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Title: Monte Carlo Evaluation of the Improvements in Nuclear Materials Identification System (NMIS) Resulting From a DT Neutron Generator

Abstract

Nuclear safeguards active measurements that rely on the time correlation between fast neutrons and gamma rays from the same fission are a promising technique. Previous studies have shown the feasibility of this method, in conjunction with the use of artificial neural networks, to estimate the mass and enrichment of fissile samples enclosed in special, sealed containers. This paper evaluates the use of the associated particle sealed tube neutron generator (APSTNG) as the interrogation source in correlation measurements. The results show that its use is of particular importance when floor reflections are present. The Nuclear Materials Identification System (NMIS) presently uses {sup 252}Cf ionization chambers as interrogation sources for the time-dependent coincidence measurements. Because triggers from this source are associated with neutrons emitted in any direction, adjacent materials such as the floor and nearby containers could affect the measurements and should be accounted for. Conversely, the APSTNG, together with an alpha particle detector, defines a cone of neutrons that can be aimed at the item under verification, thus removing the effects of nearby materials from the time-dependent coincidence distributions. Monte Carlo calculations were performed using MCNP-POLIMI, a modified version of the standard MCNP code. The code attempts to calculate more correctlymore » quantities that depend on the second moment of the neutron and gamma distributions. The simulations quantified the sensitivity enhancements and removal of the effects of nearby materials by substituting the traditional {sup 252}Cf source with the APSTNG.« less

Authors:
;
Publication Date:
Research Org.:
Oak Ridge Y-12 Plant (Y-12), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Defense Programs (DP) (US)
OSTI Identifier:
799751
Report Number(s):
Y/LB-16,126
TRN: US0203778
DOE Contract Number:  
AC05-00OR22800
Resource Type:
Conference
Resource Relation:
Conference: Institute of Nuclear Materials Management Conference, Orlando, FL (US), 06/23/2002--06/27/2002; Other Information: PBD: 16 May 2002
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; ALPHA PARTICLES; EVALUATION; FAST NEUTRONS; IDENTIFICATION SYSTEMS; IONIZATION CHAMBERS; NEURAL NETWORKS; NEUTRON GENERATORS; NEUTRONS; NUCLEAR MATERIALS MANAGEMENT

Citation Formats

Pozzi, S A, and Mihalczo, J T. Monte Carlo Evaluation of the Improvements in Nuclear Materials Identification System (NMIS) Resulting From a DT Neutron Generator. United States: N. p., 2002. Web.
Pozzi, S A, & Mihalczo, J T. Monte Carlo Evaluation of the Improvements in Nuclear Materials Identification System (NMIS) Resulting From a DT Neutron Generator. United States.
Pozzi, S A, and Mihalczo, J T. 2002. "Monte Carlo Evaluation of the Improvements in Nuclear Materials Identification System (NMIS) Resulting From a DT Neutron Generator". United States. https://www.osti.gov/servlets/purl/799751.
@article{osti_799751,
title = {Monte Carlo Evaluation of the Improvements in Nuclear Materials Identification System (NMIS) Resulting From a DT Neutron Generator},
author = {Pozzi, S A and Mihalczo, J T},
abstractNote = {Nuclear safeguards active measurements that rely on the time correlation between fast neutrons and gamma rays from the same fission are a promising technique. Previous studies have shown the feasibility of this method, in conjunction with the use of artificial neural networks, to estimate the mass and enrichment of fissile samples enclosed in special, sealed containers. This paper evaluates the use of the associated particle sealed tube neutron generator (APSTNG) as the interrogation source in correlation measurements. The results show that its use is of particular importance when floor reflections are present. The Nuclear Materials Identification System (NMIS) presently uses {sup 252}Cf ionization chambers as interrogation sources for the time-dependent coincidence measurements. Because triggers from this source are associated with neutrons emitted in any direction, adjacent materials such as the floor and nearby containers could affect the measurements and should be accounted for. Conversely, the APSTNG, together with an alpha particle detector, defines a cone of neutrons that can be aimed at the item under verification, thus removing the effects of nearby materials from the time-dependent coincidence distributions. Monte Carlo calculations were performed using MCNP-POLIMI, a modified version of the standard MCNP code. The code attempts to calculate more correctly quantities that depend on the second moment of the neutron and gamma distributions. The simulations quantified the sensitivity enhancements and removal of the effects of nearby materials by substituting the traditional {sup 252}Cf source with the APSTNG.},
doi = {},
url = {https://www.osti.gov/biblio/799751}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu May 16 00:00:00 EDT 2002},
month = {Thu May 16 00:00:00 EDT 2002}
}

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