Slashdot Mirror
A Nuclear Startup Will Fold After Failing To Deliver Reactors That Run on Spent Fuel (technologyreview.com)
Transatomic Power, an MIT spinout that drew wide attention and millions in funding, is shutting down almost two years after the firm backtracked on bold claims for its design of a molten-salt reactor. From a report: The company, founded in 2011, plans to announce later today that it's winding down. Transatomic had claimed its technology could generate electricity 75 times more efficiently than conventional light-water reactors, and run on their spent nuclear fuel. But in a white paper published in late 2016, it backed off the latter claim entirely and revised the 75 times figure to "more than twice," a development first reported by MIT Technology Review. Those downgrades forced the company to redesign its system. That delayed plans to develop a demonstration reactor, pushing the company behind rival upstarts like TerraPower and Terrestrial Energy, says Leslie Dewan, the company's cofounder and chief executive. The longer timeline and reduced performance advantage made it harder to raise the necessary additional funding, which was around $15 million. "We weren't able to scale up the company rapidly enough to build a reactor in a reasonable time frame," Dewan says.
There are around 50 nuclear startups designing 4th generation reactors. Some were always going to fail. In fact most will probably fail. Some will succeed though.
NuScale is the closest to market. Their design has already passed NRC phase 1 review, and it has been certified as meltdown proof. They will be constructing their first 12 reactors in Idaho for Utah municipalities. Hopefully in a decade they will be mass producing them like airplanes.
Being able to reprocess spent nuclear fuel means that there's less of a storage issue for nuclear waste.
Why are nuclear fanboys still pushing debunked Thorium breeder technology that has been relegated to a scientific curiosity? The new messiah is SMR's.
http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspx
I think this is less that science is hard, and more that claims two orders of magnitude improvements in anything are probably bullshit unless there's a working demonstration. I'm also not sure that millennials are any worse at falling for that kind of bullshit than previous generations were either and sites like Kickstarter just mean that the public can get in on funding the kinds of scams that venture capitalists have been shown for decades.
Why is anyone wasting their time on this when there's thorium?
Their design does use thorium. The base salt is thorium fluoride. You heat up the salt till it melts, and then just mix in the nuclear waste, hook it up to a turbine, and presto, energy too cheap to meter.
Thorium salt reactors work GREAT in theory, and nerds tend to love them. In reality, there are ... problems.
I'd rather that money be spent/wasted on failed attempts at getting us off of fossil fuels when the math indicates that the idea might work, than to continue to burn hydrocarbon fuel for stationary power plants.
Do not look into laser with remaining eye.
The momentum of the regulatory structure is impressive.
First we had Rocket Jesus, a.k.a Elon Musk, and now we have Nuclear Jesus, a.k.a Leslie Dewan. Although, molten salt does remain (eventually) a viable idea.
when the wiki page says gas plants cost $1900/kilowatt vs $5000/kilowatt.... That's the only part I don't get. Is this just building in alternative sources for better grid reliability?
Hi! I make Firefox Plug-ins. Check 'em out @ https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/
Right. The basic design principles were perfectly well-understood 60 years ago. No one is going to come along and improve the efficiency by a factor of 75. It's a claim that anyone with any sort of technical knowledge, not even specific knowledge of nuclear energy, would reject out of hand. It was bullshit for dimwitted financial types and loony environmentalists, some of whom apparently took the bait.
But I thought there were already "breeder reactors" that did this. How was this design different from them?
in a paper on its site dated November 2016, the company downgraded “75 times” to “more than twice.” In addition, it now specifies that the design “does not reduce existing stockpiles of spent nuclear fuel” or use them as its fuel source.
So, something like "I have a cure for the worst disease ever [...] I meant a cure for a disease [...] Actually, it is just a placebo".
I don't know what I find more unbelievably ridiculous: people getting tons of money from simple words with no kind of validation (not even making too much sense) and losing all of it; or their apparent lack of awareness of what written whatever implies, mainly nowadays and with internet! How can anyone say so big lies in a so public fashion without expecting any kind of consequence! IMHO, lying at all is a bad policy but, under these circumstances, it is almost a crime!! Even by assuming that they could get away with it, what about their self-respect? Thinking about others' reaction when realising about the truth? I cannot imagine how could I ever trust even a tiny bit what a person able to do such a thing says. I cannot even picture myself having the before and after conversation with someone like that. "I see that all what you said were lies and you undeservedly got lots of money which you lose. OK. Let's have a cup of coffee and not talk about all this anymore!".
