Why China Is Building a Thorium Molten-Salt Reactor

Months after satellites picked up a massive nuclear fusion facility in China's Sichuan province, the country's nuclear industry has blown the lid off fission tech.

During a private meeting earlier this month, researchers at the Chinese Academy of Sciences revealed the successful operation of a thorium-powered nuclear reactor located in the Gobi Desert. The team had achieved "full-power operation" last June, according to South China Morning Post, and recently succeeded in reloading the reactor while it was powered up — a world first.

It's a major milestone for nuclear power. Thorium offers a more accessible but less weaponizable alternative to uranium, according to the World Nuclear Association, which notes that "thorium-based power reactor fuels would be a poor source for fissile material usable in the illicit manufacture of an explosive device."
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futurism.com

China Fires Up World's First Thorium-Powered Nuclear Reactor

Researchers at the Chinese Academy of Sciences revealed the successful refueling of an operational Thorium-powered nuclear reactor.
futurism.com futurism.com
 
Because:

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After all, molten salt reactors, of any sort, have worked so well in the past...
 
I'll wait. If it succeeds, news will be blaring horns. If not, a couple articles on how certain milestones were achieved... and then the immediate program fade into oblivion.
 
A quick search online finds some very recent research which shows promising concepts for managing the material degradation that plagues the technology.

Ultimately, I suspect the success of MSRs will depend on whether the prime goal is to generate low Carbon power or breed fissile weapons grade material, and what the politics of the host nation are.
 
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edwest4 said:
Mister Gardner,

Have you studied the reactors that have used thorium?
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Yes. Molten salt reactors using whatever combination are bad news in terms of maintenance and safety. Thorium breeder reactors aren't a bad idea. Molten salt reactors are.

The specific one here, using thorium fluoride, isn't something new. The US experimented with this system back as far as the 60's. While the articles above don't mention it, it's likely that this reactor uses a graphite moderator, just another potential disaster waiting to happen. It doesn't help that the resulting fissile material can be used in nuclear weapons either.

There's a lot of downsides to this.
 
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Thank you for your reply.

Thorium - World Nuclear Association

Thorium is more abundant in nature than uranium. It is fertile rather than fissile, and can be used in conjunction with fissile material as nuclear fuel. The use of thorium as a new primary energy source has been a tantalizing prospect for many years.
world-nuclear.org
 
edwest4 said:
Thank you for your reply.

Thorium - World Nuclear Association

Thorium is more abundant in nature than uranium. It is fertile rather than fissile, and can be used in conjunction with fissile material as nuclear fuel. The use of thorium as a new primary energy source has been a tantalizing prospect for many years.
world-nuclear.org
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Yes, it is. About 4 to 5 times the amount of uranium. Building a thorium breeder reactor is a good idea, but I'm leery of one using molten salts to do it. Molten salt reactors don't have a good reputation or history behind them.
 
T. A. Gardner said:
Yes, it is. About 4 to 5 times the amount of uranium. Building a thorium breeder reactor is a good idea, but I'm leery of one using molten salts to do it. Molten salt reactors don't have a good reputation or history behind them.
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Are you sure that you don´t confuse molten salt reactors with liquid metat reactors ?
 
T. A. Gardner said:
Yes. Molten salt reactors using whatever combination are bad news in terms of maintenance and safety. Thorium breeder reactors aren't a bad idea. Molten salt reactors are.

The specific one here, using thorium fluoride, isn't something new. The US experimented with this system back as far as the 60's. While the articles above don't mention it, it's likely that this reactor uses a graphite moderator, just another potential disaster waiting to happen. It doesn't help that the resulting fissile material can be used in nuclear weapons either.

There's a lot of downsides to this.
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This is nonsense, molten Salt is allready in long term use in solar power plants and despite those are not commercially succsessfull, they prooved that molten salts are not critically for maintenance. These reactors are extremely save, even a total lack of cooling would not have any dangerous consequences, the freeze plug would melt and the molten salt would be drained, that's all. I havent seen any molten salt reactor with a graphite moderator (it might exists).

