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Sample records for high neutron flux

  1. High flux compact neutron generators

    SciTech Connect

    Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J.; Vujic, J.

    2001-06-15

    Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of {approximately}10{sup 11} n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation.

  2. High-Energy Neutron Spectra and Flux Measurements Below Ground

    NASA Astrophysics Data System (ADS)

    Roecker, Caleb; Bernstein, Adam; Marleau, Peter; Vetter, Kai

    2016-03-01

    High-energy neutrons are a ubiquitous and often poorly measured background. Below ground, these neutrons could potentially interfere with antineutrino based reactor monitoring experiments as well as other rare-event neutral particle detectors. We have designed and constructed a transportable fast neutron detection system for measuring neutron energy spectra and flux ranging from tens to hundreds of MeV. The spectrometer uses a multiplicity technique in order to have a higher effective area than traditional transportable high-energy neutron spectrometers. Transportability ensures a common detector-related systematic bias for future measurements. The spectrometer is composed of two Gd containing plastic scintillator detectors arranged around a lead spallation target. A high-energy neutron may interact in the lead producing many secondary neutrons. The detector records the correlated secondary neutron multiplicity. Over many events, the response can be used to infer the incident neutron energy spectrum and flux. As a validation of the detector response, surface measurements have been performed; results confirm agreement with previous experiments. Below ground measurements have been performed at 3 depths (380, 600, and 1450 m.w.e.); results from these measurements will be presented.

  3. Neutronics Modeling of the High Flux Isotope Reactor using COMSOL

    SciTech Connect

    Chandler, David; Primm, Trent; Freels, James D; Maldonado, G Ivan

    2011-01-01

    The High Flux Isotope Reactor located at the Oak Ridge National Laboratory is a versatile 85 MWth research reactor with cold and thermal neutron scattering, materials irradiation, isotope production, and neutron activation analysis capabilities. HFIR staff members are currently in the process of updating the thermal hydraulic and reactor transient modeling methodologies. COMSOL Multiphysics has been adopted for the thermal hydraulic analyses and has proven to be a powerful finite-element-based simulation tool for solving multiple physics-based systems of partial and ordinary differential equations. Modeling reactor transients is a challenging task because of the coupling of neutronics, heat transfer, and hydrodynamics. This paper presents a preliminary COMSOL-based neutronics study performed by creating a two-dimensional, two-group, diffusion neutronics model of HFIR to study the spatially-dependent, beginning-of-cycle fast and thermal neutron fluxes. The 238-group ENDF/B-VII neutron cross section library and NEWT, a two-dimensional, discrete-ordinates neutron transport code within the SCALE 6 code package, were used to calculate the two-group neutron cross sections required to solve the diffusion equations. The two-group diffusion equations were implemented in the COMSOL coefficient form PDE application mode and were solved via eigenvalue analysis using a direct (PARDISO) linear system solver. A COMSOL-provided adaptive mesh refinement algorithm was used to increase the number of elements in areas of largest numerical error to increase the accuracy of the solution. The flux distributions calculated by means of COMSOL/SCALE compare well with those calculated with benchmarked three-dimensional MCNP and KENO models, a necessary first step along the path to implementing two- and three-dimensional models of HFIR in COMSOL for the purpose of studying the spatial dependence of transient-induced behavior in the reactor core.

  4. Designing CNR, a very high thermal neutron flux facility

    SciTech Connect

    Difilippo, F.C.

    1986-01-01

    According to a recent study (Eastman-Seitz Committee, National Academy of Science) there is a need for a new generation of steady neutron sources with a thermal neutron flux peak between 5 to 10 times 10/sup 15//cm/sup 2/ sec. Ideally the neutron source would have to operate continuously for several days (two weeks at least) with minimum time (2 to 3 days) for refueling and/or maintenance and it would also be used to irradiate materials and produce isotopes. This paper describes the preliminary design of the nuclear reactor for the proposed Center for Neutron Research (CNR). A duplication of existing designs (HFIR, (ORNL), ILL (Grenoble, France)) would imply high total power and small core life; the necessity of higher efficiencies (in terms of peak-flux-per-unit source or power) then becomes apparent. We have found analytical expressions for the efficiency in terms of a few parameters such as the volume of the source and the Fermi age and diffusion length of thermal neutrons in both the source and reflector regions. A single analytical expression can then be used for scoping the design and to intercompare radically different designs. Higher efficiencies can be achieved by reducing the volume and the moderation of a core immersed in a very low absorbing reflector; on the contrary a very long core life has a negative effect on the efficiency at beginning of life. Consequently, and after detailed calculations, we have found a candidate design with the following characteristics: core, U/sub 3/Si/sub 2/, 93% enriched, 18.1-kg /sup 235/U, metal fraction 50%, Al cladding, and 35-L volume; reflector and moderator, D/sub 2/O; efficiency at end of life (EOL) with respect to the ILL reactor, 1.29; flux at EOL, 10 x 10/sup 15//cm/sup 2/ sec (power in core 270. MW); core life, 14 days; burnup 28.4%.

  5. Neutronic calculations for a new high flux reactor

    SciTech Connect

    Difilippo, F.C.; Worley, B.A.; Vondy, D.R.

    1985-01-01

    The Oak Ridge National Laboratory has begun the design of a new high flux reactor to be used for basic research, isotope production, and material irradiation. One of the principal goals of the design is the production of a thermal flux peak in the reflector larger than 5 x 10/sup 15//cm/sup 2/sec. A theoretical analysis of the slowing-down and diffusion of neutrons produced by a spherical fission source immersed in a moderator shows that the flux per unit power is maximized by combining a very undermoderated core with a very low absorbing reflector. The theoretical model interrelates total power, power density and transport properties with the thermal flux allowing very inexpensive scoping calculations. Full scale and detailed calculations were made with a numerical model which uses the Bold Venture code system. Calculations show that a highly enriched /sup 235/U reactor with D/sub 2/O as moderator and reflector would produce the desired peak flux, and the reactor would have a reasonable core life.

  6. High Flux Isotope Reactor cold neutron source reference design concept

    SciTech Connect

    Selby, D.L.; Lucas, A.T.; Hyman, C.R.

    1998-05-01

    In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.

  7. Neutron diffraction facilities at the high flux reactor, Petten

    NASA Astrophysics Data System (ADS)

    Ohms, C.; Youtsos, A. G.; Bontenbal, A.; Mulder, F. M.

    2000-03-01

    The High Flux Reactor in Petten is equipped with twelve beam tubes for the extraction of thermal neutrons for applications in materials and medical science. Beam tubes HB4 and HB5 are equipped with diffractometers for residual stress and powder investigations. Recently at HB4 the Large Component Neutron Diffraction Facility has been installed. It is a unique facility with respect to its capability of handling heavy components up to 1000 kg in residual stress testing. Its basic features are described and the first applications on thick piping welds are shown. The diffractometer at HB5 can be set up for powder and stress measurements. Recent applications include temperature dependent measurements on phase transitions in intermetallic compounds and on Li ion energy storage materials.

  8. Characterization of neutron yield and x-ray spectra of a High Flux Neutron Generator (HFNG)

    NASA Astrophysics Data System (ADS)

    Nnamani, Nnaemeka; HFNG Collaboration

    2015-04-01

    The High Flux Neutron Generator (HFNG) is a DD plasma-based source, with a self-loading target intended for fundamental science and engineering applications, including 40 Ar/39 Ar geochronology, neutron cross section measurements, and radiation hardness testing of electronics. Our first estimate of the neutron yield, based on the population of the 4.486 hour 115 In isomer gave a neutron yield of the order 108 n/sec; optimization is ongoing to achieve the design target of 1011 n/sec. Preliminary x-ray spectra showed prominent energy peaks which are likely due to atomic line-emission from back-streaming electrons accelerated up to 100 keV impinging on various components of the HFNG chamber. Our x-ray and neutron diagnostics will aid us as we continue to evolve the design to suppress back-streaming electrons, necessary to achieve higher plasma beam currents, and thus higher neutron flux. This talk will focus on the characterization of the neutron yield and x-ray spectra during our tests. A collimation system is being installed near one of the chamber ports for improved observation of the x-ray spectra. This work is supported by NSF Grant No. EAR-0960138, U.S. DOE LBNL Contract No. DE-AC02-05CH11231, U.S. DOE LLNL Contract No. DE-AC52-07NA27344, and the UC Office of the President Award 12-LR-238745.

  9. Development of high flux thermal neutron generator for neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Vainionpaa, Jaakko H.; Chen, Allan X.; Piestrup, Melvin A.; Gary, Charles K.; Jones, Glenn; Pantell, Richard H.

    2015-05-01

    The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5 eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3-5 · 107 n/cm2/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ∼2 · 1010 n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5 MeV neutrons are quickly thermalized to energies below 0.5 eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

  10. Gamma-ray-spectroscopy following high-flux 14-MeV neutron activation

    SciTech Connect

    Williams, R.E.

    1981-10-12

    The Rotating Target Neutron Source (RTNS-I), a high-intensity source of 14-MeV neutrons at the Lawrence Livermore National Laboratory (LLNL), has been used for applications in activation analysis, inertial-confinement-fusion diagnostic development, and fission decay-heat studies. The fast-neutron flux from the RTNS-I is at least 50 times the maximum fluxes available from typical neutron generators, making these applications possible. Facilities and procedures necessary for gamma-ray spectroscopy of samples irradiated at the RTNS-I were developed.

  11. Simulation of the Performance of a Fundamental Neutron Physics Beamline at the High Flux Isotope Reactor

    SciTech Connect

    Mahurin, R.; Greene, Geoffrey L; Koehler, Paul Edward; Cianciolo, Vince

    2005-05-01

    We study the expected performance of the proposed fundamental neutron physics beamline at the upgraded High Flux Isotope Reactor at Oak Ridge National Laboratory. A curved neutron guide transmits the neutrons from the new cold source into a guide hall. A novel feature of the proposed guide is the use of vertical focusing to increase the flux for experiments that require relatively small cross-section beams. We use the simulation code IB to model straight, multi-channel curved, and tapered guides of various m values. Guide performance for the current NPDGamma and proposed abBA experiments is evaluated.

  12. Simulation of the Performance of a Fundamental Neutron Physics Beamline at the High Flux Isotope Reactor

    PubMed Central

    Mahurin, Rob; Greene, Geoffrey; Kohler, Paul; Cianciolo, Vince

    2005-01-01

    We study the expected performance of the proposed fundamental neutron physics beamline at the upgraded High Flux Isotope Reactor at Oak Ridge National Laboratory. A curved neutron guide transmits the neutrons from the new cold source into a guide hall. A novel feature of the proposed guide is the use of vertical focussing to increase the flux for experiments that require relatively small cross-section beams. We use the simulation code IB to model straight, multi-channel curved, and tapered guides of various m values. Guide performance for the current NPDGamma and proposed abBA experiments is evaluated. PMID:27308114

  13. Simulation of the Performance of a Fundamental Neutron Physics Beamline at the High Flux Isotope Reactor.

    PubMed

    Mahurin, Rob; Greene, Geoffrey; Kohler, Paul; Cianciolo, Vince

    2005-01-01

    We study the expected performance of the proposed fundamental neutron physics beamline at the upgraded High Flux Isotope Reactor at Oak Ridge National Laboratory. A curved neutron guide transmits the neutrons from the new cold source into a guide hall. A novel feature of the proposed guide is the use of vertical focussing to increase the flux for experiments that require relatively small cross-section beams. We use the simulation code IB to model straight, multi-channel curved, and tapered guides of various m values. Guide performance for the current NPDGamma and proposed abBA experiments is evaluated. PMID:27308114

  14. Operation Hardtack. Project 2. 6. Neutron flux from very-high-altitude bursts

    SciTech Connect

    Hanscome, T.D.; Alers, P.B.; Caldwell, P.A.; Drachman, R.J.; Gorbics, S.G.

    1985-09-01

    The primary objective of this project was to measure neutron flux and gamma-ray flux versus range and time from missile-borne, megaton nuclear detonations at high altitudes by means of instrumented pods that were to be ejected, during the missile thrust period, at times that were selected to position the pods at predetermined distances from the burst. Specific objectives were: (1) neutron flux versus time was to be measured at each of three pod positions during each shot and (2) a measurement of gamma-ray dose rate versus time was sought from each pod during each shot.

  15. Progress on the realization of a new GEM based neutron diagnostic concept for high flux neutron beams

    SciTech Connect

    Croci, G.; Tardocchi, M.; Rebai, M.; Cippo, E. Perelli; Gorini, G.; Cazzaniga, C.; Palma, M. Dalla; Pasqualotto, R.; Tollin, M.; Grosso, G.; Muraro, A.; Murtas, F.; Claps, G.; Cavenago, M.

    2014-08-21

    Fusion reactors will need high flux neutron detectors to diagnose the deuterium-deuterium and deuterium-tritium. A candidate detection technique is the Gas Electron Multiplier (GEM). New GEM based detectors are being developed for application to a neutral deuterium beam test facility. The proposed detection system is called Close-contact Neutron Emission Surface Mapping (CNESM). The diagnostic aims at providing the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. This is done by placing a detector in close contact, right behind the dump. CNESM uses nGEM detectors, i.e. GEM detectors equipped with a cathode that also serves as neutron-proton converter foil. After the realization and test of several small area prototypes, a full size prototype has been realized and tested with laboratory sources. Test on neutron beams are foreseen for the next months.

  16. Progress on the realization of a new GEM based neutron diagnostic concept for high flux neutron beams

    NASA Astrophysics Data System (ADS)

    Croci, G.; Rebai, M.; Cazzaniga, C.; Palma, M. Dalla; Grosso, G.; Muraro, A.; Murtas, F.; Claps, G.; Pasqualotto, R.; Cippo, E. Perelli; Tardocchi, M.; Tollin, M.; Cavenago, M.; Gorini, G.

    2014-08-01

    Fusion reactors will need high flux neutron detectors to diagnose the deuterium-deuterium and deuterium-tritium. A candidate detection technique is the Gas Electron Multiplier (GEM). New GEM based detectors are being developed for application to a neutral deuterium beam test facility. The proposed detection system is called Close-contact Neutron Emission Surface Mapping (CNESM). The diagnostic aims at providing the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. This is done by placing a detector in close contact, right behind the dump. CNESM uses nGEM detectors, i.e. GEM detectors equipped with a cathode that also serves as neutron-proton converter foil. After the realization and test of several small area prototypes, a full size prototype has been realized and tested with laboratory sources. Test on neutron beams are foreseen for the next months.

  17. COMPTEL measurements of the omnidirectional high-energy neutron flux in near-earth orbit.

    PubMed

    Morris, D J; Aarts, H; Bennett, K; Lockwood, J A; McConnell, M L; Ryan, J M; Schonfelder, V; Steinle, H; Weidenspointner, G

    1998-01-01

    On four occasions, twice in 1991 (near solar maximum) and twice in 1994 (near solar minimum), one COMPTEL D1 detector module was used as an omnidirectional detector to measure the high-energy (> 12.8 MeV) neutron flux near an altitude of 450 km. The D1 modules are cylindrical, with radius 13.8 cm and depth 8 cm, and are filled with liquid scintillator (NE213A). The combined flux measurements can be fit reasonably well by a product of the Mt. Washington neutron monitor rate, a linear function in the spacecraft geocenter zenith angle, and an exponential function of the vertical geomagnetic cutoff rigidity in which the coefficient of the rigidity is a linear function of the neutron monitor rate. When pointed at the nadir, the flux is consistent with that expected from the atmospheric neutron albedo alone. When pointed at the zenith the flux is reduced by a factor of about 0.54. Thus the production of secondary neutrons in the massive (16000 kg) Compton Gamma-Ray Observatory spacecraft is negligible. Rather, the mass of the spacecraft provides shielding from the earth albedo. PMID:11542901

  18. NEUTRON FLUX INTENSITY DETECTION

    DOEpatents

    Russell, J.T.

    1964-04-21

    A method of measuring the instantaneous intensity of neutron flux in the core of a nuclear reactor is described. A target gas capable of being transmuted by neutron bombardment to a product having a resonance absorption line nt a particular microwave frequency is passed through the core of the reactor. Frequency-modulated microwave energy is passed through the target gas and the attenuation of the energy due to the formation of the transmuted product is measured. (AEC)

  19. Neutron Spectral Brightness of Cold Guide 4 at the High Flux Isotope Reactor

    SciTech Connect

    Winn, B. L.; Robertson, J. L.; Iverson, Erik B.; Selby, D. L.

    2009-05-03

    The High Flux Isotope Reactor resumed operation in June of 2007 with a super-critical hydrogen cold source in horizontal beam tube 4. Cold guide 4 is a guide system designed to deliver neutrons from this source at reasonable flux at wavelengths greater than 4 Å to several instruments, and includes a 15-m, 96-section, 4-channel bender. A time-of-flight spectrum with calibrated detector was recorded at port C of cold guide 4, and compared to McStas simulations, to generate a brightness spectrum.

  20. Neutron Radiography Facility at IBR-2 High Flux Pulsed Reactor: First Results

    NASA Astrophysics Data System (ADS)

    Kozlenko, D. P.; Kichanov, S. E.; Lukin, E. V.; Rutkauskas, A. V.; Bokuchava, G. D.; Savenko, B. N.; Pakhnevich, A. V.; Rozanov, A. Yu.

    A neutron radiography and tomography facilityhave been developed recently at the IBR-2 high flux pulsed reactor. The facility is operated with the CCD-camera based detector having maximal field of view of 20x20 cm, and the L/D ratio can be varied in the range 200 - 2000. The first results of the radiography and tomography experiments with industrial materials and products, paleontological and geophysical objects, meteorites, are presented.

  1. High-flux neutron source based on a liquid-lithium target

    SciTech Connect

    Halfon, S.; Feinberg, G.; Paul, M.; Arenshtam, A.; Berkovits, D.; Kijel, D.; Nagler, A.; Eliyahu, I.; Silverman, I.

    2013-04-19

    A prototype compact Liquid Lithium Target (LiLiT), able to constitute an accelerator-based intense neutron source, was built. The neutron source is intended for nuclear astrophysical research, boron neutron capture therapy (BNCT) in hospitals and material studies for fusion reactors. The LiLiT setup is presently being commissioned at Soreq Nuclear research Center (SNRC). The lithium target will produce neutrons through the {sup 7}Li(p,n){sup 7}Be reaction and it will overcome the major problem of removing the thermal power generated by a high-intensity proton beam, necessary for intense neutron flux for the above applications. The liquid-lithium loop of LiLiT is designed to generate a stable lithium jet at high velocity on a concave supporting wall with free surface toward the incident proton beam (up to 10 kW). During off-line tests, liquid lithium was flown through the loop and generated a stable jet at velocity higher than 5 m/s on the concave supporting wall. The target is now under extensive test program using a high-power electron-gun. Up to 2 kW electron beam was applied on the lithium flow at velocity of 4 m/s without any flow instabilities or excessive evaporation. High-intensity proton beam irradiation will take place at SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator currently in commissioning at SNRC.

  2. High-flux neutron source based on a liquid-lithium target

    NASA Astrophysics Data System (ADS)

    Halfon, S.; Feinberg, G.; Paul, M.; Arenshtam, A.; Berkovits, D.; Kijel, D.; Nagler, A.; Eliyahu, I.; Silverman, I.

    2013-04-01

    A prototype compact Liquid Lithium Target (LiLiT), able to constitute an accelerator-based intense neutron source, was built. The neutron source is intended for nuclear astrophysical research, boron neutron capture therapy (BNCT) in hospitals and material studies for fusion reactors. The LiLiT setup is presently being commissioned at Soreq Nuclear research Center (SNRC). The lithium target will produce neutrons through the 7Li(p,n)7Be reaction and it will overcome the major problem of removing the thermal power generated by a high-intensity proton beam, necessary for intense neutron flux for the above applications. The liquid-lithium loop of LiLiT is designed to generate a stable lithium jet at high velocity on a concave supporting wall with free surface toward the incident proton beam (up to 10 kW). During off-line tests, liquid lithium was flown through the loop and generated a stable jet at velocity higher than 5 m/s on the concave supporting wall. The target is now under extensive test program using a high-power electron-gun. Up to 2 kW electron beam was applied on the lithium flow at velocity of 4 m/s without any flow instabilities or excessive evaporation. High-intensity proton beam irradiation will take place at SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator currently in commissioning at SNRC.

  3. Glass-fiber-based neutron detectors for high- and low-flux environments

    NASA Astrophysics Data System (ADS)

    Bliss, Mary; Brodzinski, Ronald L.; Craig, Richard A.; Geelhood, Bruce D.; Knopf, Michael A.; Miley, Harry S.; Perkins, Richard W.; Reeder, Paul L.; Sunberg, Debra S.; Warner, Ray A.; Wogman, Ned A.

    1995-09-01

    Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers typically have a operational transmission length (e(superscript -1) length) of greater than 2 meters. This permits the fabrication of devices which were not possible to consider. Scintillating fibers permit conformable devices, large-area devices, and extremely small devices; in addition, as the thermal-neutron sensitive elements in a fast neutron detection system, scintillating fibers can be dispersed within moderator, improving neutron economy, over that possible with commercially available (superscript 3)He or BF(subscript 3) proportional counters. These fibers can be used for national-security applications, in medical applications, in the nuclear-power industry, and for personnel protection at experimental facilities. Data are presented for devices based on single fibers and devices made up of ribbons containing many fibers under high-and low-flux conditions.

  4. High-Flux Neutron Generator Facility for Geochronology and Nuclear Physics Research

    NASA Astrophysics Data System (ADS)

    Waltz, Cory; HFNG Collaboration

    2015-04-01

    A facility based on a next-generation, high-flux D-D neutron generator (HFNG) is being commissioned at UC Berkeley. The generator is designed to produce monoenergetic 2.45 MeV neutrons at outputs exceeding 1011 n/s. The HFNG is designed around two RF-driven multi-cusp ion sources that straddle a titanium-coated copper target. D + ions, accelerated up to 150 keV from the ion sources, self-load the target and drive neutron generation through the d(d,n)3 He fusion reaction. A well-integrated cooling system is capable of handling beam power reaching 120 kW impinging on the target. The unique design of the HFNG target permits experimental samples to be placed inside the target volume, allowing the samples to receive the highest neutron flux (1011 cm-2 s-1) possible from the generator. In addition, external beams of neutrons will be available simultaneously, ranging from thermal to 2.45 MeV. Achieving the highest neutron yields required carefully designed schemes to mitigate back-streaming of high energy electrons liberated from the cathode target by deuteron bombardment. The proposed science program is focused on pioneering advances in the 40 Ar/39 Ar dating technique for geochronology, new nuclear data measurements, basic nuclear science, and education. An end goal is to become a user facility for researchers. This work is supported by NSF Grant No. EAR-0960138, U.S. DOE LBNL Contract No. DE-AC02-05CH11231, U.S. DOE LLNL Contract No. DE-AC52-07NA27344, and UC Office of the President Award 12-LR-238745.

  5. Awareness, Preference, Utilization, and Messaging Research for the Spallation Neutron Source and High Flux Isotope Reactor

    SciTech Connect

    Bryant, Rebecca; Kszos, Lynn A

    2011-03-01

    Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world, and the SNS is one of the world's most intense pulsed neutron beams. Management of these two resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD commissioned this survey research to develop baseline information regarding awareness of and perceptions about neutron science. Specific areas of investigative interest include the following: (1) awareness levels among those in the scientific community about the two neutron sources that ORNL offers; (2) the level of understanding members of various scientific communities have regarding benefits that neutron scattering techniques offer; and (3) any perceptions that negatively impact utilization of the facilities. NScD leadership identified users of two light sources in North America - the Advanced Photon Source (APS) at Argonne National Laboratory and the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory - as key publics. Given the type of research in which these scientists engage, they would quite likely benefit from including the neutron techniques available at SNS and HFIR among their scientific investigation tools. The objective of the survey of users of APS, NSLS, SNS, and HFIR was to explore awareness of and perceptions regarding SNS and HFIR among those in selected scientific communities. Perceptions of SNS and FHIR will provide a foundation for strategic communication plan development and for developing key educational messages. The survey was conducted in two phases. The first phase included qualitative methods of (1) key stakeholder meetings; (2) online interviews with user administrators of APS and NSLS; and (3) one-on-one interviews

  6. First result of deuterium retention in neutron-irradiated tungsten exposed to high flux plasma in TPE

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Hatano, Y.; Calderoni, P.; Oda, T.; Oya, Y.; Sokolov, M.; Zhang, K.; Cao, G.; Kolasinski, R.; Sharpe, J. P.

    2011-08-01

    With the Japan-US joint research project Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), an initial set of tungsten samples (99.99% purity, A.L.M.T. Co.) were irradiated by high flux neutrons at 323 K to 0.025 dpa in High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Subsequently, one of the neutron-irradiated tungsten samples was exposed to a high-flux deuterium plasma (ion flux: 5 × 1021 m-2 s-1, ion fluence: 4 × 1025 m-2) in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory (INL). The deuterium retention in the neutron-irradiated tungsten was 40% higher in comparison to the unirradiated tungsten. The observed broad desorption spectrum from neutron-irradiated tungsten and associated TMAP modeling of the deuterium release suggest that trapping occurs in the bulk material at more than three different energy sites.

  7. New measurement system for on line in core high-energy neutron flux monitoring in materials testing reactor conditions

    SciTech Connect

    Geslot, B.; Filliatre, P.; Barbot, L.; Jammes, C.; Breaud, S.; Oriol, L.; Villard, J.-F.; Lopez, A. Legrand

    2011-03-15

    Flux monitoring is of great interest for experimental studies in material testing reactors. Nowadays, only the thermal neutron flux can be monitored on line, e.g., using fission chambers or self-powered neutron detectors. In the framework of the Joint Instrumentation Laboratory between SCK-CEN and CEA, we have developed a fast neutron detector system (FNDS) capable of measuring on line the local high-energy neutron flux in fission reactor core and reflector locations. FNDS is based on fission chambers measurements in Campbelling mode. The system consists of two detectors, one detector being mainly sensitive to fast neutrons and the other one to thermal neutrons. On line data processing uses the CEA depletion code DARWIN in order to disentangle fast and thermal neutrons components, taking into account the isotopic evolution of the fissile deposit. The first results of FNDS experimental test in the BR2 reactor are presented in this paper. Several fission chambers have been irradiated up to a fluence of about 7 x 10{sup 20} n/cm{sup 2}. A good agreement (less than 10% discrepancy) was observed between FNDS fast flux estimation and reference flux measurement.

  8. Upgrade of the wide-angle neutron diffractometer at the high flux isotope reactor

    SciTech Connect

    Katano, S.; Morii, Y.; Child, H.R.

    1997-07-15

    The Wide-Angle Neutron Diffractometer (WAND) is a flat-cone geometry diffractometer located at the High Flux Reactor (HFIR). This instrument is currently being upgraded. The central part of this upgrade is the development of a new curved one-dimensional position sensitive detector which covers a 125 degree angular range with an effective radius of 71 cm. This detector will be a multi-anode (624 anodes on a 0.2 degree pitch) {sup 3}He gas-filled proportional counter. This totally new system will give high resolution, good uniformity and high counting range - a maximum capability of 10{sup 5} cps/pixel and a 10{sup 7} cps overall. A prototype of this detector has shown that these design targets can be met. The new WAND will greatly broaden its capabilities for single-crystal diffraction experiments and for time-resolved measurements.

  9. Spacecraft-produced neutron fluxes on Skylab

    NASA Technical Reports Server (NTRS)

    Quist, T. C.; Furst, M.; Burnett, D. S.; Baum, J. H.; Peacock, C. L., Jr.; Perry, D. G.

    1977-01-01

    Estimates of neutron fluxes in different energy ranges are reported for the Skylab spacecraft. Detectors composed of uranium, thorium, and bismuth foils with mica as a fission track recorder, as well as boron foils with cellulose acetate as an alpha-particle recorder, were deployed at different positions in the Orbital Workshop. It was found that the Skylab neutron flux was dominated by high energy (greater than 1 MeV) contributions and that there was no significant time variation in the fluxes. Firm upper limits of 7-15 neutrons/sq cm-sec, depending on the detector location in the spacecraft, were established for fluxes above 1 MeV. Below 1 MeV, the neutron fluxes were about an order of magnitude lower. The neutrons are interpreted as originating from the interactions of leakage protons from the radiation belt with the spacecraft.

