RECENT PROGRESS IN FUSION-REACTOR MATERIALS STUDIES - FOCUS ON TRANSMUTATION AND RADIOACTIVATION ASPECTS

A review is presented of recent progress attained in the understanding of the influence of transmutation on the development of fusion-relevant property change data. It is shown that early experiments on helium effects on void swelling, irradiation creep and tensile properties of austenitic stainless steels were often misleading, and the influence of helium is much smaller than originally expected. Similar definitive conclusions concerning the role of helium in ferritic steels, copper alloys, and vanadium alloys cannot be drawn at this time. It is also shown, however, that the formation of solid transmutants can be very important in a number of alloy systems, especially for some of those proposed as reduced radioactivation candidates.