Thorium Instead Of Uranium: Solution To Our Energy Woes?

by johndcook • 16 years ago

76 70 16 years ago

johndcook• 16 years ago

The post doesn't give a definite answer to the question in the title, but it is interesting.

ScotterC9• 16 years ago

It could be a plausible solution to our electricity woes to a degree. Mainly in baseload electricity supply which is about 60% of the U.S. grid. Small liquid flouride thorium reactors (LFTRs) can fit on a flatbed truck and mass manufactured. The idea is that we can connect these to existing coal plant secondary systems around the country and replace the coal boilers.

Thorium is extremely abundant. We have 3000 tons of it sitting in nevada gathering dust because we have nothing better to do with it. Also, you can get an incredible amount of energy and little waste out of a liquid thorium reactor. See http://energyfromthorium.com/. That's Kirk Sorensen's blog. A NASA engineer who's really led the movement on LFTRs and got featured in Wired for it.

pjscott10• 16 years ago

If we can get the cost per megawatt of capacity low enough, liquid fluoride thorium reactors could even be used for peak power. They can scale their power output up and down pretty rapidly, since they would use Brayton-cycle gas turbines for power conversion, and it's possible to continuously (or very frequently) remove xenon-135, which is a neutron poison and has traditionally made it harder to adjust the power output of nuclear reactors.

GiraffeNecktie• 16 years ago

The short answer is that there are many entrenched interests who are not keen on the idea: Uranium mines, nuclear industry, weapons manufacturers, not to mention the oil, gas and coal lobbies, even the alternative energy suppliers like solar. Thorium would rain on all their parades.

ScotterC9• 16 years ago

Exactly. Mainly, the current nuclear power industry, i.e. Areva, Westinghouse and GE make all their money on the fabrication fo fuel rod assemblies. They tried to make thorium fuel rods work in Indian Point Unit 1, but the layout of the rod bundles was tough to optimize to allow fertile material to become fissile and cycle correctly to be efficient at heating up the primary coolant.

Add this to all the regulatory hurdles and the big three nuke companies see no reason to pursue such a financial risk.

Retric5• 16 years ago

The real answer is the R&D costs are not worth it because Uranium is still extreamly cheap. The fuel costs for a modern reactor are a small fraction of total cost.

Also, fosil fuels a not going to be replaced with wind, solar, fission or fusion any time soon because they are not really portable for anything smaller than a boat.

sdurkin• 16 years ago

You're both right.

"The real answer is the R&D costs are not worth it because Uranium is still extreamly cheap."

This answers why the market won't develop the technology on its own. But the government could still sponsor research as they did with uranium fission.

"The short answer is that there are many entrenched interests who are not keen on the idea..."

And this answers why the government would never fund it.

narrator• 16 years ago

No conspiracy theory necessary. There are only a small number of people who can design and build things of nuclear reactor level complexity from scratch and they mostly work at government labs and for major engineering firms. The government wanted these people to focus their attention on the designs that would be useful for the cold war weapons programs so the thorium reactors just didn't get built.

ngvrnd2• 16 years ago

I've read somewhere that one problem with Thorium is it can easily be converted to a fissionable isotope (of Uranium?) which can be used to build bombs. So there's that.

randallsquared• 16 years ago

One of the anti-proliferation points is that U233 (which is the isotope you're thinking of) is mixed with U232, which decays to products with high gamma output, meaning that it's more dangerous to work with than the more typical fissionable materials, and much easier to detect. For a state this probably wouldn't be a significant barrier, but it's a fair point with respect to terrorist bombs. Of course, we haven't seen any of those, which implies that there's some non-obvious factor at work, here.

CWuestefeld• 16 years ago

From the OP:

You will hear that we can’t make bombs out of U-233 because it is a virulent gamma-ray emitter. This is not true, and I find it curious that it is used as a reason. U-233 has a 158,000-year half-life. What they are referring to is the protactinium-233 contaminant, which has a 27-day half-life, beta-decaying into U-233 with gamma-ray involvement. Chemically scrub the protactinium, of course, or just wait a year and it will be gone.

eru• 16 years ago

No. The problem is the other way around: It _can't_ easily be converted. That's why is was not investigated in the 40s and during the cold war too much: People were interested in bombs, too.

ScotterC9• 16 years ago

That's true. We had two reactor options during the cold war that were choices to extend our Uranium supply. One was the Fast Breeder reactor and the other was the liquid thorium reactor. My dad worked on the Fast breeder which would use liquid sodium as a coolant to allow the reactor to operate at much higher temperatures and high neutron flux so as to burn actinides more efficiently and convert uranium into plutonium to be either burned or taken out and used for weapons. Although, it's silly, American commercial fast breeders wouldn't really be used for plutonium production even if they got off the ground because U.S. regulations wouldn't allow anyone to access the fuel very easily. Unlike Chernobyl, which was a weapons/energy plant, designed for easy access to it's fuel. Hence the lack of containment which all American plants are required to have.

