Fragility analysis and probabilistic safety evaluation of the nuclear containment structure under different prestressing loss conditions

Nuclear containment structure as the leak proof boundary for preventing radioactive materials leak into the environment during abnormal conditions. Studies on performance evaluation of nuclear containment structure under accidental conditions become a hot issue. This study presents fragility analysis and probabilistic safety evaluation of nuclear containment structure under different prestressing loss conditions. Firstly, detailed three-dimensional finite element model of nuclear containment was established. Then displacement distribution, maximum tensile stress distribution of concrete and stress distribution of steel liner is analyzed in depth. Finally, fragility and probabilistic safety evaluation of nuclear containment structure under different prestressing loss conditions were discussed. Results indicated that before concrete cracking, displacement at the equipement hatch is obviously different from that of yield of the steel liner, ordinary reinforcing steel and prestressed tendon. When internal pressure is less than 0.9 MPa, and the difference between the displacement at different elevations of \ cylinder wall is small. When internal pressure exceeds 0.9 MPa, the difference of displacement at each elevation becomes obvious. With the increase of prestressing loss level, median pressure capacity of the containment structure decreases, and the logarithmic standard deviations are basically unchanged. The variation of the safety margin and the total failure probability of the containment structure under prestressing loss level larger than 30% condition are larger than that of prestressing loss level less than 30% condition.