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Small nuclear reactors: tiny NuScale reactor gets safety approval

703 points by natcombs 6y ago

mimixco 6y ago
"Officially safe" is a hilarious term which tries to predict the possibility of an MCA or "Maximum Credible Accident." Of course, Three Mile Island, Chernobyl, and Fukushima were also "officially safe" when they were built.
- melling 6y ago
  The passive safety is a big leap forward. Removing humans from that process makes it safer. "In the event of any runaway reactor event, NuScale says, the reactor quenches itself in its pool, making it “passively safe.”"
  - cma 6y ago
    Any plausible scenarios where the pool leaks?
- core-questions 6y ago
  What a bad faith post. > Three Mile Island Was handled reasonably well, resulted in safety improvements to procedures and designs for future reactors. From https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html#summary https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3... > The approximately 2 million people around TMI-2 during the accident are estimated to have received an average radiation dose of only about 1 millirem above the usual background dose. To put this into context, exposure from a chest X-ray is about 6 millirem and the area's natural radioactive background dose is about 100-125 millirem per year for the area. The accident's maximum dose to a person at the site boundary would have been less than 100 millirem above background. Not exactly the end of the world. > Chernobyl Accident caused by Communists who did not care about what happened to Ukrainians, as usual for them, and experimented with something that any nuclear physicist could have told them was a terrible idea. This is like blaming vehicles and calling them unsafe after reaching over from the passenger seat and yanking the wheel to drive a truck into a crowd. The moral of the story here is to keep Communists away from anything important, which applies to farms, industrial sectors, food distribution, and really most things more complicated than a pitchfork or a torch. > Fukushima Was reasonably safe for its long life, but they cheaped out on the necessary wall and drainage functionality; should probably have been decomm'd and replaced before this happened. The problem in the nuclear industry is that anti-nuclear people like you form public opinion that causes it to be difficult for it to move forward. New plants based on newer designs are orders of magnitude safer - e.g. the CANDU Canadian reactor which is more fail-safe than most, and the push towards 4th generation reactors. Get out of the way and let the planet have a clean base load energy source, or be sitting here bitching about carbon footprints 50 years from now when it should be a solved problem already.
  - isatty 6y ago
    > Accident caused by Communists who did not care about what happened to Ukrainians There were many such RBMK reactors spread all over the Soviet world that had the same flaws . There are many problems with your summary so can I just recommend that you watch the HBO mini series "Chernobyl" instead? It's a great watch.
    - read_if_gay_ 6y ago
      That mini series is indeed a great watch but it's also not exactly factual.
      - regularfry 6y ago
        Are there inaccuracies around the portrayal of why and how the reactor failed?
        read_if_gay_ 6y ago
        I don’t think there are fundamental inaccuracies about that, but there are many exaggerations about the immediate aftermath. E.g. the fireman’s hand burning from touching a graphite fragment stood out as a particularly egregious one. And it is in fact shown that the disaster was caused by incompetence and carelessness, which does support GGPs point.
    - core-questions 6y ago
      Flaws? The meltdown was caused by a deliberate action on behalf of people with control of the plant. I haven't watched Chernobyl because I prefer to not get my history from television shows with a narrative axe to grind.
      - regularfry 6y ago
        My understanding is that those actions were only capable of causing the problems they did because of specific design choices involved in the coolant and moderation systems. Is that wrong?
- jimiray 6y ago
  I think picking a few accidents and saying that all nuclear is unsafe is such a disingenuous argument any more. All of those plants were based on extremely old designs and there have been tons of improvements. How about we focus on the "portable" nuclear power that is used by the US Navy for submarines and aircraft carriers safely.
- duxup 6y ago
  This seems like fretting over a term. Everything is 'safe' until we discover it isn't and improve. Many things have improved over times. Calling them safe seems fine, we can do so understanding the process of learning and advancing.
kyle_morris_ 6y ago
NRC Release: https://www.nrc.gov/reading-rm/doc-collections/news/2020/20-043.pdf https://www.nrc.gov/reading-rm/doc-collections/news/2020/20-...
- dang 6y ago
  Also https://apnews.com/910766c07afd96fbe2bd875e16087464 https://apnews.com/910766c07afd96fbe2bd875e16087464 edit: and https://arstechnica.com/science/2020/09/first-modular-nuclear-reactor-design-certified-in-the-us/ https://arstechnica.com/science/2020/09/first-modular-nuclea..., via https://news.ycombinator.com/item?id=24345288 https://news.ycombinator.com/item?id=24345288
sarcasmatwork 6y ago
fyi, OSU college has a 1-megawatt research reactor. https://www.oregon.gov/energy/facilities-safety/facilities/Pages/OSU.aspx https://www.oregon.gov/energy/facilities-safety/facilities/P... https://www.corvallisadvocate.com/2012/got-nuke-state-of-the-osu-reactor/ https://www.corvallisadvocate.com/2012/got-nuke-state-of-the...
- criddell 6y ago
  McMaster University in Hamilton, ON has a reactor as well: https://nuclear.mcmaster.ca/facility/nuclear-reactor/ https://nuclear.mcmaster.ca/facility/nuclear-reactor/
- cronix 6y ago
  Reed college in Portland has a 250kW one operating since 1968. https://reactor.reed.edu/about.html https://reactor.reed.edu/about.html
- whymsicalburito 6y ago
  UC Irvine has one underneath the chemistry building https://faculty.sites.uci.edu/trigareactor/ https://faculty.sites.uci.edu/trigareactor/
- gresrun 6y ago
  The University of Florida has a 100kW training reactor since 1959[0]. [0] https://en.wikipedia.org/wiki/UF_Training_Reactor https://en.wikipedia.org/wiki/UF_Training_Reactor
- larrywright 6y ago
  University of Illinois had one for many years in Urbana. My uncle ran the reactor and then babysat the fuel for a decade or so after it was decommissioned. It takes that long to get the fuel disposed of apparently.
- nickik 6y ago
  One of the problems in the US is that there are research reactors and production reactors, nothing in between. Research reactors are to small to prove out many concepts. So startups have to essentially go from nothing to first commercial reactor in one step, without iteration.
dang 6y ago
@natcombs would you mind emailing hn@ycombinator.com? I'd like to suggest something so we can send you repost invites in the future.
baron816 6y ago
Have they announced an estimate of how much a reactor/cost of energy production will be? That’s kind of the most important factor, isn’t it?
- foxyv 6y ago
  $0.24 per kwh is a rough estimate I've seen for NuScale. Typically initial costs for microreactors right now are around $0.25 to $0.30/kwh which is about the cost of energy created by diesel generators. Natural gas is much lower. However they hope that as we make a lot of them the cost will drop.
  - mikeyouse 6y ago
    Wow. That’s substantially more expensive than I was expecting. It’s been years but we always assumed ~$0.08/KWh for on-site natural gas generated electricity on US based projects.
    - therealdrag0 6y ago
      I wonder how much more would that be if the median carbon-tax proposal was added?
      - mikeyouse 6y ago
        We did some calcs to that effect since we were operating in Australia, and they had a $25/ton carbon tax at the time. If my memory serves, it would increase natural gas costs by ~25%. So it'd likely still be right around $0.10/KWh. Actually I take that back - our calcs were all based on ~$4/mmBTU gas but I just looked and gas prices have been below $3/mmBTU for years. So $0.08/KWh is probably a worst case even if we had a reasonable carbon tax.
    - foxyv 6y ago
      Right now they are bespoke reactors so that means that they will cost a ton. But if they are turning them out like Toyotas then the cost will drop really fast. The hope is that it will be similar to the drop in cost for solar that we've seen in the past ten years. Solar originally cost about $0.28/kwh and now it's around 6 cents.
EricE 6y ago
This is huge. Not only are micro reactors far more economical, it dramatically reduces the need to maintain a massive nationwide grid and provides flexibility to people in remote areas including greater autonomy. Efficiency should be greater without massive transmission line losses. Might start fewer fires in California too.
- toomuchtodo 6y ago
