Study on In-Containment Refueling Water Storage Tank Filter Upstream Effects Analysis Based on Three-Dimensional Design

After the high-energy pipeline break accident in the containment, the pipeline insulation and other materials near the break will be damaged after impact, which will produce a large amount of debris. Some debris will be produced, a fraction of this dislodged insulation and other materials will be transported to the containment floor by the steam/water flows from the break and the containment spray. The in-containment refueling water storage tank is widely used in the third-generation nuclear power plant as the water source to support long-term recirculation for the functions of residual heat removal, emergency core cooling, and containment atmosphere cleanup. Typically, a filter is installed around inlet of pump to filter the debris and to minimize the amount of debris entering the downstream lines and the reactor core. The accumulated debris on the screen of filter may increase the differential pressure across the screen and thus decrease the net positive suction head margin available to pumps. The system may even disable all operational capability. In order to evaluating the performance of filters during and after accident, a reasonable conservative debris evaluation is required as design input. In order to accurately evaluate the impact of filter after accident, a reasonable and conservative debris source term evaluation is needed as the design input. The nuclear island design of the third-generation nuclear power first project fully adopts 3D modeling. This paper introduces the improvement of the upstream analysis method of IRWST filter based on three-dimensional design.