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Application submitted for US molten salt research reactor

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Re: Application submitted for US molten salt research reactor

#171

Post by ethbr0 »

dangerlibrary wrote: post #17
sophacles wrote: post #15

Earlier quoted context omitted.

> So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. I was under the impression that there was a heat exchanger in the path - that is the reactor turns water into slightly radioacive steam, which is sent through a heat exchanger to turn different water into non (or way less anyway)- radioactive steam for the turbines. So bo…

That makes a lot of sense. I think I was confused by news stories about situations where the reactor has failed in some way, and then there are stories of how radioactive water needs to be stored / disposed of somehow.

In those historical cases, the priority was cooling the core, the easiest method (especially if a substantial amount of plumbing is wrecked or questionable) is dumping water into it.

Which then becomes irradiated, and pools via gravity in any lower voids, and then eventually needs to be dealt with.

Re: Application submitted for US molten salt research reactor

#172

Post by pfdietz »

jabl wrote: post #167
pfdietz wrote: post #164

Earlier quoted context omitted.

It means the offgas storage system has to be designed for a large heat load, even in accident scenarios. It also means the common MSR talking point that the FPs stay in the salt is not correct.

> common MSR talking point Well, a lot of 'common MSR talking points' are overblown, firmly detached from reality. Or at least conveniently ignoring all the significant challenges remaining in industrializing MSR technology. MSR fanboys are the most tedious of the pro-nuclear side of the energy debate, perhaps beaten only by the "this entirely unproven aneutronic fusion concept will imminently solve all our energy wo…

This is why I refer to Helion as the "least dubious" fusion concept. :)

Re: Application submitted for US molten salt research reactor

#173

Post by preisschild »

Galaxeblaffer wrote: post #96
powerhour wrote: post #44

Earlier quoted context omitted.

It's also sad that industry completely failed to convince the population that they can provide a safe solution. For all the credit we give BigCo for creating propaganda, it's curious that they were unable to be successful here, given the stakes.

Energy too cheap to meter doesn't sound like a good investment from a capitalistic viewpoint.

Not for the companies that build and design reactors

Re: Application submitted for US molten salt research reactor

#174

Post by robertlagrant »

throwaway894345 wrote: post #72
PaulHoule wrote: post #9

Earlier quoted context omitted.

Fluoride salts are good for fissile uranium + fertile thorium. If you want to work with a plutonium/uranium 238 cycle then chloride salts are a better choice. Plutonium doesn't dissolve very well in fluorides. Molten chloride reactors can have performance characteristics right out of science fiction, it seems possible for such a reactor to not only breed more fuel but to destroy the long-lived (500 year) fission prod…

> We can produce heat for hydrogen, replacing the need for fossil fuels in heating, transport and industry. What does it mean to produce "heat for hydrogen"? Why is heating hydrogen a useful property (how does hot hydrogen replace fossil fuels in heating, transport, and industry?)? That seems oddly specific, so I assume I'm misreading something?

I think it means we can produce heat that can power the generation of hydrogen, e.g. from water.

Re: Application submitted for US molten salt research reactor

#175

Post by panick21_ »

pfdietz wrote: post #163
panick21_ wrote: post #154

Earlier quoted context omitted.

Yes, one of the reason I like that reactor design. They basically put something in the fluoride that is basically designed to corrode so that the actual reactor vessel doesn't. If I understand correctly. Their design doesn't require the 7 year swap cycle most MSR do.

Right! They've got the same thing going that ordinary LWRs do: the neutrons lose their energy in a surround liquid rather than in a solid moderator or solid structural materials other than the fuel rods (which are designed to be replaced often anyway). The design even adds some hafnium to the coolant salt (substituting for zirconium, which is the sacrificial metal you refer to there); hafnium serves to shield the rea…

> One additional advantage

The problem with that is that you would likely require a different design and go threw full licensing. So in practice this will likely not be used.

Re: Application submitted for US molten salt research reactor

#176

Post by panick21_ »

ortusdux wrote: post #42
politician wrote: post #27

Earlier quoted context omitted.