  The economics are yet to be borne out. I believe the NuScale cost (feel free to correct me if this information is wrong) is still above the cost of renewables and storage [1] but below that of traditional PWRs (684Mw @ $3 billion [2], ~25 cents/kwh [3]), which is competitive in places like Hawaii (which is still relying heavily on diesel fuel for what solar isn't providing) and geographies with limited land or renewables potential, but not elsewhere (storage aside, you're still competing with renewables around 1-3 cents/kwh at utility scale). Congrats to NuScale for making it through to the other side of US nuclear regulatory purgatory. Optimism is warranted ("all of the above" to replace fossil fuels), but cautious optimism. It's not real until a commercial reactor is generating. Vogtle is still not done [4]. I hope I get to see a factory churning out prefab reactors ready for shipment. EDITs (to not pollute thread with replies): A carbon tax in the US is very unlikely, and you cannot count on economies of scale until you have arrived at scale. [1] https://www.lazard.com/perspective/lcoe2019 https://www.lazard.com/perspective/lcoe2019 [2] https://www.nuscalepower.com/benefits/cost-competitive https://www.nuscalepower.com/benefits/cost-competitive [3] https://news.ycombinator.com/item?id=24346808 https://news.ycombinator.com/item?id=24346808 [4] https://news.ycombinator.com/item?id=24061448 https://news.ycombinator.com/item?id=24061448
  - donor20 6y ago
    I think it also depends on CO2 charges if any. For example, right now we have a pretty serious externality with CO2 for coal and other sources, what are the costs that folks would assign to CO2 to clear to needed target? That could bring comparative cost (with CO2 impact) down a bit.
  - rubber_duck 6y ago
engineer_22 6y ago
Is Bill Gates an investor in NuScale? Or am I thinking of another modular reactor startup in the PNW?
- ascales 6y ago
  Bill Gates is involved with TerraPower, the other PNW based nuclear startup
  - engineer_22 6y ago
    Thank you
zymhan 6y ago
Previous Discussion 2 days ago https://news.ycombinator.com/item?id=24345288 https://news.ycombinator.com/item?id=24345288
- dang 6y ago
  Yikes - that is a classic example of a post that accumulated lots of upvotes but stayed underwater the whole time: http://hnrankings.info/24345288/ http://hnrankings.info/24345288/. This is a known problem and it's on our list to fix. Since that story didn't get much attention (relative to the interest in it), we won't call the current thread a dupe.
nsxwolf 6y ago
Article gave absolutely no indication of its dimensions. How "tiny" is it exactly?
- kyrra 6y ago
  > The reactor measures 65 feet tall x 9 feet in diameter. It sits within a containment vessel measuring 76 feet tall x 15 feet in diameter. Per: https://www.nuscalepower.com/technology/technology-overview https://www.nuscalepower.com/technology/technology-overview
  - tehabe 6y ago
    you forgot to mention that those 23 m high containment vessels are places in in a pool which of course have to be much bigger than that: "The reactor and containment vessel operate inside a water-filled pool that is built below grade." We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource.
    - deeeeeplearning 6y ago
      >We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource. I believe at current consumption rates there is still several hundred years worth of uranium. Presumably Fusion will have been figured out by then or we've killed ourselves with a climate disaster or something worse.
      - welfare 6y ago
        Nope, at the current rate of consumption it will last 70-80 years: https://en.wikipedia.org/wiki/Peak_uranium#:~:text=According%20to%20the%20World%20Nuclear%20Association%2C%20yet%20another%20industry%20group,for%20some%2070%E2%80%9380%20years https://en.wikipedia.org/wiki/Peak_uranium#:~:text=According....
        deeeeeplearning 6y ago
nickik 6y ago
As a huge fan of nuclear power, I never felt like NuScale style 'SMR' were all that great of an idea. Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. I really believe we should be a nuclear society by now, and that regulations both around reactors and fuel availability prevented this from happening. In the 1960 lots and lots of innovative reactors were build, often with relatively low budgets at that. The amount of untapped potential in nuclear energy is incredible. We don't need fusion, fission is plenty energy dense, if we can't figure out how to make fission practical, we want with fusion either. Yet here we are in the year 2020 and we are still building new PWR reactors. But the reality is, in the US it is essentially impossible to build anything else. Regulations are designed so that the only reactor that can really get approval is a PWR. If you attempt to build anything new, you have to basically pay the government to study your design and after a unknown amount of time and money, the government might develop a new regulatory framework. By the time that happens of course you have run out of money already, no buissness plan that depends on the government figuring out how to regulate a new type of reactor would ever really happen. The good thing at least is that the DoE in the last 5 years seem to have realized that their whole approach was a problem and they have done a lot of good things to try to change. Outside of the US the energy sector is government controlled or to small for a nuclear reactor startup to have a large enough market to make a new reactor worth it. Canada has established itself as basically the only viable place for new reactor development, with Terrestrial Energy and Moltex Energy (moved from Britain to Canada because regulation). So, good luck to NuScale, I hope they can prove me wrong and deploy many of these in an economical way.
- rubber_duck 6y ago
  >Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. You mean they lose operational efficiency ? Economies of scale come from the ability to mass produce. You forgot to mention the largest differentiator - eliminates the possibility of a global catastrophe.
marshray 6y ago
I think it's disingenuous to argue the economics of nuclear without mentioning: "DOE reported that it faced an estimated $494 billion in future environmental cleanup costs — a liability that roughly tripled during the previous 20 years." https://www.gao.gov/assets/700/696956.pdf https://www.gao.gov/assets/700/696956.pdf
- draugadrotten 6y ago
  How much is the future environmental cleanup costs of coal and oil?
  - xigency 6y ago
    If you consider the climate, about 100 times that.
    - vlovich123 6y ago
      Is there a paper on that? 40 trillion sounds like a lot and I’m curious how that number is generated.
      - xigency 6y ago
        If you could solve climate change for less than that, I think it would be splendid. To put that number in context, which is just an order of magnitude, it's $5,000 for every person on Earth, about 1.5x the current US national debt, and just under the combined market cap of NYSE+NASDAQ. As an existential problem for humanity that doesn't currently have a solution, I think that's a decent cost estimate.
        Retric 6y ago
        Climate change his hardly an existential threat for humanity. We survived the last ice age with stone tools, this is a less severe change. Economic impacts from things like rising sea levels really depend on how much we spend on maintaining things as they currently are vs adapting to the new normal. Aka do you live below sea level, raise the city, or move somewhere else. https://en.wikipedia.org/wiki/Raising_of_Chicago https://en.wikipedia.org/wiki/Raising_of_Chicago
Animats 6y ago
Four links down: "The staff has determined that the plant design meets the applicable requirements for the design certification stage of licensing. ... The NRC staff’s issuance of this FSER does not constitute a commitment to issue the design certification"[1] The actual review document is not up yet; search for "ML20023A318". It's not that this is smaller. It's comparable to Shippingport or Vallecitos. The argument is that it's safe enough against meltdowns not to need a full containment vessel, which makes it cheaper. The idea is to have a group of these sharing the same reactor pool. What they do if there's a leak into the cooling pool. Does that take down all the reactors? Anyway, the plan is to build the first one at the Idaho Reactor Test Station, 830 square miles with reactors spread miles apart. If something bad happens there, it's not a major problem. [1] https://www.nrc.gov/docs/ML2023/ML20231A804.pdf https://www.nrc.gov/docs/ML2023/ML20231A804.pdf
- linuxlizard 6y ago
  > If something bad happens there, it's not a major problem. Well, unless you're in Idaho like some of us. ;-)
  - Animats 6y ago
    The whole point of having 830 square miles of reactor test station is to keep the problem on the property if something goes wrong. See the SL-1 disaster. It happened there, but nobody outside the test station was affected.
  - gonational 6y ago
    LMFAO at the fact that people actually downvoted you. Pretty typical of the kind of people on here these days. Deranged, psychopath collectivists don’t give a shit about you or anyone but themselves. Anyway, it’s not like the Emmett River Valley (in Idaho) has permanent problems with people getting cancer from nuclear explosions that took place 60 years ago a thousand miles south, or anything like that.
jhallenworld 6y ago
Here is the NRC website about this reactor: https://www.nrc.gov/reactors/new-reactors/smr/nuscale.html https://www.nrc.gov/reactors/new-reactors/smr/nuscale.html Here is an interesting sub-report: https://www.nrc.gov/docs/ML2022/ML20224A525.pdf https://www.nrc.gov/docs/ML2022/ML20224A525.pdf Information withheld for security reasons. One item concerns the "ultimate heat sink". What happens when the ultimate heat sink is lost? Well a design assumption is that it is not lost: https://www.nrc.gov/docs/ML2020/ML20205L410.pdf https://www.nrc.gov/docs/ML2020/ML20205L410.pdf "A key assumption of the PRA is the availability of the UHS to provide an adequate heat sink. To support passive heat removal with the DHRS or ECCS, the reactor modules are housed and partially submerged in the UHS such that most of the outer surface of the CNV directly contacts the UHS, which is a large pool of water in the reactor building (RXB). " DHRC is decay heat. CNV is reactor containment vessel. So drain the pool and the reactor is in trouble.
