34 ms·

NRC Certifies First U.S. Small Modular Reactor Design

588 points by g0xA52A2A 4y ago

roomey 4y ago
Would love to know about expected failure modes or this reactor type. Is there any info on this?
- alexb_ 4y ago
  You can read the safety evaluation here: https://www.nrc.gov/reactors/new-reactors/smr/licensing-activities/nuscale/ser-open-items.html https://www.nrc.gov/reactors/new-reactors/smr/licensing-acti...
- cratermoon 4y ago
  https://thebulletin.org/premium/2021-07/can-small-modular-reactors-help-mitigate-climate-change/ https://thebulletin.org/premium/2021-07/can-small-modular-re...
- AtlasBarfed 4y ago
  "https://www.youtube.com/watch?v=vU-IlqiP4sU https://www.youtube.com/watch?v=vU-IlqiP4sU" Well, it says its a LWR, video says "fuel rods", which means solid rods and meltdown risk. Eh. If it's a solid fuel rod, then if you get a runaway reaction, and if circumstances mean the safety systems go offline (see: Fukushima) then meltdown. Contrast this with something like LFTR: the liquid fuel needs to stay in a certain shape/containment/vessel to maintain criticality. If it starts overreacting/heating, the "plug" at the bottom of the containment melts and the liquid flows into a shallow distributed pool that, per nuclear physics, is impossible to maintain criticality. That type of system is inherently meltdown-proof, even if all the systems go offline, the plug will melt. You know, assuming gravity still works. A pebble bed, where the solid fuel rod is instead a bunch of solid pellets, but if they get too hot you can similarly melt a plug and the pellets fall into a shape that likewise wouldn't stay critical, might also be similarly meltdown-proof, but I haven't read nearly as much on pebble bed designs. But a solid fuel rod? Nope.
  - acidburnNSA 4y ago
    Nuclear engineer here. That's not quite how it all works. Solid vs. liquid fuel is not tied directly to reactivity stability, as quantified in the power coefficient of reactivity. If it goes up in power, you want the chain reaction to naturally go down. In solid fueled reactors, this is usually accomplished via the moderator. If the moderator temperature goes up, it reduced in density, thereby reducing the overall neutron moderation in the core. Thus, fewer neutrons make it to to the energy range that causes fission. Thus, reactivity goes down and the reaction stops. This is inherently stable, just like fuel density in a fluid fuel reactor going down and reducing the overall fission rate. LFTRs are pre-melted. You melt 100% of the core and then bring it critical. That's a lot of pretty mobile fission products! As for the melt plug, that's also a false solution. Given that achieving subcriticality is trivial in modern solid and fluid fuel reactors, the challenge in an accident is afterglow heat removal. As you may know, the plants at Fukushima had all rods in and were fully subcritical an hour before the tsunami hit). But when they lost afterglow heat removal, it still melted some containment barriers. Same can happen with fluid fuel, regardless of whether or not you've moved it from one tank to another. Fluid fuel is not the panacea many people want to think it is. Passive afterglow heat removal is the thing that lets reactors of any fuel form be safer than today's typical reactors, which generally require backup power to run the cooling systems. If you use certain molten salt, liquid sodium metal, liquid lead metal, etc. cooling configurations you can achieve indefinite heat removal without any external power. That reduces core damage frequencies by about 100x from modern large LWRs. Again, regardless of fuel form. That said, 100x safer than how safe current nuclear is is kind of just playing with very small numbers. Fossil and biofuel combustion kills 8 million per year from particulate emissions, according to the WHO, and also cause climate change. So we should just be building hundreds of regular large water cooled reactors now and then switch over to fancier cooling ones later, and also breeders that are ~infinitely sustainable for the long term.
    - Symmetry 4y ago
      For people who don't know this stuff, like myself a few years ago: When a uranium atom is hit by a neutron some of the will split immediately releasing new neutrons but some of them will go into an unstable state and then split some period of time later. If the instantaneous splits are enough to keep the reaction going that's called a "prompt critical" configuration and usually seen only in atomic weapons. If the neutrons released by both the immediate reactions and the delayed reactions are enough to keep the reaction going that's only "critical." Because there are many atoms in the reactor that have been hit by neutrons and are unstable but haven't split yet a reactor continues to release a lot of heat even when it's no long critical, somewhere on the order of 10% as much power as when it was fully on.
- p1mrx 4y ago
  Here's a presentation on their approach to safety: https://www.youtube.com/watch?v=JhrxFCtCPUo&t=2360s https://www.youtube.com/watch?v=JhrxFCtCPUo&t=2360s They estimate that the risk of core damage is 3-5 orders of magnitude lower than traditional nuclear plants.
LatteLazy 4y ago
It's easy to get certified. Now they have to get a few hundred customers and local planning permissions...
- foota 4y ago
  Aren't these factory built? Seems like they could start building and then work out buyers if they're as promising as people make out.
  - LatteLazy 4y ago
    That's fine if you have a few 10s of billions to risk building products that might never be bought. There are 2 key issues here: you have to convince people these will work for a decade plus without issue despite being new AND you have to convince a large number of people (companies, municipalities etc) (>100 to make the factory viable and get the economies of scale) who actually have the cash to buy them. This is a key moat for a lot of tech: anyone could design a decent airliner. Can you convince enough airlines to order them to make it viable to mass manufacturer them, despite having no name or track record? Hence Boeing and Airbus remain the only games in town (and Airbus only got there with a lot of state assistance).
  - Overtonwindow 4y ago
    I think what that person means is that to get this actually built, is likely going to take at least 5 to 10 years of regulatory and government action. On the local level. That's not counting anyone that might throw up roadblocks, such as environmental, and safety. That could easily extend this out another five or 10 years. If a company wanted to build this reactor today, speaking as a government bureaucrat, you are looking at least 10 years before they even break ground.
