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Sample records for fluence fast neutrons

  1. The fluence research of filter material for fast neutron fluence measurement

    International Nuclear Information System (INIS)

    Tang Xiding

    2010-01-01

    When the fast neutron fluence is measured by radioactivation techniques in the nuclear reactor the fast neutron is also filtered a little by the thermal neutron filter material, and if the filter material thickness increase the filtered fast neutron increases therewith. For fast neutron fluenc measurement, there are only cadmium, boron and gadolinium three elements filtering fluence can be calculated ordinarily. In order to calculate the filtered fast neutron fluence of the all elements in the filter material, the many total cross sections of nuclides had checked out from nuclear cross section data library, converted them into the same energy group structure, then element's total cross section, compound's total cross section and multilayer filters' total cross section had calculated from these total cross sections with same energy group structure, a new cross section data library can be obtained lastly through merging these cross sections into the old cross section data library used for neutron fluence measurement. The calculation analysis indicates that the results of the unit 2 surveillance capsule U of DAYA Bay NPP and the unit 1 surveillance capsule A of the Second Nuclear Power Plant of Qinshan by considering the all elements subtracting iron are smaller about 1.5% and 2.6% respectively than the ones only to consider cadmium, boron. The old measured results accord with the new values under the measurement uncertainty, are reliable. The new results are more accuracy. (authors)

  2. Determination of fast neutron fluence at WWER-1000 pressure vessel

    International Nuclear Information System (INIS)

    Valenta, V. et al.

    1989-01-01

    The influence function method is an effective tool making it possible, by means of tabulated values to rapidly perform three-dimensional calculations of fast neutron fluences for various reactor core loadings and for various nuclear power plant units. The procedure for determining the spatial dependence of the fast neutron fluences in a WWER-1000 pressure vessel is described. For this, the reactor core is divided into sufficiently fine volume elements within which the neutron source can be regarded as coordinate-independent. The influence functions point to a substantial role of sources lying at the reactor core periphery. In WWER-1000 reactors, only 1 or 2 rows of peripheral assemblies are important. The influence function method makes possible a rapid and easy determination of preconditions for the assessment of the residual lifetime of the pressure vessel based on the actual reactor core loadings. (Z.M.). 7 figs., 8 refs

  3. Measured Thermal and Fast Neutron Fluence Rates for ATF-1 Holders During ATR Cycle 157D

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Larry Don [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, David Torbet [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 157D which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains measurements of the fluence rates corresponding to the particular elevations relative to the 80-ft. core elevation. The data in this report consist of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, and (3) plots of both the thermal and fast neutron fluence rates. The fluence rates reported are for the average power levels given in the table of power history and distribution.

  4. A hybrid source-driven method to compute fast neutron fluence in reactor pressure vessel - 017

    International Nuclear Information System (INIS)

    Ren-Tai, Chiang

    2010-01-01

    A hybrid source-driven method is developed to compute fast neutron fluence with neutron energy greater than 1 MeV in nuclear reactor pressure vessel (RPV). The method determines neutron flux by solving a steady-state neutron transport equation with hybrid neutron sources composed of peripheral fixed fission neutron sources and interior chain-reacted fission neutron sources. The relative rod-by-rod power distribution of the peripheral assemblies in a nuclear reactor obtained from reactor core depletion calculations and subsequent rod-by-rod power reconstruction is employed as the relative rod-by-rod fixed fission neutron source distribution. All fissionable nuclides other than U-238 (such as U-234, U-235, U-236, Pu-239 etc) are replaced with U-238 to avoid counting the fission contribution twice and to preserve fast neutron attenuation for heavy nuclides in the peripheral assemblies. An example is provided to show the feasibility of the method. Since the interior fuels only have a marginal impact on RPV fluence results due to rapid attenuation of interior fast fission neutrons, a generic set or one of several generic sets of interior fuels can be used as the driver and only the neutron sources in the peripheral assemblies will be changed in subsequent hybrid source-driven fluence calculations. Consequently, this hybrid source-driven method can simplify and reduce cost for fast neutron fluence computations. This newly developed hybrid source-driven method should be a useful and simplified tool for computing fast neutron fluence at selected locations of interest in RPV of contemporary nuclear power reactors. (authors)

  5. The determination of fast neutron fluence in radiation stability tests of steel samples

    International Nuclear Information System (INIS)

    Hogel, J.; Vespalec, R.

    1979-01-01

    The activation method is described of determining fast neutron fluence. Samples of steel designed for WWER type reactor pressure vessels were irradiated in the CHOUCA-rigs in the core of the WWR-S reactor. The neutron spectrum was measured by the multiple activation foil method and the effective cross sections of fluence monitors were calculated. The fluences obtained from the reactions 54 Fe(n,p) 54 Mn and 63 Cu(n,α) 60 Co are presented and the method is discussed. (author)

  6. Measured thermal and fast neutron fluence rates for ATF-1 holders during ATR cycle 160A

    International Nuclear Information System (INIS)

    Walker, B. J.; Miller, D. T.

    2017-01-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 160A which were measured by the Radiation Measurements Laboratory (RML).

  7. Measured thermal and fast neutron fluence rates for ATF-1 holders during ATR cycle 160A

    Energy Technology Data Exchange (ETDEWEB)

    Walker, B. J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, D. T. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-06

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 160A which were measured by the Radiation Measurements Laboratory (RML).

  8. International intercomparison of fluence of fast neutrons using 115In(n,γ) activation

    International Nuclear Information System (INIS)

    Lesiecki, H.; Cosack, M.

    1985-07-01

    The Physikalisch-Technische Bundesanstalt (PTB) has participated in an international intercomparison of fluence measurements of fast neutrons. This was organized under the auspices of the ''Comite Consultatif pour les Etalons de Mesure des Rayonnements Ionisants (CCEMRI)'', Sect. 3 (Mesures Neutronique). The National Physical Laboratory (NPL), Teddington, UK volunteered to assume responsibility for the experimental realization and final evaluation. This report deals with the measurements performed at the PTB for the neutron fluence intercomparison at neutron energies of Esub(n) = 144 keV and 570 keV which was based on the 115 In(n,γ) 116 Insup(m) reaction. The count rate of a 4πβ-counter which had to be used to determine the activation of the In sample was to be compared with the neutron fluence by which the sample was irradiated. A description of the neutron production, the fluence determination, the 4πβ-counting, and the evaluation of the results will be given. (orig.) [de

  9. Measured thermal and fast neutron fluence rates ATR Cycle 101-B, October 11, 1993--November 27, 1993

    International Nuclear Information System (INIS)

    Murray, R.K.; Rogers, J.W.

    1994-01-01

    This report contains the thermal (2200 m/s) and fast (E>lMeV) neutron fluence rate data for ATR Cycle 101-B which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains fluence rate values corresponding to the particular elevations (relative to the 80 ft. core elevation) where the measurements were taken. The data in this report consists of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, (3) plots of both the thermal and fast neutron fluence rates, and (4) a magnetic record (3.5 inch diskette) containing a listing of only the fast neutron fluence rates, their assigned elevations proper header identification of all monitor positions contained herein

  10. Electrical and optical analyses of low fluence fast neutron damage to JFETs

    International Nuclear Information System (INIS)

    Hoffmann, A.; Charles, J.P.; Kerns, S.E.; Kerns, D.V. Jr.; Bardonnie, M. de la; Mialhe, P.

    1999-01-01

    The effects of fast neutron irradiation (30 MeV) on silicon n-channel JFETs are studied. Electrical parameters of the gate-channel junction are analysed at 3 fluences: 4,06*10 10 , 8,12*10 10 and 1,22*10 11 n/cm 2 for a flux of 2,82*10 6 n/s*cm 2 and using a custom software. Electrical parameter changes are attributed to bulk semi-conductor defects. Irradiation effects on passivation overlayers are evacuate using analysis of gate-channel junction electroluminescence. This study shows that even for low neutron fluences (10 11 n/cm 2 ), n-channel JFETs, characterized in direct conducting mode and submitted to neutron radiation, present a decrease in the reverse saturation current associated with recombination. (A.C.)

  11. Fast neutron fluence calculations as support for a BWR pressure vessel and internals surveillance program

    International Nuclear Information System (INIS)

    Lucatero, Marco A.; Palacios-Hernandez, Javier C.; Ortiz-Villafuerte, Javier; Xolocostli-Munguia, J. Vicente; Gomez-Torres, Armando M.

    2010-01-01

    Materials surveillance programs are required to detect and prevent degradation of safety-related structures and components of a nuclear power reactor. In this work, following the directions in the Regulatory Guide 1.190, a calculational methodology is implemented as additional support for a reactor pressure vessel and internals surveillance program for a BWR. The choice of the neutronic methods employed was based on the premise of being able of performing all the expected future survey calculations in relatively short times, but without compromising accuracy. First, a geometrical model of a typical BWR was developed, from the core to the primary containment, including jet pumps and all other structures. The methodology uses the Synthesis Method to compute the three-dimensional neutron flux distribution. In the methodology, the code CORE-MASTER-PRESTO is used as the three-dimensional core simulator; SCALE is used to generate the fine-group flux spectra of the components of the model and also used to generate a 47 energy-groups job cross section library, collapsed from the 199-fine-group master library VITAMIN-B6; ORIGEN2 was used to compute the isotopic densities of uranium and plutonium; and, finally, DORT was used to calculate the two-dimensional and one-dimensional neutron flux distributions required to compute the synthesized three-dimensional neutron flux. Then, the calculation of fast neutron fluence was performed using the effective full power time periods through six operational fuel cycles of two BWR Units and until the 13th cycle for Unit 1. The results showed a maximum relative difference between the calculated-by-synthesis fast neutron fluxes and fluences and those measured by Fe, Cu and Ni dosimeters less than 7%. The dosimeters were originally located adjacent to the pressure vessel wall, as part of the surveillance program. Results from the computations of peak fast fluence on pressure vessel wall and specific weld locations on the core shroud are

  12. Estimation of fast neutron fluence in steel specimens type Laguna Verde in TRIGA Mark III reactor

    International Nuclear Information System (INIS)

    Galicia A, J.; Francois L, J. L.; Aguilar H, F.

    2015-09-01

    The main purpose of this work is to obtain the fluence of fast neutrons recorded within four specimens of carbon steel, similar to the material having the vessels of the BWR reactors of the nuclear power plant of Laguna Verde when subjected to neutron flux in a experimental facility of the TRIGA Mark III reactor, calculating an irradiation time to age the material so accelerated. For the calculation of the neutron flux in the specimens was used the Monte Carlo code MCNP5. In an initial stage, three sheets of natural molybdenum and molybdenum trioxide (MoO 3 ) were incorporated into a model developed of the TRIGA reactor operating at 1 M Wth, to calculate the resulting activity by setting a certain time of irradiation. The results obtained were compared with experimentally measured activities in these same materials to validate the calculated neutron flux in the model used. Subsequently, the fast neutron flux received by the steel specimens to incorporate them in the experimental facility E-16 of the reactor core model operating at nominal maximum power in steady-state was calculated, already from these calculations the irradiation time required was obtained for values of the neutron flux in the range of 10 18 n/cm 2 , which is estimated for the case of Laguna Verde after 32 years of effective operation at maximum power. (Author)

  13. A new Recoil Proton Telescope for energy and fluence measurement of fast neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Lebreton, Lena; Bachaalany, Mario [IRSN / LMDN (Institut de Radioprotection et de Surete nucleaire / Laboratoire de Metrologie et de dosimetrie des neutrons), Cadarache Bat.159, 13115 Saint Paul-lez-Durance, (France); Husson, Daniel; Higueret, Stephane [IPHC / RaMsEs (Institut Pluridisciplinaire Hubert Curien / Radioprotection et Mesures Environnementales), 23 rue du loess - BP28, 67037 Strasbourg cedex 2, (France)

    2015-07-01

    The spectrometer ATHENA (Accurate Telescope for High Energy Neutron metrology Applications), is being developed at the IRSN / LMDN (Institut de Radioprotection et de Surete nucleaire / Laboratoire de Metrologie et de dosimetrie des neutrons) and aims at characterizing energy and fluence of fast neutron fields. The detector is a Recoil Proton Telescope and measures neutron fields in the range of 5 to 20 MeV. This telescope is intended to become a primary standard for both energy and fluence measurements. The neutron detection is achieved by a polyethylene radiator for n-p conversion, three 50{sub m} thick silicon sensors that use CMOS technology for the proton tracking and a 3 mm thick silicon diode to measure the residual proton energy. This first prototype used CMOS sensors called MIMOSTAR, initially developed for heavy ion physics. The use of CMOS sensors and silicon diode increases the intrinsic efficiency of the detector by a factor of ten compared with conventional designs. The first prototype has already been done and was a successful study giving the results it offered in terms of energy and fluence measurements. For mono energetic beams going from 5 to 19 MeV, the telescope offered an energy resolution between 5 and 11% and fluence difference going from 5 to 7% compared to other home standards. A second and final prototype of the detector is being designed. It will hold upgraded CMOS sensors called FastPixN. These CMOS sensors are supposed to run 400 times faster than the older version and therefore give the telescope the ability to support neutron flux in the order of 107 to 108cm{sup 2}:s{sup 1}. The first prototypes results showed that a 50 m pixel size is enough for a precise scattering angle reconstruction. Simulations using MCNPX and GEANT4 are already in place for further improvements. A DeltaE diode will replace the third CMOS sensor and will be installed right before the silicon diode for a better recoil proton selection. The final prototype with

  14. Fast neutron fluence evaluation of the smart reactor pressure vessel by using the GEOSHIELD code

    International Nuclear Information System (INIS)

    Kim, K.Y.; Kim, K.S.; Kim, H.Y.; Lee, C.C.; Zee, S.Q.

    2007-01-01

    In Korea, the design of an advanced integral reactor system called SMART has been developed by KAERI to supply energy for seawater desalination as well as an electricity generation. A fast neutron fluence distribution at the SMART reactor pressure vessel was evaluated to confirm the integrity of the vessel by using the GEOSHIELD code. The GEOSHIELD code was developed by KAERI in order to prepare an input list including a geometry modeling of the DORT code and to process results from the DORT code output list. Results by a GEOSHIELD code processing and by a manual processing of the DORT show a good agreement. (author)

  15. Measured thermal and fast neutron fluence rates for ATF-1 holders during ATR cycle 158B/159A

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Larry Don [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, David Torbet [Idaho National Lab. (INL), Idaho Falls, ID (United States); Walker, Billy Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-11-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 158B/159A which were measured by the Radiation Measurements Laboratory (RML).

  16. Measured thermal and fast neutron fluence rates, ATR Cycle 102-A, 11/28/93 thru 1/16/94

    International Nuclear Information System (INIS)

    Murray, R.K.; Rogers, J.W.

    1994-02-01

    This report contains the thermal (2,200 m/s) and fast (E > 1MeV) neutron fluence rate data for ATR Cycle 102-A which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains fluence rate values corresponding to the particular elevations (relative to the 80 ft. core elevation) where the measurements were taken. The data in this report consists of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, (3) plots of both the thermal and fast neutron fluence rates, and (4) a magnetic record (3.5 inch diskette) containing a listing of only the fast neutron fluence rates, their assigned elevations and proper header identification of all monitor positions contained herein. The fluence rates reported are for the average power levels given in the table of power history and distribution. All ''H'' holder monitoring wires for this cycle are 54 inches long. All ''SR'' holder monitor wires for this cycle are 55 inches long. This length allows measurement of the full core region and makes the first count elevation 24.73 inches above core midplane. Due to the safety rod problems in the west lobe, ''BR'' holders were used in the W-1, 2, 3, and 4 positions. All ''BR'' holder monitor wires for this cycle are 56.25 inches long. The distance from the end of the wires to the first count position was 4.25 inches for all wires counted from this cycle

  17. Measured thermal and fast neutron fluence rates ATR Cycle 99-A, November 23, 1992--January 23, 1993

    International Nuclear Information System (INIS)

    Murray, R.K.; Rogers, J.W.

    1993-03-01

    This report contains the thermal (2200 m/s) and fast (E>me) neutron fluence rate data for ATR Cycle 99-A which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power ReactorPrograms (ATR Experiments) Radiation Measurements Work Order. This report contains fluence rate values corresponding to the particular elevations (relative to the 80 ft. core elevation) where the measurements were taken. The data in this report consists of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, (3) plots of both the thermal and fast neutron fluence rates, and (4) a magnetic record (3.5 inch diskette) containing a listing of only the fast neutron fluence rates, their assigned elevations and proper header identification of all monitor positions contained herein. The fluence rates reported are for the average power levels given in the table of power history and distribution. All ''H'' holder monitor wires for this cycle are 54 inches long. All ''SR'' holder monitor wires for this cycle are 55 inches long. This length allows measurement of the full core region and makes the first count elevation 24.73 inches above core midplane. Due to the safety rod problems in the west lobe, ''BR'' holders were used in the W-1, 2, 3, and 4 positions. All ''BR'' holder monitor wires for this cycle are 56.25 inches long. The distance from the end of the wires to the first count position was 4.25 inches for all wires counted from this cycle

  18. Test of Fibre Bragg Gratings samples under High Fast Neutrons Fluence

    Science.gov (United States)

    Cheymol, G.; Remy, L.; Gusarov, A.; Kinet, D.; Mégret, P.; Laffont, G.; Blanchet, T.; Morana, A.; Marin, E.; Girard, S.

    2018-01-01

    Optical fibre sensors (OFS) are worthy of interest for measurements in nuclear reactor thanks to their unique features, particularly compact size and remote multi-point sensing for some of them. But besides non negligible constraints associated with the high temperature environment of the experiments of interest, it is well known that the performances of OFS can be severely affected by high level of radiations. The Radiation Induced Attenuation (RIA) in the fibre is probably most known effect, which can be to some extent circumvented by using rad hard fibres to limit the dynamic loss. However, when the fast neutron fluence reaches 1018 to 1019 n/cm2, the density and index variations associated to structural changes may deteriorate drastically the performances of OFS even if they are based on rad hard fibres, by causing direct errors in the measurements of temperature and/or strain changes. The aim of the present study is to access the effect of nuclear radiations on the Fabry Perot (FP) and of Fibre Bragg Grating (FBG) sensors through the comparison of measurements made on these OFS - or part of them - before and after irradiation [1]. In the context of development of OFS for high irradiation environment and especially for Material Testing Reactors (MTRs), Sake 2 experiment consists in an irradiation campaign at high level of gamma and neutron fluxes conducted on samples of fibre optics - bare or functionalised with FBG. The irradiation was performed at two levels of fast neutron fluence: 1 and 3.1019 n/cm2 (E>1MeV), at 250°± 25°C, in the SCK•CEN BR2 reactor (Mol Belgium). An irradiation capsule was designed to allow irradiation at the specified temperature without active control. The neutron fluence was measured with activation dosimeters and the results were compared with MCPN computations. Investigation of bare samples gives information on the density changes, while for the FBGs both density and refractive index perturbation are involved. Some results for

  19. Approaches for accounting and prediction of fast neutron fluence on WWER pressure vessels and results of validation of calculational procedure

    International Nuclear Information System (INIS)

    Borodkin, P.G.; Khrennikov, N.N.; Ryabinin, Yu.A.; Adeev, V.A.

    2015-01-01

    A description is given of the universal procedure for calculation of fast neutron fluence (FNF) on WWER vessels. Approbation of the calculation procedure was carried out by comparing the calculation results for this procedure and measurements on the outer surface of the WWER-440 and WWER-1000 vessels. In addition, an estimation of the uncertainty of the settlement procedure was made in accordance with the requirements of regulatory documents. The developed procedure is applied at Kola NPP for independent fast neutron fluence estimates on the WWER-440 reactor vessels when planning core loads taking into account the introduction of new fuels. The results of the pilot operation of the procedure for calculating FNF at the Kola NPP were taken into account when improving the procedure and its application to the calculations of FNF on the WWER-1000 vessels [ru

  20. Neutron fluence measurements

    International Nuclear Information System (INIS)

    1970-01-01

    For research reactor work dealing with such subjects as radiation effects on solids and such disciplines as radiochemistry and radiobiology, the radiation dose or neutron fluence is an essential parameter in evaluating results. Unfortunately it is very difficult to determine. Even when the measurements have been accurate, it is difficult to compare results obtained in different experiments because present methods do not always reflect the dependence of spectra or of different types of radiation on the induced processes. After considering the recommendations of three IAEA Panels, on 'In-pile dosimetry' held in July 1964, on 'Neutron fluence measurements' in October 1965, and on 'In-pile dosimetry' in November 1966, the Agency established a Working Group on Reactor Radiation Measurements. This group consisted of eleven experts from ten different Member States and two staff members of the Agency. In the measurement of energy absorbed by materials from neutrons and gamma rays, there are various reports and reviews scattered throughout the literature. The group, however, considered that the time was ripe for all relevant information to be evaluated and gathered together in the form of a practical guide, with the aim of promoting consistency in the measurement and reporting of reactor radiation. The group arranged for the material to be divided into two manuals, which are expected to be useful both for experienced workers and for beginners

  1. Neutron fluence measurement in nuclear facilities

    International Nuclear Information System (INIS)

    Camacho L, M.E.

    1997-01-01

    The objective of present work is to determine the fluence of neutrons in nuclear facilities using two neutron detectors designed and built at Instituto Nacional de Investigaciones Nucleares (ININ), Mexico. The two neutron detectors are of the passive type, based on solid state nuclear tracks detectors (SSNTD). One of the two neutron detectors was used to determine the fluence distribution of the ports at the nuclear research reactor TRIGA Mark III, which belongs to ININ. In these facilities is important to know the neutron fluence distribution characteristic to carried out diverse kind of research activities. The second neutron detector was employed in order to carry out environmental neutron surveillance. The detector has the property to separate the thermal, intermediate and fast components of the neutron fluence. This detector was used to measure the neutron fluence at hundred points around the primary container of the first Mexican Nuclear Power plant 'Laguna Verde'. This last detector was also used to determine the neutron fluence in some points of interest, around and inside a low scattering neutron room at the 'Centro de Metrologia de Radiaciones Ionizantes' of the ININ, to know the background neutron field produced by the neutron sources used there. The design of the two neutron detector and the results obtained for each of the surveying facilities, are described in this work. (Author)

  2. Measured thermal and fast neutron fluence rates, ATR Cycle 100-BC, April 23, 1993--May 13, 1993

    International Nuclear Information System (INIS)

    Smith, L.D.; Murray, R.K.; Rogers, J.W.

    1993-07-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for ATR Cycle 100-BC which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains fluence rate values corresponding to the particular elevations (relative to the 80 ft. core elevation) where the measurements were taken. The data in this report consists of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, (3) plots of both the thermal and fast neutron fluence rates, and (4) a magnetic record (3.5 inch diskette) containing a listing of only the fast neutron fluence rates, their assigned elevations and proper header identification of all monitor positions contained herein. The fluence rates reported are for the average power levels given in the table of power history and distribution. All open-quotes Hclose quotes holder monitor wires for this cycle are 54 inches long. All open-quotes SRclose quotes holder monitor wires for this cycle are 55 inches long. This length allows measurement of the full core region and makes the first count elevation 24.73 inches above core midplane. Due to the safety rod problems in the west lobe, open-quotes BRclose quotes holders were used in the W-1, 2, 3, and 4 positions. All open-quotes BRclose quotes holder monitor wires for this cycle are 56.25 inches long. The distance from the end of the wires to the first count position was 4.25 inches for all wires counted from this cycle. The results from the measurements in the W-1, 2, 3, 4 monitor positions indicate that the safety rod followers were rotated to a different azimuthal orientation relative to the normal orientation. The results indicate that the rotation was counterclockwise from their normal orientation. This is the same condition observed starting with Cycle 99-B

  3. Analysis of influence of fast neutron fluence irradiated to Beryllium element of The RSG-GAS reactor

    International Nuclear Information System (INIS)

    Sri Kuntjoro

    2010-01-01

    Analysis of influence fast neutron fluence irradiated to the RSG-GAS beryllium reflector have been done. Methods of analysis was carried out by measuring fluxes neutron in beryllium element and block position that function as reflector.The calculation done for determination it is there any influence of neutron as long as beryllium in the core. Besides that, visualization done to make sure it there is any deformation at beryllium as effect of irradiation. Fluxes and fluences of beryllium element measurement result in 200 kW reactor power are 2.30E+07 n/cm 2 .sec and 4.19E+17 n/cm 2 in position E-2, 3.70E+07 n/cm 2 s and 6.74E+17 n/cm 2 in position J-8, 2.19E+12 n/cm 2 s and 3.99E+22 n/cm 2 in position. Measurement results in the position B-3 are 2.12E+12 n/cm 2 s and 3.86E+22 n/cm 2 in position G-10 respectively. Other result are fluxes and fluence in beryllium block, those are 5,02E+07 n/cm 2 s and 9,15E+17 n/cm 2 in position (5-6), and 2,32E+07 n/cm 2 s and 4,23E+17 n/cm 2 in position (C-D). Deformation (L/L) results for beryllium element are 1,12E-08 in position E-2, 1,84E-08 in position J-8, 1,60E-03 in position B-3, and 1,55E-03 in position G-10. In beryllium block deformation results are 2,52E-08 in position (5-6) and 1,13E-08 in position (C-D). Those results are shown unseen deformation in beryllium element and beryllium block and demonstrably by visual observation in reactor hot cell. (author)

  4. An application of low leakage loading pattern to reduce fast neutrons. Fluence on WWER-440 reactor pressure vessel in Kozloduy NPP

    International Nuclear Information System (INIS)

    Haralampieva, Tz.; Antonov, A.; Monev, M.

    2001-01-01

    The neutron exposure of a reactor pressure vessel (RPV) is one of the key factors that have to be quantified and assess reliably to provide plant life assurance and for an extension to operational life. This paper summarizes the principal methods that are used in core design optimisation for WWER-440 reactors in NPP-Kozloduy in order to reduce flux of fast neutrons at the RPV. Results of fast neutron fluence changes during the all last cycles of units 1-4 with WWER-440 reactors are considered (Authors)

  5. Accuracy of helium accumulation fluence monitor for fast reactor dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Chikara; Aoyama, Takafumi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-03-01

    A helium (He) accumulation fluence monitor (HAFM) has been developed for fast reactor dosimetry. In order to evaluate the measurement accuracy of neutron fluence by the HAFM method, the HAFMs of enriched boron (B) and beryllium (Be) were irradiated in the Fast Neutron Source Reactor `YAYOI`. The number of He atoms produced in the HAFMs were measured and compared with the calculated values. As a result of this study, it was confirmed that the neutron fluence could be measured within 5 % by the HAFM method, and that met the required accuracy for fast reactor dosimetry. (author)

  6. Fast fluence measurement for JOYO irradiation field using niobium dosimeter

    International Nuclear Information System (INIS)

    Ito, Chikara

    2004-03-01

    Neutron fluence and spectrum are key parameters in various irradiation tests and material surveillance tests so they need to be evaluated accurately. The reactor dosimetry test has been conducted by the multiple foil activation method, and a niobium dosimeter has been developed for measurement of fast neutron fluence in the experimental fast reactor JOYO. The inelastic scattering reaction of 93 Nb has a low threshold energy, about 30 keV, and the energy distribution of reaction cross section is similar to the displacement cross section for iron. Therefore, a niobium dosimeter is suitable for evaluation of the fast neutron fluence and the displacement per atom for iron. Moreover, a niobium dosimeter is suited to measure neutron fluence in long-term irradiation test because 93 Nb, which is produced by the reaction, has a long half-life (16.4 years). This study established a high precision measurement technique using the niobium reaction rate. The effect of self-absorption was decreased by the solution and evaporation to dryness of niobium dosimeter. The dosimeter weight was precisely measured using the inductively coupled plasma mass spectrometer. This technique was applied to JOYO dosimetry. The fast neutron fluences (E > 0.1 MeV) found by measuring the reaction rate in the niobium dosimeter were compared with the values evaluated using the multiple foil activation method. The ratio of measured fast neutron fluences by means of niobium dosimeter and multiple foil activation method range from 0.97 to 1.03 and agree within the experimental uncertainty. The measurement errors of fast neutron fluence by niobium dosimeter range from 4.5% (fuel region) to 10.1% (in-vessel storage rack). As a result of this study, the high precision measurement of fast neutron fluence by niobium dosimeters was confirmed. The accuracy of fast reactor dosimetry will be improved by application of niobium dosimeters to the irradiation tests in the JOYO MK-III core. (author)

  7. Study of the response of a piezoceramic motor irradiated in a fast reactor up to a neutron fluence of 2.77E+17 n/cm2

    International Nuclear Information System (INIS)

    Pillon, Mario; Monti, Chiara; Mugnaini, Giampiero; Neri, Carlo; Rossi, Paolo; Carta, Mario; Fiorani, Orlando; Santagata, Alfonso

    2015-01-01

    Highlights: • Piezoceramic motors are compliant with magnetic field, temperature and vacuum. • We studied the response of a piezoceramic motor during the irradiation with neutrons. • The response was studied using 1 MeV neutrons up to a neutron fluence of 2.77E+17 n/cm 2 . • Neutron irradiation produces a shift of the optimal resonance frequency and a decrease of the motor speed. • The performance changes do not affect the proper operation of the motor. - Abstract: A piezoceramic motor has been identified as the potential apparatus for carrying out the rotation of the scanning head of a laser radar system used for viewing the first wall of the ITER vessel. This diagnostic is simply referred to as IVVS (In Vessel Viewing System). The choice fell on a piezoceramic motor due to the presence of strong magnetic fields (up 8 T) and of the high vacuum and temperature conditions. To be compliant with all the ITER environmental conditions it was necessary to qualify the piezo-motor under gamma and neutron irradiation. In this paper are described the procedures and tests that have been performed to verify the compatibility of the operation of the motor adopted in the presence of a fast neutron fluence which was gradually increased over time in order to reach a total value of 2.77 × 10 17 n/cm 2 . Such neutron fluence was obtained by irradiating the motor in a position close to the core of the fast nuclear reactor TAPIRO, in operation at the ENEA Casaccia Research Centre, Italy. The neutron spectrum in this position has been identified as representative of that found in the rest position of the IVVS head during ITER operation. The cumulative neutron fluence reached corresponds to that it is expected to be reached during the entire life of ITER for the IVVS in the rest position without any shield. This work describes the experimental results of this test; the methodology adopted to determine the total neutron fluence achieved and the methodology adopted for the

  8. Specific heat of Nb3Sn and V2Zr compounds irradiated with high fluences fast neutrons

    International Nuclear Information System (INIS)

    Kar'kin, A.E.; Mirmel'shtejn, A.V.; Arkhipov, V.E.; Goshchitskij, B.N.

    1987-01-01

    Specific heat of Nb 3 Sn (structure A15) and V 2 Zr (C15) specimens irradiated with high fluences of bast neutrons has been measured. It is shown that in these compounds the temperature reduction of superconducting transition T c under neutron irradiation is accompanied with high decrease of N(E F ). Phonon spectrum of the irradiated V 2 Zr (amorphous phase) on the whole is harder, than at an initial state, for irradiated Nb 3 Sn state (disordered crystalline structure) phonon spectrum is differ weakly from initial one. General regularities of parameter change of electron and phonon subsystems for A15 compounds investigated here and earlier (V 3 Si, Mo 3 Si, Mo 3 Ge) have been analysed

  9. Neutron fluence spectrometry using disk activation

    International Nuclear Information System (INIS)

    Loevestam, Goeran; Hult, Mikael; Fessler, Andreas; Gasparro, Joel; Kockerols, Pierre; Okkinga, Klaas; Tagziria, Hamid; Vanhavere, Filip; Wieslander, J.S. Elisabeth

    2009-01-01

    A simple and robust detector for spectrometry of environmental neutrons has been developed. The technique is based on neutron activation of a series of different metal disks followed by low-level gamma-ray spectrometry of the activated disks and subsequent neutron spectrum unfolding. The technique is similar to foil activation but here the applied neutron fluence rates are much lower than usually in the case of foil activation. The detector has been tested in quasi mono-energetic neutron fields with fluence rates in the order of 1000-10000 cm -2 s -1 , where the obtained spectra showed good agreement with spectra measured using a Bonner sphere spectrometer. The detector has also been tested using an AmBe source and at a neutron fluence rate of about 40 cm -2 s -1 , again, a good agreement with the assumed spectrum was achieved

  10. Neutron fluence spectrometry using disk activation

    Energy Technology Data Exchange (ETDEWEB)

    Loevestam, Goeran [EC-JRC-Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel (Belgium)], E-mail: goeran.loevestam@ec.europa.eu; Hult, Mikael; Fessler, Andreas; Gasparro, Joel; Kockerols, Pierre; Okkinga, Klaas [EC-JRC-Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel (Belgium); Tagziria, Hamid [EC-JRC-Institute for the Protection and the Security of the Citizen (IPSC), Via E. Fermi 1, I-21020 Ispra (Vatican City State, Holy See,) (Italy); Vanhavere, Filip [SCK-CEN, Boeretang, 2400 Mol (Belgium); Wieslander, J.S. Elisabeth [EC-JRC-Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel (Belgium); Department of Physics, P.O. Box 35 (YFL), FIN-40014, University of Jyvaeskylae (Finland)

    2009-01-15

    A simple and robust detector for spectrometry of environmental neutrons has been developed. The technique is based on neutron activation of a series of different metal disks followed by low-level gamma-ray spectrometry of the activated disks and subsequent neutron spectrum unfolding. The technique is similar to foil activation but here the applied neutron fluence rates are much lower than usually in the case of foil activation. The detector has been tested in quasi mono-energetic neutron fields with fluence rates in the order of 1000-10000 cm{sup -2} s{sup -1}, where the obtained spectra showed good agreement with spectra measured using a Bonner sphere spectrometer. The detector has also been tested using an AmBe source and at a neutron fluence rate of about 40 cm{sup -2} s{sup -1}, again, a good agreement with the assumed spectrum was achieved.

  11. Fuels and materials research under the high neutron fluence using a fast reactor Joyo and post-irradiation examination facilities

    International Nuclear Information System (INIS)

    Soga, Tomonori; Ito, Chikara; Aoyama, Takafumi; Suzuki, Soju

    2009-01-01

    The experimental fast reactor Joyo at Oarai Research and Development Center (ORDC) of Japan Atomic Energy Agency (JAEA) is Japan's sodium-cooled fast reactor (FR). In 2003, this reactor's upgrade to the 140MWt MK-III core was completed to increase the irradiation testing capability. The MK-III core provides the fast neutron flux of 4.0x10 15 n/cm 2 s as an irradiation test bed for improving the fuels and material of FR in Japan. Three post-irradiation examination (PIE) facilities named FMF, MMF and AGF related to Joyo are in ORDC. Irradiated subassemblies and core components are carried into the FMF (Fuel Monitoring Facility) and conducted nondestructive examinations. Each subassembly is disassembled to conduct some destructive examinations and to prepare the fuel and material samples for further detailed examinations. Fuel samples are sent to the AGF (Alpha-Gamma Facility), and material samples are sent to the MMF (Materials Monitoring Facility). These overall and elaborate data provided by PIE contribute to investigate the irradiation effect and behavior of fuels and materials. This facility complex is indispensable to promote the R and D of FR in Japan. And, the function and technology of irradiation test and PIE enable to contribute to the R and D of innovative fission or fusion reactor material which will be required to use under the high neutron exposure. (author)

  12. Neutron fluence measurement in nuclear facilities.; Medicion de flujos de neutrones en instalaciones nucleares.

    Energy Technology Data Exchange (ETDEWEB)

    Camacho L, M E

    1997-12-01

    The objective of present work is to determine the fluence of neutrons in nuclear facilities using two neutron detectors designed and built at Instituto Nacional de Investigaciones Nucleares (ININ), Mexico. The two neutron detectors are of the passive type, based on solid state nuclear tracks detectors (SSNTD). One of the two neutron detectors was used to determine the fluence distribution of the ports at the nuclear research reactor TRIGA Mark III, which belongs to ININ. In these facilities is important to know the neutron fluence distribution characteristic to carried out diverse kind of research activities. The second neutron detector was employed in order to carry out environmental neutron surveillance. The detector has the property to separate the thermal, intermediate and fast components of the neutron fluence. This detector was used to measure the neutron fluence at hundred points around the primary container of the first Mexican Nuclear Power plant `Laguna Verde`. This last detector was also used to determine the neutron fluence in some points of interest, around and inside a low scattering neutron room at the `Centro de Metrologia de Radiaciones Ionizantes` of the ININ, to know the background neutron field produced by the neutron sources used there. The design of the two neutron detector and the results obtained for each of the surveying facilities, are described in this work. (Author).

  13. Neutron dosimetry intercomparison run for verification of the neutron fluence

    International Nuclear Information System (INIS)

    Penev, I.; Kinova, L.

    2001-01-01

    For the neutron fluence verification the intercomparison runs Balakovo and KORPUS have been carried out. The participation in the international intercomparison runs shows that in order to more precisely verify the calculated values of the neutron fluence more intercomparison exercises are necessary. Due to such exercises the results improved after calibration of Nb performed and are in a very good agreement with RIIAR results in spite of the different approaches in the determination of its activity

  14. Estimation of fast neutron fluence in steel specimens type Laguna Verde in TRIGA Mark III reactor; Estimacion de la fluencia de neutrones rapidos en probetas de acero tipo Laguna Verde en el reactor Triga Mark III

    Energy Technology Data Exchange (ETDEWEB)

    Galicia A, J.; Francois L, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Aguilar H, F., E-mail: blink19871@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    The main purpose of this work is to obtain the fluence of fast neutrons recorded within four specimens of carbon steel, similar to the material having the vessels of the BWR reactors of the nuclear power plant of Laguna Verde when subjected to neutron flux in a experimental facility of the TRIGA Mark III reactor, calculating an irradiation time to age the material so accelerated. For the calculation of the neutron flux in the specimens was used the Monte Carlo code MCNP5. In an initial stage, three sheets of natural molybdenum and molybdenum trioxide (MoO{sub 3}) were incorporated into a model developed of the TRIGA reactor operating at 1 M Wth, to calculate the resulting activity by setting a certain time of irradiation. The results obtained were compared with experimentally measured activities in these same materials to validate the calculated neutron flux in the model used. Subsequently, the fast neutron flux received by the steel specimens to incorporate them in the experimental facility E-16 of the reactor core model operating at nominal maximum power in steady-state was calculated, already from these calculations the irradiation time required was obtained for values of the neutron flux in the range of 10{sup 18} n/cm{sup 2}, which is estimated for the case of Laguna Verde after 32 years of effective operation at maximum power. (Author)

  15. Phototransistor response under a neutron fluence

    International Nuclear Information System (INIS)

    Santos, Luiz A.P.; Barros, Fabio R.; Ursulino, Luciano C.; Silva Junior, Eronides F.; Antonio Filho, Joao

    2009-01-01

    The purpose of this communication is to show some effects on a bipolar phototransistor after it has been under a neutron fluence. Unlike a transistor, a phototransistor is designed so that the collector has a large area and consequently it has a higher radiation detection probability. Then, it is possible to have a certain number of interactions so that any changes in the internal structure of the phototransistor can be observed after a neutron irradiation. If a phototransistor is under a certain spectra of neutron fluence the interaction depends on the cross section of the either silicon chip or its encapsulation, and recoil protons could be the charged particle responsible for changes in the semiconductor structure. Furthermore, neutron irradiation could give to the device a state of vanishing in its electrical characteristic which can be performed tracing the current versus voltage curve (I x V). The experimental arrangement basically consists of a photonic device, a neutron-gamma radiation source and a Flip-Flop electrometer second generation (EFF-2G). One of the main parameters of evaluation was the phototransistor dark current. In fact, the first results demonstrate that when the phototransistor is neutron irradiated there is a significant variation in its I x V characteristic curve. (author)

  16. Correlating Fast Fluence to dpa in Atypical Locations

    Directory of Open Access Journals (Sweden)

    Drury Thomas H.

    2016-01-01

    Full Text Available Damage to a nuclear reactor's materials by high-energy neutrons causes changes in the ductility and fracture toughness of the materials. The reactor vessel and its associated piping's ability to withstand stress without brittle fracture are paramount to safety. Theoretically, the material damage is directly related to the displacements per atom (dpa via the residual defects from induced displacements. However in practice, the material damage is based on a correlation to the high-energy (E > 1.0 MeV neutron fluence. While the correlated approach is applicable when the material in question has experienced the same neutron spectrum as test specimens which were the basis of the correlation, this approach is not generically acceptable. Using Monte Carlo and discrete ordinates transport codes, the energy dependent neutron flux is determined throughout the reactor structures and the reactor vessel. Results from the models provide the dpa response in addition to the high-energy neutron flux. Ratios of dpa to fast fluence are calculated throughout the models. The comparisons show a constant ratio in the areas of historical concern and thus the validity of the correlated approach to these areas. In regions above and below the fuel however, the flux spectrum has changed significantly. The correlated relationship of material damage to fluence is not valid in these regions without adjustment. An adjustment mechanism is proposed.

  17. Correlating Fast Fluence to dpa in Atypical Locations

    Science.gov (United States)

    Drury, Thomas H.

    2016-02-01

    Damage to a nuclear reactor's materials by high-energy neutrons causes changes in the ductility and fracture toughness of the materials. The reactor vessel and its associated piping's ability to withstand stress without brittle fracture are paramount to safety. Theoretically, the material damage is directly related to the displacements per atom (dpa) via the residual defects from induced displacements. However in practice, the material damage is based on a correlation to the high-energy (E > 1.0 MeV) neutron fluence. While the correlated approach is applicable when the material in question has experienced the same neutron spectrum as test specimens which were the basis of the correlation, this approach is not generically acceptable. Using Monte Carlo and discrete ordinates transport codes, the energy dependent neutron flux is determined throughout the reactor structures and the reactor vessel. Results from the models provide the dpa response in addition to the high-energy neutron flux. Ratios of dpa to fast fluence are calculated throughout the models. The comparisons show a constant ratio in the areas of historical concern and thus the validity of the correlated approach to these areas. In regions above and below the fuel however, the flux spectrum has changed significantly. The correlated relationship of material damage to fluence is not valid in these regions without adjustment. An adjustment mechanism is proposed.

  18. Fast neutron dosimetry

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1993-01-01

    Research concentrated on three major areas during the last twelve months: (1) investigations of energy fluence and absorbed dose measurements using crystalline and hot pressed TLD materials exposes to ultrasoft beams of photons, (2) fast neutron kerma factor measurements for several important elements as well as NE-213 scintillation material response function determinations at the intense ''white'' source available at the WNR facility at LAMPF, and (3) kerma factor ratio determinations for carbon and oxygen to A-150 tissue equivalent plastic at the clinical fast neutron radiation facility at Harper Hospital, Detroit, MI. Progress summary reports of these efforts are given in this report

  19. Neutron Fluence Evaluation using an Am-Be Neutron Sources Assembly and P ADC Detectors

    International Nuclear Information System (INIS)

    Seddik, U.

    2008-01-01

    An assembly of four 241 Am-Be sources has been constructed at Nuclear Reactions Unit (NRU) of Nuclear Research Center (NRU) to perform analysis of different materials using thermal and fast neutrons. In the present paper, we measure the value of transmittance (T) in percentage of etched CR-39 detectors using a spectrophotometer at different neutron fluences ,to relate the transmittance of the detector with the neutron fluence values. The exposed samples to neutrons with accumulated fluence of order between 10 10 and 10 12 cm -2 were etched for 15 time intervals between 10-600 min in 6.25 N NaOH at 70 degree C. The etched samples were analyzed using Tech 8500 II spectrophotometer. A trend of the sample transmission and the etching time is observed which is different for each fluence value. A linear relation between the transmittance decay constant and the neutron fluence is observed which could be used as a calibration to determine unknown neutron fluence

  20. Study of the response of a piezoceramic motor irradiated in a fast reactor up to a neutron fluence of 2.77E+17 n/cm{sup 2}

    Energy Technology Data Exchange (ETDEWEB)

    Pillon, Mario, E-mail: mario.pillon@enea.it [Associazione EURATOM-ENEA sulla Fusione, ENEA C.R. Frascati, via E. Fermi, 45, 00044 Frascati, Rome (Italy); Monti, Chiara; Mugnaini, Giampiero; Neri, Carlo; Rossi, Paolo [Associazione EURATOM-ENEA sulla Fusione, ENEA C.R. Frascati, via E. Fermi, 45, 00044 Frascati, Rome (Italy); Carta, Mario; Fiorani, Orlando; Santagata, Alfonso [ENEA C.R. CASACCIA, via Anguillarese, 301, 00123 S. Maria di Galeria, Rome (Italy)

    2015-10-15

    Highlights: • Piezoceramic motors are compliant with magnetic field, temperature and vacuum. • We studied the response of a piezoceramic motor during the irradiation with neutrons. • The response was studied using 1 MeV neutrons up to a neutron fluence of 2.77E+17 n/cm{sup 2}. • Neutron irradiation produces a shift of the optimal resonance frequency and a decrease of the motor speed. • The performance changes do not affect the proper operation of the motor. - Abstract: A piezoceramic motor has been identified as the potential apparatus for carrying out the rotation of the scanning head of a laser radar system used for viewing the first wall of the ITER vessel. This diagnostic is simply referred to as IVVS (In Vessel Viewing System). The choice fell on a piezoceramic motor due to the presence of strong magnetic fields (up 8 T) and of the high vacuum and temperature conditions. To be compliant with all the ITER environmental conditions it was necessary to qualify the piezo-motor under gamma and neutron irradiation. In this paper are described the procedures and tests that have been performed to verify the compatibility of the operation of the motor adopted in the presence of a fast neutron fluence which was gradually increased over time in order to reach a total value of 2.77 × 10{sup 17} n/cm{sup 2}. Such neutron fluence was obtained by irradiating the motor in a position close to the core of the fast nuclear reactor TAPIRO, in operation at the ENEA Casaccia Research Centre, Italy. The neutron spectrum in this position has been identified as representative of that found in the rest position of the IVVS head during ITER operation. The cumulative neutron fluence reached corresponds to that it is expected to be reached during the entire life of ITER for the IVVS in the rest position without any shield. This work describes the experimental results of this test; the methodology adopted to determine the total neutron fluence achieved and the methodology adopted

  1. Passive detectors for neutron fluence measurement

    International Nuclear Information System (INIS)

    Holt, P.D.

    1985-01-01

    The use of neutron activation detectors (slow neutron detectors and threshold detectors) and fission track detectors for radiological protection purposes, principally in criticality dosimetry, dosimetry of pulsed accelerators and calibration of neutron fluxes is discussed. References are given to compilations of cross sections. For the determination of the activity induced, either beta ray or gamma ray counting may be used. For beta-ray counting, thin foils are usually necessary which result in low neutron sensitivity. When fission track detectors are used, it is necessary to know the efficiency of track registration. Alternatively, a detector-counter system may be calibrated by exposure to a known flux of monoenergetic neutrons. Usually, the sensitivity of activation detectors is low because small foils are used. For criticality dosimetry, calibration work and shielding studies on accelerators, low sensitivity is acceptable. However, there are some instances where, by the use of long integration times, or very large quantities of detector material with gamma ray detection, neutron fluences in operational areas have been measured. (author)

  2. Studies for improvement of WWER-440 neutron fluence determination

    International Nuclear Information System (INIS)

    Ilieva, Kr.; Belousov, S.; Apostolov, T.

    2001-01-01

    For assessment of radiation embrittlement and prediction of reactor vessel lifetime with reasonable conservatism a 'best estimated' neutron fluence is necessary. New studies purposed to improve the fluence determination are presented: 1) study on the reliability of multigroup presentation of the neutron cross sections, and 2) impact of negative gradient of reactor power in the periphery assemblies on the neutron fluence evaluation. The results of these studies are base for improvement of neutron fluence determination methodology applied by the INRNE, BAS at Kozloduy NPP. (author)

  3. Neutron fluence produced in medical accelerators

    International Nuclear Information System (INIS)

    Castro, R.C.; Silva, A.X. da; Crispim, V.R.

    2004-01-01

    Radiotherapy with photon and electron beams still represents the most diffused technique to control and treat tumour diseases. To increase the treatment efficiency, accelerators of higher energy are used, the increase of electron and photon energy is joined with generation of undesired fast neutron that contaminated the therapeutic beam and give a non-negligible contribution to the patient dose. In this work we have simulated with the MCNP4B code the produced neutron spectra in the interaction between the beam and the head to the accelerator and estimating the equivalent dose for neutrons by x-ray dose for aims far from the targets. (author)

  4. A neutron source of variable fluence

    International Nuclear Information System (INIS)

    Brachet, Guy; Demichel, Pascal; Prigent, Yvon; Riche, J.C.

    1975-01-01

    The invention concerns a variable fluence neutron source, like those that use in the known way a reaction between a radioactive emitter and a target, particularly of type (α,n). The emitter being in powder form lies in a carrier fluid forming the target, inside a closed containment. Facilities are provided to cause the fluidisation of the emitter by the carrier fluid in the containment. The fluidisation of the emitting powder is carried out by a booster with blades, actuated from outside by a magnetic coupling. The powder emitter is a α emitter selected in the group of curium, plutonium, thorium, actinium and americium oxides and the target fluid is formed of compounds of light elements selected from the group of beryllium, boron, fluorine and oxygen 18. The target fluid is a gas used under pressure or H 2 O water highly enriched in oxygen 18 [fr

  5. Investigation of neutron fluence using fluence monitors for irradiation test at WWR-K

    International Nuclear Information System (INIS)

    Romanova, N.K.; Takemoto, N.

    2013-01-01

    Irradiation test of a Si ingot is planned using WWR-K in Institute of Nuclear Physics Republic of Kazakhstan (INP RK) to develop an irradiation technology for Si semiconductor production by Neutron Transmutation Doping (NTD) method in the framework of an international cooperation between INP RK and Japan Atomic Energy Agency (JAEA), Japan. It is possible to irradiate the Si ingot of 6 inch in diameter at the K-23 irradiation channel in the WWR-K. The preliminary irradiation test using 4 Al ingots was performed to evaluate the actual neutronic irradiation field at the K-23 channel in the WWR-K. Each Al ingot has the same dimension as the Si ingot, and 15 fluence monitors are equipped in it. Iron wire and aluminum-cobalt wire are inserted into them, and it is possible to evaluate both fast and thermal neutron fluxes by measurement of these radiation activities after irradiation. This report described the results of the preliminary irradiation test and the neutronic calculations by Monte Carlo method in order to evaluate the neutronic irradiation field in the irradiation position for the silicon ingot at the channel in the WWR-K. (authors)

  6. Effects of high thermal neutron fluences on Type 6061 aluminum

    International Nuclear Information System (INIS)

    Weeks, J.R.; Czajkowski, C.J.; Farrell, K.

    1992-01-01

    The control rod drive follower tubes of the High Flux Beam Reactor are contructed from precipitation-hardened 6061-T6 aluminum alloy and they operate in the high thermal neutron flux regions of the core. It is shown that large thermal neutron fluences up to ∼4 x 10 23 n/cm 2 at 333K cause large increases in tensile strength and relatively modest decreases in tensile elongation while significantly reducing the notch impact toughness at room temperature. These changes are attributed to the development of a fine distribution of precipitates of amorphous silicon of which about 8% is produced radiogenically. A proposed role of thermal-to-fast flux ratio is discussed

  7. Neutron Fluence And DPA Rate Analysis In Pebble-Bed HTR Reactor Vessel Using MCNP

    Science.gov (United States)

    Hamzah, Amir; Suwoto; Rohanda, Anis; Adrial, Hery; Bakhri, Syaiful; Sunaryo, Geni Rina

    2018-02-01

    In the Pebble-bed HTR reactor, the distance between the core and the reactor vessel is very close and the media inside are carbon and He gas. Neutron moderation capability of graphite material is theoretically lower than that of water-moderated reactors. Thus, it is estimated much more the fast neutrons will reach the reactor vessel. The fast neutron collisions with the atoms in the reactor vessel will result in radiation damage and could be reducing the vessel life. The purpose of this study was to obtain the magnitude of neutron fluence in the Pebble-bed HTR reactor vessel. Neutron fluence calculations in the pebble-bed HTR reactor vessel were performed using the MCNP computer program. By determining the tally position, it can be calculated flux, spectrum and neutron fluence in the position of Pebble-bed HTR reactor vessel. The calculations results of total neutron flux and fast neutron flux in the reactor vessel of 1.82x108 n/cm2/s and 1.79x108 n/cm2/s respectively. The fast neutron fluence in the reactor vessel is 3.4x1017 n/cm2 for 60 years reactor operation. Radiation damage in stainless steel material caused by high-energy neutrons (> 1.0 MeV) will occur when it has reached the neutron flux level of 1.0x1024 n/cm2. The neutron fluence results show that there is no radiation damage in the Pebble-bed HTR reactor vessel, so it is predicted that it will be safe to operate at least for 60 years.

  8. Neutron fluence determination for light water reactor pressure vessels

    International Nuclear Information System (INIS)

    Gold, R.

    1994-01-01

    A general description of limitations that exist in pressure vessel neutron fluence determinations for commercial light water reactors is presented. Complexity factors that arise in light water reactor pressure vessel neutron fluence calculations are identified and used to analyze calculational limitations. Two broad categories of calculational limitations are introduced, namely benchmark field limitations and deep penetration limitations. Explicit examples of limitations that can arise in each of these two broad categories are presented. These limitations are used to show that the recent draft regulatory guide for the determination of pressure vessel neutron fluence, developed by the Nuclear Regulatory Commission, is based upon procedures and assumptions that are not valid. To eliminate the complexity and limitations of calculational methods, it is recommended that the determination of light water reactor pressure vessel neutron fluence be based upon experiment. Recommendations for improved methods of pressure vessel surveillance neutron dosimetry are advanced

  9. RAMA Methodology for the Calculation of Neutron Fluence

    International Nuclear Information System (INIS)

    Villescas, G.; Corchon, F.

    2013-01-01

    he neutron fluence plays an important role in the study of the structural integrity of the reactor vessel after a certain time of neutron irradiation. The NRC defined in the Regulatory Guide 1.190, the way must be estimated neutron fluence, including uncertainty analysis of the validation process (creep uncertainty is ? 20%). TRANSWARE Enterprises Inc. developed a methodology for calculating the neutron flux, 1,190 based guide, known as RAMA. Uncertainty values obtained with this methodology, for about 18 vessels, are less than 10%.

  10. Spectral fluence of neutrons generated by radiotherapeutic Linacs

    International Nuclear Information System (INIS)

    Kralik, Miloslav; Solc, Jaroslav; Smoldasova, Jana; Vondracek, Vladimir; Farkasova, Estera; Ticha, Ivana

    2015-01-01

    Spectral fluences of neutrons generated in the heads of the radiotherapeutic linacs Varian Clinac 2100 C/D and Siemens ARTISTE were measured by means of the Bonner spheres spectrometer whose active detector of thermal neutrons was replaced by an activation detector, i.e. a tablet made of pure manganese. Measurements with different collimator settings reveal an interesting dependence of neutron fluence on the area defined by the collimator jaws. The determined neutron spectral fluences were used to derive ambient dose equivalent rate along the treatment coach. To clarify at which components of the linac neutrons are mainly created, the measurements were complemented with MCNPX calculations based on a realistic model of the Varian Clinac. (authors)

  11. Nickel Foil as Transmutation Detector for Neutron Fluence Measurements

    Directory of Open Access Journals (Sweden)

    Klupák Vít

    2016-01-01

    Full Text Available Activation detectors are very often used for determination of the neutron fluence in reactor dosimetry. However, there are few disadvantages concerning these detectors; it is the demand of the knowledge of the irradiation history and a loss of information due to a radioactive decay in time. Transmutation detectors TMD could be a solution in this case. The transmutation detectors are materials in which stable or long-lived nuclides are produced by nuclear reactions with neutrons. From a measurement of concentration of these nuclides, neutron fluence can be evaluated regardless of the cooling time.

  12. Safety factors for neutron fluences in NPP safety assessment

    International Nuclear Information System (INIS)

    Demekhin, V.L.; Bukanov, V.N.; Il'kovich, V.V.; Pugach, A.M.

    2016-01-01

    In accordance with global practice and a number of existing regulations, the use of conservative approach is required for the calculations related to nuclear safety assessment of NPP. It implies the need to consider the determination of neutron fluence errors that is rather complicated. It is proposed to carry out the consideration by the way of multiplying the neutron fluences obtained with transport calculations by safety factors. The safety factor values are calculated by the developed technique based on the theory of errors, features of the neutron transport calculation code and the results obtained with the code. It is shown that the safety factor value is equal 1.18 with the confidence level of not less than 0.95 for the majority of VVER-1000 reactor places where neutron fluences are determined by MCPV code, and its maximum value is 1.25

  13. Development of a Secondary Neutron Fluence Standard at GELINA

    International Nuclear Information System (INIS)

    Heyse, Jan; Eykens, Roger; Moens, Andre; Plompen, Arjan J.M.; Schillebeeckx, Peter; Wynants, Ruud; Anastasiou, Maria

    2013-06-01

    The MetroFission project, a Joint Research Project within the European Metrology Research Program, aims at addressing a number of metrological problems involved in the design of proposed Generation IV nuclear reactors. One of the objectives of this multidisciplinary project is the improvement of neutron cross section measurement techniques in order to arrive at uncertainties as required for the design and safety assessment of new generation power plants and fuel cycles. This objective is in line with the 'Uncertainty and target accuracy assessment for innovative systems using recent covariance data evaluations' published by a working party of the OECD Nuclear Energy Agency in 2008. These requests are often very challenging, being at or beyond the state-of-the-art in neutron measurements, which is set by self-normalizing methods and the neutron data standards used at laboratories where the data are measured. A secondary neutron fluence standard has been developed and calibrated at the neutron time-of-flight facility GELINA of the JRC's Institute for Reference Materials and Measurements (IRMM). It consists of a flux monitor, a reference ionization chamber containing a 10 B layer and a 235 U layer, and a parallel plate ionization chamber with 8 well characterized 235 U deposits. These devices are used to determine the neutron fluence, based on the well-known neutron induced fission reaction on 235 U. All deposits have been prepared and characterized at the IRMM target preparation lab. The secondary fluence standard at the GELINA facility can be used for reliable determination of the efficiency of fluence measurement devices used in neutron data measurements at IRMM and elsewhere. It is an essential tool to reliably calibrate fluence normalization devices used in neutron time-of-flight cross section measurements. (authors)

  14. Fast reactor fluence dosimetry. Technical progress report, January--November 1976

    International Nuclear Information System (INIS)

    1976-01-01

    The objectives of this task are to: (1) develop and demonstrate the use of 10 B and 6 Li helium accumulation fluence monitors (HAFM's) as a reliable and accurate method of measuring reactor neutron fluence; (2) develop and apply an expanded set of HAFM's which will provide fluence responses in different but overlapping neutron energy ranges; (3) identify, through the precise measurement of spectrum-integrated helium production cross sections, those elements which produce significant helium when used individually or as components of advanced alloys in FTR and LMFBR neutron environments, so that their use might be eliminated, minimized, or controlled; (4) use this information to predict, with confidence, the helium production rate for any alloy or material considered for fast reactor use, and (5) maintain a centralized helium measurements laboratory available to the research community, and upgrade the sample throughput capacity to handle FTR dosimetry requirements

  15. The development report of an intelligent neutron fluence integration monitor

    International Nuclear Information System (INIS)

    Jiang Zongbing; Wei Ying

    1996-10-01

    An intelligent neutron fluence integration monitor is introduced. It is used to measure the received neutron fluence of the monocrystalline silicon in reactor radiation channel. The significance of study and specifications of the instrument are briefly described. The emphasis is on the working principle, structure and characteristics of the instrument is intelligent due to use of monolithic microcomputer. It has many advantages proved in the actual practice, such as powerful function, high accuracy, diversity of application, high level automatization, easy to operate, high reliability, etc. After using this instrument the monocrystalline silicon radiation technology is improved and the efficiency of production is raised. (1 fig.)

