Joshua PollackThe "Lego Block" Nuclear Reactor

So, looking for something in a nuclear power plant, but not too big and not too expensive? How about a small, modular liquid-metal reactor, provided with its fuel installed? Look no further than the 100 MWe SVBR-100, shipped direct to you by — yes, you guessed it — the Acme company.

According to the New York Times,

Kirill Danilenko, the director of the Russian company, Akme Engineering, said that the technology could be made safe, with no greater risk of meltdown than that at a larger nuclear plant. His vision is that small reactors will become so common that utilities can connect them and “build power plants like Lego sets.”


The Russian company, Akme, is an acronym for atomic complex for small and medium energy and sometimes renders its name in English as Acme.

World Nuclear News reports that the new mini-reactors should be available by 2019. No word on species requirements for buyers.


  1. thermopile (History)


    While the lead-bismuth reactor is a reasonably proven design by Soviet standards (as on the Alfa class subs ), I’m pretty sure such exotic coolants would send the US NRC into apoplexy.

    There are more near term solutions:
    NuScale has a good one
    BWXT’s mPower is a very appealing option from a company who knows how to build stuff.
    Toshiba’s 4S and Hyperion’s nuclear battery are also possibilities, but as a nuclear engineer, I take a dim view of Hyperion’s marketing-heavy and technology-deficient approach.

    But I hope the Acme reactor will find good utility in places more willing to look at exotic coolant materials … the higher power densities are intriguing.

  2. joshua (History)

    Wonderful! This will be so much fun to play with on my new yacht !

    But I wonder if might you have something in the way of Lincoln Logs?

  3. Steven Dolley (History)

    “as a nuclear engineer, I take a dim view of Hyperion’s marketing-heavy and technology-deficient approach”

    What are your specific concerns about the design?

  4. thermopile


    Hyperion is really pushing the edge of reactor design, trying to embrace those things that have plagued other, older reactor designs. Early designs (Molten Salt Reactor, Liquid Metal Fueled Reactor, Aqueous Homogeneous Reactor) had to be shut down prematurely due to fission product release. The French have had containment problems with their liquid-metal-cooled reactors (Phenix and then SuperPhenix); the long-term material science just isn’t there yet for a “Bury it and Forget it” type of system with these designs.

    My biggest concern is with the long-term release of fission products from within the core. The cesium, the rhodium, the technetium … they’re going to plate out somewhere, and I haven’t seen any analysis of how Hyperion is going to handle this, or if it’s going to adversely affect the UH3 fuel from being able to “do its magic” and control core reactivity.

    Mother Nature has lots of tricks up her sleeve when it comes to making things fail in new and interesting ways, PARTICULARLY with respect to long term corrosion. I don’t mean to imply this is a safety or containment concern, I believe it’s a long term operational concern. I doubt they will be able to get the 7 years’ operational life they’re touting.

    If I were a potential investor (which I’m not), I would put a lot more stock in BWXT’s and NuScale’s traditional designs with 5% UO2 fuel and water.

    I’m afraid I don’t know enough to comment on the long term successes of Akme’s Pb-Bi reactor design; to my knowledge, the Soviets never published the results of their end-of-life destructive evaluation tests from the subs. (Not that I would expect them to…)

  5. MB (History)

    It’s clearly nuclear bandwagon time. Note Gates’ serious investment heading into TerraPower and their TWR. Interesting site at Have a look at the bio’s!

    Josh adds: In case there is any confusion, the above comment refers to Bill Gates.

  6. Fred Johnson (History)

    thermopile is obviously not paying attention as Hyperion announced last Fall their UN-fueled fast liquid metal reactor will hit the market first. I’ll take the word of Los Alamos scientists over some anonymous posting.

  7. Yale Simkin (History)

    thermopile – hyperion has modified its vaporware design from uh3 to an even nastier design of 20% uranium nitride with a Rube Goldberg-ish emergency system.

  8. Trevor Pyle (History)

    What about the pebble bed reactor that was talked about ten years ago or so? It sounds like it would be relatively proliferation proof and very safe when it comes to meltdowns…

  9. bradley laing (History)

    —from Huffington Post:

    WASHINGTON — An Iranian nuclear scientist who had been reported missing since last summer has defected to the U.S. and is assisting the CIA in its efforts to undermine Iran’s nuclear program, ABC News reported Tuesday.

    The scientist, Shahram Amiri, has been resettled in the U.S., according to the report.

    The CIA had no comment on the report, a spokesman said.

