Kirk Sorensen: A Detailed Exploration of Thorium's Potential as an Energy Source

While Chris and I attend to making our wives/mothers feel sufficiently celebrated today, here's an interview from the archives that is well worth revisiting. We plan to have Kirk back on in 2014 to inform us of any notable developments in the LFTR space since this interview was recorded.

Kirk Sorensen, NASA-trained engineer, is a man on a mission to open minds to the tremendous promise that thorium, a near-valueless element in today's marketplace, may offer in meeting future world energy demand.

Compared to Uranium-238-based nuclear reactors currently in use today, a liquid fluoride thorium reactor (LTFR) would be:

  • Much safer - No risk of environmental radiation contamination or plant explosion (e.g., Chernobyl, Fukushima, Three Mile Island)
  • Much more efficient at producing energy - Over 90% of the input fuel would be tapped for energy, vs. <1% in today's reactors
  • Less waste-generating - Most of the radioactive by-products would take days/weeks to degrade to safe levels, vs. decades/centuries
  • Much cheaper - Reactor footprints and infrastructure would be much smaller and could be constructed in modular fashion
  • More plentiful - LFTR reactors do not need to be located next to large water supplies, as current plants do
  • Less controversial - The byproducts of the thorium reaction are pretty useless for weaponization
  • Longer-lived - Thorium is much more plentiful than uranium and is treated as valueless today. There is virtually no danger of running out of it given LFTR plant efficiency 

Most of the know-how and technology to build and maintain LFTR reactors exists today. If made a priority, the U.S. could have its first fully-operational LFTR plant running at commercial scale in under a decade.

But no such LFTR plants are in development. In fact, the U.S. shut down its work on thorium-based energy production decades ago and has not invested materially in related research since then.

Staring at the looming energy cliff ahead, created by Peak Oil, LFTR begs the question why not?

As best Kirk can tell, we are not pursuing thorium's potential today because we are choosing not to. We are too wedded to the U-238 path that we've been investing in for decades. Indeed, the grants that funded the government's thorium research in the 50s and 60s were primarily focused on weapons development, not new energy sources. Once our attention turned to nuclear energy, we simply applied the uranium-based know-how that we developed from our atomic bomb program rather than asking is there a better way?

This is an excellent and thought-provoking interview. I highly recommend that you also visit Kirk's website and its FAQs to familiarize yourself with the thorium cycle, as I predict we will be revisiting the thorium story again in the future.


Also, we encourage our readers with engineering and nuclear expertise to share their insights in the Comments thread below. We are looking for ways to light the path ahead as we begin to descend down the global energy cliff. Will thorium shine brightly for us?

Click the play button below to listen to Chris' interview with Kirk Sorensen (36m:02s):

This is a companion discussion topic for the original entry at

$1000.00 a from each owner.
One million owners.

"One billion dollars. 

One coop.

All the money you will need,  why not?

I have no problem replacing coal. Terrible stuff.

But unless we're talking about some Black Swan batteries of the future - current ones are good for cameras, phones and cordless drills, that's about it - the reach of electricity (with respect to transportation) will remain localised. Can't fly jets, can't move tankers, can't run lorries/excavators/etc on electricity (we need to move stuff around, not just people).


4200 planes in the air over the US at the time of 911. Scale is our mountain. Peak Oil will be the future.


No doubt.


Regards, Matt

My question is why Flibe Energy is a privately held company? Selling stock would get them enough money to build an LFTR plant, maybe they need more than a stock sale would bring in, for buying our congressional representatives approval. I've held Lightbridge stock since it was Thorium Power and they still haven't built a plant even though they were supposed to have one in partnership started in 2007 with Russia's Red Star. I don't know what is holding them both back as it doesn't appear to be money with Red Star involved. Lightbridge started their agreement with Red Star in 2007 and six years later not a peep about the plant since 2010. I've given up seeing thorium used to generate power in my lifetime, there's too many big money players that are against thorium for whatever reason.

Lets see, How would Darth Vader approach this problem?
Has anyone else noticed that when we have a problem we always choose an evil option? If we need energy instead of finding the solution that is right under our noses we choose to do something gross.

So we have an energy problem- what shall we do, develop Thorium or something else or go kill millions of innocent people in some far away land and take their oil?