  10. A neutronic feasibility study for LEU conversion of the high flux isotope reactor (HFIR).

    SciTech Connect

    Mo, S. C.

    1998-01-14

    A neutronic feasibility study was performed to determine the uranium densities that would be required to convert the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) from HEU (93%) to LEU (<20%)fuel. The LEU core that was studied is the same as the current HEU core, except for potential changes in the design of the fuel plates. The study concludes that conversion of HFIR from HEU to LEU fuel would require an advanced fuel with a uranium density of 6-7 gU/cm{sup 3} in the inner fuel element and 9-10 gU/cm{sup 3} in the outer fuel element to match the cycle length of the HEU core. LEU fuel with uranium density up to 4.8 gU/cm{sup 3} is currently qualified for research reactor use. Modifications in fuel grading and burnable poison distribution are needed to produce an acceptable power distribution.

  11. A U.S. high-flux neutron facility for fusion materials development

    SciTech Connect

    Rei, Donald J

    2010-01-01

    Materials for a fusion reactor first wall and blanket structure must be able to reliably function in an extreme environment that includes 10-15 MW-year/m{sup 2} neutron and heat fluences. The various materials and structural challenges are as difficult and important as achieving a burning plasma. Overcoming radiation damage degradation is the rate-controlling step in fusion materials development. Recent advances with oxide dispersion strengthened ferritic steels show promise in meeting reactor requirements, while multi-timescale atomistic simulations of defect-grain boundary interactions in model copper systems reveal surprising self-annealing phenomenon. While these results are promising, simultaneous evaluation of radiation effects displacement damage ({le} 200 dpa) and in-situ He generation ({le} 2000 appm) at prototypical reactor temperatures and chemical environments is still required. There is currently no experimental facility in the U.S. that can meet these requirements for macroscopic samples. The E.U. and U.S. fusion communities have recently concluded that a fusion-relevant, high-flux neutron source for accelerated characterization of the effects of radiation damage to materials is a top priority for the next decade. Data from this source will be needed to validate designs for the multi-$B next-generation fusion facilities such as the CTF, ETF, and DEMO, that are envisioned to follow ITER and NIF.

  12. High-flux white neutron source based on p(35)-Be reactions for activation experiments at NPI

    NASA Astrophysics Data System (ADS)

    Stefanik, Milan; Bem, Pavel; Gotz, Miloslav; Katovsky, Karel; Majerle, Mitja; Novak, Jan; Simeckova, Eva

    2014-11-01

    The concept of International Fusion Material Irradiation Facility (IFMIF) is based on the d(40)-Li neutron source reaction which produces the white neutron spectrum with mean energy of 14 MeV, energy range with high intensity of neutron beam up to 35 MeV, and weak tail up to 55 MeV. At the Nuclear Physics Institute of the ASCR in Rez near Prague, the source reaction of p+Be was investigated for proton energy of 35 MeV and beam current intensity of 9.2 μA. The produced white spectrum with neutron flux up to 1011 cm-2 s-1 was determined by the dosimetry foils activation technique at two sample-to-target distances and validated against the Monte Carlo predictions. The neutron field of these high-flux p(35)-Be white neutron source represents the useful tool for experimental simulation of the spectrum of the IFMIF facility, validating the activation cross-section data in the energy range relevant to the IFMIF, studying the radiation hardness of electronics against the high-energy neutron fields, and various activation experiments.

  13. Neutron optics of the ILL high-flux polarized neutron three-axis spectrometer IN20B

    NASA Astrophysics Data System (ADS)

    Kulda, Jiri; Courtois, Pierre; Saroun, Jan; Thomas, Michel; Enderle, M.; Flores, P.

    2001-11-01

    The three-axis spectrometer IN20 has been upgraded to enhance significantly the data collection rate in experiments using polarized neutrons to study magnetic excitations in the (higher) thermal energy range. To increase the monochromatic polarized neutron flux, a new geometry of the primary spectrometer, optimized by detailed ray-tracing simulations, has been adopted. The main ingredients are a neutron source of a diameter increased from 100 mm to 170 mm and a large double focusing monochromator, illuminated through a heavy input slit (virtual source) of adjustable width. This geometry permits to keep the background at a possibly low level while maximizing the solid angle available for monochromatic focusing. The real challenge of the project has been the new Heusler monochromator. With its active surface of 230 x 150 mm2, consisting of 75 crystal plates mounted in 15 columns, it is the largest polarizing crystal assembly ever built. In combination with the horizontally focusing analyzer of a similar design, implemented in spring 2000, the data collection rate in the polarization analysis mode has increased by a factor 30 - 50 in April 2001 as compared to the original IN20, which up to now has provided world's highest polarized neutron flux in the thermal energy range.

  14. Monte Carlo simulations for high-rate fast neutron flux measurements made at the RAON neutron science facility by using MICROMEGAS

    NASA Astrophysics Data System (ADS)

    Hwang, Dae Hee; Hong, Ser Gi; Kim, Jae Cheon; Kim, Gi Dong; Kim, Yong Kyun

    2015-10-01

    RAON is a Korean heavy-ion accelerator complex that is planned to be built by 2021. Deuterons (53 MeV) and protons (88 MeV) accelerated by using a low-energy driver linac (SCL1) are delivered to the neutron production target in the Neutron Science Facility (NSF) to produce high-energy neutrons in the interval from 1 to 88 MeV with high fluxes of the order of 1012 n/cm2-sec. The repetition rate of the neutron beam ranges from 1 kHz to 1 MHz, and the maximum beam current is ~12 μA at 1 MHz. The beam width is 1 ~ 2 ns. The high-energy and high-rate fast neutrons are used to estimate accurate neutron-induced cross sections for various nuclides at the NSF. A MICROMEGAS (MICRO Mesh Gaseous Structure), which is a gaseous detector initially developed for tracking in high-rate, high-energy physics experiments, is tentatively being considered as a neutron beam monitor. It can be used to measure both the energy distribution and the flux of the neutron beam. In this study, a MICROMEGAS detector for installation at the NSF was designed and investigated. 6Li, 10B, 235U and 238U targets are being considered as neutron/charged particle converters. For the low-energy region, 6Li(n,α)t and 10B(n,α)7Li are used in the energy range from thermal to 1 MeV. 235U(n,f) and 238U(n,f) reactions are used for high-energy region up to 90 MeV. All calculations are performed by using the GEANT4 toolkit.

  15. Three-dimensional calculations of neutron streaming in the beam tubes of the ORNL HFIR (High Flux Isotope Reactor) Reactor

    SciTech Connect

    Childs, R.L.; Rhoades, W.A.; Williams, L.R.

    1988-01-01

    The streaming of neutrons through the beam tubes in High Flux Isotope Reactor at Oak Ridge National Laboratory has resulted in a reduction of the fracture toughness of the reactor vessel. As a result, an evaluation of vessel integrity was undertaken in order to determine if the reactor can be operated again. As a part of this evaluation, three-dimensional neutron transport calculations were performed to obtain fluxes at points of interest in the wall of the vessel. By comparing the calculated and measured activation of dosimetry specimens from the vessel surveillance program, it was determined that the calculated flux shape was satisfactory to transpose the surveillance data to the locations in the vessel. A bias factor was applied to correct for the average C/E ratio of 0.69. 8 refs., 7 figs., 3 tabs.

  16. STRATIFIED COMPOSITION EFFECTS ON PLANETARY NEUTRON FLUX

    SciTech Connect

    O. GASNAULT; ET AL

    2001-01-01

    All the bodies of the solar system that are directly irradiated by the galactic cosmic rays, emit enough neutrons to allow a measurement from space. These leakage neutron fluxes are indexes of the surface composition, depending on the energy of the neutrons [1]. Recent work propose geochemical interpretations of these fluxes: the thermal energy range is sensitive to iron, titanium, rare earth elements and thorium [2, 3], the epithermal energy range is sensitive to hydrogen, samarium and gadolinium [2] and the fast energy range is representative of the average soil atomic mass [4]. Nevertheless these studies make the hypothesis of a composition uniform within the footprint of the spectrometer and independent of depth. We show in this abstract that a stratified composition could change significantly the flux intensity and complicate the interpretation of the measurements. The neutron leakage flux is a competition between production effects (sensitive at high energy) and diffusion-capture effects (mostly sensitive at low energy). On one hand, it happens to be that the elements which produce the higher number of neutrons in typical lunar compositions are iron and titanium, which have also large cross section of absorption with the neutrons. On the other hand, the maximum of neutron intensity does not occur at the surface but at about 180 g cm{sup {minus}2} in depth. Therefore, if we have an iron- and/or titanium-rich soil (important production of neutrons) with a top layer having less iron and/or titanium (i.e. more transparent to the neutrons), we can expect an enhancement of the flux compared to a uniform composition.

  17. Modulating the Neutron Flux from a Mirror Neutron Source

    SciTech Connect

    Ryutov, D D

    2011-09-01

    A 14-MeV neutron source based on a Gas-Dynamic Trap will provide a high flux of 14 MeV neutrons for fusion materials and sub-component testing. In addition to its main goal, the source has potential applications in condensed matter physics and biophysics. In this report, the author considers adding one more capability to the GDT-based neutron source, the modulation of the neutron flux with a desired frequency. The modulation may be an enabling tool for the assessment of the role of non-steady-state effects in fusion devices as well as for high-precision, low-signal basic science experiments favoring the use of the synchronous detection technique. A conclusion is drawn that modulation frequency of up to 1 kHz and modulation amplitude of a few percent is achievable. Limitations on the amplitude of modulations at higher frequencies are discussed.

  18. High-flux source of fusion neutrons for material and component testing

    SciTech Connect

    Baldwin, D. E.; Hooper, E. B.; Ryutov, D. D.; Thomassen, K. I.

    1999-01-07

    The inner part of a fusion reactor will have to operate at very high neutron loads. In steady-state reactors the minimum fluence before the scheduled replacement of the reactor core should be at least l0-15 Mw.yr/m2. A more frequent replacement of the core is hardly compatible with economic constraints. A most recent summary of the discussions of these issues is presented in Ref. [l]. If and when times come to build a commercial fusion reactor, the availability of information on the behavior of materials and components at such fluences will become mandatory for making a final decision. This makes it necessary an early development and construction of a neutron source for fusion material and component testing. In this paper, we present information on one very attractive concept of such a source: a source based on a so called Gas Dynamic Trap. This neutron source was proposed in the mid 1980s (Ref. [2]; see also a survey [3] with discussion of the early stage of the project). Since then, gradual accumulation of the relevant experimental information on a modest-scale experimental facility GDT at Novosibirsk, together with a continuing design activity, have made initial theoretical considerations much more credible. We believe that such a source can be built within 4 or 5 years. Of course, one should remember that there is a chance for developing steady-state reactors with a liquid (and therefore continuously renewable) first wall [4], which would also serve as a tritium breeder. In this case, the need in the neutron testing will become less pressing. However, it is not clear yet that the concept of the flowing wall will be compatible with all types of steady-state reactors. It seems therefore prudent to be prepared to the need of a quick construction of a neutron source. It should also be mentioned that there exist projects of the accelerator-based neutron sources (e.g., [5]). However, they generally have two major disadvantages: a wrong neutron spectrum

  19. Apparatus for measuring a flux of neutrons

    DOEpatents

    Stringer, James L.

    1977-01-01

    A flux of neutrons is measured by disposing a detector in the flux and applying electronic correlation techniques to discriminate between the electrical signals generated by the neutron detector and the unwanted interfering electrical signals generated by the incidence of a neutron flux upon the cables connecting the detector to the electronic measuring equipment at a remote location.

  20. Determining the Magnitude of Neutron and Galactic Cosmic Ray (GCR) Fluxes at the Moon using the Lunar Exploration Neutron Detector during the Historic Space-Age Era of High GCR Flux

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Boynton, W. V.; Mitrofanov, I. G.; Milikh, G. M.; Su, J. J.; Livengood, T. A.; McClanahan, T. P.; Evans, L.; Starr, R. D.; litvak, M. L.; Sanin, A.

    2013-12-01

    The Lunar Reconnaissance Orbiter (LRO) was launched June 18, 2009 during an historic space-age era of minimum solar activity [1]. The lack of solar sunspot activity signaled a complex set of heliospheric phenomena [2,3,4] that also gave rise to a period of unprecedentedly high Galactic Cosmic Ray (GCR) flux [5]. These events coincided with the primary mission of the Lunar Exploration Neutron Detector (LEND, [6]), onboard LRO in a nominal 50-km circular orbit of the Moon [7]. Methods to calculate the emergent neutron albedo population using Monte Carlo techniques [8] rely on an estimate of the GCR flux and spectra calibrated at differing periods of solar activity [9,10,11]. Estimating the actual GCR flux at the Moon during the LEND's initial period of operation requires a correction using a model-dependent heliospheric transport modulation parameter [12] to adjust the GCR flux appropriate to this unique solar cycle. These corrections have inherent uncertainties depending on model details [13]. Precisely determining the absolute neutron and GCR fluxes is especially important in understanding the emergent lunar neutrons measured by LEND and subsequently in estimating the hydrogen/water content in the lunar regolith [6]. LEND is constructed with a set of neutron detectors to meet differing purposes [6]. Specifically there are two sets of detector systems that measure the flux of epithermal neutrons: a) the uncollimated Sensor for Epi-Thermal Neutrons (SETN) and b) the Collimated Sensor for Epi-Thermal Neutrons (CSETN). LEND SETN and CSETN observations form a complementary set of simultaneous measurements that determine the absolute scale of emergent lunar neutron flux in an unambiguous fashion and without the need for correcting to differing solar-cycle conditions. LEND measurements are combined with a detailed understanding of the sources of instrumental back-ground, and the performance of CSETN and SETN. This comparison allows us to calculate a constant scale factor

  1. Neutron conversion and cascaded cooling in paramagnetic systems for a high-flux source of very cold neutrons

    NASA Astrophysics Data System (ADS)

    Zimmer, Oliver

    2016-03-01

    A new neutron-cooling mechanism is proposed with potential benefits for novel intense sources of very cold neutrons with wavelengths >2 nm, and for enhancing the production of ultracold neutrons. It employs inelastic magnetic scattering in weakly absorbing, cold paramagnetic systems. Kinetic energy is removed from the neutron stepwise in constant decrements determined by the Zeeman energy of paramagnetic atoms or ions in an external magnetic field, or by zero-field level splittings in magnetic molecules. The stationary neutron transport equation is analyzed for an infinite, homogeneous medium with Maxwellian neutron sources, using inelastic scattering cross sections derived in an appendix. Nonmagnetic inelastic scattering processes are neglected. The solution therefore still underestimates very cold neutron densities that should be achievable in a real medium. Molecular oxygen with its triplet ground state appears particularly promising, notably as a host in fully deuterated O2-clathrate hydrate. Other possibilities are dry O2-4He van der Waals clusters and O2 intercalated in fcc-C60. For conversion of cold to ultracold neutrons, where an incident neutron imparts only a single energy quantum to the medium, the paramagnetic scattering in the clathrate system is found to be stronger, by more than an order of magnitude, than the single-phonon emission in superfluid helium, when evaluated for an incident neutron spectrum with the optimum temperature for the respective medium. Moreover, the multistep paramagnetic cooling cascade leads to further strong enhancements of very cold neutron densities, e.g., by a factor 14 (57) for an initial neutron temperature of 30 K (100 K ), for the moderator held at about 1.3 K . Due to a favorable Bragg cutoff of the O2 clathrate, the cascade-cooling can take effect in a moderator with linear extensions smaller than a meter.

  2. Neutron flux monitoring system for ITER-FEAT (abstract)

    NASA Astrophysics Data System (ADS)

    Kaschuck, Yu.; Krasilnikov, A.; Alekseyev, A.; Amosov, V.; Frunze, V.

    2001-01-01

    The concept of the neutron flux measurements for International Thermonuclear Experimental Reactor ITER-FEAT is discussed. In spite of the fact that ITER-FEAT has reduced fusion power with respect to ITER-FDR, the requirements for neutron flux monitors are similar—wide dynamic range (seven orders), good temporal resolution (1 ms), and high accuracy (10%). It is clear that fission chambers are the most suitable detectors for this application. However high neutron intensity of the fusion plasma and hard requirements lead to a more sophisticated detection system than the ordinary fission chamber. Another problem is an absolute calibration of the detectors. We propose a neutron flux monitoring system, which consist of microfission chambers placed inside the ITER vacuum chamber, three wide range fission chambers placed outside the vacuum chamber, natural diamond detector based compact neutron monitors placed inside the channels of the neutron cameras, and a compact neutron generator for calibration. Microfission chambers could be installed in the standard plugs with other detectors (vacuum x-ray diode, magnetic probe). 235U could be used as well as threshold fission materials (238U, 237Np, 232Th). In the last case the fission chamber will be covered by a boron shield to reduce the changes in the sensitivity. Wide range fission chambers will operate in both pulse count mode and Campbell mode. High linearity is provided by count mode. Temporal resolution of 1 ms is provided by the count mode at low neutron flux and by the Campbell mode at high flux. The nonlinearity of the fission chamber during the switch from count mode to Campbell mode will be corrected by another fission chamber with low sensitivity operating in count mode. Compact neutron flux monitors placed inside neutron cameras will consist of up to ten natural diamond neutron counters with sensitivity to DT neutrons doubled by properly installed poliethilen radiators. Such monitors provide DT neutron flux

  3. 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.

  4. SPHERES, Juelich's high-flux neutron backscattering spectrometer at FRM II

    SciTech Connect

    Wuttke, Joachim; Budwig, Alfred; Drochner, Matthias; Kaemmerling, Hans; Kayser, Franz-Joseph; Kleines, Harald; Ossovyi, Vladimir; Pardo, Luis Carlos; Prager, Michael; Richter, Dieter; Schneider, Gerald J.; Schneider, Harald; Staringer, Simon

    2012-07-15

    SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Juelich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 {mu}eV, a dynamic range of {+-} 31 {mu}eV, and a signal-to-noise ratio of up to 1750:1.

  5. High thermal neutron flux effects on structural and macroscopic properties of alkali-borosilicate glasses used as neutron guide substrate

    NASA Astrophysics Data System (ADS)

    Boffy, R.; Peuget, S.; Schweins, R.; Beaucour, J.; Bermejo, F. J.

    2016-05-01

    The behaviour of four alkali-borosilicate glasses under homogeneous thermal neutron irradiation has been studied. These materials are used for the manufacturing of neutron guides which are installed in most facilities as devices to transport neutrons from intense sources such as nuclear reactors or spallation sources up to scientific instruments. Several experimental techniques such as Raman, NMR, SANS and STEM have been employed in order to understand the rather different macroscopic behaviour under irradiation of materials that belong to a same glass family. The results have shown that the remarkable glass shrinking observed for neutron doses below 0.5 ·1018 n/cm2 critically depends upon the presence of domains where silicate and borate network do not mix.

  6. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed. PMID:22540588

  7. Design of a high-flux epithermal neutron beam using 235U fission plates at the Brookhaven Medical Research Reactor.

    PubMed

    Liu, H B; Brugger, R M; Rorer, D C; Tichler, P R; Hu, J P

    1994-10-01

    Beams of epithermal neutrons are being used in the development of boron neutron capture therapy for cancer. This report describes a design study in which 235U fission plates and moderators are used to produce an epithermal neutron beam with higher intensity and better quality than the beam currently in use at the Brookhaven Medical Research Reactor (BMRR). Monte Carlo calculations are used to predict the neutron and gamma fluxes and absorbed doses produced by the proposed design. Neutron flux measurements at the present epithermal treatment facility (ETF) were made to verify and compare with the computed results where feasible. The calculations indicate that an epithermal neutron beam produced by a fission-plate converter could have an epithermal neutron intensity of 1.2 x 10(10) n/cm2.s and a fast neutron dose per epithermal neutron of 2.8 x 10(-11) cGy.cm2/nepi plus being forward directed. This beam would be built into the beam shutter of the ETF at the BMRR. The feasibility of remodeling the facility is discussed. PMID:7869995

  8. The CG-1D Neutron Imaging Beamline at the Oak Ridge National Laboratory High Flux Isotope Reactor

    NASA Astrophysics Data System (ADS)

    Santodonato, Lou; Bilheux, Hassina; Bailey, Barton; Bilheux, Jean; Nguyen, Phong; Tremsin, Anton; Selby, Doug; Walker, Lakeisha

    The Oak Ridge National Laboratory Neutron Sciences Directorate has installed a neutron imaging beamline at the High Flux Isotope Reactor (HFIR) cold guide hall. CG-1D is one of the three instruments that make up the CG1 instrument suite. The beamline optics and detector have recently been upgraded to meet the needs of the neutron imaging community (better "smoothing" of guide system artifacts, higher flux or spatial resolution). These upgrades comprise a new diffuser/aperture system, two new detectors, a He-filled flight tube and silicon (Si) windows. Shielding inside the flight tube, beam scrapers and a beam stop ensure that biological dose is less than 50 μSv/hr outside of the radiation boundary. A set of diffusers and apertures (pinhole geometry) has been installed at the exit of the guide system to allow motorized L/D variation. Samples sit on a translation/rotation stage for alignment and tomography purposes. Detectors for the CG-1D beamline are (1) an ANDOR DW936 charge coupled device (CCD) camera with a field of view of approximately 7 cm x 7 cm and ∼ 80 microns spatial resolution and 1 frame per second time resolution, (2) a new Micro-Channel Plate (MCP) detector with a 2.8 cm x 2.8 cm field of view and 55 microns spatial resolution, and 5 μs timing capability. 6LiF/ZnS scintillators of thickness varying from 50 to 200 microns are being used at this facility. An overview of the beamline upgrade and preliminary data is presented here.

  9. The CG-1D neutron imaging beamline at the Oak Ridge National Laboratory High Flux Isotope Reactor

    SciTech Connect

    Santodonato, Louis J; Bilheux, Hassina Z; Bailey, William Barton; Bilheux, Jean-Christophe; Nguyen, Phong T; Tremsin, Anton S; Selby, Douglas L; Walker, Lakeisha MH

    2015-01-01

    The Oak Ridge National Laboratory Neutron Sciences Directorate has installed a neutron imaging beamline at the High Flux Isotope Reactor (HFIR) cold guide hall. CG-1D is one of the three instruments that make up the CG1 instrument suite. The beamline optics and detector have recently been upgraded to meet the needs of the neutron imaging community (better smoothing of guide system artifacts, higher flux or spatial resolution). These upgrades comprise a new diffuser/aperture system, two new detectors, a He-filled flight tube and silicon (Si) windows. Shielding inside the flight tube, beam scrapers and a beam stop ensure that biological dose is less than 50 Sv/hr outside of the radiation boundary. A set of diffusers and apertures (pinhole geometry) has been installed at the exit of the guide system to allow motorized L/D variation. Samples sit on a translation/rotation stage for alignment and tomography purposes. Detectors for the CG-1D beamline are (1) an ANDOR DW936 charge coupled device (CCD) camera with a field of view of approximately 7 cm x 7 cm and ~ 80 microns spatial resolution and 1 frame per second time resolution, (2) a new Micro-Channel Plate (MCP) detector with a 2.8 cm x 2.8 cm field of view and 55 microns spatial resolution, and 5 s timing capability. 6LiF/ZnS scintillators of thickness varying from 50 to 200 microns are being used at this facility. An overview of the beamline upgrade and preliminary data is presented here.

  10. Diurnally modulating neutron flux in the Moon's high-latitudes: Evidence for transported hydrogen volatiles and/ or complex regolith compositions in topographic slopes

    NASA Astrophysics Data System (ADS)

    McClanahan, Timothy; Mirofanov, Igor; Boynton, William; Chin, Gordon; Livengood, Timothy; Su, Jiao Jang; Sagdeev, Raold; Parsons, Ann; Evans, Larry; Starr, Richard; Hamara, Dave; Bodnarik, Julia; Williams, Jeane-Pierre; Mazarico, Erwan; Litvak, Maxim; Sanin, Anton; Murray, Joseph

    2016-04-01

    We report evidence that the Moon's diurnally modulating neutron flux is being forced by a latitude dependent mix of 1) transient hydrogen-bearing volatiles near the surface in the upper latitudes and 2) regolith temperature variation in lower latitudes. In this study we investigate diurnally varying neutron flux measurements from the Lunar Reconnaissance Orbiter's (LRO) Lunar Exploration Neutron Detector's Collimated Sensor for Epithermal Neutrons (LEND CSETN) and surface temperature observations from the Diviner radiometer poleward of >±45°. Our presentation shows that the modulating neutron flux is not consistent with a regolith temperature control for latitudes >70°. The anticorrelation may be evidence for transported lunar hydrogen volatiles or highly non-uniform regolith compositional dynamics. Observational evidence is consistent with regolith temperature being the source of the neutron flux modulation in the northern mare (45° to 60°) and may be related to its mafic composition and fast neutron contributions. Predictions for hypothesized regolith temperature effects are evaluated using insolation inferred from the Lunar Observing Laser Altimeter (LOLA) topography.

  11. An Alpha-Gamma Counter for Absolute Neutron Flux Measurement

    NASA Astrophysics Data System (ADS)

    Yue, A.; Greene, G.; Dewey, M.; Gilliam, D.; Nico, J.; Laptev, A.

    2012-03-01

    An alpha-gamma counter was used to measure the absolute neutron flux of a monochromatic cold neutron beam to sub-0.1,% precision. Simultaneously, the counter was used to calibrate a thin neutron flux monitor based on neutron absorption on ^6Li to the same precision. This monitor was used in the most precise beam-based measurement of the neutron lifetime, where the limiting systematic effect was the uncertainty in the neutron counting efficiency (0.3,%). The counter uses a thick target of ^10B-enriched boron carbide to completely absorb the beam. The rate of absorbed neutrons is determined by counting 478 keV gamma rays from neutron capture on ^10B with calibrated high-purity germanium detectors. The calibration results and the implications for the neutron lifetime will be discussed.

  12. VERITAS: a high-flux neutron reflectometer with vertical sample geometry for a long pulse spallation source

    NASA Astrophysics Data System (ADS)

    Mattauch, S.; Ioffe, A.; Lott, D.; Menelle, A.; Ott, F.; Medic, Z.

    2016-04-01

    An instrument concept of a reflectometer with a vertical sample geometry fitted to the long pulse structure of a spallation source, called “VERITAS” at the ESS, is presented. It focuses on designing a reflectometer with high intensity at the lowest possible background following the users' demand to investigate thin layers or interfacial areas in the sub-nanometer length scale. The high intensity approach of the vertical reflectometer fits very well to the long pulse structure of the ESS. Its main goal is to deliver as much usable intensity as possible at the sample position and be able to access a reflectivity range of 8 orders of magnitude and more. The concept assures that the reflectivity measurements can be performed in its best way to maximize the flux delivered to the sample. The reflectometer is optimized for studies of (magnetic) layers having thicknesses down to 5Å and a surface area of 1x1cm2. With reflectivity measurements the depth-resolved, laterally averaged chemical and magnetic profile can be investigated. By using polarised neutrons, additional vector information on the in-plane magnetic correlations (off-specular scattering at the pm length scale, GISANS at the nm length scale) can be studied. The full polarisation analysis could be used for soft matter samples to correct for incoherent scattering which is presently limiting neutron reflectivity studies to a reflectivity range on the order of 10-6.

  13. Neutronics Conversion Analyses of the Laue-Langevin Institute (ILL) High Flux Reactor (RHF)

    SciTech Connect

    Bergeron, A.; Dionne, B.; Calzavara, Y.

    2014-09-30

    The following report describes the neutronics results obtained with the MCNP model of the RHF U7Mo LEU reference design that has been established in 2010 during the feasibility analysis. This work constitutes a complete and detailed neutronics analysis of that LEU design using models that have been significantly improved since 2010 and the release of the feasibility report. When possible, the credibility of the neutronics model is tested by comparing the HEU model results with experimental data or other codes calculations results. The results obtained with the LEU model are systematically compared to the HEU model. The changes applied to the neutronics model lead to better comparisons with experimental data or improved the calculation efficiency but do not challenge the conclusion of the feasibility analysis. If the U7Mo fuel is commercially available, not cost prohibitive, a back-end solution is established and if it is possible to manufacture the proposed element, neutronics analyses show that the performance of the reactor would not be challenged by the conversion to LEU fuel.