    - justahuman74 4y ago
      Are there places were they'd receive less regulation, such as on federal land or a military base?
alexb_ 4y ago
Stupid question: the article says that each module can produce 50 megawatts. What is the time of that number? Like how many people can have their energy needs met by one module?
- xyzzyz 4y ago
  A typical household uses something on the order of 1-2 MWh of power a month. This is something like 2-3 KW on average. 1 MW can thus support something like 300-500 households, and 50 MW can support 15000-25000 households, i.e. small to medium size town.
  - LinuxBender 4y ago
    That may suffice for where they are installing the first one. [1] The county has 19k people. I assume it will be tied into the grid to shed some load from the other power plants. [1] - https://en.wikipedia.org/wiki/Lincoln_County,_Wyoming https://en.wikipedia.org/wiki/Lincoln_County,_Wyoming
- nynx 4y ago
  Watts is a measure of energy over time.
  - deleted 4y ago
    [deleted]
  - kube-system 4y ago
    [deleted]
    - coder543 4y ago
      Technically, the person you replied to is correct. Energy / time (energy over time) is power. Power * time is energy. If you had a battery with 20kWh and it was empty after two hours, you would know that it was providing 10kW, which is a measure of the energy released over time, aka. average power. I don't think nynx's comment made things much clearer to anyone, though.
giantg2 4y ago
Meh, old reactor tech with new "engineered" safety features. I would have liked to see stuff more like FAST or slow wave reactors with inherent physics based safety features.
- PaulHoule 4y ago
  A big part of the problem with today's reactors is that they are full of water which requires huge heat exchangers (often bigger than the reaction vessel but still safety critical) and have a huge steam turbine. Even if heat were free you'd have a hard time making the steam turbine powerset competitive in 2023. Nuclear might be able to compete if we can get rid of the water. In Japan they are talking about producing hydrogen directly with thermochemistry, no powerset at all. There is also talk about coupling fast reactors or molten salt reactors to this kind of powerset https://www.powermag.com/what-are-supercritical-co2-power-cycles/ https://www.powermag.com/what-are-supercritical-co2-power-cy... The claimed price of a NuScale reactor isn't going to beat a large LWR but it might possibly be able to build at the quote that NuScale quotes, whereas the large LWR struggles. If you want "the power to save the Earth" you have to get costs down and reactors that can do that are still a decade + out.
  - giantg2 4y ago
    I'll have to look up the hydrogen one. I know the only DOE work I've heard of in the US is still hydrolysis. I thought they have small scale modupar FAST reactors. I would hope they would be similar on price, or at least quote accuracy.
    - scythe 4y ago
      Thermochemical hydrogen — solar or nuclear — has been studied for a while. The simulation thermodynamic efficiency numbers are excellent (beating electricity generation by 1.5-2x), but the reaction cycles in practice tend to leak process chemicals or corrode equipment too quickly to be sustainable (even losing, e.g., 0.1% of your iodine per cycle is unacceptable). I believe Japan is considering a reactor made of tantalum. Canada started such a project in 2010 that was supposed to be online by 2016ish but has continued hitting roadblocks.
pkaye 4y ago
This video is a tour of a NuScale facility and control room. https://www.youtube.com/watch?v=brr5j50umYA https://www.youtube.com/watch?v=brr5j50umYA
- programd 4y ago
  Looking at the control room displays they use imperial units all over the place - lb/ft/F. I'm very surprised that none of that stuff is metric. I wonder if this is part of some regulatory requirement.
  - comicjk 4y ago
    These old units are common in engineering applications across North America, the US especially. When I was in chemical engineering school, we had to be effectively bilingual in terms of units. We even used some bizarre units like the lb-mol, defined as the number of atoms in 12 lbs of carbon-12 (ie 454 times more than a gram mol).
pfdietz 4y ago
NuScale recently announced large cost increases at the project with UAMPS. The cost per unit of capacity is now on par with the new reactors at Vogtle (~$20/W). This is outside the range at which the project could be competitive. https://ieefa.org/resources/eye-popping-new-cost-estimates-released-nuscale-small-modular-reactor https://ieefa.org/resources/eye-popping-new-cost-estimates-r...
- prottog 4y ago
  To put in other units: a rise from previous targets of $58/MWh to $89/MWh, more than 50%, not including a $30/MWh subsidy (so the true cost is actually $119/MWh). To be fair, it says the cost increases are mainly due to the rise in construction material prices as well as financing costs; nothing inherent to nuclear power or the novel technology itself.
  - timerol 4y ago
    Producer price index on steel pipe and structural steel are bonkers: https://fred.stlouisfed.org/series/PCU3312103312100 https://fred.stlouisfed.org/series/PCU3312103312100 and https://fred.stlouisfed.org/series/PCU33231233231211 https://fred.stlouisfed.org/series/PCU33231233231211
  - coder543 4y ago
    To provide more context, wind and solar were both in the low $30's/MWh of LCOE (levelized cost of energy) 3 years ago[0], with that number predicted to continue falling rapidly. Combined cycle (natural gas) is a bit higher[1] than solar and wind, with that number expected to rise over time, and I'm fairly sure the current numbers don't really reflect the substantial cost of the carbon emissions, which we will all have to pay for sooner or later. Either way, the number utilities see is currently much lower than SMRs. I'm pretty sure every prediction I've ever seen for how quickly the cost of wind and solar will fall has underestimated the speed in retrospect. That's the kind of thing these reactors have to compete with. Grids have also repeatedly been shown to handle more renewables than every previous prediction would make, and we haven't hit the limit. At this point, fossil fuel sources more frequently a source of blackouts than than renewables from everything I've seen, despite certain people blaming renewables at every turn. What we need is more energy storage, whether that's in the form of traditional batteries or more novel forms of energy storage. I think nuclear is a fine source of energy if you have it, but evidence over the last several decades shows that it is virtually impossible to build for myriad reasons. The Vogtle nuclear reactors have been one giant boondoggle. New nuclear is not cost competitive, unfortunately. This was also an interesting article yesterday: https://cleantechnica.com/2023/01/19/michael-bloomberg-backs-renewable-energy-in-new-op-ed/ https://cleantechnica.com/2023/01/19/michael-bloomberg-backs... [0]: https://www.eenews.net/articles/doe-heres-where-renewable-costs-are-heading/ https://www.eenews.net/articles/doe-heres-where-renewable-co... [1]: https://www.eia.gov/todayinenergy/detail.php?id=46856 https://www.eia.gov/todayinenergy/detail.php?id=46856
