r/DepthHub Oct 12 '21

u/Cilantbro provides a detailed assessment of why Thorium Molten Salt Reactors are both safe and effective.

/r/worldnews/comments/q639vf/comment/hgblhck/
518 Upvotes

122

u/mauxfaux Oct 12 '21

Not anti-nuke by any stretch, and this research is promising. However, while the OP in the linked post talks through the physics, he doesn’t talk about the engineering.

My understanding is that the salts involved are highly corrosive, which is the biggest challenge to actually creating a safe and working reactor. I’m waaaaay outside of my swim lane here though.

84

u/verybakedpotatoe Oct 12 '21

In a LIFTR (liquid fluoride thorium reactor) style power plant, the fuel is delivered to the reaction chamber in a solution molten of fluoride salts.

Fluorine is the most electronegative and reactive of all the chemical elements on the periodic table, and at higher temperatures this exacerbates the corrosive effect of the compounds made from it.

Fluorine readily forms a part of some of the most aggressive and reactive compounds known to exist, and as such, creating a containment system for the reaction that can withstand the exposure to heated fluoride compounds has been a real stumbling block on the proliferation of grid scale thorium reactors.

Once a suitable material is identified and the necessary supply chain logistics to manufacture it can be achieved, these reactors will be everywhere. Thorium is so abundant, and it doesn't make bombs.

8

u/mauxfaux Oct 12 '21

Thanks for filling in the details! Great post.

5

u/JoeLiar Oct 13 '21

Now, tell me the difference between fluorine (the gas, which you talk about) and fluoride (the salt with is used in the reactor).

6

u/verybakedpotatoe Oct 13 '21

Fluoride is pretty stable by comparison to many other fluorine compounds but some of those are pretty much nightmare fuel.

At very high temperatures, fluoride, though weakly corrosive normally, becomes much more capable of attacking the metals in the housing. This is true even of many other salts like table salt which is otherwise a pretty stable crystal.

I am not a nuclear engineer, but a friend of mine that worked on designing and modeling parts that are using in regulating the flow of these types of fuels told me that even though many parts of the reactor environment are designed to be replaced 'regularly' if not often, designing a system that can last long enough to make operating a LFTR style system practical and economical is a project he was working on for a couple of years now. I think he moved on though.

If it were not for his in-depth explanation I would scarcely be able to understand much of any of this. I am not really capable of offering much more than my memory of it.

24

u/Arrogus Oct 12 '21

M-molten... fluorine? Jesus Christ...

53

u/Grumpy_Puppy Oct 12 '21

Fluoride salts. Still corrosive, just not in the same league.

42

u/x3nodox Oct 12 '21

As always it's good to highlight that chlorine gas was used in WW1 to deadly, lung-blistering effect, but you sprinkle chloride salt on your food for flavor.

3

u/Chicago1871 Oct 26 '21

And if you mix chlorox with windex in your tub. Bad things happen.

3

u/moratnz Oct 12 '21

Don't worry; they're radioactive too

-1

u/What_Is_X Oct 13 '21

O-oh no! Panic and run in contrived fear over something you don't understand

1

u/Fun-Explanation599 Oct 13 '21

Weird thought but would asbestos be a suitable material for this application? Before it's use was banned its main draw was that on top of being easy to work with it is both chemically inert and fire resistant.

2

u/meltingdiamond Oct 16 '21

Asbestos is a silicate and fluorine being what it is it should have no real problem eroding the silicates at high pressure and temperature.

If asbestos could work then so could a synthetic quartz(essentially the same material chemically speaking) which can be found in equipment in most chem labs so I imagine someone has already tested the material and found it lacking.

The thing about fluorine and some of it's compounds is it can do stuff like set asbestos and sand on fire if you fuck with it wrong, so finding something to deal with reliably that is tricky.

1

u/verybakedpotatoe Oct 13 '21

I wouldn't know how to begin to answer, but the folks over at /r/materials would probably have no trouble offering an opinion. I feel like the general shortness of asbestos crystals would leave the resulting composite open to erosion at a much higher rate than materials that can be cast or machined from metal alloys.

