Making Safe Nuclear Power from Thorium

[Dan Warnick + 6,100]

I was watching some TEDx Talks videos and came across this title from 2015:  Making Safe Nuclear Power from Thorium

I remember Jan talking briefly on several other discussions/threads about it, but I didn't know what it was.

So, @Jan van Eck, here's your launch point!  Please bring us up to speed.

[Jan van Eck + 7,558]

17 hours ago, Dan Warnick said:

I was watching some TEDx Talks videos and came across this title from 2015:  Making Safe Nuclear Power from Thorium

I remember Jan talking briefly on several other discussions/threads about it, but I didn't know what it was.

So, @Jan van Eck, here's your launch point!  Please bring us up to speed.

Dan, from a technical standpoint, everything this fellow says in the video is exactly correct.  No errors.

From a political standpoint, everything he says is exactly correct.  No errors. 

The molten-salt reactor, as currently devised, can sit in a container on a flat-bed semi truck, be hauled to a factory, and just sit there, producing 40 MW, and run in walk-away mode with zero risk.  It does not require any of the paraphernalia you associate with reactors:  containment domes, back-up pumps, water dump systems, extra generators, all that stuff is history. 

You can burn up all the old waste lying around and not have to concern yourself further with Yucca Mountain.

What stops this technology is people.  Specifically, the Greenies, and the politicians that cater to them. 

Edited September 11, 2018 by Jan van Eck
typing error

[Dan Warnick + 6,100]

4 minutes ago, Jan van Eck said:

Dan, from a technical standpoint, everything this fellow says in the video is exactly correct.  No errors.

For a political standpoint, everything he says is exactly correct.  No errors. 

the molten-salt reactor, as currently devised, can sit in a container on a flat-bed semi truck, be hauled to a factory, and just sit there, producing 40 MW, and run in walk-away mode with zero risk.  It does not require any of the paraphernalia you associate with reactors:  containment domes, back-up pumps, water dump systems, extra generators, all that stuff is history. 

You can burn up all the old waste lying around and not have to concern yourself further with Yucca Mountain.

What stops this technology is people.  Specifically, the Greenies, and the politicians that cater to them. 

Excellent!  I suppose big oil and a few others are also interested in stopping it?

Do you know if there is some sort of worldwide effort going on to inform the general public?  I had never heard of it before you mentioned it.

[Jan van Eck + 7,558]

13 minutes ago, Dan Warnick said:

Excellent!  I suppose big oil and a few others are also interested in stopping it?

Do you know if there is some sort of worldwide effort going on to inform the general public?  I had never heard of it before you mentioned it.

There is no effort  (to publish it).

There is no effort (to stop it, no plot from Big Oil, if that is what you mean). 

One of the leading engineers in Thorium generators lives down the road from me, we do correspond a bit on the Internet,  the big barrier is the politicians, who don't want to hear of it, mostly because it includes the word "nuclear" and the Greenies go into these hysterics over that.  Unfortunately, people who are technically illiterate will dominate over people who know what they are doing.  That is mostly because people who know what they are doing are not going to go hang themselves by ropes from bridges to stop shipping traffic, are not going to sabotage oil drilling rigs, are not going to form human chains across nuke construction sites, and are not going to demand that politicians instruct contractors to spend vast billions on ridiculous hardware to cure non-existent "threats" that only the mentally challenged can conjure up.  It is what it is. 

[Rodent + 1,424]

"Fossil fuels also create other problems, like wars and conflicts around the world, and that results in migration and refugees and hardship for a lot of people who didn't get a lot of benefit from those fossil fuels in the first place."

Fossil fuels create energy. 

[Jan van Eck + 7,558]

2 hours ago, Rodent said:

 

Fossil fuels create energy. 

Rodi, is that you in the cowgirl hat peeking from behind Cruella?