  16. The activation method for determining neutron spectra and fluences

    International Nuclear Information System (INIS)

    Hogel, J.; Vespalec, R.

    1980-01-01

    3 mm thick foils of 4 and 17 mm in diameter were used for measurements. NaI scintillation detectors 45 mm in diameter by 50 mm thick and 40 mm in diameter by 1 mm thick, and a Ge-Li spectrometer of 53 cm 3 in volume were used for gamma detection. A photopeak or a certain part of the integral spectrum was measured for each radionuclide. Computer code PIKAR was applied in automatic calculation of a simple gamma spectrum obtained using the semiconductor spectrometer. The FACT code was used for calculating foil activity. Codes SAND II and RFSP were used for neutron spectra unfolding. Ge-Li detector spectrometry was used for determining neutron fluence. Code FLUE was used for determining the mean value of neutron flux density and fluence. (J.P.)

  17. Calculation of fluences of fast neutrons hitting the pressure vessel of the Dukovany NPP WWER-440 reactor. Part I. Theory, calculations, comparison with the experiment

    International Nuclear Information System (INIS)

    Rataj, J.

    1993-10-01

    The method of calculating neutron spectra and integral flux densities of neutrons hitting the pressure vessel of the Dukovany NPP WWER-440 reactor is outlined. The one-dimensional and two-dimensional calculations were performed by means of the DORT code in R, R-Z, and R-Θ geometries using the cross sections from the ELXSIR library. In the R-Θ geometry, the coupled neutron flux densities were determined. The calculated values of the maximum activation of detectors differ less than 15% from the values measured in surveillance specimens, which is within the limit of uncertainty associated with the position of the detector in the casing. The differences between the calculated and observed data behind the pressure vessel were below 4%. 10 tabs., 3 figs., 41 refs

  18. Application of the adjoint function methodology for neutron fluence determination

    International Nuclear Information System (INIS)

    Haghighat, A.; Nanayakkara, B.; Livingston, J.; Mahgerefteh, M.; Luoma, J.

    1991-01-01

    In previous studies, the neutron fluence at a reactor pressure vessel has been estimated based on consolidation of transport theory calculations and experimental data obtained from in-vessel capsules and/or cavity dosimeters. Normally, a forward neutron transport calculation is performed for each fuel cycle and the neutron fluxes are integrated over the reactor operating time to estimate the neutron fluence. Such calculations are performed for a geometrical model which is composed of one-eighth (0 to 45 deg) of the reactor core and its surroundings; i.e., core barrel, thermal shield, downcomer, reactor vessel, cavity region, concrete wall, and instrumentation well. Because the model is large, transport theory calculations generally require a significant amount of computer memory and time; hence, more efficient methodologies such as the adjoint transport approach have been proposed. These studies, however, do not address the necessary sensitivity studies needed for adjoint function calculations. The adjoint methodology has been employed to estimate the activity of a cavity dosimeter and that of an in-vessel capsule. A sensitivity study has been performed on the mesh distribution used in and around the cavity dosimeter and the in-vessel capsule. Further, since a major portion of the detector response is due to the neutrons originated in the peripheral fuel assemblies, a study on the use of a smaller calculational model has been performed

  19. Neutron irradiation effects on intermetallic precipitates in Zircaloy as a function of fluence

    International Nuclear Information System (INIS)

    Etoh, Y.; Shimada, S.

    1993-01-01

    Intermetallic precipitates in Zircaloy-2 and -4, recrystallized at the α-phase temperature, have been examined using analytical electron microscopy. The specimens were irradiated in BWRs up to a fast neutron fluence of 1.4x10 26 n/m 2 (E>1 MeV). Neutron irradiation induces a crystalline-to-amorphous transition, depleting Fe in the amorphous phase of Zr(Fe, Cr) 2 precipitates in the alloys. Amorphization starts from the periphery of the precipitates and all of them are totally amorphized at higher fluences than 1.2x10 26 n/m 2 . The width of the Fe-depleted zone increases in proportion to the 0.45 power of fluence. This result indicates that diffusion of Fe is the rate-controlling process for Fe depletion in Zr(Fe, Cr) 2 precipitates. Dissolution of Zr 2 (Fe, Ni) precipitates in Zircaloy-2 occurs during neutron irradiation. At a high fluence, such as 1.2x10 26 n/m 2 , Zr 2 (Fe, Ni) precipitates are almost completely dissolved into the matrix and the dissolution rate of Fe is faster than that of Ni. (orig.)

  20. Estimates of neutron fluence for the SDC detector

    International Nuclear Information System (INIS)

    Job, P.K.; Price, L.E.; Handler, T.; Gabriel, T.A.

    1994-01-01

    The high energy and high luminosity of SSC cause radiation problems to detectors. Almost all the radiation in the SDC detector comes from the 20 TeV on 20 TeV pp collisions. The design luminosity corresponds to 10 8 collisions per second. This luminosity is maintained for 10 7 seconds (one SSC year). It is important to know the radiation fields experienced by the tracking volume, calorimeter, electronics and the phototubes. The loss of light due to the radiation damage to the scintillators can adversely affect the physics performance of the calorimeter. Studies have been carried out earlier to estimate the radiation dose in the SDC detector. In this note the authors use ISAJET in combination with CALOR89 to make an accurate prediction of neutron fluence at the various locations of the SDC detector. The low energy neutrons are important because they can produce radioactive nuclides in large quantities. In CALOR89 the low energy neutron fluence is accurately estimated by MORSE code

  1. Fast neutrons dosimetry

    International Nuclear Information System (INIS)

    Rzyski, B.M.

    1977-01-01

    A proton recoil technique has been developed for inducing thermoluminescence with incident fast neutrons. CaF 2 was used as the TL phosphor, and cane sugar and polyethylene were used as proton radiators. The phosphor and the hydrogeneous material powders were well mixed, encapsulated in glass tubes and exposed to Am-Be sources, resulting in recoils from incident fast neutrons of energy between 0,25 and 11,25 MeV. The intrinsic response of pure CaF 2 to fast neutrons without a hydrogeneous radiator was checked by using LiF (TLD-700). Glow curves were recorded from room temperature up to 350 0 C after different doses of neutrons and gamma rays of 60 Co. First collision dose due to fast neutrons in tissue like materials such as cane sugar and polyethylene was also calculated [pt

  2. Deduction of solar neutron fluences from large gamma-ray flares

    International Nuclear Information System (INIS)

    Yoshimori, Masato; Watanabe, Hiroyuki; Takahashi, Kazuyoshi.

    1986-01-01

    Solar neutron fluences from large gamma-ray flares are deduced from accelerated proton spectra and numbers derived from the gamma-ray observations. The deduced solar neutron fluences range from 1 to 200 neutrons cm -2 . The present result indicates a possibility that high sensitivity ground-based neutron monitors can detect solar neutron events, just as detected by the Jungfraujoch and Rome neutron monitors. (author)

  3. Monitoring of the Irradiated Neutron Fluence in the Neutron Transmutation Doping Process of Hanaro

    Science.gov (United States)

    Kim, Myong-Seop; Park, Sang-Jun

    2009-08-01

    Neutron transmutation doping (NTD) for silicon is a process of the creation of phosphorus impurities in intrinsic or extrinsic silicon by neutron irradiation to obtain silicon semiconductors with extremely uniform dopant distribution. HANARO has two vertical holes for the NTD, and the irradiation for 5 and 6 inch silicon ingots has been going on at one hole. In order to achieve the accurate neutron fluence corresponding to the target resistivity, the real time neutron flux is monitored by self-powered neutron detectors. After irradiation, the total irradiation fluence is confirmed by measuring the absolute activity of activation detectors. In this work, a neutron fluence monitoring method using zirconium foils with the mass of 10 ~ 50 mg was applied to the NTD process of HANARO. We determined the proportional constant of the relationship between the resistivity of the irradiated silicon and the neutron fluence determined by using zirconium foils. The determined constant for the initially n-type silicon was 3.126 × 1019 n·Ω/cm. It was confirmed that the difference between this empirical value and the theoretical one was only 0.5%. Conclusively, the practical methodology to perform the neutron transmutation doping of silicon was established.

  4. Fluence-compensated down-scattered neutron imaging using the neutron imaging system at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Casey, D. T., E-mail: casey21@llnl.gov; Munro, D. H.; Grim, G. P.; Landen, O. L.; Spears, B. K.; Fittinghoff, D. N.; Field, J. E.; Smalyuk, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Volegov, P. L.; Merrill, F. E. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-11-15

    The Neutron Imaging System at the National Ignition Facility is used to observe the primary ∼14 MeV neutrons from the hotspot and down-scattered neutrons (6-12 MeV) from the assembled shell. Due to the strong spatial dependence of the primary neutron fluence through the dense shell, the down-scattered image is convolved with the primary-neutron fluence much like a backlighter profile. Using a characteristic scattering angle assumption, we estimate the primary neutron fluence and compensate the down-scattered image, which reveals information about asymmetry that is otherwise difficult to extract without invoking complicated models.

  5. Fast neutron damage of silicon pin photodiodes

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.; Skoczen, A.

    1990-01-01

    A Hamamatsu Photonics photodiode S1723 was tested with respect to the fast neutron radiation. The device was irradiated with neutrons of energies in the range of 0.5 MeV to 12 MeV from a Po-Be source. The irradiation was performed in several steps starting from the relatively low fluence of 2.5 x 10 10 n x cm -2 . The following characteristics were measured: leakage current vs bias voltage, capacitance vs bias voltage and vs frequency, noise vs time constant of a quasigaussian shaper and spectral density of noise. Significant changes of the leakage current and of the noise were observed at the fluence of neutrons as low as 2.5 x 10 10 n x cm -2 . 8 figs., 3 tabs., 15 refs. (author)

  6. Formation of austenite in high Cr ferritic/martensitic steels by high fluence neutron irradiation

    Science.gov (United States)

    Lu, Z.; Faulkner, R. G.; Morgan, T. S.

    2008-12-01

    High Cr ferritic/martensitic steels are leading candidates for structural components of future fusion reactors and new generation fission reactors due to their excellent swelling resistance and thermal properties. A commercial grade 12%CrMoVNb ferritic/martensitic stainless steel in the form of parent plate and off-normal weld materials was fast neutron irradiated up to 33 dpa (1.1 × 10 -6 dpa/s) at 400 °C and 28 dpa (1.7 × 10 -6 dpa/s) at 465 °C, respectively. TEM investigation shows that the fully martensitic weld metal transformed to a duplex austenite/ferrite structure due to high fluence neutron irradiation, the austenite was heavily voided (˜15 vol.%) and the ferrite was relatively void-free; whilst no austenite phases were detected in plate steel. Thermodynamic and phase equilibria software MTDATA has been employed for the first time to investigate neutron irradiation-induced phase transformations. The neutron irradiation effect is introduced by adding additional Gibbs free energy into the system. This additional energy is produced by high energy neutron irradiation and can be estimated from the increased dislocation loop density caused by irradiation. Modelling results show that neutron irradiation reduces the ferrite/austenite transformation temperature, especially for high Ni weld metal. The calculated results exhibit good agreement with experimental observation.

  7. Fast neutron dosimetry

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1992-01-01

    This progress report concentrates on two major areas of dosimetry research: measurement of fast neutron kerma factors for several elements for monochromatic and white spectrum neutron fields and determination of the response of thermoluminescent phosphors to various ultra-soft X-ray energies and beta-rays. Dr. Zhixin Zhou from the Shanghai Institute of Radiation Medicine, People's Republic of China brought with him special expertise in the fabrication and use of ultra-thin TLD materials. Such materials are not available in the USA. The rather unique properties of these materials were investigated during this grant period

  8. Effects of high thermal and high fast fluences on the mechanical properties of type 6061 aluminum in the HFBR

    International Nuclear Information System (INIS)

    Weeks, J.R.; Czajkowski, C.J.; Tichler, P.R.

    1988-01-01

    The High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) is an epithermal, externally moderated (by D 2 O) facility designed to produce neutron beams for research. Type 6061 T-6 aluminum was used for the beam tubes, pressure vessel, fuel cladding, and most other components in the high flux area. The HFBR has operated since 1965. The epithermal, external moderation of the HFBR means that materials irradiated in different areas of the facility receive widely different flux spectra. Thus, specimens from a control rod drive follower tube (CRDF) have received 1.5 /times/ 10 22 n/cm 2 (E > 0.1 MeV) and 3.2 /times/ 10 23 n/cm 2 thermal fluence, while those from a vertical thimble flow shroud received 1.9 /times/ 10 23 n/cm 2 (E > 0.1 MeV) and 1.0 /times/ 10 23 n/cm 2 thermal. These numbers correspond to fast to thermal fluence ratios ranging from 0.05 to 1.9. Irradiations are occurring at approximately 333/degree/K. The data indicate that the increase in tensile strength and decrease in ductility result primarily from the thermal fluence, i.e., the transmutation of aluminum to silicon. These effects appear to be saturating at fluences above approximately 1.8 /times/ 10 23 n/cm 2 thermal at values of 90,000 psi (6700 Kg/mm 2 ) and 9%, respectively. The specimens receiving the highest fluence ratios appear to have less increase in tensile strength and less decrease in ductility than specimens with a lower fast to thermal fluence ratio and the same thermal fluence, suggesting a possible beneficial effect of the high energy neutrons in preventing formation of silicon crystallites. 7 refs., 11 figs., 3 tabs

  9. Neutron Fluence Evaluation of Reactor Internal Structure Using 3D Transport Calculation Code, RAPTOR-M3G

    International Nuclear Information System (INIS)

    Maeng, YoungJae; Lim, MiJoung; Kim, KyungSik; Cho, YoungKi; Yoo, ChoonSung; Kim, ByoungChul

    2015-01-01

    Age-related degradation mechanisms are including the irradiation-assisted stress corrosion cracking(IASCC), void swelling, stress relaxation, fatigue, and etc. A lot of Baffle Former Bolts(BFBs) was installed at the former plate ends between baffle and barrel structure. These would undergo severe experiences, which are high temperature and pressure, bypass water flow and neutron exposure and have some radioactive limitation in inspecting their integrity. The objectives of this paper is to evaluate fast neutron fluence(n/cm 2 , E>1.0MeV) for PWR internals using 3D transport calculation code, RAPTOR-M3G, and to figure out a strategy to manage the effects of aging in PWR internals. One of age-related degradation mechanisms, IASCC, which is affected by fast neutron exposure rate, has been currently issued for PWR internals and has 2 x 10 21 (n/cm 2 ) of the threshold value by MRP-175. Because a lot of BFBs was installed around the internal components, closer inspections are required. As part of an aging management for Kori unit 2, 3D transport calculation code, RAPTOR-M3G, was applied for determining fast neutron fluence at baffle, barrel and former plates regions. As a result, the fast neutron fluence exceeds the screening or threshold values of IASCC in all of baffle, barrel and former plate region. And the most significant region is the baffle because it is located closest to the core. In addition, some regions including former plate tend to be more damaged because of less moderate ability than water. In conclusion, Ice's has been progressed for PWR internals of Kori unit 2. Several regions of internal components were damaged by fast neutron exposure and increase in size as time goes by

  10. THE FLUENCE AND DISTANCE DISTRIBUTIONS OF FAST RADIO BURSTS

    International Nuclear Information System (INIS)

    Vedantham, H. K.; Ravi, V.; Hallinan, G.; Shannon, R. M.

    2016-01-01

    Fast radio bursts (FRB) are millisecond-duration radio pulses with apparent extragalactic origins. All but two of the FRBs have been discovered using the Parkes dish, which employs multiple beams formed by an array of feed horns on its focal plane. In this paper, we show that (i) the preponderance of multiple-beam detections and (ii) the detection rates for varying dish diameters can be used to infer the index α of the cumulative fluence distribution function (the log N –log F function: α = 1.5 for a non-evolving population in a Euclidean universe). If all detected FRBs arise from a single progenitor population, multiple-beam FRB detection rates from the Parkes telescope yield the constraint 0.52 < α < 1.0 with 90% confidence. Searches at other facilities with different dish sizes refine the constraint to 0.5 < α < 0.9. Our results favor FRB searches with smaller dishes, because for α < 1 the gain in field of view for a smaller dish is more important than the reduction in sensitivity. Further, our results suggest that (i) FRBs are not standard candles, and (ii) the distribution of distances to the detected FRBs is weighted toward larger distances. If FRBs are extragalactic, these results are consistent with a cosmological population, which would make FRBs excellent probes of the baryonic content and geometry of the universe.

  11. Solid State Track Recorder fission rate measurements at high neutron fluence and high temperature

    International Nuclear Information System (INIS)

    Ruddy, F.H.; Roberts, J.H.; Gold, R.

    1985-01-01

    Solid State Track Recorder (SSTR) techniques have been used to measure 239-Pu, 235-U, and 237-Np fission rates for total neutron fluences approaching 5 x 10 17 n/cm 2 at temperatures in the range 680 to 830 0 F. Natural quartz crystal SSTRs were used to withstand the high temperature environment and ultra low-mass fissionable deposits of the three isotopes were required to yield scannable track densities at the high neutron fluences. The results of these high temperature, high neutron fluence measurements are reported

  12. High flux-fluence measurements in fast reactors

    International Nuclear Information System (INIS)

    Lippincott, E.P.; Ulseth, J.A.

    1977-01-01

    Characterization of irradiation environments for fuels and materials tests in fast reactors requires determination of the neutron flux integrated over times as long as several years. An accurate integration requires, therefore, passive dosimetry monitors with long half-life or stable products which can be conveniently measured. In addition, burn-up, burn-in, and burn-out effects must be considered in high flux situations and use of minimum quantities of dosimeter materials is often desirable. These conditions force the use of dosimeter and dosimeter container designs, measured products, and techniques that are different from those that are used in critical facilities and other well-characterized benchmark fields. Recent measurements in EBR-II indicate that high-accuracy results can be attained and that tie-backs to benchmark field technique calibrations can be accomplished

  13. Burnup influence on the VVER-1000 reactor vessel neutron fluence evaluation

    International Nuclear Information System (INIS)

    Panayotov, I.; Mihaylov, N.; Ilieva, K.; Kirilova, D.; Manolova, M.

    2009-01-01

    The neutron fluence of the vessels of the reactors is determined regularly accordingly the RPV Surveillance Program of the Kozloduy NPP Unit 5 and 6 in order to assess the state of the metal vessel and their radiation damaging. The calculations are carried out by the method of discrete ordinates used in the TORT program for operated reactor cycles. An average reactor spectrum corresponding to fresh U-235 fuel is used as an input neutron source. The impact of the burn up of the fuel on the neutron fluence of VVER-1000 reactor vessel is evaluated. The calculations of isotopic concentrations of U-235 and Pu-239 corresponding to 4 years burn up were performed by the module SAS2H of the code system SCALE 4.4. Since fresh fuel or 4 years burn up fuel assembly are placed in periphery of reactor core the contribution of Pu-239 of first year burn up and of 4 years burn up is taken in consideration. Calculations of neutron fluence were performed with neutron spectrum for fresh fuel, for 1 year and for 4 years burn up fuel. Correction factors for neutron fluence at the inner surface of the reactor vessel, in 1/4 depth of the vessel and in the air behind the vessel were obtained. The correction coefficient could be used when the neutron fluence is assessed so in verification when the measured activity of ex-vessel detectors is compared with calculated ones. (authors)

  14. Burnup influence on the WWER-1000 reactor vessel neutron fluence evaluation

    International Nuclear Information System (INIS)

    Panayotov, I.; Mihaylov, N.; Ilieva, K.; Kirilova, D.; Manolova, M.

    2009-01-01

    The neutron fluence of the vessels of the reactors is determined regularly accordingly the RPV Surveillance Program of Kozloduy NPP Unit 5 and 6 in order to assess the state of the metal vessel and their radiation damaging. The calculations are carried out by the method of discrete ordinates used in the TORT program for operated reactor cycles. An average reactor spectrum corresponding to fresh U-235 fuel is used as an input neutron source. The impact of the burn up of the fuel on the neutron fluence of WWER-1000 reactor vessel is evaluated. The calculations of isotopic concentrations of U-235 and Pu-239 corresponding to 4 years burn up were performed by the module SAS2H of the code system SCALE 4.4. Since fresh fuel or 4 years burn up fuel assembly are placed in periphery of reactor core the contribution of Pu-239 of first year burn up and of 4 years burn up is taken in consideration. Calculations of neutron fluence were performed with neutron spectrum for fresh fuel, for 1 year and for 4 years burn up fuel. Correction factors for neutron fluence at the inner surface of the reactor vessel, in ? depth of the vessel and in the air behind the vessel were obtained. The correction coefficient could be used when the neutron fluence is assessed so in verification when the measured activity of ex-vessel detectors is compared with calculated ones. (Authors)

  15. Standard Test Method for Measuring Neutron Fluence and Average Energy from 3H(d,n)4He Neutron Generators by Radioactivation Techniques 1

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers a general procedure for the measurement of the fast-neutron fluence rate produced by neutron generators utilizing the 3H(d,n)4He reaction. Neutrons so produced are usually referred to as 14-MeV neutrons, but range in energy depending on a number of factors. This test method does not adequately cover fusion sources where the velocity of the plasma may be an important consideration. 1.2 This test method uses threshold activation reactions to determine the average energy of the neutrons and the neutron fluence at that energy. At least three activities, chosen from an appropriate set of dosimetry reactions, are required to characterize the average energy and fluence. The required activities are typically measured by gamma ray spectroscopy. 1.3 The measurement of reaction products in their metastable states is not covered. If the metastable state decays to the ground state, the ground state reaction may be used. 1.4 The values stated in SI units are to be regarded as standard. No oth...

  16. BPW34 Commercial p-i-n Diodes for High-Level 1-MeV Neutron Equivalent Fluence Monitoring

    CERN Document Server

    Ravotti, F; Moll, M; Saigne, F

    2008-01-01

    The BPW34 p-i-n diode was characterized at CERN in view of its utilization as radiation monitor at the LHC to cover the broad 1-MeV neutron equivalent fluence (Phieq) range expected for the LHC machine and experiments during operation. Electrical measurements for both forward and reverse bias were used to characterize the device and to understand its behavior under irradiation. When the device is powered forward, a sensitivity to fast hadrons for Phieq > 2 times1012 cm-2 has been observed. With increasing particle fluences the forward I- V characteristics of the diode shifts towards higher voltages. At Phieq > 3times1013 cm-2, the forward characteristic starts to bend back assuming a thyristor-like behavior. An explanation for this phenomenon is given in this article. Finally, detailed radiation-response curves for the forward bias-operation and annealing studies of the diode's forward voltage are presented for proton, neutron and gamma irradiation.

  17. Activation measurements for fast neutrons. Part E. Evaluation of fast neutron 63Ni transmission factors

    International Nuclear Information System (INIS)

    Egbert, Stephen D.

    2005-01-01

    The 63 Ni measurements for fast neutrons in copper samples are compared to the calculated free-in-air 63 Ni neutron activation given in Chapter 3 by use of transmission factors. Transmission factors were calculated to account for the modification of the fluence and activation at each sample's in situ location. For the purposes of this discussion, the transmission factor (TF) is defined as the ratio of the in situ sample activation divided by the untilted free-in-air (FIA) activation at a height of 1 m above ground at the same ground range. Examples of the application of TF's will be provided in this section. (author)

  18. Neutron fluence rate and energy spectrum in SPRR-300 reactor thermal column

    International Nuclear Information System (INIS)

    Dou Haifeng; Dai Junlong

    2006-01-01

    In order to modify the simple one-dimension model, the neutron fluence rate distribution calculated with ANISN code ws checked with that calculated with MCNP code. To modify the error caused by ignoring the neutron landscape orientation leaking, the reflector that can't be modeled in a simple one-dimension model was dealt by extending landscape orientation scale. On this condition the neutron fluence rate distribution and the energy spectrum in the thermal column of SPRR-300 reactor were calculated with one-dimensional code ANISN, and the results of Cd ratio are well accorded with the experimental results. The deviation between them is less than 5% and it isn't above 10% in one or two special positions. It indicates that neutron fluence rate distribution and energy spectrum in the thermal column can be well calculated with one-dimensional code ANISN. (authors)

  19. Direct Fast-Neutron Detection

    International Nuclear Information System (INIS)

    DC Stromswold; AJ Peurrung; RR Hansen; PL Reeder

    2000-01-01

    Direct fast-neutron detection is the detection of fast neutrons before they are moderated to thermal energy. We have investigated two approaches for using proton-recoil in plastic scintillators to detect fast neutrons and distinguish them from gamma-ray interactions. Both approaches use the difference in travel speed between neutrons and gamma rays as the basis for separating the types of events. In the first method, we examined the pulses generated during scattering in a plastic scintillator to see if they provide a means for distinguishing fast-neutron events from gamma-ray events. The slower speed of neutrons compared to gamma rays results in the production of broader pulses when neutrons scatter several times within a plastic scintillator. In contrast, gamma-ray interactions should produce narrow pulses, even if multiple scattering takes place, because the time between successive scattering is small. Experiments using a fast scintillator confirmed the presence of broader pulses from neutrons than from gamma rays. However, the difference in pulse widths between neutrons and gamma rays using the best commercially available scintillators was not sufficiently large to provide a practical means for distinguishing fast neutrons and gamma rays on a pulse-by-pulse basis. A faster scintillator is needed, and that scintillator might become available in the literature. Results of the pulse-width studies were presented in a previous report (peurrung et al. 1998), and they are only summarized here

  20. Neutron fluence-to-dose conversion coefficients for embryo and fetus

    International Nuclear Information System (INIS)

    Chen, J.; Meyerhof, D.; Vlahovich, S.

    2004-01-01

    A problem of concern in radiation protection is the exposure of pregnant women to ionising radiation, because of the high radiosensitivity of the embryo and fetus. External neutron exposure is of concern when pregnant women travel by aeroplane. Dose assessments for neutrons frequently rely on fluence-to-dose conversion coefficients. While neutron fluence-to-dose conversion coefficients for adults are recommended in International Commission on Radiological Protection publications and International Commission on Radiological Units and Measurements reports, conversion coefficients for embryos and fetuses are not given in the publications. This study undertakes Monte Carlo calculations to determine the mean absorbed doses to the embryo and fetus when the mother is exposed to neutron fields. A new set of mathematical models for the embryo and fetus has been developed at Health Canada and is used together with mathematical phantoms of a pregnant female developed at Oak Ridge National Laboratory. Monoenergetic neutrons from 1 eV to 10 MeV are considered in this study. The irradiation geometries include antero-posterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT) and isotropic (ISO) geometries. At each of these standard irradiation geometries, absorbed doses to the fetal brain and body are calculated; for the embryo at 8 weeks and the fetus at 3, 6 or 9 months. Neutron fluence-to-absorbed dose conversion coefficients are derived for the four age groups. Neutron fluence-to-equivalent dose conversion coefficients are given for the AP irradiations which yield the highest radiation dose to the fetal body in the neutron energy range considered here. The results indicate that for neutrons <10 MeV more protection should be given to pregnant women in the first trimester due to the higher absorbed dose per unit neutron fluence to the fetus. (authors)

  1. Neutron fluence-to-dose conversion coefficients for embryo and fetus.

    Science.gov (United States)

    Chen, Jing; Meyerhof, Dorothy; Vlahovich, Slavica

    2004-01-01

    A problem of concern in radiation protection is the exposure of pregnant women to ionising radiation, because of the high radiosensitivity of the embryo and fetus. External neutron exposure is of concern when pregnant women travel by aeroplane. Dose assessments for neutrons frequently rely on fluence-to-dose conversion coefficients. While neutron fluence-to-dose conversion coefficients for adults are recommended in International Commission on Radiological Protection publications and International Commission on Radiological Units and Measurements reports, conversion coefficients for embryos and fetuses are not given in the publications. This study undertakes Monte Carlo calculations to determine the mean absorbed doses to the embryo and fetus when the mother is exposed to neutron fields. A new set of mathematical models for the embryo and fetus has been developed at Health Canada and is used together with mathematical phantoms of a pregnant female developed at Oak Ridge National Laboratory. Monoenergetic neutrons from 1 eV to 10 MeV are considered in this study. The irradiation geometries include antero-posterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT) and isotropic (ISO) geometries. At each of these standard irradiation geometries, absorbed doses to the fetal brain and body are calculated; for the embryo at 8 weeks and the fetus at 3, 6 or 9 months. Neutron fluence-to-absorbed dose conversion coefficients are derived for the four age groups. Neutron fluence-to-equivalent dose conversion coefficients are given for the AP irradiations which yield the highest radiation dose to the fetal body in the neutron energy range considered here. The results indicate that for neutrons <10 MeV more protection should be given to pregnant women in the first trimester due to the higher absorbed dose per unit neutron fluence to the fetus.

  2. Development of the processing software package for RPV neutron fluence determination methodology

    International Nuclear Information System (INIS)

    Belousov, S.; Kirilova, K.; Ilieva, K.

    2001-01-01

    According to the INRNE methodology the neutron transport calculation is carried out by two steps. At the first step reactor core eigenvalue calculation is performed. This calculation is used for determination of the fixed source for the next step calculation of neutron transport from the reactor core to the RPV. Both calculation steps are performed by state of the art and tested codes. The interface software package DOSRC developed at INRNE is used as a link between these two calculations. The package transforms reactor core calculation results to neutron source input data in format appropriate for the neutron transport codes (DORT, TORT and ASYNT) based on the discrete ordinates method. These codes are applied for calculation of the RPV neutron flux and its responses - induced activity, radiation damage, neutron fluence etc. Fore more precise estimation of the neutron fluence, the INRNE methodology has been supplemented by the next improvements: - implementation of more advanced codes (PYTHIA/DERAB) for neutron-physics parameter calculations; - more detailed neutron source presentation; - verification of neutron fluence by statistically treated experimental data. (author)

  3. The polarization of fast neutrons

    International Nuclear Information System (INIS)

    Talov, V.V.

    2000-01-01

    The present work is the review of polarization of fast neutrons and methods of polarization analysis. This also includes information about polarization of fast neutrons from first papers, which described polarization in the D(d,n) 3 He, 7 Li(p,n) 7 Be, and T(p,n) 3 He reactions. (authors)

  4. A novel wide range, real-time neutron fluence monitor based on commercial off the shelf gallium arsenide light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, B., E-mail: bhaskar.mukherjee@uk-essen.de [Westdeutsches Protonentherapiezentrum Essen (WPE) gGmbH, Hufelandstrasse 55, D-45147 Essen (Germany); Hentschel, R. [Strahlenklinik, University Hospital Essen (Germany); Lambert, J. [Westdeutsches Protonentherapiezentrum Essen (WPE) gGmbH, Hufelandstrasse 55, D-45147 Essen (Germany); Deya, W. [Strahlenklinik, University Hospital Essen (Germany); Farr, J. [Westdeutsches Protonentherapiezentrum Essen (WPE) gGmbH, Hufelandstrasse 55, D-45147 Essen (Germany)

    2011-10-01

    Displacement damage produced by high-energy neutrons in gallium arsenide (GaAs) light emitting diodes (LED) results in the reduction of light output. Based on this principle we have developed a simple, cost effective, neutron detector using commercial off the shelf (COTS) GaAs-LED for the assessment of neutron fluence and KERMA at critical locations in the vicinity of the 230 MeV proton therapy cyclotron operated by Westdeutsches Protonentherapiezentrum Essen (WPE). The LED detector response (mV) was found to be linear within the neutron fluence range of 3.0x10{sup 8}-1.0x10{sup 11} neutron cm{sup -2}. The response of the LED detector was proportional to neutron induced displacement damage in LED; hence, by using the differential KERMA coefficient of neutrons in GaAs, we have rescaled the calibration curve for two mono-energetic sources, i.e. 1 MeV neutrons and 14 MeV neutrons generated by D+T fusion reaction. In this paper we present the principle of the real-time GaAs-LED based neutron fluence monitor as mentioned above. The device was calibrated using fast neutrons produced by bombarding a thick beryllium target with 14 MeV deuterons from a TCC CV 28 medical cyclotron of the Strahlenklinik University Hospital Essen.

  5. Development of neutron fluence measurement and evaluation technology for the test materials in the capsule

    Energy Technology Data Exchange (ETDEWEB)

    Hong, U.; Choi, S. H.; Kang, H. D. [Kyungsan University, Kyungsan (Korea)

    2000-03-01

    The four kinds of the fluence monitor considered by self-shielding are design and fabricated for evaluation of neutron irradiation fluence. They are equipped with dosimeters consisting of Ni, Fe and Ti wires and so forth. The nuclear reaction rate is obtained by measurement on dosimeter using the spectroscopic analysis of induced {gamma}-ray. We established the nuetron fluence evaluating technology that is based on the measurement of the reaction rate considering reactor's irradiation history, burn-out, self-shielding in fluence monitor, and the influence of impurity in dosimeter. The distribution of high energy neutron flux on the vertical axis of the capsule shows fifth order polynomial equation and is good agree with theoretical value in the error range of 30% by MCNP/4A code. 22 refs., 50 figs., 27 tabs. (Author)

  6. Contraband detection with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Buffler, Andy E-mail: abuffler@science.uct.ac.za

    2004-11-01

    Recent terror events and the increase in the trade of illicit drugs have fuelled the exploration of the use of fast neutrons as probes for the detection of hidden contraband, especially explosives, in packages ranging in size from small mail items to cargo containers. The various approaches using fast neutrons for contraband detection, presently under development, are reviewed. The role that a neutron system might play in the non-intrusive interrogation of airline luggage is discussed.

  7. Superconductivity in irradiated A-15 compounds at low fluences. I. Neutron-irradiated V3Si

    International Nuclear Information System (INIS)

    Viswanathan, R.; Caton, R.; Pande, C.S.

    1978-01-01

    The behavior of the superconducting transition temperature T/sub c/ of single-crystal and polycrystalline V 3 Si was investigated as a function of low-fluence neutron irradiation. It is found that the initial degradation of T/sub c/ is sample-dependent, some specimens showing no degradation in T/sub c/ up to a fluence of 2 x 10 18 n/cm 2 . This and many other earlier observations on low-fluence behavior are explained in terms of a recently proposed model of radiation damage in A-15 compounds

  8. Compaction in optical fibres and fibre Bragg gratings under nuclear reactor high neutron and gamma fluence

    Energy Technology Data Exchange (ETDEWEB)

    Remy, L.; Cheymol, G. [CEA, French Nuclear Energy Commission, Nuclear Energy Division, DPC/SEARS/LISL Bat 467 CEA Saclay 91191 Gif/Yvette Cedex (France); Gusarov, A. [SCK.CEN - Belgian Nuclear Research center, Boeretang 200 2400 Mol (Belgium); Morana, A.; Marin, E.; Girard, S. [Universite de Saint-Etienne, Laboratoire Hubert Curien, UMR CNRS5516, 18, rue du Pr. Lauras, F-42000 Saint-Etienne (France)

    2015-07-01

    In the framework of the development by CEA and SCK.CEN of a Fabry Perot Sensor (FPS) able to measure dimensional changes in Material Testing Reactor (MTR), the first goal of the SAKE 1 (Smirnof extention - Additional Key-tests on Elongation of glass fibres) irradiation was to measure the linear compaction of single mode fibres under high fast neutron fluence. Indeed, the compaction of the fibre which forms one side of the Fabry Perot cavity, may in particular cause a noticeable measurement error. An accurate quantification of this effect is then required to predict the radiation-induced drift and optimize the sensor design. To achieve this, an innovative approach was used. Approximately seventy uncoated fibre tips (length: 30 to 50 mm) have been prepared from several different fibre samples and were installed in the SCK.CEN BR2 reactor (Mol Belgium). After 22 days of irradiation a total fast (E > 1 MeV) fluence of 3 to 5x10{sup 19} n{sub fast}/cm{sup 2}, depending on the sample location, was accumulated. The temperature during irradiation was 291 deg. C, which is not far from the condition of the intended FPS use. A precise measurement of each fibre tip length was made before the irradiation and compared to the post irradiation measurement highlighting a decrease of the fibres' length corresponding to about 0.25% of linear compaction. The amplitude of the changes is independent of the capsule, which could mean that the compaction effect saturates even at the lowest considered fluence. In the prospect of performing distributed temperature measurement in MTR, several fibre Bragg gratings written using a femtosecond laser have been also irradiated. All the gratings were written in radiation hardened fibres, and underwent an additional treatment with a procedure enhancing their resistance to ionizing radiations. A special mounting made it possible to test the reflection and the transmission of the gratings on fibre samples cut down to 30 to 50 mm. The comparison

  9. The polarization of fast neutrons

    International Nuclear Information System (INIS)

    Talov, V.V.

    2001-01-01

    It is insufficient to know coordinates and momentum to describe a state of a neutron. It is necessary to define a spin orientation. As far as it is known from quantum mechanics, a half spin has a projection in the positive direction or in the negative direction. The probability of both projections in an unpolarized beam is equal. If a direction exists, in which the projection is more probably then beam is called polarized in this direction. It is essential to know polarization of neutrons for characteristics of a neutron source, which is emitting it. The question of polarization of fast neutrons came up in 50's. The present work is the review of polarization of fast neutrons and methods of polarization analysis. This also includes information about polarization of fast neutrons from first papers, which described polarization in the D(d,n) 3 He, 7 Li (p,n) 7 Be, T(p,n) 3 He reactions. (authors)

  10. Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4

    International Nuclear Information System (INIS)

    Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R.

    2014-01-01

    Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H p (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm 3 , composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm 2 ). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

  11. Feasibility study on using imaging plates to estimate thermal neutron fluence in neutron-gamma mixed fields

    International Nuclear Information System (INIS)

    Fujibuchi, T.; Tanabe, Y.; Sakae, T.; Terunuma, T.; Isobe, T.; Kawamura, H.; Yasuoka, K.; Matsumoto, T.; Harano, H.; Nishiyama, J.; Masuda, A.; Nohtomi, A.

    2011-01-01

    In current radiotherapy, neutrons are produced in a photonuclear reaction when incident photon energy is higher than the threshold. In the present study, a method of discriminating the neutron component was investigated using an imaging plate (IP) in the neutron-gamma-ray mixed field. Two types of IP were used: a conventional IP for beta- and gamma rays, and an IP doped with Gd for detecting neutrons. IPs were irradiated in the mixed field, and the photo-stimulated luminescence (PSL) intensity of the thermal neutron component was discriminated using an expression proposed herein. The PSL intensity of the thermal neutron component was proportional to thermal neutron fluence. When additional irradiation of photons was added to constant neutron irradiation, the PSL intensity of the thermal neutron component was not affected. The uncertainty of PSL intensities was approximately 11.4 %. This method provides a simple and effective means of discriminating the neutron component in a mixed field. (authors)

  12. Radiation clusters formation and evolution in FCC metals at low-temperature neutron irradiation up to small damage fluences

    International Nuclear Information System (INIS)

    Kozlov, A.V.; Shcherbakov, E.N.; Asiptsov, O.I.; Skryabin, L.A.; Portnykh, I.A.

    2006-01-01

    Methods of transmission electron microscopy and precision size measurements are used to study the formation of radiation-induced clusters in FCC metals (Ni, Pt, austenitic steels EhI-844, ChS-68) irradiated with fast neutron (E>0.1 MeV) fluences from 7 x 10 21 up to 3.5 x 10 22 m -2 at a temperature of 310 K. Using statistical thermodynamic methods the process of radiation clusters formation and evolution is described quantitatively. The change in the concentration of point defects under irradiation as well as size variations of irradiated specimens on annealing are calculated [ru

  13. Fast neutron spectrometry and dosimetry

    International Nuclear Information System (INIS)

    Blaize, S.; Ailloud, J.; Mariani, J.; Millot, J.P.

    1958-01-01

    We have studied fast neutron spectrometry and dosimetry through the recoil protons they produce in hydrogenated samples. In spectrometric, we used nuclear emulsions, in dosimetric, we used polyethylene coated with zinc sulphide and placed before a photomultiplier. (author) [fr

  14. Fast and slow neutrons in an 18-MV photon beam from a Philips SL/75-20 linear accelerator

    International Nuclear Information System (INIS)

    Gur, D.; Rosen, J.C.; Bukovitz, A.G.; Gill, A.W.

    1978-01-01

    Fast- and slow-neutron contamination in an 18-MV photon beam from a Philips SL/75-20 linear accelerator has been measured. Aluminum and indium foils were activated to determine fast- and slow-neutron fluence, which were largely independent of field sizes. Measured fast-neutron fluences were typically 13.9 x 10 4 and 4.4 x 10 4 neutrons/cm 2 /rad of x ray inside and 5 cm outside the field, respectively. Slow-neutron fluences, 1.3 x 10 4 neutrons/cm 2 /rad of x ray, remained relatively constant inside and outside the field. The reported results are about three times higher than neutron fluences recently reported with a betatron operated at the same energy

  15. Determination of neutron fluence and radiation brittleness temperature of WWER-440 and WWER-1000 pressure vessels in Kozloduy NPP

    International Nuclear Information System (INIS)

    Ilieva, K.; Apostolov, T.; Belousov, S.; Petrova, T.; Antonov, S.; Ivanov, K.; Prodanova, R.

    1993-01-01

    In Units 1-4 of Kozloduy NPP (WWER-440/230), the weld 4 of RPV undergoes the most severe irradiation embrittlement. Neither witness-samples, nor detectors are designed for these reactors. Transport calculations of fast neutron fluence on WWER-440 RPV and ex-vessel measurements by threshold activation detectors are the primary means for adequate assessment of metal state and for prognosis concerning the reactor life span. In WWER-1000 reactors (Units 5-6) the maximum neutron fluence occurs on the weld 3. The systematical observation of metal state is performed through witness-samples and threshold activation detectors ( 54 Fe (n,p), 63 Cu (n,α), 93 Nb (n,n')) placed above the reactor top edge and at the first vessel ring level. There are big differences in energy spectrum and integral neutron flux falling onto the weld 3, the RPV base metal and the staff detectors. This requires additional neutron measurements in the air gap between the RPV and the thermal insulation. (author)

  16. Study on measurement technique contrast of 14 MeV neutron fluence

    International Nuclear Information System (INIS)

    Jiang Li; Hu Jun; Wen Dezhi

    2005-10-01

    The stability and repetition of the associated-particle method to measure DT neutron fluence was tested. The neutron activation iron method was contrasted with the associated-particle method, the preparatory experiment was done. The neutron fluence measured with associated-particle method was contrasted with neutron activation Al method, the Al activated foil was measured with 4πβ (PC)-γ coincidence standard device. The contrast result's standard deviation of the two method was less than the expand uncertainty of the associated-particle method. Therein, the uncertainty of the associated-particle method is 1.6%, the uncertainty of the activation Al method is 1.8%. (authors)

  17. The plasma focus as a large fluence neutron source

    International Nuclear Information System (INIS)

    Zucker, O.; Bostick, W.; Long, J.; Luce, J.; Sahlin, H.

    1977-01-01

    A continuously operated, 1 pps, dense-plasma-focus device capable of delivering a minimum of 10 15 neutrons per pulse for material testing purposes is described. With I 5 scaling, predicted from analysis of existing machines, yields of 10 16 -10 17 neutrons per pulse are postulated. The average power consumption, which has become a major issue as a result of the energy crisis is shown to be highly favorable. A novel approach to the capacitor bank and switch design allowing repetitive operation is discussed. (Auth.)

  18. Absolute measurement and international intercomparison of 0.1-0.8 MeV monoenergetic neutron fluence rate

    International Nuclear Information System (INIS)

    Ma Hongchang; Lu Hanlin; Rong Chaofan

    1988-01-01

    The methods for absolute measurement of 0.1-18MeV monoenergetic neutron fluence rate are described. Which include proton recoil telescope, semicoducetor telescope, hydrogen filled proportional counter and associated particale method. A long counter used as secondary recent international intercomparison of neutron fluence rate organized by BIPM, and the results were given

  19. Ultra-fast fluence optimization for beam angle selection algorithms

    Science.gov (United States)

    Bangert, M.; Ziegenhein, P.; Oelfke, U.

    2014-03-01

    Beam angle selection (BAS) including fluence optimization (FO) is among the most extensive computational tasks in radiotherapy. Precomputed dose influence data (DID) of all considered beam orientations (up to 100 GB for complex cases) has to be handled in the main memory and repeated FOs are required for different beam ensembles. In this paper, the authors describe concepts accelerating FO for BAS algorithms using off-the-shelf multiprocessor workstations. The FO runtime is not dominated by the arithmetic load of the CPUs but by the transportation of DID from the RAM to the CPUs. On multiprocessor workstations, however, the speed of data transportation from the main memory to the CPUs is non-uniform across the RAM; every CPU has a dedicated memory location (node) with minimum access time. We apply a thread node binding strategy to ensure that CPUs only access DID from their preferred node. Ideal load balancing for arbitrary beam ensembles is guaranteed by distributing the DID of every candidate beam equally to all nodes. Furthermore we use a custom sorting scheme of the DID to minimize the overall data transportation. The framework is implemented on an AMD Opteron workstation. One FO iteration comprising dose, objective function, and gradient calculation takes between 0.010 s (9 beams, skull, 0.23 GB DID) and 0.070 s (9 beams, abdomen, 1.50 GB DID). Our overall FO time is < 1 s for small cases, larger cases take ~ 4 s. BAS runs including FOs for 1000 different beam ensembles take ~ 15-70 min, depending on the treatment site. This enables an efficient clinical evaluation of different BAS algorithms.

  20. Ultra-fast fluence optimization for beam angle selection algorithms

    International Nuclear Information System (INIS)

    Bangert, M; Ziegenhein, P; Oelfke, U

    2014-01-01

    Beam angle selection (BAS) including fluence optimization (FO) is among the most extensive computational tasks in radiotherapy. Precomputed dose influence data (DID) of all considered beam orientations (up to 100 GB for complex cases) has to be handled in the main memory and repeated FOs are required for different beam ensembles. In this paper, the authors describe concepts accelerating FO for BAS algorithms using off-the-shelf multiprocessor workstations. The FO runtime is not dominated by the arithmetic load of the CPUs but by the transportation of DID from the RAM to the CPUs. On multiprocessor workstations, however, the speed of data transportation from the main memory to the CPUs is non-uniform across the RAM; every CPU has a dedicated memory location (node) with minimum access time. We apply a thread node binding strategy to ensure that CPUs only access DID from their preferred node. Ideal load balancing for arbitrary beam ensembles is guaranteed by distributing the DID of every candidate beam equally to all nodes. Furthermore we use a custom sorting scheme of the DID to minimize the overall data transportation. The framework is implemented on an AMD Opteron workstation. One FO iteration comprising dose, objective function, and gradient calculation takes between 0.010 s (9 beams, skull, 0.23 GB DID) and 0.070 s (9 beams, abdomen, 1.50 GB DID). Our overall FO time is < 1 s for small cases, larger cases take ∼ 4 s. BAS runs including FOs for 1000 different beam ensembles take ∼ 15–70 min, depending on the treatment site. This enables an efficient clinical evaluation of different BAS algorithms.

  1. Fast neutron response of coumarin in water and heavy water

    International Nuclear Information System (INIS)

    Krishnan, D.; Kher, R.K.; Gopakumar, K.; Bhandari, N.S.

    1979-01-01

    Response of coumarin in aqueous solution has been studied earlier for gamma rays and fast neutrons by fluorescence measurement. For further fast neutron studies, two systems viz coumarin in H 2 0 and coumarin in D 2 0, were irradiated with fast neutrons in SNIF facility in the swimming pool type APSARA reactor at Trombay. Neutron fluence was estimated by measuring induced activity in sulphur pellet and associated gamma radiation was estimated using CaS0 4 :Dy TLD powder. The KERMA values were calculated for H 2 0 and D 2 0, assuming modified fission spectrum for fast neutron in SNIF position, and they were in the ratio of 2:1. Response of a chemical dosimetric system is expected to be proportional to the absorbed dose in the respective system for the same neutron fluence. This was experimentally found to be the case for coumarin in H 2 0 or D 2 0. These results are likely to be true in general for any aqueous chemical system. The limitations of using such a dual system for dosimetry in a mixed field is discussed. (author)

  2. About reliability of WWER pressure vessel neutron fluence calculation

    Energy Technology Data Exchange (ETDEWEB)

    Belousov, S; Ilieva, K; Antonov, S [Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. za Yadrena Izsledvaniya i Yadrena Energetika

    1996-12-31

    This reliability study was carried out under a Research Contracts F111 and TH-324 of the Bulgarian Ministry of Higher Education and the IAEA. The effect of geometry approximation and the choice of neutron cross-sections on the calculation model is estimated. The neutron flux onto reactor pressure vessel at locations, important for metal embrittlement surveillance, has been calculated using the codes TORT and DORT. The flux values calculated for both WWER-440 and WWER-1000 show good consistency within the limits of solution accuracy. It is concluded that the synthesis method (DORT) can be used for calculations at a reasonable cost whenever metal embrittlement surveillance is considered. Using an iron sphere benchmark measurement, a comparison of an experimental leakage spectrum with spectrum calculated using multigroup neutron cross-sections based on ENDF/B-4 and ENDF/B-6 data is performed. In the energy region above 1 MeV the best agreement with the experiment is achieved for ENDF/B-6 in VITAMIN-E group structure. 7 refs., 1 fig., 4 tabs.

  3. About reliability of WWER pressure vessel neutron fluence calculation

    International Nuclear Information System (INIS)

    Belousov, S.; Ilieva, K.; Antonov, S.

    1995-01-01

    This reliability study was carried out under a Research Contracts F111 and TH-324 of the Bulgarian Ministry of Higher Education and the IAEA. The effect of geometry approximation and the choice of neutron cross-sections on the calculation model is estimated. The neutron flux onto reactor pressure vessel at locations, important for metal embrittlement surveillance, has been calculated using the codes TORT and DORT. The flux values calculated for both WWER-440 and WWER-1000 show good consistency within the limits of solution accuracy. It is concluded that the synthesis method (DORT) can be used for calculations at a reasonable cost whenever metal embrittlement surveillance is considered. Using an iron sphere benchmark measurement, a comparison of an experimental leakage spectrum with spectrum calculated using multigroup neutron cross-sections based on ENDF/B-4 and ENDF/B-6 data is performed. In the energy region above 1 MeV the best agreement with the experiment is achieved for ENDF/B-6 in VITAMIN-E group structure. 7 refs., 1 fig., 4 tabs

  4. Induced mutation breeding by fast neutron

    International Nuclear Information System (INIS)

    Chen Zhengba; You Risheng

    1988-09-01

    The high-yield and long-grain new variety 'Zhongtie 31' was developed through five generations after irradiation of the rice variety 'Tieqiu 15' dried seeds by 14 MeV fast neutrons with a fluence of (1.33 ∼ 3.33) x 10 11 neutrons cm -2 . It matured earlier 3 to 5 days, the plant is higher 10 cm, bigger ear, more grain than its original variety 'tieqiu 15', and the yield increased by 19.2% to 30.7%. The source of new variety 'Zhongtie 31' was proved by the isoenzyme genetics. In field test, it increased by 7% to 10% as compared with high-yield variety 'Guichao No.2' and the hybrid rive 'Shanyou No.2', and is more palatable. The new variety was initiated by irradiation mutagensis routine rice, its well-grown and bumper-yield performances may be compared favourably with hybrid rice variety. In July 1986, the new variety 'Zhongtie 31' was obtained by inducing mutation with fast neutron. The same year, the planted area of 'Zhongtie 31' has achieved upto 250 thousand mu (1.67 x 10 8 cm 2 )

  5. Computerized tomography using fast neutrons

    International Nuclear Information System (INIS)

    Maier-Schuler, P.

    1992-03-01

    The equipment is transportable and can be used at different neutron sources. CT-images are presented showing that it is possible to get good results by using CT with fast neutrons in non destructive testing. Small defects with high contrasts can be detected as well as larger defects with small differences in material density. Since the neutrons interact with the nuclei and not with the electron density the CT-images contain different information compared with X-ray or γ images. As neutron sources always emit γ-radiation too, this radiation can be detected simultaneously with the neutrons. Therefore one can get a γ CT-image along with the neutron image. For the examination of small samples or objects containing materials with great differences in the linear attenuation coefficients like Al and H 2 thermal neutrons have been used for CT-measurements too. A spatial resolution and a density resolution of 0.1 mm and about 5% respectively could be achieved in the CT-images with fast neutrons and 0.04 mm with thermal neutrons. (orig./HP) [de

  6. Measurement of low neutron-fluences using electrochemically etched PC and PET track detectors

    International Nuclear Information System (INIS)

    Somogyi, G.; Dajko, G.; Turek, K.; Spurny, F.

    1979-01-01

    Systematic investigations have been carried out to study different properties of electrochemically etched (ECE) polycarbonate (PC) and polyethylene-terephthalate (PET) foils. The dependence of the density of background discharge spots on surface-thickness removal, electrical field strength and frequency of voltage is given. The effect of these parameters on the neutron sensitivity of polycarbonate and polyethylene-terephthalate foils irradiated at right angles to 14.7 MeV, 241 Am-Be and 252 Cf neutrons is also studied. With knowledge of the background and sensitivity data, the etching and electrical parameters are optimized for low neutron-fluence measurements. (author)

  7. Neutron fluence-to-dose equivalent conversion factors: a comparison of data sets and interpolation methods

    International Nuclear Information System (INIS)

    Sims, C.S.; Killough, G.G.

    1983-01-01

    Various segments of the health physics community advocate the use of different sets of neutron fluence-to-dose equivalent conversion factors as a function of energy and different methods of interpolation between discrete points in those data sets. The major data sets and interpolation methods are used to calculate the spectrum average fluence-to-dose equivalent conversion factors for five spectra associated with the various shielded conditions of the Health Physics Research Reactor. The results obtained by use of the different data sets and interpolation methods are compared and discussed. (author)

  8. A new expression for determination of fluences from a spherical moderator neutron source for the calibration of spherical neutron measuring devices

    International Nuclear Information System (INIS)

    Khoshnoodi, M.; Sohrabi, M.

    1997-01-01

    A new expression modifying the inverse square law for determination of neutron fluences from spherical moderator neutron sources is reported. The formalism is based on the neutron fluence at a point outside the moderator as the summation of fluxes of two groups of neutrons: direct neutrons from the central region of the moderator, and moderated neutrons which, to a first approximation, are scattered from the outermost layers of the spherical moderator. The expression has been further developed for spherical neutron measuring devices with an appropriate geometry factor which corrects the reading of the device for non-uniform irradiation of the detector. The combination of the new fluence function and those of the air and room scattered components introduce a calibration model. The fluence relationship obtained for moderated sources may conveniently be used for calculating the more rapid change of neutron dose at close distances than that which is based on the inverse square dependence. (author)

  9. Fast neutron dosimetry

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1991-01-01

    During 1988--1990 the magnetic resonance dosimetry project was completed, as were the 250 MeV proton shielding measurements. The first cellular experiment using human cells in vitro at the 1 GeV electron storage ring was also accomplished. More detail may be found in DOE Report number-sign DOE/EV/60417-002 and the open literature cited in the individual progress subsections. We report Kinetic Energy Released in Matter (KERMA), factor measurements in several elements of critical importance to neutron radiation therapy and radiation protection for space habitation and exploration for neutron energies below 30 MeV. The results of this effort provide the only direct measurements of the oxygen and magnesium kerma factors above 20 MeV neutron energy, and the only measurements of the iron kerma factor above 15 MeV. They provide data of immediate relevance to neutron radiotherapy and impose strict criteria for normalizing and testing nuclear models used to calculate kerma factors at higher neutron energies

  10. A new method for the determination of unknown neutron fluence for 14.0 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Fariha [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan)]. E-mail: fariha@pinstech.org.pk; Khan, Ehsan U. [Department of Physics, CIIT, Islamabad (Pakistan); Qureshi, Imtinan [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Husaini, Syed N. [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Ahmad, Waqar [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Rajput, Usman [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Raza, Qaiser [Applied Physics Division, PINSTECH, Nilore, Islamabad (Pakistan)

    2006-11-15

    Measuring the correct neutron fluence in various energy intervals in and around the neutron sources is important for the purpose of personnel and environmental neutron dosimetry. In this paper, we present a new method for the measurement of the fluence of mono-energetic neutrons having the energy of 14.0 MeV. The samples exposed to neutrons from the 14.0 MeV neutron generator at PINSTECH with various fluence values ranging from 10{sup 7} to 10{sup 10} n cm{sup -2} were etched for 10 min in 6 N NaOH at 70.0{+-}1.0 {sup o}C and the transmittance of UV radiation was measured using a spectrophotometer. This procedure was repeated 20 times after etching the same sample each time for increasing time intervals till the stage when transmittance reached the constant minimum value. An exponential decay of the transmittance has been observed with respect to the increasing etching time interval in each of the samples exposed to various neutron fluence. Further, it has also been observed that there is a linear relationship between the transmittance decay constant and neutron fluence. Hence, the linear graph can be used as a calibration for measuring the unknown fluence of 14.0 MeV neutrons.

  11. The effect of incremental gamma-ray doses and incremental neutron fluences upon the performance of self-biased sup 1 sup 0 B-coated high-purity epitaxial GaAs thermal neutron detectors

    CERN Document Server

    Gersch, H K; Simpson, P A

    2002-01-01

    High-purity epitaxial GaAs sup 1 sup 0 B-coated thermal neutron detectors advantageously operate at room temperature without externally applied voltage. Sample detectors were systematically irradiated at fixed grid locations near the core of a 2 MW research reactor to determine their operational neutron dose threshold. Reactor pool locations were assigned so that fast and thermal neutron fluxes to the devices were similar. Neutron fluences ranged between 10 sup 1 sup 1 and 10 sup 1 sup 4 n/cm sup 2. GaAs detectors were exposed to exponential fluences of base ten. Ten detector designs were irradiated and studied, differentiated between p-i-n diodes and Schottky barrier diodes. The irradiated sup 1 sup 0 B-coated detectors were tested for neutron detection sensitivity in a thermalized neutron beam. Little damage was observed for detectors irradiated at neutron fluences of 10 sup 1 sup 2 n/cm sup 2 and below, but signals noticeably degraded at fluences of 10 sup 1 sup 3 n/cm sup 2. Catastrophic damage was appare...

