It truly baffles me how humanity has the technology for a nuclear reactor that can actually CREATE MORE FUEL THAN IT USES and no one wants to use it.
> That application was submitted in March 2024 and is on track for approval in December 2026
Next time you complain that waiting for a code review approval till next week is excruciatingly long, think about these turnaround times.
Also this is why we can't quickly build many reactors to ramp up electric generation for millions of new electric cars, etc.
The grid connection backlog is about 6 years, so this is considerably quicker than for a renewable energy project that requires a new grid interconnect.
That is actually VERY fast for anything related to nuclear reactors.
You probably don't want a nuclear reactor (of all things) to be built in sprints of two weeks, according to the tenets of Agile.
While true, this has nearly nothing to do with building (still to happen) or planning (has to be finished before the approval process). It is a 2 year paperwork delay and making sure the NIMBYs have all the time they might need to get organised.
Okay, we had a partial meltdown in prod, and released some radioactive iodine-131, so that goes on the sad face side of of the retro board.
But on the good side, we _didn't_ have a hydrogen explosion due to some late-night troubleshooting, great work Carl!
But we learned a lot, our alerts were confusing, and our metrics didn't surface coolant level or the relief valve that was stuck open.
So next sprint, let's focus on monitoring and cross-team knowledge transfer! 3 points, right?
> why we can't quickly build many reactors
No. The reason is that they have not been price competitive with renewables.
And so there isn't the volume of approvals that gives regulators experience which in turn reduces approval times.
Commercial solar takes months to approve by comparison.
Last I checked solar without batteries is roughly the same price per Kw as nuclear. There’s a huge difference in capability though because nuclear is 24/7 peak availability which solar can’t do and if you start building batteries the price increases substantially.
I agree on regulatory experience but that comes more from panic over nuclear proliferation rather than any economic reason. Whether or not you view that as a legitimate concern is open to debate.
For anyone arguing about this, please first look at https://www.cis.org.au/commentary/opinion/nuclear-vs-renewab...
The primary cost of running solar plants is no longer the panels themselves (ie if they drop to 0 the $/KW wouldn’t change a whole lot).
>Last I checked solar without batteries is roughly the same price per Kw as nuclear
Checked where? Lazard says it is one fifth of the price.
>There’s a huge difference in capability though because nuclear is 24/7 peak availability which solar can’t do
Not 24/7. They have to be turned off for maintenance and when that happens e.g. France burns an awful lot of gas.
Pair solar with wind and storage and it's still cheaper than raw, nuclear power and would be even if matching storage were 4x the cost.
A key metric that controls the cost is just how much storage do we want? 4 hours? 1 day? 1 week?
> Last I checked solar without batteries is roughly the same price per Kw as nuclear.
You didn't check, you decided to cook the presentation of the facts.
Indeed, solar is not available 24/7. But it's not individual installations which need 24/7 availability, it's the grid as a whole; plus, energy use during the day and night differs, so even the grid as a whole doesn't need the same generation capacity 24/7. And - the grid has many different energy sources (i.e. not just solar and nuclear), some renewable and some non-renewable, which aren't daylight-only.
Which is to say there is plenty of room for solar installations irrespective of energy storage solutions. And indeed, those installations are taking place, and they are rather cheap.
> Last I checked solar without batteries is roughly the same price per Kw as nuclear
When your basic assumption is that an entire industry is doing something dumb, it’s probably wrong. If nuclear was actually that cheap electric companies would constantly be proposing new projects, but it’s not.
> 24/7 peak availability
The industry abandoned nuclear because electricity demand stopped increasing decades ago. It simply isn’t cost competitive when facing both significant curtailment and the need for backup generation for the multiple weeks to months downtime nuclear power plants have semi annually.
That’s the core issue nuclear needs both 24/7 demand, and the grid to also be perfectly fine when it goes away for months. That only possible when it makes up ~30% of supply which is roughly where it’s been for decades.
Now having not built nuclear for decades once off projects are constantly wildly over budget and behind schedule. Solar + batteries is currently beating even optimistic estimates for nuclear just about anywhere, let alone current boondoggle pricing.
Indeed so. Renewables had about 15 years of breakneck-pace progress and massive production with huge economies of scale, which I cannot say about nuclear reactors.
But even if nukes were somehow very cheap to build, the review process due to high safety requirements and a lack of a standardized reusable reactor design would make the process slow. To become cost-competitive, nuclear reactors need to be mass-produced, using a proven design that needs little review. The French sort of achieved that, with two mass-produced types of reactors.
Renewables as baseload are still problematic though. Solar cells and even wind turbines are not expensive, but the batteries are very expensive, and are a huge fire hazard. It would be interesting to estimate how much would a kWh cost from a nuclear power station, and from an equal-power LiFePO4 battery installation with the capacity of, say, 3 days worth of the rated max power. Batteries can be replaced gradually, but would need to be replaced much sooner.