[Epic + 390]

I like this idea.  If I was president, I'd want to make as many of these things as we can.  But I do have one question:

In the video, he said, "If someone tries to fiddle with the reactor in ways that they shouldn't, then these reactors are capable of letting the world know about it before things get out of hand."

What exactly does he mean here?  If this reactor is a park-and-walk-away reactor, couldn't someone sneak in and "fiddle" with it after everyone has "walked away"?  I am not worried about the reactor messing up and forgetting to let the world know about the fiddling...what concerns me is that the people who supposed to be "listening" to make sure no one is fiddling might not actually be listening.  Worse still, what if the men doing the "fiddling" have assault riffles and shoot whoever shows up to stop them.  What I really want to know is how much time does it take from the moment the terrorists with guns show up to the time when the reactor goes full-nuclear explosion.  

I am also assuming these things would be perfectly safe in a 10 car pile-up crash that pushes the reactor over the ledge of a 100 foot drop.  

Next question: how small can these reactors be built?  Could you make one small enough to fit under a car's hood?  You could get unlimited mpg, and when your car is parked at home, you could plug it in and it could power your house.  On the other hand, if you put one of these in everyone's car, could those people "fiddle" with it in their garage (intentionally or unintentionally) and then blow up the town?  

I like low cost energy.  

I don't like nuclear accidents.  

[Jan van Eck + 7,558]

33 minutes ago, Epic said:

I like this idea.  If I was president, I'd want to make as many of these things as we can.  But I do have one question:

In the video, he said, "If someone tries to fiddle with the reactor in ways that they shouldn't, then these reactors are capable of letting the world know about it before things get out of hand."

What exactly does he mean here?  If this reactor is a park-and-walk-away reactor, couldn't someone sneak in and "fiddle" with it after everyone has "walked away"?  I am not worried about the reactor messing up and forgetting to let the world know about the fiddling...what concerns me is that the people who supposed to be "listening" to make sure no one is fiddling might not actually be listening.  Worse still, what if the men doing the "fiddling" have assault riffles and shoot whoever shows up to stop them.  What I really want to know is how much time does it take from the moment the terrorists with guns show up to the time when the reactor goes full-nuclear explosion.  

I am also assuming these things would be perfectly safe in a 10 car pile-up crash that pushes the reactor over the ledge of a 100 foot drop.  

Next question: how small can these reactors be built?  Could you make one small enough to fit under a car's hood?  You could get unlimited mpg, and when your car is parked at home, you could plug it in and it could power your house.  On the other hand, if you put one of these in everyone's car, could those people "fiddle" with it in their garage (intentionally or unintentionally) and then blow up the town?  

I like low cost energy.  

I don't like nuclear accidents.  

Sorry to bust your bubble, but a molten-salt reactor cannot be "blown up."  If it goes to over-temp because of some saboteur "fiddling," it will self-stabilize and shut itself off. The way it does that is to melt a plug in the base of the reactor section, allowing all that molten salt to dump out into some big pit, where it spreads out and loses criticality.  The reaction stops. Then the remaining heat is absorbed by the walls of the pit, all underground.  So you have this passive cooling and shut-down system that cannot be re-started, until the technicians come back on board and figure out how to scoop all that cooled salt material out of the pit, reinstall the plug, and restart.  That melted plug will leave a tell-tale that someone fiddled.  

The molten salt bath runs the reaction section and another bath of molten salt is the (low pressure) heat take-away section, and that heat is then transferred via a heat exchanger (remember the molten salt is at 800 degrees) to the generator water.  The superheated steam then can drive the generator, or be piped off for winter space heating, whatever you want lots and lots of heat for. 

The current thinking is to put the molten salt reactor into a hole in the ground.  Basically, it is all buried.  The big dump pit is underneath that. You can winch it out of there by bringing in some monster crane and hooking up a seriously hefty chain. Other than that, the guts part is where it cannot be touched.  Even if you were enterprising and brought in your terrorist crew and big crane, without first allowing the stuff to decay you would be fried by close-in radiation, so stealing the stuff is not an option.  All the terrorist thieves would be dead.  Bye-bye.  Don't try to remove reactor cores when you don't know what you are doing!