I know, we can frack and poison the soil and the water. Food scarcity? More internal security. Climate change- spread doubt. Electrical energy shortage-burn more coal. Population restless- drugs, debt and  day care to dumb them down.

It is probably the attitude of a class of people that I despise. Those who have the power and the money to actually do something useful, but are too lazy to break some self-referential mirrors. "Oh La. If I just play some meaningless mind game then I wont have to stress my brain with any real thinking."

No? Oh well. It is just paranoid ol' me.

China has a far larger percentage of engineers in the Chinese Politburo than in the "free world." We have an infestation of Lawyers whose only solution is to pass more laws. If the only tool you have is a hammer everything looks like a nail.

If we do manage to solve our energy needs, we will not be out of the woods. We will still have to solve the exponential growth thingy.

I am a great fan of LFTR, ever since I first discovered it through Kirk Sorensen's site a few years ago. In fact I am so excited about the idea of thorium energy that I talk it up every chance I get.
However, despite Sorensen's efforts, essentially nobody but a very select few know about LFTR. I had never heard anything about it before stumbling across My raising the subject is usually the first time the person I am talking to has heard of thorium never mind liquid flouride thorium reactors. Even a PhD physicist I spoke to on a plane last month had never heard of LFTR.

On the bright side, almost everyone I tell about LFTR seems to immediately grasp what a potentially important technology it could be and they usually ask "why aren't we developing these reactors?".

So having Kirk back on PP is a great idea. The more people who learn about LFTR, the more enthusiasm for the technology, the sooner it will appear on the radar of those who have the power or the means to make it a reality. That can't happen soon enough.


Let's have a grown up conversation about what we plan to do with more energy if we get it.  If we all agree to curb consumerism, war mongering, pollution and exponential growth and move forward with building a more perfect world then I say let's do it.  Otherwise let's not give more toys to misbehaving children (myself included).

So on one hand we are facing the end of civilization — possibly the extinction of mankind (remember - 98% of all ag land is farmed using oil and gas based pesticides - the land is DEAD without them… so how will you feed 7.2 billion people?  How will you keep thousands of spent nuke fuel ponds from exploding???)
But apparently there is a silver bullet at hand — something we've known about for some time.


And you are claiming that we are ignoring this solution to our problems???


If thorium made sense venture capitalists would be pouring billions into this — because whoever makes this a reality will be richer than Gates, Buffet, Zuckerberg, every hedge fund manager on the planet, the King of every oil emirate on the planet COMBINED!!!

And say the government does not invest because they are beholden to dirty power interests.

Yet how many hundreds of billions have governments invested in other clean energy punts such as solar? 

If this had even the slightest chance of success of course the Fed would be directing hundreds of billions into research (they are printing trillions…)

As we can see some are trying and failing completely;

Thorium is like all green energy concepts - PIE IN THE SKY.

Nothing will replace fossil fuels - ever.   We are on the cusp of a collapse because cheap fossil fuels are running out


Fracking is the only thing between us and total calamity - and it will not last for long… when fracking peaks — it's game over


Having a grow up conversation is only going to perpetuate the mentality that the world's energy situation and all other industries currently rest upon. So what is the mentality of our current systems? As I see it, it rest upon the belief of "managing risks" for human endeavors. Also known as the source code of our consciousness.
If we were to model after nature's teachings then we would build our conscious source code upon "maximizing opportunities" for all life. It could be possible that finding and deploying energy solutions could be like swatting mosquitoes in the jungle. But to do this requires the unimaginable. Which is why I try to imagine it, with all my faculties. However, everything man made lie-ing around has been birthed by risk management and can not be trusted which is why it's just so damn hard.

I really hope we don't make the mistake of forcing one of natures creative energy solutions out of the darkness before it wants to be seen. As the scientific magicians have the power to do it, but they'd be best ready to deal with the unmeasurable, perpetual biases, and the illusions of predictability and the fallout. The best way to be friends with me is to simply ask, forced friendship without asking is just rude!


See the Economist article from 12-Apr-2014.  Interesting read.  I will try to learn how to insert links someday.  :slight_smile:

Nixon gave the USA war in Vietnam, war in Cambodia, Watergate, HMOs then canned Thorium reactor energy research and threw the remnants of the gold standard to the wind.   Did he do anything right besides hand in his resignation?

"Nixon gave the USA war in Vietnam"
No. That was LBJ that got us into the Vietnam war. Nixon was terrible but you can't blame the Vietnam war on him. 