[Update:]
If we take a modest nuclear generation unit producing 300 MW of electric power, I'd like to compare it with a battery that can store 300 MW * 3 days of energy from renewable sources. It's 21.6 GWh. With LiFePO4 typical bulk price of $100 per kWh, the upfront cost in batteries alone would be $2.16 billion. It's still lower than nuclear reactor equipment, but very much in the same ballpark.
> but the batteries are very expensive, and are a huge fire hazard
Have you seen how the fire risk petroleum presents? It's crazy.
> but very much in the same ballpark
You need to factor in waste disposal and decommissioning costs for nuclear.
And if you are concerned with the fire risks of batteries you may want to think about the impact of serious events with a nuclear reactor. In almost all cases they end up being quite expensive.
Not like there's a history of steam explosions or hydrogen formation in historical nuclear reactor incidents.
Once they’ve approved this reactor, build more of the same.
That's a decision for the markets.
And right now renewables continue to get better and cheaper so it will be hard for nuclear to get much traction.
Did we cannibalize some of our nuclear warheads, in order to get the enriched uranium?
https://wyofile.com/fate-of-natrium-nuclear-plant-may-depend...
Apparently yes, accoriding to [CNN].
"In the current stockpile, the average duration since a warhead was manufactured or refurbished is roughly 28 years." [DoE]. I suppose some of the aging warheads will be reprocessed as fuel.
[CNN]: https://www.cnn.com/2024/09/09/climate/nuclear-warheads-hale...
[DoE]: https://www.energy.gov/nnsa/us-nuclear-weapons-stockpile
(Previous version of this comment was incorrect.)
Liquid sodium certainly is a choice. Very few non-experimental liquid sodium reactors out there.
It has a huge advantage of being able to operate at 850C at much lower pressures so you don't need 30cm thick steel
This is a fast reactor. That is, a reactor in which the neutrons, instead of being moderated down to thermal energies, remain at high energy.
The fission cross section for such energetic neutrons is much lower than for thermal neutrons. Therefore, there has to be a much greater density of fissionable material in the reactor core.
The lack of a moderator also means rearrangement of the core in an accident is potentially much more dangerous. If the fuel itself rearranges to become more compact, say by melting and flowing, the reactivity could increase. This is not possible in (say) a light water reactor, where such a rearrangement would reduce reactivity.
The nightmare scenario for any fast reactor, warned about by Edward Teller in 1967, is a rearrangement that causes the core to become supercritical on prompt neutrons alone (that is, on only the neutrons released promptly at the moment of fission, not on those + the delayed neutrons emitted by some fission products as they decay). A fast prompt supercritical configuration could potentially explode with great violence, greater than Chernobyl. An atomic bomb is a prompt fast supercritical system.
I will want to see how the NRC does or does not license their design, a process that has just started. I will not be surprised if their approach ends up being unlicensable in the US because safety cannot be assured by analysis under accident conditions.
It's not quite like that.
> An atomic bomb is a prompt fast supercritical system.
Yes, it is, but more precisely it is a fast hypercritical system. The difference is this: in a supercritical system the ratio of neutrons in a new generation vs the old generation (generally denoted by k) is higher than one. For example 1.001 qualifies as supercritical. In a hypercritical configuration, k is higher than 2. In nature things generally evolve in a continuous way. To get to 2 you need to first get to 1 and 1.001, for example. For a bomb, it is very important to get to 2 extremely quickly, so that the assembly does not start the chain reaction while k is 1.001, or 1.1. To do that, you use either a gun or high explosives, to quickly reassemble a subcritical configuration into a hypercritical one, before a stray neutron has a chance to start a barely supercritical reaction (also known as a "fizzle").
With a reactor, there's no way to get an atomic bomb effect, because you go through the point of k=1.001. When you get there, there are plenty of neutrons around that this results in a "fizzle". Heat is produced and the core dilates and the ratio becomes low again. This results in "prompt excursions", each one lasting less than one second, each one some sort of a "bomb fizzle". These excursions are annoying, but they are not Hiroshima.
> I will not be surprised if their approach ends up being unlicensable in the US because safety cannot be assured by analysis under accident conditions.
What you are saying is a Catch-22. NRC can't approve a new design because it doesn't know how it performs under accident conditions, but then you can't know how something performs under accident conditions if you don't build it, and you don't build it if NRC does not approve it.
The fact is, Russia has been operating the BN-800 sodium-cooled fast reactor for 10 years [1], and the smaller BN-600 for 45 years. So sodium-cooled fast reactors can work, and Russia likes them enough that it plans to build a bigger version, BN-1200. They don't explode. You could say "not yet", and sure thing, this means that the NRC needs to work hard to cover all the bases. But this is not impossible.
reddit had a nice list of the pros and cons: https://www.reddit.com/r/NuclearPower/comments/17k0wcc/natri...
I understand the risks around sodium, but the "passive natural circulation cooling" I don't understand. Is it more feasible with this design and why?