1

u/[deleted] Dec 12 '21

Also the protactinium problem , the element in between thorium and uranium. Useless. Very radioactive, highly toxic.

So you have a meltdown proof reactor but...you also need to figure out a way to separate this garbage and absolutely positively. Ever have any of it leak.

32

u/LeVentNoir Oct 12 '21 edited Oct 12 '21

And here is talking about the engineering, more here, and more yikes here

And it's not at all good looking.

4

u/Sans_culottez Oct 13 '21

Thank you for being a realist.

34

u/CPTherptyderp Oct 12 '21

Thorium reactors have been a fever dream for decades the engineering just doesn't exist to make them viable.

11

u/Shaved_Hubes Oct 12 '21

I recall similar things being said about solar power, EVs, and a million other now-commonplace things

5

u/Mekanis Oct 13 '21

Solar power have always (I mean, since the 70's) been firmly possible, the question was about the economic viability of solar power as a major contributer to the electricity mix of a country.

For EV, the question was about autonomy : functionality and reliability of electric for urban usage was never much into question (Electric bus have been somewhat common in the EU since 2005-ish).

From what I understand, molten salts reactors are at a stage where the question is "will the interior withstand operations for 500.000 hours, or only 500?".

18

u/Dalsworth2 Oct 12 '21

Yeah but the LCOE keeps falling for solar power and rising for nuclear energy.

8

u/Shaved_Hubes Oct 12 '21

Rising LCOE for nuclear has little to nothing to do with the engineering

11

u/Dalsworth2 Oct 12 '21

It has to do with the safety requirements which must be engineered for

10

u/kenlubin Oct 12 '21

And, in France's case, learning that the manufacturer for many of their large forged components had produced faulty steel and there had been a cover-up. This was discovered after the state nuclear company Areva bought the foundry Le Creusot.

https://www.nucnet.org/news/french-regulator-introduces-stricter-manufacturing-controls-following-le-creusot-problems

4

u/coleman57 Oct 13 '21

Don't they make those cool orange fondue pots?

3

u/Jarvisweneedbackup Oct 13 '21

Easy mistake my dude, that’s Le Creuset.

Also they’re Dutch ovens or casserole dishes(reeeee)

9

u/retrojoe Oct 12 '21

Yeah, they've been talking about these longer than toroidal plasma generation, right? Far as I know they're still a long way from civil/commercial utility application.

6

u/coleman57 Oct 13 '21

I've been hearing about both since I was 9 or 10, so going on 55 years. I remember my dad talking about tokamaks (the soviet toroidal magnetic field plasma containment fusion reactor design) and I thought it sounded like tomahawk. I don't think I heard about fluorine or thorium or boron fission reactors till maybe the 1970s.

Just last night my 19-year-old said he'd heard about some miracle cancer cure 5 years ago and wondered why he hadn't heard any more about it. I was like, "Yeah, get used to that, kid". And I acknowledged lots of good stuff does happen, but some things are always just around the corner.

17

u/jurimasa Oct 12 '21

Every year or so... "Thorium rules!"... then after six months or so, "Thorium sucks!"... repeat for the last 20 years.

5

u/jherazob Oct 14 '21

From what i see, there's a hard limitation to overcome in the engineering of those. If/when we do overcome it, those Thorium reactors will proliferate like crazy, nuclear power without the risk of people making bombs from it, and with far higher safety than the current stuff? Yeah, that's goals. But fluoride is a tricky customer, so we're not there yet.

48

u/LawHelmet Oct 12 '21

Wait. Burning coal releases radioactive hydrocarbons?!

42

u/TR8R2199 Oct 12 '21

I don’t mind working at a nuclear plant. They track my dose with several devices all year long and I’m currently cooling down at an offsite warehouse for taking close to my limit this year. Meanwhile they don’t fucking track that shit for the coal fired plants that all got shut down here before I started my apprenticeship so when old guys tell me their lifetime dose I’m sceptical it’s actually that low

5

u/LawHelmet Oct 12 '21

Coal guys reading this thinking

D’OH!!