Custom Solvers 2.0 = Alvaro Carballo Garcia = varocarbas.
claims two orders of magnitude improvements in anything are probably bullshit
Normally I'd agree, but in this case the 10^2 improvement is largely based on the horrific inefficiency of our current fleet of solid-fuel, water moderated nukes, which is something like 0.7%. The vast majority of this efficiency gain is due to the liquid-fuel design (in this case, molten salt), which allows fuel to be reprocessed on the fly, whereas "traditional" nukes use solid fuel rods which degrade over time, and become unusable long before their energy content is anywhere near used up.
Other molten salt designs are under development, such as LFTR, which have similar claims on improved efficiency. The main difference is that this one (WAMSR) was supposed to be able to burn up existing stockpiles of spent nuclear fuel. Apparently that particular trick turned out to be more difficult than they anticipated.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
Being able to process English would be a great thing for the fake news editors to handle first. MIT spinout, really?
Would you prefer 'MIT flameout' instead?
Better yet, MIT Fallout!
There are around 50 nuclear startups designing 4th generation reactors. Some were always going to fail. In fact most will probably fail.
No there are lots of them CLAIMING to be developing new reactor designs. Some of them might actually be working on the problem even. Curiously we've seen zero of these actually make it to market.
Some will succeed though.
There is no guarantee of that.
NuScale is the closest to market.
Maybe. Best info I can find says they hope to have an operational reactor in 2024 and that was their projection in 2013. That means optimistically they might have something to show 6+ years from now. Not exactly cause for excitement.
Their design has already passed NRC phase 1 review, and it has been certified as meltdown proof.
NRC phase 1 review is a "Preliminary Safety Evaluation Report (SER) and Requests for Additional Information". It does not mean it has been certified as anything.
They will be constructing their first 12 reactors in Idaho for Utah municipalities.
If that were true you would think they would post it somewhere on their website. Perhaps you are talking about this project?
Hopefully in a decade they will be mass producing them like airplanes.
While I wish them well I think this is a good approximation of impossible.
Many of the processes required to utilize thorium (which is fertile, not fissile, but fertile at slow-spectrum which is interesting) can be applied to 238U at fast spectrum instead. EBR-II (IFR) demonstrated this. The main advantage of thorium is it's an abundant reserve source for making 233U (+232U, which makes it difficult to handle) if we can't find uranium anymore.
IIRC, a startup called Oklo is looking at reviving the EBR-II technology at very small scale, ~1-2MW, basically diesel generator replacement (or maybe it becomes your primary electricity source and the grid becomes your "backup"?)
the real at&t mix
The DUPIC fuel cycle allows for the direct reuse of PWR fuel in CANDU heavy water reactors. The only thing required is mechanical modification of the PWR fuel bundles so that they fit into the CANDU fuel channels.
...si hoc legere nimium eruditionis habes...
Four issues : Cost, oversight, nuclear weapons capabilities, and transportation logistics. Cost ought to get two slots, to signify how much of an issue it actually is. The others could be solved at great cost. The rub, renewables are cheaper.
Nuclear isn't going to disappear but the idea of expanding it "on a budget" to meet the world's local power needs while wasting abundant clean, cheap renewable energy just doesn't make actual real-world business sense.
You haven't proven that any will succeed any more than you've defined success.
You could say that about any innovation. Internal combustion--you're going to deliberately set off thousands of explosions inside a sealed, iron box? Steam power? Microprocessors? Fire itself?
Imagine the first person who proposed "we're going to build a boat out of steel and it's not going to sink!" It's ludicrous! Steel is expensive. And everyone knows metal sinks and wood floats. Why on God's green Earth would you make a boat out of steel instead of good old fashioned wood?!? I'm not going to listen until you prove you have a working business model.
We won't know if any of these companies will succeed until one does. I can't predict which one it will be so I'm not willing to invest. Others have greater risk tolerance than I do, yay for them. In the mean time, I wish them all the best because the promise is amazing.
Processing spent fuel as you suggest is extremely dirty and generates about 10x the amount of original waste, most of it highly radioactive.
People forget the US tried to reprocess fuel for a while, the location is a radioactive superfund site.
Being able to process English would be a great thing for the fake news editors to handle first. MIT spinout, really?
That's perfectly normal American English Technobabble and has been since the mid 1960s. (I personally encountered it quite a lot, especially with respect to the substantial collection of laser and holographic spinouts from the University of Michigan.)