  12. Neutron flux uncertainty and covariances for spectrum adjustment and estimation of WWER-1000 pressure vessel fluences

    International Nuclear Information System (INIS)

    Boehmer, Bertram

    2000-01-01

    Results of estimation of the covariance matrix of the neutron spectrum in the WWER-1000 reactor cavity and pressure vessel positions are presented. Two-dimensional calculations with the discrete ordinates transport code DORT in r-theta and r-z-geometry used to determine the neutron group spectrum covariances including gross-correlations between interesting positions. The new Russian ABBN-93 data set and CONSYST code used to supply all transport calculations with group neutron data. All possible sources of uncertainties namely caused by the neutron gross sections, fission sources, geometrical dimensions and material densities considered, whereas the uncertainty of the calculation method was considered negligible in view of the available precision of Monte Carlo simulation used for more precise evaluation of the neutron fluence. (Authors)

  13. Medical radiography with fast neutrons

    International Nuclear Information System (INIS)

    Duehmke, E.

    1980-01-01

    Neutron radiography is important in medicine for two reasons. On the one hand, macroradiographical findings are different from X-ray findings, i.e. new information may be gained on the morphology of humans and animals. On the other hand, there is a direct practical application in the radiotherapy of malignant tumours if one considers the assessment of the growth of malignant processes. Fast neutrons are required for neutron radiographies of biological objects with a diameter of more than 2 cm. In addition sensitive, two-dimensional detectors must be used which are selective for fast neutrons. The book describes the optimisation and sensitisation of a detector using the example of cellulose nitrate foil for fast reactor neutrons. Images of human spinal chords with tumours proved by pathological and anatomical examinations give a better picture of the dimensions of the tumour than comparative X-ray pictures. For examinations of living patients, neutron radiography should be applied only in those tumour-bearing parts of the bodies in which radiation treatment is required for therapeutical purposes anyway. (orig./MG) [de

  14. Fast neutron physics

    International Nuclear Information System (INIS)

    Moura Neto, C. de; Amorim, E.S. do.

    1979-12-01

    Finite systems of small dimensions were investigated in comparison with systems where the diffusion theory is valid with reasonable precision. Elaborated methods were introduced for the study of small systems, based on different approximations of the neutron transport equation. Experimental data, obtained from the literature, were compared with values by the ANISN-DLC/2D system. (Author) [pt

  15. Thickness optimization of various moderator materials for maximization of thermal neutron fluence

    International Nuclear Information System (INIS)

    Dhang, Prosenjit; Verma, Rishi; Shyam, Anurag

    2015-01-01

    Plasma focus device is widely being used as pulsed neutron source for variety of applications. Measurements of neutron yield by largely preferred Helium-3 proportional counter and Silver activation counter are mainly sensitive to thermal neutrons and are typically used with a neutron moderator. Thermalization of neutron is based on scattering reaction and hydrogenous materials are the best thermalizing medium. The efficiency of aforementioned neutron detectors is considerably affected by physical and geometrical properties of thermalizing medium i.e. moderator material, its thickness and shape. In view of the same, simulations have been performed to explore the effective utilization of Polyethylene, Perspex and Light water as moderating mediums for cylindrical and spherical geometry. In this study, estimated thermal fluence value up to 0.5 eV has been considered as the benchmark factor for comparing efficient thermalization by specific material, its thickness and shape. In either of the shapes being cylindrical or spherical, use of Polyethylene as moderating medium has resulted in minimum optimum thickness along with highest thermal fluence. (author)

  16. Neutron fluence measurement in the cavity of Balakovo nuclear power plant, unit 3

    International Nuclear Information System (INIS)

    Voorbraak, W.P.; Baard, J.H.; Paardekooper, A.; Nolthenius, H.J.

    1996-12-01

    An international benchmark exercise has been organized by the Russian GOSATOMNADZOR. The aim was to reduce the uncertainty of fluence measurements in Nuclear Power Plants in particular VVER-1000 reactors. The benchmark was set up in the cavity of the Balakovo NPP 3. Eight institutes were involved. This report presents the results obtained by ECN. From this report, it can be concluded that the results of the relative large monitor set (13 different reaction rates with overlapping response regions) point to possible imperfections in the calculated neutron spectra. However the experimental information is not powerful enough to reduce the uncertainty of the neutron fluence rate especially in the energy region between 0.1 and 0.5 MeV below 50 percent. (orig.)

  17. Dosimetry of fast neutrons

    International Nuclear Information System (INIS)

    Jahr, R.

    1975-03-01

    Following an explanation of the physical fundamentals of neutron dosimetry, the special needs in medicine and biology are gone into. It is shown that the dose equivalent used in radiation protection simplifies in an undue manner the complicated dependence of the biological effects. The reason for this is the fact that the RBE for heavy recoil nuclei, amongst others, depends on the energy and sort of particle, whereas it is approximately equal to one for electrons independent of the energy. It is thus necessary in the fields of biology and medicine to have additional information on energy spectra of the neutrons as well as of all charged secondary particles as a function of the position in the phantom. These are obtained partly by calculation and partly by special dosemeters. The accuracy achieved so far is 5%. (ORU/LH) [de

  18. Fast neutron activation analysis

    International Nuclear Information System (INIS)

    Pepelnik, R.

    1986-01-01

    Since 1981 numerous 14 MeV neutron activation analyses were performed at Korona. On the basis of that work the advantages of this analysis technique and therewith obtained results are compared with other analytical methods. The procedure of activation analysis, the characteristics of Korona, some analytical investigations in environmental research and material physics, as well as sources of systematic errors in trace analysis are described. (orig.) [de

  19. Effect of high fluence neutron irradiation on transport properties of thermoelectrics

    Science.gov (United States)

    Wang, H.; Leonard, K. J.

    2017-07-01

    Thermoelectric materials were subjected to high fluence neutron irradiation in order to understand the effect of radiation damage on transport properties. This study is relevant to the NASA Radioisotope Thermoelectric Generator (RTG) program in which thermoelectric elements are exposed to radiation over a long period of time in space missions. Selected n-type and p-type bismuth telluride materials were irradiated at the High Flux Isotope Reactor with a neutron fluence of 1.3 × 1018 n/cm2 (E > 0.1 MeV). The increase in the Seebeck coefficient in the n-type material was partially off-set by an increase in electrical resistivity, making the power factor higher at lower temperatures. For the p-type materials, although the Seebeck coefficient was not affected by irradiation, electrical resistivity decreased slightly. The figure of merit, zT, showed a clear drop in the 300-400 K range for the p-type material and an increase for the n-type material. Considering that the p-type and n-type materials are connected in series in a module, the overall irradiation damages at the device level were limited. These results, at neutron fluences exceeding a typical space mission, are significant to ensure that the radiation damage to thermoelectrics does not affect the performance of RTGs.

  20. Standard Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 The purpose of this test method is to define a general procedure for determining an unknown thermal-neutron fluence rate by neutron activation techniques. It is not practicable to describe completely a technique applicable to the large number of experimental situations that require the measurement of a thermal-neutron fluence rate. Therefore, this method is presented so that the user may adapt to his particular situation the fundamental procedures of the following techniques. 1.1.1 Radiometric counting technique using pure cobalt, pure gold, pure indium, cobalt-aluminum, alloy, gold-aluminum alloy, or indium-aluminum alloy. 1.1.2 Standard comparison technique using pure gold, or gold-aluminum alloy, and 1.1.3 Secondary standard comparison techniques using pure indium, indium-aluminum alloy, pure dysprosium, or dysprosium-aluminum alloy. 1.2 The techniques presented are limited to measurements at room temperatures. However, special problems when making thermal-neutron fluence rate measurements in high-...

  1. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Niobium

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method describes procedures for measuring reaction rates by the activation reaction 93Nb(n,n′)93mNb. 1.2 This activation reaction is useful for monitoring neutrons with energies above approximately 0.5 MeV and for irradiation times up to about 30 years. 1.3 With suitable techniques, fast-neutron reaction rates for neutrons with energy distribution similar to fission neutrons can be determined in fast-neutron fluences above about 1016cm−2. In the presence of high thermal-neutron fluence rates (>1012cm−2·s−1), the transmutation of 93mNb due to neutron capture should be investigated. In the presence of high-energy neutron spectra such as are associated with fusion and spallation sources, the transmutation of 93mNb by reactions such as (n,2n) may occur and should be investigated. 1.4 Procedures for other fast-neutron monitors are referenced in Practice E 261. 1.5 Fast-neutron fluence rates can be determined from the reaction rates provided that the appropriate cross section information ...

  2. Calibration of a He accumulation fluence monitor for fast reactor dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Chikara [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-03-01

    The helium accumulation fluence monitor (HAFM) has been developed for a fast reactor dosimetry. The HAFM measurement system was calibrated using He gas and He implanted samples and the measurement accuracy was confirmed to be less than 5%. Based on the preliminary irradiation test in JOYO, the measured He in the {sup 10}B type HAFM agreed well with the calculated values using the JENDL-3.2 library. (author)

  3. Lifetime Neutron Fluence Analysis of the Ringhals Unit 1 Boiling Water Reactor

    Directory of Open Access Journals (Sweden)

    Kulesza Joel A.

    2016-01-01

    Full Text Available This paper describes a neutron fluence assessment considering the entire commercial operating history (35 cycles or ∼ 25 effective full power years of the Ringhals Unit 1 reactor pressure vessel beltline region. In this assessment, neutron (E >1.0 MeV fluence and iron atom displacement distributions were calculated on the moderator tank and reactor pressure vessel structures. To validate those calculations, five in-vessel surveillance chain dosimetry sets were evaluated as well as material samples taken from the upper core grid and wide range neutron monitor tubes to act as a form of retrospective dosimetry. During the analysis, it was recognized that delays in characterizing the retrospective dosimetry samples reduced the amount of reactions available to be counted and complicated the material composition determination. However, the comparisons between the surveillance chain dosimetry measurements (M and calculated (C results show similar and consistent results with the linear average M/C ratio of 1.13 which is in good agreement with the resultant least squares best estimate (BE/C ratios of 1.10 for both neutron (E >1.0 MeV flux and iron atom displacement rate.

  4. RAMA Methodology for the Calculation of Neutron Fluence; Metodologia RAMA para el Calculo de la Fluencia Neutronica

    Energy Technology Data Exchange (ETDEWEB)

    Villescas, G.; Corchon, F.

    2013-07-01

    he neutron fluence plays an important role in the study of the structural integrity of the reactor vessel after a certain time of neutron irradiation. The NRC defined in the Regulatory Guide 1.190, the way must be estimated neutron fluence, including uncertainty analysis of the validation process (creep uncertainty is ? 20%). TRANSWARE Enterprises Inc. developed a methodology for calculating the neutron flux, 1,190 based guide, known as RAMA. Uncertainty values obtained with this methodology, for about 18 vessels, are less than 10%.

  5. Flux effect on neutron irradiation embrittlement of reactor pressure vessel steels irradiated to high fluences

    International Nuclear Information System (INIS)

    Soneda, N.; Dohi, K.; Nishida, K.; Nomoto, A.; Iwasaki, M.; Tsuno, S.; Akiyama, T.; Watanabe, S.; Ohta, T.

    2011-01-01

    Neutron irradiation embrittlement of reactor pressure vessel (RPV) steels is of great concern for the long term operation of light water reactors. In particular, the embrittlement of the RPV steels of pressurized water reactors (PWRs) at very high fluences beyond 6*10 19 n/cm 2 , E > 1 MeV, needs to be understood in more depth because materials irradiated in material test reactors (MTRs) to such high fluences show larger shifts than predicted by current embrittlement correlation equations available worldwide. The primary difference between the irradiation conditions of MTRs and surveillance capsules is the neutron flux. The neutron flux of MTR is typically more than one order of magnitude higher than that of surveillance capsule, but it is not necessarily clear if this difference in neutron flux causes difference in mechanical properties of RPV. In this paper, we perform direct comparison, in terms of mechanical property and microstructure, between the materials irradiated in surveillance capsules and MTRs to clarify the effect of flux at very high fluences and fluxes. We irradiate the archive materials of some of the commercial reactors in Japan in the MTR, LVR-15, of NRI Rez, Czech Republic. Charpy impact test results of the MTR-irradiated materials are compared with the data from surveillance tests. The comparison of the results of microstructural analyses by means of atom probe tomography is also described to demonstrate the similarity / differences in surveillance and MTR-irradiated materials in terms of solute atom behavior. It appears that high Cu material irradiated in a MTR presents larger shifts than those of surveillance data, while low Cu materials present similar embrittlement. The microstructural changes caused by MTR irradiation and surveillance irradiation are clearly different

  6. Fluence measurement at the neutron time of flight experiment at CERN

    CERN Document Server

    Weiss, Christina; Jericha, Erwin

    At the neutron time of flight facility n_TOF at CERN a new spallation target was installed in 2008. In 2008 and 2009 the commissioning of the new target took place. During the summer 2009 a fission chamber of the Physikalisch Technische Bundesanstalt (PTB) Braunschweig was used for the neutron fluence measurement. The evaluation of the data recorded with this detector is the primary topic of this thesis. Additionally a neutron transmission experiment with air has been performed at the TRIGA Mark II reactor of the Atomic Institute of the Austrian Universities (ATI). The experiment was implemented to clarify a question about the scattering cross section of molecular gas which could not be answered clearly via the literature. This problem came up during the evaluations for n_TOF.

  7. Measurement of thermal neutron fluence with CaSO4 thermoluminescent phosphors

    International Nuclear Information System (INIS)

    Liu Jinhua; Su Jingling; Wei Zemin

    1984-01-01

    During neutron irradiation, some TL phosphors were activated. After leaving the irradiation field the TL phosphor produced self-irradiation. The TL output of self-dose was only related to the original neutron fluence and independent of the γ-radiation. Several CaSO 4 TL phosphors were made. They were CaSO 4 :Dy, CaSO 4 :Dy-Teflon, CaSO 4 :Dy mixed with Dy 2 O 3 , CaSO 4 :Mn mixed with Dy 2 O 3 . The linearity, and lower detection limits of these TL phosphors were measured. The thermal neutron response of CaSO 4 :Mn mixed with Dy 2 O 3 was 64 R/(10 10 cm -2 ) and the lower detection limit was 1.3x10 5 cm -2

  8. Validation of neutron-transport calculations in benchmark facilities for improved damage-fluence predictions

    International Nuclear Information System (INIS)

    Williams, M.L.; Stallmann, F.W.; Maerker, R.E.; Kam, F.B.K.

    1983-01-01

    An accurate determination of damage fluence accumulated by reactor pressure vessels (RPV) as a function of time is essential in order to evaluate the vessel integrity for both pressurized thermal shock (PTS) transients and end-of-life considerations. The desired accuracy for neutron exposure parameters such as displacements per atom or fluence (E > 1 MeV) is of the order of 20 to 30%. However, these types of accuracies can only be obtained realistically by validation of nuclear data and calculational methods in benchmark facilities. The purposes of this paper are to review the needs and requirements for benchmark experiments, to discuss the status of current benchmark experiments, to summarize results and conclusions obtained so far, and to suggest areas where further benchmarking is needed

  9. Time changes of vertical profile of neutron fluence rate in LVR-15 reactor

    International Nuclear Information System (INIS)

    Viererbl, L.; Stehno, J.; Erben, O.; Lahodova, Z.; Marek, M.

    2003-01-01

    The LVR-15 reactor is a light water research type reactor, which is situated, in Nuclear Research Institute, Rez near Prague. The reactor is used as a multipurpose facility. For some experiments and material productions, e.g. for homogeneity of silicon resistance in production of radiation doped silicon, the time changes of vertical profile of neutron fluence rate are particularly important. The assembly used for silicon irradiation has two self-powered neutron detectors installed in a vertical irradiation channel in LVR-15 reactor. Vertical profile of thermal neutron fluence rate was automatically scanned during reactor operation. The results of measurements made in 2002 and 2003 with these detectors are presented. A set of vertical profile measurements was made during two 21-days reactor cycles. During the cycle the vertical profile slightly changes both in the position of its maximum and in the shape. The time dependences of the position of profile maximum and the profile width at half maximum during the cycle are given. (author)

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

    International Nuclear Information System (INIS)

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

    1991-01-01

    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 ∼.05 V/rad responsivity with ≥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 5 to 10 7 n/cm 2 range indicate smearing over ∼1 to 10% of CCD array with charge per pixel ranging between noise and saturation levels

  11. Calculation of neutron fluence-to-dose conversion factors for extremities

    International Nuclear Information System (INIS)

    Stewart, R.D.; Harty, R.; McDonald, J.C.; Tanner, J.E.

    1993-04-01

    The Pacific Northwest Laboratory is developing a standard for the performance testing of personnel extremity dosimeters for the US Department of Energy. Part of this effort requires the calculation of neutron fluence-to-dose conversion factors for finger and wrist extremities. This study focuses on conversion factors for two types of extremity models: namely the polymethyl methacrylate (PMMA) phantom (as specified in the draft standard for performance testing of extremity dosimeters) and more realistic extremity models composed of tissue-and-bone. Calculations for each type of model are based on both bare and D 2 O-moderated 252 Cf sources. The results are then tabulated and compared with whole-body conversion factors. More appropriate energy-averaged quality factors for the extremity models have also been computed from the neutron fluence in 50 equally spaced energy bins with energies from 2.53 x 10 -8 to 15 MeV. Tabulated results show that conversion factors for both types of extremity phantom are 15 to 30% lower than the corresponcung whole-body phantom conversion factors for 252 Cf neutron sources. This difference in extremity and whole-body conversion factors is attributable to the proportionally smaller amount of back-scattering that occurs in the extremity phantoms compared with whole-body phantoms

  12. Fast neutron irradiation and thermal properties of doped nonstoichiometric lithium potassium sulphate crystals

    International Nuclear Information System (INIS)

    Kassem, M.E.; Gomaa, N.G.; El-Khatib, A.M.

    1990-01-01

    The influence of point defects introduced by fast neutron irradiations with neutron fluences up to 1.08 x 10 10 n/cm 2 on the thermal properties of pure and doped Li 1.4 K 0.6 SO 4 single crystals are studied in the vicinity of high temperature phase transition at 705 K. The temperature dependence of specific heat is found to be shifted towards lower temperature with the increase of neutron fluence, and can be affected by the presence of Cu 2+ dopant. The change in the value of the specific heat can be attributed to the presence of internal strain generated inside the crystal. (author)

  13. Neutron fluence in a 18 MeV Electron Accelerator for Therapy

    International Nuclear Information System (INIS)

    Paredes G, L.C.

    2001-01-01

    An investigation was made on the theoretical fundamentals for the determination of the neutron fluence in a linear electron accelerator for radiotherapy applications and the limit values of leakage neutron radiation established by guidelines and standards in radiation protection for these type of accelerators. This investigation includes the following parts: a) Exhaustive bibliographical review on the topics mentioned above, in order to combine and to update the necessary basic information to facilitate the understanding of this subject; b) Analysis of the accelerator operation and identification of its main components, specially in the accelerator head; c) Study of different types of targets and its materials for the Bremsstrahlung production which is based on the electron initial energy, the thickness of the target, and its angular distribution and energy, which influences in the neutron generation by means of the photonuclear and electro disintegration reactions; d) Analysis of the neutron yield based on the target type and its thickness, the energy of electrons and photons; e) Analysis of the neutron energy spectra generated in the accelerator head, inside and outside the treatment room; f) Study of the dosimetry fundamentals for neutron and photon mixed fields, the dosimeter selection criteria and standards applied for these applications, specially the Panasonic U D-809 thermoluminescent dosemeter and C R-39 nuclear track dosimeter; g) Theoretical calculation of the neutron yield using a simplified geometric model for the accelerator head with spherical cell, which considers the target, primary collimator, flattener filter, movable collimators and the head shielding as the main components for radiation production. The cases with W and Pb shielding for closed movable collimators and an irradiation field of 20 x 20 cm 2 were analyzed and, h) Experimental evaluation of the leakage neutron radiation from the patient and head planes, observing that the accelerator

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

    International Nuclear Information System (INIS)

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

    1991-01-01

    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 (16-MeV endpoint) are utilized to calibrate the devices as radiometric imaging sensors capable of distinguishing between the two types of ionizing radiation. Measurements indicate ∼0.5 V/rad responsivity with ≥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 5 to 10 7 n/cm 2 range indicate smearing over ∼1 to 10% of CCD array with charge per pixel ranging between noise and saturation levels. 9 refs., 12 figs., 4 tabs

  15. Experiments for neutron fluence assessment on WWER-440 and WWER-1000 pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Ilieva, K; Apostolov, T; Penev, I; Trifonov, A; Taskaev, E; Belousov, S; Antonov, S; Petrova, T; Stoeva, L [Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. za Yadrena Izsledvaniya i Yadrena Energetika; Boyadzhiev, Z; Nelov, N; Tsocheva, V; Andreeva, I; Lilkov, B; Velichkov, V; Monev, M [Kombinat Atomna Energetika, Kozloduj (Bulgaria)

    1996-12-31

    The activity of shavings sampled out from the expected maximum embrittlement location (weld 4) on the inner pressure vessel wall of the Kozloduy-1 Unit after the 14-th cycle has been measured. The experiment was carried out along the INEI channel using Fe and Cu string and foil detectors. The axial neutron flux distribution at the Unit 3 after the cycle 11 has been measured and compared to the calculated values. The calculations of the expected activities have been carried out taking into account the local power distribution. A comparison between measured and calculated values using ACTIVAT code is made. It shows a discrepancy of about 20%. It is recommended to carry out ex-vessel neutron fluence measurements using a rack device with activation detectors in order to verify the calculation results. 8 refs., 3 figs., 2 tabs.

  16. Fast Radio Bursts’ Recipes for the Distributions of Dispersion Measures, Flux Densities, and Fluences

    Science.gov (United States)

    Niino, Yuu

    2018-05-01

    We investigate how the statistical properties of dispersion measure (DM) and apparent flux density/fluence of (nonrepeating) fast radio bursts (FRBs) are determined by unknown cosmic rate density history [ρ FRB(z)] and luminosity function (LF) of the transient events. We predict the distributions of DMs, flux densities, and fluences of FRBs taking account of the variation of the receiver efficiency within its beam, using analytical models of ρ FRB(z) and LF. Comparing the predictions with the observations, we show that the cumulative distribution of apparent fluences suggests that FRBs originate at cosmological distances and ρ FRB increases with redshift resembling the cosmic star formation history (CSFH). We also show that an LF model with a bright-end cutoff at log10 L ν (erg s‑1 Hz‑1) ∼ 34 are favored to reproduce the observed DM distribution if ρ FRB(z) ∝ CSFH, although the statistical significance of the constraints obtained with the current size of the observed sample is not high. Finally, we find that the correlation between DM and flux density of FRBs is potentially a powerful tool to distinguish whether FRBs are at cosmological distances or in the local universe more robustly with future observations.

  17. Neutron fluence determination for operation effectiveness assessment and prediction of WWER pressure vessel lifetime at the Kozloduy NPP

    Energy Technology Data Exchange (ETDEWEB)

    Apostolov, T; Ilieva, K; Belousov, S; Petrova, T; Antonov, S; Ivanov, K; Prodanova, R; Penev, I; Taskaev, E [Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. za Yadrena Izsledvaniya i Yadrena Energetika; Ivanov, I; Tsokov, P; Nelov, N; Lilkov, B; Tsocheva, V; Monev, M; Velichkov, V; Kharalampieva, Ts [Kombinat Atomna Energetika, Kozloduj (Bulgaria)

    1996-12-31

    Embrittlement processes in reactor pressure vessel (RPV) metal have been investigated by neutron dosimetry. A software package for fluence calculations has been developed and used for evaluation of the accumulated neutron fluence, the critical temperature of radiation embrittlement and the RPV lifetime. A digital reactivity meter DR-8 has been introduced for continuous neutron fluence monitoring. Estimates of the neutron fluence and the radiation state of all 6 units of the Kozloduy NPP are presented. The Unit 4 RPV is in the best state regarding metal embrittlement, while the Units 2 and 3 can be safely operated up to the end of their design lifetime only using dummy cassettes. The neutron fluence accumulation in the Unit 1 RPV is quite big and can not be reduced with annealing. Activity measurements of the Unit 1 internal wall shavings are made after the 14-th cycle which show a good agreement with calculated values (1.10{sup 5} Bq/g). The critical embrittlement temperature of the Units 1 - 4 is estimated as a function of the working cycles. 11 figs., 1 tab.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-22

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

  19. Application of low-cost Gallium Arsenide light-emitting-diodes as kerma dosemeter and fluence monitor for high-energy neutrons

    International Nuclear Information System (INIS)

    Mukherjee, B.; Simrock, S.; Khachan, J.; Rybka, D.; Romaniuk, R.

    2007-01-01

    Displacement damage (DD) caused by fast neutrons in unbiased Gallium Arsenide (GaAs) light emitting diodes (LED) resulted in a reduction of the light output. On the other hand, a similar type of LED irradiated with gamma rays from a 60 Co source up to a dose level in excess of 1.0 kGy (1.0 x 10 5 rad) was found to show no significant drop of the light emission. This phenomenon was used to develop a low cost passive fluence monitor and kinetic energy released per unit mass dosemeter for accelerator-produced neutrons. These LED-dosemeters were used to assess the integrated fluence of photoneutrons, which were contaminated with a strong Bremsstrahlung gamma-background generated by the 730 MeV superconducting electron linac driving the free electron laser in Hamburg (FLASH) at Deutsches Elektronen-Synchrotron. The applications of GaAs LED as a routine neutron fluence monitor and DD precursor for the electronic components located in high-energy accelerator environment are highlighted. (authors)

  20. [Fast neutron cross section measurements

    International Nuclear Information System (INIS)

    Knoll, G.F.

    1992-01-01

    From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are ''clean'' and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its ''data production'' phase

  1. Fast neutron detection by means of an organic solid state track detector

    International Nuclear Information System (INIS)

    Doerschel, B.; Streubel, G.

    1980-01-01

    Solid state track detectors consisting of cellulose triacetate foils are appropriate for measuring the fast neutron fluence without applying external radiators. Detector sensitivity has been determined as a function of neutron energy by performing irradiations with various neutron sources and monoenergetic neutrons of different energies. A comparison with theoretical results given in the literature for a simple model of track recording has shown sufficient agreement. The measuring errors and the influence of spectral changes in the neutron field on detector response are discussed for the studied method of fluence measurement. By means of these errors the measuring range has been determined for well defined irradiation conditions, taking into account spectral changes in the neutron field. (author)

  2. Intermediate and fast neutron absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1987-10-01

    The experimental fuel channel EFC is created as one of the fast neutron fields at the RB reactor. The intermediate and fast neutron spectra in EFC are measured by activation technique. The intermediate and fast neutron absorbed doses are computed on the basis of these experimental results. At the end the obtained doses are compared. (author)

  3. Influence of the number of energy groups on the accuracy of neutron fluence calculations

    International Nuclear Information System (INIS)

    Barz, H.U.; Konheiser, J.

    1999-01-01

    The question how many groups are necessary to obtain all needed integral quantities for the neutron load of pressure vessels and detector positions outside the vessel with sufficient accuracy is of general interest. Until now, there are no systematic investigations on this question. In principle 3-dimensional consideration is required for such neutron load calculations. Therefore, an estimation of the needed number of groups can be of interest to minimize calculation time. One general problem is the P L -approximation of the angular distributions for the transfers between different groups. For elastic scattering this P L -approximation becomes poorer with increasing number of groups. As deterministic methods generally use the P L -approximation they cannot be used for investigations of the errors caused by the group approximation. We have investigated this problem applying group Monte-Carlo but nearly exact representation of this elastic slowing down without P L -approximation. The calculations were directed to assess the neutron fluence of a Russian WWER-1000 reactor. For that a simplified geometrical model of this reactor type has been used. (orig.)

  4. Electrical characterization of 10B doped diamond irradiated with low thermal neutron fluence

    International Nuclear Information System (INIS)

    Reed, M.L.; Reed, M.J.; Jagannadham, K.; Verghese, K.; Bedair, S.M.; El-Masry, N.; Butler, J.E.

    2004-01-01

    A sample of 10 B isotope doped diamond was neutron irradiated to a thermal fluence of 1.3x10 19 neutron cm -2 . The diamond sample was cooled continuously during irradiation in a nuclear reactor. 7 Li is formed by nuclear transmutation reaction from 10 B. Characterization for electrical conductance in the temperature range of 160 K 10 B doped sample and the 10 B doped and irradiated sample. The unirradiated diamond sample showed p-type conductance at higher temperature (T>200 K) and p-type surface conductance at lower temperature (T 7 Li that is formed by nuclear transmutation reaction from 10 B atoms. Also, compensation of n-type carriers from 7 Li by p-type carriers from 10 B is used to interpret the conductance above 400 K. A low concentration of radiation induced defects, absence of defect complexes, and the low activation energy of n-type 7 Li are thought responsible for the observed variation of conductance in the irradiated diamond. The present results illustrate that neutron transmutation from 10 B doped diamond is a useful method to achieve n-type conductivity in diamond

  5. EFFECTS OF IRRADIATION ON THERMAL CONDUCTIVITY OF ALLOY 690 AT LOW NEUTRON FLUENCE

    Directory of Open Access Journals (Sweden)

    WOO SEOG RYU

    2013-04-01

    Full Text Available Alloy 690 has been selected as a steam generator tubing material for SMART owing to a near immunity to primary water stress corrosion cracking. The steam generators of SMART are faced with a neutron flux due to the integrated arrangement inside a reactor vessel, and thus it is important to know the irradiation effects of the thermal conductivity of Alloy 690. Alloy 690 was irradiated at HANARO to fluences of (0.7−28 × 1019n/cm2 (E>0.1MeV at 250°C, and its thermal conductivity was measured using the laser-flash equipment in the IMEF. The thermal conductivity of Alloy 690 was dependent on temperature, and it was a good fit to the Smith-Palmer equation, which modified the Wiedemann-Franz law. The irradiation at 250°C did not degrade the thermal conductivity of Alloy 690, and even showed a small increase (1% at fluences of (0.7∼28 × 1019n/cm2 (E>0.1MeV.

  6. The influence of fast neutron irradiation on the noise properties of silicon surface-barrier detectors

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.

    1988-01-01

    The susceptibility to the fast neutron irradiation of silicon surface-barrier detectors has been investigated. It was shown that the 1/f-noise decreases substantially with increasing fluence in the range from 10 10 n/cm 2 to 10 11 n/cm 2 . The deterioration of the detector performance is caused mainly by the positively-charged defects induced by the radiation. The critical value of the neutron fluence, at which the detector performance begins to be worsened was also determined. 5 refs., 5 figs. (author)

  7. Fast neutron activation analysis in metallurgy

    International Nuclear Information System (INIS)

    Sterlinski, S.

    1981-01-01

    Article discusses the usage of a 14 MeV neutron generator for producing fast neutrons of different energies and intensities. A complete instrumental set-up for the neutron activation analysis (NAA) is given. In metallurgy the device is mainly used in the determination of oxygen and silicon in steel and non-ferrous metal, including different alloys

  8. A silicon diode for fast neutron dosimetry

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    The effect of fast neutrons on both animate and inanimate objects, including human beings, can be extremely serious and cumulative. There is thus a need for a small, simple and cheap component which will provide a permanent or semi-permanent record of the accumulated fast neutron dose

  9. Shield design for next-generation, low-neutron-fluence, superconducting tokamaks

    International Nuclear Information System (INIS)

    Lee, V.D.; Gohar, Y.

    1985-01-01

    A shield design using stainless steel (SST), water, boron carbide, lead, and concrete materials was developed for the next-generation tokamak device with superconducting toroidal field (TF) coils and low neutron fluence. A device such as the Tokamak Fusion Core Experiment (TFCX) is representative of the tokamak design which could use this shield design. The unique feature of this reference design is that a majority of the bulk steel in the shield is in the form of spherical balls with two small, flat spots. The balls are purchased from ball-bearing manufacturers and are added as bulk shielding to the void areas of builtup, structural steel shells which form the torus cavity of the plasma chamber. This paper describes the design configuration of the shielding components

  10. Shield design for next-generation, low-neutron-fluence, superconducting tokamaks

    International Nuclear Information System (INIS)

    Lee, V.D.; Gohar, Y.

    1985-01-01

    A shield design using stainless steel (SST), water, boron carbide, lead, and concrete materials was developed for the next-generation tokamak device with superconducting toroidal field (TF) coils and low neutron fluence. A device such as the Tokamak Fusion Core Experiment (TFCX) is representative of the tokamak design which could use this shield design. The unique feature of this reference design is that a majority of the bulk steel in the shield is in the form of spherical balls with two small, flat spots. The balls are purchased from ball-bearing manufacturers and are added as bulk shielding to the void areas of built-up, structural steel shells which form the torus cavity of the plasma chamber. This paper describes the design configuration of the shielding components

  11. Tritium release kinetics in lithium orthosilicate ceramic pebbles irradiated with low thermal-neutron fluence

    International Nuclear Information System (INIS)

    Xiao, Chengjian; Gao, Xiaoling; Kobayashi, Makoto; Kawasaki, Kiyotaka; Uchimura, Hiromichi; Toda, Kensuke; Kang, Chunmei; Chen, Xiaojun; Wang, Heyi; Peng, Shuming; Wang, Xiaolin; Oya, Yasuhisa; Okuno, Kenji

    2013-01-01

    Tritium release kinetics in lithium orthosilicate (Li 4 SiO 4 ) ceramic pebbles irradiated with low thermal-neutron fluence was studied by out-of-pile annealing experiments. It was found that the tritium produced in Li 4 SiO 4 pebbles was mainly released as tritiated water vapor (HTO). The apparent desorption activation energy of tritium on the pebble surface was consistent with the diffusion activation energy of tritium in the crystal grains, indicating that tritium release was mainly controlled by diffusion process. The diffusion coefficients of tritium in the crystal grains at temperatures ranging from 450 K to 600 K were obtained by isothermal annealing tests, and the Arrhenius relation was determined to be D = 1 × 10 −7.0 exp (−40.3 × 10 3 /RT) cm 2 s −1

  12. Tritium release kinetics in lithium orthosilicate ceramic pebbles irradiated with low thermal-neutron fluence

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Chengjian; Gao, Xiaoling [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Box 919-214, Mian Yang 621900 (China); Kobayashi, Makoto; Kawasaki, Kiyotaka; Uchimura, Hiromichi; Toda, Kensuke [China Academy of Engineering Physics, Box 919-1, Mian Yang 621900 (China); Kang, Chunmei; Chen, Xiaojun; Wang, Heyi; Peng, Shuming [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Box 919-214, Mian Yang 621900 (China); Wang, Xiaolin, E-mail: xlwang@caep.ac.cn [China Academy of Engineering Physics, Box 919-1, Mian Yang 621900 (China); Oya, Yasuhisa; Okuno, Kenji [Radiochemistry Research Laboratory, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka 422-8529 (Japan)

    2013-07-15

    Tritium release kinetics in lithium orthosilicate (Li{sub 4}SiO{sub 4}) ceramic pebbles irradiated with low thermal-neutron fluence was studied by out-of-pile annealing experiments. It was found that the tritium produced in Li{sub 4}SiO{sub 4} pebbles was mainly released as tritiated water vapor (HTO). The apparent desorption activation energy of tritium on the pebble surface was consistent with the diffusion activation energy of tritium in the crystal grains, indicating that tritium release was mainly controlled by diffusion process. The diffusion coefficients of tritium in the crystal grains at temperatures ranging from 450 K to 600 K were obtained by isothermal annealing tests, and the Arrhenius relation was determined to be D = 1 × 10{sup −7.0} exp (−40.3 × 10{sup 3}/RT) cm{sup 2} s{sup −1}.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  14. General remarks on fast neutron reactor physics

    International Nuclear Information System (INIS)

    Barre, J.Y.

    1980-01-01

    The main aspects of fast reactor physics, presented in these lecture notes, are restricted to LMFBR's. The emphasis is placed on the core neutronic balance and the burn-up problems. After a brief description of the power reactor main components and of the fast reactor chronology, the fundamental parameters of the one-group neutronic balance are briefly reviewed. Then the neutronic burn-up problems related to the Pu production and to the doubling time are considered

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Measurement and evaluation of fast neutron flux of CT and OR5 irradiation hole in HANARO

    International Nuclear Information System (INIS)

    Yang, Seong Woo; Choo, Kee Nam; Lee, Seung-Kyu; Kim, Yong Kyun

    2012-01-01

    The irradiation test has been conducted to evaluate the irradiation performance of many materials by a material capsule at HANARO. Since the fast neutron fluence above 1 MeV is important for the irradiation test of material, it must be measured and evaluated exactly at each irradiation hole. Therefore, a fast neutron flux was measured and evaluated by a 09M-02K capsule irradiated in an OR5 irradiation hole and a 10M-01K capsule irradiated in a CT irradiation hole. Fe, Ni, and Ti wires as the fluence monitor were used for the detection of fast neutron flux. Before the irradiation test, the neutron flux and spectrum was calculated for each irradiation hole using an MCNP code. After the irradiation test, the activity of the fluence monitor was measured by an HPGe detector and the reaction rate was calculated. For the OR5 irradiation hole, the radial difference of the fast neutron flux was observed from a calculated data due to the OR5 irradiation hole being located outside the core. Furthermore, a control absorber rod was withdrawn from the core as the increase of the irradiation time at the same irradiation cycle, so the distribution of neutron flux was changed from the beginning to the end of the cycle. These effects were considered to evaluate the fast neutron flux. Neutron spectrums of the CT and OR5 irradiation hole were adjusted by the measured data. The fluxes of a fast neutron above 1 MeV were compared with calculated and measured value. Although the maximum difference was shown at 18.48%, most of the results showed good agreement. (author)

  17. Determination of the neutron fluence in the welding of the 'Core shroud' of the BWR reactor core

    International Nuclear Information System (INIS)

    Lucatero, M.A.; Xolocostli M, J.V.; Gomez T, A.M.; Palacios H, J.C.

    2006-01-01

    With the purpose of defining the inspection frequency, in function of the embrittlement of the materials that compose the welding of the 'Core Shroud' or encircling of the core of a BWR type reactor, is necessary to know the neutron fluence received for this welding. In the work the calculated values of neutron fluence accumulated maxim (E > 1 MeV) during the first 8 operation cycles of the reactor are presented. The calculations were carried out according to the NRC Regulatory Guide 1.190, making use of the DORT code, which solves the transport equation in discreet ordinate in two dimensions (xy, rΘ, and rz). The results in 3D were obtained applying the Synthesis method according to the guide before mentioned. Results are presented for the horizontal welding H3, H4, and H5, showing the corresponding curves to the fluence accumulated to the cycle 8 and a projection for the cycle 14 is presented. (Author)

  18. Thermal and fast neutron dosimetry using artificial single crystal diamond detectors

    International Nuclear Information System (INIS)

    Angelone, M.; Pillon, M.; Prestopino, G.; Marinelli, Marco; Milani, E.; Verona, C.; Verona-Rinati, G.; Aielli, G.; Cardarelli, R.; Santonico, R.; Bedogni, R.; Esposito, A.

    2011-01-01

    In this work we propose the artificial Single Crystal Diamond (SCD) detector covered with a thin layer (0.5 μm/4 μm) of 6 LiF as a simultaneous thermal and fast neutron fluence monitor. Some interesting properties of the diamond response versus the neutron energy are evidenced thanks to Monte Carlo simulation using the MCNPX code which allows to propose the diamond detector also as an ambient dose equivalent (H∗(10)) monitor (REM counter).

  19. Status of the design concepts for a high fluence fast pulse reactor (HFFPR)

    International Nuclear Information System (INIS)

    Philbin, J.S.; Nelson, W.E.; Rosenstroch, B.

    1978-10-01

    The report describes progress that has been made on the design of a High Fluence Fast Pulse Reactor (HFFPR) through the end of calendar year 1977. The purpose of this study is to present design concepts for a test reactor capable of accommodating large scale reactor safety tests. These concepts for reactor safety tests are adaptations of reactor concepts developed earlier for DOE/OMA for the conduct of weapon effects tests. The preferred driver core uses fuel similar to that developed for Sandia's ACPR upgrade. It is a BeO/UO 2 fuel that is gas cooled and has a high volumetric heat capacity. The present version of the design can drive large (217) pin bundles of prototypically enriched mixed oxide fuel well beyond the fuel's boiling point. Applicability to specific reactor safety accident scenarios and subsequent design improvements will be presented in future reports on this subject

  20. Fast neutron dosimetry by means of different solid state nuclear track detectors

    International Nuclear Information System (INIS)

    Spurny, F.; Turek, K.

    1977-01-01

    The comparative study of three different types of fast neutron dosimeters based on solid state nuclear track detectors is presented; the dosimeters studied were: - microscopic soda glass in contact with 232 Th; - polycarbonate Makrofol E; and - cellulose nitrate Kodak LR 115. All detectors were evaluated by visual counting in a microscope. The authors have studied such properties as the background, angular as well as energetical dependences of detectors. The results obtained show that all studied detectors are suitable for fast neutron dosimetry; their application depends however on the concrete experimental conditions (neutron spectrum, fluence etc.). Both advantages and disadvantages of each of them are presented. (Auth.)

  1. Fast neutron dosimeter with wide base silicon diode

    International Nuclear Information System (INIS)

    Ma Lu

    1986-01-01

    This paper briefly introduces a wide base silicon diode fast neutron dosimeter with wide measuring range and good energy response to fast neutron. It is suitable to be used to detect fast neutrons in the mixed field of γ-ray, thermal neutrons and fast neutrons

  2. COLLI-PTB, Neutron Fluence Spectra for 3-D Collimator System by Monte-Carlo

    International Nuclear Information System (INIS)

    Schlegel-Bickmann, Dietrich

    1995-01-01

    1 - Description of program or function: For optimizing collimator systems (shieldings) for fast neutrons with energies between 10 KeV and 20 MeV. Only elastic and inelastic neutron scattering processes are involved. Isotropic angular distribution for inelastic scattering in the center of mass system is assumed. 2 - Method of solution: The Monte Carlo method with importance sampling technique, splitting and Russian Roulette is used. The neutron attenuation and scattering kinematics is taken into account. 3 - Restrictions on the complexity of the problem: Energy range from 10 KeV to 20 MeV. For the output spectra any bin width is possible. The output spectra are confined to 40 equidistant channels

  3. Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4; Calculo de coeficientes de fluencia de neutrons para equivalente de dose individual utilizando o GEANT4

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

  4. Fast neutron radiography using photoluminescent imaging plates

    International Nuclear Information System (INIS)

    Rant, J.; Kristof, E.; Balasko, M.; Stade, J.

    1999-01-01

    Fast neutron radiography (FNR) and resonance neutron radiography (RNR) are complementary to the conventional radiography with high energy gamma-rays or brems-strahlung radiation used for the inspection of thick metal objects. In both non-destructive methods, the contrast sensitivity and the penetration power can be improved by using higher energy neutrons. At present direct techniques based either n Solid State Nuclear Track detectors (SSNTDs) or scintillating screens and transfer techniques using activation threshold detectors and radiographic films are applied for the detection of fast neutron images. Rather low detection sensitivity of film and SSNTD based fast neutron imaging methods and also rather poor inherent image contrast of SSNTD pose a problem for FNR in the fast neutron energy region 1-15 MeV interesting for NDT. For more efficient detection of fast neutron images the use of novel highly sensitive photoluminescent imaging plates (IP) in combination with threshold at the KFKI research reactor. The conventional IP produced by FUJI Photo Film Co. for the detection of beta and X-ray radiation were used. The threshold activation detectors were the reactions 115 In(n, n') 115m In, 64 Zn(n,p) 64 Cu, 56 Fe(n, p) 56 Mn, 24 Mg(n, p) 24 Na and 27 Al(n, α) 24 Na. These threshold reactions cover the fast neutron energy region between 0,7 MeV and 12 MeV. Pure, commercially available metals 0,1 mm to 0,25 mm thick made of In, Zn, Fe, Mg and Al were used as converter screens. The very high sensitivity of IP, the linearity of their response over 5 decades of exposure dose and the high dynamic digitalisation latitude enabled fast neutron radiography of image quality comparable to the quality of thermal NR. In our experimental conditions (φ n ∼ 10 8 n/cm 2 s, R Cd ∼ 2) the neutron exposure and IP exposure periods were still practical and comparable to the half life of the corresponding reaction products (half an hour to several hours). Even with the 27 Al(n.α) 24

  5. Some neutronics of innovative subcritical assembly with fast neutron spectrum

    International Nuclear Information System (INIS)

    Kiyavitskaya, H.; Fokov, Yu.; Rutkovskaya, Ch.; Sadovich, S.; Kasuk, D.; Gohar, Y.; Bolshinsky, I.

    2013-01-01

    Conclusion: • New assembly can be used to: • develop the experimental techniques and adapt the existing ones for monitoring the sub-criticality level, neutron spectra measurements, etc; • study the spatial kinetics of sub-critical and critical systems with fast neutron spectra; • measure the transmutation reaction rates of minor-actinides etc

  6. International key comparison of neutron fluence measurements in mono-energetic neutron fields: C.C.R.I.(3)-K10

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; Wang, Z.; Rong, C. [China Institute of Atomic Energy (CIAE), Beijing, People' s Republic of China (China); Lovestam, G.; Plompen, A.; Puglisi, N. [EC-JRC-Institute for Reference Materials and Measurements (IRMM), Geel (Belgium); Gilliam, D.M.; Eisenhauer, C.M.; Nico, J.S.; Dewey, M.S. [National Institute of Standards and Technology (NIST), Gaithersburg (United States); Kudo, K.; Uritani, A.; Harano, H.; Takeda, N. [National Metrology Institute of Japan (NMIJ), Tsukuba (Japan); Thomas, D.J.; Roberts, N.J.; Bennett, A.; Kolkowski, P. [National Physical Laboratory (NPL), Teddington (United Kingdom); Moisseev, N.N.; Kharitonov, I.A. [Mendeleyev Institute for Metrology (VNIIM), St Petersburg (Russian Federation); Guldbakke, S.; Klein, H.; Nolte, R.; Schlegel, D. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany)

    2007-12-15

    C.C.R.I. Section III (neutron measurements) conducted a unique key comparison of neutron fluence measurements in mono-energetic neutron fields. In contrast to former comparisons, here the fluence measurements were performed with the participants' instruments in the same neutron fields at the P.T.B. accelerator facility. Seven laboratories- the C.I.A.E. (China), I.R.M.M. (E.C.), N.M.I.J. (Japan), N.I.S.T. (USA), N.P.L. (UK), P.T.B. (Germany) and the V.N.I.I.M. (Russia)-employed their primary standard reference methods or transfer instruments carefully calibrated against their primary standards, to determine the fluence of 0.144 MeV, 1.2 MeV, 5.0 MeV and 14.8 MeV neutrons and reported calibration coefficients for a selected neutron monitor and each neutron energy with a detailed uncertainty budget for the measurements. The key comparison reference values (K.C.R.V.) were finally evaluated as the weighted mean values of the neutron fluence at 1 m distance from the target in vacuum per neutron monitor count. The uncertainties of each K.C.R.V. amounted to about 1%. The degree of equivalence (D.o.E.), defined as the deviation of the result reported by the laboratories for each energy from the corresponding K.C.R.V., and the associated expanded uncertainty are also reported. The deviations between the results of two laboratories each with the corresponding expanded uncertainties complete the documentation of the degrees of equivalence. (authors)

  7. Clinical application of fast neutrons

    International Nuclear Information System (INIS)

    Battermann, J.J.

    1981-01-01

    The results of treatments and clinical experiments with neutrons (from a medical d+T neutron generator with an output of 10 12 neutrons per second) are reported and discussed. Data on RBE values are presented after single doses and multiple fractions of neutrons and 60 Co-gamma rays on pulmonary metastases. The results of pilot studies on head and neck tumours, brain tumours and pelvic tumours are discussed. The accuracy of the calculated dose is tested with some in-vivo experiments during neutron irradiation of the pelvis. Estimations of RBE values for tumour control, skin damage and intestinal damage after fractionated neutron therapy are dealt with and the results obtained in treatment of sarcomas are discussed. The preliminary results are given of some clinical trials in Amsterdam. Also some data from other centres are reviewed. From these data some remarks about the future of neutron therapy are made. (Auth.)

  8. Use of CPXSD for generation of effective fast multigroup libraries for pressure vessel fluence calculations

    International Nuclear Information System (INIS)

    Alpan, F. Arzu; Haghighat, Alireza

    2008-01-01

    Multigroup (i.e., broad-group) libraries play a significant role in the accuracy of transport calculations. There are several broad-group libraries available for particular applications. For example the 47-neutron (26 fast groups), 20-gamma-group BUGLE libraries are commonly used for light water reactor shielding and pressure vessel dosimetry problems. However, there is no publicly available methodology to construct group structures for a problem and objective of interest. Therefore, we have developed the Contribution and Point-wise Cross-Section Driven (CPXSD) methodology, which constructs effective fine-and broad-group structures. In this paper, we use the CPXSD methodology to construct broad-group structures for fast neutron dosimetry problems. It is demonstrated that the broad-group libraries generated from CPXSD constructed group structures, while only 14 groups (rather than 26 groups) in the fast energy range are in good agreement (similar to 1 %-2 %) with the fine-group library from which they were derived, in reaction rate calculations.

  9. Fast neutron analysis code SAD1

    International Nuclear Information System (INIS)

    Jung, M.; Ott, C.

    1985-01-01

    A listing and an example of outputs of the M.C. code SAD1 are given here. This code has been used many times to predict responses of fast neutrons in hydrogenic materials (in our case emulsions or plastics) towards the elastic n, p scattering. It can be easily extended to other kinds of such materials and to any kind of incident fast neutron spectrum

  10. Absolute measurement of thermal neutron fluence and its application for fission track dating

    International Nuclear Information System (INIS)

    Ganzawa, Yoshihiro; Honda, Teruyuki; Nozaki, Tetsuya.

    1988-01-01

    The absolute measurements of thermal neutron fluence for fission track dating have been developed after the proceeding results of Honda et al. (1987). The 2,200 m/sec activation cross section of 197 Au (98.8 barn) is corrected to 87.4 barn (σa) by the three factors of the neutron temperature, Maxwellian distribution of thermal neutrons and non 1/v correction factor for the above absolute measurement. The calibrated factor (B th ) of standard glasses (SRM613, SRM962a, CN-1 and CN-2) and zeta-a (ζa) values for fission track dating are determined on the basis of these experimental results. The values of B th , (7.47 ± 0.29) x 10 9 for SRM613, (7.43 ± 0.34) x 10 9 for SRM962a, (2.50 ± 0.06) x 10 9 for CN-1 and (2.74 ± 0.06) x 10 9 for CN-2 closely agree with those reported previously by Honda et al. (1987). Further, the ζa values of 392.3 ± 16.5 for SRM962a and SRM613, 131.4 ± 3.1 for CN-1 and 144.1 ± 3.3 for CN-2 calculated from B th , effective thermal neutron fission cross-section σf (497.4 barn), isotopic abundance ratio 235 U/ 239 U, I (7.2527 x 10 -3 ) and spontaneous fission decay constant of 238 U, λ f (6.85 x 10 -17 a -7 ) show close agreement with ζ b values (392.5 ± 10.0, 131.6 ± 3.3, 140.1 ± 3.5) derived from the absolute age of Fish Canyon Tuff (27.9 ± 0.7 Ma) respectively. The fission track dating of zircons separated from Oligocene-Miocene tuff distributed in Eastern Hokkaido have been carried out by the external detector method using ζ a . The obtained ages are 28.6 ± 0.7 Ma (1 - 2) and 23.3 ± 0.7 Ma (3 - 2). These results agree well with the geologic age supported from Ashoro Fossil Fauna, K-Ar ages of volcanic rocks and stratigraphy in this area. (author)

  11. On the studies of thermodynamics properties of fast neutron irradiated (LixK1-x)2SO4 crystals

    Science.gov (United States)

    El-Khatib, A. M.; Kassem, M. E.; Gomaa, N. G.; Mahmoud, S. A.

    The effect of fast neutron irradiation on the thermodynamic properties of (LixK1-x)2SO4, (x = 0.1, 0.2,˙˙˙˙˙˙˙˙0.5) has been studied. The measurements were carried out in the vicinity of phase transition. The study reveals that as the lithium content decreases the first high temperature phase Tc = 705 K disappears, while the second one is shifted to lower temperature. It is observed also that the specific heat, Cp, decreases sharply with neutron integrated fluence φ and increases once more. Both entropy and enthalpy changes increase with the increase of neutron integrated fluence.

  12. Assessment of the effects of neutron fluence on Swedish nuclear pressure vessels

    International Nuclear Information System (INIS)

    Rao, S.

    1980-11-01

    Nuclear pressure vessels are subject to neutron irradiation during service causing embrittlement. This is one important factor in the overall problem of reactor vessel integrity. At present the irradiation effects are mainly assessed by the Charpy V-notch test. Two measures of embrittlement are defined: the increase of the ductile/brittle transition temperature and the decrease in the upper-shelf energy. The object of the present work is to assess these changes for the Swedish nuclear pressure vessels. On the basis of data from irradiations carried out in other countries and Swedish surveillance programmes, the expected end of life embrittlement is estimated for Swedish vessels. The results show that the embrittlement of most reactor vessels is expected to be quite small. Oskarshamn 1 and PWR-vessels, however, will probably show moderate changes, the former due to the higher copper content, and the latter due to the high end of life fluences. Some of the vessel materials which exhibit marginal properties in the upper-shelf energy, as measured by the Charpy V-notch impact test, are identified. It is recommended that fracture mechanics analyses be applied in these cases. (author)

  13. Novel applications of fast neutron interrogation methods

    International Nuclear Information System (INIS)

    Gozani, Tsahi

    1994-01-01

    The development of non-intrusive inspection methods for contraband consisting primarily of carbon, nitrogen, oxygen, and hydrogen requires the use of fast neutrons. While most elements can be sufficiently well detected by the thermal neutron capture process, some important ones, e.g., carbon and in particular oxygen, cannot be detected by this process. Fortunately, fast neutrons, with energies above the threshold for inelastic scattering, stimulate relatively strong and specific gamma ray lines from these elements. The main lines are: 6.13 for O, 4.43 for C, and 5.11, 2.31 and 1.64 MeV for N. Accelerator-generated neutrons in the energy range of 7 to 15 MeV are being considered as interrogating radiations in a variety of non-intrusive inspection systems for contraband, from explosives to drugs and from coal to smuggled, dutiable goods. In some applications, mostly for inspection of small items such as luggage, the decision process involves a rudimentary imaging, akin to emission tomography, to obtain the localized concentration of various elements. This technique is called FNA - Fast Neutron Analysis. While this approach offers improvements over the TNA (Thermal Neutron Analysis), it is not applicable to large objects such as shipping containers and trucks. For these challenging applications, a collimated beam of neutrons is rastered along the height of the moving object. In addition, the neutrons are generated in very narrow nanosecond pulses. The point of their interaction inside the object is determined by the time of flight (TOF) method, that is measuring the time elapsed from the neutron generation to the time of detection of the stimulated gamma rays. This technique, called PFNA (Pulsed Fast Neutron Analysis), thus directly provides the elemental, and by inference, the chemical composition of the material at every volume element (voxel) of the object. The various neutron-based techniques are briefly described below. ((orig.))

  14. Calculation of neutron fluence in the region of the pressure vessel for the history of different reactors by using the Monte-Carlo-method

    International Nuclear Information System (INIS)

    Barz, H.U.; Bertram, W.

    1992-01-01

    Embrittlement of pressure vessel material caused by neutron irradiation is a very important problem for VVER-440 reactors. For the estimation of the fracture risk highly reliable neutron fluence values are necessary. For this reason a special theoretical determination of space dependent neutron fluences has been performed mainly on the basis of Monte-Carlo calculations. The described method allows the accurate calculation of neutron fluences near the pressure vessel in the height of the core region for all reactor histories and loading cycles in an efficient manner. To illustrate the accuracy of the suggested method a comparison with experimental results was done. The calculated neutron fluence values can be used for planning the loading schemes of each reactor according to the safety requirements against brittle fracture. (orig.)

  15. DOUBLE-EXPONENTIAL FITTING FUNCTION FOR EVALUATION OF COSMIC-RAY-INDUCED NEUTRON FLUENCE RATE IN ARBITRARY LOCATIONS.

    Science.gov (United States)

    Li, Huailiang; Yang, Yigang; Wang, Qibiao; Tuo, Xianguo; Julian Henderson, Mark; Courtois, Jérémie

    2017-12-01

    The fluence rate of cosmic-ray-induced neutrons (CRINs) varies with many environmental factors. While many current simulation and experimental studies have focused mainly on the altitude variation, the specific rule that the CRINs vary with geomagnetic cutoff rigidity (which is related to latitude and longitude) was not well considered. In this article, a double-exponential fitting function F=(A1e-A2CR+A3)eB1Al, is proposed to evaluate the CRINs' fluence rate varying with geomagnetic cutoff rigidity and altitude. The fitting R2 can have a value up to 0.9954, and, moreover, the CRINs' fluence rate in an arbitrary location (latitude, longitude and altitude) can be easily evaluated by the proposed function. The field measurements of the CRINs' fluence rate and H*(10) rate in Mt. Emei and Mt. Bowa were carried out using a FHT-762 and LB 6411 neutron prober, respectively, and the evaluation results show that the fitting function agrees well with the measurement results. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Irradiation embrittlement of some 15Kh2MFA pressure vessel steels under varying neutron fluence rates

    Energy Technology Data Exchange (ETDEWEB)

    Valo, M; Bars, B [Technical Research Centre of Finland, Espoo (Finland); Ahlstrand, A [Imatran Voima Oy (IVO), Helsinki (Finland)

    1994-12-31

    Irradiation sensitivity of two forging materials was measured with Charpy-V and fracture mechanic tests, and with different fluence, fluence rate and irradiation time values. Irradiation sensitivity of the materials was found to be less or equal to the current Russian standard, and appears to be well described by the fluence parameter only. A slight additional effect on embrittlement from a long term low fluence irradiation is noticed, but it stays within the total scatter band of data. 7 refs., 17 figs., 4 tabs.

  17. A new electret dosimeter for fast neutrons

    International Nuclear Information System (INIS)

    Campos, L.L.; Suarez, A.A.; Mascarenhas, S.

    1982-01-01

    A new electret for fast-neutron personnel dosimetry is described and calibration curves obtained. Its performance may be improved by changes in the wall composition and geometric parameters. The advantages of electrets over TL and film are the non-erasure of information, low cost, fast reading and portability. (U.K.)

  18. Chemical reactions induced by fast neutron irradiation

    International Nuclear Information System (INIS)

    Katsumura, Y.

    1989-01-01

    Here, several studies on fast neutron irradiation effects carried out at the reactor 'YAYOI' are presented. Some indicate a significant difference in the effect from those by γ-ray irradiation but others do not, and the difference changes from subject to subject which we observed. In general, chemical reactions induced by fast neutron irradiation expand in space and time, and there are many aspects. In the time region just after the deposition of neutron energy in the system, intermediates are formed densely and locally reflecting high LET of fast neutrons and, with time, successive reactions proceed parallel to dissipation of localized energy and to diffusion of the intermediates. Finally the reactions are completed in longer time region. If we pick up the effects which reserve the locality of the initial processes, a significant different effect between in fast neutron radiolysis and in γ-ray radiolysis would be derived. If we observe the products generated after dissipation and diffusion in longer time region, a clear difference would not be observed. Therefore, in order to understand the fast neutron irradiation effects, it is necessary to know the fundamental processes of the reactions induced by radiations. (author)

  19. Fast neutron dosimetry. Progress report, 30 August 1992--1 September 1993

    Energy Technology Data Exchange (ETDEWEB)

    DeLuca, P.M. Jr.; Pearson, D.W.

