Proposed plans for the use of soluble nuclear absorbers at the Idaho Chemical Processing Plant

Soluble neutron absorbers are proposed for criticality safety control in future processes at the Idaho Chemical Processing Plant. Solutions of neutron poisons have been used in the past for criticality control in processing various reactor fuels. No problems were encountered in the safe use of the neutron poisons although dissolution of different types of fuel occasionally required reevaluation of the poison concentrations. Proposed plans include the uses of soluble neutron poisons in the Rover fuel dissolver, the Fluorinel dissolver, and in increased concentrations in the electrolytic dissolver. These proposals are presented and the criticality safety aspects are discussed. The criticality safety of the Rover Fuels Processing Facility is assured by means of engineering design, soluble nuclear poison (boron), and administrative controls. Accumulation of a critical mass in the Fluorinel dissolver is prevented by positive identification of fuel units, administrative controls, procedures, and design of equipment to preclude double batching. The electrolytic dissolution facility is an existing facility at the ICPP for dissolution of stainless steel fuels. Gadolinium is used as a soluble neutron absorber in the nitric acid dissolving reagent and the cooling system. Stainless steel fuels planned for processing in the future will require reevaluation and adjustment of the gadolinium concentration to retain adequate criticality safety. Equipment design, administrative controls, sampling, and procedures are used to assure criticality safety