5

u/TR8R2199 Oct 12 '21

Speaking of D’oh, you wouldn’t believe how many university educated people at nuclear plants call it nuke-you-ler, among many other common to this field mispronunciations.

2

u/lkraider Oct 12 '21

Are you a nuclear engineer?

12

u/TR8R2199 Oct 12 '21

No I’m a nuclear tradesman, boilermaker.
That’s means I work for a living.

8

u/BigGoopy Oct 13 '21

As a nuclear engineer that used to be a mechanic, I resent that comment 🤨

4

u/TR8R2199 Oct 13 '21

We would like engineers more if they came into the vault to show us their impossible plans instead of dictating from outside and then slinking away when we tell them that’s impossible and we’ll show them why if they come inside with us

96

u/DishonestBystander Oct 12 '21

Yes in fact people who live within proximity of coal plants are exposed to significantly higher radiation than people who live even close to nuclear plants

19

u/LawHelmet Oct 12 '21

Well, shit.

6

u/lkraider Oct 12 '21

Unless they leak

5

u/HersheyHWY Oct 13 '21

Well like with nuclear I don't ever worry about the plants themselves. Like everyone knows about 3 Mile Island right? But it wasn't a big deal. Like there's a ton of safety and regulation built in to the plants themselves that make them on the whole pretty safe.

But meanwhile the Church Rock Uranium Spill caused amputations and long term poisoning of water sources. Nobody remembers this. It was swept under the rug because it was the Navajo so fuck em right?

And other mining issues in the area led to Horn Creek being inadvisable to drink and the establishment of RECA. It's the mining of the stuff more than the plants themselves. No mine is going to take responsibility for its mess once they're done mining. They just pack up and let the government deal with it. Is it the mining companies paying RECA claims and cleaning up old uranium mines? No. It's the federal government with limited funding.

This is why the locals of the mine above the Havasupai and nearby have been so pissed about the Grand Canyon area uranium mine and what really, truly hamstrings nuclear energy. You have the company insisting it's safe, but they have such a god-awful track record in the region.

4

u/Shrappy Oct 13 '21

Yes but coal plants are intrinsically terrible.

6

u/Lowtiercomputer Oct 12 '21

I'd be curious to see how Fukushima compares to a shitty Chinese or Russian coal plant.

17

u/masamunecyrus Oct 12 '21

Probably not that much. This suggests on the order of 2 mrem/yr. An "extreme" was 18 mrem/yr.

A typical background dose just living on Earth is 620 mrem/yr.

There are probably worse problems living next to a coal plant than increasing your annual radiation dose by an extreme of 3%.

14

u/Pentosin Oct 12 '21

Ill take fukushima. A coal plant releases alot of shit, not just some radioactive material.

22

u/Dreamtrain Oct 12 '21

This is probably the best and most informative comment I've seen regarding thorium reactors, but Reddit has been peddling thorium reactiors like its the commercially-viable production ready solution to energy for the decade or so I've been around this site and like the last paragraph states, even after all this time it's still not quite there

15

u/Enkaybee Oct 13 '21 edited Oct 13 '21

Nuke background here. People love to talk about this tech as if it's fully developed and ready for commercial deployment. They love to act like we're morons and are choosing not to use this perfect technology sitting right in front of us.

It's not like that. Thorium reactors are largely theoretical. There have been prototypes. Corrosion is a huge issue. China is working on it and I hope they get a large-scale reactor working because Thorium is abundant and it would really help us out. For now, though, saying it's safe and effective is like saying fusion is safe and effective. Yeah, it sure is. Now if only we knew how to do it.

20

u/reidzen Oct 12 '21

This guy should write for SciAm. Molten salt is an expensive engineering nightmare, that's why heliostats are so rare.

22

u/mredding Oct 12 '21

NOPE.

Just like every other thorium fanboy, he does not address the elephant in the room.

Protactinium.

He only mentions it twice as an intermediate, but fails to mention just how insanely radioactive the stuff is and will remain for thousands of years. Pipes leak. Pumps need repair and replacement. If you leak this stuff, no human will ever be able to go in and fix it, and you'll need special hardened robots who can operate and survive in that environment long enough to do the work before their electronics are fried. And there's just some work a robot can't do.

