US firm offers India thorium reactors

By K.S. Jayaraman, IANS

Bangalore : While India is still debating how to make the Indo-US nuclear deal work, an American company, anxious to enter the Indian market, has offered to build commercial nuclear power reactors in the country.

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These reactors will rely entirely on India’s thorium resources — except at the start – and thereby remove the objections of critics.

The California-based Dauvergne Brothers Inc (DBI) says its novel type of thorium breeder reactor is fuelled with fissile material like uranium only once when it is started. It runs for its full operational life on Uranium-233 (or U-233) bred in its core from thorium.

Thorium, which India has in plenty, cannot be directly burned in a reactor. It has to be converted into fissile U-233. India’s own thorium utilisation strategy hinges on reprocessing — a contentious issue between India and the US. The DBI claims its design is tailor-made for the Indian situation.

According to the company, its reactor “starts up using conventional uranium-based nuclear fuels, and incrementally converts to an all-thorium fuel cycle over a period of 10 years, using India’s abundant supply of thorium ores to maintain energy independence”.

It said that computer simulations of the DBI thorium breeder reactor show that a single load of 25 percent uranium oxide fuel and 75 percent thorium oxide will keep the reactor running for a decade.

“In that time enough U-233 will be bred in the thorium oxide fuel to increase the output power of the DBI reactor core by 50 percent adding only fresh thorium oxide as fuel.” After that, no uranium ores are needed.

Conventional breeder reactor designs — including the one contemplated by Indian scientists — require chemical reprocessing to retrieve bred fuel from used uranium fuel rods or from irradiated thorium” blankets”.

The DBI reactor, according to the company, uses a different strategy.

After approximately 10 years of operation, much of the activated thorium fuel would be transferred without any reprocessing into a second-generation DBI reactor core with higher power output than the first.

“Fresh thorium breeder bundles will be added to perpetuate the cycle.”

This fuel plan relies on a robust, low-neutron absorbing, radiation-resistant, proprietary fuel encapsulation system developed by DBI, the company said.

Unlike the zirconium fuel cladding of most breeder reactors, the DBI fuel capsules are derived from industrially available material, much less expensive than nuclear-grade zirconium alloys.

While the modular core design offers scalability, several other features of the DBI thorium reactor programme could prevent weapons proliferation, the company claims.

For instance, it says the start up fuel could be a proliferation-resistant fuel, such as the denatured plutonium/thorium fuel recently developed by Thorium Power Inc, another US company.

“International agreements between India and uranium-source nations to use proliferation-resistant fuels in the DBI Reactor Programme, subject to IAEA monitoring, could sever the link between civilian and military nuclear programmes in India, without adversely affecting India’s ability to scale up the DBI Reactor Programme using native thorium in future generations,” the company said.