(250c) Experimental Analysis of Plutonium Product and Raffinate Streams from Multiple Purex Process on a Low Burn-up, Fast Neutron Irradiated DUO2 Pellet

Experimental investigations of separating actinides (uranium and plutonium) from fission products (FPs) were conducted using modified Plutonium Uranium Recovery by Extraction (PUREX) process. The samples under investigation were from a low burn-up (< 5 GWd/tU), depleted uranium dioxide (DUO₂) pellet (~13 milligrams) irradiated in a fast neutron spectrum in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). This sample simulated the DUO₂ blanket region of a Fast Breeder Reactor (FBR) which was removed at low burn-up for weapons-grade plutonium (WGPu) recovery. The potential to misuse the material generated in this type of reactor prompts interest in a detailed analysis of the FPs present in the separated plutonium product and raffinate streams. A detailed understanding of these unique compositions would aid nuclear forensics activities for source attribution in the case of smuggled plutonium interdiction or at an inspection of a reprocessing plant to catch the misuse of such a plant.
Aliquots of the dissolved neutron irradiated DUO₂ sample containing FPs and WGPu, underwent three modified bench-top scale PUREX processes. Each process had its own specific goal; maximize Pu recovery; minimize FP contamination in the product Pu; and characterize Pu decontamination factor (DF) values for a single stage extraction and back-extraction. Through these processes each step was analyzed via high-resolution gamma spectroscopy or ICP-MS. Distribution ratios and DF values were calculated for nuclides of interest to be incorporated into a larger nuclear forensics database. The reported experiments were performed in an argon atmosphere glove box, with low oxygen, moisture concentrations, and at room temperature.