    1993-12-01

    Research concentrated on three major areas during the last twelve months: (1) investigations of energy fluence and absorbed dose measurements using crystalline and hot pressed TLD materials exposes to ultrasoft beams of photons, (2) fast neutron kerma factor measurements for several important elements as well as NE-213 scintillation material response function determinations at the intense ``white`` source available at the WNR facility at LAMPF, and (3) kerma factor ratio determinations for carbon and oxygen to A-150 tissue equivalent plastic at the clinical fast neutron radiation facility at Harper Hospital, Detroit, MI. Progress summary reports of these efforts are given in this report.

  20. Rapid method of calculating the fluence and spectrum of neutrons from a critical assembly and the resulting dose

    International Nuclear Information System (INIS)

    Bessis, J.

    1977-01-01

    The proposed calculation method is unsophisticated but rapid. The first part (computer code CRITIC), which is based on the Fermi age equation, evaluates the number of neutrons per fission emitted from a moderated critical assembly and their energy spectrum. The second part (computer code NARCISSE), which uses the current albedo for concrete, evaluates the product of neutron reflection on the walls and calculates the fluence resulting at any point in the room and its energy distribution by 21 groups. The results obtained are shown to compare satisfactorily with those obtained through the use of a Monte Carlo program

  1. A system for fast neutron radiography

    International Nuclear Information System (INIS)

    Klann, R.T.

    1996-01-01

    A system has been designed and a neutron generator installed to perform fast neutron radiography. With this sytem, objects as small as a coin or as large as a waste drum can be radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3x10 10 neutrons/second with an average energy of 14.5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available cassettes. The cassettes have been modified to include a thin sheet of plastic to convert neutrons to protons through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9x10 7 to 3.8x10 8 n/cm 2 depending on the type of screen and film

  2. Three-dimensional Monte Carlo calculations of the neutron and γ-ray fluences in the TFTR diagnostic basement and comparisons with measurements

    International Nuclear Information System (INIS)

    Liew, S.L.; Ku, L.P.; Kolibal, J.G.

    1985-10-01

    Realistic calculations of the neutron and γ-ray fluences in the TFTR diagnostic basement have been carried out with three-dimensional Monte Carlo models. Comparisons with measurements show that the results are well within the experimental uncertainties

  3. Fast Neutron Damage Studies on NdFeB Materials

    CERN Document Server

    Spencer, James; Baldwin, A; Boussoufi, Moe; Pellet, David; Volk, James T; Wolf, Zachary

    2005-01-01

    Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas over the life of the facility. Although the linacs will be superconducting, there are still many potential uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the radiation damage situation for rare earth permanent magnet materials was presented at PAC2003 and our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC2004 where the damage appeared proportional to the distances between the effective operating points and Hc. Here we have extended those doses and included more commercial samples together with the induced radioactivities associated with their respective dopants. Hall probe data for the external induction distributions are compared with vector magnetizatio...

  4. Fast Neutron Damage Studies on NdFeB Materials

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.; Spencer, J.; Wolf, Z.; /SLAC; Baldwin, A.; Pellett, D.; Boussoufi, M.; /UC, Davis

    2005-05-17

    Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) since both accelerator and detectors will be subjected to large fluences of hadrons, leptons and {gamma}'s over the life of the facility [1]. While the linacs will be superconducting, there are still many uses for NdFeB in the damping rings, injection and extraction lines and final focus. Our understanding of the situation for rare earth, permanent magnet materials was presented at PAC03 [2]. Our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented at EPAC04 [3]. We have extended the doses, included other manufacturer's samples, and measured induced radioactivities which are discussed in detail.

  5. A Direction Sensitive Fast Neutron Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Antolkovic, B; Holmqvist, B; Wiedling, T

    1964-06-15

    A direction sensitive fast neutron monitor is described and its properties are discussed in some detail. The counter is a modification of the standard long counter of the Hanson and McKibben type. Directional sensitivity is obtained by increasing the shielding of the counter and providing it with a 70 cm long collimator channel. The behaviour of this long counter monitor is compared with that of a standard long counter when both are used in neutron experiments.

  6. Fast neutron damage in germanium detectors

    International Nuclear Information System (INIS)

    Kraner, H.W.

    1979-10-01

    The effects of fast neutron radiation damage on the performance of both Ge(Li) and Ge(HP) detectors have been studied during the past decade and will be summarized. A review of the interaction processes leading to the defect structures causing trapping will be made. The neutron energy dependence of observable damage effects will be considered in terms of interaction and defect production cross sections

  7. Fast neutron therapy in advanced malignant tumour treatment

    International Nuclear Information System (INIS)

    Avinc, A.

    1998-01-01

    In this report the fast neutron therapy applications were examined by thoroughly consideration of the fast neutron sources and the interactions of the fast neutron by the medium. The efficacy of fast neutron radiotherapy with that of patients with locally advanced tumours were compared. Radiological data indicate that fast neutrons could bring benefit in the treatment of some tumour types especially salivary glands, paranasal sinuses, soft tissue sarcomas, prostatic adenocarcinomas, palliative treatment of melanoma and rectum. There is a significant improvement in local/regional control for the neutron group, but no improvement in the survival. The neutron therapy is suggested through which this benefit could be achieved

  8. Measurement of fast neutron background in SAGE

    CERN Document Server

    Abdurashitov, J N; Kalikhov, A V; Matushko, V L; Shikhin, A A; Yants, V E; Zaborskaia, O S

    2002-01-01

    The spectrometer intended for direct measurements of ultra low fluxes of fast neutrons is described. It is sensitive to neutron fluxes of 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 +- 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 +- 2.1) x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4700 meters of water equivalent was measured to be (7.3 +- 2.4) x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be < 2.3 x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in 1.0-11.0 MeV energy range.

  9. Measurement of fast neutron background in SAGE

    International Nuclear Information System (INIS)

    Abdurashitov, J.N.; Gavrin, V.N.; Kalikhov, A.V.; Matushko, V.L.; Shikhin, A.A.; Yants, V.E.; Zaborskaia, O.S.

    2002-01-01

    The spectrometer intended for direct measurements of ultra low fluxes of fast neutrons is described. It is sensitive to neutron fluxes of 10 -7 cm -2 s -1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 ± 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 ± 2.1) x 10 -7 cm -2 s -1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4700 meters of water equivalent was measured to be (7.3 ± 2.4) x 10 -7 cm -2 s -1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be -7 cm -2 s -1 in 1.0-11.0 MeV energy range

  10. Investigation of the reflection of fast neutrons

    International Nuclear Information System (INIS)

    Devillers, Christian; Hasselin, Gilbert

    1964-10-01

    The authors report the study of the reflection of fast neutrons on a plane plate having a finite and varying thickness and an infinite width. Calculations are performed by using a Monte-Carlo method which allows the number, the energy, the direction, the emergence point of neutrons reflected on a plate, to be computed with respect to the energy and direction of incident neutrons. The author present how paths, elastic and inelastic shocks, direction after shock are calculated. Different information are calculated: the numbers of elastic shocks, inelastic shocks and transmitted neutrons, the number, energy and dose albedo, the spectrum and angular distribution, the distribution of neutron in terms of energy and direction

  11. The effects of fast-neutron irradiation on the mechanical properties of austenitic stainless steel

    International Nuclear Information System (INIS)

    Dalton, J.H.

    1978-01-01

    The paper reviews the effects of fast-neutron irradiation on the tensile properties of austenitic stainless steels at irradiation temperatures of less than 400 degrees Celcius, using as an example, work carried out at Pelindaba on an AISI 316 type steel produced in South Africa. Damage produced in these steels at higher irradiation temperatures and fluences is also briefly discussed. The paper concludes with a discussion of some methods of overcoming or decreasing the effects of irradiation damage [af

  12. Radiation therapy with fast neutrons: A review

    International Nuclear Information System (INIS)

    Jones, D.T.L.; Wambersie, A.

    2007-01-01

    Because of their biological effects fast neutrons are most effective in treating large, slow-growing tumours which are resistant to conventional X-radiation. Patients are treated typically 3-4 times per week for 4-5 weeks (sometimes in combination with X-radiation) for a variety of conditions such as carcinomas of the head and neck, salivary gland, paranasal sinus and breast; soft tissue, bone and uterine sarcomas and malignant melanomas. It is estimated that about 27,000 patients have undergone fast neutron therapy to date

  13. Fast Neutron Radiation Effects on Bacillus Subtili

    International Nuclear Information System (INIS)

    Chen Xiaoming; Zhang Jianguo; Chu Shijin; Ren Zhenglong; Zheng Chun; Yang Chengde; Tan Bisheng

    2009-01-01

    To examine the sterilizing effect and mechanism of neutron radiation, Bacillus subtilis var. niger. strain (ATCC 9372) spores were irradiated with the fast neutron from the Chinese fast burst reactor II(CFBR-II). The plate-count results indicated that the D 10 value was 384.6 Gy with a neutron radiation dose rate of 7.4 Gy/min. The rudimental catalase activity of the spores declined obviously with the increase in the radiation dose. Meanwhile, under the scanning electron microscope, no visible influence of the neutron radiation on the spore configuration was detected even if the dose was increased to 4 kGy. The content and distribution of DNA double-strand breaks induced by neutron radiation at different doses were measured and quantified by pulsed-field gel electrophoresis (PFGE). Further analysis of the DNA release percentage (PR), the DNA breakage level (L), and the average molecular weight, indicated that DNA fragments were obviously distributed around the 5 kb regions at different radiation doses, which suggests that some points in the DNA molecule were sensitive to neutron radiation. Both PR and L varied regularly to some extent with the increase in radiation dose. Thus neutron radiation has a high sterilization power, and can induce falling enzyme activity and DNA breakage in Bacillus subtilis spores

  14. Determination of the Neutron Fluence, the Beam Characteristics and the Backgrounds at the CERN-PS TOF Facility

    CERN Multimedia

    Leal, L C; Kitis, G; Guber, K H; Quaranta, A; Koehler, P E

    2002-01-01

    In the scope of our programme we propose to start in July 2000 with measurements on elements of well known cross sections, in order to check the reliability of the whole experimental installation at the CERN-TOF facility. These initial exploratory measurements will provide the key-parameters required for the further experimentation at the CERN-TOF neutron beam. The neutron fluence and energy resolution will be determined as a function of the neutron kinetic energy by reproducing standard capture and fission cross sections. The measurements of capture cross sections on elements with specific cross section features will allow to us to disentangle the different components of backgrounds and estimate their level in the experimental area. The time-energy calibration will be determined and monitored with a set of monoenergetic filters as well as by the measurements of elements with resonance-dominated cross sections. Finally, in this initial phase the behaviour of several detectors scheduled in successive measureme...

  15. Risk from fast neutron exposure

    International Nuclear Information System (INIS)

    Bond, V.P.

    1978-01-01

    The recommendations made by Rossi and Mays imply that the risk associated with the current annual dose equivalent limit of 5 rem for all radiations is unacceptably high, that this limit must be reduced by a factor of 10 or more, and that the conservative linear, no threshold hypothesis must be abandoned. It is shown here that these recommendations are not supported by the newly-analyzed neutron data, and certainly cannot be applied selectively to the annual absorbed dose limit for neutrons. In particular, the judgment that the risk of an annual exposure from 0.5 rad (5 rem) of neutrons is unacceptable high, although perhaps defensible as a personal opinion of the authors, does not follow either from the assumption of a linear-quadratic dose effect relation for low-LET radiation or from other radiobiological considerations. At issue is the level of risk that is to be considered acceptable, a question that is societal and thus not resolvable on purely technical or scientific grounds

  16. The Edinburgh experience of fast neutron therapy

    International Nuclear Information System (INIS)

    Duncan, W.; Arnott, S.J.; Orr, J.A.; Kerr, G.R.

    1982-01-01

    The Edinburgh experience is based on a d(15 + Be) neutron beam generated by a compact CS 30 Cyclotron. Neutron therapy alone given in 20 daily fractions over four weeks has been compared with photon therapy given in the same fractionation schedule. Since clinical studies began in March, 1977, over 500 patients have been treated by fast neutrons. Almost all patients are now admitted to randomly controlled trials. In the head and neck trial conducted in collaboration with collegues in Amsterdam and Essen, 192 patients are available for analysis. Most patients had T3 lesions and about 50% had involved nodes. The cumulative regression rate at six months is similar after neutrons and photons (75%). Later recurrence rates (36%) are also similar. The early radiation morbidity is similar in both groups, but the late reactions are greater after neutrons (15%) than photons (6%). Overall survival is better after photon therapy. A trial of patients with glioblastoma has also shown a better survival after photon therapy. Neutron therapy was associated with demyelinization in three of 18 patients. Patients with transitional cell cancer of the bladder have also been the subject of study. Local tumor control was similar (53%) after neutrons and photons. Late radiation morbidity was much greater after neutrons (20%), compared with photons (2%). In a trial of advanced carcinoma of the rectum, the local tumor control was also similar after neutrons and photons (30%), but morbidity was greater after neutrons. Soft tissue sarcomas have shown response rates (37%) that may be expected after photon therapy. Salivary gland tumors have shown a similar experience, although slow growing tumors such as adenoid cystic carcinoma may respond better to neutrons

  17. Structural elements for fast-neutron reactors

    International Nuclear Information System (INIS)

    Blin, J.C.; Sainfort, Gerard; Silvent, Alain; Silvestres, Georges.

    1974-01-01

    These elements are characterized in that they are obtained from a nickel-alloy and at least a material M, selected from the group comprising iron and silicon, in proportions, by weight, such that irradiation by fast neutrons leads to the generation of Ni 3 -M with no noticeable swelling of said elements. This can be applied to fuel assembly cladding [fr

  18. Microdosimetry of intermediate energy neutrons in fast neutron fields

    International Nuclear Information System (INIS)

    Saion, E.B.; Watt, D.E.

    1988-01-01

    A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)

  19. Neutron flux calculation and fluence in the encircling of the core and vessel of a reactor BWR

    International Nuclear Information System (INIS)

    Martinez C, E.

    2011-01-01

    One of the main objectives related to the safety of any nuclear power plant, including the nuclear power plant of Laguna Verde is to ensure the structural integrity of reactor pressure vessel. To identify and quantify the damage caused by neutron irradiation in the vessel of any nuclear reactor, it is necessary to know both the neutron flux and the neutron fluence that the vessel has been receiving during its operation lifetime, and that the damage observed by mechanical testing are products of microstructural effects induced by neutron irradiation; therefore, it is important the study and prediction of the neutron flux in order to have a better understanding of the damage that these materials are receiving. The calculation here described uses the DORT code, which solves the neutron transport equation in discrete ordinates in two dimensions (x-y, r-θ and r-z), according to a regulatory guide, it should make an approximation of the neutron flux in three dimensions by the so called synthesis method. It is called in that way because it achieves a representation of 3 Dimensional neutron flux combining or summarizing the fluxes calculated by DORT r-θ, r-z and r. This work presents the application of synthesis method, according to Regulatory Guide 1190, to determine the 3 Dimensional fluxes in internal BWR reactor using three different spatial meshes. The results of the neutron flux and fluence, using three different meshes in the directions r, θ and z were compared with results reported in the literature obtaining a difference not larger than 9.61%, neutron flux reached its maximum, 1.58 E + 12 n/cm 2 s, at a height H 4 (239.07 cm) and angle 32.236 o in the core shroud and 4.00 E + 09 n/cm 2 s at a height H 4 and angle 35.27 o in the inner wall of the reactor vessel, positions that are consistent to within ±10% over the ones reported in the literature. (Author)

  20. Fast neutron dosimetry: Progress summary

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.

    1988-01-01

    The purpose was to investigate the radiological physics and biology of very low energy photons derived from a 1-GeV electron synchrotron storage ring. An extensive beam line and irradiation apparatus was designed, developed, and constructed. Dosimetry measurements required invention and testing of a miniature absolute calorimeter and a cell irradiation fixture suitable for scanning exposures under computer control. Measurements of the kerma factors of oxygen, aluminum and silicon for 14-20 MeV neutrons. Custom designed miniature proportional counters of cylindrical symmetry were employed in these determinations. The oxygen kerma factor was found significantly lower than values calculated from microscopic cross sections. We also tested Mg and Fe walled conventional spherical counters. The direct neutron-counting gas interaction is significant enough for these counters that a correction is needed. We also investigated the application of Nuclear Magnetic Resonance spectroscopy to radiation dosimetry. Our purpose was to take advantage of recent development of very high-field magnets, complex RF-pulse techniques for solvent suppression, and improved spectral analysis techniques

  1. Personal fast neutrons dosimetry using radiophotoluminescent glass

    International Nuclear Information System (INIS)

    Salem, Y. O.; Nachab, A.; Nourreddine, A.; Roy, C.

    2013-06-01

    In a previous paper we described a new ambient RPL dosimeter that detects fast neutrons in a mixed n-γ field via (n, p) reactions in a polyethylene converter. In the present study, a personal dosimeter is introduced to enable evaluating the individual dose equivalent H p (10) taking into account the albedo. A calibration factor for estimating H p (10) has been determined from the diminishing angular response as the angle of neutron incidence increases to 60 deg from the normal. MCNPX simulations for 241 Am-Be and 252 Cf neutrons, together with a series of monoenergetic neutron beams from 0.144 to 5 MeV, have been used to characterize the dosimeter response, which agrees well with the experimental 241 Am-Be response. (authors)

  2. Neutron shielding studies on an advanced molten salt fast reactor design

    International Nuclear Information System (INIS)

    Merk, Bruno; Konheiser, Jörg

    2014-01-01

    Highlights: • Material damage due to irradiation has already been discovered at the MSRE. • Neutronic analysis of MSFR with curved blanket wall geometry. • Neutron fluence limit at the wall of the outer vessel can be kept for 80 years. • Shielded MSFR core will be of same dimension than a SFR core. - Abstract: The molten salt reactor technology has gained some new interest. In contrast to the historic molten salt reactors, the current projects are based on designing a molten salt fast reactor. Thus the shielding becomes significantly more challenging than in historic concepts. One very interesting and innovative result of the most recent EURATOM project on molten salt reactors – EVOL – is the fluid flow optimized design of the inner reactor vessel using curved blanket walls. The developed structure leads to a very uniform flow distribution. The design avoids all internal structures. Based on this new geometry a model for neutron physics calculation is presented. The major steps are: the modeling of the curved geometry in the unstructured mesh neutron transport code HELIOS and the determination of the real neutron flux and power distribution for this new geometry. The developed model is then used for the determination of the neutron fluence distribution in the inner and outer wall of the system. Based on these results an optimized shielding strategy is developed for the molten salt fast reactor to keep the fluence in the safety related outer vessel below expected limit values. A lifetime of 80 years can be assured, but the size of the core/blanket system will be comparable to a sodium cooled fast reactor. The HELIOS results are verified against Monte-Carlo calculations with very satisfactory agreement for a deep penetration problem

  3. The Edinburgh experience of fast neutron therapy

    International Nuclear Information System (INIS)

    Duncan, W.; Arnott, S.J.; Orr, J.A.; Kerr, G.R.

    1982-01-01

    The Edinburgh experience is based on a d(15 + Be) neutron beam generated by a compact CS 30 Cyclotron. The facility has an iso-center treatment head providing 240 0 of rotation. The most important limitation of the beam is its poor penetrating quality. We have compared neutron therapy alone given in 20 daily fractions over four weeks with photon therapy given in the same fractionation schedule. Since clinical studies began in March, 1977, over 500 patients have been treated by fast neutrons. Almost all patients are now admitted to randomly controlled trials. In the head and neck trial conducted in collaboraton with colleagues in Amsterdam and Essen, 92 patients are available for analysis. Most patients had T3 lesions and about 50% had involved nodes. The cumulative regression rate at six months is similar after neutrons and photons (75%). Later recurrence rates (36%) are also similar. The early radiation morbidity is similar in both groups, but the late reactions are greater after neutrons (15%) than photons (6%). Overall survival is better after photon therapy. A trial of patients with glioblastoma has also shown a better survival after photon therapy. Neutron therapy was associated with demelinization in three of 18 patients. Patients with transitional cell cancer of the bladder have also been the subject of study. Local tumor control was similar (53%) after neutrons and photons. Late radiation morbidity was much greater after neutrons (20%), compared with photons (2%). In a trial of advanced carcinoma of the rectum, the local tumor control was also similar after neutrons and photons (30%), but morbidity was greater after neutrons. Soft tissue sarcomas have shown response rates (37%) that may be expected after photon therapy

  4. Energy dependence of fast neutron dosimetry using electrochemical etching

    International Nuclear Information System (INIS)

    Su, S.J.; Morgan, K.Z.

    1978-01-01

    Registration of fast-neutron induced recoil tracks by the electrochemical etching technique as applied to sensitive Lexan polycarbonate foils provides a simple and inexpensive means of fast neutron personnel dosimetry. The sensitivity (tracks/neutron) of recoil particle registration is given as a function of neutron energy. Neutrons of 7 Li (p,n) 7 Be, 3 T (d,n) 4 He and 9 B, respectively. Results are compared with other studies using other neutron sources and conventional etching method

  5. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    DESIG: E 263 09 ^TITLE: Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron ^SIGNUSE: Refer to Guide E 844 for guidance on the selection, irradiation, and quality control of neutron dosimeters. Refer to Practice E 261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors. Pure iron in the form of foil or wire is readily available and easily handled. Fig. 1 shows a plot of cross section as a function of neutron energy for the fast-neutron reaction 54Fe(n,p)54Mn (1). This figure is for illustrative purposes only to indicate the range of response of the 54Fe(n,p)54Mn reaction. Refer to Guide E 1018 for descriptions of recommended tabulated dosimetry cross sections. 54Mn has a half-life of 312.13 days (3) (2) and emits a gamma ray with an energy of 834.845 keV (5). (2) Interfering activities generated by neutron activation arising from thermal or fast neutron interactions are 2.57878 (46)-h 56Mn, 44.95-d (8) 59Fe, and 5.27...

  6. Fast neutron activation analysis by means of low voltage neutron generator

    Directory of Open Access Journals (Sweden)

    M.E. Medhat

    Full Text Available A description of D-T neutron generator (NG is presented. This machine can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. Procedure of neutron flux determination and efficiency calculation is described. Examples of testing some Egyptian natural cosmetics are given. Keywords: Neutron generator, Fast neutron activation analysis, Elemental analysis

  7. [Fast neutron cross section measurements

    International Nuclear Information System (INIS)

    1991-01-01

    In the 14 MeV Neutron Laboratory, we have continued the development of a facility that is now the only one of its kind in operation in the United States. We have refined the klystron bunching system described in last year's report to the point that 1.2 nanosecond pulses have been directly measured. We have tested the pulse shape discrimination capability of our primary NE 213 neutron detector. We have converted the RF sweeper section of the beamline to a frequency of 1 MHz to replace the function of the high voltage pulser described in last year's report which proved to be difficult to maintain and unreliable in its operation. We have also overcome several other significant experimental difficulties, including a major problem with a vacuum leak in the main accelerator column. We have completed additional testing to prove the remainder of the generation and measurement systems, but overcoming some of these experimental difficulties has delayed the start of actual data taking. We are now in a position to begin our first series of ring geometry elastic scattering measurements, and these will be underway before the end of the current contract year. As part of our longer term planning, we are continuing the conceptual analysis of several schemes to improve the intensity of our current pulsed beam. These include the provision of a duoplasmatron ion source and/or the provision of preacceleration bunching. Additional details are given later in this report. A series of measurements were carried out at the Tandem Dynamatron Facility involving the irradiation of a series of yttrium foils and the determination of activation cross sections using absolute counting techniques. The experimental work has been completed, and final analysis of the cross section data will be completed within several months

  8. Thermoluminescence fast neutron dosimetry by laser heating

    International Nuclear Information System (INIS)

    Mathur, V.K.; Brown, M.D.; Braeunlich, P.

    1984-01-01

    Heating rates in excess of 10 4 K.sec -1 have been achieved for thin layers of TL dosemeters by laser heating. The high heating rate improves the signal to noise ratio up to a factor of 10 3 . Thus sensitive thin film fast neutron dosemeters with negligible self-shielding have become a practical reality. Thin samples of CaSO 4 :Dy have been investigated for their response to fast neutrons from a Pu-Be source and a 14.6 MeV neutron generator by using a hydrogenous radiator. A 15 watt CO 2 laser was focussed on the thin TLD layer to a spot size of less than 1 mm to heat it. An exposure of a few tens of milliseconds was sufficient to obtain a TLD curve, which was displayed and processed by a wave form digitiser. The laser spot could be scanned over the TLD sample by a x-y positioner and a large number of observations were obtained on each sample. Preliminary results show that it is possible to obtain a figure of merit of approx. 5% in a mixed n, γ field. A practical design for a fast neutron dosemeter is proposed. (author)

  9. Fast neutron dosimetry using CR-39 track detectors with polyethylene as radiator

    International Nuclear Information System (INIS)

    Castillo, F.; Espinosa, G.; Golzarri, J.I.; Osorio, D.; Rangel, J.; Reyes, P.G.; Herrera, J.J.E.

    2013-01-01

    The chemical etching parameters (etching time, temperature, normality of etchant, etc.) for the use of CR-39 (allyl diglycol carbonate – Lantrack ® ) as a fast neutron dosimeter have been optimized. The CR-39 chips, placed under a 1.5 mm polyethylene radiator, were exposed for calibration to an 241 Am-Be source at different time intervals for a given neutron fluence. After several chemical etching processes of the detectors with different conditions, the optimum characteristics for the chemical etching were found at 6N KOH solution, 60 ± 1 °C, for 12 h. An accurate relationship between the dose and fluence calculations was obtained as a function of the track density. - Highlights: ► Optimum etching time for fast neutron irradiated CR-39 track detectors is found. ► Relationship between dose and fluence obtained as a function of the track density. ► Results are consistent with those reported elsewhere, and extend the dose range

  10. A study of television imaging system for fast neutron radiography

    International Nuclear Information System (INIS)

    Yoshii, Koji

    1992-01-01

    The neutron radiography with fast neutron beam is a very useful imaging technique for thicker objects, especially those composed of hydrogen-rich materials which are sometimes difficult to image by thermal neutron radiography. The fast neutron radiography has not been studied so much as the thermal neutron radiography. The fast neutron radiography has been studied at the fast neutron source reactor 'Yayoi' of the University of Tokyo built in Tokai-mura. The average neutron energy of the Yayoi is about 1 MeV, and the peak neutron flux at the core center is 0.8 x 10 12 at the maximum operating power of 2 kW. In the experiment on fast neutron radiography, a CR39 nuclear track detector has been used successfully. But in the Yayoi radiography procedure, about 24 hours were required for obtaining an imaging result. To get a prompt imaging result and a real-time imaging result, it is necessary to develop a fast neutron television system, and in this paper, a new fast neutron TV system is proposed. The main difference is the converter material sensitive to fast neutrons. The study on the fast neutron TV system was carried out by using the Baby Cyclotron of Japan Steel Works, and the good images were realized. (K.I.)

  11. Fast neutron dosimetry in research reactors

    International Nuclear Information System (INIS)

    Eckert, R.

    1960-01-01

    This work chiefly concerns the measurement of fast neutron fluxes by means of threshold detectors. It is shown first that the cross sections to use for measurements by threshold detectors depend largely on the neutron spectrum, that is the position in which the measurement is performed. The spectrum is determined by calculation for several positions in the piles EL2 and EL3; from this can be deduced the cross-sections to be used for the measurements carried out in these positions. In the last part of the report, possible methods for the experimental determination of the spectrum are indicated. (author) [fr

  12. Scattering of fast neutrons from 103Rh

    International Nuclear Information System (INIS)

    Barnard, E.; Reitmann, D.

    1978-01-01

    The scattering of fast neutrons from 103 Rh was studied by means of (n, n), (n, n') and (n, n'γ) measurements at neutron energies up to 2 MeV. More than fifty unknown γ-transitions were identified and a level scheme established which includes fifteen unreported excited states. Branching ratios, spins and parities for these levels were deduced, as well as the effective activation cross sections for the 103 Rh(n, n')sup(103m)Rh reaction. The results are compared with existing data and with calculations based on the optical and statistical models. (Auth.)

  13. A system for fast neutron radiography

    International Nuclear Information System (INIS)

    Klann, R.T.

    1997-01-01

    A system has been designed and a neutron generator installed to perform fast neutron radiography. With this system, objects as small as a coin and as large as a 19 liter container have been radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3 x 10[sup 10] neutrons/second with an average energy of 14. 5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available light-tight cassettes. The cassettes have been modified to include a thin sheet of plastic to produce protons from the neutron beam through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9 x 10[sup 7] n/cm[sup 2] to 3.8 x 10[sup 8] n/cm[sup 2] depending on the type of screen and film. The optimum source-to-film distance was found to be 150 cm. At this distance, the geometric unsharpness was determined to be approximately 2.2-2.3 mm and the smallest hole that could be resolved in a 1.25 cm thick sample had a diameter of 0.079 cm

  14. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Copper

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers procedures for measuring reaction rates by the activation reaction 63Cu(n,α)60Co. The cross section for 60Co produced in this reaction increases rapidly with neutrons having energies greater than about 5 MeV. 60Co decays with a half-life of 1925.27 days (±0.29 days)(1) and emits two gamma rays having energies of 1.1732278 and 1.332492 MeV (1). The isotopic content of natural copper is 69.17 % 63Cu and 30.83 % 65Cu (2). The neutron reaction, 63Cu(n,γ)64Cu, produces a radioactive product that emits gamma rays which might interfere with the counting of the 60Co gamma rays. 1.2 With suitable techniques, fission-neutron fluence rates above 109 cm−2·s−1 can be determined. The 63Cu(n,α)60Co reaction can be used to determine fast-neutron fluences for irradiation times up to about 15 years (for longer irradiations, see Practice E261). 1.3 Detailed procedures for other fast-neutron detectors are referenced in Practice E261. 1.4 This standard does not purport to address all of the...

  15. Fission-neutrons source with fast neutron-emission timing

    Energy Technology Data Exchange (ETDEWEB)

    Rusev, G., E-mail: rusev@lanl.gov; Baramsai, B.; Bond, E.M.; Jandel, M.

    2016-05-01

    A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of {sup 252}Cf. The time is provided by registering the fission fragments in a layer of a thin scintillation film with a signal rise time of 1 ns. The scintillation light output is measured by two silicon photomultipliers with rise time of 0.5 ns. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements using it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  16. Fast and epithermal neutron radiography using neutron irradiator

    International Nuclear Information System (INIS)

    Oliveira, Karol A.M. de; Crispim, Verginia R.; Ferreira, Francisco J.O.

    2013-01-01

    The neutron radiography technique (NR) with neutrons in the energy range fast to epithermal is a powerful tool used in no-destructive inspection of bulky objects of diverse materials, including those rich in hydrogen, oxygen, nitrogen ad carbon. Thus, it can be used to identify, inclusions, voids and thickness differences in materials such as explosive artifacts and narcotics. Aiming at using NR with fast and epithermal neutrons, an Irradiator was constructed by: a 241 Am-Be source, with 5 Ci activity, a collimator with adjustable collimation rate, L/D; and a shield device composed by plates of borated paraffin and iron. The test specimens chosen were a Beam Purity Indicator (BPI) and an Indicator of Visual Resolution (IVR). The neutron radiography images obtained had a resolution of 444.4 μm and 363.6 μm respectively when registered in: 1) the sheet of the nuclear track solid detector, CR-39 type, through X (n,p) Y nuclear reaction; and 2) Kodak Industrex M radiographic film plate in close contact with a boron converter screen, both stored in a Kodak radiographic cassette. (author)

  17. Development of Optical Fiber Detector for Measurement of Fast Neutron

    International Nuclear Information System (INIS)

    YAGI, Takahiro; KAWAGUCHI, Shinichi; MISAWA, Tsuyoshi; PYEON, Cheol Ho; UNESAKI, Hironobu; SHIROYA, Seiji; OKAJIMA, Shigeaki; TANI, Kazuhiro

    2008-01-01

    Measurement of fast neutron flux is important for investigation of characteristic of fast reactors. In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO 2 as converter material because 232 Th makes fission reaction with fast neutrons. The place where 232 Th can be used is limited by regulations because 232 Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without 232 Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons. (authors)

  18. Monitoring the fast neutrons in a high flux: The case for 242Pu fission chambers

    International Nuclear Information System (INIS)

    Filliatre, P.; Jammes, C.; Oriol, L.; Geslot, B.; Vermeeren, L.

    2009-01-01

    Fission chambers are widely used for on-line monitoring of neutron fluxes in irradiation reactors. A selective measurement of a component of interest of the neutron flux is possible in principle thanks to a careful choice of the deposit material. However, measuring the fast component is challenging when the flux is high (up to 10 15 n/cm 2 /s) with a significant thermal component. The main problem is that the isotopic content of a material selected for its good response to fast neutrons evolves with irradiation, so that the material is more and more sensitive to thermal neutrons. Within the framework of the FNDS (Fast Neutron Detector System) project, we design tools that simulate the evolution of the isotopic composition and fission rate for several deposits under any given flux. In the case of a high flux with a significant thermal component, 242 Pu is shown after a comprehensive study of all possibilities to be the best choice for measuring the fast component, as long as its purity is sufficient. If an estimate of the thermal flux is independently available, one can correct the signal for that component. This suggests a system of two detectors, one of which being used for such a correction. It is of very high interest when the detectors must be operated up to a high neutron fluence. (authors)

  19. Monitoring the fast neutrons in a high flux: The case for {sup 242}Pu fission chambers

    Energy Technology Data Exchange (ETDEWEB)

    Filliatre, P.; Jammes, C.; Oriol, L.; Geslot, B. [Commissariat a l' Energie Atomique, DEN/SPEX/LDCI, Centre de Cadarache, F-13108 Saint-Paul-lez-Durance (France); Vermeeren, L. [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)

    2009-07-01

    Fission chambers are widely used for on-line monitoring of neutron fluxes in irradiation reactors. A selective measurement of a component of interest of the neutron flux is possible in principle thanks to a careful choice of the deposit material. However, measuring the fast component is challenging when the flux is high (up to 10{sup 15} n/cm{sup 2}/s) with a significant thermal component. The main problem is that the isotopic content of a material selected for its good response to fast neutrons evolves with irradiation, so that the material is more and more sensitive to thermal neutrons. Within the framework of the FNDS (Fast Neutron Detector System) project, we design tools that simulate the evolution of the isotopic composition and fission rate for several deposits under any given flux. In the case of a high flux with a significant thermal component, {sup 242}Pu is shown after a comprehensive study of all possibilities to be the best choice for measuring the fast component, as long as its purity is sufficient. If an estimate of the thermal flux is independently available, one can correct the signal for that component. This suggests a system of two detectors, one of which being used for such a correction. It is of very high interest when the detectors must be operated up to a high neutron fluence. (authors)

  20. Comparison of Calculated and Measured Neutron Fluence in Fuel/Cladding Irradiation Experiments in HFIR

    International Nuclear Information System (INIS)

    Ellis, Ronald James

    2011-01-01

    A recently-designed thermal neutron irradiation facility has been used for a first series of irradiations of PWR fuel pellets in the high flux isotope reactor (HFIR) at Oak Ridge National Laboratory. Since June 2010, irradiations of PWR fuel pellets made of UN or UO 2 , clad in SiC, have been ongoing in the outer small VXF sites in the beryllium reflector region of the HFIR, as seen in Fig. 1. HFIR is a versatile, 85 MW isotope production and test reactor with the capability and facilities for performing a wide variety of irradiation experiments. HFIR is a beryllium-reflected, light-water-cooled and -moderated, flux-trap type reactor that uses highly enriched (in 235 U) uranium (HEU) as the fuel. The reactor core consists of a series of concentric annular regions, each about 2 ft (0.61 m) high. A 5-in. (12.70-cm)-diam hole, referred to as the flux trap, forms the center of the core. The fuel region is composed of two concentric fuel elements made up of many involute-shaped fuel plates: an inner element that contains 171 fuel plates, and an outer element that contains 369 fuel plates. The fuel plates are curved in the shape of an involute, which provides constant coolant channel width between plates. The fuel (U 3 O 8 -Al cermet) is nonuniformly distributed along the arc of the involute to minimize the radial peak-to-average power density ratio. A burnable poison (B 4 C) is included in the inner fuel element primarily to reduce the negative reactivity requirements of the reactor control plates. A typical HEU core loading in HFIR is 9.4 kg of 235 U and 2.8 g of 10 B. The thermal neutron flux in the flux trap region can exceed 2.5 x 10 15 n/cm 2 · s while the fast flux in this region exceeds 1 x 10 15 n/cm 2 · s. The inner and outer fuel elements are in turn surrounded by a concentric ring of beryllium reflector approximately 1 ft (0.30 m) thick. The beryllium reflector consists of three regions: the removable reflector, the semi-permanent reflector, and the

  1. Dosimetry and biological effects of fast neutrons

    International Nuclear Information System (INIS)

    Zoetelief, J.

    1981-01-01

    This thesis contains studies on two types of cellular damage: cell reproductive death and chromosome aberrations induced by irradiation with X rays, gamma rays and fast neutrons of different energies. A prerequisite for the performance of radiobiological experiments is the determination of the absorbed dose with a sufficient degree of accuracy and precision. Basic concepts of energy deposition by ionizing radiation and practical aspects of neutron dosimetry for biomedical purposes are discussed. Information on the relative neutron sensitivity of GM counters and on the effective point of measurement of ionization chambers for dosimetry of neutron and photon beams under free-in-air conditions and inside phantoms which are used to simulate the biological objects is presented. Different methods for neutron dosimetry are compared and the experimental techniques used for the investigations of cell reproductive death and chromosome aberrations induced by ionizing radiation of different qualities are presented. Dose-effect relations for induction cell inactivation and chromsome aberrations in three cultured cell lines for different radiation qualities are presented. (Auth.)

  2. Direct fast neutron detection: A status report

    International Nuclear Information System (INIS)

    Peurrung, A.J.; Hansen, R.R.; Craig, R.A.; Hensley, W.K.; Hubbard, C.W.; Keller, P.E.; Reeder, P.L.; Sunberg, D.S.

    1997-12-01

    This report describes the status of efforts to develop direct fast-neutron detection via proton recoil within plastic scintillator. Since recording proton recoil events is of little practical use without a means to discriminate effectively against gamma-ray interactions, the present effort is concentrated on demonstrating a method that distinguishes between pulse types. The proposed method exploits the different pulse shapes that are to be expected primarily on the basis of the slower speed of the recoiling fission neutrons. Should this effort ultimately prove successful, the resulting novel technology will have the potential to significantly lower cost and increase capability for a number of critical neutron-detection applications. Considerable progress has been made toward a clear and compelling demonstration of this new technique. An exhaustive theoretical and numerical investigation of the method has been completed. The authors have been able to better understand the laboratory results and estimate the performance that could ultimately be achieved using the proposed technique. They have assessed the performance of a number of different algorithms for discriminating between neutron and gamma ray events. The results of this assessment will be critical when the construction of low-cost, field-portable neutron detectors becomes necessary. Finally, a laboratory effort to realize effective discrimination is well underway and has resulted in partial success

  3. Fast-neutron, coded-aperture imager

    Science.gov (United States)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  4. NGI-9 pulsed neutron generator with a fluence to 1010 n/s

    International Nuclear Information System (INIS)

    Allakhverdov, A.Sh.; Ogarkin, V.I.; Silicheva, G.P.; Timofeev, Yu.I.

    1975-01-01

    A neutron pulse generator with 14 MeV energy used for the activation analysis, is described. Its functional diagram and the technical characteristics are presented. The studies of the generator that resulted in determination of the effect of the accelerating voltage amplitude, the delay in the ion source firing with respect to the pulse of the accelerating voltage, the amount of operating ion sources and the energy imparted to them on the neutron flux magnitude are conducted. It is confirmed by the studies that the neutron generator operating in the nominal regime makes it possible to obtain a neutron flux of 5x10 9 -10 10 neutr./s. The dependence of the neutron flux variation on the frequency of pulse sequence for various ion sources is shown

  5. Towards radiation hard converter material for SiC-based fast neutron detectors

    Science.gov (United States)

    Tripathi, S.; Upadhyay, C.; Nagaraj, C. P.; Venkatesan, A.; Devan, K.

    2018-05-01

    In the present work, Geant4 Monte-Carlo simulations have been carried out to study the neutron detection efficiency of the various neutron to other charge particle (recoil proton) converter materials. The converter material is placed over Silicon Carbide (SiC) in Fast Neutron detectors (FNDs) to achieve higher neutron detection efficiency as compared to bare SiC FNDs. Hydrogenous converter material such as High-Density Polyethylene (HDPE) is preferred over other converter materials due to the virtue of its high elastic scattering reaction cross-section for fast neutron detection at room temperature. Upon interaction with fast neutrons, hydrogenous converter material generates recoil protons which liberate e-hole pairs in the active region of SiC detector to provide a detector signal. The neutron detection efficiency offered by HDPE converter is compared with several other hydrogenous materials viz., 1) Lithium Hydride (LiH), 2) Perylene, 3) PTCDA . It is found that, HDPE, though providing highest efficiency among various studied materials, cannot withstand high temperature and harsh radiation environment. On the other hand, perylene and PTCDA can sustain harsh environments, but yields low efficiency. The analysis carried out reveals that LiH is a better material for neutron to other charge particle conversion with competent efficiency and desired radiation hardness. Further, the thickness of LiH has also been optimized for various mono-energetic neutron beams and Am-Be neutron source generating a neutron fluence of 109 neutrons/cm2. The optimized thickness of LiH converter for fast neutron detection is found to be ~ 500 μm. However, the estimated efficiency for fast neutron detection is only 0.1%, which is deemed to be inadequate for reliable detection of neutrons. A sensitivity study has also been done investigating the gamma background effect on the neutron detection efficiency for various energy threshold of Low-Level Discriminator (LLD). The detection

  6. Swelling in several commercial alloys irradiated to very high neutron fluence

    International Nuclear Information System (INIS)

    Gelles, D.S.; Pintler, J.S.

    1984-01-01

    Swelling values have been obtained from a set of commercial alloys irradiated in EBR-II to a peak fluence of 2.5 x 10 23 n/cm 2 (E > 0.1 MeV) or approx. 125 dpa covering the range 400 to 650 0 C. The alloys can be ranked for swelling resistance from highest to lowest as follows: the martensitic and ferritic alloys, the niobium based alloys, the precipitation strengthened iron and nickel based alloys, the molybdenum alloys and the austenitic alloys

  7. Fast-neutron, coded-aperture imager

    International Nuclear Information System (INIS)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-01-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  8. Fast-neutron, coded-aperture imager

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F., E-mail: bernard.phlips@nrl.navy.mil; Hutcheson, Anthony L., E-mail: anthony.hutcheson@nrl.navy.mil; Wulf, Eric A., E-mail: eric.wulf@nrl.navy.mil

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  9. Neutron fluence in a 18 MeV Electron Accelerator for Therapy; Fluencia de neutrones en un Acelerador de Electrones de 18 MeV para terapia

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L C [Instituto Nacional de Investigaciones Nucleares, Direccion de Innovacion Tecnologica, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2001-07-01

    An investigation was made on the theoretical fundamentals for the determination of the neutron fluence in a linear electron accelerator for radiotherapy applications and the limit values of leakage neutron radiation established by guidelines and standards in radiation protection for these type of accelerators. This investigation includes the following parts: a) Exhaustive bibliographical review on the topics mentioned above, in order to combine and to update the necessary basic information to facilitate the understanding of this subject; b) Analysis of the accelerator operation and identification of its main components, specially in the accelerator head; c) Study of different types of targets and its materials for the Bremsstrahlung production which is based on the electron initial energy, the thickness of the target, and its angular distribution and energy, which influences in the neutron generation by means of the photonuclear and electro disintegration reactions; d) Analysis of the neutron yield based on the target type and its thickness, the energy of electrons and photons; e) Analysis of the neutron energy spectra generated in the accelerator head, inside and outside the treatment room; f) Study of the dosimetry fundamentals for neutron and photon mixed fields, the dosimeter selection criteria and standards applied for these applications, specially the Panasonic U D-809 thermoluminescent dosemeter and C R-39 nuclear track dosimeter; g) Theoretical calculation of the neutron yield using a simplified geometric model for the accelerator head with spherical cell, which considers the target, primary collimator, flattener filter, movable collimators and the head shielding as the main components for radiation production. The cases with W and Pb shielding for closed movable collimators and an irradiation field of 20 x 20 cm{sup 2} were analyzed and, h) Experimental evaluation of the leakage neutron radiation from the patient and head planes, observing that the

  10. Biological effects and RAPD analysis of alfalfa (medicago sativa L.) irradiated by fast neutrons

    International Nuclear Information System (INIS)

    Han Weibo; Zhang Yuexue; Tang Fenglan; Liu Jielin; Liu Fengqi; Shang Chen; Kong Fuquan; Wang Xiao; Liu Luxiang

    2011-01-01

    Dry seeds of alfalfa variety Zhaodong were irradiated by fast neutrons generated by linear accelerator with three fluences, 3.60 × 10 11 , 7.10 × 10 11 and 3.54 × 10 12 /cm 2 respectively. Seed germination, growth, and RAPD analysis on the mutation were reported in this study. The results showed that germination vigor and germination rate of irradiated seeds were higher than those of control, but seedling height and root length were reduced with the increase of fluences. When the dosages reached 3.54 × 10 12 /cm 2 , seedling root length decreased by 81.63% compared with the control, but the seedling didn't grow any true leaves except for cotyledon. 36 primers were used in RAPD analysis, and the results showed that the RAPD polymorphic loci rate was 7.25%, 6.52% and 5.80% among the 3.60 × 10 11 /cm 2 , 7.10 × 10 11 /cm 2 and 3.54 × 10 12 /cm 2 treated M 1 plants. RAPD polymorphic loci rate in the 3.60 × 10 11 /cm 2 treated plants was the highest among three treatment. It is concluded that 3.60 × 10 11 /cm 2 could be on optimum fluences for a alfalfa mutation by fast neutrons. (authors)

  11. Development of a High Fluence Neutron Source for Nondestructive Characterization of Nuclear Waste

    International Nuclear Information System (INIS)

    Pickrell, Mark M.

    1999-01-01

    We are addressing the need to measure nuclear wastes, residues, and spent fuel in order to process these for final disposition. For example, TRU wastes destined for the WIPP must satisfy extensive characterization criteria outlined in the Waste Acceptance Criteria, the Quality Assurance Program Plan, and the Performance Demonstration Plan. Similar requirements exist for spent fuel and residues. At present, no nondestructive assay (NDA) instrumentation is capable of satisfying all of the PDP test cycles (particularly for Remote-Handled TRU waste). One of the primary methods for waste assay is by active neutron interrogation. The objective of this project is to improve the capability of all active neutron systems by providing a higher intensity neutron source (by about a factor of 1,000) for essentially the same cost, power, and space requirements as existing systems. This high intensity neutron source is an electrostatically confined (IEC) plasma device. The IEC is a symmetric sphere that was originally developed in the 1960s as a possible fusion reactor. It operates as DT neutron generator. Although it is not likely that this device will scale to fusion reactor levels, previous experiments1 have demonstrated a neutron yield of 2 x 1010 neutrons/second on a table-top device that can be powered from ordinary laboratory circuits (9 kilowatts). Subsequently, the IEC physics has been extensively studied at the University of Illinois and other locations. We have established theoretically the basis for scaling the output up to 1 x 1011 neutrons/second. In addition, IEC devices have run for cumulative times approaching 10,000 hours, which is essential for practical application to NDA. They have been operated in pulsed and continuous mode. The essential features of the IEC plasma neutron source, compared to existing sources of the same cost, size and power consumption, are: Table 1: Present and Target Operating Parameters for Small Neutron Generators Parameter Present IEC

  12. Development and application of a detector for absolute measurement of neutron fluence rate in MeV region

    International Nuclear Information System (INIS)

    Silva Dias, M. da.

    1988-01-01

    The development and performance of the DTS (Dual Thin Scintillator) for the absolute measurement of the neutron fluence rate between 1 and 15 MeV is decribed. The DTS detector consists of a pair of organic scintillators in a dual configuration, where the incident produces a proton-recoil which is detected in a 2Π geometry therefore avoiding the effect of the escape of protons. Thin scintillators are used resulting in small multiple scattering corrections. The theoretical caluclations of detector efficiency and proton-recoil spectrum were performed by means of a Monte Carlos code - CARLO DTS. The calculated efficiency was compared to the experimental one at two neutron energies namely 2.446 MeV and 14.04 MeV applying the Time Correlated Associated Particle technique. The theoretical and experimental efficiencies agreed within the experimental uncertainties of 1.44% and 0.77%, respectively. The performance of the DTS has been verified in an absolute 235 U(n,f) cross section measurement between 1 and 6 MeV neutron energy. The cross section results were compared to those obtained replacing the DTS detector by the NBS (National Bureau of Standards, USA) Black Neutron Detector. The agreement was excellent in the overlapping energy interval of the two experiments (between 1 and 3 MeV), within the estimated uncertainly in the range of 1,0 to 1,7%. The agreement with the most recent evaluation from the ENDF/B-VI was excellent in almost all the energy range between 1 and 6 MeV. The 235 U(n,f) cross section, average over the 252 Cf fission neutron spectrum has been evaluated. The result including the cross section values of the present work was 1220 mb, in excellent agreement with the average value among the most recent measurements, 1227 +- 12 mb, and with the value 1213 mb, using the ENDF/B-VI data. (author) [pt

  13. Radiation annealing mechanisms of low-alloy reactor pressure vessel steels dependent on irradiation temperature and neutron fluence

    International Nuclear Information System (INIS)

    Pachur, D.

    1982-01-01

    Heat treatment after irradiation of reactor pressure vessel steels showed annealing of irradiation embrittlement. Depending on the irradiation temperature, the embrittlement started to anneal at about 220 0 C and was completely annealed at 500 0 C with 4 h of annealing time. The annealing behavior was normally measured in terms of the Vickers hardness increase produced by irradiation relative to the initial hardness as a function of the annealing temperature. Annealing results of other mechanical properties correspond to hardness results. During annealing, various recovery mechanisms occur in different temperature ranges. These are characterized by activation energies from 1.5 to 2.1 eV. The individual mechanisms were determined by the different time dependencies at various temperatures. The relative contributions of the mechanisms showed a neutron fluence dependence, with the lower activation energy mechanisms being predominant at low fluence and vice versa. In the temperature range where partial annealing of a mechanism took place during irradiation, an increase in activation energy was observed. Trend curves for the increase in transition temperature with irradiation, for the relative increase of Vickers hardness and yield strength, and for the relative decrease of Charpy-V upper shelf energy are interpreted by the behavior of different mechanisms

  14. Irradiation induced creep in graphite with respect to the flux effect and the high fluence behaviour

    International Nuclear Information System (INIS)

    Cundy, M.R.

    1984-01-01

    In accelerated irradiation creep tests, performed in the HFR Petten, in a fast neutron flux of about 2x10 4 cm -2 s -1 and at temperatures of 300 and 500 0 C, a fast neutron fluence in excess of 20x10 21 cm -2 (EDN) has been attained so far. As a supplement to this, an analogous creep test was conducted in a fast neutron flux lower by a factor of four which is more typical for the service conditions in a HTR, with a maximum fast fluence of only 4x10 21 cm -2 (EDN). This experiment was aimed at answering the question if, for equal fast fluence, enhanced irradiation creep and Wigner dimensional change would take place in a reduced fast neutron flux. This problem has more generally been addressed to as the ''flux effect'' or the ''equivalent temperature concept''. (orig./IHOE)

  15. Rhodium self-powered detector for monitoring neutron fluence, energy production, and isotopic composition of fuel

    International Nuclear Information System (INIS)

    Sokolov, A.P.; Pochivalin, G.P.; Shipovskikh, Yu.M.; Garusov, Yu.V.; Chernikov, O.G.; Shevchenko, V.G.

    1993-01-01

    The use of self-powered detectors (SPDs) with a rhodium emitter customarily involves monitoring of neutron fields in the core of a nuclear reactor. Since current in an SPD is generated primarily because of the neutron flux, which is responsible for the dynamics of particular nuclear transformations, including fission reactions of heavy isotopes, the detector signal can be attributed unambiguously to energy release at the location of the detector. Computation modeling performed with the KOMDPS package of programs of the current formation in a rhodium SPD along with the neutron-physical processes that occur in the reactor core makes it possible to take account of the effect of the principal factors characterizing the operating conditions and the design features of the fuel channel and the detector, reveal quantitative relations between the generated signal and individual physical parameters, and determine the metrological parameters of the detector. The formation and transport of changed particles in the sensitive part of the SPC is calculated by the Monte Carlo method. The emitter activation, neutron transport, and dynamics of the isotopic composition in the fuel channel containing the SPD are determined by solving the kinetic equation in the multigroup representation of the neutron spectrum, using the discrete ordinate method. In this work the authors consider the operation of a rhodium SPD in a bundle of 49 fuel channels of the RBMK-1000 reactor with a fuel enrichment of 2.4% from the time it is inserted into a fresh channel

  16. Core of a fast neutron nuclear reactor

    International Nuclear Information System (INIS)

    Giacometti, Christian; Mougniot, J.-C.; Ravier, Jean.

    1974-01-01

    The fast neutron nuclear reactor described includes an internal area in fissile material completely enclosed in an area of fertile material forming the outside blanket. The internal fissile area is provided with housings exclusively filled with fertile material forming one or more inside blankets. In this core the internal blankets are shaped like rings vertically separating superimposed rings of fissile material. The blanket of material nearest to the periphery is circumscribed externally by a contour having an indented shape on its straight section so as to increase the contact area between this blanket and the external blanket [fr

  17. Fast-neutron solid-state dosimeter

    International Nuclear Information System (INIS)

    Kecker, K.H.; Haywood, F.F.; Perdue, P.T.; Thorngate, J.H.

    1975-01-01

    This patent relates to an improved fast-neutron solid-state dosimeter that does not require separation of materials before it can be read out, that utilizes materials that do not melt or otherwise degrade at about 300 0 C readout temperature, that provides a more efficient dosimeter, and that can be reused. The dosimeters are fabricated by intimately mixing a TL material, such as CaSO 4 :Dy, with a powdered polyphenyl, such as p-sexiphenyl, and hot-pressing the mixture to form pellets, followed by out-gassing in a vacuum furnace at 150 0 C prior to first use dosimeters

  18. Fast neutron spectrometer with pulse shape discrimination

    International Nuclear Information System (INIS)

    Verbitsky, S.S.

    1978-01-01

    A fast neutron spectrometer with a stilbene single crystal designed to operate at high pulsed count rate has been described. Making use of identification and rejection of events, accompanied by pile-up, allowed to increase permissible count rates by an order of magnitude. The results of energy dependence of signal amplitude and shape relative anisotropy in stilbene in the range 4-10 and 2-8 MeV respectively have been presented. Taking into account anisotropy of the detector-scintillation properties allowed to improve particle discrimination. (Auth.)

  19. Measurement of low neutron fluences with polycarbonate foils electrochemically etched with methyl alcohol-KOH solution

    International Nuclear Information System (INIS)

    Kumamoto, Y.

    1982-01-01

    Electrochemical etching of polycarbonate foils was performed using a KOH solution with a high concentration of methyl alcohol under different conditions of field strength, frequency, temperature and etching time. These studies showed that the highest neutron sensitivity relative to the inherent background in the foil was obtained under the following etching conditions: 52 kV/cm, 1 kHz, 30 0 C, 30 min in a solution of 45 gm KOH + 80 cc CH 3 OH + 20 cc H 2 O. Under these conditions, 100 mrem of neutrons from a Ra-Be source gave 70 pits per cm 2 while background was 7 +- 3 pits per cm 2 (10 +- 5 mrem). The pit diameters were about 90 μm. This sensitivity (giving lowest measurable dose of 15 mrem) is quite sufficient for personnel neutron dosimetry applications and the size of the pits is large enough for easy counting using a microscope at magnification of 40X. (author)

  20. Neutron Spectra, Fluence and Dose Rates from Bare and Moderated Cf-252 Sources

    Energy Technology Data Exchange (ETDEWEB)

    Radev, Radoslav P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-04-01

    A new, stronger 252Cf source (serial number SR-CF-3050-OR) was obtained from Oak Ridge National Laboratory (ORNL) in 2014 to supplement the existing 252Cf sources which had significantly decayed. A new instrument positioning track system was designed and installed by Hopewell Designs, Inc. in 2011. The neutron field from the new, stronger 252Cf source in the modified calibration environment needed to be characterized as well as the modified neutron fields produced by the new source and seven different neutron moderators. Comprehensive information about our 252Cf source, its origin, production, and isotopic content and decay characteristics needed to be compiled as well. This technical report is intended to address these issues.

  1. Reprocessing of fast neutron reactor fuel

    International Nuclear Information System (INIS)

    Bourgeois, M.

    1981-05-01

    A PUREX process specially adapted to fast neutron reactor fuels is employed. The results obtained indicate that the aqueous process can be applied to this type of fuel: almost 10 years operation at the AT 1 plant which processes fuel from RAPSODIE; the good results obtained at the MARCOULE pilot plant on large batches of reference fuels. The CEA is continuing its work to transfer this technology onto an industrial scale. Industrial prototypes and the launching of the TOR (traitement d'oxydes rapides) project will facilitate this transfer. In 1984, it is expected that fast fuels will be able to be processed on a significant scale and that supplementary R and D facilities will be available [fr

  2. Fast-neutron coincidence-counter manual

    International Nuclear Information System (INIS)

    Ensslin, N.; Atwell, T.L.; Lee, D.M.; Erkkila, B.; Marshall, R.S.; Morgan, A.; Shonrock, C.; Tippens, B.; Van Lyssel, T.

    1982-03-01

    The fast neutron counter (FNC) described in this report is a computer-based assay system employing fast-pulse counting instrumentation. It is installed below a glove box in the metal electrorefining area of the Los Alamos National Laboratory Plutonium Processing Facility. The instrument was designed to assay plutonium salts and residues from this process and to verify the mass of electrorefined metal. Los Alamos National Laboratory Groups Q-1, Q-3, and CMB-11 carried out a joint test and evaluation plan of this instrument between May 1978 and May 1979. The results of that evaluation, a description of the FNC, and operating instructions for further use are given in this report

  3. Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl2O3

    Science.gov (United States)

    Rahman, Abu Zayed Mohammad Saliqur; Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long; Xu, Qiu; Atobe, Kozo

    2014-09-01

    The positron lifetimes of fast-neutron-irradiated MgO·nAl2O3 single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10-3 m0c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies.

