Abstract
Safety analysis has been the most important issue for the design of nuclear power plant (NPP) recently. Computational Fluid Dynamics (CFD) methodology can be applied in predicting the detailed knowledge of thermal-hydraulic phenomena in the applications of nuclear safety. In the present work, PWR pressure vessel model has been developed with CFD to predict the exhaustive of thermal-hydraulic behaviour in the downcomer of PWR. In the meanwhile, the framework composed of PIRT, validation and mesh uncertainty has been made to discuss the effects under different mesh designs followed from ASME V&V. Based on the analysis of PIRT, SO-1, MSLB, and SBLOCA were set as transient events for simulation. The results showed that unexpected variations on temperature, shear stress and velocity can be found near the vessel wall during a short period. The positions in downcomer for the inlet of cold leg and the neutron shielding plate may affect the core flow distribution and enhance cooling ability for core in some parts of vessel. This study presented the procedure of uncertainty qualification, including PIRT, mesh uncertainty and the methodology of CFD model, for PWR has been developed. The result can be regarded as the damage risk in RPV for comparison with the safety regulation requirements on vessel as well as a reference for the operation of PWR plants in Taiwan.