Re-Thinking the Nuclear Option

This blog debated whether to post information about the use of thorium as nuclear fuel. The idea came from a reader’s email:

SV: Do you know much about Thorium and LFTR (Liquid Fluoride Thorium Reactors)? A coworker tweeted this sped up Google talk video (16 minutes). I am wondering if this is for real or just an industry hoodwink. Much less waste, Plentiful resource, safer. Sales pitch?

JS: Well, I know more after viewing the fast pitch. Not a chemical engineer, so lack an appreciation for the frozen plug. The idea of 300 year half-life vs. 10,000 is certainly appealing. Most appealing was the continuous fuel process.

Was scared by the idea of its application to oil shale and other Fischer-Tropsch, looked like a faster ticket to Hell. Bottom line knee jerk response – Green Light it and avoid wasting the heat**.

SV: I liked the low waste and some 300 year half-life products.
* plentiful
* inexpensive fuel preparation
* efficient
* safer self regulating (should be higher on the list under less radioactive products )

Treehugger posts on the topic of Thorium Molten Salt Reactors:

For more info, also refer to posts by Charles Barton:

Schematic of Prismatic Block Nuclear Reactor
Prismatic block HTGRs (High Temperature Graphite Reactors) feature “a fairly standard design comprised of graphite blocks containing ceramic uranium fuel and coolant channels bored into the graphite for cooling.”

** Note: Speaking of using the heat from high temperature nuclear reactors, in the lengthy discussion, which ensued on The Oil Drum after Mr. Baton’s article, Engineer Poet commented:

I suggested some time back that the appropriate place to put nuclear plants was beneath cities so that the exhaust steam could be used for space heat and/or absorption chillers. This would be about as benign as you could get; the spent steam would be at least one loop removed from the reactor itself, and perhaps more. If you were driving an absorption chiller, you’d have another two layers of steel between the steam and living space; a hot water radiator would give you just one, but isn’t that enough?

Anyway, such an endorsement is rather a drastic shift since this blog cautioned that potential pollution from nuclear energy makes the pollution from the Kingston plant spill or Alberta tar sands processing plants look like a walk in the park.

Why such an about face? In the sped-up Google video (we can listen faster than people normally speak), a presenter explains that the Thorium path was eschewed because it was impractical for making atomic weapons. A risk of nuclear power, as Amory Lovins repeatedly has cautioned, is the potential availability of a source for a nuclear weapon. Which is not the case with LFTR.

There still is an element of risk with these high temperature nuclear reactors. dio82 informs:

  1. The coolant has to be absolutely chemically stable at these temperatures. Chemists may correct me if I am wrong, but at these temperatures the only gas that doesn’t react chemically are noble gases. And here the choice for Helium is fairly obvious; it is an exceptionally stable isotope that can’t be turned into an unstable isotope due to neutron capture.
  2. The moderator has to be able to withstand these extreme temperatures. The lightest Atom that can be found that is still solid at these temperatures is Carbon in the form of graphite.
  3. The fuel and more importantly its cladding needs to be exceptionally stable at high temperatures.

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This entry was written by jcwinnie, posted on 2009-12-9 at 7:48 pm, filed under chemistry, design, energy and tagged , , , . Bookmark the permalink. Follow any comments here with the RSS feed for this post. Both comments and trackbacks are currently closed.

7 Comments

  1. jcwinnie
    Posted 2009-12-10 at 2:05 pm | Permalink

    A terrible danger exists in generalization, i.e., “Oh, you endorse nuclear power?” No. Not if it is the existing system or even if newer generation, fast breeder reactors.

    A Reuters headline reads: “Climate concerns put fuel focus back on uranium.” And, this I will maintain is NAG-T (Not A Good Thing). Among the developed and developing countries assembled in Copenhagen for COP15, some want to advocate greater use of uranium. This is despite opposition by environmentalists on safety grounds. The problem with advocating nuclear power as a carbon-free energy solution is the radioactive waste.