  4. Research Reactor Application for Materials under High Neutron Fluence. Proceedings of an IAEA Technical Meeting (TM-34779)

    International Nuclear Information System (INIS)

    2011-05-01

    Research reactors (RRs) have played, and continue to play, a key role in the development of the peaceful uses of nuclear energy and technology. The role of the IAEA is to assist Member States in the effective utilization of these technologies in various domains of research such as fundamental and applied science, industry, human health care and environmental studies, as well as nuclear energy applications. In particular, material testing reactors (MTRs), serve as unique tools in scientific and technological development and they have quite a wide variety of applications. Today, a large range of different RR designs exist when compared with power reactors and they also have different operating modes, producing high neutron fluxes, which may be steady or pulsed. Recently, an urgent need has arisen for the development of new advanced materials, for example in the nuclear industry, where RRs offer capacities for irradiation programmes. Besides the scientific and research activities and commercial applications, RRs are also used extensively for educational training activities for scientists and engineers. This report is a compilation of outputs of an IAEA Technical Meeting (TM-34779) held on Research Reactor Application for Materials under High Neutron Fluence. The overall objective of the meeting was to review typical applications of small and medium size RRs, such as material characterization and testing, neutron physics and beam research, neutron radiography and imaging as well as isotope production and other types of non-nuclear applications. Several issues were discussed during the meeting, in particular: (1) recent development of irradiation facilities, specific irradiation programmes and their implementation; (2) effective and optimal RR operation regimes for irradiation purposes; (3) sharing of best practices and existing technical knowledge; and (4) fostering of advanced or innovative technologies, e.g. information exchange and effective collaboration. This

  5. The effect of fast neutron irradiation on the superconducting properties of REBCO coated conductors with and without artificial pinning centers

    Science.gov (United States)

    Fischer, D. X.; Prokopec, R.; Emhofer, J.; Eisterer, M.

    2018-04-01

    Superconductors are essential components of future fusion power plants. The magnet coils responsible for producing the field required for confining the fusion plasma are exposed to considerable neutron radiation. This makes irradiation studies necessary for understanding the radiation response of the superconductor. High temperature superconductors are promising candidates as magnet coil materials. YBCO and GdBCO tapes of several manufacturers were irradiated to fast neutron fluences of up to 3.9 × 1022 m-2 in the research reactor at the Atominstitut. Low energy neutrons contribute to the fission reactor spectrum but not to the expected spectrum at the fusion magnets. Low energy neutrons have to be shielded in irradiation experiments to avoid their substantial effect on the superconducting properties of tapes containing gadolinium. The critical current (I c) of the tapes in this study was examined at fields of up to 15 T and down to a temperature of 30 K. I c first increases upon irradiation and reaches a maximum at a certain fluence, which depends highly on temperature, being highest at low temperature. I c declines at high fluences and eventually degrades with respect to its initial value. Tapes with artificial pinning centers (APCs) degrade at lower fluences than tapes without them. The n-values decrease in all types of tapes after irradiation even when the critical currents are increased. The field dependence of the volume pinning force differs in pristine tapes with and without APCs but shows the same behavior after irradiation.

  6. Does fast-neutron radiotherapy merely reduce the radiation dose

    International Nuclear Information System (INIS)

    Ando, Koichi

    1984-01-01

    We examined whether fast-neutron radiotherapy is superior to low-LET radiotherpy by comparing the relationship between cell survival and tumor control probabilities after exposure of tumor-bearing (species) to the two modalities. Analysis based on TCD 50 assay and lung colony assay indicated that single dose of fast neutron achieved animal cures at higher survival rates than other radiation modalities including single and fractionated γ-ray doses, fractionated doses of fast neutron, and the mixed-beam scheme with a sequence of N-γ-γ-γ-N. We conclude that fast-neutron radiotherapy cured animal tumors with lower cell killing rates other radiation modalities. (author)

  7. [Fast neutron cross section measurements]: Progress report

    International Nuclear Information System (INIS)

    1988-01-01

    As projected in our previous proposal, the past year on the cross section project at the University of Michigan has been one primarily of construction and assembly of our 14 MeV pulsed Neutron Facility. All the components of the system have now been either purchased or fabricated in our shop facilities and have been assembled in their final configuration. We are now in the process of testing the rf components that have been designed to deliver voltage to both the pulser and buncher stages. We expect that the system will be operational by the end of the current contract year. We have also accomplished the design and construction of several other major pieces of equipment that are needed to begin fast neutron time-of-flight measurements. These include the primary proton recoil detector, and a californium fission chamber needed in the efficiency calibration of the primary detector. We have also added considerable concrete shielding designed to lower the neutron background in the experimental area. 10 figs., 5 tabs

  8. Uncertainty Assessments in Fast Neutron Activation Analysis

    International Nuclear Information System (INIS)

    W. D. James; R. Zeisler

    2000-01-01

    Fast neutron activation analysis (FNAA) carried out with the use of small accelerator-based neutron generators is routinely used for major/minor element determinations in industry, mineral and petroleum exploration, and to some extent in research. While the method shares many of the operational procedures and therefore errors inherent to conventional thermal neutron activation analysis, its unique implementation gives rise to additional specific concerns that can result in errors or increased uncertainties of measured quantities. The authors were involved in a recent effort to evaluate irreversible incorporation of oxygen into a standard reference material (SRM) by direct measurement of oxygen by FNAA. That project required determination of oxygen in bottles of the SRM stored in varying environmental conditions and a comparison of the results. We recognized the need to accurately describe the total uncertainty of the measurements to accurately characterize any differences in the resulting average concentrations. It is our intent here to discuss the breadth of potential parameters that have the potential to contribute to the random and nonrandom errors of the method and provide estimates of the magnitude of uncertainty introduced. In addition, we will discuss the steps taken in this recent FNAA project to control quality, assess the uncertainty of the measurements, and evaluate results based on the statistical reproducibility

  9. Material classification by fast neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Buffler, A. E-mail: abuffler@physci.uct.ac.za; Brooks, F.D. E-mail: brooks@physci.uct.ac.za; Allie, M.S.; Bharuth-Ram, K.; Nchodu, M.R

    2001-02-01

    The scattering of a beam of fast monoenergetic neutrons is used to determine elemental compositions of bulk samples (0.2-0.8 kg) of materials composed from one or more of the elements H, C, N, O, Al, S, Fe and Pb. Scattered neutrons are detected by liquid scintillators placed at forward and at backward angles. Different elements are identified by their characteristic scattering signatures derived either from a combination of time-of-flight and pulse height measurements, or from pulse height measurements alone. Scattering signatures measured for multi-element samples are analysed to determine atom fractions for H, C, N, O and other elements in the sample. Atom fractions determined from scattering signatures are insensitive to neutron interactions in material surrounding the scattering sample, provided the amount of material is not excessive. The atom fraction data are used to classify scattering material into categories including 'explosives', 'illicit drugs' and 'other materials' for the purpose of contraband detection.

  10. Silicon Diode Dosimeter for Fast Neutrons

    International Nuclear Information System (INIS)

    Svansson, L.; Widell, C.O.; Swedberg, P.; Wik, M.

    1968-11-01

    The change of the current-voltage characteristics of a small silicon diode is used as a measure of fast neutron dose in the Fast Neutron Dosimeter 5422. This change is permanent and therefore it is possible to integrate doses over a long period of time. Doses from some rad up to 1000 rad can be measured and the information stored is not destroyed during readout. Considerable research work in this field has previously been carried out by the Swedish Institute for National Defence in collaboration with the Institute of Semiconductor Research Stockholm. The present investigation has been made in order to establish the possibilities of the dosimeter for practical applications and to study the variations of important parameters as a function of the production process. In particular the following parameters have been studied: - dose sensitivity, - energy dependence; - fading effect; - temperature influence; - maximum measurable dose. In general one might conclude that the dosimeter 5422 well fulfills requirements usually specified for a dosimeter for field service. Temperature influence and fading effect are of little practical importance within the recommended range of measurement

  11. Silicon Diode Dosimeter for Fast Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Svansson, L; Widell, C O; Swedberg, P [The Inst. of Semiconductor Researc h, Stockholm (Sweden); Wik, M [The Swedish Institute for National Defence, Sun dbyberg (Sweden)

    1968-11-15

    The change of the current-voltage characteristics of a small silicon diode is used as a measure of fast neutron dose in the Fast Neutron Dosimeter 5422. This change is permanent and therefore it is possible to integrate doses over a long period of time. Doses from some rad up to 1000 rad can be measured and the information stored is not destroyed during readout. Considerable research work in this field has previously been carried out by the Swedish Institute for National Defence in collaboration with the Institute of Semiconductor Research Stockholm. The present investigation has been made in order to establish the possibilities of the dosimeter for practical applications and to study the variations of important parameters as a function of the production process. In particular the following parameters have been studied: - dose sensitivity, - energy dependence; - fading effect; - temperature influence; - maximum measurable dose. In general one might conclude that the dosimeter 5422 well fulfills requirements usually specified for a dosimeter for field service. Temperature influence and fading effect are of little practical importance within the recommended range of measurement.

  12. MPACT Fast Neutron Multiplicity System Prototype Development

    Energy Technology Data Exchange (ETDEWEB)

    D.L. Chichester; S.A. Pozzi; J.L. Dolan; M.T. Kinlaw; S.J. Thompson; A.C. Kaplan; M. Flaska; A. Enqvist; J.T. Johnson; S.M. Watson

    2013-09-01

    This document serves as both an FY2103 End-of-Year and End-of-Project report on efforts that resulted in the design of a prototype fast neutron multiplicity counter leveraged upon the findings of previous project efforts. The prototype design includes 32 liquid scintillator detectors with cubic volumes 7.62 cm in dimension configured into 4 stacked rings of 8 detectors. Detector signal collection for the system is handled with a pair of Struck Innovative Systeme 16-channel digitizers controlled by in-house developed software with built-in multiplicity analysis algorithms. Initial testing and familiarization of the currently obtained prototype components is underway, however full prototype construction is required for further optimization. Monte Carlo models of the prototype system were performed to estimate die-away and efficiency values. Analysis of these models resulted in the development of a software package capable of determining the effects of nearest-neighbor rejection methods for elimination of detector cross talk. A parameter study was performed using previously developed analytical methods for the estimation of assay mass variance for use as a figure-of-merit for system performance. A software package was developed to automate these calculations and ensure accuracy. The results of the parameter study show that the prototype fast neutron multiplicity counter design is very nearly optimized under the restraints of the parameter space.

  13. Fast neutron spectroscopy by gas proton-recoil methods at the light water reactor pressure vessel simulator

    International Nuclear Information System (INIS)

    Rogers, J.W.

    1980-10-01

    Fast neutron spectrum measurements were made in a Light Water Reactor (LWR) Pressure Vessel Simulator (PVS) to provide neutron spectral definition required to appropriately perform and interpret neutron dosimetry measurements related to fast neutron damage in LWR-PV steels. Proton-recoil proportional counter methods using hydrogen and methane gas-filled detectors were applied to obtain the proton spectra from which the neutron spectra were derived. Cylindrical and spherical geometry detectors were used to cover the neutron energy range between 50 keV and 2 MeV. Results show that the neutron spectra shift in energy distribution toward lower energy between the front and back of a PVS. The relative neutron flux densities increase in this energy range with increasing thickness of the steel. Neutron spectrum fine structure shapes and changes are observed. These results should assist in the generation of more accurate effective cross sections and fluences for use in LWR-PV fast neutron dosimetry and materials damage analyses

  14. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Aluminum

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers procedures measuring reaction rates by the activation reaction 27Al(n,α)24Na. 1.2 This activation reaction is useful for measuring neutrons with energies above approximately 6.5 MeV and for irradiation times up to about 2 days (for longer irradiations, see Practice E261). 1.3 With suitable techniques, fission-neutron fluence rates above 106 cm−2·s−1 can be determined. 1.4 Detailed procedures for other fast neutron detectors are referenced in Practice E261. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  15. Effect of Fast Neutron Irradiation on Current Transport Properties of HTS Materials

    CERN Document Server

    Ballarino, A; Kruglov, V S; Latushkin, S T; Lubimov, A N; Ryazanov, A I; Shavkin, S V; Taylor, T M; Volkov, P V

    2004-01-01

    The effect of fast neutron irradiation with energy up to 35 MeV and integrated fluence of up to 5 x 10**15 cm-2 on the current transport properties of HTS materials Bi-2212 and Bi-2223 has been studied, both at liquid nitrogen and at room temperatures. The samples irradiated were selected after verification of the stability of their superconducting properties after temperature cycling in the range of 77 K - 293 K. It has been found that the irradiation by fast neutrons up to the above dose does not produce a significant degradation of critical current. The effect of room temperature annealing on the recovery of transport properties of the irradiated samples is also reported, as is a preliminary microstructure investigation of the effect of irradiation on the soldered contacts.

  16. Measurements of possible type inversion in silicon junction detectors by fast neutron irradiation

    International Nuclear Information System (INIS)

    Li, Z.; Kraner, H.W.

    1991-05-01

    The successful application of silicon position sensitive detectors in experiments at the SSC or LHC depends on an accurate assessment of the radiation tolerance of this detector species. In particular, fast neutrons (E av = 1 MeV) produce bulk displacement damage that is projected, from estimated fluences, to cause increased generation (leakage) current, charge collection deficiencies, resistivity changes and possibly semiconductor type change or inversion. Whereas the leakage current increase was believed to be the major concern for estimated fluences of 10 12 n/cm 2 experiment year at the initial SSC luminosity of 10 33 /cm 2 -sec, increased luminosity and exposure time has raised the possible exposure to 10 14 n/cm 2 , which opens the door for the several other radiation effects suggested above to play observable and significant roles in detector degradation or change. 17 refs., 19 figs

  17. Calculation of the neutron parameters of fast thermal reactor

    International Nuclear Information System (INIS)

    Kukuleanu, V.; Mocioiu, D.; Drutse, E.; Konstantinesku, E.

    1975-01-01

    The system of neutron calculation for fast reactors is given. This system was used for estimation of physical parameters of fast thermal reactors investigated. The results obtained and different specific problems of the reactors of this type are described. (author)

  18. Alloys of nickel-iron and nickel-silicon do not swell under fast neutron irradiation

    International Nuclear Information System (INIS)

    Silvestre, G.; Silvent, A.; Regnard, C.; Sainfort, G.

    1975-01-01

    This research is concerned with the effect of fast-neutron irradiation on the swelling of nickel and nickel alloys. Ni-Fe (0-60at%Fe) and Ni-Si (0-8at%Si) were studied, and the fluences were in the range 10 20 -4.3x10 22 n/cm 2 . In dilute alloys, the added elements are dissolved and reduce swelling, silicon being particularly effective. In more concentrated alloys, irradiation of Ni-Fe and Ni-Si alloys brings about the formation of plate-shaped precipitates of Ni 3 X and these alloys do not swell. (Auth.)

  19. Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.

    1986-06-01

    Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

  20. Transmutation of Americium in Fast Neutron Facilities

    International Nuclear Information System (INIS)

    Zhang, Youpeng

    2011-01-01

    In this thesis, the feasibility to use a medium sized sodium cooled fast reactor fully loaded with MOX fuel for efficient transmutation of americium is investigated by simulating the safety performance of a BN600-type fast reactor loaded with different fractions of americium in the fuel, using the safety parameters obtained with the SERPENT Monte Carlo code. The focus is on americium mainly due to its long-term contribution to the radiotoxicity of spent nuclear fuel and its deterioration on core's safety parameters. Applying the SAS4A/SASSYS transient analysis code, it is demonstrated that the power rating needs to be reduced by 6% for each percent additional americium introduction into the reference MOX fuel, maintaining 100 K margin to fuel melting, which is the most limiting failure mechanism. Safety analysis of a new Accelerator Driven System design with a smaller pin pitch-to-diameter ratio comparing to the reference EFIT-400 design, aiming at improving neutron source efficiency, was also performed by simulating performance for unprotected loss of flow, unprotected transient overpower, and protected loss-of-heat-sink transients, using neutronic parameters obtained from MCNP calculations. Thanks to the introduction of the austenitic 15/15Ti stainless steel with enhanced creep rupture resistance and acceptable irradiation swelling rate, the suggested ADS design loaded with nitride fuel and cooled by lead-bismuth eutectic could survive the full set of transients, preserving a margin of 130 K to cladding rupture during the most limiting transient. The thesis concludes that efficient transmutation of americium in a medium sized sodium cooled fast reactor loaded with MOX fuel is possible but leads to a severe power penalty. Instead, preserving transmutation rates of minor actinides up to 42 kg/TWh th , the suggested ADS design with enhanced proton source efficiency appears like a better option for americium transmutation

  1. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Nickel

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers procedures for measuring reaction rates by the activation reaction 58Ni(n,p)58Co. 1.2 This activation reaction is useful for measuring neutrons with energies above approximately 2.1 MeV and for irradiation times up to about 200 days in the absence of high thermal neutron fluence rates (for longer irradiations, see Practice E 261). 1.3 With suitable techniques fission-neutron fluence rates densities above 107 cm−2·s−1 can be determined. 1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E 261. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Note—The burnup corrections were com...

  2. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Titanium

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers procedures for measuring reaction rates by the activation reactions 46Ti(n,p) 46Sc + 47Ti(n, np)46Sc. Note 1—Since the cross section for the (n,np) reaction is relatively small for energies less than 12 MeV and is not easily distinguished from that of the (n,p) reaction, this test method will refer to the (n,p) reaction only. 1.2 The reaction is useful for measuring neutrons with energies above approximately 4.4 MeV and for irradiation times up to about 250 days (for longer irradiations, see Practice E 261). 1.3 With suitable techniques, fission-neutron fluence rates above 109 cm–2·s–1 can be determined. However, in the presence of a high thermal-neutron fluence rate, 46Sc depletion should be investigated. 1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E 261. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all...

  3. Boron neutron capture therapy (BNCT) using fast neutrons: Effects in two human tumor cell lines

    International Nuclear Information System (INIS)

    Sauerwein, W.; Ziegler, W.; Szypniewski, H.; Streffer, C.

    1990-01-01

    The results demonstrate that the effect of fast neutrons on cell survival in cell culture can be enhanced by boron neutron capture reaction. Even with lower enhancement ratios, the concept of NCT assisted fast neutron therapy may successfully be applied for tumor treatment with the Essen cyclotron. (orig.)

  4. Magneto-resistance of Si0,97Ge0,03 whiskers irradiated by reactor fast neutrons

    International Nuclear Information System (INIS)

    Pavlovska, N.T.; Litovchenko, P.G.; Karpenko, A.Ya.; Uhryn, Yu.O.; Pavlovskyj, Yu.V.; Ostrovskii, I.P.; Khoverko, Yu.M.

    2012-01-01

    The influence of reactor fast-neutrons irradiation by the fluence of 8,6·10 17 n/cm 2 and strong magnetic field (up to 14 T) on resistance of Si 1-x Ge x (x = 0.03) whiskers in the temperature range of 4,2 - 300 K is studied. The activation energy of the of impurity levels is calculated. The interpretation of changes in the magneto-resistance is proposed

  5. Neutron Fluence and Energy Reconstruction with the LNE-IRSN/MIMAC Recoil Detector MicroTPC at 27 keV

    Energy Technology Data Exchange (ETDEWEB)

    Maire, D.; Lebreton, L.; Querre, Ph. [Institute for Radioprotection and Nuclear Safety - IRSN, site of Cadarache, 13115 Saint Paul lez Durance (France); Bosson, G.; Guillaudin, O.; Muraz, J.F.; Riffard, Q.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie - LPSCCNRSIN2P3/ UJF/INP, 38000 Grenoble (France)

    2015-07-01

    The French Institute for Radiation protection and Nuclear Safety (IRSN), designated by the French Metrology Institute (LNE) for neutron metrology, is developing a time projection chamber using a Micromegas anode: microTPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize the energy distribution of neutron fluence in the energy range 8 keV - 5 MeV with a primary procedure. The time projection chambers are gaseous detectors able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulation of the detector response. The μTPC is a new reliable detector able to measure energy distribution of the neutron fluence without unfolding procedure or prior neutron calibration contrary to usual gaseous counters. The microTPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27 keV and 144 keV are shown and compared to the complete detector response simulation. This work

  6. Generation of laser-induced fast neutron and its application

    International Nuclear Information System (INIS)

    Cha, Hyung Ki; Lee, S.; Kwon, D.; Nam, S.; Park, S.; Rhee, Y.; Jung, Y.; Lee, K.; Cha, Y.; Kwon, S.; Lim, C.; Han, J.; Park, S.; Chung, C.

    2012-04-01

    The supply of high-efficiency neutron source is still problematic even though a fast neutron source is being accepted increasingly for industrial applications. Radioisotopes and a neutron tube are typically being used, but their neutron flux, lifetime, and price are the limiting factors for more diverse applications. As ultra high power, short pulse laser technologies have been developed, a neutron source generated via laser induced nuclear reaction comes to the fore. The laser induced neutron source has a high peak flux in comparison to the traditional neutron source and is like a point source with its diameter less than 1 mm. These properties can be utilized effectively for the analysis of pulsed fast neutron activation or the studies of a fast neutron material damage and/or recover. The purpose of R and D here is to develop a robust neutron source with a yield of 107 neutrons/s during 1st R and D stage ('07 ∼ '09) and to construct a stable laser neutron source in longer operation and to demonstrate its usefulness for a neutron activation analysis of explosive materials and a neutron impact analysis of crystalline in the second R and D stage ('10 ∼ '11)

  7. Development of a TPC for energy and fluence references in low energies neutronic fields (from 8 keV to 5 MeV)

    International Nuclear Information System (INIS)

    Maire, Donovan

    2015-01-01

    In order to judge the measurement reliability, metrology requires to measure quantities with their uncertainties, in relation to a reference through a documented and unbroken chain of calibrations. In neutron radiation field, instrument response has to be known as a function of the neutron energy. Then detector calibrations are required using reference neutron fields. In France, primary reference neutron fields are held by the LNE-IRSN, at the Laboratory for Neutron Metrology and Dosimetry (LMDN). In order to improve reference neutron field characterization, the LNE-IRSN MIMAC μTPC has been developed. This detector is a Time Projection Chamber (TPC), using a gas at low pressure (30 mbar abs. to 1 bar abs.). Nuclear recoils are generated by neutron elastic scattering onto gas atoms. By measuring the nuclear recoil energy and scattering angle, the μTPC detector is able to measure the energy distribution of the neutron fluence between 8 keV and 5 MeV. The main challenge was to perform accurate spectrometry of neutron fields in the keV range, following a primary procedure. First of all, a metrological approach was followed in order to master every physical process taking part in the neutron detection. This approach led to develop the direct and inverse models, representing the detector response function and its inverse function respectively. Using this detailed characterization, the energy distribution of the neutron fluence has been measured for a continuous neutron field of 27 keV. The reconstructed energy is 28,2 ± 4,5 keV, the difference between μTPC integral fluence measurement and other measurement methods is less than 6%. The LNE-IRSN MIMAC μTPC system becomes the only one system able to measure simultaneously energy and fluence at energies lower than 100 keV, following a primary procedure. The project goal is then reached. These measurements at energies lower than 100 keV shows also a non-linearity between the ionization charge and the ion kinetic energy

  8. SPECTRUM WEIGHTED RESPONSES OF SEVERAL DETECTORS IN MIXED FIELDS OF FAST AND THERMAL NEUTRONS

    Directory of Open Access Journals (Sweden)

    SANG IN KIM

    2014-04-01

    Full Text Available The spectrum weighted responses of various detectors were calculated to provide guidance on the proper selection and use of survey instruments on the basis of their energy response characteristics on the neutron fields. To yield the spectrum weighted response, the detector response functions of 17 neutron-measuring devices were numerically folded with each of the produced calibration neutron spectra through the in-house developed software ‘K-SWR’. The detectors’ response functions were taken from the IAEA Technical Reports Series No. 403 (TRS-403. The reference neutron fields of 21 kinds with 2 spectra groups with different proportions of thermal and fast neutrons have been produced using neutrons from the 241Am-Be sources held in a graphite pile, a bare 241Am-Be source, and a DT neutron generator. Fluence-average energy (Eave varied from 3.8 MeV to 16.9 MeV, and the ambient-dose-equivalent rate [H*(10/h] varied from 0.99 to 16.5 mSv/h.

  9. A Project for High Fluence 14 MeV Neutron Source

    CERN Document Server

    Pillon, Mario; Pizzuto, Aldo; Pietropaolo, Antonino

    2014-01-01

    The international community agrees on the importance to build a large facility devoted to test and validate materials to be used in harsh neutron environments. Such a facility, proposed by ENEA , reconsiders a previous study known as “Sorgentina” but takes into account new technological development so far attained. The “New Sorgentina” Fusion Source (NSFS) project is based upon an intense D - T 14 MeV neutron source achievable with T and D ion beams impinging on 2 m radius rotating target s . NSFS produces about 1 x10 13 n cm - 2 s - 1 over about 50 cm 3 . The NSFS facility will use the ion source and accelerating system technology developed for the Positive Ion Injectors (PII) used to heat the plasma in the fusion experiments,. NSFS, to be intended as an European facility, may be realized in a few years, once provided a preliminary technological program devote to study the operation of the ion source in continuous mode, target h eat loading/ removal, target and tritium handling, inventory as well as ...

  10. Feasibility of the Precise Energy Calibration for Fast Neutron Spectrometers

    Science.gov (United States)

    Gaganov, V. V.; Usenko, P. L.; Kryzhanovskaja, M. A.

    2017-12-01

    Computational studies aimed at improving the accuracy of measurements performed using neutron generators with a tritium target were performed. A measurement design yielding an extremely narrow peak in the energy spectrum of DT neutrons was found. The presence of such a peak establishes the conditions for precise energy calibration of fast-neutron spectrometers.

  11. Recent advances in fast neutron radiography for cargo inspection

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  12. Neutron fluence and energy reconstruction with the IRSN recoil detector μ-TPC at 27 keV, 144 keV and 565 keV

    Energy Technology Data Exchange (ETDEWEB)

    Maire, D.; Lebreton, L.; Richer, J.P. [IRSN, PRP-HOM, SDE, LMDN, 13115 Saint Paul-Lez-Durance (France); Bosson, G.; Bourrion, O.; Guillaudin, O.; Riffard, Q.; Santos, D. [CNRS/IN2P3-UJF-INPG, LPSC, 38000 Grenoble (France)

    2015-07-01

    The French Institute for Radioprotection and Nuclear Safety (IRSN), associated to the French Metrology Institute (LNE), is developing a time projection chamber using a Micromegas anode: μ-TPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize with a primary procedure the energy distribution of neutron fluence in the energy range 8 keV - 1 MeV. The time projection chambers are gaseous detectors, which are able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulated detector response. The μ-TPC is a new reliable detector which enables to measure energy distribution of the neutron fluence without deconvolution or neutron calibration contrary to usual gaseous counters. The μ-TPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27.2 keV, 144 keV and 565 keV are shown and compared to the complete detector simulation. This work shows the first direct

  13. Preliminary design of the cooling system for a gas-cooled, high-fluence fast pulsed reactor (HFFPR)

    International Nuclear Information System (INIS)

    Monteith, H.C.

    1978-10-01

    The High-Fluence Fast Pulsed Reactor (HFFPR) is a research reactor concept currently being evaluated as a source for weapon effects experimentation and advanced reactor safety experiments. One of the designs under consideration is a gas-cooled design for testing large-scale weapon hardware or large bundles of full-length, fast reactor fuel pins. This report describes a conceptual cooling system design for such a reactor. The primary coolant would be helium and the secondary coolant would be water. The size of the helium-to-water heat exchanger and the water-to-water heat exchanger will be on the order of 0.9 metre (3 feet) in diameter and 3 metres (10 feet) in length. Analysis indicates that the entire cooling system will easily fit into the existing Sandia Engineering Reactor Facility (SERF) building. The alloy Incoloy 800H appears to be the best candidate for the tube material in the helium-to-water heat exchanger. Type 316 stainless steel has been recommended for the shell of this heat exchanger. Estimates place the cost of the helium-to-water heat exchanger at approximately $100,000, the water-to-water heat exchanger at approximately $25,000, and the helium pump at approximately $450,000. The overall cost of the cooling system will approach $2 million

  14. Code system for fast reactor neutronics analysis

    International Nuclear Information System (INIS)

    Nakagawa, Masayuki; Abe, Junji; Sato, Wakaei.

    1983-04-01

    A code system for analysis of fast reactor neutronics has been developed for the purpose of handy use and error reduction. The JOINT code produces the input data file to be used in the neutronics calculation code and also prepares the cross section library file with an assigned format. The effective cross sections are saved in the PDS file with an unified format. At the present stage, this code system includes the following codes; SLAROM, ESELEM5, EXPANDA-G for the production of effective cross sections and CITATION-FBR, ANISN-JR, TWOTRAN2, PHENIX, 3DB, MORSE, CIPER and SNPERT. In the course of the development, some utility programs and service programs have been additionaly developed. These are used for access of PDS file, edit of the cross sections and graphic display. Included in this report are a description of input data format of the JOINT and other programs, and of the function of each subroutine and utility programs. The usage of PDS file is also explained. In Appendix A, the input formats are described for the revised version of the CIPER code. (author)

  15. Determination of uranium and thorium in semiconductor memory materials by high fluence neutron activation analysis

    International Nuclear Information System (INIS)

    Dyer, F.F.; Emery, J.F.; Northcutt, K.J.; Scott, R.M.

    1981-01-01

    Uranium and thorium were measured by absolute neutron activation analysis in high-purity materials used to manufacture semiconductor memories. The main thrust of the study concerned aluminum and aluminum alloys used as sources for thin film preparation, evaporated metal films, and samples from the Czochralski silicon crystal process. Average levels of U and Th were found for the source alloys to be approx. 65 and approx. 45 ppB, respectively. Levels of U and Th in silicon samples fell in the range of a few parts per trillion. Evaporated metal films contained about 1 ppB U and Th, but there is some question about these results due to the possibility of contamination

  16. Effect of low level doses of fast neutrons on the activity of the snake venom

    International Nuclear Information System (INIS)

    Hanafy, Magda S.; Amin, Aida M.

    1998-01-01

    In this work, the effect of low level doses of fast neutrons from 252 Cf on snake venom (Cerastes cerastes) was studied through measurements of biophysical and haematological changes. The absorption spectrum (200-700 nm) of haemoglobin (Hb) collected from the blood of rats after 3 and 24 hours post injection with irradiated and non-irradiated snake venom with neutron fluences of 3x10 6 , 2.8x10 7 and 3X10 8 n/cm 2 was measured. The results indicated that injection of animals with either non- irradiated or irradiated venom ( with different neutron fluences) resulted into the decrease of the absorption band intensities of Hb. These changes in the properties of the characteristic band showed to be a marker for irradiated venom and is dose dependent. It was concluded that neutron irradiation of the venom leads to the decrease of its toxicity and, consequently, to the increase of the chance of repair mechanism in livings. Obvious changes of most haematological erythrocytic values of Hb, packed cell volume (PCV), red blood counts (RBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCHb) and mean corpuscular haemoglobin concentration (MCHC) were observed in the blood of the rats injected with non-irradiated venom (as a first group) and those injected with the irradiated venom (as a second group). The microcytic haemolytic anemia was more acute in the first group than in the second one which showed lesser extent. It is concluded from this study that low level doses of fast neutrons could postpone and lower acute haematological action induced by the venom. (authors)

  17. Japanese experience with clinical trials of fast neutrons

    International Nuclear Information System (INIS)

    Tsunemoto, H.; Arai, T.; Morita, S.; Ishikawa, T.; Aoki, Y.; Takada, N.; Kamata, S.

    1982-01-01

    Between November, 1975 and November, 1981, 825 patients were treated with 30 MeV (d-Be) neutrons at the National Institute of Radiological Sciences, Chiba. At the Institute of Medical Science, Tokyo, 302 patients were referred to the Radiation Therapy department and were treated with 16 MeV (d-Be) neutrons. The emphasis of these clinical trials with fast neutrons was placed on the estimation of the effect of fast neutrons for locally advanced cancers or radioresistant cancers, and on evaluation of the rate of complication of normal tissues following irradiation with fast neutrons. Results were evaluated for patients with previously untreated cancer; local control of the tumor was observed in 59.1%. Complications requiring medical care developed in only 32 patients. Late reaction of soft tissue seemed to be more severe than that observed with photon beams. The results also suggest that for carcinoma of the larynx, esophagus, uterine cervix, Pancoast's tumor of the lung and osteosarcoma, fast neutrons were considered to be effectively applied in this randomized clinical trial. For carcinoma of the larynx, a fast neutron boost was effectively delivered, although an interstitial implant was necessarily combined with fast neutrons for carcinoma of the tongue. The cumulative survival rate of the patients with carcinoma of the esophagus treated with fast neutrons of 26% compared to the survival rate of 10.5% obtained using photons. The results also indicate that local control and relief of the symptom related to Pancoast's tumor of the lung seemed to be better with neutrons than with photons. For patients suffering from osteosarcoma, the surgical procedures preserving the function of the leg and arm were studied according to the better local control rate of the tumor following fast neutron beam therapy

  18. Effect of fast-neutron irradiation on plastic deformation of Type 304 stainless steel

    International Nuclear Information System (INIS)

    Yamada, H.

    1978-01-01

    Plastic deformation of EBR-II-irradiated Type 304 stainless steel was investigated by a stress-relaxation method. The stress-strain-rate relationships for the irradiated specimens at room temperature are concave upward, which are similar to those for the unirradiated specimens. However, concave downward behavior in the stress-strain-rate relationships were observed at much lower temperatures for the irradiated specimens in contrast to the unirradiated specimens. These results were analyzed succccessfully using Hart's mechanical equation-of-state concept. It was found that the hardness sigma*, which is the minimum stress necessary for the dislocation to overcome obstacles without thermal activation, increases linearly with fast-neutron fluence. This increase in sigma* is consistent with so-called ''irradiation hardening.'' In addition, resistance to dislocation glide, which is quantitatively measured in terms of sigma 0 , was observed to decrease linearly with fast-neutron fluence. The decrease in sigma 0 can be attributed to a decrease of solute drag due to irradiation-induced solute segregation

  19. An improved fast neutron radiography quantitative measurement method

    International Nuclear Information System (INIS)

    Matsubayashi, Masahito; Hibiki, Takashi; Mishima, Kaichiro; Yoshii, Koji; Okamoto, Koji

    2004-01-01

    The validity of a fast neutron radiography quantification method, the Σ-scaling method, which was originally proposed for thermal neutron radiography was examined with Monte Carlo calculations and experiments conducted at the YAYOI fast neutron source reactor. Water and copper were selected as comparative samples for a thermal neutron radiography case and a dense object, respectively. Although different characteristics on effective macroscopic cross-sections were implied by the simulation, the Σ-scaled experimental results with the fission neutron spectrum cross-sections were well fitted to the measurements for both the water and copper samples. This indicates that the Σ-scaling method could be successfully adopted for quantitative measurements in fast neutron radiography

  20. Television imaging system for fast neutron radiography using baby cyclotron

    International Nuclear Information System (INIS)

    Yoshii, Koji; Miya, Kenzo; Katoh, Norihiko.

    1993-01-01

    A television imaging system for fast neutron radiography (FNR-TV) developed using the fast neutron source reactor YAYOI was applied to the baby-cyclotron based fast neutron source to get images of thick objects quickly. In the system the same technique as a current television imaging system of thermal neutron radiography was applied, while the luminescent converter was used to detect fast neutrons. Using the CR39 track etch method it took about 7 h to get an image, while the FNR-TV only 20 s enough for taking the same object. However the FNR-TV imaging result of the simulation model of a large explosive device for the space launch vehicle of H-2 type was not so good as the image taken with the CR39 track etch method. The reason was that the luminescence intensity of the FNR-TV converter was a quarter of that in the YAYOI. (author)

  1. Neutron spectrum determination by activation method in fast neutron fields at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1994-01-01

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (author)

  2. Neutron spectrum determination by activation method in fast neutron fields at the RB reactors

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.S.; Pesic, M.P.; Antic, D.P.

    1994-01-01

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (authors). 7 refs., 3 tabs

  3. Generation of laser-induced fast neutron and its application

    International Nuclear Information System (INIS)

    Cha, Hyung Ki; Kwon, D. H.; Nam, S. M.

    2010-04-01

    The supply of high-efficiency neutron source is still problematic even though a fast neutron source is being accepted increasingly for industrial applications. Radioisotopes and a neutron tube are typically being used, but their neutron flux, lifetime, and price are the limiting factors for more diverse applications. As ultra high power, short pulse laser technologies have been developed, a neutron source generated via laser induced nuclear reaction comes to the fore. The laser induced neutron source has a high peak flux in comparison to the traditional neutron source and is like a point source with its diameter less than 1 mm. These properties can be utilized effectively for the analysis of pulsed fast neutron activation or the studies of a fast neutron material damage and/or recover. The purpose of R and D here is to develop a robust neutron source with a yield of 10 7 neutrons/s, and to carry out a preliminary research for application study in the next research stage

  4. Microhardness measurement in AISI 321 stainless steel with niobium additions before and after fast neutron irradiation

    International Nuclear Information System (INIS)

    Galli, V.L.; Lucki, G.

    1980-01-01

    Data about influence of neutron irradiation on the microhardness of stainless steel of type AISI 321 with 0.05 and 0.1wt.% Nb additions are presented. The microhardness measurements were made in the range of 300 to 650 0 C, before and after fast neutron irradiation with fluences about 10 17 n/cm 2 . Our results indicate that radiation damage peaks occur around 480 0 C for the stainless steel of type AISI 321 without Nb addition, around 500 0 C for the composition with 0.05 wt.% Nb addition and around 570 0 C for the composition with 0.1 wt.% Nb addition. Microhardness data are in agreement with those obtained by means of electrical resistivity measurements, performed at the same conditions. (Author) [pt

  5. New statistical model of inelastic fast neutron scattering

    International Nuclear Information System (INIS)

    Stancicj, V.

    1975-07-01

    A new statistical model for treating the fast neutron inelastic scattering has been proposed by using the general expressions of the double differential cross section in impuls approximation. The use of the Fermi-Dirac distribution of nucleons makes it possible to derive an analytical expression of the fast neutron inelastic scattering kernel including the angular momenta coupling. The obtained values of the inelastic fast neutron cross section calculated from the derived expression of the scattering kernel are in a good agreement with the experiments. A main advantage of the derived expressions is in their simplicity for the practical calculations

  6. Present status of fast neutron therapy for the malignant tumors

    Energy Technology Data Exchange (ETDEWEB)

    Tsunemoto, H; Morita, S; Honke, Y [National Inst. of Radiological Sciences, Chiba (Japan)

    1980-04-01

    Fast neutron therapy has been applied to the treatment of cancer of the head and the neck, prostatic cancer, osteosarcoma, and malignant melanoma, and the basic treatment schedule for this therapy for them has been almost established. The effectiveness of this therapy for squamous cell carcinoma of the uterus will be established by the results of future clinical application of this therapy. It is expected that postoperative irradiation of fast neutron will decrease local recurrence of adenocarcinoma of the uterus. Treatment schedule for fast neutron therapy for esophageal cancer and lung cancer must be established, and moreover, it is necessary to apply this therapy to the treatment of gastric and pancreatic cancer.

  7. Fast neutron spectrum measurement in the JMTR

    International Nuclear Information System (INIS)

    Sakurai, K.; Mizuho, M.

    1980-01-01

    Fast neutron spectrum measurement at positions of K-10 (fuel region), J-11 (first beryllium reflector region) and I-12 (second beryllium reflector region) in the JMTRC has been performed with the threshold detectors such as 107 Ag(n,n')sup(107m)Ag, 103 Rh(n,n')sup(103m)Rh, 115 In(n,n')sup(115m)In and 238 U(n,f)F.P. above 0.1 MeV energy region. The activity data have been analyzed by the unfolding code SAND-II using ANISN spectrum for initial spectrum. An effective cross section of 54 Fe(n,p) 54 Mn is calculated with Fabry's cross section data and SAND-II spectrum for K-10, J-11 and I-12. They are 76.7 mb, 69.0 mb and 68.2 mb for K-10, J-11 and I-12 respectively. These values agree with the effective cross sections (calculated by Fabry's cross section data and ANISN spectrum) within +-6%

  8. Medical use of fast neutrons in radiotherapy and radiography

    International Nuclear Information System (INIS)

    Bewley, D.K.

    1975-01-01

    Over 400 patients have been treated with fast neutrons from a cyclotron at Hammersmith Hospital, London, using 16 MeV deuterons on beryllium. A large variety of malignant disease is included in this trial. A randomized trial of fast neutron therapy for cancer of the mouth and throat is in progress and preliminary results will be given. Fast neutron radiographs are often taken to check the positions of the fields used on the patients. These show no contrast from bone, but demonstrate only the presence of gas-filled cavities. As a diagnostic method, fast neutron radiography suffers from a number of disadvantages, the main ones being lack of sensitivity of the image-forming system and the hazard to the patient due to a large Quality Factor. Estimation of the absorbed dose given to different types of tissue is an important factor in the medical use of fast neutrons. More data are needed on the processes whereby fast neutrons impart energy to matter, particularly for neutrons above 15 MeV

  9. Japanese experience with clinical trails of fast neutrons

    International Nuclear Information System (INIS)

    Tsunemoto, H.; Arai, T.; Morita, S.; Ishikawa, T.; Aoki, Y.; Takada, N.; Kamata, S.

    1982-01-01

    Between November, 1975 and November, 1981, 825 patients were treated with 30 MeV (d-Be) neutrons at the National Institute of Radiological Sciences, Chiba. At the Institute of Medical Science, Tokyo, 302 patients were referred to the Radiation Therapy department and were treated with 16 MeV (d-Be) neutrons. The emphasis of these clinical trials with fast neutrons was placed on the estimation of the effect of fast neutrons for locally advanced cancers or radioresistant cancers, and on evaluation of the rate of complication of normal tissues following irradiaton with fast neutrons. Results were evaluated for patients with previously untreated cancer; local control of the tumor was observed in 59.1%. Complications requiring medical care developed in only 32 patients. Patients who had received pre- or postoperative irradiation were excluded from this evaluation. Late reaction of soft tissue seemed to be more severe than that observed with photon beams. The results also suggest that for carcinoma of the larynx, esophagus, uterine cervix, Pancoasts's tumor of the lung and osteosarcoma, fast neutrons were considered to be effectively applied in this randomized clinical trial. For carcinoma of the larynx, a fast nuetron boost was effectively delivered, although an interstitial implant was necessarily combined with fast neutrons for carcinoma of the tongue. The cumulative survival rate of the patients with carcinoma of the esophagus treated with fast neutrons was 26% compared to the survival rate of 10.5% obtained using photons. This was supported by evidence from the pathological studies that showed that the tumor cells which had deeply invaded into the esophagus were effectively destroyed when fast neutrons were applied

  10. The vessel fluence; Fluence cuve

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    This book presents the proceedings of the technical meeting on the reactors vessels fluence. They are grouped in eight sessions: the industrial context and the stakes of the vessels control; the organization and the methodology for the fluence computation; the concerned physical properties; the reference computation methods; the fluence monitoring in an industrial context; vessels monitoring under irradiation; others methods in the world; the research and development programs. (A.L.B.)

  11. Experimental possibilities and fast neutron dose map of the fast neutron fields at the RB reactor facility

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.

    1993-01-01

    The RB is an unshielded, zero power nuclear facility with natural and enriched uranium fuel (2% and 80%) and D 2 O as moderator. It is possible to create different configurations of non-reflected and partially reflected critical systems and to make experiments in the fields of thermal neutrons. The fields of fast neutrons with 'softened' fission spectrum are made by modifying the system: modified experimental fuel channel EFC, coupled fast-thermal system in two configurations CFTS-1 and CFTS-2, coupled fast-thermal core HERBE. The intermediate and fast neutron absorbed doses in fast neutron fields are given. In first configuration of RB reactor it was almost impossible to perform dosimetric and other experiments. By creating these fields, with in our circumstances available fuel elements, the possibilities for different experiments are greatly improved. Now we can irradiate food samples, soil samples, electronic devices, study material properties, perform various dosimetry experiments, etc. (1 tab.)

  12. Fast neutron boost for the treatment of grade IV astrocytomas

    International Nuclear Information System (INIS)

    Breteau, N.; Destembert, B.; Favre, A.; Pheline, C.; Schlienger, M.

    1989-01-01

    A previous study, on grade IV astrocytomas, compared a combination of photons and fast neutron boost to photons only, both treatments being delivered following a concentrated irradiation schedule. A slight improvement in survival was observed after neutron boost for non operated patients, but not for operated patients. Since death was always related to local recurrence and since no complication occurred after neutron boost, the neutron dose was increased from 6 to 7 Gy in January 1985. No improvement in survival was observed for patients treated with neutron boost after complete resection. After subtotal resection, the group that was treated with the higher neutron boost (7 Gy) showed a significant benefit in survival at twelve months. When patients had only a biopsy before irradiation, there was a benefit in survival after neutron boost, but no additional benefit was gained when the size of the neutron boost was increased from 6 to 7 Gy. (orig.) [de

  13. Ionization signals from diamond detectors in fast-neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); CIVIDEC Instrumentation, Wien (Austria); Frais-Koelbl, H. [University of Applied Sciences, Wiener Neustadt (Austria); Griesmayer, E.; Kavrigin, P. [CIVIDEC Instrumentation, Wien (Austria); Vienna University of Technology, Wien (Austria)

    2016-09-15

    In this paper we introduce a novel analysis technique for measurements with single-crystal chemical vapor deposition (sCVD) diamond detectors in fast-neutron fields. This method exploits the unique electronic property of sCVD diamond sensors that the signal shape of the detector current is directly proportional to the initial ionization profile. In fast-neutron fields the diamond sensor acts simultaneously as target and sensor. The interaction of neutrons with the stable isotopes {sup 12}C and {sup 13}C is of interest for fast-neutron diagnostics. The measured signal shapes of detector current pulses are used to identify individual types of interactions in the diamond with the goal to select neutron-induced reactions in the diamond and to suppress neutron-induced background reactions as well as γ-background. The method is verified with experimental data from a measurement in a 14.3 MeV neutron beam at JRC-IRMM, Geel/Belgium, where the {sup 13}C(n, α){sup 10}Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the {sup 12}C(n, α){sup 9}Be reaction was substantially improved. The presented analysis technique is especially relevant for diagnostics in harsh radiation environments, like fission and fusion reactors. It allows to extract the neutron spectrum from the background, and is particularly applicable to neutron flux monitoring and neutron spectroscopy. (orig.)

  14. Evaluation of the fluence to dose conversion coefficients for high energy neutrons using a voxel phantom coupled with the GEANT4 code

    CERN Document Server

    Paganini, S

    2005-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from Galactic cosmic radiation. Crews of future high-speed commercial flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the male adult voxels phantom MAX, developed in the Nuclear Energy Department of Pernambuco Federal University in Brazil, has been coupled with the Monte Carlo simulation code GEANT4. This toolkit, distributed and upgraded from the international scientific community of CERN/Switzerland, simulates thermal to ultrahigh energy neutrons transport and interactions in the matter. The high energy neutrons are pointed as the component that contribute about 70% of the neutron effective dose that represent the 35% to 60% total dose at aircraft altitude. In this research calculations of conversion coefficients from fluence to effective dose are performed for neutrons of energies from 100 MeV ...

  15. Conceptual design, neutronic and radioprotection study of a fast neutron irradiation station at SINQ

    International Nuclear Information System (INIS)

    Zanini, L.; Baluc, N.; Simone, A. De; Eichler, R.; Joray, S.; Manfrin, E.; Pouchon, M.; Rabaioli, S.; Schumann, D.; Welte, J.; Zhernosekov, K.

    2011-12-01

    This comprehensive, illustrated report by the Paul Scherrer Institute PSI in Switzerland documents the proposals concerning the conceptual design, neutronic and radioprotection study of a fast neutron irradiation station at the PSI's Swiss Spallation Neutron Source SINQ facility. The need for fast neutron irradiation is discussed and the possibility of using SINQ as a fast neutron irradiation facility is considered. The production of isotopes, tracers and medical isotopes is discussed, as are fission and fusion reactor technologies. The characteristics of the neutron spectrum in SINQ are discussed. The neutronic and radioprotection calculations for an irradiation station at SINQ are looked at in detail and extensive examples of work done and results obtained are presented and discussed. Radioprotection issues are also looked at. Further contributions in the report cover the hot/cold irradiation station in the SINQ target. An appendix provides detailed drawings of the facility's pneumatic delivery system

  16. Triple GEM gas detectors as real time fast neutron beam monitors for spallation neutron sources

    International Nuclear Information System (INIS)

    Murtas, F; Claps, G; Croci, G; Tardocchi, M; Pietropaolo, A; Cippo, E Perelli; Rebai, M; Gorini, G; Frost, C D; Raspino, D; Rhodes, N J; Schooneveld, E M

    2012-01-01

    A fast neutron beam monitor based on a triple Gas Electron Multiplier (GEM) detector was developed and tested for the ISIS spallation neutron source in U.K. The test on beam was performed at the VESUVIO beam line operating at ISIS. The 2D fast neutron beam footprint was recorded in real time with a spatial resolution of a few millimeters thanks to the patterned detector readout.

  17. Interministerial decree of 10 February 1988 fixing the derived limits of the air concentration and the annual intake limit and the values of the quality factor and the neutron fluence rate

    International Nuclear Information System (INIS)

    1988-01-01

    This decree establishes the derived concentration limits in the air and annual inhalation limits for the radioisotopes and the values of the quality factors and the conversion factors fluence/dose equivalent for neutrons and protons

  18. Damages to gladiolu corm caused by fast neutron irradiation

    International Nuclear Information System (INIS)

    Zhang Zhiwei; Wang Dan; Zhang Dongxue; Zheng Chun

    2007-01-01

    Gladiolus corms were irradiated to 100-500kGy by fast neutrons in the CFBR-II pulsed reactor, Scanning electron microscope images of the irradiated samples revealed significant radiation damages to the gladiolus corms, and the mutagenic effects were studied by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Within the dose range, radiation damage to the corm increased with the dose, with corm epidermis of the samples irradiated in vertical incidence being more serious than those irradiated in side-incidence to the same dose. Biological characters were investigated via field experiments, and the bands of protein subunit were analyzed by SDS-PAGE. The results showed that the fast neutrons irradiation inhibited growth of M1 generation seedling significantly. Protein expression was obviously inhibited by the irradiation. The study indicates that fast neutron induction is an effective way for gladiolus breeding. And the results may lay a foundation for studies on fast neutron mutation breeding. (authors)

  19. Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl2O3

    International Nuclear Information System (INIS)

    Rahman, Abu Zayed Mohammad Saliqur; Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long; Xu, Qiu; Atobe, Kozo

    2014-01-01

    Highlights: •Detection of Al monovacancy by positron lifetime spectroscopy in fast neutron-irradiated MgO·nAl 2 O 3 (n=2). •Concentration of defects is also estimated for Al monovacancy. •O atom peak was observed by using coincidence Doppler broadening spectroscopy. -- Abstract: The positron lifetimes of fast-neutron-irradiated MgO·nAl 2 O 3 single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10 −3 m 0 c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies

  20. Indoor Fast Neutron Generator for Biophysical and Electronic Applications

    Science.gov (United States)

    Cannuli, A.; Caccamo, M. T.; Marchese, N.; Tomarchio, E. A.; Pace, C.; Magazù, S.

    2018-05-01

    This study focuses the attention on an indoor fast neutron generator for biophysical and electronic applications. More specifically, the findings obtained by several simulations with the MCNP Monte Carlo code, necessary for the realization of a shield for indoor measurements, are presented. Furthermore, an evaluation of the neutron spectrum modification caused by the shielding is reported. Fast neutron generators are a valid and interesting available source of neutrons, increasingly employed in a wide range of research fields, such as science and engineering. The employed portable pulsed neutron source is a MP320 Thermo Scientific neutron generator, able to generate 2.5 MeV neutrons with a neutron yield of 2.0 x 106 n/s, a pulse rate of 250 Hz to 20 KHz and a duty factor varying from 5% to 100%. The neutron generator, based on Deuterium-Deuterium nuclear fusion reactions, is employed in conjunction with a solid-state photon detector, made of n-type high-purity germanium (PINS-GMX by ORTEC) and it is mainly addressed to biophysical and electronic studies. The present study showed a proposal for the realization of a shield necessary for indoor applications for MP320 neutron generator, with a particular analysis of the transport of neutrons simulated with Monte Carlo code and described the two main lines of research in which the source will be used.

  1. Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor

    International Nuclear Information System (INIS)

    Yavar, A.R.; Sarmani, S.B.; Wood, A.K.; Fadzil, S.M.; Radir, M.H.; Khoo, K.S.

    2011-01-01

    Determination of thermal to fast neutron flux ratio (f fast ) and fast neutron flux (φ fast ) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The f fast and subsequently φ fast were determined using the absolute method. The f fast ranged from 48 to 155, and the φ fast was found in the range 1.03x10 10 -4.89x10 10 n cm -2 s -1 . These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.

  2. Development of fast neutron radiography system based on portable neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th [Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Rd., Patumwan, Bangkok, THAILAND 10330 (Thailand)

    2016-01-22

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  3. Irradiation of oxyhemoglobin and carboxyhemoglobin by fast neutrons

    International Nuclear Information System (INIS)

    AbdelBaset, M.S.; Salama, A.A.

    1991-01-01

    Oxyhemoglobin (Hbo 2 ) and carboxyhemoglobin (HbCO) (2.6x10 - 5 M) were subjected to Cf neutron fluences in the range of 10 - 10 n/cm . Irradiation caused partial conversion of oxyhemoglobin to methemoglobin according to the exposure doses. Also, the results indicated that the exposure of HbCO to neutrons leads to the cleavage of iron porphyrin-CO to free CO. After cleavage of 100% CO, the effect of neutrons is devoted to the oxidation of hemoglobin to methemoglobin. From the results presented in this study, it is concluded that HbCO is more radioresistant than HbO 2 . The main target in the case of HbCO is the iron-porphyrin-CO.2 tab.3 fig

  4. Semi-insulating GaAs detectors of fast neutrons

    International Nuclear Information System (INIS)

    Sagatova, A.; Sedlackova, K.; Necas, V.; Zatko, B.; Dubecky, F.; Bohacek, P.

    2012-01-01

    The present work deals with the technology of HDPE neutron conversion layer application on the surface of semi-insulating (SI) GaAs detectors via developed polypropylene (PP) based glue. The influence of glue deposition on the electric properties of the detectors was studied as well as the ability of the detectors to register the fast neutrons from "2"3"9Pu-Be neutron source. (authors)

  5. Conventional sources of fast neutrons in 'cold fusion' experiments

    International Nuclear Information System (INIS)

    Cribier, M.; Spiro, M.; Favier, J.

    1989-04-01

    In 'cold fusion' experiments with heavy water a source of neutrons is the dissociation of deuterium induced by alpha particles emitted by natural occurring radioisotopes. We evaluate the rate of fast neutron emission as a function of the concentration of U, Th, Rn in contact with deuterium and discuss the possibility that the neutrons claimed to have been observed in 'cold fusion' experiments could be due to this conventional source

  6. A fast neutron detector with IP by track measurement

    International Nuclear Information System (INIS)

    Miao Zhengqiang; Yang Jun; Zhang Qiang; Zhao Xiangfeng; Wang Daohua

    2004-01-01

    Imaging Plate(IP) is very sensitive to electric particles, especially to heavy ions. As we know, the recoiling protons are produced while fast neutrons scattered in light material containing hydrogen. When the recoiling proton enters in the sensitive layer of IP, a track will be recorded by IP. In this paper, a fast neutron detector based on IP and (n, p) reaction is described in detail, the detector's efficiency is studied also. (authors)

  7. Fast neutron activation analysis of Kalewa (Myanmar) coal

    Energy Technology Data Exchange (ETDEWEB)

    Myint, U; Naing, W [Yangon Univ. (Myanmar). Dept. of Chemistry

    1994-06-01

    Aluminium, silicon, copper, iron, magnesium and sulfur in Kalewa (Myanmar) coal were determined by fast neutron activation analysis. For activation a KAMAN A-710 Neutron Generator was used. Kalewa coal was found to be low in sulfur and relatively rich in iron. (author) 2 refs.; 1 fig.; 1 tab.

  8. Fast neutron activation analysis of Kalewa (Myanmar) coal

    International Nuclear Information System (INIS)

    Myint, U.; Naing, W.

    1994-01-01

    Aluminium, silicon, copper, iron, magnesium and sulfur in Kalewa (Myanmar) coal were determined by fast neutron activation analysis. For activation a KAMAN A-710 Neutron Generator was used. Kalewa coal was found to be low in sulfur and relatively rich in iron. (author) 2 refs.; 1 fig.; 1 tab

  9. Fast neutron fluxes distribution in Egyptian ilmenite concrete

    International Nuclear Information System (INIS)

    Megahed, R.M.; Abou El-Nasr, T.Z.; Bashter, I.I.

    1978-01-01

    This work is concerned with the study of the distribution of fast neutron fluxes in a new type of heavy concrete made from Egyptian ilmenite ores. The neutron source used was a collimated beam of reactor neutrons emitted from one of the horizontal channels of the ET-RR-1 reactor. Measurements were carried-out using phosphorous activation detectors. Iso-flux curves were represented which give directly the shape and thickness required to attenuate the emitted fast neutron flux to a certain value. The relaxation lengths were also evaluated from the measured data for both disc monodirectional source and infinite plane monodirectional source. The obtained values were compared with that calculated using the derived values of relative number densities and microscopic removal cross-sections of the different constituents. The obtained data show that ilmenite concrete attenuates fast neutron flux more strongly than ordinary concrete. A semiemperical formula was derived to calculate the fast neutron flux at different thicknesses along the beam axis. Another semiemperical formula was also derived to calculate the fast neutron flux in ordinary concrete along the beam axis using the corresponding value in ilmenite concrete

  10. Correlation properties of delayed neutrons from fast neutron induced fission

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Isaev, S.G.

    1998-01-01

    The experimental studies of the energy dependence of the delayed neutron parameters for various fissioning systems has shown that the behavior of a some combination of delayed neutron parameters (group relative abundances a i and half lives T i ) has a similar features. On the basis of this findings the systematics of delayed neutron experimental data for thorium, uranium, plutonium and americium isotopes have been investigated with the purpose to find a correlation of DN parameters with characteristics of fissioning system as well as a correlation between the delayed neutron parameters themselves. Below we will present the preliminary results which were obtained during this study omitting the physics interpretation of the results. (author)

  11. Delayed neutron yield from fast neutron induced fission of 238U

    International Nuclear Information System (INIS)

    Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Roshchenko, V.A.; Goverdovski, A.A.; Tertytchnyi, R.G.

    2002-01-01

    The measurements of the total delayed neutron yield from fast neutron induced fission of 238 U were made. The experimental method based on the periodic irradiation of the fissionable sample by neutrons from a suitable nuclear reaction had been employed. The preliminary results on the energy dependence of the total delayed neutron yield from fission of 238 U are obtained. According to the comparison of experimental data with our prediction based on correlation properties of delayed neutron characteristics, it is concluded that the value of the total delayed neutron yield near the threshold of (n,f) reaction is not a constant. (author)

  12. Fast neutron sensitivity of polymer dosemeters

    International Nuclear Information System (INIS)

    Harper, M.W.; Pearson, D.W.; Moran, P.R.

