Thorium, named for the Norse god of thunder, is much more abundant than uranium and has 200 times that metal's energy potential. Thorium is also a more efficient fuel source -- unlike natural uranium, which must be highly refined before it can be used in nuclear reactors, all thorium is potentially usable as fuel. It is so abundant that it's almost an annoyance. Thorium is considered a waste product when mining for rare-earth metals.
|Thorium-fueled MSR reactor, |
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The Telegraph says Obama needs a Roosevelt moment, recalling the famous breakfast meeting when Albert Einstein convinced the president to start the Manhattan Project. A thorium stimulus could be just what the lagging economy needs.
(Summarized from Rebecca Boyle, Development of Tiny Thorium Reactors Could Wean the World Off Oil In Just Five Years, Popular Science, August 2010)
Newer nuclear reactor designs, collectively called Generation IV, include the thorium-powered molten-salt reactor (MSR). In an MSR, liquid thorium would replace the solid uranium fuel used in today’s plants, a change that would make meltdowns all but impossible.
MSRs were developed at Tennessee’s Oak Ridge National Laboratory in the early 1960s and ran for a total of 22,000 hours between 1965 and 1969. “It was not a full system, but it showed you could successfully design and operate a molten-salt reactor,” says Oak Ridge physicist Jess Gehin, a senior program manager in the lab’s Nuclear Technology Programs office.
The MSR design has two primary safety advantages. Its liquid fuel remains at much lower pressures than the solid fuel in light-water plants. This greatly decreases the likelihood of an accident, such as the hydrogen explosions that occurred at Fukushima. Further, in the event of a power outage, a frozen salt plug within the reactor melts and the liquid fuel passively drains into tanks where it solidifes, stopping the fission reaction. “The molten-salt reactor is walk-away safe,” Kutsch says. “If you just abandoned it, it had no power, and the end of the world came--a comet hit Earth--it would cool down and solidify by itself.”
Because of this efficiency, a thorium MSR would produce far less waste than today’s plants. Uranium-based waste will remain hazardous for tens of thousands of years. With thorium, it’s more like a few hundred. As well, raw thorium is not fissile in and of itself, so it is not easily weaponized. “It can’t be used as a bomb,” Kutsch says. “You could have 1,000 pounds in your basement, and nothing would happen.”
| One ton of thorium: as much energy |
as 200 tons of uranium
Even with military and corporate support, the transition to a new type of nuclear power generation is likely to be slow, at least in the U.S. Light-water reactors are already established, and no regulations exist to govern other reactor designs. Outside the U.S., the transition could come more quickly.
In January 2011 the Chinese government launched a thorium reactor program. “The Chinese Academy of Sciences has approved development of an MSR with relatively near-term deployment--maybe 10 years,” says Gehin, who thinks the Chinese decision may increase work on the technology worldwide. Even after Fukushima, “there’s still interest in advanced nuclear,” he says. “I don’t see that changing.”
(Summarized from Kalee Thompson, Concepts & Prototypes: Two Next-Gen Nukes, Popular Science, July 2011)
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