Progress on the Development of Spent Nuclear Fuel Dissolver Models for Accurate Process Monitoring Safeguards

Process monitoring offers a path forward in reducing the safeguards’ error propagation in a large commercial reprocessing facility without sacrificing throughput. High precision measurements of simple parameters like process temperature – backed by an accurate model – provide ideal process monitoring conditions. Work is underway at Argonne National Laboratory to demonstrate the feasibility of process monitoring in reprocessing spent fuel by dissolution in nitric acid. A suitable model was adopted to determine the expected performance of the dissolver for a given initial temperature and nitric acid concentration ranging from 351-370 K and 4.46-6.06 M, respectively. Adjusting these parameters using the adopted model help determine the threshold levels that cannot be exceeded by the operator in order to maintain optimization and appropriate safeguards. Literature research has produced several other models to serve as the baseline metric, and the research also underscores the complexity of understanding all of the factors involved in spent fuel dissolution. Integrating additional factors into the adopted model is the basis for continuing work in this area.