"Much safer - No risk of environmental radiation contamination or plant explosion"

False. Thorium reactors will produce long lived radioative isotopes that are just a bad as Uranium. In fact the original Core of the Experimental Thoruim MSR from the 1960's is still not completely decommissioned because its still too hot to handle. A MSR can have a meltdown just like a light water reactor. As as far as explosions: A molten flouride salt coming in contact with water will react explosively.

Thorium mining creates a lot of contaminate waste that ends up polluting water and ground water. The people mining and processing thorium ore face huge health risks. In my opinion, anyone promoting Thorium reactors should be the first to signup to work in a thorium mine!

"More plentiful - LFTR reactors do not need to be located next to large water supplies, as current plants do"

False again. Thorium reactors make electricity the same way Uranium reactors do: with steam turbines. after the steam exits the turbines it needs to be cool so it condenses back into water. Either a cooling tower or a reservor using an heat exchanger is required. A cooling tower just sprays water over a radiator to condense the steam, About half of the spray water that touches the radiators evaporates. 

"Less controversial - The byproducts of the thorium reaction are pretty useless for weaponization"

Also false. In fact the US is missing 75 Kg of weapons grade U-233 produced for the Thorium reactor program back in the 1960's. U-233 is the fuel that is transmuted from thorium in a thorium reactor. Its just deadly to handle because a small amount will be U-232 which emits a very high energy gamma. In 1955 the US detenoted a U-233 bomb.

"Compared to Uranium-238-based nuclear reactors currently in use today, a liquid fluoride thorium reactor (LTFR) would be:"

I think the author meant U-235 based reactors since U-238 is practically inert in Light-water reactors. U-235 provides almost all of the energy produced. In other reactors, heavy water, graphite-pile, and  breader reactors, U-238 is the fertile fuel that is converted into plutonium which is fissile. U-238 is not fissile as does not release any free neutrons when it splits. Only Isotopes with Odd atomic masses are fissile. A fertial fuel is a non-fissible fuel that can be transmuted into a fissible fuel.

Thorium reactors are breeder reactors as the Thorium fuel is also not fissile and must be transmuted into U-233 which is fissile. Also any working Thorium reactor can be converted to produce plutonium if the thorium is swapped with Uranium. Making the arguement that Thorium reactors can't be used producing weapons is misleading if not completely wrong. 

MSR's (molten Salt Reactors) have some major drawbacks which make them impractical. For instance its impossible to visual inspect a MSR since the Salt is Opaque. The salt is very corrosive, abrasive and hydrophilic. In virtually all MSR reactors the salts solidify on the reactor and pipe surfaces which eventual break off and damage the circulation pumps. The Salt also needs to be constantly reprocessed to remove fission products that build up. Several of them act as neutron poisons that prevent fission chain reactors and decrease conversion efficiencies. Servicing and repairing a thorium reactor is very difficult since a small amount of thorium will be converted to the deadly U-232, which releases a 2.6 MeV gamma which is impossible to shield (need about 12 to 15 feet of concrete. Any workers that need to replace pumps, piping will certainly get cancer or other radiation cause diseases.

The last time I read a study on the cost effectiveness of breeder reactors, the price of Uranium would need to rise to about $3K to $5K per Kg. I believe the current market price for Uranium is about $65 per Kg. That would be the equivalent of $4000/bbl oil. The Odds are that the global economy will completely collapse before we get anywhere the prices that make them market competive.




When reading this keep in mind the source — The Guardian - which is a HUGE proponent of Green initiatives…
So if they are dropping a pile of stinking dung on the thorium dream— you can be well sure this technology is pie in the sky and will NEVER happen.



China did announce this year that it intended to develop a thorium MSR, but nuclear radiologist Peter Karamoskos, of the International Campaign to Abolish Nuclear Weapons (ICAN), says the world shouldn't hold its breath.

'Without exception, [thorium reactors] have never been commercially viable, nor do any of the intended new designs even remotely seem to be viable. Like all nuclear power production they rely on extensive taxpayer subsidies; the only difference is that with thorium and other breeder reactors these are of an order of magnitude greater, which is why no government has ever continued their funding.'

China's development will persist until it experiences the ongoing major technical hurdles the rest of the nuclear club have discovered, he says.

In his reading, thorium is merely a way of deflecting attention and criticism from the dangers of the uranium fuel cycle and excusing the pumping of more money into the industry.

