Posts by Nick_Geary

Small nuke reactors are really coming online by next year, US energy secretary insists

Re: Micro reactors and technology demonstrators

"Whether they can have one of those running within a year depends on whether someone has the parts to build one already sitting around, and even then it would be a stretch."

It may depend more on the speed of the regulators. The only team in the U.S. who currently has permits to build demo reactors is Kairos Power, and they have already shown they can quickly build reactor vessels. (Their latest vessel was built in the UK a few months ago, making use of Sheffield Forge's electron beam welding process, which greatly reduced build time.) But a permit to build the demo facility is just the start of the paperwork. The onsite NRC inspector has to sign off on every pour of nuclear-related concrete. And they are still working through the process to get their fuel and production line certified, to get a permit to make the fuel, another to transport the fuel (in certified casks), another to load the fuel, and site and personnel licenses to actually operate the reactor. They are not currently expecting to get through all the regulatory certification, permit, and licensing requirements before 2027.

Molten salt nuclear reactors slated to power Google datacenters in 2030

Re: Reliable sources?

[And the downwards reflectance is roughly double the incoming solar energy absorbed at the surface.]

"I have to assume you're mistaken, or are kidding."

I'm not kidding, I could, of course, be mistaken. But it's also possible you didn't understand me, or that you reject the information I've seen.

"Insolation is rougly 800W/m^2 from that incoming solar energy."

Is that a flat-facing measure? I'm pretty sure the global average is more like 340W/m^2. But also, I said "solar energy absorbed at the surface". That doesn't include reflected light (not absorbed) nor high-altitude absorption (not at the surface). And not every Earth energy diagram includes the downward reflectance, because some are only tracking net values in and out. But here are samples which do include it:

https://oceanwiki.ethz.ch/lib/exe/detail.php?id=lecture1%3Aenergybudget&media=figures:global_mean_energy_budget.png (Solar absorbed at surface 161 W/m^2; reflected radiation absorbed at the surface 333 W/m^2)

And https://www.noaa.gov/sites/default/files/2021-12/energy_balance.jpg (47 units solar heat value at surface; 98 units reflectance heat value at surface)

So, the reflectance heat value is 2.07 and 2.08 times the solar heat value at the surface in those diagrams--or like I said, roughly double.

"Albedo is an important factor in climate change because it determines the amount of energy from the Sun that the Earth absorbs,"

And combustion particulates have been increasing reflectance both directly (sulfur-oxides are highly reflective) and through contributing to cloud condensation. Which is going to be a problem we'll have to deal with as we scale down the combustion particulates.

https://www.science.org/content/article/changing-clouds-unforeseen-test-geoengineering-fueling-record-ocean-warmth

"Also you might find this article interesting-" https://wattsupwiththat.com/2025/08/21/how-co2-both-warms-and-cools-our-atmosphere/

If the energy-stealing properties of oxygen and nitrogen work as described, then right there you have your mechanism for delayed radiation into space. But the first paragraph claims "Oxygen and nitrogen comprise 99% of our atmosphere. Those molecules do not absorb or emit radiation." That would mean if you have pure oxygen or pure nitrogen, they won't emit any infrared no matter how how much you heat them. That just seems wrong. I think I'm going to need to see some evidence for that claim.

"My bad, I should have said Technetium-99 rather than Technetium-99m."

Okay, yeah, Sellafield definitely discharges technetium-99. Like, hundreds of kilograms over the years. Tc-99 has a very weak beta decay energy, with no gamma emissions, so it's a low-impact radionuclide, but even so, it's really bad for public relations to be discharging it--even if the medical industry also does it. It's also kind of a waste, since Tc-99 is just one neutron capture away from becoming stable and valuable ruthenium 100.

"But a huge problem with climate 'science' is the activists frequently deny the right to participate, or worse. Sceptics were rebranded as 'deniers' "

I've seen both involved in the climate debate. To me, they are distinct. A skeptic acknowledges that warming could be occurring according to the mainstream view, but has not yet found the case convincing. A denier rejects the mainstream view and believes the warming model is false. But in popular perception, I expect many people don't see that distinction. In like manner, I happen to think the Big Bang theory is unconvincing and has some serious problems, but I don't consider myself a denier because I allow for the possibility that maybe the general theory could be salvaged and made workable with some modifications. Even so, I've definitely been called a denier by some people.

" $2.3bn is maybe 1/3rd to 1/4 of the amount given to UK 'renewables' subsidy seekers and then there's more money to be made promoting carbon credits and trading. But trillions being wasted to promote 'Net Zero' which will result in no measurable effect on temperatures. It would be far better to invest that money in nuclear instead, especially as it's our money being wasted."

I see good potential in a well-run carbon credits market, though I also think we don't have one of those yet. I also think there are good and bad ways to do nuclear, and I would rate any that are so expensive that they will actually drive energy prices up as also being an extravagant waste. On that count, I am just mystified by how the UK has been trying to do nuclear lately. Something has gone very wrong from the days when the UK was a world leader in nuclear science and engineering--including being the place where Triso fuel was invented. Oh well. At least other countries will benefit from that.

Re: Reliable sources?

[If our infra-red photons could reach space that quickly, our night-time temperatures would plunge precipitously every night.] "Well.. it does."

If it only took a few seconds for infrared photons to reach space, even equatorial regions would fall far below freezing every night.

"So the difference between Tmin and Tmax is greater than the increase in Tmax attributed to anthropogenic CO2."

Sure. The net warming is only on the order of a few degrees per century. Just like daily variability is of much larger magnitude than the daily drift due to seasonal changes. But a small but persistent trend in the noise can eventually accumulate to a large difference.