Because molten-salt units are not dependent on coolant pumps and emergency dump valves and pools, you don't have these various factors where things can, at least in theory, go wrong.  The unit simply produces power from the reactions in the core, and provides heat to the take-away pipes that then run the generator same as any other installation. It is a "no worries" design.  In short, you really cannot screw it up. 

Nuclear power is actually quite benign.  You have to get away from these ideas that it is constantly on the edge of blowing up in some spectacular explosion that is doomsday for 500 miles around.  It does not work like that, even with pressure-water reactors. After all, they put four of those on an aircraft carrier,  I think 100 MW each, never have any problems with them.  And those are the old-style units. 

You can forget about worries over collisions on the road.  Nuclear material including fuels and warheads for the Navy are moved in a very controlled environment.  Basically it is a rolling roadblock with the police escort 1/4 mile in front and 1/4 mile in back and the entrances blocked off.  Nobody gets anywhere near the "target" being escorted.  I once drove in such a caravan running a Vice President and  I can flat-out guarantee you that nobody, and I mean Nobody, is going to get past the cops. They have that all figured out. That nuke material sits in a special truck and gently rolls along at about 50 mph and stops for nothing, in a cleared, running roadblock or moving section of empty roadway. Works fine. 

I doubt if you can build a reactor smaller than about 5 MW.  That is still a big enough unit.  It is not practical for mobile applications, as you have that melt-plug fuse to dump the stuff, and dumping nuclear material out on the public roadway is not really a bright idea.  So no, you can forget about using such a reactor in your car, at least in the current level of development.  What somebody else dreams up in another 50 years, hey who knows.  I consider it implausible, but that is my personal opinion.  Remember, at one time back around 1950 some nuke engineers had figured out a reactor to power an airplane, and the reactor part they built as a prototype actually worked, although there is no record of it being installed in an aircraft.  It would have been a very big aircraft in any event, something the size of an Antonov AN-235.  Oh, well.

 

[Dan Warnick + 6,100]

6 hours ago, Jan van Eck said:

So no, you can forget about using such a reactor in your car, at least in the current level of development.  What somebody else dreams up in another 50 years, hey who knows.

Just to make a point of the fact that it can be the source of the electricity that is used to plug into a car and charge its batteries.

A couple of quick questions for those in the know about current battery development: 

1) I assume that the charging system itself is not the limiting factor with regards to the time needed to recharge a car's batteries; that the batteries themselves are the limiting factor in how fast they can accept a charge.  Is this correct, and if it is, how do developers propose getting past this hurdle?

2) Another assumption I have (problem with assumptions aside ) is that wireless charging must be going on at the same time as all the rest of this battery power development.  Where is the industry in the development of wireless car battery chargers?

It would seem that a great deal more people, myself included, would be much more enthusiastic about electric cars if you can take away the wait for a recharge and if all I had to do was park in the right spot, at home, at work and at recharge stations.

[Jan van Eck + 7,558]

4 minutes ago, Dan Warnick said:

2) Another assumption I have (problem with assumptions aside ) is that wireless charging must be going on at the same time as all the rest of this battery power development.  Where is the industry in the development of wireless car battery chargers?

It would seem that a great deal more people, myself included, would be much more enthusiastic about electric cars if you can take away the wait for a recharge and if all I had to do was park in the right spot, at home, at work and at recharge stations.

The design of the cell will control the maximum rate of charge. 

Wireless charging is well developed in Sweden for the re-charge of inter-island ferries.  You bring in a large flat plate up next to the ship's hull at a point where a big receiving coil is located, the space being about 10 cm.  Then the charge is transferred by AC, just as if you had a big transformer with coils wound in proximity. Works quite well; the Swedes now have these all-electric ferries doing relatively short runs. 

