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Nuclear startup Oklo gets thumbs-down from regulators (canarymedia.com)
333 points by orangebanana1 on Jan 14, 2022 | hide | past | favorite | 291 comments

I don't think it's a bad reactor but I looked at the application and it wasn't a good application. (The NRC says the same)

There was a large amount of hand-wringing about the risk of avalanches and other natural disasters that were extremely low probability.

They were skimpy on interesting details about the reactor such as "What do you do if the sodium coolant catches on fire?" (e.g. sodium burns in water, sodium burns in air, sodium burns in carbon dioxide) There are good answers to that in the U.S. and Russian experience. They don't draw on that experience to show they can solve it.

If they fix the application and submit it again it could get approved.

I think it is probably a bad reactor and a questionable company.

1. The company is totally opaque on even basic design details. This is not ghost mode. It's likely hiding incompetence and lack of design work / maturity.

2. It's a fast reactor so lots of high energy neutrons that will cause faster material degradation, higher maintenance cost, more downtime - the economics for fast reactors have never worked (not even in Russia or China), and this is probably why fusion reactors will never be economical (32x greater neutronicity).

3. It has terrible fuel utilization: 1% burn-up of fuel, with 100 metric tons uranium / GWe-year compared to 5-10% in other normal and advanced reactors.

4. The founders lie to congress claiming their reactor “can consume the used fuel from today’s reactors” when each reactor is actually going to require 3 tons of pretty pristine HALEU...

5. The founders peddle some serious BS (bitcoin mining, TED talks ... etc) not unlike the other great MIT nuclear startup Transatomic.

6. NRC really went out of their way to publicly reject this with press release and all. This was not done lightly to a company often featured in the WSJ and Popular Mechanics.

7. I'm disturbed by the way they talk about their reactor as a "community meeting place" with their modern glass A-frame without any power generating equipment. Is there going to be a daycare center or country club in there? Where the hell are the cooling towers? I'm all for nuclear power, but we shouldn't be down playing the seriousness of nuclear power systems.

Look to FFTF for a completely successful fast reactor run in the U.S. that was unfortunately shut down for political reasons that, retrospectively, look like a terrible mistake.

One of the most interesting features of the FFTF was a sodium-to-air heat exchanger which is a key to fast reactors having superior economics.

That is, no nuclear reactor which uses a steam turbine is going to be economically competitive with fossil fuel fired gas turbine generators. Between the absolutely huge and massive steam turbine and absolutely huge and massive heat exchangers (look at how big the steam generators are in the PWR or the huge tube-in-shell heat exchanger used at Dounreay)

A closed cycle gas turbine will fit in the employee break room of the turbine house of a conventional LWR. It requires some kind of reactor that runs at a higher temperature than the LWR. I like fast reactors and molten salts but have a hard time being enthusiastic about HTGR and friends.

So much of the literature still looks like a stopped clock. People still compare nuclear to coal although coal has been economic for a long time for the same reason as the LWR... The cost of that huge steam turbine.

Problems with fast reactors I worry about are the fear of proliferation (not proliferation) constricting what you can use for fuel and (more so) the plutonium nanoparticle problem w/ MOX fabrication. Of course you don't need to use MOX or you'd think in 2022 you could use 100% remote handling and not have the problems that Karen Silkwood was worried about at the place where she worked.

I went looking for operating closed cycle gas turbine power plants- this seems like a research topic all on its own, no matter the heat source.

It's definitely true that simple cycle gas turbine plants are much cheaper than equivalent size steam plants. This right here sets the bar for any kind of thermal power plant.

See table ES3 for cost comparisons..


> One of the most interesting features of the FFTF was a sodium-to-air heat exchanger which is a key to fast reactors having superior economics. > That is, no nuclear reactor which uses a steam turbine is going to be economically competitive with fossil fuel fired gas turbine generators.

OK, but FFTF reactor has not generated electricity at all. How is “sodium to air heat exchanger” supposed to generate electricity, to make it more economical than steam turbines?

> That is, no nuclear reactor which uses a steam turbine is going to be economically competitive with fossil fuel fired gas turbine generators.

That’s highly likely to be true (at least until cheap gas runs out, which will happen at some point, though it will take many decades/centuries until then), but I thought we are aiming to get off fossil fuels, no? We should be willing to pay some premium for nuclear, because it does not emit GHG.

A next generation nuclear reactor is not going to couple to air but probably to carbon dioxide and then to a powerset like


Nuclear also competes with fossil fuel powerplants that capture carbon. There are many options such as: (1) turn the fuel to hydrogen and burn the hydrogen, (2) run the exhaust gas through an amine stripper, (3) burn the fuel in pure oxygen so the amine stripper has less work to do (recycle the combustion products so the turbine doesn't burn up), (4) chemical looping combustion that uses a metal like iron as an oxygen carrier, etc.

The cost of something like that doesn't look crazy, optimizing it is a job for the systems engineering department, you can compress the CO2 to 1500 psi and inject it into saline aquifers which exist in most places. (Drives me nuts that carbfix gets so much press for a process which only works in a few places and consumes much more water than the carbon it captures)

It is not happening because regulators aren't forcing it, there is no carbon tax or carbon credit for it.

You could save the world with a nuclear option that is truly cheaper than the alternatives without subsidy. Anything that involves subsidy is going to give somebody an opportunity to get rich by siphoning off 5% of the credits and keep the gravy train running by paying 1% of that to politicians. Anything like that will run into intense opposition, look like a scam to people, probably be a scam in many cases (extortion like "we'll cut down this forest if you don't pay us" and then the forest gets cut down or burned anyway, unverifiable schemes like grinding up rocks and leaving them at the beach, ...) damage the legitimacy of the government and delay real solutions.

You're exactly right here, and I'd say this is well put in several areas.

I'll add that supercritical CO2 sounds like science fiction to people, but it's actually been pretty well demonstrated at the small sizes. The scaling up is what needs to happen if it's used at sizes beyond a few MWe. We've worked with vendors who have these available at the <5 MWe scale.

And I'll second what you're saying about subsidy. The incredible subsidies out there, if I didn't care about fission, would make me agree with those that are effectively anti-nuclear. If those hundreds millions and billions to single companies are necessary to * ever * get a single nuclear plant built, it just doesn't add up that it will be successful without all that propping it up. I agree it isn't necessary to subsidize, and that's how we believed it was important to run our company to date.

In this case, I'll name names, and I hope this isn't taken in a malicious sense because it isn't meant that way. But I've always wondered why Bill Gates, one of the wealthiest humans on the planet, would go to Capitol Hill for money for his nuclear company. I think I've learned that it's for reasons along the lines of what you said there. Creating a self-sustaining government program goes a long way to guaranteeing that the government cares about your company, and anyone else along the trail of $. I'm not blaming that, of course it is smart, it is just intriguing what paths occur.

PS also agree on "carbfix" - that while I'm all for all solutions to climate issues, it is wild to me too how much press that carbfix gets too in comparison to at least my perception of its reality of potential. But i suspect it goes back also to a great govt relations piece...

RE: your last paragraph:

Basically you're praying for China to succeed at this point. They have full blown LFTR research underway and I think other reactor designs under aggressive research.

Alas private funding of reactor designs is a not starter at this moment, with battery/wind/solar in rapidly evolving economies of scale and R&D. Solar/Wind is closing in on beating the leveled cost of gas turbines, and a reactor project wouldn't hit the market for ten years.

What's the economics of battery/wind/solar at that point? Salt water or Li-Sulfer batteries that are ultracheap, ultracheap but decently efficient perovskite or other techs? Too murky.

I agree we should be funding reactor techs in the billion-per-year range in the US (take it from the boondoggle fusion funding if you have to) and keeping close watch on China's progress, but probably all nuclear startups are fraud for the next decade.

Thank you for your response, it seems to be much better informed about both the technical side, and also the public choice side of the issue, than I typically see on sites like HN.

> the plutonium nanoparticle problem w/ MOX fabrication.

IIRC the Oklo design is using metal fuel, like EBRII or IFR? And the Russians are apparently working to switch from MOX to nitride fuels in their fast reactors.

Anyway, the French have been producing MOX fuel at industrial scale for decades, AFAIK without poisoning their workers. Maybe they are doing it smarter than the Americans in the 1970'ies.

I have been trying to figure it out and my guess is this.

At that factory Karen Silkwood worked (fuel for the FFTF) at they were making the workers wear respirators 100% of the time because they couldn't eliminate detectable particles.

I think in the US that's considered unacceptable. I think the French consider it OK.

The French tried to build a MOX factory in the US near the Savannah River Site last decade and it was never completed. I think there was some circle they realized they couldn't square. The UK was able to reprocess nuclear fuel and produce plutonium powder but they were unable to turn it into quality MOX fuel.

Metal fuels have a small particle problem too but you can melt the metal, pour it into a glass tube, then break the tube... All things straightforward to do with remote handling in the 1950s.

On paper nitride fuels are very high performing but I have no idea what goes into making them. It seems that with advances in robotics remote handling in fuel fabrication should be capable of much more than it ever was.

> At that factory Karen Silkwood worked (fuel for the FFTF) at they were making the workers wear respirators 100% of the time because they couldn't eliminate detectable particles.

Hmm. Dealing with Pu dust is a well known problem. Nobody knows exactly why, but Pu dust has an amazing capability to rapidly contaminate things. Best guess is that the high alpha activity of Pu produces a lot of recoil events propelling the Pu dust particle around (increasing it's diffusion constant, if you will).

I don't know exactly what the French do to make it work, is it PPE's, robotic handling or whatever.

> On paper nitride fuels are very high performing but I have no idea what goes into making them.

It's in some respects similar to making oxide fuels, you first somehow create microgranules (hopefully evenly sized) of the fuel which you then sinter into pellets. Nitrides, however, present several additional challenges. But it seems that these are not insurmountable problems, it's just that oxides have a large head start; and nitrides not being compatible with LWR's doesn't help finding R&D money either. Here's a recent overview: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6267113/

Personally I'm somewhat bullish on nitrides, if large-scale use of metal cooled reactors ever becomes a thing, that is.

Can you elaborate as to why you aren't excited about HTGRs?

Gas is poor as a heat transfer medium, so the reactor vessel is both very large (power density is on the order of one tenth of current LWR designs) and has to withstand high pressure. Hard to make such a thing economical.

OTOH, the high temperature opens up interesting industrial applications outside electricity generation.

HTGR has faced numerous development problems.

One of the coolest sounding ideas is the "pebble bed" reactor where you have carbide coated spheres that are fed into the top of the reactor and get withdrawn from the bottom, taken up an elevator and replaced.

When they tested this out in air the spheres we well lubricated and slipped past each other. In hot helium the Germans found that there was a lot more friction and the spheres were sticking to each other, cracking, getting stuck, and releasing radiation.

"Prismatic" designs where the same material is in blocks seem a little more promising. Still the reactors haven't done that well and as lurid the stories around the plutonium economy have been, the ratio of progress to problems for the liquid metal fast breeder reactor has been better.

