Evaluation of the structural integrity of the CPR1000 PWR containment under steam explosion accidents

Abstract

Detailed three-dimensional finite element models were set up to study the dynamic response and the possible damage of the CPR1000 PWR containment under steam explosion accidents with a full consideration of the complex geometric structures, the complex mechanical behavior of materials and the complex blast loadings. The structural integrity of the containment and the internal structures was evaluated under five typical steam explosion scenarios. In addition, the influence of the thermal loading was investigated by setting up a thermal-mechanical coupling finite element model. It is found that under steam explosions, only a small portion of energy is transferred to the concrete containment and therefore, the influence of the explosions on the containment is insignificant. Although the internal facilities and the structures are damaged severely by the blast loadings, the damage to the containment is negligible and the structural integrity is ensured. The thermal loading has a noticeable influence on the loading-capability of the containment structure. It is shown even a pure thermal load, i.e., a 150°C temperature variation across the containment wall, can cause some damage to the concrete containment. The damage is further deepened by a simultaneous blast loading due to a steam explosion. However, the maximum depth of the damage is small compared with the thickness of the wall and the integrity of the concrete containment is still ensured.