Dec 29 2009

Thorium: The Nuclear Alternative

Posted by: Jonathan Marshall

We've all heard the litany of complaints from opponents of nuclear power: it creates long-lived radioactive waste; the fuel cycle produces plutonium that could be diverted to nuclear weapons; and runaway nuclear reactions might cause reactor meltdowns, endangering the public.

The nuclear industry has good answers to each of these claims, but the best answer may someday be to reinvent nuclear power altogether.

To wit: substitute a relatively abundant, silvery-white element called thorium for uranium and plutonium in commercial reactors.

Thorium-based reactors, like those using uranium or plutonium, work on the principle of nuclear fission. Thorium absorbs neutrons to create uranium 233, whose nuclei are then split to release energy that can be harnessed by steam generators to produce electric power.

Experiments at Oak Ridge National Laboratory in the 1960s and 1970s proved that thorium could work as a fuel, but industry saw no need to introduce new designs when uranium reactors worked well enough.

In principle, say boosters of the rival element,

thorium could solve the nuclear power industry's most intractable problems. After it has been used as fuel for power plants, the element leaves behind minuscule amounts of waste. And that waste needs to be stored for only a few hundred years, not a few hundred thousand like other nuclear byproducts. Because it's so plentiful in nature, it's virtually inexhaustible. It's also one of only a few substances that acts as a thermal breeder, in theory creating enough new fuel as it breaks down to sustain a high-temperature chain reaction indefinitely. And it would be virtually impossible for the byproducts of a thorium reactor to be used by terrorists or anyone else to make nuclear weapons.

In addition, proponents say thorium-based reactors can be designed to regulate their output to eliminate the risk of a meltdown.

Interest in thorium is growing worldwide. India is working on a thorium-based reactor design that may be ready within a couple of years. China also hopes to exploit domestic reserves of thorium to reduce its nuclear industry's dependence on imported uranium. An expert panel formed by the China National Nuclear Corporation has reportedly selected a Canadian reactor design as the most promising way to shift to a thorium fuel cycle. 

A public U.S. company called Lightbridge Corp. is working with nuclear designers in France and Russia to produce thorium-based fuel rods that could replace uranium in some commercial reactors by 2017.

Finally, further research on the prospects of thorium has been championed--so far unsuccessfully--by an unusual pair of bipartisan sponsors in the Senate: Orrin Hatch of Utah and Harry Reid of Nevada.

"With the growing interest in thorium nuclear power in the world and in the U.S.," Hatch said when introducing the Thorium Energy Independence and Security Act of 2008 last fall, "it's time we made sure our government has a regulatory infrastructure in place to accommodate this new generation of nuclear power."

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