Corrosion of Stainless Steel for HLW Containers Under Gamma Irradiation

ABSTRACTThe corrosion behavior of type 304 stainless steel was studied under gamma irradiation as part of the evaluation for the long-term durability of high-level radioactive waste (HLW) disposal containers. Gamma rays, generated from fission products in high-level radioactive waste, are considered to change the environment around the canisters and overpacks. The redox potentials for NaCl solutions and corrosion potentials of stainless steel were measured to consider the effects of gamma irradiation, by using an electrochemical method. The pitting potentials of stainless steel for NaCl solutions were also measured to examine the pitting corrosion under gamma irradiation. As a result of this experiment, it is concluded that the oxidizing properties as a result of the formation of H2O2 and H2 produced by gamma irradiation depended on the concentration of Cl−, and that the strength of oxidizing properties of 1M (mol·dm−3) NaCl solution was particularly high. and the pitting corrosion was found for 1M NaCI solution under gamma irradiation at the dose rate of 2.6×102 C/kg·h (1.0×106 R/h) at 60°C, by using an electrochemical method.