  14. The development of a high count rate neutron flux monitoring channel using silicon carbide semiconductor radiation detectors

    NASA Astrophysics Data System (ADS)

    Reisi Fard, Mehdi

    In this dissertation, a fast neutron flux-monitoring channel, which is based on the use of SiC semiconductor detectors is designed, modeled and experimentally evaluated as a power monitor for the Gas Turbine Modular Helium Reactors. A detailed mathematical model of the SiC diode detector and the electronic processing channel is developed using TRIM, MATLAB and PSpice simulation codes. The flux monitoring channel is tested at the OSU Research Reactor. The response of the SiC neutron-monitoring channel to neutrons is in close agreement to simulation results. Linearity of the channel response to thermal and fast neutron fluxes, pulse height spectrum of the channel, energy calibration of the channel and the detector degradation in a fast neutron flux are presented. Along with the model of the neutron monitoring channel, a Simulink model of the GT-MHR core has been developed to evaluate the power monitoring requirements for the GT-MHR that are most demanding for the SiC diode power monitoring system. The Simulink model is validated against a RELAP5 model of the GT-MHR. This dyanamic model is used to simulate reactor transients at the full power and at the start up, in order to identify the response time requirements of the GT-MHR. Based on the response time requirements that have been identified by the Simulink model and properties of the monitoring channel, several locations in the central reflector and the reactor cavity are identified to place the detector. The detector lifetime and dynamic range of the monitoring channel at the detector locations are calculated. The channel dynamic range in the GT-MHR central reflector covers four decades of the reactor power. However, the detector does not survive for a reactor refueling cycle in the central reflector. In the reactor cavity, the detector operates sufficiently long; however, the dynamic range of the channel is smaller than the dynamic range of the channel in the central reflector.

  15. Development of a Position Sensitive Neutron Detector with High Efficiency and Energy Resolution for Use at High-Flux Beam Sources

    PubMed Central

    Markoff, Diane M.; Cianciolo, Vince; Britton, Chuck L.; Cooper, Ronald G.; Greene, Geoff L.

    2005-01-01

    We are developing a high-efficiency neutron detector with 1 cm position resolution and coarse energy resolution for use at high-flux neutron source facilities currently proposed or under construction. The detector concept integrates a segmented 3He ionization chamber with the position sensitive, charged particle collection methods of a MicroMegas detector. Neutron absorption on the helium produces protons and tritons that ionize the fill gas. The charge is amplified in the field region around a wire mesh and subsequently detected in current mode by wire strips mounted on a substrate. One module consisting of a high-voltage plate, a field-shaping high-voltage plate, a grid and wire strips defines a detection region. For 100 % efficiency, detector modules are consecutively placed along the beam axis. Analysis over several regions with alternating wire strip orientation provides a two-dimensional beam profile. By using 3He, a 1/v absorption gas, each axial region captures neutrons of a different energy range, providing an energy-sensitive detection scheme especially useful at continuous beam sources. PMID:27308166

  16. Development of a Position Sensitive Neutron Detector with High Efficiency and Energy Resolution for Use at High-Flux Beam Sources.

    PubMed

    Markoff, Diane M; Cianciolo, Vince; Britton, Chuck L; Cooper, Ronald G; Greene, Geoff L

    2005-01-01

    We are developing a high-efficiency neutron detector with 1 cm position resolution and coarse energy resolution for use at high-flux neutron source facilities currently proposed or under construction. The detector concept integrates a segmented (3)He ionization chamber with the position sensitive, charged particle collection methods of a MicroMegas detector. Neutron absorption on the helium produces protons and tritons that ionize the fill gas. The charge is amplified in the field region around a wire mesh and subsequently detected in current mode by wire strips mounted on a substrate. One module consisting of a high-voltage plate, a field-shaping high-voltage plate, a grid and wire strips defines a detection region. For 100 % efficiency, detector modules are consecutively placed along the beam axis. Analysis over several regions with alternating wire strip orientation provides a two-dimensional beam profile. By using (3)He, a 1/v absorption gas, each axial region captures neutrons of a different energy range, providing an energy-sensitive detection scheme especially useful at continuous beam sources. PMID:27308166

  17. Measurement of the Neutron Spectrum of the HB-4 Cold Source at the High Flux Isotope Reactor at Oak Ridge National Laboratory

    NASA Astrophysics Data System (ADS)

    Robertson, J. L.; Iverson, E. B.

    2009-08-01

    Measurements of the cold neutron spectrum from the super critical hydrogen cold source at the High Flux Isotope Reactor at Oak Ridge National Laboratory were made using time-of-flight spectroscopy. Data were collected at reactor power levels of 8.5MW, 42.5MW and 85MW. The moderator temperature was also varied. Data were collected at 17K and 25K while the reactor power was at 8.5MW, 17K and 25K while at 42.5MW and 18K and 22K while at 85MW. The purpose of these measurements was to characterize the brightness of the cold source and to better understand the relationship between reactor power, moderator temperature, and cold neutron production. The authors will discuss the details of the measurement, the changes observed in the neutron spectrum, and the process for determining the source brightness from the measured neutron intensity.

  18. Dual neutron flux/temperature measurement sensor

    DOEpatents

    Mihalczo, John T.; Simpson, Marc L.; McElhaney, Stephanie A.

    1994-01-01

    Simultaneous measurement of neutron flux and temperature is provided by a single sensor which includes a phosphor mixture having two principal constituents. The first constituent is a neutron sensitive 6LiF and the second is a rare-earth activated Y203 thermophosphor. The mixture is coated on the end of a fiber optic, while the opposite end of the fiber optic is coupled to a light detector. The detected light scintillations are quantified for neutron flux determination, and the decay is measured for temperature determination.

  19. Monte Carlo Simulations on Neutron Transport and Absorbed Dose in Tissue-Equivalent Phantoms Exposed to High-Flux Epithermal Neutron Beams

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Gambarini, G.; Negri, A.; Carrara, M.; Burian, J.; Viererbl, L.

    2010-04-01

    Presently there are no standard protocols for dosimetry in neutron beams for boron neutron capture therapy (BNCT) treatments. Because of the high radiation intensity and of the presence at the same time of radiation components having different linear energy transfer and therefore different biological weighting factors, treatment planning in epithermal neutron fields for BNCT is usually performed by means of Monte Carlo calculations; experimental measurements are required in order to characterize the neutron source and to validate the treatment planning. In this work Monte Carlo simulations in two kinds of tissue-equivalent phantoms are described. The neutron transport has been studied, together with the distribution of the boron dose; simulation results are compared with data taken with Fricke gel dosimeters in form of layers, showing a good agreement.

  20. Ground-based observations of thunderstorm-correlated fluxes of high-energy electrons, gamma rays, and neutrons

    SciTech Connect

    Chilingarian, A.; Daryan, A.; Arakelyan, K.; Hovhannisyan, A.; Mailyan, B.; Melkumyan, L.; Hovsepyan, G.; Chilingaryan, S.; Reymers, A.; Vanyan, L.

    2010-08-15

    The Aragats Space Environmental Center facilities continuously measure fluxes of neutral and charged secondary cosmic ray incidents on the Earth's surface. Since 2003 in the 1-minute time series we have detected more than 100 enhancements in the electron, gamma ray, and neutron fluxes correlated with thunderstorm activities. During the periods of the count rate enhancements, lasting tens of minutes, millions of additional particles were detected. Based on the largest particle event of September 19, 2009, we show that our measurements support the existence of long-lasting particle multiplication and acceleration mechanisms in the thunderstorm atmosphere. For the first time we present the energy spectra of electrons and gamma rays from the particle avalanches produced in the thunderstorm atmosphere, reaching the Earth's surface.

  1. High energy neutron radiography

    SciTech Connect

    Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

    1996-06-01

    High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos.

  2. CR-39 detector based thermal neutron flux measurements, in the photo neutron project

    NASA Astrophysics Data System (ADS)

    Mameli, A.; Greco, F.; Fidanzio, A.; Fusco, V.; Cilla, S.; D'Onofrio, G.; Grimaldi, L.; Augelli, B. G.; Giannini, G.; Bevilacqua, R.; Totaro, P.; Tommasino, L.; Azario, L.; Piermattei, A.

    2008-08-01

    PhoNeS (photo neutron source) is a project aimed at the production and moderation of neutrons by exploiting high energy linear accelerators, currently used in radiotherapy. A feasibility study has been carried out with the scope in mind to use the high energy photon beams from these accelerators for the production of neutrons suitable for boron neutron capture therapy (BNCT). Within these investigations, it was necessary to carry out preliminary measurements of the thermal neutron component of neutron spectra, produced by the photo-conversion of X-ray radiotherapy beams supplied by three LinAcs: 15 MV, 18 MV and 23 MV. To this end, a simple passive thermal neutron detector has been used which consists of a CR-39 track detector facing a new type of boron-loaded radiator. Once calibrated, this passive detector has been used for the measurement of both the thermal neutron component and the cadmium ratio of different neutron spectra. In addition, bubble detectors with a response highly sensitive to thermal neutrons have also been used. Both thermal neutron detectors are simple to use, very compact and totally insensitive to low-ionizing radiation such as electrons and X-rays. The resultant thermal neutron flux was above 10 6 n/cm 2s and the cadmium ratio was no greater than 15 for the first attempt of photo-conversion of X-ray radiotherapy beams.

  3. Instruments to study fast neutrons fluxes in the upper atmosphere with the use of high-altitude balloons

    NASA Astrophysics Data System (ADS)

    Iyudin, A. F.; Bogomolov, V. V.; Galkin, V. I.; Golovanov, I. A.; Krasnov, A.; Markelova, A. K.; Markelov, I.; Morgunova, Yu.; Osedlo, V. I.; Panasyuk, M. I.; Rozhkov, G.; Svertilov, S. I.

    2015-11-01

    The successful circumpolar flight of the X-ray polarimeter PoGOLite in the northern hemisphere during the summer campaign of 2013 inspired us, the team consisting mostly of students and senior researchers, to develop a Modular Monitor of the Cosmic Neutral Emission (MMCNE) prototype that can be flown on the high-altitude balloons to study two components of neutral emission, namely spectra of neutrons and of gamma-rays in the upper layers of Earth atmosphere. Instrument modular concept, and some of the simulated detection characteristics for the selected layout will be presented in this paper.

  4. Neutronics Simulations of 237Np Targets to Support Safety-Basis and 238Pu Production Assessment Efforts at the High Flux Isotope Reactor

    SciTech Connect

    Chandler, David; Ellis, Ronald James

    2015-01-01

    Fueled by two highly enriched uranium-bearing fuel elements surrounded by a large concentric ring of beryllium reflector, the High Flux Isotope Reactor (HFIR) provides one of the highest neutron fluxes in the world and is used to produce unique isotopes like plutonium-238. The National Aeronautics and Space Administration use radioisotope thermoelectric generators powered by 238Pu for deep-space missions. As part of the US Department of Energy s task to reestablish the domestic production of 238Pu, a technology demonstration sub-project has been initiated to establish a new 238Pu supply chain. HFIR safety-basis neutronics calculations are being performed to ensure the target irradiations have no adverse impacts on reactor performance and to calculate data required as input to follow-on thermal-structural, thermal-hydraulic and radionuclide/dose analyses. Plutonium-238 production assessments are being performed to estimate the amount of 238Pu that can be produced in HFIR s permanent beryllium reflector. It is estimated that a total of 0.96 1.12 kg 238Pu (~1.28 1.49 kg PuO2 at 85% 238Pu/Pu purity) could be produced per year in HFIR s permanent beryllium reflector irradiation facilities if they are all utilized.

  5. Performance improvement of neutron flux monitor at KSTAR

    NASA Astrophysics Data System (ADS)

    Kim, Y.-K.; Lee, S.-K.; Kang, B.-H.; Son, J.-B.; Kim, G.-D.

    2012-06-01

    The evaluation of plasma performance in fusion reactors is carried out by various particle or ion detection systems. Neutron diagnostic systems are used to evaluate different aspects of plasma performance and are very important tools because they can directly detect the neutrons of D-D or D-T fusion reactions. Among them, the stilbene scintillator has good Pulse Shape Discrimination (PSD), a fast response of 10 ns and it can also evaluate neutron energy using an unfolding method. Because of these properties, it was proposed as a neutron flux monitor in the Korea Superconducting Tokamak Advanced Research magnetic fusion reactor (KSTAR). Under high radiation fields, specially designed electronics are necessary to measure only fast neutron spectra and to reject background gamma rays. In order to increase the data transfer rate for real-time evaluation of plasma performance, we have developed a Flash Analog to Digital Convertor (FADC) with a Field-Programmable Gate Array (FPGA) that implements a Digital Charge Comparison (DCC) algorithm. Performance evaluation of stilbene was conducted in a 2011 KSTAR campaign and it showed good results for measuring real-time neutron flux with temporal resolution of 1 ms, and it operated well under high magnetic field conditions.

  6. Dissipative mode filtration in a “levitating” neutron flux

    SciTech Connect

    Petelin, M. I. Tai, M. L.

    2015-06-15

    In experiments [1–4], where a flux of neutrons is injected into a horizontal channel, the output flux structure proves to be a nonmonotonic function of the vertical coordinate. This flux evolution is explained by the absorption of neutrons in the floor material.

  7. Improved monitoring system of neutron flux during boron-neutron capture therapy

    SciTech Connect

    Harasawa, S.; Nakamoto, A.; Hayakawa, Y.; Egawa, J.

    1981-10-01

    Continuous and simultaneous monitoring of neutron flux in the course of a boron-neutron capture operation on a brain tumor has been achieved using a new monitoring system. A silicon surface barrier diode mounted with /sup 6/LiF instead of the previously reported borax is used to sense neutrons. The pulse heights of /sup 3/H and ..cap alpha.. particles from /sup 6/Li(n, ..cap alpha..)/sup 2/H reaction are sufficiently high and well separated from noises due to ..gamma.. rays. The effect of pulse-height reduction due to the radiation damage of the diode thus becomes smaller, permitting continuous monitoring. The relative error of the monitoring is within 2% over 5 hr for a neutron-flux density of 2 x 10/sup 9/ n/cm/sup 2/ sec.

  8. Radial Flux Distribution of Low-Energy Neutrons.

    ERIC Educational Resources Information Center

    Higinbotham, J.

    1979-01-01

    Describes an experiment designed to illustrate the basic principle involved in the process of moderation of fast neutrons by water, and the monitoring of the low-energy neutron flux using indium as a probe. (GA)

  9. Thermal neutron flux mapping in a head phantom

    NASA Astrophysics Data System (ADS)

    Lee, C. L.; Zhou, X.-L.; Harmon, J. F.; Bartholomay, R. W.; Harker, Y. D.; Kudchadker, R. J.

    1999-02-01

    Boron neutron capture therapy (BNCT) is a binary cancer treatment modality in which a boron-containing compound is preferentially loaded into a tumor, followed by irradiation by thermal neutrons. In accelerator-based BNCT, neutrons are produced by charged particle-induced reactions such as 7Li(p, n) 7Be. For deeply seated brain tumors, epithermal (1 eV to 10 kev) neutrons are needed to penetrate the skull cap and subsequently thermalize at the tumor location. Cell damage in BNCT is caused by the high linear energy transfer (LET) products from the 10B(n, α) 7Li reaction. Because the cross section for this reaction is of 1/ v character, the dose due to 10B has essentially the same spatial distribution as the thermal neutron flux. A cylindrical acrylic head phantom (15.24 cm diameter by 21.59 cm length) has been constructed to simulate the patient's head and neck, and acrylic spacers of varying width allow placement of small (active sizes: 0.635 cm diameter by 1.27 cm length and 1.5875 cm diameter by 2.54 cm length) BF 3 proportional counters at nearly all radial and axial locations. Measurements of the thermal flux have also been benchmarked with gold and indium foils (bare and cadmium covered), as well as MCNP simulations. Measurement of the thermal neutron flux using these small BF 3 counters is shown to be adequate for experimentally determining the spatial variation of the 10B dose in head phantoms for accelerator-based BNCT.

  10. Determination of TFTR far-field neutron detector efficiencies by local neutron flux spectrum measurement

    NASA Astrophysics Data System (ADS)

    Jassby, D. L.; Ascione, G.; Kugel, H. W.; Roquemore, A. L.; Barcelo, T. W.; Kumar, A.

    1997-01-01

    Neutron detectors have often been located on the tokamak fusion test reactor (TFTR) test cell floor 3 m or more from the vacuum vessel for ease of detector access, to reduce radiation damage, minimize count saturation problems, and to avoid high magnetic fields. These detectors include Si surface-barrier diodes, fission chambers, natural diamond detectors, and T2 production in a moderated 3He cell. To evaluate the performance of these detectors during deuterium-tritium (D-T) operation, we determined the neutron flux spectrum incident on the principal detector enclosure using nuclide sample sets containing Al, Ti, Fe, Co, Cu, Zn, Ni, Zr, Nb, In, and Au activation foils. Foils were installed and then removed after ample exposure to TFTR D-T neutrons. High efficiency, high purity Ge detectors were used for gamma spectroscopy of the irradiated foils. The incident neutron fluence and spectral distribution were unfolded from the measured results, and used to derive absolute detector efficiencies.

  11. A study on the optimum fast neutron flux for boron neutron capture therapy of deep-seated tumors.

    PubMed

    Rasouli, Fatemeh S; Masoudi, S Farhad

    2015-02-01

    High-energy neutrons, named fast neutrons which have a number of undesirable biological effects on tissue, are a challenging problem in beam designing for Boron Neutron Capture Therapy, BNCT. In spite of this fact, there is not a widely accepted criterion to guide the beam designer to determine the appropriate contribution of fast neutrons in the spectrum. Although a number of researchers have proposed a target value for the ratio of fast neutron flux to epithermal neutron flux, it can be shown that this criterion may not provide the optimum treatment condition. This simulation study deals with the determination of the optimum contribution of fast neutron flux in the beam for BNCT of deep-seated tumors. Since the dose due to these high-energy neutrons damages shallow tissues, delivered dose to skin is considered as a measure for determining the acceptability of the designed beam. To serve this purpose, various beam shaping assemblies that result in different contribution of fast neutron flux are designed. The performances of the neutron beams corresponding to such configurations are assessed in a simulated head phantom. It is shown that the previously used criterion, which suggests a limit value for the contribution of fast neutrons in beam, does not necessarily provide the optimum condition. Accordingly, it is important to specify other complementary limits considering the energy of fast neutrons. By analyzing various neutron spectra, two limits on fast neutron flux are proposed and their validity is investigated. The results show that considering these limits together with the widely accepted IAEA criteria makes it possible to have a more realistic assessment of sufficiency of the designed beam. Satisfying these criteria not only leads to reduction of delivered dose to skin, but also increases the advantage depth in tissue and delivered dose to tumor during the treatment time. The Monte Carlo Code, MCNP-X, is used to perform these simulations. PMID:25479433

  12. Neutron flux spectra and radiation damage parameters for the Russian Bor-60 and SM-2 reactors

    SciTech Connect

    Karasiov, A.V.; Greenwood, L.R.

    1995-04-01

    The objective is to compare neutron irradiation conditions in Russian reactors and similar US facilities. Neutron fluence and spectral information and calculated radiation damage parameters are presented for the BOR-60 (Fast Experimental Reactor - 60 MW) and SM-2 reactors in Russia. Their neutron exposure characteristics are comparable with those of the Experimental Breeder Reactor (ERB-II), the Fast Flux Test Facility (FFTF), and the High Flux Isotope Reactor (HFIR) in the United States.

  13. Portable, high intensity isotopic neutron source provides increased experimental accuracy

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Stewart, D. C.; Wahlgren, M. A.

    1968-01-01

    Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy.

  14. Neutron Unfolding Code System for Calculating Neutron Flux Spectra from Activation Data of Dosimeter Foils.

    Energy Science and Technology Software Center (ESTSC)

    1982-04-30

    Version 00 As a part of the measurement and analysis plan for the Dosimetry Experiment at the "JOYO" experimental fast reactor, neutron flux spectral analysis is performed using the NEUPAC (Neutron Unfolding Code Package) code system. NEUPAC calculates the neutron flux spectra and other integral quantities from the activation data of the dosimeter foils.

  15. Neutron Flux Characterization of Irradiation Holes for Irradiation Test at HANARO

    NASA Astrophysics Data System (ADS)

    Yang, Seong Woo; Cho, Man Soon; Choo, Kee Nam; Park, Sang Jun

    2016-02-01

    The High flux Advanced Neutron Application ReactOr (HANARO) is a unique research reactor in the Republic of Korea, and has been used for irradiation testing since 1998. To conduct irradiation tests for nuclear materials, the irradiation holes of CT and OR5 have been used due to a high fast-neutron flux. Because the neutron flux must be accurately calculated to evaluate the neutron fluence of irradiated material, it was conducted using MCNP. The neutron flux was measured using fluence monitor wires to verify the calculated result. Some evaluations have been conducted, however, more than 20% errors have frequently occurred at the OR irradiation hole, while a good agreement between the calculated and measured data was shown at the CT irradiation hole.

  16. High flux reactor

    DOEpatents

    Lake, James A.; Heath, Russell L.; Liebenthal, John L.; DeBoisblanc, Deslonde R.; Leyse, Carl F.; Parsons, Kent; Ryskamp, John M.; Wadkins, Robert P.; Harker, Yale D.; Fillmore, Gary N.; Oh, Chang H.

    1988-01-01

    A high flux reactor is comprised of a core which is divided into two symetric segments housed in a pressure vessel. The core segments include at least one radial fuel plate. The spacing between the plates functions as a coolant flow channel. The core segments are spaced axially apart such that a coolant mixing plenum is formed between them. A channel is provided such that a portion of the coolant bypasses the first core section and goes directly into the mixing plenum. The outlet coolant from the first core segment is mixed with the bypass coolant resulting in a lower inlet temperature to the lower core segment.

  17. Detailed flux calculations for the conceptual design of the Advanced Neutron Source Reactor

    SciTech Connect

    Wemple, C.A.

    1995-05-01

    A detailed MCNP model of the Advanced Neutron Source Reactor has been developed. All reactor components inside the reflector tank were included, and all components were highly segmented. Neutron and photon multigroup flux spectra have been calculated for each segment in the model, and thermal-to-fast neutron flux ratios were determined for each component segment. Axial profiles of the spectra are provided for all components of the reactor. Individual segment statistical uncertainties were limited wherever possible, and the group fluxes for all important reflector components have a standard deviation below 10%.

  18. Origin of neutron flux increases observed in correlation with lightning

    NASA Astrophysics Data System (ADS)

    Babich, Leonid P.; Roussel-Dupré, Robert A.

    2007-07-01

    The past decade of research into the phenomenon of lightning has seen an accumulation of evidence for the existence of penetrating radiation (X- and γ-rays) in direct association with many forms of discharges. As a result, our basic understanding of the mechanisms that produce lightning has shifted from the present paradigm based on conventional breakdown to a picture that incorporates the acceleration and avalanche of energetic particles. Experiments conducted at high mountainous facilities in Gulmarg, India, have further confirmed the need for a paradigm shift. These measurements have shown an enhancement in neutron flux in the atmosphere in correlation with lightning electromagnetic pulses. We demonstrate here that the prevailing neutron generation theory based on synthesis of deuterium nuclei in the lightning channel is not feasible. Instead, this phenomenon is most likely connected with photonuclear reactions produced as part of the recently elaborated theory of relativistic runaway breakdown.

  19. Neutron flux profile monitor for use in a fission reactor

    DOEpatents

    Kopp, Manfred K.; Valentine, Kenneth H.

    1983-01-01

    A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occured. Neutron flux profiles of reactor cores can be more accurately measured as a result.

  20. Global Maps of Lunar Neutron Fluxes from the LEND Instrument

    NASA Technical Reports Server (NTRS)

    Litvak, M. L.; Mitrofanov, I. G.; Sanin, A.; Malakhov, A.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Golovin, D. V.; Harshman, K.; McClanahan, T. P.; Mokrousov, M. I.; Mazarico, E.; Milikh, G.; Neumann, G.; Sagdeev, R.; Smith, D. E.; Starr, R.; Zuber, M. T.

    2012-01-01

    The latest neutron spectrometer measurements with the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) are presented. It covers more than 1 year of mapping phase starting on 15 September 2009. In our analyses we have created global maps showing regional variations in the flux of thermal (energy range < 0.015 eV) and fast neutrons (>0.5 MeV), and compared these fluxes to variances in soil elemental composition, and with previous results obtained by the Lunar Prospector Neutron Spectrometer (LPNS). We also processed data from LEND collimated detectors and derived a value for the collimated signal of epithermal neutrons based on the comparative analysis with the LEND omnidirectional detectors. Finally, we have compared our final (after the data reduction) global epithermal neutron map with LPNS data.

  1. Investigation of flux line lattices by SANS with unpolarized and polarized neutrons

    NASA Astrophysics Data System (ADS)

    Forgan, Ted; Lycett, Richard J.; Bowell, Charlotte; Charalambous, Demetris; Farago, Bela; Laver, Mark; Cubitt, Bob; Dewhurst, Charles

    2007-07-01

    We have investigated flux lines in low- and high- Tc superconductors using unpolarized and polarized neutron techniques. In high- Tc materials, we observe transitions from triangular to square flux line lattices (FLLs) which probably represent the effects of d-wave pairing. In niobium, a supposedly ‘conventional’ superconductor, even more FLL phase transitions can be observed, into structures which spontaneously break the crystal symmetry. Observations of polarized neutron scattering intensities from niobium with a high density of pinning centers show the effects of pinning on the spin-dependence of the signal. Other possible applications of polarized neutrons scattering from the FLL are mentioned.

  2. A scintillating fission detector for neutron flux measurements

    SciTech Connect

    Stange, Sy; Esch, Ernst I; Burgett, Eric A; May, Iain; Muenchausen, Ross E; Taw, Felicia; Tovesson, Fredrik K

    2010-01-01

    Neutron flux monitors are commonly used for a variety of nuclear physics applications. A scintillating neutron detector, consisting of a liquid scintillator loaded with fissionable material, has been developed, characterized, and tested in the beam line at the Los Alamos Neutron Science Center, and shows a significant improvement in neutron sensitivity compared with a conventional fission chamber. Recent research on nanocomposite-based scintillators for gamma-ray detection indicates that this approach can be extended to load nanoparticles of fissionable material into a scintillating matrix, with up to three orders of magnitude higher loading than typical fission chambers. This will result in a rugged, cost-efficient detector with high efficiency, a short signal rise time, and the ability to be used in low neutron-flux environments. Initial efforts to utilize the luminescence of uranyl oxide to eliminate the need for wavelength-shifting dyes were unsuccessful. Excitation of uranyl compounds has been reported at wavelengths ranging from 266 nm to 532 nm. However, neither the 300 nm emission of toluene, nor the 350 nm emission of PPO, nor the 410 nm emission of POPOP resulted in significant excitation of and emission by uranyl oxide. As indicated by UV/visible spectroscopy, light emitted at these wavelengths was absorbed by the colored solution. {sup 235}U remains the most attractive candidate for a fissionable scintillator, due to its high fission cross-section and lack of a threshold fission energy, but all solutions containing molecular uranium compounds will be colored, most more highly than the U{sup 6+} compounds used here. Research is therefore continuing toward the fabrication of uranium nanoparticles, in which, due to Rayleigh scattering, the coloration should be less pronounced. The characterization of the thorium-loaded liquid scintillator and the fabrication of the 100 mL detectors for use at LANSCE demonstrated the feasibility of loading fissionable

  3. Determination of spallation neutron flux through spectral adjustment techniques

    NASA Astrophysics Data System (ADS)

    Mosby, M. A.; Engle, J. W.; Jackman, K. R.; Nortier, F. M.; Birnbaum, E. R.

    2016-08-01

    The Los Alamos Isotope Production Facility (IPF) creates medical isotopes using a proton beam impinged on a target stack. Spallation neutrons are created in the interaction of the beam with target. The use of these spallation neutrons to produce additional radionuclides has been proposed. However, the energy distribution and magnitude of the flux is not well understood. A modified SAND-II spectral adjustment routine has been used with radioactivation foils to determine the differential neutron fluence for these spallation neutrons during a standard IPF production run.