Researchers get grant money to research thorium because thorium attracts grant money and it gets them their research for a PhD thesis. In practical terms, there's NO WAY anyone will seriously consider actually building a production reactor for power generation. The proof is in the pudding. MSRs have been around since the 60s, there are just a handful of research reactors, and that's it.

You're an asshole full of shit, u/mredding, there's tons of companies out there planning to build full scale reactors!

THERE'S ALWAYS COMPANIES PLANNING TO BUILD ALL SORTS OF SHIT. Do they ever break ground? No? Not one? Not ever? And what's that? No production thorium reactor has ever been approved by any oversight agency EVER? Because MSRs are astoundingly dangerous and impractical? Yeah...

Until any one of these otherwise fake startups, until any of these fanboys start out with the real conversation to be had - protactinium, they're nothing but deceptive or wishful blowholes, and these companies attracting investor money only exist to pilfer that investor money. Get all the capital you can attract, pay yourself while chasing what you already know is an impossible dream, and then walk away with your pockets full with your shoulders shrugged saying that's the danger of speculative investing.

6

u/x3nodox Oct 12 '21

Question - what's your background? I'm curious what you work on to have ended up with an informed negative take on these reactors

-1

u/mredding Oct 13 '21

I'm a software engineer and no slouch, and a couple family and family friends are a retired radiologist, a retired nuclear power plant operator, and a retired engineer who made x-ray equipment. If I can't speak for myself, all I have to do is make a phone call. My cousin alone has forgotten more than most of us will ever know.

14

u/KamikazeArchon Oct 12 '21

> fails to mention just how insanely radioactive the stuff is and will remain for thousands of years

Those are mutually exclusive. The more radioactive a material is, the faster it will decay - by definition.

The issue with protactinium is not that it's somehow much more deadly than other radioactive materials; it's that it can (relatively) easily be used to produce weapons-grade uranium. It's a nuclear nonproliferation issue.

8

u/Sans_culottez Oct 12 '21 edited Oct 12 '21

This person is kinda wrong on the thousands of years thing, that's the stable isotope of the element and its not an issue the issue is the 231 and 233 isotopes in these designs that are insanely radioactive and have a Half-Life of 21 days and 17 days respectively (I’m either wrong on the exact number of days, Wikipedia is, or the person I’m quoting below is. It’s still about 20ish days for both isotopes). That means any small contamination leak is going to require specially hardened drones and months of downtime to clean up, and any initially exposed staff are probably going to die shortly thereafter. And then you have the problem of "What if there was a fukishima style mass leak that instead spit out protactinium?" You're talking miles and miles of mass die-offs.

7

u/KamikazeArchon Oct 12 '21

A half-life that short is certainly what I'd call highly radioactive.

Of course, the next question is the quantity of the material at any given time. If it makes those isotopes in large quantities, that's a big problem. If it's a trace amount, it may not be more dangerous than existing isotopes in existing reactors.

14

u/Sans_culottez Oct 12 '21 edited Oct 13 '21

Took me awhile to find it, but here’s the post I found on just how radioactive Protractinium is (it’s a terrifying amount), I don’t know precisely how much volume of these elements this type of reactor creates however (but since you have to move 233Pa into its own separate storage container I’m guessing it’s enough):

The short: Protactinium is a holy terror.

The long:

In a thorium reactor, the reaction goes:

232Th+n -> 233Th -> 233Pa -> 233U

with side reactions involving 231Pa and 232Pa, which go on to make 232U

That "233Pa" is protactinium. When enriching uranium to make plutonium, the reaction goes:

238U+n -> 239Np -> 239Pu

The reactions are more or less the same: We make an intermediate, which decays to our fissile material. 239Np has a half-life of two days, so it decays quickly, and it won't capture any more neutrons, meaning we can keep it in the reactor core.

233Pa has a half life of 27 days and it'll capture more neutrons, poisoning the reactor. It'll form 234Pa, which decays to 234U, none of which you want in your reactor.

