Mechanical and leakrate predictions for nuclear power plant containments in accidental conditions

In 1996, EDF decided to build a containment model at the scale 1:3, the Maquette echange vapeur/air (MAEVA) mock-up, in order to check and study the behavior of a prestressed concrete containment vessel without liner in terms of mechanical strength and leaktightness, for loadings corresponding to its design and beyond design conditions. In parallel to the construction and testing of the mock-up, predictive calculations of the mechanical and leaktightness behaviour of the mock-up were performed in the framework of a cost shared R&D action supported by the European Union, the Containment Evaluation under Severe Accidents (CESA) project. The strategy of EDF concerning the R&D performed on leaktightness of concrete and concrete structures is first explained and the goal of two interesting programs is shortly presented and discussed in the first part of the paper. Then, the emphasis is made on the predictive calculations performed on the MAEVA mock-up by means of finite elements (FE) calculations. A summary of the main achievements is then given and the interest of FE calculations is discussed for describing both the mechanical and leaktightness behaviour of a concrete structure as a function of crack development.