    1975-01-01

    The responses of polymer thermocurrent dosemeters to fission spectrum and 14 MeV neutrons were measured. The dosemeters are in the form of disks 1 cm diam by 0.5 mm thick. Relative to Cobalt 60 gamma responses, teflon PTFE dosemeters show a 6 percent response to 14 MeV neutrons and a 5 percent response to fission neutrons on a tissue rad basis. Polymethylpentene dosemeters show a 49 percent response to 14 MeV neutrons and a 40 percent response to fission neutrons on a tissue rad basis when provided with adequate recoil proton buildup. The sensitivity of these dosemeters is limited to neutron doses greater than 10 rads by spurious background currents

  13. Specification of fast neutron radiation quality from cell transformation data

    International Nuclear Information System (INIS)

    Coppola, M.

    1992-01-01

    Experimental data on the neoplastic transformation of C3H 10T1/2 cells measured at Casaccia after neutron and X-ray irradiation were used to determine neutron RBE values for the RSV-Tapiro fast reactor energy spectrum and for monoenergetic neutrons of 0.5, 1, and 6 MeV. In parallel, micro-dosimetric measurements provided the actual lineal energy distributions and related mean parameters for the reactor radiation. From these experiments, values of the neutron quality factor were derived for the reactor neutron energy spectrum and, in turn, for the other neutron energies tested. A mathematical expression giving a smooth dependence on neutron energy was also determined for the effective quality factor in the entire energy range examined. The results were compared with other proposals

  14. Effect of Fast Neutron to MA/PU Burning/Transmutation Characteristic Using a Fast Reactor

    International Nuclear Information System (INIS)

    Marsodi; Lasman, As Natio; Kimamoto, A.; Marsongkohadi; Zaki, S.

    2003-01-01

    MA/Pu burning/transmutation has been studied and evaluated using fast neutrons. Generally, neutron density at this fast burner reactor and transmutation has spectrum energy level around 0.2 MeV with wide enough variation, i.e. from low neutron spectrum to its peak is 0.2 MeV. This neutron spectrum energy level depends on the kind of cooler material or fuel used. Neutron spectrum higher than fast power reactor neutron spectrum is found by means of changing oxide fuel by metallic fuel and changing natrium cooler material by metallic or gas cooler material. This evaluation is conducted by various variations in accordance with the kind of fuel or cooler, MA/Pu fractions and fuel comparison fraction with respect to its cooler in order to get better neutron usage and MA/Pu burning speed. Reactor calculation evaluation in this paper was conducted with 26-group nuclear data cross section energy spectrum. The main purpose of the discussion is to know the effect of fast neutrons to burning/transmutation MA/Pu using fast neutrons

  15. A new neutron noise technique for fast reactors

    International Nuclear Information System (INIS)

    Zhuo Fengguan; Jin Manyi; Yao Shigui; Su Zhuting

    1987-12-01

    This paper gives a new neutron noise technique for fast reactors, which is known as thermalization measurement technique of the neutron noise. The theoretical formulas of the technique were developed, and a digital delayed coincidence time analyzer consisted of TTL integrated circuits was constructed for the study of this technique. The technique has been tested and applied practically at Df-VI fast zero power reactor. It was shown that the provided technique in this work has a number of significant advantages in comparison with the conventional neutron noise method

  16. Modeling delayed neutron monitoring systems for fast breeder reactors

    International Nuclear Information System (INIS)

    Bunch, W.L.; Tang, E.L.

    1983-10-01

    The purpose of the present work was to develop a general expression relating the count rate of a delayed neutron monitoring system to the introduction rate of fission fragments into the sodium coolant of a fast breeder reactor. Most fast breeder reactors include a system for detecting the presence of breached fuel that permits contact between the sodium coolant and the mixed oxide fuel. These systems monitor for the presence of fission fragments in the sodium that emit delayed neutrons. For operational reasons, the goal is to relate the count rate of the delayed neutron monitor to the condition of the breach in order that appropriate action might be taken

  17. Investigation of Response of Several Neutron Surveymeters by a DT Neutron Generator

    International Nuclear Information System (INIS)

    Kim, Sang In; Jang, In Su; Kim, Jang Lyul; Lee, Jung IL; Kim, Bong Hwan

    2012-01-01

    Several neutron measuring devices were tested under the neutron fields characterized with two distinct kinds of thermal and fast neutron spectrum. These neutron fields were constructed by the mixing of both thermal neutron fields and fast neutron fields. The thermal neutron field was constructed using by a graphite pile with eight AmBe neutron sources. The fast neutron field of 14 MeV was made by a DT neutron generator. In order to change the fraction of fast neutron fluence rate in each neutron fields, a neutron generator was placed in the thermal neutron field at 50 cm and 150 cm from the reference position. The polyethylene neutron collimator was used to make moderated 14 MeV neutron field. These neutron spectra were measured by using a Bonner sphere system with an LiI scintillator, and dosimetric quantities delivered to neutron surveymeters were determined from these measurement results.

  18. The Effect of Radiator on CR-39 Registration of Fast Neutrons

    International Nuclear Information System (INIS)

    El-Badrya, B.A.; Hegazya, T.M.; Morsya, A.A.; Zaki, M.F.

    2008-01-01

    Three different configurations of a personal neutron dosimeter using CR-39 plastic detector were placed in Plastiplast pouch composed from inside to outside of Aluminum ( 27 Al, 40 Ξ m), polyethylene (PE, 20 Ξ m), Cellulose Nitrate (CN, 40 Ξ m). One dosimeter was composed of a CR-39 detector and a PE radiator (1 mm thick), another of two CR-39 detectors with one serving as radiator, and the other of CR-39 alone (without radiator). These dosimeters have been irradiated with fast neutrons of average energy 4.5 MeV with neutron fluence ranging from 5.5 x 10 6 to 0.5 x 10 8 cm - 2 emitted from 241 Am-Be neutron source. The polymeric materials have been chosen on the basis of their hydrogen contents, which are as followed: CR-39, 48%, Polyethylene, 66.7% and CN, 32% by atomic ratio to produce protons via (n, p) elastic scattering with hydrogen and increasing the detection efficiency of CR-39. After irradiation, the dose equivalent response of the detectors has been studied by using conventional etching for two periods, 6h and 8h for these configurations. The thicknesses and compositions of the radiators are chosen so as to suppress the CR-39 response below 4 MeV by preventing the recoils of hydrogen nuclei, out of the hydrogen-rich radiators (PE, CR-39), from reaching the post-etch surface of the detector. Track counting was performed using an automated system. It was found that the dosemeter responses were linear as a function of a neutron equivalent dose and that the CR-39 detector has the same response with radiator or without radiator and thus appears as a promising fast neutron dosimeter. The results are discussed and compared with the literature

  19. An attempt to fabricate an ion injection type fast neutron dosimeter

    International Nuclear Information System (INIS)

    Pells, G.P.; Hughes, A.E.

    1976-10-01

    This report describes the results of work carried out to investigate a novel type of solid state, fast neutron dosimeter. The concept and quantitative features of the dosimeter, in which collisions between fast neutrons and ions in a source compound cause the ions to be injected into a host compound where they could then be detected by their characteristic luminescence, are described. It is shown that with the aid of a complex reader mrad sensitivities should in principle be possible. Initial experiments showed that accelerator implantation of Bi 3+ ions into CaO gives a linear dependence of luminescence output with fluence of activator ions. A number of host/activator combinations were investigated from which SiO 2 :Gd 3+ appeared the most promising. Host/activator configurations are briefly considered. The production of compacts of SiO 2 and Gd 2 O 3 ultrafine powders is described. Attempts were made to characterise these compacts using scanning electron microscopy and luminescence spectroscopy. After fast neutron irradiation to 250 Mrad no Gd 3+ ion injection could be detected. An alternative configuration of ultrafine SiO 2 powder dispersed in a solid Gd(NO 3 ) 3 .5H 2 O matrix is described but again no Gd 3+ ion injection into the SiO 2 could be detected after fast neutron irradiation. Perspex, as a host, was also tried without success. An appendix is included which demonstrates that the lack of success in detecting ion-injection may be largely due to the optically opaque nature of the specimens that could be produced. (author)

  20. Fast counting electronics for neutron coincidence counting

    International Nuclear Information System (INIS)

    Swansen, J.E.

    1987-01-01

    This patent describes a high speed circuit for accurate neutron coincidence counting comprising: neutron detecting means for providing an above-threshold signal upon neutron detection; amplifying means inputted by the neutron detecting means for providing a pulse output having a pulse width of about 0.5 microseconds upon the input of each above threshold signal; digital processing means inputted by the pulse output of the amplifying means for generating a pulse responsive to each input pulse from the amplifying means and having a pulse width of about 50 nanoseconds effective for processing an expected neutron event rate of about 1 Mpps: pulse stretching means inputted by the digital processing means for producing a pulse having a pulse width of several milliseconds for each pulse received form the digital processing means; visual indicating means inputted by the pulse stretching means for producing a visual output for each pulse received from the digital processing means; and derandomizing means effective to receive the 50 ns neutron event pulses from the digital processing means for storage at a rate up to the neutron event rate of 1 Mpps and having first counter means for storing the input neutron event pulses

  1. Plastic fiber scintillator response to fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Danly, C. R.; Sjue, S.; Wilde, C. H.; Merrill, F. E.; Haight, R. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2014-11-15

    The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.

  2. Elemental analysis of fertilizer by fast neutron activation

    International Nuclear Information System (INIS)

    Bodart, F.; Deconninck, G.

    1977-01-01

    A simple and accurate technique has been developed to analyse commercial fertilizers for phosphorus, potassium, chlorine, magnesium and silicon. The method is based on fast-neutron activation using a neutron flux of 2x10 11 neutrons/second. The optimum analytical conditions are tabulated. After irradiation, the sample is measured on a conventional counting system including a Ge(Li) detector (10% efficiency and 2 keV resolution for 60 Co) and a multichannel analyser. Monitor foils radioactivity are measured separately at the same time with a 2''x2''NaI detector coupled with a single channel analyser and a scaler. Fast neutron activation has proved to be a fast, simple, reliable and low cost analytical technique for the determination of phosphorus, silicon, potassium, magnesium and chlorine in fertilizers. Not less than five phosphorus determinations are possible in one hour, while two potassium, magnesium and chlorine determinations are made at the same time. (T.G.)

  3. Fast neutron radiation inactivation of Bacillus subtilis: Absorbed dose determination

    International Nuclear Information System (INIS)

    Song Lingli; Zheng Chun; Ai Zihui; Li Junjie; Dai Shaofeng

    2011-01-01

    In this paper, fast neutron inactivation effects of Bacillus subtilis were investigated with fission fast neutrons from CFBR-II reactor of INPC (Institute of Nuclear Physics and Chemistry) and mono-energetic neutrons from the Van de Graaff accelerator at Peking University. The method for determining the absorbed dose in the Bacillus subtilis suspension contained in test tubes is introduced. The absorbed dose, on account of its dependence on the volume and the form of confined state, was determined by combined experiments and Monte Carlo method. Using the calculation results of absorbed dose, the fast neutron inactivation effects on Bacillus subtilis were studied. The survival rates and absorbed dose curve was constructed. (authors)

  4. Absorbing rods for nuclear fast neutron reactor absorbing assembly

    International Nuclear Information System (INIS)

    Aji, M.; Ballagny, A.; Haze, R.

    1986-01-01

    The invention proposes a neutron absorber rod for neutron absorber assembly of a fast neutron reactor. The assembly comprises a bundle of vertical rods, each one comprising a stack of pellets made of a neutron absorber material contained in a long metallic casing with a certain radial play with regard to this casing; this casing includes traps for splinters from the pellets which may appear during reactor operation, at the level of contact between adjacent pellets. The present invention prevents the casing from rupture involved by the disintegration of the pellets producing pieces of boron carbide of high hardness [fr

  5. Fast neutron activation analysis at Texas A and M University

    International Nuclear Information System (INIS)

    James, W.D.

    1997-01-01

    Fast neutron generators are used at Texas A and M University to provide a supply of high energy neutrons for nuclear analytical measurements. A series of neutron activation analysis procedures have been developed for determining various major, minor and trace constituents in a variety of materials. These procedures are primarily developed to compliment our reactor based NAA program, thereby expanding the list of determinable elements to include those difficult or impossible to measure using thermal neutrons. A few typical methods are discussed. The unique implementation of the methodologies at Texas A and M are explained. (author)

  6. Dosimetric properties of the fast neutron therapy beams at TAMVEC

    International Nuclear Information System (INIS)

    Almond, P.R.; Smith, A.R.; Smathers, J.R.; Otte, V.A.

    1975-01-01

    In October 1972, M.D. Anderson Hospital and Tumor Institute of the University of Texas System Cancer Center initiated a clinical trial of fast neutron radiotherapy using the cyclotron at Texas A and M University. Initially, the study used neutrons produced by bombarding beryllium with 16 MeV deuterons, but since March, 1973, neutrons from 50 MeV deuterons have been used. The dosimetric properties of the 30 MeV beams have also been measured for comparison with the neutron beams from D-T generators. The three beams are compared in terms of dose rate, skin sparing, depth dose and field flatness. Isodose curves for treatment planning were generated using the decrement line method and compared to curves measured by a computer controlled isodose plotter. This system was also used to measure the isodose curves for wedge fields. Dosimetry checks on various patients were made using silicon diodes as in vivo fast neutron dosimeters

  7. Seminar on Heat-transfer fluids for fast neutron reactors

    International Nuclear Information System (INIS)

    Brechet, Yves; Dautray, Robert; Friedel, Jacques; Brezin, Edouard; Martin, Georges; Pineau, Andre; Carre, Francois; Gauche, Francois; Rodriguez, Guillaume; Latge, Christian; Cabet, Celine; Garnier, Jean-Claude; Bamberger, Yves; Sauvage, Jean-Francois; Buisine, Denis; Agostini, Pietro; Ulyanov, Vladimir; Auger, Thierry; Heuer, Daniel; Ghetta, Veronique; Bubelis, Evaldas; Charlaix, Elisabeth; Barrat, Jean-Louis; Boquet, Lyderic; Glickman, Evgueny; Escaravage, Claude

    2014-03-01

    This book reports the content of a two-day meeting held by the Academy of Sciences on the use of heat-transfer fluids in fast neutron reactors. After a first part which proposes an overview of scientific and technical problems related to these heat-transfer fluids (heat transfer process, nuclear properties, chemistry, materials, risks), a contribution proposes a return on experience on the use of heat-transfer fluids in the different design options of reactors of fourth generation: from mercury to NaK in the first fast neutron reactor projects, specific assets and constraints of sodium used as heat-transfer fluid, concepts of fast neutron reactors cooled by something else than sodium, perspectives for projects and research in fast neutron reactors. The next contribution discusses the specifications of future fast-neutron reactors: expectations for fourth-generation reactors, expectations in terms of performance and of safety, specific challenges. The last contribution addresses actions to be undertaken in the field of research and development: actions regarding all reactor types or specific types as sodium-cooled reactors, lead cooled reactors, molten salt reactors, and gas-cooled fast reactors

  8. System design considerations for fast-neutron interrogation systems

    International Nuclear Information System (INIS)

    Micklich, B.J.; Curry, B.P.; Fink, C.L.; Smith, D.L.; Yule, T.J.

    1993-01-01

    Nonintrusive interrogation techniques that employ fast neutrons are of interest because of their sensitivity to light elements such as carbon, nitrogen, and oxygen. The primary requirement of a fast-neutron inspection system is to determine the value of atomic densities, or their ratios, over a volumetric grid superimposed on the object being interrogated. There are a wide variety of fast-neutron techniques that can provide this information. The differences between the various nuclear systems can be considered in light of the trade-offs relative to the performance requirements for each system's components. Given a set of performance criteria, the operational requirements of the proposed nuclear systems may also differ. For instance, resolution standards will drive scanning times and tomographic requirements, both of which vary for the different approaches. We are modelling a number of the fast-neutron interrogation techniques currently under consideration, to include Fast Neutron Transmission Spectroscopy (FNTS), Pulsed Fast Neutron Analysis (PFNA), and its variant, 14-MeV Associated Particle Imaging (API). The goals of this effort are to determine the component requirements for each technique, identify trade-offs that system performance standards impose upon those component requirements, and assess the relative advantages and disadvantages of the different approaches. In determining the component requirements, we will consider how they are driven by system performance standards, such as image resolution, scanning time, and statistical uncertainty. In considering the trade-offs between system components, we concentrate primarily on those which are common to all approaches, for example: source characteristics versus detector array requirements. We will then use the analysis to propose some figures-of-merit that enable performance comparisons between the various fast-neutron systems under consideration. The status of this ongoing effort is presented

  9. Fast Neutrons - LET Distributions and the Response of Mammalian Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bewley, D. K. [Medical Research Council Cyclotron Unit, Hammersmith Hospital, London (United Kingdom)

    1968-03-15

    Distributions of stopping power (LET) are given for four beams of fast neutrons, namely, neutrons of 14.6 MeV, neutrons produced by bombarding a thick beryllium target with 15 MeV deuterons, neutrons of 3 MeV, and fast neutrons produced by bombardment of a {sup 235}U converter plate with thermal neutrons. The track average LET is correlated with mean neutron energy, but the dose average is approximately constant. However, neither of these types of average is expected to have much relevance to radiobiology. Further, specification of a ''biologically effective LET'' depends on the biological test used, and is not solely a function of the radiation quality. An attempt has been made to calculate the response of T.I. kidney cells in tissue culture to these four beams of neutrons, based on their response to charged particles using the track-segment method. The calculated RBE's of the neutron beams are lower than the observed values and the calculated values of the oxygen enhancement ratio are higher. These differences seem too great to be explained by errors in dosimetry and in the calculated LET spectra. The suggestion is made that LET is not an adequate criterion of radiation quality, and that the discrepancies may be explained by more detailed consideration of the part played by delta rays and by heavy recoil tracks of short range. (author)

  10. Pulsed thermal neutron source at the fast neutron generator.

    Science.gov (United States)

    Tracz, Grzegorz; Drozdowicz, Krzysztof; Gabańska, Barbara; Krynicka, Ewa

    2009-06-01

    A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14 MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal neutron intensity and the short decay time of the thermal neutron flux. The source has been built and the test experiments have been performed. To ensure the response is not due to the choice of target for the experiments, calculations have been done to demonstrate the response is valid regardless of the thermalization properties of the target.

  11. Neutron intensity of fast reactor spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Takamatsu, Misao; Aoyama, Takafumi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-03-01

    Neutron intensity of spent fuel of the JOYO Mk-II core with a burnup of 62,500 MWd/t and cooling time of 5.2 years was measured at the spent fuel storage pond. The measured data were compared with the calculated values based on the JOYO core management code system `MAGI`, and the average C/E approximately 1.2 was obtained. It was found that the axial neutron intensity didn`t simply follow the burnup distribution, and the neutron intensity was locally increased at the bottom end of the fuel region due to an accumulation of {sup 244}Cm. (author)

  12. Fast-neutron scattering from elemental cadmium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1982-07-01

    Neutron differential-elastic-scattering cross sections of elemental cadmium are measured from approx. = 1.5 to 4.0 MeV at incident-neutron energy intervals of 50 to 200 keV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Concurrently, lumped-level neutron inelastic-excitation cross sections are measured. The experimental results are used to deduce parameters of an optical-statistical model that is descriptive of the observables and are compared with corresponding quantities given in ENDF/B-V

  13. Preliminary examination of the applicability of imaging plates to fast neutron radiography

    International Nuclear Information System (INIS)

    Matsubayashi, Masahito; Hibiki, Takashi; Mishima, Kaichiro; Yoshii, Koji; Okamoto, Koji

    2001-01-01

    Fast neutron radiography is an attractive non-destructive inspection technique because of the excellent penetration characteristics of fast neutrons in matter. However, the difficulty of detecting fast neutrons reduces this attractive feature. As an experiment to overcome the difficulty, imaging plates were applied to fast neutron radiography. A simple combination of two sheets of imaging plates and a sheet of polyethylene as a proton emitter was examined with the (fast neutron, thermal neutron and gamma ray) FTG discriminator proposed by Yoneda et al. . The experimental results showed that the method could be applicable to fast neutron radiography with effective discrimination of γ-rays

  14. High resolution fast neutron spectrometry without time-of-flight

    International Nuclear Information System (INIS)

    Evans, A.E.; Brandenberger, J.D.

    1978-01-01

    Performance tests of a spectrometer tube of the type developed by Cuttler and Shalev show that the measurement of fast neutron spectra with this device can be made with an energy resolution previously obtainable only in large time-of-flight facilities. In preliminary tests, resolutions of 16.4 keV for thermal neutrons and 30.9 keV for 1-MeV neutrons were obtained. A broad-window pulse-shape discrimination (PSD) system is used to remove from pulse-height distributions most of the continua due to 3 He-recoil events, noise, and wall effect. Use of PSD improved the energy resolution to 12.9 keV for thermal neutrons and 29.2 keV for 1-MeV neutrons. The detector is a viable tool for neutron research at nominally equipped accelerator laboratories

  15. Scattering of fast neutrons from elemental molybdenum

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1982-11-01

    Differential broad-resolution neutron-scattering cross sections of elemental molybdenum were measured at 10 to 20 scattering angles distributed between 20 and 160 degrees and at incident-neutron energy intervals of approx. = 50 to 200 keV from 1.5 to 4.0 MeV. Elastically-scattered neutrons were fully resolved from inelastic events. Lumped-level inelastic-neutron-scattering cross sections were determined corresponding to observed excitation energies of; 789 +- 23, 195 +- 23, 1500 +- 34, 1617 +- 12, 1787, 1874, 1991, 2063 +- 24, 2296, 2569 and 2802 keV. An optical-statistical model was deduced from the measured elastic-scattering results. The experimental values were compared with the respective quantities given in ENDF/B-V

  16. Dosimetry intercomparisons between fast neutron radiotherapy facilities

    International Nuclear Information System (INIS)

    Almond, P.R.; Smith, A.R.; Smathers, J.B.; Otte, V.A.

    1975-01-01

    Neutron dosimetry intercomparisons have been made between M.D. Anderson Hospital and Tumor Institute, Naval Research Laboratory, University of Washington Hospital, and Hammersmith Hospital. The parameters that are measured during these visits are: tissue kerma in air, tissue dose at depth of dose maximum, depth dose, beam profiles, neutron/gamma ratios and photon calibrations of ionization chambers. A preliminary report of these intercomparisons will be given including a comparison of the calculation and statement of tumor doses for each institution

  17. Determination of contraband using fast neutron resonance technique

    Energy Technology Data Exchange (ETDEWEB)

    Bae, J.; Whang, J. [Kyunghee Univ., Dept. of Nuclear Engineering, Yongin-shi, Kyongki-do (Korea, Republic of)

    2004-07-01

    'Full-text:' Resonance technique with monoenergetic fast neutron beam is able to map features in bulk samples in a way that is sensitive to their elemental composition. It has a number of potential applications, for example, in mining and in the detection of contraband materials such as illicit drugs and explosives. By moving around the neutron detector experiences neutrons in the form of narrow line beam with different energies as the angle to the neutron source changes. Projection data was obtained using the Monte Carlo code MCNP4C. Therefore the fast neutrons scattered from an unknown object are used to determine the elemental content of the object and hence lead to its identification. Scattered features simulated for various test materials are analyzed using the HEPRO program system (PTB, Braunschweig) to determine the atom weight fractions for H. C. N, O and other elements in the materials. Atom weight fractions determined from scattering features are insensitive to neutron interactions in interfering materials surrounding the object. The simulations demonstrate that the fast neutron resonance technique (FNRT) provides reliable elemental characterization of bulk materials and has the necessary sensitivity to distinguish between drugs, explosives and other materials. (author)

  18. Determination of contraband using fast neutron resonance technique

    International Nuclear Information System (INIS)

    Bae, J.; Whang, J.

    2004-01-01

    'Full-text:' Resonance technique with monoenergetic fast neutron beam is able to map features in bulk samples in a way that is sensitive to their elemental composition. It has a number of potential applications, for example, in mining and in the detection of contraband materials such as illicit drugs and explosives. By moving around the neutron detector experiences neutrons in the form of narrow line beam with different energies as the angle to the neutron source changes. Projection data was obtained using the Monte Carlo code MCNP4C. Therefore the fast neutrons scattered from an unknown object are used to determine the elemental content of the object and hence lead to its identification. Scattered features simulated for various test materials are analyzed using the HEPRO program system (PTB, Braunschweig) to determine the atom weight fractions for H. C. N, O and other elements in the materials. Atom weight fractions determined from scattering features are insensitive to neutron interactions in interfering materials surrounding the object. The simulations demonstrate that the fast neutron resonance technique (FNRT) provides reliable elemental characterization of bulk materials and has the necessary sensitivity to distinguish between drugs, explosives and other materials. (author)

  19. Test of Fibre Bragg Gratings samples under High Fast Neutrons Fluence

    Directory of Open Access Journals (Sweden)

    Cheymol G.

    2018-01-01

    The measurements show that for nearly all gratings the Bragg peak remains visible after the irradiation, and that Radiation Induced Bragg Wavelength Shifts (RI-BWSs vary from few pm (equivalent to an error of less than 1°C for a temperature sensor to nearly 1 nm (equivalent to 100°C depending of the FBG types. High RI-BWSs could indeed be expected when considering the huge refractive index variation and compaction of the bare fibre samples that have been measured by other techniques. Post writing thermal annealing is confirmed as a key parameter in order to obtain a more radiation tolerant FBG. Our results show that specific annealing regimes allow making FGBs suitable to perform temperature measurements in a MTR experiment.

  20. Studies of the dependence on oxidation thermal processes of effects on the electrical properties of silicon detectors by fast neutron radiation

    International Nuclear Information System (INIS)

    Li, Zheng; Kraner, H.W.

    1991-11-01

    High resistivity silicon detectors along with MOS capacitors made on five silicon dioxides with different thermal conditions (975 degree C to 1200 degree C) have been exposed to fast neutron irradiation up to the fluence of a few times 10 14 n/cm 2 . New measurement techniques such as capacitance-voltage (C-V) of MOS capacitors and current-voltage (I-V) of back to back diodes (p + -n - - p + if n - is not inverted to p) or resistors (p + -p-p + if inverted) have been introduced in this study in monitoring the possible type-inversion (n→p) under high neutron fluence. No type-inversion in the material underneath SiO 2 and the p + contact has been observed so far in this work for detectors made on the five oxides up to the neutron fluence of a few times 10 13 n/cm 2 . However, it has been found that detectors made on higher temperature oxides (T≤ 1100 degree C) exhibit less leakage current increase at high neutron fluence (φ ≤ 10 13 n/cm 2 )

  1. Monte Carlo evaluation of a photon pencil kernel algorithm applied to fast neutron therapy treatment planning

    Science.gov (United States)

    Söderberg, Jonas; Alm Carlsson, Gudrun; Ahnesjö, Anders

    2003-10-01

    When dedicated software is lacking, treatment planning for fast neutron therapy is sometimes performed using dose calculation algorithms designed for photon beam therapy. In this work Monte Carlo derived neutron pencil kernels in water were parametrized using the photon dose algorithm implemented in the Nucletron TMS (treatment management system) treatment planning system. A rectangular fast-neutron fluence spectrum with energies 0-40 MeV (resembling a polyethylene filtered p(41)+ Be spectrum) was used. Central axis depth doses and lateral dose distributions were calculated and compared with the corresponding dose distributions from Monte Carlo calculations for homogeneous water and heterogeneous slab phantoms. All absorbed doses were normalized to the reference dose at 10 cm depth for a field of radius 5.6 cm in a 30 × 40 × 20 cm3 water test phantom. Agreement to within 7% was found in both the lateral and the depth dose distributions. The deviations could be explained as due to differences in size between the test phantom and that used in deriving the pencil kernel (radius 200 cm, thickness 50 cm). In the heterogeneous phantom, the TMS, with a directly applied neutron pencil kernel, and Monte Carlo calculated absorbed doses agree approximately for muscle but show large deviations for media such as adipose or bone. For the latter media, agreement was substantially improved by correcting the absorbed doses calculated in TMS with the neutron kerma factor ratio and the stopping power ratio between tissue and water. The multipurpose Monte Carlo code FLUKA was used both in calculating the pencil kernel and in direct calculations of absorbed dose in the phantom.

  2. The study of creep in stainless steel irradiated with fast neutron and alpha particles

    International Nuclear Information System (INIS)

    Correa, D.A.C.

    1985-01-01

    The objective of the present work is to study the creep behavior of the 316 type stainless steel 50% cold worked in different conditions of temperature and applied stress, after neutron radiation and Alfa particles implantation. For this experiment, non-irradiated samples, samples irradiated in the research reactor IEA-R1 with fast neutron (E≥ MeV) up to a fluence of 8.6.10 17 n/cm 2 , and samples implanted with Alfa particles in the cyclotron CV-28 with Helium concentrations of 5 and 26 appm, were creep tested with applied stresses of the 200-300 MPa at temperatures between 650 0 C and 700 0 C. The deformation versus time curves were plotted and it was observed tha the second stage is not well defined, with the creep rate increasing continuously until the occurrence of failure of the material. The study of the effect of increase from 200 MPa to 300 MPa at the same temperature was performed. It can be concluded that this increase produces an approximately 70% reductions in the fracture time of the material, with practically no influence in the total deformation. Samples were tested at different temperatures (650, 675 and 700 0 C) at a same applied stress (200 MPa). It has been observed that a temperature of 50 0 C produces 98,9% of reduction in the fracture time and almost doubles the total deformation. On neutron irradiated samples, creep tests were performed at the same temperature and stress of the non irradiated samples. Comparing the results obtained a tendency of embrittlement due to the neutron irradiation can be observed; no remarkable structure changes were detected due to small fast neutron. Microstructural and metalographic observations were performed before and after each creep test. (author) [pt

  3. Beam profiles for fast neutrons; and reply

    International Nuclear Information System (INIS)

    Bewley, D.K.; Parnell, C.J.; Bloch, P.

    1976-01-01

    The authors express surprise that Bloch et al. (Bloch, P.H., Hendry, G.O., Hilton, J.L., Quam, W.M., Reinhard, D.K., and Wilson, C., 1976, Phys. Med. Biol., Vol. 21, 450) justified a target size of 5.5 x 5.5 cm in a neutron generator by comparison with the profile given by a 2.5 MV X-ray generator. The penumbral width of this new neutron generator is more than twice that of a modern megavoltage X-ray machine, and larger than those of beams from standard 60 Co units, or of the Hammersmith Hospital cyclotron beam. The large target size of the neutron generator may have to be accepted as a necessary evil, but should not be considered satisfactory. In reply, one of the authors of the original note presents the results of calculations of beam profiles for 14 MeV neutron beams in a tissue-equivalent phantom, and suggests that the broader profiles are principally caused by the larger probability of side scatter, not by source size. The most fruitful approach to sharpening the neutron beam profile would seem to be to design a field flattening filter to increase relative dose near the edge inside the geometrically defined field. Calculations indicating that Bewley and Parnell have underestimated the penumbral widths of 60 Co beams are also presented. (U.K.)

  4. Effect of whole-body irradiation by fast neutrons on mouse tissues. Pt. 1

    International Nuclear Information System (INIS)

    Kotb, M.A.; Abdel-Mawla, A.; El-Khatib, A.; Ramadan, M.I.A.; El-Bassiouni, E.A.

    1991-01-01

    Groups of male Swiss albino mice were irradiated by single doses of either 7 rem or 14 rem of fast neutrons with 14 MeV average energy, corresponding to fluences of 1.27x10 8 n/cm 2 and 2.54x10 8 n/cm 2 , respectively. The activities of acid phosphatase (ACP) and succinic dehydrogenase (SDH) in kidney, lung and liver were determined at different time point up to seven days after irradiation. Lysosomal affection was represented by statistically significant increase of ACP activity in all cell types of the three tested organs immediately after irradiation with either of the doses used. The effect of SDH was represented by reduction in activity in all three organs. The activities of both enzymes showed tendencies to return to pre-irradiation levels with time in most cell types especially after the 7 rem dose. (orig.) [de

  5. Fast neutron flux and intracranial dose distribution at a neutron irradiation facility

    International Nuclear Information System (INIS)

    Matsumoto, Tetsuo; Aizawa, Otohiko; Nozaki, Tetsuya

    1981-01-01

    A head phantom filled with water was used to measure the fast neutron flux using 115 In(n, n')sup(115m)In and 103 Rh(n, n')sup(103m)Rh reactions. γ-ray from sup(115m)In and x-ray from sup(103m)Rh were detected by a Ge(Li) and a Na(Tl)I counter, respectively. TLD was used to investigate the γ-dose rate distribution inside the phantom. Flux of fast neutron inside the phantom was about 1 x 10 6 n/cm 2 sec, which was 3 order smaller than that of thermal neutron. The fast neutron flux decreased to 1/10 at 15 cm depth, and γ-dose rate was about 200 R/h at 100 kW inside the phantom. Total dose at the surface was 350 rad/h, to which, fast neutrons contributed more than γ-rays. The rate of fast neutron dose was about 10% of thermal neutron's in Kerma dose unit (rad), however, the rate was highly dependent on RBE value. (Nakanishi, T.)

  6. Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT)

    Energy Technology Data Exchange (ETDEWEB)

    Cecilia, A.; Baccaro, S.; Cemmi, A. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Colli, V.; Gambarini, G. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy); Rosi, G. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Scolari, L. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy)

    2004-07-01

    A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF{sub 2}:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH{sub 3}CH(NH{sub 2})COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT. (authors)

  7. Real‑time, fast neutron detection for stimulated safeguards assay

    International Nuclear Information System (INIS)

    Joyce, Malcolm J.; Adamczyk, Justyna; Plenteda, Romano; Aspinall, Michael D.; Cave, Francis D.

    2015-01-01

    The advent of low‑hazard organic liquid scintillation detectors and real‑time pulse‑shape discrimination (PSD) processing has suggested a variety of modalities by which fast neutrons, as opposed to neutrons moderated prior to detection, can be used directly to benefit safeguards needs. In this paper we describe a development of a fast‑neutron based safeguards assay system designed for the assessment of 235 U content in fresh fuel. The system benefits from real‑time pulse‑shape discrimination processing and auto‑calibration of the detector system parameters to ensure a rapid and effective set‑up protocol. These requirements are essential in optimising the speed and limit of detection of the fast neutron technique, whilst minimising the intervention needed to perform the assay.

  8. On the studies of thermodynamics properties of fast neutron irradiated (Li{sub x}K{sub 1-x}){sub 2}SO{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    El-Khatib, A.M.; Kassem, M.E.; Gomaa, N.G.; Mahmoud, S.A. [Alexandria Univ. (Egypt). Dept. of Physics

    1996-12-31

    The effect of fast neutron irradiation on the thermodynamic properties of (Li{sub x}K{sub 1-x}){sub 2}SO{sub 4}, (x = 0.1, 0.2,......0.5) has been studied. The measurements were carried out in the vicinity of phase transition. The study reveals that as the lithium content decreases the first high temperature phase T{sub c} 705K disappears, while the second one is shifted to lower temperature. It is observed also that the specific heat, C{sub p}, decreases sharply with neutron integrated fluence {phi} and increases once more. Both entropy and enthalpy changes increase with the increase of neutron integrated fluence. (Author).

  9. Fast neutron scattering near shell closures: Scandium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1992-08-01

    Neutron differential elastic- and inelastic-scattering cross sections are measured from ∼ 1.5 to 10 MeV with sufficient detail to define the energy-averaged behavior of the scattering processes. Neutrons corresponding to excitations of 465 ± 23, 737 ± 20, 1017 ± 34, 1251 ± 20, 1432 ± 23 and 1692 ± 25 keV are observed. It is shown that the observables, including the absorption cross section, are reasonably described with a conventional optical-statistical model having energy-dependent geometric parameters. These energy dependencies are alleviated when the model is extended to include the contributions of the dispersion relationship. The model parameters are conventional, with no indication of anomalous behavior of the neutron interaction with 45 Sc, five nucleons from the doubly closed shell at 40 Ca

  10. Fast-neutrons incident on rotors: Tantalum

    International Nuclear Information System (INIS)

    Smith, Alan B.

    2005-01-01

    Mono-energetic neutrons are elastically and inelastically scattered from elemental tantalum at incident energies of ∼0.3-10.0 MeV. These experimental results are augmented with neutron total-cross-section and additional neutron-scattering data from the literature to form a composite experimental database. The latter is interpreted in the context of optical-statistical and coupled-channels models, including consideration of collective rotations, dispersion effects and other physical properties. The results are compared with those of similar processes in this region of collective nuclei. A regional model is proposed for the interpretation and prediction of such interactions. The model and the experimental results are compared with corresponding values given in ENDF/B-VI

  11. Fast neutron dose equivalent rates in heavy ion target areas

    International Nuclear Information System (INIS)

    Fulmer, C.B.; Butler, H.M.; Ohnesorge, W.F.; Mosko, S.W.

    1978-01-01

    At heavy ion accelerators, personnel access to areas near the target is sometimes important for successful performance of experiments. Radiation levels determine the amount of time that can be spent in these areas without exceeding maximum permissible exposures. Inasmuch as the fast neutrons contribute the major part of the Rem dose rates in these areas, knowledge of the fast neutron levels is important for planning permissive entry to target areas. Fast neutron dose rates were measured near thick medium mass targets bombarded with beams of C, N, O, and Ne ions. beam energies ranged from 3 to 16 MeV/amu. Dose rates (mrem/h) 1 meter from the target 90 degrees from the beam direction range from approx. 0.05 at MeV/amu to approx. 50 at 16 MeV/amu. These data should be helpful in planning permissive entry to heavy ion target areas

  12. Fast neutron dose equivalent rates in heavy ion target areas

    Energy Technology Data Exchange (ETDEWEB)

    Fulmer, C.B.; Butler, H.M.; Ohnesorge, W.F.; Mosko, S.W.

    1978-01-01

    At heavy ion accelerators, personnel access to areas near the target is sometimes important for successful performance of experiments. Radiation levels determine the amount of time that can be spent in these areas without exceeding maximum permissible exposures. Inasmuch as the fast neutrons contribute the major part of the Rem dose rates in these areas, knowledge of the fast neutron levels is important for planning permissive entry to target areas. Fast neutron dose rates were measured near thick medium mass targets bombarded with beams of C, N, O, and Ne ions. beam energies ranged from 3 to 16 MeV/amu. Dose rates (mrem/h) 1 meter from the target 90 degrees from the beam direction range from approx. 0.05 at MeV/amu to approx. 50 at 16 MeV/amu. These data should be helpful in planning permissive entry to heavy ion target areas.

  13. Measurements of fast neutrons by bubble detectors

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, F.; Martinez, H. [Laboratorio de Espectroscopia, Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251, Cuernavaca Morelos (Mexico); Leal, B. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Ciudad Universitaria, Mexico D. F. (Mexico); Rangel, J. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Ciudad Universitaria, Mexico D. F (Mexico); Reyes, P. G. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario 100, Col. Centro, 50000, Toluca Estado de Mexico (Mexico)

    2013-07-03

    Neutron bubble detectors have been studied using Am-Be and D-D neuron sources, which give limited energy information. The Bubble Detector Spectrometer (BDS) have six different energy thresholds ranging from 10 KeV to 10 Mev. The number of bubbles obtained in each measurement is related to the dose (standardized response R) equivalent neutrons through sensitivity (b / {mu}Sv) and also with the neutron flux (neutrons per unit area) through a relationship that provided by the manufacturer. Bubble detectors were used with six different answers (0.11 b/ {mu}Sv, 0093 b/{mu}Sv, 0.14 b/{mu}Sv, 0.17 b/{mu}Sv, 0051 b/{mu}Sv). To test the response of the detectors (BDS) radiate a set of six of them with different energy threshold, with a source of Am-Be, placing them at a distance of one meter from it for a few minutes. Also, exposed to dense plasma focus Fuego Nuevo II (FN-II FPD) of ICN-UNAM, apparatus which produces fusion plasma, generating neutrons by nuclear reactions of neutrons whose energy emitting is 2.45 MeV. In this case the detectors were placed at a distance of 50 cm from the pinch at 90 Degree-Sign this was done for a certain number of shots. In both cases, the standard response is reported (Dose in {mu}Sv) for each of the six detectors representing an energy range, this response is given by the expression R{sub i}= B{sub i} / S{sub i} where B{sub i} is the number of bubbles formed in each and the detector sensitivity (S{sub i}) is given for each detector in (b / {mu}Sv). Also, reported for both cases, the detected neutron flux (n cm{sup -2}), by a given ratio and the response involves both standardized R, as the average cross section sigma. The results obtained have been compared with the spectrum of Am-Be source. From these measurements it can be concluded that with a combination of bubble detectors, with different responses is possible to measure the equivalent dose in a range of 10 to 100 {mu}Sv fields mixed neutron and gamma, and pulsed generated fusion

  14. Fast neutron capture cross section facility at Cadarache

    International Nuclear Information System (INIS)

    Le Rigoleur, C.; Arnaud, A.

    1975-01-01

    The total energy weighting technique has been applied to measure absolute fast neutron capture cross section at Cadarache. We use a non hydrogeneous liquid scintillator to detect the gamma from the cascade. The neutron flux is measured with a B 10 INa(Tl) detector or Li 6 glass scintillator of well known efficiency. Time of flight technique is used with on line digital computer data processing. (orig.) [de

  15. Fast neutron activating detectors for pulsed flow measurements

    International Nuclear Information System (INIS)

    Dyatlov, V.D.; Kunaev, G.T.; Popytaev, A.N.; Cheremukhov, B.V.

    1979-01-01

    The requirements to the activation detectors of the pulsed flows of the fast neutrons are considered; the criteria of optimum measurement time, geometrical moderator sizes and radioactive detector element properties have been obtained. On their analysis parameter selection has been carried out. The neutron detector to register the short pulses has been designed and calibrated. The ways of further increase of sensitivity and efficiency of such detectors are discussed

  16. Transportable, Low-Dose Active Fast-Neutron Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mihalczo, John T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wright, Michael C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McConchie, Seth M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Archer, Daniel E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Palles, Blake A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    This document contains a description of the method of transportable, low-dose active fast-neutron imaging as developed by ORNL. The discussion begins with the technique and instrumentation and continues with the image reconstruction and analysis. The analysis discussion includes an example of how a gap smaller than the neutron production spot size and detector size can be detected and characterized depending upon the measurement time.

  17. Wide-range scintillation spectrometer of fast neutrons

    International Nuclear Information System (INIS)

    Blinov, M.V.; Gavrilov, B.P.; Ivannikova, L.L.; Kozulin, Eh.M.; Mozhaev, A.N.; Saidgareev, V.M.; Tyurin, G.P.

    1984-01-01

    A spectrometer of fast neutrons developed on the base of stilbene crystas and permitting to detect neutrons simultaneously by time-of-flight and recoil protons with analysis of pulse shape in the 0.5-50 MeV energy range is described. The detecting part is performed in the CAMAC standard. The ''Minsk-32'' computer was used for data storage and preliminary processing

  18. Coupled hydro-neutronic calculations for fast burst reactor accidents

    International Nuclear Information System (INIS)

    Paternoster, R.; Kimpland, R.; Jaegers, P.; McGhee, J.

    1994-01-01

    Methods are described for determining the fully coupled neutronic/hydrodynamic response of fast burst reactors (FBR) under disruptive accident conditions. Two code systems, PAD (1 -D Lagrangian) and NIKE-PAGOSA (3-D Eulerian) were used to accomplish this. This is in contrast to the typical methodology that computes these responses by either single point kinetics or in a decoupled manner. This methodology is enabled by the use of modem supercomputers (CM-200). Two examples of this capability are presented: an unreflected metal fast burst assembly, and a reflected fast burst assembly typical of the Skua or SPR-III class of fast burst reactor

  19. Fast neutron radiotherapy: for equal or for better

    International Nuclear Information System (INIS)

    Broerse, J.J.; Battermann, J.J.

    1981-01-01

    The renewed application of fast neutrons in clinical radiotherapy has been stimulated by fundamental radiobiological findings. The biological effects of high LET radiation, including fast neutrons, are different from those obtained with x rays in at least three respects: the oxygen enhancement ratio, the sensitivity of cells at different phases of the cell cycle, and the contribution of sublethal damage to cell reproductive death. Furthermore, wide variations in relative biological effectiveness (RBE) have been observed for different tumors and normal tissues. Measurements of volume changes in human pulmonary metastases indicate that the RBE for slowly growing tumors which are generally well-differentiated is higher than that for poorly differentiated lesions. Six thousand patients have now been treated with fast neutron beams. The results of the clinical applications vary according to the method of application and to the type of cancer involved: treatment of inoperable malignancies of the salivary gland is very encouraging: the therapeutic gain is rather small for bladder and rectal cancers, soft tissue sarcomas and advanced carcinomas of the cervix; the responses of brain tumors are very disappointing. Most neutron radiotherapy applications have been less than optimal because of inadequate physical and technical conditions. Despite these difficulties, some interesting clinical data have become available. Due to the technical shortcomings, the possible advantages of fast neutrons are probably underestimated for many tumor sites. Well-designed clinical trials, preferably performed with high energy cyclotrons in clinical environments, will provide a decisive answer to the question of the usefulness of the new radiation modality

  20. Neutron gamma competition in fast fission

    International Nuclear Information System (INIS)

    Frehaut, J.

    1989-01-01

    In the present paper we analyse the data we have obtained on the distribution of the gamma-ray energy per fission, as well as on the average energy E-barγ released per fission for the neutron induced fission of several isotopes, in the energy range up to 15 MeV. 6 refs, 9 figs

  1. Neutron nuclear physics under the neutron science project

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    The concept of fast neutron physics facility in the Neutron Science Research project is described. This facility makes use of an ultra-short proton pulse (width < 1 ns) for fast neutron time-of-flight works. The current design is based on an assumption of the maximum proton current of 100 {mu}A. Available neutron fluence and energy resolution are explained. Some of the research subjects to be performed at this facility are discussed. (author)

  2. Fast Neutron Dose Distribution in a Linac Radiotherapy Facility

    International Nuclear Information System (INIS)

    Al-Othmany, D.Sh.; Abdul-Majid, S.; Kadi, M.W.

    2011-01-01

    CR-39 plastic detectors were used for fast neutron dose mapping in the radiotherapy facility at King AbdulAziz University Hospital (KAUH). Detectors were calibrated using a 252 Cf neutron source and a neutron dosimeter. After exposure chemical etching was performed using 6N NaOH solution at 70 degree C. Tracks were counted using an optical microscope and the number of tracks/cm 2 was converted to a neutron dose. 15 track detectors were distributed inside and outside the therapy room and were left for 32 days. The average neutron doses were 142.3 mSv on the accelerator head, 28.5 mSv on inside walls, 1.4 mSv beyond the beam shield, and 1 mSv in the control room

  3. Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

    Science.gov (United States)

    Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

    2013-10-01

    Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

  4. Design and Implementation of a High-Flux Photoneutron Converter for Analysis of Fast Neutron Radiation Damage on Gallium Nitride Transistors

    Science.gov (United States)

    2017-06-01

    as the polarization and 2DEG control between aluminum gallium nitride (AlGaN) and GaN layers. Third, the physical and electrical properties of...electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures,” Journal of Applied Physics , vol...relationship of the electrical and physical characteristics of the devices with respect to the fast neutron fluence. The damage was also analyzed using

  5. Neutron cross section measurements for the Fast Breeder Program

    International Nuclear Information System (INIS)

    Block, R.C.

    1979-06-01

    This research was concerned with the measurement of neutron cross sections of importance to the Fast Breeder Reactor. The capture and total cross sections of fission products ( 101 102 104 Ru, 143 145 Nd, 149 Sm, 95 97 Mo, Cs, Pr, Pd, 107 Pd, 99 Tc) and tag gases (Kr, 78 80 Kr) were measured up to 100 keV. Filtered neutron beams were used to measure the capture cross section of 238 U (with an Fe filter) and the total cross section of Na (with a Na filter). A radioactive neutron capture detector was developed. A list of publications is included

  6. Transparent fast neutron shielding material and shielding method

    International Nuclear Information System (INIS)

    Nashimoto, Tetsuji; Katase, Haruhisa.

    1993-01-01

    Polyisobutylene having a viscosity average molecular weight of 20,000 to 80,000 and a hydrogen atom density of greater than 7.0 x 10 22 /cm 3 is used as a fast neutron shielding material. The shielding material is excellent in the shielding performance against fast neutrons, and there is no worry of leakage even when holes should be formed to a vessel. Further, it is excellent in fabricability, relatively safe even upon occurrence of fire and, in addition, it is transparent to enable to observe contents easily. (T.M.)

  7. Measurement of fast neutron spectra. 1-2

    International Nuclear Information System (INIS)

    Kimura, Itsuro

    1976-01-01

    The present status of the techniques for the measurement of fast neutron spectra is reviewed with particular attention to the recent activities in Japan. The first section of this report defines the energy range of fast neutrons, and various techniques are classified into four groups. In the following sections, recent development in each group is reviewed. The first part is the integral method represented mainly by the activation method. The variation of this method is shortly reviewed, and some results of the spectrum measurement for JRR-4 (a thermal research reactor) and YAYOI (a fast neutron source reactor) are presented together with the results of computed spectra. The second part is the method of proton recoil. The improvement of a proportional counter by Ichimori is shortly reviewed. The use of liquid scintillator is also discussed together with the experimental and computational results of YAYOI benchmark spectra of fast neutrons transmitted through the layers of iron. The utilization of n-α or n-p reaction as a sandwitch counter is discussed in the third part. Measured and calculated spectra in the FCA (a fast critical assembly) core are presented as examples. The method of time-of-flight is discussed in the fourth part. Recent developments in Japan such as the method with a double-scintillation counter are shortly presented together with its block diagram. (Aoki, K.)

  8. Transmutation of Americium in Fast Neutron Facilities

    OpenAIRE

    Zhang, Youpeng

    2011-01-01

    In this thesis, the feasibility to use a medium sized sodium cooled fast reactor fully loaded with MOX fuel for efficient transmutation of americium is investigated by simulating the safety performance of a BN600-type fast reactor loaded with different fractions of americium in the fuel, using the safety parameters obtained with the SERPENT Monte Carlo code. The focus is on americium mainly due to its long-term contribution to the radiotoxicity of spent nuclear fuel and its deterioration on c...

  9. Comparison of pressure vessel neutron fluences for the Balakovo-3 reactor with measurements and investigation of the influence of neutron cross sections and number of groups on the results

    Energy Technology Data Exchange (ETDEWEB)

    Barz, H U; Boehmer, B; Konheiser, J; Stephan, I

    1998-10-01

    The general methodical questions of experimental and theoretical determination of neutron fluences have been described in connection with the measurements and 3-D Monte Carlo calculation for the Rovno-3 reactor. The same calculation and measurement methods were applied for the Balakovo-3 reactor. In the first part, the results of the comparison for Balakovo will be given and discussed. However, for this reactor the main attention was focussed on investigations of the accuracy of the calculation. In this connection an important question is the influence of neutron data on the results. With this respect not only the source of the data but also the number of energy groups is important. (orig.)

  10. Fast neutron biological effects on normal and tumor chromatin

    International Nuclear Information System (INIS)

    Constantinescu, B.; Bugoi, Roxana; Paunica, Tatiana; Radu, Liliana

    1997-01-01

    Growing interest in neutron therapy and radioprotection requires complex studies on the mechanisms of neutron action on biological systems, especially on chromatin (the complex of deoxyribonucleic acid-DNA- with proteins in eukaryotic cells). Our study aims to investigate the fast neutrons induced damages in normal and tumor chromatin, studying thermal transition, intrinsic fluorescence and fluorescence of chromatin-ethidium bromide complexes behavior versus irradiation dose. The Bucharest U-120 variable energy Cyclotron was employed as an intense source of fast neutrons produced by 13.5 MeV deuterons on a thick beryllium target (166.5 mg/cm 2 ) placed at 20 angle against the incident beam. The average energy is 5.24 MeV. The total yield at 0 angle is 6.7 x 10 16 n/sr·C·MeV. To determine neutron and gamma irradiation doses, home made thermoluminescent detectors-TLD(γ) and TLD (γ + n) were used: for gamma MgF 2 : Mn mixed with Teflon pellets (φ 12.5 mm, 0.6±0.1 mm thick) and for gamma plus neutrons MgF 2 :Mn mixed with 6 LiF and Teflon pellets (same dimensions). Using a 8.022 x 10 -2 albedo factor value and the equivalence 1Gy (n)=2·10 10 fast neutron/cm 2 , the dose for the irradiation of 1.2 x 10 2 Gy/μC, with an estimated precision of 15% C for neutrons and 7.8 x 10 -4 Gy/μC for gamma, at 10 cm behind Be target, was found, respectively. A diminution of the negative fluorescence intensity for chromatin-ethidium bromide complexes with the increasing of neutron dose (from 0.98 at 5 Gy to 0.85 at 100 Gy) was observed for normal chromatin. This fact reflects chromatin DNA injuries, with the decrease of double helix DNA proportion. To study the influence of gyrostan, thyroxine and D3 vitamin treatments on fast neutron radiolysis in tumor chromatin,10 mg/kg of anticancer drug gyrostan, 40μg/kg of hormonal compound thyroxine and 30,000 IU/kg of D3 vitamin were administrated, separately or associated, to Wistar rats bearing Walker carcinosarcoma. Representing

  11. An empirical formula for scattered neutron components in fast neutron radiography

    International Nuclear Information System (INIS)

    Dou Haifeng; Tang Bin

    2011-01-01

    Scattering neutrons are one of the key factors that may affect the images of fast neutron radiography. In this paper, a mathematical model for scattered neutrons is developed on a cylinder sample, and an empirical formula for scattered neutrons is obtained. According to the results given by Monte Carlo methods, the parameters in the empirical formula are obtained with curve fitting, which confirms the logicality of the empirical formula. The curve-fitted parameters of common materials such as 6 LiD are given. (authors)

  12. The investigation of fast neutron Threshold Activation Detectors (TAD)

    International Nuclear Information System (INIS)

    Gozani, T; King, M J; Stevenson, J

    2012-01-01

    The detection of fast neutrons is usually done by liquid hydrogenous organic scintillators, where the separation between the ever present gamma rays and neutrons is achieved by the pulse shape discrimination (PSD). In many practical situation the detection of fast neutrons has to be carried out while the intense source (be it neutrons, gamma rays or x-rays) that creates these neutrons, for example by the fission process, is present. This source, or ''flash'', usually blinds the neutron detectors and temporarily incapacitates them. By the time the detectors recover the prompt neutron signature does not exist. Thus to overcome the blinding background, one needs to search for processes whereby the desired signature, such as fission neutrons could in some way be measured long after the fission occurred and when the neutron detector is fully recovered from the overload. A new approach was proposed and demonstrated a good sensitivity for the detection of fast neutrons in adverse overload situations where normally it could not be done. A temporal separation of the fission event from the prompt neutrons detection is achieved via the activation process. The main idea, called Threshold Activation Detection (or detector)-TAD, is to find appropriate substances that can be selectively activated by the fission neutrons and not by the source radiation, and then measure the radioactively decaying activation products (typically beta and γ-rays) well after the source pulse has ended. The activation material should possess certain properties: a suitable half-life; an energy threshold below which the numerous source neutrons will not activate it (e.g. about 3 MeV); easily detectable activation products and has a usable cross section for the selected reaction. Ideally the substance would be part of the scintillator. There are several good candidates for TAD. The first one we have selected is based on fluorine. One of the major advantages of this element is the fact that it is a major

  13. The investigation of fast neutron Threshold Activation Detectors (TAD)

    Science.gov (United States)

    Gozani, T.; King, M. J.; Stevenson, J.

    2012-02-01

    The detection of fast neutrons is usually done by liquid hydrogenous organic scintillators, where the separation between the ever present gamma rays and neutrons is achieved by the pulse shape discrimination (PSD). In many practical situation the detection of fast neutrons has to be carried out while the intense source (be it neutrons, gamma rays or x-rays) that creates these neutrons, for example by the fission process, is present. This source, or ``flash'', usually blinds the neutron detectors and temporarily incapacitates them. By the time the detectors recover the prompt neutron signature does not exist. Thus to overcome the blinding background, one needs to search for processes whereby the desired signature, such as fission neutrons could in some way be measured long after the fission occurred and when the neutron detector is fully recovered from the overload. A new approach was proposed and demonstrated a good sensitivity for the detection of fast neutrons in adverse overload situations where normally it could not be done. A temporal separation of the fission event from the prompt neutrons detection is achieved via the activation process. The main idea, called Threshold Activation Detection (or detector)-TAD, is to find appropriate substances that can be selectively activated by the fission neutrons and not by the source radiation, and then measure the radioactively decaying activation products (typically beta and γ-rays) well after the source pulse has ended. The activation material should possess certain properties: a suitable half-life; an energy threshold below which the numerous source neutrons will not activate it (e.g. about 3 MeV); easily detectable activation products and has a usable cross section for the selected reaction. Ideally the substance would be part of the scintillator. There are several good candidates for TAD. The first one we have selected is based on fluorine. One of the major advantages of this element is the fact that it is a major

  14. The interaction of fast neutrons with hafnium

    International Nuclear Information System (INIS)

    Smith, A.B.

    2002-01-01

    Elemental hafnium neutron total cross sections are measured from ∼0.75 to 4.5 MeV in steps of ∼40 keV. Differential neutron elastic-scattering cross sections are measured from ∼4.5 to 10.0 MeV in ∼0.5 MeV steps and at 40 scattering angles distributed between ∼17 and 160 deg. These data are combined with those found in the literature to construct a comprehensive experimental data base which is interpreted in terms of coupled-channels models. Physical characteristics of the resulting potentials are discussed. Comparisons are made with ENDF/B-6 (MAT 7200). A detailed report of this work is given by Smith (Smith, A., 2001. Argonne National Laboratory Report ANL/NDM-153)

  15. Explosives detection via fast neutron transmission spectroscopy

    International Nuclear Information System (INIS)

    Overley, J.C.; Chmelik, M.S.; Rasmussen, R.J.; Schofield, R.M.S.; Sieger, G.E.; Lefevre, H.W.

    2006-01-01

    A review of a five-year project on detection of explosives in luggage is presented. Experimental methods are described. Explosive detection algorithms based on elemental distributions in a 5-dimensional space are also described. Single-blind tests of the method suggest that a false-alarm rate of 4% and a detection rate of 93% are possible. Improvements in the method are suggested. Measurements of neutron total cross sections for chlorine are presented

  16. Fast neutron scattering on actinide nuclei

    International Nuclear Information System (INIS)

    1982-01-01

    More and more sophisticated neutron experiments have been carried out with better samples in several laboratories and it was necessary to intercompare them. In this respect, let us quote for example (n,n'e) and (n,n'#betta#) measurements. Moreover, high precision (p,p), (p,p') and (p,n) measurements have been made, thus supplementing neutron experiments in the determination of the parameters of the optical model, still widely used to describe the neutron-nucleus interaction. The optical model plays a major role and it is therefore essential to know it well. The spherical optical model is still very useful, especially because of its simplicity and of the relatively short calculation times, but is obviously insufficient to treat deformed nuclei such as actinides. For accurate calculations about these nuclei, it is necessary to use a deformed potential well and solve a set of coupled equations, hence long computational times. The importance of compound nucleus formation at low energy requires also a good knowledge of the statistical model together with that of all the reaction mechanisms which are involved, including fission for which an accurate barrier is necessary and, of course, well-adjusted level densities. The considerations form the background of the Scientific Programme set up by a Programme Committee whose composition is given further on in this book

  17. The risk from fast neutron exposure

    International Nuclear Information System (INIS)

    Bond, V.P.

