Activation properties of tungsten as a first wall protection in fusion power plants

Tungsten is a candidate material for protective armour on the plasma-facing first wall of a fusion power plant. In order to assess the radiological implications of this use of tungsten, two power plant models from the European Power Plant Conceptual Study (PPCS) have been extended by the addition of a 2 mm tungsten layer on the ferritic–martensitic first wall. Neutronics and activation modelling have shown that there is no significant impact on the favourable conclusions regarding long-term disposal of materials, but that earlier activity levels could potentially be of importance on the timescale of maintenance operations. The short-term activity and decay are expected to have only a minor impact on the consequences of postulated accidents.