mindslight 4y ago
Does this qualify for the 30% residential energy tax credit? Asking for a friend.
- Schroedingersat 4y ago
  If by 30% tax credit you mean they are being handed enough money to pay for 3x the net capacity in renewables and then having their energy price subsidized by an amount higher than the total cost of unsubsidized renewables on top of that, and that rate payers must pay however much they spend on it no matter how far over budget it goes, then yes.
panick21_ 4y ago
While I don't really think PWR in a module is that huge of an improvment. They did help to develop some certification that will help many other SMR companies. Congrats on getting this certification threw. Its a huge achievment even with a PWR. Sadly if it wasnt a PWR it would essentially have been impossible in the US.
- exhilaration 4y ago
  I had to google PWR and it stands for pressurized water reactor https://en.wikipedia.org/wiki/Pressurized_water_reactor https://en.wikipedia.org/wiki/Pressurized_water_reactor What are the alternatives?
  - sofixa 4y ago
    For instance my favourite reactor type - lead bismuth cooled fast reactors. They've only been actually used once, on the Soviet "Alfa" class submarines, and have some interesting advantages (lead naturally blocks gamma radiation, in case of a leak temperatures will go down and the coolant will solidify thus preventing radiation leaks, high efficiency due to the high temperatures, etc.), but are pretty expensive and impractical (the coolant solidifies if temperatures get lower than expected, thus you need specialised equipment to keep them hot/operate them 24/7). There's also thorium, molten salt reactors.
    - LarryMullins 4y ago
      NaK cooled reactors have an advantage of not freezing when you shut them down since NaK freezes at -12C. However Nak explodes when mixed with water...
  - credit_guy 4y ago
    The Department of Energy is working with a number of startups on various reactors designs (including NuScale). [1] is a very nice summary. [1] https://www.energy.gov/sites/default/files/2020/05/f74/Advanced-Reactor-Types_Fact-Sheet_Draft_Hi-Res_R1.pdf https://www.energy.gov/sites/default/files/2020/05/f74/Advan...
legulere 4y ago
How much waste does it produce per electric energy produced? SMRs typically produce even more nuclear waste than big reactors. How fast can it be regulated up and down? We need solutions to step in when neither wind is blowing nor sun is shining.
- trenchgun 4y ago
  Neither of these is an important variable. Nuclear waste is in general mostly a solved problem. A bunch of barrels less or more over the lifecycle of the plant in the storage site does not move a needle much, economically or otherwise. Initial investment dominates the equation. It mostly does not make sense to ramp nuclear power up and down, because of economical reasons. Gas costs are mostly dominatd by the fuel, so there ramping up and down makes sense. Nuclear costs are dominated by the initial investment. But even without ramping up and down, still nuclear power helps integrate variable renewables, since it is providing valuable inertia to keep the grid stable.
  - nerdponx 4y ago
    > Nuclear waste is in general mostly a solved problem. A bunch of barrels less or more over the lifecycle of the plant in the storage site does not move a needle much, economically or otherwise. Storage of nuclear waste was one of several issues that led residents around the Indian Point nuclear plant to push hard for its shutdown, at which they eventually succeeded. Other issues included ecological harm to the adjacent Hudson River due to discharge of unnaturally warm water, and (probably the biggest one) the risk of widespread death and injury in the event of an accident or terrorist attack. Indian Point is in relatively densely populated area with relatively low-capacity highways, and there was a pervasive sense that the official evacuation plans would be insufficient in case of a disaster. If the plan here is to make more, smaller, cheaper nuclear plants in or near more cities and towns, this means you are going to have even more towns putting up the same local resistance on those same issues. Advocates of nuclear will need to have answers.
    - marmetio 4y ago
dang 4y ago
Related: The First Small Modular Nuclear Reactor Was Just Approved by US Regulators - https://news.ycombinator.com/item?id=32367791 https://news.ycombinator.com/item?id=32367791 - Aug 2022 (229 comments) US regulators will certify first small nuclear reactor design - https://news.ycombinator.com/item?id=32282632 https://news.ycombinator.com/item?id=32282632 - July 2022 (742 comments) Developers of small modular reactors hope their time has come - https://news.ycombinator.com/item?id=30787076 https://news.ycombinator.com/item?id=30787076 - March 2022 (277 comments) First U.S. Small Nuclear Reactor Design Is Approved - https://news.ycombinator.com/item?id=24485962 https://news.ycombinator.com/item?id=24485962 - Sept 2020 (105 comments) Small nuclear reactors: tiny NuScale reactor gets safety approval - https://news.ycombinator.com/item?id=24358850 https://news.ycombinator.com/item?id=24358850 - Sept 2020 (541 comments) NuScale’s small nuclear reactor is first to get US safety approval - https://news.ycombinator.com/item?id=24345288 https://news.ycombinator.com/item?id=24345288 - Sept 2020 (5 comments) Related a bit more loosely: China leads the quest for small modular nuclear reactors–will the world follow? - https://news.ycombinator.com/item?id=34395892 https://news.ycombinator.com/item?id=34395892 - Jan 2023 (41 comments) Small Modular Reactors Exacerbate Challenges of Nuclear Waste - https://news.ycombinator.com/item?id=31639398 https://news.ycombinator.com/item?id=31639398 - June 2022 (268 comments) Next generation nuclear reactor to be built in Wyoming - https://news.ycombinator.com/item?id=27376834 https://news.ycombinator.com/item?id=27376834 - June 2021 (26 comments) Wyoming site of new nuclear power plant from Bill Gates' TerraPower - https://news.ycombinator.com/item?id=27374840 https://news.ycombinator.com/item?id=27374840 - June 2021 (113 comments) Small modular nuclear reactors may help polluting industries reduce emissions - https://news.ycombinator.com/item?id=25791023 https://news.ycombinator.com/item?id=25791023 - Jan 2021 (45 comments) NASA completes full-power tests of small, portable nuclear reactor - https://news.ycombinator.com/item?id=16984551 https://news.ycombinator.com/item?id=16984551 - May 2018 (124 comments) Canada begins Small Modular Reactor strategy roadmap - https://news.ycombinator.com/item?id=16498617 https://news.ycombinator.com/item?id=16498617 - March 2018 (49 comments) China's Yanlong: a small nuclear reactor strictly for district heating - https://news.ycombinator.com/item?id=15967724 https://news.ycombinator.com/item?id=15967724 - Dec 2017 (60 comments) Small Modular Nuclear Reactors Overcome Existing Barriers to Nuclear - https://news.ycombinator.com/item?id=11751705 https://news.ycombinator.com/item?id=11751705 - May 2016 (84 comments)