We know how to bury oxide fuels for the long term and we know how to reprocess them. If there is a "what to do about the waste" problem it's that we can't make up our minds. Carbide fuels can be encapsulated in concrete and stored for the medium term but the actual mass and volume of the fuel is dramatically more than the LWR fuel because of the low power density. The long term stability for burial is not established, and the amount of material is 10x more. Reprocessing is not developed and faces the problems of dealing with a large amount of 'filler' that is going to be somewhat radioactive and have to be dealt with.

China's HTR-PM pair of test reactors is now grid connected. We'll see how it performs over the next few years.

The demonstration High Temperature Gas-Cooled Reactor - Pebble-bed Module (HTR-PM) at the Shidaowan site in Shandong province of China has been connected to the grid, the partners in the consortium building the plant have announced.


> I'm disturbed by the way they talk about their reactor as a "community meeting place" with their modern glass A-frame without any power generating equipment

I'll submit that a nuclear startup that presents such a stylish Architectural Digest concept for its facilities, that by itself is enough for us to be extremely skeptical of the leadership team. Their head is in the wrong place.

You will counter-argue that it takes little effort for them to hire an artist-designer to create the rendering. Nonetheless: their head is in the wrong place. They're not reading the room. None of us (not the public and not the NRC) are looking for a new alpine lodge to grab an espresso. We basically just care that you don't blow up and you don't poison the land, water, and air around you.

If leadership spend any cycles to spend on hiring a stylish designer, then their priorities aren't straight.

It would seem that both could be possible, but you're the expert here. ;) We didn't have to spend much time or money on an actually nice looking design, and the a-frame has a lot of practicalities I'm happy to talk about more (modular construction, resilience against snow, useful angle for the solar panels, strength for the internal cranes). (and yes, the power generating equipment, offices, and other space, is inside)

I guess then again here I am as part of the leadership engaging in communicating with the HN community on a friday night and hopefully transparently answering questions. I guess I can't help myself! I do think the public needs to both learn about the realities of fission, and I don't think it has to be ugly.

> I guess then again here I am as part of the leadership engaging in communicating with the HN community on a friday night and hopefully transparently answering questions.

Are you trying to guilt trip people by showing your dedication? It's in your own interest to do this, if you don't feel like it go and watch TV or something and don't bother. "Here I am on a Saturday morning commenting on HN etc..."

Haha not really. :) I was pretty much laughing at myself, responding to the commenter's idea that Oklo leadership shouldn't be spending cycles on building parameters with architects (i did - it's arguably important on a number of levels - security, regulatory, cost/finance/constructability, human factors, community relations etc...) but here i am spending cycles on like HN comments instead of other work which of course we do all weekend anyway.

Presumably they're trying to shift the image of a nuclear plant from "dangerous, not in my backyard" to something more friendly and appealing.

NuScale Power's choice of communicating this seems a lot better. By contrast this is just like rendered images of hipster micro lodges in the mountains. For a nuclear reactor. A glass metal frame structure? It doesn't inspire safety at all. In the mountains? An avalanche could raze this structure in the blink of an eye.

It's a good thing then that we analyzed to such extreme events as completely losing everything above ground, whether due to an avalanche, a tornado, an earthquake, etc, etc. :) The inherent safety in the fuel type means that there would still be zero dose. (for more info on the tests that showed this result originally in historic research reactors in operation: http://www.thesciencecouncil.com/pdfs/PlentifulEnergy.pdf)

PS I realized that you thought the structure was glass. No wonder. It's not, it's steel panels. Modular construction. There are optional solar panels on the exterior, maybe that's what you saw.

At least use an image of a panel, not glass, geodesic dome then and don't try to sell it as a community meeting point. That's a more acceptable current day view on how a nuclear reactor should look. Also cut the bitcoin BS. It's like trying to associate your project with Bernie Madoff. The hardest thing is to change people's perception and radical approaches don't cut it in this case.

I edited the above comment instead of replying here (whoops). I realized that you thought the structure was glass. No wonder. It's not, it's steel panels. Modular construction. There are optional solar panels on the exterior, maybe that's what you saw. Please see the other comments on why having a heated, lighted building space is important in the communities we've gotten to know. Bitcoin isn't BS when it's a first moving customer, even while we are actively working with plenty of other customers you'll recognize well, when the time comes to announce. It takes time.

I am all for style, but they aren't sending the right message. There's a certain beauty in a cartridge reactor that is buried below grade and shows hardly anything.

Fair point, but when we examined just having everything underground, it was more expensive actually. Once you consider operational realities in a remote environment (especially in permafrost), it is beneficial to have power conversion equipment indoors, offices, a bathroom, storage areas, etc. and then you're talking a building above ground anyway. There is security protection built in too that I can't elaborate on.

like this one? https://usnc.com

> the economics for fast reactors have never worked (not even in Russia or China)

Russia currently has two sodium-cooled fast reactors that are producing power, the BN-600 and BN-800. They also have another sodium reactor under development, the BN-1200. BREST-OD-300, a lead-cooled fast reactor, is under construction as well.

But those don't have to be economical purely on power generation, right, because they also produce Pu-239? Presumably fast breeder reactors would be useful to the Russian state even if they didn't produce electricity at all...

There's no evidence that they are being used to breed plutonium. In fact the BN-800 burns a mixture of uranium and plutonium to reduce their weapons stockpile.

They have RBMKs which will produce 10 times that, and more cheaply.

They went bankrupt with their arsenal once, so I'd argue it would be more useful to their rivals.

> 2. It's a fast reactor so lots of high energy neutrons that will cause faster material degradation, higher maintenance cost, more downtime - the economics for fast reactors have never worked (not even in Russia or China), and this is probably why fusion reactors will never be economical (32x greater neutronicity).

Commonwealth Fusion Systems's ARC has an interesting approach to handling this -- using a liquid blanket which can be circulated. Of course, ARC isn't built yet! But if that approach is workable, perhaps it can be applied more generally?

I believe it has to be replaced every 4 years of operation as intermediate level radioactive waste.

CFS claims that it's manageable, although I don't know enough to evaluate that claim. It's also not clear from this quote if the once/twice per year is referring to full replacement of the vacuum vessel, or maybe just to inspection or replacement of a subset of components.

"Bob Mumgaard, CEO of Commomwealth Fusion Systems, regards neutron flux as part of a fusion power plant’s wear-and-tear—a routine aspect of its servicing cycle, happening perhaps once or twice a year. “We can simplify the internal components, develop maintenance scenarios,” he says. “We have such a scheme substantially in place.”" https://nautil.us/issue/86/energy/the-road-less-traveled-to-...

Does it produce less waste than a fast reactor without the liquid blanket?

The replaced blanket itself is waste, so I'd venture to say no?

Hey Gloriana, I'm sure PR experts would say I'm probably not making a good decision responding here, and I haven't even had anything to drink, but I'll take a stab at sharing a bit on each of your points. I hope this response will be taken in the good faith in which it is given.

1) There's certainly many hundreds of pages/slides in the fully public docket on the NRC website, but the easiest source for the most information in one place is our application itself: bit.ly/AuroraCOLA. I don't expect anyone to want to read that entire thing either, but it's there. The only main things that are withheld are generally either: export controlled (defined by the Department of Energy, and we take it seriously) which includes detailed core maps, or security-related information (defined by the NRC). But the rest of it is all there. If there's something you want to know that isn't there, I'm happy to respond.

2) We are building our designs off the 30 years of experience and data with EBR-II and other fast reactors (http://www.thesciencecouncil.com/pdfs/PlentifulEnergy.pdf). EBR-II was ended prematurely for political reasons and had plenty of life left. The EBR-II showed how electricity could be put on the grid with higher uptimes than even the commercial fleet at the time. Unfortunately, I can't give details, but let's just say other major developers of historical fast reactors didn't release their economics because they didn't want it to cannibalize their other plants. But you don't need to believe that either. Our business model is to provide power via PPA so if the economics don't work for the customer we simply won't have a deal. Our FOAK plants are economic already in remote or higher cost areas, but the real key to our economics is when we are able to recycle existing waste, a fact unique to fast reactors.

3) 1% was really to be conservative for the FOAK, to try to make the licensing of the FOAK simpler within the datasets we had. I assume you know a number of SFRs have worked toward establishing datasets for up to and beyond 15% burnup. I really don't know where the number of 100 MT of uranium comes from. We would have <5MT total of fuel for 20 years, with <1T of that being uranium. 1.5MWex24hrx350days/yrx20 years is something like 250 GWe?

4) Oof. Yes, fast reactors can consume the fuel from today's reactors, and even though that supply chain isn't established, the FOAK is using waste fuel from EBR-II. I can assure you it is not pristine. No one else wants it. :) But we are working together with the DOE on a project with Argonne National Lab to begin work on the recycling from today's reactors (https://www.energy.gov/articles/doe-announces-over-65-millio...).

5) Hm. well, I want to be positive here: I'd argue there's a difference between our first customer announcement being Compass and a TEDx with my alma mater, and moving forward for years with something that fellow students and professors said had fundamental issues since grad school, which a professor finally leaked to the press out of frustration (and yes, we might have been fellow students). It's funny, I always said we should never do a TED too because they seem so smarmy, but a friend at my undergrad and the students there were organizing a TEDx and honestly it was cute and was just a fun opportunity to go back there for various reasons. We've been working with other more traditional customers in ways that we can't announce yet. But, we are working with other customers you'll likely approve of more. Remote communities as well as big companies just truly do need reliable power and they do want it to be emission-free.

6. They did seem to go out of their way didn't they. More will come on this once we are able to put out our own account too after 30 days, just because we should have the opportunity to set the record as well. But, to put myself in their shoes, they are trying to defend against an appeal or legal action. Neither of which we really have interest in, we just want to try again, move forward.

7. I responded to this with Paul. TL;DR: I don't think an attractive and functional building with all required security and operational characteristics means we are "down playing the seriousness." If you've been out to these truly poor, remote communities in the Arctic circle as I have, you'll see why they care about having heated, lighted, indoor areas in the long winters. And when the analysis shows the safety and security required, why wouldn't we offer that to them?

Well, there you go. Feel free to pick it apart but hopefully it added some context to the press releases and pretty pictures and whatnot.

Thanks for the response.

I had previously gone though the Oklo COLA, which is indeed hundreds of pages. But quantity is not always quality. I have seen the same types of submissions from other reactor proponents, and they are far more detailed, comprehensive, and informative and they are mostly at earlier stages of NRC engagement in pre-application discussions. As an example, I can't find a basic dimensioned or labeled reactor drawing or system diagram in Oklo's COLA. As far as the COLA illustrates, the Aurora design consists of an A-Frame drawing and a cylindrical vessel in a dugout. The safety analysis provided are generally simplified, rarely showing uncertainties or limitations of the analysis. See the NuScale or GE-Hitachi designs in pre-application or even the Transformational Challenge Reactor (TCR) as an example of a well documented research thrust that has not even begun the regulatory process if it ever will: https://tcr.ornl.gov/publications/

As far as spent fuel goes, the EBR II fuel that Oklo plans to use took decades to reprocess at a cost much greater than 0, which Oklo is not paying for. EBR II is not a civilian power generating reactor like all LWRs and BWRs currently in operation. Perhaps one day, reprocessing spent fuel will be cost effective. But today, it is a totally unnecessary activity as there's plenty of uranium and spent fuel storage is not an issue. I think telling congress that Aurora will consume spent fuel from today's reactors is false and disingenuous, both because it is extremely expensive to do so and because it is not particularly useful.

