다중기기 손상 상관성에 의한 지진리스크 영향 분석 = Influence Analysis of Seismic Risk due to the Failure Correlation in Seismic Probabilistic Safety Assessment

다국어 초록 (Multilingual Abstract)

The seismic safety of nuclear power plants has always been emphasized by the effects of accidents. In general, the seismic safety evaluation of nuclear power plants carries out a seismic probabilistic safety assessment. The current probabilistic safety assessment assumes that damage to the structure, system, and components (SSCs) occurs independently to each other or perfect dependently to each other. In case of earthquake events, the failure event occurs with the correlation due to the correlation between the seismic response of the SSCs and the seismic performance of the SSCs. In this study, the EEMS (External Event Mensuration System) code is developed which can perform the seismic probabilistic safety assessment considering correlation. The developed code is verified by comparing with the multiplier n, which is for calculating the joint probability of failure, which is proposed by Mankamo. It is analyzed the changes in seismic fragility curves and seismic risks with correlation. As a result, it was confirmed that the seismic fragility curves and seismic risk change according to the failure correlation coefficient. This means that it is important to select an appropriate failure correlation coefficient in order to perform a seismic probabilistic safety assessment. And also, it was confirmed that carrying out the seismic probabilistic safety assessment in consideration of the seismic correlation provides more realistic results, rather than providing conservative or non-conservative results comparing with that damage to the SSCs occurs independently.

참고문헌 (Reference)

1 Ellingwood B., "Validation studies of seismic PRAs" 123 (123): -189-196., 1990

2 Kim JH, "Uncertainty analysis of system fragility for seismic safety evaluation of NPP" 241 (241): 2570-2579, 2011

3 "Severe accident risk assessment – Limerick Generation Station (in 2 vols.)" Philadelphia Electric Co. by NUS Corporation 1983

4 Ravindra MK., "Sensitivity studies of seismic risk models" Electric Power Research Institute 1984

5 Smith PD, "Seismic safety margins research program" Lawrence Livermore Laboratory 1981

6 US Nuclear Regulatory Commission, "Reactor Safety Study" 1975

7 US Nuclear Regulatory Commission, "Procedures for the External Event Core Damage Frequency Analyses for NUREG-1150" 1990

8 Budnitz RJ, "Correlation of Seismic Performance in Similar SSCs (Structures, Systems, and Components)" Nuclear Regulatory Commission 2017

9 Reed JW, "Analytical Techniques for Performing Probabilistic Seismic Risk Assessment of Nuclear Power Plants" 3 : 253-261, 1985