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Title: Neutron and photon transport in seagoing cargo containers

Abstract

Factors affecting sensing of small quantities of fissionable material in large seagoing cargo containers by neutron interrogation and detection of {beta}-delayed photons are explored. The propagation of variable-energy neutrons in cargos, subsequent fission of hidden nuclear material and production of the {beta}-delayed photons, and the propagation of these photons to an external detector are considered explicitly. Detailed results of Monte Carlo simulations of these stages in representative cargos are presented. Analytical models are developed both as a basis for a quantitative understanding of the interrogation process and as a tool to allow ready extrapolation of our results to cases not specifically considered here.

Authors:
; ; ; ;  [1];  [2]
  1. Lawrence Livermore National Laboratory, N-Division, 7000 East Avenue, Livermore, California 94550 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20713932
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 97; Journal Issue: 9; Other Information: DOI: 10.1063/1.1887835; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; CARGO; COMPUTERIZED SIMULATION; CONTAINERS; EXTRAPOLATION; FISSION; FISSIONABLE MATERIALS; MARITIME TRANSPORT; MONTE CARLO METHOD; NEUTRON DETECTION; NEUTRON TRANSPORT; NEUTRON TRANSPORT THEORY; NUCLEAR FUELS; PHOTON TRANSPORT; REACTOR FUELING; SECURITY

Citation Formats

Pruet, J., Descalle, M.-A., Hall, J., Pohl, B., Prussin, S.G., and Department of Nuclear Engineering, University of California at Berkeley. Neutron and photon transport in seagoing cargo containers. United States: N. p., 2005. Web. doi:10.1063/1.1887835.
Pruet, J., Descalle, M.-A., Hall, J., Pohl, B., Prussin, S.G., & Department of Nuclear Engineering, University of California at Berkeley. Neutron and photon transport in seagoing cargo containers. United States. doi:10.1063/1.1887835.
Pruet, J., Descalle, M.-A., Hall, J., Pohl, B., Prussin, S.G., and Department of Nuclear Engineering, University of California at Berkeley. 2005. "Neutron and photon transport in seagoing cargo containers". United States. doi:10.1063/1.1887835.
@article{osti_20713932,
title = {Neutron and photon transport in seagoing cargo containers},
author = {Pruet, J. and Descalle, M.-A. and Hall, J. and Pohl, B. and Prussin, S.G. and Department of Nuclear Engineering, University of California at Berkeley},
abstractNote = {Factors affecting sensing of small quantities of fissionable material in large seagoing cargo containers by neutron interrogation and detection of {beta}-delayed photons are explored. The propagation of variable-energy neutrons in cargos, subsequent fission of hidden nuclear material and production of the {beta}-delayed photons, and the propagation of these photons to an external detector are considered explicitly. Detailed results of Monte Carlo simulations of these stages in representative cargos are presented. Analytical models are developed both as a basis for a quantitative understanding of the interrogation process and as a tool to allow ready extrapolation of our results to cases not specifically considered here.},
doi = {10.1063/1.1887835},
journal = {Journal of Applied Physics},
number = 9,
volume = 97,
place = {United States},
year = 2005,
month = 5
}
  • Factors affecting sensing of small quantities of fissionable material in large sea-going cargo containers by neutron interrogation and detection of {beta}-delayed photons are explored. The propagation of variable-energy neutrons in cargos, subsequent fission of hidden nuclear material and production of the {beta}-delayed photons, and the propagation of these photons to an external detector are considered explicitly. Detailed results of Monte Carlo simulations of these stages in representative cargos are presented. Analytical models are developed both as a basis for a quantitative understanding of the interrogation process and as a tool to allow ready extrapolation of the results to cases notmore » specifically considered here.« less
  • Monte Carlo simulations of a pixelated detector array of inorganic scintillators for high spatial resolution imaging of 1-9 MeV photons are presented. The results suggest that a detector array of 0.5 cm x 0.5 cm x 5 cm pixels of bismuth germanate may provide sufficient efficiency and spatial resolution to permit imaging of an object with uncertainties in dimension of several mm. The cross talk between pixels is found to be in the range of a few percent when pixels are shielded by {approx} 1mm of lead or tungsten. The contrast at the edge of an object is greatly improvedmore » by rejection of events depositing less than {approx} 1 MeV. Given the relatively short decay time of BGO, the simulations suggest that such a detector may prove adequate for the purpose of rapid scanning of highly-shielded cargos for possible presence of high atomic number (including clandestine fissionable) materials when used with low current high duty factor x-ray sources.« less
  • Nowadays in Russia and abroad there are several groups of scientists, engaged in development of systems based on 'tagged' neutron method (API method) and intended for detection of dangerous materials, including high explosives (HE). Particular attention is paid to possibility of detection of dangerous objects inside a sea cargo container. Energy gamma-spectrum, registered from object under inspection is used for determination of oxygen/carbon and nitrogen/carbon chemical ratios, according to which dangerous object is distinguished from not dangerous one. Material of filled container, however, gives rise to additional effects of rescattering and moderation of 14 MeV primary neutrons of generator, attenuationmore » of secondary gamma-radiation from reactions of inelastic neutron scattering on objects under inspection. These effects lead to distortion of energy gamma-response from examined object and therefore prevent correct recognition of chemical ratios. These difficulties are taken into account in analytical method, presented in the paper. Method has been validated against experimental data, obtained by the system for HE detection in sea cargo, based on API method and developed in VNIIA. Influence of shielding materials on results of HE detection and identification is considered. Wood and iron were used as shielding materials. Results of method application for analysis of experimental data on HE simulator measurement (tetryl, trotyl, hexogen) are presented.« less