U.S.N.R.C. research on severe accidents and other safety matters

PRA studies have generally treated core melt accident sequences conservatively in terms of the likelihood of failure and the nature of the radiological release. Unless and until those conservatisms are removed, PRA methods by themselves are insufficient for judging the cost effectiveness of design modification to reduce the risk of severe accidents. The NRC coordinates program management and exchange information regularly with IDCOR and participates in joint programs with EPRI. The NRC has secured the participation of a number of countries in its program of physical research. NRC aims to secure sufficient data and methods to form a sound technical basis for Commission rules on severe accidents. (DG)