Zone refining work at Trombay

The theory of zone-refining, a technique to obtain materials in ultrapure form, is explained. The purity achieved by this purification process is of the order of 99.999 (5N) or more. The know-how of this technique in India was developed by the Chemistry Division of the Bhabha Atomic Research Centre, Bombay. The division fabricated a prototype of automatic zone refining unit in 1965 and later on built many such units. Utilising this know-how, the Nuclear Fuel Complex, Hyderabad fabricated larger units which are in operation at its Special Materials Plant. (M.G.B.)