Effects of Salt Cleanup Failure Modes on the Electrorefiner in a Signature Based Safeguards (SBS) Framework

Traditional International Atomic Energy Agency (IAEA) safeguards are based on nuclear material accountancy (NMA) and detection of the loss of a significant quantity of fissile material. For large throughput nuclear facilities, such as commercial reprocessing plants, it is difficult to satisfy the IAEA safeguards accountancy goal for detection of diversion. Several publications have demonstrated the safeguards benefit from using process monitoring (PM) on nuclear facilities as a complementary safeguards measure to NMA. More recently, this concept has been expanded and preliminarily demonstrated for pyroprocessing technology and has been termed Signature Based Safeguards (SBS). It 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 difference (SEID). This paper applies the SBS methodology to the electrorefiner (ER) unit operation and assesses a failure mode involving long term operation of the ER with no or incomplete salt cleanup. This is of safeguards significance because real time or near real time detection of this anomaly can help resolve mass balance inconsistencies further down the process. Following the SBS methodology, this study describes the operational conditions that would cause the salt concentration to change, it simulates the off normal processing to generate sensor output using electrochemical techniques coupled with traditional NMA methods, such as the Pu to Cm ratio technique, and finally this paper provides an analysis of those signatures to determine their safeguards significance.