Radiation Damage in a PWR Baffle-Bolt CW 316 Austenitic Stainless Steel Irradiated by Self-ions at High Doses and Temperatures: Comparison with a Fast Reactor Irradiation

Abstract

A transmission electron microscopy investigation of radiation-induced damage in a cold-worked 316 stainless steel of PWR baffle bolts is presented after 5 MeV Fe⁺⁺ or Ni⁺⁺ irradiation to 23 and 130 dpa at 380°C. The determined damage reveals a close match with BOR-60 fast reactor irradiation of the identical material (Heat B) to 25 and 46 dpa at 320°C. Both irradiations are compared in term of qualitative and quantitative assessment of Frank dislocation loops, cavities (not present in either self-ion or neutron irradiation), radiation-induced precipitates, and radiation-- induced segregation (RIS) at high-angle grain boundaries. Although the difference in dose rates was large, ~10^-3 dpa/s for self-ions and ~5 × 10^-7 dpa/s for fast neutrons, a relatively small temperature shift of 60°C was sufficient to emulate radiation-induced microstructure and segregation during a single ion irradiation. Additionally, the results from self-ion irradiations were compared with a high-dose radiation damage in a CW 316 SS of PWR fast flux thimble tubes characterized up to a dose of 100 dpa. In this case, the radiation damage induced by self-ions (except for cavities) matched even closer than for BOR-60 irradiations.