  4. Neutron flux assessment of a neutron irradiation facility based on inertial electrostatic confinement fusion.

    PubMed

    Sztejnberg Gonçalves-Carralves, M L; Miller, M E

    2015-12-01

    Neutron generators based on inertial electrostatic confinement fusion were considered for the design of a neutron irradiation facility for explanted organ Boron Neutron Capture Therapy (BNCT) that could be installed in a health care center as well as in research areas. The chosen facility configuration is "irradiation chamber", a ~20×20×40 cm(3) cavity near or in the center of the facility geometry where samples to be irradiated can be placed. Neutron flux calculations were performed to study different manners for improving scattering processes and, consequently, optimize neutron flux in the irradiation position. Flux distributions were assessed through numerical simulations of several models implemented in MCNP5 particle transport code. Simulation results provided a wide spectrum of combinations of net fluxes and energy spectrum distributions. Among them one can find a group that can provide thermal neutron fluxes per unit of production rate in a range from 4.1·10(-4) cm(-2) to 1.6·10(-3) cm(-2) with epithermal-to-thermal ratios between 0.3% and 13% and fast-to-thermal ratios between 0.01% to 8%. Neutron generators could be built to provide more than 10(10) n s(-1) and, consequently, with an arrangement of several generators appropriate enough neutron fluxes could be obtained that would be useful for several BNCT-related irradiations and, eventually, for clinical practice. PMID:26122974

  5. Distribution of thermal neutron flux around a PET cyclotron.

    PubMed

    Ogata, Yoshimune; Ishigure, Nobuhito; Mochizuki, Shingo; Ito, Kengo; Hatano, Kentaro; Abe, Junichiro; Miyahara, Hiroshi; Masumoto, Kazuyoshi; Nakamura, Hajime

    2011-05-01

    The number of positron emission tomography (PET) examinations has greatly increased world-wide. Since positron emission nuclides for the PET examinations have short half-lives, they are mainly produced using on-site cyclotrons. During the production of the nuclides, significant quantities of neutrons are generated from the cyclotrons. Neutrons have potential to activate the materials around the cyclotrons and cause exposure to the staff. To investigate quantities and distribution of the thermal neutrons, thermal neutron fluxes were measured around a PET cyclotron in a laboratory associating with a hospital. The cyclotron accelerates protons up to 18 MeV, and the mean particle current is 20 μA. The neutron fluxes were measured during both 18F production and C production. Gold foils and thermoluminescent dosimeter (TLD) badges were used to measure the neutron fluxes. The neutron fluxes in the target box averaged 9.3 × 10(6) cm(-2) s(-1) and 1.7 × 10(6) cm(-2) s(-1) during 18F and 11C production, respectively. Those in the cyclotron room averaged 4.1 × 10(5) cm(-2) s(-1) and 1.2 × 10(5) cm(-2) s(-1), respectively. Those outside the concrete wall shielding were estimated as being equal to or less than ∼3 cm s, which corresponded to 0.1 μSv h(-1) in effective dose. The neutron fluxes outside the concrete shielding were confirmed to be quite low compared to the legal limit. PMID:21451309

  6. Accurate Relations Between the Neutron Current Densities and the Neutron Fluxes

    SciTech Connect

    Ronen, Yigal

    2004-02-15

    Accurate relations between neutron current densities and neutron flux are obtained using the integral transport equation. Using these relations and Fick's Law, diffusion constants can be calculated. These diffusion constants are better than those usually used for the cases in which {sigma}{sub a}/{sigma}{sub s} is not small.

  7. NEUTRONIC REACTOR HAVING LOCALIZED AREAS OF HIGH THERMAL NEUTRON DENSITIES

    DOEpatents

    Newson, H.W.

    1958-06-01

    A nuclear reactor for the irradiation of materials designed to provide a localized area of high thermal neutron flux density in which the materials to be irradiated are inserted is described. The active portion of the reactor is comprised of a cubicle graphite moderator of about 25 feet in length along each axis which has a plurality of cylindrical channels for accommodatirg elongated tubular-shaped fuel elements. The fuel elements have radial fins for spacing the fuel elements from the channel walls, thereby providing spaces through which a coolant may be passed, and also to serve as a heatconductirg means. Ducts for accommnodating the sample material to be irradiated extend through the moderator material perpendicular to and between parallel rows of fuel channels. The improvement is in the provision of additional fuel element channels spaced midway between 2 rows of the regular fuel channels in the localized area surrounding the duct where the high thermal neutron flux density is desired. The fuel elements normally disposed in the channels directly adjacent the duct are placed in the additional channels, and the channels directly adjacent the duct are plugged with moderator material. This design provides localized areas of high thermal neutron flux density without the necessity of providing additional fuel material.

  8. Progress on performance assessment of ITER enhanced heat flux first wall technology after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Bao, L.; Barabash, V.; Chappuis, Ph; Eaton, R.; Escourbiac, F.; Giqcuel, S.; Merola, M.; Mitteau, R.; Raffray, R.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Wirtz, M.; Boomstra, D.; Magielsen, A.; Chen, J.; Wang, P.; Gervash, A.; Safronov, V.

    2016-02-01

    ITER first wall (FW) panels are irradiated by energetic neutrons during the nuclear phase. Thus, an irradiation and high heat flux testing programme is undertaken by the ITER organization in order to evaluate the effects of neutron irradiation on the performance of enhanced heat flux (EHF) FW components. The test campaign includes neutron irradiation (up to 0.6-0.8 dpa at 200 °C-250 °C) of mock-ups that are representative of the final EHF FW panel design, followed by thermal fatigue tests (up to 4.7 MW m-2). Mock-ups were manufactured by the same manufacturing process as proposed for the series production. After a pre-irradiation thermal screening, eight mock-ups will be selected for the irradiation campaigns. This paper reports the preparatory work of HHF tests and neutron irradiation, assessment results as well as a brief description of mock-up manufacturing and inspection routes.

  9. High energy neutron dosimeter

    DOEpatents

    Rai, K.S.F.

    1994-01-11

    A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

  10. High energy neutron dosimeter

    DOEpatents

    Sun, Rai Ko S.F.

    1994-01-01

    A device for measuring dose equivalents in neutron radiation fields. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning.

  11. High flux solar energy transformation

    DOEpatents

    Winston, Roland; Gleckman, Philip L.; O'Gallagher, Joseph J.

    1991-04-09

    Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes.

  12. High flux solar energy transformation

    DOEpatents

    Winston, R.; Gleckman, P.L.; O'Gallagher, J.J.

    1991-04-09

    Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes. 7 figures.

  13. 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).

  14. MONDO: A neutron tracker for particle therapy secondary emission fluxes measurements

    NASA Astrophysics Data System (ADS)

    Marafini, M.; Patera, V.; Pinci, D.; Sarti, A.; Sciubba, A.; Spiriti, E.

    2016-07-01

    Cancer treatment is performed, in Particle Therapy, using accelerated charged particles whose high irradiation precision and conformity allows the tumor destruction while sparing the surrounding healthy tissues. Dose release monitoring devices using photons and charged particles produced by the beam interaction with the patient body have already been proposed, but no attempt based on the detection of the abundant secondary radiation neutron component has been made yet. The reduced attenuation length of neutrons yields a secondary particle sample that is larger in number when compared to photons and charged particles. Furthermore, neutrons allow for a backtracking of the emission point that is not affected by multiple scattering. Since neutrons can release a significant dose far away from the tumor region, a precise measurement of their flux, production energy and angle distributions is eagerly needed in order to improve the Treatment Planning Systems (TPS) software, so to predict not only the normal tissue toxicity in the target region but also the risk of late complications in the whole body. All the aforementioned issues underline the importance for an experimental effort devoted to the precise characterization of the neutron production gaining experimental access both to the emission point and production energy. The technical challenges posed by a neutron detector aiming for a high detection efficiency and good backtracking precision will be addressed within the MONDO (MOnitor for Neutron Dose in hadrOntherapy) project. The MONDO's main goal is to develop a tracking detector targeting fast and ultrafast secondary neutrons. The tracker is composed by a scintillating fiber matrix (4 × 4 × 8cm3). The full reconstruction of protons, produced in elastic interactions, will be used to measure energy and direction of the impinging neutron. The neutron tracker will measure the neutron production yields, as a function of production angle and energy, using different

  15. "Influence Method" applied to measure a moderated neutron flux

    NASA Astrophysics Data System (ADS)

    Rios, I. J.; Mayer, R. E.

    2016-01-01

    The "Influence Method" is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency. This method exploits the influence of the presence of one detector, in the count rate of another detector when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency. The method and its detailed mathematical description were recently published (Rios and Mayer, 2015 [1]). In this article we apply it to the measurement of the moderated neutron flux produced by an 241AmBe neutron source surrounded by a light water sphere, employing a pair of 3He detectors. For this purpose, the method is extended for its application where particles arriving at the detector obey a Poisson distribution and also, for the case when efficiency is not constant over the energy spectrum of interest. Experimental distributions and derived parameters are compared with theoretical predictions of the method and implications concerning the potential application to the absolute calibration of neutron sources are considered.

  16. High power neutron production targets

    SciTech Connect

    Wender, S.

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  17. 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.

  18. 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.

  19. LaBr3 scintillator response to admixed neutron and γ-ray fluxes

    NASA Astrophysics Data System (ADS)

    Cazzaniga, C.; Croci, G.; Giacomelli, L.; Grosso, G.; Nocente, M.; Tardocchi, M.; Gorini, G.; Weller, A.

    2013-12-01

    The γ-ray spectroscopy is a promising method for diagnosing fast ions and confined α particles in a fusion plasma device. This application requires γ-ray detectors with high energy resolution (say a few percent for γ-ray energies in the range 1-5 MeV), high efficiency and high count rate capability, ideally up to a few MHz. Furthermore, the detector will have to withstand the high 14 MeV and 2.45 MeV neutron fluxes produced by the main fusion reactions between deuterium and tritium. Experimental results demonstrate that the requirements on energy resolution, efficiency and count rate can be met with a LaBr3(Ce) scintillator detector equipped with fast digital data acquisition. The measured response of the detector to 2.45 MeV neutrons is presented in this paper and discussed in terms of the interaction mechanism between neutrons and detector.

  20. HFBR handbook, 1992: High flux beam reactor

    SciTech Connect

    Axe, J.D.; Greenberg, R.

    1992-10-01

    Welcome to the High Flux Beam Reactor (HFBR), one of the world premier neutron research facilities. This manual is intended primarily to acquaint outside users (and new Brookhaven staff members) with (almost) everything they need to know to work at the HFBR and to help make the stay at Brookhaven pleasant as well as profitable. Safety Training Programs to comply with US Department of Energy (DOE) mandates are in progress at BNL. There are several safety training requirements which must be met before users can obtain unescorted access to the HFBR. The Reactor Division has prepared specific safety training manuals which are to be sent to experimenters well in advance of their expected arrival at BNL to conduct experiments. Please familiarize yourself with this material and carefully pay strict attention to all the safety and security procedures that are in force at the HFBR. Not only your safety, but the continued operation of the facility, depends upon compliance.

  1. Design of a transportable high efficiency fast neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Roecker, C.; Bernstein, A.; Bowden, N. S.; Cabrera-Palmer, B.; Dazeley, S.; Gerling, M.; Marleau, P.; Sweany, M. D.; Vetter, K.

    2016-08-01

    A transportable fast neutron detection system has been designed and constructed for measuring neutron energy spectra and flux ranging from tens to hundreds of MeV. The transportability of the spectrometer reduces the detector-related systematic bias between different neutron spectra and flux measurements, which allows for the comparison of measurements above or below ground. The spectrometer will measure neutron fluxes that are of prohibitively low intensity compared to the site-specific background rates targeted by other transportable fast neutron detection systems. To measure low intensity high-energy neutron fluxes, a conventional capture-gating technique is used for measuring neutron energies above 20 MeV and a novel multiplicity technique is used for measuring neutron energies above 100 MeV. The spectrometer is composed of two Gd containing plastic scintillator detectors arranged around a lead spallation target. To calibrate and characterize the position dependent response of the spectrometer, a Monte Carlo model was developed and used in conjunction with experimental data from gamma ray sources. Multiplicity event identification algorithms were developed and used with a Cf-252 neutron multiplicity source to validate the Monte Carlo model Gd concentration and secondary neutron capture efficiency. The validated Monte Carlo model was used to predict an effective area for the multiplicity and capture gating analyses. For incident neutron energies between 100 MeV and 1000 MeV with an isotropic angular distribution, the multiplicity analysis predicted an effective area of 500 cm2 rising to 5000 cm2. For neutron energies above 20 MeV, the capture-gating analysis predicted an effective area between 1800 cm2 and 2500 cm2. The multiplicity mode was found to be sensitive to the incident neutron angular distribution.

  2. Applicability of the Ge(n,γ) Reaction for Estimating Thermal Neutron Flux

    NASA Astrophysics Data System (ADS)

    Nikolov, J.; Medić, Ž.; Jovančević, N.; Hansman, J.; Todorović, N.; Krmar, M.

    A simple experimental setup was used to measure gamma lines appearing in spectra after interactions of neutrons with Ge in the active volume of a high-purity germanium detector placed in a low-background shield. As source of neutrons a 252Cf spontaneous fission source and different thicknesses of PVC plates were used to slow down neutrons. A cadmiumenvelope was placed over the detector dipstick to identify the effect from slow and fast neutrons. Intensities of several characteristic γ-lines were measured, including intensity of the 139.9 keV γ-line from the reaction 74Ge(n,γ)75mGe, usually used for estimation of thermal neutron flux. Obtained results signify that only a part of the detected 139.9 keV γ-rays originate from thermal neutron capture. Some preliminary results indicate that in our detection setup thermal neutron capture contributes with 30% to 50% to the total intensity of the 139.9 keV γ-line, depending on the thickness of the PVC plates.

  3. On the 252Cf primary and secondary gamma rays and epithermal neutron flux for BNCT

    NASA Astrophysics Data System (ADS)

    Ghassoun, J.; Merzouki, A.; El Morabiti, A.; Jehouani, A.

    2007-10-01

    Monte Carlo simulation has been used to calculate the different components of neutrons and secondary gamma rays originated by 252Cf fission and also the primary gamma rays emitted directly by the 252Cf source at the exit face of a compact system designed for the BNCT. The system consists of a 252Cf source and a moderator/reflector/filter assembly. To study the material properties and configuration possibilities, the MCNP code has been used. The moderator/reflector/filter arrangement is optimised to moderate neutrons to epithermal energy and, as far as possible, to get rid of fast and thermal neutrons and photons from the therapeutic beam. To reduce the total gamma contamination and to have a sufficiently high epithermal neutron flux we have used different photon filters of different thickness. Our analysis showed that the use of an appropriate filter leads to a gamma ray flux reduction without affecting the epithermal neutron beam quality at the exit face of the system.

  4. Neutron Imager and Flux Monitor Based on Micro Channel Plates (MCP) in Electrostatic Mirror Configuration

    NASA Astrophysics Data System (ADS)

    Variale, V.

    In this paper, a new high transparency device based on MCP for the monitoring the flux and spatial profile of a neutron beam will be described. The assembly consists of a carbon foil with a 6Li deposit, placed in the beam, and a MCP equipped with a phosphor screen readout viewed by a CCD camera, placed outside the beam. Secondary emitted electrons (SEE) produced in the carbon foil by the alpha-particles and tritons from the 6Li+n reaction, are deflected to the MCP detector by means of an electrostatic mirror, suitably designed to preserve the spatial resolution. The conductive layer on the phosphor can be used for neutron counting, and to obtain time-of-flight information. A peculiar feature of this device is that the use of an electrostatic mirror minimizes the perturbation of the neutron beam, i.e. absorption and scattering. It can be used at existing time-of-flight (TOF) facilities, in particular at the n_TOF facility at CERN, for monitoring the flux and special profile of the neutron beam in the thermal and epithermal region. In this work, the device principle and design will be presented, together with the main features in terms of resolution and neutron detection efficiency.

  5. Relationship between neutron yield rate of tokamak plasmas and spectrometer measured flux for different sight lines

    SciTech Connect

    Gorini, G.; Kaellne, J.; Ognissanto, F.; Tardocchi, M.

    2011-03-15

    A parametric relationship between total neutron yield rate and collimated fluxes related to the brightness (B) of plasma chords ({lambda}) is developed for different emissivity distributions of tokamak plasmas. Specifically, the brightness was expressed as a function of chord coordinates of radial position using a simple model for the emissivity profiles of width parameter w. The functional brightness dependence B({lambda},w) was calculated to examine the relationship between measured flux and deduced yield rate, and its plasma profile dependence. The results were used to determine the chord range of minimum profile sensitivity in order to identify the preferred collimator sight for the determination of yield rate from neutron emission spectroscopy (YNES) measurements. The YNES method is discussed in comparison to conventional methods to determine the total neutron yield rates and related plasma fusion power relying on uncollimated flux measurements and a different calibration base for the flux-yield relationship. The results have a special bearing for tokamaks operating with both deuterium and deuterium-tritium plasmas and future high power machines such as for ITER, DEMO, and IGNITOR.

  6. Experimental study on the performance of an epithermal neutron flux monitor for BNCT.

    PubMed

    Guan, Xingcai; Manabe, Masanobu; Tamaki, Shingo; Liu, Shuangtong; Sato, Fuminobu; Murata, Isao; Wang, Tieshan

    2016-07-01

    The performance of an epithermal neutron (0.5eVflux monitor designed for boron neutron capture therapy (BNCT) was experimentally studied by using a prototype monitor in an appropriate neutron field at the intense deuterium-tritium neutron source facility OKTAVIAN of Osaka University, Japan. It was convinced from the experimental results that the developed monitor worked well and the epithermal neutron fluxes in BNCT neutron sources can be measured within 5% by the monitor. PMID:27110926

  7. Bayesian calibration of reactor neutron flux spectrum using activation detectors measurements: Application to CALIBAN reactor

    SciTech Connect

    Cartier, J.; Casoli, P.; Chappert, F.

    2013-07-01

    In this paper, we present calibration methods in order to estimate reactor neutron flux spectrum and its uncertainties by using integral activation measurements. These techniques are performed using Bayesian and MCMC framework. These methods are applied to integral activation experiments in the cavity of the CALIBAN reactor. We estimate the neutron flux and its related uncertainties. The originality of this work is that these uncertainties take into account measurements uncertainties, cross-sections uncertainties and model error. In particular, our results give a very good approximation of the total flux and indicate that neutron flux from MCNP simulation for energies above about 5 MeV seems to overestimate the 'real flux'. (authors)

  8. Characterisation of CVD diamond detectors used for fast neutron flux monitoring

    NASA Astrophysics Data System (ADS)

    Foulon, F.; Bergonzo, P.; Amosov, V. N.; Kaschuck, Yu.; Frunze, V.; Tromson, D.; Brambilla, A.

    2002-01-01

    Natural diamond detectors (NDD) have been successfully used for fast neutron spectrometry on various fusion installations in plasma diagnostics. These detectors can work at high temperature, are radiation hard and exhibit a high energy resolution. However, the use of NDD is limited by the availability of IIa type diamonds exhibiting high electronic properties. With the recent advance in the growth of high quality chemically vapour deposited (CVD) diamond at LETI, CVD diamond appears to be a very promising material for plasma diagnostics. We present here for the first time results of the use of CVD diamond detectors for fast neutron flux monitoring on a neutron generator. The characteristics of CVD diamond detectors are compared with that of high quality NDD made by TRINITI. Pulse height spectra have been measured with CVD detectors and NDD under both 5.5 MeV alpha particles and 14.1 MeV neutrons. The quality of CVD diamond enables the recording of structured spectra allowing the distinction between the different neutron reactions on carbon. The efficiency of CVD diamond monitors and their actual limitations are analysed and discussed.

  9. Extraterrestrial high energy neutrino fluxes

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1979-01-01

    Using the most recent cosmic ray spectra up to 2x10 to the 20th power eV, production spectra of high energy neutrinos from cosmic ray interactions with interstellar gas and extragalactic interactions of ultrahigh energy cosmic rays with 3K universal background photons are presented and discussed. Estimates of the fluxes from cosmic diffuse sources and the nearby quasar 3C273 are made using the generic relationship between secondary neutrinos and gammas and using recent gamma ray satellite data. These gamma ray data provide important upper limits on cosmological neutrinos. Quantitative estimates of the observability of high energy neutrinos from the inner galaxy and 3C273 above atmospheric background for a DUMAND type detector are discussed in the context of the Weinberg-Salam model with sq sin theta omega = 0.2 and including the atmospheric background from the decay of charmed mesons. Constraints on cosmological high energy neutrino production models are also discussed. It appears that important high energy neutrino astronomy may be possible with DUMAND, but very long observing times are required.

  10. Advanced high temperature heat flux sensors

    NASA Technical Reports Server (NTRS)

    Atkinson, W.; Hobart, H. F.; Strange, R. R.

    1983-01-01

    To fully characterize advanced high temperature heat flux sensors, calibration and testing is required at full engine temperature. This required the development of unique high temperature heat flux test facilities. These facilities were developed, are in place, and are being used for advanced heat flux sensor development.

  11. High-pressure neutron diffraction

    SciTech Connect

    Xu, Hongwu

    2011-01-10

    This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

  12. High-flux solar photon processes

    SciTech Connect

    Lorents, D C; Narang, S; Huestis, D C; Mooney, J L; Mill, T; Song, H K; Ventura, S

    1992-06-01

    This study was commissioned by the National Renewable Energy Laboratory (NREL) for the purpose of identifying high-flux photoprocesses that would lead to beneficial national and commercial applications. The specific focus on high-flux photoprocesses is based on the recent development by NREL of solar concentrator technology capable of delivering record flux levels. We examined photolytic and photocatalytic chemical processes as well as photothermal processes in the search for processes where concentrated solar flux would offer a unique advantage. 37 refs.

  13. High intensity, pulsed thermal neutron source

    DOEpatents

    Carpenter, J.M.

    1973-12-11

    This invention relates to a high intensity, pulsed thermal neutron source comprising a neutron-producing source which emits pulses of fast neutrons, a moderator block adjacent to the last neutron source, a reflector block which encases the fast neutron source and the moderator block and has a thermal neutron exit port extending therethrough from the moderator block, and a neutron energy- dependent decoupling reflector liner covering the interior surfaces of the thermal neutron exit port and surrounding all surfaces of the moderator block except the surface viewed by the thermal neutron exit port. (Official Gazette)

  14. Proceedings of the Oak Ridge National Laboratory/Brookhaven National Laboratory workshop on neutron scattering instrumentation at high-flux reactors

    SciTech Connect

    McBee, M.R.; Axe, J.D.; Hayter, J.B.

    1990-07-01

    For the first three decades following World War II, the US, which pioneered the field of neutron scattering research, enjoyed uncontested leadership in the field. By the mid-1970's, other countries, most notably through the West European consortium at Institut Laue-Langevin (ILL) in Grenoble, France, had begun funding neutron scattering on a scale unmatched in this country. By the early 1980's, observers charged with defining US scientific priorities began to stress the need for upgrading and expansion of US research reactor facilities. The conceptual design of the ANS facility is now well under way, and line-item funding for more advanced design is being sought for FY 1992. This should lead to a construction request in FY 1994 and start-up in FY 1999, assuming an optimal funding profile. While it may be too early to finalize designs for instruments whose construction is nearly a decade removed, it is imperative that we begin to develop the necessary concepts to ensure state-of-the-art instrumentation for the ANS. It is in this context that this Instrumentation Workshop was planned. The workshop touched upon many ideas that must be considered for the ANS, and as anticipated, several of the discussions and findings were relevant to the planning of the HFBR Upgrade. In addition, this report recognizes numerous opportunities for further breakthroughs on neutron instrumentation in areas such as improved detection schemes (including better tailored scintillation materials and image plates, and increased speed in both detection and data handling), in-beam monitors, transmission white beam polarizers, multilayers and supermirrors, and more. Each individual report has been cataloged separately.

  15. Neutron flux and power in RTP core-15

    NASA Astrophysics Data System (ADS)

    Rabir, Mohamad Hairie; Zin, Muhammad Rawi Md; Usang, Mark Dennis; Bayar, Abi Muttaqin Jalal; Hamzah, Na'im Syauqi Bin

    2016-01-01

    PUSPATI TRIGA Reactor achieved initial criticality on June 28, 1982. The reactor is designed to effectively implement the various fields of basic nuclear research, manpower training, and production of radioisotopes. This paper describes the reactor parameters calculation for the PUSPATI TRIGA REACTOR (RTP); focusing on the application of the developed reactor 3D model for criticality calculation, analysis of power and neutron flux distribution of TRIGA core. The 3D continuous energy Monte Carlo code MCNP was used to develop a versatile and accurate full model of the TRIGA reactor. The model represents in detailed all important components of the core with literally no physical approximation. The consistency and accuracy of the developed RTP MCNP model was established by comparing calculations to the available experimental results and TRIGLAV code calculation.

  16. The High-Resolution Powder Diffractometer at the High Flux Isotope Reactor

    SciTech Connect

    Garlea, Vasile O; Chakoumakos, Bryan C; Moore, Scott A; Taylor, Gerald Brent; Chae, Timothy L; Maples, Ron G; Riedel, Richard A; Lynn, Gary W; Selby, Douglas L

    2010-01-01

    Neutron powder diffraction is increasingly recognized as one of the most powerful techniques for studying the structural and magnetic properties of advanced materials. Despite the growing demand to study an ever-increasing array of interesting materials, there is only a handful of neutron diffractometers available to serve the U.S. neutron scattering community. This article describes the new high-resolution powder diffractometer that has recently been installed at the High Flux Isotope Reactor in Oak Ridge. The instrument is designed to provide an optimum balance between high neutron flux and high resolution. Due to its versatility the diffractometer can be employed for a large variety of experiments, but it is particularly adapted for refinements of structures with large interplanar spacings as well as of complex magnetic structures. In addition to traditional crystal and magnetic structural refinements, studies of phase transitions, thermal expansion, texture analysis, and ab initio structure solution from powder data can be undertaken.

  17. Wide Range Neutron Flux Measuring Channel for Aerospace Application

    SciTech Connect

    Cibils, R. M.; Busto, A.; Gonella, J. L.; Martinez, R.; Chielens, A. J.; Otero, J. M.; Nunez, M.; Tropea, S. E.

    2008-01-21

    The use of classical techniques for neutron flux measurements in nuclear reactors involves the switching between several detection chains as the power grows up to 10 decades. In space applications where mass and size constraints are of key significance, such volume of hardware represents a clear disadvantage. Instead of requiring different instruments for each reactor operating range (start-up, ramping-up, and nominal power), a single instrument chain should be desirable. A Wide Range Neutron Detector (WRND) system, combining a classic pulse Counting Channel with a Campbell's theorem based Fluctuation Channel can be implemented for the monitoring and control of a space nuclear reactor. Such an instrument will allow for a reduction in the complexity of space-based nuclear instrumentation and control systems. In this presentation we will discuss the criteria and tradeoffs involved in the development of such a system. We will focus particularly on the characteristics of the System On Chip (SOC) and the DSP board used to implement this instrument.

  18. High-energy neutron dosimetry

    NASA Astrophysics Data System (ADS)

    Sutton, Michele Rhea

    2001-12-01

    Fluence-to-dose conversion coefficients for the radiation protection quantity effective dose were calculated for neutrons, photons and protons with energies up to 2 GeV using the MCNPX code. The calculations were performed using the Pacific Northwest National Laboratory versions of the MIRD-V male and female anthropomorphic phantoms modified to include the skin and esophagus. The latest high-energy neutron evaluated cross-section libraries and the recommendations given in ICRP Publication 60 and ICRP Publication 74 were utilized to perform the calculations. Sets of fluence-to- effective dose conversion coefficients are given for anterior-posterior, posterior-anterior, left-lateral, right-lateral and rotational irradiation geometries. This is the first set of dose conversion coefficients over this energy range calculated for the L-LAT irradiation geometry. A unique set of high-energy neutron depth-dose benchmark experiments were performed at the Los Alamos Neutron Science Center/Weapons Neutron Research (LANSCE/WNR) complex. The experiments consisted of filtered neutron beams with energies up to 800 MeV impinging on a 30 x 30 x 30 cm3 tissue-equivalent phantom. The absorbed dose was measured in the phantom at various depths with tissue-equivalent ion chambers. The phantom and the experimental set-up were modeled using MCNPX. Comparisons of the experimental and computational depth- dose distributions indicate that the absorbed dose calculated by MCNPX is within 13% for neutrons with energies up to 750 MeV. This experiment will serve as a benchmark experiment for the testing of high-energy radiation transport codes for the international radiation protection community.

