Is Thorium A Magic Bullet For Our Energy Problems?

As the search for cheap, safe and non-carbon emitting sources of energy continues, a band of scientists say the answer may be nuclear reactors fueled by thorium. Others caution that thorium reactors pose waste and proliferation risks. Ira Flatow and guests discuss the pros and cons of thorium reactors.

IRA FLATOW, HOST:

This is SCIENCE FRIDAY. I'm Ira Flatow. What if there was a nuclear reactor that was meltdown safe, generated power inexpensively, created no weapons-grade byproducts and burnt up existing nuclear waste stockpiled? Sound too good to be true?

Well, a group of scientists and engineers around the world say there is such a reactor. They're talking about nuclear reactors based on the element thorium, naturally occurring and much more abundant than uranium. Well, if this technology is so great, then why aren't we using it? My next guest explored that question and why nuclear power from thorium has become a forgotten energy source in his new book.

Richard Martin is the author of "SuperFuel: Thorium, The Green Energy Source for the future, and he's a contributing editor for Wired and editorial director for Pike Research. He joins us from Boulder, Colorado. Welcome to SCIENCE FRIDAY.

RICHARD MARTIN: Ira, it's a pleasure to be here.

FLATOW: Thank you. So why don't we - tell us what the difference between a thorium reactor and the nuclear one that we have now.

MARTIN: Well, first you have to talk about the difference between the two elements, and as you say, thorium is much more abundant than uranium. It's about as common as lead. But the critical difference for this discussion is thorium is not fissile, it's fertile, and I'll explain that difference.

Fissile means you can cram enough of the material together in a single place, and a chain reaction will start spontaneously and continue. Fertile means you have to have an external neutron source to bombard the thorium, which then transmutes into actually an isotope, a different form of uranium, which is far better to use for creating power. So that's the most fundamental difference.

And as I say in "SuperFuel," the book, thorium has been kind of a shadow element to uranium over the last, oh, century and a half or so when they were both discovered in the 19th century, and thorium has a lot of qualities that are sort of parallel and yet contrasting with uranium that again make it safer and cleaner and so on.

FLATOW: And your thesis in the book is that if we had started with thorium from the beginning, we'd be much better off now?

MARTIN: Well, that's what's interesting about the story, right. There's a very complicated history of thorium and uranium in the early days of the Manhattan Project and then in the '50s and '60s in the days of the fledgling nuclear power industry. And the thing to remember about thorium is it's not a new technology.

We worked with it extensively. It was used in some of the earliest nuclear physics experiments by Marie Curie, by Ernest Rutherford when he first started to understand the principle of nuclear decay and so on. And so the early nuclear physicists were very familiar with it.

And then in the '30s, fascism rose in Europe. We had to fight World War II, and uranium, which is much better for making bombs, took over the stage, as it were, and that's when thorium actually sort of was pushed aside.

But I have to tell you that at Oak Ridge National Laboratory in Tennessee, there was extensive work done on - not just on thorium as a nuclear fuel but on an alternative form of reactor, as well. what was then called the molten salt reactor and is now known as the liquid fuel thorium reactor. So it's an entirely different reactor technology, as well as a different fuel.

FLATOW: Was one actually built?

MARTIN: Yes, so the molten salt reactor experiment ran from about '59 until 1973, when it was canceled, and the director of Oak Ridge, Alvin Weinberg, who was a great proponent of thorium and of molten salt reactors, was actually fired by the Nixon administration in 1973, partly because of his belief that we needed an alternative form and that thorium was really a better fuel.

And so they ran the molten salt reactor, started out running it on conventional uranium, transitioned to uranium-233, which as I mentioned is the byproduct of thorium once it's in a nuclear reactor. And it was completely proven. I've read the documents from Oak Ridge, in which they were - the officials were reporting on the results of this experiment, and it's basically Dr. Weinberg, thank you very much, your experiment has been a complete success, and now we're shutting it down.

