Re-evaluation of the use of low activation materials in waste management strategies for fusion

The world fusion programs have had a long goal that fusion power stations s hould produce only low level waste and thus not pose a burden for the futur e generations. However, the environmental impact of waste material is deter mined not only by the level of activation, but also the total Volume of act ivated material. Since a tokamak power plant is large, the potential to gen erate a correspondingly large volume of activated material exists. The adop tion of low activation materials, while important for reducing the radiotox icity of the most active components, should be done as part of a strategy t hat also minimizes the volume of waste material that might be categorized a s radioactive, even if lower in level. In this paper we examine different f usion blanket and shield designs in terms of their ability to limit the act ivation of the large vessel/ex-vessel components (e.g. vacuum vessel, magne ts) and we identify the trends that allow improved in-vessel shielding to r esult in reduced vessel/ex-vessel activation. Recycling and clearance are o ptions for reducing the volume of radioactive waste in a fusion power plant . Thus, the performance of typical fusion power plant designs with respect to recycling and clearance criteria are also assessed, to show the potentia l for improvement in waste volume reduction by careful selection of materia ls' combinations. We discuss the impact of these results on fusion waste st rategies and on the development of fusion power in the future. (C) Publishe d by Elsevier Science B.V.