Improved Volatile and Semi-volatile Radionuclide Off-Gas Management

The capture and storage of volatile and semi-volatile radionuclides from aqueous reprocessing of used nuclear fuel (UNF) represent over 10% of capital costs and a significant fraction of operating expenses. While the current reprocessing schemes can capture, separate, and store the byproducts, they require substantial consumables or extreme temperatures (e.g., cryogenic distillation) and create significant volumes of waste products while failing to capture some critical off-gassing species fully. Therefore, there is a need, especially at the head-end of the process, to implement cost-effective separation and trapping of the volatile and semi-volatile species. Mainstream Engineering proposes to develop a series of selective adsorption steps based on vacuum swing separation unit operations integrating highly selective absorbents to trap and concentrate the volatile radionuclides. To maximize the efficiency, the absorbents will integrate highly selective metal oxide frameworks (MOFs) into a high solid loading, high porosity, hard, spherical polymeric beads which will optimize the use of the small particle size MOF active material and the adsorbent column ensuring the active MOF structure is fully available for the capture of the gasses and facilitating the packing in the columns. We will initially target 3H, 85Kr, 129I, and 14C gas management. These units will reduce the size of the radiation-shielded area required, decrease the number and complexity of the unit operations lowering the capital costs, simplifying logistics, reducing operating costs, and significantly lowering waste volumes created. This will enable reduced costs, improved capture of 129I and 85Kr, and retaining or capturing over 99.5% of the volatile radionucleotides.