ScotterC9• 16 years ago

Add a neutron to Thorium-232 and it becomes protactinium for 30 days which then decays to Uranium-233. Uranium-233 is great bomb material and perfect reactor fuel, although as mentioned it is quite hot and difficult to work with. The key with thorium reactors, is that apart from the U-233 seed to start the process of converting fertile thorium into fissile material, no more needs to be added.

Thorium is all around us. Adding a neutron to it to create uranium is no simple matter if one doesn't have a high flux neutron supply (such as a reactor).

magamiako• 16 years ago

If you need lots of thorium you can usually find a ton of it Winterspring or the Burning Steppes!

ScotterC9• 16 years ago

You can find it pretty much anywhere actually. It's a by-product of many mining processes and India has literal beaches of it.

AndrewHampton• 16 years ago

I believe magamiako is referring to areas in World of Warcraft where thorium can be found.

grandinj• 16 years ago

This is a classic case of a solution to a problem that does not exist.

Firstly, Uranium is practically an insignificant cost of a nuclear power station. The price would have to go up by a factor of a 100 before it made a difference.

Secondly, the supplies of uranium are currently limited because the demand is limited. The moment the price shifts up by even a little, supply will grow because several other mining locations will become profitable.

Retric5• 16 years ago

We have already mined something like 100 years worth of Uranium that is just waiting around to be used in power plants. Or, if the US moved to breeder reactors we could go for something like 1000 years without mining any new uranium.

terra_t4• 16 years ago

The trouble with fast breeders is that you need a huge fissile inventory to get one started.

A study of the PRISM design, a modern fast breeder that uses integral reprocessing to reduce the inventory of plutonium that's sitting around, not fissioning, indicates that if we reprocessed all spent fuel in the U.S. today, we'd have enough Pu to power about 33 MWe worth of breeders, about 1/3 of the current fleet.

It comes down to energy vs power. "Fast" breeders can tap a huge energy resource, but they can only produce a low level of power because they tap that energy slowly. That's the whole reason they use highly reactive sodium as a coolant; to reduce fissile inventory per unit of power, you need a coolant with incredibly high heat conductivity. Lead is a much easier material to handle, but a lead-cooled fast reactor has 1/3 the power density of a sodium reactor, which means 3x the fissile inventory.

Fast breeders, therefore, can sustain energy production over a long period of time, but they can't drive a rapid expansion of nuclear energy, like the 5-fold increase we'd need to replace fossil fuels and stop global warming -- it becomes hard to justify the economics of a plutonium economy in the same way... You have to be thinking more than "seven generations" ahead to see the economic boon.

Thermal reactors effectively trade a moderator material (water, graphite, etc.) for (relatively scarce) fissile material. Thermal reactors (even today's LWR) extract 10-20x as much power from fuel than do fast reactors with less aggressive design (although the LWR extracts only 2% as much energy, in the long term, as a breeder could.)

A thermal breeder, based on thorium, could provide the best of worlds. With small inventory, it's possible to meet high power requirements, but by using abundant thorium instead of rare U-235, be able to sustain that power for thousands of years.

olegkikin2• 16 years ago

Your 100 and 1000 year assumptions are just silly. You assume energy demands will remain constant, while they are exponential.

Just think what will happen if electric cars become popular. We will need a lot of electricity.

edfrtghjkjh• 16 years ago

True for the US with a big supply of uranium in a (relatively) friendly country to the north.

Different for say India that has lots of Thorium, no Uranium and doesn't want to go begging to Russia or spend hard currency in Canada.

cstross2• 16 years ago

No, there is a problem.

But the problem is political, not economic.

A uranium fuel cycle makes it relatively easy to breed plutonium or explain why you're building enrichment plants which can be used to make weapons-grade HEU. Ergo, bombs. Ergo, proliferation-policing issues.

To move the planet onto nuclear power (as a zero-carbon solution) is therefore politically unpalatable to those who enforce the current nuclear weapons oligopoly.

A Thorium economy might be manageable without making proliferation too easy, if the fuel is converted to U-233 and burned in situ. (Certainly U-233 isn't used in weapons at present as far as I know ...)

DanielBMarkham• 16 years ago

I'm a big fan of Thorium, but I'm also a big fan of nuclear in general. It just makes sense.

In fact, this is a lot like the issue of not building any oil refineries in the United States since the 1970s. While I'm sure there are good reasons for our lack of needed nuke plants, at the end of the day it looks like the system has let us all down.

I hate to sound like old cranky guy again, but frack, if you really wanted to get off oil you could do the math for how many nuke plants you'd need -- it'd be a lot! But it wouldn't be impossible, and we've known all of this for decades. It's just very frustrating. Things like the thorium ideas just make things worse because we can't even solve our problems using the old technology, much less the new stuff. It's almost like rubbing salt in the wound to see such potential and realize how improbable it will be to see the light of day (in a massive production sense). I find the state of our energy policy completely incredible, but the tech continues to look better with each passing year. Sigh.

henrikschroder2• 16 years ago

Nuclear power plants can't replace oil- or coal-powered plants, because nuclear plants can't adjust output over the day to fit actual usage. Nuclear power plants are great for providing the baseline power production, but you need something adjustable to handle the morning and evening peaks, like oil or coal or wind or hydro or really big batteries.

