An evaluation of the application of fracture mechanics procedures to fusion first wall structures

An analysis of the application of J integral based elastic-plastic fracture mechanics procedures to fusion structures is carried out. Some limiting flaw-structure geometries are specified along with estimates of upper- and lower-bound service properties of a martensitic stainless steel. Size requirements for J procedures in unconstrained flow geometries and for low strain-hardening conditions result in a small range of valid application even for lower-bound properties. In constrained deformation geometries the range of application is extended for lower-bound properties. Failure of J procedures is shown to coincide with approach to fully-plastic fracture, which can be treated partly with limit-load or net-section stress criteria.