Swelling and swelling resistance possibilities of austenitic stainless steels in fusion rectors

Fusion reactor helium generation rates in stainless steels are intermediate to those found in EBR-II and HFIR, and swelling in fusion reactors may differ from the fission swelling behavior. Advanced titanium-modified austenitic stainless steels exhibit much better void swelling resistance than AISI 316 under both EBR-II and HFIR irradiations. The stability of fine titanium carbide precipitates plays an important role in void swelling resistance for the cold-worked titanium-modified steels irradiated in role in void swelling resistance for the cold-worked titanium-modified steels irradiated in EBR-II. Furthermore, increased helium generation in these steels can (a) suppress void conversion, (b) suppress radiation-induced solute segregation and (c) stabilize fine MC particles, if sufficient bubble nucleation occurs early in the irradiation. The combined effects of helium-enhanced MC stability and helium-suppressed RIS suggest better void swelling resistance in these steels for fusion service than under EBR-II irradiation. (orig.)