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By Shane Lasley
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UK group promotes different nuclear fuel

Rocket scientist, environmental campaigners champion the REE-associated metal, thorium, as a greener, safer alternative to uranium

 

Last updated 9/25/2011 at Noon



Could thorium oust uranium as the fuel of choice for nuclear power plants in a post-Fukushima era? Nuclear experts and environmental leaders alike are touting the metal commonly associated with rare earth elements as a safer, more abundant and environmentally friendlier alternative to its infamous cousin.

According to the World Nuclear Association, "Thorium continues to be a tantalizing possibility for use in nuclear power reactors; though for many years India has been the only sponsor of major research efforts to use it."

The Weinberg Foundation - a nonprofit organization that made its debut at the United Kingdom House of Lords Sept. 8 - aims to thrust the silvery-white metal that derives its name from the Norse gold of thunder into the limelight.

The group - which takes its name from the late Alvin Weinberg, the nuclear physicist who pioneered liquid-fueled thorium energy while leading the Oak Ridge National Laboratory during the 1950s and 1960s - is championing thorium as a game-changer in safe, carbon-free power generation.

Baroness Katherine Worthington, environmental campaigner and patron of the Weinberg Foundation said, "The world desperately needs sustainable, low-carbon energy to address climate change, while lifting people out of poverty. Thorium-based reactors, such as those designed by the late Alvin Weinberg, could radically change perceptions of nuclear power leading to widespread deployment."

Thorium-fueled nuclear energy is not embraced by all members of the environmental community. Many who see renewable energy as the low-carbon answer to global power needs say the technology has not been commercially proven and only serves as a distraction from the dangers of nuclear energy as a whole.

During his tenure at Oak Ridge, Weinberg oversaw a five-year trial operation of a 7.4-megawatt liquid-thorium-fueled test reactor. Though the experiment was considered a success, the prototype was powered down in 1969 and the technology was largely forgotten until a recent resurgence of interest in India.

Passive safety

The Weinberg Foundation and a supporting group of scientists say liquid-fluoride thorium reactors, based on the technology developed at Oak Ridge, hold several safety and environmental advantages over conventional nuclear power plants fueled with uranium.

In the aftermath of the March meltdown at the Fukushima nuclear facility in Japan, the inherent safety features of LFTRs could be what gains thorium credence as a legitimate alternative to the conventional nuclear fuel.

Experts say LFTRs have several attributes that would prevent harmful and potentially devastating nuclear accidents like those experienced at Three-Mile Island in the United States, Chernobyl in Russia and Fukushima.

One of the key advantages of LFTRs is that they operate at near-atmospheric pressure, so they are not prone to the hydrogen blowouts seen during past nuclear power plant disasters. But a passive safety mechanism could be the most important attribute of the LFTR design.

Unlike uranium rods that fuel conventional reactors, thorium fuel is a liquid. A plug at the bottom of the reactor is kept frozen while the plant is operating. If the facility overheats or shuts down, the plug thaws and the liquid salt thorium fuel drains into an underground storage tank.

"There is no need for computers, or the sort of electrical pumps that were crippled by the tsunami. The reactor saves itself," explains Kirk Sorenson, a nuclear and aerospace engineer who has worked for both NASA and Teledyne Brown Engineering.

Sorenson's interest in thorium-fueled reactors is not purely academic. He is co-founder and president of Flibe Energy, a company formed to design, build and operate LFTRs.

Other attributes being promoted by LFTR advocates: The technology is scalable, and waste from thorium plants is "orders of magnitude" less than the amounts produced by uranium-fueled reactors. Moreover, thorium-powered plants are particularly well-suited for operating in tandem with water desalination facilities.

Found abundantly with REEs

Thorium, which is four times as common as uranium in the earth's crust, has the added advantage of being plentiful.

The U.S. Geological Survey estimates current world reserves of thorium to be around 1.3 million metric tons. About 440,000 metric tons included in the agency's reserve estimate are found in the United States. India and Australia, at about 300,000 tons each, hold the bulk of the remaining reserves.

According to Flibe Energy, thorium is so energy-dense it would only take 6,600 metric tons of the metal to replace the combined 5.3 billion metric tons of coal, 31.1 billion barrels of oil, 2.92 trillion cubic meters of natural gas, and 65,000 metric tons of uranium that the world consumes annually.

The USGS said past thorium production in the United States was a byproduct of REE mining, but no thorium has been produced in the country in recent years.

"Reserves are contained primarily in the rare-earth ore mineral monazite and the thorium mineral thorite. Without demand for the rare earths, monazite would probably not be recovered for its thorium content. Other ore minerals with higher thorium contents, such as thorite, would be more likely sources if demand significantly increased. New demand is possible with the development and testing of thorium nuclear fuel in Russia and India," the USGS wrote in its 2011 minerals report.

A thriving thorium-fueled global nuclear program could bode well for mining companies pondering what to do with this moderately radioactive byproduct of rare earth element mining.

"Domestic mine production of thorium-bearing monazite ceased at the end of 1994 as world demand for ores containing naturally occurring radioactive thorium declined," the USGS reported. "It is likely that thorium's use will continue to decline unless a low-cost disposal process is developed or new technology, such as a non-proliferative nuclear fuel, creates renewed demand."

No plutonium

So, if thorium is a proven, safer, more abundant and environmentally friendlier alternative to uranium, then why is the latter element the fuel of choice for today's nuclear reactors? The Weinberg Foundation contends the answer lies in yet another benefit of LFTR technology.

Unlike thorium-reactors, uranium-fueled power plants produce weapons-grade plutonium. This nuclear-chain-reaction producing element was an important by-product to the nuclear powerhouses of the Cold War era.

"Despite its many benefits, U.S. policy at the time was not focused on nuclear safety or reduction of waste, but rather on maximizing plutonium production. Since the thorium technology did not produce plutonium, its funding was withdrawn and development stalled," the Weinberg Foundation said in a written statement.

Chalking nuclear proliferation resistance on the list of benefits, the Weinberg Foundation has set out to share its vision of a greener, cleaner and safer world fueled by thorium.

"The abundance, safety and proliferation-resistance of thorium, utilized in proven reactor platforms, presents real hope for a viable and peaceful solution to our global energy needs - from desalination in desperately arid regions to lighting our homes and cities," said Weinberg Foundation co-founder and environmental philanthropist John Durham.

 

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