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Title: Report on Concepts & Approaches for SSBD for eCHEM

The verification of special nuclear material (SNM) in spent fuel pyroprocessing is an important safeguards challenge. The detection of spontaneous fission (SF) neutrons from curium is an accepted, non-destructive technique that has been applied to verify special nuclear material (SNM) content in used fuel and other materials in the fuel cycle. The nuclear material accounting (NMA) technique at the Korea Atomic Energy Research Institute’s Reference Engineering-scale Pyroprocessing Facility (REPF) is based on the Cm balance technique[1]. The 244Cm isotope is used as a Pu indicator because it is the dominant source of SF neutrons in the used fuel. The plutonium content in spent fuel can be obtained by multiplying the doubles (D) or singles (S) neutron count of spent fuel by the Pu/Cm ratio. Using D’s is preferred to avoid the effect of neutrons produced from the ( ,n) reactions; however in metal samples, ( ,n) neutrons should be negligible. The Pu/Cm ratio can be determined by destructive analysis (DA) of small samples taken from the feed materials, the electrolyte, or the cathode deposit. Although DA is accurate, it is a more expensive and timely technique, but it is used to verify the results of nondestructive analysis (NDA) that wouldmore » be done more frequently and easily[2]. This neutron counting technique can only be applied when curium and plutonium are not separated in the system and under normal operating conditions transuranics (TRU) are not separated in the pyroprocessing facility. The electrorefiner (ER) poses particular safeguards concerns and should be closely monitored using real time or near real time analysis (NRTA). While Pu and Cm exhibit similar electrochemical behavior [3, 4], previous studies have shown that certain off-normal operating conditions in the ER may lead to the co-deposition of Pu on the cathode causing it to separate from the other TRUs[5, 6, 7]. Several publications have demonstrated the safeguards benefit from using process monitoring (PM) on nuclear facilities as a complementary measure to NMA[8, 9, 10, 11]. More recently, this concept was expanded and preliminarily demonstrated for pyroprocessing. The concept of Signature Based Safeguards (SBS) is part of this expansion and is built around the interpretation of input from various sensors in a declared facility coupled with complementary NMA methods to increase confidence and lower standard error inventory differences (SEID)[12, 13, 6]. The SBS methodology was conceptually developed and relies on NRTA of process monitoring data to detect material diversion complimented by robust containment and surveillance (C/S) measures. This work demonstrates one example of how the SBS framework can be used in the ER. In this SBS application, a combination of cyclic voltammetry (CV) and neutron counting is applied to track and monitor Pu mass balance.« less
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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Resource Type:
Technical Report
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States