Waste Disposal of Candidate Structural Materials in Fusion Reactors Utilizing Different Fuel Cycles

The management and disposal of the radioactive waste generated in any nuclear system are major safety and environmental concerns for the deployment of such a power source. The waste disposal rating is compared for four structural materials when used in deuteriumtritium, deuterium-deuterium, and D-³He fusion reactors. The materials considered are HT-9, primary candidate alloy (PCA), Tenelon, and a modified HT-9. Generic models for the reactors are assumed such that each produces a fusion power ofI0MW/m of the axial length and has a sufficient shield/blanket to produce identical magnet damage rates. The latter is achieved by varying the material compositions and thicknesses. The results show that using the advanced fuel cycle D-³He, with its low neutron yield, alleviates the activation problems and also allows considerable volume reduction of the radioactive waste. This cycle also permits the use of conventional alloys and at the same time satisfies the regulations criteria for shallow land burial of the low-level waste. In addition, and because of the low damage rate in the D-³He reactors, the useful lifetimes of the materials are greatly increased.