- adammunich 6y ago
  It's really hard to comprehend just how much heat a reactor can make from decay alone. Like... boiling a hot tub in only a minute.
  - phkahler 6y ago
    And so a pool of water is not enough because it will boil away. A continuous flow must be present that can not be interrupted.
    - sitharus 6y ago
      You need a sufficiently large reserve to allow the reactor to cool, not an infinite supply. Reactors can be shut down and in this case the pool is sized to absorb all decay heat from the shutdown, plus a significant safety margin.
      - phkahler 6y ago
        Great, and ideally gravity can be used to move it. Remember, at Fukushima power to the pumps was lost.
jdeibele 6y ago
One thing not addressed is physical security. As pointed out by @adrianmonk it would take many of these tiny reactors to generate the same amount as a typical older reactor. Older reactors are designed like fortresses, supposedly able to take a direct hit by a commercial jet and survive. They have armed guards, etc. It would be interesting to see how they would try to protect these. Typical electrical substations are protected by a chain-link fence and a padlock.
- jabl 6y ago
  The idea is to put multiple reactors at the same site, not to spread out mini reactors all over the landscape. So the end result would be a powerplant that produces about as much power as a "normal" nuclear power plant, just that it contains many small reactors instead of a few big ones.
  - jessaustin 6y ago
    This undermines some of the claimed benefits. A bunch of little Fukushima Daiichi reactors in the same location wouldn't have fared any better than the actual Fukushima Daiichi reactor.
    - jabl 6y ago
      In this particular case, a power plant with these nuscale reactors would probably have survived a Fukushima type accident. One effect of being small is that the reactors are designed to be passively cooled after shutdown, using convection instead of pumped flow. So there is no need for emergency diesel generators to keep the coolant pumps running.
      - jessaustin 6y ago
        Sure, it's safer for reactors to tolerate flooding, if indeed these reactors actually do tolerate flooding. Definitely that would be a better design in flood/tsunami-prone areas. No design (from history, especially no reactor design) is perfect. A set of smaller reactors that were not co-located would be more tolerant of site-specific vulnerabilities in their design.
m3kw9 6y ago
Things are always different when deployed, I want to see how it performs before real world before getting excited.
normanmatrix 6y ago
I was thinking Nuclear would be the stable baseline for renewable. But this is not a sustainable option. We need to enforce hydrogen. Do not submit to the fallacy of nuclear waste disposal. First Elon needs to fix space travel and make transport into the sun feasible. And we will have iter by then.
- HideousKojima 6y ago
  Why would you need to put it in the sun? That would be a huge waste of energy, just stick it in a stable graveyard orbit, or just get it fast enough to escape Earth's gravity
- riquito 6y ago
  Hydrogen can be a practical fuel, but you need energy to extract it, which could very well be nuclear
  - phs318u 6y ago
    Or solar. Or wind. Or tidal. The beauty of hydrogen is its a great way of time-shifting intermittent energy on a large scale (assuming a large enough water supply) for later use. I’m talking primarily about electricity generation as opposed to fuel for vehicles.
- nuccy 6y ago
  Hydrogen is not a good (at the moment at least) source of energy or fuel for cars or industry (chemically speaking, obviously much better together with Deuterium and Tritium for fission, though we are still from such a technology). Steam reforming, which is currently the most common way of hydrogen production, uses natural gas and water and produces plenty of CO2 [1]. Nice summary as for cars fuel application here [2]. [1] https://en.m.wikipedia.org/wiki/Hydrogen_production https://en.m.wikipedia.org/wiki/Hydrogen_production [2] https://m.youtube.com/watch?v=f7MzFfuNOtY https://m.youtube.com/watch?v=f7MzFfuNOtY
  - pfdietz 6y ago
    Hydrogen is an answer to the question "how do renewables serve 100% of the grid?". It enables renewables to cover that last 10% or so, and rare prolonged dark/calm periods, without excessive amounts of overcapacity or batteries.
RangerScience 6y ago
Thinking about the cooling pool: Could you just make an off-shore in-ocean "farm" of these?
- AnimalMuppet 6y ago
  Salt water might add to your corrosion issues. Also, physical security of nuclear reactors is a big deal. Now you need a navy to do it.
  - RangerScience 6y ago
    Half-kidding, and it wouldn't deal with the saltwater corrosion issues, but.... Legit use for Project Plowshare harbors?
    - AnimalMuppet 6y ago
      And if you have a reactor leak, you just say it didn't matter, because Plowshare already contaminated everything. This is insane, but it has a certain consistent logic to it...
- pvaldes 6y ago
  > Could you just make an off-shore in-ocean "farm" Not! Ocean is inherently unstable!. The first serious storm would dislodge and damage the whole farm crashing one module against the other before to vomit them in the shore. Some modules just would dissapear. And then you have a humongous environmental damage and a really expensive rescue problem trying to clean the fragmented mess.
  - therealdrag0 6y ago
    Don't offshore wind farms do okay?
    - pvaldes 6y ago
      Is a totally different scale than a nuclear powerplant. A chain of entire cities will not be made unhinhabitable if a wind farm dislodges. Fishermen industries and touristic areas will not be distroyed. We have more room for losing one or two each 20 years (that is what will happen) and rebuild it again Fish cages and other offshore structures can be moved to earth in tornado season or when necessary. Moving a nuclear farm, would be much more difficult.
hinkley 6y ago
Can someone refresh my memory? Is generating electricity directly from the products of fission proven [mathematically] to be less efficient than decay->steam->mechanical->electrical or is just that the applied science of steam power is so far ahead of everything else? My peace of mind would be much greater if the energy transfer went through solid state systems instead of a working fluid that is pretty good at carrying the bad products of a [malfunctioning] reactor.
- kortilla 6y ago
  Has there even been a case of the steam being problematic?
  - hinkley 6y ago
    Most of the time? Isn’t that why everyone was pushing for molten salt or pebble reactors? I was going to say coincidence but this was clearly Google doing creepy stalker things after it saw what else I was searching for on the Internet (even not using google.com) This popped into recommendations an hour after you asked: https://youtube.com/watch?v=q3d3rzFTrLg https://youtube.com/watch?v=q3d3rzFTrLg
- cogman10 6y ago
  The problem is heat. fission produces a ton of it and it has to go somewhere. Yes, you can absorb radiation thrown off by fission, but you still have the problem that heat will melt everything. So you throw water (or salt) on the reactor, heat it up, and do work with the steam that is ultimately produced. It has less to do with steam being the ideal route and more to do the the practicality of dealing with heat. AFAIK, most reactors are closed loops anyways, so there's not much of an issue with water carrying away radioactive materials.
  - hinkley 6y ago
    Most people are worried about the reactor transitioning to an open loop against the wishes of the maintainers. But that’s good info, thanks. Molten salt still has to heat transfer to steam because we don’t have any thermovoltaics in the 50% efficient range. I think I now understand that most of the heat comes from absorbing neutrons, which don’t like to generate electricity (vs betavoltaics and gammavoltaics). And any device inside the pressure vessel would be altered by those neutrons, need to be accounted for as another source of decaying particles, and need to be replaced. And/Or, you’d want a completely different reaction and then need a neutron generator capable of running continuously. That about right?
EGreg 6y ago
What’s keeping the nuclear fusion so long? It’s much safer. Can we use Thorium for now?
dangjc 6y ago
How is nuclear compatible with variable renewable energy sources? It can’t ramp up or down quickly, so it’s not good for filling the gaps in the day when the sun is not shining. And solar is now so cheap during sunny days that the excess power is curtailed or at a negative price.
- RangerScience 6y ago
  San Francisco in the summer :D I kid! AFAIK you most want this kind of immense baselines power for heavy industrial activities. Also AFAIK, if these are simple/easy/small enough, you could co-locate the heavy consumption with the generation which'd cut power consumption (due to transmission) by something like 30% (on top of infrastructure maintenance savings). Kinda like Netflix putting boxes in local switches (if I have those terms correct).
- enaaem 6y ago
