Thorium: World's greatest energy breakthrough?

[Chris_]

Thorium: World's greatest energy breakthrough?

If, like many of the world's leaders, you are eager for a dependable and cheap energy source that doesn't spew toxins and greenhouse gases into the atmosphere -- and that doesn't result in terrible, billion dollar accidents -- you can end your search now.

At least, that's the news from a tight-knit collective of energy blogs, dedicated to a common but relatively unknown metal called thorium.
In the right kind of nuclear reactor, they say, thorium could power the world forever -- and without the problems that come with the nuclear energy we use today, from Fukushima-like meltdowns to the difficult by-products of plutonium that leave behind radioactive waste and weapons material.

The idea certainly sounds like the stuff of fringe internet conspiracists, but it was actually born in the U.S. government's major atomic lab in the 1960s under the auspices of one of the country's most respected nuclear scientists, and the inventor of today's most common kind of nuclear technology, the light water reactor.

CNN

The Thorium Dream

I thought I'd read some stories about the Germans experimenting with nuclear reaction that never panned out.  Wasn't Chernobyl a heavy-water reactor?

[DumbAss Tanker]

Yeah, the Germans had three reactors in varying stages of completion, all relying on heavy water for neutron moderation.  They never got as far as Fermi's sustained chain reaction, though they came pretty close.

Funny reading about thorium in this connection now, when I start reading Heinlein's youth SF about fifty years ago, it was the energy metal for ship reactors in his stories.   

[Chris_]

The second link I posted has a decent primer on the subject with the exception of the stupid, kooky woman at about 17 minutes and the moon-eyed acolytes that show up throughout the video.

[JohnnyReb]

"If it sounds to good to be true, .........."

[TVDOC]

Not a panacea, however not really new technology.  Its primary advantage is that it exists in its pure form in nature, requiring little to no refining and enrichment, plus.....and perhaps most importantly; to the tree-huggers, is that a Thorium reaction is not self-sustaining, eliminating the vast level of paranoia confronting Uranium reactors:

Fuel Cycle:

Although not fissile itself, Th232 will absorb slow neutrons to produce, after two beta decays, U233, which is fissile. Hence, like U238, it is fertile. Also, preparation of thorium fuel does not require isotopic separation.

The thorium fuel cycle creates U233, which, if separated from the reactor's fuel, can be used for making nuclear weapons. This is why a liquid-fuel cycle (e.g., Molten Salt Reactor or MSR) is preferred — only a limited amount of U233 ever exists in the reactor and its heat-transfer systems, preventing any access to weapons material; however the neutrons produced by the reactor can be absorbed by a thorium or uranium blanket and fissile U233 or Pu239 produced. Also, the U233 could be continuously extracted from the molten fuel as the reactor is running. Neutrons from the decay of uranium-233 can be fed back into the fuel cycle to start the cycle again.

The neutron flux from spontaneous fission of U233 is negligible. U233 can thus be used easily in a simple gun-type nuclear bomb design. In 1977, a light-water reactor at the Shippingport Atomic Power Station was used to establish a Th232-U233 fuel cycle. The reactor worked until its decommissioning in 1982. Thorium can be and has been used to power nuclear energy plants using both the modified traditional Generation III reactor design and prototype Generation IV reactor designs. The use of thorium as an alternative fuel is one innovation being explored by the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO), conducted by the International Atomic Energy Agency (IAEA).

Unlike its use in MSRs, when using solid thorium in modified light water reactor (LWR) problems include: the undeveloped technology for fuel fabrication; in traditional, once-through LWR designs potential problems in recycling thorium due to highly radioactive Th228; some weapons proliferation risk due to production of U233; and the technical problems (not yet satisfactorily solved) in reprocessing. Much development work is still required before the thorium fuel cycle can be commercialized for use in LWR. The effort required has not seemed worth it while abundant uranium is available, but geopolitical forces (e.g. India looking for indigenous fuel) as well as uranium production issues, proliferation concerns, and concerns about the disposal/storage of radioactive waste are starting to work in its favor.