FLATOW: Not everyone sees thorium reactors as cheap, clean and safe alternatives, that - as a bet for the future. With me is Dr. Arjun Makhijani. He is president of the Institute for Energy and Environmental Research. He's here in our D.C. studios. Do you agree with Richard Martin that we missed out on thorium? If we had started out with thorium, would be in better shape now?

ARJUN MAKHIJANI: I don't think so. I think the problems of nuclear power, fundamentally, would remain. The safety problems would be different. I mean, Mr. Martin and proponents of thorium are right in the sense that the liquid fuel reactor has a number of safety advantages, but it also has a number of disadvantages.

For instance, this breeder reactor lost out with the sodium-cooled breeder, in the incident that Mr. Martin mentioned, because the liquid - the molten sodium reactor, the sodium-cooled reactor has a much better breeding ratio. It produces a lot more excess fuel that you can then take to the next reactor.

In this reactor, because thorium is not a fissile material, you actually need either plutonium or enriched uranium to start it. In fact, this reactor that operated in Oak Ridge for a few years, it actually started up in 1964, it never used thorium to breed uranium-233.

Some uranium-233 was put into the reactor at one point, but it had been made in another reactor. It hadn't been made in that reactor. It operated with enriched uranium, some plutonium and some uranium-233, but not made in that reactor.

So what are the problems? The problem is that with this particular reactor, most people will want a reprocessing, that is separating the fissile material on-site. so you have a continuous flow of molten salt out of the reactor. You take out the protactinium-233, which is a precursor of uranium, and then you put the uranium back in the reactor, and then you keep it going.

But if you look at the Princeton University paper on thorium reactors from a few years ago, you'll see that this onsite reprocessing allows you to separate protactinium altogether. Now, the U.S. wouldn't do it, but if you were a county without nuclear materials and had a reprocessing plant right there, you'd separate the protactinium-233, you'd get pure uranium-233, which is easier to make bombs with than plutonium.

I can read you the quote from the Princeton University paper, but I won't bother.

FLATOW: So you're saying that it doesn't solve the safety issues.

MAKHIJANI: It doesn't solve the proliferation problem. It doesn't solve the waste problem, either. So every nuclear reactor, no matter what type, creates fission products, which are highly radioactive materials, some short-lived, some long-lived, to make energy.

With the present reactors, we create about a ton per reactor, per year. If you have a more efficient reactor, at least you will create half a ton, probably eight-tenths of a ton, nine-tenths of a ton. This is highly radioactive waste. If you look at Oak Ridge's current evaluation, they say you have to condition this waste, you have to convert the fluorides, and then you have to have a deep geologic repository.

What's in this waste? Cesium-137 and strontium-190, hundreds of years, just like today's reactors. Cesium-135 and iodine-129, millions of years half-life. Technetium-99, 200,000 years. Now, Mr. Martin says that you don't have to worry about Technetium-99 because it's used in medical practice on millions of people.

Now, Technetium-99 is radioactive, and it's used not because it's risk-free, but because there's some need that balances off the risk according to the doctor, gives some benefit to the person. Technetium-99, like other radioactive materials, inside your body, creates a cancer risk.

So you ask: Well, how much cancer risk does medical use of radiation in the United States create every year? If you use National Academy's coefficients for cancer risk, the answer would be about 90,000 cancers.

FLATOW: Richard Martin, any reaction?

MARTIN: Well, first I want to pause and thank Dr. Makhijani for - I'm very familiar with his work, and at least he has engaged with the issues around thorium and around nuclear power in general, as opposed to most people in the nuclear power establishment, as well as in the environmental movement, who simply dismiss it out of hand. So I want to compliment him on at least treating it in thorough and rational way.

MAKHIJANI: Thank you.

MARTIN: However - you're welcome. However, some of those conclusions are just wrong. So when we talk about the waste, one of the things that skeptics of the liquid fuel thorium reactor ignore is the fact that because the core is a liquid, you can continually process waste, even from existing conventional reactors into forms that are much smaller in terms of volume, and the radioactivity drops off much, much quicker. We're talking about a few hundred years as opposed to tens of thousands of years.