  Nuclear can operate in load following mode for a long time now. It's already done in Europe. https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-load-following-e.pdf https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-lo...
- pfdietz 6y ago
  Even if nuclear could level up and down instantly, it's economically incompatible with variable renewable sources. If the plant is not operating nearly all the time the cost of power from it goes up and up.
ed25519FUUU 6y ago
> The current design, which still has several steps until it can be constructed in the wild, is for 50 megawatts per module. NuScale seeks to apply for a 60-megawatt version next. I'm very impressed by that output. It will make a difference with areas of high solar and wind generation, which can't maintain a sustained high duty cycle. I expect these types of reactors to be in places to augment solar and wind, not replace it.
fareesh 6y ago
If you build one of these things don't you also need to build an impervious shell around them so they can't be attacked? I have read that the existing reactors can withstand air crash impacts, etc.
jokit 6y ago
I was wondering if Hyperion Power Generation had become NuScale, but no.. apparently a different solution. I remember reading about Hyperions small plant that would be buried. Glad to see the progress. I wonder how Hyperion is doing.
cm2187 6y ago
I don’t understand what makes small reactors desirable. Don’t you loose economies of scales, not only production, but also demand (ie if you have small local sources of electricity you miss the diversification of the demand you have in the central grid and you need to overprovision a lot more)?
- jobu 6y ago
  When I first heard about these small scale reactors 10+ years ago I remember the goals were to build them to be maintenance-free and disposable. They build a self contained unit that needs minimal labor to run, is highly failsafe, and pumps out ~50Mw for roughly 20 years. When it's done they drop the whole unit (roughly the size of a train car) into a concrete grave onsite and plug in a replacement. I'm not sure if the goals for this project are the same, or if the goal of a low-maintenance reactor are even possible, but it sounded pretty cool.
- credit_guy 6y ago
  > Don’t you loose economies of scales On the contrary, you gain economies of scale. The way the economies of scale work is if you build n identical widgets, it costs you less than n times the cost of building one single widgets. In other words the unit cost of a widget goes down as the number of produced widgets increases. If you want to produce a bigger widget though, you generally have diseconomies of scale. For example the Saturn V rocket was about 20 times bigger than the Titan 2 rocket (from which it was derived) but cost about 60 times more. So, if a Gigawatt-size nuclear power plant is too expensive to build, you build 20 plants of 50 MW each. This is how you achieve economies of scale.
aamsuzon 6y ago
Many people are just comment.they don’t care what is the topic. I just fool. Reading others comment.
guscost 6y ago
Best news I’ve heard in years.
pfdietz 6y ago
The ratio of the weight of the reactor assembly for these reactors to their power is about an order of magnitude worse than the similar ratio (using weight of the reactor vessel + pressurizer + steam generators) of a conventional PWR. How is this going to be competitive? I understand they've given up on making that part themselves in a factory of their own, btw.
jvanderbot 6y ago
"The design is based on Multi-Application Small Light Water Reactor developed at Oregon State University in the early 2000s. NuScale is a natural circulation light water reactor with the reactor core and helical coil steam generators located in a common reactor vessel in a cylindrical steel containment. The reactor vessel containment module is submerged in water in the reactor building safety related pool, which is also the ultimate heat sink for the reactor. The pool portion of the reactor building is located below grade. The reactor building is designed to uphold 12 SMRs. Each NuScale SMR has a rated thermal output of 160 MWt and electrical output of 50 MWe, yielding a total capacity of 600 MWe for 12 SMRs."
SMAAART 6y ago
So, what's the size of one of these tings? small? how small is small? Tiny? how tiny is tiny?
- baking 6y ago
  Each containment, vessel which produces 50MW of electric power, can fit on a truck. Each site might contain up to 12 separate reactors. That was basically the design constraint so the can be manufactured off site and shipped as one unit. A regional power company might seek permitting at 10-20 locations. If some locations didn't get a permit or if other locations proved to be uneconomical to produce power at the time of construction, they could just build at the sites they chose. Basically takes the two phase pre-construction permitting and post-construction operating permit which has been killing nuclear power and streamlines it. Because the designs are standard and modular they will be pre-approved to operate.
anonymousiam 6y ago
From the article: "In the event of any runaway reactor event, NuScale says, the reactor quenches itself in its pool, making it 'passively safe.'” So what happens when an earthquake causes a rupture of the pool barrier and all the water leaks out?
- willis936 6y ago
  This is a solved problem. Tokyo is a good example. https://en.wikipedia.org/wiki/Earthquake-resistant_structures https://en.wikipedia.org/wiki/Earthquake-resistant_structure...
jv22222 6y ago
Finally, 1.21 gigawatts for my DeLorean.
PeterStuer 6y ago
Fwiw, any nuclear reactor design in history was sold as 100% safe. In reality, shit happen. Contractors use subspec material, things on the building site get overlooked and inspectors miss things or get told to look away, But hey, I'm sure, this time, it will be different. 100%.
- jonathanyc 6y ago
  Nuclear power is comparable in safety to solar and hydropower. https://ourworldindata.org/safest-sources-of-energy https://ourworldindata.org/safest-sources-of-energy
- petre 6y ago
  Watch the "A is for Atom" episode of Adam Curtis' Pandora's Box series. It's linked in one of my other comments. Basically industrialists and sales people got involved, brushing off scientists' concerns. And irresponsible politically connected engineers in the USSR. That's why we have Chernobyl and Fukushima. However, these are lessons learned. Today it's quite hard to come up with a reactor design without many safeguards and passive safety features, like it's quite hard to come up with a car with no seatbelts or airbags.
- janmalec 6y ago
  Nothing is 100% safe, who said Nuclear power is? Nuclear power always has been and still is one of the safest ways to generate electrical power and this is what counts. Solar power for example causes a lot of fatalities due to accidents that happen during installation and has it's own environmental problems, yet nobody talks about it.
- dmix 6y ago
  What if they build this on a floating oil rig type situation and fallback dumps it into an ocean fed pool (like a box with gaps for ocean water going down 100ft) far enough off the coast to have power lines but easy enough to recover?
NiceWayToDoIT 6y ago
Why is most important left out? So, power output 50MW ... How long does one "charge" last? What is the price of unit and per kWh? What is the maintenance procedure? How long is the life? What after expiry?
sriku 6y ago
I was looking for a reference to the physical size of the reactor and couldn't find it. The sites only say "smaller". Any links with size info and requirements for containing infrastructure?
Mrdarknezz 6y ago
Great, we really need a way to produce massive amounts of green energy.
known 6y ago
Aren't BIG nuclear plants with universal distribution system BETTER from security/safety/management perspective?
codecamper 6y ago
why do we bother with this junk when we have a very large fusion reaction that is located several million miles away from us & delivers it's energy to us in the form of photons every single day.
- p1mrx 6y ago
  > every single day As a California resident, I would like the option to run A/C after sunset.
grandinj 6y ago
I don't know why they are bothering to try and build this in the US. Between the insane regulations, the anti-nuclear lobby, and the NIMBYs, they don't stand a chance. Surely they would have a much easier time selling things like that elsewhere? Growing nations would probably love reliable power that could be plonked down off a ship and added to incrementally.
hikerclimb 6y ago
Boom!
eigenhombre 6y ago
If you have 20 minutes, the video linked in the comments of the earlier HN post is quite informative, giving a much better technical explanation than the original article: https://www.youtube.com/watch?v=7gtog_gOaGQ https://www.youtube.com/watch?v=7gtog_gOaGQ It is fascinating, for example, how a slight change in the packaging of the fuel (as sand-sized pellets coated with carbon) affects the safety/stability of the design, and how resonances in the cross section for neutron absorption come into play (they broaden at higher temperatures, dampening rather than enhancing the overall reaction speed, as temperatures rise).
mlindner 6y ago
Amazing how many people in this thread don't understand nuclear and are spouting rampant fear mongering. Nuclear is fundamentally a safe technology, and these new reactors are safer than anything before. Think about how many deaths have actually been caused because of nuclear compared to coal power. The difference is dramatic.
deleted 6y ago
[deleted]

