Energy

Can thorium reactors dispose of weapons-grade plutonium?

Can thorium reactors dispose o...
According to a new Russian study, thorium reactors could provide a safer alternative to nuclear energy, while also safely disposing of nuclear waste
According to a new Russian study, thorium reactors could provide a safer alternative to nuclear energy, while also safely disposing of nuclear waste
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According to a new Russian study, thorium reactors could provide a safer alternative to nuclear energy, while also safely disposing of nuclear waste
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According to a new Russian study, thorium reactors could provide a safer alternative to nuclear energy, while also safely disposing of nuclear waste

Thorium reactors have long been proposed as a cleaner, safer alternative to conventional nuclear energy, and now a new Russian study has added another potential benefit to the mix. Scientists from Tomsk Polytechnic University (TPU) propose a new thorium reactor design that can burn weapons-grade plutonium, producing power and thermal energy while disposing of nuclear waste at the same time.

Weapons-grade plutonium (plutonium-239) is one of the dangerous radioactive by-products of nuclear power, and with a half-life of over 24,000 years, it's tricky to store and dispose of. The substance is still packed with potential energy, but reusing it requires chemical processing that can be expensive and complicated.

Enter thorium. This element is more abundant in nature, cleaner and potentially more efficient than uranium, so thorium reactors have long been proposed as a viable alternative to conventional nuclear reactors. Unfortunately, the properties that make it attractive also raise new obstacles.

Once things get cooking in a nuclear reactor, the chain reaction can essentially keep feeding back into itself. Neutrons strike the nucleus of the atoms of the fuel source (usually uranium), breaking it into its components and releasing energy in a process known as fission. More neutrons are released along with the energy, which can in turn be used to fission other atoms.

The problem is, that self-sustaining cycle can also lead to nuclear power's most devastating downside. If operators lose control of that chain reaction or fail to properly keep it cool, a meltdown can occur, resulting in disasters like those seen at Chernobyl and Fukushima.

By itself, thorium can't sustain that feedback loop. That means it won't get out of hand on its own, but to produce power it still requires some other radioactive material. And that's where the TPU study comes in.

The Russian researchers plan to use weapons-grade plutonium to fuel that reaction, giving the reactor the safety benefits of thorium while also disposing of the nuclear waste. According to the team the reactor can burn almost all of the plutonium, and the waste material that's produced is a mix of graphite, plutonium and other decay products that no longer pose a nuclear hazard.

"Large amounts of weapons-grade plutonium were accumulated in the Soviet era," says Sergey Bedenko, an author of the study. "The cost for storing this fuel is enormous, and it needs to be disposed of. In the US, it is chemically processed and burned, and in Russia, it is burned in the reactors. However, some amount of plutonium still remains, and it needs to be disposed of in radioactive waste landfills. Our technology improves this drawback since it allows burning 97 percent of weapons-grade plutonium. When all weapons-grade plutonium is disposed of, it will be possible to use uranium-235 or uranium-233 in thorium reactors."

The proposed thorium reactor has other advantages as well. The plant requires relatively low input energy, from 60 MWt, which can make them up to 50 percent more efficient than other reactors. Waste heat can also be harnessed for desalination of water or to produce hydrogen fuel, according to the researchers.

"The main advantage of such plants will be their multi-functionality," says Bedenko. "Firstly, we efficiently dispose one of the most dangerous radioactive fuels in thorium reactors, secondly, we generate power and heat, thirdly, with its help, it will be possible to develop industrial hydrogen production."

Thorium reactors have been discussed almost as long as nuclear energy has, but the technology has never been successfully developed. Renewed focus on environmentally friendly energy in recent times has seen scientists begin to experiment with thorium-based nuclear power again after 40 years, and this latest development could lend further impetus to getting it off the ground.

The research was published in the journal Annals of Nuclear Energy.

