizawa, M; Nakamura, T

    2002-01-01

    A dose evaluation method for neutrons in the energy range of a few MeV to 100 MeV has been developed using a spectrum weight function (G-function), which is applied to an organic liquid scintillator of 12.7 cm in diameter and 12.7 cm in length. The G-function that converts the pulse height spectrum of the scintillator into the ambient dose equivalent, H*(10), was calculated by an unfolding method using successive approximation of the response function of the scintillator and the ambient dose equivalent per unit neutron fluence (H*(10) conversion coefficients) of ICRP 74. To verify the response function of the scintillator and the value of H*(10) evaluated by the G-function. pulse height spectra of the scintillator were measured in some different neutron fields, which have continuous energy, monoenergetic and quasi-monoenergetic spectra. Values of H*(10) estimated using the G-function and pulse height spectra of the scintillator were compared with those calculated using neutron energy spectra. These doses agreed with each other. From the results, it was concluded that H*(10) can be evaluated directly from the pulse height spectrum of the scintillator by applying the G-function proposed in this study. PMID:12212900

  12. Rotor-Shaped Cyclopentadienyltetraphenyl-Cyclobutadienecobalt: An Advanced Inorganic Experiment

    ERIC Educational Resources Information Center

    MacFarland, Darren K.; Gorodetzer, Rebecca

    2005-01-01

    Organometallic complex synthesis in advanced inorganic or organic courses usually begin with the synthesis of ferrocene. A synthetic experiment of an alternative compound that has a more interesting structure and the same air stability that makes ferrocene desirable is presented.

  13. A Closer Look at an Advanced Placement Calculus Problem.

    ERIC Educational Resources Information Center

    Rudd, David

    1985-01-01

    Answers and justifications for an interesting problem on the Advanced Placement Calculus AB Examination are discussed. The problem provides diverse ways in which students can gain appreciation and understanding for the subject. (MNS)

  14. Synthesis and Electrochemistry of Cyclopentadienylcarbonyliron Tetramer: An Advanced Experiment.

    ERIC Educational Resources Information Center

    White, A. J.; Cunningham, Alice J.

    1980-01-01

    Describes an advanced level experiment in which a transition metal cluster compound, cyclopentadienylcarbonyliron tetramer, is synthesized and characterized spectroscopically. Its redox properties are then explored through cyclic voltammetry. (CS)

  15. ANEM: A rotating composite target to produce an atmospheric-like neutron beam at the LNL SPES facility

    NASA Astrophysics Data System (ADS)

    Acosta Urdaneta, Gabriela Carolina; Bisello, Dario; Esposito, Juan; Mastinu, Pierfrancesco; Prete, Gianfranco; Silvestrin, Luca; Wyss, Jeffery

    2016-09-01

    A fast neutron (E> MeV) irradiation facility is under development at the 70 MeV SPES proton cyclotron at LNL (Legnaro, Italy) to investigate neutron-induced Single Event Effects (SEE) in microelectronic devices and systems. After an overview on neutron-induced SEE in electronics, we report on the progress in the design of ANEM (Atmospheric Neutron EMulator), a water-cooled rotating target made of Be and W to produce neutrons with an energy spectrum similar to that of neutrons produced by cosmic rays at sea-level. In ANEM, the protons from the cyclotron alternatively impinge on two circular sectors of Be and W of different areas; the effective neutron spectrum is a weighted combination of the spectra from the two sectors. In this contribution, we present the results of thermal-mechanical Finite Element Analysis (ANSYS) calculations of the performance of the ANEM prototype. The calculations at this stage indicate that ANEM can deliver fast neutrons with an atmospheric-like energy spectrum and with an integral flux Φn(1-70 MeV) ˜107 n cm‑2s‑1 that is 3×109 more intense than the natural one at sea-level: a very competitive flux for SEE testing.

  16. ANEM: A rotating composite target to produce an atmospheric-like neutron beam at the LNL SPES facility

    NASA Astrophysics Data System (ADS)

    Acosta Urdaneta, Gabriela Carolina; Bisello, Dario; Esposito, Juan; Mastinu, Pierfrancesco; Prete, Gianfranco; Silvestrin, Luca; Wyss, Jeffery

    2016-09-01

    A fast neutron (E> MeV) irradiation facility is under development at the 70 MeV SPES proton cyclotron at LNL (Legnaro, Italy) to investigate neutron-induced Single Event Effects (SEE) in microelectronic devices and systems. After an overview on neutron-induced SEE in electronics, we report on the progress in the design of ANEM (Atmospheric Neutron EMulator), a water-cooled rotating target made of Be and W to produce neutrons with an energy spectrum similar to that of neutrons produced by cosmic rays at sea-level. In ANEM, the protons from the cyclotron alternatively impinge on two circular sectors of Be and W of different areas; the effective neutron spectrum is a weighted combination of the spectra from the two sectors. In this contribution, we present the results of thermal-mechanical Finite Element Analysis (ANSYS) calculations of the performance of the ANEM prototype. The calculations at this stage indicate that ANEM can deliver fast neutrons with an atmospheric-like energy spectrum and with an integral flux Φn(1-70 MeV) ˜107 n cm-2s-1 that is 3×109 more intense than the natural one at sea-level: a very competitive flux for SEE testing.

  17. An Antiproton Ion Collider (AIC) for Measuring Neutron and Proton Distributions in Stable and Radioactive Nuclei

    SciTech Connect

    Kienle, Paul

    2005-10-19

    An antiproton-ion collider is proposed to independently determine mean square radii for protons and neutrons in stable and short lived nuclei by means of antiproton absorption at medium energies. The experiment makes use of the electron ion collider complex (ELISE) of the GSI FAIR project with appropriate modifications of the electron ring to store, cool and collide antiprotons of 30 MeV energy with 740A MeV energy ions.The total absorption cross-section of antiprotons by the stored ions will be measured by detecting their loss by means of the Schottky noise spectroscopy method. Cross sections for the absorption on protons and neutrons, respectively, will be studied by detection of residual nuclei with A-1 either by the Schottky method or by analysing them in recoil detectors after the first dipole stage of the NESR following the interaction zone. With a measurement of the A-1 fragment momentum distribution, one can test the momentum wave functions of the annihilated neutron and proton, respectively. Furthermore by changing the incident ion energy the tails of neutron and proton distribution can be measured.The absorption cross section is at asymptotic energies in leading order proportional to the mean square radius of the nucleus. Predicted cross sections and luminosities show that the method is applicable to nuclei with production rates of about 105 s-1 or lower, depending on the lifetime of the ions in the NESR, and for half-lives down to 1 second.

  18. An Improved Elastic and Nonelastic Neutron Transport Algorithm for Space Radiation

    NASA Technical Reports Server (NTRS)

    Clowdsley, Martha S.; Wilson, John W.; Heinbockel, John H.; Tripathi, R. K.; Singleterry, Robert C., Jr.; Shinn, Judy L.

    2000-01-01

    A neutron transport algorithm including both elastic and nonelastic particle interaction processes for use in space radiation protection for arbitrary shield material is developed. The algorithm is based upon a multiple energy grouping and analysis of the straight-ahead Boltzmann equation by using a mean value theorem for integrals. The algorithm is then coupled to the Langley HZETRN code through a bidirectional neutron evaporation source term. Evaluation of the neutron fluence generated by the solar particle event of February 23, 1956, for an aluminum water shield-target configuration is then compared with MCNPX and LAHET Monte Carlo calculations for the same shield-target configuration. With the Monte Carlo calculation as a benchmark, the algorithm developed in this paper showed a great improvement in results over the unmodified HZETRN solution. In addition, a high-energy bidirectional neutron source based on a formula by Ranft showed even further improvement of the fluence results over previous results near the front of the water target where diffusion out the front surface is important. Effects of improved interaction cross sections are modest compared with the addition of the high-energy bidirectional source terms.

  19. Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility

    SciTech Connect

    Mackinnon, A J; Johnson, M G; Frenje, J A; Casey, D T; Li, C K; Seguin, F H; Petrasso, R; Ashabranner, R; Cerjan, C; Clancy, T J; Bionta, R; Bleuel, D; Bond, E J; Caggiano, J A; Capenter, A; Eckart, M J; Edwards, M J; Friedrich, S; Glenzer, S H; Haan, S W; Hartouni, E P; Hatarik, R; Hachett, S P; McKernan, M; Jones, O; Lepape, S; Lerche, R A; Landen, O L; Moran, M; Moses, E; Munro, D; McNaney, J; Rygg, J R; Sepke, S; Spears, B; Springer, P; Yeamans, C; Farrell, M; Kilkenny, J D; Nikroo, A; Paguio, R; Knauer, J; Glebov, V; Sangster, T; Betti, R; Stoeckl, C; Magoon, J; Shoup, M J; Grim, G P; Moran, G L; Murphy, T J; Leeper, R J; Ruiz, C

    2012-05-02

    DT neutron yield (Y{sub n}), ion temperature (T{sub i}) and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-Time-Of-Flight (nTOF) spectrometers and a Magnetic Recoil Spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the redundancy required for reliable measurements of Yn, Ti and dsr. From the measured dsr value, an areal density ({rho}R) is determined from the relationship {rho}R{sub tot} (g/cm{sup 2}) = (20.4 {+-} 0.6) x dsr{sub 10-12 MeV}. The proportionality constant is determined considering implosion geometry, neutron attenuation and energy range used for the dsr measurement. To ensure high accuracy in the measurements, a series of commissioning experiments using exploding pushers have been used for in situ calibration. The spectrometers are now performing to the required accuracy, as indicated by the good agreement between the different measurements over several commissioning shots. In addition, recent data obtained with the MRS and nTOFs indicate that the implosion performance of cryogenically layered DT implosions, characterized by the experimental Ignition Threshold Factor (ITFx) which is a function of dsr (or fuel {rho}R) and Y{sub n}, has improved almost two orders of magnitude since the first shot in September, 2010.

  20. An Advanced Undergraduate Nuclear Lifetime experiment.

    ERIC Educational Resources Information Center

    Rollefson, A. A.; Prior, R. M.

    1978-01-01

    Describes an experiment for measuring the lifetime of the 60-keV state in 237-Np which is populated in the alpha decay of 241-Am. The technique used is the delayed coincidence method using a time-to-pulse-height converter. (Author/GA)

  1. Measurement of the energy spectrum of cosmic-ray induced neutrons aboard an ER-2 high-altitude airplane.

    PubMed

    Goldhagen, P; Reginatto, M; Kniss, T; Wilson, J W; Singleterry, R C; Jones, I W; Van Steveninck, W

    2002-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial aircraft flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the atmospheric ionizing radiation (AIR) project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on five flights of a NASA ER-2 high-altitude aircraft. The primary AIR instrument was a highly sensitive extended-energy multisphere neutron spectrometer with lead and steel shells placed within the moderators of two of its 14 detectors to enhance response at high energies. Detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using MCNPX. Neutron spectra were unfolded from the measured count rates using the new MAXED code. We have measured the cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron effective dose and dose equivalent rates and their dependence on altitude and geomagnetic cutoff. The measured cosmic-ray neutron spectra have almost no thermal neutrons, a large "evaporation" peak near 1 MeV and a second broad peak near 100 MeV which contributes about 69% of the neutron effective dose. At high altitude, geomagnetic latitude has very little effect on the shape of the spectrum, but it is the dominant variable affecting neutron fluence rate, which was eight times higher at the northernmost measurement location than it was at the southernmost. The shape of the spectrum varied only slightly with altitude from 21 km down to 12 km (56-201 g cm-2 atmospheric depth), but was significantly different on the ground. In all cases, ambient dose equivalent was greater than effective dose for cosmic-ray neutrons.

  2. Neutron spectral measurements in an intense photon field associated with a high-energy x-ray radiotherapy machine.

    PubMed

    Holeman, G R; Price, K W; Friedman, L F; Nath, R

    1977-01-01

    High-energy x-ray radiotherapy machines in the supermegavoltage region generate complex neutron energy spectra which make an exact evaluation of neutron shielding difficult. Fast neutrons resulting from photonuclear reactions in the x-ray target and collimators undergo successive collisions in the surrounding materials and are moderated by varying amounts. In order to examine the neutron radiation exposures quantitatively, the neutron energy spectra have been measured inside and outside the treatment room of a Sagittaire medical linear accelerator (25-MV x rays) located at Yale-New Haven Hospital. The measurements were made using a Bonner spectrometer consisting of 2-, 3-, 5-, 8-, 10- and 12-in.-diameter polyethylene spheres with 6Li and 7Li thermoluminescent dosimeter (TLD) chips at the centers, in addition to bare and cadmium-covered chips. The individual TLD chips were calibrated for neutron and photon response. The spectrometer was calibrated using a known PuBe spectrum Spectrometer measurements were made at Yale Electron Accelerator Laboratory and results compared with a neutron time-of-flight spectrometer and an activation technique. The agreement between the results from these independent methods is found to be good, except for the measurements in the direct photon beam. Quality factors have been inferred for the neutron fields inside and outside the treatment room. Values of the inferred quality factors fall primarily between 4 and 8, depending on location.