703 points by natcombs 6y ago

"Officially safe" is a hilarious term which tries to predict the possibility of an MCA or "Maximum Credible Accident." Of course, Three Mile Island, Chernobyl, and Fukushima were also "officially safe" when they were built.

melling 6y ago
The passive safety is a big leap forward. Removing humans from that process makes it safer. "In the event of any runaway reactor event, NuScale says, the reactor quenches itself in its pool, making it “passively safe.”"
- cma 6y ago
  Any plausible scenarios where the pool leaks?
core-questions 6y ago
What a bad faith post. > Three Mile Island Was handled reasonably well, resulted in safety improvements to procedures and designs for future reactors. From https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html#summary https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3... > The approximately 2 million people around TMI-2 during the accident are estimated to have received an average radiation dose of only about 1 millirem above the usual background dose. To put this into context, exposure from a chest X-ray is about 6 millirem and the area's natural radioactive background dose is about 100-125 millirem per year for the area. The accident's maximum dose to a person at the site boundary would have been less than 100 millirem above background. Not exactly the end of the world. > Chernobyl Accident caused by Communists who did not care about what happened to Ukrainians, as usual for them, and experimented with something that any nuclear physicist could have told them was a terrible idea. This is like blaming vehicles and calling them unsafe after reaching over from the passenger seat and yanking the wheel to drive a truck into a crowd. The moral of the story here is to keep Communists away from anything important, which applies to farms, industrial sectors, food distribution, and really most things more complicated than a pitchfork or a torch. > Fukushima Was reasonably safe for its long life, but they cheaped out on the necessary wall and drainage functionality; should probably have been decomm'd and replaced before this happened. The problem in the nuclear industry is that anti-nuclear people like you form public opinion that causes it to be difficult for it to move forward. New plants based on newer designs are orders of magnitude safer - e.g. the CANDU Canadian reactor which is more fail-safe than most, and the push towards 4th generation reactors. Get out of the way and let the planet have a clean base load energy source, or be sitting here bitching about carbon footprints 50 years from now when it should be a solved problem already.
- isatty 6y ago
  > Accident caused by Communists who did not care about what happened to Ukrainians There were many such RBMK reactors spread all over the Soviet world that had the same flaws . There are many problems with your summary so can I just recommend that you watch the HBO mini series "Chernobyl" instead? It's a great watch.
  - read_if_gay_ 6y ago
    That mini series is indeed a great watch but it's also not exactly factual.
    - regularfry 6y ago
      Are there inaccuracies around the portrayal of why and how the reactor failed?
      - read_if_gay_ 6y ago
        I don’t think there are fundamental inaccuracies about that, but there are many exaggerations about the immediate aftermath. E.g. the fireman’s hand burning from touching a graphite fragment stood out as a particularly egregious one. And it is in fact shown that the disaster was caused by incompetence and carelessness, which does support GGPs point.
  - core-questions 6y ago
    Flaws? The meltdown was caused by a deliberate action on behalf of people with control of the plant. I haven't watched Chernobyl because I prefer to not get my history from television shows with a narrative axe to grind.
    - regularfry 6y ago
      My understanding is that those actions were only capable of causing the problems they did because of specific design choices involved in the coolant and moderation systems. Is that wrong?
jimiray 6y ago
I think picking a few accidents and saying that all nuclear is unsafe is such a disingenuous argument any more. All of those plants were based on extremely old designs and there have been tons of improvements. How about we focus on the "portable" nuclear power that is used by the US Navy for submarines and aircraft carriers safely.
duxup 6y ago
This seems like fretting over a term. Everything is 'safe' until we discover it isn't and improve. Many things have improved over times. Calling them safe seems fine, we can do so understanding the process of learning and advancing.

kyle_morris_ 6y ago

NRC Release: https://www.nrc.gov/reading-rm/doc-collections/news/2020/20-043.pdf https://www.nrc.gov/reading-rm/doc-collections/news/2020/20-...

dang 6y ago
Also https://apnews.com/910766c07afd96fbe2bd875e16087464 https://apnews.com/910766c07afd96fbe2bd875e16087464 edit: and https://arstechnica.com/science/2020/09/first-modular-nuclear-reactor-design-certified-in-the-us/ https://arstechnica.com/science/2020/09/first-modular-nuclea..., via https://news.ycombinator.com/item?id=24345288 https://news.ycombinator.com/item?id=24345288

sarcasmatwork 6y ago

fyi, OSU college has a 1-megawatt research reactor. https://www.oregon.gov/energy/facilities-safety/facilities/Pages/OSU.aspx https://www.oregon.gov/energy/facilities-safety/facilities/P... https://www.corvallisadvocate.com/2012/got-nuke-state-of-the-osu-reactor/ https://www.corvallisadvocate.com/2012/got-nuke-state-of-the...

criddell 6y ago
McMaster University in Hamilton, ON has a reactor as well: https://nuclear.mcmaster.ca/facility/nuclear-reactor/ https://nuclear.mcmaster.ca/facility/nuclear-reactor/
cronix 6y ago
Reed college in Portland has a 250kW one operating since 1968. https://reactor.reed.edu/about.html https://reactor.reed.edu/about.html
whymsicalburito 6y ago
UC Irvine has one underneath the chemistry building https://faculty.sites.uci.edu/trigareactor/ https://faculty.sites.uci.edu/trigareactor/
gresrun 6y ago
The University of Florida has a 100kW training reactor since 1959[0]. [0] https://en.wikipedia.org/wiki/UF_Training_Reactor https://en.wikipedia.org/wiki/UF_Training_Reactor
larrywright 6y ago
University of Illinois had one for many years in Urbana. My uncle ran the reactor and then babysat the fuel for a decade or so after it was decommissioned. It takes that long to get the fuel disposed of apparently.
nickik 6y ago
One of the problems in the US is that there are research reactors and production reactors, nothing in between. Research reactors are to small to prove out many concepts. So startups have to essentially go from nothing to first commercial reactor in one step, without iteration.

dang 6y ago

@natcombs would you mind emailing hn@ycombinator.com? I'd like to suggest something so we can send you repost invites in the future.

baron816 6y ago

Have they announced an estimate of how much a reactor/cost of energy production will be? That’s kind of the most important factor, isn’t it?

foxyv 6y ago
$0.24 per kwh is a rough estimate I've seen for NuScale. Typically initial costs for microreactors right now are around $0.25 to $0.30/kwh which is about the cost of energy created by diesel generators. Natural gas is much lower. However they hope that as we make a lot of them the cost will drop.
- mikeyouse 6y ago
  Wow. That’s substantially more expensive than I was expecting. It’s been years but we always assumed ~$0.08/KWh for on-site natural gas generated electricity on US based projects.
  - therealdrag0 6y ago
    I wonder how much more would that be if the median carbon-tax proposal was added?
    - mikeyouse 6y ago
      We did some calcs to that effect since we were operating in Australia, and they had a $25/ton carbon tax at the time. If my memory serves, it would increase natural gas costs by ~25%. So it'd likely still be right around $0.10/KWh. Actually I take that back - our calcs were all based on ~$4/mmBTU gas but I just looked and gas prices have been below $3/mmBTU for years. So $0.08/KWh is probably a worst case even if we had a reasonable carbon tax.
  - foxyv 6y ago
    Right now they are bespoke reactors so that means that they will cost a ton. But if they are turning them out like Toyotas then the cost will drop really fast. The hope is that it will be similar to the drop in cost for solar that we've seen in the past ten years. Solar originally cost about $0.28/kwh and now it's around 6 cents.

