On Plastic Collapse Analysis

This report describes an in-depth finite element simulation of a spent fuel canister for geological disposal loaded in iso-static pressure until plastic collapse. The canister consists of a copper overpack and a ductile cast iron insert with steel cassettes where the spent fuel is placed. The higgly non-linear finite element analysis is based on the explicit formulation and includes large deformations, non-linear material behaviour and contact between the canister components. The analysis includes comparison between two-and three dimensional models and assessment of the different geometrical features such as corner radius of the cassette, cassette off-set, different bonding/dedonding conditions between insert and steel cassette. The analysis shows that the bonding cassette/insert has a large impact on the collapse load. Two large-scale mock-ups test that had been performed earlier are also simulated by the developed finite element models. There is a very good agreement between measured and computed deformations versus applied load and collapse load.