"Basic CO2 dogma is it somehow 'traps heat'"

It slows down its egress.

"because upwelling IR is re-radiated back downwards."

And the downwards reflectance is roughly double the incoming solar energy absorbed at the surface. (And that was the case long before humans came along, but now there is a small change in that ratio.)

"Yet all the PR is around Tmax, "

I'm pretty sure it's about averages.

"which could have other causes"

Possible. But human activity looks like the most likely long-term trend cause.

"But yep, when a CO2 molecule sheds a photon, it'll be emitted in a random direction. Which means if, say, it's emitted from a valley floor, it's more likely to hit the ground again"

And with multiple absorptions and re-radiations in the air, the net downwards emissions nearly equal the net upwards emissions.

"but the higher it rises, the probability increases that it'll miss."

Or that the upward emissions will, on average, get slightly further before reabsorption than the downward emissions into denser atmosphere.

"the massive eruption of Hunga Tonga kicked gigatonnes of H2O high into the atmosphere. Theory goes that would lead to a few years of warming,"

I'm pretty sure water cycles through the atmosphere a lot faster than that. The oceans put around 440 trillion tonnes of water into the air each year. But warmer air does hold more water vapor, so we could see water vapor amplifying warming effects.

"Act Now! and lock in trillions in spending to fight the War on Warmth, banish the CO2 molecule and solve a problem that might not actually exist."

It's possible surface warming isn't happening, but the odds are small. It's pretty clear the glaciers are receding, as is arctic ice, and our upper atmosphere is getting colder and we are radiating less heat into space. It's possible we aren't the cause of the surface warming, but the odds are small. And there are certainly some very expensive ways to constrain CO2 emissions, some of which will probably make warming worse, but that doesn't mean we have no good options. I think a transition to nuclear hydrocarbon fuels will ultimately save money (and reduce pollution and destructive mining and save lives and all that good stuff) and once we have that capability on a large scale, we could use a fraction of that capacity to set atmo CO2 to whatever level we want. We could also knock down the worst of the hydropower dams and maybe restore some river ecosystems and fish runs. Abundant cheap energy gives us all kinds of options.

"G.Brown Esq .. spent time scouring our shores, finding particles of Technetium-99m and screeching this was 'proof' that Sellafield was leaking..

Technetium-99m has a half-life of approximately 6 hours. It is highly unlikely that could be coming from Sellafield.

"Climate 'scientists' aren't energy experts and shouldn't be part of the energy policy conversation."

I think everyone has a right to participate in the conversation. And it creates a dilemma for anti-nuclear climate activists when leading climate scientists come out strongly in favor of nuclear development. I like to see the controversy. That's where change happens.

"Nuclear has an excellent safety record, waste is manageable, but overcoming decades of anti-nuclear FUD is challenging, although we do appear to be heading in the right direction at last."

Anti-nuclear organizations in the U.S. alone rake in more than $2.3 billion per year and the product they are selling is FUD, which I imagine is pretty cheap to manufacture. They are not going to give up such a lucrative business model easily or willingly. And their longtime supporters are going to find it hard to come to terms with the prospect that they may have been fighting on the wrong side of this issue, and donating lots of money to make things worse, and they'll find it easier to retreat into the alternate-reality cult bubble the anti-nuke leaders are creating for them. Considering what it takes to overcome such factors, the dramatic rise in public acceptance of nuclear is even more remarkable and impressive.

Re: Flipping the Script

When they were doing site excavation for the Kairos demo plant where an old diffusion enrichment facility used to stand, they encountered a lot of buried power cables, cooling pipes, broken tools, and some demolition debris from another site. And while that was annoying and slowed them down, the nightmare would have been if they had dug up something of historical, or archaeological, or Native cultural significance. Or encountered an unknown geologic fault. Or found some rare burrowing creature. There's a lot less of that to deal with out in the ocean.

You can buy a remarkably large, double-hull supertanker, brand new, for only around $100 million, and a power station hull would be much smaller than that. Robotic welders and material handlers have revolutionized ship building. And we already have lots of advanced ship yard production capability around the world. No need to set up a special factory just to crank out nuclear power stations.

Re: Reliable sources?

[CO2 sequestration for verifiable carbon credits.]

"Enron were also pioneers in this field, lobbying hard for creating a carbon market that thus far has proven to be massively fraudulent."

And piecemeal, and mismanaged, and diluted with misguided good intentions. Yes. All that. To work, it has to be a large system with many parts, and the process of assembly is unavoidably going to be messy. This cannot be put together by fossil companies alone, nor by individual countries. This needs to be an international market, which means it needs a global oversight board. And the credits need to be based on CO2 removal which can be monitored, measured, validated, and audited. But all the largest players want this, so there's a good chance it can happen.

"One popular scam/scheme was trading trees for offsets"

And the inclusion of credits for forest-preservation in some markets was also a mistake. Nice idea, but it doesn't belong there.

"Plus a new casino for a new commodity and trading profits."

That's a problem for the C-credit producers and customers to work out. The important part is to establish a market where in order to release a unit of CO2, someone, somewhere, has to verifiably sequester the going exchange-rate unit of CO2. (Probably under-unity at first but potentially going to over-unity as the market matures.)

This is better than cap and trade because it wouldn't base the currency on previous emissions, and better than carbon taxes because 1) it would be international, and 2) because it wouldn't just penalize emissions, it would also reward capture and sequestration--and fund the development of an industry to do that.

"But could also incentivise reforestation,"

Only if they can figure out the validation. If not, then we should look for a better vehicle for that elsewhere.