EricE 6y ago

This is huge. Not only are micro reactors far more economical, it dramatically reduces the need to maintain a massive nationwide grid and provides flexibility to people in remote areas including greater autonomy. Efficiency should be greater without massive transmission line losses. Might start fewer fires in California too.

toomuchtodo 6y ago
The economics are yet to be borne out. I believe the NuScale cost (feel free to correct me if this information is wrong) is still above the cost of renewables and storage [1] but below that of traditional PWRs (684Mw @ $3 billion [2], ~25 cents/kwh [3]), which is competitive in places like Hawaii (which is still relying heavily on diesel fuel for what solar isn't providing) and geographies with limited land or renewables potential, but not elsewhere (storage aside, you're still competing with renewables around 1-3 cents/kwh at utility scale). Congrats to NuScale for making it through to the other side of US nuclear regulatory purgatory. Optimism is warranted ("all of the above" to replace fossil fuels), but cautious optimism. It's not real until a commercial reactor is generating. Vogtle is still not done [4]. I hope I get to see a factory churning out prefab reactors ready for shipment. EDITs (to not pollute thread with replies): A carbon tax in the US is very unlikely, and you cannot count on economies of scale until you have arrived at scale. [1] https://www.lazard.com/perspective/lcoe2019 https://www.lazard.com/perspective/lcoe2019 [2] https://www.nuscalepower.com/benefits/cost-competitive https://www.nuscalepower.com/benefits/cost-competitive [3] https://news.ycombinator.com/item?id=24346808 https://news.ycombinator.com/item?id=24346808 [4] https://news.ycombinator.com/item?id=24061448 https://news.ycombinator.com/item?id=24061448
- donor20 6y ago
  I think it also depends on CO2 charges if any. For example, right now we have a pretty serious externality with CO2 for coal and other sources, what are the costs that folks would assign to CO2 to clear to needed target? That could bring comparative cost (with CO2 impact) down a bit.
- rubber_duck 6y ago

engineer_22 6y ago

Is Bill Gates an investor in NuScale? Or am I thinking of another modular reactor startup in the PNW?

ascales 6y ago
Bill Gates is involved with TerraPower, the other PNW based nuclear startup
- engineer_22 6y ago
  Thank you

zymhan 6y ago

Previous Discussion 2 days ago https://news.ycombinator.com/item?id=24345288 https://news.ycombinator.com/item?id=24345288

dang 6y ago
Yikes - that is a classic example of a post that accumulated lots of upvotes but stayed underwater the whole time: http://hnrankings.info/24345288/ http://hnrankings.info/24345288/. This is a known problem and it's on our list to fix. Since that story didn't get much attention (relative to the interest in it), we won't call the current thread a dupe.

nsxwolf 6y ago

Article gave absolutely no indication of its dimensions. How "tiny" is it exactly?

kyrra 6y ago
> The reactor measures 65 feet tall x 9 feet in diameter. It sits within a containment vessel measuring 76 feet tall x 15 feet in diameter. Per: https://www.nuscalepower.com/technology/technology-overview https://www.nuscalepower.com/technology/technology-overview
- tehabe 6y ago
  you forgot to mention that those 23 m high containment vessels are places in in a pool which of course have to be much bigger than that: "The reactor and containment vessel operate inside a water-filled pool that is built below grade." We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource.
  - deeeeeplearning 6y ago
    >We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource. I believe at current consumption rates there is still several hundred years worth of uranium. Presumably Fusion will have been figured out by then or we've killed ourselves with a climate disaster or something worse.
    - welfare 6y ago
      Nope, at the current rate of consumption it will last 70-80 years: https://en.wikipedia.org/wiki/Peak_uranium#:~:text=According%20to%20the%20World%20Nuclear%20Association%2C%20yet%20another%20industry%20group,for%20some%2070%E2%80%9380%20years https://en.wikipedia.org/wiki/Peak_uranium#:~:text=According....
      - deeeeeplearning 6y ago

nickik 6y ago

As a huge fan of nuclear power, I never felt like NuScale style 'SMR' were all that great of an idea. Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. I really believe we should be a nuclear society by now, and that regulations both around reactors and fuel availability prevented this from happening. In the 1960 lots and lots of innovative reactors were build, often with relatively low budgets at that. The amount of untapped potential in nuclear energy is incredible. We don't need fusion, fission is plenty energy dense, if we can't figure out how to make fission practical, we want with fusion either. Yet here we are in the year 2020 and we are still building new PWR reactors. But the reality is, in the US it is essentially impossible to build anything else. Regulations are designed so that the only reactor that can really get approval is a PWR. If you attempt to build anything new, you have to basically pay the government to study your design and after a unknown amount of time and money, the government might develop a new regulatory framework. By the time that happens of course you have run out of money already, no buissness plan that depends on the government figuring out how to regulate a new type of reactor would ever really happen. The good thing at least is that the DoE in the last 5 years seem to have realized that their whole approach was a problem and they have done a lot of good things to try to change. Outside of the US the energy sector is government controlled or to small for a nuclear reactor startup to have a large enough market to make a new reactor worth it. Canada has established itself as basically the only viable place for new reactor development, with Terrestrial Energy and Moltex Energy (moved from Britain to Canada because regulation). So, good luck to NuScale, I hope they can prove me wrong and deploy many of these in an economical way.

rubber_duck 6y ago
>Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. You mean they lose operational efficiency ? Economies of scale come from the ability to mass produce. You forgot to mention the largest differentiator - eliminates the possibility of a global catastrophe.

marshray 6y ago

I think it's disingenuous to argue the economics of nuclear without mentioning: "DOE reported that it faced an estimated $494 billion in future environmental cleanup costs — a liability that roughly tripled during the previous 20 years." https://www.gao.gov/assets/700/696956.pdf https://www.gao.gov/assets/700/696956.pdf

draugadrotten 6y ago
How much is the future environmental cleanup costs of coal and oil?
- xigency 6y ago
  If you consider the climate, about 100 times that.
  - vlovich123 6y ago
    Is there a paper on that? 40 trillion sounds like a lot and I’m curious how that number is generated.
    - xigency 6y ago
      If you could solve climate change for less than that, I think it would be splendid. To put that number in context, which is just an order of magnitude, it's $5,000 for every person on Earth, about 1.5x the current US national debt, and just under the combined market cap of NYSE+NASDAQ. As an existential problem for humanity that doesn't currently have a solution, I think that's a decent cost estimate.
      - Retric 6y ago
        Climate change his hardly an existential threat for humanity. We survived the last ice age with stone tools, this is a less severe change. Economic impacts from things like rising sea levels really depend on how much we spend on maintaining things as they currently are vs adapting to the new normal. Aka do you live below sea level, raise the city, or move somewhere else. https://en.wikipedia.org/wiki/Raising_of_Chicago https://en.wikipedia.org/wiki/Raising_of_Chicago

Animats 6y ago

Four links down: "The staff has determined that the plant design meets the applicable requirements for the design certification stage of licensing. ... The NRC staff’s issuance of this FSER does not constitute a commitment to issue the design certification"[1] The actual review document is not up yet; search for "ML20023A318". It's not that this is smaller. It's comparable to Shippingport or Vallecitos. The argument is that it's safe enough against meltdowns not to need a full containment vessel, which makes it cheaper. The idea is to have a group of these sharing the same reactor pool. What they do if there's a leak into the cooling pool. Does that take down all the reactors? Anyway, the plan is to build the first one at the Idaho Reactor Test Station, 830 square miles with reactors spread miles apart. If something bad happens there, it's not a major problem. [1] https://www.nrc.gov/docs/ML2023/ML20231A804.pdf https://www.nrc.gov/docs/ML2023/ML20231A804.pdf

linuxlizard 6y ago
> If something bad happens there, it's not a major problem. Well, unless you're in Idaho like some of us. ;-)
- Animats 6y ago
  The whole point of having 830 square miles of reactor test station is to keep the problem on the property if something goes wrong. See the SL-1 disaster. It happened there, but nobody outside the test station was affected.
- gonational 6y ago
  LMFAO at the fact that people actually downvoted you. Pretty typical of the kind of people on here these days. Deranged, psychopath collectivists don’t give a shit about you or anyone but themselves. Anyway, it’s not like the Emmett River Valley (in Idaho) has permanent problems with people getting cancer from nuclear explosions that took place 60 years ago a thousand miles south, or anything like that.

