Leave a Reply

Your email address will not be published. Required fields are marked *

Subscribe to Comments:


  1. This is a great article on the status of small reactors. As a retired nuclear engineer who has worked in a variety of roles including at a nuclear utility, regulator, and consulting company, I am supportive of the move towards small modular reactors. I agree with the many points raised by Mr. Adams. Let me share some insights that I have observed through the decades. On the Diseconomy of Scale issue: decades ago as a graduate student, my class undertook an exercise on the very topic. Yes, it is true that the overnight cost in terms of dollars per kilowatt of installed capacity decreases as the reactor size increases. But we showed that, at high borrowing costs during construction and commissioning, the compounded interest during construction of large reactors could more than offset this economy especially as construction time stretches out the commissioning date. On the other hand, operations and maintenance costs, normalized for unit size and power generation, can at some point overwhelm all other costs including fuel and depreciation. It is no coincidence that the first units to permanently shut down have been the smaller, single unit sites where labor costs have been relatively high — a fixed O&M budget divided by too few megawatt-hours produced will come back to hurt the economics at some point (think of the increasing challenges facing Yankee Rowe at 186 MWe, although that unit was primarily shut down at the time because of reactor pressure vessel embrittlement uncertainty issues). Take one particular area, security, as an example. Without getting into the specifics of safeguards information, a situation where at current commercial reactors the number of security personnel can be greater than the operations staff is not a business model that could be successfully carried over to the fleet of smaller reactors. This is also the case for emergency planning cost. Siting is yet another matter: easier to license and construct fewer large reactor units on a moderate number of sites than thousands of units on hundreds of sites distributed around the country. Each site can be its own lure for obstructionism. A paradigm shift is necessary if small, modular reactors are to become the predominant business model, I believe.

    1. Donald:

      You are correct in stating that we need to have a paradigm shift to ensure small modular reactor success. We need to push for answers and successes that keep the already shifting paradigm on track.

      With security, there are solid answers being developed. Many of the SMR projects I’ve been reviewing take the challenge seriously and have incorporated security by design in ways that will seriously reduce the required security manpower. Unlike conventional reactors that were built many years before the increased ratcheting requirements in force today, modern power plant designs protect critical areas and provide clear sight lines. They incorporate modern security monitoring systems with sensors and cameras….

      They’re also working on changing security paradigms by explaining how a large, heavily armed guard force capable of withstanding force on force drills can add more vulnerability than it removes.

      Site licensing will also need to change. Generic environmental impact assessments for small reactors would help. Replacing coal plants with reactors should be given the credit it deserves as an improvement to the local environment, for example.

      There’s lots of work to do. I hope you find the time to continue making a positive contribution to the discussion.

  2. Its also easier for small reactors to be deployed on floating barges for the offshore production of electricity and desalinated water and even the remote ocean production of synthetic fertilizers (ammonia) and fuel (methanol, gasoline, and jet fuel).

    Methanol can be used to replace marine fuel for ships modified to use methanol. Methanol can also replace natural gas in natural gas electric power plants cheaply modified to use methanol. In both systems, the CO2 can be captured and recycled to produce more methanol through nuclear energy.

  3. Wow that is really a problem. We might have 2 football fields of slightly used uranium. Show me a problem that actually kills some folks.

    The reason I am excited about SMR’s especially “micro” reactors is that they would scatter a bunch of reactors all over the place. This would increase their acceptance greatly! We need thousands of reactors of all sizes to power a fully electric grid and potentially produce syn fuels. If small reactors get started we will be looking at hundreds of them in fairly short order. A product can be improved a project can only be completed.

    Some of the reactors will be working in the fast breeder range using the left over actinides the thermal reactors will be producing.

  4. What would encourage the construction of small modular reactors?
    What caused the closure of many reactors in the United States?

    It was natural gas.

    It seems not that long ago that there was to be a nuclear renaissance. Natural gas prices were high and there was a buzz about more nuclear plants.

    Then the fracking boom hit and we were promised ample natural gas for the next 50 years. Natural gas was cheap. Coal plants began to close like falling dominoes. Nuclear plants followed the closures with closures of their own. Combined cycle natural gas plants offered cleaner operation with a far smaller operating crew for the same megawatt output. These were built all over the US. This raised the demand for natural gas. American industry also used the abundant natural gas for various productive activities. Natural gas lowered the greenhouse gas emissions for the US utility industry. Life was good.