    President Barack Obama said Tuesday he hopes international sanctions against Iran for pursuing its nuclear ambitions will be in place this spring. Iran maintains that its nuclear research is for peaceful purposes and not to develop weapons

  10. FSB

    Nuclear power is not magic.

    It, too, runs on fuel. Which is limited.

    At present, fossil fuels provide 87 percent of the world’s total energy while nuclear power plants provide just 4.8 percent. (All nuclear power plants currently generate electricity, accounting for about 15 percent of world electricity generation, while fossil fuels produce almost 67 percent of the electricity.)

    The best estimates put the amount of uranium that can be mined economically (what geologists call the reserves) at about 5.5 million metric tons, and according to the International Atomic Energy Agency, today’s nuclear power plants use 70,000 metric tons a year of uranium. At this rate of use, the uranium that could be mined economically would last about 80 years.

    Suppose it were possible to replace all fossil fuels with nuclear power. Suppose that we could use nuclear energy to make liquid and gas fuels to power vehicles, and could do this quickly using conventional nuclear power plants.

    We would have to build enough plants to increase energy production by 17.4 times, which means using 1.2 million tons of uranium ore each year. At that rate of use, the reserves of uranium would be used up in less than five years.

    Nuclear power is a non-solution, especially considering its poor safety and waste record and potential security problems.

    Stop dreaming and get behind renewables.

  11. Josh (History)

    The Shahram Amiri story appeared last year. It wasn’t covered very heavily in the U.S. media — so lightly, in fact, that ABC News seems to think it has a new story. But little in it appears to be new.

  12. Carey Sublette

    There are a number of things that may prevent the deployment of nuclear power on a much larger scale than currently seen. The high capital cost, relative to fossil fuel plants, has been the major factor restricting deployment (and without a carbon tax will continue to do so) and a lack of industrial capacity to build plants is a critical constraint right now.

    But the argument that there isn’t enough uranium to support major expansion needs to be examined a little more closely.

    The phrase FSB uses “can be mined economically” specifically means at a benchmark price of $50/lb U3O8 ($130/kg U). In estimating reserves adopting some benchmark price is mandatory, but one should use caution before assuming that the chose benchmark is an iron ceiling.

    The uranium spot market price has been above this level for a couple of months during the past year, and hit $136/lb in 2007 before the current economic crisis. Further, at $50/lb the contribution of uranium cost to the final electricity cost is only 0.3 cents/kWHr. Even at prices ten times higher, the additional 3 cents/kWHr still leaves nuclear electricity much cheaper than solar electricity and on par with large scale off-shore wind farm proposals.

    Uranium resources that can be exploited are vastly larger than the nominal reserves set at a benchmark price that is becoming a historical curiosity.

  13. FSB

    Carey, yes we can play with prices and change the five years I mentioned into, say, 10 years. Same argument, different number.

    Nuclear Power is not a silver bullet and can only be a dirty, risky, unsafe small part of the energy mix needed going into the future. Better that the smart people involved with it go and work in another field.

  14. Yale Simkin (History)

    …human society is too diverse, national passions too strong, human aggression too deep-seated for peaceful and warlike atoms to stay divorced for too long. We cannot embrace one while abhorring the other; we must learn, if we want to live at all, to live without both… – Jacques Costeau

  15. Mark Pontin (History)

    If FSB wishes to play the ‘there’s not enough uranium game,’ however much uranium is out there — and it’s a lot more than FSB wishes to concede — we can possibly do nuclear transmutation of just about any isotope or, conceivably, any element today. Effective industrial-scale nuclear transmutation is 20-30 years away in terms of most useful ways of working the fuel cycle I can think of.

    I would first, though, consider thorium-based fuel cycles. Thorium (Th-232) isn’t fissile itself, but absorbs slow neutrons to produce uranium-233 (U-233), which is. The irradiated fuel can then be unloaded from the reactor, the U-233 separated from the thorium, and fed back into another reactor as part of a closed fuel cycle. Altogether, Th-232 to U-233 has great advantages over the currently dominant U-235/Pu-239 fuel cycle. To whit: –

    [1] Much better economics in every way: There’s three-four times more thorium than uranium on Earth, and all the thorium mined can be used in a reactor (compared to 0.6 percent of natural uranium). Then, too, U-233 is better than uranium-235/plutonium-239, having a much greater energy density thanks to a higher neutron yield per neutron absorbed. Additionally, as Europe’s MYRRHA project
    is meant to show, feasible industrial-scale reprocessing could allow U-233 to be re-introduced as fuel. Finally, the actual thorium plant designs could be much smaller and more economical to build; the original thorium reactor design was developed in the early 1950s for an aircraft, the US Air Force’s proposed nuclear bomber.