There are many different types of molten salt reactors, some (Terra power) are using the salt just for heat transfer and some use a fluid reactorfuel.

Thorium is might be about 4 to 5 times abuntant than Uranium, but so, it is 200 to 250 times more abuntant than Uranium 235. Only 2 % of the Uranium can be used in conventional light water reactors and only about 7 % of the 2 % are actually burned. With a closed fuel cycle (burning virtually all the Thorium) the supply is around 3000 x higher compared to U235.

Thorium reactors produce almost no transuranic waste and molten salt reactors can even transmutate the waste of current light water reactors.
 
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The issue is the corrosiveness combined with radiation. The molten salt causes grain boundary erosion, and the radiation then causes the cracks generated by the erosion to propagate at an accelerated rate. Individually they are manageable, combined they're enough of a problem that research into appropriate materials is ongoing.
 
Corrosion only apears when oxygen is present and even than, the oxygen will be eaten up when coroding metal.. Andasol in Spain is using the same type of (hot) salt which is proposed for most SMR.

Salt bath are also quite common for heat treatments of metal which should be much more problematic because of open tops, inpurities and comparable or even higher temperatures.
 
How soluble the atoms of metals within a given alloy are into the molten salt mixture is a significant factor in the rate of corrosion.

Really good article here
 
Intrestingly, radiation reduces the corrosion significantly (by a factor of 2-3). This artikle is quite promising, a MSR should have a longer operation time than Andasol. Despite that, Thorcon plans to exchange the reactor every ten years and to reuse the filling (after adding fresh Thorium) for the next reactor.

One should keep in mind, that the molten salt is not pressurized, so even if there would be cracks through th wall, it would simply cause the salt to drain out, cool down and the reaction would stop. All the fission material will be inclosed in a block of solid salt.
 
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Nicknick said:
Intrestingly, radiation reduces the corrosion significantly (by a factor of 2-3). This artikle is quite promising, a MSR should have a longer operation time than Andasol. Despite that, Thorcon plans to exchange the reactor every ten years and to reuse the filling (after adding fresh Thorium) for the next reactor.

One should keep in mind, that the molten salt is not pressurized, so even if there would be cracks through th wall, it would simply cause the salt to drain out, cool down and the reaction wild stop. All the fission material will be inclosed in a block of solid salt.
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The problem is you end up with everything involving this reactor being highly radioactive. The salts, the core, the plumbing, etc. This greatly increases the amount of 'stuff' that you have to deal with that's radioactive.
 
T. A. Gardner said:
The problem is you end up with everything involving this reactor being highly radioactive. The salts, the core, the plumbing, etc. This greatly increases the amount of 'stuff' that you have to deal with that's radioactive.
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The same holds true for conventional reactors. After spending billions, no safe way to store nuclear waste underground has been found. I was surprised to see video on TV of nuclear waste in 55 gallon drums being dropped into the ocean. I have also heard that abandoned mines are being considered.
 
edwest4 said:
The same holds true for conventional reactors. After spending billions, no safe way to store nuclear waste underground has been found. I was surprised to see video on TV of nuclear waste in 55 gallon drums being dropped into the ocean. I have also heard that abandoned mines are being considered.
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The promise with molten salt reactors is that neutron poisons like xenon bubble out, and If you're running the thing as a breeder/fast spectrum reactor you can burn many of the others in situ.

Fuel waste becomes pretty much a non issue.
 
edwest4 said:
The same holds true for conventional reactors. After spending billions, no safe way to store nuclear waste underground has been found. I was surprised to see video on TV of nuclear waste in 55 gallon drums being dropped into the ocean. I have also heard that abandoned mines are being considered.
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Yucca Mountain was a safe repository. The material was put in casks that were pretty close to indestructible. Aside from that, the waste is mostly long-life alpha emitters which aren't that big a safety hazard. Reprocessing is possible and should be done in any case. Water as coolant isn't a big issue on its own as it loses any added radioactivity in a matter of weeks.
 