  3. An advanced thermionic theory: Recent developments

    NASA Astrophysics Data System (ADS)

    Marshall, Albert C.

    2000-01-01

    In previous papers I have shown that a revision is required to the basic approach for predicting net currents in thermionic energy conversion diodes. Revised equations were developed to properly account for electron reflection and temperature coefficient effects. Electron spectrum equations for averaging transmission coefficients were also developed. In this paper the spectrum equations are simplified and several new developments are presented that relate to the revised methodology. Recent developments include a demonstration of the general applicability of the new equations, equations for space charge that include the effects of reflection and an emitting collector, and electron cooling equations with electron reflection effects included. In addition, methods are developed to apply the new equations to non-uniform surfaces. .

  4. Stress changes ahead of an advancing tunnel

    USGS Publications Warehouse

    Abel, J.F.; Lee, F.T.

    1973-01-01

    Instrumentation placed ahead of three model tunnels in the laboratory and ahead of a crosscut driven in a metamorphic rock mass detected stress changes several tunnel diameters ahead of the tunnel face. Stress changes were detected 4 diameters ahead of a model tunnel drilled into nearly elastic acrylic, 2??50 diameters ahead of a model tunnel drilled into concrete, and 2 diameters ahead of a model tunnel drilled into Silver Plume Granite. Stress changes were detected 7??50 diameters ahead of a crosscut driven in jointed, closely foliated gneisses and gneissic granites in an experimental mine at Idaho Springs, Colorado. These results contrast markedly with a theoretical elastic estimate of the onset of detectable stress changes at 1 tunnel diameter ahead of the tunnel face. A small compressive stress concentration was detected 2 diameters ahead of the model tunnel in acrylic, 1.25 diameters ahead of the model tunnel in concrete, and 1 diameter ahead of the model tunnel in granite. A similar stress peak was detected about 6 diameters ahead of the crosscut. No such stress peak is predicted from elastic theory. The 3-dimensional in situ stress determined in the field demonstrate that geologic structure controls stress orientations in the metamorphic rock mass. Two of the computed principal stresses are parallel to the foliation and the other principal stress is normal to it. The principal stress orientations vary approximately as the foliation attitude varies. The average horizontal stress components and the average vertical stress component are three times and twice as large, respectively, as those predicted from the overburden load. An understanding of the measured stress field appears to require the application of either tectonic or residual stress components, or both. Laboratory studies indicate the presence of proportionately large residual stresses. Mining may have triggered the release of strain energy, which is controlled by geologic structure. ?? 1973.

  5. The aerodynamic design of an advanced rotor airfoil

    NASA Technical Reports Server (NTRS)

    Blackwell, J. A., Jr.; Hinson, B. L.

    1978-01-01

    An advanced rotor airfoil, designed utilizing supercritical airfoil technology and advanced design and analysis methodology is described. The airfoil was designed subject to stringent aerodynamic design criteria for improving the performance over the entire rotor operating regime. The design criteria are discussed. The design was accomplished using a physical plane, viscous, transonic inverse design procedure, and a constrained function minimization technique for optimizing the airfoil leading edge shape. The aerodynamic performance objectives of the airfoil are discussed.

  6. An advanced unmanned vehicle for remote applications

    SciTech Connect

    Pletta, J.B.; Sackos, J.

    1998-03-01

    An autonomous mobile robotic capability is critical to developing remote work applications for hazardous environments. A few potential applications include humanitarian demining and ordnance neutralization, extraterrestrial science exploration, and hazardous waste cleanup. The ability of the remote platform to sense and maneuver within its environment is a basic technology requirement which is currently lacking. This enabling technology will open the door for force multiplication and cost effective solutions to remote operations. The ultimate goal of this work is to develop a mobile robotic platform that can identify and avoid local obstacles as it traverses from its current location to a specified destination. This goal directed autonomous navigation scheme uses the Global Positioning System (GPS) to identify the robot`s current coordinates in space and neural network processing of LADAR range images for local obstacle detection and avoidance. The initial year funding provided by this LDRD project has developed a small exterior mobile robotic development platform and a fieldable version of Sandia`s Scannerless Range Imager (SRI) system. The robotic testbed platform is based on the Surveillance And Reconnaissance ground Equipment (SARGE) robotic vehicle design recently developed for the US DoD. Contingent upon follow-on funding, future enhancements will develop neural network processing of the range map data to traverse unstructured exterior terrain while avoiding obstacles. The SRI will provide real-time range images to a neural network for autonomous guidance. Neural network processing of the range map data will allow real-time operation on a Pentium based embedded processor board.

  7. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  8. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    SciTech Connect

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  9. Neutron Capture Reactions on lu Isotopes at Dance

    NASA Astrophysics Data System (ADS)

    Roig, O.; Meot, V.; Daugas, J.-M.; Morel, P.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Wouters, J. M.

    2013-03-01

    The DANCE1 (Detector for Advanced Neutron Capture Experiments) array at LANSCE spallation neutron source in Los Alamos has been used to obtain the neutron radiative capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process.2,3 Three targets were used to perform these measurements. One was natural Lu foil of 31 mg/cm2 and the other two were isotope-enriched targets of 175Lu and 176Lu. Firstly, the cross sections were obtained by normalizing yield to a well-known cross section at the thermal neutron energy. Now, we want to obtain absolute cross sections of radiative capture through a precise neutron flux determination, an accurate target mass measurement and an efficiency determination of the DANCE array.

  10. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  11. Elementary quantum mechanics of the neutron with an electric dipole moment

    NASA Astrophysics Data System (ADS)

    Baym, Gordon; Beck, D. H.

    2016-07-01

    The neutron, in addition to possibly having a permanent electric dipole moment as a consequence of violation of time-reversal invariance, develops an induced electric dipole moment in the presence of an external electric field. We present here a unified nonrelativistic description of these two phenomena, in which the dipole moment operator, DD→, is not constrained to lie along the spin operator. Although the expectation value of DD→ in the neutron is less than 101310‑13 of the neutron radius, rnrn, the expectation value of D2D→ 2 is of order rn2rn2. We determine the spin motion in external electric and magnetic fields, as used in past and future searches for a permanent dipole moment, and show that the neutron electric polarizability, although entering the neutron energy in an external electric field, does not affect the spin motion. In a simple nonrelativistic model we show that the expectation value of the permanent dipole is, to lowest order, proportional to the product of the time-reversal-violating coupling strength and the electric polarizability of the neutron.

  12. Elementary quantum mechanics of the neutron with an electric dipole moment

    NASA Astrophysics Data System (ADS)

    Baym, Gordon; Beck, D. H.

    2016-07-01

    The neutron, in addition to possibly having a permanent electric dipole moment as a consequence of violation of time-reversal invariance, develops an induced electric dipole moment in the presence of an external electric field. We present here a unified nonrelativistic description of these two phenomena, in which the dipole moment operator, DD→, is not constrained to lie along the spin operator. Although the expectation value of DD→ in the neutron is less than 10-1310-13 of the neutron radius, rnrn, the expectation value of D2D→ 2 is of order rn2rn2. We determine the spin motion in external electric and magnetic fields, as used in past and future searches for a permanent dipole moment, and show that the neutron electric polarizability, although entering the neutron energy in an external electric field, does not affect the spin motion. In a simple nonrelativistic model we show that the expectation value of the permanent dipole is, to lowest order, proportional to the product of the time-reversal-violating coupling strength and the electric polarizability of the neutron.

  13. Neutron streak camera

    DOEpatents

    Wang, C.L.

    1983-09-13

    Disclosed is an apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon. 4 figs.

  14. Organic metal neutron detector

    DOEpatents

    Butler, M.A.; Ginley, D.S.

    1984-11-21

    A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

  15. Performance of an improved thermal neutron activation detector for buried bulk explosives

    NASA Astrophysics Data System (ADS)

    McFee, J. E.; Faust, A. A.; Andrews, H. R.; Clifford, E. T. H.; Mosquera, C. M.

    2013-06-01

    First generation thermal neutron activation (TNA) sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on multi-sensor landmine detection systems. The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. The sensor is described, with emphasis on the improvements. Experiments to characterize the performance of the second generation TNA in detecting buried landmines and improvised explosive devices (IEDs) hidden in culverts are described. Performance results, including comparisons between the performance of the first and second generation systems are presented.

  16. Experimental results of neutron fluence outside an iron shield in the forward direction

    SciTech Connect

    Torres, M.M.C.; Elwyn, A.J.; Fein, D.; James, E.; Johns, K.; Davis, W.; Ciampa, D.P.; Mierkiewicz, E.

    1996-09-01

    Analyses of both lateral shielding measurements and Monte Carlo calculations for beam stop geometry for incident hadrons at energies between 10 GeV and 10 TeV suggests that the dose equivalent can be represented by the expression H = H{sub 0}(E)e{sup -r/{lambda}}/r{sup 2} where H, is the source term, r is the radial distance to the point of interest in the shield, and {lambda} is the effective interaction length, or absorption mean free path. However, unlike the lateral shielding case, there is no similarly simple analytical expression that can be used to describe the on-axis longitudinal cascade development. In this study the results from the measurement in the forward direction of neutron fluence spectra (and the derived quantity dose equivalent) for 25 to 150 GeV pions incident on an iron beam stop as a function of thickness of iron are presented. The observed dependence of both fluence and dose equivalent on shield thickness and hadron energy was then quantified in terms of an expression in which a build up factor as well as an attenuation term was included. On the basis of this analysis the conversion factor from fluence to dose equivalent was also determined for these forward going neutrons. This work represents the first systematic study at an high energy accelerator of the depth dependence of neutron fluence in longitudinal shielding.

  17. EURADOS IC2012N: FURTHER INFORMATION DERIVED FROM AN EURADOS INTERNATIONAL COMPARISON OF NEUTRON PERSONAL DOSEMETERS.

    PubMed

    Chevallier, M-A; Fantuzzi, E; Cruz-Suarez, R; Luszik-Bhadra, M; Mayer, S; Thomas, D J; Tanner, R; Vanhavere, F

    2016-09-01

    In 2012, the European Radiation Dosimetry Group (EURADOS) performed an intercomparison for neutron dosemeters that are intended to measure personal dose equivalent, Hp(10). A total of 31 participants registered with 34 dosimetry systems. The irradiation tests were chosen to provide the participants with useful information on their dosimetry systems, i.e. linearity, reproducibility, responses for different energies and angles and to simulated workplace fields. This paper gives details of the extensive information derived from the exercise. PMID:26715777

  18. An investigation of the neutron flux in bone-fluorine phantoms comparing accelerator based in vivo neutron activation analysis and FLUKA simulation data

    NASA Astrophysics Data System (ADS)

    Mostafaei, F.; McNeill, F. E.; Chettle, D. R.; Matysiak, W.; Bhatia, C.; Prestwich, W. V.

    2015-01-01

    We have tested the Monte Carlo code FLUKA for its ability to assist in the development of a better system for the in vivo measurement of fluorine. We used it to create a neutron flux map of the inside of the in vivo neutron activation analysis irradiation cavity at the McMaster Accelerator Laboratory. The cavity is used in a system that has been developed for assessment of fluorine levels in the human hand. This study was undertaken to (i) assess the FLUKA code, (ii) find the optimal hand position inside the cavity and assess the effects on precision of a hand being in a non-optimal position and (iii) to determine the best location for our γ-ray detection system within the accelerator beam hall. Simulation estimates were performed using FLUKA. Experimental measurements of the neutron flux were performed using Mn wires. The activation of the wires was measured inside (1) an empty bottle, (2) a bottle containing water, (3) a bottle covered with cadmium and (4) a dry powder-based fluorine phantom. FLUKA was used to simulate the irradiation cavity, and used to estimate the neutron flux in different positions both inside, and external to, the cavity. The experimental results were found to be consistent with the Monte Carlo simulated neutron flux. Both experiment and simulation showed that there is an optimal position in the cavity, but that the effect on the thermal flux of a hand being in a non-optimal position is less than 20%, which will result in a less than 10% effect on the measurement precision. FLUKA appears to be a code that can be useful for modeling of this type of experimental system.

