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Title: The DD Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Uranium Neutron Coincidence Collar

Abstract

The 235U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques because of the limited penetration of the item by the characteristic 235U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Coincidence Collar (UNCL), and 252Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., 252Cf or Am(Li)] to achieve better measurement accuracies than are possible using gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The 252Cf shuffler systems rely on the use of high-output 252Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every 5–7 years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. Previously we examined the performance of Oak Ridge National Laboratory’s Large Volumemore » Active Well Coincidence Counter modified to accept a commercially available deuterium-deuterium (DD) neutron generator to examine the potential of the DD neutron generator as an alternative to the isotopic sources [1]. That work indicated that the DD generator was a viable replacement for the AWCC applications, but because of the large dimensions of that generator, the DD/AWCC would have to be run as a delayed neutron counting system to provide equivalent measurement precision. In this work we examine the performance of a standard UNCL modified to accept the DD neutron generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium and highly enriched uranium items. The projected performance of the modified UNCL for fresh pressurized water reactor fuel assemblies operated in both traditional coincidence counting and delayed neutron counting modes is presented.« less

Authors:
 [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
OSTI Identifier:
1427636
Report Number(s):
ORNL/TM-2017/736
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; 07 ISOTOPE AND RADIATION SOURCES

Citation Formats

McElroy, Robert Dennis, and Cleveland, Steven L. The DD Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Uranium Neutron Coincidence Collar. United States: N. p., 2017. Web. doi:10.2172/1427636.
McElroy, Robert Dennis, & Cleveland, Steven L. The DD Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Uranium Neutron Coincidence Collar. United States. https://doi.org/10.2172/1427636
McElroy, Robert Dennis, and Cleveland, Steven L. 2017. "The DD Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Uranium Neutron Coincidence Collar". United States. https://doi.org/10.2172/1427636. https://www.osti.gov/servlets/purl/1427636.
@article{osti_1427636,
title = {The DD Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Uranium Neutron Coincidence Collar},
author = {McElroy, Robert Dennis and Cleveland, Steven L.},
abstractNote = {The 235U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques because of the limited penetration of the item by the characteristic 235U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Coincidence Collar (UNCL), and 252Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., 252Cf or Am(Li)] to achieve better measurement accuracies than are possible using gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The 252Cf shuffler systems rely on the use of high-output 252Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every 5–7 years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. Previously we examined the performance of Oak Ridge National Laboratory’s Large Volume Active Well Coincidence Counter modified to accept a commercially available deuterium-deuterium (DD) neutron generator to examine the potential of the DD neutron generator as an alternative to the isotopic sources [1]. That work indicated that the DD generator was a viable replacement for the AWCC applications, but because of the large dimensions of that generator, the DD/AWCC would have to be run as a delayed neutron counting system to provide equivalent measurement precision. In this work we examine the performance of a standard UNCL modified to accept the DD neutron generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium and highly enriched uranium items. The projected performance of the modified UNCL for fresh pressurized water reactor fuel assemblies operated in both traditional coincidence counting and delayed neutron counting modes is presented.},
doi = {10.2172/1427636},
url = {https://www.osti.gov/biblio/1427636}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 01 00:00:00 EST 2017},
month = {Fri Dec 01 00:00:00 EST 2017}
}