Applications of the CONTAIN 1.0 computer code to the analysis of containment loading under severe accident conditions

Recently, the computer code CONTAIN 1.0 was released; it is intended to be the US NRC's principal best estimate calculational tool for severe accident containment analysis. It models all three phenomenological areas of interest in such analyses: thermal-hydraulics, aerosol behavior, and fission product decay, heating and transport. As the code has matured, and as validation and testing have generated confidence in its predictions, it has been found to be useful in a number of NRC studies over the past year. This paper discusses some of the more interesting results which have been obtained when CONTAIN 1.0 has been applied to practical accident sequence calculations. Several elements of NRC's source term work have made use of CONTAIN. For example, a large number of parametric calculations were run for the Containment Loads Working Group. Phenomena studied included the effect of heat sinks on steam spikes, and the effect of direct heating of the containment atmosphere by finely dispersed hot debris. More recently, a number of parameter studies have been run for NRC's source term study relating to the effects of pressure- or temperature-dependent containment leakage, and of containment isolation failure. These two sets of calculations are the focus of this paper. Other recent applications of CONTAIN are also cited but not reviewed in detail