  19. Validation of the MCNP computational model for neutron flux distribution with the neutron activation analysis measurement

    NASA Astrophysics Data System (ADS)

    Tiyapun, K.; Chimtin, M.; Munsorn, S.; Somchit, S.

    2015-05-01

    The objective of this work is to demonstrate the method for validating the predication of the calculation methods for neutron flux distribution in the irradiation tubes of TRIGA research reactor (TRR-1/M1) using the MCNP computer code model. The reaction rate using in the experiment includes 27Al(n, α)24Na and 197Au(n, γ)198Au reactions. Aluminium (99.9 wt%) and gold (0.1 wt%) foils and the gold foils covered with cadmium were irradiated in 9 locations in the core referred to as CT, C8, C12, F3, F12, F22, F29, G5, and G33. The experimental results were compared to the calculations performed using MCNP which consisted of the detailed geometrical model of the reactor core. The results from the experimental and calculated normalized reaction rates in the reactor core are in good agreement for both reactions showing that the material and geometrical properties of the reactor core are modelled very well. The results indicated that the difference between the experimental measurements and the calculation of the reactor core using the MCNP geometrical model was below 10%. In conclusion the MCNP computational model which was used to calculate the neutron flux and reaction rate distribution in the reactor core can be used for others reactor core parameters including neutron spectra calculation, dose rate calculation, power peaking factors calculation and optimization of research reactor utilization in the future with the confidence in the accuracy and reliability of the calculation.

  20. Relationships between cosmic ray neutron flux and rain flows in dependence on different latitudes and altitudes

    NASA Astrophysics Data System (ADS)

    Velinov, Peter; Velinov, Peter; Belov, Anatolii; Yanke, Viktor; Eroshenko, Evgenia; Mishev, Alexander; Tassev, Yordan

    A convenient tool for investigation of primary cosmic ray variations is the registration of secondary cosmic ray neutrons. A network of neutron monitors, aiming the studies of cosmic ray variations exists. At the same time cosmic ray variations may be related to some atmospheric processes. In this connection, using the data from Moskow neutron monitor (latitude 55 degree) and lead free neutron monitor at BEO Moussala (latitude 42 degree and latitude 2971 m above see level), we studied the correlations between rain flows and neutron flux. In this study we used daily averages on the basis of 10 min data for the neutron flux, corrected for barometric pressure and data for local meteo-stations. The measured data permitted to study such effect at different observation levels and latitudes. The preliminary studies permits to observe correlation between rain flows and neutron flux in several cases.

  1. Rhodium self-powered neutron detector as a suitable on-line thermal neutron flux monitor in BNCT treatments

    SciTech Connect

    Miller, Marcelo E.; Sztejnberg, Manuel L.; Gonzalez, Sara J.; Thorp, Silvia I.; Longhino, Juan M.; Estryk, Guillermo

    2011-12-15

    Purpose: A rhodium self-powered neutron detector (Rh SPND) has been specifically developed by the Comision Nacional de Energia Atomica (CNEA) of Argentina to measure locally and in real time thermal neutron fluxes in patients treated with boron neutron capture therapy (BNCT). In this work, the thermal and epithermal neutron response of the Rh SPND was evaluated by studying the detector response to two different reactor spectra. In addition, during clinical trials of the BNCT Project of the CNEA, on-line neutron flux measurements using the specially designed detector were assessed. Methods: The first calibration of the detector was done with the well-thermalized neutron spectrum of the CNEA RA-3 reactor thermal column. For this purpose, the reactor spectrum was approximated by a Maxwell-Boltzmann distribution in the thermal energy range. The second calibration was done at different positions along the central axis of a water-filled cylindrical phantom, placed in the mixed thermal-epithermal neutron beam of CNEA RA-6 reactor. In this latter case, the RA-6 neutron spectrum had been well characterized by both calculation and measurement, and it presented some marked differences with the ideal spectrum considered for SPND calibrations at RA-3. In addition, the RA-6 neutron spectrum varied with depth in the water phantom and thus the percentage of the epithermal contribution to the total neutron flux changed at each measurement location. Local (one point-position) and global (several points-positions) and thermal and mixed-field thermal neutron sensitivities were determined from these measurements. Thermal neutron flux was also measured during BNCT clinical trials within the irradiation fields incident on the patients. In order to achieve this, the detector was placed on patient's skin at dosimetric reference points for each one of the fields. System stability was adequate for this kind of measurement. Results: Local mixed-field thermal neutron sensitivities and global

  2. Flux flow and flux dynamics in high-Tc superconductors

    NASA Technical Reports Server (NTRS)

    Bennett, L. H.; Turchinskaya, M.; Swartzendruber, L. J.; Roitburd, A.; Lundy, D.; Ritter, J.; Kaiser, D. L.

    1991-01-01

    Because high temperature superconductors, including BYCO and BSSCO, are type 2 superconductors with relatively low H(sub c 1) values and high H(sub c 2) values, they will be in a critical state for many of their applications. In the critical state, with the applied field between H(sub c 1) and H(sub c 2), flux lines have penetrated the material and can form a flux lattice and can be pinned by structural defects, chemical inhomogeneities, and impurities. A detailed knowledge of how flux penetrates the material and its behavior under the influence of applied fields and current flow, and the effect of material processing on these properties, is required in order to apply, and to improve the properties of these superconductors. When the applied field is changed rapidly, the time dependence of flux change can be divided into three regions, an initial region which occurs very rapidly, a second region in which the magnetization has a 1n(t) behavior, and a saturation region at very long times. A critical field is defined for depinning, H(sub c,p) as that field at which the hysteresis loop changes from irreversible to reversible. As a function of temperature, it is found that H(sub c,p) is well described by a power law with an exponent between 1.5 and 2.5. The behavior of H(sub c,p) for various materials and its relationship to flux flow and flux dynamics are discussed.

  3. TORT/MCNP coupling method for the calculation of neutron flux around a core of BWR.

    PubMed

    Kurosawa, Masahiko

    2005-01-01

    For the analysis of BWR neutronics performance, accurate data are required for neutron flux distribution over the In-Reactor Pressure Vessel equipments taking into account the detailed geometrical arrangement. The TORT code can calculate neutron flux around a core of BWR in a three-dimensional geometry model, but has difficulties in fine geometrical modelling and lacks huge computer resource. On the other hand, the MCNP code enables the calculation of the neutron flux with a detailed geometry model, but requires very long sampling time to give enough number of particles. Therefore, a TORT/MCNP coupling method has been developed to eliminate the two problems mentioned above in each code. In this method, the TORT code calculates angular flux distribution on the core surface and the MCNP code calculates neutron spectrum at the points of interest using the flux distribution. The coupling method will be used as the DOT-DOMINO-MORSE code system. This TORT/MCNP coupling method was applied to calculate the neutron flux at points where induced radioactivity data were measured for 54Mn and 60Co and the radioactivity calculations based on the neutron flux obtained from the above method were compared with the measured data. PMID:16604689

  4. A benchmark analysis of radiation flux distribution for Boron Neutron Capture Therapy of canine brain tumors

    SciTech Connect

    Moran, J.M.

    1992-02-01

    Calculations of radiation flux and dose distributions for Boron Neutron Capture Therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly-heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This work describes a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador Retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador Retriever head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for the model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous tissue model. Comparison of the results showed that the peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.

  5. Comparison of HEU and LEU Fuel Neutron Spectrum for ATR Fuel Element and ATR Flux-Trap Positions

    SciTech Connect

    G. S. Chang

    2008-10-01

    The Advanced Test Reactor (ATR) is a high power 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 high total core power and high neutron flux, the ATR is an ideal candidate for assessing the feasibility of converting an HEU driven reactor to a low-enriched core. An optimized low-enriched uranium (LEU) (U-10Mo) core conversion case, which can meet the project requirements, has been selected. However, LEU contains a significant quantity of high density U-238 (80.3 wt.%), which will harden the neutron spectrum in the core region. Based on the reference ATR HEU and the optimized LEU full core plate-by-plate (PBP) models, the present work investigates and compares the neutron spectra differences in the fuel element (FE), Northeast flux trap (NEFT), Southeast flux trap (SEFT), and East flux trap (EFT) positions. A detailed PBP MCNP ATR core model was developed and validated for fuel cycle burnup comparison analysis. The current ATR core with HEU U 235 enrichment of 93.0wt.% was used as the reference model. Each HEU fuel element contains 19 fuel plates with a fuel meat thickness of 0.508 mm (20 mil). In this work, an optimized LEU (U-10Mo) core conversion case with a nominal fuel meat thickness of 0.330 mm (13 mil) and the U-235 enrichment of 19.7 wt.% was used to calculate the impact of the neutron spectrum in FE and FT positions. MCNP-calculated results show that the neutron spectrum in the LEU FE is slightly harder than in the HEU FE, as expected. However, when neutrons transport through water coolant and beryllium (Be), the neutrons are thermalized to an equilibrium neutron spectrum as a function of water volume fraction in the investigated FT positions. As a result, the neutron spectrum differences of the HEU and LEU in the NEFT, SEFT, and EFT are negligible. To demonstrate that the LEU core fuel cycle performance can meet the

  6. Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Chandler, K. C.; Barish, J.

    1972-01-01

    Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra were calculated using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron-leakage spectrum at the particular latitude considered support the theory that the cosmic-ray-albedo-neutron-decay mechanism is the source of the protons and electrons trapped in the Van Allen belts.

  7. Theoretical analysis of integral neutron transport equation using collision probability method with quadratic flux approach

    SciTech Connect

    Shafii, Mohammad Ali Meidianti, Rahma Wildian, Fitriyani, Dian; Tongkukut, Seni H. J.; Arkundato, Artoto

    2014-09-30

    Theoretical analysis of integral neutron transport equation using collision probability (CP) method with quadratic flux approach has been carried out. In general, the solution of the neutron transport using the CP method is performed with the flat flux approach. In this research, the CP method is implemented in the cylindrical nuclear fuel cell with the spatial of mesh being conducted into non flat flux approach. It means that the neutron flux at any point in the nuclear fuel cell are considered different each other followed the distribution pattern of quadratic flux. The result is presented here in the form of quadratic flux that is better understanding of the real condition in the cell calculation and as a starting point to be applied in computational calculation.

  8. OVERALL CONTROL SYSTEM FOR HIGH FLUX PILE

    DOEpatents

    Newson, H.W.; Durham, N.C.; Wigner, E.P.; Princeton, N.J.; Epler, E.P.

    1961-05-23

    A control system is given for a high fiux reactor incorporating an anti- scram control feature whereby a neutron absorbing control rod acts as a fine adjustment while a neutron absorbing shim rod, actuated upon a command received from reactor period and level signals, has substantially greater effect on the neutron level and is moved prior to scram conditions to alter the reactor activity before a scram condition is created. Thus the probability that a scram will have to be initiated is substantially decreased.

  9. Flux attenuation at NREL's High-Flux Solar Furnace

    NASA Astrophysics Data System (ADS)

    Bingham, Carl E.; Scholl, Kent L.; Lewandowski, Allan A.

    1994-10-01

    The High-Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL) has a faceted primary concentrator and a long focal-length-to-diameter ratio (due to its off-axis design). Each primary facet can be aimed individually to produce different flux distributions at the target plane. Two different types of attenuators are used depending on the flux distribution. A sliding-plate attenuator is used primarily when the facets are aimed at the same target point. The alternate attenuator resembles a venetian blind. Both attenuators are located between the concentrator and the focal point. The venetian-blind attenuator is primarily used to control the levels of sunlight failing on a target when the primary concentrators are not focused to a single point. This paper will demonstrate the problem of using the sliding-plate attenuator with a faceted concentrator when the facets are not aimed at the same target point. We will show that although the alternate attenuator necessarily blocks a certain amount of incoming sunlight, even when fully open, it provides a more even attenuation of the flux for alternate aiming strategies.

  10. High precision thermal neutron detectors

    SciTech Connect

    Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B.

    1994-12-31

    Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex, their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at the Brookhaven National Laboratory. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of response and reliability over time, for devices of this type.

  11. Upper limit to the 1-20 MeV solar neutron flux.

    NASA Technical Reports Server (NTRS)

    Lockwood, J. A.; Ifedili, S. O.; Jenkins, R. W.

    1973-01-01

    The upper limit on the quiet time solar neutron flux from 1 to 20 MeV has been measured to be less than .002 neutrons at the 95% confidence level. This result is deduced from the OGO-6 neutron detector measurements of the 'day-night' effect near the equator at low altitudes for the period from June 7 to Dec. 23, 1969. The OGO-6 detector had very low (less than 4%) counting rate contributions from locally produced neutrons in the detecting system and the spacecraft and from charged-particle interactions in the neutron sensor.

  12. Estimation method of planetary fast neutron flux by a Ge gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Hareyama, M.; Fujibayashi, Y.; Yamashita, Y.; Karouji, Y.; Nagaoka, H.; Kobayashi, S.; Reedy, R. C.; Gasnault, O.; Forni, O.; d'Uston, C.; Kim, K. J.; Hasebe, N.

    2016-08-01

    An intensity map of lunar fast neutrons (LFNs) and their temporal variation has been estimated by fitting "sawtooth" peaks in the energy spectra of lunar gamma rays observed by the Kaguya (SELENE) Gamma Ray Spectrometer (GRS) consisting of a high-purity germanium (HPGe) detector with a BGO scintillator. While an ordinary peak in the spectrum is produced by only gamma ray lines, the sawtooth peak is produced by gamma ray lines and recoil nuclei in the detector by Ge(n ,n‧ γ) reaction. We develop a model for the shape of the sawtooth peak and apply it to fit sawtooth peaks together with ordinary peaks in actual observed spectra on the Moon. The temporal variation of LFNs is synchronous with that of galactic cosmic rays (GCRs), and the global distribution of fast neutrons on the lunar surface agrees well with the past observation reported by the Neutron Spectrometer aboard Lunar Prospector. Based on these results, a new method is established to estimate the flux of fast neutrons by fitting sawtooth peaks on the gamma ray spectrum observed by the HPGe detector.

  13. The Experimental Determination of Thermal Neutron Flux in the Radiochemistry Curriculum

    ERIC Educational Resources Information Center

    Grant, Patrick M.

    1977-01-01

    Describes an experiment for determining the thermal neutron flux of the light-water nuclear reactor at the University of California, Irvine. The difficulty of the activity can be varied to match the student's level of proficiency. (SL)

  14. Validation of neutron flux redistribution factors in JSI TRIGA reactor due to control rod movements.

    PubMed

    Kaiba, Tanja; Žerovnik, Gašper; Jazbec, Anže; Štancar, Žiga; Barbot, Loïc; Fourmentel, Damien; Snoj, Luka

    2015-10-01

    For efficient utilization of research reactors, such as TRIGA Mark II reactor in Ljubljana, it is important to know neutron flux distribution in the reactor as accurately as possible. The focus of this study is on the neutron flux redistributions due to control rod movements. For analyzing neutron flux redistributions, Monte Carlo calculations of fission rate distributions with the JSI TRIGA reactor model at different control rod configurations have been performed. Sensitivity of the detector response due to control rod movement have been studied. Optimal radial and axial positions of the detector have been determined. Measurements of the axial neutron flux distribution using the CEA manufactured fission chambers have been performed. The experiments at different control rod positions were conducted and compared with the MCNP calculations for a fixed detector axial position. In the future, simultaneous on-line measurements with multiple fission chambers will be performed inside the reactor core for a more accurate on-line power monitoring system. PMID:26141293

  15. Applicability of copper alloys for DEMO high heat flux components

    NASA Astrophysics Data System (ADS)

    Zinkle, Steven J.

    2016-02-01

    The current state of knowledge of the mechanical and thermal properties of high-strength, high conductivity Cu alloys relevant for fusion energy high heat flux applications is reviewed, including effects of thermomechanical and joining processes and neutron irradiation on precipitation- or dispersion-strengthened CuCrZr, Cu-Al2O3, CuNiBe, CuNiSiCr and CuCrNb (GRCop-84). The prospects for designing improved versions of wrought copper alloys and for utilizing advanced fabrication processes such as additive manufacturing based on electron beam and laser consolidation methods are discussed. The importance of developing improved structural materials design criteria is also noted.

  16. Neutron-flux profile monitor for use in a fission reactor

    DOEpatents

    Kopp, M.K.; Valentine, K.H.

    1981-09-15

    A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occurred. Neutron flux profiles of reactor cores can be more accurately measured as a result.

  17. Abnormal changes in the density of thermal neutron flux in biocenoses near the earth surface.

    PubMed

    Plotnikova, N V; Smirnov, A N; Kolesnikov, M V; Semenov, D S; Frolov, V A; Lapshin, V B; Syroeshkin, A V

    2007-04-01

    We revealed an increase in the density of thermal neutron flux in forest biocenoses, which was not associated with astrogeophysical events. The maximum spike of this parameter in the biocenosis reached 10,000 n/(sec x m2). Diurnal pattern of the density of thermal neutron flux depended only on the type of biocenosis. The effects of biomodulation of corpuscular radiation for balneology are discussed. PMID:18214289

  18. Tetrakis-amido high flux membranes

    DOEpatents

    McCray, Scott B.

    1989-01-01

    Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

  19. Tetrakis-amido high flux membranes

    DOEpatents

    McCray, S.B.

    1989-10-24

    Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

  20. Combined analysis of neutron and photon flux measurements for the Jules Horowitz reactor core mapping

    SciTech Connect

    Fourmentel, D.; Villard, J. F.; Lyoussi, A.; Reynard-Carette, C.; Bignan, G.; Chauvin, J. P.; Gonnier, C.; Guimbal, P.; Malo, J. Y.; Carette, M.; Janulyte, A.; Merroun, O.; Brun, J.; Zerega, Y.; Andre, J.

    2011-07-01

    We study the combined analysis of nuclear measurements to improve the knowledge of the irradiation conditions in the experimental locations of the future Jules Horowitz Reactor (JHR). The goal of the present work is to measure more accurately neutron flux, photon flux and nuclear heating in the reactor. In a Material Testing Reactor (MTR), nuclear heating is a crucial parameter to design the experimental devices to be irradiated in harsh nuclear conditions. This parameter drives the temperature of the devices and of the samples. The numerical codes can predict this parameter but in-situ measurements are necessary to reach the expected accuracy. For this reason, one objective of the IN-CORE program [1] is to study the combined measurements of neutron and photon flux and their cross advanced interpretation. It should be reminded that both neutron and photon sensors are not totally selective as their signals are due to neutron and photon interactions. We intend to measure the neutron flux by three different kinds of sensors (Uranium Fission chamber, Plutonium Fission chamber and Self Powered Neutron Detector), the photon flux by two different sensors (Ionization chamber and Self Powered Gamma Detector) and the nuclear heating by two different ones (Differential calorimeter and Gamma Thermometer). For the same parameter, we expect that the use of different kinds of sensors will allow a better estimation of the aimed parameter by mixing different spectrum responses and different neutron and gamma contributions. An experimental test called CARMEN-1 is scheduled in OSIRIS reactor (CEA Saclay - France) at the end of 2011, with the goal to map irradiation locations in the reactor reflector to get a first validation of the analysis model. This article focuses on the sensor selection for CARMEN-1 experiment and to the way to link neutron and photon flux measurements in view to reduce their uncertainties but also to better assess the neutron and photon contributions to nuclear

  1. Flux and dose transmission through concrete of neutrons from proton induced reactions on various target elements

    NASA Astrophysics Data System (ADS)

    Maiti, Moumita; Nandy, Maitreyee; Roy, S. N.; Sarkar, P. K.

    2004-12-01

    Simple empirical expressions for transmission of flux and dose through concrete are presented for neutrons from proton induced reactions. For this purpose the neutron emission from different targets in proton induced reactions in the energy range 25-200 MeV have been considered. The calculated effective dose outside a concrete shield shows overall good agreement with the effective dose estimated from measured neutron flux in the framework of the Moyer model. The calculated effective attenuation length shows a rising trend with incident proton energy and shield thickness.

  2. Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

    2014-12-01

    Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

  3. Conformity Between LR0 Mock-Ups and Vvers Npp Rpv Neutron Flux Attenuation

    NASA Astrophysics Data System (ADS)

    Belousov, Sergey; Ilieva, Krassimira; Kirilova, Desislava

    2009-08-01

    The conformity of the mock-up results and those for reactor pressure vessel (RPV) of nuclear power plants (NPP) has been evaluated in order to qualify if the mock-ups data could be used for benchmark's purpose only, or/and for simulating of the NPP irradiation conditions. Neutron transport through the vessel has been calculated by the three-dimensional discrete ordinate code TORT with problem oriented multigroup energy neutron cross-section library BGL. Neutron flux/fluence and spectrum shape represented by normalized group neutron fluxes in the multigroup energy structure, for neutrons with energy above 0.5 MeV, have been used for conformity analysis. It has been demonstrated that the relative difference of the attenuation factor as well as the group neutron fluxes did not exceed 10% at all considered positions for VVER-440. For VVER-1000, it has been obtained the same consistency, except for the location behind the RPV. The neutron flux attenuation behind the RPV is 18% higher than the mock-up attenuation. It has been shown that this difference arises from the dissimilarity of the biological shielding. The obtained results have demonstrated that the VVERs' mock-ups are appropriate for simulating the NPP irradiation conditions. The mock-up results for VVER-1000 have to be applied more carefully i.e. taking into account the existing peculiarity of the biological shielding and RPV attenuation azimuthal dependence.

  4. Boron neutron capture enhancement (BNCE) of fast neutron irradiation for glioblastoma: increase of thermal neutron flux with heavy material collimation, a theoretical evaluation.

    PubMed

    Paquis, P; Pignol, J P; Lonjon, M; Brassart, N; Courdi, A; Chauvel, P; Grellier, P; Chatel, M

    1999-01-01

    Despite the fact that fast neutron irradiation of glioblastoma has shown on autopsies an ability to sterilize tumors, no therapeutic windows have been found for these particles due to their toxicity toward normal brain. Therefore, the Boron Neutron Capture Enhancement (BNCE) of fast neutron beam has been suggested. This paper addresses the problem of fast neutron beam collimation, which induces a dramatic decrease of the thermal neutron flux in the depth of the tissues when smaller irradiation fields are used. Thermoluminescent dosimeter TLD-600 and TLD-700 were used to determine the thermal neutron flux within a Plexiglas phantom irradiated under the Nice Biomedical Cyclotron p(60)+Be(32) fast neutron beam. A BNCE of 4.6% in physical dose was determined for a 10 x 10 cm2 field, and of 10.4% for a 20 x 20 cm2 one. A Dose Modification Factor of 1.19 was calculated for CAL 58 glioblastoma cells irradiated thanks to the larger field. In order to increase the thermal flux in depth while shaping the beam, heavy material collimation was studied with Monte Carlo simulations using coupled FLUKA and MCNP-4A codes. The use of 20 cm width lead blocks allowed a 2 fold thermal neutron flux increase in the depth of the phantom, while shielding the fast neutron beam with a fast neutron dose transmission of 23%. Using the DMF of 1.19, a BNCE of 40% was calculated in the beam axis. This enhancement might be sufficient to open, at least theoretically, a therapeutic window. PMID:10222419

  5. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    NASA Astrophysics Data System (ADS)

    Ivanova, A. A.; Zubarev, P. V.; Ivanenko, S. V.; Khilchenko, A. D.; Kotelnikov, A. I.; Polosatkin, S. V.; Puryga, E. A.; Shvyrev, V. G.; Sulyaev, Yu. S.

    2016-08-01

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL-3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL-3 and GDT devices. This analyzer was tested and calibrated with the help of 137Cs and 252Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented.

  6. Neutron and Gamma Fluxes and dpa Rates for HFIR Vessel Beltline Region (Present and Upgrade Designs)

    SciTech Connect

    Blakeman, E.D.

    2001-01-11

    The Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) is currently undergoing an upgrading program, a part of which is to increase the diameters of two of the four radiation beam tubes (HB-2 and HB-4). This change will cause increased neutron and gamma radiation dose rates at and near locations where the tubes penetrate the vessel wall. Consequently, the rate of radiation damage to the reactor vessel wall at those locations will also increase. This report summarizes calculations of the neutron and gamma flux (particles/cm{sup 2}/s) and the dpa rate (displacements/atom/s) in iron at critical locations in the vessel wall. The calculated dpa rate values have been recently incorporated into statistical damage evaluation codes used in the assessment of radiation induced embrittlement. Calculations were performed using models based on the discrete ordinates methodology and utilizing ORNL two-dimensional and three-dimensional discrete ordinates codes. Models for present and proposed beam tube designs are shown and their results are compared. Results show that for HB-2, the dpa rate in the vessel wall where the tube penetrates the vessel will be increased by {approximately}10 by the proposed enlargement. For HB-4, a smaller increase of {approximately}2.6 is calculated.

  7. Triga Mark III Reactor Operating Power and Neutron Flux Study by Nuclear Track Methodology

    NASA Astrophysics Data System (ADS)

    Espinosa, G.; Golzarri, J. I.; Raya-Arredondo, R.; Cruz-Galindo, S.; Sajo-Bohus, L.

    The operating power of a TRIGA Mark III reactor was studied using Nuclear Track Methodology (NTM). The facility has a Highly Enriched Uranium core that provides a neutron flux of around 2 x 1012 n cm-2 s-1 in the TO-2 irradiation channel. The detectors consisted of a Landauer® CR-39 (allyl diglycol polycarbonate) chip covered with a 3 mm Plexiglas® converter. After irradiation, the detectors were chemically etched in a 6.25M-KOH solution at 60±1 °C for 6 h. Track density was determined by a custom-made Digital Image Analysis System. The results show a direct proportionality between reactor power and average nuclear track density for powers in the range 0.1-7 kW. Data reproducibility and relatively low uncertainty (±3%) were achieved. NTM is a simple, fast and reliable technique that can serve as a complementary procedure to measure reactor operating power. It offers the possibility of calibrating the neutron flux density in any low power reactor.

  8. Neutron flux measurements in the side-core region of Hunterston B advanced gas-cooled reactor

    SciTech Connect

    Allen, D.A.; Shaw, S.E.; Huggon, A.P.; Steadman, R.J.; Thornton, D.A.; Whiley, G.S.

    2011-07-01

    The core restraints of advanced gas-cooled reactors are important structural components that are required to maintain the geometric integrity of the cores. A review of neutron dosimetry for the sister stations Hunterston B and Hinkley Point B identified that earlier conservative assessments predicted high thermal neutron dose rates to key components of the restraint structure (the restraint rod welds), with the implication that some of them may be predicted to fail during a seismic event. A revised assessment was therefore undertaken [Thornton, D. A., Allen, D. A., Tyrrell, R. J., Meese, T. C., Huggon, A.P., Whiley, G. S., and Mossop, J. R., 'A Dosimetry Assessment for the Core Restraint of an Advanced Gas Cooled Reactor,' Proceedings of the 13. International Symposium on Reactor Dosimetry (ISRD-13, May 2008), World Scientific, River Edge, NJ, 2009, W. Voorbraak, L. Debarberis, and P. D'hondt, Eds., pp. 679-687] using a detailed 3D model and a Monte Carlo radiation transport program, MCBEND. This reassessment resulted in more realistic fast and thermal neutron dose recommendations, the latter in particular being much lower than had been thought previously. It is now desirable to improve confidence in these predictions by providing direct validation of the MCBEND model through the use of neutron flux measurements. This paper describes the programme of work being undertaken to deploy two neutron flux measurement 'stringers' within the side-core region of one of the Hunterston B reactors for the purpose of validating the MCBEND model. The design of the stringers and the determination of the preferred deployment locations have been informed by the use of detailed MCBEND flux calculations. These computational studies represent a rare opportunity to design a flux measurement beforehand, with the clear intention of minimising the anticipated uncertainties and obtaining measurements that are known to be representative of the neutron fields to which the vulnerable steel

  9. RADIATION DOSIMETRY AT THE BNL HIGH FLUX BEAM REACTOR AND MEDICAL RESEARCH REACTOR.

    SciTech Connect

    HOLDEN,N.E.

