Evaluation of susceptibility on crevice corrosion for ITER vacuum vessel

Nakahira, Masataka

JAERI-Tech 2003-083, 79 Pages, 2003/11

JAERI-Tech-2003-083.pdf:10.29MB

The ITER Vacuum Vessel has a double-walled structure and cooling water is filled in between inner and outer shells. It is planned to apply T-welded joints with partial penetration at the connection between outer shell and rib. The length and gap of non-penetrated part are controlled and limited to less than 5mm and 0.5mm respectively. Although it can be considered to be low susceptibility, crevice corrosion can possibly occur, because the water is stagnant in the crevice and impurities will condense. In this report, the corrosion-crevice repassivation potential, E, was experimentally measured under the several density of NaCl solution, and compared to the steady-state corrosion potential in the pertinent environment, to evaluate the susceptibility. Simulated conditions are normal operating condition with water temperature of 150C, baking operation with water temperature of 200C and impurity condense by cyclic wet and dry condition.