These days "startup" is more common. But "spinout" is both still valid and more specific, as it identifies implies a single institutional source of the founding technology and bulk of the founding personnel (usually identified in the sentence as a "from Foo" modifier). "Startups" may also be born by aggregation, while "spinouts" bud from an ongoing institution, typically when there's something to be commercialized that isn't a good fit with the parent institution's ongoing mission.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
The problem with any theoretical design is the same, it's untested. Pebble bed and molten salt reactors are a interesting idea but are untested, until someone builds one we don't even know if they will work. The molten sodium (the salt) used in your particular example has a tendency to burn quite fiercely when exposed to oxygen and fires and nuclear material are catastrophic failure.
not debunked at all, smarter countries than yours are doing them
When asked who was responsibility for the discrepancy between 75x and 2x, the lead scientist Michael Bolton confessed, "Oh shit, I always do that! I always mess sup some mundane detail." :P
Well, there's spam egg sausage and spam, that's not got much spam in it.
Much of the problems I attribute here to politics and impatience - the funding dries up when folks just get impatient that progress isn't occurring. It's understandable, but sometimes there are HARD problems that need a lot of time and money to solve, yet the payback will be worth it in the long run. Nuclear frequently ticks that mark IMO. I don't think our (US) investment climate is compatible with this much.
A old letter posted by Will Davis @atomicnews today - http://ecolo.org/documents/documents_in_english/Rickover.pdf - Easily as relevant today, and basically agrees with your statement. It's a hard problem but we've done hard problems before.
In some sense, I wonder if our economic trend towards consolidation of resources into a few rich individuals is a subtle "invisible hand" reaction to our incessantly short-term thinking, because it's those few with overabundance who are in the best position right now to fund long-term, hard projects with open-ended amounts of capital.
the real at&t mix
molten salt reactors are a interesting idea but are untested
Molten salt reactors are proven technology. They ran one at Oak Ridge for thousands of hours back in the 1960s. There's a ton of info about this online, such as this lecture from a few years ago about LFTR. The Chinese currently have the most active (and best funded) program in this area. With any luck we might see a commercial product from them in the next few years, which could be a real game changer.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
"I thought the MIT kids were smarter than that."
And they are. They've managed to find gullible enough investors as to live la vida loca for eigth years in a row.
*And* they'll probably will manage to paint their "failure" as an advantage because of "the lessons learnt" for their next gig.
I'd rather that money be spent/wasted on failed attempts at getting us off of fossil fuels when the math indicates that the idea might work, than to continue to burn hydrocarbon fuel for stationary power plants.
I'd rather not nurture your false dichotomy, and suggest instead using the money to improve and implement already-proven technologies like wind and solar.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
All that was done with the Integral Fast Reactor in the 90's. It ran well for a couple years before being defunded by Gore and his allies.
This company failed for business reasons, not theoretical ones.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
There is a large difference between the remarkable claims made for LFTR and those of TransAtomic (and some others) trying to take shortcuts with non-breeding designs. Some of the later face substantial skepticism even within the MSR community. The use of thorium in non-breeding designs is also questionable, as it makes the eventual processing more difficult.
LFTR's claims rest on sound science and successful experiments. Running an MSR on U233 has been demonstrated. Breeding thorium into U233 has been demonstrated in solid fuel, which is even more difficult. The chemical processing has also been demonstrated offline. The components of a LFTR have yet to be integrated, but they have been proven. The astounding efficiencies achievable are a result of the ability to breed and completely consume the fuel, which is possible because salts can't be damaged by radiation. For many reasons, salts are simply a superior fuel/coolant form for nuclear reactors.
In addition to the remarkable efficiency of LFTR, there is a more recent variant of LFTR adapted to be fueled by actinides from spent fuel, allowing it to destroy "nuclear waste" 90x faster. This is another remarkable claim with a solid basis. It arises from the realization that actinides in spent fuel are the long term concern, not what is essentially natural uranium. Separating out the (barely radioactive) uranium beforehand is trivial, and greatly speeds the process of destroying the hazardous component.
You mean that little 62MW demo plant they built?
It worked okay but after what happened in Japan no one is going back to that design. No, not Fukushima, Monjou. Numerous attempts, numerous failures including some quite serious accidents. Liquid sodium will spontaneously ignite on contact with air, and explode on contact with water so fire control is a bit of a problem, and of course they had just such a fire.
In the end it just proved too problematic and costly to bother with, and decommissioning is going to be expensive too.
