The zero-waste option for nuclear fusion reactors: Advanced fuel cycles and clearance of radioactive materials

This paper deals with the radioactive waste issue for fusion reactors, proposing an innovative solution (the “zero-waste” option), which could be a clear advantage of fusion power versus fission, in view of its ultimate safety and public acceptance. Its goal is the Clearance (declassification to non-radioactive materials) of all reactor components, after a sufficient period of interim decay, according to the recommendations recently issued by IAEA. Even if feasible in theory, a zero-waste option for fusion reactors using the Deuterium–Tritium fuel cycle will be difficult to obtain in practice: a relevant amount of radioactive materials from reactor decommissioning – even if recyclable within the nuclear industry – should be disposed of as low-level waste. As a further step towards the zero-waste option, the features of fusion reactors based on alternative advanced fuel cycles have been examined, to assess whether that goal could be reached for such devices. Fusion reactors with advanced Deuterium–Helium-3 (DHe) fuel cycle have quite outstanding environmental advantages. Compact ignition tokamaks can be designed in order to achieve DHe ignition. Ignitor, a compact ignition experiment aimed at studying DT plasmas, may also be used in that direction. The extrapolation of Ignitor technologies towards a larger and more powerful experiment using advanced fuel cycles (Candor) is described. Results show that Candor does reach the zero-waste option. A fusion power reactor based on the DHe cycle could be the ultimate correct response to the environmental requirements for future nuclear power plants.