Could thorium reactors provide the next generation of nuclear power?


There were a couple of reports that caught my eye in the Phoenix New Times last week that I have not seen reported elsewhere. First, AZ Senate Committee Says Nuclear Power Is a Renewable Energy Resource:

pvngs01The Senate Committee on Water and Energy narrowly passed SB 1134, a bill that classifies “nuclear energy from sources fueled by uranium fuel rods that include 80 percent or more of recycled nuclear fuel and natural thorium reactor resources under development” to be a renewable-energy source.

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As it stands now, the Arizona Administrative Code R14-2-1801 says nuclear and fossil fuels are not renewable resources. But Senator Steve Smith, a Republican from District 23, and the main sponsor of SB 1134, would like that to be changed.

Sen. Smith’s predecessor, Sen. Cap’n Al Melvin, was the guy who carried nuclear energy bills in the past, so it looks like Smith is stepping into his role. Not much of a difference: “When it comes to nuclear materials, Smith said,”we have so much that can be reused that it’s almost renewable!” Wow.

The second report is far more interesting. Renewable Energy Not Enough: Scientists Want More Nuclear Plants to Curb Climate Change:

Scientists say there’s a critical need to build more nuclear power plants.

In its new survey, Pew pitted the beliefs of random U.S. citizens against “a representative sample of scientists connected to the American Association for the Advancement of Science.” The scientists want to see less offshore drilling than does the general public, no doubt because they’re concerned about the local and global impact and better understand the risks to the environment of that activity.

At the same time, 65 percent of the scientists polled want to see more nuclear-power plants built, compared to 45 percent of Americans. This is because scientists have a better understanding of the risks and benefits of nuclear energy, and they know that when it comes to fighting the source of climate change, renewable energy isn’t going to cut it.

The poll results come about a year after top climate-change scientists including James Hansen sent an open letter to world leaders pushing for more nuclear energy. A 2013 documentary, “Pandora’s Promise,” discussed the debate over nuclear as a climate-change solution and received a little media attention.

The public’s fear of nuclear energy due to disasters like Chernobyl and Fukushima is already becoming a significant obstacle to avoiding the far-more serious global catastrophe of climate change. For instance, President Obama’s new $4 trillion budget proposal contains some dollars for research and development for a new generation of nuclear plants, but no funds, loans or tax credits to construct any new nuclear plants, according to information we received on Monday week from White House spokesman Keith Maley.

If you heard that wind and solar energy can meet current or future demand for electricity, you’ve been misinformed — probably by the wind and solar lobby.

New Times explained in a 2013 article, “Dim Watt,” why solar energy is unlikely to power more than a fraction of Arizona’s electricity demand in the coming decades despite the state’s large “solar resource.” As we covered in our in-depth story, the factors involved include the high expense and the lack of political will of leaders and residents for endless subsidies. But they also include the relative weakness of solar power, which typically captures less than 25 percent of the sun’s 1,000 watts of power-per-square-meter when the sun is shining.

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By comparison, the Palo Verde Nuclear Generating Station west of Phoenix (pictured above), which consists of three reactors and is the largest nuclear plant in the country, cost $5.9 billion to build (in 1988 — yes, we know it would cost more now), and has a rated capacity of 3,942 megawatts. Like other nuclear plants, it produces more than 90 percent of its rated capacity.

In other words, nuclear plants put out so much more power than solar plants, it’s just silly. And they produce reliable base-load power, not the intermittent power of solar and wind.

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As the Pew poll indicates, scientists believe a less-carbonized modern society can only be achieved by adding more nuclear to the mix. And it needs to be done soon, if not yesterday.

Few people are interested in listening to the scientists.

Even if renewable energy was as good as its proponents say, which it isn’t, raw megawatts of electricity coming online from renewable energy are being added much too slowly to prevent disaster, experts say.

An updated report released last week by the International Energy Agency argues forcefully that the world needs to be building twice as many nuclear plants in order to keep the world from surpassing the dreaded two-degree increase over current average global temperature.

China, India, the Middle East and Russia are on pace to lead the way.

The IEA says . . . “Global installed capacity would need to more than double from current levels of 396 gigawatts (GW) to reach 930 GW in 2050, with nuclear power representing 17% of global electricity production,” the report states. “Although lower than the 2010 Roadmap vision of 1,200 GW and 25% share of generation, this increase still represents a formidable growth for the nuclear industry.”

