Effect of Irradiation Environment of Fast Reactor's Fuel Elements on Void Swelling in P, Ti-Modified 316 Stainless Steel

摘要

The difference in swelling behavior of P, Ti-modified 316 stainless steel (PNC316) between sample irradiation using material irradiation vehicle (e.g. FFTF/MOTA) and fuel assembly irradiation in FBR was investigated. From the evaluation of the dose dependence in the swelling of PNC316, it is clearly shown that swelling of claddings irradiated by fuel assemblies occurred earlier than the swelling of samples irradiated by material irradiation vehicle in the range of irradiation temperatures from 723K to 823K. The microstructural evolution of the claddings irradiated by fuel assemblies, which is represented by void formation, should be mainly affected by the irradiation environments: irradiation temperature history, temperature gradient within the thickness of the claddings, and by the primary and secondary stresses within the cladding during irradiation.