Aurora is ostensibly a tiny fast reactor, though I have to guess at this as there are no dimensioned figures in the COLA. Neutron leakage is going to be big and burnup low. This might be why Aurora is limited to 1% burnup. Maybe Oklo plans to make much larger reactors in the future, which have very different safety characteristics but can achieve higher burnup. It's curious that of the 70+ reactors in development, there are no fast spectrum and tiny reactors except for Oklo. There are fast reactors like TerraPower Natrium but they 200x larger than Aurora.

The calculation for tons / GWe-yr is as below assuming a 33% efficient power cycle (reasonable given the low temperatures of the heat pipes, but maybe the sCO2 is really good). GWe-yr is a unit of energy.

1.5 MWe * 20 yr means you are producing 4.5 MWth for 20 years, and must have fissioned 35 kg of Uranium (you get 200 MeV per U fission which is 2.6 MWyr / kg U). If 1% burnup is assumed, as indicated, Aurora is using 3500 kg or 3.5 tons of HALEU. I think this would change a bit depending on the spectrum.

3 tons HALEU / (1.5 MWe * 20 yr) * (1000 MW / 1 GW) = 100 ton HALUE / GWe-yr

Thanks for the followup as well. I'll just respond on a couple of the points:

- you don't see these detailed core schematics with analyses because in our design they are designated export controlled (ECI) as I mentioned. It doesn't mean that they aren't in there or that they haven't been extensively performed and documented.

- the endeavor (and cost) of downblending EBR-II fuel over many years has been based on the national and state nonproliferation agreements to downblend this high enriched used fuel from EBR-II. Don't confuse that endeavor with processing used, low-enriched fuel from existing plants. In the one case, the downblending work was being performed for many years in the interest of downblending before storing as waste (except now, instead, it can be used to produce clean power and demonstrate a FOAK fission plant). In the other case, recycling existing waste, we are already working with DOE (and starting NRC interactions) about deploying recycling existing nuclear waste for fuel. I can tell you it's incredibly cost effective for a fast reactor to utilize the TRU in existing low-enriched waste and that is our goal for not just feel-good reasons but also for economic reasons. It is not false nor disingenuous.

It's true that the burnup is far less than would be ultimately most economically efficient. The FOAK was intended to serve as a bit of an MVP as I already mentioned. But it's key that larger doesn't mean less safety. The fundamentals of the safety in this case lie in how the fuel has inherent shutdown characteristics, which were proven true of EBR-II (at 65 MWth) even as it's true of Aurora (<10MWth). Many different plants have different mechanisms of safety at various size ranges!

Thanks for engaging and your thoughtful responses.

In Fusion reactors the neutrons are used to breed Tritium from the Lithium so they're not hitting the structure and degrading it.

Not quite. 80% of the energy in D-T fusion reactions are released as neutron energy. I sure hope most of that will be used for generating electrical power rather than breeding tritium... :) The dpa rates and helium embrittlement are way higher for fusion and fast fission reactors than for thermal fission reactors. See Figure 3 and 5 of https://www.annualreviews.org/doi/abs/10.1146/annurev-matsci...

You have to absorb the neutrons to capture that energy, so you will always have to deal with transmutation. You can't choose one or the other.

On this case, the lithium absorbs the neutrons and convert most of the energy into heat, while it becomes tritium.

So, we have half a meter of lithium just sitting there, not contained in any structure?


> Seems like you have an ax to grind

I don't feel like this is at all a fair or appropriate response to GP. They all seemed like very valid points. Which points fall under the "grinding an axe" category, as opposed to "valid criticism" category?

Point 2 is highly debatable. DOE is funding TerraPower's Natrium (Bill Gates company) which is a fast reactor, to the tune of 2.5B as part of the Advanced Reactor Demo Program. So a lot of people in the industry believe fast reactors can be commercially viable.

People being wrong about things is not a reason to accuse them of acting in bad faith.

I mean, I am just criticizing the founders and company based on the information available - which isn't much, but it's their fault. They seem to have a lot of press coverage for an empty landing page, and a lot of it is unreasonably glowing.

Also, it’s far from unusual for someone to find a given company suspicious and go digging to find out more and produce public reports or comments questioning their validity. That’s not “axe to grind” and more “amateur investigative journalism”.

Please feel free to reference a list of Oklo press releases here: https://www.businesswire.com/portal/site/home/search/?search...

Well we're all creatures of opinion; but there is a lot here without much real backing. We have a similar post on tech forums for almost every company from Apple to ... I can't think of a company name starting with Z, Volkswagen will have to do. And pretty much every startup if someone cares to look in to them.

Cynicism is extremely easy. Every company looks dodgy from the outside and most of them are dodgy. Many such posts turn out to be correct. But that is because cynicism is misplaced - the point of these startups is that some of them will, despite looking dodgy, turn out to be keystones for trillions of dollars of industrial success.

The upside of a serious energy revolution completely outweighs any of these points raised. There needs to be a way for dodgy-looking startups to experiment without just getting a "nah, this year's work is a write off. Oh well lol" from regulators.

I completely agree - but let's call it scientific research not startups.

Startups are about industrialising existing working processes. What we are missing here is the multiple different funded experiments that take the different combinations of salts, heat exchangers and so on and come up with "hey this one works best" - make these.

Funding these experiments through VC is just asking for bias and PR not empirical results.

In short, if the government was running 100+ experimental reactors, this press release would be "whoops, 99 to go" and not even create a stir. It's only because there is 100M at stake is anyone fighting back.

> from Apple to ... I can't think of a company name starting with Z

Zeppelin? :)


That's cool! Nice pictures and a couple good videos of the Zeppelin in flight. I was a bit disappointed not to see any ads for beer on the side of the Zeppelins. Seemed like a marketing miss.



Zeit unfortunately is now Vercel

Oklo has hundreds of pages of information on safety and all kinds of details of their design that is fully public. To say they’re hiding something is ridiculous and disengenuous.

Don’t claim they are lying to Congress about being able to reuse waste. You are the one who is blatantly lying about this to the point I wonder who’s paying you? It does not require “pristine haleu”- the very first reactor is using waste from Idaho National Labs. The DOE and Oklo are also working together on a waste-to-fuel factory as a second project. The fact you’d make up this information is reason enough to question both your motives and the entirety of your post.

Transatomic is nonexistent and Oklo chose not to work with them for a reason. They are quite different.

You also clearly don’t know anything about the NRC and their dealings with this company; they are working with Oklo currently on approval process.

Again, you seem uninformed on this company and their tech; the entire thing is small and on shutdown creates only as much heat as a riding lawnmower. So yes- there can be a country club or a daycare or whatever else you want to put on top. That’s part of why it’s so safe and needs to be approved. I question that you’re actually for nuclear power at all; if you are, stop making up lies about a revolutionary company working to solve our energy crisis.

> You are the one who is blatantly lying about this to the point I wonder who’s paying you?

Ah the good old I disagree or you are wrong therefore you must be a shill accusation. That one is so boring it is actually part of the guidelines so if you're wondering why your comment is dead, that's it.

Engaging in personal attacks is not the way to fight disinformation. This comment will likely be down voted and flagged into oblivion.

Take a look here for guidelines on how to comment on HN: https://news.ycombinator.com/newsguidelines.html

Excuse me- they are the ones claiming this company is lying to Congress, which they are not, and this person has zero proof of. In no way was I personally attacking- I am correcting their blatant lie. You should be standing up against a commenter making up lies about a small company in a huge space that’s doing amazing work.

> You should be standing up against a commenter making up lies

I am trying to help you understand how to do that effectively yourself given that you appear to be new to the site (given your account age) and unfamiliar how to effectively communicate in this community.

People are frequently factually wrong. You will be more effective at correcting those factual errors if your tone remains civil, focused on facts and especially if you provide good citations to back up your corrections.

Additionally, calling out people as shills is specifically discouraged here as it does not lead to productive discussions. If you are concerned that someone is a shill, you should send an email to the HN moderators as they do investigate.

This is also explained the the guidelines (which really are worth reading.):

> Please don't post insinuations about astroturfing, shilling, bots, brigading, foreign agents and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email hn@ycombinator.com and we'll look at the data.

This is a great assessment of the response by the NRC. The operating phrase to focus on is "without prejudice," which in this context means "just fix the problems and try again."

We applied for a direct to phase 2 SBIR in 2020 and were thoroughly denied, mostly due to fixable errors in our application that we made because we put it together ourselves and had never applied for a grant before. After involving some consultants and the relevant institutions, we got a much lower impact score and are likely to receive the grant soon.

Moral of the story: you can't fake regulatory experience, and regulatory applications require specialist knowledge to put together correctly.

I wish them all the best in their resubmission!

> you can't fake regulatory experience

While that seems true, but reading previous applications doesn't help?

> and regulatory applications require specialist knowledge to put together correctly.

Again, seems trivially true, but (again) how come you can't copy-paste a previously accepted application? (I mean, if you find a very similar site, same risks, hazards, geology, weather patters, distance from population centers, blablabla, same technology, same trade offs... shouldn't it be okay? [assuming the regulations haven't changed])

Nobody has gotten an application approved for a new reactor (e.g. not an LWR) yet.

It's not that the NRC is unfair but it is like private spaceflight. For years there was talk at best. Designs like


have been up in the air for decades but nobody was serious about getting approval and building them. Oklo ought to be proud to be the first to get shot down, pick themselves up again, and submit a better proposal.

Most regulatory consultants give hyperfocused advice specific to your application, and cost in the ~$10k order of magnitude, sometimes pushing the ~$100k. Given the capital investments in applications, you'd be hard pressed to find successful, complete applications with enough details relevant to your proposal that you could simply plagiarize them.

For reference, our SBIR submission was over 200 pages, much of it containing _incredibly_ specific technical documentation about our system, clinical protocols, statistical analysis plans, etc.

Point being, it's not as simple as copy pasting a known good application.

But is this the one that got approved?

So 200 pages of technical details seems like a pretty good thing to go over, understand and then base a new application on.

The regulations have a laundry list of things that need to be included in the application, right? Looking at bad and good applications helps form a mental model of how one has to actually present the answers to those items on the list.

Of course it's not literal copypaste but which part is black magic from a system integrator point of view?

Of course hiring someone who wrote a few successful ones helps, but they are also basing their new work on their previous one, no? (Again not letter by letter obviously. And in some cases some sections require more depth, more detailed answers, in some cases they are not applicable, but good applications are similar to each other, because they are complete, they cover all the required risk assessments, etc... if not, what going on, could someone help me understand this?)

And it shouldn't be. Without the relevant knowledge to make the application you shouldn't be receiving the 'go'.

Congratulations on (hopefully!) getting a phase 2 approved, that can be a breath of life for a lot of smaller companies.