Pixelbrick said:
The promise with molten salt reactors is that neutron poisons like xenon bubble out, and If you're running the thing as a breeder/fast spectrum reactor you can burn many of the others in situ.

Fuel waste becomes pretty much a non issue.
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On the other hand, the salts are often corrosive and always highly toxic aside from being radioactive.
 
T. A. Gardner said:
The problem is you end up with everything involving this reactor being highly radioactive. The salts, the core, the plumbing, etc. This greatly increases the amount of 'stuff' that you have to deal with that's radioactive.
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The used fuel of conventional reactors is a much higher mass of nuclear waste than the scrapp metal of the reactor. In standart light water reactors, only 5 % of the Uran (U235) contributes significantly to the power production whereas the remaining 95 % (U238) are responsible for almost all of the really nasty stuff (transuranic elements) which are very dangerous and very long lasting. In a fast Thorium reactor, all of the Thorium can be split as well as other heavy elements, therefor the amount of long lasting heavy elements is very small (or even negative, if nuclear waste is burned as fuel. The radioactive waster of a MSR is therefore less dangerous, short lived and can partially be recycled. It even can be negative, if nuclear waste from conventional reactors is used as fuel.

A fast MSR doesn't need any refuelling within 10 years and after that period, the content can be freshed up with new Thorium and the removal of the fission products for a new reactor, so that the amount of waste is extremely small.

BTW, the plumbing gets always slightly radioactive, but the amount of radioactivity is way smaller than that of the waste fuel!
 
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Nicknick said:
Canada: hold my beer....

(We Candu that too...)
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Yes at Point Lepreau

en.wikipedia.org

Point Lepreau Nuclear Generating Station - Wikipedia

en.wikipedia.org en.wikipedia.org

not sure if the plan to use thorium but it is a molten salt reactor.

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True, but initially I ment the ability to refuel a running fission reactor (like it was emphasist in the title). This can be done in Candu reactors as well, which makes them well suited for producing weapon grade Plutonium....

I think, Candu designs could potentially also run with Thorium, but Im not totally sure about that.
 
T. A. Gardner said:
Those too are dangerous. The liquid metal ones are more like OMG! dangerous.
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besides that liquid Natrium isnt as dangerous as it sounds, there are other metalls which can be used. The Russian Brest od300 reactor uses liquid led, please explain what is especially dangerous of liquid led? (Other than drinking it.. )
 
T. A. Gardner said:
Yucca Mountain was a safe repository. The material was put in casks that were pretty close to indestructible. Aside from that, the waste is mostly long-life alpha emitters which aren't that big a safety hazard. Reprocessing is possible and should be done in any case. Water as coolant isn't a big issue on its own as it loses any added radioactivity in a matter of weeks.
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You mean minutes.



Nicknick said:
besides that liquid Natrium isnt as dangerous as it sounds, there are other metalls which can be used.
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Molten sodium has a bad habit of meeting water in the steam generators. Which is why the USN ripped the entire Sodium-cooled reactor out of SSN575 Seawolf at the first refueling overhaul.


Nicknick said:
The Russian Brest od300 reactor uses liquid led, please explain what is especially dangerous of liquid led? (Other than drinking it.. )
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The fact that you must keep the lead molten at all times, so you're constantly at 508degF or whatever even when trying to do maintenance.

You can't just shut down the reactor and then let it cool down to room temperature over a couple days/weeks like with a water-cooled reactor.
 
Im sure you can drain the led out of the reactor. The decay heat will keep it hot for long time anyway, even after a shutdown. Unlike in a pwr, you dont reley on a cooling systems for the decay heat, which is a hughe advantage. Even if the lead would become solid, it wouldnt be a safety hazzard, it would just damage the internals of the reactor.


