On Developing a Mechanistic Model and Supporting Database to Predict High Fluence-Low Flux Extended Life RPV Embrittlement: Status, Challenges and Opportunities

摘要

Reactor pressure vessel (RPV) embrittlement could limit the lifetime of light water reactors (LWRs). Radiation damage, caused by high energy neutrons, creates excess defects that cluster together or with solutes and act as hardening features. Further, the increased vacancy concentration enhances solute diffusion rates leading to accelerated formation of precipitates. Due to the very low solubility of Cu in Fe, Cu-enriched precipitates (CRPs) begin forming at low fluence. CRPs are well understood and are treated in current embrittlement prediction models. It is well established that CRPs are also enriched in Mn, Ni and Si, which increases their volume fraction and the corresponding hardening and embrittlement. While the effects of Ni and Mn are included in some current models, CRP embrittlement is assumed to saturate when Cu is depleted from the matrix. Further, the potential for precipitation of Mn-Ni-Si rich phases in low or Cu-free steels is not accounted for.