    1999-09-10

    RADIATION DOSIMETRY MEASUREMENTS HAVE BEEN PERFORMED OVER A PERIOD OF MANY YEARS AT THE HIGH FLUX BEAM REACTOR (HFBR) AND THE MEDICAL RESEARCH REACTOR (BMRR) AT BROOKHAVEN NATIONAL LABORATORY TO PROVIDE INFORMATION ON THE ENERGY DISTRIBUTION OF THE NEUTRON FLUX, NEUTRON DOSE RATES, GAMMA-RAY FLUXES AND GAMMA-RAY DOSE RATES. THE MCNP PARTICLE TRANSPORT CODE PROVIDED MONTE CARLO RESULTS TO COMPARE WITH VARIOUS DOSIMETRY MEASUREMENTS PERFORMED AT THE EXPERIMENTAL PORTS, AT THE TREATMENT ROOMS AND IN THE THIMBLES AT BOTH HFBR AND BMRR.

  10. High-flux PGAA for milligram-weight samples

    NASA Astrophysics Data System (ADS)

    Kudejova, P.; Révay, Z.; Kleszcz, K.; Genreith, C.; Rossbach, M.

    2015-05-01

    With the high-intensity cold neutron flux available at the Prompt Gamma Activation Analysis (PGAA) instrument of the research reactor FRM II at the Heinz Maier-Leibnitz Zentrum (MLZ), samples with a weight of 1 mg or even less can be investigated for their elemental compositions using the (n,γ) capture reaction. In such cases, the typical sample packing material for PGAA experiments made of 25 μm thick PTFE foil (ca. 80 mg) can be orders of magnitude more massive than the sample weight itself. Proper choice of the packing material and measuring conditions are then of the highest importance [1].

  11. Verification and validation of the maximum entropy method of moment reconstruction of energy dependent neutron flux

    NASA Astrophysics Data System (ADS)

    Crawford, Douglas Spencer

    Verification and Validation of reconstructed neutron flux based on the maximum entropy method, is presented in this paper. The verification is carried out by comparing the neutron flux spectrum from the maximum entropy method with Monte Carlo N Particle 5 version 1.40 (MCNP5) and Attila-7.1.0-beta (Attila). A spherical 100% 235U critical assembly is modeled as the test case to compare the three methods. The verification error range for the maximum entropy method is 15% to 23% where MCNP5 is taken to be the comparison standard. Attila relative error for the critical assembly is 20% to 35%. Validation is accomplished by comparing a neutron flux spectrum that is back calculated from foil activation measurements performed in the GODIVA experiment (GODIVA). The error range of the reconstructed flux compared to GODIVA is 0%-10%. The error range of the neutron flux spectrum from MCNP5 compared to GODIVA is 0%-20% and the Attila error range compared to the GODIVA is 0%-35%. The maximum entropy method for reconstructing flux is shown to be a fast reliable method, compared to either Monte Carlo methods (MCNP5) or 30 multienergy group methods (Attila) and with respect to the GODIVA experiment.

  12. Energetic ion diagnostics using neutron flux measurements during pellet injection

    SciTech Connect

    Heidbrink, W.W.

    1986-01-01

    Neutron measurements during injection of deuterium pellets into deuterium plasmas on the Tokamak Fusion Test Reactor (TFTR) indicate that the fractional increase in neutron emission about 0.5 msec after pellet injection is proportional to the fraction of beam-plasma reactions to total fusion reactions in the unperturbed plasma. These observations suggest three diagnostic applications of neutron measurements during pellet injection: (1) measurement of the beam-plasma reaction rate in deuterium plasmas for use in determining the fusion Q in an equivalent deuterium-tritium plasma, (2) measurement of the radial profile of energetic beam ions by varying the pellet size and velocity, and (3) measurement of the ''temperature'' of ions accelerated during wave heating. 18 refs., 3 figs.

  13. Flux stabilization in neutron problems with fixed sources

    SciTech Connect

    Tomatis, D.; Dall'Osso, A.

    2012-07-01

    Although critical core calculations are the most common in design and safety analysis, fixed source calculations are needed for specific applications, e.g. to compute ex-core detector response functions, to develop new methodologies for dilution and reload error accidents and more in general for all situations involving sub-critical shut-down states. It is well known that the source problem becomes difficult to be solved with core configuration close to criticality, i.e. with the multiplication factor approaching unity, for the occurrence of numerical ill-conditioning and very high number of iterations, possibly leading to failure in the flux convergence. In this work, the Wielandt Eigen-shift technique used in iterative methods of critical problems is developed for source problems too, in order to stabilize the solution. The mathematical basis and the proof of the convergence are discussed. Compared to the existing methods, this technique allows also more control to avoid singular behavior at inner iterations. Numerical tests with a 1D analytical benchmark are reported to prove the robustness of the technique. (authors)

  14. Experimental neutron flux measurements with a diamond detector at the QUINTA setup

    NASA Astrophysics Data System (ADS)

    Berlev, A. I.; Rodionov, N. B.; Tyutyunnikov, S. I.; Amosov, V. N.; Meshchaninov, S. A.; Yudin, I. P.

    2016-05-01

    The operational capability of a diamond detector used to measure the neutron spectrum by the response function on the QUINTA setup [1] installed at the proton beam of the phasotron [2] (Laboratory of Nuclear Problems, Joint Institute for Nuclear Research) was demonstrated in the energy interval of 2.1-20 MeV. The neutron-flux count rate was measured. The energy of neutrons was estimated at 7.4-25.7 MeV based on the diamond-detector response spectrum. The dependence of the diamond-detector response spectra on the angle between the proton beam and the line going through the detector and the center of the QUINTA setup was investigated. The angular anisotropy of the neutron flux was demonstrated. Measurements at different distances from the detector to the QUINTA setup were performed.

  15. Comparison of the high temperature heat flux sensor to traditional heat flux gages under high heat flux conditions.

    SciTech Connect

    Blanchat, Thomas K.; Hanks, Charles R.

    2013-04-01

    Four types of heat flux gages (Gardon, Schmidt-Boelter, Directional Flame Temperature, and High Temperature Heat Flux Sensor) were assessed and compared under flux conditions ranging between 100-1000 kW/m2, such as those seen in hydrocarbon fire or propellant fire conditions. Short duration step and pulse boundary conditions were imposed using a six-panel cylindrical array of high-temperature tungsten lamps. Overall, agreement between all gages was acceptable for the pulse tests and also for the step tests. However, repeated tests with the HTHFS with relatively long durations at temperatures approaching 1000%C2%B0C showed a substantial decrease (10-25%) in heat flux subsequent to the initial test, likely due to the mounting technique. New HTHFS gages have been ordered to allow additional tests to determine the cause of the flux reduction.

  16. Altitude and latitude variations in avionics SEU and atmospheric neutron flux

    SciTech Connect

    Normand, E.; Baker, T.J. )

    1993-12-01

    The direct cause of single event upsets in SRAMs at aircraft altitudes by the atmospheric neutrons has previously been documented. The variation of the in-flight SEU rate with latitude is demonstrated by new data over a wide range of geographical locations. New measurements and models of the atmospheric neutron flux are also evaluated to characterize its variation with altitude, latitude and solar activity.

  17. The prototype of a detector for monitoring the cosmic radiation neutron flux on ground

    SciTech Connect

    Lelis Goncalez, Odair; Federico, Claudio Antonio; Mendes Prado, Adriane Cristina; Galhardo Vaz, Rafael; Tizziani Pazzianotto, Mauricio

    2013-05-06

    This work presents a comparison between the results of experimental tests and Monte Carlo simulations of the efficiency of a detector prototype for on-ground monitoring the cosmic radiation neutron flux. The experimental tests were made using one conventional {sup 241}Am-Be neutron source in several incidence angles and the results were compared to that ones obtained with a Monte Carlo simulation made with MCNPX Code.

  18. High heat flux loop heat pipes

    NASA Technical Reports Server (NTRS)

    North, Mark T.; Sarraf, David B.; Rosenfeld, John H.; Maidanik, Yuri F.; Vershinin, Sergey

    1997-01-01

    Loop heat pipes (LHPs) can transport very large thermal power loads over long distances, through flexible, small diameter tubes against gravitational heads. In order to overcome the evaporator limit of LHPs, which is of about 0.07 MW/sq m, work was carried out to improve the efficiency by threefold to tenfold. The vapor passage geometry for the high heat flux conditions is shown. A bidisperse wick material within the circumferential vapor passages was used. Along with heat flux enhancement, several underlying issues were demonstrated, including the fabrication of bidisperse powder with controlled properties and the fabrication of a device geometry capable of replacing vapor passages with bidisperse powder.

  19. High flux source of cold rubidium atoms

    NASA Astrophysics Data System (ADS)

    Slowe, Christopher; Vernac, Laurent; Hau, Lene Vestergaard

    2005-10-01

    We report on the production of a continuous, slow, and cold beam of Rb87 atoms with an extremely high flux of 3.2×1012atoms/s, a transverse temperature of 3mK, and a longitudinal temperature of 90mK. We describe the apparatus created to generate the atom beam. Hot atoms are emitted from a rubidium candlestick atomic beam source and transversely cooled and collimated by a 20cm long atomic collimator section, boosting overall beam flux by a factor of 50. The Rb atomic beam is then decelerated and longitudinally cooled by a 1m long Zeeman slower.

  20. The effect of craters on the lunar neutron flux

    NASA Astrophysics Data System (ADS)

    Eke, V. R.; Bower, K. E.; Diserens, S.; Ryder, M.; Yeomans, P. E. L.; Teodoro, L. F. A.; Elphic, R. C.; Feldman, W. C.; Hermalyn, B.; Lavelle, C. M.; Lawrence, D. J.

    2015-08-01

    The variation of remotely sensed neutron count rates is measured as a function of cratercentric distance using data from the Lunar Prospector Neutron Spectrometer. The count rate, stacked over many craters, peaks over the crater center, has a minimum near the crater rim, and at larger distances, it increases to a mean value that is up to 1% lower than the mean count rate observed over the crater. A simple model is presented, based upon an analytical topographical profile for the stacked craters fitted to data from the Lunar Orbiter Laser Altimeter. The effect of topography coupled with neutron beaming from the surface largely reproduces the observed count rate profiles. However, a model that better fits the observations can be found by including the additional freedom to increase the neutron emissivity of the crater area by ˜0.35% relative to the unperturbed surface. It is unclear what might give rise to this effect, but it may relate to additional surface roughness in the vicinities of craters. The amplitude of the crater-related signal in the neutron count rate is small, but not too small to demand consideration when inferring water-equivalent hydrogen (WEH) weight percentages in polar permanently shaded regions (PSRs). If the small crater-wide count rate excess is concentrated into a much smaller PSR, then it can lead to a large bias in the inferred WEH weight percentage. For instance, it may increase the inferred WEH for Cabeus crater at the Moon's south pole from ˜1% to ˜4%.

  1. The influence of plasma horizontal position on the neutron rate and flux of neutral atoms in injection heating experiment on the TUMAN-3M tokamak

    NASA Astrophysics Data System (ADS)

    Kornev, V. A.; Chernyshev, F. V.; Melnik, A. D.; Askinazi, L. G.; Wagner, F.; Vildjunas, M. I.; Zhubr, N. A.; Krikunov, S. V.; Lebedev, S. V.; Razumenko, D. V.; Tukachinsky, A. S.

    2013-11-01

    Horizontal displacement of plasma along the major radius has been found to significantly influence the fluxes of 2.45 MeV DD neutrons and high-energy charge-exchange atoms from neutral beam injection (NBI) heated plasma of the TUMAN-3M tokamak. An inward shift by Δ R = 1 cm causes 1.2-fold increase in the neutron flux and 1.9-fold increase in the charge-exchange atom flux. The observed increase in the neutron flux is attributed to joint action of several factors-in particular, improved high-energy ion capture and confinement and, probably, decreased impurity inflow from the walls, which leads to an increase in the density of target ions. A considerable increase in the flux of charge-exchange neutrals in inward-shifted plasma is due to the increased number of captured high-energy ions and, to some extent, the increased density of the neutral target. As a result of the increase in the content of high-energy ions, the central ion temperature T i (0) increased from 250 to 350 eV. The dependence of the neutron rate on major radius R 0 should be taken into account when designing compact tokamak-based neutron sources.

  2. Comparison of three-dimensional neutron flux calculations for Maine Yankee

    SciTech Connect

    Urban, W.T.; Crotzer, L.A.; Waters, L.S.; Parsons, D.K.; Alcouffe, R.E.; Spinney, K.B.; Cacciapouti, R.J.

    1996-10-01

    Calculations have been performed on the Maine Yankee Power Plant to obtain three-dimensional neutron fluxes using the spatial synthesis with the two-dimensional discrete ordinates code DORT, the three-dimensional discrete ordinates code THREEDANT and the three-dimensional Monte Carlo code MCNP. Neutron fluxes are compared for energies above 0.1 MeV and 1.0 MeV as well as dpa. Results were obtained at the Yankee dosimetry locations and special test regions within the pressure vessel, in the reactor cavity, and in a shield tank detector well.

  3. Digital Real-Time Multiple Channel Multiple Mode Neutron Flux Estimation on FPGA-based Device

    NASA Astrophysics Data System (ADS)

    Thevenin, Mathieu; Barbot, Loïc; Corre, Gwénolé; Woo, Romuald; Destouches, Christophe; Normand, Stéphane

    2016-02-01

    This paper presents a complete custom full-digital instrumentation device that was designed for real-time neutron flux estimation, especially for nuclear reactor in-core measurement using subminiature Fission Chambers (FCs). Entire fully functional small-footprint design (about 1714 LUTs) is implemented on FPGA. It enables real-time acquisition and analysis of multiple channels neutron's flux both in counting mode and Campbelling mode. Experimental results obtained from this brand new device are consistent with simulation results and show good agreement within good uncertainty. This device paves the way for new applications perspectives in real-time nuclear reactor monitoring.

  4. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  5. Bayesian Statistical Analysis Applied to NAA Data for Neutron Flux Spectrum Determination

    NASA Astrophysics Data System (ADS)

    Chiesa, D.; Previtali, E.; Sisti, M.

    2014-04-01

    In this paper, we present a statistical method, based on Bayesian statistics, to evaluate the neutron flux spectrum from the activation data of different isotopes. The experimental data were acquired during a neutron activation analysis (NAA) experiment [A. Borio di Tigliole et al., Absolute flux measurement by NAA at the Pavia University TRIGA Mark II reactor facilities, ENC 2012 - Transactions Research Reactors, ISBN 978-92-95064-14-0, 22 (2012)] performed at the TRIGA Mark II reactor of Pavia University (Italy). In order to evaluate the neutron flux spectrum, subdivided in energy groups, we must solve a system of linear equations containing the grouped cross sections and the activation rate data. We solve this problem with Bayesian statistical analysis, including the uncertainties of the coefficients and the a priori information about the neutron flux. A program for the analysis of Bayesian hierarchical models, based on Markov Chain Monte Carlo (MCMC) simulations, is used to define the problem statistical model and solve it. The energy group fluxes and their uncertainties are then determined with great accuracy and the correlations between the groups are analyzed. Finally, the dependence of the results on the prior distribution choice and on the group cross section data is investigated to confirm the reliability of the analysis.

  6. High flux expansion divertor studies in NSTX

    SciTech Connect

    Soukhanovskii, V A; Maingi, R; Bell, R E; Gates, D A; Kaita, R; Kugel, H W; LeBlanc, B P; Maqueda, R; Menard, J E; Mueller, D; Paul, S F; Raman, R; Roquemore, A L

    2009-06-29

    Projections for high-performance H-mode scenarios in spherical torus (ST)-based devices assume low electron collisionality for increased efficiency of the neutral beam current drive. At lower collisionality (lower density), the mitigation techniques based on induced divertor volumetric power and momentum losses may not be capable of reducing heat and material erosion to acceptable levels in a compact ST divertor. Divertor geometry can also be used to reduce high peak heat and particle fluxes by flaring a scrape-off layer (SOL) flux tube at the divertor plate, and by optimizing the angle at which the flux tube intersects the divertor plate, or reduce heat flow to the divertor by increasing the length of the flux tube. The recently proposed advanced divertor concepts [1, 2] take advantage of these geometry effects. In a high triangularity ST plasma configuration, the magnetic flux expansion at the divertor strike point (SP) is inherently high, leading to a reduction of heat and particle fluxes and a facilitated access to the outer SP detachment, as has been demonstrated recently in NSTX [3]. The natural synergy of the highly-shaped high-performance ST plasmas with beneficial divertor properties motivated a further systematic study of the high flux expansion divertor. The National Spherical Torus Experiment (NSTX) is a mid-sized device with the aspect ratio A = 1.3-1.5 [4]. In NSTX, the graphite tile divertor has an open horizontal plate geometry. The divertor magnetic configuration geometry was systematically changed in an experiment by either (1) changing the distance between the lower divertor X-point and the divertor plate (X-point height h{sub X}), or by (2) keeping the X-point height constant and increasing the outer SP radius. An initial analysis of the former experiment is presented below. Since in the divertor the poloidal field B{sub {theta}} strength is proportional to h{sub X}, the X-point height variation changed the divertor plasma wetted area due to

  7. Neutron Flux Spectra Determination by Multiple Foil Activation - Iterative Method.

    Energy Science and Technology Software Center (ESTSC)

    1994-07-08

    Version 00 Neutron energy spectra are determined by an analysis of experimental activation detector data. As with the original CCC-112/SAND-II program, which was developed at Air Force Weapons Laboratory, this code system consists of four modules, CSTAPE, SLACTS, SLATPE, and SANDII. The first three modules pre-process the dosimetry cross sections and the trial function spectrum library. The last module, SANDII, actually performs the iterative spectrum characterization.

  8. The High Flux Beam Reactor at Brookhaven National Laboratory

    SciTech Connect

    Shapiro, S.M.

    1994-12-31

    Brookhaven National Laboratory`s High Flux Beam Reactor (HFBR) was built because of the need of the scientist to always want `more`. In the mid-50`s the Brookhaven Graphite reactor was churning away producing a number of new results when the current generation of scientists, led by Donald Hughes, realized the need for a high flux reactor and started down the political, scientific and engineering path that led to the BFBR. The effort was joined by a number of engineers and scientists among them, Chemick, Hastings, Kouts, and Hendrie, who came up with the novel design of the HFBR. The two innovative features that have been incorporated in nearly all other research reactors built since are: (i) an under moderated core arrangement which enables the thermal flux to peak outside the core region where beam tubes can be placed, and (ii) beam tubes that are tangential to the core which decrease the fast neutron background without affecting the thermal beam intensity. Construction began in the fall of 1961 and four years later, at a cost of $12 Million, criticality was achieved on Halloween Night, 1965. Thus began 30 years of scientific accomplishments.

  9. A unique method of neutron flux determination from experimental data

    SciTech Connect

    Paxton, Frank A.

    1998-12-01

    A method is provided for determining the fission heat flux of a prime specimen inserted into a specimen of a test reactor. A pair of thermocouple test specimens are positioned at the same level in the holder and a determination is made of various experimental data including the temperature of the thermocouple test specimens, the temperature of bulk water channels located in the test holder, the gamma scan count ratios for the thermocouple test specimens and the prime specimen, and the thicknesses of the outer clads, the fuel fillers, and the backclad of the thermocouple test specimen. Using this experimental data, the absolute value of the fission heat flux for the thermocouple test specimens and prime specimen can be calculated.

  10. Development of a high-count-rate neutron detector with position sensitivity and high efficiency

    SciTech Connect

    Nelson, R.; Sandoval, J.

    1996-10-01

    While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled {sup 3}He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source.

  11. Protons in High Density Neutron Matter

    NASA Astrophysics Data System (ADS)

    Sargsian, Misak M.

    2014-03-01

    We discuss the possible implication of the recent predictions of two new properties of high momentum distribution of nucleons in asymmetric nuclei for neutron star dynamics. The first property is about the approximate scaling relation between proton and neutron high momentum distributions weighted by their relative fractions (xp and xn) in the nucleus. The second is the existence of inverse proportionality of the high momentum distribution strength of protons and neutrons to xp/n. Based on these predictions we model the high momentum distribution functions for asymmetric nuclei and demonstrate that it describes reasonably well the high momentum characteristics of light nuclei. We also extrapolate our results to heavy nuclei as well as infinite nuclear matter and calculate the relative fractions of protons and neutrons with momenta above kF. Our results indicate that for neutron stars starting at three nuclear saturation densities the protons with xp = 1/9 will populate mostly the high momentum tail of the momentum distribution while only 2% of the neutrons will do so. Such a situation may have many implications for different observations of neutron stars which we discuss.

  12. Transmission Probability Code System for Calculating Neutron Flux Distributions in Hexagonal Geometry.

    Energy Science and Technology Software Center (ESTSC)

    1991-01-25

    Version 00 TPHEX calculates the multigroup neutron flux distribution in an assembly of hexagonal cells using a transmission probability (interface current) method. It is primarily intended for calculations on hexagonal LWR fuel assemblies but can be used for other purposes subject to the qualifications mentioned in Restrictions/Limitations.

  13. Computer program calculates gamma ray source strengths of materials exposed to neutron fluxes

    NASA Technical Reports Server (NTRS)

    Heiser, P. C.; Ricks, L. O.

    1968-01-01

    Computer program contains an input library of nuclear data for 44 elements and their isotopes to determine the induced radioactivity for gamma emitters. Minimum input requires the irradiation history of the element, a four-energy-group neutron flux, specification of an alloy composition by elements, and selection of the output.

  14. Minimum activation martensitic alloys for surface disposal after exposure to neutron flux

    DOEpatents

    Lechtenberg, Thomas

    1985-01-01

    Steel alloys for long-term exposure to neutron flux have a martensitic microstructure and contain chromium, carbon, tungsten, vanadium and preferably titanium. Activation of the steel is held to within acceptable limits for eventual surface disposal by stringently controlling the impurity levels of Ni, Mo, Cu, N, Co, Nb, Al and Mn.

  15. High Brightness Neutron Source for Radiography

    SciTech Connect

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  16. Biocompatibility of high-flux membranes.

    PubMed

    Putz, D; Barnas, U; Luger, A; Mayer, G; Woloszczuk, W; Graf, H

    1992-08-01

    Standard dialysis with cuprophane membranes is known to stimulate the immune system. As a result of activation of macrophages various interleukins and tumor necrosis factor (TNF) are secreted, presenting further evidence of the poor biocompatibility of cuprophane. We investigated the immunogenic properties of three modern high-flux membranes. Seven patients were studied during hemodiafiltration sessions using either a polysulfone (F60, Fresenius), a polymethylmetacrylate (BK 2.1, Toray) or a cellulose triacetate (FB-210 U, Nipro) dialyzer in a hemodiafiltration procedure. Serial measurements were made during each treatment of interleukin-1 beta (II-1 beta), TNF, soluble IL-2 receptor (sII-2r), soluble CD4 (sCD4), soluble CD8 (sCD8), interferon gamma (IFNg) and neopterin. In contrast to the known increase of IL-1 beta, IL-2r and TNF with cuprophane membranes, none of the modern high-flux dialyzers stimulated the production of these factors. Significant decreases of neopterin and sCD4 were observed. IFNg and sCD8 did not change significantly. Our results suggest that the modern high-flux dialyzers are non-immunogenic, and thus provide further evidence of the superior biocompatibility of synthetic or semisynthetic membranes over the conventional cuprophane. PMID:1399092

  17. Diurnally Varying Hydrogen Volatiles or Regolith Temperature? Mare and Highlands Studies of the Moon's Diurnally Modulating Epithermal Neutron Flux Using LRO's LEND, Diviner, and LOLA Instruments

    NASA Astrophysics Data System (ADS)

    McClanahan, T. P.; LEND Team; Parsons, A. M.; Williams, J. P.; Mazarico, E.

    2015-10-01

    In this study we seek to discriminate the source of variation that is diurnally modulating the Moon's neutron emission flux. We characterize the neutron emission flux from the topography in the northern mare and highlands regions.

  18. Neutron flux from a 14-MeV neutron generator with tungsten filter for research in NDA methods for nuclear safeguards and security

    SciTech Connect

    Rennhofer, H.; Pedersen, B.; Crochemore, J.-M.

    2009-12-02

    The Joint Research Centre has taken into operation a new experimental device designed for research in the fields of nuclear safeguards and security applications. The research projects currently undertaken include detection of shielded contraband materials, detection of fissile materials, and mass determination of small fissile materials in shielded containers. The device, called the Pulsed Neutron Interrogation Test Assembly (PUNITA), incorporates a pulsed 14-MeV (D-T) neutron generator and a large graphite mantle surrounding the sample cavity. By pulsing the neutron generator with a frequency in the range of 10 to 150 Hz, a sample may be interrogated first by fast neutrons and a few hundred micro-seconds later by a pure thermal neutron flux. The permanent detection systems incorporated in PUNITA include {sup 3}He neutrons detectors, HPGe gamma detectors, and lanthanum bromide scintillation detectors.We have studied the effects of placing a tungsten liner around the neutron generator target. The 14-MeV neutrons induce (n, 2n) and (n, 3n) reactions. In addition the mean neutron energy emitted from generator/tungsten assembly is reduced to about 1 MeV. Both of these effects increase the thermal neutron flux in the sample cavity. The paper describes the observed advantages of the tungsten liner with respect to increase in thermal flux, and better shielding capabilities of the nearby gamma and neutron detectors.

  19. High aspect ratio composite structures with 48.5% thermal neutron detection efficiency

    SciTech Connect

    Shao, Q.; Voss, L. F.; Conway, A. M.; Nikolic, R. J.; Dar, M. A.; Cheung, C. L.

    2013-02-11

    The pillar structured thermal neutron detector is based on the combination of high aspect ratio silicon p-i-n pillars surrounded by the neutron converter material {sup 10}B. By etching high aspect ratio pillar structures into silicon, the result is a device that efficiently absorbs the thermal neutron flux by accommodating a large volume fraction of {sup 10}B within the silicon pillar array. Here, we report a thermal neutron detection efficiency of 48.5% using a 50 {mu}m pillar array with an aspect ratio of 25:1.

  20. Experimental study of the interaction of pulsations of the neutron flux and the coolant flow in a boiling-water reactor

    SciTech Connect

    Leppik, P.A.

    1984-12-01

    This paper presents results of a study designed to confirm that the interaction of the neutron flux and the coolant flow plays an important role in the mechanism of high-frequency (HF) resonant instability of the VK-50 boiling water reactor. To do this and to check the working model, signals from probes measuring the flow rate of the coolant and the neutron flux were recorded simultaneously (with the help of a magnetograph) in experiments performed in 1981 on driving the VK-50 reactor into the HF reonant instability regimes. Estimates were then obtained for the statistical characteristics of the pulsations of the flow rate and of the neutron flux, including the cross-correlation functions and coherence functions. The basic results of these studies are reported here.

  1. Testing of actively cooled high heat flux mock-ups

    NASA Astrophysics Data System (ADS)

    Rödig, M.; Duwe, R.; Kühnlein, W.; Linke, J.; Scheerer, M.; Smid, I.; Wiechers, B.

    1998-10-01

    Several un-irradiated CFC monoblock mock-ups have been loaded in thermal fatigue tests up to 1000 cycles at power densities <25 MW/m 2. No indication of failure was observed for these loading conditions. Two of the mock-ups were inspected by ultra-sonic methods before thermal cycling. It could be proved that the voids found in the post-mortem metallography existed before and had no effect on the integrity of the mock-up. For the first time, neutron-irradiated CFC monoblock mock-ups have been tested in the electron beam facility JUDITH. These mock-ups had been irradiated before in the High Flux Reactor at Petten up to 0.3 dpa at 320°C and 770°C. All samples showed a significant increase of surface temperature, due to the irradiation induced decrease in thermal conductivity of the CFC materials.

  2. Diffuse fluxes of cosmic high energy neutrinos

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1978-01-01

    Production spectra of high-energy neutrinos from galactic cosmic ray interactions with interstellar gas and extragalactic ultrahigh energy cosmic-ray interactions with microwave black-body photons are presented and discussed. These production processes involve the decay of charged pions and are thus related to the production of cosmic gamma-rays from the decay of neutral pions. Estimates of the neutrino fluxes from various diffuse cosmic sources are then made and the reasons fro significant differences with previous estimates are discussed. Predicted event rates for a DUMAND type detection system are significantly lower than early estimates indicated.

