Effect of Radiation on Corrosion of Structural Materials by Molten Fluorides

A survey of the experimental methods used in testing the radiation stability of molten salts and their corrosion properties is presented. The effects of irradiation on the corrosion of Inconel exposed to fluoride fuel mixtures and on the physical and chemical stability of the fuel mixtures have been investigated by irradiating in the MTR capsules filled with static fuel and by operating in-pile forced-circulation loops in the LITR and in the MTR. In the many capsule tests and in the three in-pile loop tests made to date, no major changes have occurred in the fuel mixtures that can be attributed to irradiation, other than normal burn-up of uranium. Metallurgical examinations of the Inconel capsules and tubing have likewise shown no changes in corrosion that can be the result of radiation damage. The low corrosion results obtained for the in-pile loops have been confirmed by chemical analyses for corrosion products in the fuel mixtures.