"except that's offset by Drax burning forests"

Ironic that it was treehugger activism that drove the creation of the standard Drax exploited.

"But I've long been a fan of the Sabatier & Fischer-Tropsch processes."

I suspect we've just barely scratched the surface of their potential.

"so 'peak oil' is a bit of a myth when we can just make more.. If we can solve the cost problem."

I think Kairos will solve the capital cost problem. The fuel, on the other hand, will be a lot more expensive than traditional nuclear--something like $10 per MWh(th) at first. But their fuel looks like a good candidate for cost reduction through mass production. A barrel of oil is currently running around $38 per MWh(th), and I gather Fischer-Tropsch energy efficiency is generally around 50%, so even at the high initial price, that's not a huge distance from competitive price territory. When we develop molten salt fast reactors, the fuel cost will be effectively free, so their challenge will be constraining the cost to build and operate them. These are the reactors we really need, but the business case for them is very tough. The basic principles are virtually unpatentable, and the first-mover regulatory costs will be horrendous (if we don't fix that).

"At least Texas could use the CO2 for enhanced recovery, but the fundamental problem remains. Spending billions to produce a product that is then just dumped into holes in the ground. So massive costs, and no economic benefit."

That's what the carbon credit market would be for. It's like the billions we spend on sustaining crypto-currency, except this currency would be based on something real and doing actual good.

[between a third and a half of the heating potential is being masked by the shading effect from our combustion particulates.]

"There is a measurable effect, but the causation is by no means certain."

All science is probabilistic. But we can measure the dimming effect, and the reflectance effect. The main indeterminate value is how much the low-reflectance particulates have shifted solar absorption from the ground and lower atmosphere to the upper atmosphere (where re-radiation into space happens quicker).

"But it won't. The physics of CO2 are well understood. 4 absorption/emission bands, 3 overlapping with the dominant 'GHG', H2O."

Even the overlapping bands can add to the greenhouse gas effect. And yes, the effect is small relative to H2O. But in total system terms, warming is also a small effect. Absorbed solar energy averages something like ~240 W/m^2 and the imbalance is currently running around 0.76 W/m^2, so it's only around 0.3% difference between energy absorbed and energy radiated.

"and the 'Greenhouse Effect' only 'traps' heat for a tiny fraction of a second before those photons continue their inexorable journey upwards to space."

If our infra-red photons could reach space that quickly, our night-time temperatures would plunge precipitously every night. As I understand it, the photons are absorbed and re-radiated many times in the air, and there is no preferential direction for each re-radiation.

"Acidification isn't a serious risk because the oceans are alkaline and contain terratonnes of carbonates."

Nearly 3 terratonnes of free carbonate in the waters, I gather. And this does act as a buffering agent as it converts to bicarbonate--eventually. But only a fraction of that supply is available in the upper waters where shell and coral building takes place, and the data looks like we've already increased the supply of free protons in these waters by around 25 to 30% on average--which slows down shell building and coral formation, posing a particular risk to the youngest shell builders. There's some uncertainty about how this will play out, but marine biologists are clearly worried.

"...we can go stand on a massive graveyard of these criitters-"

But how long did that take to accumulate? Our enemy here is time.

"Given all the evidence for higher temperatures and CO2 levels in the past, why haven't we died already?"

Modern humans began to exist around 300,000 years ago. At no point during the past 2.5 million years (until the industrial revolution) did CO2 exceed 300 ppm. We're now above 420 and climbing rapidly.

"We know from all the chalk they've left behind, they've thrived when temperatures & CO2 levels were higher."

And many species that thrived in high-CO2 periods might not even be able to survive at our lower levels. But changes in the past have generally occurred on timescales of millions of years. That gives species time to adapt, or for ecosystem to adapt with a slower rate of extinctions.

"Nuclear alchemy also produces the medical & industrial isotopes we need, and 'renewables' can't produce."

This probably won't be a large factor for Triso fuel. It is very tough to take apart. (Though we can use the neutrons in the reactor to do some of that.) Today's spent fuel is relatively easy to take apart, and we should be doing that--both for the usable isotopes and to reduce the waste profile by over 99%. Molten salt fast reactors will be where the isotope industry really takes off.

"pretty [much] everything benefits from cheap, reliable energy. Which 'Net Zero' is doing the opposite by making energy more expensive and less reliable."

I think future people will look back at today's environmentalists and climate activists opposing nuclear in much the same way we view doctors of old who opposed hand-washing and sanitary operating conditions. But they are slowly coming around. The Nature Conservancy is now pro-nuclear. Zion Lights left her high-profile position with Extinction Rebellion and is now a nuclear advocate. And we only need the reasonable ones. Leaving the zealots, fraudsters, and crazies to represent the opposition side is good for the pro-nuclear side.

Re: Reliable sources?

"...if they are cost effective, then they could be built without any public subsidy."

New kinds of nuclear might not be cost effective right at first, especially with the front-loading of billions in regulatory costs. But we supported wind and solar before they became economically viable, and I think new kinds of nuclear have even better potential.

"Or Google could decide to build molten salt batteries to complement the SMRs they're building and be self-sufficent."

Google is contracting the power from Kairos, But Google would be a steady customer, and Kairos would be a steady supplier, so neither would need storage. The storage approach would be for helping the grid with fluctuations in demand and production. As you note, this is a difficult problem for electron storage. But it's relatively easy and safe when the energy is stored as heat.

"Plants like Gemasolar don't appear to be that efficient, even when they're in sunny Spain..."

I was citing them as an example of economically-viable heat storage. Storage should work same way if the heat comes from nuclear reactors--though it can be cycled in a way that is more useful to the grid.