  3. Ultra high resolution neutron scattering: Neutron Resonance Spin-Echo and Larmor Diffraction

    NASA Astrophysics Data System (ADS)

    Walters, Andrew; Keller, Thomas; Keimer, Bernhard

    2012-02-01

    The TRISP spectrometer at the FRM II neutron source near Munich, Germany, is a unique world-leading neutron scattering instrument which employs the Neutron Resonance Spin-Echo technique (NRSE). Linewidths of dispersive excitations with energy transfers up to 50 meV can be measured with an energy resolution in the μeV range without the restrictive flux limitations that normally apply to high resolution neutron triple-axis spectrometers. Pioneering studies on the electron-phonon interaction in elemental superconductorsootnotetextP. Aynajian et al., Science 319 1509 (2008) and the lifetimes of magnetic excitations in archetypal magnetic systems will be reviewed.ootnotetextS. Bayrakci et al., Science 312 1928 (2006) The instrument can also be used as a Larmor diffractometer, enabling d-spacings to be measured with a resolution of δdd ˜10-6, i.e. more than one order of magnitude more sensitive than conventional diffraction techniques.ootnotetextC. Pfleiderer et al., Science 316 1871 (2007) Ongoing and future NRSE and Larmor diffraction projects will be outlined, especially in regard to prospective studies which will take full advantage of the new low temperature and high pressure sample environment capabilities now available at TRISP.

  4. Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device.

    PubMed

    Isobe, M; Ogawa, K; Miyake, H; Hayashi, H; Kobuchi, T; Nakano, Y; Watanabe, K; Uritani, A; Misawa, T; Nishitani, T; Tomitaka, M; Kumagai, T; Mashiyama, Y; Ito, D; Kono, S; Yamauchi, M; Takeiri, Y

    2014-11-01

    A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ∼5 × 10(9) counts/s. Because a maximum total neutron emission rate over 1 × 10(16) n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design. PMID:25430293

  5. Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device

    SciTech Connect

    Isobe, M. Takeiri, Y.; Ogawa, K.; Miyake, H.; Hayashi, H.; Kobuchi, T.; Nakano, Y.; Watanabe, K.; Uritani, A.; Misawa, T.; Nishitani, T.; Tomitaka, M.; Kumagai, T.; Mashiyama, Y.; Ito, D.; Kono, S.; Yamauchi, M.

    2014-11-15

    A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ∼5 × 10{sup 9} counts/s. Because a maximum total neutron emission rate over 1 × 10{sup 16} n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design.

  6. Measurement of Neutron and Muon Fluxes 100~m Underground with the SciBath Detector

    SciTech Connect

    Garrison, Lance

    2014-01-01

    The SciBath detector is an 80 liter liquid scintillator detector read out by a three dimensional grid of 768 wavelength-shifting fibers. Initially conceived as a fine-grained charged particle detector for neutrino studies that could image charged particle tracks in all directions, it is also sensitive to fast neutrons (15-200 MeV). In fall of 2011 the apparatus performed a three month run to measure cosmic-induced muons and neutrons 100~meters underground in the FNAL MINOS near-detector area. Data from this run has been analyzed and resulted in measurements of the cosmic muon flux as \

  7. Neutron Powder Diffraction Measurements of the Spinel MgGa2O4:Cr3+ - A Comparative Study between the High Flux Diffractometer D2B at the ILL and the High Resolution Powder Diffractometer Aurora at IPEN

    NASA Astrophysics Data System (ADS)

    da Silva, M. A. F. M.; Sosman, L. P.; Yokaichiya, F.; Mazzocchi, V. L.; Parente, C. B. R.; Mestnik-Filho, J.; Henry, P. F.; Bordallo, H. N.

    2012-02-01

    Optical materials that emit from the visible to the near-infrared spectral region are of great interest due to their possible application as tunable radiation sources, as signal transmission, display, optoelectronics signal storage, cellulose industry as well as in dosimetry. One important family of such systems are the spinel compounds doped with Cr3+, in which the physical the properties are related to the insertion of punctual defects in the crystalline structure. The purpose of our work is two fold. First, we compare the luminescence of the MgGa2O4-Ga2O3 system with the single phase Ga2O3 and MgGa2O4 and relate structural changes observed in MgGa2O4-Ga2O3 system to the optical properties, and secondly, to compare the neutron powder diffraction results obtained using two diffractometers: D2B located at the ILL (Grenoble, France) and Aurora located at IPEN (São Paulo, Brazil). In the configuration chosen, Aurora shows an improved resolution, which is related to the design of its silicon focusing monochromator.

  8. Neutron source

    DOEpatents

    Cason, J.L. Jr.; Shaw, C.B.

    1975-10-21

    A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.

  9. Earthquake effects in thermal neutron variations at the high-altitude station of Northern

    NASA Astrophysics Data System (ADS)

    Antonova, Valentina; Chubenko, Alexandr; Kryukov, Sergey; Lutsenko, Vadim

    2016-04-01

    Results of study of thermal neutron variations under various space and geophysical conditions on the basis of measurements on stationary installations with high statistical accuracy are presented. Installations are located close to the fault of the earth's crust at the high-altitude station of cosmic rays (3340 m above sea level, 43.02 N, 76.56 E, 20 km from Almaty) in the mountains of Northern Tien-Shan. Responses of the most effective gelio- and geophysical events (variations of atmospheric pressure, coronal mass ejections, earthquakes) has consistently considered in the variations of the thermal neutron flux and compared with variations of high-energy neutrons (standard monitor 18NM64) of galactic origin during these periods. Coefficients of correlation were calculated between data of thermal neutron detectors and data of the neutron monitor, recording the intensity of high-energy particles. High correlation coefficients and similarity of responses to changes of space and geophysical conditions are obtained, that confirms the conclusion of the genetic connection of thermal neutrons with high-energy neutrons of galactic origin and suggests same sources of disturbances in the absence of seismic activity. Observations and analysis of experimental data during the activation of seismic activity in the vicinity of Almaty showed the frequent breakdown of the correlation between the intensity of thermal and high-energy neutrons and the absence of similarity between variations during these periods. We suppose that the additional thermal neutron flux of the lithospheric origin appears under these conditions. Method of separating of thermal neutron flux variations of the lithospheric origin from neutrons variations generated in the atmosphere by subtracting the normalized data is proposed, taking into account the conclusion that variations caused with the atmospheric and interplanetary origins in thermal neutron detectors are similar to variations of high-energy neutrons

  10. Theoretical models of flux pinning and flux motion in high-{Tc} superconducting oxides

    SciTech Connect

    Welch, D.O.

    1991-12-31

    Various issues involved in the development of phenomenological models of flux pinning and motion in high-{Tc} oxides are discussed. A simplified model is presented for the critical current density and is used to examine the question of whether flux flow results from an instability due to plasticity of the flux-line array or from pin breaking.

  11. Theoretical models of flux pinning and flux motion in high- Tc superconducting oxides

    SciTech Connect

    Welch, D.O.

    1991-01-01

    Various issues involved in the development of phenomenological models of flux pinning and motion in high-{Tc} oxides are discussed. A simplified model is presented for the critical current density and is used to examine the question of whether flux flow results from an instability due to plasticity of the flux-line array or from pin breaking.

  12. Neutron and high speed photogrammetric arcjet diagnosis

    NASA Technical Reports Server (NTRS)

    Stewart, P. A. E.; Rogers, J. D.; Fowler, P. H.; Deininger, W. D.; Taylor, A. D.

    1989-01-01

    Two methods for real time internal diagnostics of arcjet engines are described. One method uses cold, thermal, or epithermal neutrons. Cold neutrons are used to detect the presence and location of hydrogenous propellants. Thermal neutrons are used to delineate the edge contours of anode and cathode surfaces and to measure stress/strain. Epithermal neutrons are used to measure temperatures on arcjet surfaces, bulk material temperatures, and point temperatures in bulk materials. It is found that this method, with an exposure time of 10 min, produces at temperature accuracy for W or Re of + or - 2.5 C. The other method uses visible-light high-speed photogrammetry to obtain images of the transient behavior of the arc during start-up and to relate this behavior to electrial supply characteristics such as voltage, current, and ripple.

  13. Integral measurements of neutron and gamma-ray leakage fluxes from the Little Boy replica

    SciTech Connect

    Muckenthaler, F.J.

    1984-03-01

    This report presents integral measurements of neutron and gamma-ray leakage fluxes from a critical mockup of the Hiroshima bomb Little Boy at Los Alamos National Laobratory with detector systems developed by Oak Ridge National Laboratory. Bonner ball detectors were used to map the neutron fluxes in the horizontal midplane at various distances from the mockup and for selected polar angles, keeping the source-detector separation constant. Gamma-ray energy deposition measurements were made with thermoluminescent detectors at several locations on the iron shell of the source mockup. The measurements were performed as part of a larger progam to provide benchmark data for testing the methods used to calculate the radiation released from the Little Boy bomb over Hiroshima. 3 references, 10 figures.

  14. High-Flux and Low-Flux Membranes: Efficacy in Hemodialysis

    PubMed Central

    Oshvandi, Khodayar; Kavyannejad, Rasol; Borzuo, Sayed Reza; Gholyaf, Mahmoud

    2014-01-01

    Background: Inadequacy of dialysis is one of the main causes of death in hemodialysis patients. Some studies have suggested that high‐flux membrane improves the removal of moderate-sized molecules while other studies indicate no significant effect on them. Objectives: This study aimed to investigate the dialysis efficacy of low-flux versus high-flux membranes in hemodialysis patients. Patients and Methods: Forty hemodialysis patients participated in this cross-over clinical trial. Two sessions of low-flux and high-flux membrane dialysis were performed consecutively, in the first and second stage of the trial. In both stages, blood samples before and after the dialysis were taken and sent to the laboratory for assessment. Blood urea nitrogen (BUN), KT/V and the urea reduction ratio (URR) indexes were used to determine dialysis efficacy. Data were analyzed using t test and paired t test. Results: The mean KT/V was 1.27 ± 0.28 in high-flux and 1.10 ± 0.32 in low-flux membrane which, these differences were statistically significant (P = 0.017). The mean of URR was 0.65 ± 0.09 in high-flux and 0.61 ± 0.14 in low-flux membrane, which these differences were not statistically significant (P = 0.221). Conclusions: The high-flux membrane had better dialysis adequacy, so we suggest using high-flux membrane in hemodialysis centers. PMID:25699283

  15. High flux isotope reactor cold source preconceptual design study report

    SciTech Connect

    Selby, D.L.; Bucholz, J.A.; Burnette, S.E.

    1995-12-01

    In February 1995, the deputy director of Oak Ridge National Laboratory (ORNL) formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced Neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. The anticipated cold source will consist of a cryogenic LH{sub 2} moderator plug, a cryogenic pump system, a refrigerator that uses helium gas as a refrigerant, a heat exchanger to interface the refrigerant with the hydrogen loop, liquid hydrogen transfer lines, a gas handling system that includes vacuum lines, and an instrumentation and control system to provide constant system status monitoring and to maintain system stability. The scope of this project includes the development, design, safety analysis, procurement/fabrication, testing, and installation of all of the components necessary to produce a working cold source within an existing HFIR beam tube. This project will also include those activities necessary to transport the cold neutron beam to the front face of the present HFIR beam room. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and research and development (R and D), (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the preconceptual phase and establishes the concept feasibility. The information presented includes the project scope, the preliminary design requirements, the preliminary cost and schedule, the preliminary performance data, and an outline of the various plans for completing the project.

  16. Neutron flux characterisation of the Pavia TRIGA Mark II research reactor for radiobiological and microdosimetric applications.

    PubMed

    Alloni, D; Prata, M; Salvini, A; Ottolenghi, A

    2015-09-01

    Nowadays the Pavia TRIGA reactor is available for national and international collaboration in various research fields. The TRIGA Mark II nuclear research reactor of the Pavia University offers different in- and out-core neutron irradiation channels, each characterised by different neutron spectra. In the last two years a campaign of measurements and simulations has been performed in order to guarantee a better characterisation of these different fluxes and to meet the demands of irradiations that require precise information on these spectra in particular for radiobiological and microdosimetric studies. Experimental data on neutron fluxes have been collected analysing and measuring the gamma activity induced in thin target foils of different materials irradiated in different TRIGA experimental channels. The data on the induced gamma activities have been processed with the SAND II deconvolution code and finally compared with the spectra obtained with Monte Carlo simulations. The comparison between simulated and measured spectra showed a good agreement allowing a more precise characterisation of the neutron spectra and a validation of the adopted method. PMID:25958412

  17. High-flux first-wall design for a small reversed-field pinch reactor

    NASA Astrophysics Data System (ADS)

    Cort, G. E.; Graham, A. L.; Christensen, K. E.

    To achieve the goal of a commercially economical fusion power reactor, small physical size and high power density should be combined with simplicity (minimized use of high technology systems). The Reversed-Field Pinch (RFP) is a magnetic confinement device that promises to meet these requirements with power densities comparable to those in existing fission power plants. To establish feasibility of such an RFP reactor, a practical design for a first wall capable of withstanding high levels of cyclic neutron wall loadings is needed. Associated with the neutron flux in the proposed RFP reactor is a time averaged heat flux of 4.5 MW/sq m with a conservatively estimated transient peak approximately twice the average value. The design for a modular first wall made from a high-strength copper alloy that will meet these requirements of cyclic thermal loading is presented. The heat removal from the wall is by subcooled water flowing in straight tubes at high linear velocities.

  18. On Poynting-flux-driven bubbles and shocks around merging neutron star binaries

    NASA Astrophysics Data System (ADS)

    Medvedev, Mikhail V.; Loeb, Abraham

    2013-05-01

    Merging binaries of compact relativistic objects (neutron stars and black holes) are thought to be progenitors of short gamma-ray bursts and sources of gravitational waves, hence their study is of great importance for astrophysics. Because of the strong magnetic field of one or both binary members and high orbital frequencies, these binaries are strong sources of energy in the form of Poynting flux (e.g. magnetic-field-dominated outflows, relativistic leptonic winds, electromagnetic and plasma waves). The steady injection of energy by the binary forms a bubble (or a cavity) filled with matter with the relativistic equation of state, which pushes on the surrounding plasma and can drive a shock wave in it. Unlike the Sedov-von Neumann-Taylor blast wave solution for a point-like explosion, the shock wave here is continuously driven by the ever-increasing pressure inside the bubble. We calculate from the first principles the dynamics and evolution of the bubble and the shock surrounding it and predict that such systems can be observed as radio sources a few hours before and after the merger. At much later times, the shock is expected to settle on to the Sedov-von Neumann-Taylor solution, thus resembling an explosion.

  19. First PGAA and NAA experimental results from a compact high intensity D-D neutron generator

    SciTech Connect

    Reijonen, J.; Leung, K.-N.; Firestone, R.B.; English, J.A.; Perry, D.L.; Smith, A.; Gicquel, F.; Sun, M.; Bandong, B.; Garabedian, G.; Revay, Zs.; Szentmiklosi, L.; Molnar, G.

    2003-05-13

    Various types of neutron generator systems have been designed and tested at the Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory. These generators are based on a D-D fusion reaction. These high power D-D neutron generators can provide neutron fluxes in excess of the current state of the art D-T neutron generators, without the use of pre-loaded targets or radioactive tritium gas. Safe and reliable long-life operations are the typical features of these D-D generators. All of the neutron generators developed in the Plasma and Ion Source Technology Group are utilizing powerful RF-induction discharge to generate the deuterium plasma. One of the advantages of using the RF-induction discharge is it's ability to generate high fraction of atomic ions from molecular gases, and the ability to generate high plasma densities for high extractable ion current from relatively small discharge volume.

  20. Characterization of the high-energy neutron beam of the PRISMA beamline using a diamond detector

    NASA Astrophysics Data System (ADS)

    Cazzaniga, C.; Frost, C. D.; Minniti, T.; Schooneveld, E.; Perelli Cippo, E.; Tardocchi, M.; Rebai, M.; Gorini, G.

    2016-07-01

    The high-energy neutron component (En > 10 MeV) of the neutron spectrum of PRISMA, a beam-line at the ISIS spallation source, has been characterized for the first time. Neutron measurements using a Single-crystal Diamond Detector at a short-pulse source are obtained by a combination of pulse height and time of flight analysis. An XY scan provides a 2D map of the high-energy neutron beam which has a diameter of about 40 mm. The high neutron flux, that has been found to be (3.8 ± 0.7) · 105 cm‑2s‑1 for En > 10 MeV in the centre, opens up for a possible application of the beam-line as a high-energy neutron irradiation position. Results are of interest for the development of the ChipIR beam-line, which will feature an atmospheric-like neutron spectrum for chip irradiation experiment. Furthermore, these results demonstrate that diamond detectors can be used at spallation sources to investigate the transport of high-energy neutrons down instruments which is of interest in general to designers as high-energy neutrons are a source of background in thermal beamlines.

  1. Flux and instrumentation upgrade for the epithermal neutron beam facility at Washington State University.

    PubMed

    Nigg, D W; Venhuizen, J R; Wemple, C A; Tripard, G E; Sharp, S; Fox, K

    2004-11-01

    An epithermal neutron beam facility for preclinical neutron capture therapy research has been constructed at the Washington State University TRIGA research reactor installation. Subsequent to a recent upgrade, this new facility offers a high-purity epithermal beam with intensity on the order of 1.2x10(9)n/cm(2)s. Key features include a fluoride-based design for the neutron filtering and moderating components as well as a novel collimator design that allows ease of assembly and disassembly of the beamline components. PMID:15308181

  2. Flux and Instrumentation Upgrade for the Epithermal Neutron Beam Facility at Washington State University

    SciTech Connect

    David W. Nigg; J.R. Venhuizen; C.E. Wemple; G. E. Tripard; S. Sharp; K. Fox

    2004-11-01

    An epithermal neutron beam facility for preclinical neutron capture therapy research has been constructed at the Washington State University TRIGA research reactor installation. Subsequent to a recent upgrade, this new facility offers a high-purity epithermal beam with intensity on the order of 1.2×109 n/cm2 s. Key features include a fluoride-based design for the neutron filtering and moderating components as well as a novel collimator design that allows ease of assembly and disassembly of the beamline components.

  3. A high temperature high pressure cell for quasielastic neutron scattering.

    PubMed

    Yang, F; Kaplonski, J; Unruh, T; Mamontov, E; Meyer, A

    2011-08-01

    We present our recent development of a high temperature high pressure cell for neutron scattering. Combining a water cooled Nb1Zr pressure cell body with an internal heating furnace, the sample environment can reach temperatures of up to 1500 K at a pressure of up to 200 MPa at the sample position, with an available sample volume of about 700 mm(3). The cell material Nb1Zr is specifically chosen due to its reasonable mechanical strength at elevated temperatures and fairly small neutron absorption and incoherent scattering cross sections. With this design, an acceptable signal-to-noise ratio of about 10:1 can be achieved. This opens new possibilities for quasielastic neutron scattering studies on different types of neutron spectrometers under high temperature high pressure conditions, which is particularly interesting for geological research on, e.g., water dynamics in silicate melts. PMID:21895254

  4. A high temperature high pressure cell for quasielastic neutron scattering

    SciTech Connect

    Yang, F.; Meyer, A.; Kaplonski, J.; Unruh, T.; Mamontov, E.

    2011-08-15

    We present our recent development of a high temperature high pressure cell for neutron scattering. Combining a water cooled Nb1Zr pressure cell body with an internal heating furnace, the sample environment can reach temperatures of up to 1500 K at a pressure of up to 200 MPa at the sample position, with an available sample volume of about 700 mm{sup 3}. The cell material Nb1Zr is specifically chosen due to its reasonable mechanical strength at elevated temperatures and fairly small neutron absorption and incoherent scattering cross sections. With this design, an acceptable signal-to-noise ratio of about 10:1 can be achieved. This opens new possibilities for quasielastic neutron scattering studies on different types of neutron spectrometers under high temperature high pressure conditions, which is particularly interesting for geological research on, e.g., water dynamics in silicate melts.

  5. A Numerical Method for Obtaining Monoenergetic Neutron Flux Distributions and Transmissions in Multiple-Region Slabs

    NASA Technical Reports Server (NTRS)

    Schneider, Harold

    1959-01-01

    This method is investigated for semi-infinite multiple-slab configurations of arbitrary width, composition, and source distribution. Isotropic scattering in the laboratory system is assumed. Isotropic scattering implies that the fraction of neutrons scattered in the i(sup th) volume element or subregion that will make their next collision in the j(sup th) volume element or subregion is the same for all collisions. These so-called "transfer probabilities" between subregions are calculated and used to obtain successive-collision densities from which the flux and transmission probabilities directly follow. For a thick slab with little or no absorption, a successive-collisions technique proves impractical because an unreasonably large number of collisions must be followed in order to obtain the flux. Here the appropriate integral equation is converted into a set of linear simultaneous algebraic equations that are solved for the average total flux in each subregion. When ordinary diffusion theory applies with satisfactory precision in a portion of the multiple-slab configuration, the problem is solved by ordinary diffusion theory, but the flux is plotted only in the region of validity. The angular distribution of neutrons entering the remaining portion is determined from the known diffusion flux and the remaining region is solved by higher order theory. Several procedures for applying the numerical method are presented and discussed. To illustrate the calculational procedure, a symmetrical slab ia vacuum is worked by the numerical, Monte Carlo, and P(sub 3) spherical harmonics methods. In addition, an unsymmetrical double-slab problem is solved by the numerical and Monte Carlo methods. The numerical approach proved faster and more accurate in these examples. Adaptation of the method to anisotropic scattering in slabs is indicated, although no example is included in this paper.

  6. High heat flux engineering in solar energy applications

    SciTech Connect

    Cameron, C.P.

    1993-07-01

    Solar thermal energy systems can produce heat fluxes in excess of 10,000 kW/m{sup 2}. This paper provides an introduction to the solar concentrators that produce high heat flux, the receivers that convert the flux into usable thermal energy, and the instrumentation systems used to measure flux in the solar environment. References are incorporated to direct the reader to detailed technical information.

  7. A comparative study of the neutron flux spectra in the MNSR irradiation sites for the HEU and LEU cores using the MCNP4C code.

    PubMed

    Dawahra, S; Khattab, K; Saba, G

    2015-10-01

    A comparative study for fuel conversion from the HEU to LEU in the Miniature Neutron Source Reactor (MNSR) has been performed in this paper using the MCNP4C code. The neutron energy and lethargy flux spectra in the first inner and outer irradiation sites of the MNSR reactor for the existing HEU fuel (UAl4-Al, 90% enriched) and the potential LEU fuels (U3Si2-Al, U3Si-Al, U9Mo-Al, 19.75% enriched and UO2, 12.6% enriched) were investigated using the MCNP4C code. The neutron energy flux spectra for each group was calculated by dividing the neutron flux by the width of each energy group. The neutron flux spectra per unit lethargy was calculated by multiplying the neutron energy flux spectra for each energy group by the average energy of each group. The thermal neutron flux was calculated by summing the neutron fluxes from 0.0 to 0.625 eV, the fast neutron flux was calculated by summing the neutron fluxes from 0.5 MeV to 10 MeV for the existing HEU and potential LEU fuels. Good agreements have been noticed between the flux spectra for the potential LEU fuels and the existing HEU fuels with maximum relative differences less than 10% and 8% in the inner and outer irradiation sites. PMID:26142805

  8. Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source

    SciTech Connect

    Lacy, Jeffrey L

    2009-05-22

    Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically

  9. Superconducting High Resolution Fast-Neutron Spectrometers

    SciTech Connect

    Hau, I D

    2006-05-25

    Superconducting high resolution fast-neutron calorimetric spectrometers based on {sup 6}LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, {alpha}) reactions with fast neutrons in {sup 6}Li and {sup 10}B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies k{sub B}T on the order of {mu}eV that serve as signal carriers, resulting in an energy resolution {Delta}E {approx} (k{sub B}T{sup 2}C){sup 1/2}, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB{sub 2} absorber using thermal neutrons from a {sup 252}Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in {sup 7}Li. Fast-neutron spectra obtained with a {sup 6}Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the {sup 6}Li(n, {alpha}){sup 3}H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.

  10. Influence of neutron flux, frequency and temperature to electrical impedance of nano silica particles

    SciTech Connect

    Huseynov, Elchin E-mail: hus.elchin@gmail.com; Garibov, Adil; Mehdiyeva, Ravan; Andreja, Eršte; Rustamov, Anar

    2014-11-15

    We studied electric impedance of SiO{sub 2} nanomaterial at its initial state and after being exposed to continuous neutron irradiation for up to 20 hours. In doing so we employed a flux of neutrons of 2x10{sup 13} n⋅cm{sup −2}s{sup −1} while the frequency and temperature ranges amounted to 0,09 – 2.3 MHz and 100 – 400 K correspondingly. Analysis in terms of the Cole-Cole expression revealed that with increasing irradiation period the polarization and relaxation times decrease as a result of combination of nanoparticles. Moreover, it is demonstrated that the electric conductivity of samples, on the other hand, increases with the increasing irradiation period. At low temperatures formations of clusters at three distinct states with different energies were resolved.

  11. Anisn-Dort Neutron-Gamma Flux Intercomparison Exercise for a Simple Testing Model

    NASA Astrophysics Data System (ADS)

    Boehmer, B.; Konheiser, J.; Borodkin, G.; Brodkin, E.; Egorov, A.; Kozhevnikov, A.; Zaritsky, S.; Manturov, G.; Voloschenko, A.

    2003-06-01

    The ability of transport codes ANISN, DORT, ROZ-6, MCNP and TRAMO, as well as nuclear data libraries BUGLE-96, ABBN-93, VITAMIN-B6 and ENDF/B-6 to deliver consistent gamma and neutron flux results was tested in the calculation of a one-dimensional cylindrical model consisting of a homogeneous core and an outer zone with a single material. Model variants with H2O, Fe, Cr and Ni in the outer zones were investigated. The results are compared with MCNP-ENDF/B-6 results. Discrepancies are discussed. The specified test model is proposed as a computational benchmark for testing calculation codes and data libraries.

  12. A high yield neutron target

    NASA Technical Reports Server (NTRS)

    Alger, D. L.; Steinberg, R.; Weisenbach, P.

    1974-01-01

    Target, in cylinder form, rotates rapidly in front of beam. Titanium tritide film is much thicker than range of accelerated deutron. Sputtering electrode permits full use of thick film. Stream of high-velocity coolant provides efficient transfer of heat from target.

  13. Calculated Neutron and Gamma-ray Spectra across the Prismatic Very High Temperature Reactor Core

    SciTech Connect

    James W. Sterbentz

    2008-05-01

    Neutron and gamma-ray flux spectra are calculated using the MCNP5 computer code and a one-sixth core model of a prismatic Very High Temperature Reactor based on the General Atomics Gas Turbine-Modular Helium Reactor. Spectra are calculated in the five inner reflector graphite block rings, three annular active core fuel rings, three outer graphite reflector block rings, and the core barrel. The neutron spectra are block and fuel pin averages and are calculated as a function of temperature and burnup. Also provided are the total, fast, and thermal radial profile fluxes and core barrel dpa rates.

  14. In-situ monitoring the realkalisation process by neutron diffraction: Electroosmotic flux and portlandite formation

    SciTech Connect

    Castellote, Marta . E-mail: martaca@ietcc.csic.es; Llorente, Irene; Andrade, Carmen; Turrillas, Xavier; Alonso, Cruz; Campo, Javier

    2006-05-15

    Even though the electroosmotic flux through hardened cementitious materials during laboratory realkalisation trials had been previously noticed, it has never been in-situ monitored, analysing at the same time the establishment of the electroosmotic flux and the microstructure changes in the surroundings of the rebar. In this paper, two series of cement pastes, cast with CEM I and CEM I substituted in a 35% by fly ash, previously carbonated at 100% CO{sub 2}, were submitted to realkalisation treatments followed on line by simultaneous acquisition of neutron diffraction data. As a result, it has been possible to confirm the electroosmosis as the driving force of carbonates towards the rebar and to determine the range of pH in the anolyte in which most of the relevant electroosmotic phenomena takes place. On the other hand, the behaviour of the main crystalline phases involved in the process has been monitored during the treatment, with the precipitation of portlandite as main result.

  15. Numerical studies of the flux-to-current ratio method in the KIPT neutron source facility

    SciTech Connect

    Cao, Y.; Gohar, Y.; Zhong, Z.