Source: Tomsk Polytechnic University

17 comments
Terence Hawkes
THe idea that it is safer is debatable. If you get near an unshielded operating reactor or close to the plutonium required to get it started, you die. If the reactor contents leak, you die. If you handle the byproducts without protection, you die. If you think it is safe and you mske a mistske, you still die,
notarichman
the guy sitting on a huge thorium mine near boise, idaho will be glad to see this article...then he can sell it.
AlainGassmann
Safer, not completely safe although molten salt Thorium systems are getting that way. Using up stocks stockpiles of weapon grade plutonium will make the world a safer place, however, and that for the next few thousand years. The trouble is that the nuclear powers that be want the weapons grade plutonium.
owlbeyou
Terence Hawkes, judging by what you have written, one has the impression that you are a fatalist of some kind. Be careful if you go out and get in a car or airplane because one mistake and you might die. What the TPU is doing is remarkable and I wish them every possible success. Something has to be done about all the nuclear waste besides burying it. The fact that this process can potentially be used to produce hydrogen as well as produce more energy is a plus.
Rustin Lee Haase
If humanity was inherantly good, this would be a great technology. Unfortunately we are a deceptive, selfish lot and people would be more likely to build plants like this and gladly accept other people's plutonium and then stockpile it secretly instead of destroy it. I would definitely NOT trust the Russians, Chinese, or others who fear neither God nor man to actually destroy any plutonium they get their "hands" on. Because of human nature this is NOT a good way to get rid of plutonium. Only a fool would be so optimistic. We are going to have to count on upsidasium's (plutonium's) short half life to get rid of most of it, or we could bring lots of it together and.... That said, getting energy out of thorium isn't a bad idea and its good to see us working on such technology for that purpose.
Bruce Golden
The space agencies are consumers of plutonium for spacecraft missions that get past the point where solar cells can be a reasonable size (weight to launch). Plutonium has been used for several deep space missions. Was just an article here about NASA working on 1-10 kW nuclear reactors "because plutonium was in short supply". UK has reportedly 100 tonne of plutonium. Thorium is separately a possible earth energy resource and requires a neutron source to "fire" the reaction. Turn the source off and the thorium reaction ceases ... still have radiation and heat to manage but much lower possibility of a run away reaction.
Expanded Viewpoint
Exactly right there, Terrence and Alain. Nukes are like a comfort food to tyrants, they need them to feel safe and secure. According to something I'd read about 15 years ago, Hydroxy supposedly greatly reduces the level of radioactivity of fissile materials when heated to their melting point. It was not stated if the amount of the reduction of radioactivity was seen only on the first time the material was melted, or if it took a certain amount of time in the molten state for the effect to take place. It might be a bogus claim to begin with, but I don't happen to have any Plutonium sitting in my garage to test the theory out right now, I lent it to my good friend and mentor, Doc Brown.
Kpar
None of this is actually news- it has been argued for decades. For a more complete picture on Thorium, check out Thorium Energy Alliance. The future can be now...
JimFox
"but the technology has never been successfully developed" So the experimental LFTR at Oak Ridge designed & operated by Alvin Weinberg for FOUR years in the early 1960's doesn't count? Terence Hawkes-- LFTR & thorium reactors in general are proven far safer than the PWR's or other uranium fission reactors. Handling plutonium is indeed very risky- but that's true independent of thorium reactors; you still have to manage the stuff. What operating reactor of ANY type is ever unshielded? LFTR operates at near- atmospheric pressure; waste products are about 2% of those from a PWR; half lives are max 300 years, not tens of thousands; LFTR cannot explode nor melt down, the fuel is already in liquid form and the drain plug melts if temperature exceeds design, releasing the fuel into a drainage tank where it solidifies, ending the fission reaction. It is 'walk-away' safe. You would do better with a little basic research, otherwise your comments are unsubstantiated.
JimFox
Alan Gassman-- The 'powers that be' have far too much plutonium, that's the whole point of the article. Costs of safely storing this nightmare are astronomical which is why they want rid of most of it. Perhaps you didn't read the article closely enough?