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.
> 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.
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...
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.
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.
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.
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.