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Title: The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

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 due to 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 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 five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’smore » (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.« less

Authors:
 [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1346681
Report Number(s):
ORNL/TM-2017/57
DN4001030; MDGA517
DOE Contract Number:
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

McElroy, Robert Dennis, and Cleveland, Steven L. The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter. United States: N. p., 2017. Web. doi:10.2172/1346681.
McElroy, Robert Dennis, & Cleveland, Steven L. The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter. United States. doi:10.2172/1346681.
McElroy, Robert Dennis, and Cleveland, Steven L. Wed . "The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter". United States. doi:10.2172/1346681. https://www.osti.gov/servlets/purl/1346681.
@article{osti_1346681,
title = {The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter},
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 due to 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 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 five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.},
doi = {10.2172/1346681},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}

Technical Report:

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  • This report summarizes and evaluates field tests of the Active Well Coincidence Counter (AWCC) at Winfrith and Dounreay, United Kingdom. The applicability of the AWCC for assaying the uranium content of a wide variety of materials was demonstrated and calibration curves were generated. The AWCC was used in three modes (fast, thermal, and passive) while assaying powders, pellets, cartridges, plates, assorted residues, and materials-testing-reactor fuel assemblies.
  • An Active Well Coincidence Counter (AWCC) and a portable shift register (PSR-B) produced by Aquila Technologies Group, Inc., have been tested and cross-calibrated with existing AWCCs used by the International Atomic Energy Agency (IAEA). This report summarizes the results of these tests and the cross-calibration of the detector. In addition, updated tables summarizing the cross-calibration of existing AWCCs and AmLi sources are also included. Using the Aquila PSR-B with existing IAEA software requires secondary software also supplied by Aquila to set up the PSR-B with the appropriate measurement parameters.
  • Highly enriched uranium-containing graphite-based material from the Los Alamos National Laboratory (LANL) is currently stored at the Idaho National Engineering and Environmental Laboratory (INEEL). Measurements to verify the uranium content of these samples are required prior to their disposition to the Y-12 facility in Tennessee. The stored materials vary significantly in their matrix purity and in their {sup 235}U content and enrichment. A set of 26 samples selected from the LANL material inventory were analyzed non-destructively using an Active Well Coincidence Counter (AWCC) calibrated versus pure UO{sub 3} standards. A correction, calculated from published data and the approximate carbon-to-uranium atommore » ratios of each sample, was applied for the response enhancement from the carbon matrix. In some cases this correction was as high as 30%. Eight of the 26 sample that had been analyzed in the AWCC were destructively analyzed to provide a benchmark for the non-destructive analyses. The average recovery (NDA/Destructive results) was 0.997 {+-} 0.115. One sample had a destructive result that lay outside a 3-sigma interval about the NDA result.« less
  • This study emphasized the Active Well Coincidence Counter (AWCC) capabilities for the U3O8 powder samples, which ranged up to 12 Kg in mass and 93 percent in 235U enrichment.