Probabilistic Seismic Risk Assessment of Nuclear Reactor in a Hypothetical UK Site

The paper presents a probabilistic seismic risk assessment to determine the probability of unacceptable performance of a nuclear reactor in a hypothetical rock site in the UK. The analysis adopts an intensity-based approach, whereby the ground-shaking intensity is defined by accelerograms from the north-western European Stable Continental Region. The seismic demand of each component is estimated through eleven non-linear time-history analysis, however, to estimate with high confidence the seismic vulnerability obtained from a limited number of data, the results are statistically-manipulated using a Monte Carlo algorithm. The seismic capacity is computed through response-based fragility curves, using the spectral floor acceleration as demand parameter. The role played by the definition of the ground-shaking hazard on the overall seismic performance of the reactor is finally investigated by comparing the cumulative distribution of unacceptable performance obtained from the proposed intensity-based approach with those computed -for the same nuclear reactor and site, using different scenario-based approaches. It is demonstrated that the definition of the ground-shaking hazard has a strong effect on the cumulative distribution of probability of unacceptable performance and its variation for different probability of non-exceedance