garbagecoder 4y ago
I am an enormous advocate for nuclear as a transition energy source and I know energy geeks love decentralization, but I don't think nuclear and decentralization is a good mix. The basic rationale is that you are risking a few dead spots on the planet (Chernobyl, Fukushima, etc.) in exchange for the entire planet being destroyed, but that only makes sense if the number of places you are risking is quite small. Ideally, it would be places that are already in use for radiological purposes.
sklargh 4y ago
I would love to see SMRs deployed at older coal fuel power plant sites to replace baseload power these facilities offer. These locations are already connected to their respective grids and are environmentally degraded.
- lettergram 4y ago
  What does “environmentally degraded” mean?
  - NegativeK 4y ago
    I assume they're referring to the immediate local pollution that collects around a coal plant.
  - loeg 4y ago
    Full of toxic coal byproducts, which are either radioactive or never break down.
todd8 4y ago
There is a lot of discussion here about renewables. I recommend a recent paper published in Nature Communications titled "Geophysical constraints on the reliability of solar and wind power worldwide"[1]. It considers mixes of Solar and Wind, with or without excess capacity, and storage facilities zero, 3, or 12 hours. The paper's model (it looks like the code is available on GitHub) makes optimist assumptions (e.g. no transmission losses within a single country and feasibility of 12hrs of storage for the whole country). Nevertheless, the results are interesting. Figure 3 (see[1]) indicates how much power outage must be tolerated across the entire country for different mixes renewable capacity and storage depending on the country: US -- Generation 1.5 times the capacity needed, 12 hours of storage, wind and solar have a power supply gap of 15% when the goal is to tolerate 10 hours of power outage. Germany -- Generation 3 times the capacity needed, 12 hours of storage, wind and solar have a power supply gap of 60% when the goal is to tolerate 10 hours of power outage. The larger the power supply gap, the more additional dispatchable power that must be provided. [1] https://www.nature.com/articles/s41467-021-26355-z https://www.nature.com/articles/s41467-021-26355-z
- melling 4y ago
  [flagged]
  - einpoklum 4y ago
    > In other news, it’s too late to limit the temperature increase to 1.5 C And you would argue that is due to preferring solar and wind over nuclear? Perhaps that is why you get downvoted. (I have not downvoted you though.)
  - dang 4y ago
    Please don't post in the flamewar style and please don't break the site guidelines with complaints about downvotes, tendentious generalizations about the community, etc. All of this noticeably lowers discussion quality. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- DiogenesKynikos 4y ago
Animats 4y ago
Well, not exactly the first. Vallecitos, 1957.[1] [1] https://www.youtube.com/watch?v=nn1zESA0V8k https://www.youtube.com/watch?v=nn1zESA0V8k
runesofdoom 4y ago
To quote the late Admiral Rickover, "An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose (’omnibus reactor’). (7) Very little development is required. It will use mostly off-the-shelf components. (8) The reactor is in the study phase. It is not being built now. “On the other hand, a practical reactor plant can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated." From the article, "The first module is expected to be operational by 2029 with full plant operation the following year."
- credit_guy 4y ago
  In this particular case, what is this quote supposed to imply?
  - deleted 4y ago
    [deleted]
  - eganist 4y ago
    > In this particular case, what is this quote supposed to imply? I don't know that it's supposed to imply anything but rather shine a light on the different acceptance criteria for a study reactor v. one that generates power for, in his case, mission critical needs (though power for homes and businesses would be life-critical, so it's up there). If a study reactor breaks, even though there's a possible risk to life depending on how it fails, you can endure the downtime for a bit while bringing it back up. If a practical reactor breaks, people are far more likely to die.
    - likeabbas 4y ago
      That's why it's important to have a multitude of energy sources on a competitive power grid. The nice thing about SMRs is you can build enough of them to make the overall output consistent as needed, even with a higher tolerance for failure of any individual reactor.
beders 4y ago
I'm not convinced this will solve anything. According to this: https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why-small-modular-reactors-cant-compete-with-renewable-energy/ https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why... building intentionally small is not a good idea if you need to convert heat to electricity. And creating more nuclear waste is not ideal either. For the $600m of taxpayer money invested into this, how much solar and wind could have been built? (probably around 1GW?)
- b59831 4y ago
  The perfect is the enemy of the good.
patientplatypus 4y ago
[dead]
Julesman 4y ago
All nuclear fission for energy production is a bad thing. Full stop.
hackandthink 4y ago
"Why Small Modular Reactors Can’t Compete With Renewable Energy" "So the physics of thermal efficiency are important. So is modularity and manufacturability. There’s an optimizing curve in there that the SMR firms are trying to figure out" https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why-small-modular-reactors-cant-compete-with-renewable-energy/ https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why...
dbcooper 4y ago
Any indication of cost per kWh?

