Friday, August 26, 2005

Revolutionary Reactor Design by BARC

Scientists at the Bhabha Atomic Research Centre, Bombay, have designed what they claim is the safest and most economical nuclear reactor in the world. BARC scientists V Jagannathan and Usha Pal revealed the design, which has been in the making for seven years, in their paper presented at the week-long 12th International Conference on Emerging Nuclear Energy Systems (ICENES 2005) in Brussels.

There are some nice and unique things about this reactor. The design presented was for a reactor that can produce, "600 MW of electricity for two years 'with no refuelling and practically no control manoeuvres.'" Most accidents are because of human error. So automation would mean minimal chances of accident - plus reduction in cost. Importantly for India, the reactor does not need uranium, and runs of thorium instead (which India has in plenty). I have doubts about that being an advantage. Though it does not need uranium, it still needs plutonium (800 kg a year), and in comparable quantities to the thorium (1100 kg a year).

The design is called ATBR (A Thorium Breeder Reactor). It uses plutonium as the seed to start the reaction cycle, which then carries on with thorium getting converted to fissionable uranium-233. It is a thorium breeder of sorts (a first with thorium in the world - fast breeding is normally done with plutonium), so it produces as much fissile material as it depletes, extending a single cycle over a period of two years. Thus the minimal human interference required.

World reserves of thorium are about three times that of uranium, and India has 32 per cent of the world's thorium. Thus India is rather anxious to start exploiting this huge resource, which incidentally also cannot be used to create nuclear weapons.

India has a so-called "three-stage nuclear program". In the first stage, plutonium is created in its pressurized heavy water reactors (PHWRs) and extracted by reprocessing. In the second stage, fast breeder reactors (FBRs) use this plutonium in 70-percent MOX-fuel to breed uranium-233 in a thorium blanket around the core. In the final stage, the FBR's use thorium-232 and produce uranium-233 for other reactors.

The first stage has been realized with India's 10 nuclear power plants. The second stage is only realized by a small experimental fast breeder reactor (13 MW), at Kalpakkam.