Low activation structural materials for fusion

Low-activation materials are seen as an important means of enhancing the safety and environmental advantages of fusion as an alternative energy source. potential benefits are anticipated in diverse areas of operation embracing an extremely wide span of timescales, ranging from considerations of decay heat and accidental releases for which relevant radionuclide decay times may be in the order of hours, to aspects of waste disposal for which timescales of millenia are appropriate. Thus, in addition to an extensive set of engineering property specifications, there is a range of possible radiological requirements on low-activation materials, not all of which may be satisfied simultaneously. Possible design aims for low-activation materials are discussed and the performances of some proposed candidates examined. The effect of critical impurity elements on the radiological properties is considered and the prospects for reduction of impurity contents to acceptable levels in commercial-scale production are examined. (author). 12 refs.; 13 figs.; 4 tabs