588 points by g0xA52A2A 4y ago

roomey 4y ago

Would love to know about expected failure modes or this reactor type. Is there any info on this?

alexb_ 4y ago
You can read the safety evaluation here: https://www.nrc.gov/reactors/new-reactors/smr/licensing-activities/nuscale/ser-open-items.html https://www.nrc.gov/reactors/new-reactors/smr/licensing-acti...
cratermoon 4y ago
https://thebulletin.org/premium/2021-07/can-small-modular-reactors-help-mitigate-climate-change/ https://thebulletin.org/premium/2021-07/can-small-modular-re...
AtlasBarfed 4y ago
"https://www.youtube.com/watch?v=vU-IlqiP4sU https://www.youtube.com/watch?v=vU-IlqiP4sU" Well, it says its a LWR, video says "fuel rods", which means solid rods and meltdown risk. Eh. If it's a solid fuel rod, then if you get a runaway reaction, and if circumstances mean the safety systems go offline (see: Fukushima) then meltdown. Contrast this with something like LFTR: the liquid fuel needs to stay in a certain shape/containment/vessel to maintain criticality. If it starts overreacting/heating, the "plug" at the bottom of the containment melts and the liquid flows into a shallow distributed pool that, per nuclear physics, is impossible to maintain criticality. That type of system is inherently meltdown-proof, even if all the systems go offline, the plug will melt. You know, assuming gravity still works. A pebble bed, where the solid fuel rod is instead a bunch of solid pellets, but if they get too hot you can similarly melt a plug and the pellets fall into a shape that likewise wouldn't stay critical, might also be similarly meltdown-proof, but I haven't read nearly as much on pebble bed designs. But a solid fuel rod? Nope.
- acidburnNSA 4y ago
  Nuclear engineer here. That's not quite how it all works. Solid vs. liquid fuel is not tied directly to reactivity stability, as quantified in the power coefficient of reactivity. If it goes up in power, you want the chain reaction to naturally go down. In solid fueled reactors, this is usually accomplished via the moderator. If the moderator temperature goes up, it reduced in density, thereby reducing the overall neutron moderation in the core. Thus, fewer neutrons make it to to the energy range that causes fission. Thus, reactivity goes down and the reaction stops. This is inherently stable, just like fuel density in a fluid fuel reactor going down and reducing the overall fission rate. LFTRs are pre-melted. You melt 100% of the core and then bring it critical. That's a lot of pretty mobile fission products! As for the melt plug, that's also a false solution. Given that achieving subcriticality is trivial in modern solid and fluid fuel reactors, the challenge in an accident is afterglow heat removal. As you may know, the plants at Fukushima had all rods in and were fully subcritical an hour before the tsunami hit). But when they lost afterglow heat removal, it still melted some containment barriers. Same can happen with fluid fuel, regardless of whether or not you've moved it from one tank to another. Fluid fuel is not the panacea many people want to think it is. Passive afterglow heat removal is the thing that lets reactors of any fuel form be safer than today's typical reactors, which generally require backup power to run the cooling systems. If you use certain molten salt, liquid sodium metal, liquid lead metal, etc. cooling configurations you can achieve indefinite heat removal without any external power. That reduces core damage frequencies by about 100x from modern large LWRs. Again, regardless of fuel form. That said, 100x safer than how safe current nuclear is is kind of just playing with very small numbers. Fossil and biofuel combustion kills 8 million per year from particulate emissions, according to the WHO, and also cause climate change. So we should just be building hundreds of regular large water cooled reactors now and then switch over to fancier cooling ones later, and also breeders that are ~infinitely sustainable for the long term.
  - Symmetry 4y ago
    For people who don't know this stuff, like myself a few years ago: When a uranium atom is hit by a neutron some of the will split immediately releasing new neutrons but some of them will go into an unstable state and then split some period of time later. If the instantaneous splits are enough to keep the reaction going that's called a "prompt critical" configuration and usually seen only in atomic weapons. If the neutrons released by both the immediate reactions and the delayed reactions are enough to keep the reaction going that's only "critical." Because there are many atoms in the reactor that have been hit by neutrons and are unstable but haven't split yet a reactor continues to release a lot of heat even when it's no long critical, somewhere on the order of 10% as much power as when it was fully on.
p1mrx 4y ago
Here's a presentation on their approach to safety: https://www.youtube.com/watch?v=JhrxFCtCPUo&t=2360s https://www.youtube.com/watch?v=JhrxFCtCPUo&t=2360s They estimate that the risk of core damage is 3-5 orders of magnitude lower than traditional nuclear plants.

LatteLazy 4y ago

It's easy to get certified. Now they have to get a few hundred customers and local planning permissions...

foota 4y ago
Aren't these factory built? Seems like they could start building and then work out buyers if they're as promising as people make out.
- LatteLazy 4y ago
  That's fine if you have a few 10s of billions to risk building products that might never be bought. There are 2 key issues here: you have to convince people these will work for a decade plus without issue despite being new AND you have to convince a large number of people (companies, municipalities etc) (>100 to make the factory viable and get the economies of scale) who actually have the cash to buy them. This is a key moat for a lot of tech: anyone could design a decent airliner. Can you convince enough airlines to order them to make it viable to mass manufacturer them, despite having no name or track record? Hence Boeing and Airbus remain the only games in town (and Airbus only got there with a lot of state assistance).
- Overtonwindow 4y ago
  I think what that person means is that to get this actually built, is likely going to take at least 5 to 10 years of regulatory and government action. On the local level. That's not counting anyone that might throw up roadblocks, such as environmental, and safety. That could easily extend this out another five or 10 years. If a company wanted to build this reactor today, speaking as a government bureaucrat, you are looking at least 10 years before they even break ground.
  - justahuman74 4y ago
    Are there places were they'd receive less regulation, such as on federal land or a military base?

