Integrated items safety classification method considering risk evaluation for nuclear reactors

The safety classes of items, which are the basis of selecting appropriate design and manufacture codes, seismic grades, and quality assurance classes, are directly related to the safety and economy of nuclear reactors. The reasonable safety classification of items is very important for improving the safety and economy of nuclear reactors. The current safety classification of items is sometimes too conservative, without combining different safety classification approaches, such as function based, consequence based, and probability based. This contribution firstly introduced and compared the 50-SG-D1, SSG-30, and risk-informed safety classification methods briefly. Then, based on these safety classification methods, an integrated items safety classification method considering risk evaluation for nuclear reactors was proposed, and a case study was performed on the Vacuum Vessel Pressure Suppression System (VVPSS) of International Thermonuclear Experimental Reactor (ITER) to demonstrate the effectiveness of the proposed method. The results show that the proposed method, which fully integrates the characteristics of 50-SG-D1, SSG-30, and risk-informed safety classification methods, is more comprehensive and advanced.