"Price arbitrage and grid stabilisation are also anti-competitive because their function is to increase the price of energy, not reduce it."

Price fluctuations are a normal way for markets to try to match supply and demand.

[CO2 capture] "That's kind of swapping a Bhopal style battery fire for a Lake Nyos incident."

We are already piping CO2 thousands of miles. Yes, it needs to be managed well.

"Plus there isn't much "waste" energy."

Currently, nuclear power throws away all the heat that doesn't go toward producing electricity (around 66%). With hotter reactors, the secondary heat (what we currently call "waste" heat) is also hotter and becomes more useful for other purposes.

"There is no demand for 300kt of CO2 either, unless that gets used for enhanced oil & gas recovery."

CO2 sequestration could also be used to produce verifiable carbon credits. Oxy Petroleum wanted to do this on a gigatonne scale on the King Ranch in Texas--before Trump returned and messed it up, or at least delayed it. Or, combine CO2 with hydrogen, and you can produce syncrude, from which a range of hydrocarbon fuels and products can be refined. The U.S. Navy researched this to produce jet fuel from seawater and showed that it worked. But using expensive Navy nuclear heat to drive the process resulted in a cost of around $7 per gallon, which was not competitive. But much cheaper nuclear heat could make the fuel much cheaper. Using hydrocarbons as an energy storage and transfer medium, any of our internal combustion engines could be converted to running on nuclear power--using the fuel infrastructure we already have in place.

"So common proposals are to use calcium & sodium hydroxide."

Or potassium hydroxide, in the case of the half-megaton Stratos plant currently being built in Texas.

"Which is again Kafka-esque because they're made from quicklime, which is made heating limestone to >800C"

The calcium can be recycled endlessly, and there are ways to reduce the CO2 release temperatures down to as low as 300C.

"which requires a lot of energy"

Which is a less big deal if it is a co-process paired with electricity production.

"don't think about how this process wastes energy and will have no measurable effect on temperatures."

We are at around a trillion tonnes excess atmo CO2 from pre-industrial levels so far. It's definitely having a measurable effect, but between a third and a half of the heating potential is being masked by the shading effect from our combustion particulates. If all we do is go to clean energy and we don't do anything about the CO2 already in the air, our pace of heating will increase greatly once we lose the smog shading, and that heating will persist for centuries. We only have two options to counteract the long-term heating. We can reduce the incoming sunlight or we can radiate our heat out into space faster (such as by reducing our greenhouse effect).

"Or how nature beat us to this problem, which is why there are many, many gigatonnes of carbonates already in the environment"

Trillions of tonnes in our seas, quintillions of tons on land. Yes. But the natural conversion processes are slow. We got into this situation on an industrial scale, and now we need to address it on an industrial scale.

"reducing atmospheric CO2 means we lose the fertilisation effects and boosts to crop yields,"

There are some benefits, in some places, to having more CO2. But you also have to look at the harms and risks. Like how we're jeopardizing the thermo-haline circulation of our oceans. And with less turnover, acidification in surface waters becomes a more serious risk. (There are lots of ways to address that directly, but they need energy too.) Like how we might release a huge amount of methane as the permafrost layer descends. Like the risks of more heat-stress, more wildfires, more droughts, more floods, and more woodland blights.

"so food costs increase"

A large chunk of agriculture is for energy crops. With synfuels, we wouldn't need those. Nuclear heat can also produce fertilizers, and in some cases, nitrogen is a larger constraint than CO2. With a lot of clean energy, we could also support energy-intensive food production systems, like aquaponics or cell-cultivated foods.

"increasing inflation even faster than wasting energy on 'ideas' like this already do."

Money is created as debt. Money to cover the interest on the debt is not created. Inflation is baked into our monetary system. Even producing a large amount of cheap energy won't be able to fix that.

Re: Flipping the Script

"Isn't that mostly solved with Hastaloy?"

Depends on what you mean by "mostly". Hastelloy-N is one of the best-performing alloys we've found so far, but some tests in some conditions found intergranular crack progression rates from tellurium attack of around 1 mm per year at high temperatures. That's seriously bad, and though it is the worst we have found, we don't know that it is the worst that is possible. On the other hand, under different conditions, the crack progression rate was trivial. Managing the redox potential of the salt helped. Adding small amounts of technetium to the metal seemed to help. Niobium in the salt sometimes helped. Argon sometimes helped and sometimes made things worse. And as fission products accumulate in the salt, the salt chemistry changes. And with neutron activation, additives can change into other isotopes. As a practical matter, managing the corrosion will likely not be a big deal. From a regulatory standpoint, the large number of changing variables with complex interactions creates a qualification nightmare.

"It makes me wonder that since the reactor isn't a massive high-pressure vessel if there would be enough lifetime to build multiple reactors on one site and refurbish one when required with the others taking the load"

That's basically the Kairos plan (with Thorcon also doing something similar). They plan to standardize on a 75/200 MW(e/th) reactor, and have at least two vessels feeding one steam turbine and generator. And then each 20 years or so, they'll replace each vessel, and they are trying to design to make the swap operation as quick and easy as possible. Since the salt in the secondary loop is basically the same as solar salt, they could also bolt on thermal storage to augment the running reactor(s) while one is being replaced. The short service life makes it a lot easier to get regulatory qualification, and it also allows each plant to have a pathway for ongoing reactor design improvements. It also means each plant would have an indefinite service life. The cost of their reactor vessel is likely to be less than the cost of a couple of burnable kg. of their fuel, so it would be a cheap consumable--with each retired vessel ready for recycling in about a year. Triso in Flibe molten salt would also be a particularly safe fuel for marine applications, so I think there could be good potential for offshore power plants. For those, the whole plant could be swapped out just by bringing in a new plant and switching the grid connections. With good synchronization, it might even be possible to do that without interrupting power.

