An experience in dynamic seals of reduction and hydrofluorination furnaces in refining plant

Reduction and hydrofluorination are some of the most important stages in the production of nuclear grade green salt, UF4, involving solid-gas reactions. They are difficult steps considering the process conditions and nature of materials to be handled (reduction involves cracked ammonia at 600 deg C which is highly explosive, handling of brown oxide which is radioactive and pyroforic; hydrofluorination involves highly toxic and corrosive hydrofluoric acid diluted with cracked ammonia at 450 deg C). In view of the above, emphasis has to be given for efficient leak tightness of the equipment being employed for this purpose such that atmospheric air should not leak into the equipment as well as process gases, radioactive powder should not leak out. Previous experience from other Department of Atomic Energy (DAE) units, indicated that the failure of dynamic seals is the nagging problem with consequent bearing on safety, availability and ease of maintenance. The attempt made in improving the design, showed promising results at Rare Materials Plant (RMP), Mysore is described. (author)