Microstructural evolution in an austenitic stainless steel fusion reactor first wall

Abstract The design of near-term fusion reactors will require the extrapolation of radiation effects data which have been generated in fast fission reactors. A detailed rate-theory-based model of microstructural evolution under fast neutron irradiation has been developed to aid in this interpretation. The prominent new feature of this model is the treatment of dislocation evolution. Frank faulted loops form, grow, and unfault to provide a source for network dislocations while the dislocation network is simultaneously evolving. The dislocation evolution model has been coupled with a previously developed cavity swelling model. The predictions of this composite model compare favorably with fast reactor microstructural data over a broad range of irradiation temperatures and doses. The composite model has been used to predict the microstructural evolution in a DT fusion reactor first wall. The predicted network dislocation densities are generally somewhat lower for the fusion case. However, the major effects of the higher fusion He/dpa ratio are a reduced incubation time for swelling and enhanced swelling at low temperatures.

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