So to say that thorium reactors, like any other reactor, will create waste that needs to be handled and stored, et cetera, is true, but the volume, we're talking tenths of a percent of the comparable volume from a conventional reactor. And not only that, but we've got all that waste from our existing nuclear reactor fleet, just sitting around, and we've got no plan for it.

And so we're talking about building a reactor that can process that into forms that are much, much easier to deal with. And so that's the waste issue. The proliferation issue is complicated. And the point that Dr. Makhijani, in the paper that I've read, brings up but then kind of dismisses is that in order to build a bomb with uranium-233, you somehow have to obtain it out of the reactor.

And because this is a self-contained, liquid fuel system, it's - there's no point at which you can divert material. There's no material sitting in a warehouse somewhere, getting ready to be put in the reactor and so on. And to be able to obtain that material, you would have to somehow breach the reactor, shut it down, separate out the fissionable material and get away with it.

And as I say in "SuperFuel," the book, good luck with that. But the other point is that even if you did manage to do that, the uranium-233 is contaminated with yet another isotope, U-232, which is one of the nastiest substances in the universe, and it makes handling and processing and separating out the U-233 virtually impossible, even for a sophisticated nuclear power lab, much less for a rogue nation, or terrorist group or someone of that ilk.

So to say that in principle you could obtain material with which you could make a bomb from a liquid-fueled thorium reactor is true. In the real world, the chances of that are, you know, very, very slim - so much as to be negligible.

FLATOW: 1-800-989-8255. We're going to go take a break, but first we're talking with Richard Martin, author of "SuperFuel: Thorium, The Green Energy Source for the Future"; also Arjun Makhijani, who is president of the Institute for Energy and Environmental Research. Our number, 1-800-989-8255. You can also tweet us @scifri or participate in the discussion on our Facebook page. Stay with us. We'll be right back after this break. So don't go away.

(SOUNDBITE OF MUSIC)

FLATOW: I'm Ira Flatow, and this is SCIENCE FRIDAY from NPR.

(SOUNDBITE OF MUSIC)

FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow. We're talking this hour about the pros and cons of nuclear power from thorium with Richard Martin, author of the book "SuperFuel: Thorium, The Green Energy Source for the Future," and also with Arjun Makhijani, who is president of the Institute for Energy and Environmental Research. Arjun, any rebuttal?

MAKHIJANI: Yeah. But first let me thank Mr. Martin and say I'll send you my book, "Carbon-free, Nuclear-free: Roadmap for U.S. Energy Policy," since I have your book from your publisher.

MARTIN: I look forward to it.

MAKHIJANI: Quickly on proliferation, then I'll talk about waste. The Princeton University paper says that the inline reprocessing, and this is a quote, offers a way to completely bypass the uranium-232, this terrible radioactive material, contamination problem, because the 27-day half-life of protactinium-233 could be separated out before it decays to uranium-233.

I didn't want to say that earlier, but the bottom line from that is you have that reprocessing, you can actually get rid of the U-232 problem. This particular reactor is more vulnerable to proliferation, and I think Mr. Martin should revisit this question just for accuracy.

But on waste, here's what Mr. Weinberg, who was the father, guru of this reaction, Dr. Weinberg, is very enthusiastic about nuclear energy. But in the '70s, he grew more cautious on proliferation and waste. He coined the phrase Faustian bargain. It will give you a great energy source, but you've got to worry about proliferation and waste.

He also said that, looking back, this enthusiasm about these reactors reminds me of what Mr. Weinberg said sort of ruefully about his own excitement. He says: I was a little bit like the Ayatollah is at the moment. He said that in 1981. And then in 1994, when he wrote his memoir, he really rued the fact that waste had been relegated to a secondary issue, which is exactly what the proponents of (unintelligible), the really solid ones, you know, enthusiastic, rah-rah crowd is doing, which is relegating to a secondary issue.

Mr. - Dr. Weinberg said that if he had to do it over again, he would put the waste issue at the top of the agenda of Oak Ridge National Lab.

FLATOW: Richard Martin, rebuttal?

