Physical Insights

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Nuclear fuel recycling in the United States

with 3 comments

Earlier this month an editorial was posted on GreenvilleOnline.com titled Nuclear reprocessing is risky and impractical, laying out the case against recycling of nuclear fuels (or at least the case against conventional methods for recycling of conventional nuclear fuels). (Thanks to Atomic Insights for the story tip.)

The editorial states:

Nuclear reprocessing separates plutonium from radioactive waste so that it can be reused to generate additional energy. However, reprocessing also has an unfortunate side effect: It dramatically increases the volume of radioactive waste.

Of course, if the alternative to nuclear fuel recycling is to take all the used fuel and label it as supposed “waste” material, and of course that is the alternative, then it’s a universally accepted fact that of course recycling of the nuclear fuel reduces the volume of material that is considered “waste”.

Typical used fuel from a typical LWR with a LEU fuel consists of approximately 96% uranium-238 and 235, which is completely unchanged in the reactor from the original fuel, about 3% of fission product nuclides, about 1% of plutonium, about half of which is plutonium-239 and half of which is comprised of other plutonium nuclides, and small trace quantities of other actinides, including a little U-236, U-232, Np-237, Am-241 and what have you.

Even if nuclear reprocessing involves only taking the uranium from that nuclear fuel, then immediately, with uranium separation alone, you’ve removed 96% of the mass of the radioactive “waste” that you need to deal with – and that’s without any consideration of the valuable, useful materials which constitute the other four percent.

If “nuclear waste” is such a terrible concern, the the first thing that should be done is to make sure we’re not wasting it.

The separation of plutonium is not necessary in any way for the use of nuclear energy, nor is it required at any point for the efficient recycling of used uranium fuels. The separation of plutonium, contrary to popular belief, is not the point of nuclear recycling. Separation of plutonium is an integral part of nuclear weapon building, and it is certain technologies which were developed for this latter purpose which have, historically, been applied to the recycling of power reactors fuels.

To construct a nuclear fission weapon from plutonium does indeed require the chemical separation of pure plutonium from uranium irradiated within a nuclear reactor – but that’s the only thing that requires separation of plutonium. This is why separation of plutonium, or the possibility of it, seems to be viewed with distrust and suspicion, especially at the Savannah River Site, perhaps, given its historical mission of the production of weaponisable plutonium via nuclear reactors and PUREX extraction.

Even if you want to use plutonium from used civilian reactor fuel efficiently, and recycle it back into the recycled nuclear fuel, where it serves as a potent, valuable energy source, chemical separation of plutonium is not needed. Even though most established, mature efforts for the recycling of nuclear fuels at the industrial scale involve the PUREX process, which was designed and established specifically to support the production of separated plutonium for nuclear weapons, there is no reason why this process is essential at all. It’s quite straightforward to modify the chemistry of the solvent extraction process so that the plutonium is kept combined with the other actinides, so that this material can be recycled into new nuclear fuel without any material being produced that presents any proliferation risk. That is what is done with the COEX or DIAMEX chemical processes, and what can be done even better via pyroprocessing or in-situ separation of nuclear poisons in a molten salt reactor.

Even if the potential for diversion and weaponisable plutonium was considered so grave that we were insistent of taking the plutonium and disposing of it in some kind of deep geological repository, this would only constitute 1% of the fuel – so, we wouldn’t be losing much of the fuel, really. However, plutonium-239 is a moderately long lived nuclide – with a half-life of 24,400 years, it doesn’t just go away overnight if put in a geological repository. So, in decades to come, the material could still be removed, and weaponised.

The only proper way to get rid of plutonium, if you’re really concerned about nuclear weapons proliferation, is to fission it in a nuclear reactor – and, lo and behold, you get plenty of clean, safe energy to boot, at the same time.

According to the Union of Concerned Scientists, “After reprocessing … the total volume of nuclear waste will have been increased by a factor of twenty or more ….”

Of course, that’s simply absurd. What sort of definition of reprocessing are they using? What evidence is provided for such a claim?

For instance, discharges of iodine-129, a very long-lived carcinogen, have contaminated the shores of Denmark and Norway at levels 1,000 times higher than nuclear weapons fallout.

Well, does that tell us anything? What is the background dose rate to the public as a result of the nuclear weapons fallout, and what is the contribution added to the dose rate to the public as a result of nuclear fuel reprocessing?

Health studies indicate that significant excess childhood cancers have occurred near French and English reprocessing plants.

Is there any peer-reviewed, scientifically motivated, literature which demonstrates the existence of such excess childhood cancers, and demonstrates, or even reasonably motivates, a causal connection between the two?

In 2003, for example, researchers from Harvard’s Kennedy School of Government said that reprocessing costs more than twice as much as safe, on-site interim storage of nuclear waste.