    [2] Much less risk in every way: Thorium fuel cycles produce much less plutonium and other radioactive transuranic elements than uranium fuel cycles. The thorium cycle’s worst waste products remain dangerous for effectively 250 years, rather than thousands – and that’s if the industrial transmutation MYRRHA is meant to develop fails. Furthermore, waste products generated by the thorium cycle could be rendered proliferation-resistant, with no weapons-usable plutonium produced.

  16. FSB

    Excellent point, Mark — I suggest you patent the process and make such a Th reactor. Why post it on the web?

    Did you read the article I linked to? Please do. It ain’t just me. There is not much U to power the world significantly.

  17. Yale Simkin (History)

    A very nice overview by Kanga and von Hippel on

    U-232 and the Proliferation-
    Resistance of U-233 in Spent

    Most interesting is the point they make that a weapon’s core of U-232-contaminated U233, when nestled within a lead (or uranium) tamper/reflector, is a rather small emitter of gamma radiation.

    A second point (not discussed in the essay) is the India-style fuel cycle. U233 and/or reactor grade Pu is used to fuel fast-breeder LM reactors which are used to create super-grade plutonium laundry in the breeding blankets. (plus more U233 in the radial blanket).

  18. Carey Sublette

    Changing the price benchmark by a modest multiple does a little more than change five years to ten. At prices two or three times the IAEA/OECD benchmark even terrestrial resources are probably around five times (25-30 million tons) the currently quoted estimate (though the lowest grade ores require mining operations approaching the scale of coal). But at these same prices it also becomes economic to extract uranium from seawater and the reserves jump to 4 billion tons. Thus five years of supplying all the world’s energy becomes four thousand or so.

    But this “all the world’s energy” criterion is a bit of a red herring (it is a useful yardstick perhaps but not a real scenario). Let us remind ourselves of the time frame in which terrestrial uranium resources would actually be depleted (“peak uranium”). At current consumption rates and yesterdays prices (the long term contract price for uranium has been above the IAEA/OECD benchmark for over three years now) we have an 80 year supply. Doubling world nuclear capacity in 10 years seems impossible (the capital and industrial constraints, and project time lines), and quadrupling it in 20 similarly seems improbable. Replacing all the world’s existing electricity production in 30 years seems very optimistic to me, but even so terrestrial resources alone should support this (with the certain reality of higher prices) for 60 years. So real depletion is several decades off which is a lot of time to shake the bugs out of seawater extraction and build plants. But it won’t happen as long as cheaper sources exist, or until some proliferating country with a coastline wants to slurp up some uranium on the sly (I am betting this is where the technology first sees industrial scale deployment).

    Now my scenario means that nuclear power is not going to conquer global warming, or replace oil, during this century by itself. No technology can do this. But it can take up a fair chunk of burden, along with wind, solar, and biomass (other prospects seem dim).

    BTW – I want to emphasize the extremely strong claim FSB is making. He is asserting that the necessary amount of exploitable uranium to power a large fraction of the world’s economy for more than a few years simply does not exist and this obstacle cannot be overcome. Instead it seems that only a single successful industrial process, a cost-effective uranium ion sponge, is needed to demolish this claimed barrier. This is a far less radical assumption than supposing that commercially viable breeder reactors will appear (and they very well may in time). Like the gas centrifuge before it, one single industrial process really transform the nuclear power and proliferation landscape.

  19. Mark Pontin (History)

    @ Yale Simkin –

    Thanks for the paper by Kanga & Hippel. It’s great work and I hadn’t seen it before.

  20. FSB

    India has been toying (and more) with the Th reactor concept for years. Yes, it is theoretically more proliferation resistant but does not address the waste issue. Th reactors make less waste, but there is still toxic waste. And proliferation resistance discussion do not address dirty bombs for which no Pu in the waste is not a show-stopper. No-one is really worried about terrorists making a nuclear bomb from waste — or they should not be. It is virtually impossible for terrorists to make a nuclear weapon.

    Maybe by 2050 the economics will favor some investment in Th technology over U reactors. Good probability that humanity will have extinguished itself by then, in large part due to not abandoning the magical lure of (U-based) nuclear power.

