The Hindu : IGCAR to reprocess reactor fuel

Online edition of India's National Newspaper
Tuesday, Feb 11, 2003

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National

IGCAR to reprocess reactor fuel

By R. Prasad

CHENNAI FEB. 10. The Indira Gandhi Centre for Atomic Research (IGCAR) at Kalpakkam is readying itself to reprocess the spent fuel and thus close the fuel cycle. Reprocessing the spent fuel forms the last but an important step in closing the fuel cycle.

This crucial exercise is scheduled to start by the end of this month. The Fast Breeder Test Reactor (FBTR) uses plutonium uranium carbide fuel (30 per cent uranium and 70 per cent plutonium mixed carbide fuel) that was developed indigenously and used for the first time in the world.

Reprocessing the plutonium carbide fuel is a tricky issue compared to oxide fuel that is normally used in fast breeder reactors the world over. For one, the dissolution in nitric acid is difficult and more importantly the dissolution leaves behind organic complexes.

But the IGCAR is optimistic of overcoming the challenges posed by plutonium carbide fuel. Trials conducted in the laboratory with both irradiated and unirradiated fuel have shown complete fuel dissolution in nitric acid. "But it was done in a laboratory. We would like to see how it would perform on industrial scale," said S.B. Bhoje, director, IGCAR. But in all probability, reprocessing on industrial scale may not spring many surprises.

The plan is to start the trial with three subassemblies that have undergone different burn-ups. Each subassembly has 61 pins. "We intend to reprocess ten pins each week to check the parameters required to bring about complete dissolution," he said.

Increasing the concentration of nitric acid or resorting to electro-dissolution are some of the options available to bring about complete dissolution of the spent fuel. Electro-dissolution involves applying certain amount of current to accelerate the dissolution.

It is expected to complete the reprocessing of three subassemblies in three months. Initial parameters such as concentration of nitric acid required, knowing the organic complexes that would be formed and ways of removing them, are expected to be established by this time. Periodical removal of organic complexes is a must lest certain problems crop up during reprocessing.

Regular reprocessing of spent fuel is expected to begin once the trials are completed. "Nobody has done reprocessing of carbide fuel in the world," reminds Mr. Bhoje. It would mark another and a crucial milestone in IGCAR's endeavour.

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