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

Abstract

The world fusion programs have had a long goal that fusion power stations should produce only low level waste and thus not pose a burden for the future generations. However, the environmental impact of waste material is determined not only by the level of activation, but also the total volume of activated material. Since a tokamak power plant is large, the potential to generate a correspondingly large volume of activated material exists. The adoption of low activation materials, while important for reducing the radiotoxicity of the most active components, should be done as part of a strategy that also minimizes the volume of waste material that might be categorized as radioactive, even if lower in level. In this paper we examine different fusion blanket and shield designs in terms of their ability to limit the activation of the large vessel/ex-vessel components (e.g. vacuum vessel, magnets) and we identify the trends that allow improved in-vessel shielding to result in reduced vessel/ex-vessel activation. Recycling and clearance are options 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 potential for improvement in waste volume reduction by careful selection of materials’ combinations. We discuss the impact of these results on fusion waste strategies and on the development of fusion power in the future.