" Pros:
high temperature means we can use process-heat which is a much more efficient use of heat.
fast spectrum neutrons means we can burn importantly troublesome parts of nuclear waste.
fast spectrum is also better for breeding new fuel, significantly increasing how much energy we can extract from uranium/thorium.
passive natural circulation cooling is much more feasible.
fast spectrum is a little more complicated to control.
fast reactors require high enrichment.
inspection of the plant is very difficult with liquid metal.
high temperature liquid metal doesn't play nicely with metal pipes.
sodium burns in air and is explosive with water.
we simply do not have nearly as much experience with sodium as we do water and that really cannot be understated.
"Russia has been operating a sodium-cooled fast reactor for 45 years.
I suppose that "passive natural circulation cooling" means that plain convection of the coolant(s) is sufficient to cool the reactor, without involving pumps which could fail. Convection can't fail as long as there is coolant and no significant obstacles.
Based on your comment it sounds unreasonable to select this design. It must have some reason to exist?
It can make more fuel than it uses. It needs enriched uranium at startup but then can convert regular uranium and/or thorium to usable fuel.
The main advantages of using a fast reactor are less nuclear waste and more energy for a given fuel input.
Even burning some of the "nuclear waste" which is just nuclear fuel than needs refining.
Fast reactors do have some attractive features. They have better neutron economy and work better with plutonium. They can achieve breeding ratios comfortably above 1 with the U-Pu system. They produce less actinide waste since the chance of neutron capture not causing fission is lower, and can more effectively destroy actinide waste. Sodium-cooled fast reactors will operate at higher temperature than LWRs, enabling the salt thermal storage scheme they propose to use.
In large reactors, these features have not been enough to compensate for the disadvantages and sodium-cooled reactors have not been successful, coming in more expensive than light water reactors for a given power output. France, which had been developing fast reactors, has recently mothballed the effort with no plan to restart before 2050.
Russia has two of them, one 800MW and one 600MW, and plan to build a 1.2GW version.
> If the fuel itself rearranges to become more compact, say by melting and flowing, the reactivity could increase.
Wouldn't you just design the shape of the reactor so that if it got too hot for any reason, the shape it would melt into would result in a less compact geometry that would slow down rather than speed up the reaction?
How do you do that in a way that's amenable to conclusive analytic demonstration? For example, how do you prevent melted fuel from flowing into the cooling channels that go through the core?
About the only approach I'd be comfortable with would be dissolving the fuel in molten salt (probably chloride salt). This is not Natrium's approach.
Melting of fuel is not a theoretical problem -- it has actually happened at two fast reactors in the US (EBR-1 and Fermi-1, the latter the reactor in the hyperbolically titled book "We Almost Lost Detroit"). No explosions occurred, but it's very troubling the fuel melted at all. The NRC will surely insist on analysis of the consequences of partial fuel melting accidents.
To begin with you might start with a geometry which by design is already close to maximally compact, so that a geometry change would tend to go in one direction.
> For example, how do you prevent melted fuel from flowing into the cooling channels that go through the core?
Expect that to happen and use a geometry that doesn't cause the reaction to increase in speed if it does, e.g. because fuel flowing into the cooling channels would make the fuel less rather than more compact.
Slightly hesitant to jump in since pfdietz definitely knows more about this than I do... but...
Cooling typically means things like maximizing surface area, minimizing the thickness of the object being cool, etc.
Maximum neutron density presumably happens in a sphere, which is coincidentally the shape that minimizes surface area.
The whole point of a nuclear reactor is that it heats up, and you can convert that heat into useful fuel. Presumably that means you need to carry quite a lot of heat away per volume. Presumably that means putting the fuel into a spherical shape really doesn't work that well.
To cool something, you need a material which is a decent conductor of heat. The reaction materials are mostly uranium, plutonium and thorium, which are metals. They conduct heat pretty well all on their own.
Metal fuels also melt at considerably lower temperature than oxide fuels.
Uranium oxide melts at 2865 C; uranium metal at 1132 C, plutonium metal at just 639 C. In contact with iron, plutonium forms a eutectic with a melting point of just 410 C, below the melting point of zinc. There was a crazy reactor at Los Alamos, LAMPRE, that used molten eutectic Pu-Fe in tantalum tubes as the fuel.
Why would fuel melting be possible? The way I'd show it is by having the increased Doppler broadening and thermal conductivity and lots of headroom make that sort of accident impossible.
Presumably, those operating EBR-1 and Fermi-1 (and SRE in California, which also melted down) didn't think those would melt either. The issue is showing by analysis such an occurrence is not possible. It's not incumbent on anyone to show it is possible, it's incumbent on the prospective licensee to show it isn't.
> That application was submitted in March 2024 and is on track for approval in December 2026
Huh? Is this something where there's multiple incremental steps in the process, and that date is just the final approval stamp, or does it actually just take more than 1.5 years?
I'm generally pretty open to the idea that the NRC is bad and needs to be reformed, but a year and a half doesn't seem that unreasonable? Especially for a new reactor design.
I'm pretty sure this is extremely fast for the nuclear industry.
I hope this involves a lot of much faster feedback / modification cycles, and the process ends when all the feedback has been addressed.
It's always fun seeing someone jump into NRC discourse for the first time.
Feds