Simulation of external reactor vessel cooling in a lumped-parameter code

In the course of a severe accident in a nuclear power plant the integrity of the reactor vessel may be preserved by External Reactor Vessel Cooling (ERVC). By flooding the cavity surrounding the reactor vessel the decay heat is removed from molten core material through the vessel wall to water at the submerged vessel surface. In order to simulate the boiling process at the external vessel wall during ERVC in the framework of lumped parameter codes a model based on a boiling model used in the code ANSYS CFX 13.0 is developed. (orig.)