Current Projects:

India's Kakrapar-1 reactor is the world's first reactor which uses thorium rather than depleted uranium to achieve power flattening across the reactor core. India, which has about 25% of the world's thorium reserves, is developing a 300 MW prototype of a thorium-based Advanced Heavy Water Reactor (AHWR). The prototype is expected to be fully operational by 2011, after which five more reactors will be constructed. Considered to be a global leader in thorium-based fuel, India's new thorium reactor is a fast-breeder reactor and uses a plutonium core rather than an accelerator to produce neutrons. As accelerator-based systems can operate at sub-criticality they could be developed too, but that would require more research. India currently envisages meeting 30% of its electricity demand through thorium-based reactors by 2050.

The German THTR-300 was the first commercial power station powered almost entirely with Thorium. India's 300 MWe AHWR CANDU type reactor will begin construction in 2011. The design envisages a start up with reactor grade plutonium which will breed U-233 from Th-232.After that the input will only be thorium for the rest of the reactor's design life.


The primary fuel of the HT3R Project near Odessa, Texas, USA will be ceramic-coated thorium beads. The earliest date the reactor will become operational in 2015.

Best results occur with molten salt reactors (MSRs), such as ORNL's liquid fluoride thorium reactor (LFTR), which have built-in negative-feedback reaction rates, due to salt expansion and thus reactor throttling via load. This is a great safety advantage, since no emergency cooling system is needed, which is both expensive and adds thermal inefficiency. In fact, an MSR was chosen as the base design for the 1960s DoD nuclear aircraft largely because of its great safety advantages, even under aircraft maneuvering. In the basic design, an MSR generates heat at higher temperatures, continuously, and without refuelling shutdowns, so it can provide hot air to a more efficient (Brayton Cycle) turbine. An MSR run this way is about 30% better in thermal efficiency than common thermal plants, whether combustive or traditional solid-fuelled nuclear.

In 2010, Congressman Joe Sestak added funding for research and development of a destroyer-sized reactor using thorium.

CANDU reactors of Atomic Energy Canada Limited are capable of using thorium as a fuel source.

At the 2011 annual conference of the Chinese Academy of Sciences it was announced that "China has initiated a research and development project in thorium molten-salt reactor technology."

Various sources.......

doc

[NHSparky]

Sorry, as a nuke worker there's no way in hell I'd want to work in a Thorium-based plant.

[TVDOC]

Sorry, as a nuke worker there's no way in hell I'd want to work in a Thorium-based plant.

A bit too close to the old Russian nuke boat reactor designs for comfort??

doc

[NHSparky]

A bit too close to the old Russian nuke boat reactor designs for comfort??

doc

Among other reasons.  Thorium being a pretty healthy alpha-emitter and all doesn't help either.

[Chris_]

Among other reasons.  Thorium being a pretty healthy alpha-emitter and all doesn't help either.

I take it that is not a good thing.

[NHSparky]

I take it that is not a good thing.

Alphas, once inhaled or ingested, are nasty.

[DumbAss Tanker]

Alphas, once inhaled or ingested, are nasty.

Well, actually getting a mote of the emitter inside you is what does the damage, the particles themselves have virtually no chance of gettting inside you if the emitter is outside your body.  I'm sure that's what you meant, but it may not be clear to anyone reading it who is unfamiliar with ionizing radiation effects.

The interesting thing in that 'Fuel cycle' passage is it keeps saying how it won't produce weapons metal, but then it keeps also noting the weapons metal can be extracted at various steps.  That's a bit disingenuous, since extracting it is what makes it available in concentrated form for further concentration into weapons-grade material.

[TVDOC]

The interesting thing in that 'Fuel cycle' passage is it keeps saying how it won't produce weapons metal, but then it keeps also noting the weapons metal can be extracted at various steps. That's a bit disingenuous, since extracting it is what makes it available in concentrated form for further concentration into weapons-grade material.

True, however the point that is downplayed in all the hype is that Thorium itself will not sustain a chain reaction......meaning that in order for a reactor to function, there must be a steady supply of emissions from either U-235 or Plutonium, at very close to weapons-grade enrichment levels to sustain the reaction. Granted, it's used only as an "initiator", and not consumed in the fuel cycle......however, it's still there.  I can't see an advantage from the waste handling/disposal perspective either.

From strictly an engineering point of view, the only advantage to Thorium reactors is that the fuel requires little, if any enrichment.  

Close to weapons-grade fissile material will always be present in a reactor, regardless of fuel, the only difference is the quantity and ease of access. The hype also claims that since the Thorium reaction is not self-sustaining, that many of the present reactor safety systems, and emergency cooling systems will not be needed.......I suspect that is a good part of Sparky's problem with them, along with the liquid salt/heavy water design. The Russians used a liquid Sodium reactor design (similar to this) on many of their nuke boats which, from a safety perspective were rightfully dubbed "widowmakers".........