And yet the nuclear industry itself is also sceptical, with none of the big players backing what should be – in PR terms and in a post-Fukushima world – its radioactive holy grail: safe reactors producing more energy for less and cheaper fuel.

In fact, a 2010 National Nuclear Laboratory (NNL) report (PDF)concluded the thorium fuel cycle 'does not currently have a role to play in the UK context [and] is likely to have only a limited role internationally for some years ahead' – in short, it concluded, the claims for thorium were 'overstated'.

'Even if thorium technology does progress to the point where it might be commercially viable, it will face the same problems as conventional nuclear: it is not renewable or sustainable and cannot effectively connect to smart grids. The technology is not tried and tested, and none of the main players is interested. Thorium reactors are no more than a distraction.'


And zero revolutions. None, zich, nothing, Nihil.
$100 000 000 000 per year, by the USA alone.;feature=player_detailpage

Thorium does not work - PERIOD."Without exception, [thorium reactors] have never been commercially viable, nor do any of the intended new designs even remotely seem to be viable. Like all nuclear power production they rely on extensive taxpayer subsidies; the only difference is that with thorium and other breeder reactors these are of an order of magnitude greater, which is why no government has ever continued their funding.'

So Kirk — as a NASA scientist you surely are aware of the posts above that demonstrate Thorium is a complete and total joke.
Yet you are claiming it is viable.

So what is your angle in making what are obviously false claims?

Can you disclose your interests in this industry?  Are you benefiting from spreading this dis-information?

I wait with baited breath.

I don't really have a horse in this race, but this rhetoric seems overblown to me;

'Even if thorium technology does progress to the point where it might be commercially viable, it will face the same problems as conventional nuclear: it is not renewable or sustainable and cannot effectively connect to smart grids. The technology is not tried and tested, and none of the main players is interested. Thorium reactors are no more than a distraction.'

Clearly Th is not a renewable resource, but that does not mean there is any shortage of it.  From what I understand, there is plenty and in that sense it would be sustainable.  Also, why on earth would a smart grid care from whence it get's it's electricity?  This seems to me to be really stretching hard for negatives, whereas there are clearly many positives in a post-Fukushima world;
Reza Hashemi-Nezhad, director of the Institute of Nuclear Science at the University of Sydney, has focused on the advantages of thorium when used in an accelerator-driven nuclear reactor operating at subcritical conditions. Nuclear waste is less toxic than from a standard reactor. In a lecture delivered last year, he said that thorium fuel is a safe and cleaner source of nuclear energy, that the use of uranium fuel in nuclear power plants is controversial, and that the latter suffers from many disadvantages. "A thorium burning Accelerator Driven Subcritical Nuclear Reactor (ADSNR) avoids many of these problems," he said. "The reactors cannot melt-down, there is minimal production of long lived waste, diversion to military use is very difficult, reserves of thorium are almost inexhaustible and costs are expected to be lower than for uranium fuelled reactors." Additionally, he said, "If an ADSNR is fueled with fissile material bred from abundant natural thorium it can provide the world with an almost unlimited amount of clean and cheap energy." Read more at:

would they give us something that is cheap and abundant. With the move towards pointless renewables at sky high prices, they get to keep us right where they want us, on our knees. Sufficient grid power will be for the privileged only.


Methinks SudburyHardRockMiner doth protest too much. His statement “thorium reactors have never been commercially viable” is meaningless as no commercial reactors have ever been operated. An experimental reactor operated at Oak Ridge for 15000 hours from 1965 to 1969. After which the Atomic Energy Commission reported:

So far the molten-salt reactor experiment has operated successfully and has earned a reputation for reliability. I think that some day the world will have commercial power reactors of both the uranium-plutonium and the thorium-uranium fuel cycle type.” ~ Glenn Seaborg, Chairman AEC.

However, during the cold war, the thorium reactor was mothballed as the powers that be were not interested in a reactor that did not produce weapons grade material. Alvin Weinberg, who was director of Oak Ridge until 1973 and championed the thorium reactor was forced out by Hyman Rickover who wanted plutonium for bombs.

There is no major theoretical reason why a LFTR should not be commercially successful. The only thing standing between us and thorium power is an engineering project to bring the 1960s experimental design up to modern standards by the incorporation of methods and materials which have been developed since then.