    1979-01-01

    The conclusions and recommendations made by Rossi and Mays in recent papers (Rad. Res. 71, 1, 1977; Rad. Environ. Biophys. 14, 275, 1977; Health Phys. 34, 353, 1978), based on their analysis of recent Japanese data are discussed. They imply that the risk associated with the current annual dose equivalent limit of 5 rem for all radiations is unacceptably high, that this limit must be reduced by a factor of 10 or more, and that the conservative linear, no threshold hypothesis must be abandoned. It is shown in this paper that these recommendations are not supported by the newly-analyzed neutron data, and certainly cannot be applied selectively to the annual absorbed dose limit for neutrons. In particular the judgement that the risk of an annual exposure from 0.5 rad (5 rem) of neutrons is unacceptably high, is a personal opinion of the authors, and does not necessarily follow either from the assumption of a linear-quadratic dose effect relation for low-LET radiation or from other radiobiological considerations. At issue is the level of risk that is to be considered 'acceptable', a question that is societal and thus not resolvable on purely technical or scientific grounds. (author)

  18. Fast ultrasonic visualisation under sodium. Application to the fast neutron reactors

    International Nuclear Information System (INIS)

    Imbert, Ch.

    1997-01-01

    The fast ultrasonic visualization under sodium is in the programme of research and development on the inspection inside the fast neutron reactors. This work is about the development of a such system of fast ultrasonic imaging under sodium, in order to improve the existing visualization systems. This system is based on the principle of orthogonal imaging, it uses two linear antennas with an important dephasing having 128 piezo-composite elements of central frequency equal to 1.6 MHz. (N.C.)

  19. He-4 fast neutron detectors in nuclear security applications

    International Nuclear Information System (INIS)

    Murer, D. E.

    2014-01-01

    This work presents studies of "4He fast neutron detectors for nuclear security applications. Such devices are high pressure gas scintillation detectors, sensitive to neutrons in the energy range of fission sources. First, an introduction to the scope of the intended application is given. This is followed by a description of all components relevant to the operation of the detector. The next chapter presents studies of various characteristics of the neutron detector, among them properties of its scintillation response, differences between neutron and gamma interactions and effects of the light collection process. The results of the detector characterization are used to develop neutron gamma discrimination methods. These methods are put to the test using measurements with a high gamma flux, and the results are compared to performance requirements of Radiation Portal Monitors. Background neutron measurements are presented next. Measured neutron rates are compared to values published in scientific literature. The fluctuation of the background count rate was studied, and the contribution of muons evaluated. Two applications of the detectors in the field of nuclear security are discussed in the last two chapters. The first one is a novel method to measure the plutonium mass in a container filled with Mixed Oxide Fuel. The last chapter presents the development of a Radiation Portal Monitor which, in addition to neutron and gamma counting, exploits time correlation to detect threats such as plutonium and "6"0Co. (author)

  20. He-4 fast neutron detectors in nuclear security applications

    Energy Technology Data Exchange (ETDEWEB)

    Murer, D. E.

    2014-07-01

    This work presents studies of {sup 4}He fast neutron detectors for nuclear security applications. Such devices are high pressure gas scintillation detectors, sensitive to neutrons in the energy range of fission sources. First, an introduction to the scope of the intended application is given. This is followed by a description of all components relevant to the operation of the detector. The next chapter presents studies of various characteristics of the neutron detector, among them properties of its scintillation response, differences between neutron and gamma interactions and effects of the light collection process. The results of the detector characterization are used to develop neutron gamma discrimination methods. These methods are put to the test using measurements with a high gamma flux, and the results are compared to performance requirements of Radiation Portal Monitors. Background neutron measurements are presented next. Measured neutron rates are compared to values published in scientific literature. The fluctuation of the background count rate was studied, and the contribution of muons evaluated. Two applications of the detectors in the field of nuclear security are discussed in the last two chapters. The first one is a novel method to measure the plutonium mass in a container filled with Mixed Oxide Fuel. The last chapter presents the development of a Radiation Portal Monitor which, in addition to neutron and gamma counting, exploits time correlation to detect threats such as plutonium and {sup 60}Co. (author)

  1. Detection of land mines using fast and thermal neutron analysis

    International Nuclear Information System (INIS)

    Bach, P.

    1998-01-01

    The detection of land mines is made possible by using nuclear sensor based on neutron interrogation. Neutron interrogation allows to detect the sensitive elements (C, H, O, N) of the explosives in land mines or in unexploded shells: the evaluation of characteristic ratio N/O and C/O in a volume element gives a signature of high explosives. Fast neutron interrogation has been qualified in our laboratories as a powerful close distance method for identifying the presence of a mine or explosive. This method could be implemented together with a multisensor detection system - for instance IR or microwave - to reduce the false alarm rate by addressing the suspected area. Principle of operation is based on the measurement of gamma rays induced by neutron interaction with irradiated nuclei from the soil and from a possible mine. Specific energy of these gamma rays allows to recognise the elements at the origin of neutron interaction. Several detection methods can be used, depending on nuclei to be identified. Analysis of physical data, computations by simulation codes, and experimentations performed in our laboratory have shown the interest of Fast Neutron Analysis (FNA) combined with Thermal Neutron Analysis (TNA) techniques, especially for detection of nitrogen 14 N, carbon 12 C and oxygen 16 O. The FNA technique can be implemented using a 14 MeV sealed neutron tube, and a set of detectors. The mines detection has been demonstrated from our investigations, using a low power neutron generator working in the 10 8 n/s range, which is reasonable when considering safety rules. A fieldable demonstrator would be made with a detection head including tube and detectors, and with remote electronics, power supplies and computer installed in a vehicle. (author)

  2. Fast neutron irradiation induced changes in the optical and thermal properties of modified polyvinyl chloride

    Energy Technology Data Exchange (ETDEWEB)

    Abou Taleb, W.M. [Alexandria Univ. (Egypt); Madi, N.K.; Kassem, M.E.; El-Khatib, A.M. [Alexandria Univ. (Egypt). Dept. of Physics

    1996-05-01

    The effect of both dopant and neutron radiation on the optical and thermal properties of polyvinyl chloride (PVC) has been studied. The doped samples with Pb and Cd were irradiated with a 14 MeV-neutron fluence in the range 7-28.8 x 10{sup 9} n/cm{sup 2}. The optical energy gap E{sub op} exhibits a significant dependence on the type of additive and the neutron irradiation fluence. The specific heat at constant pressure C{sub p} showed a nonmonotonical change with radiation fluence. The results of this study show that PVC:Pb behaves as a crystalline structure which is only slightly affected by neutron irradiation, while PVC:Cd is highly affected. (author).

  3. Fast neutron irradiation induced changes in the optical and thermal properties of modified polyvinyl chloride

    International Nuclear Information System (INIS)

    Abou Taleb, W.M.; Madi, N.K.; Kassem, M.E.; El-Khatib, A.M.

    1996-01-01

    The effect of both dopant and neutron radiation on the optical and thermal properties of polyvinyl chloride (PVC) has been studied. The doped samples with Pb and Cd were irradiated with a 14 MeV-neutron fluence in the range 7-28.8 x 10 9 n/cm 2 . The optical energy gap E op exhibits a significant dependence on the type of additive and the neutron irradiation fluence. The specific heat at constant pressure C p showed a nonmonotonical change with radiation fluence. The results of this study show that PVC:Pb behaves as a crystalline structure which is only slightly affected by neutron irradiation, while PVC:Cd is highly affected. (author)

  4. Neutronics methods for transient and safety analysis of fast reactors

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, Marco

    2017-07-01

    Modeling the evolution of possible or postulated accidents in nuclear reactors is fundamental in designing safe systems. For the next generation of reactors, in particular fast reactors, fuel movement during an accident can, in principle, drive an energetic event. Such is the issue of recriticality. The thermal energy produced during these events will, possibly, be converted into mechanical energy by some mechanisms. For example, the nuclear heat deposited in the fuel could cause fuel vaporization and its subsequent expansion. This movement would accelerate the surrounding sodium: part of the initial energy in the fuel is thus converted into sodium kinetic energy. This mechanical energy will finally be absorbed, in some way or another, by the reactor vessel. Providing an accurate estimate for the maximum mechanical work that any accidental sequence can do onto the reactor vessel is an essential step in designing a reactor containment that would withstand any load generated by any accident. That would assure accident containment, without consequences for the general public. Fast reactor accident modeling is a complicated task. The outcome of an accident is determined by different physical phenomena, all acting at almost the same time. Safety analysts must track all these different phenomena. Multi-physics codes have been developed for this task. They must contain accurate models for fluid-dynamics, neutronics, and structures. This work has to do with neutronics modeling of such accidents. Past and recent analyses have been limited to the approximate description of the neutronic field, for example by using a rough description of the energy and/or of the angular dependence of the neutron flux. In this work, different neutronic solvers are selected and coupled into a general multi-physics code for fast reactor accident analysis. Performances of each of them is then assessed. Some emphasis has been put also in assessing the speed of these solvers for determining the

  5. Fast Neutron Emission Tomography of Used Nuclear Fuel Assemblies

    Science.gov (United States)

    Hausladen, Paul; Iyengar, Anagha; Fabris, Lorenzo; Yang, Jinan; Hu, Jianwei; Blackston, Matthew

    2017-09-01

    Oak Ridge National Laboratory is developing a new capability to perform passive fast neutron emission tomography of spent nuclear fuel assemblies for the purpose of verifying their integrity for international safeguards applications. Most of the world's plutonium is contained in spent nuclear fuel, so it is desirable to detect the diversion of irradiated fuel rods from an assembly prior to its transfer to ``difficult to access'' storage, such as a dry cask or permanent repository, where re-verification is practically impossible. Nuclear fuel assemblies typically consist of an array of fuel rods that, depending on exposure in the reactor and consequent ingrowth of 244Cm, are spontaneous sources of as many as 109 neutrons s-1. Neutron emission tomography uses collimation to isolate neutron activity along ``lines of response'' through the assembly and, by combining many collimated views through the object, mathematically extracts the neutron emission from each fuel rod. This technique, by combining the use of fast neutrons -which can penetrate the entire fuel assembly -and computed tomography, is capable of detecting vacancies or substitutions of individual fuel rods. This paper will report on the physics design and component testing of the imaging system. This material is based upon work supported by the U.S. Department of Energy, Office of Defense Nuclear Nonproliferation Research and Development within the National Nuclear Security Administration, under Contract Number DE-AC05-00OR22725.

  6. ACTIV87 Fast neutron activation cross section file 1987

    International Nuclear Information System (INIS)

    Manokhin, V.N.; Pashchenko, A.B.; Plyaskin, V.I.; Bychkov, V.M.; Pronyaev, V.G.; Schwerer, O.

    1989-10-01

    This document summarizes the content of the Fast Neutron Activation Cross Section File based on data from different evaluated data libraries and individual evaluations in ENDF/B-5 format. The entire file or selective retrievals from it are available on magnetic tape, free of charge, from the IAEA Nuclear Data Section. (author)

  7. Fast neutron induced increase of flowering in portulaca grandiflora linn

    International Nuclear Information System (INIS)

    Abraham, V.; Desai, B.M.

    1975-01-01

    Unbranched cuttings were exposed to fast neutron doses of 71-284 rads and planted along with unirradiated controls. There was a significant increase in the numbers of flowers in the treated populations due to the increased production of primary and secondary branches. (MG) [de

  8. Fast neutron sensitivity of dry and germinating tomato seeds

    NARCIS (Netherlands)

    Contant, R.B.

    1970-01-01

    A study was made of changes in fast neutron effectiveness during the hydration and germination of tomato seeds. The main findings and conclusions are the following,

    Section 3.6

    Samples of unirradiated seeds and their constituent parts (seedcoat+endosperm and embryo) were taken at short

  9. Semiclassical model of cross section for fast neutrons

    International Nuclear Information System (INIS)

    Rosato, A.; D'Oliveira, A.A.

    1977-01-01

    A study for main aspects of fast neutron scattering is presented and, a semiclassical approximation applying to several pratic cases is described. The obtained results are compared with experimental data for deformed nuclei, and, with theoretical data based on optical model without treatment of deformations. (M.C.K.) [pt

  10. FERMILAB: operation resumes in meson area; fast neutron therapy

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Improvements and modifications in the Meson Area at Fermilab are described. The target train was rebuilt and energy range of some beams raised to 400 GeV with provisions for Tevatron beams of 1000 GeV in the future. The work of the fast neutron therapy facility is summarised. (W.D.L.).

  11. Basic concepts underlying fast-neutron-based contraband interrogation technology

    International Nuclear Information System (INIS)

    Fink, C.L.; Guenther, P.T.; Smith, D.L.

    1992-01-01

    All accelerator-based fast-neutron contraband interrogation systems have many closely interrelated subsystems, whose performance parameters will be critically interdependent. For optimal overall performance, a systems analysis design approach is required. This paper provides a general overview of the interrelationships and the tradeoffs to be considered for optimization of nonaccelerator subsystems

  12. Spectroscopic study of fast-neutron-irradiated chromatin

    International Nuclear Information System (INIS)

    Radu, L.; Gazdaru, D.; Constantinescu, B.

    2004-01-01

    The effects produced by fast neutrons (0-100 Gy) on chromatin structure were analyzed by (i) [ 1 H]-NMR spectroscopy, (ii) time resolved spectroscopy, and (iii) fluorescence resonance energy transfer (FRET). Two types of chromatin were tested: (i) a chromatin from a normal tissue (liver of Wistar rats) and (ii) a chromatin from a tumoral tissue (Guerin limphotrope epithelioma, a rat solid tumor). The fast-neutron action on chromatin determines greater values of the [ 1 H]-NMR transverse relaxation time, indicating a more injured structure. Time-resolved fluorescence measurements show that the relative contribution of the excited state lifetime of bound ethidium bromide to chromatin DNA diminishes with increasing irradiation doses. This reflects the damage that occurs in DNA structure: production of single- and double-strand breaks due to sugar and base modifications. By the FRET method, the distance between dansyl chloride and acridine orange coupled at chromatin was determined. This distance increases upon fast-neutron action. The radiosensitivity of the tumor tissue chromatin seems higher than that of the normal tissue chromatin, probably because of its higher (loose) euchromatin/(compact) heterochromatin ratio. As the values of the physical parameters analyzed are specific for a determined dose, the establishment of these parameters may constitute a criterion for the microdosimetry of chromatin radiolesions produced by fast neutrons. (author)

  13. Spectroscopic study of fast-neutron-irradiated chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L. [V. Babes National Inst., Dept. of Molecular Genetics, Bucharest (Romania)]. E-mail: serbanradu@pcnet.ro; Gazdaru, D. [Bucharest Univ., Dept. of Biophysics, Physics Faculty, Bucharest (Romania); Constantinescu, B. [H. Hulubei National Inst., Dept. of Cyclotron, Bucharest (Romania)

    2004-02-01

    The effects produced by fast neutrons (0-100 Gy) on chromatin structure were analyzed by (i) [{sup 1}H]-NMR spectroscopy, (ii) time resolved spectroscopy, and (iii) fluorescence resonance energy transfer (FRET). Two types of chromatin were tested: (i) a chromatin from a normal tissue (liver of Wistar rats) and (ii) a chromatin from a tumoral tissue (Guerin limphotrope epithelioma, a rat solid tumor). The fast-neutron action on chromatin determines greater values of the [{sup 1}H]-NMR transverse relaxation time, indicating a more injured structure. Time-resolved fluorescence measurements show that the relative contribution of the excited state lifetime of bound ethidium bromide to chromatin DNA diminishes with increasing irradiation doses. This reflects the damage that occurs in DNA structure: production of single- and double-strand breaks due to sugar and base modifications. By the FRET method, the distance between dansyl chloride and acridine orange coupled at chromatin was determined. This distance increases upon fast-neutron action. The radiosensitivity of the tumor tissue chromatin seems higher than that of the normal tissue chromatin, probably because of its higher (loose) euchromatin/(compact) heterochromatin ratio. As the values of the physical parameters analyzed are specific for a determined dose, the establishment of these parameters may constitute a criterion for the microdosimetry of chromatin radiolesions produced by fast neutrons. (author)

  14. Nuclear structure effects on calculated fast neutron reaction cross sections

    International Nuclear Information System (INIS)

    Avrigeanu, V.

    1992-01-01

    The importance of accurate low-lying level schemes for reaction cross section calculation and need for microscopically calculated levels are proved with reference to fast neutron induced reactions in the A = 50 atomic mass range. The uses of the discrete levels both for normalization of phenomenological level density approaches and within Hauser-Feshbach calculations are discussed in this respect. (Author)

  15. Joint estimation of the fast and thermal components of a high neutron flux with a two on-line detector system

    International Nuclear Information System (INIS)

    Filliatre, P.; Oriol, L.; Jammes, C.; Vermeeren, L.

    2009-01-01

    A fission chamber with a 242 Pu deposit is the best suited detector for on-line measurements of the fast component of a high neutron flux (∼10 14 ncm -2 s -1 or more) with a significant thermal component. To get the fast flux, it is, however, necessary to subtract the contribution of the thermal neutrons, which increases with fluence because of the evolution of the isotopic content of the deposit. This paper presents an algorithm that permits, thanks to measurements provided by a 242 Pu fission chamber and a detector for thermal neutrons, to estimate the thermal and the fast flux at any time. An implementation allows to test it with simulated data.

  16. Joint estimation of the fast and thermal components of a high neutron flux with a two on-line detector system

    Energy Technology Data Exchange (ETDEWEB)

    Filliatre, P. [CEA, DEN, SPEx/LDCI, F-13108 Saint-Paul-lez-Durance (France); Laboratoire Commun d' Instrumentation CEA-SCK-CEN (France)], E-mail: philippe.filliatre@cea.fr; Oriol, L.; Jammes, C. [CEA, DEN, SPEx/LDCI, F-13108 Saint-Paul-lez-Durance (France); Laboratoire Commun d' Instrumentation CEA-SCK-CEN (France); Vermeeren, L. [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium); Laboratoire Commun d' Instrumentation CEA-SCK-CEN (France)

    2009-05-21

    A fission chamber with a {sup 242}Pu deposit is the best suited detector for on-line measurements of the fast component of a high neutron flux ({approx}10{sup 14}ncm{sup -2}s{sup -1} or more) with a significant thermal component. To get the fast flux, it is, however, necessary to subtract the contribution of the thermal neutrons, which increases with fluence because of the evolution of the isotopic content of the deposit. This paper presents an algorithm that permits, thanks to measurements provided by a {sup 242}Pu fission chamber and a detector for thermal neutrons, to estimate the thermal and the fast flux at any time. An implementation allows to test it with simulated data.

  17. Application of Van Hove theory to fast neutron inelastic scattering

    International Nuclear Information System (INIS)

    Stanicicj, V.

    1974-11-01

    The Vane Hove general theory of the double differential scattering cross section has been used to derive the particular expressions of the inelastic fast neutrons scattering kernel and scattering cross section. Since the considered energies of incoming neutrons being less than 10 MeV, it enables to use the Fermi gas model of nucleons. In this case it was easy to derive an analytical expression for the time-dependent correlation function of the nucleus. Further, by using an impulse approximation and a short-collision time approach, it was possible to derive the analytical expression of the scattering kernel and scattering cross section for the fast neutron inelastic scattering. The obtained expressions have been used for Fe nucleus. It has been shown a surprising agreement with the experiments. The main advantage of this theory is in its simplicity for some practical calculations and for some theoretical investigations of nuclear processes

  18. Radiation hardness tests of piezoelectric actuators with fast neutrons at liquid helium temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fouaidy, M.; Martinet, G.; Hammoudi, N.; Chatelet, F.; Olivier, A.; Blivet, S.; Galet, F. [CNRS-IN2P3-IPN Orsay, Orsay (France)

    2007-07-01

    Piezoelectric actuators, which are integrated into the cold tuning system and used to compensate the small mechanical deformations of the cavity wall induced by Lorentz forces due to the high electromagnetic surface field, may be located in the radiation environment during particle accelerator operation. In order to provide for a reliable operation of the accelerator, the performance and life time of piezoelectric actuators ({approx}24.000 units for ILC) should not show any significant degradation for long periods (i.e. machine life duration: {approx}20 years), even when subjected to intense radiation (i.e. gamma rays and fast neutrons). An experimental program, aimed at investigating the effect of fast neutrons radiation on the characteristics of piezoelectric actuators at liquid helium temperature (i.e. T{approx}4.2 K), was proposed for the working package WPNo.8 devoted to tuners development in the frame of CARE project. A neutrons irradiation facility, already installed at the CERI cyclotron located at Orleans (France), was upgraded and adapted for actuators irradiations tests purpose. A deuterons beam (maximum energy and beam current: 25 MeV and 35{mu}A) collides with a thin (thickness: 3 mm) beryllium target producing a high neutrons flux with low gamma dose ({approx}20%): a neutrons fluence of more than 10{sup 14} n/cm{sup 2} is achieved in {approx}20 hours of exposure. A dedicated cryostat was developed at IPN Orsay and used previously for radiation hardness test of calibrated cryogenic thermometers and pressure transducers used in LHC superconducting magnets. This cryostat could be operated either with liquid helium or liquid argon. This irradiation facility was upgraded for allowing fast turn-over of experiments and a dedicated experimental set-up was designed, fabricated, installed at CERI and successfully operated for radiation hardness tests of several piezoelectric actuators at T{approx}4.2 K. This new apparatus allows on-line automatic measurements

  19. Radiation hardness tests of piezoelectric actuators with fast neutrons at liquid helium temperature

    International Nuclear Information System (INIS)

    Fouaidy, M.; Martinet, G.; Hammoudi, N.; Chatelet, F.; Olivier, A.; Blivet, S.; Galet, F.

    2007-01-01

    Piezoelectric actuators, which are integrated into the cold tuning system and used to compensate the small mechanical deformations of the cavity wall induced by Lorentz forces due to the high electromagnetic surface field, may be located in the radiation environment during particle accelerator operation. In order to provide for a reliable operation of the accelerator, the performance and life time of piezoelectric actuators (∼24.000 units for ILC) should not show any significant degradation for long periods (i.e. machine life duration: ∼20 years), even when subjected to intense radiation (i.e. gamma rays and fast neutrons). An experimental program, aimed at investigating the effect of fast neutrons radiation on the characteristics of piezoelectric actuators at liquid helium temperature (i.e. T∼4.2 K), was proposed for the working package WPNo.8 devoted to tuners development in the frame of CARE project. A neutrons irradiation facility, already installed at the CERI cyclotron located at Orleans (France), was upgraded and adapted for actuators irradiations tests purpose. A deuterons beam (maximum energy and beam current: 25 MeV and 35μA) collides with a thin (thickness: 3 mm) beryllium target producing a high neutrons flux with low gamma dose (∼20%): a neutrons fluence of more than 10 14 n/cm 2 is achieved in ∼20 hours of exposure. A dedicated cryostat was developed at IPN Orsay and used previously for radiation hardness test of calibrated cryogenic thermometers and pressure transducers used in LHC superconducting magnets. This cryostat could be operated either with liquid helium or liquid argon. This irradiation facility was upgraded for allowing fast turn-over of experiments and a dedicated experimental set-up was designed, fabricated, installed at CERI and successfully operated for radiation hardness tests of several piezoelectric actuators at T∼4.2 K. This new apparatus allows on-line automatic measurements of actuators characteristics and the

  20. Energy-resolved fast neutron resonance radiography at CSNS

    Science.gov (United States)

    Tan, Zhixin; Tang, Jingyu; Jing, Hantao; Fan, Ruirui; Li, Qiang; Ning, Changjun; Bao, Jie; Ruan, Xichao; Luan, Guangyuan; Feng, Changqin; Zhang, Xianpeng

    2018-05-01

    The white neutron beamline at the China Spallation Neutron Source will be used mainly for nuclear data measurements. It will be characterized by high flux and broad energy spectra. To exploit the beamline as a neutron imaging source, we propose a liquid scintillator fiber array for fast neutron resonance radiography. The fiber detector unit has a small exposed area, which will limit the event counts and separate the events in time, thus satisfying the requirements for single-event time-of-flight (SEToF) measurement. The current study addresses the physical design criteria for ToF measurement, including flux estimation and detector response. Future development and potential application of the technology are also discussed.

  1. Code of practice for in-core instrumentation for neutron fluence rate (flux) measurements in power reactors

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    This standard applies to in-core (on-line) neutron detectors and instrumentation which is designed for safety, information or control purposes. It also applies to components in so far as these components are contained within the primary envelope of the reactor. The detector types usually used are dc ionization chambers and self-powered neutron detectors

  2. A measurement of the response to fast neutrons of several materials dosemeters

    International Nuclear Information System (INIS)

    Jones, L.T.; Kitching, S.J.; Lewis, T.A.; Playle, T.S.

    1986-07-01

    The response to fast neutrons was measured for three types of materials testing dosemeters: fast neutron dosimetry silicon diodes; beryllia, alumina and calcium fluoride TLDs; graphite walled ionisation chambers. The calibrations were made using a 3MW positive ion accelerator. The arrangement of the target, beam monitor and devices is described, and the measured fast neutron sensitivities are presented. (UK)

  3. System and plastic scintillator for discrimination of thermal neutron, fast neutron, and gamma radiation

    Science.gov (United States)

    Zaitseva, Natalia P.; Carman, M. Leslie; Faust, Michelle A.; Glenn, Andrew M.; Martinez, H. Paul; Pawelczak, Iwona A.; Payne, Stephen A.

    2017-05-16

    A scintillator material according to one embodiment includes a polymer matrix; a primary dye in the polymer matrix, the primary dye being a fluorescent dye, the primary dye being present in an amount of 3 wt % or more; and at least one component in the polymer matrix, the component being selected from a group consisting of B, Li, Gd, a B-containing compound, a Li-containing compound and a Gd-containing compound, wherein the scintillator material exhibits an optical response signature for thermal neutrons that is different than an optical response signature for fast neutrons and gamma rays. A system according to one embodiment includes a scintillator material as disclosed herein and a photodetector for detecting the response of the material to fast neutron, thermal neutron and gamma ray irradiation.

  4. Neutron fluence at the reactor pressure vessel wall - a comparison of French and German procedures and strategies in PWRs

    International Nuclear Information System (INIS)

    Tricot, N.; Jendrich, U.

    2003-01-01

    While the neutrons within the core may take part in the chain reaction, those neutrons emitted from the core are basically lost for the energy production. This 'neutron leakage' represents a loss of fuel efficiency and causes neutron embrittlement of the reactor pressure vessel (RPV) wall. The latter raises safety concerns, needs to be monitored closely and may necessitate mitigating measures. There are different strategies to deal with these two undesirable effects: The neutron emission may be reduced to some extent all around the core or just at the 'hot spots' of RPV embrittlement by tailored core loading patterns. A higher absorption rate of neutrons may also be achieved by a larger water gap between the core and the RPV. In this paper the inter-relations between the distribution of neutron flux, core geometry, core loading strategy, RPV embrittlement and its surveillance are discussed at first. Then the different strategies followed by the German and French operators are described. Finally the conclusions will highlight the communalities and differences between these strategies as different approaches to the same problem of safety as well as economy. (authors)

  5. Nuclear fuel assembly for fast neutron reactors

    International Nuclear Information System (INIS)

    Ilyunin, V.G.; Murogov, V.M.; Troyanov, M.F.; Rinejskij, A.A.; Ustinov, G.G.; Shmelev, A.N.

    1982-01-01

    The fuel assembly of a fast reactor consists of fuel elements comprising sections with fissionable and breeding material and tubes with hollows designed for entrapping gaseous fission products. Tubes joining up to the said sections are divided in a middle and a peripheral group such that at least one of the tube groups is placed in the space behind the coolant inlet ports. The configuration above allows reducing internal overpressure in the fuel assembly, thus reducing the volume of necessary structural elements in the core. (J.B.)

  6. EDF research on fast neutron reactors

    International Nuclear Information System (INIS)

    In order to make possible the calculation of the temperatures of the sodium, of the sheath and of the fuel in fast reactor assemblies, taking into account the mixing phenomena induced by the helicoidal wires, two design codes have been developed. Those codes have then been adapted for their integration in the Superalcyon system. This system shall constitute the reference tool for the development of those codes that shall manage Phenix, and other reactors of the family. Cooling accidents, thermohydraulic studies, and steam generator studies are also in progress

  7. A multi-group neutron noise simulator for fast reactors

    International Nuclear Information System (INIS)

    Tran, Hoai Nam; Zylbersztejn, Florian; Demazière, Christophe; Jammes, Christian; Filliatre, Philippe

    2013-01-01

    Highlights: • The development of a neutron noise simulator for fast reactors. • The noise equation is solved fully in a frequency-domain. • A good agreement with ERANOS on the static calculations. • Noise calculations induced by a localized perturbation of absorption cross section. - Abstract: A neutron noise simulator has been developed for fast reactors based on diffusion theory with multi-energy groups and several groups of delayed neutron precursors. The tool is expected to be applicable for core monitoring of fast reactors and also for other reactor types with hexagonal fuel assemblies. The noise sources are modeled through small stationary fluctuations of macroscopic cross sections, and the induced first order noise is solved fully in the frequency domain. Numerical algorithms are implemented for solving both the static and noise equations using finite differences for spatial discretization, where a hexagonal assembly is radially divided into finer triangular meshes. A coarse mesh finite difference (CMFD) acceleration has been used for accelerating the convergence of both the static and noise calculations. Numerical calculations have been performed for the ESFR core with 33 energy groups and 8 groups of delayed neutron precursors using the cross section data generated by the ERANOS code. The results of the static state have been compared with those obtained using ERANOS. The results show an adequate agreement between the two calculations. Noise calculations for the ESFR core have also been performed and demonstrated with an assumption of the perturbation of the absorption cross section located at the central fuel ring

  8. Illicit substance detection using fast-neutron transmission spectroscopy

    International Nuclear Information System (INIS)

    Micklich, B.J.; Harper, M.K.; Novick, A.H.; Smith, D.L.

    1994-01-01

    Fast-neutron interrogation techniques are of interest for detecting illicit substances such as explosives and drugs because of their ability to identify light elements such as carbon, nitrogen, and oxygen. Fast-Neutron Transmission Spectroscopy (FNTS) uses standard time-of-flight techniques to measure the energy spectrum of neutrons emitted from a collimated continuum source before and after transmission through the interrogated sample. The Monte Carlo transport code MCNP is used to model fast-neutron transmission experiments using a 9 Be(d, n) source (E d =5 MeV). The areal densities (number of atoms per cm 2 ), and the uncertainties, of various elements present in the sample are determined by an unfolding algorithm which includes the effects of cross-section errors and correlations. Results are displayed in the form of normalized densities, including their errors and correlations, which are then compared to the values for explosives and benign substances. Probabilistic interpretations of the results are discussed in terms of substance detection and identification. ((orig.))

  9. Illicit substance detection using Fast-Neutron Transmission Spectroscopy

    International Nuclear Information System (INIS)

    Micklich, B.J.; Harper, M.K.; Novick, A.H.; Smith, D.L.

    1994-01-01

    Fast-neutron interrogation techniques are of interest for detecting illicit substances such as explosives and drugs because of their ability to identify light elements such as carbon, nitrogen, and oxygen. Fast-Neutron Transmission Spectroscopy (FNTS) uses standard time-of-flight techniques to measure the energy spectrum of neutrons emitted from a collimated continuum source before and after transmission through the interrogated sample. The Monte Carlo transport code MCNP is used to model fast-neutron transmission experiments using a 9 Be(d,n) source [E d = 5 MeV]. The areal densities (number of atoms per cm 2 ), and the uncertainties, of various elements present in the sample are determined by an unfolding algorithm which includes the effects of cross-section errors and correlations. Results are displayed in the form of normalized densities, including their errors and correlations, which are then compared to the values for explosives and benign substances. Probabilistic interpretations of the results are discussed in terms of substance detection and identification

  10. nGEM fast neutron detectors for beam diagnostics

    International Nuclear Information System (INIS)

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

    2013-01-01

    Fast neutron detectors with a sub-millimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. A nGEM detector has been developed for the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a triple GEM gaseous detector equipped with polypropylene and polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a nGEM detector at the ISIS spallation source on the VESUVIO beam line. Beam profiles (σ x =14.35 mm, σ y =15.75 mm), nGEM counting efficiency (around 10 -4 for 3 MeV n <15 MeV), detector stability (≈4.5%) and the effect of filtering the beam with different type of materials were successfully measured. The x beam profile was compared to the one measured by a single crystal diamond detector. Finally, the efficiency of the detector was simulated exploiting the GEANT4 tool

  11. Apparatus and method for detecting contraband using fast neutron activation

    International Nuclear Information System (INIS)

    Gozani, T.; Sawa, Z.P.; Shea, P.M.

    1992-01-01

    This patent describes a method of detecting contraband within an object under investigation. It comprises: generating a beam of case neutrons; irradiating the object with the beam of fast neutrons, the fast neutrons interacting with atomic nuclei of the elements contained within the object to produce a gamma-ray spectrum having spectral lines characteristic of the elements contained within the object; measuring the spectral lines of the gamma-ray spectrum using a multiplicity of gamma-ray detectors judiciously positioned around the object; detecting the number of neutrons that pass through the object without interacting substantially with atomic nuclei within the object; determining the spatial and density distributions of the atomic nuclei of the elements contained within the object from the measured gamma-ray spectrum obtained from the multiplicity of gamma-ray detectors and the number of neutrons that pass through the object; comparing the measured spatial and density distributions of the atomic nuclei of the elements within the object with known spatial and density distributions of atomic nuclei for elements characteristic of contraband; and determining that contraband is present within the object when the comparison indicates a substantial match

  12. Optimization of CR-39 for fast neutron dosimetry applications

    International Nuclear Information System (INIS)

    Vilela, E.; Fantuzzi, E.; Giacomelli, G.; Giorgini, M.; Morelli, B.; Patrizii, L.; Serra, P.; Togo, V.

    1999-01-01

    We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: 241 Am-Be, 252 Cf and 238 Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose

  13. Measurements of the absolute neutron fluence spectrum emitted at 00 and 900 from the Little-Boy replica

    International Nuclear Information System (INIS)

    Roberts, J.H.; Gold, R.; Preston, C.C.

    1986-01-01

    Nuclear research emulsions (NRE) have been used to characterize the neutron spectrum emitted by the Little-Boy replica. NRE were irradiated at the Little-Boy surface, as well as approximately 2 m from the center of the Little-Boy replica, using polar angles of 0 0 , 30 0 , 60 0 , and 90 0 . For the NRE exposed at 2 m, neutron background was determined using shadow shields of borated polyethylene. Emulsion scanning to date has concentrated exclusively on the 2-m, 0 0 and 2-m, 90 0 locations. Approximately 5000 proton-recoil tracks have been measured in NRE irradiated at each of these locations. At the 2-m, 90 0 location, the NRE neutron spectrum extends from 0.37 MeV up to 8.2 MeV; whereas the NRE neutron spectrum at the 2-m, 0 0 location is much softer and extends only up to 2.7 MeV. NRE neutron spectrometry results at these two locations are compared with both liquid scintillator neutron spectrometry and Monte Carlo calculations. (author)

  14. Computer aided design of fast neutron therapy units

    International Nuclear Information System (INIS)

    Gileadi, A.E.; Gomberg, H.J.; Lampe, I.

    1980-01-01

    Conceptual design of a radiation-therapy unit using fusion neutrons is presently being considered by KMS Fusion, Inc. As part of this effort, a powerful and versatile computer code, TBEAM, has been developed which enables the user to determine physical characteristics of the fast neutron beam generated in the facility under consideration, using certain given design parameters of the facility as inputs. TBEAM uses the method of statistical sampling (Monte Carlo) to solve the space, time and energy dependent neutron transport equation relating to the conceptual design described by the user-supplied input parameters. The code traces the individual source neutrons as they propagate throughout the shield-collimator structure of the unit, and it keeps track of each interaction by type, position and energy. In its present version, TBEAM is applicable to homogeneous and laminated shields of spherical geometry, to collimator apertures of conical shape, and to neutrons emitted by point sources or such plate sources as are used in neutron generators of various types. TBEAM-generated results comparing the performance of point or plate sources in otherwise identical shield-collimator configurations are presented in numerical form. (H.K.)

  15. Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yavar, A.R. [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Sarmani, S.B. [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Wood, A.K. [Analytical Chemistry Application Group, Industrial Technology Division, Malaysian Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor (Malaysia); Fadzil, S.M. [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Radir, M.H. [Analytical Chemistry Application Group, Industrial Technology Division, Malaysian Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor (Malaysia); Khoo, K.S., E-mail: khoo@ukm.m [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2011-05-15

    Determination of thermal to fast neutron flux ratio (f{sub fast}) and fast neutron flux ({phi}{sub fast}) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The f{sub fast} and subsequently {phi}{sub fast} were determined using the absolute method. The f{sub fast} ranged from 48 to 155, and the {phi}{sub fast} was found in the range 1.03x10{sup 10}-4.89x10{sup 10} n cm{sup -2} s{sup -1}. These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.

  16. Design of a boron neutron capture enhanced fast neutron therapy assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu [Georgia Inst. of Technology, Atlanta, GA (United States)

    2006-12-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm 10B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The

  17. Fast neutron scintillation spectrometer in a heavy ion accelerator

    International Nuclear Information System (INIS)

    Blinov, M.V.; Gavrilov, B.P.; Ivannikova, L.L.; Kozulin, Eh.M.; Mozhaev, A.N.; Tyurin, G.P.

    1984-01-01

    Scintillation fast neutron spectrometer in a heavy ion accelerator is described in short. The spectrometer is used to measure characteristics of neutrons emitted in heavy ion interaction with different nuclei. Experiment was performed on the base of particle flight from 0.7 up to 2 m. Within the angle range of 0-150 deg. The technique is based on recording of two-dimensional neutron spectra obtained due to combination of the time-of-flight method and the method of recoil proton energy detection. Two measuring channels were used in the spectrometer. Each channel comprise both amplitude and time tracks. Detector on the base microchannel plates (MCP) generated a signal in passing the next ion bunch was used in order to obtain the time mark. Data from the scintillation block are recorded with respect to three parameters: recoil proton amplitude, time of neutron or γ-quantum arrival in respect of MCP-sensor pulse. Apparatus is carried out within the CAMAC standard. The spectrometer calibration within the 1-20 MeV neutron range was conducted in the Van-de-Graaf accelerator, and for higher energies - with the use of lightguides. Spectrometer time resolution for neutron energies of 0.5-50 MeV constituted 1.5-1.8 ns. The above measuring of neutron spectra from 1 /H2C+ 181 Ta and sup(20, 22)Ne+sup(181)Ta reaction have revealed a possibility of the experiment organization in heavy ion accelerators in the presence of strong neutron and γ-fields. Organization of multi-dimensional analysis combining two methods allows one to separate accelerator cycle, a region of the most reliable information, free of a low-energy gamma background and limited both by a dynamic threshold and a region of permissible energy values

  18. Fast analysis of carbon content by inelastic scattering of neutrons

    International Nuclear Information System (INIS)

    Heinrich, B.; Irmer, K.; Poetschke, R.

    1986-01-01

    The direct measurement of carbon concentration of conveyor belts is a difficult problem. The great penetration depth by the fast neutrons and the 4.43 MeV γ-radiation gives an especially suitable method. The measurement were performed by the following methods: excitation of γ-radiation by a Pu-Be neutron source, excitation of γ-radiation by DT-neutron generator in stationary regime, in pulse regime, or coupled with time correlated associated particle method. Furthermore, a special Monte Carlo code in which the geometry of the measuring equipment could be specified, was written to calculate the 4.43 MeV γ counting rate for backscatter geometries and for penetration geometries. The influence of conveyor belt, of content of H, O, Fe and of mass by surface for 4.43 MeV γ-radiation was calculated for application brown coal in industry. (author)

  19. NeuLand submodules exposed to fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Gasparic, Igor [Technische Univ. Darmstadt (Germany); Rudjer Boskovic Institute, Zagreb (Croatia); Aumann, Thomas [Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Boretzky, Konstanze; Heil, Michael; Simon, Haik [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Jaehrling, Simon [Technische Univ. Darmstadt (Germany); Collaboration: R3B-Collaboration

    2013-07-01

    Within the R{sup 3}B collaboration (Reactions with Relativistic Radioactive Beams), a new neutron detector NeuLAND (New Large Area Neutron Detector) is being developed. The technical design was finalized in November 2011, a fully active scintillator concept was chosen. It will be a box-shaped 2.5 x 2.5 x 3 m{sup 3} detector consisting of 3000 scintillator bars arranged in 60 planes with mutually orthogonal orientation. An array of 150 NeuLAND bars was exposed to fast ''mono-energetic'' neutrons stemming from quasi-free deuteron breakup reactions on a CH{sub 2} target (250 to 1500 AMeV). The experiment carried out at GSI in Nov. 2012 aims for determination of both time resolution and efficiency of NeuLAND submodules. Preliminary results of the analysis are presented.

  20. Quantitative fuel motion determination with the CABRI fast neutron hodoscope

    International Nuclear Information System (INIS)

    Baumung, K.; Augier, G.

    1991-01-01

    The fast neutron hodoscope installed at the CABRI reactor in Cadarache, France, is employed to provide quantitative fuel motion data during experiments in which single liquid-metal fast breeder reactor test pins are subjected to simulated accident conditions. Instrument design and performance are reviewed, the methods for the quantitative evaluation are presented, and error sources are discussed. The most important findings are the axial expansion as a function of time, phenomena related to pin failure (such as time, location, pin failure mode, and fuel mass ejected after failure), and linear fuel mass distributions with a 2-cm axial resolution. In this paper the hodoscope results of the CABRI-1 program are summarized

  1. Fast neutron reactors: the safety point of view

    International Nuclear Information System (INIS)

    Laverie, M.; Avenas, M.

    1984-01-01

    All versions of nuclear reactors present favourable and unfavourable characteristics from the point of view of safety. The safety of the installations is obtained by making efforts to utilize in the best possible way those which are favourable and by taking proper steps in the face of those which are unfavourable. The present article shows how this general principle has been applied as regards the fast neutron reactors of integrated design which have been developped in France, taking into account the specific features of this version. A qualitative method to compare the safety of this version with that of pressurized water reactors which has been widely put to the test commercially all over the world is presented. These analyses make, generally speaking, several positive characteristics stand out for these fast neutron reactors from the safety aspects [fr

  2. Chromatin damage induced by fast neutrons or UV laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L.; Constantinescu, B.; Gazdaru, D.; Mihailescu, I

    2002-07-01

    Chromatin samples from livers of Wistar rats were subjected to fast neutron irradiation in doses of 10-100 Gy or to a 248 nm excimer laser radiation, in doses of 0.5-3 MJ.m{sup -2}. The action of the radiation on chromatin was monitored by chromatin intrinsic fluorescence and fluorescence lifetimes (of bound ethidium bromide to chromatin) and by analysing fluorescence resonance energy transfer between dansyl chloride and acridine orange coupled to chromatin. For the mentioned doses of UV excimer laser radiation, the action on chromatin was more intense than in the case of fast neutrons. The same types of damage are produced by the two radiations: acidic and basic destruction of chromatin protein structure, DNA strand breaking and the increase of the distance between DNA and proteins in chromatin. (author)

  3. Chromatin damage induced by fast neutrons or UV laser radiation

    International Nuclear Information System (INIS)

    Radu, L.; Constantinescu, B.; Gazdaru, D.; Mihailescu, I.

    2002-01-01

    Chromatin samples from livers of Wistar rats were subjected to fast neutron irradiation in doses of 10-100 Gy or to a 248 nm excimer laser radiation, in doses of 0.5-3 MJ.m -2 . The action of the radiation on chromatin was monitored by chromatin intrinsic fluorescence and fluorescence lifetimes (of bound ethidium bromide to chromatin) and by analysing fluorescence resonance energy transfer between dansyl chloride and acridine orange coupled to chromatin. For the mentioned doses of UV excimer laser radiation, the action on chromatin was more intense than in the case of fast neutrons. The same types of damage are produced by the two radiations: acidic and basic destruction of chromatin protein structure, DNA strand breaking and the increase of the distance between DNA and proteins in chromatin. (author)

  4. Preliminary experiment of fast neutron imaging with direct-film method

    International Nuclear Information System (INIS)

    Pei Yuyang; Tang Guoyou; Guo Zhiyu; Zhang Guohui

    2005-01-01

    A preliminary experiment is conducted with direct-film method under the condition that fast neutron is generated by the reaction of 9 Be(d, n) on the Beijing University 4.5 MV Van de Graaff, whose energy is lower than 7 MeV. Basic characteristics of direct-film neutron radiography system are investigated with the help of samples in different materials, different thickness and holes of different diameter. The fast neutron converter, which is vital for fast neutron imaging, is produced with the materials made in China. The result indicates that fast neutron converter can meet the requirement of fast neutron imaging; further research of fast neutron imaging can be conducted on the accelerator and neutron-generator in China. (authors)

  5. Thermal and epithermal neutron fluence rate gradient measurements by PADC detectors in LINAC radiotherapy treatments-field

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, M. T., E-mail: mariate9590@gmail.com; Barros, H.; Pino, F.; Sajo-Bohus, L. [Universidad Simón Bolívar, Nuclear Physics Laboratory, Sartenejas, Caracas (Venezuela, Bolivarian Republic of); Dávila, J. [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    LINAC VARIAN 2100 is where energetic electrons produce Bremsstrahlung radiation, with energies above the nucleon binding energy (E≈5.5MeV). This radiation induce (γ,n) and (e,e’n) reactions mainly in the natural tungsten target material (its total photoneutron cross section is about 4000 mb in a energy range from 9-17 MeV). These reactions may occur also in other components of the system (e.g. multi leaf collimator). During radiation treatment the human body may receive an additional dose inside and outside the treated volume produced by the mentioned nuclear reactions. We measured the neutron density at the treatment table using nuclear track detectors (PADC-NTD). These covered by a boron-converter are employed, including a cadmium filter, to determine the ratio between two groups of neutron energy, i.e. thermal and epithermal. The PADC-NTD detectors were exposed to the radiation field at the iso-center during regular operation of the accelerator. Neutron are determined indirectly by the converting reaction {sup 10}B(n,α){sup 7}Li the emerging charged particle leave their kinetic energy in the PADC forming a latent nuclear track, enlarged by chemical etching (6N, NaOH, 70°C). Track density provides information on the neutron density through calibration coefficient (∼1.6 10{sup 4} neutrons /track) obtained by a californium source. We report the estimation of the thermal and epithermal neutron field and its gradient for photoneutrons produced in radiotherapy treatments with 18 MV linear accelerators. It was obsered that photoneutron production have higher rate at the iso-center.

  6. Determination of the neutron fluence in the welding of the 'Core shroud' of the BWR reactor core; Determinacion de la fluencia neutronica en las soldaduras del 'core shroud' del nucleo de un reactor BWR

    Energy Technology Data Exchange (ETDEWEB)

    Lucatero, M A; Xolocostli M, J V; Gomez T, A M; Palacios H, J C [ININ, 52750 Ocoyoacac, Estado de mexico (Mexico)

    2006-07-01

    With the purpose of defining the inspection frequency, in function of the embrittlement of the materials that compose the welding of the 'Core Shroud' or encircling of the core of a BWR type reactor, is necessary to know the neutron fluence received for this welding. In the work the calculated values of neutron fluence accumulated maxim (E > 1 MeV) during the first 8 operation cycles of the reactor are presented. The calculations were carried out according to the NRC Regulatory Guide 1.190, making use of the DORT code, which solves the transport equation in discreet ordinate in two dimensions (xy, r{theta}, and rz). The results in 3D were obtained applying the Synthesis method according to the guide before mentioned. Results are presented for the horizontal welding H3, H4, and H5, showing the corresponding curves to the fluence accumulated to the cycle 8 and a projection for the cycle 14 is presented. (Author)

  7. Pulsed neutron intensity from rectangular shaped light water moderator with fast-neutron reflector

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki; Iwasa, Hirokatsu

    1982-01-01

    With a view to enhancing the thermal-neutron intensity obtained from a pulsed neutron source, an experimental study has been made to determine the optimum size of a rectangular shaped light water moderator provided with fast neutron reflector of beryllium oxide or graphite, and decoupled thermal-neutronically by means of Cd sheet. The optimum dimensions for the moderator are derived for the neutron emission surface and the thickn ess, for the cases in which the neutron-producing target is placed beneath the moderator (''wing geometry'') or immediately behind the moderator (''slab geometry''). The major conclusions drawn from the experimental results are as follows. The presence of the Cd decoupler inserted between the moderator and reflector prevent the enhancement of thermal-neutron emission time gained by the provision of reflector. With a graphite reflector about 14 cm thick, (a) the optimum area of emission surface would be 25 x 25 cm 2 for wing geometry and still larger for slab geometry, and (b) the optimum moderator thickness would be 5.5 cm for slab geometry and 8.5 cm for wing geometry. It is thus concluded that a higher neutron emission intensity can be obtained with slab than with wing geometry provided that a large emission surface can be adopted for the moderator. (author)

  8. Fast Neutron Elastic and Inelastic Scattering of Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T

    1969-11-15

    Fast neutron scattering interactions with vanadium were studied using time-of-flight techniques at several energies in the interval 1.5 to 8.1 MeV. The experimental differential elastic scattering cross sections have been fitted to optical model calculations and the inelastic scattering cross sections have been compared with Hauser-Feshbach calculations, corrected for the fluctuation of compound-nuclear level widths.

  9. Theoretical and Experimental Analysis of Fast Neutron Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Van Dam, H.; Kleijn, H. R. [Reactor Instituut, Delft (Netherlands)

    1968-04-15

    The reactor physics division of the Inter-Academic Reactor Institute at Delft is concentrating its efforts in the field of fast reactor physics on problems of a more fundamental nature. The object of the programme is to determine experimentally a number of microscopic reactor physics parameters such as conversion potentials, fission ratios and Doppler coefficients for simple geometries and material compositions. Because of the extreme importance of knowledge of the neutron spectrum for the interpretation of the results, attention has initially been concentrated on both the measurement and the calculation of fast neutron spectra. The transport of neutrons in absorbing and non-absorbing heavy atom materials is studied by solving the Boltzmann equation. Both isotropic and anisotropic scattering are considered. Anisotropic scattering is treated by the P{sub n}-approximation, while flux-anisotropy is handled with the S{sub N}-method. In the code FAST-DELFT, scattering is treated up to the P{sub 4} component, a further extension of which is useless because of the lack of available cross-section data. By using this method, the effect of scattering anisotropy on the spectrum formation has been studied. In addition the influence of group cross-section inaccuracies was determined. The experimental work has been concentrated on methods to determine in-core spectra. Using home-made proportional counters with gamma-ray discrimination provisions fast neutron spectra have been measured in simple geometries. These experiments were complemented by foil measurements in the lower energy region. The results of this work are presented in this paper. (author)

  10. Symmetrized neutron transport equation and the fast Fourier transform method

    International Nuclear Information System (INIS)

    Sinh, N.Q.; Kisynski, J.; Mika, J.

    1978-01-01

    The differential equation obtained from the neutron transport equation by the application of the source iteration method in two-dimensional rectangular geometry is transformed into a symmetrized form with respect to one of the angular variables. The discretization of the symmetrized equation leads to finite difference equations based on the five-point scheme and solved by use of the fast Fourier transform method. Possible advantages of the approach are shown on test calculations

  11. A study of the NRPB fast neutron personal monitoring service

    International Nuclear Information System (INIS)

    Bartlett, D.T.; Knight, A.; Marshall, T.O.

    1975-10-01

    The NRPB Fast Neutron Personal Monitoring Service has been reviewed and modifications have been, or are being, introduced to improve the accuracy and reliability of the nuclear emulsion dosemeter employed by the Service. This report presents the conclusions of the study. Experimental results of the investigations undertaken in the course of this study, together with full details of the dosemeter and Service, are appended. (author)

  12. Fast neutron radiography of extended biological and medical objects

    International Nuclear Information System (INIS)

    Duehmke, E.; Greim, L.

    1978-01-01

    The fast neutron radiography enables us to image extended objects and yields quite different pictures than conventional roentgenograms. Using foils of cellulose nitrate and the track etching technique a γ-ray-insensitive detector is available providing sufficient imaging qualities. One of the biological neutrograms shown in the paper is of special importance because one can see a malignant tumor of the columna vertebralis. This finding was not detectable by roentgenological examination. (orig.) [de

  13. A methodology of neutronic-thermodynamics simulation for fast reactor

    International Nuclear Information System (INIS)

    Waintraub, M.

    1986-01-01

    Aiming at a general optimization of the project, controlled fuel depletion and management, this paper develop a neutronic thermodynamics simulator, SIRZ, which besides being sufficiently precise, is also economic. That results in a 75% reduction in CPU time, for a startup calculation, when compared with the same calculation at the CITATION code. The simulation system by perturbation calculations, applied to fast reactors, which produce errors smaller than 1% in all components of the reference state given by the CITATION code was tested. (author)

  14. Note: Fast neutron efficiency in CR-39 nuclear track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, S. [Dipartimento di Fisica ed Astronomia,Università di Catania, Via S. Sofia 44, 95123 Catania, Italy and INFN-LNS, Via S. Sofia 42, 95123 Catania (Italy)

    2015-03-15

    CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.

  15. Fast Neutron Detection Using Pixelated CdZnTe Spectrometers

    Science.gov (United States)

    Streicher, Michael; Goodman, David; Zhu, Yuefeng; Brown, Steven; Kiff, Scott; He, Zhong

    2017-07-01

    Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed.

  16. Influence of Neutron Spectra Unfolding Method on Fast Neutron Dose Determination

    International Nuclear Information System (INIS)

    Marinkovic, P.

    1991-01-01

    Full text: Accuracy of knowing the fast neutron spectra has great influence on equivalent dose determination. In usual fast neutron spectrum measurements with scintillation detectors based on proton recoil, the main difficulty is confidence of unfolding method. In former ones variance of obtained result is usually great and negative values are possible too, which does means that we don't now exactly is obtained neutron spectrum real one. The new unfolding method based on Shanon's information theory, which gives non-negative spectrum and relative low variance, is obtained and appropriate numerical code for application in fast neutron spectrometry based on proton recoil is realized. In this method principle of maximum entropy and maximum likelihood are used together. Unknown group density distribution functions, which are considered as desired normalized mean neutron group flux, are constl u cted using only constrain of knowing mean value. Obtained distributions are consistent to available information (counts in NCA from proton recoil), while being maximally noncommittal with respect to all other unknown circumstances. For maximum likelihood principle, distribution functions around mean value of counts in the channels of MCA are taken to be Gauss function shape. Optimal non-negative solution is searched by means of Lagrange parameter method. Nonlinear system of equations, is solved using gradient and Newton iterative algorithm. Error covariance matrix is obtained too. (author)

  17. Genes involved in yeast survival after irradiation with fast neutrons

    International Nuclear Information System (INIS)

    Bozin, D.; Milosevic, M.J.

    2001-01-01

    Life on the Earth has evolved against a continuous background of ionizing radiation. It would be expected, therefore, that all possible mutations have been produced at some time or another; man-made radiation from medical or industrial sources will not result in any new types of mutation but will simply increase the whole spectrum of mutations that occur spontaneously. Any such lesion can be mutagenic and, in principle, lethal. To counteract the consequences of DNA damage, evolution has equipped all living cells with an intricate network of defense and repair systems. Together, these systems act as a kind of nuclear 'immune system' that is able to recognize and eliminate many types of DNA lesions. In the case of the yeast Saccharomyces cerevisiae, in these processes over 30 RAD genes participate. We tested the survival of haploid and diploid rad1 yeast mutant strains at a dose of 15 Gy of γ or fast neutron radiation. We demonstrated that the lethality of rad1 mutants both haploid and diploid are significantly higher after fast neutron irradiation. The results indicate to the role and position of these genes in the DNA repair of damages specifically induced by fast neutrons. (authors)

  18. Effects of fast neutrons on chromatin: dependence on chromatin structure

    Energy Technology Data Exchange (ETDEWEB)

    Radu, L. [Dept. of Molecular Genetics, V. Babes National Inst., Bd. Timisoara, Bucharest (Romania); Constantinescu, B. [Dept. of Cyclotron, H. Hulubei National Inst., Bucharest (Romania); Gazdaru, D. [Dept. of Biophysics, Physics Faculty, Univ. of Bucharest (Romania)

    2002-07-01

    The effects of fast neutrons (10-100 Gy) on chromatin extracted from normal (liver of Wistar rats) and tumor (Walker carcinosarcoma maintained on Wistar rats) tissues were compared. The spectroscopic assays used were (i) chromatin intrinsic fluorescence, (ii) time-resolved fluorescence of chromatin-proflavine complexes, and (iii) fluorescence resonance energy transfer (FRET) between dansyl chloride and acridine orange coupled to chromatin. For both normal and tumor chromatin, the intensity of intrinsic fluorescence specific for acidic and basic proteins decreased with increasing dose. The relative contributions of the excited-state lifetime of proflavine bound to chromatin were reduced upon fast-neutron irradiation, indicating a decrease in the proportion of chromatin DNA available for ligand binding. The Forster energy transfer efficiencies were also modified by irradiation. These effects were larger for chromatin from tumor tissue. In the range 0-100 Gy, fast neutrons induced alterations in DNA and acidic and basic proteins, as well as in global chromatin structure. The radiosensitivity of chromatin extracted from tumor tissue seems to be higher than that of chromatin extracted from normal tissue, probably because of its higher euchromatin (loose)-heterochromatin (compact) ratio. (author)

  19. Effects of fast neutrons on chromatin: dependence on chromatin structure

    International Nuclear Information System (INIS)

    Radu, L.; Constantinescu, B.; Gazdaru, D.

    2002-01-01

    The effects of fast neutrons (10-100 Gy) on chromatin extracted from normal (liver of Wistar rats) and tumor (Walker carcinosarcoma maintained on Wistar rats) tissues were compared. The spectroscopic assays used were (i) chromatin intrinsic fluorescence, (ii) time-resolved fluorescence of chromatin-proflavine complexes, and (iii) fluorescence resonance energy transfer (FRET) between dansyl chloride and acridine orange coupled to chromatin. For both normal and tumor chromatin, the intensity of intrinsic fluorescence specific for acidic and basic proteins decreased with increasing dose. The relative contributions of the excited-state lifetime of proflavine bound to chromatin were reduced upon fast-neutron irradiation, indicating a decrease in the proportion of chromatin DNA available for ligand binding. The Forster energy transfer efficiencies were also modified by irradiation. These effects were larger for chromatin from tumor tissue. In the range 0-100 Gy, fast neutrons induced alterations in DNA and acidic and basic proteins, as well as in global chromatin structure. The radiosensitivity of chromatin extracted from tumor tissue seems to be higher than that of chromatin extracted from normal tissue, probably because of its higher euchromatin (loose)-heterochromatin (compact) ratio. (author)

  20. Comparison of four NDT methods for indication of reactor steel degradation by high fluences of neutron irradiation

    Czech Academy of Sciences Publication Activity Database

    Tomáš, Ivan; Vértesy, G.; Pirfo Barroso, S.; Kobayashi, S.

