Investigation of the corrosion resistance of nickel-based alloys in fluoride melts

The results of tests of the compatibility of nickel-based alloys and metal-fluoride melts are generalized for molten-salt reactors. The structure and strength characteristics of the alloys Kh80MTYu, KhN80M-VI, and MONIKR in the initial state, after thermomechanical treatment and quenching, exposure for 1200 h to thermal convection loop filled with 58NaF-15LiF-27BeF sub(2) with heating by 100C, are investigated. A method for removing impurities from the melt has been developed. The results of corrosion tests performed on samples of nickel-based alloys in a setup with natural circulation with maximum melt temperature up to 700C and redox potential of the system 1.25-1.33 V relative to a beryllium comparison electrode are presented. It is shown that deep removal of oxidizing impurities from the melt and maintaining a low redox potential give slow uniform corrosion (less than 5 km/yr) of Kh80MTYu and KhN80M-VI samples. After the tests were completed, none of the alloys studied exhibited any tendency toward intercrystallite absorption.