Sodium-cooled reactors have a long and troubled history.

* Sodium Reactor Experiment (Leak, minor sodium explosion, decommissioned)[1]

* Monju Nuclear Power Plant (Sodium fire, never worked properly, decommissioned)[2]

There's even been a sodium fire at a solar plant, one of those big focused mirror systems.

Many of these new reactor designs are based on complex arguments that the worst-case accident doesn't require a huge, expensive secondary containment vessel capable of containing a major accident. That's a tough sell, since Chernobyl didn't have a containment vessel and Fukushima's reactors had ones that were too small. On the other hand, Three Mile Island had a big, strong containment vessel, and in that meltdown, it held, containing the problem. In all three accidents, the actual accident was worse than the design maximum credible accident.

The NRC is right to be skeptical of weak containment designs.

It's frustrating. The reactor designs that have worked reliably for long periods are very simple inside the radioactive portion of the system. Sodium reactors had leaks and fires. Pebble bed reactors had pebble jams. Helium gas-cooled reactors had leak problems. Molten salt reactors include a radioactive chemical plant. So nuclear power is stuck with water as a working fluid.

[1] https://en.wikipedia.org/wiki/Sodium_Reactor_Experiment

[2] https://en.wikipedia.org/wiki/Monju_Nuclear_Power_Plant

EBR-II and FFTF were 100% successful in the USA. Russia has also had very good experience with fast reactors. Sodium fires are a problem, but fires happen in industrial facilities all the time, you just detect them and then you put them out.

Monju had many things wrong with the design, it was a loop-type reactor that nobody is talking about building anymore. Also it was nowhere near adequate from a seismic perspective it is kinda shocking they were allowed to build it at all.

Water reactors have no future for the same reason nobody has built a coal plant since 1980. The steam turbine and associated heat exchangers are unacceptably large and capital intensive compared to modern fossil fuel power plants based on gas turbines. (Look at how huge the steam generators are for the PWR)

Even if the construction problems were solved for the LWR, the economics will not work, you are better off capturing the carbon from a fossil fuel gas turbine plant and pumping it underground.

For nuclear power to be competitive we have to develop closed cycle gas turbine powersets. The 1970s model was that a fast reactor would be more capital intensive than an LWR but with the CCGT advanced reactors could be possibly be competitive -- if we can develop the powerset and reactors that run at high enough temperatures (not water) to support the powerset.

> Water reactors have no future for the same reason nobody has built a coal plant since 1980. The steam turbine and associated heat exchangers are unacceptably large and capital intensive compared to modern fossil fuel power plants based on gas turbines.

Hmm, seems China, India and Indonesia are still building them at a rate of one per week or so, unfortunately. Heck, even Germany opened a new coal plant last year.

The hard coal power plant Dattel was planned in the 2000s and serves as a replacement for three shut down power plants. It was the last coal-fired power plant that will ever go online in Germany. It has to be shut down in 2038 due to the general phase-out of coal.

Not all MSRs have the radioactive chemical plant, just the thorium-fueled ones. Several MSR companies are working on uranium-fueled versions; e.g. Terrestrial Energy, where the reactor core is a sealed can that gets swapped out every few years.

I am a fan of the can.

France has recently given up entirely on fast reactors, mothballing their proposed new program.


In addition to be bad news for fast reactors, this also means France does not see nuclear being a major factor in avoiding global warming (a nuclear powered world using burner reactors would run out of uranium very quickly, or would need to tap vast new sources at dubiously low cost.)

The French Superphenix is the butt of jokes, but France really has led the world in (1) reprocessing spent fuel, and (2) really fabricating the extracted plutonium into MOX fuel and putting it back into reactors. Everybody else has been too scared of the high energy ball mill and the plutonium nanoparticles that it makes.

(Ok, the Russians are serious too about using MOX in fast reactors but they've developed an alternative to the high energy ball mill.)

The supply of uranium is vast if you consider seawater as a resource. If burner reactors can be made economical in terms of capital cost we could possible make seawater uranium work. With a breeder cycle seawater uranium would certainly be affordable, we'd wind up spending a lot more on the rest of the fuel cycle.

Reprocessing only makes sense if you're going to put that separated plutonium into a fast reactor. MOX fuel's value for LWRs is so marginal that it's not worth reprocessing spent fuel to make it.

Seawater uranium extraction would have to be scaled up by a factor approaching a trillion if nuclear w. LWRs is going to fuel the world (to in excess of 1 million tonnes of natural uranium per year), and it would only last a few thousand years.

A few thousand years is plenty of time to come up with alternatives.

It's illustrative of the scale of U extraction that would be needed. A single 1 GW(e) burner reactor would require a field of U absorbers covering 170 km^2 of continental shelf (and to supply 18 TW of primary thermal energy would need about 6000 such reactors). The power/area would be considerably worse than solar (with solar capacity factor taken into account).

Anyway, I don't believe France (or anyone else) has any major program to bring seawater uranium extraction to market either.

At least it gave up building them as public projects. They really want to control costs. Get the most boring thing possible and make more of it cheaper. (The EPR 2 project.)

> So nuclear power is stuck with water as a working fluid.

Steam explosions :|

Isn't a sodium fire suppressible by throwing powder/foam on it?

Isn't a containment building that can dump powder on a fire much cheaper than one that is able to withstand explosions?

Also there are non-flammable salts (eg. FLiBe)?

Here's some footage of Monju - pretty scary: https://www.youtube.com/watch?v=DRJGHWbIxC0

"Molten salt reactors include a radioactive chemical plant"

So.... what happens with solid fuel rod processing that is any different?

Well, I guess they just bury it rather than trying to consume all the fuel?

I think all reactors are evil until proven otherwise. Avalanches and natural disasters happen.

Do we really want nuclear anything in remote areas without human guards? What if someone decides they might like to cause an unnatural disaster?

Everyone says nuclear is safe... but where's the proof it would still be safe without the level of hand wringing we currently have?

If someone wants to do nuclear, they have to prove it's safe. Move fast and break things has no place here.

I can't say what kinds of security analyses we had to do to meet regulatory requirements, because there's a host of things you have to do to even know what security requirements there are. That's not even close to publicly available, for good reason.

I can say we have to analyze to massive vehicle bombs, armed assault, etc.

Here's what the possibly interesting, counterintuitive analysis showed. If you have a plant where a massive bomb can't cause damage to exceed regulatory standards (...we are talking about a truly miniscule amount of material here in this micro fission powerhouse in comparison with the nuclear plants you are probably thinking of... literally not more than a meter tall and wide, underground, below layers and tonnage of concrete and steel) and if an armed assault can't cause damage like that either, are you doing a favor by having a host of armed people on site? Probably not, in fact. Insider risk is then too large. There you go!

(totally agree with no "move fast and break things" here. I'm about 8 years into working on this company and still see many years ahead. we wouldn't be doing anything great if we weren't bringing forward the safest emission-free power plant to reality)

> Move fast and break things has no place here.


This is exactly why I always find it fun to read discussions about nuclear power on HN. Lots of people here are hardwired to only think in terms of software (where it's all 1s and 0s and you can do whatever you want), and then they apply that thinking and logic to real world engineering fields and the logic collapses. Doubly so for the nuclear sector because you can cause catastrophy if you aren't careful.

The question that should be asked is if the faults of the application is severe enough that its worth continuing burning fossil fuels until/if there is a new and better source of energy. That is the counter part when determining a balance between the need for strict regulation and risk assessments. The damage we know we are causing with known technology, or the damage we might cause with new technology.

We have this kind of cost-benefit assessment in other regulations. It is always a trade off between the benefit of having them vs the cost of not allowing it, be it a new food safety restrictions or building codes. A replacement for diesel generators might be worth a slightly higher risk given how much damage those fossil fuel generators do to the environment, and the global commitment to prevent climate change.

That question does not need to be asked. Nuclear power is dangerous and needs to be done with extreme care and extensive regulation. A worst case nuclear disaster can have local and not so local effects which are worse, sooner, and longer lasting than any global warming threat. If you are careful those things don’t happen.

Nuclear accidents contaminate a few thousand square kilometers for a few hundred years at the very worst. Global warming threatens the stability of the whole ecosphere and carbon dioxide levels in the atmosphere decrease in timeframes on the order of tens of thousands of years.

Alternatively, “we asked that question and the answer is ‘yes’.”

I suspect that the current state of things is that nuclear is overregulated on a 'consequences to humanity' basis but not necessarily on a 'convincing humanity to let us ever build more nuclear plants' basis.

If you're competent and do your job correctly then it's possible to get NRC approval on the first try. Doing it right doesn't have to be slower or more expensive.

We can keep working on these reactors for another ten or fifteen years while we put maximum effort into building PV and wind turbines and electrifying everything. It's easy to have 50% renewables on your grid with essentially no storage at all. The world is very far away from getting 50% if its energy needs from renewables.

> if the faults of the application is severe enough that its worth continuing burning fossil fuels until/if there is a new and better source of energy

You make it sound as if the only two options we had were to build these reactors or to burn fossil fuels. These are not the only two options that you have.

Can you say more about this? I'm glad the top comment here is actually about the application itself and would love to read more about this.

You can access Oklo's public combined license application at http://bit.ly/AuroraCOLA, and read more about what's next for Oklo here - https://okloinc.medium.com/whats-next-566bb49b74dc

> There are good answers to that in the U.S. and Russian experience.

What are your personal favorites of what those good answers are? One write up I found [1] doesn't go into much engineering details, and I find similar high-level descriptions elsewhere.

This reminds me of a documentary I once saw about what seemed to me a completely balls-to-the-wall experimental lab (the best kind) studying the earth's magnetic field by rotating a 12+ ton ball of molten sodium.

The way they solved the fire question was by suspending dewars of liquid nitrogen above the ball of death metal. The only way I could think of to improve upon that is a passive trigger design, wrapping the ball with walls of dewars with spring-loaded lids that open up when pressure drops below the level that the liquid nitrogen is normally contained at. If one is breached, they all breach at the same time enveloping the entire sodium footprint.

[1] http://nucleargreen.blogspot.com/2010/01/fire-in-sodium-cool...

Sodium fires are often flashy but not that bad. They look scary because they form hot aerosol particles that radiate a lot of light and heat. It's nothing like a hydrogen fire you might walk into before you see or feel anything.

Sometimes you spill a few liters of sodium and it goes poof and makes some caustic aerosol you have to clean up. If the heat exchanger with a carbon dioxide secondary pops it forms a crust that will probably keep the carbon dioxide inside. Even if a water tertiary heat exchanger develops a pinhole leak the reaction happens on a 2-d surface and develops more slowly than you might think it would.




Russians documented hundreds of fires at a reactor in the 1970s most of which were little poofs, they kept calm and carried on because the prize is clean energy to power civilization for 1000s of years.

Every time I hear "liquid sodium" I think "run away!" How in the world would you make that safe even without the nuclear stuff?

(1) Argon cover gas

(2) Fires happen all the time in industrial facilities. You detect them and put them out. US and Russian literature tells you how it is done. EBR-II, FFTF and BN-800 point the way. Japan shows you how not to do it. (Not detect the fire for a long time, lie to the media about how bad the damage was)

> Fires happen all the time in industrial facilities. You detect them and put them out.

