By David Lague
HONG KONG (Reuters) - China isn't alone in turning to thorium as a potential source of power. Enthusiasm for exploiting this alternative to uranium is on the rise across the world, even as the cleanup continues from the Fukushima nuclear accident in Japan.
A new generation of scientists and nuclear engineers argue that thorium could be the key to realizing a dream of safe, cheap and plentiful nuclear power for an energy hungry world.
Thorium deposits, estimated to be about four times more abundant than uranium, are widely distributed: Substantial reserves have been found in China, Australia, the United States, Turkey, India, and Norway. About 6,600 metric tons (7.75.3 tons) of thorium used to power the most efficient proposed reactors would provide enough energy to replace all of the fossil fuels and nuclear energy consumed globally each year, proponents say.
Uranium-poor India has a long-term research effort under way and has decided thorium will become the mainstay of its nuclear energy industry later this century. The French government has a research program. Companies in the United States, Australia, Norway and the Czech Republic are working on reactor designs or thorium fuel technology.
Energy from thorium is not just scientific theory. On April 25, Thor Energy, a private Norwegian company, began producing power from thorium - named after the Norse god of thunder - at the Halden test reactor in Norway.
"It is the fundamental first step in the thorium evolution," says company CEO Oystein Asphjell. The tests are aimed at showing the fuel could be a valuable alternative to uranium for existing reactor operators. Nuclear giant Westinghouse, a unit of Toshiba Corp, is part of an international consortium that Thor Energy established to fund and manage the experiments.
Thorium is a shiny, slightly radioactive metal. In its natural form, thorium isn't fissile - meaning that, in contrast to uranium, it can't split to sustain a nuclear chain reaction.
But if thorium is bombarded with neutrons from a small amount of fissile nuclear fuel acting as a starter, either uranium-235 or plutonium-239, it is converted to uranium-233 - a form of uranium that is a first-rate nuclear fuel. Once started in a reactor, the process is self-sustaining, with subsequent fissions of uranium-233 in turn converting more thorium to nuclear fuel.
Also, because most of the fuel is consumed, thorium yields little waste and is much less radioactive, proponents say. Most of the residue will become inert within 30 years, with about 17 per cent needing secure storage for about 300 years.
The most dangerous waste from current generation reactors requires storage for 10,000 years.
The molten-salt reactor may have one further benefit. Some advocates believe they can be used to burn off existing nuclear waste.
A privately owned U.S. start-up, Transatomic Power of Cambridge, Massachusetts, says it plans to build molten salt cooled reactors to burn some of the 270,000 metric tons of nuclear waste accumulated worldwide. "There is enough waste just in the U.S. to power the country for a century," says Russ Wilcox, company CEO and co-founder.
Thorium and the dream of clean nuclear power
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