jhallenworld 6y ago

Here is the NRC website about this reactor: https://www.nrc.gov/reactors/new-reactors/smr/nuscale.html https://www.nrc.gov/reactors/new-reactors/smr/nuscale.html Here is an interesting sub-report: https://www.nrc.gov/docs/ML2022/ML20224A525.pdf https://www.nrc.gov/docs/ML2022/ML20224A525.pdf Information withheld for security reasons. One item concerns the "ultimate heat sink". What happens when the ultimate heat sink is lost? Well a design assumption is that it is not lost: https://www.nrc.gov/docs/ML2020/ML20205L410.pdf https://www.nrc.gov/docs/ML2020/ML20205L410.pdf "A key assumption of the PRA is the availability of the UHS to provide an adequate heat sink. To support passive heat removal with the DHRS or ECCS, the reactor modules are housed and partially submerged in the UHS such that most of the outer surface of the CNV directly contacts the UHS, which is a large pool of water in the reactor building (RXB). " DHRC is decay heat. CNV is reactor containment vessel. So drain the pool and the reactor is in trouble.

adammunich 6y ago
It's really hard to comprehend just how much heat a reactor can make from decay alone. Like... boiling a hot tub in only a minute.
- phkahler 6y ago
  And so a pool of water is not enough because it will boil away. A continuous flow must be present that can not be interrupted.
  - sitharus 6y ago
    You need a sufficiently large reserve to allow the reactor to cool, not an infinite supply. Reactors can be shut down and in this case the pool is sized to absorb all decay heat from the shutdown, plus a significant safety margin.
    - phkahler 6y ago
      Great, and ideally gravity can be used to move it. Remember, at Fukushima power to the pumps was lost.

jdeibele 6y ago

One thing not addressed is physical security. As pointed out by @adrianmonk it would take many of these tiny reactors to generate the same amount as a typical older reactor. Older reactors are designed like fortresses, supposedly able to take a direct hit by a commercial jet and survive. They have armed guards, etc. It would be interesting to see how they would try to protect these. Typical electrical substations are protected by a chain-link fence and a padlock.

jabl 6y ago
The idea is to put multiple reactors at the same site, not to spread out mini reactors all over the landscape. So the end result would be a powerplant that produces about as much power as a "normal" nuclear power plant, just that it contains many small reactors instead of a few big ones.
- jessaustin 6y ago
  This undermines some of the claimed benefits. A bunch of little Fukushima Daiichi reactors in the same location wouldn't have fared any better than the actual Fukushima Daiichi reactor.
  - jabl 6y ago
    In this particular case, a power plant with these nuscale reactors would probably have survived a Fukushima type accident. One effect of being small is that the reactors are designed to be passively cooled after shutdown, using convection instead of pumped flow. So there is no need for emergency diesel generators to keep the coolant pumps running.
    - jessaustin 6y ago
      Sure, it's safer for reactors to tolerate flooding, if indeed these reactors actually do tolerate flooding. Definitely that would be a better design in flood/tsunami-prone areas. No design (from history, especially no reactor design) is perfect. A set of smaller reactors that were not co-located would be more tolerant of site-specific vulnerabilities in their design.

m3kw9 6y ago

Things are always different when deployed, I want to see how it performs before real world before getting excited.

normanmatrix 6y ago

I was thinking Nuclear would be the stable baseline for renewable. But this is not a sustainable option. We need to enforce hydrogen. Do not submit to the fallacy of nuclear waste disposal. First Elon needs to fix space travel and make transport into the sun feasible. And we will have iter by then.

HideousKojima 6y ago
Why would you need to put it in the sun? That would be a huge waste of energy, just stick it in a stable graveyard orbit, or just get it fast enough to escape Earth's gravity
riquito 6y ago
Hydrogen can be a practical fuel, but you need energy to extract it, which could very well be nuclear
- phs318u 6y ago
  Or solar. Or wind. Or tidal. The beauty of hydrogen is its a great way of time-shifting intermittent energy on a large scale (assuming a large enough water supply) for later use. I’m talking primarily about electricity generation as opposed to fuel for vehicles.
nuccy 6y ago
Hydrogen is not a good (at the moment at least) source of energy or fuel for cars or industry (chemically speaking, obviously much better together with Deuterium and Tritium for fission, though we are still from such a technology). Steam reforming, which is currently the most common way of hydrogen production, uses natural gas and water and produces plenty of CO2 [1]. Nice summary as for cars fuel application here [2]. [1] https://en.m.wikipedia.org/wiki/Hydrogen_production https://en.m.wikipedia.org/wiki/Hydrogen_production [2] https://m.youtube.com/watch?v=f7MzFfuNOtY https://m.youtube.com/watch?v=f7MzFfuNOtY
- pfdietz 6y ago
  Hydrogen is an answer to the question "how do renewables serve 100% of the grid?". It enables renewables to cover that last 10% or so, and rare prolonged dark/calm periods, without excessive amounts of overcapacity or batteries.

RangerScience 6y ago

Thinking about the cooling pool: Could you just make an off-shore in-ocean "farm" of these?

AnimalMuppet 6y ago
Salt water might add to your corrosion issues. Also, physical security of nuclear reactors is a big deal. Now you need a navy to do it.
- RangerScience 6y ago
  Half-kidding, and it wouldn't deal with the saltwater corrosion issues, but.... Legit use for Project Plowshare harbors?
  - AnimalMuppet 6y ago
    And if you have a reactor leak, you just say it didn't matter, because Plowshare already contaminated everything. This is insane, but it has a certain consistent logic to it...
pvaldes 6y ago
> Could you just make an off-shore in-ocean "farm" Not! Ocean is inherently unstable!. The first serious storm would dislodge and damage the whole farm crashing one module against the other before to vomit them in the shore. Some modules just would dissapear. And then you have a humongous environmental damage and a really expensive rescue problem trying to clean the fragmented mess.
- therealdrag0 6y ago
  Don't offshore wind farms do okay?
  - pvaldes 6y ago
    Is a totally different scale than a nuclear powerplant. A chain of entire cities will not be made unhinhabitable if a wind farm dislodges. Fishermen industries and touristic areas will not be distroyed. We have more room for losing one or two each 20 years (that is what will happen) and rebuild it again Fish cages and other offshore structures can be moved to earth in tornado season or when necessary. Moving a nuclear farm, would be much more difficult.

hinkley 6y ago

Can someone refresh my memory? Is generating electricity directly from the products of fission proven [mathematically] to be less efficient than decay->steam->mechanical->electrical or is just that the applied science of steam power is so far ahead of everything else? My peace of mind would be much greater if the energy transfer went through solid state systems instead of a working fluid that is pretty good at carrying the bad products of a [malfunctioning] reactor.

kortilla 6y ago
Has there even been a case of the steam being problematic?
- hinkley 6y ago
  Most of the time? Isn’t that why everyone was pushing for molten salt or pebble reactors? I was going to say coincidence but this was clearly Google doing creepy stalker things after it saw what else I was searching for on the Internet (even not using google.com) This popped into recommendations an hour after you asked: https://youtube.com/watch?v=q3d3rzFTrLg https://youtube.com/watch?v=q3d3rzFTrLg
cogman10 6y ago
The problem is heat. fission produces a ton of it and it has to go somewhere. Yes, you can absorb radiation thrown off by fission, but you still have the problem that heat will melt everything. So you throw water (or salt) on the reactor, heat it up, and do work with the steam that is ultimately produced. It has less to do with steam being the ideal route and more to do the the practicality of dealing with heat. AFAIK, most reactors are closed loops anyways, so there's not much of an issue with water carrying away radioactive materials.
- hinkley 6y ago
  Most people are worried about the reactor transitioning to an open loop against the wishes of the maintainers. But that’s good info, thanks. Molten salt still has to heat transfer to steam because we don’t have any thermovoltaics in the 50% efficient range. I think I now understand that most of the heat comes from absorbing neutrons, which don’t like to generate electricity (vs betavoltaics and gammavoltaics). And any device inside the pressure vessel would be altered by those neutrons, need to be accounted for as another source of decaying particles, and need to be replaced. And/Or, you’d want a completely different reaction and then need a neutron generator capable of running continuously. That about right?

EGreg 6y ago

What’s keeping the nuclear fusion so long? It’s much safer. Can we use Thorium for now?

dangjc 6y ago

How is nuclear compatible with variable renewable energy sources? It can’t ramp up or down quickly, so it’s not good for filling the gaps in the day when the sun is not shining. And solar is now so cheap during sunny days that the excess power is curtailed or at a negative price.