    The case for nuclear power “is bolstered by estimates that electricity demand is due to surge by up to two-thirds by 2030.” China and India are two countries that see nuclear power meeting their growing demands for cleaner energy.

    “A gap of almost 12 trillion kilowatt hours needs to be filled by 2030,” said CIBC analyst Ian Parkinson in a research note. “We expect nuclear energy to play a major role in this growth.”

    Most environmentalists are still adamant in their opposition to nuclear energy, arguing that tough problems remain unsolved, such as the threat of nuclear fuel getting into the wrong hands and finding safe storage for spent radioactive waste.

    And, few can appreciate a distinction between uranium-based and thorium-based nuclear power. Fissionable material is fissionable material. Especially confusing is that the use of thorium actually includes uranium, although the milder, safer version.

    Similar to the choice in the earlier 1900′s between electric and internal combustion engines for transportation, a choice was made in the 1950′s to go with uranium-based nuclear power rather than thorium-based. Thus, now, when the alternate path is more appealing, the revision faces strong opposition from existing systems that are in place to pursue the previous choices.

  2. jcwinnie
    Posted 2009-12-11 at 3:05 pm | Permalink

    From Copenhagen, HuffPo contributor Evelyn Leopold reports, “In the search for “green” alternatives to oil or coal, nuclear energy is expected to make a comeback – mainly in Russia, China, India and developing nations.”

    She then rhetorically asks, “Does the relatively cheap electricity and low carbon footprint justify construction costs, radioactive waste and proliferation dangers?” No.

    “If you look at countries like India and China…which are highly reliant on coal I really don’t see us coming to grips with climate change at a global level without nuclear energy playing a role,” said Yvo de Boer, the UN climate chief at the current climate conference in Copenhagen. But he told reporters that nuclear energy could only play a major role “if we can deal with issues of safety, if we can deal with issues of waste and if we can find people that actually want one of these things in their backyard.”

  3. jcwinnie
    Posted 2009-12-17 at 9:51 am | Permalink

    In general, Peak Energy and After Gutenberg agree, “Nukes are Stupid.”

  4. jcwinnie
    Posted 2009-12-22 at 10:12 am | Permalink

    Redditor soreff doesn’t get it; it being the advantages of Thorium as described in Wired Magazine article entitled “Uranium is so last century. Enter Thorium, the New Green Nuke.”

    Yes, thorium is more abundant than uranium, and a lot more abundant than U-235 but…

    • This may be proliferation-resistant, but it isn’t proliferation proof. The U-233 from the Th-232 is still fissile, and can still be used in a bomb (albeit harder to handle because of the gamma radiation).
    • Separating Th-232 from U-233 is a chemical operation, not isotope enrichment, so it is easier to do than making a bomb from natural uranium.
    • There are still fission products – the nuclear waste is still damned dangerous.
    • If the cooling gets screwed up – yes the fission stops (it does so when a water-moderated reactor loses its water too), and yes, since the fuel is liquid to start with, there isn’t an issue with a further melt-down; but there is still the prompt beta decay heat of all of those fission products to worry about. It isn’t as though you can just turn it off and walk away.
    • Just how much better is the long term radioisotope mix from this vs. the uranium-235 or uranium/plutonium fuels? My understanding is that some long-lived transuranics are avoided, but some of the long-lived radiation is just from neutron activation of structural steel. That doesn’t go away.

      Thorium helps. It is certainly less wasteful than burn-the-U-235-and-throw-the-U-238-away. I haven’t seen a solid argument that it helps all that much.

  5. jcwinnie
    Posted 2009-12-22 at 10:20 am | Permalink

    Redditor ElectricRebel addresses a few of the concerns soref mentioned.

    Full disclosure: I have an engineering background, but am not an expert in nuclear engineering. I just know a bit of this stuff from reading papers and watching the Google Tech Talks on thorium.