As you say, business reasons, no-one is going to throw money at that idea again.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Designed decades ago using lots of manpower and ingenuity, these are already efficient enough to run off the waste of existing reactors (about 4 reactors to one CANDU). I think Korea was looking into this, and may already be doing so. CANDU HWR waste is a lot less of a problem than LWR, but it is harder to get nuclear weapons grade plutonium from (uses un-enriched uranium, and is much harder to extract anything from waste). There are even reports of the design working with Thorium with minor adjustments (already works with MOX, mixed oxide, fuels containing thorium).
Yes, however there is also abundance of uranium and ready facilities to prepare uranium based fuel.
In detail, thorium is prevalent on land whilst uranium in oceans (estimated more in total than thorium) additionally considering existing infrastructure and equipment to mine/process and prepare power plant ready fuel rods and all the paperwork related to build a new power plant it is simply cheaper to build something close to existing solutions then to push for a novelty. Some government studies and research would be needed to brake the impasse.
An interesting design is the Traveling Wave Reactor being researched by TerraPower, they suppose to build a prototype in China.
Thanks for the link! I've been a fan of Sorensen's for many years, but I didn't know he was working on using SNF now too. I don't know enough about TransAtomic's approach to critique it, but your points all make sense to me. My only nitpick would be the reason why molten salt is the enabling factor in the efficiency gains: your argument is that salts don't mind getting smacked around in the neutron flux (they remain chemically stable); whereas I would say the key factor is that liquids are more chemically miscible than solids... this is what allows the fuel to be reprocessed on the fly, which in turn allows all (or nearly all) of the fuel to be burned while waste products are continually removed. Both of these aspects are important.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
No, pebble bed was very much tested. Turns out it produced massive amounts of Strontium-90 dust, clogging up the reactor and even escaping into the ground water.
And as pointed out below, molten salt has it's own problems with a highly chemically reactive coolant. I don't know about you, but the potential of a leak leading to coolant boiling away in chemical reactions does not fill me with a strong sense of safety; after Fukushima the nuke fanbois tried to sell us on molten salt because the heat absorption capabilities would make the reactor safe from decay heat meltdown without needing active cooling. But considering what damage an earthquake could do to the piping holding the secondary coolant, which would then merrily burn away reacting with water and/or oxygen...
"I know I will be modded down for this": where's the option '-1, Asking for it'?
Silly, the sun does not shine at night. And the problem is storage ("capacitance"). Scaling up the tesla battery from australia to a 100% renewable grid would take $40 trillion+ for just the us. That is why 95% of storage is pumped hydro. Maybe you should do your homework, silly.
But I thought there were already "breeder reactors" that did this. How was this design different from them?
Old fashioned breeder reactors turn U-238 into plutonium. Although plutonium can be used as reactor fuel, it can also be used to make bombs. Furthermore, these reactors use fuel rods, and pressurized containers, and have the same complexity and safety problems as LWRs.
What makes this reactor different is that it doesn't make plutonium, it burns the fuel that in breeds in situ so no extra expensive reprocessing is needed, and it is an inherently safe design: It can't have a "meltdown" since it is already liquid, and it is not pressurized.
That is the theory. In practice, molten salt reactors don't have a very good track record.
Molten salt reactor
If by proven you means experimented with but no actual safety, reliability, cost or power generating capability analysis done.
Running a little experimental reactor for a couple years tells you nothing about the commercial viability let alone safety. One of the biggest problems with "molten salt" or liquid sodium reactors is that if the reaction vessel holding this mix of highly radioactive sodium and uranium mixture is every directly exposed to water or oxygen it will explode, burn and fill the atmosphere with a highly radioactive cloud of burning sodium which will then rain down on the surrounding countryside.
Reactor designs like molten salt reactors always fall apart as viable designs when they start talking about surviving things like earthquakes or other natural disasters. This is because to engineer around those disasters you have to do stuff like the current Georgia reactor under construction and spend $20 Billion building a pressure vessel that can survey tidal waves and earthquakes that wipe out the rest of the plant. And when that eventual power is priced at $0.25 kw/hr it's completely uneconomical.
The government doesn't research these "innovative" reactors because every time in the past they've tried the site ended up a superfund site. Every Single Time.
You are forgetting the 4th dimension.
Wait, our nuclear waste can time travel now?
Sure. But it only goes in one direction.
Running a little experimental reactor for a couple years tells you nothing about the commercial viability let alone safety.
Pardon my French: horseshit. Obviously we build smaller ones on the way toward building bigger ones -- whether it be nukes or jets or whatever -- it's called engineering.
