Roles for process monitoring in nuclear safeguards at aqueous reprocessing plants

Process monitoring (PM) is increasingly important in nuclear safeguards as a supplement to mass-balance based nuclear ma-terials accounting (NMA). The main goal for using PM in addi-tion to NMA is to improve the ability to detect off-normal plant operation, which could indicate intent to divert special nuclear material. With this main goal in mind, programs within the U.S. Department of Energy and the National Nuclear Security Ad-ministration aim to advance the use of PM. This paper reviews traditional PM roles, describes possible new roles, and then illustrates new PM roles using two diversion scenarios. Particular focus is on safeguards at aqueous reprocessing plants where in the particular case of solution monitoring, PM tracks frequent measurements of bulk solution mass and volume.