It gets harder with autos as the two plates do not get closer than whatever ground clearance is created by the tires.  That distance is greater than 10 cm. You could put a big plate under the car body and lower it down onto the ground for the transfer, but now you are making things complex, and you want to avoid that.  The closer you are, the faster the rate of energy transfer possible.

[Dan Warnick + 6,100]

5 minutes ago, Jan van Eck said:

The design of the cell will control the maximum rate of charge. 

Wireless charging is well developed in Sweden for the re-charge of inter-island ferries.  You bring in a large flat plate up next to the ship's hull at a point where a big receiving coil is located, the space being about 10 cm.  Then the charge is transferred by AC, just as if you had a big transformer with coils wound in proximity. Works quite well; the Swedes now have these all-electric ferries doing relatively short runs. 

It gets harder with autos as the two plates do not get closer than whatever ground clearance is created by the tires.  That distance is greater than 10 cm. You could put a big plate under the car body and lower it down onto the ground for the transfer, but now you are making things complex, and you want to avoid that.  The closer you are, the faster the rate of energy transfer possible.

Very interesting about the Swedish ferries.  For cars, I'm sure the ground clearance issue can be addressed "from the ground up", so that shouldn't be an issue for long, if they've not already solved it.  Thanks for sharing and elaborating.  A quick search on Google revealed BMW's current wireless recharging setup.  Impressive.

BMW Wireless Charging Car charging in 3,5 hrs without a cable

[Jan van Eck + 7,558]

6 minutes ago, Dan Warnick said:

Very interesting about the Swedish ferries.  For cars, I'm sure the ground clearance issue can be addressed "from the ground up", so that shouldn't be an issue for long, if they've not already solved it.  Thanks for sharing and elaborating.  A quick search on Google revealed BMW's current wireless recharging setup.  Impressive.

BMW Wireless Charging Car charging in 3,5 hrs without a cable

But remember that the BMW system is for the effete rich, those self-absorbed individuals who think they are too important to actually do "manual labor" of plugging in a cable.  That wireless system is "lossy," in that it is not a 100% transfer of energy.  You end up losing some of the power through the magnetic coupling system.  For those effete snobs that pay $60,000 and up for their BMW, that is not even on the radar.  What do they care about energy losses?  Nothing.  And BMW caters to this arrogance.

[Epic + 390]

10 hours ago, Jan van Eck said:

If it goes to over-temp because of some saboteur "fiddling," it will self-stabilize and shut itself off. The way it does that is to melt a plug in the base of the reactor section, allowing all that molten salt to dump out into some big pit, where it spreads out and loses criticality.

I definitely like the concept behind thorium reactors.  But here is my next question.  What happens when there is no pit?  In the future, if there are millions of these reactors in use, it is possible that over time, the elements could cause some of these pits to fail.  Maybe some of the pits get filled with floodwaters and debris. or a wall collapses after 30 years which fills the pit with dirt...I don't know, there could be many ways the pits fail.  Also, the terrorists could always dig a side hole and then pump concrete into the pit, filling it up, after which they tamper with it to cause it to over-heat.  Regardless of how it happens, the point is that if we make enough of these things (and I think we should make as many as possible), eventually one of these pits will fail.  What happens when the plug melts but that thorium doesn't drain out into the pit?  

I read that thorium is not a fissile material, and so it cannot be used to make nukes.  Does that mean that it won't explode when it goes critical?  If not, what will happen?  Will it just get really hot?  And if so, how hot and how much damage will it cause?