When we're talking about sodium fires in a nuclear facility, though, this comment reads to me like possibly a wry joke? I'm not even 100% sure it wasn't one, so apologies if I am responding inappropriately. It rather reminds me of an emergency physician I know who likes to comment that gunshot wounds are easy to treat; it's mostly a matter of plugging the hole. He enjoys seeing how saying it makes people squirm.

It's meant to be serious and funny at the same time.

Sodium fires are a real problem but they are manageable. If you detect the fires and put them out they are a minor problem. If you let the fires get out of control, let them wreck the equipment room next to the reactor, then try to cover up how bad the damage was to the media that is the Japanese experience with Monju.

People don't realize that Japan led the world in nuclear accidents from 1990 until Fukushima. There is something badly wrong with their safety culture that led to problems at Tokaimura and Monju and their choice to not install a proper backup electrical system at Fukushima. Choosing not to spend $1M to fortify their diesel generators that would have saved billions and billions. Remember it is a choice.

USA and Russia have dealt with the problem realistically and run beautiful and clean machines with sodium coolant. This is one of the nicest industrial facilities I have ever seen:


> There is something badly wrong with their safety culture

I would not be surprised at all if their hierarchical culture and fear of speaking up to superiors played into a lot of these accidents.

> You detect them and put them out.

Well, not molten sodium. You don't put it out. You isolate the fire and let it run.

Keep it inside the box I suppose, same principle as keeping the nuclear stuff safe.

Sometimes you open the box. There could be 'cartridge reactors' that live in a stylish hutch and only get opened at the factory, but if this is the first one they will probably need to open it and poke around inside for some reason.

Even if it only gets opened at the factory then you have to worry about the factory.

That one is reasonably easy. You make sure that you only open the box when it's not molten. It's much easier than the nuclear part.

If the sodium is cold you will have the hardest time getting the fuel rods in and out to refuel.

If sodium solidifies, you gace ruined the reactor - its a metal solid mass in your pipes

Is there a reason why most molten salt reactors chose sodium? There's got to be a good reason to pick it given all its negatives (i.e. it burns in air, water, etc.).

Sodium has great thermal conductivity and runs at high power density.

Fast reactors need a large load of fuel (often high enrichment) to attain a critical mass. High power density helps pay for the fuel. It also means the reactor is smaller and the capital cost goes down compared to, say, a lead cooled reactor.

If you get fuel damage the most biologically dangerous fission product is iodine. The iodine reacts with the coolant to form NI salt, that salt dissolves in the sodium. Dangerous iodine isotopes decay in a few weeks. An experimental reactor melted down in the suburbs of LA in the 1950s and they never saw the iodine because it stayed put and it decayed in place.

Sodium reactors can run at high temperatures compared to water reactors. In the 1970s it was assumed that sodium reactors were attached to steam turbines and it was assumed fast reactors would cost more than thermal reactors, even though the performance of the steam turbine improves at high temperature.

Modern thinking is that a closed-cycle gas turbine is 10% the size of a steam turbine and the same for the heat exchangers so a high temperature reactor could beat the LWR for capital cost and be competitive with other power sources. A sodium reactor is a good match for a CCGT.

I can tell you know this but just to clarify, sodium and lead don't moderate the neutrons like water does (i.e. slow them down), so you can have a fast reactor, which means you can fission your U238 and transuranics instead of throwing them away as nuclear waste.

You can run a water reactor with a much faster spectrum if you have more fuel and less water.

Shippingport was able to breed on the Thorium-U233 cycle.

Plutonium breeding could also be accomplished with a water reactor, possibly with two separate reactors in the fuel cycle to tune up the use of odd and even numbered isotopes. See


The trouble with it is that water has limited ability to remove heat so you are going to have a large amount of fuel tied up creating a critical mass producing relatively little water. That makes it hard to build up the fuel inventory for a fleet of breeders and economics are even worse than today's water reactors.

Lead does slow down sufficiently fast neutrons, by inelastic nuclear scattering. But this has a threshold (0.57 MeV); below that energy it hardly affects neutron energy at all.

The source term for cesium is more important than iodine over the long term, isn't it? What does cesium do in liquid sodium?

Someone else replied with reasons for sodium, just want to mention that molten salt reactors are not sodium reactors. Sodium catches fire in water and air, salt is the stuff on your kitchen table. A molten salt reactor has nothing that could cause a chemical explosion.

The NRC has never approved a new nuclear reactor (which ended up in production). The NRC says the same about every application.

It also took two years for the NRC to provide this rejection.

Please don't excuse incompetence on an issue this important to the future.

Applicants and the NRC have to figure out what the expectations are for a new reactor application to be considered a good application. Oklo is leading the way in that process, I hope they make it through.

It sounds like Oklo didn't bother to try to figure out what the regulators wanted, since they didn't bother to answer the questions of regulators.

I've done some first mover approval work in biology, and yes it's more work, but all first movement is more work in every way because you're pioneering something new. The FDA, at least, is not unreasonable and is usually very open about the bar they think they need to set. You just need to talk to them, request a meeting, and show up. And also realize that it's going to be an iterative process, as any new product design process is also iterative.

I remember someone lecturing about the nuclear industry mentioned that there is an inherent second mover advantage in the industry because the first mover has to figure out all the new stuff and get it approved by regulators. The second mover just follows the template and has a much easier time. If this is truly the case, then it seems like it would be hard to innovate in this space. If so, how can we remedy that?

Slow down the approval of the second mover to match the pace of the first approval.

Calculate the total cost of the approval process. Now divide it by the number of participants and have them each pay an equal share. This means that when the fifth mover comes, they only have to pay 20% of the cost of the first mover, but they're paying it to the people who came before them, so that they're really each paying 20%.

Unformed thought: This sounds like a situation where something shaped kinda like the (or at least an improved form of the) patent system might help.

Limit the regulations. That’s the only way.

I'm often at least sympathetic to anti-regulatory sentiment whether or not I'm fully onboard with it, but not here. The risk to others in operating a nuclear reactor is considerable, and anyone wishing to do so should be required to prove they understand the risks and have mitigated them to a degree acceptable to the public.

Instead, regulators may have opportunities to improve the process to make it easier for applicants to understand what they must do to receive approval. In this case, I have the impression the NRC did adequately explain what Oklo needs to improve in its application.

For nuclear power. Right.



>Excessive concern about low levels of radiation led to a regulatory standard known as ALARA: As Low As Reasonably Achievable. What defines “reasonable”? It is an ever-tightening standard. As long as the costs of nuclear plant construction and operation are in the ballpark of other modes of power, then they are reasonable.

>This might seem like a sensible approach, until you realize that it eliminates, by definition, any chance for nuclear power to be cheaper than its competition. Nuclear can‘t even innovate its way out of this predicament: under ALARA, any technology, any operational improvement, anything that reduces costs, simply gives the regulator more room and more excuse to push for more stringent safety requirements, until the cost once again rises to make nuclear just a bit more expensive than everything else. Actually, it‘s worse than that: it essentially says that if nuclear becomes cheap, then the regulators have not done their job.

US test reactors have a reputation of running very very clean and being safe places to work.

The well-established LWR has had continuous improvement both in terms of reliable performance, high uptime, and reduced occupational exposure for nuke workers.

The cost problem is not over-regulation but: (1) the LWR depends on an oversized steam turbine and heat exchangers that an order of magnitude more expensive than the gas turbines used to produce energy from fossil fuels today; they quit building coal plants in 1980 for the same reason they quit building nuclear plants, the cost of the steam turbine. Even if the heat was free the steam turbine would struggle. (2) Building an LWR is a bungle-bung bridge right out of Dr. Seuss, it's hard to find a complete reckoning but it seems anything that can go wrong will go wrong, everything from All-American Cost Disease to the factory in China that struggles to build the pump that was supposed to be cheaper to manufacture.

Even if LWR construction went 100% to plan, (1) would still make the LWR unattractive. You might be able to add pre or post combustion carbon capture to the gas turbine, compress the CO2 to 1500 psi and inject it into a saline aquifer for less.

If you want "the power to save the world" you gotta quit it with the "conservative" claptrap and take the radical step of coupling a higher temperature reactor to a closed-cycled gas turbine powerset. In the 1970s it was thought that a fast reactor had to be more expensive than an LWR but in the 2020 it is not worth moving forward unless you can do better.

> For nuclear power. Right.

This right here is the problem.

It is actually possible to over-regulate something, no matter what it is. The more people believe something needs to be regulated, the more likely it is to be regulated disproportionate to the need. Consider the safety record of commercial nuclear power in the US.

So some coal company gets a regulation inserted that says that in order to open a new nuclear reactor, you must first push a boulder up a hill for a thousand years.

Later someone does a cost benefit analysis on that regulation, it turns out to be costing a lot while actually making safety worse, so they propose to repeal it.

Headline: Get your Pitchforks, People, They Want To Deregulate Nuclear Power

I was answering the question. What other ways can you achieve innovation without limiting regulation? If the NRC is unwilling to budge, and they hold the keys to the castle, there’s no solution.

I'm not sure why you'd be suggesting that the already captured regulators at NRC should be even more limited, unless your wish were to see some nice nuclear fireworks.

So why is anyone wasting money trying to innovate on this technology in the US?

Surely there is some other nation state that is less risk averse and open to nurturing innovation.

Oh, there is another nation. It's named China.

Two years actually sounds incredibly reasonable for a new nuclear reactor design.

It's a good conjecture, Paul. One might assume that low probability events were a major issue. With a design that is first of a kind, and given that the proven inherent safety characteristics, Oklo could analyze to the most extreme events (as you know, EBR-II showed how this fuel type, with no flowing coolant, and no shutdown systems, would inherently shut itself down http://www.thesciencecouncil.com/pdfs/PlentifulEnergy.pdf).

In this case, that meant assuming that everything above ground was completely gone. The building, the secondary side (power conversion equipment etc), and all human intervention, were all assumed gone. On top of that, Oklo analyzed the simultaneous loss of one of 3 independent shutdown systems. This is obviously a much higher bar than any existing nuclear plant, and for good reason: our mission is to build a new kind of plant with these inherent safety characteristics.

There might be a reason why there wasn't a lot of detail on sodium fires - there is no pool of sodium. The heat pipes use potassium. :) Oklo did tests on what happens in air, if sodium heat pipes were fully breached with huge holes and interacted directly with air. I was there. We just straight up had incredible amounts of energy hitting the heat pipe from myriad solar mirrors. It was pretty fun to test advanced fission with solar thermal. Anyway, there was a little bit of smoke, and actually the heat pipes kept functioning far longer than even the heat pipe expert expected, because the reacted sodium kept self-cauterizing the hole. In this reactor's case, the heat pipes would be in an inert environment, but it was interesting to see what would happen if somehow it were just pulverized in an open outdoor field.

