Since these reactors have to be inducted in large numbers in shortest possible time, the spent fuel is to be reprocessed as quickly as possible.
In Fast Breeder Reactors, there is an increase in plutonium content while uranium is consumed. The irradiated fuel is reprocessed for recovering Uranium and Plutonium for reuse in the reactor.
In the Fuel Reprocessing Plant, the fuel pins are dismantled from the subassembly. These pins are then chopped and dissolved in nitric acid. Solvent extraction process with tributyl phosphate as solvent, is used to separate Uranium, Plutonium and fission products.
A very large fraction of the radioactive fission products and long-lived radioactive elements are fixed in suitable solid matrices such as glass and disposed and monitored in deep geological repositories. A tiny fraction gets released along with the gaseous and liquid effluents from the reprocessing plants, which is controlled and maintained as per the stringent regulatory requirements.
The Plutonium and the Uranium recovered from the reprocessing plant along with fresh uranium are fabricated as fuel elements in fabrication plant. The refabricated fuel is used in the reactor. The fuel cycle is thus closed.