Re: Flipping the Script

"At this point you would be barking mad to buy US reactors with a US fuel subscription."

By the time Kairos gets into the international market, I expect they will also have international production capability. Also, Kairos is designing their reactors to work with a range of fuel types (with varied kinds of enriched uranium, MOX, and thorium being considered, either individually or in blends), and they are likely to use mixed fuel types while developing new fuels, so the fuel specifications are not exacting. There will likely be a number of international suppliers who could make workable fuel balls in roughly the right diameter. Also, it would not be as barking mad as buying US weapons systems, or actually offering purchasing pledges to appease Trump, yet here we are.

"One of the solid plusses of solar vs nuclear or wind is you are safer against supplier adversaries."

I imagine inherently safe forms of nuclear would also be at very low risk from malicious action.

"it is easy for your supplier-adversary to remotely destroy all the invertors, wind turbine blades, gearboxes and generators,..."

I am not familiar with how this would work. I knew wind turbines could be remotely turned out of the wind and braked, and that remote operators can use electric motors to spin up the windmills in some designs, but I thought over-rev braking was automatic and autonomous. At the risk of drifting off-topic, can the safety systems be remotely disabled? Would remote wind power sabotage require extreme conditions to work, or could it do damage under normal or even idle conditions?

Re: Thorium reactors are the future - until fusion

"...Kairos using triso solid fuel in a once through cycle, which is only increasing the problem, not reducing it."

Increasing the volume of a problem is not the same as increasing the problem. Yes, the Triso spent fuel will be somewhat bulkier (despite higher burnup) because of the many layers of cladding material. But bulk is not the problem with legacy spent fuel. The problem is the isotope containment is not very good. Some of the pellets are damaged and leaking even before they come out of the reactor, and the cladding could fail in a fire, or with exposure to steam, or even if it simply loses cooling in the first roughly three months out of the reactor. Triso is far more robust, chemically inert, and heat-resistant, so nearly all the hazard comes from getting close to it without shielding. That is a very manageable hazard.

Re: Thorium reactors are the future - until fusion

"There's just the problem of high energy gammas one gets from U233 that can be seen miles off."

I don't think so. I'm pretty sure it does a clean alpha decay with no gamma emission. An very small percent of the time, it will spontaneously fission, and some fission products release gamma rays, but the amount would be very tiny. A human body would be a brighter source of gamma rays.

Re: Flipping the Script

"It does make me wonder if using triso is a bit of a subscription fuel play"

Kairos is probably not thinking in those terms, at least at first. Their business plan is to finance their builds, to build all their own plants, make their own fuel, and then to own and operate the plants, and make their revenue from selling energy and possibly nuclear products. The subscription model might be more important for export reactors, especially if it involves return of the used fuel. That would be good for establishing long-term international ties, and good for reducing customer anxiety about what to do with the used fuel.

"when you compare it to molten salt fuel, that looks a lot cheaper to make, a lot easier to make (i.e. you don't have to buy it from the US or X), with easy-ish reuse and higher burnup possible."

The higher burnup would only apply to breeder reactors--either thorium or molten salt fast reactors. The downsides of liquid fuel are a bigger corrosion problem, the extra cost of having chemical-processing capability at every reactor, and having to manage and store multiple streams of radionuclides coming out of the reactor. So, cheaper fuel, but more expensive plant, equipment, and operating costs. With Triso, there would be no processing on site and all the radionuclides would remain locked in the fuel.

"Triso does seem to be a bit of a US favorite at the moment."

Some improvements in manufacturing have made it remarkably robust. In the version of Triso that Kairos is planning to use, they characterized the failure rate by taking samples up to 19% burnup, and then subjected them to 3000 deg. F for ten days, and found a rate of less than ten failures per million grains of fuel--with nearly all of those failures being caused by some residual production defects--so even that small rate could be improved even further. That is a much more severe test than the fuel is ever likely to experience, and it doesn't even include the added containment protections of the grains being embedded in tough multi-layer balls, with the balls floating in molten salt (which aggressively binds to cesium, strontium, and iodine), inside a sealed reactor vessel. The molten salt carrier also means shock loading, stack loading, surface abrasion, bridging, hot-spots, and control rod jamming are effectively eliminated (all being problems that previous gas-cooled Biso and Triso reactors had).

Being a super tough fuel will also mean it will not be practical to take it apart to do post-processing. That's bad from the standpoint of being able to use the spent fuel in future fast reactors, but good from the standpoint of strong containment and very low proliferation risk.

Re: Flipping the Script

[Their full-sized reactor vessel is made out of inch-thick standard 316H stainless]

My goof. I misread 1.6 in my notes as 1.0. So the vessel wall thickness is actually 1.6" or 4 cm.

"China's also doing (or claiming to be doing) some interesting things with exotic forms of steel."

Also some interesting ceramic coatings to combat tellurium corrosion. The Kairos design won't need that (the tellurium remains locked in the fuel) but the liquid-fuel molten salt designs might benefit. I think China has also pulled into the lead for having the fastest and cheapest method for pulling uranium out of seawater, but such leads typically don't last very long. It's usually only a year or two before the next significant advancement.

Re: Reliable sources?

