Numerical Modelling of the Behaviour over 60 Years of a Nuclear Power Plant Containment Vessel Submitted to an Internal Swelling Reaction

In France, the extending of nuclear power plant service life from 40 to 60 years is an actual issue. Due to the number of nonlinear and concomitant concrete phenomena, such structure needs a reliable tool to ensure and predict their behavioural evolution. In this work, a thermo-hydro-chemo-mechanical model considering passive reinforcements in a distributed manner is applied to the calculation of a containment vessel with ISR. Shrinkage, creep, ISR swelling and induced damage are strongly coupled to each other, and all depend on thermal and humidity environmental conditions. The calculation is based on the available basic mechanical characteristics, the passive reinforcement ratios, the tensioning kinetic data of the prestressing cables and the structure’s geometry. The results show a good correlation with the multiaxial strains of the structure on the in-situ data. The model is used to make predictions over the next 30 years. Two scenarios of maximum swelling are considered. Cracking, which is an essential information for these containment structures, is compared between 30 years and 60 years. The prediction at 60 years shows that the pathology, with a hypothesis of rapid evolution, does not have a deleterious effect on the structure.