It has been shown in containment pressure tests that the global displacement measured at liner failure does not correspond to the critical strain level for the liner. A general conclusion from these tests is that significant strain concentration has to take place to get this "early" liner failure. In this paper the detailed liner behavior in the region of the equipment hatch of a 1/4 scale containment model (Sandia 1/4) is studied by non-linear finite element models. An analysis approach with three levels of model discretization is used, where level 1 regards the global concrete containment behavior, level 2 regards the local liner-concrete interaction and level 3 regards the detailed strain level in vicinity of a discontinuity. The results from this study show two typical regions with elevated liner strain; (1) in the vertical folds between the equipment hatch embossments and the general curved wall and (2) in sections where the wall hoop reinforcement is decreased. The elevated strain along the vertical fold arises due to the flexural behavior when the liner is straightened out at high internal pressure. The elevated strain in regions with decreased reinforcement arises due to decreased axial wall stiffness in these regions. In the Sandia 1/4 pressure test, liner failures were detected in regions which agrees with elevated strain found in this paper.
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