Abstract
The usefulness of ITER to fusion development can be substantially increased if the design parameters and features are selected so as to maximize reactor relevance without significantly increasing the risk. One critical area in which reactor relevance and risk are major issues is the tritium-producing blanket. A helium-cooled solid breeder blanket is found to offer the highest potential for a low-risk reactor-relevant blanket that can meet all the ITER requirements. It has many attractive features that include: (1) a large design margin to account for uncertainties in predicting the effects of the fusion environment; (2) an available data base that is rapidly expanding worldwide; (3) flexibility in accommodating changes in the operating parameters of ITER (e.g. fusion power and wall load); (4) solid breeder operation at reactor relevant temperatures and flexibility in setting the helium temperature to reduce risk and/or optimize the structure temperature while keeping the helium pressure at a modest level; and (5) safety features, including the use of inert gas with no chemical reaction or corrosion, a low activation solid breeder, and multiple containment of tritium.