Improving Safety and Economic Feasibility of NPP by Management of Secondary Side Piping Life

Flow accelerated corrosion (FAC), which caused major accidents at Sarri-2 NPP and Mihama-3 NPP, is the main ageing mechanism of NPP secondary side piping. FAC determines the service life of piping made of carbon steel. Wear prediction using computer codes is considered a tool for life management. The paper presents analysis of computer codes of the USA, Germany and Russia and considers the advantages of computer codes for life management and repair planning. Some problems that arise from using computer codes for analyzing the results of ultrasonic thickness gauging are indicated. The paper provides the algorithm for piping life management at Japanese NPPs and proposes the ways of improving piping life management algorithm, which makes it possible to proceed to the implementation of piping repair concept according to their condition.