Numerical Simulation of Ex-Vessel Steam Explosion Based on 1000 MW Level PWR Nuclear Power Plant

In order to investigate the pressure distribution outside the vessel during the process of steam explosion including both the premixing stage and explosion stage, a three dimensional multiphase fluid analysis code MC3 D has been used based on the structural and environmental characteristics of the sever accident state of 1000 MW level PWR Nuclear Power Plant with the consideration of both pressure variation and impulse variation. Analysis of effect of break’s size and its location is also included. The results indicate that the explosion stage creates a high level and sharp pressure peak which threatens the integrity of the reactor cavity structure. In addition, when the intersection angle between axis of the vessel and location of the break is 45° and size of the break is 0.7 m, the risk of steam explosion is the greatest.