CHARPY IMPACT PROPERTIES OF LOW-ACTIVATION ALLOYS FOR FUSION APPLICATIONS AFTER NEUTRON-IRRADIATION

The MANITU irradiation and fracture-toughness testing program although initially foreseen to clarify the early dose-saturation of Delta DBTT for commercial ferritic steels has been extended to include the mediu m temperature (greater than or equal to 250 degrees C) irradiation har dening behaviour of promising low-activation alloys. The results after a first 0.8 dpa irradiation clearly show a much better behaviour of t he new alloys in any respect (e.g. DBTT after irradiation always below +50 degrees C for subsize specimens, for the ORNL steel even below -2 0 degrees C). The complexity of temperature dependency is probably cau sed by the transition range in dose accumulation, and should therefore not be 'over-interpreted'.