Nuclear fuel recycling could offer plentiful energy (w/ Video)

Jun 25, 2012 BY LOUISE LERNER
Nuclear fuel recycling could offer plentiful energy (w/ Video)
Frances Dozier conducts research on recycling used nuclear fuel in a glovebox at Argonne National Laboratory.

Imagine the mess if we mined one ton of coal, burned five percent of it for energy, and then threw away the rest.

That is what happens with uranium for today. Currently, only about five percent of the uranium in a fuel rod gets fissioned for energy; after that, the rods are taken out of the reactor and put into permanent storage.

There is a way, however, to use almost all of the uranium in a fuel rod. Recycling used nuclear fuel could produce hundreds of years of energy from just the uranium we’ve already mined, all of it carbon-free. Problems with older technology put a halt to recycling used nuclear fuel in the United States, but new techniques developed by scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory address many of those issues.

One of the reasons why so little uranium is used is that almost every commercial reactor today is a type called a light-water reactor, or LWR. While LWRs are good at many things, they aren’t designed to wring every last watt of energy out of fuel.

But LWRs aren’t the only type of reactor. Another class, called fast reactors, boasts the ability to “recycle” used fuel to get much more energy out of it.

The main difference between the types of reactors is what cools the core. LWRs use ordinary water. Fast reactors use a different coolant, such as sodium or lead. This coolant doesn’t slow the neutrons as much, and consequently, the reactor can fission a host of different isotopes. This means that fast reactors can get electricity out of many kinds of fuel, including all of that leftover used fuel from LWRs. (LWRs can burn recycled fuel too, with some modification, but they aren’t as good at it.)

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If we built fast reactors, it would be entirely possible to take all of the used fuel we’ve generated over the past 60 years, currently stored at reactor sites, and feed it back into fast reactors. Some of it would still need to be permanently stored, but far less; recycling all of the uranium and other actinides would reduce the volume of waste we have to store permanently by 80 percent. To get used fuel ready to put back into a reactor, however, it needs some processing. This has been done for decades in other countries using a technique called PUREX, which has its roots in 1940s U.S. research to separate plutonium out of used fuel. The problem with PUREX is the risk that the process could be diverted to extract weapons-grade plutonium, a concern that prompted then-president Jimmy Carter to ban PUREX reprocessing in 1978.

This spurred scientists at Argonne to search for a different, more efficient way to reprocess used fuel. Their brainchild is a technique called “pyroprocessing”, which uses an electrical current to sift out the useful elements and does not separate pure plutonium.

How it works

When used fuel comes out of a light-water reactor, it’s in a hard ceramic form, and almost all of it is still just uranium – about 95 percent, along with one percent other long-lived radioactive elements, called actinides. Both of these can be recycled as fuel. The remaining four percent are fission products, which are truly unusable.

Pyroprocessing begins by chopping the ceramic fuel into little pieces and converting it into metal. Then it’s submerged in a vat of molten salts, and an electric current separates out uranium and other reusable elements, which can be shaped back into fuel rods.

The truly useless fission products stay behind to be removed from the electrorefiner and cast into stable glass discs. These leftovers do have to be put into permanent storage, but they revert back to the radioactivity of naturally occurring uranium in a few hundred years – far less than the thousands of years that untreated used fuel needs to be stored.

Why don’t we use pyroprocessing already?

  • Lack of financial incentive. Raw uranium is cheap. At the moment, it’s cheapest to run the fuel through once and then store it, mostly because other methods would have to be researched and tested. Light-water reactors are cheaper to build, because both utilities and the U.S. Nuclear Regulatory Committee are familiar with the technology. Since the process for approving a new reactor design takes years, there’s not much incentive to build different types of reactors, including fast reactors.
  • Proliferation fears. Some worry that the spread of reprocessing technology will help terrorists gain access to plutonium and uranium for weapons. Pyroprocessing concepts address this fear in two ways. First, the technique itself laces the plutonium with and highly radioactive actinides, making both stealing it and creating weapons with it more difficult. Second, pyroprocessing plants with fast reactors can be built directly on the site of a former light-water to create an enclosed recycling facility. This approach reduces the security risk by eliminating the need to transport the used fuel from and new fuel to the fast reactors at the site.
Looking ahead

To date, nuclear energy remains the only stable, large-scale source of carbon-free electricity. Reactors are sprouting across Asia as its developing powers need more energy; China alone has quintupled its nuclear capacity in just the past decade.

