FULL-SCOPE PSA LEVEL 3 OF NPP GOESGEN - METHODS AND RESULTS

摘要

The severe accident at the nuclear power plant in Fukushima has increased the interest in the evaluation of offsite consequences caused by external events from a risk perspective. Therefore NPP Goesgen-Daeniken launched a project for the extension of the existing full scope (internal events and external events including seismic events and airplane crash) all operational states integrated Level 1/ Level 2 PSA model to a full Level 3 PSA for power operation. The model was developed using the linked event tree approach implemented in the risk software RISKMAN. The development of the Level 3 PSA model, included numerous analyses performed using MELCOR 1.8.6 (MELSIM_KKG) to evaluate source terms and plant response under severe accident conditions. A realistic data base has been generated for the site by using the GIS maps, statistical data on population distributions and agricultural products in a wide area (50 km radius, 785400 ha) covering parts of Switzerland and neighboring countries (Germany and France). The results include the analysis of the contamination level, public exposure (collective, individual and organs), complementary cumulative distribution functions and conditional probability distribution functions which are used for the integration of the results into the PSA model. This paper provides an insight to the full-scope PSA model, the methods used and the consequence analysis made for NPP Goesgen-Daeniken. Finally, it also gives a qualitative comparison with the Fukushima accident consequences.