There are roughly 40 external events that had to be analyzed: earthquakes, wind, tornadoes, seiche, avalanches, landslides, wildfires, you get the idea. What happens in our methods was that the worst possible event was analyzed. We took seismic accelerations worse than ever recorded in the history of the entire united states. It turns out, with a thorough risk analysis (based on risk analysis standards set up in the history of EBR-II and PRISM and others), that assuming you lose literally everything above ground is about the most conservative thing that is within the realm of happening once every million years. Keep in mind we were just seeking a 20 year license for a plant smaller than the MIT research reactor, but low-enriched.

But the end result is as you say, we have learned, they've learned, and we resubmit. We believe deeply that if fission is going to make a difference a commercial plant has to be built before the end of the decade! Happy to answer any questions.

Low-probability is not enough to wave away concerns when it comes to planning nuclear power

Yes, but focusing on the astronomically low probability scenarios while failing to discuss much higher probability scenarios is a bad look.

Natural disasters are not astronomically low probability scenarios, they happen all the time. Astronomically low probability would be something that is unlikely to happen during the entire lifetime of the planet.

No, but an avalanche in a flat area is a lot less likely than, say, "what if the coolant runs out" and it seems they were missing some basic handling of these sorts of scenarios while still waxing poetic about things like avalanche contingency plans.

Is it? Those astronomically low-probability scenarios have a track record of creating real-world catastrophes.

This is pretty straightforward survivorship bias, i.e., you don't hear about the astronomically low-probability scenarios which don't result in real-world catastrophes (consider every building, bridge, etc which hasn't collapsed).

We have to balance that against the millions of annual fossil fuel deaths (tens of thousands die each year just in the US and just due to coal pollution https://www.scientificamerican.com/article/the-other-reason-...) and the cliff toward which climate science tells us we're careening.

Survivorship bias may explain why these events are so vivid in people's minds, but when the bar is that _there should be no survivors at all_ (i.e. no catastrophes), the fact that there _are_ survivors with which to form a bias is in and of itself a concern.

It’s a concern which must be weighed against the alternative. In the case of nuclear vs fossil fuels, it’s millions of annual deaths in the near term (air pollution) and much more with climate change.

Fukushima was a power failure. Sure, am improbable disaster caused the power failure, but the issue was still a power failure. They should haven’t been able to handle it and couldn’t.

The power failure is not "low probability", it is the dominant failure mode that happens somewhere around 1 in 1000 to 1 in 10,000 reactor years.

Reactors were licensed in the 1970s based on an entirely wrong model which saw the dominant failure mode being the pressure vessel bursting. Laymen have a totally wrong point of view about that, they think a pressure cooker really has the metal burst and go off like a bomb, really the seal breaks and you get sprayed with superheated steam which is dangerous enough. Pressure vessels burst because the chemicals eat them from the inside out but for every pressure vessel that bursts thousands of storage tanks get sucked in.

After TMI the model was updated to recognize "station blackout" as the #1 risk.

Fukushima currently has a body count of 1 and the city is perfectly habitable.

It was also basically the worst case scenario that could happen to that reactor design.

The tsunami and the earthquake killed 20000 for a scale.

Sure, I think that's true, but it was an event of such magnitude that there's a clear state interest in regulating against it! They had to evacuate a huge area around the disaster, for some time. Sure, it was a best-case scenario, but it was the best case of a worst case.

(I support nuclear power, for whatever that's worth. I think it's a good idea and we should do a lot more of it.)

Only because the high probably scenarios are handled safely...

What? Depends how low the probability is and the magnitude of the worst case we're talking about.

The classic Rickover quote, from the 1950s:

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. (7) Very little development will be required. It will use 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 can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.

The tools of the academic designer are a piece of paper and a pencil with an eraser. If a mistake is made, it can always be erased and changed. If the practical-reactor designer errs, he wears the mistake around his neck; it cannot be erased. Everyone sees it. The academic-reactor designer is a dilettante.

"Little that’s happened in the 60 years since suggests Rickover was wrong." -- Kennedy Maize, 12/30/2014, Power Magazine contributing editor.

My favorite pithy quote is "In theory, it works in practice; in practice, it works in theory."

And the corollary, "In theory, theory and practice are the same thing. In practice..."

Here's the denial letter to Oklo directly from the Nuclear Regulatory Commission:


All Oklo application documents linked to from this top level page: https://www.nrc.gov/reactors/new-reactors/col/aurora-oklo.ht...

While searching World Nuclear News for background about Oklo I ran into this story:

"Oklo to power bitcoin mining machines"


This is dubious on a couple of levels. Micro-reactors like Oklo (1.5 megawatt electrical output per unit, compared to 1000+ megawatts for Generation III reactors currently being built) would be hard pressed to produce electricity suitable for an industry that seeks globally-cheapest prices. Announcing a "20-year commercial partnership" to supply 100 units to a mining firm, before they've built a single unit, is optimistic to the point of recklessness.

The Oklo founders [1], Caroline Cochran and Jacob DeWitte, have no industrial experience, according to their LinkedIn profiles. They met at MIT while TA'ing and went straight from graduate school to founding Oklo.

I just don't think that Oklo knows what they are doing.

[1] https://www.cnbc.com/2021/06/28/oklo-planning-nuclear-micro-...

Ultimately I do not know whether Oklo and/or their founders know what they're doing, though I hope for the sake of the planet that they do and they succeed.

But calling them out for having no nuclear industry experience seems somewhere between aggressive and wrong. Both founders have graduate degrees in nuclear science from MIT and have been in the nuclear industry _at Oklo_ for the better part of a decade. A quick LinkedIn search also shows that Oklo employs other people with nuclear industry experience, including at the NRC itself.

If someone had a PhD from MIT in machine learning and then worked at Google doing machine learning for 8 years, would you say that person has no machine learning industry experience? At face value such a person would seem like a plausible expert!

I mean that they've never been at an organization that actually builds reactors or reactor components. Building working machines, at scale, at a price that customers can afford, is hard even if you're not in a heavily regulated industry. I'd also be skeptical of the chances for a pair of people to successfully move from graduate research in solar technology at MIT to commercializing a new solar cell design through their startup.

Hah, it's the opposite of "you need 5 years of experience in a 3 year old technology": they need X years of experience in an industry that has been dead for the last 40.

Looking at the number of failed kickstarters for physical objects that are multiple orders of magnitude less complicated than a nuclear power plant with new technology might be instructive.

China's been building new reactors, poach some of those project managers.

There aren't any organizations that build reactors though. You'd have to go to France or China.

Even if you really had to go to France or China to get some experts (which is not the case) it would be quite reasonable to expect that they do so; using a combination of modern inventions such as airplanes and money it should be possible to get some of them across the ocean.

Doesn't Westinghouse build nuclear reactors?


They're hoping to get to build some. Not in the US of course.

They're building reactors in the state of Georgia:


Other companies that manufacture nuclear components in the US include Areva, General Electric, and Framatome. But Westinghouse is the only company that has a new reactor design currently under construction in the US.

The US is still fielding new nuclear submarines and aircraft carriers. So, they ARE building new power plants, just...not commercial ones.

France does not appear to have the expertise either, Flamanville and Olkiluoto have been disasters.

Plus, it's really not clear how they could translate their organizational skills to entirely different culture. Maybe it would work, but it's certainly not a sure thing.

> I hope for the sake of the planet that they do and they succeed.

The planet doesn't need nuclear. It just needs a concerted push to roll out renewables on a bigger scale and invest into promising long/medium term energy storage solutions (like various gravity storage solutions)

The opportunity costs for nuclear are just way too high.


> invest into promising long/medium term energy storage solutions (like various gravity storage solutions)

Since when is gravity storage a promising solution for powering the national grid?

If they started an ML company that applied for grants and failed to supply the required information, it would be acceptable to inquire about their expertise.

Academic experience does not equal Industry experience.

Nuclear powered bitcoin mining. How is the human race so smart, yet simultaneously so so dumb?

Sometimes you have to attach yourself to dumb ideas to sell the smart idea. There's a good chance these folks don't care about cypto at all and are just using this to obtain further investment and survive another day.

"We want to build a nuclear reactor to supply energy exclusively to _____." is an easy blank to fill.

Bitcoin mining is actually a really interesting use case as induced demand for a nuclear reactor which cannot easily lower its output beyond a certain threshold. Currently, fossil fuel plants are spun up and shut down to match demand for electricity, if our grid was entirely solar, wind, and nuclear, supply cannot be regulated, but by turning bitcoin miners on and off, you can regulate demand. There are other ways too, of course, such as grid connected EV chargers, but the nice thing about bitcoin mining is that the utility company can operate it themselves and use the revenue from mining to subsidize the construction and operation of the nuclear plant.

From what I understand the purpose of the mining operation is to keep the grid "balanced". "Bitcoin solves this" loses its luster a little when you compare it to running a data center next to that plant, without implicitly gambling the financial success of the nuclear investment on the continued value of bitcoin.

If it displaces fossil fuel based Bitcoin mining that's still a net gain in my book.

Our intelligence is dwarfed by our unlimited greed.

We’re more properly Homo callidus, not Homo sapiens.

They want to put this in the middle of nowhere in Idaho. It wouldn't be worth running transmission lines to connect a reactor this size to the grid.

You could put the bitcoin mine right next to the facility and do something useful with the electricity. It really should be coupled to some real sink so they can see the dynamics of the reactor + powerset + consumer.

Before people jump down your throat with pseudo ethical pearl clutching, just replace "do something useful" with "generate income".

You don't have to personally believe that bitcoin mining is "useful" to acknowledge that it certainly can generate real money to offset the cost of a remote experiment like this one.

I have to admit I'm amazed how sentiment on HN against cryptocurrency has turned sharply negative.

I think a year ago we were comfortable with Bitcoin as a store of value but the NFT craze has made almost all of us adopt the "right-clicker mentality".

Years ago I was an INTP but something happened to me a year ago and I got into doing art projects and I lately scored as an INFP. I told my therapist the other day that, more than anything else, I want to plant my feelings like seeds, intensify and cultivate them, compress them into a ball, throw it at somebody and have it hit them like a lighting bolt.

NFT people drive me nuts because (1) I'm not that good at art, (2) I want to get much better, (3) I know I'm going to do that by really emotionally connecting with people and (4) I can't know I'm really doing it with people who are blinded with NFT greed. (Look at the sh1t they buy!)

I think it's more that people are getting increasingly terrified by the threat of climate change, so anything that uses and "unnecessary" energy is the most evil thing in the world. Naturally, these same people rarely turn their energy use critiques on their own hyper wasteful western lifestyles.

Ironically, bitcoin is one of the few things that gives me hope for a future potentially devastated by threats like climate change.

honestly part of staying sane as a working artist is quickly learning to detach notions of quality and value from one another. robert hughes outlined the depressing absurdity of art speculation over a decade before anyone ever uttered the phrase nft.


all that aside the most surefire way to get better at art is to enjoy it and keep doing things you enjoy, in perpetuity,



It is an old story. I was doing some reading to try to get into the head of somebody who'd been involved with the art world and came across


which was a cynical take from 1975.

"The Oklo founders [1], Caroline Cochran and Jacob DeWitte, have no industrial experience, according to their LinkedIn profiles."

