PSA analyses of mitigation strategies for extreme external events

After the Fukushima nuclear accident nuclear regulatory bodies and nuclear industry in different countries are developing programs in order to strengthen the capability of their nuclear power plants to deal with extreme external events. Recently some of these programs have been discussed and some mitigation strategies have been proposed. In this paper few systems for water injection during severe events are proposed and analysed. Portable and/ or fixed equipment is considered as a part of each system. The initial assumption for each system is that the installed equipment is capable to survive extreme external events. Each system is modelled using the fault tree technique. Probabilistic safety assessment is performed. Comparison is made between the systems. The obtained results are analysed and discussed.