Concentration of plastic strains in steel liners due to concrete cracks in the containment wall

A substantial part of nuclear containments in US and Europe are designed with an outer bearing concrete structure and an inner sealing consisting of a tight-welded steel liner. The liner constitutes the ultimate leak-barrier, which prevents leakage at high internal pressure loads. The purpose of this paper is to show which influence a through-wall concrete crack may have on the strain level in the liner. A non-linear bar model is used to evaluate the liner behavior. It is shown that the effect from friction between the concrete and liner could be significant and cause high concentration of plastic strain. The influence of friction on the liner is verified by an experimental program presented in this paper. One of the conclusions is that concentrations of strain due to friction increase with decreasing liner thickness. This is important to consider when results from scale tests are interpreted. Scale models, which have thinner liners, could get significantly higher liner strain than the actual full-scale containment.