  19. Non-Destructive Spent Fuel Characterization with Semi-Conducting Gallium Arsinde Neutron Imaging Arrays

    SciTech Connect

    Douglas S. McGregor; Holly K. Gersch; Jeffrey D. Sanders; John C. Lee; Mark D. Hammig; Michael R. Hartman; Yong Hong Yang; Raymond T. Klann; Brian Van Der Elzen; John T. Lindsay; Philip A. Simpson

    2002-01-30

    High resistivity bulk grown GaAs has been used to produce thermal neutron imaging devices for use in neutron radiography and characterizing burnup in spent fuel. The basic scheme utilizes a portable Sb/Be source for monoenergetic (24 keV) neutron radiation source coupled to an Fe filter with a radiation hard B-coated pixellated GaAs detector array as the primary neutron detector. The coated neutron detectors have been tested for efficiency and radiation hardness in order to determine their fitness for the harsh environments imposed by spent fuel. Theoretical and experimental results are presented, showing detector radiation hardness, expected detection efficiency and the spatial resolution from such a scheme. A variety of advanced neutron detector designs have been explored, with experimental results achieving 13% thermal neutron detection efficiency while projecting the possibility of over 30% thermal neutron detection efficiency.

  20. Investigation of an advanced fault tolerant integrated avionics system

    NASA Technical Reports Server (NTRS)

    Dunn, W. R.; Cottrell, D.; Flanders, J.; Javornik, A.; Rusovick, M.

    1986-01-01

    Presented is an advanced, fault-tolerant multiprocessor avionics architecture as could be employed in an advanced rotorcraft such as LHX. The processor structure is designed to interface with existing digital avionics systems and concepts including the Army Digital Avionics System (ADAS) cockpit/display system, navaid and communications suites, integrated sensing suite, and the Advanced Digital Optical Control System (ADOCS). The report defines mission, maintenance and safety-of-flight reliability goals as might be expected for an operational LHX aircraft. Based on use of a modular, compact (16-bit) microprocessor card family, results of a preliminary study examining simplex, dual and standby-sparing architectures is presented. Given the stated constraints, it is shown that the dual architecture is best suited to meet reliability goals with minimum hardware and software overhead. The report presents hardware and software design considerations for realizing the architecture including redundancy management requirements and techniques as well as verification and validation needs and methods.

  1. An asymptotic homogenized neutron diffusion approximation. I. Theory

    SciTech Connect

    Trahan, T. J.; Larsen, E. W.

    2012-07-01

    A monoenergetic, homogenized, anisotropic diffusion equation is derived asymptotically for large, 3-D, multiplying systems with a periodic lattice structure. The primary assumption is that the system is slightly perturbed from an infinite, periodic lattice, and that the length scale of a lattice element is small relative to the total system size. The perturbed flux is slightly buckled, and the leading order term is the product of a slowly varying amplitude component, and a rapidly varying periodic component. The amplitude function is the solution to the homogenized diffusion equation, while the periodic component is the solution to the unperturbed, infinite system, and can be found using any high-order transport method. The first order term acts as a correction term, and makes it possible to obtain a zero flux extrapolation distance for the diffusion equation by applying the Marshak boundary condition. (authors)

  2. Field ionization characteristics of an ion source array for neutron generators

    NASA Astrophysics Data System (ADS)

    Bargsten Johnson, B.; Schwoebel, P. R.; Resnick, P. J.; Holland, C. E.; Hertz, K. L.; Chichester, D. L.

    2013-11-01

    A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77 K and 293 K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293 K was demonstrated for the first time from microfabricated array structures with integrated gates.

  3. Field ionization characteristics of an ion source array for neutron generators

    SciTech Connect

    B. Bargsten Johnson; P. R. Schwoebel; P. J. Resnick; C. E. Holland; L. Hertz; D. L. Chichester

    2013-11-01

    A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77?K and 293?K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293?K was demonstrated for the first time from microfabricated array structures with integrated gates.

  4. Field ionization characteristics of an ion source array for neutron generators

    SciTech Connect

    Bargsten Johnson, B.; Schwoebel, P. R.; Resnick, P. J.; Holland, C. E.; Hertz, K. L.; Chichester, D. L.

    2013-11-07

    A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77 K and 293 K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293 K was demonstrated for the first time from microfabricated array structures with integrated gates.

  5. Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Wanchun; Broussard, L. J.; Hoffbauer, M. A.; Makela, M.; Morris, C. L.; Tang, Z.; Adamek, E. R.; Callahan, N. B.; Clayton, S. M.; Cude-Woods, C.; Currie, S.; Dees, E. B.; Ding, X.; Geltenbort, P.; Hickerson, K. P.; Holley, A. T.; Ito, T. M.; Leung, K. K.; Liu, C.-Y.; Morley, D. J.; Ortiz, Jose D.; Pattie, R. W.; Ramsey, J. C.; Saunders, A.; Seestrom, S. J.; Sharapov, E. I.; Sjue, S. K.; Wexler, J.; Womack, T. L.; Young, A. R.; Zeck, B. A.; Wang, Zhehui

    2016-09-01

    Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15 μm has been achieved, which is equivalent to a UCN energy resolution below 2 pico-electron-volts through the relation δE =m0 gδx. Here, the symbols δE, δx, m0 and g are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. This method allows different types of UCN spectroscopy and other applications.

  6. A Reverse Osmosis System for an Advanced Separation Process Laboratory.

    ERIC Educational Resources Information Center

    Slater, C. S.; Paccione, J. D.

    1987-01-01

    Focuses on the development of a pilot unit for use in an advanced separations process laboratory in an effort to develop experiments on such processes as reverse osmosis, ultrafiltration, adsorption, and chromatography. Discusses reverse osmosis principles, the experimental system design, and some experimental studies. (TW)

  7. An overview of advance care planning for patients with advanced chronic kidney disease: The basics.

    PubMed

    Wasylynuk, Betty Ann; Davison, Sara N

    2016-01-01

    As the number of Canadians living with end-stage kidney disease (ESKD) continues to grow, even higher numbers are living with advanced chronic kidney disease (CKD). Many of these people will eventually require renal replacement therapy (RRT), either dialysis or transplantation. More than 50% of patients starting RRT today are aged 65 or older, with the fastest growing group being patients 75 years and older. Despite advances to dialysis technology and dialysis care, the mortality rates remain high and dialysis patients' end-of-life care may not align with their preferences or values. Advance care planning (ACP) is an essential component of quality comprehensive kidney care. Kidney care teams develop strong relationships with their patients and are well positioned to integrate ACP into routine kidney care. This article defines ACP, outlines the essential components of ACP, and discusses the benefits, challenges, and special considerations of ACP. By enhancing the kidney care team's understanding of ACP, this article aims to assist in integrating ACP into routine kidney care for patients with advanced CKD. PMID:27215058

  8. Monitoring method for neutron flux for a spallation target in an accelerator driven sub-critical system

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang, He, Zhi-Yong; Yang, Lei; Zhang, Xue-Ying; Cui, Wen-Juan; Chen, Zhi-Qiang; Xu, Hu-Shan

    2016-07-01

    In this paper, we study a monitoring method for neutron flux for the spallation target used in an accelerator driven sub-critical (ADS) system, where a spallation target located vertically at the centre of a sub-critical core is bombarded vertically by high-energy protons from an accelerator. First, by considering the characteristics in the spatial variation of neutron flux from the spallation target, we propose a multi-point measurement technique, i.e. the spallation neutron flux should be measured at multiple vertical locations. To explain why the flux should be measured at multiple locations, we have studied neutron production from a tungsten target bombarded by a 250 MeV-proton beam with Geant4-based Monte Carlo simulations. The simulation results indicate that the neutron flux at the central location is up to three orders of magnitude higher than the flux at lower locations. Secondly, we have developed an effective technique in order to measure the spallation neutron flux with a fission chamber (FC), by establishing the relation between the fission rate measured by FC and the spallation neutron flux. Since this relation is linear for a FC, a constant calibration factor is used to derive the neutron flux from the measured fission rate. This calibration factor can be extracted from the energy spectra of spallation neutrons. Finally, we have evaluated the proposed calibration method for a FC in the environment of an ADS system. The results indicate that the proposed method functions very well. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03010000 and XDA03030000) and the National Natural Science Foundation of China(91426301).

  9. Neutron streak camera

    DOEpatents

    Wang, Ching L.

    1983-09-13

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  10. Neutron streak camera

    DOEpatents

    Wang, C.L.

    1981-05-14

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  11. INEEL Advanced Radiotherapy Research Program Annual Report 2001

    SciTech Connect

    Venhuizen, James R.

    2002-04-30

    This report summarizes the major activities and accomplishments of the Idaho National Engineering and Environmental Laboratory (INEEL) Advanced Radiotherapy Research Program for calendar year 2001. Applications of supportive research and development, as well as technology deployment in the fields of chemistry, radiation physics and dosimetry, and neutron source design and demonstration are described. Contributions in the fields of physics and biophysics include development of advanced patient treatment planning software, feasibility studies of accelerator neutron source technology for Neutron Capture Therapy (NCT), and completion of major modifications to the research reactor at Washington State University to produce an epithermal-neutron beam for NCT research applications.

  12. INEEL Advanced Radiotherapy Research Program Annual Report 2001

    SciTech Connect

    Venhuizen, James Robert

    2002-04-01

    This report summarizes the major activities and accomplishments of the Idaho National Engineering and Environmental Laboratory (INEEL) Advanced Radiotherapy Research Program for calendar year 2001. Applications of supportive research and development, as well as technology deployment in the fields of chemistry, radiation physics and dosimetry, and neutron source design and demonstration are described. Contributions in the fields of physics and biophysics include development of advanced patient treatment planning software, feasibility studies of accelerator neutron source technology for Neutron Capture Therapy (NCT), and completion of major modifications to the research reactor at Washington State University to produce an epithermal-neutron beam for NCT research applications.

  13. THE DOUBLE PULSAR: EVIDENCE FOR NEUTRON STAR FORMATION WITHOUT AN IRON CORE-COLLAPSE SUPERNOVA

    SciTech Connect

    Ferdman, R. D.; Kramer, M.; Stappers, B. W.; Lyne, A. G.; Stairs, I. H.; Breton, R. P.; McLaughlin, M. A.; Freire, P. C. C.; Possenti, A.; Kaspi, V. M.; Manchester, R. N.

    2013-04-10

    The double pulsar system PSR J0737-3039A/B is a double neutron star binary, with a 2.4 hr orbital period, which has allowed measurement of relativistic orbital perturbations to high precision. The low mass of the second-formed neutron star, as well as the low system eccentricity and proper motion, point to a different evolutionary scenario compared to most other known double neutron star systems. We describe analysis of the pulse profile shape over 6 years of observations and present the resulting constraints on the system geometry. We find the recycled pulsar in this system, PSR J0737-3039A, to be a near-orthogonal rotator with an average separation between its spin and magnetic axes of 90 Degree-Sign {+-} 11 Degree-Sign {+-} 5 Degree-Sign . Furthermore, we find a mean 95% upper limit on the misalignment between its spin and orbital angular momentum axes of 3. Degree-Sign 2, assuming that the observed emission comes from both magnetic poles. This tight constraint lends credence to the idea that the supernova that formed the second pulsar was relatively symmetric, possibly involving electron capture onto an O-Ne-Mg core.

  14. Surviving to tell the tale : Argonne's Intense Pulsed Neutron Source from an ecosystem perspective.

    SciTech Connect

    Westfall, C.; Office of The Director

    2010-07-01

    At first glance the story of the Intense Pulsed Neutron Source (IPNS), an accelerator-driven neutron source for exploring the structure of materials through neutron scattering, seems to be one of puzzling ups and downs. For example, Argonne management, Department of Energy officials, and materials science reviewers continued to offer, then withdraw, votes of confidence even though the middling-sized IPNS produced high-profile research, including work that made the cover of Nature in 1987. In the midst of this period of shifting opinion and impressive research results, some Argonne materials scientists were unenthusiastic, members of the laboratory's energy physics group were key supporters, and materials scientists at another laboratory provided, almost fortuitously, a new lease on life. What forces shaped the puzzling life cycle of the IPNS? And what role - if any - did the moderate price tag and the development of scientific and technological ideas play in the course it took? To answer these questions this paper looks to an ecosystem metaphor for inspiration, exploring how opinions, ideas, and machinery emerged from the interrelated resource economies of Argonne, the DOE, and the materials science community by way of a tangled web of shifting group interactions. The paper will conclude with reflections about what the resulting focus on relationality explains about the IPNS story as well as the underlying dynamic that animates knowledge production at U.S. national laboratories.

