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 co nsidering this application, two factors relating to the long-term avai lability 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 n eutron flux. Both factors indicate a need to conserve tungsten resourc es through the reclamation of used material. Re-use of the tungsten is favoured by the fact that its radioisotopes are relatively short-live d, hence chemical separation from its transmutation products after a c ooling period of about 15 years would, ideally, yield a non-active rec ycled material. Several plausible processes are examined for segregati on of tungsten from its principal transmutation products Os, Re, Ta, I r, Pt and Hf, and a route based on chlorination followed by fractional distillation of the metal chlorides is suggested as the most promisin g.