What I want to focus on is a term buried in the reporting above: “natural thorium reactor.” Most people believe that all nuclear power plants are uranium and plutonium fuel-based, which is where their fear of Chernobyl and Fukushima comes from, and justifiably so. Most people have never heard of thorium reactors, so here’s a cursory Wiki primer on Thorium-based nuclear power:

After World War II, uranium-based nuclear reactors were built to produce electricity. These were similar to the reactor designs that produced material for nuclear weapons. During that period, the U.S. government also built an experimental molten salt reactor using U-233 fuel, the fissile material created by bombarding thorium with neutrons. The reactor, built at Oak Ridge National Laboratory, operated critical for roughly 15000 hours from 1965 to 1969. In 1968, Nobel laureate and discoverer of Plutonium, Glenn Seaborg, publicly announced to the Atomic Energy Commission, of which he was chairman, that the thorium-based reactor had been successfully developed and tested:

So far the molten-salt reactor experiment has operated successfully and has earned a reputation for reliability. I think that some day the world will have commercial power reactors of both the uranium-plutonium and the thorium-uranium fuel cycle type.

In 1973, however, the U.S. government shut down all thorium-related nuclear research—which had by then been ongoing for approximately twenty years at Oak Ridge National Laboratory. The reasons were that uranium breeder reactors were more efficient, the research was proven, and byproducts could be used to make nuclear weapons. In Moir and Teller’s opinion, the decision to stop development of thorium reactors, at least as a backup option, “was an excusable mistake.”

In other words, the Cold War dictated the use of uranium and plutonium reactors for the fissile material to make nuclear bombs. Since then,

After studying the feasibility of using thorium, nuclear scientists Ralph W. Moir and Edward Teller suggested that thorium nuclear research should be restarted after a three-decade shutdown and that a small prototype plant should be built. Research and development of thorium-based nuclear reactors, primarily the liquid fluoride thorium reactor, (LFTR), MSR design, has been or is now being done in India, China, Norway, U.S., Israel and Russia.

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Despite the documented history of thorium nuclear power, many of today’s nuclear experts were nonetheless unaware of it. According to Chemical & Engineering News, “most people—including scientists—have hardly heard of the heavy-metal element and know little about it…,” noting a comment by a conference attendee that “it’s possible to have a Ph.D. in nuclear reactor technology and not know about thorium energy.”

Others, including former NASA scientist and thorium expert Kirk Sorensen, agree that “thorium was the alternative path that was not taken … ” According to Sorensen, during a documentary interview, he states that if the U.S. had not discontinued its research in 1974 it could have “probably achieved energy independence by around 2000.”

The Economist reported last year, Thorium reactors: Asgard’s fire:

Atomic energy is seen by many, and with reason, as the misbegotten stepchild of the world’s atom-bomb programmes: ill begun and badly done. But a clean slate is a wonderful thing. And that might soon be provided by two of the world’s rising industrial powers, India and China, whose demand for energy is leading them to look at the idea of building reactors that run on thorium.

Existing reactors use uranium or plutonium—the stuff of bombs. Uranium reactors need the same fuel-enrichment technology that bomb-makers employ, and can thus give cover for clandestine weapons programmes. Plutonium is made from unenriched uranium in reactors whose purpose can easily be switched to bomb-making. Thorium, though, is hard to turn into a bomb; not impossible, but sufficiently uninviting a prospect that America axed thorium research in the 1970s. It is also three or four times as abundant as uranium. In a world where nuclear energy was a primary goal of research, rather than a military spin-off, it would certainly look worthy of investigation. And it is, indeed, being investigated.

India has abundant thorium reserves, and the country’s nuclear-power programme, which is intended, eventually, to supply a quarter of the country’s electricity (up from 3% at the moment), plans to use these for fuel. This will take time. The Indira Gandhi Centre for Atomic Research already runs a small research reactor in Kalpakkam, Tamil Nadu, and the Bhabha Atomic Research Centre in Mumbai plans to follow this up with a thorium-powered heavy-water reactor that will, it hopes, be ready early next decade.