    Now it is 2022 and perhaps we are seeing the beginnings of the end of the natural gas party. Gas prices have been rising. Some gas is being sold to Europe as LNG to make up for Russian gas losses. Can we expect these prices to fall soon? See EIA link.


    Could the rising price of natural gas cause an attempt to actually build some of these small modular reactors instead of just talking about them?

    In addition to this even conservatives have shifted their stance on global warming in recent years to grudgingly accept it as reality.

  5. Many of Donald’s concerns, about costs of security, siting, and emergency planning, could be addressed or alleviated by placing multiple SMR units on a single site. That’s what NuScale is doing, at UAMPS, etc..

    Also, with respect to emergency planning, isn’t it the case that many SMRs have a much smaller EPZ, perhaps even the plant site boundary? The much lower potential release for SMRs should reduce EP costs. My understanding was that NRC is receptive to greatly reduced EPZs.

  6. Eino:

    I’d add something else to your list of pressures pushing natural gas demand (and prices) up. Our first LNG export shipment took place in 2015. US has moved rapidly to top of leader board among LNG exporters. When all facilities are running, we export about 11 bcf/day. That’s ~10% of our production leaving US shores each day.

    Much higher prices in international market. I don’t begrudge suppliers who are seeking most profitable markets.

  7. Thanks Rod for the excellent rebuttal of the arguments made
    by Krall et. al. in their paper against SMR designs, especially
    their explicit ignorance of potential advantages made possible
    by recycling and reuse, as they have said, “because these treatments
    will not eliminate the need for the storage, transportation, treatment,
    and disposal of radioactive materials.”.

    Perhaps Krall et. al. have not heard about Deep Isolation’s approach
    to nuclear waste disposal using deep borehole technology, which
    seems quite capable of addressing all of the issues they raised.

    Perhaps Krall et. al. have also ignored the effects of reprocessing
    and storing highly radioactive fission products separately from
    reusable fuels. Those effects include the reduction of required
    storage lifetimes of fission products by 3 orders of magnitude,
    which can greatly reduce the complexity of deep borehole siting

  8. Licensing seems to be the biggest obstacle right now, particularly when it comes to Gen IV designs, which is big part of why virtually all orders for new reactors globally are for LWR’s. One need look no further than the CRBR site, now proposed to be the site for a BWRX-300. Probably the saddest commentary anywhere on the complete and utter failure to move beyond the LWR. You also see it in the UK where AGR’s are being replaced with PWR’s. Technological regression on this scale will inevitably result in the fission industry’s inability to compete long term. The ~33% thermal efficiency and sub-5% fuel utilization characteristic of LWR’s will all but guarantee it.

    1. AGRs get miserable fuel utilization since the clad is stainless steel and achieve about 37% of PWR discharge burnup. That is not to say that CO2 cooled systems have no future, but AGRs did not pan out to be competitive with the pwr and that’s why the design did not proliferate globally. I’m a fan of the concept, and I believe there is a Gen 4 in there somewhere, but it is not in the running. None of the Gen 4 are a leap in operability or cost; all things considered (i.e. fuel handling, gaseous waste, etc. for MSR, SFR) not a safe bet for a sure investment…. Thus PWRs are built in the developing world.

      1. The AGR unique selling point was online refuelling and hence higher availability (I realise other reactors like CANDU can be refuelled online but PWRs can’t). The higher availability didn’t work out as PWRs got much slicker at refuelling. Add the larger plant required for single phase gas as a primary coolant, larger if lower pressure reactor chambers and larger overall buildings and AGRs lost.

        1. I imagine the desire to power Britain with British technology was among the main selling points for the AGR; additionally, the local talent probably had desire/direction to recoup/build-upon some MAGNOX sunk cost as well. Most power reactor concepts other than the LWRs have minimal excess reactivity and require frequent or constant fuel handling. The tremendous excess reactivity of LWRs at < 5% enrichment is a virtue of these reactors semantically similar to "energy storage" – it has few downsides (mostly in analytical accident scenarios). Those who extoll the virtues of Gen4 could better understand how LWRs are the benchmark, setting the bar quite high for ease/cost of operations, safety, reliability, waste volume, etc.. They are no more 'dinosaurs' than commercial airliners, which share the general architecture of military airplanes developed prior to 1950. We don't see widespread criticism of airplane/automobile manufacturers for failing to reimagine their incrementally improved designs…, but ‘futurists’ are quick to criticize the LWRs. The appeal to novelty fallacy (e.g. SMRs, Gen4) adds another confounding distraction in a public discussion that hasn't sufficiently ripened; we haven’t had that “pain at the meter” to spur new construction. Perhaps successive generations will tolerate a slowly reduced standard of living, reserving pain for those who once kept their homes at 20°C and sipped plastic straws… there could be ANOTHER new normal where pro nuclear folks (like myself) remain frustrated.

