Development of an assessment system for fracture safety and reliability on reactor pressure vessel

Long-term operation of reactor pressure vessels (RPVs) leads to material aging due to fast neutron irradiation, resulting in a significant reduction in fracture toughness. As the fracture toughness decreases, the defects in the vessel are more likely to penetrate the wall thickness under rapid start up and stop of reactor, pressurized thermal shock (PTS) and other heating or cooling events, threatening the safety of the reactor. In this paper, the fracture safety evaluation methods of the RPV under pressurized thermal shock event, pressure-temperature (P-T) curve under start up and stop, and PTS failure probability problem were studied based on the fracture mechanics theory. With these methods, this study presents a modular assessment system that integrates fracture mechanics, finite element analysis, and international standards to evaluate RPV fracture safety and reliability under pressurized thermal shock and startup/shutdown events. The developed system provides an important technical support and convenient integrated analysis tool for RPV fracture safety assessment in nuclear power plants, demonstrating innovation in its application within the domestic nuclear industry.