Understanding the role of defect production in radiation embrittlement of reactor pressure vessels

摘要

Understanding microstructural evolution in nuclear reactor pressure vessels (RPVs) is critical for predicting and modeling radiation embrittlement. It is however a complex process involving a variety of environmental variables (irradiation flux, fluence, temperature, etc.) and metallurgical variables (alloy composition, preexisting microstructure, etc.). Rate theory approaches have been used to incorporate these various variables and model the evolution of microstructural features such as alloy phases (e.g. copper-rich precipitates (CRPs)) and defect clusters with fluence. Embrittlement is caused by yield stress increases introduced by these hardening centers (hence the terms 'embrittlement' and 'hardening' are used interchangeably in the remainder of the paper). As available computing power increases, atomistic simulations of microstructual evolution such as molecular dynamics (MD) and kinetic Monte Carlo have become more practical. While offering the potential to eventually supplant mean-field rate theory, these approaches are in their early application stages and are subject to current computational and physical limitations e.g. inadequate interatomic potentials, limited simulation cell size and simulation time, incomplete reproduction of measured physical properties, etc.