Fused-salt-liquid-metal corrosion of refractory alloys in the presence of hot cell impurities

摘要

The pyrochemical conditioning of spent nuclear fuel for the purpose of final disposal is currently being demonstrated at Argonne National Laboratory (ANL). One aspect of this program is to develop a lithium preprocessing stage for the Fuel Conditioning Facility (FCF). Furthermore, a pilot scale of this preprocessing stage is being designed by ANL-W to demonstrate the in situ hot cell capability of this process. In this pilot scale system, fused lithium chloride salt is saturated with molten lithium to form a powerful fluxing compound with a vigorous reducing agent. During this stage of the fuel conditioning, the reduction will take place at a nominal temperature of 650 C in an argon-cell atmosphere contaminated with up to 10,000 ppm nitrogen, 100 ppm oxygen and 100 ppm of moisture. The maximum local temperature was calculated to be 725 C on the inner shell of the reduction vessel during operation. One of the significant concerns of this project is the system's corrosion response in the presence of irradiated commercial fuel as well as atmospheric impurities. The purpose of this work was to demonstrate the potential corrosivity of the salt matrix in a worse case environment as well as provide a boundary for allowable impurities in the system during operation.