Editorial: Succeeding against all odds
Published in The Hindu on June 14, 2005
By successfully reprocessing the mixed carbide fuel used in the Fast Breeder Test Reactor (FBTR), which has undergone 100,000 MW day/tonne burn-up, the Indira Gandhi Centre for Atomic Research at Kalpakkam has crossed a major milestone. About 12 per cent of the total uranium and plutonium present in the fuel undergoes fission in the FBTR for 100,000 MW day/tonne burn-up. Reprocessing the spent fuel plays a crucial role in closing the fuel cycle. This is an imperative for a sustained growth of the nuclear power industry, given the limited availability of natural uranium in India. Utilisation of natural uranium can be increased to 70-80 per cent in fast breeder reactors when the reprocessed fuel is reused. Also, effective reprocessing of spent fuel minimises the quantity of nuclear waste to be vitrified for safe storage. Reprocessing mixed carbide fuel has been a major challenge. The mixed carbide fuel — 30 per cent uranium carbide and 70 per cent plutonium carbide — used in the FBTR is the first of its kind in the world and there exists no literature on reprocessing it. By any standards, the successful reprocessing of this fuel is a commendable achievement, testimony to the capability of Indian nuclear scientists working against the odds.
If reprocessing carbide fuel is a daunting task, doing it on a fuel that has undergone 100,000 MW day/tonne burn-up makes it all the more challenging. As the burn-up — the cumulative amount of energy that can be extracted per unit mass of fuel — increases, the number of fission products shoots up and the difficulty at every stage of reprocessing increases. The pyrophoric nature of the fuel makes reprocessing specially difficult. This is the first time a fuel containing 70 per cent plutonium burned to 100,000 MW day/tonne has been reprocessed. Again, the waste stream containing plutonium requires close control within prescribed limits and the IGCAR could achieve it. It has now embarked on reprocessing a second batch of fuel that has undergone 100,000 MW day/tonne burn-up. While the reprocessing procedure has been optimised, the focus will be on optimising the time taken. Refabricating the reprocessed fuel, vital for closing the fuel cycle, is a task that lies ahead and it is seen as less challenging, since the radioactivity and impurities in the reprocessed fuel have already been brought within the prescribed limits. Having reprocessed a difficult fuel, reprocessing mixed oxide — 20-30 per cent plutonium oxide and 70-80 per cent uranium oxide — the fuel to be used in the proposed 500 MW Fast Breeder Reactor at Kalpakkam, will be less daunting. It is noteworthy that the IGCAR intends to take up reprocessing of mixed oxide fuel that has undergone 100,000 MW day/tonne burn-up years before the 500 MW Fast Breeder Reactor goes critical. The test mixed oxide fuel in the FBTR has already undergone 50,000 MW day/tonne burn-up.
