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Permissioning is complicated because nuclear plants, even small ones, are complicated. There's a reason real nuclear plants are getting bigger and bigger.

You're comparing vaporware to technologies with a proven track record.




Well let me describe what I mean.

A couple years ago I got to sit in a meeting between people from a dozen GenIV reactor startups and a former head of the NRC. The reactor people said their biggest problem was that the NRC required a near-complete design before they would even take a look. At that point they either said yes or no. If no then that was the end of it, you were out of business. If yes you still had only a paper reactor. Getting to that point required several hundred million dollars.

That's a very difficult sell to investors. They said just a more phased process would help a lot. The NRC person was unsympathetic, said it wasn't the NRC's job to help develop or promote nuclear technology, and was uninterested in climate change.

Canada has a more rational approach to R&D, while maintaining rigorous safety. That's why MSR companies are moving there, and why the first one, Terrestrial Energy, is making solid progress.

(And as a side note, molten salt reactors are a lot simpler than light water reactors, because they have safety advantages inherent to the physics of the fuel and coolant.)


> And as a side note, molten salt reactors are a lot simpler than light water reactors, because they have safety advantages inherent to the physics of the fuel and coolant.

I don't know. MSR's are certainly interesting, but they have downsides as well as upsides.

Some of the PWR SMR's like NuScale also sport passive safety features, which should make it simpler and safer. Being a PWR, it's still a high pressure design, of course, which MSR's avoid.

While MSR are very cool, in some ways they're pretty scary too. I mean, you're pumping around tonnes of super-radioactive goop. What if you have a leak? At least with a traditional design you have a couple of extra protective layers, with fuel being contained in solid pellets contained in tubes. And you have to be very careful with the chemistry of the fuel salt; IIRC one of the early MSR's (ARE?) had to be shutdown since they messed up their redox chemistry which lead to fissiles plating out on the heat exchangers. Eek!

There's the famous Rickover quote that anybody can design a paper reactor, but real reactors tend to be complicated, over budget, and over schedule.


That quote by Rickover is one reason we should fix the NRC process, so companies don't have to spend $300M and get nothing but a paper reactor.

Moltex Energy agrees with you on pumping fuel salt. They keep their liquid fuel in a fuel rod, open at the top, no pumping. All the rods are immersed in a pool of liquid salt coolant, which just sits there. Secondary coolant in pipes through through that.


> That quote by Rickover is one reason we should fix the NRC process, so companies don't have to spend $300M and get nothing but a paper reactor.

(I didn't answer your previous points about the NRC process, but for the record, I completely agree with you.)

> Moltex Energy agrees with you on pumping fuel salt. They keep their liquid fuel in a fuel rod, open at the top, no pumping. All the rods are immersed in a pool of liquid salt coolant, which just sits there. Secondary coolant in pipes through through that.

Yes, Moltex is an interesting design. The main drawback, AFAICS, is that since the fuel concentration in the fuel salt is quite low compared to solid fuel designs, they have to use pretty enriched fuel. I think their current plans call for 40% Pu. And the breeding ratio is poor, around 0.5 according to a paper I skimmed through a while ago.


Is that for the fast reactor design? They also have a thermal design which I'd assume is much lower enrichment.


Yes, the "waste burner" design. So the entire fuel story revolves around having access to spent fuel which they can reprocess to extract the Pu.

Yes, they also have the thermal design which I'm quite sure requires much lower enrichment, but AFAICT is more a concept than something they're actively developing. It makes sense of course to focus on one design at a time, unless they have infinite money.

One of the other fast spectrum MSR startups, Elysium, also proposes using spent fuel + maybe leftover military Pu for startup. The interesting thing about Elysium is that their design at least breeds, so they only need enriched fuel for starting up. They're saying that they can run up to 40 years before needing to reprocess the fuel, just by adding U238 online to the salt.


Only several hundred million dollars? This is not some software startup we are talking about here. The reactors are going to cost several billion dollars so it doesn't make sense to let startups just "wing it". Even if the R&D costs are 10 billion you could quickly amortize it by simply building multiple reactors with the same design. At least that is what the pro nuclear lobby says will happen.


WOuldn't you expect those kind of costs? It seems fairly low compared to airline development costs, where a program may cost $25+ billion.


It sounds like we should let Canada shoulder the brunt of the research and then build commercial MSRs once Canada has mastered the tech....in 50 years or so.




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