  15. An Algorithm for the Transport of Anisotropic Neutrons

    NASA Technical Reports Server (NTRS)

    Tweed, J.

    2005-01-01

    One major obstacle to human space exploration is the possible limitations imposed by the adverse effect of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar particle events (SPE) were of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated GCR exposures can be high. Because cancer induction rates increase behind low to rather large thicknesses of aluminum shielding, according to available biological data on mammalian exposures to GCR like ions, the shield requirements for a Mars mission are prohibitively expensive in terms of mission launch costs. Therefore, a critical issue in the Human Exploration and Development of Space enterprise is cost effective mitigation of risk associated with ionizing radiation exposure. In order to estimate astronaut risk to GCR exposure and associated cancer risks and health hazards, it is necessary to do shield material studies. To determine an optimum radiation shield material it is necessary to understand nuclear interaction processes such as fragmentation and secondary particle production which is a function of energy dependent cross sections. This requires knowledge of material transmission characteristics either through laboratory testing or improved theoretical modeling. Here ion beam transport theory is of importance in that testing of materials in the laboratory environment generated by particle accelerators is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are a major emphasis of the present work.

  16. Enhanced Analysis Techniques for an Imaging Neutron and Gamma Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Madden, Amanda C.

    The presence of gamma rays and neutrons is a strong indicator of the presence of Special Nuclear Material (SNM). The imaging Neutron and gamma ray SPECTrometer (NSPECT) developed by the University of New Hampshire and Michigan Aerospace corporation detects the fast neutrons and prompt gamma rays from fissile material, and the gamma rays from radioactive material. The instrument operates as a double scatter device, requiring a neutron or a gamma ray to interact twice in the instrument. While this detection requirement decreases the efficiency of the instrument, it offers superior background rejection and the ability to measure the energy and momentum of the incident particle. These measurements create energy spectra and images of the emitting source for source identification and localization. The dual species instrument provides superior detection than a single species alone. In realistic detection scenarios, few particles are detected from a potential threat due to source shielding, detection at a distance, high background, and weak sources. This contributes to a small signal to noise ratio, and threat detection becomes difficult. To address these difficulties, several enhanced data analysis tools were developed. A Receiver Operating Characteristic Curve (ROC) helps set instrumental alarm thresholds as well as to identify the presence of a source. Analysis of a dual-species ROC curve provides superior detection capabilities. Bayesian analysis helps to detect and identify the presence of a source through model comparisons, and helps create a background corrected count spectra for enhanced spectroscopy. Development of an instrument response using simulations and numerical analyses will help perform spectra and image deconvolution. This thesis will outline the principles of operation of the NSPECT instrument using the double scatter technology, traditional analysis techniques, and enhanced analysis techniques as applied to data from the NSPECT instrument, and an

  17. An unequivocal good? Acknowledging the complexities of advance care planning.

    PubMed

    Robins-Browne, K; Palmer, V; Komesaroff, P

    2014-10-01

    Over the past few decades advance care planning (ACP) has become the subject of debate, research and legislation in many countries. Encouraging people to express their preference for treatment in advance, ideally in written form, seems a natural way to identify what someone might have wanted when they can no longer participate in decision-making. The notion of ACP as an unequivocal good permeates much of the research and policy work in this area. For example, ACP is now actively encouraged in Australian federal and state government policies and the Victorian Government has recently published a practical ACP strategy for Victorian health services (2014-2018). However, advance care plan is ethically complex and the introduction of the Victorian health services strategy provides an opportunity to reflect on this complexity, particularly on the benefits and risks of ACP.

  18. Development of an instrument for non-destructive identification of Unexploded Ordnance using tagged neutrons - a proof of concept study

    SciTech Connect

    Mitra, S.; Dioszegi, I.

    2011-10-23

    cover 30 cm/nanosecond). The main advantage of the technique is its ability to simultaneously provide 2D and 3D imaging of objects and their elemental composition. This work reports on the efficacy of using 14 MeV neutrons tagged by the associated particle neutron time-of-flight technique (APnTOF) to extract neutron induced characteristic gamma-rays from an object-of-interest with high SNR and without interference from nearby clutter.

  19. An Approach to Model Neutron Diffraction Pattern of Uniaxial Deformed Sandstone Using Elastic Properties of Quartz

    NASA Astrophysics Data System (ADS)

    Breuer, S.; Schilling, F. R.; Mueller, B.; Scheffzuek, C.

    2015-12-01

    Mechanical properties of sedimentary rocks such as stress-strain-relations are essential for understanding dynamic processes within the Earth's crust. The measurement of in-situ lattice strain in bulk samples is possible with diffraction methods, e.g. with neutrons. The advantage of neutron diffraction is their high penetration depth, which enables to gather a statistically relevant number of grains by diffraction. The neutron time-of-flight diffraction at the strain diffractometer EPSILON which is located at the pulsed neutron source IBR-2M (JINR Dubna, RUS) enables the detection of the complete diffraction pattern up to λ = 7.1 Å (d = 5.1 Å). Uniaxial cyclic deformation experiments were carried out up to 50 MPa (three steps) on a macroscopically isotropic sandstone from Kuhbach / Lahr (Germany). The aim of the present study is to model diffraction patterns for different applied stress-levels, based on the zero-stress diffraction pattern and known elastic properties of Quartz single crystals. The as received model-predictions are compared to observations, both, in the direction of maximum stress (along the cylindric axis) and perpendicular to it. The results show that the shape of the grains has an influence on the macroscopic elastic behavior of the rock whereas the microscopic strain is affected in a different manner. The model is based on spherical quartz grains. The spheres are divided into slices. By removing some slices, the shape of sand grains is approximated. The reaction of each slice through the applied stress is modelled. Together with the relative volume of each slice and it´s elastic behavior, the diffraction pattern is predicted for different applied loads. Measured and modelled diffraction-patterns at different applied loads are in good agreement.

  20. The Dynomak: An advanced spheromak reactor system with imposed-dynamo current drive and next-generation nuclear power technologies

    NASA Astrophysics Data System (ADS)

    Sutherland, D. A.; Jarboe, T. R.; Marklin, G.; Morgan, K. D.; Nelson, B. A.

    2013-10-01

    A high-beta spheromak reactor system has been designed with an overnight capital cost that is competitive with conventional power sources. This reactor system utilizes recently discovered imposed-dynamo current drive (IDCD) and a molten salt blanket system for first wall cooling, neutron moderation and tritium breeding. Currently available materials and ITER developed cryogenic pumping systems were implemented in this design on the basis of technological feasibility. A tritium breeding ratio of greater than 1.1 has been calculated using a Monte Carlo N-Particle (MCNP5) neutron transport simulation. High-temperature superconducting tapes (YBCO) were used for the equilibrium coil set, substantially reducing the recirculating power fraction when compared to previous spheromak reactor studies. Using zirconium hydride for neutron shielding, a limiting equilibrium coil lifetime of at least thirty full-power years has been achieved. The primary FLiBe loop was coupled to a supercritical carbon dioxide Brayton cycle due to attractive economics and high thermal efficiencies. With these advancements, an electrical output of 1000 MW from a thermal output of 2486 MW was achieved, yielding an overall plant efficiency of approximately 40%. A paper concerning the Dynomak reactor design is currently being reviewed for publication.

  1. An Evaluation of Neutron Energy Spectrum Effects in Iron Based on Molecular Dynamics Displacement Cascade Simulations

    SciTech Connect

    Stoller, R.E.; Greenwood, L.R.

    1998-06-16

    The results of molecular dynamics (MD) displacement cascade simulations in bcc iron have been used to obtain effective cross sections for two measures of primary damage production: (1) the number of surviving point defects expressed as a fraction of the displacements calculated using the standard secondary displacement model of Norgett, Robinson, and Torrens (NRT), and (2) the fraction of the surviving interstitials contained in clusters that formed during the cascade event. Primary knockon atom spectra for iron obtained from the SPECTER code have been used to weight these MD-based damage production cross sections in order to obtain spectrally-averaged values for several locations in commercial fission reactors and materials test reactors. An evaluation of these results indicates that neutron energy spectrum differences between the various enviromnents do not lead to significant differences between the average primary damage formation parameters. In particular, the defect production cross sections obtained for PWR and BWR neutron spectra were not significantly different. The variation of the defect production cross sections as a function of depth into the reactor pressure vessel wall is used as a sample application of the cross sections. A slight difference between the attenuation behavior of the PWR and BWR was noted; this difference could be explained by a subtle difference in the energy dependence of the neutron spectra. Overall, the simulations support the continued use of dpa as a damage correlation parameter.

  2. Boron neutron capture therapy (BNCT) for liver metastasis: therapeutic efficacy in an experimental model

    SciTech Connect

    David W. Nigg

    2012-08-01

    Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. The present study evaluates tumor control and potential radiotoxicity of BNCT in an experimental model of liver metastasis. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA–BNCT, boronophenylalanine (BPA) ? neutron irradiation; Beam only, neutron irradiation; Sham, matched manipulation. The total absorbed dose administered with BPA–BNCT was 13 ± 3 Gy in tumor and 9 ± 2 Gy in healthy liver. Three weeks posttreatment, the tumor surface area post-treatment/pre-treatment ratio was 0.46 ± 0.20 for BPA–BNCT, 2.7 ± 1.8 for Beam only and 4.5 ± 3.1 for Sham. The pre-treatment tumor nodule mass of 48 ± 19 mgfell significantly to 19 ± 16 mg for BPA–BNCT, but rose significantly to 140 ± 106 mg for Beam only and to 346 ± 302 mg for Sham. For both end points, the differences between the BPA–BNCT group and each of the other groups were statistically significant (ANOVA). No clinical, macroscopic or histological normal liver radiotoxicity was observed. It is concluded that BPA– BNCT induced a significant remission of experimental colorectal tumor nodules in liver with no contributory liver toxicity.

  3. From "fixing women" to "institutional transformation": An ADVANCE case study

    NASA Astrophysics Data System (ADS)

    Yennello, Sherry; Kaunas, Christine

    2015-12-01

    The United States' position in the global economy requires an influx of women into science, technology, engineering, and mathematics (STEM) fields in order to remain competitive. Despite this, the representation of women in STEM continues to be low. The National Science Foundation's ADVANCE Program addresses this issue by funding projects that aim to increase the representation of women in academic STEM fields through transformation of institutional structures that impede women's progress in academic STEM fields. This paper includes a case study of the Texas A&M University ADVANCE Program.

  4. Hughes advanced nickel-cadmium batteries: An update

    NASA Technical Reports Server (NTRS)

    Bogner, R. Sam

    1991-01-01

    After delivering a significant data base on boilerplate and prototype advanced nickel cadmium (Ni/Cd) battery cells, Hughes decided to start using the Advanced Ni/Cd batteries on several of their flight programs. The advanced cell can been operated at 80 percent depth of discharge (DOD) for more than 10 years, and possibly 15 years, in geosynchronous earth orbit (GEO) applications. This cell offers an important weight saving over the standard Ni/Cd cell that is usually only operated at 50 to 60 percent DOD in GEO applications. The negative and positive electrodes are manufactured using electrochemical deposition methods which reduce the sinter corrosion problems encountered by the chemical deposition process used in the standard cells. The degradable nylon separators used in standard cells was replaced by polymer impregnated Zirconia separators.

  5. Development of an advanced photovoltaic concentrator system for space applications

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F., Jr.; O'Neill, Mark J.

    1987-01-01

    Recent studies indicate that significant increases in system performance (increased efficiency and reduced system mass) are possible for high power space based systems by incorporating technological developments with photovoltaic power systems. The Advanced Photovoltaic Concentrator Program is an effort to take advantage of recent advancements in refractive optical elements. By using a domed Fresnel lens concentrator and a prismatic cell cover, to eliminate metallization losses, dramatic reductions in the required area and mass over current space photovoltaic systems are possible. The advanced concentrator concept also has significant advantages when compared to solar dynamic Organic Rankine Cycle power systems in Low Earth Orbit applications where energy storage is required. The program is currently involved in the selection of a material for the optical element that will survive the space environment and a demonstration of the system performance of the panel design.