So Theranous all over again?

Having read possibly too much Matt Levine my first thought wrt the Bitcoin things was "this is an investor relations move".

Hand picked by Sam Altman. Lol

> no nuclear plant that has submitted an application since the formation of the NRC in 1975 has yet commenced operation.

Wait, what? I knew that reactor construction stopped around then. I hear it alluded to often enough, e.g. "US grid could have been 100% low-CO2 power by now if we had just kept up the pace of deploying nuclear instead of stopping in the 80s." Still, I thought the story was a messy mix of regulations hitting at the same time as city growth was topping off and interest rates were skyrocketing.

If the NRC just says "no" to everything, that's a big deal. Is there more to the story?

The NRC said "yes" to 4 new AP1000 reactors in Georgia and South Carolina more than 10 years ago. They were all supposed to be completed years ago. The South Carolina project was abandoned after cost and schedule blowouts. The Georgia project continues to chug forward despite similar cost and schedule blowouts. Here's a brief synopsis of the Georgia project:

On August 26, 2009, the Nuclear Regulatory Commission (NRC) issued an Early Site Permit and a Limited Work Authorization. Limited construction at the new reactor sites began, with Unit 3 then expected to be operational in 2016, followed by Unit 4 in 2017, pending final issuance of the Combined Construction and Operating License by the NRC. These dates have since slipped to 2022 and 2023 for Units 3 and 4, respectively.


Right, but one interpreation of this fact is that they set the bar for compliance too high, so it's almost impossible to finish a reactor in a financially feasible way.

Unfortunately, there seems to be no way for our society to overcome the apparent moral high ground that nuclear skpetics hold. Nuclear disastors are too good at capturing the imagination and all a skeptic has to say is "you can never be too safe."

Meanwhile, we claim that our reliance on fossil fuels is a disastor, but if it's not enough of a disastor to compel us to make nuclear regulatorily viable, how much of a disaster can it really be?

It not being financially feasible to finish a reactor and comply with the regulations doesn’t mean they’re set too high. Maybe it just means you can’t have safe AND financially feasible nuclear right now.

It actually does since other countries are actually building nuclear plants. I bet if you traced through the NRC membership you would find government malaise and industry connections stopping new reactor designs from making their way through.

Thanks for the context!

Yeah, that syncs up better with my intuition: disasters plus bad economic timing killed the industry in the 80s and it hasn't gotten back on its feet because big projects are hard enough with momentum and the industry has to start over from zero.

Here's hoping they can get back on their feet!

Westinghouse Electric Company (the reactor manufacturer) took over construction management in 2015 after the first constructor botched schedules and costs. Westinghouse subcontracted to Fluor. In 2016, adding Bechtel.

In 2017, Westinghouse declares Chapter 11 bankruptcy from construction losses, and the final owner Southern Company reselects Bechtel as the construction manager.

Current operational date looks like 3Q 2022, and on track.

tl;dr - Don't allow megaproject management experience to atrophy. The US military learned this (see: how the Navy builds carriers and nuclear subs). Have a prime and a secondary. Rotate. And, for god's sake keep the pipeline full. Skills atrophy and knowledge is forgotten.

The South Carolina reactors were abandoned. Vogtle looks on track to spin up this year. Vogtle was held up a long time because the index reactor of the type in China was held up while the factories were taking a while to figure out how to make the parts.

In so far as a water reactor could be practical (awful economics of the steam turbine and steam generators) the AP1000 looks pretty good.

How is it that four AP1000 reactors are built and running in China, that the companies building nuclear reactors have a long and apparently successful history of providing reactors to the US Navy, and yet trying to build two in the US bankrupts the company?

One of the advantages of China's large and diverse reactor programme is that when they are building FOAK designs and something comes up that holds up the work (as it did on both their AP1000 and their EPR builds), they put their nuclear qualified workforce on buses and move them to other builds.

Compare that to Flamanville, Olkiluoto, and the US AP1000 builds where every time there was a work stoppage to review a detailed design element, a massive and expensive workforce just had some paid chill time.

If I had to guess, neither China nor the US Navy care about generating a profit from the reactors.

There used to be four under construction in the US. Those in South Carolina were left partially built instead of spending even more money trying to complete them after the project went off the rails. Regional newspapers have gone into great depth explaining what went wrong. Here's a recent article from the Atlanta Journal-Constitution about problems building the Georgia reactors:

"How Georgia nuclear project’s big finish went so wrong"


There were even worse problems in South Carolina that actually led to federal criminal convictions:

"Former Westinghouse Executive Charged with Conspiracy, Fraud in Connection with V.C. Summer Nuclear Project"

Former Westinghouse Electric Co. Senior Vice President Jeffrey A. Benjamin was charged with 16 felony counts, including conspiracy, wire fraud, securities fraud, and causing a publicly traded company to keep a false record, for his part in failing to truthfully report information regarding construction of new nuclear units at the V.C. Summer nuclear plant in South Carolina.

Benjamin is the fourth individual to be charged in the ongoing federal investigation. Former SCANA CEO Kevin Marsh, former SCANA Executive Vice President Stephen Byrne, and former Westinghouse Vice President Carl Churchman have all pleaded guilty to federal felony charges for their roles in the matter.


Here's a big investigative series that the Charleston Post and Courier did about the problems with the VC Summer expansion in South Carolina:


See this chart:



Apparently they approved NuScale's Small Modular Reactors:

NuScale spent over $500 million and more than 2 million labor hours to compile the information needed for its design certification application.

> If the NRC just says "no" to everything, that's a big deal. Is there more to the story?

The NRC doesn't say "no" to everything; AP-600/1000 designs were approved, an SMR design has been approved. The NRC is entirely willing to approve competent design efforts.

The most candid explanation of the attitude of the NRC was offered by former chairman Dale Klien and his "no bozos" baloney test; there is no room in nuclear power for hucksters and the NRC won't indulge them. This rejection is evidence that this mentality still prevails; failure to respond to NRC questions about reactor design in a timely manner is bozoery and this is the correct outcome.

The Oklo proposal isn't some generational variant on PWRs. They are proposing a fast breeder. You can't go to the NRC with a fast breeder application on anything less than a multi-billion dollar R&D operation designed to positively thrill the NRC with actually epic levels of competence and preparation and expect to be approved, and that is exactly how it should be.

What stopped the first nuclear buildout in the US was a combination of things. One is that the 7%/year growth in electricity demand suddenly moderated. This caught some utilities by surprise; if they had many NPPs in process they were in for pain (WPPSS went bankrupt). Another is the passage of PURPA in 1978, which started to open the grids to non-utility power. Cogeneration started to take off then. Any industrial activity that needed heat could now drive a combustion turbine and sell some power at low marginal cost, using the waste heat for their need. There were also some cogeneration-in-name-only non-utility plants that were mostly just to make power.

All this made large, new, expensive nuclear plants difficult to justify. TMI was just the icing on the cake.

The more recent "nuclear renaissance" died because natural gas become very cheap (and a combined cycle NG power plant costs $1/W to build; a factor of 10 cheaper than a nuclear plant) and because nuclear construction was more expensive than promised (bye, Westinghouse).

To be fair natural gas is only cheap because the cost to the environment isn't factored in. The cost of nuclear power is pennies when compared to the decimation global warming will bring to the human race.

Even so, natural gas in the US is so cheap that the CO2 charge that would be needed for new nuclear to compete would be very high, so high that very large CO2 emission reduction would occur elsewhere first.



“The cost of new nuclear is prohibitive for us to be investing in,” says Crane. Exelon considered building two new reactors in Texas in 2005, he says, when gas prices were $8/MMBtu and were projected to rise to $13/MMBtu. At that price, the project would have been viable with a CO2 tax of $25 per ton. “We’re sitting here trading 2019 gas at $2.90 per MMBtu,” he says; for new nuclear power to be competitive at that price, a CO2 tax “would be $300–$400.” Exelon currently is placing its bets instead on advances in energy storage and carbon sequestration technologies.

Reminds me of that FDA reviewer who refused to approve any drugs on the grounds that risk couldn't be completely eliminated.

A common solution to the Trolley Problem.

got a link?

Below your quote, it says that NuScale has gotten approval. It’s not that nobody has gotten approved, it’s that nobody has commenced operation.

NuScale will, after about 15 years of engagement, receive a design certification later in 2022. After that- they will still need to apply with a combined license application like Oklo did.

Each of the words there happens to be significant.

- plant: plants that had reactors first approved earlier have since had reactors approved that will commence operation soon (Vogtle is the classic)

- commenced operation: designs exist that have been approved but haven't commenced operation

One could argue that the NRC only approves commercially unviable designs or something like that, I suppose. Or that we have just as many plants as we need and we just need more reactors. Or that the general stance of the public has shifted away from nuke.

You're misreading the claim. It's not that they have not given any approvals, it's that those reactors did not go on to reach operating status. That means these are more likely to be business problems, not regulator problems.

I don't think it makes sense to talk about the business of building nuclear reactors as something separate from regulator problems. The two are very tightly intertwined.

Four AP1000s are operating in China right now, demonstrating that under different regulatory regimes, the plants can be built.

The question then, is whether a Chinese regulatory regime (or any other sort of Chinese regime) is something the US should aspire to emulate.

I don’t see that as a useful question at all. The fact that China has working AP1000 reactors is one piece of circumstantial evidence that regulatory regime has an effect on the ability to build nuclear reactors in a timely way.

If you think that the regulatory regime plays a role, then there are three obvious questions to ask: (1) is our current regulatory regime Pareto optimal on a safety versus build time plot? I.e. are there changes that we could make which improve build time without negatively affecting safety? (2) should we consider moves along the Pareto front? I.e. should we trade some safety for some construction speed? Or vice versa? (3) are there things that we can learn from other regulatory approaches that would help us address question 1 or 2? Your proposed question fits under here, but it should be much broader than the way you posed it.

I was confused by the wording of that as well! I guess it would have helped if they put "yet" at the end of the sentence.

No worries. That’s only 47 years. Not too long in terms of new energy technologies.

Sophons at work.

Maybe the sophons should have paid more attention to Chinese literature?

Anti-nuclear lobbyists and demagogues have infiltrated the regulatory bodies in the US and Europe.

The NRC has approved several designs over the years. It's always a good idea to doublecheck what people say, even if it confirms your bias.

I don't get why the first response of the startup is to go on the attack and fight the NRC without responding to the substance of the claims. This is the part of startup behavior I really dislike. Fake it till you make it and be loud and boisterous and brash but still deflect and push vague promises. It's hard to put the required trust in these companies when they react like this. Don't they want people to trust their offering? Especially in a market where trust is everything? Calm down startup founders and stop blustering your way to "success".

This behavior is rewarded in the world of founders though. It’s always fun to watch people like this confront serious regulation. I once advised a startup that had to deal directly with HIPAA and the petulance of these MBAs was honestly kinda funny.

Oklo's response...


>We woke up a few days ago to incredibly surprising decisions by the NRC. Although Oklo responded to every request for information, and the last thing we heard from the NRC was that the information we submitted was helpful, the NRC has denied our first application on the basis of not having submitted information. The NRC has now gone from having one combined license under review to none.