Argonne scientists and engineers continue to work on ways to make fuel safer, cheaper and more efficient. In the Engineering-Scale Electrorefiner, a large glovebox, Argonne scientists test pyroprocessing at a scale closer to what industry would use. They’ve also turned to computational modeling, which helps simulate the chemical processes down to molecules and up to whole facilities. Other Argonne research projects design and studysmall modular reactors and different types of fast reactors, including techniques to reduce the cost.

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User comments : 16

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Caliban
2 / 5 (8) Jun 25, 2012
Why does this seem like "trolling for subsidies"? All that energy just sitting idly by because of the initial/ongoing cost to reprocess spent LWR fuel...

Let me be the first to call bullshit. If there was a way to entrain this tech economically by bypassing the PUREX ban, then it would have already been a done deal --so this appears to be another technology ransomed by the "free market" by profiteering
nuclear energy interests slavering for those sweet taxpayer dollar$$$.

A sad state of affairs, indeed.

Osiris1
1 / 5 (4) Jun 25, 2012
Some countries will just ignore this obvious luddite economic sabotage and go ahead and use recycled fuel rather than buy new fuel at rapaciously inflated and extortionary prices. This seems Iran's whole gripe with monopolies that would keep people around the world in poverty for the forcible extraction of blood money. The idea of 'nonproliferation' is a canard, much like the 'bogeymen' stories told us as children by parents that wanted to scare us into submission. Proliferation as such is already here in thousands of basements around the world in the form of already manufactured and missing and otherwise unaccountable Russian suitcase nooooks. Warnings about these surfaced years ago and promptly disappeared from unclassified view. That did not mean the problem went away; rather that scared old men by the thousands are looking for them to this day. Far better this unholy alliance of misguided useful fools (safety nutz) and monopolists is broken up by the energy poor & oil short!
TkClick
1 / 5 (6) Jun 25, 2012
The state of research with thorium fission is similar to cold fusion: after initial period of enthusiasm the research did essentially freeze. But I wouldn't support the fission based technologies in general due their inherent radiative danger and attractiveness for various terrorist groups. The thorium fission cannot compete in safety with uranium fission, not to say about cold fusion. For further info read the factsheet: Thorium Fuel No Panacea for Nuclear Power...
CapitalismPrevails
3.1 / 5 (8) Jun 25, 2012
I thought this article might mention LFTRs. I'm disappointed...
paxus
1.6 / 5 (8) Jun 25, 2012
What i lovely article and it would be informative and useful, if this was 1985. What we have learned since then, at the failed Monju breeder in Japan, at the failed Phenox and Super Phenix breeders in France, at the failed Sellafield reprocessing facility in the UK is that the entire breeder/reprocessing scheme is a waste of money and an technical nightmare. We keep getting promised these rosy dreams,as you do above and what is delivered generally does not work and is crazy expensive. Solar PV just broke 50% of the daily electricity supply in Germany for a day a couple weeks back, more than nuclear ever provided. Please step out of the nuclear stone age and do something useful with your time.
Jeddy_Mctedder
2.1 / 5 (7) Jun 25, 2012
Balogna. nuclear spent fuel recycling has been known for years, it has been proven to work and the reason the government doens't force our industry to do this
is because the nuclear industry OWNS government. and make money from MINING. not from building power plants.

the electric utilities don't care either way. and the greenies are against just about anything nuclear because theyre simply dumb and would rather complain about nuclear waste piling up in waste pools waiting for an accident , rather than proposing a progressive solution to the problem, rather than just proposing to bury this 'stuff' that contains massive quantities of energy.

and it's not the big military that needs mining of uranium to continue. the military can secure a stable source of uranium for their needs. it IS the uranium mining and fuel assembler interests that are the nuclear industries source of profit. The outlay for new plants that would eliminate this profit would destroy them.
rwinners
2.8 / 5 (4) Jun 25, 2012
France has been recycling spent fuel for decades and supplying all of Europe with the product.
All that fuel, sitting around the US in casks at storage sites could easily be reprocessed and reused... and more than once.
One cannot argue with stupidity.
dirk_bruere
3.7 / 5 (3) Jun 25, 2012
The reasons why reprocessing is not economic:
http://belfercent...uel.html
rbrtwjohnson
2 / 5 (4) Jun 25, 2012
In my opinion, it is possible to produce carbon-free electricity with no long-lived radioactive elements and no enrichment of uranium and plutonium for weapon proliferation. Nuclear fusion is not a dead end after all. Nuclear fusion is clean and safe, and it is possible a well-conceived fusion reactor that produces more energy out than in by wisely using electrostatic acceleration. http://www.youtub...-QYqqxzM
luinil
2.6 / 5 (5) Jun 26, 2012
in less than fifty years, we had 4 accidents in reactors with leakage of radioactive material (1 in Chernobyl, 3 in Fukushima) and a meltdown in the US.