I am new to these reactors, but it sounds like the most dangerous aspects of them would also be the easiest to guard against.  Namely, thorium can be turned into 92U233, which could then be turned into a nuke.  So, if the terrorists happened to have a nuclear physicist lying around (unlikely, I know, but still possible), and all they need to make their own nuke is to get their hands on some thorium, and it just so happened that every town in the US has multiple thorium reactors sitting around not being watched, then that could be a problem.  Now, I am not worried about an Alek Minassian trying to get that thorium.  As you said, Jan, Alek would try to get it and then die from radiation poisoning.  I'm more worried about that nuclear physicist who has a bone to pick and is helping the terrorists to get that thorium.  He would not only know how to get that material, but he would also know how to make it into that bomb.  Still, I think the fix for this is quite simple.  Since low cost energy is so critical to national wealth, the government could subsidize the installation of thorium reactors in every city and town.  Then, after a reactor is installed, government funds could be used to build a new police station on top of it.  If the only way one can access these reactors is to first go through the police, well, that should protect them well enough.  Moreover, if the police know they have a nuclear reactor in their basement, they might even send a patrol officer down there once in a while to check to make sure the pit is clear and safe.  So, I'm not seeing any downside to these reactors. 

In fact, I want to build some of these things.  How much do they cost, anyway?  

[Jan van Eck + 7,558]

1 hour ago, Epic said:

I definitely like the concept behind thorium reactors.  But here is my next question.  What happens when there is no pit?  In the future, if there are millions of these reactors in use, it is possible that over time, the elements could cause some of these pits to fail.  Maybe some of the pits get filled with floodwaters and debris. or a wall collapses after 30 years which fills the pit with dirt...I don't know, there could be many ways the pits fail.  Also, the terrorists could always dig a side hole and then pump concrete into the pit, filling it up, after which they tamper with it to cause it to over-heat.  Regardless of how it happens, the point is that if we make enough of these things (and I think we should make as many as possible), eventually one of these pits will fail.  What happens when the plug melts but that thorium doesn't drain out into the pit?  

I read that thorium is not a fissile material, and so it cannot be used to make nukes.  Does that mean that it won't explode when it goes critical?  If not, what will happen?  Will it just get really hot?  And if so, how hot and how much damage will it cause?

I am new to these reactors, but it sounds like the most dangerous aspects of them would also be the easiest to guard against.  Namely, thorium can be turned into 92U233, which could then be turned into a nuke.  So, if the terrorists happened to have a nuclear physicist lying around (unlikely, I know, but still possible), and all they need to make their own nuke is to get their hands on some thorium, and it just so happened that every town in the US has multiple thorium reactors sitting around not being watched, then that could be a problem.  Now, I am not worried about an Alek Minassian trying to get that thorium.  As you said, Jan, Alek would try to get it and then die from radiation poisoning.  I'm more worried about that nuclear physicist who has a bone to pick and is helping the terrorists to get that thorium.  He would not only know how to get that material, but he would also know how to make it into that bomb.  Still, I think the fix for this is quite simple.  Since low cost energy is so critical to national wealth, the government could subsidize the installation of thorium reactors in every city and town.  Then, after a reactor is installed, government funds could be used to build a new police station on top of it.  If the only way one can access these reactors is to first go through the police, well, that should protect them well enough.  Moreover, if the police know they have a nuclear reactor in their basement, they might even send a patrol officer down there once in a while to check to make sure the pit is clear and safe.  So, I'm not seeing any downside to these reactors. 

In fact, I want to build some of these things.  How much do they cost, anyway?  

Chad, I was not suggesting that the "pit" be left as bare earth!  The "pit" can be made as a basement, with concrete, you could line it with steel plate, whatever you want.   the purpose of the Pit is to take the molten material which is held in a cube, for criticality, and spread it out into a large-surface layer, so that the fissile material is sufficiently removed from itself that it stops being of critical mass.  Once the reaction stops, it will passively get cold, by natural heat convection into the walls (floor) of the Pit. 

the point is that you don't need a cooling system for emergencies, with pumps, generators, all that other stuff that gets expensive fast and requires its own back-up systems.  All that is gone. 