One of the biggest problems with "molten salt" or liquid sodium reactors is that if the reaction vessel holding this mix of highly radioactive sodium and uranium mixture is every directly exposed to water or oxygen it will explode, burn and fill the atmosphere with a highly radioactive cloud of burning sodium which will then rain down on the surrounding countryside
You seem to be conflating molten salt with molten sodium. They are completely different. Sodium by itself is highly reactive, whereas sodium chloride (though somewhat corrosive) is quite stable. If you hit a LFTR with a bunker-buster bomb, it would indeed spray radioactive molten salt around the countryside. But it would rapidly solidify and fall to the ground, where it would be easy to find with a geiger counter. (Unlike radioactive steam which just floats away...)
you have to do stuff like the current Georgia reactor under construction and spend $20 Billion building a pressure vessel that can survey tidal waves and earthquakes
The reason for that pressure vessel is because water boils at 100C, and nuclear reactors are just getting warmed up around 400C. So a water-cooled reactor needs plumbing that can handle 150 atmospheres of pressure, just so they can run the reactor at the barely efficient temperature of 300C. But since FLiBe doesn't even melt until 360C (and doesn't boil until well over 1400C) you have a very heat-dense material that can both transport your fuel (enabling on-the-fly reprocessing) and cool your reactor over a broad range of heat regimes... and it does all this at ambient pressure. So you don't need that $20B pressure vessel in the first place.
Watch the video I linked above, it will explain all this in greater detail, and save me the trouble of writing it.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
You seem to be conflating molten salt with molten sodium. They are completely different. Sodium by itself is highly reactive, whereas sodium chloride (though somewhat corrosive) is quite stable. If you hit a LFTR with a bunker-buster bomb, it would indeed spray radioactive molten salt around the countryside. But it would rapidly solidify and fall to the ground, where it would be easy to find with a geiger counter. (Unlike radioactive steam which just floats away...)
Maybe you should investigate the chemical composition, it's not molten NaCl. It's typically a lithium flouride or berylium flouride based salt as in previous designs, though the recent tendency in these designs has been to super heated liquid sodium for heat transfer.
The reason for that pressure vessel is because water boils at 100C, and nuclear reactors are just getting warmed up around 400C. So a water-cooled reactor needs plumbing that can handle 150 atmospheres of pressure, just so they can run the reactor at the barely efficient temperature of 300C. But since FLiBe doesn't even melt until 360C (and doesn't boil until well over 1400C) you have a very heat-dense material that can both transport your fuel (enabling on-the-fly reprocessing) and cool your reactor over a broad range of heat regimes... and it does all this at ambient pressure. So you don't need that $20B pressure vessel in the first place.
The reason for the pressure vessel and the surrounding concrete sarcophagus (the huge cost in any reactor) is to contain a meltdown. The difference between Chernobyl and Fukashima was Japan had a full concrete sarcophagus containment chamber (which eventually leaked) whereas Chernobyl had no containment vessel so when it went critical, exploded and then began to burn there was nothing to contain the radioactivity that rained down on the surrounding countryside.
Nuclear's an uneconomical boondoggle. It's not cost effective, it's dangerous and it's accidents are catastrophic. There is literally no reason to pursue it, we have better, cheaper, cleaner means of energy production.
The glut in the uranium market doesn't help. Why go to advanced technologies when basic uranium fission is so cheap.
Fission reactors are little more than putting hot rocks in a jar and running water over it, and using that to power a steam turbine.
Let the 21st century researchers at least do fusion, or better yet something actually advanced.
Let's forget for one second about what accomplishing fusion implies, how far away we are from having a working version and if it is even possible to get there ever. And let's focus just on answering one question: how are you planning to convert nuclear power into actually-usable one (e.g., electricity)?
Do you know what nuclear (fission or fusion) power really means, right? Basically, it means efficiently generating heat for long periods; pretty much what oil or gas accomplish by different means. You are basically feeding in a small amount of energy (to separate particles or merge them by provoking a set of chain reactions autonomously multiplying your original effort) to get a bigger one in a form which you can use for other purposes (heat). So, my question again: how are you planning to convert that heat from fusion into something really useful for us? You don't want to use the old heat-mechanical-electrical (water-steam-turbine-electricity). What do you propose, then? An app, a cool-looking attitude or just an empty promise? LOL.
Custom Solvers 2.0 = Alvaro Carballo Garcia = varocarbas.