Those reactors have been cooled with water, replace it with a highly explosive substance like sodium and think about what would probably happen in the next 50 years with those new reactors.

Just imagine Fukushima with liquid sodium instead of water...

This article is nothing but pure propaganda.
TkClick
2.6 / 5 (5) Jun 26, 2012
The people should realize one thing: the thorium is not fissile, it must be converted with fission reactor with fissile uranium fuel. The stability of nuclear reactors strongly depends on the complexity of nuclear reactors which occur in it. If some product of radioactive decay cumulates in it - which may occur during period of both low, both high activity - it may lead into unexpected avalanche-like production of heat. This is how the Chernobyl explosion happened (samarium poisoning). Therefore the thorium reactors are inherently less stable and they must run at higher rate, than the uranium reactors, where the fuel is rather diluted. This brings the requirement of higher production temperatures and pressures, the higher heat flux gradient, the necessity of sodium coolant and another technological complications, which increase the risk of danger even more. If you're unsure about classical uranium reactors, then the thorium reactors will not be probably the right option for you.
TkClick
2.6 / 5 (5) Jun 26, 2012
A semantic error: "...complexity of nuclear reactors.." should be "complexity of nuclear reactions..." indeed..
the_life_atomic
3 / 5 (2) Jun 26, 2012
Despite the glaring lack of any knowledge in most of your comments, this article is not about the financial merits of reprocessing, "profiteering nuclear energy interests", reactor safety, or nuclear security legacy. It's a discussion about potential out-year resource utilization. If renewables simply come up short with demand, coal and petroleum eventually are deemed too harmful, and performance of used nuclear fuel in a repository is an important consideration, then there is a tremendous argument for utilizing used fuel. Whether the market or policy steer it that direction is a complex question. But there are is no simple technological reason not to utilize used nuclear fuel. We may rely on it in the future.
TkClick
2.6 / 5 (5) Jun 26, 2012
We shouldn't produce such a waste at all. We are just trying to solve the problems, which would never appeared, if we would follow consequentially the optimal route. Cold fusion finding is actually fifty years old. But I don't believe, most of current wastes are recyclable. They're immobilized in concrete of glass already. And you cannot fill the nuclear reactor with random shit, or its behaviour will become unpredictable. You should realize, the low degree of uranium fuel utilization is given just by fact, the actinides products represent a poison for nuclear reactors: they're absorbing neutrons heavily and they convert itself into radioisotopes of unpredictable fission routes (xenon or samarium and promethium). We therefore cannot the refill the nuclear reactor just with the same poison, for which we're replacing the uranium rods prematurely for the sake of reactor stability.
TkClick
2.3 / 5 (3) Jun 26, 2012
there is a tremendous argument for utilizing used fuel
Only if we neglect all these financial, safety and/or nuclear security issues. Without these issues I could say easily, there are a tremendous arguments for widespread usage of nuclear reactors in our cars, planes and kitchens. But does it mean something realistic? The physicists don't care about these externalities at all - they're just writing their publications about existing nuclear processes blindly, because they're used to do so.
Caliban
3 / 5 (2) Jun 26, 2012

atomique,

Despite the glaring lack of any knowledge in most of your comments, this article is not about the financial merits of reprocessing, "profiteering nuclear energy interests", reactor safety, or nuclear security legacy. It's a discussion about potential out-year resource utilization. If renewables simply come up short with demand, coal and petroleum eventually are deemed too harmful, and performance of used nuclear fuel in a repository is an important consideration, then there is a tremendous argument for utilizing used fuel. Whether the market or policy steer it that direction is a complex question. But there are is no simple technological reason not to utilize used nuclear fuel. We may rely on it in the future.


It's actually about ALL that.

As was stated --and then further commented upon-- the technology is already there, in use.

My point is that the industry won't put it to work because of the financial disincentive, or at least not without taxpayer support.