Coupled Simulation of Reactor Pressure Vessel (RPV) subjected to Pressurized Thermal Shock (PTS) Using Cardinal

As one of the most significant components of a Reactor, the Reactor Pressure Vessel (RPV) is exposed to an aggressive environment during the operation time (e.g. more than 40 years). Ageing degradation mechanisms (e.g. thermo-fatigue) could grow initial defects up to a critical size, increasing the susceptibility to failure in the RPV. Very limited studies consider the real conditions of the RPV subjected to a thermal shock due to a Loss of Coolant Accident (LOCA). During a LOCA event, the most severe conditions take place when the emergency core cooling (ECC) water is injected inside the cold legs filled initially with hotter water and/or steam. The rapid cooling of the down-comer and the internal RPV surface followed probably by re-pressurization of the RPV causes large temperature gradients and variation of pressure which induces thermal-mechanical stresses. In order to develop the model for integrity assessment of a RPV subjected to pressurized thermal shock (PTS), a multi-physics simulation, which includes the thermo-hydraulic, thermo-mechanical and fracture mechanics analysis is necessary. In this paper, a demonstrational coupled simulation is performed to support multi-physics analysis for RPV subjected to PTS. The study use a simplified computational domain to represents a real RPV. The purpose of the study is to demonstrate the capability of predicting the transient temperature and stress response of RPV to ECC injection with coupled simulation. The prediction of the temperature and stress field is achieved by using Cardinal, a wrapping of the GPU-oriented spectral element Computational Fluid Dynamics (CFD) code NekRS and other multi-physics sub-module within the MOOSE framework.