In the late 1960s, Oak Ridge National Labs in the USA built and operated a 7.5 MW thermal molten salt reactor. During 1968, it operated 75% of the time and generated 41,000 megawatt hours of heat. The film below was produced in 1969 by Oak Ridge National Laboratory for the United States Atomic Energy Commission to inform the public regarding the history, technology, and milestones of the Molten Salt Reactor Experiment (MSRE). Oak Ridge National Laboratory’s Molten Salt Reactor Experiment was designed to assess the viability of liquid fuel reactor technologies for use in commercial power generation. It operated from January 1965 through December 1969, logging more than 13,000 hours at full power during its four-year run.
Nextbigfuture has reviewed a few of the most promising Molten Salt Fission nuclear projects.
They have the potential to lower the cost of nuclear energy and creating a power source with virtually no downsides.
Nextbigfuture describes how close we are to perfect nuclear energy.
A modern tutorial on Molten Salt Reactor technology is in this video.
China has just completed a 2 megawatt thermal molten salt reactor and this is part of larger program to develop commercial molten salt reactors.
Kirk Sorenson runs one of the Molten salt nuclear companies and describes the space of technical and scientific tradeoffs for new molten salt nuclear reactors.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
Known for identifying cutting edge technologies, he is currently a Co-Founder of a startup and fundraiser for high potential early-stage companies. He is the Head of Research for Allocations for deep technology investments and an Angel Investor at Space Angels.
A frequent speaker at corporations, he has been a TEDx speaker, a Singularity University speaker and guest at numerous interviews for radio and podcasts. He is open to public speaking and advising engagements.
30 thoughts on “Past and Future of Molten Salt Reactors”
Quaise or Altarock may make nuclear reactors obsolete anyway. GW sized power plants using holes drilled right where we already have infrastructure like power lines and turbines. Holes producing power for a century or more. Anywhere in the world.
If the test site works out we should Elon Musk this technology, fast track the first few sites by streamlining regulatory hurdles and/or subsidise them the way we have for nuclear power plants.
If there was ever a time to have a Manhattan project style effort to build MSRs, now would be the time. Europe could become completely energy independent in 5 years.
Every design has it’s place and time. Quite frankly looking at the almost “not really doing much in a practical sense time” since the 60’s with the molten Salt reactor, I doubt that there is anything practical coming any time soon.
5 years, I am sorry but this is no practical timeline for the vast majority of PowerPlant designs including conventional ones, unless you are China, and even then.
From a geopolitical point of view the idea for Europe is to switch energy dependency from Russia to the US and others, not to make it autarkic! After all Europe imports all nuclear fuel from outside Europe.
Any system that can turn into a rock if it cools below several hundred degrees presents significant operational and maintenance issues, particularly in systems consisting of components/valves/piping well removed from the core. Not that unusual to end up being forced to cutout and replace the system parts because cannot fully turn all the material back into a liquid.
Dealing with highly radioactive material (solid slugs, fluids, systems) is a major maintenance headache that is further greatly complicated by Nuclear Regulatory Commission regulations.
I think the developers of these technologies do not fully appreciate the difficulties of dealing with radiation from a power plant perspective. The problem is particularly acute if the liquid is intensely radioactive liquid nuclear fuel.
After 50 years, a commercially successful SCO2 power plant remains elusive. Using liquid fuel that can turn into a rock really complicates heat exchanger designs. Not so sure an SCO2 system with the claimed efficiency is realistically achievable at the article’s 700 C temperatures and is further questionable when considering the practical efficiency of heat exchangers (including compact designs).
Ultimately, are all the MSR problems worth the headaches (including questionable profitability)? Seems very unlikely from my perspective.
You can design the lines to be heated electrically prior to start-up. Industry does it all of the time with processes that pump molten materials through pipes.
There’s always an answer, right? Someone cites an impractical difficulty and another suggests a seemingly reasonable solution, and you get into the complex reality where lube oil pumps have lube oil pumps and diverse electrical supplies and coolers in rooms with chillers. Welcome to the nuke plant!
Pretty sure there are few to none heat tracing applications at 500C that would be needed for FLiBe. The saltpeter “solar salt” is kept at like 300C by burning natural gas overnight at solar-thermal power stations. Years ago I accidentally melted KNO3 in a mason jar in my microwave in an attempt to drive off moisture – brought it to a dull red glow – maybe you could just wave-guide microwaves into the reactor – that’ll work. See, we got a new subsystem for the reactor that started as the most mechanically simple configuration imaginable (a bucket) moments ago!