RangerScience 6y ago
San Francisco in the summer :D I kid! AFAIK you most want this kind of immense baselines power for heavy industrial activities. Also AFAIK, if these are simple/easy/small enough, you could co-locate the heavy consumption with the generation which'd cut power consumption (due to transmission) by something like 30% (on top of infrastructure maintenance savings). Kinda like Netflix putting boxes in local switches (if I have those terms correct).
enaaem 6y ago
Nuclear can operate in load following mode for a long time now. It's already done in Europe. https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-load-following-e.pdf https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-lo...
pfdietz 6y ago
Even if nuclear could level up and down instantly, it's economically incompatible with variable renewable sources. If the plant is not operating nearly all the time the cost of power from it goes up and up.

ed25519FUUU 6y ago

> The current design, which still has several steps until it can be constructed in the wild, is for 50 megawatts per module. NuScale seeks to apply for a 60-megawatt version next. I'm very impressed by that output. It will make a difference with areas of high solar and wind generation, which can't maintain a sustained high duty cycle. I expect these types of reactors to be in places to augment solar and wind, not replace it.

fareesh 6y ago

If you build one of these things don't you also need to build an impervious shell around them so they can't be attacked? I have read that the existing reactors can withstand air crash impacts, etc.

jokit 6y ago

I was wondering if Hyperion Power Generation had become NuScale, but no.. apparently a different solution. I remember reading about Hyperions small plant that would be buried. Glad to see the progress. I wonder how Hyperion is doing.

cm2187 6y ago

I don’t understand what makes small reactors desirable. Don’t you loose economies of scales, not only production, but also demand (ie if you have small local sources of electricity you miss the diversification of the demand you have in the central grid and you need to overprovision a lot more)?

jobu 6y ago
When I first heard about these small scale reactors 10+ years ago I remember the goals were to build them to be maintenance-free and disposable. They build a self contained unit that needs minimal labor to run, is highly failsafe, and pumps out ~50Mw for roughly 20 years. When it's done they drop the whole unit (roughly the size of a train car) into a concrete grave onsite and plug in a replacement. I'm not sure if the goals for this project are the same, or if the goal of a low-maintenance reactor are even possible, but it sounded pretty cool.
credit_guy 6y ago
> Don’t you loose economies of scales On the contrary, you gain economies of scale. The way the economies of scale work is if you build n identical widgets, it costs you less than n times the cost of building one single widgets. In other words the unit cost of a widget goes down as the number of produced widgets increases. If you want to produce a bigger widget though, you generally have diseconomies of scale. For example the Saturn V rocket was about 20 times bigger than the Titan 2 rocket (from which it was derived) but cost about 60 times more. So, if a Gigawatt-size nuclear power plant is too expensive to build, you build 20 plants of 50 MW each. This is how you achieve economies of scale.

aamsuzon 6y ago

Many people are just comment.they don’t care what is the topic. I just fool. Reading others comment.

guscost 6y ago

Best news I’ve heard in years.

pfdietz 6y ago

The ratio of the weight of the reactor assembly for these reactors to their power is about an order of magnitude worse than the similar ratio (using weight of the reactor vessel + pressurizer + steam generators) of a conventional PWR. How is this going to be competitive? I understand they've given up on making that part themselves in a factory of their own, btw.

jvanderbot 6y ago

"The design is based on Multi-Application Small Light Water Reactor developed at Oregon State University in the early 2000s. NuScale is a natural circulation light water reactor with the reactor core and helical coil steam generators located in a common reactor vessel in a cylindrical steel containment. The reactor vessel containment module is submerged in water in the reactor building safety related pool, which is also the ultimate heat sink for the reactor. The pool portion of the reactor building is located below grade. The reactor building is designed to uphold 12 SMRs. Each NuScale SMR has a rated thermal output of 160 MWt and electrical output of 50 MWe, yielding a total capacity of 600 MWe for 12 SMRs."

SMAAART 6y ago

So, what's the size of one of these tings? small? how small is small? Tiny? how tiny is tiny?

baking 6y ago
Each containment, vessel which produces 50MW of electric power, can fit on a truck. Each site might contain up to 12 separate reactors. That was basically the design constraint so the can be manufactured off site and shipped as one unit. A regional power company might seek permitting at 10-20 locations. If some locations didn't get a permit or if other locations proved to be uneconomical to produce power at the time of construction, they could just build at the sites they chose. Basically takes the two phase pre-construction permitting and post-construction operating permit which has been killing nuclear power and streamlines it. Because the designs are standard and modular they will be pre-approved to operate.

anonymousiam 6y ago

From the article: "In the event of any runaway reactor event, NuScale says, the reactor quenches itself in its pool, making it 'passively safe.'” So what happens when an earthquake causes a rupture of the pool barrier and all the water leaks out?

willis936 6y ago
This is a solved problem. Tokyo is a good example. https://en.wikipedia.org/wiki/Earthquake-resistant_structures https://en.wikipedia.org/wiki/Earthquake-resistant_structure...

jv22222 6y ago

Finally, 1.21 gigawatts for my DeLorean.

PeterStuer 6y ago

Fwiw, any nuclear reactor design in history was sold as 100% safe. In reality, shit happen. Contractors use subspec material, things on the building site get overlooked and inspectors miss things or get told to look away, But hey, I'm sure, this time, it will be different. 100%.

jonathanyc 6y ago
Nuclear power is comparable in safety to solar and hydropower. https://ourworldindata.org/safest-sources-of-energy https://ourworldindata.org/safest-sources-of-energy
petre 6y ago
Watch the "A is for Atom" episode of Adam Curtis' Pandora's Box series. It's linked in one of my other comments. Basically industrialists and sales people got involved, brushing off scientists' concerns. And irresponsible politically connected engineers in the USSR. That's why we have Chernobyl and Fukushima. However, these are lessons learned. Today it's quite hard to come up with a reactor design without many safeguards and passive safety features, like it's quite hard to come up with a car with no seatbelts or airbags.
janmalec 6y ago
Nothing is 100% safe, who said Nuclear power is? Nuclear power always has been and still is one of the safest ways to generate electrical power and this is what counts. Solar power for example causes a lot of fatalities due to accidents that happen during installation and has it's own environmental problems, yet nobody talks about it.
dmix 6y ago
What if they build this on a floating oil rig type situation and fallback dumps it into an ocean fed pool (like a box with gaps for ocean water going down 100ft) far enough off the coast to have power lines but easy enough to recover?

NiceWayToDoIT 6y ago

Why is most important left out? So, power output 50MW ... How long does one "charge" last? What is the price of unit and per kWh? What is the maintenance procedure? How long is the life? What after expiry?

sriku 6y ago

I was looking for a reference to the physical size of the reactor and couldn't find it. The sites only say "smaller". Any links with size info and requirements for containing infrastructure?

Mrdarknezz 6y ago

Great, we really need a way to produce massive amounts of green energy.

known 6y ago

Aren't BIG nuclear plants with universal distribution system BETTER from security/safety/management perspective?

codecamper 6y ago

why do we bother with this junk when we have a very large fusion reaction that is located several million miles away from us & delivers it's energy to us in the form of photons every single day.

p1mrx 6y ago
> every single day As a California resident, I would like the option to run A/C after sunset.

grandinj 6y ago

I don't know why they are bothering to try and build this in the US. Between the insane regulations, the anti-nuclear lobby, and the NIMBYs, they don't stand a chance. Surely they would have a much easier time selling things like that elsewhere? Growing nations would probably love reliable power that could be plonked down off a ship and added to incrementally.

hikerclimb 6y ago

Boom!

eigenhombre 6y ago

If you have 20 minutes, the video linked in the comments of the earlier HN post is quite informative, giving a much better technical explanation than the original article: https://www.youtube.com/watch?v=7gtog_gOaGQ https://www.youtube.com/watch?v=7gtog_gOaGQ It is fascinating, for example, how a slight change in the packaging of the fuel (as sand-sized pellets coated with carbon) affects the safety/stability of the design, and how resonances in the cross section for neutron absorption come into play (they broaden at higher temperatures, dampening rather than enhancing the overall reaction speed, as temperatures rise).

mlindner 6y ago

Amazing how many people in this thread don't understand nuclear and are spouting rampant fear mongering. Nuclear is fundamentally a safe technology, and these new reactors are safer than anything before. Think about how many deaths have actually been caused because of nuclear compared to coal power. The difference is dramatic.

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