    2013-01-01

    Roč. 265, DEC (2013), s. 201-209 ISSN 0029-5493 Institutional support: RVO:68378271 Keywords : neutron irradiation * steel degradation * nuclear reactor pressure vessel * magnetic NDT * magnetic minor hysteresis loops * Magnetic Barkhausen Emission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.972, year: 2013 http://www.sciencedirect.com/science/article/pii/S0029549313004664

  1. Radiation protection aspects of a high flux, fast neutron generator

    International Nuclear Information System (INIS)

    DeLuca, P.M.; Torti, R.P.; Chenevert, G.M.; Tesmer, J.R.; Kelsey, C.A.

    1976-01-01

    During the development and operation of a gas target, DT neutron generator for use in cancer therapy, two radiation hazards were routinely encountered - personnel exposure to neutrons and to tritium. The principal hazard was irradiation by fast neutrons. By assembling the source below ground level, adding shielding and the use of a controlled access, key identification interlock, the neutron hazard has been reduced. With the present source strength of 2 x 10 12 n/sec, an average neutron dose rate in the control room of 20 mrem/hr was measured- a level compatible with a limited run schedule. The second hazard was exposure to tritium in both gaseous and solid forms. A target inventory of 90 Ci, and overall inventory of 500 Ci, and the need to modify and repair the generator present significant potential hazard due to tritium exposure. The use of protective gloves, wipe tests, urine assays, continuous room air monitoring, and equipment decontamination minimized personnel exposure and effectively confined contamination. The dose due to tritium has been ∼ 0.5 rem/year and negligible spread of contamination has occurred

  2. The multielement potential of fast neutron cyclic activation analysis

    International Nuclear Information System (INIS)

    Nonie, S.E.; Randle, K.

    1994-01-01

    Cyclic neutron activation analysis (CNAA) has, in recent years been developed as a useful analytical tool for the assay of short-lived isotopes in single element situations. The work described in this paper investigates the potential of the technique for composite samples having a wide range of elements that produce short-lived and long-lived isotopes on neutron irradiation. Accelerator-derived neutrons with average energies of 3 MeV, 6 MeV and 14 MeV were employed in what has been dubbed 'Fast Neutron Cyclic Neutron Activation Analysis' (FNCAA). The approach to multi-element analysis entailed: determination of cycle parameters in single element samples via the reactions 27 Al(n,p) 27 Mg(9.6 min,E γ =840keV), and 137 Ba(n,n 'γ137m Ba(2.3 min,E γ 137m Ba(2.3 min,E γ =662 keV), a test of the method on a composite rock sample, determination of analytical sensitivities using both powdered kale and rock standards and a comparison of analytical results with other techniques. The results obtained in all these measurements are presented and discussed. (author) 10 refs.; 3 figs.; 5 tabs

  3. Polarization of fast neutrons in VVR-M reactor

    International Nuclear Information System (INIS)

    Garusov, E.A.; Lifshits, E.P.; Petrov, Yu.V.

    1987-01-01

    Neutron polarization in the reactor leads to circular polarization of γ quanta emitted both in radiational capture of neutrons and in the transition of nuclei excited as a result of inelastic scattering to the ground state. This may be used to determine the polarization of reactor neutrons. The circular polarization of γ quanta at light-water and graphite targets at the center of the active zone of the VVR-M reactor at the B.P. Konstantinov Leningrad Institute of Nuclear Physics was recently measured. A simplified experimental scheme is shown. Fast neutrons leaving the active zone of the reactor were excited in the inelastic scattering at the target nuclei. The polarization of the γ quanta emitted by nuclei in transitions to the ground state was measured by a polarimeter positioned above the active zone. The reason for the circular polarization of γ quanta may also be nonconservation of P parity on account of weak interaction in the capture of a neutron by hydrogen

  4. Activation measurements of fast neutron radiative capture for 139La

    International Nuclear Information System (INIS)

    Luo, Junhua; Han, Jiuning; Liu, Rong; Jiang, Li; Liu, Zhenlai; Sun, Guihua; Ge, Suhong

    2013-01-01

    The neutron capture cross section of the neutron magic isotope 139 La has been measured relative to that of 27 Al by means of the activation method. The fast neutrons were produced via the 3 H(d,n) 4 He reaction on Pd-300 neutron generator. The natural high-purity La 2 O 3 powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The new values for E n =13.5±0.2, 14.1±0.2, and 14.8±0.2 MeV are found to be 1.30±0.08, 1.15±0.08 and 0.99±0.07 mb, respectively. Results were discussed and compared with some corresponding values found in the literature. - Highlights: ► D–T neutron source was used to measure cross sections using activation method. ► 27 Al(n,α) 24 Na was used as the monitor for the measurement. ► The cross sections for the (n,γ) reactions on neutron magic isotope 139 La have been measured. ► The data for 139 La(n,γ) 140 La reaction are presented. ► The results were compared with previous data and with evaluation data

  5. Effect of neutron anisotropic scattering in fast reactor analysis

    International Nuclear Information System (INIS)

    Chiba, Gou

    2004-01-01

    Numerical tests were performed about an effect of a neutron anisotropic scattering on criticality in the Sn transport calculation. The simplest approximation, the consistent P approximation and the extended transport approximation were compared with each other in one-dimensional slab fast reactor models. JAERI fast set which has been used for fast reactor analyses is inadequate to evaluate the effect because it doesn't include the scattering matrices and the self-shielding factors to calculate the group-averaged cross sections weighted by the higher-order moment of angular flux. In the present study, the sub-group method was used to evaluate the group-averaged cross sections. Results showed that the simplest approximation is inadequate and the transport approximation is effective for evaluating the anisotropic scattering. (author)

  6. Accelerator requirements for fast-neutron interrogation of luggage and cargo

    International Nuclear Information System (INIS)

    Micklich, B.J.; Fink, C.L.; Yule, T.J.

    1995-01-01

    Several different fast-neutron based techniques are being studied for the detection of contraband substances in luggage and cargo containers. The present work discusses the accelerator requirements for fast-neutron transmission spectroscopy (FNTS), pulsed fast-neutron analysis (PFNA), and 14-MeV neutron interrogation. These requirements are based on the results of Monte-Carlo simulations of neutron or gamma detection rates. Accelerator requirements are driven by count-rate considerations, spatial resolution and acceptable uncertainties in elemental compositions. The authors have limited their analyses to luggage inspection with FNTS and to cargo inspection with PFNA or 14-MeV neutron interrogation

  7. Study on neutron streaming effect in large fast critical assembly

    International Nuclear Information System (INIS)

    Takeda, Toshikazu; Yamaoka, Mitsuaki; Sakurai, Shungo; Tanimoto, Koichi; Abe, Yuhei

    1981-03-01

    A cell calculation method taking into account the neutron leakage from a cell and a transport calculation method treating the neutron streaming have been developed, and their applicability has been investigated. In the cell calculation method, the neutron leakage in the perpendicular direction to plates was treated by introducing an albedo collision probability which is a first-flight collision probability incorporating albedos at cell boundaries, and that in the parallel direction was treated by the pseudo absorption method. The use of the albedo collision probability made it possible to calculate the flux tilt in a cell exactly. This cell calculation method was applied to two slab models where fuel drawers were stacked in perpendicular and parallel directions to plates. Cell averaged cross sections calculated by the proposed method agreed well with those obtained from exact transport calculations treating the plate-wise heterogeneity, while the infinite cell calculation and the conventional pseudo absorption method produced about 2% errors in the cell-averaged cross sections. The cell-averaging procedure for control-rod channels was also proposed, and this method was applied to the calculation of control-rod worths and control-rod position worths. A transport calculation method based on the response matrix method has been proposed to treat the neutron streaming in fast critical assemblies directly. A response matrix code in two dimensional XY geometry RES2D was made. The accuracy of response matrices obtained from the RES2D code was checked by applying it to a slab cell and by comparing cell-averaged cross sections and k-infinity with those from a reference cell calculation based on the collision probability. The agreement of the results was good, and it was found that the response matrix method is very promising for the treatment of the neutron streaming in fast critical assemblies. (author)

  8. A high gain energy amplifier operated with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Rubbia, C. [CERN, Geneva (Switzerland)

    1995-10-01

    The basic concept and the main practical considerations of an Energy Amplifier (EA) have been exhaustively described elsewhere. Here the concept of the EA is further explored and additional schemes are described which offer a higher gain, a larger maximum power density and an extended burn-up. All these benefits stem from the use of fast neutrons, instead of thermal or epithermal ones, which was the case in the original study. The higher gain is due both to a more efficient high energy target configuration and to a larger, practical value of the multiplication factor. The higher power density results from the higher permissible neutron flux, which in turn is related to the reduced rate of {sup 233}Pa neutron captures (which, as is well known, suppress the formation of the fissile {sup 233}U fuel) and the much smaller k variations after switch-off due to {sup 233}Pa decays for a given burn-up rate. Finally a longer integrated burn-up is made possible by reduced capture rate by fission fragments of fast neutrons. In practice a 20 MW proton beam (20 mA @ 1 GeV) accelerated by a cyclotron will suffice to operate a compact EA at the level of {approx} 1 GW{sub e}. The integrated fuel burn-up can be extended in excess of 100 GW d/ton, limited by the mechanical survival of the fuel elements. Radio-Toxicity accumulated at the end of the cycle is found to be largely inferior to the one of an ordinary Reactor for the same energy produced. Schemes are proposed which make a {open_quotes}melt-down{close_quotes} virtually impossible. The conversion ratio, namely the rate of production of {sup 233}U relative to consumption is generally larger than unity, which permits production of fuel for other uses. Alternatively the neutron excess can be used to transform unwanted {open_quotes}ashes{close_quotes} into more acceptable elements.

  9. Fast-neutron activation analysis of manganese nodules

    International Nuclear Information System (INIS)

    Michaelis, W.; Fanger, H.U.; Mueller, A.; Pepelnik, R.

    1976-01-01

    The present paper describes the development of a new nuclear method that allows rapid determinations of the most relevant metals Ni and Cu without sample treatment, thus being particularly suited for quasi-continuous elemental analyses in mining and processing. The measurement is based on fast-neutron activation using Cockcroft-Walton generators, sealed neutron tubes or, possibly, (α,n)-type natural sources. Fast-neutron activation of manganese nodules is dominated by the (n,p)-reactions on Si, Al, Fe; the (n,α)-reaction on Mn and the (n,2n)-reaction on Cu. By choosing appropriate irradiation and cooling periods gamma-ray activities with comparatively simple spectral distributions are induced. From these spectra the Mn/Fe ratio in the nodules can be determined without the elaborate procedures usually required in absolute methods for eliminating systematic errors from fluctuations in sample and/or irradiation parameters. It is connected with the absolute Ni and Cu contents via well-known geochemical correlations which according to a lot of statistical data apply to quite different deposits and nodule types in the Pacific. Using these correlations the determination of the most important metals reduces to the evaluation of a peak area ratio. Measurements of the neutron flux distribution and the apparent sample density are unnecessary. The simple structure of the spectra allows the application of detectors with modest energy resolution, e.g. scintillation counters which can be manufactured as ruggedized crystal assemblies with great resistance to thermal and mechanical shock. The method is described in detail and possible interference, in particular from thermal and epithermal neutrons, are discussed. (orig.) [de

  10. Fast neutron dosimetry. Progress report, July 1, 1979-June 30, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Attix, F.H.

    1980-01-01

    Progress is reported in: the development and testing of new gas mixtures more suitable for fast neutron dosimetry using the common A150-type Tissue-equivalent plastic ion chambers; comparison of photon doses determined with a graphite-walled proportional counter and with paired dosimeters irradiated by 14.8-MeV neutrons; a detector for the direct measurement of LET distributions from irradiation with fast neutrons; LET distributions from fast neutron irradiation of TE-plastic and graphite measured in a cylindrically symmetric geometry; progress in development of a tandem fast neutron and /sup 60/Co gamma ray source irradiation facility; an approach to the correlation of cellular response with lineal energy; calculated and measured HTO atmospheric dispersion rates within meters of a release site; application of cavity theory to fast neutrons; and fast neutron dosimetry by thermally stimulated currents in Al/sub 2/O/sub 3/. (GHT)

  11. Fast neutron dosimetry. Progress report, July 1, 1979-June 30, 1980

    International Nuclear Information System (INIS)

    Attix, F.H.

    1980-01-01

    Progress is reported in: the development and testing of new gas mixtures more suitable for fast neutron dosimetry using the common A150-type Tissue-equivalent plastic ion chambers; comparison of photon doses determined with a graphite-walled proportional counter and with paired dosimeters irradiated by 14.8-MeV neutrons; a detector for the direct measurement of LET distributions from irradiation with fast neutrons; LET distributions from fast neutron irradiation of TE-plastic and graphite measured in a cylindrically symmetric geometry; progress in development of a tandem fast neutron and 60 Co gamma ray source irradiation facility; an approach to the correlation of cellular response with lineal energy; calculated and measured HTO atmospheric dispersion rates within meters of a release site; application of cavity theory to fast neutrons; and fast neutron dosimetry by thermally stimulated currents in Al 2 O 3

  12. Induced effects of gamma-rays and fast neutrons on the D.C. electric resistivity of polyethylene for high level dosimetry

    International Nuclear Information System (INIS)

    Youssef, S.K.; Mashad, A.M.; Osiris, W.C.; Adawi, M.A.

    1988-01-01

    The effects of gamma- and neutron-irradiations on the D.C. electric resistivity of polyethylene were investigated. The results showed that, the D.C. electric resistivity of polyethylene decreased as the samples irradiation by gamma doses as well as fast neutron fluences over the ranges 10 2 -6x10 6 Gy, and 10 8 -10 11 n/cm 2 , respectively. Moreover, electric resistivity of the polyethylene samples indicated more sensitivity change when irradiated by fast neutrons in comparison with equivalent doses of gamma-radiation. Semi-empirical formulae were deduced for the calculation of gamma-dose and/or neutron fluence from the changes in the electric resistivity of the detector. Storage of the irradiated specimens at room decay temperature showed a continuous increase in the relative fade of electric resistivity by recovery with time. The retained electric resistivity by recovery showed values of about 47% and 33% for post specimens irradiated by 6x10 6 Gy and 1x10 11 n/cm 2 , respectively, after 80 hours

  13. On the problem of monitoring the neutron parameters of the Fast Energy Amplifier

    International Nuclear Information System (INIS)

    Behringer, K.; Wydler, P.

    1998-10-01

    The conceptual Fast Energy Amplifier, proposed by Rubbia et al. (1995), consists of a combination of a U-233/Th-232 fuelled fast-neutron subcritical facility with a proton accelerator. An intense beam of 1 GeV protons is injected into liquid lead at the core centre and drives the reactor by producing spallation neutrons. The burst of spallation neutrons produced by a single proton alters the basic neutron statistics which are well known for thermal neutrons in conventional nuclear reactors. A short assessment of standard neutron noise analysis methods is made with respect to monitoring neutron parameter data. (author)

  14. Preliminary investigations of Monte Carlo Simulations of neutron energy and LET spectra for fast neutron therapy facilities

    International Nuclear Information System (INIS)

    Kroc, T.K.

    2009-01-01

    No fast neutron therapy facility has been built with optimized beam quality based on a thorough understanding of the neutron spectrum and its resulting biological effectiveness. A study has been initiated to provide the information necessary for such an optimization. Monte Carlo studies will be used to simulate neutron energy spectra and LET spectra. These studies will be bench-marked with data taken at existing fast neutron therapy facilities. Results will also be compared with radiobiological studies to further support beam quality ptimization. These simulations, anchored by this data, will then be used to determine what parameters might be optimized to take full advantage of the unique LET properties of fast neutron beams. This paper will present preliminary work in generating energy and LET spectra for the Fermilab fast neutron therapy facility.

  15. Fast neutron dosimetry: [Progress report, 1986-1987

    International Nuclear Information System (INIS)

    DeLuca, P.M. Jr.; Gould, M.N.; Meisner, L.F.; Pearson, D.W.

    1987-01-01

    A new research area was initiated in ultrasoft x-rays with the University of Wisconsin 1-GeV electron storage ring used as a radiation source. A new beam line and irradiation apparatus was designed and constructed. Amongst the distinguishing features are an irradiation vessel of considerable generality allowing many types of radiological/biological experiments to be performed; the ability to maintain low-pressure, high humidity environments with good control; and a computer controlled sample slide for [X,Y,Z] motions of high precision that allows fully controlled velocities and accelerations for complex sample irradiations. Work in the area of chromosomal aberration studies has continued after the completion of the investigation into the possible synergistic effects of mixed beams of neutrons and photons. Of special interest is the damage dependence on absorbed dose and dose rate for low-dose and low-dose rate exposures to high LET radiation. A unique microdosimetric instrument was employed in the continuing effort to measure dose distribution in LET from fast neutron irradiation of metal-metal oxide walls. Our purpose is to determine this distribution for oxygen, an element of critical importance to fast neutron dosimetry. 31 refs., 7 figs., 2 tabs

  16. Detection of hidden explosives by fast neutron activation analysis

    International Nuclear Information System (INIS)

    Li Xinnian; Guo Junpeng; Luo Wenyun; Wang Chuanshan; Fang Xiaoming; Yu Tailiu

    2008-01-01

    The paper describes the method and principle for detection of hidden explosive by fast neutron activation analysis (FNAA). The method of detection of explosives by FNAA has the specific properties of simple determination equipments, high reliability, and low detecting cost, and would be beneficial to the applicability and popularization in the field of protecting and securing nation. The contents of nitrogen and oxygen in four explosives, more then ten common materials and TNT samples covered with soil, were measured by FNAA. 14 MeV fast neutrons were generated from (d, t) reaction with a 400 kV Cockcroft Walton type accelerator. The two-dimension distributions for nitro- gen and oxygen counting rates per unit mass of determined matters were obtained, and the characteristic area of explosives and non-explosives can be defined. By computer aided pattern recognition, the samples were identified with low false alarm or omission rates. The Monte-Carlo simulation indicates that there is no any radiation at 15 m apart from neutron source and is safe for irradiation after 1 h. It is suggested that FNAA may be potential in remote controlling for detection hidden explosive system with multi-probe large array. (authors)

  17. Fast neutron spectrometry and dosimetry; Spectrometrie et dosimetrie des neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Blaize, S; Ailloud, J; Mariani, J; Millot, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    We have studied fast neutron spectrometry and dosimetry through the recoil protons they produce in hydrogenated samples. In spectrometric, we used nuclear emulsions, in dosimetric, we used polyethylene coated with zinc sulphide and placed before a photomultiplier. (author)Fren. [French] Nous avons etudie la spectrometrie et la dosimetrie des neutrons rapides en utilisant les protons de recul qu'ils produisent dans une matiere hydrogenee. En spectrometrie, nous avons employe des emulsions nucleaires, en dosimetrie, du polyethylene recouvert de sulfure de zinc place devant un photomultiplicateur. (auteur)

  18. Measured and evaluated fast neutron cross sections of elemental nickel

    International Nuclear Information System (INIS)

    Guenther, P.; Smith, A.; Smith, D.; Whalen, J.; Howerton, R.

    1975-07-01

    Fast neutron total and scattering cross sections of elemental nickel are measured. Differential elastic scattering cross sections are determined from incident energies of 0.3 to 4.0 MeV. The cross sections for the inelastic neutron excitation of states at: 1.156 +- 0.015, 1.324 +- 0.015, 1.443 +- 0.015, 2.136 +- 0.013, 2.255 +- 0.030, 2.449 +- 0.030, 2.614 +- 0.020 and 2.791 +- 0.025 MeV are measured to incident neutron energies of 4.0 MeV. The total neutron cross sections are determined from 0.25 to 5.0 MeV. The experimental results are discussed in the context of optical and statistical models. It is shown that resonance width-fluctuation and correlation effects are significant. The present experimental and theoretical results, together with previously reported values, are used to construct a comprehensive evaluated elemental data file in the ENDF format. Some comparisons are made with previously reported evaluated files. In addition, some selected reactions which are widely used in dosimetry and other applications are presented as supplemental evaluated isotopic-data files. The numerical quantities are presented in tabular form. (3 tables, 29 figures)

  19. Research on Fast-Doppler-Broadening of neutron cross sections

    International Nuclear Information System (INIS)

    Li, S.; Wang, K.; Yu, G.

    2012-01-01

    A Fast-Doppler-Broadening method is developed in this work to broaden Continuous Energy neutron cross-sections for Monte Carlo calculations. Gauss integration algorithm and parallel computing are implemented in this method, which is unprecedented in the history of cross section processing. Compared to the traditional code (NJOY, SIGMA1, etc.), the new Fast-Doppler-Broadening method shows a remarkable speedup with keeping accuracy. The purpose of using Gauss integration is to avoid complex derivation of traditional broadening formula and heavy load of computing complementary error function that slows down the Doppler broadening process. The OpenMP environment is utilized in parallel computing which can take full advantage of modern multi-processor computers. Combination of the two can reduce processing time of main actinides (such as 238 U, 235 U) to an order of magnitude of 1∼2 seconds. This new method is fast enough to be applied to Online Doppler broadening. It can be combined or coupled with Monte Carlo transport code to solve temperature dependent problems and neutronics-thermal hydraulics coupled scheme which is a big challenge for the conventional NJOY-MCNP system. Examples are shown to determine the efficiency and relative errors compared with the NJOY results. A Godiva Benchmark is also used in order to test the ACE libraries produced by the new method. (authors)

  20. The desing study of high voltage plasma focus for a large fluence neutron source by using a water capacitor bank

    International Nuclear Information System (INIS)

    Ueno, Isao; Kobata, Tadasuke

    1983-01-01

    A new possibility for high intensity neutron source (HINS) would be opened by the plasma focus device if we have a high voltage capacitor bank. A scaling law of neutron yield for D-T gas discharge in plasma focus device is obtained after Imshennik, Filippov and Filippova. The resulting scaling law shows the realizability of the D-T HINS by the use of plasma focus, provided that the device is operated under a high voltage condition. Until now, it has been difficult to construct the high voltage capacitor bank of long life, for example with V 0 =300kV, C 0 =200μF and L 0 --5nH necessary in the level of HINS. It becomes possible to design this capacitor bank by using the coaxial water capacitor which has been developed for the electron and ion beam accelerator. The size of a capacitor designed for V 0 =300kV, C 0 =1μF is phi5m x 22m. Two hundred capacitors are used in parallel in order to get the 200μF. (author)

  1. Random mask optimization for fast neutron coded aperture imaging

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, Kyle [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Univ. of California, Los Angeles, CA (United States); Marleau, Peter [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Brubaker, Erik [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-05-01

    In coded aperture imaging, one of the most important factors determining the quality of reconstructed images is the choice of mask/aperture pattern. In many applications, uniformly redundant arrays (URAs) are widely accepted as the optimal mask pattern. Under ideal conditions, thin and highly opaque masks, URA patterns are mathematically constructed to provide artifact-free reconstruction however, the number of URAs for a chosen number of mask elements is limited and when highly penetrating particles such as fast neutrons and high-energy gamma-rays are being imaged, the optimum is seldom achieved. In this case more robust mask patterns that provide better reconstructed image quality may exist. Through the use of heuristic optimization methods and maximum likelihood expectation maximization (MLEM) image reconstruction, we show that for both point and extended neutron sources a random mask pattern can be optimized to provide better image quality than that of a URA.

  2. Ionizing Energy Depositions After Fast Neutron Interactions in Silicon

    CERN Document Server

    Bergmann, Benedikt; Caicedo, Ivan; Kierstead, James; Takai, Helio; Frojdh, Erik

    2016-01-01

    In this study we present the ionizing energy depositions in a 300 μm thick silicon layer after fast neutron impact. With the Time-of-Flight (ToF) technique, the ionizing energy deposition spectra of recoil silicons and secondary charged particles were assigned to (quasi-)monoenergetic neutron energies in the range from 180 keV to hundreds of MeV. We show and interpret representative measured energy spectra. By separating the ionizing energy losses of the recoil silicon from energy depositions by products of nuclear reactions, the competition of ionizing (IEL) and non-ionizing energy losses (NIEL) of a recoil silicon within the silicon lattice was investigated. The data give supplementary information to the results of a previous measurement and are compared with different theoretical predictions.

  3. Optimization of CR-39 for fast neutron dosimetry applications

    CERN Document Server

    Vilela, E; Giacomelli, G; Giorgini, M; Morelli, B; Patrizii, L; Serra, P; Togo, V

    1999-01-01

    We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: sup 2 sup 4 sup 1 Am-Be, sup 2 sup 5 sup 2 Cf and sup 2 sup 3 sup 8 Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose.

  4. Fast neutron attenuation measurements for detection of illicit materials

    International Nuclear Information System (INIS)

    Lee, Hee Seock; Chung, Chin Wha; Guon, Ki Il; Lee, Bo Young; Ko, Seung Kook; Shin, Yong Mu

    2002-01-01

    Experiments were carried out to develop a novel method using neutron attenuation for the detection of illicit materials. By using pulsed fast neutrons generated from a Bi target bombarded with a 2 GeV electron beam, attenuation spectra of C, N, and O have been measured to study the feasibility of a practical application. The spectral dependence on the material thickness and the geometrical distribution as well as the ability to identify different elements in a layered environment have been studied. For the elements mentioned here, the total cross sections have been obtained from the measured attenuation spectra and compared with ENDF-VI, which showed good agreement. The study confirms that a conventional low energy electron linac can be put into a practical use, and some practical idea is presented

  5. Prototype fast neutron counter for the assay of impure plutonium

    International Nuclear Information System (INIS)

    Wachter, J.R.; Adams, E.L.; Ensslin, N.

    1987-01-01

    A fast coincident neutron counter using liquid scintillators and gamma-ray/neutron pulse-shape discrimination has been constructed for the analysis of plutonium samples with unknown self-multiplication and (α,n) production. The counter was used to measure plutonium-bearing materials that cover a range of masses and (α,n) reaction rates of importance to the safeguards community. Measured values of the 240 Pu effective mass differed, on average, from their declared values by 0.4% for plutonium oxides and by -2.2% for metal and MgO-loaded samples. Poorer results were obtained for materials with large (α,n) reaction rates and low self-multiplication such as plutonium ash and plutonium fluoride

  6. Axial distribution of absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.

    1988-11-01

    The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)

  7. Modern methods to improve the accuracy in fast neutron dosimetry

    International Nuclear Information System (INIS)

    Baers, B.; Karnani, H.; Seren, T.

    1985-01-01

    In order to improve the quality of fast neutron dose estimates at the reactor pressure vessel (PV) some modern methods are presented. In addition to basic principles, some error reduction procedures are also presented based on the combined use of relative measurements, direct sample taking from the pressure vessel and the use of iron and niobium as dosimeters. The influence of large systematic errors could be significantly reduced by carrying out relative measurements. This report also presents the successful use of niobium as a dosimeter by destructive treatment of PV samples. (author)

  8. Estimation of sulfur in coal by fast neutron activation

    International Nuclear Information System (INIS)

    Das, G.C.; Bhattacharyya, P.K.

    1995-01-01

    A simple method is described for estimation of sulfur in coal using fast neutron activation of sulfur, i.e. 32 S(n,p) 32 P and subsequent measurement of 32 P β-activity (1.72 MeV) by a Geiger-Mueller counter. Since the sulfur content of Indian coal ranges from 0.25 to 3%, simulated samples of coal containing sulfur in the range from 0.25 to 3% and common impurities like oxides of aluminium, calcium, iron and silicon have been used to establish the method. (author). 6 refs., 2 figs., 1 tab

  9. Nuclear theory for fast neutron nuclear data evaluation

    International Nuclear Information System (INIS)

    1988-11-01

    The proceedings contain all invited and contributed papers presented at the Advisory Group Meeting on Nuclear Theory for Fast Neutron Data Evaluation held in Beijing 12-16 October 1987, as well as the conclusions and recommendations and the Chairman's summary of the meeting. The meeting presentations have been divided into six sessions devoted to the following topics: introductory speech (1 paper), optical potential (9 papers), compound nuclear theory (10 papers), pre-compound nuclear theory (13 papers), isomeric cross-section (1 paper) and intercomparison of nuclear model computer codes (1 paper). A separate abstract was prepared for each of these papers. Refs, figs and tabs

  10. Fast neutrons and the optical model: some observations

    International Nuclear Information System (INIS)

    Smith, A.B.; Lawson, R.D.; Guenther, P.T.

    1985-01-01

    The optical model of fast-neutron-induced phenomena is considered from the observational viewpoint. Experimental characteristics governing the reliability of the modeling are outlined with attention to implications on model parameters and their uncertainties. The physical characteristics of experimentally-deduced ''regional'' and ''specific'' model parameters are examined including: parameter trends with mass and energy, implications of collective effects, and fundamental relations between real and imaginary potentials. These physical properties are illustrated by studies in the A=60 and 90 regions. General trends are identified and outstanding issues cited. Throughout, the approach is that of observational interpretation for basic and applied purposes. 20 refs., 11 figs., 2 tabs

  11. Gas loop - continuous measurement of thermal and fast neutron fluxes

    International Nuclear Information System (INIS)

    Droulers, Y.; Pleyber, G.; Sciers, P.; Maurin, G.

    1964-01-01

    The measurement method described in this report can be applied both to thermal and fast neutron fluxes. A description is given of two practical applications in each of these two domains. This method is particularly suitable for measurements carried out on 'loop' type equipment. The measurement of the relative flux variations are carried out with an accuracy of 5 per cent. The choice of the shape of the gas circuit leaves a considerable amount of liberty for the adaptation of the measurement circuit to the experimental conditions. (authors) [fr

  12. Non-destructive characterization using pulsed fast-thermal neutrons

    International Nuclear Information System (INIS)

    Womble, P.C.

    1995-01-01

    Explosives, illicit drugs, and other contraband materials contain various chemical elements in quantities and ratios that differentiate them from each other and from innocuous substances. Furthermore, the major chemical elements in coal can provide information about various parameters of importance to the coal industry. In both examples, the non-destructive identification of chemical elements can be performed using pulsed fast-thermal neutrons that, through nuclear reactions, excite the nuclei of the various elements. This technique is being currently developed for the dismantling of nuclear weapons classified as trainers, and for the on-line coal bulk analysis. (orig.)

  13. Metal ion protection of DNA to fast neutron irradiation

    International Nuclear Information System (INIS)

    Constantinescu, B.; Bugoi, R.; Radulescu, I.; Radu, L.

    1998-01-01

    The most important effects of the ionising radiation are the single and double strand breaks (SSB and DBS), modifications of the DNA bases and deoxyribose, as well as the occurrence of alkali and heat labile sites (revealed as strand breaks after alkaline or thermic treatment of irradiated DNA). The ionising particles can have either direct effects on the DNA constituents or indirect effects, mediated by the OH - radicals, produced by water radiolysis. The occurrence of SSB and DSB in the chromatin DNA strands is supposed to hinder the DNA-dye complex formation. Usually, the dyes present different fluorescence parameters in the two possible states, so one can correlate the lifetime or the quantum yield with the extent of the damage. We took into account the protective effect offered both by histones, which behave as 'scavenger molecules' for OH - radicals and by the high compactness of DNA chromatin. Similar protective effects might be the results of the metallic ion addition which triggers some conformational transitions of the chromatin DNA towards a highly compacted structure. In this paper we present a study of the complexes of fast neutron irradiated chromatin with proflavine. Fluorimetric and time resolved spectroscopic determinations (single photon counting method) of chromatin-Pr complexes were realised. Information regarding the chromatin protein damage were obtained by monitoring the fluorescence of Trp. The chromatin was irradiated (20-100 Gy) with fast neutrons, obtained by the reaction of 13.5 MeV deuterons on a thick beryllium target at the IFIN-HH U-120 Cyclotron. The dose mean lineal energy in water at the point of interest was 50 keV/m and the mean dose rate was 1.5 Gy/min. By fluorescence determinations, changes of the Pr intercalation parameters in fast neutron irradiated chromatin DNA have been observed. Fluorescence techniques provide valuable information on the binding equilibrium by considering the radiation deexcitation of the complex. The

  14. Study on the fast neutron sensitivity of thermoluminescent detectors

    International Nuclear Information System (INIS)

    Szabo, P.P.; Palfalvi, J.

    1984-03-01

    Fast neutron (14.7 MeV) sensitivity of several thermoluminescent detectors was determined. The investigated detectors were MTS-N type pellets (made in Poland) used routinely in the authors' institute for personnel dosimetry, 7 LiF powder used for accident dosimetry, CaSO 4 :Dy and CaSO 4 :Tm powders (made in Hungary) used for enviromental monitoring and space dosimetry. Both free-in-air and on-phantom irradiations were performed. The new results are compared with responses calculated and measured earlier. (author)

  15. Overview of US fast-neutron facilities and testing capabilities

    International Nuclear Information System (INIS)

    Evans, E.A.; Cox, C.M.; Jackson, R.J.

    1982-01-01

    Rather than attempt a cataloging of the various fast neutron facilities developed and used in this country over the last 30 years, this paper will focus on those facilities which have been used to develop, proof test, and explore safety issues of fuels, materials and components for the breeder and fusion program. This survey paper will attempt to relate the evolution of facility capabilities with the evolution of development program which use the facilities. The work horse facilities for the breeder program are EBR-II, FFTF and TREAT. For the fusion program, RTNS-II and FMIT were selected

  16. Microstructural evolution of martensitic steels during fast neutron iradiation

    International Nuclear Information System (INIS)

    Maziasz, P.J.

    1989-01-01

    Irradiation of martensitic/ferritic steels with fast neutrons (E > 0.1 MeV) to displacement damage levels of 30--50 dpa at temperatures of 300--500 degree C produces significant changes in the as-tempered microstructure. Dislocation loops and networks can be produced, irradiation-induced precipitates can form, the lath/subgrain boundary structure and the thermal precipitates produced during tempering can become unstable, and if helium is present, bubbles and voids can form. These microstructural changes caused by irradiation can have important effects on the properties of this class of steels for both fast breeder reactor (FBR) and magnetic fusion reactor (MFR) applications. The purpose of this paper is to compare reactor-irradiated and long-term thermally aged 9Cr--1MoVNb specimens, in order to distinguish effects due to displacement damage from those caused by elevated-temperature exposure alone. 7 refs., 1 fig

  17. A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Cester, D., E-mail: davide.cester@gmail.com [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Lunardon, M.; Moretto, S. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Pino, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Sajo-Bohus, L. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Apartado 89000, 1080 A Caracas (Venezuela, Bolivarian Republic of); Stevanato, L.; Bonesso, I.; Turato, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2016-09-11

    A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

  18. A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

    International Nuclear Information System (INIS)

    Cester, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pino, F.; Sajo-Bohus, L.; Stevanato, L.; Bonesso, I.; Turato, F.

    2016-01-01

    A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

  19. Microstructural evolution in fast-neutron-irradiated austenitic stainless steels

    International Nuclear Information System (INIS)

    Stoller, R.E.

    1987-12-01

    The present work has focused on the specific problem of fast-neutron-induced radiation damage to austenitic stainless steels. These steels are used as structural materials in current fast fission reactors and are proposed for use in future fusion reactors. Two primary components of the radiation damage are atomic displacements (in units of displacements per atom, or dpa) and the generation of helium by nuclear transmutation reactions. The radiation environment can be characterized by the ratio of helium to displacement production, the so-called He/dpa ratio. Radiation damage is evidenced microscopically by a complex microstructural evolution and macroscopically by density changes and altered mechanical properties. The purpose of this work was to provide additional understanding about mechanisms that determine microstructural evolution in current fast reactor environments and to identify the sensitivity of this evolution to changes in the He/dpa ratio. This latter sensitivity is of interest because the He/dpa ratio in a fusion reactor first wall will be about 30 times that in fast reactor fuel cladding. The approach followed in the present work was to use a combination of theoretical and experimental analysis. The experimental component of the work primarily involved the examination by transmission electron microscopy of specimens of a model austenitic alloy that had been irradiated in the Oak Ridge Research Reactor. A major aspect of the theoretical work was the development of a comprehensive model of microstructural evolution. This included explicit models for the evolution of the major extended defects observed in neutron irradiated steels: cavities, Frank faulted loops and the dislocation network. 340 refs., 95 figs., 18 tabs

  20. Chemical methods for the use of niobium from pressure vessel cladding as a fast neutron dosimeter

    International Nuclear Information System (INIS)

    Karnani, Hari

    1986-08-01

    the steel samples from the cladding of a pressure vessel of an operating nuclear power reactor were obtained by scraping. The cladding material of the pressure vessel contained about 0.5 % niobium. It was desired to use the niobium as a dosimeter for estimating fast fluences at the pressure vessel. The weak radiation from the reaction product 93m Nb cannot be measured in the presence of other elements and interfering activities. A method was developed to separate niobium from other metals present; the concentration and yield of niobium were determined spectrophotometrically. The irradiated niobium was electrodeposited from aqueous solutions on copper discs. The amount of the deposited niobium was determined by a radiochemical method which makes use of its own radioactivity - measured with a liquid scintillation counter - and the known starting mass of niobium. It was possible to determine the deposited niobium masses (5 to 200 microgram) with a desired degree of accuracy. The absolute emission rate of X-rays could then be measured without any self-absorption or interference from other activities. The mass of niobium on each preparate and its X-ray emission rate, later on, were used as basic experimental data for the estimation of last neutron doses at the pressure vessel

  1. The response of dispersion-strengthened copper alloys to high fluence neutron irradiation at 415 degrees C

    International Nuclear Information System (INIS)

    Edwards, D.J.; Newkirk, J.W.; Garner, F.A.; Hamilton, M.L.; Nadkarni, A.; Samal, P.

    1993-01-01

    Various oxide-dispersion-strengthened copper alloys have been irradiated to 150 dpa at 415 degrees C in the Fast Flux Test Facility (FFTF). The Al 2 O 3 -strengthened GlidCop TM alloys, followed closely by a HfO 2 -strengthened alloy, displayed the best swelling resistance, electrical conductivity, and tensile properties. The conductivity of the HfO 2 -strengthened alloy reached a plateau at the higher levels of irradiation, instead of exhibiting the steady decrease in conductivity observed in the other alloys. A high initial oxygen content results in significantly higher swelling for a series of castable oxide-dispersion-strengthened alloys, while a Cr 2 O 3 -strengthened alloy showed poor resistance to radiation

  2. Fast neutron activation analysis using short-lived radionuclides

    International Nuclear Information System (INIS)

    Salma, I.; Zemplen-Papp, E.

    1993-01-01

    Fast neutron activation analysis experiments were performed to investigate the analytical possibilities and prospective utilization of short-lived activation products. A rapid pneumatic transfer system for use with neutron generators has been installed and applied for detecting radionuclides with a half-life from ∼300 ms to 20 s. The transport time for samples of total mass of 1-4 g is between 130 and 160 ms for pressurized air of 0.1-0.4 MPa. The reproducibility of transport times is less than 2%. The employed method of correcting time-dependent counting losses is based on the virtual pulse generator principle. The measuring equipment consists of CAMAC modules and a special gating circuit. Typical time distributions of counting losses are presented. The same 14 elements were studied by the conventional activation method (single irradiation and single counting) by both a typical pneumatic transport system (run time 3 s) and the fast pneumatic transport facility. Furthermore, the influence of the cyclic activation technique on the elemental sensitivities was investigated. (author) 15 refs.; 5 figs.; 3 tabs

  3. Some Applications of Fast Neutron Activation Analysis of Oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Owrang, Farshid

    2003-07-01

    In this thesis we focus on applications of neutron activation of oxygen for several purposes: A) measuring the water level in a laboratory tank, B) measuring the water flow in a pipe system set-up, C) analysing the oxygen in combustion products formed in a modern gasoline SI engine, and D) measuring on-line the amount of oxygen in bulk liquids. A) Water level measurements. The purpose of this work was to perform radiation based water level measurements, aimed at nuclear reactor vessels, on a laboratory scale. A laboratory water tank was irradiated by fast neutrons from a neutron generator. The water was activated at different water levels and the water level was decreased. The produced gamma radiation was measured using two detectors at different heights. The results showed that the method is suitable for measurement of water level and that a relatively small experimental set-up can be used for developing methods for water level measurements in real boiling water reactors based on activated oxygen in the water. B) Water flows in pipe. The goal in this work was to investigate the asymmetric distribution of activity in flow measurements with pulsed neutron activation (PNA) in a laboratory piping system. Earlier investigations had shown a discrepancy between the measured velocity of the activated water by PNA and the true mean velocity in the pipe. This discrepancy decreased with larger distances from the activation point. It was speculated that the induced activity in the pipe did not distribute homogeneously. With inhomogeneous radial distribution of activity in combination with a velocity profile in the pipe, the activated water may not have the same velocity as the mean velocity of water in the pipe. To study this phenomenon, a water-soluble colour was injected into a transparent pipe for simulation of the transport of the activated water. The radial concentration of the colour, at different distances from the activation point, was determined. The result

  4. Some Applications of Fast Neutron Activation Analysis of Oxygen

    International Nuclear Information System (INIS)

    Owrang, Farshid

    2003-01-01

    In this thesis we focus on applications of neutron activation of oxygen for several purposes: A) measuring the water level in a laboratory tank, B) measuring the water flow in a pipe system set-up, C) analysing the oxygen in combustion products formed in a modern gasoline SI engine, and D) measuring on-line the amount of oxygen in bulk liquids. A) Water level measurements. The purpose of this work was to perform radiation based water level measurements, aimed at nuclear reactor vessels, on a laboratory scale. A laboratory water tank was irradiated by fast neutrons from a neutron generator. The water was activated at different water levels and the water level was decreased. The produced gamma radiation was measured using two detectors at different heights. The results showed that the method is suitable for measurement of water level and that a relatively small experimental set-up can be used for developing methods for water level measurements in real boiling water reactors based on activated oxygen in the water. B) Water flows in pipe. The goal in this work was to investigate the asymmetric distribution of activity in flow measurements with pulsed neutron activation (PNA) in a laboratory piping system. Earlier investigations had shown a discrepancy between the measured velocity of the activated water by PNA and the true mean velocity in the pipe. This discrepancy decreased with larger distances from the activation point. It was speculated that the induced activity in the pipe did not distribute homogeneously. With inhomogeneous radial distribution of activity in combination with a velocity profile in the pipe, the activated water may not have the same velocity as the mean velocity of water in the pipe. To study this phenomenon, a water-soluble colour was injected into a transparent pipe for simulation of the transport of the activated water. The radial concentration of the colour, at different distances from the activation point, was determined. The result

  5. Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Abu Zayed Mohammad Saliqur, E-mail: zayed82000@yahoo.com [Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquanlu Shijingshan District, Beijing 100049 (China); Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long [Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquanlu Shijingshan District, Beijing 100049 (China); Xu, Qiu [Reactor Research Institute, Kyoto University 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Atobe, Kozo [Nuclear Safety Technology Center, 9-15, 1-chome, Utsubohonmachi, Nishi Ku, Osaka 550-0004 (Japan)

    2014-09-15

    Highlights: •Detection of Al monovacancy by positron lifetime spectroscopy in fast neutron-irradiated MgO·nAl{sub 2}O{sub 3}(n=2). •Concentration of defects is also estimated for Al monovacancy. •O atom peak was observed by using coincidence Doppler broadening spectroscopy. -- Abstract: The positron lifetimes of fast-neutron-irradiated MgO·nAl{sub 2}O{sub 3} single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10{sup −3} m{sub 0}c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies.

  6. Bubble masks for time-encoded imaging of fast neutrons.

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John T.; Sweany, Melinda; Throckmorton, Daniel J.

    2013-09-01

    Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is inducedtypically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gapsbubblespropagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.

  7. Dose Calibration of the ISS-RAD Fast Neutron Detector

    Science.gov (United States)

    Zeitlin, C.

    2015-01-01

    The ISS-RAD instrument has been fabricated by Southwest Research Institute and delivered to NASA for flight to the ISS in late 2015 or early 2016. ISS-RAD is essentially two instruments that share a common interface to ISS. The two instruments are the Charged Particle Detector (CPD), which is very similar to the MSL-RAD detector on Mars, and the Fast Neutron Detector (FND), which is a boron-loaded plastic scintillator with readout optimized for the 0.5 to 10 MeV energy range. As the FND is completely new, it has been necessary to develop methodology to allow it to be used to measure the neutron dose and dose equivalent. This talk will focus on the methods developed and their implementation using calibration data obtained in quasi-monoenergetic (QMN) neutron fields at the PTB facility in Braunschweig, Germany. The QMN data allow us to determine an approximate response function, from which we estimate dose and dose equivalent contributions per detected neutron as a function of the pulse height. We refer to these as the "pSv per count" curves for dose equivalent and the "pGy per count" curves for dose. The FND is required to provide a dose equivalent measurement with an accuracy of ?10% of the known value in a calibrated AmBe field. Four variants of the analysis method were developed, corresponding to two different approximations of the pSv per count curve, and two different implementations, one for real-time analysis onboard ISS and one for ground analysis. We will show that the preferred method, when applied in either real-time or ground analysis, yields good accuracy for the AmBe field. We find that the real-time algorithm is more susceptible to chance-coincidence background than is the algorithm used in ground analysis, so that the best estimates will come from the latter.

  8. Workshop on the next plan for the study of 'physics of fast neutron reactions and measurements'

    International Nuclear Information System (INIS)

    1985-03-01

    A work shop titled ''Physics of fast neutron reaction and measurements'' was held on 25 December 1984, where discussions were made on the new approach and techniques for neutron measurements. The possibilities of experimental tests with AVF cyclotron was also discussed. The followings are the list of papers presented at the work shop (all papers are written in Japanese except for the abstracts). (1) Monoenergetic neutron beam in Tohoku Cyclotron. (2) Spin-dependent response probed in (p,n) and (n,p) reactions. (3) Measurement of D(n,p) 2n reaction and instrumentation for (n,x) reactions in the 40 - 80 MeV region. (4) Two comments related to the neutron reaction. (5) High energy neutron production facilities in the world and a possibility of neutron induced reaction experiments at RCNP. (6) A neutron counter by detection of recoil protons with solid state detectors and development of neutron source by heavy ions. (7) The measurement of neutrons with the recoil detector. (8) Polarization transfer measurements (Py, Dss, Ds 1 , · · ·) with fast neutron beams. (9) Neutron elastic scattering. (10) Neutron capture gamma reaction and effective charge. (11) Comparison between neutron and charged particle induced reactions. (12) Study of giant resonances by fast neutrons. (Aoki, K.)

  9. A fast and flexible reactor physics model for simulating neutron spectra and depletion in fast reactors - 202

    International Nuclear Information System (INIS)

    Recktenwald, G.D.; Bronk, L.A.; Deinert, M.R.

    2010-01-01

    Determining the time dependent concentration of isotopes within a nuclear reactor core is central to the analysis of nuclear fuel cycles. We present a fast, flexible tool for determining the time dependent neutron spectrum within fast reactors. The code (VBUDS: visualization, burnup, depletion and spectra) uses a two region, multigroup collision probability model to simulate the energy dependent neutron flux and tracks the buildup and burnout of 24 actinides, as well as fission products. While originally developed for LWR simulations, the model is shown to produce fast reactor spectra that show high degree of fidelity to available fast reactor benchmarks. (authors)

  10. Fast neutron measurements with 7Li and 6Li enriched CLYC scintillators

    International Nuclear Information System (INIS)

    Giaz, A.; Blasi, N.; Boiano, C.; Brambilla, S.; Camera, F.; Cattadori, C.; Ceruti, S.; Gramegna, F.; Marchi, T.; Mattei, I.; Mentana, A.; Million, B.; Pellegri, L.; Rebai, M.; Riboldi, S.; Salamida, F.; Tardocchi, M.

    2016-01-01

    The recently developed Cs 2 LiYCl 6 :Ce (CLYC) crystals are interesting scintillation detectors not only for their gamma energy resolution (<5% at 662 keV) but also for their capability to identify and measure the energy of both gamma rays and fast/thermal neutrons. The thermal neutrons were detected by the 6 Li(n,α)t reaction while for the fast neutrons the 35 Cl(n,p) 35 S and 35 Cl(n,α) 32 P neutron-capture reactions were exploited. The energy of the outgoing proton or α particle scales linearly with the incident neutron energy. The kinetic energy of the fast neutrons can be measured using both the Time Of Flight (TOF) technique and using the CLYC energy signal. In this work, the response to monochromatic fast neutrons (1.9–3.8 MeV) of two CLYC 1″×1″ crystals was measured using both the TOF and the energy signal. The observables were combined to identify fast neutrons, to subtract the thermal neutron background and to identify different fast neutron-capture reactions on 35 Cl, in other words to understand if the detected particle is an α or a proton. We performed a dedicated measurement at the CN accelerator facility of the INFN Legnaro National Laboratories (Italy), where the fast neutrons were produced by impinging a proton beam (4.5, 5.0 and 5.5 MeV) on a 7 LiF target. We tested a CLYC detector 6 Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector 7 Li-enriched at more than 99%, which is suitable for fast neutron measurements.

  11. Assessment of fast and thermal neutron ambient dose equivalents around the KFUPM neutron source storage area using nuclear track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fazal-ur-Rehman [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: fazalr@kfupm.edu.sa; Al-Jarallah, M.I. [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Abu-Jarad, F. [Radiation Protection Unit, Environmental Protection Department, Saudi Aramco, P. O. Box 13027, Dhahran 31311 (Saudi Arabia); Qureshi, M.A. [Center for Applied Physical Sciences, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2005-11-15

    A set of five {sup 241}Am-Be neutron sources are utilized in research and teaching at King Fahd University of Petroleum and Minerals (KFUPM). Three of these sources have an activity of 16Ci each and the other two are of 5Ci each. A well-shielded storage area was designed for these sources. The aim of the study is to check the effectiveness of shielding of the KFUPM neutron source storage area. Poly allyl diglycol carbonate (PADC) Nuclear track detectors (NTDs) based fast and thermal neutron area passive dosimeters have been utilized side by side for 33 days to assess accumulated low ambient dose equivalents of fast and thermal neutrons at 30 different locations around the source storage area and adjacent rooms. Fast neutron measurements have been carried out using bare NTDs, which register fast neutrons through recoils of protons, in the detector material. NTDs were mounted with lithium tetra borate (Li{sub 2}B{sub 4}O{sub 7}) converters on their surfaces for thermal neutron detection via B10(n,{alpha})Li6 and Li6(n,{alpha})H3 nuclear reactions. The calibration factors of NTD both for fast and thermal neutron area passive dosimeters were determined using thermoluminescent dosimeters (TLD) with and without a polyethylene moderator. The calibration factors for fast and thermal neutron area passive dosimeters were found to be 1.33 proton tracks cm{sup -2}{mu}Sv{sup -1} and 31.5 alpha tracks cm{sup -2}{mu}Sv{sup -1}, respectively. The results show variations of accumulated dose with the locations around the storage area. The fast neutron dose equivalents rates varied from as low as 182nSvh{sup -1} up to 10.4{mu}Svh{sup -1} whereas those for thermal neutron ranged from as low as 7nSvh{sup -1} up to 9.3{mu}Svh{sup -1}. The study indicates that the area passive neutron dosimeter was able to detect dose rates as low as 7 and 182nSvh{sup -1} from accumulated dose for thermal and fast neutrons, respectively, which were not possible to detect with the available active neutron

  12. Fast neutron dosimetry in research reactors; Dosimetrie en neutrons rapides dans les reacteurs de recherche

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    This work chiefly concerns the measurement of fast neutron fluxes by means of threshold detectors. It is shown first that the cross sections to use for measurements by threshold detectors depend largely on the neutron spectrum, that is the position in which the measurement is performed. The spectrum is determined by calculation for several positions in the piles EL2 and EL3; from this can be deduced the cross-sections to be used for the measurements carried out in these positions. In the last part of the report, possible methods for the experimental determination of the spectrum are indicated. (author) [French] On etudie principalement la mesure des flux de neutrons rapides a l'aide de detecteurs a seuil. On montre d'abord que les sections efficaces a utiliser pour les mesures par detecteurs a seuil, dependent grandement du spectre des neutrons, c'est-a-dire de l'emplacement ou s'effectue la mesure. La determination du spectre est effectuee par le calcul pour plusieurs emplacements des piles EL2 et EL3; on en deduit les sections efficaces a utiliser pour les mesures effectuees a ces emplacements. Dans la derniere partie du rapport, on indique quelles methodes sont possibles pour la determination experimentale du spectre. (auteur)

  13. Neutron transport. Physics and calculation of nuclear reactors with applications to pressurized water reactors and fast neutron reactors. 2 ed.

    International Nuclear Information System (INIS)

    Bussac, J.; Reuss, P.

    1985-01-01

    This book presents the main physical bases of neutron theory and nuclear reactor calculation. 1) Interactions of neutrons with matter and basic principles of neutron transport; 2) Neutron transport in homogeneous medium and the neutron field: kinetic behaviour, slowing-down, resonance absorption, diffusion equation, processing methods; 3) Theory of a reactor constituted with homogeneous zones: critical condition, kinetics, separation of variables, calculation and neutron balance of the fundamental mode, one-group and multigroup theories; 4) Study of heterogeneous cell lattices: fast fission factor, resonance absorption, thermal output factor, diffusion coefficient, computer codes; 5) Operation and control of reactors: perturbation theory, reactivity, fuel properties evolution, poisoning by fission products, calculation of a reactor and fuel management; 6) Study of some types of reactors: PWR and fast breeder reactors, the main reactor types of the present French program [fr

  14. Integral test of JENDL dosimetry file using fast neutron field in the Experimental Fast Reactor JOYO

    International Nuclear Information System (INIS)

    Aoyama, Takafumi; Sekine, Takashi

    1999-09-01

    In order to evaluate the applicability of the JENDL dosimetry file, an integral test using a fast neutron spectrum field in the Experimental Fast Reactor JOYO Mark-II core was performed. The dosimeter set consisting of eight reactions of 46 Ti(n,p) 46 Sc, 54 Fe(n,p) 54 Mn, 58 Fe(n,γ) 59 Fe, 58 Ni(n,p) 58 Co, 59 Co(n,γ) 60 Co, 63 Cu(n,α) 60 Co, 238 U fission and 237 Np fission was irradiated for approximately 30 days near the core center of the JOYO Mk-II. Neutron flux at the dosimeter position was calculated using the two dimensional discrete ordinate transport code 'DORT'. The core configuration was modeled in XY geometry, and the 100 group cross section set of JSD-J2 / JFT-J2, which was processed from JENDL-2, was utilized. The absolute value of neutron flux was normalized so that the 235 U fission rate using the calculated neutron spectrum agreed with the measured reaction rate. The 103 group cross section data were processed by 'NJOY' code for nuclides to be used in the JOYO dosimetry. As the results of integral test for JENDL/D-99 (new file) and JENDL/D-91 (previous file), calculated values by JENDL/D-99 agreed well with the experimental values, and the C/E ratios ranged from 0.95 to 1.22. By comparing the results between JENDL/D-99 and JENDL/D-91, small differences exist, except for 58 Fe(n, γ) 59 Fe reaction, which was improved significantly in JENDL/D-99. (author)

  15. How resilient is the soybean genome? Insights from fast neutron mutagenesis

    Science.gov (United States)

    Previously, we described the development of a fast neutron mutant population resource in soybean and identified mutations of interest through phenotypic screening. Here, we consider the resiliency of the soybean genome by examining genomic rearrangements and mutations that arise from fast neutron ra...

  16. Neutron and gamma ray streaming experiments at the fast neutron source reactor 'YAYOI'

    International Nuclear Information System (INIS)

    Oka, Yoshiaki; Yanagisawa, Ichiro; Akiyama, Masatsugu; An, Shigehiro

    1979-07-01

    Neutron and gamma ray streaming experiments were performed in the ducts and cavities that were located in the heavy concrete shields of the fast neutron source reactor YAYOI of University of Tokyo. The configurations have the feature that the streaming through the ducts are occurred following the scattering in the cavity. The axes of the ducts are perpendicular to the source radiation from the core. The spectrum of the source was modified by putting a plug in the beam hole of the core. An aluminum plug and the plug which contains paraffin were used. The decay in the ducts, however, hardly depends on the source spectrum. The decay in the ducts is nearly exponential. (author)

  17. Bulk moisture determination in building materials by fast neutron/gamma technique

    International Nuclear Information System (INIS)

    Padron Diaz, I.; Felipe Desdin, L.; Martin Hernandez, G.; Shtejer, K.; Perez Tamayo, N.; Ceballos, C.; Lemus, O.

    1998-01-01

    Fast Neutron/Gamma Transmission technique has been improved to allow to measure moisture content in building materials. In order to improve fast neutron/gamma discrimination in the transmission system employing the NE-213 scintillation detector a pulse shape discrimination system was constructed at the CEADEN. A separate neutron/gamma detection approach was used with neutron transmission measurement using an Am-Be neutron source and a BF 3 detector and gamma transmission measurement using a collimated 137 Cs source and a NaI scintillator

  18. Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source

    International Nuclear Information System (INIS)

    Tarifeño-Saldivia, Ariel; Soto, Leopoldo

    2014-01-01

    This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode. (paper)

  19. Detection of fast neutrons in a plastic scintillator using digital pulse processing to reject gammas

    International Nuclear Information System (INIS)

    Reeder, P.L.; Peurrung, A.J.; Hansen, R.R.; Stromswold, D.C.; Hensley, W.K.; Hubbard, C.W.

    1999-01-01

    We report on neutron-gamma discrimination in a plastic scintillator based on the time delay inherent in second and third chance neutron scattering. Because of the time delay (∼3 ns) between the first and second scattering of a neutron, calculations of gammas and neutrons in a plastic scintillator predict that a neutron signal should be significantly broader than a pulse from a gamma event. Experimentally, we have used a fast digital oscilloscope coupled to a computer to examine individual pulses from neutron or gamma induced signals in fast scintillators coupled to a fast PMT. Individual neutron-induced signals were consistent with the predictions of our model, but gamma pulses were broader than expected. We present various tests to understand this phenomenon and discuss a way to overcome this problem

  20. Indium antimonide crystal defects formed by fast neutron irradiation

    International Nuclear Information System (INIS)

    Vitovskij, N.A.; Dolgolenko, A.P.; Mashovets, T.V.; Oganesyan, O.V.

    1979-01-01

    It is shown, that indium antimonide irradiation with fast neutrons of reactor results in the formation of disorded regions with a mean radius of approximately 130 A surrounded with space charge regions forming barriers for main carriers. But the found values of defect cluster depolarization coefficient (Lsub(x)sup(n)=0.18 and Lsub(x)sup(p)=0.29) show, that the clusters have marked conductivity for main charge carriers. The found position of the Fermi level in the disorded regions Esub(F)=Esub(c)-0.085 eV does not depend on the impurity type and its concentration in an initial material. The disorded regions play the main part in charge carrier scattering at low temperatures and markedly contribute to the change of mobility at 80 K. It is found, that irradiation temperature change in the range from 77 to 300 K does not effect practically on the disorded region parameters