New Codification Approach for the Design of NPP Containments With Metallic Liner

We address in this paper the case of a new generation PWR NPPs, which containment is equipped with a metallic liner on the inner face, in order to minimise leakage. A net of angles that, in addition to studs, constitute the anchoring system to the concrete, strengthens this metallic liner, also used as concrete shuttering during the construction phase. The thickness of the plate, the size and distribution of the anchors and the mechanical characteristics of the steel are the main parameters of the liner design. The accidental and in service loadings on the liner which are mainly due to the concrete pre-stressing and shrinkage and to the temperature inside the containment, can lead to local blistering. This phenomenon was observed on 900 MW PWR currently in operation in France. Difficulties related to the application of the available codification while using modern numerical methods are in a large extent due to the small strain allowable for the liner plate, considering the above loadings in addition with initial imperfections or failure of one or several studs. In order to cope with this problem, while respecting the safety requirements, a new codification approach has been developped.