Impurity activation in magnet structural materials for fusion reactors

Neutron-induced activity in fusion-reactor components can be effectively controlled through materials selection. This primarily applies to in-vessel components (first wall, blanket, etc.). However, some of the other machine components, such as the magnet coils, are also activated. In the Next European Torus (NET) project, for instance, activity in these components is high enough to require remote handling. The role of impurities in determining the activity in first-wall materials has already been investigated. In particular, it turns out that their medium- and long-term activity is remarkable affected by the presence of certain impurities. In order to satisfy currently proposed low-activity criteria, severe limitations have to be imposed on these impurities. In this paper, the authors examines the same problem in magnet structural materials. Specifically, the authors shall determine whether impurities can contribute a significant part of the activity in these materials.