There are so many issues with fluoride fuel salts including chemical [in]stability. When oxide sits in storage, it stays oxide. When fluoride sits in storage, it gives off UF6 and F2 through processes involving radiolysis. The both UO2 and UF4 are hypostoichiometric – difference is that UO2 grabs oxygen from water and becomes yellow cake U3O8 whereas UF4 grabs whatever fluorine freed by radiolysis and becomes UF6 gas which into the headspace of the container. If the fuel salt is thorium bearing, this UF6 would have some rather high fissile fraction (233U).
There are lots of details the MSR folks address with hand waving and credential posturing. Another instance where ‘trust the experts’ can only happen if you find the experts, yet most experts aren’t as loud as Kirk. Fans go shopping for experts – whoever produces a watchable enthusiastic YouTube experience. For all his white shirt and necktie, Kirk got his MSNE in 2014 and still shows his internships as employment history on LinkedIn. Kirk certainly does possess esoteric knowledge in his realm, as do many hobbyists (I know the pinouts on a LS1 v8 ECU). It is admirable that Kirk has managed to monetize his efforts and obtain investments and grants; I would have ethical issues campaigning and carrying-on as he does for this technology. I imagine he wouldn’t be particularly useful in an actual nuclear fuels outfit due to megalomania. He compared himself to Elon in one interaction I had with him. At least he’s politically conservative – except when it comes to DOE funding.
Kirk will get his funding mostly because China is funding MSRs. Cold war parity thinking.
In the meantime NuScale will move forward.
These things can’t be run to failure – they need inspection just to see if they need maintenance. A steam generator tube rupture is a big enough failure to lose/suspend the operating license at a LWR (evidence of an organizational failure to maintain the equipment). Imagine snaking sensitive electronics through salt-encrusted tubes in a 10x lethal dose field, while maintaining an inerted atmosphere (humidity yields HF), and a hundred other maintenance details (inspecting any wetted structure/surface) no fanboi imagines (because the reactor is a black box to the fanboi). Plan/design the inspection methods/tools to accompany the powerpoint reactor and watch overnight costs increase to moonshot scale, as the initially assumed bucket of slop becomes a reliable machine that is safe to operate and maintain. You don’t have to take my word for it – look around and see how many have been built. You’re a youngish kiwi – we’ll watch this not happen together over the next 30 years.
The main reason those were not built was the production of plutonium for bombs.
Scary has written his explanation somewhat cyptically and without details, because he’s gone into extensive detail in previous threads.
But there is enough there to work out what he is on about when it comes to major issues with MSRs.
The line about nuclear bombs is a cool throw away line about the initial motivations back in the 1940s, but the issue is far more complicated than a cool throw away line can sum up.
I don’t know. Today’s LWRs & BWRs DO produce lots of plutonium (for bombs), so it is quite possible that they were chosen for this reason.
I think that was more the U235 vs thorium choice, than the water reactor vs salt reactor choice. Thorium reactors produce U233, but also produce a bit of U232, which was considered a problem for bomb purposes.
For a bom you need a cor that is over 90% plutonium 239. Any reactor that produces power does not create pure Pu 239. Instead power reactors produce a mix of Pu 239, 240, 241 and other elements. like americium. You cannot make a bomb with this mix of materials. And we cannot separate this mix to extract pure 239. So the plutonium made by most reactors is can only be used to produce power. They don’t make the pure plutonium 239 needed to make a box.
I order to make pure Pu239 the uranium needs tp be put into the reactor and removed a couple of days later. This creates a very small amount of plutonium 239 without minimal Pu240, 241 and other elements. The plutonium can then be chemically separated out leaving you with over 90% 239 with much lower levels of Pu240,241.
So to make bom grade Plutonium you need a reactor specifically designed to allow rapid replacement of of the uranium fuel. And it is properferable to have a reactor that has a slow nuclear reaction rate. A reaction rate too slow to produce usable electric power.
Commercial LWRs produce Pu for bombs? News to me. AFAIK up to 40% of that reactor grade Pu isn’t fissile (even Atomic number).
I would have liked to see the plutonium dangers mentioned in the first video. Video had great facts but seemed to breeze past the uncomfortable issue of plutonium theft, nuclear terrorism and blackmail as is happening in Ukraine;
reactor defense and hardening against missiles, jetliners, and mortars/rpgs.