I find their public response unprofessional and immature. The Nuclear regulatory process is similar to other federal and international public-safety regulatory processes such as aviation, medical, and wireless: companies soon learn that it is best to work with the regulations and regulators and not fight them.

A relative of mine with the background to have an opinion on it once told me about how companies were vaporizing millions and billions of dollars for not properly cooperating with regulators and it was just baffling to them.

In reading over this, I honestly became more worried about the prospect of this company building nuclear reactors than before I read it. This is not a professional response that breeds confidence. It is... petulant.

> Oklo will respond to the NRC letter with a letter clarifying things that cannot be left the way they were characterized. So you will see that soon. But mostly, we want you to know that we are moving ahead. With your support, this will generate positive change. This is a distraction, but it may ultimately enable us to move ahead even faster. We look forward to continuing to share more about what is next for us as we move forward!

Did they even run this article by a copy-editor? It's pretty poorly worded, like one of the founders stayed up until 3am to pen this post.

Wow, that part of the response just sounds unhinged. Characterizing a response from their industry's governing body as "a distraction" is immensely concerning.

I'm sure that phrasing will endear them to the NRC.

It's funny given what the NRC letter says about that same time period:

> The staff determined that neither topical report contained sufficient information to initiate detailed technical reviews. Each report contained conceptual information, rather than repeatable methodologies, and each left many issues unresolved and open for future potential applicants referencing the topical reports to address. The NRC staff informed Oklo of the insufficiency of the topical reports by two emails dated August 5, 2021 (ADAMS Accession Nos. ML21201A079 and ML21201A111), that included attachments describing in detail the supplemental information Oklo must provide for the NRC staff to begin the detailed review of each topical report.

> By letters dated October 5, 2021 (ADAMS Accession No. ML21292A325), Oklo submitted revised topical reports for the MCA and PBLM methodologies. The NRC staff conducted a completeness review of the revised topical reports and determined that Oklo provided no new substantive information and failed to fully address the information gaps identified during the original completeness review and discussed during public meetings

There are also a few places on the NRC letter that hint at the NRC's frustration with Oklo:

> letter dated November 17, 2020 (ADAMS Accession No. ML20300A593), the NRC staff informed Oklo that Step 1 was completed for the area of applicability of regulations. The NRC staff’s Step 1 review focused on regulations Oklo identified as not applicable to its Aurora design and did not evaluate the acceptability of requested exemptions. By letter dated December 21, 2020 (ADAMS Accession No. ML20357A002) Oklo informed the NRC staff that they intend to pursue further engagement on the topic of applicability of regulation


> On December 2, 2020, during a routine scheduling call, Oklo requested that the NRC staff temporarily pause its review and stop developing additional RAIs for the Aurora custom combined license application;

> The NRC’s docketing decision for the Aurora custom combined license application was designed to obtain the necessary additional design information from Oklo and complete Step 1 activities within five (5) months. The NRC staff engaged extensively with Oklo to complete Step 1 through numerous meetings and by conducting audits, requesting additional information, and clarifying its information needs. More than a year has passed since the application review commenced, during half of which the technical review was paused at the applicant’s request. Oklo’s proposal to develop generic methodologies to address the topics of MCA and classification of SSCs was not successful in closing Step 1 of the review, and foundational issues identified during the Aurora custom combined license application acceptance review remain unresolved. Accordingly, the NRC staff is unable to complete Step 1 of the two-step review, or establish a reliable and predictable schedule.

Given that, I sure hope that cooler heads at Oklo prevail and they don't follow through on:

> Oklo will respond to the NRC letter with a letter clarifying things that cannot be left the way they were characterized. So you will see that soon.

That really doesn't seem the way to resolve the issues Oklo is having with the NRC.

This is a huge issue for nuclear power generally. It is incredibly expensive to navigate the regulations. Oklo thought they were good and now they need to spend millions and millions more to apply again. (I’m assuming good faith on Oklo’s part). I really think there needs to be serious reform at the NRC.

You call it an issue, I call it a boon.

I do not want nuclear power approved quickly, or easily. I want it to be burdensome, difficult, and with a massive requirement for proving out safety in even the most unlikely of scenarios.

This area does not need Silicon Valley style disruption at the cost of endangering lives and destroying the earth.

This is very much "status quo" bias, as if the current state of the world were not endangering lives and destroying the earth.

People talk about climate change in apocalyptic terms until it actually matters in real world decisions for things other than the things they wanted to do anyway.

>This area does not need Silicon Valley style disruption at the cost of endangering lives and destroying the earth.

We are currently destroying the earth because we are stuck using technology from the 1800s to power our 21st century society. Yes we do need silicon valley style disruption.

Give them a pacific atoll, or an old oil drilling platform, and let them do whatever they want.

We have the tools we need, already, to avert the catastrophe.

Problem is it will cost the rich and powerful a little opportunity cost and a bit of wealth.

The looming climate catastrophe has political and social solutions. Not technical ones.

Storing wind/solar energy for a long enough duration to prevent long-tail blackouts, while also transitioning buildings to electric heat, is a pretty big technical problem.

Pumped hydroelectric storage is a "big" problem in that the scale is large, but it's not particularly complicated. The solutions exist, and they're comfortably boring, and trivially scalable and redundant.

Moreover, we're still pretty far from the point where this even becomes an issue. We can accelerate the deployment of renewables a lot before this is a real constraint on anything.

We don't though, or we'd be using them. Nuclear is clearly the only current technology that can provide the same type of grid available electricity that we're used to AND actually exists Now.

That is twentieth century thinking. Central power plants with a grid to distribute

In the future (I predict) it will more and more be distributed both production and consumption.

The technology all exists. But it does not suit the concentration of power. It will take democracy (people taking action - perhaps direct action) to avert the catastrophe.

I am optimistic.

I do not thing regulatory hurdles are what's stopping us from building more nuclear plants but public funding and will. So if a bored billionaire wants to enter this space, he won't be stymied by the approval process or need to sidestep it.

This seems not grounded in reality.

The article is really sparse on what information was missing. Neither the NRC or Oklo specified what else is needed. It’s probably wise to give both sides the benefit of the doubt.

While the article doesn't reference all these details, the NRC's denial letter to Oklo covers more of them: https://www.nrc.gov/docs/ML2200/ML22006A267.pdf

The claim from the NRC in that letter is:

“Oklo’s application continues to contain significant information gaps in its description of Aurora’s potential accidents as well as its classification of safety systems and components,” Veil said. “These gaps prevent further review activities. We are prepared to re-engage with Oklo if they submit a revised application that provides the information we need for a thorough and timely review.”

(phew, that PDF does not copy/paste text cleanly, at least not in Safari. Had to re-type it.)

That sounds reasonable to me.

What are the gaps?

Asking for more information until the other party gives up is a tactic -- as is refusing to provide damning information. It's hard to say which game is being played, or even if any game is being played at all, without knowing details.

From Rod Adams: Oklo's COL application is part of an effort to achieve a difficult, but important goal. The company has challenged the standard way of doing things and designed a nuclear power system that is as different from a conventional reactor as a gasoline powered scooter is from a 100 MW slow speed diesel pushing a large container ship. Oklo submitted a license application they believe satisfies the letter and the intent of the governing regulations in a form appropriate for its proposed system. The NRC reviewers are not yet satisfied with the information provided and left open the opportunity to modify the application to fill in the gaps it believes exist. The NRC chose to deny the application instead of continuing the process of obtaining additional information. That might have been stimulated by a legislative timeline of 3 years from docketing to final determination. I expect Oklo will be resubmitting its application before the end of the summer.

Longer explanation

Oklo's application doesn't follow the Standard Review Plan format. That 4,500 page document of regulatory guidance fits the large light water reactor systems, structures, components, and processes it was designed for. But it is unwieldy and inappropriate for Oklo's reactor design. Reviewers are used to the SRP and the applications produced using its specified format; they are not yet comfortable with the way that the Oklo application provides required information.

The NRC's denial of Oklo's novel COL application is a disappointment, but it's not a complete surprise. Oklo is doing something that is difficult by pushing change in a federal regulatory agency whose processes and procedures have been developed over decades to focus on a particular kind of reactor. Oklo's 1.5 MWe reactor uses liquid metal filled heat pipes to passively move heat energy out of a few dozen assemblies containing metallic alloy fuel rods. That is a completely different machine than a 1,000 MWe reactor that pumps high pressure water through a core made up of hundreds of assemblies consisting of a bundle of hundreds of thin walled tubes filled with UO2 pellets. Oklo and the NRC review team have worked diligently to come to an agreement that the COL contained information required for a complete safety review. Oklo has answered every request for information it has received, but the NRC has judged those responses to be not yet complete. The NRC had the option of obtaining information it thought was missing through another, more focused round of RAIs and response. Under the pressure of a Congressionally mandated deadline of 3 years for reviewing a docketed application, it chose to deny the application "without prejudice." This gives the NRC the opportunity, outside of a formal license review process, to communicate what they believe is missing from the application. It gives Oklo the opportunity to produce a better application that fills those information gaps.

Pertinent info FTA:

Oklo co-founder and COO Caroline Cochran pointed out the stunning fact that no nuclear plant that has submitted an application since the formation of the NRC in 1975 has yet commenced operation.

Assuming accuracy, that's a damning statistic. I don't believe for a minute that every single application that's crossed their desk for nearly half a century was so flawed or unsafe that it was unworkable.

Knowing what I know of governments and bureaucrats, I'd speculate that they're being asked for a bunch of irrelevant or impossible (i.e. doesn't apply to their design) information, and the people in the bureau are being useless and obstructive about it since there's no downsisde for false negatives.

Not really, it is very specifically worded to paint the NRC in bad light. Vogtle, Virgil C. Summer and company have gotten the applications regarding their designs approved. They just haven't managed to bring the construction to a finish yet.

The NRC may be the culprit there also, but that is a completely different question.

Aren't those standard LWR designs? Have any new technologies been approved?

None have commenced operation, but NRC has approved applications for new nuclear plants.

It's easy to blame regulators, but a big factor is simply cost. For the last 20-30 years, low fossil fuel costs in the US have meant that the huge investment needed to get a nuclear plant from application to operations didn't make sense. Westinghouse Electric went bankrupt in 2017 because of it. Add in that nuclear has been very out of favor with the public, it makes it really hard to get a reactor built.

It's pretty carefully worded, even if that's true it's possible that NRC has approved lots of applications that haven't commenced operation for other reasons. It's bad regardless, but unclear if NRC is rejecting everything or if projects are failing because of other factors.

I'd imagine that the initial application is not the only touch point.

It’s not that the applications are denied, it’s that they haven’t started operation. Below that quote it mentions another company that has gotten approval.

It's a little misleading since the expansions at Vogtle in Georgia are scheduled to finish this year and next year.

That’s still 47 years assuming the Vogtle is actually finished this year.

There was an interesting discussion of this on Twitter the other day when Patrick Collison posted about it:


Also part of bureaucracy is cronyism. There's a lot of big contractors working for and with the NRC who might not like any new competition.

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