  9. Factory-based assembly and disassembly of SMRs would seem to provide an opportunity for
    closed fuel cycles based on used fuel reprocessing, depending on the regulatory status
    of reprocessing. Recently I’ve heard in a webcast talk (given by Zabrina Johal of General
    Atomics) that reprocessing is forbidden in the US due to “weapons proliferation concerns”.

    What is the current US regulatory status of reprocessing? Would reprocessing of used
    fuel in an SMR factory site be forbidden by current regulations even though recycled fuel
    is only used in the vendor’s reactors? If so, would US Government action (e.g., by the DOE)
    be needed to overcome the prohibition in order to permit reprocessing in SMRs?

  10. Zabrina Johal of General Atomics is also a board member of the National Museum
    of Nuclear Science and History in Albuquerque NM, which will be the venue in Oct 2022
    of the 11th Thorium Energy Alliance Conference (TEAC 11). I’ve sent the museum a
    question that I hope will be forwarded to Ms. Johal, asking for the details of the
    “weapons proliferation concerns”.

    AFAICT the concerns may be related to transportation or trading of MOX fuels which
    conceivably might raise concerns about weapons proliferation. But concerns about
    weapons proliferation raised by secure in-house reprocessing as part of factory based
    SMR assembly and disassembly? Not so much. AFAICT.

    If I haven’t received a reply from either Ms. Johal or someone on the staff of the National
    Museum, perhaps Rod might want to try to contact her directly at TEAC 11 where he is
    listed as an expected attendee.

    Based on her talk, Ms Johal’s company is an all-in supporter of nuclear fusion (thermally
    hot variety). Perhaps Rod might also want to ask her how long she expects the transition
    to take from ITER ignition (millions of degrees Celsius for a few msec) to 24x7x52 reliable
    clean energy at scales comparable to those projected for fission-based SMRs. 🙂

  11. When we find that Krall et al. use the loaded word, “waste” 99 times, and the aggressively loaded term, “spent fuel”, “SNF” 110 times, it is time to check where these guys are coming from. All three authors are members of the “Center for International Security and Cooperation”, whose website declares that “Since the beginning, one of our key goal [sic] has been to reduce nuclear risk…” They seem to believe that they could stamp out nuclear war by obstructing fuel reprocessing in the US. To be wary of giving credence to such voices, we should avoid using the word “waste” and never speak of fuel as “spent”.

    Ironically, they point to Toshiba’s 4S , which can be configured as a plutonium burner, itself a solution to their fear of ever-accumulating “nuclear waste”.

  12. Actually I’m a fan of the concept of AGRs and one of my favorite advanced reactor designs is an AGR, a micro-modular reactor (MMR) design by Ultra Safe Nuclear Corp (https://usnc.com). It’s helium cooled, TRISO fueled, and seems designed especially well for remote communities and mining sites (think coal-mining replacement). Among other things, it avoids corrosion issues associated with molten salt fueled reactors. Not sure how they deal with reactivity swings associated with xenon-135 generation.

    Like other SMRs, they have passive safety, factory-based assembly and disassembly, and unlike others, they’re using 3D printing to lower fuel manufacturing costs.They’ve just opened a fuel-manufacturing site this month in Oak Ridge, Tennessee.

    The main limitation I see is that their TRISO fuel design makes reprocessing even more expensive. But if reprocessing is off limits in USA due to old
    NRC regulations intended to block manufacture and trading of MOX fuels, it might make sense to consider closed open-pit coal mines as deep borehole sites for used fuel disposal.

    What do you think?

    1. Scaryjello,
      I should have added the context to the above comment that it
      was all in response to your previous largely positive comment on

      [I assumed that since I initiated the comment using the ‘Reply’
      button that my response would be placed in-line with yours.]

Recent Comments from our Readers

  1. Avatar
  2. Avatar
  3. Avatar
  4. Avatar
  5. Avatar

Similar Posts