Thorium-LSHW, and conventional liquid Sodium cooled reactors can be built very small (in cubic feet of reactor per KW of output), however the coolant is highly reactive.......a tiny leak in an enclosed environment can be critical (further, refueling and cooling system maintenance is a nightmare). Current light water designs, with all of their foibles and backup requirements are (at least in practice) much safer in the long run (at least to those required to operate and maintain them).

A Note on Nuclear Power Plants, Waste, and Terrorism:

A great deal of the paranoia surrounding nuclear power, its waste products, and terrorism, is engendered by the possibility of someone making one of two types of devices.  First, a "dirty bomb" which is a conventional explosion designed to dispurse radioactive material over a wide area (these ARE NOT nuclear explosions).  In the event such an event were planned, it is far more likely that medical radiological material would be used for a couple of reasons:  First, it's much more widely available, and second, subject to far less security.......the average large urban hospital oncology unit would have enough isotopic material for such purposes.

The second.....an actual nuclear weapon, is far more complex.  Such a device would require between 2.5 and 10.5 kg of weapons-grade material, and the know-how to put it together successfully.  Making a "gun-type" weapon is fairly straightforward, but vastly inefficient, prone to "fizzle" (and nearly impossible to radiologically conceal).  A "lens-type" device is far more powerful, and  several orders of magnitude more complex to build.  It is significantly more likely that any group bent on such an event would procure a weapon from someones existing arsenal than attempt to construct it themselves.

Neither scenario places nuclear power plants very high on the list of resources.

doc

[DumbAss Tanker]

...conventional liquid Sodium cooled reactors can be built..., however the coolant is highly reactive...

Yeh.  Perhaps a wee bit of understatement, there.


 

[JohnnyReb]

Yeh.  Perhaps a wee bit of understatement, there.


 

If the sodium causes any problems, just piss on it.

[TVDOC]

Yeh.  Perhaps a wee bit of understatement, there.


 

Yeah.......just trying to keep a boring subject on an academic level, i.e. more boring........if half the class isn't asleep, the lecture is a failure.....how else can one make pop quizzes so much fun......

doc

[TVDOC]

If the sodium causes any problems, just piss on it.

There is that......Sodium and seawater in close proximity is a recipe for disaster.......however, as I understand it (and the Russians are understandably close-mouthed about it), the main problem was keeping it liquid  during maintenance periods.  Screw that up and you have hundreds of tons of radioactive scrap that used to be your power plant........

doc

[vesta111]

India will be going on line before the rest of the world.????

If it works good for them.   I however wonder how many generations will have to come and go to insure that all our theory's today become fact.    Somewhere down the line new discovery's will happen that our best scientists never dreamed of. The down side may be found to be a tad bit more dangerous then we think.

Fire, as we know can aid mankind to live a better life, downside it is a killer if not controlled properly. All about control or who is watching the baby. Are they qualified to do so, do they know how to react in an emergency???

All the training in the world will not stop hysteria in mankind, something happens and the supervisors facing split second decisions on a problem they never before encountered or was taught about.   We walked into Atom smashing with no real idea of the consequences.

Everything we did was and today still is based on theory, when Japan was nuked  in 1945 we sent stunned scientists to see the results.  It took years to somewhat understand the outcome.  Today we still do not know what radio active rain has done to crops world wide. Mutations take generations to form, nothing that happens overnight.

Seems like just yesterday the Japanese government  was calling in all scientists to help with a reactor saw the darn thing blow sky high.    No one was watching the baby it seems.   No one to ask, what happens if Godzilla is a fact.

If 20 back ups are adequate, throw in 20 more

Japan has gotten tidal waves from time began, why did they not take that into consideration when building these plants???------------------

Is Diablo Canyon still on line, the plant straddles a earth quake zone, the land sold to the government was owned by a relative of some State big wig.   When it needed repairs EX working for NUS went out there and called me most every day with horror storeys on the condition of the plant---1982-1984.  or there abouts.

I will feel better if I knew there were scientists that first go into the negative aspects, cover every event that could possibly happen under all known conditions. And some very far fetched conditions.

As an old lady I hope I live long enough to see how this all works out.