  6. Advanced pressurized water reactor for improved resource utilization, part II - composite advanced PWR concept

    SciTech Connect

    Turner, S.E.; Gurley, M.K.; Kirby, K.D.; Mitchell, W III

    1981-09-15

    This report evaluates the enhanced resource utilization in an advanced pressurized water reactor (PWR) concept using a composite of selected improvements identified in a companion study. The selected improvements were in the areas of reduced loss of neutrons to control poisons, reduced loss of neutrons in leakage from the core, and improved blanket/reflector concepts. These improvements were incorporated into a single composite advanced PWR. A preliminary assessment of resource requirements and costs and impact on safety are presented.

  7. 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.

  8. Cavity Ring down Spectroscopy Experiment for an Advanced Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Stacewicz, T.; Wasylczyk, P.; Kowalczyk, P.; Semczuk, M.

    2007-01-01

    A simple experiment is described that permits advanced undergraduates to learn the principles and applications of the cavity ring down spectroscopy technique. The apparatus is used for measurements of low concentrations of NO[subscript 2] produced in air by an electric discharge. We present the setup, experimental procedure, data analysis and some…

  9. Strategy to Promote Active Learning of an Advanced Research Method

    ERIC Educational Resources Information Center

    McDermott, Hilary J.; Dovey, Terence M.

    2013-01-01

    Research methods courses aim to equip students with the knowledge and skills required for research yet seldom include practical aspects of assessment. This reflective practitioner report describes and evaluates an innovative approach to teaching and assessing advanced qualitative research methods to final-year psychology undergraduate students. An…

  10. Psychiatric Advance Directives and Social Workers: An Integrative Review

    ERIC Educational Resources Information Center

    Van Dorn, Richard A.; Scheyett, Anna; Swanson, Jeffrey W.; Swartz, Marvin S.

    2010-01-01

    Psychiatric advance directives (PADs) are legal documents that allow individuals to express their wishes for future psychiatric care and to authorize a legally appointed proxy to make decisions on their behalf during incapacitating crises. PADs are viewed as an alternative to the coercive interventions that sometimes accompany mental health crises…

  11. Polybrominated Diphenyl Ethers in Dryer Lint: An Advanced Analysis Laboratory

    ERIC Educational Resources Information Center

    Thompson, Robert Q.

    2008-01-01

    An advanced analytical chemistry laboratory experiment is described that involves environmental analysis and gas chromatography-mass spectrometry. Students analyze lint from clothes dryers for traces of flame retardant chemicals, polybrominated diphenylethers (PBDEs), compounds receiving much attention recently. In a typical experiment, ng/g…

  12. Beginning an Advanced Placement Music Course. Edition Y.

    ERIC Educational Resources Information Center

    Thomson, William; And Others

    The College Entrance Examination Board has prepared this publication to help secondary school teachers develop Advanced Placement (AP) courses in music. The discussion of strategy recommendations, reading materials, and record collections should be adapted to suit local preferences and individual skills. An opening section of general remarks…

  13. Measuring Alumna Career Advancement: An Approach Based on Educational Expectations.

    ERIC Educational Resources Information Center

    Ben-Ur, Tamar; Rogers, Glen

    Alverno College (Wisconsin), a women's liberal arts college, has developed an Alumni Career Level Classification (AACLC) scheme to measure alumna career advancement and demonstrate institutional accountability. This validation study was part of a larger longitudinal study of two entire cohorts of students entering the college in 1976 and 1977, of…

  14. An Advanced Criminology Based on Psychology-of-Mind.

    ERIC Educational Resources Information Center

    Kelley, Thomas M.

    1993-01-01

    Attempts to move beyond the current criminological frames of reference to examine how the field has evolved into its present state and proposes the need for an advanced criminology based on a deeper understanding of the psychological function that is used to create all patterns of thought. (Author)

  15. A Multistep Synthesis for an Advanced Undergraduate Organic Chemistry Laboratory

    ERIC Educational Resources Information Center

    Chang Ji; Peters, Dennis G.

    2006-01-01

    Multistep syntheses are often important components of the undergraduate organic laboratory experience and a three-step synthesis of 5-(2-sulfhydrylethyl) salicylaldehyde was described. The experiment is useful as a special project for an advanced undergraduate organic chemistry laboratory course and offers opportunities for students to master a…

  16. An Advanced Marathi Reader. Parts One and Two.

    ERIC Educational Resources Information Center

    Berntsen, Maxine; Nimbkar, Jai

    This advanced reader, containing ten stories, is designed for adult students of Marathi with an intermediate knowledge of the language. It is intended to increase the students' reading skills and introduce them to some main themes in Maharashtrian life and literature. The selections deal primarily with women and marriage, and religion. It is felt…

  17. Advanced Learning Space as an Asset for Students with Disabilities

    ERIC Educational Resources Information Center

    Císarová, Klára; Lamr, Marián; Vitvarová, Jana

    2015-01-01

    The paper describes an e-learning system called Advanced Learning Space that was developed at the Technical University of Liberec. The system provides a personalized virtual work space and promotes communication among students and their teachers. The core of the system is a module that can be used to automatically record, store and playback…

  18. Novel neutron sources at the Radiological Research Accelerator Facility

    SciTech Connect

    Xu, Yanping; Garty, G.; Marino, S. A.; Massey, Thomas Neal; Johnson, G. W.; Randers-Pehrson, Gerhard; Brenner, D. J.

    2012-03-16

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the Li-7(p,n)Be-7 reaction. Lastly, this novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

  19. Novel neutron sources at the Radiological Research Accelerator Facility.

    PubMed

    Xu, Yanping; Garty, Guy; Marino, Stephen A; Massey, Thomas N; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

    2012-03-16

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons.We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target.A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the (7)Li(p,n)(7)Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

  20. Novel neutron sources at the Radiological Research Accelerator Facility

    DOE PAGESBeta

    Xu, Yanping; Garty, G.; Marino, S. A.; Massey, Thomas Neal; Johnson, G. W.; Randers-Pehrson, Gerhard; Brenner, D. J.

    2012-03-16

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will bemore » based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the Li-7(p,n)Be-7 reaction. Lastly, this novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.« less

  1. Novel neutron sources at the Radiological Research Accelerator Facility

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Garty, G.; Marino, S. A.; Massey, T. N.; Randers-Pehrson, G.; Johnson, G. W.; Brenner, D. J.

    2012-03-01

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

  2. Novel neutron sources at the Radiological Research Accelerator Facility

    PubMed Central

    Xu, Yanping; Garty, Guy; Marino, Stephen A.; Massey, Thomas N.; Randers-Pehrson, Gerhard; Johnson, Gary W.; Brenner, David J.

    2012-01-01

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10–20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components. PMID:22545061

  3. Neutron dose equivalent meter

    DOEpatents

    Olsher, Richard H.; Hsu, Hsiao-Hua; Casson, William H.; Vasilik, Dennis G.; Kleck, Jeffrey H.; Beverding, Anthony

    1996-01-01

    A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

  4. Pulsed-neutron monochromator

    DOEpatents

    Mook, H.A. Jr.

    1984-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  5. Pulsed-neutron monochromator

    DOEpatents

    Mook, Jr., Herbert A.

    1985-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  6. Excited states in neutron-rich 188W produced by an 18O-induced 2-neutron transfer reaction

    NASA Astrophysics Data System (ADS)

    Shizuma, T.; Ishii, T.; Makii, H.; Hayakawa, T.; Shigematsu, S.; Matsuda, M.; Ideguchi, E.; Zheng, Y.; Liu, M.; Morikawa, T.; Walker, P. M.; Oi, M.

    2006-11-01

    Excited states in neutron-rich 188W have been populated using a 186W(18O,16O) reaction. In-beam γ-rays were measured in coincidence with scattered particles detected by a high-resolution ΔE-E Si telescope. In this experiment, the ground-state band has been identified up to I π = 8+. The γ band, the K π = 2- octupole band, and a 2-quasiparticle state were also observed. The results are compared with predictions of self-consistent HFB cranking calculations and blocked-BCS multi-quasiparticle calculations.

  7. Design and implementation of a multiaxial loading capability during heating on an engineering neutron diffractometer

    DOE PAGESBeta

    Benafan, O.; Padula, S. A.; Skorpenske, H. D.; An, K.; Vaidyanathan, R.

    2014-10-02

    Here we discuss a gripping capability that was designed, implemented, and tested for in situ neutron diffraction measurements during multiaxial loading and heating on the VULCAN engineering materials diffractometer at the spallation neutron source at Oak Ridge National Laboratory.

  8. Method for measuring dose-equivalent in a neutron flux with an unknown energy spectra and means for carrying out that method

    DOEpatents

    Distenfeld, Carl H.

    1978-01-01

    A method for measuring the dose-equivalent for exposure to an unknown and/or time varing neutron flux which comprises simultaneously exposing a plurality of neutron detecting elements of different types to a neutron flux and combining the measured responses of the various detecting elements by means of a function, whose value is an approximate measure of the dose-equivalent, which is substantially independent of the energy spectra of the flux. Also, a personnel neutron dosimeter, which is useful in carrying out the above method, comprising a plurality of various neutron detecting elements in a single housing suitable for personnel to wear while working in a radiation area.

  9. Monte-Carlo simulation of an ultra small-angle neutron scattering instrument based on Soller slits

    SciTech Connect

    Rieker, T.; Hubbard, P.

    1997-09-01

    Monte Carlo simulations are used to investigate an ultra small-angle neutron scattering instrument for use at a pulsed source based on a Soller slit collimator and analyzer. The simulations show that for a q{sub min} of {approximately}le-4 {angstrom}{sup -1} (15 {angstrom} neutrons) a few tenths of a percent of the incident flux is transmitted through both collimators at q=0.

  10. Neutron-proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon-nucleus scattering data within an isospin dependent optical model

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Hua; Guo, Wen-Jun; Li, Bao-An; Chen, Lie-Wen; Fattoyev, Farrukh J.; Newton, William G.

    2015-04-01

    The neutron-proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be mn-p* ≡ (mn* - mp*) / m = (0.41 ± 0.15) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.

  11. Performance and Weight Estimates for an Advanced Open Rotor Engine

    NASA Technical Reports Server (NTRS)

    Hendricks, Eric S.; Tong, Michael T.

    2012-01-01

    NASA s Environmentally Responsible Aviation Project and Subsonic Fixed Wing Project are focused on developing concepts and technologies which may enable dramatic reductions to the environmental impact of future generation subsonic aircraft. The open rotor concept (also historically referred to an unducted fan or advanced turboprop) may allow for the achievement of this objective by reducing engine fuel consumption. To evaluate the potential impact of open rotor engines, cycle modeling and engine weight estimation capabilities have been developed. The initial development of the cycle modeling capabilities in the Numerical Propulsion System Simulation (NPSS) tool was presented in a previous paper. Following that initial development, further advancements have been made to the cycle modeling and weight estimation capabilities for open rotor engines and are presented in this paper. The developed modeling capabilities are used to predict the performance of an advanced open rotor concept using modern counter-rotating propeller designs. Finally, performance and weight estimates for this engine are presented and compared to results from a previous NASA study of advanced geared and direct-drive turbofans.

  12. Architectural development of an advanced EVA Electronic System

    NASA Technical Reports Server (NTRS)

    Lavelle, Joseph

    1992-01-01

    An advanced electronic system for future EVA missions (including zero gravity, the lunar surface, and the surface of Mars) is under research and development within the Advanced Life Support Division at NASA Ames Research Center. As a first step in the development, an optimum system architecture has been derived from an analysis of the projected requirements for these missions. The open, modular architecture centers around a distributed multiprocessing concept where the major subsystems independently process their own I/O functions and communicate over a common bus. Supervision and coordination of the subsystems is handled by an embedded real-time operating system kernel employing multitasking software techniques. A discussion of how the architecture most efficiently meets the electronic system functional requirements, maximizes flexibility for future development and mission applications, and enhances the reliability and serviceability of the system in these remote, hostile environments is included.

  13. Dose equivalent neutron dosimeter

    DOEpatents

    Griffith, Richard V.; Hankins, Dale E.; Tomasino, Luigi; Gomaa, Mohamed A. M.

    1983-01-01

    A neutron dosimeter is disclosed which provides a single measurements indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer containing conversion material such as .sup.6 Li and .sup.10 B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet. The density of conversion material in the radiator layer is of an amount which is chosen so that the density of tracks produced in the detecting sheet is proportional to the biological damage done by neutrons, regardless of whether the tracks are produced as the result of moderate energy neutrons striking the radiator layer or as the result of higher energy neutrons striking the sheet of track etch material.

  14. Secondary neutron spectrum from 250-MeV passively scattered proton therapy: Measurement with an extended-range Bonner sphere system

    SciTech Connect

    Howell, Rebecca M.; Burgett, E. A.

