Application and development of containment sump strainers in PWR power stations in China

In the event of LOCA (Loss-of-Coolant Accident) or HELB (High Energy Line Break) within the containment of a light-water reactor (LWR), piping thermal insulation and other materials in the vicinity of the break will be dislodged by the pipe break and the ensuing steam/water-jet impingement. A fraction of this debris will be transported to the containment floor by the steam/water flows induced by the break and by the containment sprays. Some of this debris will eventually be transported to and accumulate on the containment sump strainers. Debris accumulation on the sump screen or strainers could challenge the plant's capability to provide adequate, long-term cooling water to the Emergency Core Cooling System (ECCS) and to the Containment Spray System (CSS) pumps. Some countries have carried out researches on the properties of containment sump strainers and debris transportation in containment and different types of containment sump strainers have been developed. In nuclear power stations of China, there also exist many problems of containment sump strainers. Increasing attentions were paid to the safety issue of containment sump strainers, and some new-style containment sump strainers have been developed. On the basis of comparisons between containment sump strainers of China and those of other countries, the authors discuss the problems, developments and applications of containment sump strainers in PWR power stations of China. (author)