alexb_ 4y ago

Stupid question: the article says that each module can produce 50 megawatts. What is the time of that number? Like how many people can have their energy needs met by one module?

xyzzyz 4y ago
A typical household uses something on the order of 1-2 MWh of power a month. This is something like 2-3 KW on average. 1 MW can thus support something like 300-500 households, and 50 MW can support 15000-25000 households, i.e. small to medium size town.
- LinuxBender 4y ago
  That may suffice for where they are installing the first one. [1] The county has 19k people. I assume it will be tied into the grid to shed some load from the other power plants. [1] - https://en.wikipedia.org/wiki/Lincoln_County,_Wyoming https://en.wikipedia.org/wiki/Lincoln_County,_Wyoming
nynx 4y ago
Watts is a measure of energy over time.
- deleted 4y ago
  [deleted]
- kube-system 4y ago
  [deleted]
  - coder543 4y ago
    Technically, the person you replied to is correct. Energy / time (energy over time) is power. Power * time is energy. If you had a battery with 20kWh and it was empty after two hours, you would know that it was providing 10kW, which is a measure of the energy released over time, aka. average power. I don't think nynx's comment made things much clearer to anyone, though.

giantg2 4y ago

Meh, old reactor tech with new "engineered" safety features. I would have liked to see stuff more like FAST or slow wave reactors with inherent physics based safety features.

PaulHoule 4y ago
A big part of the problem with today's reactors is that they are full of water which requires huge heat exchangers (often bigger than the reaction vessel but still safety critical) and have a huge steam turbine. Even if heat were free you'd have a hard time making the steam turbine powerset competitive in 2023. Nuclear might be able to compete if we can get rid of the water. In Japan they are talking about producing hydrogen directly with thermochemistry, no powerset at all. There is also talk about coupling fast reactors or molten salt reactors to this kind of powerset https://www.powermag.com/what-are-supercritical-co2-power-cycles/ https://www.powermag.com/what-are-supercritical-co2-power-cy... The claimed price of a NuScale reactor isn't going to beat a large LWR but it might possibly be able to build at the quote that NuScale quotes, whereas the large LWR struggles. If you want "the power to save the Earth" you have to get costs down and reactors that can do that are still a decade + out.
- giantg2 4y ago
  I'll have to look up the hydrogen one. I know the only DOE work I've heard of in the US is still hydrolysis. I thought they have small scale modupar FAST reactors. I would hope they would be similar on price, or at least quote accuracy.
  - scythe 4y ago
    Thermochemical hydrogen — solar or nuclear — has been studied for a while. The simulation thermodynamic efficiency numbers are excellent (beating electricity generation by 1.5-2x), but the reaction cycles in practice tend to leak process chemicals or corrode equipment too quickly to be sustainable (even losing, e.g., 0.1% of your iodine per cycle is unacceptable). I believe Japan is considering a reactor made of tantalum. Canada started such a project in 2010 that was supposed to be online by 2016ish but has continued hitting roadblocks.

pkaye 4y ago

This video is a tour of a NuScale facility and control room. https://www.youtube.com/watch?v=brr5j50umYA https://www.youtube.com/watch?v=brr5j50umYA

programd 4y ago
Looking at the control room displays they use imperial units all over the place - lb/ft/F. I'm very surprised that none of that stuff is metric. I wonder if this is part of some regulatory requirement.
- comicjk 4y ago
  These old units are common in engineering applications across North America, the US especially. When I was in chemical engineering school, we had to be effectively bilingual in terms of units. We even used some bizarre units like the lb-mol, defined as the number of atoms in 12 lbs of carbon-12 (ie 454 times more than a gram mol).

pfdietz 4y ago

NuScale recently announced large cost increases at the project with UAMPS. The cost per unit of capacity is now on par with the new reactors at Vogtle (~$20/W). This is outside the range at which the project could be competitive. https://ieefa.org/resources/eye-popping-new-cost-estimates-released-nuscale-small-modular-reactor https://ieefa.org/resources/eye-popping-new-cost-estimates-r...

prottog 4y ago
To put in other units: a rise from previous targets of $58/MWh to $89/MWh, more than 50%, not including a $30/MWh subsidy (so the true cost is actually $119/MWh). To be fair, it says the cost increases are mainly due to the rise in construction material prices as well as financing costs; nothing inherent to nuclear power or the novel technology itself.
- timerol 4y ago
  Producer price index on steel pipe and structural steel are bonkers: https://fred.stlouisfed.org/series/PCU3312103312100 https://fred.stlouisfed.org/series/PCU3312103312100 and https://fred.stlouisfed.org/series/PCU33231233231211 https://fred.stlouisfed.org/series/PCU33231233231211
- coder543 4y ago
  To provide more context, wind and solar were both in the low $30's/MWh of LCOE (levelized cost of energy) 3 years ago[0], with that number predicted to continue falling rapidly. Combined cycle (natural gas) is a bit higher[1] than solar and wind, with that number expected to rise over time, and I'm fairly sure the current numbers don't really reflect the substantial cost of the carbon emissions, which we will all have to pay for sooner or later. Either way, the number utilities see is currently much lower than SMRs. I'm pretty sure every prediction I've ever seen for how quickly the cost of wind and solar will fall has underestimated the speed in retrospect. That's the kind of thing these reactors have to compete with. Grids have also repeatedly been shown to handle more renewables than every previous prediction would make, and we haven't hit the limit. At this point, fossil fuel sources more frequently a source of blackouts than than renewables from everything I've seen, despite certain people blaming renewables at every turn. What we need is more energy storage, whether that's in the form of traditional batteries or more novel forms of energy storage. I think nuclear is a fine source of energy if you have it, but evidence over the last several decades shows that it is virtually impossible to build for myriad reasons. The Vogtle nuclear reactors have been one giant boondoggle. New nuclear is not cost competitive, unfortunately. This was also an interesting article yesterday: https://cleantechnica.com/2023/01/19/michael-bloomberg-backs-renewable-energy-in-new-op-ed/ https://cleantechnica.com/2023/01/19/michael-bloomberg-backs... [0]: https://www.eenews.net/articles/doe-heres-where-renewable-costs-are-heading/ https://www.eenews.net/articles/doe-heres-where-renewable-co... [1]: https://www.eia.gov/todayinenergy/detail.php?id=46856 https://www.eia.gov/todayinenergy/detail.php?id=46856

mindslight 4y ago

Does this qualify for the 30% residential energy tax credit? Asking for a friend.

