INTERCOMPARISON OF MICROCHEMICAL EVOLUTION UNDER VARIOUS TYPES OF PARTICLE IRRADIATION

The problem of irradiation-assisted stress corrosion cracking (IASCC) in reactor cores is currently being addressed using different types of particle irradiation (electrons, heavy and light ions) to study the effect of neutron damage. Differences among the types of irradiation include particle type, temperature, dose and dose rate. In using different types of particle irradiation, the issue becomes how to determine whether a particular irradiation experiment produces the same effect as neutron irradiation in terms of a measurable quantity such as the amount of grain boundary depletion of chromium in 304 (Fe-20Cr-9Fe) stainless steel. Results of computer modeling experiments indicate that the expected amount of segregation is a strong function of displacement efficiency (particle type) and dose rate at constant dose. Charged particle irradiation has a higher efficiency than neutron irradiation and is generally conducted at a higher displacement rate requiring larger doses to achieve the same measure of radiation effect. The expected amount of segregation is also a sensitive function of the proximity to steady state.