Also walk-away safe wasn’t clear to me. If the reactor shuts down you walk away, but if it SCRAMs, from operating level power,and if there is no water pump power and generators, a la Fukushima, doesn’t that risk/cause melt down in most UtIlity PWRs and BWRs?
So I can’t tell which of these new reactors are really passively safe, if that’s what it means safe shutdown from SCRAM w/o external pumps or gens.
Again I’m ignorant sorry if I get things mixed up.
But I can’t tellwhats reliably safe, nor what the costs are going to be, or how the waste can be really safely stored, or reprocessed.
Re costs, i read new PWR estimates of LCOE of 8, 15, and even 20 cents/KWH, for baseload power only I think since the reactor life is shortened by thermal cycling?
And it is worrisome that the LCOE In the US has been steadily increasing for years, unlike most competing technologies; suggesting maybe that past US reactors weren’t designed with enough redundancy and weld inspection and containment hardening, or other?
Will advanced reactors show a normal learning curve?
And I think US reactors and waste are enormously subsidized with huge risks on accident liability, and waste solution, dumped onto ordinary citizens. Plus subsidies for financing
and power production? Solar and wind subsidized too but can’t see it being a level field.
Thanks for all the research.
These units are mild and simple especially compared to large Steam Uranium complex systems. Use much lower levels of radio activity materials. So the scary stuff is a hype.
When the heat transfer medium, moderator, shielding and working fluid is the most abundant, inert, nontoxic, transparent liquid substance in the biosphere (water), maintenance can be performed with eyes/cameras, tools on poles… components can be flooded and drained with minimal decontamination. Everybody always thinks this equation is only driven by overnight construction costs, but operational and dose challenges will kill a design quicker than the Thorium MOX fueled Ft. Saint Vrain. In the real world, at clean LWRs, there is a dose budget that simply couldn’t be managed without disposable Tesla Bots at an MSR bigger and more complex than 5MWt lab scale.
Fort St Vrain failed mainly because of water contamination. Steam or hydrogen explosions happened at Chernobyl and Fukushima, and threatened at Three Mile Island. Light, and heavy, water tech is great – makes British gas- and Russian sodium-cooled reactors look like a dead end – but it’s still valuable to try alternatives. If western countries could build an EPR or an AP1000 as fast as the Chinese do Hualongs, nobody would have any argument against them.
These things can’t be run to failure – they need inspection just to see if they need maintenance. A steam generator tube rupture is a big enough failure to lose/suspend the operating license at a LWR (evidence of an organizational failure to maintain the equipment). Imagine snaking sensitive electronics through salt-encrusted tubes in a 10x lethal dose field, while maintaining an inerted atmosphere (humidity yields HF), and a hundred other maintenance details (inspecting any wetted structure/surface) no fanboi imagines (because the reactor is a black box to the fanboi). Plan/design the inspection methods/tools to accompany the powerpoint reactor and watch overnight costs increase to moonshot scale, as the initially assumed bucket of slop becomes a reliable machine that is safe to operate and maintain. You don’t have to take my word for it – look around and see how many have been built. You’re a youngish man – we’ll watch this not happen together over the next 30 years.
“If western countries could build an EPR or an AP1000 as fast as the Chinese do Hualongs, nobody would have any argument against them.”
The recent inflationary climate bill (now law) has a provision to provide a $15/MWh to nuclear generators in the USA starting in 2024. This will replace the $10/MWh state (read: ratepayer) subsidy that keeps my units online for green feels. Takeaway: long paid-off nukes are not competitive with fossil plants. That is an “argument against them”.
Natural gas prices in the US are running 3-4x higher than historical norms. Its a good time to produce fossil fuels and to ship them to Europe.
Also a good time to build new nuclear outside of the US. Inside the US? Maybe just to provide reliable, clean baseload and to charge EVs at night.
Tell me more about charging cars.
The problem with using heated water is the pressurized steam.
Water is actually quite dangerous in a reactor, because it needs to be handled under high (ie explosive) pressure. Plus at high enough temperatures it breaks up into its constituent hydrogen & oxygen (an explosive mixture). Low pressure operation of the radioactive loops is a BIG selling point of MSRs.
I’ve been pretty interested in pursuing molten salt reactors for a few interesting and important reasons. Having said that, while Kirk Sorenson makes it seem like they are a silver bullet, they have a number of problems that will be difficult to overcome.