The Russians have long time expiriences with Sodium cooled reactors. In the beginning they indeed had some small fires (in secondary cooling loops) which turned out to be easy controlable. Of course, things would be different in a cramped submarine. Terrapower will eliminate the fire risk of their sodium fast reactor by using molten salt in the secondary cooling circuit. Molten salts dont react intensly with water or sodium, so that leaks will be less critically. Molten salts enable also heat storage and a flexible electricity production, which is another bid advantage.
 
Nicknick said:
Im sure you can drain the led out of the reactor.
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Then you have to refill it at some point, which is not particularly safe.


Nicknick said:
The decay heat will keep it hot for long time anyway, even after a shutdown. Unlike in a pwr, you dont reley on a cooling systems for the decay heat, which is a hughe advantage.
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That is a massive maintenance DISADVANTAGE.



Nicknick said:
Even if the lead would become solid, it wouldnt be a safety hazzard, it would just damage the internals of the reactor.
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If a molten-metal reactor solidifies, you have to scrap the entire thing.


Nicknick said:
The Russians have long time expiriences with Sodium cooled reactors. In the beginning they indeed had some small fires (in secondary cooling loops) which turned out to be easy controlable. Of course, things would be different in a cramped submarine. Terrapower will eliminate the fire risk of their sodium fast reactor by using molten salt in the secondary cooling circuit. Molten salts dont react intensly with water or sodium, so that leaks will be less critically. Molten salts enable also heat storage and a flexible electricity production, which is another bid advantage.
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You're not getting anywhere near the temperature or pressure drop through the turbines with molten salts as with water. There's a reason both the US and USSR used water for the secondary loops. (Ignoring the dumbasses with boiling water and turbines in the primary loop)
 
The experimental US molten salt reactor was shut down every Friday by switching of the cooling. By doing so, the freeze plug melted and the salt drained out of the reactor, only to be refilled on Monday, must have been a convinient process...

Maintaining a reactor vessel on the inside is something I never heard off and I doubt that this is normally done ever!

All Sodium reactors I have ever heard off, used Sodium in the primary and secondary loop with water (of course) in the turbine loop. Bill Gates with Terrapower will use molten salt in the secondary loop, for safety reasons as well as for heat atorage and flexibel electricity production.
 
Scott Kenny said:
You mean minutes.
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Two weeks is considered the normal time for all the radioactives except a few long-lived low decay rate ones to go away.
Scott Kenny said:
Molten sodium has a bad habit of meeting water in the steam generators. Which is why the USN ripped the entire Sodium-cooled reactor out of SSN575 Seawolf at the first refueling overhaul.
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Use of a material that is solid at 'room' temperature is a problem regardless. You have this mass of radioactive material to deal with. Depending on what you are using, it could stay highly radioactive for years and is difficult to reprocess. Water, with just hydrogen and oxygen for all intents, is far more easily managed.
Scott Kenny said:
The fact that you must keep the lead molten at all times, so you're constantly at 508degF or whatever even when trying to do maintenance.

You can't just shut down the reactor and then let it cool down to room temperature over a couple days/weeks like with a water-cooled reactor.
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If the reactor has to stay at 508 F all the time, THAT is a HUGE problem. Even shutdown, you'll need to be adding energy from somewhere because decay heat alone won't keep things that hot. With a BWR or PWR you can shutdown and just circulate the cooling water using the pumps until you reach a temperature below boiling. Once you're there you just monitor the water in the reactor itself and use a circ pump occasionally if it rises too much.

The other advantage is it is unpressurized at that point. If you are at 500+ degrees, then there's pressure on the system as well. Another issue to deal with.

Exotic materials create exotic problems. While these may be some engineering wet dream in efficiency or whatever, the problems that come with them aren't worth the small increases in efficiency derived.
 

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