China’s thorium programme looks bigger. The Chinese Academy of Sciences claims the country now has “the world’s largest national effort on thorium,” employing a team of 430 scientists and engineers, a number planned to rise to 750 by 2015. This team, moreover, is headed by Jiang Mianheng, an engineering graduate of Drexel University in the United States who is the son of China’s former leader, Jiang Zemin (himself an engineer). Some may question whether Mr Jiang got his job strictly on merit. His appointment, though, does suggest the project has political clout. The team plan to fire up a prototype thorium reactor in 2015. Like India’s, this will use solid fuel. But by 2017 the Shanghai Institute of Applied Physics expects to have one that uses a trickier but better fuel, molten thorium fluoride.

Thorium itself is not fissile. If bombarded by neutrons, though, it turns into an isotope of uranium, 233U, which is. Thorium can thus be burned in a conventional reactor along with enriched uranium or plutonium to provide the necessary neutrons. But a better way is to turn the element into its fluoride, mix that with fluorides of beryllium and lithium to bring its melting-point down from 1,110ºC to a more tractable 360ºC, and melt the mixture. The resulting liquid can be pumped into a specially designed reactor core, where fission raises its temperature to 700ºC or so. It then moves on to a heat exchanger, to transfer its newly acquired heat to a gas (usually carbon dioxide or helium) which is employed to drive turbines that generate electricity. That done, the now-cooled fluoride mixture returns to the core to be recharged with heat.

This is roughly how America’s experimental thorium reactor, at Oak Ridge National Laboratory, worked in the 1960s. Its modern incarnation is known as an LFTR (liquid-fluoride thorium reactor).

One of the cleverest things about LFTRs is that they work at atmospheric pressure. This changes the economics of nuclear power. In a light-water reactor, the type most commonly deployed at the moment, the cooling water is under extremely high pressure. As a consequence, light-water reactors need to be sheathed in steel pressure vessels and housed in fortress-like containment buildings in case their cooling systems fail and radioactive steam is released. An LFTR needs none of these.

Thorium is also easier to prepare than its rivals. Only 0.7% of natural uranium is the fissionable isotope 235U. The rest is 238U, which is heavier because it has three more neutrons, and does not undergo fission because of the stability these neutrons bring. This is why uranium has to be enriched by the complicated process of centrifugation. Plutonium is made by bombarding 238U with neutrons in a manner similar to the conversion of thorium into 233U. In its case, however, this requires a separate reactor from the one the plutonium is eventually burned in. By contrast thorium, once extracted from its ore, is reactor-ready.

It does, it is true, need a seed of uranium or plutonium to provide neutrons to start the ball rolling. Once enough of it has been converted into 233U, though, the process becomes self-sustaining, with neutrons from the fission of 233U transmuting sufficient thorium to replace the 233U as it is consumed. The seed material then becomes superfluous and can, because the fuel is liquid, be flushed out of the reactor along with the fission products generated when 233U atoms split up. Similarly, more thorium fluoride can be bled in as needed. The consequence is that thorium reactors can run non-stop for years, unlike light-water reactors. These have to be shut down every 18 months to replace batches of fuel rods.

Thorium has other advantages, too. Even the waste products of LFTRs are less hazardous than those of a light-water reactor. There is less than a hundredth of the quantity and its radioactivity falls to safe levels within centuries, instead of the tens of millennia for light-water waste.

Paradoxically, though, given thorium’s history, it is the difficulty of weaponising thorium which many see (as it were) as its killer app in civil power stations. One or two 233U bombs were tested in the Nevada desert during the 1950s and, perhaps ominously, another was detonated by India in the late 1990s. But if the American experience is anything to go by, such bombs are temperamental and susceptible to premature detonation because the intense gamma radiation 233U produces fries the triggering circuitry and makes handling the weapons hazardous. The American effort was abandoned after the Nevada tests.

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Rogue nations interested in an atom bomb are thus likely to leave thorium reactors well alone when there is so much poorly policed plutonium scattered around the world. So a technology abandoned because it could not be turned into weapons may now, in part for that very reason, be about to resurface.

Here’s a final thought: the U.S. and the Five Powers are currently negotiating with Iran over limiting its enrichment of uranium and plutonium from its nuclear power plants. Why does the world not offer to replace Iran’s traditional nuclear power plants with a new generation of liquid-fluoride thorium reactors (LFTR)? If Iran is to be believed that it is not developing the technology to produce a nuclear weapon (dubious), then it should welcome this opportunity for the next generation of nuclear reactors. This solution is far better than the alternative of a world at war.


