Nuclear Energy Insight Winter 2012
—Officials in India are ready to build a large-scale prototype of a reactor fueled by a combination of thorium and low-enriched uranium.
Ratan Kumar Sinha, chairman of the Bhabha Atomic Research Center in Mumbai, recently told the U.K.’s Guardian newspaper, “The basic physics and engineering of the thorium-fueled Advanced Heavy Water Reactor are in place, and the design is ready.” He said the Indian government has begun a six-month search for a site for the 300-megawatt reactor while conducting confirmatory tests on the final design.
India’s Advanced Heavy Water Reactor design would use the country’s abundant thorium supply. Sinha said the reactor could be operational by the end of the decade.
One of the three elements widely considered to be useful in the generation of nuclear energy, thorium is three to four times more plentiful than uranium and is widely distributed in nature. India has one of the world’s largest thorium deposits.
The element cannot be used alone in a reactor because it cannot split apart to release energy. However, it can be converted inside a reactor into the fissile isotope uranium-233 when used with other fissile material such as uranium-235 or plutonium-239.
Only a relatively small amount of uranium or plutonium is needed to convert thorium to uranium, because the thorium will continue to create more fuel during normal operation in the reactor.
The Indian plant will demonstrate the use of low-enriched uranium, which is readily available on the world market, to breed fuel from thorium. Previous thorium-based nuclear facilities used high-enriched uranium or plutonium to convert thorium. Low-enriched uranium carries a much smaller proliferation risk.
Additionally, the used fuel from thorium reactors also mitigates proliferation concerns because it includes fewer radioactive byproducts than uranium.
Scientists and engineers have long been interested in developing nuclear reactor technology based on thorium. In the 1960s and 1970s, thorium-based research reactors operated in the United States, Germany and the Soviet Union. U.S. reactors in Pennsylvania (Peach Bottom and Shippingport) and Colorado (Fort St. Vrain) have used thorium.
The thorium is placed within and around the reactor core, where it absorbs neutrons from the fission chain reaction and becomes uranium-233. The uranium is either extracted and manufactured separately into fuel or used directly within the same reactor.
India is not the only developing nation interested in thorium fuel and reactor technology. In January, China announced it was commencing research and development of a thorium-fueled molten-salt reactor design.
—Read more articles in Nuclear Energy Insight and Insight Web Extra.