Investigations on pressure drop characteristics and disposal optimization of conflux channels of containment sump strainers

In the event of LOCA (Loss-of-Coolant Accident) or HELB (High Energy Line Break) within the containment of a light-water reactor (LWR), some debris will be transported to and accumulate on the containment sump strainers by the steam/water flows induced by the break and by the containment sprays. And pressure loss will be introduced by the accumulated debris, which will decrease the available net positive suction head (NPSH) of circulating pumps of emergency core cooling system (ECCS) and containment spray system (CSS). Then cavitations may occur to induce the failure of ECCS and CSS pumps. Consequently it is necessary to carry out calculation and experiment to investigate the pressure drop characteristics of containment sump strainers. In the event of LOCA or HELB, the pressure drop of containment sump strainers is mainly composed of the pressure drop introduced by debris bed, strainer screen and the conflux channels. The authors established 3-D computational simulations to conduct investigations on the velocity field distribution and the pressure field distribution of water flow in the conflux channels. By analyzing pressure drop characteristics, the design optimization and disposal optimization were brought forward to minimize the pressure loss. (author)