The report cited, from the Belfer Center for Science & International Affairs at Harvard University, The Economics of Reprocessing vs. Direct Disposal of Spent Nuclear Fuel, states:

At a uranium price of $40/kgU (comparable to current prices), reprocessing and recycling at a reprocessing price of $1000/kgHM would increase the cost of nuclear electricity by 1.3 mills/kWh. Since the total back-end cost for the direct disposal is in the range of 1.5 mills/kgWh, this represents more than an 80% increase in the costs attributable to spent fuel management (after taking account of appropriate credits or charges for recovered plutonium and uranium from reprocessing).

Furthermore, the editorial’s authors continue with much the same assertion:

In 2007, the National Academies of Science (NAS) noted that no reprocessing technology currently on the table “is at a stage of reliability and understanding that would justify commercial-scale construction” and the report therefore concluded “there is no economic justification for going forward with this program at anything approaching a commercial scale.”

The nuclear industry has reached a similar conclusion. A 2007 report by the Keystone Center, underwritten by various utility companies, said “reprocessing of spent fuel will not be cost-effective in the foreseeable future.”

The “reprocessing is not economically competitive” argument basically boils down to the idea that recycling the used fuel is more expensive than the inefficient, once-through use of newly mined uranium.

People are frequently concerned about the environmental intensiveness of uranium mining and the handling of radioactive wastes from nuclear power – and yet recycling and efficient re-use of nuclear fuels minimise the requirement for both of these things. To me, the argument against recycling because recycling costs more is ridiculous, and it’s essentially equivalent to eschewing the use of alternative energy systems in favor of more coal, because coal is cheaper.

Written by Luke Weston

September 16, 2008 at 11:49 am

3 Responses

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  1. Out of curosity, what is the cost of mining “fresh” uranium, as opposed to producing MOX from reprocessing? I am not againt uranium reprocessing at all, seeing as how nuclear “waste” contains 90% usable fuel. Do you know of a link that provides an economic asessment of reprocessing?

    The only reason I am asking about this is that I am wondering on what sort of incentive exists for the US government to start reprocessing its nuclear material rather than burying it at Yucca Mountain aside from the fact that it reduces the total volume of waste produced. The US government and its citizens are still very radiophobic, so I am not sure how you would approach this issue. Also, I have heard of a new technology known as “pyro-reprocessing” that is supposed to be cheaper than PUREX. How does it differ from the PUREX method? Have any countries started utilizing it?

    Neurovore

    September 16, 2008 at 10:31 pm

  2. Neurovore,

    http://www.wise-uranium.org/nfcc.html has a nice and handy calculator for calculating the cost of fuel fabricated from fresh U. Using all their defaults, 1t enriched U costs around 4.5M USD over its life cycle.

    I think part of the mindblock over reprocessing arises out of (IMO spurious) concerns that weapons-grade Pu can easily be seperated from SNF. The other part is because conventional, commercially deployed processes are aqueous, producing significant amounts of low and medium level waste (the reactants used in the reprocessing are not exactly chemically benign, either), although AREVA et al have made significant strides in reducing said waste through their experience.

    http://www.wise-uranium.org/nfccr.html is another handy little gizmo for evaluating comparative costs of various fuel cycle strategies – using their defaults and shooting for 1t enriched fuel fabricated from repU, the comparative costs come out close (355k USD for natU, 347k for repU) enough to be called a wash, considering the cost of conventional reprocessing plant.

    Pyroprocessing, as the name implies, uses heat (and a couple of chemicals), to seperate out the actinides and fission products. The Argonne process electrorefines the actinides out together for fabrication into fuel, not individually seperating them, while bundling the fission products off for disposal.

    Flouride volatility, as used in MSRE and proposed for LFTR, instead chooses a system that is simple enough to be used online (as proved out in MSRE) – it uses the salt heat plus judicious flourination to first form volatile flourides – the majority of FPs form solid flourides and drop out the bottom, while transition metals and halogens accompany the uranium, plutonium and other actinide flourides out into the distillation unit. Simple fractional distillation seperates things out based on boiling point, with the FPs going to waste and the actinides going around again, either as refabricated solid fuel or directly in a liquid fuel loop.

    I am not aware of any commercial pyroprocessing operations, unfortunately.

    fnord

    September 23, 2008 at 5:21 am

  3. Thank you for answering my questions. I am very interested in the concept of molten salt reactors, even though the technology is practically dead and buried here in the US. It will probably remain so for the foreseeable future because of political roadblocks to nuclear power. There is also the fact that if anybody builds a molten salt reactor here, the NRC (Nuclear Regulatory Commission) which is infamous for obstructive red tape will probably refuse to grant it an operating license.

    Neurovore

    October 3, 2008 at 4:12 am


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