Stress distribution and fatigue crack growth in pressurized tubes including the effect of swelling and radiation creep

The lifetime of the first wall and blanket system of fusion reactors can be limited by fatigue crack growth due to cyclic operation of a fusion reactor. Many lifetime calculations have been performed in the past, often using constraint plates to simulate the first wall. As an alternative and a further step in the direction of more complex structures the behaviour of pressurized tubes has been investigated. The stress distribution caused by external heating and internal pressure changes due to radiation creep and swelling. Cyclic operation of the fusion reactor causes a change of the stress field. The stress intensity factor range ΔK was calculated for different locations of cracks and fatigue crack propagation until final failure was predicted. For stainless steel 316 small pre-existing cracks cause failure after relatively short lifetimes