    Separating Th-232 from U-233 is a chemical operation, not isotope enrichment, so it is easier to do than making a bomb from natural uranium

    The issue isn’t separating Th-232 from U-233, it is separating U-232 from U-233. Some U-232 is generated in the breeding process and it is a hard gamma ray emitter that not only isn’t fissile, but destroys electronics of bombs. Therefore, you need centrifuges, which means you are better off just starting with Uranium ore. It is also significantly more difficult than U-235 or Pu-239 to make weapons with because of the gamma rays. That is why the US did a couple of bomb tests with U-233 and then never worked with it again.

    There are still fission products – the nuclear waste is still damned dangerous

    Yes, but for a much shorter term. If we do the Liquid Fluoride design, then we can use the reactor to bombard the waste with neutrons and change to change their decay series into something with half-lives in the low hundreds of years rather than the many tens of thousands of years. Also, because this is a closed cycle that uses all of the thorium rather than an open cycle (plus enrichment), thousands of times less high level waste is generated. The Google Tech Talks discuss this in detail.

    Also, in general about nuclear waste: I am not worried even if we do generate long term waste because I am confident that future technology will be able to clean it up, as long as we don’t generate an overwhelming amount of it (which is another argument for the thorium cycle). Also, on the danger side: I think we know how to handle the waste really well. As far as I know, US plants haven’t had any radiation poisoning accidents in recent history (although I could be wrong on that). Also, we have very advanced robotics now to handle this stuff, unlike the poor saps working at the Hanford reactor back in the day. Overall, I think the waste is a complication, but something that we have proven we can handle.

    but there is still the prompt beta decay heat of all of those fission products to worry about. It isn’t as though you can just turn it off and walk away

    Look into the freeze plug design used in the Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Lab. If the cooling fails, then the reactor automatically drains the liquid into a non-critical container that has enough heat sink capacity to deal with the beta decay. Of course, there is a lot of work that has to be done to engineer it right, but I think the fundamental solution is there.

    My understanding is that some long-lived transuranics are avoided, but some of the long-lived radiation is just from neutron activation of structural steel.

    This is still an issue, as with all forms of nuclear reactors (including fusion). I believe that there are some materials available to deal with this, but I am not an expert in materials science, so I’d appreciate someone else to comment on the matter.

    Also, my understanding was that the neutron activation for the steel (depending on the particular materials used), was only a problem for a few years. I could be wrong on this though.

    I haven’t seen a solid argument that it helps all that much.

    If you haven’t watched the Google Tech Talks, I highly recommend you do that. They make a convincing case. I’m a very skeptical person and have been trying to find arguments against the LFTR and they all seem to boil down to: the AEC didn’t care about thorium early on because it was useless for making bombs, then TMI happened and funding and excitement for anything nuclear disappeared. On the technical side, it just appears to need some engineering work to get a commercial design going, but there aren’t any major roadblocks that would prevent us from making one in a few years (since Oak Ridge already built a prototype 40 years ago).
    Finally, I’d like to say this: I support nuclear for a number of reasons. It is the most energy dense technology we know of because it extracts energy directly from the strong nuclear force, not chemical or mechanical energy. Nuclear reactors have an extremely high capacity factor (I believe they are the most reliable form of base load we have). It doesn’t emit carbon. And if we use breeding of U-238 or Th-232, then we have enough fuel to last for the foreseeable future.

  6. jcwinnie
    Posted 2010-1-3 at 11:25 am | Permalink

    mrshermanoaks writes:

    When the choices for developing nuclear energy were being made, we went with uranium because it had the byproduct of producing plutonium that could be weaponized. But thorium is safer and easier to work with, and may cause a lot fewer headaches. ‘It’s abundant — the US has at least 175,000 tons of the stuff — and doesn’t require costly processing. It is also extraordinarily efficient as a nuclear fuel. As it decays in a reactor core, its byproducts produce more neutrons per collision than conventional fuel. The more neutrons per collision, the more energy generated, the less total fuel consumed, and the less radioactive nastiness left behind. Even better, Weinberg realized that you could use thorium in an entirely new kind of reactor, one that would have zero risk of meltdown. The design is based on the lab’s finding that thorium dissolves in hot liquid fluoride salts. This fission soup is poured into tubes in the core of the reactor, where the nuclear chain reaction — the billiard balls colliding — happens. The system makes the reactor self-regulating: When the soup gets too hot it expands and flows out of the tubes — slowing fission and eliminating the possibility of another Chernobyl. Any actinide can work in this method, but thorium is particularly well suited because it is so efficient at the high temperatures at which fission occurs in the soup.’ So why are we not building these reactors?