    2014-09-15

    Purpose: Secondary neutrons are an unavoidable consequence of proton therapy. While the neutron dose is low compared to the primary proton dose, its presence and contribution to the patient dose is nonetheless important. The most detailed information on neutrons includes an evaluation of the neutron spectrum. However, the vast majority of the literature that has reported secondary neutron spectra in proton therapy is based on computational methods rather than measurements. This is largely due to the inherent limitations in the majority of neutron detectors, which are either not suitable for spectral measurements or have limited response at energies greater than 20 MeV. Therefore, the primary objective of the present study was to measure a secondary neutron spectrum from a proton therapy beam using a spectrometer that is sensitive to neutron energies over the entire neutron energy spectrum. Methods: The authors measured the secondary neutron spectrum from a 250-MeV passively scattered proton beam in air at a distance of 100 cm laterally from isocenter using an extended-range Bonner sphere (ERBS) measurement system. Ambient dose equivalent H*(10) was calculated using measured fluence and fluence-to-ambient dose equivalent conversion coefficients. Results: The neutron fluence spectrum had a high-energy direct neutron peak, an evaporation peak, a thermal peak, and an intermediate energy continuum between the thermal and evaporation peaks. The H*(10) was dominated by the neutrons in the evaporation peak because of both their high abundance and the large quality conversion coefficients in that energy interval. The H*(10) 100 cm laterally from isocenter was 1.6 mSv per proton Gy (to isocenter). Approximately 35% of the dose equivalent was from neutrons with energies ≥20 MeV. Conclusions: The authors measured a neutron spectrum for external neutrons generated by a 250-MeV proton beam using an ERBS measurement system that was sensitive to neutrons over the entire

  15. The potential benefit of an advanced integrated utility system

    NASA Technical Reports Server (NTRS)

    Wolfer, B. M.

    1975-01-01

    The applicability of an advanced integrated utility system based on 1980 technology was investigated. An example of such a system, which provides electricity, heating and air conditioning, solid waste disposal, and water treatment in a single integrated plant, is illustrated for a hypothetical apartment complex. The system requires approximately 50 percent of the energy and approximately 55 percent of the water that would be required by a typical current conventional system.

  16. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1957-09-24

    Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are um-formly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted sunface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.

  17. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  18. Applicability of self-activation of an NaI scintillator for measurement of photo-neutrons around a high-energy X-ray radiotherapy machine.

    PubMed

    Wakabayashi, Genichiro; Nohtomi, Akihiro; Yahiro, Eriko; Fujibuchi, Toshioh; Fukunaga, Junichi; Umezu, Yoshiyuki; Nakamura, Yasuhiko; Nakamura, Katsumasa; Hosono, Makoto; Itoh, Tetsuo

    2015-01-01

    The applicability of the activation of an NaI scintillator for neutron monitoring at a clinical linac was investigated experimentally. Thermal neutron fluence rates are derived by measurement of the I-128 activity generated in an NaI scintillator irradiated by neutrons; β-rays from I-128 are detected efficiently by the NaI scintillator. In order to verify the validity of this method for neutron measurement, we irradiated an NaI scintillator at a research reactor, and the neutron fluence rate was estimated. The method was then applied to neutron measurement at a 10-MV linac (Varian Clinac 21EX), and the neutron fluence rate was estimated at the isocenter and at 30 cm from the isocenter. When the scintillator was irradiated directly by high-energy X-rays, the production of I-126 was observed due to photo-nuclear reactions, in addition to the generation of I-128 and Na-24. From the results obtained by these measurements, it was found that the neutron measurement by activation of an NaI scintillator has a great advantage in estimates of a low neutron fluence rate by use of a quick measurement following a short-time irradiation. Also, the future application of this method to quasi real-time monitoring of neutrons during patient treatments at a radiotherapy facility is discussed, as well as the method of evaluation of the neutron dose.

  19. Deinterlacing algorithm with an advanced non-local means filter

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Jeon, Gwanggil; Jeong, Jechang

    2012-04-01

    The authors introduce an efficient intra-field deinterlacing algorithm using an advanced non-local means filter. The non-local means (NLM) method has received considerable attention due to its high performance and simplicity. The NLM method adaptively obtains the missing pixel by the weighted average of the gray values of all pixels within the image, and then automatically eliminates unrelated neighborhoods from the weighted average. However, spatial location distance is another important issue for the deinterlacing method. Therefore we introduce an advanced NLM (ANLM) filter while consider neighborhood similarity and patch distance. Moreover, the search region of the conventional NLM is the whole image, while, the ANLM can just utilize the limited search region and achieve good performance and high efficiency. When compared with existing deinterlacing algorithms, the proposed algorithm improves the peak signal-to-noise-ratio while maintaining high efficiency.

  20. An increased estimate of the merger rate of double neutron stars from observations of a highly relativistic system.

    PubMed

    Burgay, M; D'Amico, N; Possenti, A; Manchester, R N; Lyne, A G; Joshi, B C; McLaughlin, M A; Kramer, M; Sarkissian, J M; Camilo, F; Kalogera, V; Kim, C; Lorimer, D R

    2003-12-01

    The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present estimates of this rate are rather low, because we know of only a few double-neutron-star binaries with merger times less than the age of the Universe. Here we report the discovery of a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic double-neutron-star binary with an orbital period of 2.4 hours. This system will merge in about 85 Myr, a time much shorter than for any other known neutron-star binary. Together with the relatively low radio luminosity of PSR J0737-3039, this timescale implies an order-of-magnitude increase in the predicted merger rate for double-neutron-star systems in our Galaxy (and in the rest of the Universe).

  1. An increased estimate of the merger rate of double neutron stars from observations of a highly relativistic system.

    PubMed

    Burgay, M; D'Amico, N; Possenti, A; Manchester, R N; Lyne, A G; Joshi, B C; McLaughlin, M A; Kramer, M; Sarkissian, J M; Camilo, F; Kalogera, V; Kim, C; Lorimer, D R

    2003-12-01

    The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present estimates of this rate are rather low, because we know of only a few double-neutron-star binaries with merger times less than the age of the Universe. Here we report the discovery of a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic double-neutron-star binary with an orbital period of 2.4 hours. This system will merge in about 85 Myr, a time much shorter than for any other known neutron-star binary. Together with the relatively low radio luminosity of PSR J0737-3039, this timescale implies an order-of-magnitude increase in the predicted merger rate for double-neutron-star systems in our Galaxy (and in the rest of the Universe). PMID:14654834

  2. Myelin basic protein reduces molecular motions in DMPA, an elastic neutron scattering study

    NASA Astrophysics Data System (ADS)

    Natali, F.; Gliozzi, A.; Rolandi, R.; Cavatorta, P.; Deriu, A.; Fasano, A.; Riccio, P.

    2001-07-01

    We have studied the effect of physiological amounts of myelin basic protein (MBP) on pure dimyristoyl L- α-phosphatidic acid (DMPA) vesicles using the elastic neutron scattering technique. Elastic scans have been performed in a wide temperature range (20-300 K). In the lower temperature region the behaviour of the integrated elastic intensity was the typical one of harmonic systems. The analysis of the Q and T dependence performed in terms of an asymmetric double well potential clearly showed that the effect of the protein consisted in a significant reduction of the conformational mobility of the DMPA bilayers and in the stabilisation of the membrane.

  3. Tagged Neutron Source for API Inspection Systems with Greatly Enhanced Spatial Resolution

    SciTech Connect

    2012-06-04

    We recently developed induced fission and transmission imaging methods with time- and directionally-tagged neutrons offer new capabilities for characterization of fissile material configurations and enhanced detection of special nuclear materials (SNM). An Advanced Associated Particle Imaging (API) generator with higher angular resolution and neutron yield than existing systems is needed to fully exploit these methods.

  4. Neutron scatter camera

    DOEpatents

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  5. Organic metal neutron detector

    DOEpatents

    Butler, Michael A.; Ginley, David S.

    1987-01-01

    A device for detecting neutrons comprises a layer of conductive polymer sandwiched between electrodes, which may be covered on each face with a neutron transmissive insulating material layer. Conventional electrodes are used for a non-imaging integrating total neutron fluence-measuring embodiment, while wire grids are used in an imaging version of the device. The change in conductivity of the polymer after exposure to a neutron flux is determined in either case to provide the desired data. Alternatively, the exposed conductive polymer layer may be treated with a chemical reagent which selectively binds to the sites altered by neutrons to produce an image of the flux detected.

  6. Determination of mass of an isolated neutron star using continuous gravitational waves with two frequency modes: an effect of a misalignment angle

    NASA Astrophysics Data System (ADS)

    Eda, Kazunari; Ono, Kenji; Itoh, Yousuke

    2016-05-01

    A rapidly spinning neutron star (NS) would emit a continuous gravitational wave (GW) detectable by the advanced LIGO, advanced Virgo, KAGRA and proposed third generation detectors such as the Einstein Telescope (ET). Such a GW does not propagate freely, but is affected by the Coulomb-type gravitational field of the NS itself. This effect appears as a phase shift in the GW depending on the NS mass. We have shown that mass of an isolated NS can, in principle, be determined if we could detect the continuous GW with two or more frequency modes. Indeed, our Monte Carlo simulations have demonstrated that mass of a NS with its ellipticity 10-6 at 1 kpc is typically measurable with precision of 20% using the ET, if the NS is precessing or has a pinned superfluid core and emits GWs with once and twice the spin frequencies. After briefly explaining our idea and results, this paper concerns with the effect of misalignment angle (“wobble angle” in the case of a precessing NS) on the mass measurement precision.

  7. New developments in APSTNG neutron probe diagnostics

    SciTech Connect

    Rhodes, E.; Dickerman, C.E.

    1995-12-31

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) show potential to allow the associated-particle diagnostic method to be moved out of the laboratory into field applications. The APSTNG interrogates the inspected object with 14-MeV neutrons generated from the deuterium-tritium reaction and detects the alpha-particle associated with each neutron inside a cone encompassing the region of interest. Gamma-ray spectra of resulting neutron reactions identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles separate the prompt and delayed gamma-ray spectra and can yield a separate coarse tomographic image of each identified nuclide, from a single orientation. Chemical substances are identified by comparing relative spectral line intensities with ratios of elements in reference compounds. The high-energy neutrons and gamma-rays penetrate large objects and dense materials. The gamma-ray dector and neutron generator can be located on the same side of the interrogated object, so spaces behind walls and other confirmed areas can be inspected. No collimators or radiation shielding are needed, the neutron generator is relatively simple and small, and commercial-grade electronics are employed. A complete system could be transported in an automotive van. Proof-of-concept laboratory experiments have been successfully performed for simulated nuclear, chemical warfare, and conventional munitions. Inspection applications have been investigated for presence of cocaine in propane tanks, uranium and plutonium smuggling, and radioactive and toxic waste characterization. An advanced APSTNG tube is being designed and constructed that will be transportable and rugged, yield a substantial neutron output increase, and provide sufficiently improved lifetime to allow operation at more than an order of magnitude increase in neutron flux.

  8. Advanced gray rod control assembly

    DOEpatents

    Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

    2013-09-17

    An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

  9. Elements of an advanced integrated operator control station

    SciTech Connect

    Clarke, M.M.; Kreifeldt, J.G.

    1984-01-01

    One of the critical determinants of peformance for any remotely operated maintenance system is the compatibility achieved between elements of the man/machine interface (e.g., master manipulator controller, controls, displays, etc.) and the human operator. In the Remote Control Engineering task of the Consolidated Fuel Reprocessing Program, considerable attention has been devoted to optimizing the man/machine interface of the operator control station. This system must be considered an integral element of the overall maintenance work system which includes transporters, manipulators, remote viewing, and other parts. The control station must reflect the integration of the operator team, control/display panels, manipulator master controllers, and remote viewing monitors. Human factors principles and experimentation have been used in the development of an advanced integrated operator control station designed for the advance servomanipulator. Key features of this next-generation design are summarized in this presentation. 7 references, 4 figures.

  10. Elements of an advanced integrated operator control station

    SciTech Connect

    Clarke, M.M.; Kreifeldt, J.G.