"as long as those biases are made clear"

The IEEFA doesn't have an explicit mission statement to combat nuclear energy that I have found--as many anti-nuke organizations do--but they cite notorious anti-nuke individuals in their papers and use the same talking points and rhetoric, they attend and conduct anti-nuke seminars and events, and their work is showcased on anti-nuke sites, so I would say their bias is pretty clear. And while they don't appear to engage in outright lies and fraud, their work is clearly cherry-picked and one-sided. For their paper about how SMRs are too expensive, slow, and risky, they characterized an entire class of reactor (for which there are around 80 different designs in development) based on just four designs (zero of which were molten salt reactors).

"energy storage is hard, especially when high density energy storage is basically a bomb and the magic pixies really want to be free."

That would be the case for electron storage. It is much easier, safer, and cheaper to store energy as heat. The IEEFA paper mentioned the proposal to use molten salt thermal storage at high-temperature reactors for flexible output, and their rebuttal for that was based on capacity factor, saying "The less they run, the more their per megawatt-hour costs rise and the harder it will be for them to compete in the market. Having invested billions, it is unlikely developers will willingly cycle their plants to accommodate renewables." First, they didn't understand that, with storage, the capacity factor of the reactor would be divorced from the capacity factor for the plant. They also didn't understand that time-shifting the reactor output to when electricity price is high increases the revenue for the amount of fuel burned. They also assumed a model of an expensive nuclear plant and cheap fuel--which wouldn't apply to Kairos. And they also didn't get that plants with thermal storage would actually benefit from and rely on intermittents carrying the load at times to give the reactors a chance to recharge the thermal storage tanks.

"With a total capacity of 600MWh, Thurrock Storage is capable of powering up to 680,000 homes,"

The Gemasolar plant has 300MWh worth of electricity-equivalent storage (with virtually no explosion potential) for a 20 MW(e) plant. If that much storage is cost-effective for such a small solar plant, it should be at least as feasible to have 3600MWh(e) storage for an 240MW(e) capacity nuclear plant (paired with, say, an 80MW(e) reactor), especially since all the storage could be dedicated to price arbitrage and accommodating grid fluctuations instead of most of it having to cover a low-capacity-factor heat source.

A 240MW plant would also be small enough to make air-cooling feasible. (A 400MW air-cooled geothermal plant is planned for Utah). With air cooling, one of the things you can do with the secondary heat and the large amounts of air moved by the cooling fans is to use that to power direct-from-air CO2 extraction (currently possible at around 2MWH(th) per tonne of CO2). With that, around 80MW-years of electricity production could also power around 300k tonnes of CO2 capture, mostly on "waste" energy. Build 100k plants like that and we might be able to pull around 30 gigatonnes of CO2 out of the air per year.

Re: Thorium reactors are the future - until fusion

Thorium has a tight neutron economy, and protactinium 233 gobbles up neutrons. So you either need a supplemental source of neutrons, or you need to remove the protactinium 233 from the core while it undergoes transition into U-233. The reports about the China thorium reactor indicate it is breeding protactinium, and they demonstrated full-power refueling earlier this year, which sounds like they were inserting the U-233 from the protactinium. If that's correct, that means they are doing protactinium separation, and that means anyone who has one of these reactors will be able to use it to produce weapons-grade U-233--the best fuel for a suitcase nuke. And from the international patents they have filed, it looks like they mean to export this reactor to the world market. We can't stop them, but we might be able to beat them to market with better, cheaper, safer reactors, and the Kairos design looks like a good contender for that. Also, thorium reactors would only be able to consume around 1% of what's in our legacy spent fuel. Molten salt fast reactors would be able to consume more like 96%, plus any surplus or decommissioned uranium or plutonium bomb fuel, plus the neptunium wastes we still have left over from our Cold War bomb production days, plus enriched, or natural, or depleted uranium. And western nations are already developing molten salt fast reactors, while it looks like China is not.

Re: Shipping container sized

The Kairos FHR vessel is currently spec'd to have a diameter of 2.4 meters. It might require a special transport container, but it should be possible to get it into the standard form factor. Kairos is also demonstrating how the power plant construction can be accelerated with the use of 3-D printed forms for the concrete. The 316H material in the vessel will undergo neutron activation, and it will take about a year for the radiation levels to drop to a point where the vessel can be recycled. They are planning to have a duty cycle of around 20 years for each reactor vessel. Replacing them on a short cycle like that greatly simplifies showing regulators they can resist corrosion and radiation damage for their rated service life. It also means any updates or improvements to the reactor design can propagate through their existing fleet of power plants, and it means the power plant can last as long as its structure can, and It greatly simplifies plant decommissioning,

Flipping the Script

With traditional nuclear, the upfront cost was huge while the fuel was cheap. It looks like Kairos has a good chance of reversing that. They've already built three full-scale reactor vessels, and they've shaved months off the build time with each iteration. They built their third unit in the UK to test Sheffield's electron beam welding (shortened some weld times from roughly a week down to a few minutes--with better weld quality) and even with shipping from the UK, it took around 4 months from design finalization (they modify the design after each build) to installation in Tennessee. Their full-sized reactor vessel is made out of inch-thick standard 316H stainless and can be assembled with common metalforming equipment, so setting up each production line should be cheap. The vessel canister weighs less than two 40-foot shipping containers (lighter than an average wind turbine blade now), and if they met their objective to hold assembly cost for Unit 3 to 20% of the finished cost (the rest being materials costs) that would be around a 50X reduction in cost per MW capacity relative to a traditional gigascale high-pressure vessel. The fuel, on the other hand, will initially be the most expensive ever used for civilian power (Navy fuel will still be a lot more expensive). Early estimates are around $225,000 per burnable kg for the enriched fuel and Triso / pebble fabrication. But each kg burned will produce around 22 million kWH of heat or around 8.4 million kWh of electricity. So the fuel share of the energy production cost would be around a penny per kWH for heat, or 2.7 cents per kWh for electricity. And High Assay Triso fuel production is exactly the sort of automated process which should be able to realize major cost reduction when scaled up for mass production--and that future cost reduction will benefit every one of their reactors.