There is material in there with a half-life of over nine days, so it takes a bit before it can be handled again.  I don't think your invading guerrilla army is going to be able to hold out against the US Marines for say three months while the fissile material gets cool enough to start handling, up close and personal.  

I think if your saboteurs are busy digging a hole to the Pit and bringing in a big cement truck to fill that Pit up, somebody is going to notice.  I suspect the logical result will be a shoot-out with the locals.  I would not bet my money on the saboteurs;  Americans are well known as being rather good shots.  And I just don't see that cement company becoming a willing participant, those big trucks cost money to replace.  

Yes, U233 can be processed into bomb material.  Is the U233 "poisoned" with other isotopes that contaminate that process?  Likely so. How do you isolate the material?  In your garage?  On some remote farm, in a barn?   I really think you are getting way ahead of yourself here.  You have to bring in some monster crane, you have to shut off the power (that should attract attention), hook up the big chain, use the crane to yank the core, put that on some truck, make the material non-critical, try to drive off with it - all in total secrecy, with no one noticing.  Does not strike me as realistic.  For all that work, might as well go break into a sub base and steal an ICBM, hey why not?

As to your last question, nobody knows the cost, as they are not in production.  Should be cheap enough.  Anticipate your retail electricity to start out at around 3 cents/kwhr.  Let it drift down from there.  Eventually, toss the meters, and flat-rate the power.  Cheers.

[Bhimsen Pachawry + 72]

On 9/10/2018 at 11:58 PM, Dan Warnick said:

I was watching some TEDx Talks videos and came across this title from 2015:  Making Safe Nuclear Power from Thorium

I remember Jan talking briefly on several other discussions/threads about it, but I didn't know what it was.

So, @Jan van Eck, here's your launch point!  Please bring us up to speed.

 

On 9/11/2018 at 12:55 AM, Jan van Eck said:

Dan, from a technical standpoint, everything this fellow says in the video is exactly correct.  No errors.

From a political standpoint, everything he says is exactly correct.  No errors. 

The molten-salt reactor, as currently devised, can sit in a container on a flat-bed semi truck, be hauled to a factory, and just sit there, producing 40 MW, and run in walk-away mode with zero risk.  It does not require any of the paraphernalia you associate with reactors:  containment domes, back-up pumps, water dump systems, extra generators, all that stuff is history. 

You can burn up all the old waste lying around and not have to concern yourself further with Yucca Mountain.

What stops this technology is people.  Specifically, the Greenies, and the politicians that cater to them. 

You two are not going to the real issue of Thorium reactors. Thorium reactors use A type of reactors called fast breeding reactor to make Thorium convert into U233. These reactors have been tried by France (check phoenix reactor), Japan, Russia, India etc and all of them have not seen grand success. Russia is the only country that has seen some success but that too is limited. The reasons are:

1. The coolant is sodium, not sodium salt or any other salt
2. Sodium is explosive when it comes in contact with air, especially molten sodium at 1000+Celsius temperature
3. Sodium is extremely reactive and can react with water or air explosively. Sodium can become a radioactive molecule itself which can hamper reaction as well as react with with fission products like Iodine
4. In case Sodium leaks, even a bit, there will not just be explosion but also solidifying of Sodium and its reacted compounds in the reactor. This means the entire reactor is now a junk
5. Replacing sodium coolant over the lifecycle is very difficult unlike that of water
6. The FBR has to be small in order for neutrons to be effectively captured. If the reactor is big (500MW+), the reaction would be difficult and breeding would be slow or impossible.