    2013-07-01

    The reactivity of a subcritical assembly has to be monitored continuously in order to assure its safe operation. In this paper, the flux-to-current ratio method has been studied as an approach to provide the on-line reactivity measurement of the subcritical system. Monte Carlo numerical simulations have been performed using the KIPT neutron source facility model. It is found that the reactivity obtained from the flux-to-current ratio method is sensitive to the detector position in the subcritical assembly. However, if multiple detectors are located about 12 cm above the graphite reflector and 54 cm radially, the technique is shown to be very accurate in determining the k{sub eff} this facility in the range of 0.75 to 0.975. (authors)

  16. High momentum protons in superdense neutron matter

    NASA Astrophysics Data System (ADS)

    Sargsian, Misak M.

    2013-10-01

    Recent observations of strong dominance of pn as compared to pp and nn short range correlations (SRCs) in nuclei indicate on possibility of unique new condition for asymmetric high density nuclear matter, in which the pp and nn interactions are suppressed while the pn interactions are enhanced due to tensor interaction. We demonstrate that, due to this enhancement, in high density neutron matter containing small portion of proton component the momentum distribution of protons is strongly deformed towards the high momentum states. This result is obtained by extracting the probabilities of two-nucleon (2N) SRCs from the analysis of the experimental data on high momentum transfer A(e,'e)X reactions and fitting them as a function of nuclear density and asymmetry. Using this fit we estimated that starting at three nuclear saturation densities the protons with fractional densities xp = 1/9 will populate mostly the high momentum tail of the momentum distribution while only few% of the neutrons will do so. We discuss the possible implications of this result for neutron stars.

  17. Utilization of the High Flux Isotope Reactor at Oak Ridge National Laboratory

    SciTech Connect

    Selby, Douglas L; Bilheux, Hassina Z; Meilleur, Flora; Jones, Amy; Bailey, William Barton; Vandergriff, David H

    2015-01-01

    This paper addresses several aspects of the scientific utilization of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR). Topics to be covered will include: 1) HFIR neutron scattering instruments and the formal instrument user program; 2) Recent upgrades to the neutron scattering instrument stations at the reactor, and 3) eMod a new tool for addressing instrument modifications and providing configuration control and design process for scientific instruments at HFIR and the Spallation Neutron Source (SNS). There are 15 operating neutron instrument stations at HFIR with 12 of them organized into a formal user program. Since the last presentation on HFIR instruments at IGORR we have installed a Single Crystal Quasi-Laue Diffractometer instrument called IMAGINE; and we have made significant upgrades to HFIR neutron scattering instruments including the Cold Triple Axis Instrument, the Wide Angle Neutron Diffractometer, the Powder Diffractometer, and the Neutron Imaging station. In addition, we have initiated upgrades to the Thermal Triple Axis Instrument and the Bio-SANS cold neutron instrument detector system. All of these upgrades are tied to a continuous effort to maintain a high level neutron scattering user program at the HFIR. For the purpose of tracking modifications such as those mentioned and configuration control we have been developing an electronic system for entering instrument modification requests that follows a modification or instrument project through concept development, design, fabrication, installation, and commissioning. This system, which we call eMod, electronically leads the task leader through a series of questions and checklists that then identifies such things as ES&H and radiological issues and then automatically designates specific individuals for the activity review process. The system has been in use for less than a year and we are still working out some of the inefficiencies, but we believe that this will become a very

  18. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  19. Rebuilding the Brookhaven high flux beam reactor: A feasibility study

    SciTech Connect

    Brynda, W.J.; Passell, L.; Rorer, D.C.

    1995-01-01

    After nearly thirty years of operation, Brookhaven`s High Flux Beam Reactor (HFBR) is still one of the world`s premier steady-state neutron sources. A major center for condensed matter studies, it currently supports fifteen separate beamlines conducting research in fields as diverse as crystallography, solid-state, nuclear and surface physics, polymer physics and structural biology and will very likely be able to do so for perhaps another decade. But beyond that point the HFBR will be running on borrowed time. Unless appropriate remedial action is taken, progressive radiation-induced embrittlement problems will eventually shut it down. Recognizing the HFBR`s value as a national scientific resource, members of the Laboratory`s scientific and reactor operations staffs began earlier this year to consider what could be done both to extend its useful life and to assure that it continues to provide state-of-the-art research facilities for the scientific community. This report summarizes the findings of that study. It addresses two basic issues: (i) identification and replacement of lifetime-limiting components and (ii) modifications and additions that could expand and enhance the reactor`s research capabilities.

  20. 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.

  1. Measuring neutron fluences and gamma/x-ray fluxes with CCD cameras

    SciTech Connect

    Yates, G.J.; Smith, G.W.; Zagarino, P.; Thomas, M.C.

    1991-12-01

    The capability to measure bursts of neutron fluences and gamma/x-ray fluxes directly with charge coupled device (CCD) cameras while being able to distinguish between the video signals produced by these two types of radiation, even when they occur simultaneously, has been demonstrated. Volume and area measurements of transient radiation-induced pixel charge in English Electric Valve (EEV) Frame Transfer (FT) charge coupled devices (CCDs) from irradiation with pulsed neutrons (14 MeV) and Bremsstrahlung photons (4--12 MeV endpoint) are utilized to calibrate the devices as radiometric imaging sensors capable of distinguishing between the two types of ionizing radiation. Measurements indicate {approx}.05 V/rad responsivity with {ge}1 rad required for saturation from photon irradiation. Neutron-generated localized charge centers or ``peaks`` binned by area and amplitude as functions of fluence in the 10{sup 5} to 10{sup 7} n/cm{sup 2} range indicate smearing over {approx}1 to 10% of CCD array with charge per pixel ranging between noise and saturation levels.

  2. Periods of High Intensity Solar Proton Flux

    NASA Technical Reports Server (NTRS)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.

    2012-01-01

    Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  3. HIGH FLUENCE NEUTRON SOURCE FOR NONDESTRUCTIVE CHARACTERIZATION OF NUCLEAR WASTE

    EPA Science Inventory

    We propose to research the basic plasma physics necessary to develop a high fluence neutron source based on the inertial electrostatically confined (IEC) plasma. An intense neutron source directly addresses the capability to characterize nuclear materials under difficult measurem...

  4. Measurements with the high flux lead slowing-down spectrometer at LANL

    NASA Astrophysics Data System (ADS)

    Danon, Y.; Romano, C.; Thompson, J.; Watson, T.; Haight, R. C.; Wender, S. A.; Vieira, D. J.; Bond, E.; Wilhelmy, J. B.; O'Donnell, J. M.; Michaudon, A.; Bredeweg, T. A.; Schurman, T.; Rochman, D.; Granier, T.; Ethvignot, T.; Taieb, J.; Becker, J. A.

    2007-08-01

    A Lead Slowing-Down Spectrometer (LSDS) was recently installed at LANL [D. Rochman, R.C. Haight, J.M. O'Donnell, A. Michaudon, S.A. Wender, D.J. Vieira, E.M. Bond, T.A. Bredeweg, A. Kronenberg, J.B. Wilhelmy, T. Ethvignot, T. Granier, M. Petit, Y. Danon, Characteristics of a lead slowing-down spectrometer coupled to the LANSCE accelerator, Nucl. Instr. and Meth. A 550 (2005) 397]. The LSDS is comprised of a cube of pure lead 1.2 m on the side, with a spallation pulsed neutron source in its center. The LSDS is driven by 800 MeV protons with a time-averaged current of up to 1 μA, pulse widths of 0.05-0.25 μs and a repetition rate of 20-40 Hz. Spallation neutrons are created by directing the proton beam into an air-cooled tungsten target in the center of the lead cube. The neutrons slow down by scattering interactions with the lead and thus enable measurements of neutron-induced reaction rates as a function of the slowing-down time, which correlates to neutron energy. The advantage of an LSDS as a neutron spectrometer is that the neutron flux is 3-4 orders of magnitude higher than a standard time-of-flight experiment at the equivalent flight path, 5.6 m. The effective energy range is 0.1 eV to 100 keV with a typical energy resolution of 30% from 1 eV to 10 keV. The average neutron flux between 1 and 10 keV is about 1.7 × 109 n/cm2/s/μA. This high flux makes the LSDS an important tool for neutron-induced cross section measurements of ultra-small samples (nanograms) or of samples with very low cross sections. The LSDS at LANL was initially built in order to measure the fission cross section of the short-lived metastable isotope of U-235, however it can also be used to measure (n, α) and (n, p) reactions. Fission cross section measurements were made with samples of 235U, 236U, 238U and 239Pu. The smallest sample measured was 10 ng of 239Pu. Measurement of (n, α) cross section with 760 ng of Li-6 was also demonstrated. Possible future cross section measurements

  5. Development of micro-pocket fission detectors (MPFD) for near-core and in-core neutron flux monitoring

    NASA Astrophysics Data System (ADS)

    Ohmes, Martin F.; McGregor, Douglas S.; Shultis, J. Kenneth; Whaley, P. Michael; Ahmed, A. S. M. Sabbir; Bolinger, Clayton C.; Pinsent, Tracy C.

    2004-01-01

    Miniaturized Micro-Pocket Fission Detectors (MPFD) are under investigation as real-time neutron flux monitors. The devices are capable of performing near-core and in-core reactor power measurements. The basic design utilizes neutron reactive material confined within a miniaturized gas pocket, similar to that of a fission chamber. Device size ranges from 500 microns to a few millimeters thick, thereby allowing them to be inserted directly between fuel elements of a reactor core. Fabricated from inexpensive ceramic materials, the detectors can be fashioned into a linear array to facilitate 3-D mapping of a reactor core neutron flux profile in "real-time". Initial tests have shown these devices to be extremely radiation hard and potentially capable of operating in a neutron fluence exceeding 1016 n cm-2 without noticeable degradation.

  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. Spectrum and density of neutron flux in the irradiation beam line no. 3 of the IBR-2 reactor

    NASA Astrophysics Data System (ADS)

    Shabalin, E. P.; Verkhoglyadov, A. E.; Bulavin, M. V.; Rogov, A. D.; Kulagin, E. N.; Kulikov, S. A.

    2015-03-01

    Methodology and results of measuring the differential density of the neutron flux in irradiation beam line no. 3 of the IBR-2 reactor using neutron activation analysis (NAA) are presented in the paper. The results are compared to the calculation performed on the basis of the 3D MCNP model. The data that are obtained are required to determine the integrated radiation dose of the studied samples at various distances from the reactor.

  8. High Intensity, Pulsed, D-D Neutron Generator

    NASA Astrophysics Data System (ADS)

    Williams, D. L.; Vainionpaa, J. H.; Jones, G.; Piestrup, M. A.; Gary, C. K.; Harris, J. L.; Fuller, M. J.; Cremer, J. T.; Ludewigt, B. A.; Kwan, J. W.; Reijonen, J.; Leung, K.-N.; Gough, R. A.

    2009-03-01

    Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1010 n/s. Previously, Adelphi and LBNL have demonstrated these generators' applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

  9. High Intensity, Pulsed, D-D Neutron Generator

    SciTech Connect

    Williams, D. L.; Vainionpaa, J. H.; Jones, G.; Piestrup, M. A.; Gary, C. K.; Harris, J. L.; Fuller, M. J.; Cremer, J. T.; Ludewigt, Bernhard A.; Kwan, J. W.; Reijonen, J.; Leung, K.-N.; Gough, R. A.

    2008-08-01

    Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1E10 n/s. Previously, Adelphi and LBNL have demonstrated these generators' applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

  10. Analysis of neutron flux distribution for the validation of computational methods for the optimization of research reactor utilization.

    PubMed

    Snoj, L; Trkov, A; Jaćimović, R; Rogan, P; Zerovnik, G; Ravnik, M

    2011-01-01

    In order to verify and validate the computational methods for neutron flux calculation in TRIGA research reactor calculations, a series of experiments has been performed. The neutron activation method was used to verify the calculated neutron flux distribution in the TRIGA reactor. Aluminium (99.9 wt%)-Gold (0.1 wt%) foils (disks of 5mm diameter and 0.2mm thick) were irradiated in 33 locations; 6 in the core and 27 in the carrousel facility in the reflector. The experimental results were compared to the calculations performed with Monte Carlo code MCNP using detailed geometrical model of the reactor. The calculated and experimental normalized reaction rates in the core are in very good agreement for both isotopes indicating that the material and geometrical properties of the reactor core are modelled well. In conclusion one can state that our computational model describes very well the neutron flux and reaction rate distribution in the reactor core. In the reflector however, the accuracy of the epithermal and thermal neutron flux distribution and attenuation is lower, mainly due to lack of information about the material properties of the graphite reflector surrounding the core, but the differences between measurements and calculations are within 10%. Since our computational model properly describes the reactor core it can be used for calculations of reactor core parameters and for optimization of research reactor utilization. PMID:20855215

  11. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

    DOE PAGESBeta

    Mauro, N. A.; Vogt, A. J.; Derendorf, K. S.; Johnson, M. L.; Rustan, G. E.; Quirinale, D. G.; Kreyssig, A.; Lokshin, K. A.; Neuefeind, J. C.; An, Ke; et al

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. But, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elasticmore » and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. Furthermore, to demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample ( 100 mg).« less

  12. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

    SciTech Connect

    Mauro, N. A.; Vogt, A. J.; Derendorf, K. S.; Johnson, M. L.; Rustan, G. E.; Quirinale, D. G.; Kreyssig, A.; Lokshin, K. A.; Neuefeind, J. C.; An, Ke; Wang, Xun-Li; Goldman, A. I.; Egami, T.; Kelton, K. F.

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. But, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. Furthermore, to demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample ( 100 mg).

  13. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

    NASA Astrophysics Data System (ADS)

    Mauro, N. A.; Vogt, A. J.; Derendorf, K. S.; Johnson, M. L.; Rustan, G. E.; Quirinale, D. G.; Kreyssig, A.; Lokshin, K. A.; Neuefeind, J. C.; An, Ke; Wang, Xun-Li; Goldman, A. I.; Egami, T.; Kelton, K. F.

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (˜100 mg).

  14. Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source.

    PubMed

    Mauro, N A; Vogt, A J; Derendorf, K S; Johnson, M L; Rustan, G E; Quirinale, D G; Kreyssig, A; Lokshin, K A; Neuefeind, J C; An, Ke; Wang, Xun-Li; Goldman, A I; Egami, T; Kelton, K F

    2016-01-01

    Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (∼100 mg). PMID:26827330

  15. Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

    2015-12-01

    BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source. PMID:26302662

  16. Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

    NASA Technical Reports Server (NTRS)

    Moon, S.; Simnett, G. M.; White, R. S.

    1975-01-01

    The UCR large area solid-angle double scatter neutron telescope was flown to search for solar neutrons on 3 balloon flights on September 26, 1971, May 14, 1972 and September 19, 1972. The first two flights were launched from Palestine, Texas and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet time solar neutron fluxes at the 95% confidence level are .00028, .00046, .00096 and .00090 neutrons/sq cm-sec in the energy intervals of 10-30, 30-50, 50-100 and 10-100 MeV, respectively.

  17. Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments.

    PubMed

    Lee, K W; Sheu, R J

    2015-04-01

    High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with (252)Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing (252)Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6_8 extended-range sphere versus the 6″ standard sphere). PMID:25280480

  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. Study of blend composition of nano silica under the influence of neutron flux

    NASA Astrophysics Data System (ADS)

    Huseynov, Elchin; Garibov, Adil; Mehdiyeva, Ravan

    2014-08-01

    Nano SiO2 compound with 160 m2/g specific surface area and 20 nm sizes has been irradiated continuously with neutron flux up to 20 hours in various periods in TRIGA Mark II type research reactor. The initial activities of different type radionuclides defined in the result of eight day activity analysis changes between wide range of 1,5 kBq- 1,5GBq. In the result of activity analysis carried out after the irradiation, the element content of 0,5% mixture existing in nano SiO2 compound has been defined with radionuclides of relevant element. It has been defined percentage amounts of elements in blend composition according to the performed activities.

  20. Verification of MCNP simulation of neutron flux parameters at TRIGA MK II reactor of Malaysia.

    PubMed

    Yavar, A R; Khalafi, H; Kasesaz, Y; Sarmani, S; Yahaya, R; Wood, A K; Khoo, K S

    2012-10-01

    A 3-D model for 1 MW TRIGA Mark II research reactor was simulated. Neutron flux parameters were calculated using MCNP-4C code and were compared with experimental results obtained by k(0)-INAA and absolute method. The average values of φ(th),φ(epi), and φ(fast) by MCNP code were (2.19±0.03)×10(12) cm(-2)s(-1), (1.26±0.02)×10(11) cm(-2)s(-1) and (3.33±0.02)×10(10) cm(-2)s(-1), respectively. These average values were consistent with the experimental results obtained by k(0)-INAA. The findings show a good agreement between MCNP code results and experimental results. PMID:22885391

  1. Operation Sun Beam shots Little Feller I and II, Johnie boy, and Small Boy. Project Officer's report. Project 2. 3. Neutron flux measurements

    SciTech Connect

    Rigotti, D.L.; McNeilly, J.H.; Brady, R.E.; Tarbox, J.L.

    1985-09-01

    The objectives of this project were (1) to measure free-field neutron flux and spectrum as required in support of other projects; (2) to document the neutron flux versus ground range; and (3) to determine the effect of various blast containers and shields on detector activation.

  2. The TOFOR Neutron Spectrometer For High-Performance Measurements of D Plasma Fuel Ion Properties

    SciTech Connect

    Johnson, M. Gatu; Giacomelli, L.; Hjalmarsson, A.; Weiszflog, M.; Sunden, E. Andersson; Conroy, S.; Ericsson, G.; Hellesen, C.; Ronchi, E.; Sjoestrand, H.; Kaellne, J.; Gorini, G.; Tardocch, M.

    2008-03-12

    The impact of scattered neutrons on the total flux reaching the TOFOR spectrometer at JET has been studied to allow for improvement of the data analysis. The scattered neutrons are demonstrated to contribute significantly to the flux. This will have implications for any neutron diagnostic on ITER.

  3. The Vertical Distribution of Buried Volatiles at the Moon revealed by Thermal and Epithermal Neutron Fluxes from LEND Observations

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.; Livengood, T. A.

    2015-12-01

    Determining the quantity and vertical distribution of volatile species on and below the surface of planetary bodies is vital to understand the primordial chemical inventory and subsequent evolution of planets. Volatiles may provide resources to support future human exploration. This is particularly true for the Moon, which is well observed by many methods from ground-based, lunar orbit, and in situ, and is an accessible destination or way station for human exploration. We present Geant4 models of relative fluxes of Fast, Epithermal, and Thermal neutron emission generated in a planetary regolith by galactic cosmic rays to reveal the first 1-2 meters vertical structure of embedded hydrogen or water. Varying ratios of Thermal versus Epithermal, low-energy-Epithermal versus high-energy-Epithermal, and Thermal versus Fast neutron emissions are diagnostics of the depth in which hydrogen/water layers are buried within the top 1-2 meters of the regolith. In addition, we apply model calculations to Lunar Exploration Neutron Detector (LEND) thermal and epithermal data, acquired on the Lunar Reconnaissance Orbiter (LRO), in specific regions of the Moon to retrieve the vertical distribution of buried ice from the remote sensing information. GEANT4 is a set of particle physics transport simulation codes that exploits object-oriented software methods to deliver a comprehensive and flexible toolkit that is modular and extensible, based on a free open-source development model. GEANT4 has become a standard tool to simulate applications as diverse as particle telescope and detector response, space radiation shielding and optimization, total ionizing dose in spacecraft components, and biological effects of radiation.

  4. Searching for Gravitational Waves from Unknown Galactic Neutron Stars - Evaluation of the PowerFlux Pipeline

    NASA Astrophysics Data System (ADS)

    Sauter, Orion; Riles, Keith; Dergachev, Vladimir

    2016-03-01

    Isolated rotating neutron stars with significant non-axisymmetry can emit gravitational radiation of nearly constant frequency and amplitude. Because the resulting amplitudes are expected to be extremely weak, long time integrations must be carried out to detect a signal. This task is made difficult in all-sky searches for unknown galactic stars by the motion of the Earth (daily rotation and orbital motion) which induces substantial, location-dependent modulations of detected frequency and amplitude. Several software pipelines have been developed to search for such signals in recent data from Advanced LIGO. An evaluation of the performances of these pipelines in data containing instrumental artifacts has been carried out in a mock data challenge, using software injections in Initial LIGO data, We present here the performance of the PowerFlux search program in a search band of 40-2000 Hz, including detection of ``blind'' injections. The program uses a multi-stage hierarchical algorithm, based on semi-coherent and loosely coherent power sums. Results indicate that PowerFlux is well suited to analysis of Advanced LIGO data.

  5. High flux and high quality FEL resonator mirrors

    SciTech Connect

    Anthony, F.M.; Mistretta, A.L.; Tonnessen, T.W. )

    1989-08-01

    The Free Electron Laser Cooled Mirror Technology Development Program was highly successful; this technology can be applied to cooled silicon mirror requirements for RF linac FEL's. Designs were developed for a 100 cm hyperboloid subjected to a peak absorbed flux of 1000 w/cm[sup 2] and for a 50 cm paraboloid with an absorbed peak flux of 500 w/cm[sup 2]. Although the design concepts were essentially the same detailed implementation was somewhat different for each of the mirrors. Both designs incorporated variable geometry and internal flow tailoring over the planform area so as to produce a near spherical distortion response to the input Gaussian power distribution. This enhanced correctability of the overall distortion such that the net distortion was only 0.2 A/(w/cm[sup 2]) after correction for sphere, piston and bit as compared to a design goal of 0.5 A/(w/cm[sup 2]). Structural integrity testing of small samples, that incorporated internal geometries of both types of mirrors, verified the adequacy of the designs. Fabrication of the different types of test specimens demonstrated the producibility of the configurations. Planform bonding of manifold simulations was successful; they type of bonding is required to produce a 50 cm diameter circular silicon mirror from boules that are somewhat smaller in diameter. After planform bonding of preforms they were machined, etched, assembled into pressure test specimens, and burst pressure tested. The average burst pressure of 1550 psig was somewhat stronger than early SHOP specimens of the same configuration but somewhat lower than more recently produced specimens which evidenced burst pressure strengths of 2500 psig. Demonstrated planform bond strengths are more than adequate for the mirrors of interest, better performance can be expected as the bonding precess is refined. These, and the other experimental results indicate the large factor of safety provided by the designs.

  6. High flux and high quality FEL resonator mirrors. Final report

    SciTech Connect

    Anthony, F.M.; Mistretta, A.L.; Tonnessen, T.W.

    1989-08-01

    The Free Electron Laser Cooled Mirror Technology Development Program was highly successful; this technology can be applied to cooled silicon mirror requirements for RF linac FEL`s. Designs were developed for a 100 cm hyperboloid subjected to a peak absorbed flux of 1000 w/cm{sup 2} and for a 50 cm paraboloid with an absorbed peak flux of 500 w/cm{sup 2}. Although the design concepts were essentially the same detailed implementation was somewhat different for each of the mirrors. Both designs incorporated variable geometry and internal flow tailoring over the planform area so as to produce a near spherical distortion response to the input Gaussian power distribution. This enhanced correctability of the overall distortion such that the net distortion was only 0.2 A/(w/cm{sup 2}) after correction for sphere, piston and bit as compared to a design goal of 0.5 A/(w/cm{sup 2}). Structural integrity testing of small samples, that incorporated internal geometries of both types of mirrors, verified the adequacy of the designs. Fabrication of the different types of test specimens demonstrated the producibility of the configurations. Planform bonding of manifold simulations was successful; they type of bonding is required to produce a 50 cm diameter circular silicon mirror from boules that are somewhat smaller in diameter. After planform bonding of preforms they were machined, etched, assembled into pressure test specimens, and burst pressure tested. The average burst pressure of 1550 psig was somewhat stronger than early SHOP specimens of the same configuration but somewhat lower than more recently produced specimens which evidenced burst pressure strengths of 2500 psig. Demonstrated planform bond strengths are more than adequate for the mirrors of interest, better performance can be expected as the bonding precess is refined. These, and the other experimental results indicate the large factor of safety provided by the designs.

  7. Advanced Multiphysics Thermal-Hydraulics Models for the High Flux Isotope Reactor

    SciTech Connect

    Jain, Prashant K; Freels, James D

    2015-01-01

    Engineering design studies to determine the feasibility of converting the High Flux Isotope Reactor (HFIR) from using highly enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL). This work is part of an effort sponsored by the US Department of Energy (DOE) Reactor Conversion Program. HFIR is a very high flux pressurized light-water-cooled and moderated flux-trap type research reactor. HFIR s current missions are to support neutron scattering experiments, isotope production, and materials irradiation, including neutron activation analysis. Advanced three-dimensional multiphysics models of HFIR fuel were developed in COMSOL software for safety basis (worst case) operating conditions. Several types of physics including multilayer heat conduction, conjugate heat transfer, turbulent flows (RANS model) and structural mechanics were combined and solved for HFIR s inner and outer fuel elements. Alternate design features of the new LEU fuel were evaluated using these multiphysics models. This work led to a new, preliminary reference LEU design that combines a permanent absorber in the lower unfueled region of all of the fuel plates, a burnable absorber in the inner element side plates, and a relocated and reshaped (but still radially contoured) fuel zone. Preliminary results of estimated thermal safety margins are presented. Fuel design studies and model enhancement continue.

  8. High-performance deuterium-lithium neutron source for fusion materials and technology testing

    SciTech Connect

    Lawrence, G.P.; Bhatia, T.S.; Blind, B.; Guy, F.W.; Krakowski, R.A.; Neuschaefer, G.H.; Schnurr, N.M.; Schriber, S.O.; Varsamis, G.L.; Wangler, T.P.

    1989-01-01

    Advances in high-current linear-accelerator technology since the design of the Fusion Materials Irradiation Test (FMIT) Facility have increased the attractiveness of a deuterium-lithium (D-Li) neutron source for fusion materials and technology testing. This paper discusses a new approach to such a source aimed at meeting the near-term requirements of a high-flux high-energy International Fusion Materials Irradiation Facility (IFMIF). The concept employs multiple accelerator modules providing deuteron beams to two liquid-lithium jet targets oriented at right angles. This beam/target geometry provides much larger test volumes than can be attained with a single beam and target and produces significant regions of low neutron-flux gradient. A preliminary beam-dynamics design has been obtained for a 250-mA reference accelerator module. Neutron-flux levels and irradiation volumes were calculated for a neutron source incorporating two such modules, and interaction of the beam with the lithium jet was studied using a thermal-hydraulic computer simulation. Cost estimates are provided for a range of beam currents and a possible facility staging sequence is suggested. 12 refs., 7 figs., 3 tabs.

  9. Significantly high wave trains in cosmic rays and solar radio flux

    NASA Astrophysics Data System (ADS)

    Mishra, Rajesh Kumar; Agarwal, Rekha

    2016-07-01

    Magnetic field of the Sun disturbs the propagation of cosmic rays during their propagation through the Heliosphere, and introduces variations on time scales that range from hours to millennia. Changes in the heliosphere arising from fluctuations in the Sun's magnetic field mean that galactic cosmic rays are less able to reach the Earth when the Sun is more active so the cosmic ray flux is inversely related to solar activity. In the present work studies has been carried on the occurrence of a large number high amplitude wave train events in cosmic ray intensity and to identify a possible dependence on 10.7-cm solar radio flux (solar activity) using the hourly cosmic ray neutron monitor data for two different ground based neutron monitors. The phase for both high amplitude events as well as for all days is found to significantly deviate towards an earlier hour as compared to the corotational/azimuthal direction. The amplitude of first harmonic and 10.7-cm solar radio flux significantly deviates and reaches to its peak and phase remains in the corotational direction during the years close to solar activity maximum for these high amplitude events. The occurrence of high amplitude wave train events is dominant during solar activity minimum as well as maximum years. The amplitude as well as phase of the first harmonic of cosmic ray intensity during high amplitude events shows significant correlation with solar activity. However, the frequency of occurrence of high amplitude events shows a very nominal dependence on solar activity. Keywords: high amplitude wave trains, cosmic ray, solar activity, 10.7-cm solar radio flux, magnetic field.

  10. High efficiency proportional neutron detector with solid liner internal structures

    DOEpatents

    Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.

    2014-08-05

    A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.