One of those safety improvements -- a freeze plug -- passively halts the reaction in the event of a power cut. The reactor sits on top of a vault that has a larger volume separated by a narrow tube containing molten salt that has been frozen into a plug by cryocoolers powered by the turbines themselves. If the pumps stop for any reason, then the plug quickly melts and the molten fluid from the reactor drains into the…

One of my favorite safety elements is often over-looked: they operate at 1 atmosphere. So much of the cost and bulk of a traditional reactor is the shielding needed to protect from an over-pressure event.

And even better, most of the things that are dangerous in a traditional reactor is chemically bound to the salt. So even if there is some kind of explosion, these materials would not be vaporized and transported in the air with wind.

So no crazy misinformed graphics all over the news.

So even if you drop a hand-grande into that reactor, it just gone be like throwing a rock into a bucket full of toothpaste. Its gone be a mess but its not gone result in a lot of airborne materials.

Re: Application submitted for US molten salt research reactor

#177

Post by panick21_ »

ortusdux wrote: post #39
JumpCrisscross wrote: post #34

Earlier quoted context omitted.

Are freeze plug failures recoverable? Or is is this a final failsafe that toasts the reactor?

Easily recoverable. The tube drains into a collection tank filled with control rods, so any reactions are halted. You can just reheat the salt and pump it back into the reactor. Reportedly, one of the first test reactors in the 50's was shut off every Friday and restarted on Monday. A full power loss, what would be catastrophic for any other reactor, was tested weekly for a year without issue.

I love the image of some guy before going home hitting the red button and some guy on Monday just hitting the green button.

Re: Application submitted for US molten salt research reactor

#178

Post by panick21_ »

pfdietz wrote: post #164
jabl wrote: post #142

Earlier quoted context omitted.

> "Over 40% of [fission products] leave core [in offgas]" "Large fraction of cesium, strontium, and iodine end up in offgas" That could, in theory at least, be an advantage if you have a good process for capturing and storing that offgas (reacting it with something to make it solid and then glassifying it, for instance). In a traditional fission reactor, gaseous fission products cause swelling and cracking of fuel pe…

It means the offgas storage system has to be designed for a large heat load, even in accident scenarios. It also means the common MSR talking point that the FPs stay in the salt is not correct.

Moltex Energy talks a lot about that. It is actually pretty nice, some things stay in the salt, some leave it. The most dangerous stuff that shows up in the news a big scary cloud coming over from Japan to the US would still be in the salt.

Some other things that you really don't in your fuel, like Xenon and Krypton will bubble out.

So I think overall it is an advantage.

Re: Application submitted for US molten salt research reactor

#179

Post by panick21_ »

pnw wrote: post #51
dangerlibrary wrote: post #12

So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…

I hope we manage to improve the design over the 1960s version MSRE which cost $130m to clean up due to unforeseen problems including a near-criticality incident. Certainly there is a lot of research to be done.

Even with that issue, it was still a project that was amazing, they did incredible work, and the cost was very small. Almost hilariously so compared to other nuclear reactor projects.

Had that same team received the funding for a next large commercial prototype, the world would be different now.

But sadly Nixon preferred to spend money for nuclear research in California, Tennessee not exactly a priority.

Alvin M. Weinberg also didn't make himself any friends with government higher ups when he criticized PWR programs for civilian nuclear.

Re: Application submitted for US molten salt research reactor

#180

Post by kennend3 »

mulmen wrote: post #104
kenned3 wrote: post #78

Earlier quoted context omitted.

non-metals have their own problems and glass tends to have some really weird properties. I would think a major one would be their failure mode. Metals flex and expand before they eventually fail. Glass/ceramic is fine until suddenly it isn't and has a total failure. Think of a window being hit. If it were metal it would probably deform but if it is glass it shatters. Next would be joining them on-site. If needed, met…

Glass is already basically welded, or maybe it's more like brazing. But an oxyacetylene torch can be used to work with glass just as well as to cut or weld metal. Metals also have weird properties. Like tempering and hardening based on temperature. In an industrial setting you need expert welders with deep knowledge of the materials or a weld is going to fail and ruin your day. So it doesn't seem like a huge leap to…

I noticed you focused almost exclusively on the welding while ignoring the brittle nature of glass?

I would think that putting liquid salt in a a glass pipe is somewhat asking for trouble. One of the many issues with glass is "thermal shock".

Let's say there is a fire and water based sprinklers are activated.. what will the 1,400F glass do once water touches it?

Or there is an accident and someone bangs into the glass. Metal can deform and not fail, glass cant.

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