Mechanical strength of the first wall box of NET loaded by accidental internal pressure

The structural analysis of a first wall box design proposed for NET (Next European Torus) is presented. It was performed assuming the accidental loads due to a coolant pipe break in a breeding blanket module and the consequent failure of the module shell. The pressure transient has been determined from the reaction kinetics of the breeder-water interaction. Finite-element analysis in both the elastic and the elastic-plastic regime was carried out on a single shell structure equivalent to the real structure of the box. The first wall failure is reached for an overpressure of about 0.15 MPa. The time for mitigating counter-measures is about two hours