A year ago, a massive earthquake triggered a tsunami that nearly destroyed Japan’s Fukushima Daiichi nuclear power plant and further frightened people who had been wary of nuclear power since the Three Mile Island accidents in 1979 and Chernobyl in 1986.
But a small group of scholars, entrepreneurs, and advocates see the post-Fukushima era as the perfect opportunity to get the United States to ponder a proposal it has made unsuccessfully for years. What about a new fuel and maybe a new type of reactor?
The proposed fuel is thorium, an abundant silver-gray element named after the Norse god of thunder. It’s less radioactive than the uranium that has always powered US facilities, and proponents say that not only does it produce less waste, but it is more difficult to turn into nuclear weapons.
They are driving the idea of adapting plants to use thorium as fuel or replacing them with a completely new type of reactor called a liquid fluoride thorium reactor, or LFTR (pronounced “lifter”). The LFTR would use a mixture of molten chemical salts to cool the reactor and transfer energy from the fission reaction to a turbine.
Proponents say such a system would be more efficient and safer than existing facilities that use pressurized water to cool uranium fuel rods and boiling water or steam to transfer the energy they create.
“A molten salt reactor is not a pressure reactor,” said John Kutsch, director of the Thorium Energy Alliance, a trading group based in Harvard, Ill. Possible hydrogen explosion like you did in Fukushima. “
Kutsch and others say that a thorium powered reactor burns hotter than uranium reactors and uses more fuel. “Ninety-nine percent of the thorium is burned,” he said. “Instead of 10,000 pounds of waste, you’d have 300 pounds of waste.”
“Small shiploads of fanatics”
Although the idea of thorium power has been around for decades – and some countries are planning to build thorium-powered plants – it has not caught on either with the companies that design and build nuclear power plants in the United States, or with the national research laboratories commissioned to investigate future energy sources .
“There are small shiploads of fanatics on thorium who fail to see the drawbacks,” said Dan Ingersoll, senior project manager for nuclear technology at Oak Ridge National Laboratory in Tennessee. On the one hand, it is too expensive to replace or convert the nuclear power plants already in operation in this country: “A thorium-based fuel cycle has some advantages, but is not essential for infrastructure and investments.”
He also pointed out that thorium would still have some radioactive by-products – just not as much as uranium and not as long-lived – and that there is no ready-made supply of thorium in the United States. It would have to be dismantled.
Overall, the benefits do not outweigh the enormous cost of converting technologies. “I’m looking for something convincing enough to destroy billions of dollars of infrastructure that we already have, and I don’t see it.”
Thorium proponents like Kirk Sorensen, a former NASA engineer who is now the managing director of Flibe Energy in Huntsville, Ala., Won’t be put off.
“We recognize that this is a new and different technology and its evolution is very different from the existing nuclear industry,” said Sorensen. “Part of the problem is that nuclear power means only one thing in public, and [U.S.] Government spirit. “
Thorium occurs in the soil as thorium oxide and, according to a report by the International Atomic Energy Agency in 2005, is three to four times as common worldwide as uranium. Thorium is less radioactive than uranium and emits alpha particles that are less biologically harmful than uranium’s gamma particles. This makes the safe storage of thorium easier.
With an extremely high melting point (over 6,000 degrees), thorium has been used in portable gas lanterns, high temperature ceramic products, and aerospace applications. However, due to its radioactivity and the development of alternative materials, most uses of the element have been discontinued.
Once a work experiment
Half a century ago, however, the United States took a serious look at thorium as a nuclear fuel. It was used in a molten salt reactor that government scientists built and operated at Oak Ridge from 1965 to 1969.
After India detonated an atomic bomb in 1974 using plutonium extracted from a reactor designed for use without weapons, fears of proliferation convinced successive US governments to curtail experimental nuclear programs. The thorium fuel project has been largely forgotten. Instead, all subsequent nuclear power plants were designed to use uranium, the fuel that powers all 104 reactors operating in the United States today.
