Radiation-induced inter-granular segregation in first wall fusion reactor materials

Experimental evidence for phosphorus segregation at grain boundaries in steels is presented. Theories for irradiation-induced inter-granular segregation are described. Non-equilibrium segregation (NES) and rate theory approaches have similar success in predicting phosphorus behaviour in the practically important temperature range although site competition and micro-structural effects are better accounted for by the NES theory. The need for better data on diffusion constants and point defect-impurity binding energy is emphasised.