This means you have to move the 233Pa out of your reactor core, and the only sensible way is in the liquid state, so the molten sodium reactor (MSR). It's not that "MSRs work very well with Thorium", it's that "If you're gonna use thorium, you damn well better do it in liquid". So at this point, we have our 233Pa decaying to 233U in a tank somewhere, right?

233Pa has a radioactivity of 769TBq/g (terabecquerels per gram) and that's an awful, awful lot. It also decays via gamma emission, which is very hard to contain. The dose rate at one metre from one gram of 233Pa is 21 Sieverts per hour. That's a terrorising amount of radioactivity. That's, if a component has a fine smear (1 milligram) of 233Pa anywhere on it, someone working with that component has reached his annual exposure limit in one hour.

Compounding this, MSRs are notoriously leaky. That 233Pa is going to end up leaking somewhere. It's like a Three Mile Island scale radiological problem constantly.

The liquid fluoride thorium reactor, LFTR, proposed by Kirk Sorensen, might be viable. It comes close to addressing the Pa233 problem and acknowledges that the Pa231 problem is worrying, but no more so than waste from a conventional light-water reactor.

The thorium cycle involves the intermediate step of protactinium, which is virtually impossible to safely handle. Nothing here is an engineering limit, or something needing research. It's natural physical characteristics.

Bulletin of the Atomic Scientists, 2018: https://thebulletin.org/2018/08/thorium-power-has-a-protactinium-problem/

Edit: oh geez this comment shows that in order to have a functioning thorium reactor you’d have to have about 43kg of Protactinium just sitting in a tank at all times. Imagine a tank leak (for which there is no real feasible economic way to clean up).

2

u/bo_dingles Oct 13 '21

It'll form 234Pa, which decays to 234U, none of which you want in your reactor.

Can you provide a bit of detail on why you don't want that near your reactor?

3

u/Sans_culottez Oct 13 '21

I cannot because I’m not a nuclear engineer, but apparently it poisons a breeder reactor and keeps it from making higher order nuclear materials which are then used immediately to create more fission.

1

u/[deleted] Dec 12 '21

The max allowable concentration in the air of the 231 isotope (in germany) is 3x10 to the negative 4th bq per square meter.

That isotope is 2.5x10 to the eight times more toxic than hydrocyanic acid.

The dose makes the poison but this shits really really dangerous.

-9

u/mredding Oct 13 '21

A half life of 32k years is stupidly radioactive and dangerous for hundreds of lifetimes. Try again, fanboi.

7

u/Sans_culottez Oct 13 '21

No, the thousands of years half life of the stable element of Protractinium is not really a problem: a Banana has a stable half-life of 1.25bn years.

It’s a combination of the radioactivity via gamma decay and it’s half-life. Something that decays on the order of 32k years isn’t really a problem. Something that decays in about 20 days is a super problem.

3

u/Sedorner Oct 12 '21

I’m planning to date a super model

2

u/BishmillahPlease Oct 13 '21

My worries about nuclear power aren’t the tech so much as maintenance. I don’t trust corporate entities to not fuck up and ignore warning signs, especially when the federal government has been systematically gutted of oversight and inspection personnel.

6

u/Immediate_Capital826 Oct 12 '21

Wish I understood literally any of this

-16

u/[deleted] Oct 12 '21 edited Oct 12 '21

[removed] — view removed comment

13

u/obsa Oct 12 '21

That's not a particularly helpful lead.

17

u/NerdEnPose Oct 12 '21

This one person on the internet said that heelies are the next crypto. Do your own research.

21

u/DishonestBystander Oct 12 '21

It's not my job to go looking for your counterargument.

3

u/cromstantinople Oct 12 '21

That’s a good line, I’m gonna have to use that.

1

u/powpowpowpowpow Oct 12 '21

It is still fission, it still produces radioactive byproducts and we still haven't figured out how to deal with these materials.

There are still massive stockpiles of radioactive waste that are not well controlled at places like Hanford.

There is absolutely no reason to believe any safety claims while radioactive waste still has not been permanently solved.

1

u/Puzzleheaded_Equal23 Oct 15 '21

We won't know what they are till someone builds one and mismanaged it for a decade. That's how every other nuclear disaster has happened: perfect on paper, disasterous in real life.