Google tries to greenwash massive AI energy consumption with another vague nuclear deal

Not "clean" unless actinide-free

By the time of the first humans, the world oceans contained billions of tonnes of actinides, and continental crust contained contained tens of trillions of tonnes of actinides. And that's still the case. So if you say actinides are "dirty", then Nature is clearly orders of magnitude dirtier than humans on this count.

Beryllium cost

"IIRC Be is 200x the cost of Al alloy."

So that would be around $480,000 per tonne. But 2023 global Be production revenues averaged $360,000 per tonne, That difference is probably because Be producers sell both metallic Be, and cheaper BeF2--which is a precursor stage before the high-energy electro-refining which produces the metal. For fluoride salt production, you'd buy the cheaper BeF2--since that's what you are going for anyway. For their full-scale salt test loop, Kairos loaded 14 tonnes Flibe. At roughly 30% Be, that was probably less than $1.5 million for the Be share. Be has a slow consumption rate in molten salt reactors, but let's say you only get ten full-power reactor-years worth of use out of the Be. That would be $1.5 million spread over 6,574,500 MWh(e)--for an average cost of 22 cents per MWh(e). Trivial. Just the regulatory costs are going to be orders of magnitude higher than the BeF2 costs.

Re: 1 trillion tonnes of CO2

A 2022 IPCC report estimated the potential for improved biological CO2 capture means (reforestation, wetland and peat bog restoration, changes in agriculture, biochar, etc.) and it projected a potential to sequester 860 million tonnes of CO2 per year worldwide by 2030, and as much as 4.19 Gt per year by 2100. And that would be great, but right now, we are making almost no progress towards implementation. And even if we accomplish it, it's not enough. Even if we were at zero CO2 emissions by 2100 for a net negative of 4.19 Gt per year, that rate of capture would take over 200 years to draw down a trillion tonnes (and our current excess is a trillion tonnes, so the excess could be considerably higher by 2100). We need something more like 20 - 30 net-negative Gt CO2 per year, and we need it a lot sooner than 2100.

We don't know at this point how much industrial CO2 drawdown can help, but there are some intriguing possibilities. We have figured out ways to pull CO2 out of the air using common and re-usable materials at an energy expenditure of around 1.5 to 2 MWh per tonne CO2--with most of that needed energy being in the form of heat, and most of the non-heat energy going to fans. Coincidentally, some of the advanced reactor developers are planning for smaller, hotter power plants which can be air-cooled--meaning they will be running fans to move a lot of air anyway, and will be throwing away a lot of reject heat--in a range that CO2 capture can use. Piggyback CO2 capture onto a 200MW(e) nextgen nuke, and on top of generating the electricity, it could also sequester around a million tonnes of CO2 per year with the reject heat. If we can get the cost of nukes down into an attractive range, we'll easily have enough energy demand to support building tens of thousands of nukes at that scale--potentially tens of gigatonnes of CO2 removal per year. This won't replace the need for the biological methods. We'll still need every scrap of those we can achieve, and every other CO2 capture method we can develop as well. But nuclear is in a unique position to help because it is, and will always be, the largest source of clean energy which produces its primary energy in the form of heat, rather than electricity.

Re: " it would be very tough to dig out the tiny particles of fuel-"

"Crush the pellets, burn off the graphite..(etc)... and you'll have a fresh supply of uranium to go."

But it would still be a long ways from weapons-grade, so it would still need a lot of additional enrichment to make a bomb. But if you already have the enrichment equipment to do that, it's easier to just start from natural uranium than to deal with the Triso mess. Even easier is to get ultra-high purity bomb fuel from a thorium MSR.

"But IMHO the real killer is the enrichment ... higher enrichment --> higher cost."

It will cost more; I don't think that will be fatal. Early cost indicators look like around 35 - 40,000 $ per kg. U in Haleu Triso. And each kg. U could produce around 4250 MWh of heat, so that works out to around $9.40 per MWh of heat, or around $28 per MWh of electricity (or a bit less with improved thermal efficiency). That's not horrible compared to the fuel cost of combined-cycle natural gas or coal, at around $35 per MWh(e). Plus, with experience, Triso fabrication cost should come down. Plus there's the MOX option, replacing some of that enrichment with reactor-grade plutonium. Thorium blending is another possibility. And every Kairos reactor will be able to benefit from future fuel improvements.

On the flipside, there should be very large capital cost savings relative to old nuclear. And cheaper turbines relative to combined-cycle gas. The tough one to beat will be coal, but only because coal offloads its worst costs onto the environment and the public.

"Then of course there's the Beryllium ... very toxic."

Primarily in dust form--which won't be a thing for beryllium in molten salt. We use beryllium in many aerospace applications, so we have some experience in how to handle it.

"It's a pity because I liked both the MSR and the pebble bed reactor."

Both are good--in different ways. The hybrid creates a new category with its own features. Advantage over liquid-fuel MSR is it's not nearly as corrosive without the tellurium, so the reactor vessel can be stamped out of ordinary 316 stainless (and recycled after about a year out of service). And Triso fuel won't need any on-site chemical processing like liquid fuel will. Disadvantage is that it adds ball-handling equipment, and reactor control will have to be done by control rods. Advantage over gas-cooled pebble bed is easier ball handling (pulling floating balls off the top rather than from the bottom of a heavy stack), hot-spots within the stacks are eliminated, stack and shock loading of the balls is eliminated (much less risk of ball damage--which has been a problem), much easier insertion of control rods, and the salt aggressively grabs and retains any cesium, strontium or iodine which might escape from any damaged balls, adding another robust layer of containment. This would be a particular advantage for maritime reactors--where even a core breach directly into the ocean would not result in a significant release of contaminants. Gas-cooled pebble bed has the advantage for very high-temperature applications.

