Investigation on the Plasticity Correction of Stress Intensity Factor Calculations for Underclad Cracks in Reactor Vessels

摘要

When conducting structural integrity assessments for reactor pressure vessels (RPVs) subjected to pressurized thermal shock (PTS) events, the stress intensity factor (SIF) is evaluated for a postulated crack near the inner surface of RPVs. If the underclad crack is postulated, it is known that the cladding made of a stainless steel has a relatively lower yield stress, the plasticity effect of cladding should be considered in SIF calculations. In the previous study, the authors proposed a plasticity correction method on SIFs for underclad cracks based on three-dimensional finite element analyses for Japanese three-loop RPVs using un-irradiated material properties. In this paper, further studies were conducted to investigate the applicability of the proposed plasticity correction method. The effect of hardening due to neutron irradiation was considered. In addition, different Japanese RPV geometries such as two-loop and four-loop RPVs were also investigated.