This paper illustrates potential safeguards benefits that process monitoring (PM) may have as a diversiondeterrent and as a complementary safeguards measure to nuclear material accountancy (NMA). Thisbenefit is illustrated by quantifying the standard deviation associated with detecting a considered materialdiversion scenario using either an NMA-based method or a PM-based approach. To illustrate the benefitsof PM for effective safeguards, we consider a reprocessing facility. We assume that the diversion ofinterest for detection manifests itself as a loss of Pu caused by abnormally operating a dissolver for anextended period to accomplish protracted diversion (or misdirection) of Pu to a retained (unconditioned)waste stream. For detecting the occurrence of this diversion (which involves anomalous operation of thedissolver), we consider two different data evaluation and integration (DEI) approaches, one based onNMA and the other based on PM. The approach based on PM does not directly do mass balancecalculations, but rather monitors for the possible occurrence of anomaly patterns related to potential lossof nuclear material. It is thus assumed that the loss of a given mass amount of nuclear material can bedirectly associated with the execution of proliferation-driven activities that trigger the occurrence of ananomaly pattern consisting of series of events or signatures occurring at different unit operations and timeinstances. By effectively assessing these events over time and space, the PM-based DEI approach tries toinfer whether this specific pattern of events has occurred and how many times within a given time period.To evaluate the goodness of PM, the 3 Sigma of the estimated mass loss is computed under both DEIapproaches as function of the number of input batches processed. Simulation results are discussed.
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