Determining the Optimal Radiation Detector Configuration for Measuring Fuel Characteristics of an Accountability Tank within a PUREX Facility

Aqueous reprocessing facilities face unique safeguard challenges due to their continuous operation, high-throughput, high radiation fields, and highly corrosive environments. This paper seeks to explore the radiation signatures present in a 200 tHM/year sample PUREX facility. An MCNP model was constructed of the Input Accountability Tank (IAT) inside of a concrete shielded hot cell. The source term was generated using the Separations and Safeguards Performance Model (SSPM). This data was used to inform the type and placement of radiation detectors as well as the collimation and shielding required to obtain and verify fuel characteristics such as burn up, initial enrichment, and cooling time. A high purity germanium detector and a 1 cm diameter cylindrical collimator through the hot cell wall produced count rates on the order of 10^5 cps. Two Y-88 gamma peaks were consistently observed as was a correlation between the fuel burnup and the count rates in these two peaks. This work is part of a larger study at UC Berkeley to study material holdup in bulk handling facilities to ultimately inform future facilities and improve nuclear material accountancy methods.