Risken för översvämningar vid de svenska kärnkraftverken : en statistisk och historisk extremvärdesanalys

Sammanfattning: This thesis investigates the overall risks of flooding over the Design Basis Flooding Level (DBFL) at the Swedish nuclear power plants (Oskarshamn, Ringhals and Forsmark), using statistical data and methods, but also considers historical events which might affect the overall risk of flooding at the specified sites. Considering the nuclear accident which happened in Fukushima in conjuction with the earthquake and tsunami which struck eastern Japan on 11 March 2011, operators and licensors of nuclear power plants all over the world conducted reviews and investigations on the overall risks posed to the plants from external events. One important such event is extreme water level. One part of the thesis includes an extreme value analysis (using Generalized Extreme Value distribution and Generalized Pareto distribution) of water level data from SMHI (Sweden's Meteorological and Hydrological Institute) measured at stations close to the Swedish nuclear power plants. The results of the statistical studies indicate that considering the return period used in the thesis (100 000 years), the water levels at the Swedish nuclear power plants are not expected to exceed DBFL. The other part of the thesis consists of a historical study of extreme weather-related events. The results of this study indicate that no historical events seem to have occured which would indicate a higher risk of flooding than the one suggested by the statistical study.