    1984-01-01

    One of the critical determinants of performance for any remotely operated maintenance system is the compatibility achieved between elements of the man/machine interface (e.g., master manipulator controller, controls, displays) and the human operator. In the remote control engineering task of the Consolidated Fuel Reprocessing Program, considerable attention has been devoted to optimizing the man/machine interface of the operator control station. This system must be considered an integral element of the overall maintenance work system which includes transporters, manipulators, remote viewing, and other parts. The control station must reflect the integration of the operator team, control/display panels, manipulator master controllers, and remote viewing monitors. Human factors principles and experimentation have been used in the development of an advanced integrated operator control station designed for the advance servomanipulator. Key features of this next-generation design are summarized in this presentation. 7 references, 4 figures.

  11. An advanced actuator for high-performance slewing

    NASA Technical Reports Server (NTRS)

    Downer, James; Eisenhaure, David; Hockney, Richard

    1988-01-01

    A conceptual design for an advanced momentum exchange actuator for application to spacecraft slewing is described. The particular concept is a magnetically-suspended, magnetically gimballed Control Moment Gyro (CMG). A scissored pair of these devices is sized to provide the torque and angular momentum capacity required to reorient a large spacecraft through large angle maneuvers. The concept described utilizes a composite material rotor to achieve the high momentum and energy densities to minimize system mass, an advanced superconducting magnetic suspension system to minimize system weight and power consumption. The magnetic suspension system is also capable of allowing for large angle gimballing of the rotor, thus eliminating the mass and reliability penalties attendant to conventional gimbals. Descriptions of the various subelement designs are included along with the necessary system sizing formulation and material.

  12. Neutronic reactor

    DOEpatents

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  13. NEUTRONIC REACTORS

    DOEpatents

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  14. Neutronics and Thermal Hydraulics Study for Using a Low-Enriched Uranium Core in the Advanced Test Reactor -- 2008 Final Report

    SciTech Connect

    G. S. Chang; M. A. Lillo; R. G. Ambrosek

    2008-06-01

    The Advanced Test Reactor (ATR) is a high power density and high neutron flux research reactor operating in the United States. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the large test volumes located in high flux areas, the ATR is an ideal candidate for assessing the feasibility of converting an HEU driven reactor to a low-enriched core. The present work investigates the necessary modifications and evaluates the subsequent operating effects of this conversion. A detailed plate-by-plate MCNP ATR 1/8th core model was developed and validated for a fuel cycle burnup comparison analysis. Using the current HEU U 235 enrichment of 93.0 % as a baseline, an analysis was performed to determine the low-enriched uranium (LEU) density and U-235 enrichment required in the fuel meat to yield an equivalent K-eff versus effective full power days (EFPDs) between the HEU and the LEU cores. The MCNP ATR 1/8th core model was used to optimize the U 235 loading in the LEU core, such that the differences in K-eff and heat flux profiles between the HEU and LEU cores were minimized. The depletion methodology MCWO was used to calculate K-eff versus EFPDs in this paper. The MCWO-calculated results for the LEU demonstrated adequate excess reactivity such that the K-eff versus EFPDs plot is similar to the ATR reference HEU case study. Each HEU fuel element contains 19 fuel plates with a fuel meat thickness of 0.508 mm (20 mil). In this work, the proposed LEU (U-10Mo) core conversion case with nominal fuel meat thickness of 0.330 mm (13 mil) and U-235 enrichment of 19.7 wt% is used to optimize the radial heat flux profile by varying the fuel meat thickness from 0.191 mm (7.0 mil) to 0.330 mm (13.0 mil) at the inner 4 fuel plates (1-4) and outer 4 fuel plates (16-19). A 0.8g of Boron-10, a burnable absorber, was added in the inner and outer plates to reduce the initial excess reactivity, and the peak to average ratio of the

  15. Near Real-Time Nondestructive Active Inspection Technologies Utilizing Delayed γ-Rays and Neutrons for Advanced Safeguards

    SciTech Connect

    Hunt, Alan; Reedy, E. T.E.; Mozin, V.; Tobin, S. J.

    2015-02-12

    In this two year project, the research team investigated how delayed γ-rays from short-lived fission fragments detected in the short interval between irradiating pulses can be exploited for advanced safeguards technologies. This program contained experimental and modeling efforts. The experimental effort measured the emitted spectra, time histories and correlations of the delayed γ-rays from aqueous solutions and solid targets containing fissionable isotopes. The modeling effort first developed and benchmarked a hybrid Monte Carlo simulation technique based on these experiments. The benchmarked simulations were then extended to other safeguards scenarios, allowing comparisons to other advanced safeguards technologies and to investigate combined techniques. Ultimately, the experiments demonstrated the possible utility of actively induced delayed γ-ray spectroscopy for fissionable material assay.

  16. An advanced structural analysis/synthesis capability - ACCESS 2

    NASA Technical Reports Server (NTRS)

    Schmit, L. A.; Miura, H.

    1976-01-01

    An advanced automated design procedure for minimum-weight design of structures (ACCESS 2) is reported. Design variable linking, constraint deletion, and explicit constraint approximation are used to combine effectively finite-element and nonlinear mathematical programming techniques. The approximation-concepts approach to structural synthesis is extended to problems involving fiber composite structure, thermal effects, and natural frequency constraints in addition to the usual static stress and displacement limitations. Sample results illustrating these features are given.

  17. An advanced structural analysis/synthesis capability - ACCESS 2

    NASA Technical Reports Server (NTRS)

    Schmit, L. A.; Miura, H.

    1978-01-01

    An advanced automated design procedure for minimum weight design of structures (ACCESS 2) is reported. Design variable linking, constraint deletion, and explicit constraint approximation are used to effectively combine finite element and nonlinear mathematical programming techniques. The approximation concepts approach to structural synthesis is extended to problems involving fiber composite structure, thermal effects and natural frequency constraints in addition to the usual static stress and displacement limitations. Sample results illustrating these new features are given.

  18. Overview of an Advanced Hypersonic Structural Concept Test Program

    NASA Technical Reports Server (NTRS)

    Stephens, Craig A.; Hudson, Larry D.; Piazza, Anthony

    2007-01-01

    This viewgraph presentation provides an overview of hypersonics M&S advanced structural concepts development and experimental methods. The discussion on concepts development includes the background, task objectives, test plan, and current status of the C/SiC Ruddervator Subcomponent Test Article (RSTA). The discussion of experimental methods examines instrumentation needs, sensors of interest, and examples of ongoing efforts in the development of extreme environment sensors.

  19. Structural response of an advanced combustor liner: Test and analysis

    NASA Technical Reports Server (NTRS)

    Moorhead, Paul E.; Thompson, Robert L.; Tong, M.; Higgins, M.

    1987-01-01

    An advanced (segmented) combustor liner supplied by Pratt and Whitney Aircraft was tested in the structural component test rig at Lewis Research Center. It was found that the segmented liner operated at much lower temperatures than the conventional liner (about 400 F lower) for the same heat flux. At the lower temperatures and low thermal gradients, little distortion to the segments was observed. The operating conditions were not severe enough to distort or damage the segmented liner.

  20. Personnel neutron dose assessment upgrade: Volume 2, Field neutron spectrometer for health physics applications

    SciTech Connect

    Brackenbush, L.W.; Reece, W.D.; Miller, S.D.; Endres, G.W.R.; Durham, J.S.; Scherpelz, R.I.; Tomeraasen, P.L.; Stroud, C.M.; Faust, L.G.; Vallario, E.J.

    1988-07-01

    Both the (ICRP) and the (NCPR) have recommended an increase in neutron quality factors and the adoption of effective dose equivalent methods. The series of reports entitled Personnel Neutron Dose Assessment Upgrade (PNL-6620) addresses these changes. Volume 1 in this series of reports (Personnel Neutron Dosimetry Assessment) provided guidance on the characteristics, use, and calibration of personnel neutron dosimeters in order to meet the new recommendations. This report, Volume 2: Field Neutron Spectrometer for Health Physics Applications describes the development of a portable field spectrometer which can be set up for use in a few minutes by a single person. The field spectrometer described herein represents a significant advance in improving the accuracy of neutron dose assessment. It permits an immediate analysis of the energy spectral distribution associated with the radiation from which neutron quality factor can be determined. It is now possible to depart from the use of maximum Q by determining and realistically applying a lower Q based on spectral data. The field spectrometer is made up of two modules: a detector module with built-in electronics and an analysis module with a IBM PC/reg sign/-compatible computer to control the data acquisition and analysis of data in the field. The unit is simple enough to allow the operator to perform spectral measurements with minimal training. The instrument is intended for use in steady-state radiation fields with neutrons energies covering the fission spectrum range. The prototype field spectrometer has been field tested in plutonium processing facilities, and has been proven to operate satisfactorily. The prototype field spectrometer uses a /sup 3/He proportional counter to measure the neutron energy spectrum between 50 keV and 5 MeV and a tissue equivalent proportional counter (TEPC) to measure absorbed neutron dose.

  1. An international dosimetry exchange for boron neutron capture therapy. Part I: Absorbed dose measurements.

    PubMed

    Binns, P J; Riley, K J; Harling, O K; Kiger, W S; Munck af Rosenschöld, P M; Giusti, V; Capala, J; Sköld, K; Auterinen, I; Serén, T; Kotiluoto, P; Uusi-Simola, J; Marek, M; Viererbl, L; Spurny, F

    2005-12-01

    An international collaboration was organized to undertake a dosimetry exchange to enable the future combination of clinical data from different centers conducting neutron capture therapy trials. As a first step (Part I) the dosimetry group from the Americas, represented by MIT, visited the clinical centers at Studsvik (Sweden), VTT Espoo (Finland), and the Nuclear Research Institute (NRI) at Rez (Czech Republic). A combined VTT/NRI group reciprocated with a visit to MIT. Each participant performed a series of dosimetry measurements under equivalent irradiation conditions using methods appropriate to their clinical protocols. This entailed in-air measurements and dose versus depth measurements in a large water phantom. Thermal neutron flux as well as fast neutron and photon absorbed dose rates were measured. Satisfactory agreement in determining absorbed dose within the experimental uncertainties was obtained between the different groups although the measurement uncertainties are large, ranging between 3% and 30% depending upon the dose component and the depth of measurement. To improve the precision in the specification of absorbed dose amongst the participants, the individually measured dose components were normalized to the results from a single method. Assuming a boron concentration of 15 microg g(-1) that is typical of concentrations realized clinically with the boron delivery compound boronophenylalanine-fructose, systematic discrepancies in the specification of the total biologically weighted dose of up to 10% were apparent between the different groups. The results from these measurements will be used in future to normalize treatment plan calculations between the different clinical dosimetry protocols as Part II of this study.

  2. Technological advances in bovine mastitis diagnosis: an overview.

    PubMed

    Duarte, Carla M; Freitas, Paulo P; Bexiga, Ricardo

    2015-11-01

    Bovine mastitis is an economic burden for dairy farmers and preventive control measures are crucial for the sustainability of any dairy business. The identification of etiological agents is necessary in controlling the disease, reducing risk of chronic infections and targeting antimicrobial therapy. The suitability of a detection method for routine diagnosis depends on several factors, including specificity, sensitivity, cost, time in producing results, and suitability for large-scale sampling of milk. This article focuses on current methodologies for identification of mastitis pathogens and for detection of inflammation, as well as the advantages and disadvantages of different methods. Emerging technologies, such as transcriptome and proteome analyses and nano- and microfabrication of portable devices, offer promising, sensitive methods for advanced detection of mastitis pathogens and biomarkers of inflammation. The demand for alternative, fast, and reliable diagnostic procedures is rising as farms become bigger. Several examples of technological and scientific advances are summarized which have given rise to more sensitive, reliable and faster diagnostic results.

  3. An assessment of General Aviation utilization of advanced avionics technology

    NASA Technical Reports Server (NTRS)

    Quinby, G. F.

    1980-01-01

    Needs of the general aviation industry for services and facilities which might be supplied by NASA were examined. In the data collection phase, twenty-one individuals from nine manufacturing companies in general aviation were interviewed against a carefully prepared meeting format. General aviation avionics manufacturers were credited with a high degree of technology transfer from the forcing industries such as television, automotive, and computers and a demonstrated ability to apply advanced technology such as large scale integration and microprocessors to avionics functions in an innovative and cost effective manner. The industry's traditional resistance to any unnecessary regimentation or standardization was confirmed. Industry's self sufficiency in applying advanced technology to avionics product development was amply demonstrated. NASA research capability could be supportive in areas of basic mechanics of turbulence in weather and alternative means for its sensing.