 

If you want to hold a reactor on the back of your car, you must get PWR reactor, not Sodium cooled one. The sodium cooled reactor needs large area. The safe design is that of PWR which can be made quite small and fit into submarines and trucks

[Jan van Eck + 7,558]

1 hour ago, Bhimsen Pachawry said:

 

You two are not going to the real issue of Thorium reactors. Thorium reactors use A type of reactors called fast breeding reactor to make Thorium convert into U233. These reactors have been tried by France (check phoenix reactor), Japan, Russia, India etc and all of them have not seen grand success. Russia is the only country that has seen some success but that too is limited. The reasons are:

1. The coolant is sodium, not sodium salt or any other salt
2.  

You don't have to use a breeder if you don't want to.  You can, it is a design variant, but with all the old nuclear fuel lying about, why bother?

Nobody is using sodium as a coolant any more.  It has gone to using Liquid fluoride salt in molten form, at 800 degrees.  That is a nice stable platform and works fine. 

[Dan Warnick + 6,100]

2 minutes ago, Jan van Eck said:

You don't have to use a breeder if you don't want to.  You can, it is a design variant, but with all the old nuclear fuel lying about, why bother?

Nobody is using sodium as a coolant any more.  It has gone to using Liquid fluoride salt in molten form, at 800 degrees.  That is a nice stable platform and works fine. 

I thought that is what you described in your previous posts.  I did not see anything about just sodium.

[Jan van Eck + 7,558]

1 minute ago, Dan Warnick said:

I thought that is what you described in your previous posts.  I did not see anything about just sodium.

Because of the sodium issues as respects corrosion, the thinking is to use fluoride.  Lots  of development work going in in several countries, also Canada, which has a very promising design headed for prototype.

[Dan Warnick + 6,100]

1 minute ago, Jan van Eck said:

Because of the sodium issues as respects corrosion, the thinking is to use fluoride.  Lots  of development work going in in several countries, also Canada, which has a very promising design headed for prototype.

Yes.  I'm not going to go back and watch the TEDx Talk videos, but one of them talked at length about the use of fluoride as being the breakthrough finding.

[Bhimsen Pachawry + 72]

1 hour ago, Jan van Eck said:

Because of the sodium issues as respects corrosion, the thinking is to use fluoride.  Lots  of development work going in in several countries, also Canada, which has a very promising design headed for prototype.

 

59 minutes ago, Dan Warnick said:

Yes.  I'm not going to go back and watch the TEDx Talk videos, but one of them talked at length about the use of fluoride as being the breakthrough finding.

The key word here is that it is still "developing". Fluoride is not yet practical. Sodium has melting point of 100 celsius whereas Sodium fluoride has melting point of 1000 celsius which means unless heated till about 1000 celsius, there is always a chance for it to be soldified prematurely. The cooler end of the coolant generally comes to 500 celsius for sodium coolant. Keeping the entire coolant always above 1000 celsius is a very difficult task. Coolant also needs to cool down at one end and then transfer heat from the other

Next, if you want energy by thorium, you have to breed thorium into U233. There is no other way. You can also breed U238 into Pu239 similarly to get fissile material. But, both these process require breeder reactor. Water is not used here as water absorbs neutrons and slows down breeding. 

[Sebastian Meana + 278]

Is not necessarily and inherent advantage of thorium reactors but an advantage of Molten Salt reactors, which can come in two flavours Thermal-Spectrum/moderated and Fast spectrum which is moderated, the moderator tends to be water, or graphite, or boron.

A Fast breeder molten salt reactors has more advantages than a thermal reactors, any reactors that produces more fissile material than it consumes is a breeder thorium reactors are breeder reactors that convert Thorium-232 into Uranium-233, the real difference with Uranium-Plutonium breeders is that thorium reactors can work on fast spectrum-.

while there are problems of corrosion with the high temperature liquid salts they are not much bigger than problems of corrosion with superheated steam, Chloride based salts are less corrosive than fluoride based salts, and fluoride salts are less corrosive than pure water, the catch is that has to be PURE with no oxygen or nitrogen or any humidity or water or it will then produce a series of pretty annoying chemical reactions.