  7. jcwinnie
    Posted 2010-1-26 at 11:50 am | Permalink

    While, in the first comment above, this blog expressed disfavor for newer generation, fast breeder reactors, Steve Kirsch reports that DOE Secretary Steven Chu favors them. “Let’s hope that Chu prevails,” writes the HuffPo contributor. “The fate of the planet is at stake.”

    The White House has proposed barring Energy Department research on fast reactor recycling of nuclear waste and technical support for licensing of small, modular light-water reactors, drawing protests from Energy Secretary Steven Chu that such prohibitions will have broad adverse effects, including hurting the U.S. nuclear industry’s renaissance; crimping U.S. ability to influence other countries’ fast reactor designs to address proliferation concerns; and taking away nuclear waste disposal options that might be considered by the administration’s planned blue-ribbon panel on alternatives to the Yucca Mountain repository.

    In the letter, Chu said he “strongly disagree[s] with the policy direction [proposed by OMB] concerning allowable nuclear energy R&D activities.”

    Chu added: “The OMB [passback] prohibits fast reactor R&D within the [nuclear] fuel cycle R&D program; prohibits light-water licensing and manufacturing support activities associated with small/modular reactors; and directs that the reactor enabling technologies program be renamed ‘advanced concepts’ and be entirely run as an investigator-initiated, competitive process.”

    It’s clear to me that Chu is right and Orszag is wrong. Here are a few reasons, summarized by fast reactor scientist George Stanford, as to why DOE should be building a fast reactor now:

    It seems clear that uranium supply is not a near-term problem, even for thermal reactors. But there are other reasons to forge ahead with fast reactors (such as the IFR). Here are some:

    1. Eighty years of waste from 1000 (1-GWe) reactors would leave enough used fuel for 10 or 20 Yucca Mountains.

    2. The environmental effects of accelerated uranium mining will impinge increasingly on the public’s consciousness. Resistance to uranium mining is already growing.

    3. The accumulating plutonium inventory will, rightly or wrongly, be seen as an ever-increasing proliferation risk,

    4. The multiplying need for uranium enrichment means the spread of centrifuge technology and loss of international control of that technology, with serious proliferation implications.

    5. Since China, India, Russia, et al. are forging ahead with their fast-reactor programs, technological leadership will continue to move in that direction.

    6. The concomitant spread of fuel-processing technology will mean loss of international control of that technology, with further serious proliferation implications.

    7. No nation can make nuclear weapons without either enrichment or reprocessing facilities, regardless of how many reactors it has. The loss of U.S. technological leadership will mean the loss of ability to bring order to the global development and deployment of nuclear technology, with the consequent uninhibited spread of proliferation potential.

    8. The institutional knowledge of the U.S.-developed fast reactor technology is rapidly dying off, accelerating the North American descent to second-class technological status.

    This blog objects to fast reactor technology because it still means highly dangerous waste. One might imagine Secretary Chu supports development because 1) further study is needed and 2) nuclear energy helps fill the gap unmet by clean energy if we actually begin to take the idea of reducing carbon emissions from coal-fired power plants seriously.

One Trackback

  1. By Opportunity Knocks, Opportunity Costs – After Gutenberg on 2010-1-5 at 10:54 pm

    [...] Which relates to a previous assertion by this blog that investing in energy efficiency and renewable energy is better than more nuclear power stations. In general, Peak Energy and After Gutenberg agree, “Nukes are Stupid,” despite the allure from Generation IV reactors, i.e., IFR (Integral Fast Reactor) and LFTR (Liquid Fluoride Thorium Reactors) [...]

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