So no, you can't do the math for how many nuclear plants you would need to get off oil.

cameldrv• 16 years ago

Sure they can. Hybrids that charge at night, that get cheaper rates to charge when the utility sends a signal, pumped storage, only running hydroelectric during the day, running aluminum smelters at night, thermal storage, or worst case, just not using the extra electricity. There is stuff to build, but we're not going to build all of those nuke plants overnight either.

ColinDabritz• 16 years ago

Can we not solve this problem by storing energy in the longer term?

It's true some 'burst' capacity is important, but can you not get a lot closer to 'average load' than the baseline by using the energy? Pumping water into a reservoir at night, and getting the power back with a small hydro plant during the day comes to mind. We smooth out an even worse problem with wind and solar, which is spiky AND out of sync with demand sometimes. I believe flywheels are used to store energy in the short term sometimes. You did mention 'really big batteries', implying that we would need too many, but we aren't limited to chemical forms of energy storage.

I think this is a solved problem, or at least a fairly solvable problem, and nuke plants can provide not only the 'baseline' but close to the bulk average needs for power. We can decouple the power generation and the need for "something adjustable" and benefit.

pjscott10• 16 years ago

France is using some of their nuclear plants to provide peak load, and they adjust the power output of most of their plants over the day to better fit the actual usage. Their reactors are not ideal for this; there are better ways to design nuclear plants for load-following. But it can certainly be done.

Alternately, you could make enough nuclear capacity to provide your peak power levels all the time, and dump excess energy into some energy-hungry industrial process, like aluminum smelting, or synthetic fuel production, or ammonia synthesis.

So yes, you can do the math. It's just that there are a bunch of different ways to do that math, and most of them involve a lot of cleverness, large budgets, careful engineering, and a fair dose of uncertainty.

greyfade• 16 years ago

Yes you can.

Liquid-Fluoride Thorium Reactors can be started and stopped without incident, in a few hours. I believe their output can also be adjusted in operation. They're safe and efficient enough to build one into a 40-foot trailer that can be started, stopped, and moved on a moment's notice.

mkn• 16 years ago

You're thinking of solid-fuel uranium reactors.

Actually, thorium reactors have a natural load-following capability due to their negative thermal coefficient of reactivity. You suck power out of them too fast, they cool, get denser, and the reaction rate increases, increasing power output.

In addition, shutting down a liquid salt reactor is literally a matter of pulling, actually melting, a plug. Simply overheat the core, melting the freeze plug, and the fuel falls into a subcritically shaped catchment tray. Reheat and reload and the reactor is up again. They're very easy to start and stop.

There's a wealth of information on the Net about these guys. I hope they get built!

sethg• 16 years ago

The US government already provides massive incentives for nuclear power, but even with those incentives, nobody is building. Maybe the American nuclear industry just has such an awful record of cost overruns that investors don’t want to give them any more rope. But if the Indians can run their nuclear industry in a more competent fashion, good for them.

pjscott10• 16 years ago

The US government has a horrendous nuclear regulatory regime. If anything, they're anti-subsidizing.

tbrownaw• 16 years ago

> American nuclear industry just has such an awful record of cost overruns

Due primarily to NIMBY lawsuits, IIRC. Nuclear is technically easyish, but misinformed protesters make it socially/legally messy.

ScotterC9• 16 years ago

The current energy industry is so over regulated that it completely stifles innovation. It's worse then Taggart Transcontinental

_delirium• 16 years ago

Part of the reason for no new refineries was a long period of extremely poor profitability. Companies were actually shutting down existing refineries through much of the 1980s and 90s, amidst worries of industry-wide "excess refining capacity".

cromulent• 16 years ago

Patrick Moore (Greenpeace founder) and James Lovelock (Gaia theory) must also be "cranky old guys" as they also believe nuclear makes sense.

http://www.washingtonpost.com/wp-dyn/content/article/2006/04...

It is super frustrating. And we aren't building enough to replace the old ones!

http://www.nytimes.com/2009/05/29/business/energy-environmen...

Sometimes it seems as though Western civilization has peaked, simply because we've lost our mojo.

whyenot• 16 years ago

I'm all for thorium and nuclear energy, BUT only if we in the US stop with the NIMBY-ing and find a permanent storage location for nuclear waste.

warfangle• 16 years ago

No need for a 'permanent storage solution' for thorium waste. What little waste there is decays to safe levels in less half a century.

muhfuhkuh• 16 years ago

I thought all of the arguments against nuclear were overwhelmingly about NIMBY (not in my backyard). People just look at Three Mile Island and Chernobyl and think "hell no."

Maybe after the BP spill, we'll think a little more about nuclear.

ericd• 16 years ago

Wouldn't getting over our fear of reprocessing Uranium make this a non-issue? That seems the simplest and most straightforward path... Just have to figure out a way to lock down the resulting plutonium.

Thorium Instead Of Uranium: Solution To Our Energy Woes?

Related Stories