"High enrichment (actually any enrichment, given we know how to build natural U reactors, and have since the 1940's) is bad."

In moderated reactors, enrichment greatly reduces the amount of uranium that goes through the reactors, which greatly shrinks the amount of high-level waste (used fuel) produced. Molten salt fast reactors could solve the waste problem by utilizing close to 100% of their uranium fuel, but those are a new concept and we likely have another 10-15 years of development work yet to do on those. But that is the direction we'll need to go eventually.

"Guess time will tell if this gets done or what."

Advanced reactors will definitely get developed somewhere. China is hoping we'll drop the ball here, like we've done in so many other places where we could have led.

"Remind me what the CO2 contributions of the bicycle are compared to the SR-71 Blackbird?"

The analogy was physical speed to production speed. But you knew that. I couldn't think of an analogy which covered both production speed and CO2 profile, but hotter reactors using some of their heat to power CO2 extraction from the air could have very large negative-CO2 profiles--way better than wind, solar, hydro, and bicycles. And we are going to need a lot of that if we are going to have reasonable hope of removing about a trillion tonnes of CO2 from the air fast enough to avoid catastrophic warming or ocean acidification collapse.

"...the AI bollocks and it's attendant energy race do not and will not contribute to the sum of human happiness."

The enormous sums of money connected to AI development could launch multiple kinds of next-gen reactors, and once launched, they could take off on their own. The clean energy potential is huge, the fuel is abundant, and it is the only energy source we know of capable of driving industrial-scale CO2 drawdown. It could help to shut down some toxic and deadly forms of pollution, offset highly destructive kinds of mining, could lift billions out of energy poverty, and could help shrink the human footprint on the natural world. And I think all of those factors, and more, have the potential to contribute to human health and happiness--even if the AI itself never does.

Re: 200MW is a good size for an SMR

"On the down side MSR have historically run high enrichment IE near-bomb-grade levels."

I think there is no historical precedent for the Kairos strategy of running Triso fuel in molten salt coolant. The Kairos fuel will be enriched to slightly under 20% U-235. Weapons-grade U-235 is 90%. (Some U.S. Navy reactors have used fuel enriched to 97% U-235, though now 93% is more common.) And once formed into Triso fuel balls, it would be very tough to dig out the tiny particles of fuel--a lot more work than just enriching natural uranium up to the same level. So far as I know, all of the other enriched-U molten salt developers are also planning on using below-20% enrichment.

The bomb-hazard molten salt reactors are the ones that will run on U-233 bred from thorium--the kind that China is developing. Base-purity without improvement is around 99.87% U-233. With 54 days of decay segregation, that can be reduced to one part contaminant per 1589 trillion parts U-233. (i.e. 99.99999999999994% pure U-233) Gun-detonator grade is anything below 1 part contaminant per million parts U-233. And with an unreflected critical mass of only 15 kg. (as opposed to 52 kg. for U-235), that kind of purity would make it possible--even easy-- to build a briefcase-sized, hand-carried U-233 nuke that uses a very simple gun detonator. And if we don't like the idea of China selling a bunch of those reactors to their friends, we'd better develop something which can outcompete it quickly. They've already got their thorium test reactor up and running.

"as The Register pointed out recently, Google's nuclear plans - along with ... others - may be too little too late to address the growing concerns that there isn't enough power to fuel the growing demand from datacenters and AI."

Yes, there isn't enough power right now to meet the future rising demand, so we'll be adding more power, and some of it won't be clean. Nuclear isn't going to be able to help much for the next five years. But once we have modular manufacturing up and running, it could become one of the fastest growing clean energy sectors. The near-term delay doesn't mean it will be "too late" for anything--other than arbitrary near-term deadlines that don't mean anything and which we aren't going to meet anyway, no matter what we do.

"Another abstract agreement ..."

Aren't all agreements abstract?

"... through a company that has yet to build anything is unlikely to help now, when we really need it to,"

We'll still be needing it 5, 10, 15, and 20+ years from now. We can only go from where we are. As for the "yet to build anything" knock, that definitely does not apply to Kairos Power. Starting with nothing in 2016, they built a rapid-prototyping lab and a large assembly prototyping lab--and built and knocked down many prototypes, they built a salt production facility, they built and ran the world's largest molten salt test loop, they set up a regulatory affairs center and are currently setting up an operator training facility, they have started setting up their Triso fuel production line, they've started construction on their reactor factory, they've started construction on their Hermes 1 demo facility, and earlier this year, they completed their first in-house build of their commercial-scale reactor vessel--in a matter of months--without benefit of their planned mass-production capabilities. Considering they've also been having to push multiple simultaneous permit and license applications through a notoriously slow NRC while doing all this, I would rate their accomplishments and speed so far as quite impressive.

In a cold-start race between a bicycle and an SR-71 Blackbird, the cyclist will easily jump out into the lead right off the line, and in a few seconds the cyclist will be sprinting away at near top speed while the Blackbird is still sitting motionless. But just because the Bird hasn't moved doesn't mean nothing is happening, and it doesn't mean the Bird is "too slow". Once the engines are spooled up and making thrust, the race dynamics will change rapidly.