A Cheaper, Safer Sort of Nuclear Power
The case for thorium.
SuperFuel: Thorium, the Green Energy Source for the Future, by Richard Martin, Palgrave MacMillan, 240 pages, $27.
Suppose—just suppose—that there were a tested energy technology out there that
• produces electricity cheaper than coal, because of lower capital and fuel costs,
• uses a fuel that is in almost inexhaustible supply, both in the U.S. and elsewhere,
• operates continuously, in baseload or peaking mode, for up to 30 years,
• operates at an efficient high temperature but at atmospheric pressure,
• can be factory-built and deployed in compact 100-megawatt modules close to the end use of the power,
• contributes nothing to air or water pollution and needs no water for operation,
• safely consumes long-lived transuranic waste products from current nuclear fission reactors,
• produces high-temperature process heat that can make hydrogen fuel for vehicles, and
• is walkaway safe.
Science journalist Richard Martin's book SuperFuel makes the case that such a technology exists. It's thorium, and particularly the LFTR—the liquid fluoride thorium reactor.
All 104 units of the U.S. reactor fleet, plus all of its naval nuclear fleet, are comprised of light water reactors using low-enriched uranium. (Around 4 percent of the uranium fuel is the fissionable U235.) These reactors transfer the fission heat of nuclear fuel into water and then high-pressure steam, which eventually turns turbines that turn generators that produce electricity.
These conventional reactors have gotten larger over the years—up to 1,700 megawatts—to attain capital cost efficiency. They generate power inside large steel and concrete containment vessels to contain any accidents. There are several other varieties of nuclear reactors: high temperature gas cooled (China's HTR-10, Germany's THTR), heavy water and natural uranium (Canada's CANDU), graphite moderated bomb factories (Chernobyl), and the fast breeder (Russia's BR600, France's Superphenix).
In the 1960s, Oak Ridge National Laboratory pioneered the idea of the thorium reactor. If you bombard the plentiful and slightly radioactive heavy metal thorium 232 with neutrons, you convert it to fissionable uranium 233. Instead of water, the LFTR circulates the thorium tetrafluoride fuel through the reactor core dissolved in molten lithium and beryllium fluoride salts. A small amount of U235—or later, U233—supplies the neutrons that cause fission. Excess neutrons fly off into a surrounding blanket of molten thorium salt to convert more thorium into new U233 fuel, which can then be used to keep the reaction going. Because the molten salt expands when heated, it is inherently safe: The lower density fuel won't support a continuing nuclear reaction.
Every stage of this process—fuel loading, neutron management, fuel separation, heat exchange, refueling, and waste separation—has been successfully tested in actual reactors, although not in an optimum commercial-scale configuration.
So why aren't we doing it? To answer that, Martin details the long battle between the demanding and acerbic Admiral Hyman Rickover, who wanted nuclear engines based on known technology right now to propel his fleet of submarines, and the gentle visionary Alvin Weinberg, longtime director of Oak Ridge National Laboratory, who envisioned a fleet of safe and affordable thorium-powered electric plants. Rickover, a savage bureaucratic infighter, got what he wanted, and Weinberg got fired. The industry put its muscle behind the hugely expensive liquid metal fast breeder reactor. It in turn was shelved in 1984 after Congress spent $8 billion on the Clinch River Breeder without turning a shovelful of dirt.
As Martin puts it, "Light water reactors and their younger cousin, the liquid metal breeder, won out because of technological intransigence rooted in the military origins of the U.S. nuclear program."
From 1965 to 1969, Weinberg's molten salt reactor experiment had operated successfully, in the later months with thorium-derived U233 fuel. By 1973, Weinberg was gone, molten salt was rejected, and thorium was dead. Rickover's uranium-based industrial empire was preserved, as Westinghouse and other companies built the admiral's naval reactors; the cheaper, safer alternative was shelved.
A man with all the capital in the world couldn't crack into the U.S. nuclear power market: Since it involves uranium, the government stands adamantly in the way, arm in arm with the interests committed to defeating any challenge from disruptive technology. (Nuclear Regulatory Commission approval of a new reactor type typically takes up to 10 years.) That's why Martin believes the LFTR or a variant is more likely to be developed and eventually marketed by China, Russia, India, France, Canada, or even the Czech Republic, all of which are actively pursuing the idea.
Is the LFTR just another fantasy? Weinberg's R&D program solved the major technical problems over 40 years ago. There are several unsolved but not insuperable issues: getting the neutron-eating lithium 6 out of the lithium salt, separating certain fission product salts from the molten salt carrier, and managing small amounts of gaseous tritium. And of course, it will take a lot of engineering to put all the pieces together into one efficient, factory-built 100 Mw modular plant sized to supply, say, Terre Haute, Indiana. It remains to be seen how hard it will be to get such a plant insured, but LFTRs are inherently far safer than light water reactors. If one obtains a Nuclear Regulatory Commission license as a certification of safety, insurers ought to accept it—but there will terrific pressure from the established industry to drag out that certification for as long as possible.
Martin's book is a good read, but when he proposes the steps he thinks are needed to bring his "superfuel" into widespread use, he just comes up with more industrial policy. He wants the government that snuffed out thorium and molten salt reactors four decades ago to subsidize them back into existence, perhaps (one might conjecture) making use of the now vacant Solyndra factory. Maybe the government ought to just get out of the way? If thorium is the Next Big Energy Thing, let its advocates prove it—as soon as Washington stops protecting anachronistic technologies and the companies that sell them, and lets new ideas and talent bring us into a brighter energy future.