Risk implication of severe accident management strategies

The Swiss Federal Nuclear Safety Inspectorate (HSK) is in the process of conducting independent Probabilistic Safety Analyses (PSAs) of all swiss nuclear power plants, in support of the ongoing periodic safety reviews, and other regulatory requirements. These studies are full scope level 1 / level 2 PSAs, including external events and uncertainties. The uncertainty analyses address both the so-called lack of knowledge uncertainties as well as stochastic uncertainties. These studies are being maintained as living PSA for use in regulatory decision making. An example level 2 study for a PWR type reactor, with large, dry containment is used for the present accident management study. In the analysis, the evaluation of accident progression does not credit automatic systemic recoveries (due to recovery of AC power, for instance), for lack of plant-specific data, and severe accident management strategies (SAMs), which are not yet implemented. The risk implications of SAMs are discussed in the present article. For all SAM strategies, with the exception of accident management involving SGTRs, all of the level 2 analyses are repeated