Oxidation behavior of stainless steel for fast breeder reactor fuel cladding under low oxygen pressure

Corrosion behavior by oxygen and tellurium is studied on SUS-316 stainless steels for the cladding material of a fast breeder reactor under the condition simulating the atmosphere at the fuel-cladding interface during irradiation. The oxygen and tellurium potentials surrounding the specimen are controlled by Mo/MoO2 oxygen buffer and tellurium vapor, respectively. The mass gain by oxygen increases parabolically with reaction time under the condition of only Mo/MoO2 oxygen buffer. The parabolic rate constant is determined in the temperature range 873 -- 1073 K. Under the condition of Mo/MoO2 oxygen buffer and tellurium partial pressure, the corrosion behavior shows two characteristic features. Under tellurium partial pressure less than 10 Pa the oxidation behavior is not influenced by the existance of tellurium, and under tellurium partial pressure more than 10 Pa the mass gains by oxygen and tellurium increase rapidly with increasing tellurium partial pressure. The corrosion behavior is discussed, based on microstructual and compositional informations of the reaction layers. (author)