  1. I would argue that this article on solar vs. nuclear energy is misleading. Unfortunately, I am not an energy expert and am not prepared to give an adequate critical analysis. I encourage you to contact the local, Rincon chapter of the Sierra Club for a critical analysis of the issues you raise. A member of the Chapter’s executive committee is an energy expert who can provide such a critical analysis. . Phone (520) 620-6401.

    It should be obvious to all that nuclear energy is not “renewable” in the same sense that solar energy is. Solar energy is inexhaustible, whereas uranium and thorium are not. It may be that solar panels only capture about 25% of the sunshine energy, but so what? “The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth’s non-renewable resources of coal, oil, natural gas, and mined uranium combined” ( Anyway, the cheapest, most efficient energy source comes from better use of available energy, e.g., via insulation of buildings.

    We have to ask whether nuclear energy is more economically viable than solar energy. If so, why won’t financial sources fund it without the support of huge government subsidies, and special, legal hazard insurance limitations? I have read that the development of new solar is less expensive than new nuclear. In addition, the economic and risk problems of storing nuclear waste from power plants have yet to be solved.

    Nuclear energy plants are sited near large rivers and near oceans because they require enormous amounts of water. Palo Verde runs on the effluent of one of the largest cities in America. One wonders where the Arizona Legislature would site the next Palo Verde in sunny, arid, drought- stricken Arizona in this era of a changing climate that is on track to make Arizona even more arid. Perhaps, the legislature is motivated by lobbies of special interests that cannot own the sunshine in the same way that they can own a fossil fuel or mineral source.

    Is the thorium reactor the answer to all the current problems of nuclear energy? Surely there are some cons. I wonder what they are: expert needed! The first commercial thorium plant has yet to be built, and it will probably take many years before one or more are built and tested. Over time both uranium and thorium will become more expensive as supplies dwindle.

    • Let’s be honest here: As far as the Sierra Club is concerned, there will never be an acceptable form of nuclear power. I realize their charter requires them to lean heavily in favor of the natural state, so I don’t criticize them for that. It is just important to understand the perspective they bring to the table.

      Continuing with that honesty: The only logical solution to our near term needs for energy is nuclear energy. The alternatives are still many years from achieving their potential and even more years from achieving their productive capacity. That capacity will never be sufficient to make alternative forms anything more than a portion of our energy supply. Our needs for energy are only going to grow. Our dependence on oil has to be curtailed. Nuclear power has to be part of the solution.

  2. Before anyone gets too excited about this Thorium has a known level of toxicity, 4 superfund sites are contaminated with thorium and its downstream decay particles, which are also toxic, other sites have been proposed for Superund designation. Workers have suffered toxicity from exposure and children have been exposed by living near thorium facilities. Here is a link from NIH:

    In addition the articles on solar (and let’s not forget wind) and other true renewables do not accurately reflect what we KNOW about how easy and inexpensive it would be to power the country with these sources. An area the size of Area 51 in Nevada covered with solar panels would be sufficient to provide power to the entire country not just now but for the projected rise in power use for the next 30 years (the calculations are easy). Energy storage technology is improving by the day, but even old energy storage tech works just fine for thousands of houses off the grid. The U.S. Military is investing heavily in solar energy for a reason, they have done the analysis and see that as the best way forward for energy independence. The ONLY thing holding Arizona back as what could be THE solar capital of the U.S. is politics. That politics is driven by greed alone. The fossil and nuclear industries in AZ do not want the competition from solar and wind. Yes they have a few facilities themselves, but they can see a day when they are relegated to back-up power for businesses and homeowners who are their own individual, democratized, power plants. And by the way, the cost of solar modules has decreased by 80% in the last 8 years, making it second to wind as one of the least costly methods of generating power. If pollution and clean-up costs were included even at today’s low fossil fuel prices solar and wind would be less expensive. This is why Germany now generates something near 30% of its power from solar and wind. If the German number crunchers can figure it out then you have to figure it makes financial sense. And let’s not forget the ceapest source of rewable energy of all, energy conservation. If you don’t use it, you won’t have to generate it. Energy conservation pays $3 for every $1 invested.

  3. I am truly surprised to find out that you are in favor of nuclear energy of any sort. That isn’t something I expect from the left. You did an excellent job explaining to lay persons why thorium based nuclear power plants could have a real future for us and the rest of the world. I hope it catches on because it would solve a LOT of problems facing us. Thank you for posting such an informative and valuable article!

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