Evaluation of Reactor Cavity Structure for Ex-Vessel Steam Explosion Loading

This paper documents the analytical evaluation of a reactor cavity structure subjected to ex-vessel steam explosion loading. The ex-vessel steam explosion may occur during a severe accident scenario after beyond-design-basis earthquake event when the molten core of the failed vessel begins to drop into a flooded reactor cavity area. This causes an impulse load on the reactor cavity that can impose greater demand on the structural components. The structural integrity and leak-tightness of the reactor cavity structure were evaluated using a detailed finite element analysis model. For selected critical loading cases, local damage in close proximity to the explosion locations was visible in the reactor cavity structure. While localized damage was present, the explosion loading cases did not affect the overall stability of the structure and the strain at the liner location was low enough to prevent any tearing of the liner or leakage.