Almost all US plants are at least 25 years old; Some are approaching 50. With the federal government unable to set up a permanent landfill, each reactor site piles up spent fuel rods that have remained radioactive for thousands of years.
Even so, utilities have been preparing to build 20 to 30 similar reactors to replace the older ones. (Earlier this month, the Nuclear Regulatory Commission approved the Atlanta-based Southern Co.’s proposal to build two such reactors in Georgia.)
For the past few years, Sorensen has tried to convince them to build LFTRs instead. He publishes technical papers from the Oak Ridge thorium reactor on his blog, Energy from Thorium. Last year he quit his job at Teledyne Brown Engineering to start Flibe, whose name is derived from the mixture of fluoride, lithium and beryllium salts used in an LFTR.
“We can look back on Oak Ridge,” he says, “to rebuild the capabilities that existed in 1974.”
According to Sorensen, an LFTR that uses a mixture of thorium as fuel and either uranium or plutonium to start the reaction could produce higher core temperatures at lower pressures than steam reactors, meaning that it would not require as many safety and cooling systems.
Even better, he says, LFTRs could be configured to consume the spent fuel that is at nuclear sites across the country.
Other entrepreneurs go a different way. McLean’s Lightbridge plans to mix thorium and uranium to slightly boost the performance of existing nuclear power plants. Lightbridge is helping the Russian government set up such a program, said Seth Grae, president and chief executive officer of the company.
Most US nuclear industry executives, however, are wary of either approach to thorium, saying that neither utility nor investor are out to bet on an unknown technology.
“Customers tell us: ‘Let’s focus on taking [financial] Risk off the table, don’t put it back on, ”said Chris Mowry, President and CEO of Babcock & Wilcox, a Lynchburg-based company that builds smaller reactors that run on uranium. “We see [thorium] than something that’s down the street. It’s more like the science project phase. “
Military applications
In a search for non-petroleum-based energy sources, the Pentagon’s Advanced Defense Research Project Agency (DARPA) announced in 2010 that it would propose a plan to produce jet fuel and electricity from small mobile nuclear power plants. Sorensen says he spoke to Pentagon officials about the use of thorium for such reactors in hostile areas. Since thorium is less adaptable for weapons purposes, the reactor would be safe enough to be left behind for civilian use when US troops withdraw.
“Thorium would potentially provide a way to address this security challenge if we were to convince ourselves to build nuclear power plants in these locations,” said Col. Paul E. Roege, chief of the Army’s operational power cell at the Pentagon.
Roege said the Pentagon is considering the pros and cons of thorium. One downside, he said, is that the engineers aren’t familiar with it. “We have a lot of uranium reactors, people are comfortable with them, and we have mature technology,” said Roege. “That is not the case with thorium reactors.”
Ingersoll, the Oak Ridge scientist who is skeptical of thorium as a new fuel, agreed that it is virtually impossible to use to make a nuclear weapon. However, he warned that the material is still radioactive: “It won’t remove that [nuclear waste] Product. It’s just not that bad. ”
Ingersoll said thorium-fueled reactors make more sense for countries lacking access to the United States’ plentiful uranium reserves.
Chinese government officials announced in February 2011 that they were developing a thorium-based reactor and would be commissioning it over the next 15 or 20 years. India has plans to use thorium in some of its existing reactors.
Kutsch argues that the United States could lose the development of an important technology. He has urged members of Congress to introduce laws that would classify thorium as a special industrial material rather than a nuclear material. “Our legislation would say that thorium is not like uranium and plutonium,” he said. “It can be safely and handled and stored like ammonia or fertilizer.”
Kutsch is also pushing for another bill to instruct the Nuclear Regulatory Commission to develop rules for the use of thorium. This would give US companies the opportunity to use thorium in existing reactors.
Illinois Republican John Shimkus, chairman of a subcommittee that oversees nuclear waste management, says he will enact thorium legislation this year.
“For those who hate that [problem of] Nuclear waste at a high level, ”said Shimkus in a telephone interview,“ Thorium is a great answer. “
Niiler is a freelance writer and lives in Chevy Chase.
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