1. Like this article suggests, the one they experimented with only operated 3/4ths of the time. Is this because a liquid reactor core is not as consistent? I heard a top physicist dismiss MSRs because of this very reason.
2. The coating of the reactor vessel will have to withstand high temperatures for a LONG time. We’re talking, a decade or more at a stretch, I think.
3. Nuclear scientists are pretty comfortable with solid cores, but with a liquid medium, even they get squeamish.
4. MSRs will be MORE radioactive than our current reactors, requiring more shielding, not to mention that it’s a liquid, so I’m guessing harder to work with if you need to in the first place. Add the higher radioactivity, and it sounds like a nightmare.
Aside from those concerns, the prospects are still tantalizing.
1. They can burn through close to 100 percent of the fuel, rather than 3 percent.
2. Thorium is more abundant, and can power the world for billions of years, according to Kirk Sorenson.
3. Dimethyl Ether production, due to high operating temperatures, need I say more? Civilization runs in large part off of diesel fuel, and this would be a DIRECT replacement.
4. Water desalination, again, possible because of high operating temperatures. Is there another way to avoid upcoming water shortages, and ultimately, water wars?
5. Will it ultimately provide cheap enough electricity to run fusion torches off of them? This sure sounds esoteric, but I don’t think it actually is. Many materials can only travel one way through our economy, because you can’t recycle them back to their pure elemental form, at least, without using a fusion torch. We have known the technology behind fusion torches for DECADES, we have only needed a cheap enough source of electricity to run them.
6. Will it ultimately provide enough (cheap) energy to clean up the environment? If you actually took a look at a simple Youtube video, say, of Nigeria, for example, you would instantly understand how much energy it is going to take to reverse the damage we have ALREADY caused to the environment.
7. Walk-away safe
But ultimately, regardless of the prospects, MSRs can’t be implemented fast enough to stop climate change. On top of that, we don’t have the capacity to do it, either. Plus, whatever your opinion on MSRs, the public can’t be convinced in their favor in any case.
However, I’m just an armchair enthusiast. Any of you are welcome to correct me.
1. MSRE 75% capacity factor likely because it was an experiment; 75% is quite high for an experiment.
2. Yeah coatings – or graphite tiles.
3. Nuclear scientists have no problem with whatever liquid/solid/gas core because they work with fortran and spreadsheets. Operations/maintenance is historically an afterthought – see Rickover’s paper reactor essay.
4. The total radioactive material content in MSR may be more or less than current reactors depending on stuff. Yes, forfeiting the first two fission product barriers to release (1-pellet, 2-cladding) is wildly impractical with regards to maintenance, dose and environmental release.
1. Fuel cycle white papers are fun to read – they describe what theoretically could be accomplished in the limit where figures of merit go to infinity. These papers are great for conferences. If including the 10:1 feed to product ratio for each 5% enrichment the 3-6% fuel utilization of LWR actually becomes 0.3-0.6%. The 0.7 fuel atoms bred in LWR for each atom consumed is often omitted from the math when framing LWR as antiquated.
2. Thorium is very abundant and lacks the hexavalent state. Separation of the uranium vector (1.5% 232U and 98.5% 233U) from Th MOX is trivial upon conversion to fluoride. The thorium remains solid ThF4 and the uranium wafts out of the mixture as UF6 at room temperature.
3. Synthetic fuels? Go for it. Sounds great. Do a pilot demonstration with RF heating.
4. Desalination? High temperature isn’t necessary. Is done on industrial scale in arid areas using various methods including multi-stage flash distillation.
5. Pyrolysis is a great idea for some of our waste streams – nuclear energy isn’t quite cheap.
6. Clean the environment? Ur consuming too much youtube.
7. Walk-away safe? Marketing speak runs the gamut from fantastic unsupported assertions about paper objects (Sorenson) to absolute fiction.
We will soon begin to hear about Uranium shortages. Switching to Thorium could extend the current uranium stockpile and burn a lot of hazardous waste in the process.
Why would we run out of uranium ? We have less and less reactors burning the existing stockpiles. The problem is the reactor costs, not the fuel availability. At this point uranium could be free and building a new nuclear plant is still a lowing enterprise
I would wait for a few years after China publishes the research results. Only then we can judge how cost effective an MSR reactor would be.
Yes I agree that we should wait. When we do get information we should extremely scrutinize the report as iam certain it will be doctored to look as though all is good.
Comments are closed.