Yet we have had provable meltdown proof reactors since the 1980's. See Experimental Breeder Reactor II
You should read your link. They did tests to see if the reactor would not melt down under specific circumstances. This is a far different thing than proving it is "meltdown proof" under all circumstances. Passive fail-safe cooling systems are a good thing but they only solve some of the dangers presented by fission power plants. Furthermore just because they are in place does not mean they still cannot fail due to flaws in engineering, construction, maintenance, natural disasters, or physical damage.
You seem obsessed with meltdowns. That is just one failure mode among thousands for a nuclear power plant and not the most likely even for reactor designs without fail-safe designs. Even with a reactor that theoretically or provably cannot melt down, there remain plenty of ways for them to contaminate the surrounding areas. Nuclear power is a useful thing but pretending it doesn't carry some substantial risks is irresponsible.
From what I read, which admittedly isn't much, the primary concern to be addressed with in molten salt reactors is the fact that it is highly corrosive. Which means that they won't last as long as conventional reactors, and require costly maintenance to keep in service for any reasonable lifespan to be feasible. I think much of the other problems have been addressed or at least mitigated to some degree, but that primary one is still the thorn that keeps it largely on paper.
People who promise us unicorns as solutions for current engineering issues? I am completely within my rights to call them fanbois.
And heaping liquid sodium and liquid salt reactors together as 'fourth generation' is your favourite game, and if someone takes that conflation and picks it apart you suddenly act all high and mighty and rational and act as if you made that distinction? Fuck off with your moving goalposts.
"I know I will be modded down for this": where's the option '-1, Asking for it'?
If you listen to the scientists at that lab they said the EBRII could not meltdown under any circumstances.
Find me a quote of any scientist claiming that meltdowns were impossible under "any circumstances". That's just obviously bullshit unless you are talking about specific conditions. It assumes no engineering flaws, no manufacturing flaws, proper maintenance, no external disasters or attacks, etc. They did some tests which the reactor passed but that isn't remotely the same thing as being safe in all conditions. Furthermore a meltdown is NOT the only failure mode of concern. There are a lot of still very serious but much more likely failure modes to worry about. Even if you eliminate meltdowns as a failure mode entirely that doesn't mean nuclear is 100% safe.
They intentionally tried to cause a meltdown and failed.
No they did not do that. They did some tests under conditions they were fairly confident the reactor would perform safely. There isn't a way in hell they would have gotten approval to actually try to create a meltdown if there was a reasonable chance of them actually achieving a meltdown.
You are overstating the risks of nuclear energy
Doesn't matter if I am or not. The insurance companies are all the evidence you need as they are the ones who have to put real money on the line. The fact that nuclear plants basically cannot get built without government guarantees and heavy safety regulation should tell you everything you need to know about how risky they are. When the people whose job it is to evaluate risk and profit from it aren't enthusiastic without government backing then that's a pretty reliable sign of something with serious safety concerns. That's not to say nuclear power isn't worth the risk but pretending there aren't very serious and real risks to it is dumb.
It cannot meltdown. They proved it. The reactor was designed to have a negative thermal coefficient of reactivity making meltdowns impossible.
No they did not prove it for all conceivable circumstances. They proved it for SOME conditions and methods with a specific reactor design. Your argument assumes that there is no chance of that reactor design being incorrectly engineered, no chance of improper construction or maintenance, no chance of external damage (natural disasters, war, etc), and that in all other ways the reactor cannot be compromised to induce that failure mode. And even if a meltdown were indeed impossible that's not the only possible failure of concern.
They did two tests with EBRII which tested the passive fail safe systems. They tested shutting off the primary cooling pumps and then they tested shutting down the secondary cooling systems. They did not test failure modes like the sodium pool being compromised for example. They did not test under conditions where there might be a flaw in construction. They did not test for conditions where maintenance was neglected.
Comparing Chernobyl to the EBRII or any western reactor is disingenuous.
No it is not. Chernobyl happened fundamentally because of human error (bad engineering + bad operation) which is a problem for EVERY nuclear plant design we have - even the theoretical ones. While the exact circumstance that resulted in that particular catastrophe are unlikely to be replicated closely, human stupidity and human failures have not been eliminated as risks. Claiming that EBRII was perfectly safe under all conditions is just an absurd claim without supporting evidence. Yes it appears to have been a solid design in many ways that mitigated serious failure modes under important conditions. There has been follow on designs based on what was learned from that reactor. That's a good thing and I'm glad such work is being done. But please stop it with the claims that people couldn't find a way (intentionally or unintentionally) to induce a serious catastrophic failure.