Schroedingersat 4y ago
If by 30% tax credit you mean they are being handed enough money to pay for 3x the net capacity in renewables and then having their energy price subsidized by an amount higher than the total cost of unsubsidized renewables on top of that, and that rate payers must pay however much they spend on it no matter how far over budget it goes, then yes.

panick21_ 4y ago

While I don't really think PWR in a module is that huge of an improvment. They did help to develop some certification that will help many other SMR companies. Congrats on getting this certification threw. Its a huge achievment even with a PWR. Sadly if it wasnt a PWR it would essentially have been impossible in the US.

exhilaration 4y ago
I had to google PWR and it stands for pressurized water reactor https://en.wikipedia.org/wiki/Pressurized_water_reactor https://en.wikipedia.org/wiki/Pressurized_water_reactor What are the alternatives?
- sofixa 4y ago
  For instance my favourite reactor type - lead bismuth cooled fast reactors. They've only been actually used once, on the Soviet "Alfa" class submarines, and have some interesting advantages (lead naturally blocks gamma radiation, in case of a leak temperatures will go down and the coolant will solidify thus preventing radiation leaks, high efficiency due to the high temperatures, etc.), but are pretty expensive and impractical (the coolant solidifies if temperatures get lower than expected, thus you need specialised equipment to keep them hot/operate them 24/7). There's also thorium, molten salt reactors.
  - LarryMullins 4y ago
    NaK cooled reactors have an advantage of not freezing when you shut them down since NaK freezes at -12C. However Nak explodes when mixed with water...
- credit_guy 4y ago
  The Department of Energy is working with a number of startups on various reactors designs (including NuScale). [1] is a very nice summary. [1] https://www.energy.gov/sites/default/files/2020/05/f74/Advanced-Reactor-Types_Fact-Sheet_Draft_Hi-Res_R1.pdf https://www.energy.gov/sites/default/files/2020/05/f74/Advan...

legulere 4y ago

How much waste does it produce per electric energy produced? SMRs typically produce even more nuclear waste than big reactors. How fast can it be regulated up and down? We need solutions to step in when neither wind is blowing nor sun is shining.

trenchgun 4y ago
Neither of these is an important variable. Nuclear waste is in general mostly a solved problem. A bunch of barrels less or more over the lifecycle of the plant in the storage site does not move a needle much, economically or otherwise. Initial investment dominates the equation. It mostly does not make sense to ramp nuclear power up and down, because of economical reasons. Gas costs are mostly dominatd by the fuel, so there ramping up and down makes sense. Nuclear costs are dominated by the initial investment. But even without ramping up and down, still nuclear power helps integrate variable renewables, since it is providing valuable inertia to keep the grid stable.
- nerdponx 4y ago
  > Nuclear waste is in general mostly a solved problem. A bunch of barrels less or more over the lifecycle of the plant in the storage site does not move a needle much, economically or otherwise. Storage of nuclear waste was one of several issues that led residents around the Indian Point nuclear plant to push hard for its shutdown, at which they eventually succeeded. Other issues included ecological harm to the adjacent Hudson River due to discharge of unnaturally warm water, and (probably the biggest one) the risk of widespread death and injury in the event of an accident or terrorist attack. Indian Point is in relatively densely populated area with relatively low-capacity highways, and there was a pervasive sense that the official evacuation plans would be insufficient in case of a disaster. If the plan here is to make more, smaller, cheaper nuclear plants in or near more cities and towns, this means you are going to have even more towns putting up the same local resistance on those same issues. Advocates of nuclear will need to have answers.
  - marmetio 4y ago

dang 4y ago

Related: The First Small Modular Nuclear Reactor Was Just Approved by US Regulators - https://news.ycombinator.com/item?id=32367791 https://news.ycombinator.com/item?id=32367791 - Aug 2022 (229 comments) US regulators will certify first small nuclear reactor design - https://news.ycombinator.com/item?id=32282632 https://news.ycombinator.com/item?id=32282632 - July 2022 (742 comments) Developers of small modular reactors hope their time has come - https://news.ycombinator.com/item?id=30787076 https://news.ycombinator.com/item?id=30787076 - March 2022 (277 comments) First U.S. Small Nuclear Reactor Design Is Approved - https://news.ycombinator.com/item?id=24485962 https://news.ycombinator.com/item?id=24485962 - Sept 2020 (105 comments) Small nuclear reactors: tiny NuScale reactor gets safety approval - https://news.ycombinator.com/item?id=24358850 https://news.ycombinator.com/item?id=24358850 - Sept 2020 (541 comments) NuScale’s small nuclear reactor is first to get US safety approval - https://news.ycombinator.com/item?id=24345288 https://news.ycombinator.com/item?id=24345288 - Sept 2020 (5 comments) Related a bit more loosely: China leads the quest for small modular nuclear reactors–will the world follow? - https://news.ycombinator.com/item?id=34395892 https://news.ycombinator.com/item?id=34395892 - Jan 2023 (41 comments) Small Modular Reactors Exacerbate Challenges of Nuclear Waste - https://news.ycombinator.com/item?id=31639398 https://news.ycombinator.com/item?id=31639398 - June 2022 (268 comments) Next generation nuclear reactor to be built in Wyoming - https://news.ycombinator.com/item?id=27376834 https://news.ycombinator.com/item?id=27376834 - June 2021 (26 comments) Wyoming site of new nuclear power plant from Bill Gates' TerraPower - https://news.ycombinator.com/item?id=27374840 https://news.ycombinator.com/item?id=27374840 - June 2021 (113 comments) Small modular nuclear reactors may help polluting industries reduce emissions - https://news.ycombinator.com/item?id=25791023 https://news.ycombinator.com/item?id=25791023 - Jan 2021 (45 comments) NASA completes full-power tests of small, portable nuclear reactor - https://news.ycombinator.com/item?id=16984551 https://news.ycombinator.com/item?id=16984551 - May 2018 (124 comments) Canada begins Small Modular Reactor strategy roadmap - https://news.ycombinator.com/item?id=16498617 https://news.ycombinator.com/item?id=16498617 - March 2018 (49 comments) China's Yanlong: a small nuclear reactor strictly for district heating - https://news.ycombinator.com/item?id=15967724 https://news.ycombinator.com/item?id=15967724 - Dec 2017 (60 comments) Small Modular Nuclear Reactors Overcome Existing Barriers to Nuclear - https://news.ycombinator.com/item?id=11751705 https://news.ycombinator.com/item?id=11751705 - May 2016 (84 comments)