  21. Mark Pontin (History)

    @ FSB –

    I’m sorry. But I don’t buy Mr. Botkin’s figures in his NY TIMES op-ed. I see various estimates of global uranium reserves and — though, honestly, none of them are fully convincing — they don’t accord with his account. Rather, Mr. Botkin’s and your own comments seem to start from the a priori assumption that nuclear is bad. Given that, you neither know nor feel you need to know anything about developments like new reactors or cleaner fuel cycles.

    Truly identifying in that respect, for instance, is your assumption that Th-232 to U-233 fuel cycle is some fantasy of mine. No. I wish I was that smart, but it’s been around for decades and has been done in a variety of forms. The USAF bomber’s thorium reactor in 1954 used the molten salt approach, but thorium fuel cycle-based systems are also doable via pebble bed reactors and now, after some Japanese experiments last year, via the ADS (Accelerator Driven Systems) approach.

    Why didn’t we take this path before if the designs have already been developed? Primarily because the thorium fuel cycle is a terrible approach if you’re interested in also making nuclear weapons and all your initial expertise in nuclear technology has been aimed towards that end, using uranium fuel cycles. And this was the case with the U.S. and the other 20th century nuclear-capable countries.

    Which brings us to the heart of the problem. The historical fact is that the anti-nuclear activist movement grew out of the nuclear disarmament movement, then was taken up by Greens and other activists across the board. I understand that wasn’t unreasonable under the then-prevailing circumstances. But I would also submit to you that if now an entire generation cannot accept the single energy technology with a proven track record suggesting it could be a solution to global warming and the world’s energy problems, it’s because to do so would entail an almost unbearable recognition: that a very large part of their lives’ work has been fundamentally, disastrously wrong, and by obstructing the transition to nuclear back in the 1970s, they bear direct responsibility both for global warming and the millions dead from coal-related pollution since then.

  22. FSB


    you say:

    “I’m sorry. But I don’t buy Mr. Botkin’s figures in his NY TIMES op-ed. I see various estimates of global uranium reserves and — though, honestly, none of them are fully convincing — they don’t accord with his account. Rather, Mr. Botkin’s and your own comments seem to start from the a priori assumption that nuclear is bad.”

    Fair enough — please send me the references for your figures that disagree with those I quoted.

    And, yes, nuclear power as has been practiced, is bad.

    Bad w/r/t waste, safety and security.

    Theoretically, it is a good energy source, but not practically.

    Nuclear power, as it has been practiced for the last decades, is not a solution to climate change as its risks far outweigh the risks of climate change itself.

    Supporters argue that nuclear power is soft on the environment and that it can provide large sources of affordable power, ready for use when needed. These claims are misleading and highly disputable. There are many reasons why more nuclear power is not a good idea – especially given the existence of viable alternatives in the forms of energy conservation and renewable energy (wind, solar, biomass, geothermal, ethanol, biodiesel, etc.).

    The list of shortcomings regarding nuclear power is long. Here are the highlights:

    Nuclear waste — from actual existing nuclear reactors, not theoretical future Th ones — are radioactive for millennia, with no solution for permanently storing these wastes. Without a permanent solution to storing this waste, nuclear proliferation concerns will never be laid to rest.

    Further, the fact that a fifty-year old industry requires billion of dollars in subsidies and government-backed insurance – as provided by the federal 2005 Energy Policy Act – suggests that nuclear power, a mature industry, cannot stand on its own two feet. That people who otherwise consider themselves conservative republicans support such a wasteful government handout industry is especially disturbing.

    Nuclear energy is historically very expensive. A significant reason for deregulation in California was the high cost of utility-owned nuclear power generation. Construction costs of nuclear power plants were far more than anticipated, causing nuclear power to be the most expensive electricity in California for many years. Now that the construction costs have been paid off, it may appear that the state’s two nuclear power plants are producing power relatively cheaply, but construction costs cannot be simply swept under the rug and forgotten. Be wary when proponents for the new round of nuclear plants argue that capital costs for new plants will be lower. Many of the same arguments were made during the 1970s – and have been shown by history to be patently wrong.

    Proponents argue that nuclear power offers a quick way to substantially reduce our greenhouse gas emissions. While it does produce fewer emissions than coal or natural gas-fired power plants, the emissions are not negligible. One report by Dutch researchers found that nuclear power plants that use high-grade ore (for which supplies are diminishing) emit about 40 percent of the greenhouse gas emissions of a natural gas power plant, from ore refining and plant construction.

    As uranium ore quality decreases, the greenhouse gas emissions rise because it takes more fossil energy to refine the ore. Ditto for Carey’s seawater extraction idea.

    If the renewed interest in nuclear power leads to many new nuclear power plants, these supplies will be exhausted even sooner, leading to steep cost increases for uranium.