  4. Advanced glycation end products in renal failure: an overview.

    PubMed

    Noordzij, M J; Lefrandt, J D; Smit, A J

    2008-12-01

    The article aims to present an overview of the existing knowledge on advanced glycation end products (AGE). They are moieties that bind to proteins, but also lipids and nuclear acids. AGE are formed during glycation and oxidative stress. Accumulation of AGE occurs especially in diabetes and chronic renal failure and plays a major pathogenetic role. The deleterious effects of AGE result from cross-linking of proteins and activation of the receptor for advanced glycation end products. AGE accumulation can be noninvasively assessed by the skin autofluorescence reader. In diabetics, the skin autofluorescence predicts cardiac mortality and the occurrence of macro- and microvascular complications. In patients on haemodialysis, skin autofluorescence is highly elevated and predicts mortality. After renal transplantation AGE accumulation is lower than during haemodialysis, but still remains elevated and is a strong risk factor for chronic renal transplant dysfunction. Some of the potential methods to intervene with AGE accumulation are discussed in this article.

  5. JB-300: An advanced medium size transport for 2005

    NASA Technical Reports Server (NTRS)

    Debrouwer, Giles; Graham, Katherine; Ison, Jim; Juarez, Vince; Moskalik, Steve; Pankonin, Jon; Weinstein, Arnold

    1993-01-01

    In the fall of 1992, the TAC Team was presented with a Request for Proposal (PFP) for a mid-size (250-350 passenger) commercial transport. The aircraft was to be extremely competitive in the areas of passenger comfort, performance, and economic aspects. Through the use of supercritical airfoils, a technologically advanced Very High By-pass Ratio (VHBR) turbofan engine, a low overall drag configuration, a comparable interior layout, and mild use of composites, the JB-300 offers an economically viable choice to the airlines. The cents per passenger mile of the JB-300 is 1.76, which is considerably lower than current aircraft in the same range. Overall, the JB-300 is a technologically advanced aircraft, which will meet the demands of the 21st century.

  6. Advanced glycation end products in renal failure: an overview.

    PubMed

    Noordzij, M J; Lefrandt, J D; Smit, A J

    2008-12-01

    The article aims to present an overview of the existing knowledge on advanced glycation end products (AGE). They are moieties that bind to proteins, but also lipids and nuclear acids. AGE are formed during glycation and oxidative stress. Accumulation of AGE occurs especially in diabetes and chronic renal failure and plays a major pathogenetic role. The deleterious effects of AGE result from cross-linking of proteins and activation of the receptor for advanced glycation end products. AGE accumulation can be noninvasively assessed by the skin autofluorescence reader. In diabetics, the skin autofluorescence predicts cardiac mortality and the occurrence of macro- and microvascular complications. In patients on haemodialysis, skin autofluorescence is highly elevated and predicts mortality. After renal transplantation AGE accumulation is lower than during haemodialysis, but still remains elevated and is a strong risk factor for chronic renal transplant dysfunction. Some of the potential methods to intervene with AGE accumulation are discussed in this article. PMID:19090900

  7. Writing an employer-focused resume for advanced practice nurses.

    PubMed

    Welton, Robert H

    2013-01-01

    The most important new trend in resumes is the employer-focused resume. Writing one is not difficult, but it requires a change in focus. The focus of this type of resume is on the needs of prospective employers. This new resume format allows applicants to describe to prospective employers what they can provide related to the employer's needs as opposed to a simple listing of their academic and work experiences without relation to the prospective new job. This article provides advanced practice nurses with sources to guide construction of informative text about their advanced practice nursing skills and competencies using language familiar to employers. Resumes and curriculum vitae formats are compared, and advice is provided on developing content for either format. Guidelines are provided about listing credentials, identifying clinical proficiencies from student clinical practicum, using qualification summaries rather than an objective statement, choosing references, and including essential components in a cover letter.

  8. Foundational development of an advanced nuclear reactor integrated safety code.

    SciTech Connect

    Clarno, Kevin; Lorber, Alfred Abraham; Pryor, Richard J.; Spotz, William F.; Schmidt, Rodney Cannon; Belcourt, Kenneth; Hooper, Russell Warren; Humphries, Larry LaRon

    2010-02-01

    This report describes the activities and results of a Sandia LDRD project whose objective was to develop and demonstrate foundational aspects of a next-generation nuclear reactor safety code that leverages advanced computational technology. The project scope was directed towards the systems-level modeling and simulation of an advanced, sodium cooled fast reactor, but the approach developed has a more general applicability. The major accomplishments of the LDRD are centered around the following two activities. (1) The development and testing of LIME, a Lightweight Integrating Multi-physics Environment for coupling codes that is designed to enable both 'legacy' and 'new' physics codes to be combined and strongly coupled using advanced nonlinear solution methods. (2) The development and initial demonstration of BRISC, a prototype next-generation nuclear reactor integrated safety code. BRISC leverages LIME to tightly couple the physics models in several different codes (written in a variety of languages) into one integrated package for simulating accident scenarios in a liquid sodium cooled 'burner' nuclear reactor. Other activities and accomplishments of the LDRD include (a) further development, application and demonstration of the 'non-linear elimination' strategy to enable physics codes that do not provide residuals to be incorporated into LIME, (b) significant extensions of the RIO CFD code capabilities, (c) complex 3D solid modeling and meshing of major fast reactor components and regions, and (d) an approach for multi-physics coupling across non-conformal mesh interfaces.

  9. Partner for Promotion: An Innovative Advanced Community Pharmacy Practice Experience

    PubMed Central

    Legg, Julie E.; Casper, Kristin A.

    2008-01-01

    Objectives To implement the Partner for Promotion (PFP) program which was designed to enhance the skills and confidence of students and community pharmacy preceptors to deliver and expand advanced patient care services in community pharmacies and also to assess the program's impact. Design A 10-month longitudinal community advanced pharmacy practice experience was implemented that included faculty mentoring of students and preceptors via formal orientation; face-to-face training sessions; online monthly meetings; feedback on service development materials; and a web site offering resources and a discussion board. Pre- and post-APPE surveys of students and preceptors were used to evaluate perceptions of knowledge and skills. Assessment The skills survey results for the first 2 years of the PFP program suggest positive changes occurring from pre- to post-APPE survey in most areas for both students and preceptors. Four of the 7 pharmacies in 2005-2006 and 8 of the 14 pharmacies in 2006-2007 were able to develop an advanced patient care service and begin seeing patients prior to the conclusion of the APPE. As a result of the PFP program from 2005-2007, 14 new experiential sites entered into affiliation agreements with The Ohio State University College of Pharmacy. Conclusion The PFP program offers an innovative method for community pharmacy faculty members to work with students and preceptors in community pharmacies in developing patient care services. PMID:19325954

  10. PERSONNEL NEUTRON DOSIMETER

    DOEpatents

    Fitzgerald, J.J.; Detwiler, C.G. Jr.

    1960-05-24

    A description is given of a personnel neutron dosimeter capable of indicating the complete spectrum of the neutron dose received as well as the dose for each neutron energy range therein. The device consists of three sets of indium foils supported in an aluminum case. The first set consists of three foils of indium, the second set consists of a similar set of indium foils sandwiched between layers of cadmium, whereas the third set is similar to the second set but is sandwiched between layers of polyethylene. By analysis of all the foils the neutron spectrum and the total dose from neutrons of all energy levels can be ascertained.

  11. Grazing incidence neutron optics

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

    2012-01-01

    Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20 .ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

  12. Grazing Incidence Neutron Optics

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

    2013-01-01

    Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20.ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

  13. Design of an ultra low power CMOS pixel sensor for a future neutron personal dosimeter

    SciTech Connect

    Zhang, Y.; Hu-Guo, C.; Husson, D.; Hu, Y.

    2011-07-01

    Despite a continuously increasing demand, neutron electronic personal dosimeters (EPDs) are still far from being completely established because their development is a very difficult task. A low-noise, ultra low power consumption CMOS pixel sensor for a future neutron personal dosimeter has been implemented in a 0.35 {mu}m CMOS technology. The prototype is composed of a pixel array for detection of charged particles, and the readout electronics is integrated on the same substrate for signal processing. The excess electrons generated by an impinging particle are collected by the pixel array. The charge collection time and the efficiency are the crucial points of a CMOS detector. The 3-D device simulations using the commercially available Synopsys-SENTAURUS package address the detailed charge collection process. Within a time of 1.9 {mu}s, about 59% electrons created by the impact particle are collected in a cluster of 4 x 4 pixels with the pixel pitch of 80 {mu}m. A charge sensitive preamplifier (CSA) and a shaper are employed in the frond-end readout. The tests with electrical signals indicate that our prototype with a total active area of 2.56 x 2.56 mm{sup 2} performs an equivalent noise charge (ENC) of less than 400 e - and 314 {mu}W power consumption, leading to a promising prototype. (authors)

  14. Switchable radioactive neutron source device

    DOEpatents

    Boyar, Robert E.; DeVolpi, Alexander; Stanford, George S.; Rhodes, Edgar A.

    1989-01-01

    This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned with the neutron portion of the second plate to produce neutrons and brought out of alignment to cease production of neutrons.

  15. Switchable radioactive neutron source device

    DOEpatents

    Stanford, G.S.; Rhodes, E.A.; Devolpi, A.; Boyar, R.E.

    1987-11-06

    This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned with the neutron portion of the second plate to produce neutrons and brought out of alignment to cease production of neutrons. 3 figs.

  16. The neutron dose conversion coefficients calculation in human tooth enamel in an anthropomorphic phantom.

    PubMed

    Khailov, A M; Ivannikov, A I; Skvortsov, V G; Stepanenko, V F; Tsyb, A F; Trompier, F; Hoshi, M

    2010-02-01

    In the present study, MCNP4B simulation code is used to simulate neutron and photon transport. It gives the conversion coefficients that relate neutron fluence to the dose in tooth enamel (molars and pre-molars only) for 20 energy groups of monoenergetic neutrons with energies from 10-9 to 20 MeV for five different irradiation geometries. The data presented are intended to provide the basis for connection between EPR dose values and standard protection quantities defined in ICRP Publication 74. The results of the calculations for critical organs were found to be consistent with ICRP data, with discrepancies generally less than 10% for the fast neutrons. The absorbed dose in enamel was found to depend strongly on the incident neutron energy for neutrons over 10 keV. The dependence of the data on the irradiation geometry is also shown. Lower bound estimates of enamel radiation sensitivity to neutrons were made using obtained coefficients for the secondary photons. Depending on neutron energy, tooth enamel was shown to register 10-120% of the total neutron dose in the human body in the case of pure neutron exposure and AP irradiation geometry. PMID:20065707

  17. Precision neutron flux measurement with a neutron beam monitor

    NASA Astrophysics Data System (ADS)

    Ino, T.; Otono, H.; Mishima, K.; Yamada, T.

    2014-07-01

    Neutron beam monitors are regularly used in various neutron beam experiments to compare two or more sets of data taken in different experimental conditions. A neutron lifetime experiment at BL05, the NOP beamline, in J-PARC requires to monitor the initial neutron intensity with an precision of 0.1% to measure the neutron lifetime with the same accuracy. The performance of a thin 3He gas neutron beam monitor used for the experiment was studied to estimate the systematic uncertainties in the neutron lifetime measurement.

  18. Neutrons against cancer

    NASA Astrophysics Data System (ADS)

    Dovbnya, A. N.; Kuplennikov, E. L.; Kandybey, S. S.; Krasiljnikov, V. V.

    2014-09-01

    The review is devoted to the analysis and generalization of the research carried out during recent years in industrially advanced countries on the use of fast, epithermal, and thermal neutrons for therapy of malignant tumors. Basic facilities for neutron production used for cancer treatment are presented. Optimal parameters of therapeutic beams are described. Techniques using neutrons of different energy regions are discussed. Results and medical treatment efficiency are given. Comparison of the current state of neutron therapy of tumors and alternative treatments with beams of protons and carbon ions has been conducted. Main attention is given to the possibility of the practical use of accumulated experience of application of neutron beams for cancer therapy.

  19. Neutronic Reactor Design to Reduce Neutron Loss

    DOEpatents

    Miles, F. T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall. The wall is surrounded by successive layers of pure fertile material and moderator containing fertile material. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. Since the steel has a smaller capture cross section for the fast neutrons, greater nunnbers of neutrons will pass into the blanket, thereby increasing the over-all efficiency of the reactor. (AEC)

  20. NEUTRONIC REACTOR DESIGN TO REDUCE NEUTRON LOSS

    DOEpatents

    Mills, F.T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall which is surrounded by successive layers of pure fertile material and fertile material having moderator. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. As the steel has a smaller capture cross-section for the fast neutrons, then greater numbers of the neutrons will pass into the blanket thereby increasing the over-all efficiency of the reactor.