garbagecoder 4y ago

I am an enormous advocate for nuclear as a transition energy source and I know energy geeks love decentralization, but I don't think nuclear and decentralization is a good mix. The basic rationale is that you are risking a few dead spots on the planet (Chernobyl, Fukushima, etc.) in exchange for the entire planet being destroyed, but that only makes sense if the number of places you are risking is quite small. Ideally, it would be places that are already in use for radiological purposes.

sklargh 4y ago

I would love to see SMRs deployed at older coal fuel power plant sites to replace baseload power these facilities offer. These locations are already connected to their respective grids and are environmentally degraded.

lettergram 4y ago
What does “environmentally degraded” mean?
- NegativeK 4y ago
  I assume they're referring to the immediate local pollution that collects around a coal plant.
- loeg 4y ago
  Full of toxic coal byproducts, which are either radioactive or never break down.

todd8 4y ago

There is a lot of discussion here about renewables. I recommend a recent paper published in Nature Communications titled "Geophysical constraints on the reliability of solar and wind power worldwide"[1]. It considers mixes of Solar and Wind, with or without excess capacity, and storage facilities zero, 3, or 12 hours. The paper's model (it looks like the code is available on GitHub) makes optimist assumptions (e.g. no transmission losses within a single country and feasibility of 12hrs of storage for the whole country). Nevertheless, the results are interesting. Figure 3 (see[1]) indicates how much power outage must be tolerated across the entire country for different mixes renewable capacity and storage depending on the country: US -- Generation 1.5 times the capacity needed, 12 hours of storage, wind and solar have a power supply gap of 15% when the goal is to tolerate 10 hours of power outage. Germany -- Generation 3 times the capacity needed, 12 hours of storage, wind and solar have a power supply gap of 60% when the goal is to tolerate 10 hours of power outage. The larger the power supply gap, the more additional dispatchable power that must be provided. [1] https://www.nature.com/articles/s41467-021-26355-z https://www.nature.com/articles/s41467-021-26355-z

melling 4y ago
[flagged]
- einpoklum 4y ago
  > In other news, it’s too late to limit the temperature increase to 1.5 C And you would argue that is due to preferring solar and wind over nuclear? Perhaps that is why you get downvoted. (I have not downvoted you though.)
- dang 4y ago
  Please don't post in the flamewar style and please don't break the site guidelines with complaints about downvotes, tendentious generalizations about the community, etc. All of this noticeably lowers discussion quality. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
DiogenesKynikos 4y ago

Animats 4y ago

Well, not exactly the first. Vallecitos, 1957.[1] [1] https://www.youtube.com/watch?v=nn1zESA0V8k https://www.youtube.com/watch?v=nn1zESA0V8k

runesofdoom 4y ago

To quote the late Admiral Rickover, "An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose (’omnibus reactor’). (7) Very little development is required. It will use mostly off-the-shelf components. (8) The reactor is in the study phase. It is not being built now. “On the other hand, a practical reactor plant can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated." From the article, "The first module is expected to be operational by 2029 with full plant operation the following year."

credit_guy 4y ago
In this particular case, what is this quote supposed to imply?
- deleted 4y ago
  [deleted]
- eganist 4y ago
  > In this particular case, what is this quote supposed to imply? I don't know that it's supposed to imply anything but rather shine a light on the different acceptance criteria for a study reactor v. one that generates power for, in his case, mission critical needs (though power for homes and businesses would be life-critical, so it's up there). If a study reactor breaks, even though there's a possible risk to life depending on how it fails, you can endure the downtime for a bit while bringing it back up. If a practical reactor breaks, people are far more likely to die.
  - likeabbas 4y ago
    That's why it's important to have a multitude of energy sources on a competitive power grid. The nice thing about SMRs is you can build enough of them to make the overall output consistent as needed, even with a higher tolerance for failure of any individual reactor.

beders 4y ago

I'm not convinced this will solve anything. According to this: https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why-small-modular-reactors-cant-compete-with-renewable-energy/ https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why... building intentionally small is not a good idea if you need to convert heat to electricity. And creating more nuclear waste is not ideal either. For the $600m of taxpayer money invested into this, how much solar and wind could have been built? (probably around 1GW?)

b59831 4y ago
The perfect is the enemy of the good.

patientplatypus 4y ago

[dead]

Julesman 4y ago

All nuclear fission for energy production is a bad thing. Full stop.

hackandthink 4y ago

"Why Small Modular Reactors Can’t Compete With Renewable Energy" "So the physics of thermal efficiency are important. So is modularity and manufacturability. There’s an optimizing curve in there that the SMR firms are trying to figure out" https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why-small-modular-reactors-cant-compete-with-renewable-energy/ https://cleantechnica.com/2023/01/18/the-nuclear-fallacy-why...

dbcooper 4y ago

Any indication of cost per kWh?