    Breeder reactors, used in Europe and Japan, can help extend limited supplies of uranium, but such plants can be unstable and generate the fissionable materials for nuclear weapons.

    To those who advocate nuclear power as an opportunity for greater energy security, I would remind them that nuclear power stations are highly vulnerable to terrorist attacks. Any time a highly concentrated fuel source is created and confined, it gives rise to safety concerns. But nuclear power presents an even greater risk because of its incredibly concentrated nature and the existence of nuclear power plants near population centers – like Diablo Canyon, located near many towns in San Luis Obispo County and endangering also Santa Barbara County. Additionally, it didn’t take terrorists to cause the accidents at Chernobyl or Three Mile Island – it simply took human error.

    It’s time to become smart about our energy policy and realize that long-term energy policies require that we use technologies that are sustainable and don’t damage the environment. Nuclear power does not fit either of these criteria. Energy conservation and renewable energy are here today and can provide cost-effective power that has none of the very significant downsides of nuclear power.


    you say “I want to emphasize the extremely strong claim FSB is making. He is asserting that the necessary amount of exploitable uranium to power a large fraction of the world’s economy for more than a few years simply does not exist and this obstacle cannot be overcome.”

    No, I never said that at all. I am saying that current U reserves (i.e. not including expensive, fossil fuel intensive sea-water extraction that you mention) at even reasonable multiples of current U prices, severely limit the power nuclear can supply going into the future. Minus the large subsidies, nuclear power is already uneconomical.

    The fantasy that nuclear power can be a silver bullet needs to be demolished.

    You say:

    “Now my scenario means that nuclear power is not going to conquer global warming, or replace oil, during this century by itself. No technology can do this. But it can take up a fair chunk of burden, along with wind, solar, and biomass (other prospects seem dim)”

    I have a better idea: zero-out the expensive, subsidy-heavy, dirty, unsafe and dangerous nuclear part of the equation and replace it by conservation.

    Good day gentlemen.

  23. Yale Simkin (History)

    From FSB’s comments above, I don’t think I made my points clearly.
    I think that the thorium cycle is NOT a good barrier to build bombs. It complicates the proliferator’s task, but (IMNVHO) it is not the salvation of a (thankfully) dead industry – the hype notwithstanding. The paper by Kanga and von Hippel was an analysis of the NON-proliferation resistance of the thorium cycle. That’s why I highlighted their point that a hi-z tamper, which a bomb-builder could certainly opt for, makes an excellent shield for the nasty gamma emissions.

    My mention of the India plan was to show that thorium can be directly used in a cycle to produce super-grade plutonium – thus removing any proliferation resistance value to it’s use.

  24. Carey Sublette

    Mark Pontin: I’m sorry. But I don’t buy Mr. Botkin’s figures in his NY TIMES op-ed…

    Botkin’s figures (those he chooses to mention that is) are correct. Note that FSB picked the most extreme scenario Botkin offered, but Botkin does acknowledge that known terrestrial reserves are six times larger (35 million tons) at higher price levels. Of course the possibility of exploiting sea water uranium is not mentioned at all since his argument would collapse at that point.

    To make breeder reactors “go away” as a possibility he plays games with time lines. There aren’t any now, so they cannot “reduce our dependence on fossil fuels now or in the near future” and then parlays that in his next sentence into his conclusion that thus: “there is no way that nuclear power can play a dominant role in the world’s energy supply.”

    This conclusion should be footnoted: *If one first discounts all approaches in which it could play a dominant role.

  25. Carey Sublette

    I am happy to see that FSB has come around to supporting my original post, although he still chooses to frame it as being in opposition.

    I observed that the main obstacle for nuclear power expansion is its high capital cost, which is not going away, but can be offset if carbon sources are penalized (which they should be in any case). FSB concurs that the high costs are the major obstacle to nuclear power expansion.

    And I pointed out that the argument that there simply isn’t enough uranium to supply a large expansion is false, which FSB now concedes in a round about way.

    However FSB is right in pointing out conservation that I omitted from my short list of energy options – it is indeed the cheapest way to “expand” our energy supply.

  26. FSB

    I am happy that Carey and I are in agreement that nuclear is an impractical and expensive power solution for the foreseeable future and that conservation is the smarter option.

    I would differ in that the “main obstacle” is not the measurable expense but the fact that nuclear is dirty and dangerous, which is hard to quantify in dollar terms, but were it to be, it would exceed the capital and fuel cost issue.

    Thank you all for the discussion.

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