MARTIN: First of all, I just want to talk about Dr. Weinberg for a moment, because I think he's a bit of a forgotten figure. And as Arjun says, he really was a prophet of nuclear safety issues. Alvin Weinberg never lost his enthusiasm for thorium-based nuclear power. He never lost his belief that nuclear power would be the answer, long-term, for our energy needs.

And he talked about the second age of nuclear power and how confident he was that it would happen, and his only regret was that he would not be around to see it. And as it turns out, that is exactly what's happening with the nuclear renaissance, and hopefully with the thorium revival.

But I also want to take just a step back, here, if I may for a moment, and talk about this whole issue of risk. We've been focusing in on some details of protactinium and the build-up of U-232 and so on, but my question to Dr. Makhijani would be: OK, you have concerns about thorium-based nuclear power, and those are not to be dismissed lightly. But what is the answer if this is not it?

Because as I demonstrate in "SuperFuel," the book, renewables are not going to solve our problem in the time scales that we need it - in other words, in the next 30 to 50 years. Solar and wind and so on are just not going to be at large enough scales and at the prices to really replace a significant fraction of fossil fuel-based energy in the timeframes that we need.

So we're talking about two different risks, here: the risks associated with an innovative form of nuclear power based on a very abundant and safe material versus the risk of a three-degree-Celsius, let's say, rise in global temperatures over the next 50 years, within, you know, my son's lifetime. So, as a society, I don't think we're very good at calculating risk. And so to hone in on these pretty technical issues of, well, there might be some proliferation risk with thorium, there's no question that thorium - liquid-fueled thorium reactors can be used to consume the existing waste from conventional reactors.

It's unpressurized liquid chemistry. We are really good at that. And one thing we haven't mentioned yet is the whole issue of nuclear accidents. And so I'd like to dwell on that for a moment, as well.

FLATOW: Well, I've only got about a minute or so to go. But you brought it up, and let me get a reaction from Dr. Makhijani.

MARTIN: Of course.

MAKHIJANI: I have a favorite molten salt reactor. My reactor is free. It's in the sky, 93 million miles away. You can store its energy in molten salt. It is being done today. You can generate electricity for 24 hours a day. The - so the impermanency problem has been solved.

I don't know why - I'm still trying to understand why photovoltaics are still so expensive in this country. But you know Germany - I was at a seminar yesterday at the Heinrich Boll Foundation about the Germany decision to get out of nuclear. They're going to have a completely renewable system maybe by the time thorium reactors become commercial.

This isn't going to happen tomorrow, even if you pour money into it. It would take 10 years for the NRC to understand and write regulations for this thing. And it would take 10 years before that to build the reactors, do the experiments and produce the data so you can regulate this thing, because all of our regulation is based on light water reactors.

Six years ago, I might have agreed with Mr. Martin that maybe, you know, impermanency is a big problem. Somebody said you haven't looked. You really should do a study. So I did an honest, unbiased look, not thinking we could do renewable energy. And I found out that my hunch was wrong: We can do 100 percent renewable energy, and the Germans are actually aiming for it.

You know, they have an export surplus with China, and we have a huge export deficit. Maybe they know something we don't know.

FLATOW: Last word, Richard, quickly?

MARTIN: Sure. I think Arjun has brought up a very important point, which is that this is not going to happen in the United States because of the licensing issues he just mentioned. It is happening in China. It is happening in India. It is happening in certain countries in Western Europe. And so our choice in this country is whether we are going to be left behind on the next big energy technology, or whether we are going to take advantage of a technology that was developed right here at Oak Ridge and that has been proven out. And that's really the choice before us.

And the thorium revival is inevitable. The question is whether the United States is going to be a follower or a leader.

FLATOW: All right, you have the last word. Richard Martin, author of the book "SuperFuel: Thorium, the Green Energy Source for the Future," also contributing editor for Wired and editorial director for Pike Research. Dr. Arjun Makhijani is also president of The Institute for Energy and Environmental Research. Thank you both for taking time to be with us this afternoon.

MAKHIJANI: Thank you, Ira.

MARTIN: Thanks, Ira.

Copyright © 2012 NPR. All rights reserved. Visit our website terms of use and permissions pages at www.npr.org for further information.

NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.