Authors: Z. Chen, D. Lu, H. Zhao, Y. Zhang
Year: 2021
Industry: Nuclear & SMR
Keywords: Use FSE, Transient, Dynamic, Validation, Verification
ABSTRACT
The feed water pipes of steam generators (SG) stretch across the pump building of the component cooling water system (CCS), thereby connecting the reactor containment and the steam turbine building in the pressurized water reactor of a nuclear power plant. When main feed water pipes rupture, large quantities of water and steam may discharge into the CCS pump building, which causes the CCS pumps to be submerged and the CCS system to shut down, thereby threatening the safety of nuclear power plants. Therefore, it is necessary to analyze the overflow characteristics after such an accident. However, it is difficult to perform experiments in the CCS pump building, owing to its huge area and complex structure. In this study, numerical simulation was performed via computational fluid dynamics by using the volume of fluid model, in which three phases (water, air, and steam) were considered. Validation & Verification (V&V) is performed by comparing the calculated results with experimental verification of the small model, so that the reliability of the calculation method and results are proved. Overflow characteristics in three different accidental conditions were also analyzed: the pump trip accident triggered by double-end fracture (TDEF), pump trip accident triggered by conservative maximum flow rate discharge (TmaxD), and pump trip accident not triggered by a fracture (TnotF) in the pressure compartment. It has been revealed that under TDEF and TmaxD, the maximum water level around the two CCS pumps is lower than the waterproof foundation bed of the CCS pumps. However, under TnotF, the highest water level around the two CCS pumps is much higher than the waterproof foundation bed of the CCS pumps, which may threaten their safety. To address this problem, certain new optimization design schemes have also been proposed.