Current status of pyrochemical reprocessing research in India

Abstract

Reducing the cooling time of spent fast breeder reactor (FBR) fuel, thus reducing the doubling time and introducing metallic fuels into FBRs, is essential for meeting the increasing energy demand of India. Development of pyrochemical reprocessing technology for processing the spent FBR fuels is another prerequisite. Accordingly, studies on the molten salt electrorefining process for metallic fuels and the oxide electrowinning process for oxide fuels have been carried out at the Indira Gandhi Centre for Atomic Research, Kalpakkam. A laboratory-scale argon atmosphere facility for molten salt electrorefining process studies is operational. Using this facility, studies on all the unit operations of the process have been carried out on uranium alloys. A code, PRAGAMAN, based on thermochemical modeling has been developed to simulate the electrotransport behavior of elements during the electrorefining process. Based on our studies, the eutectic MgCl₂-NaCl-KCl ternary salt has been proposed as the alternate electrolyte for the conventional 2CsCl-NaCl electrolyte for oxide processing. A facility to demonstrate the remotization of all the process steps of the molten salt electrorefining process flow sheet for metallic fuels at 1- to 3-kg scale is being set up. Basic electrochemical studies on the reduction behavior of the chlorides and oxychlorides of uranium and the lanthanides in molten salts have also been carried out. This paper describes the studies carried out so far and the plans for the near future.