But then to be sure you can add another kind of salts to the mixture, for example in a Potassium-Rubidium-Sodium Chloride salt mixture is possible to add titanium chloride to make a less corrosive mixture that doesn't react with the walls of the vessel

even that, in a fast reactor you can also avoid corrosion by not using metal but ceramics, or coating the vessel with ceramic bricks, made of things like Zirconium Carbide, Titanium Carbide, Silicon carbide, Niobium Carbide, and using Tungsten Carbide as a neutron reflector, the cool thing about the Titanium- Zirconium-Silicon-Carbide mix is that the silicon-carbide reacts to form a glass-like coating on the surface that prevents corrosion at very high temperature, and remember corrosion is no different than oxidation, materials tend to search the point of highest energy stability the higher the melting point the higher the stability of the material and the lower the possibility of corrosion, Zirconium likes more to bond with carbon than with chloride. and Carbon likes to bond more with zirconium than with either uranium or thorium, and uranium or thorium and chloride make a good couple together.

Going back to safety it can't suffer a meltdown because the fuel is already melted, and it can't overheat because the negative-temperature-coefficient, let me explain this, when the reactors gets hot the liquid salt expands, and that reduces the criminality because there's less atoms in the same area, which makes it lower the rate of fission, with makes temperature to go down because is producing less power and that makes the volume  go down which again makes the rate of fission go up because the criticality goes up, and so on, is a funny trick that makes reactors to regulate themselves if they can support high temperature, sodium reactors do the same, in a molten salt reactors the salt has a high heat capacity but also high heat conductivity so it's unlikely that will reach a very high temperature, many people get's aroused on how a engineered machine can get a equilibrium like that , get to certain power output and staying there without any help

even if that doesn't work you can add passive convection water cooling systems, and make the control rods go down which will kill any possibility of fission or putting an energy tank made of neutron absorbing highly thermally conductive materials (hafnium or samarium boride) it can get a solenoid valve that will open when the power is out and will drain the liquid core into a tank

[ronwagn + 6,290]

I have heard about the thorium reactors for decades. If someone could actually build one and make it work economically they would have, and could use our experts if necessary. Russia, China, Japan, etc. They do not have eco-extremism problems. China loves nuclear and could go thorium if they thought it was possible. It is easy to blame it on politicians or greenies but logic says otherwise. 

[Robert Ziegler + 121]

On 9/10/2018 at 2:31 PM, Dan Warnick said:

Excellent!  I suppose big oil and a few others are also interested in stopping it?

Do you know if there is some sort of worldwide effort going on to inform the general public?  I had never heard of it before you mentioned it.

Who did not like the LFTR is the military-industrial complex, who preferred the dual use Uranium light water reactor..... For us in O&G the LFTR would be the best since sliced bread, allowing safe, unlimited and basically free steam to produce all the heavy oil in the world.....

[Robert Ziegler + 121]

Kirk Sorensen is your man if you want to know more. Last I heard is the Chinese are interested. It also would lend itself perfectly as a floating nuclear power plant, much better than any offshore "windfarm" as it is mobile and actually produces reliable energy.

https://www.ted.com/talks/kirk_sorensen_thorium_an_alternative_nuclear_fuel

[Jonathan Galt + 40]

The Thorium cycle of energy was successfully repressed (i.e. not even taught to people obtaining degrees in nuclear energy) for decades. The reason is obvious and political - if people knew that clean safe cheap nuclear power were a possibility they would have fought back against traditional nuclear reactors, the real reason for which they exist being to create nuclear fuel for weapons.  Much easier to tout LWRs as "energy of the future" to a dumb populace.  Can I prove it?  Only using Res Ipsa Loquitar.  I did train to deliver nuclear weapons, and no they didn't teach us that there but you learned to read between the lines concerning political policies if you weren't an idiot.

Can MSRs be profitable today?  Hard to say - in a few more years solar plus batteries will undercut fossil fuels.  Perhaps in higher latitudes with less sunlight they will make sense.