Reclamation of tungsten from activated fusion reactor components

Tungsten or tungsten-rich alloys have been proposed as constructional materials for various near-plasma components in fusion reactors. In considering this application, two factors relating to the long-term availability of tungsten should be taken into account. Firstly, it should be noted that tungsten is a relatively rare element and has non-fusion applications for which it would be difficult to find substitutes and, secondly, that it exhibits a high rate of transmutation in a fusion neutron flux. Both factors indicate a need to conserved tungsten resources through the reclamation of used material. Re-use of the tungsten is favoured by the fact that its radioisotopes are relatively short-lived, hence chemical separation from its transmutation products after a cooling period of about 15 years would, ideally, yield a non-active recycled material. Several plausible processes are examined for segregation of tungsten from its principal transmutation products Os, Re, Ta, Ir, Pt and Hf, and a route based on chlorination followed by fractional distillation of the metal chlorides is suggested as the most promising.