Thorium Instead Of Uranium: Solution To Our Energy Woes? | Hacker News Reader

Thorium Instead Of Uranium: Solution To Our Energy Woes?

wmbriggs.com

76 pointsjohndcook70 comments

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.

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.

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.

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.

Here's the electricity demand curve for the UK for the last 8 days:

http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Dem...

Electricity demand during the night is about half of what it is during the day. If you were to have nuclear baseline production that covers peak consumption, you would have to find a way to store about 100000MWh of energy that gets produced during the night and then distribute that during the following day, or you would just waste it, somewhere, somehow.

(Disclaimer: Back-of-the-envelope math, I'm assuming the scale on that graph is in MW, it's only for the UK, not the US)

Yes, it's not an impossible problem. Yes, you can even out the peaks by changing behaviour. Yes, you could perhaps figure out a way to store and release that much energy each day.

But my point still stands, replacing fossil-based electricity production with nuclear is not trivial, it's a lot more complicated than summing up the total output of all fossil-based plants and dividing it by the average output of a new nuclear plant as DanielBMarkham argues.

I'm also a big fan of nuclear. Many countries would probably benefit from having their baseline production completely covered by nuclear plants. But how to deal with peak demand of electricity without fossil-based production and in an economically viable way, that is not a solved problem yet.

One of the reasons demand is light at night is that we run our central heating systems on gas -- mostly imported from Norway or parts east, these days. Per kWh, gas heating is a lot cheaper for the consumer. But if we had a serious base load nuclear infrastructure, we could provide much cheaper off-peak electricity for domestic heating, which would smooth out the demand curve significantly.

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.

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

Heck, you don't have to do anything with it, just disconnect your turbines from your generators.

Technically, sure. Economically, since most of the cost of nuclear power is the capital cost of building the plants, you want to be running them as close to 100% capacity as you can, all the time. If you can smelt some aluminum while you're at it, that really helps.

Good idea on the face but the energy needs to be dumped somewhere and dumping that much excess energy is tough and costly. Used to work in the industry, if the turbines tripped or anything else happened along the way, you SCRAM immediately as a safety precaution.

And they buy massive amounts of coal produced electric energy from germany during peak load times in winter.

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.

My favorite idea for this sort of thing is to put a LFTR on a barge (or, better, in a submarine), using seawater for cooling, and ship them out to any coastal area where they're needed. Build them in factories, assemble them in shipyards where such things are relatively easy, and handle the periodic maintenance and refueling in a centralized location.

Here's where it gets really fun: you can use the waste heat for desalination. There are a lot of places that sit next to a coastline but are short on electricity and fresh water. Russia is trying to make a lot of money from this, using a variant of the reactors they've been using on their nuclear ice-breaker ships.

And if you're using something like a LFTR that's compact enough to fit in a submarine, the water will protect you from hurricanes, earthquakes, aerial attack, and so on. It's a pretty clever scheme. Here's a thread on the Energy From Thorium forums discussing it:

http://energyfromthorium.com/forum/viewtopic.php?f=43&t=...

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!

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.

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

Without the government's liability coverage for nuclear plants, none would ever be built at all. A nuclear plant is simply un-insurable.

To all those people who insist nuclear power is very safe: no private insurance company has ever concluded the risks are sufficiently quantifiable to offer insurance.

> 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.

> Nuclear is technically easyish

Not the way it's been done in the US. Every plant was essentially a one-off design, with all the risks you'd expect from a multi-billion dollar construction project with significant R&D aspects. The industry is trying to standardize on replicable reactor designs, but it's not a cakewalk. Even the French have had a lot of difficulty producing a standard reactor, and few countries have invested as much in nuclear as they have.

This is why I'm optimistic about smaller reactors like the B&W mPower reactor, or China's HTR-PM pebble bed reactors. They're meant to be cranked out in bulk, identically, and shipped out to wherever the site is.

The AP1000 also looks like a pretty impressive attempt at standardization, since it comes mostly in the form of factory-produced modules that get assembled on-site.

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

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".

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.

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.

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.

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.

Over the next 40 years there is little economic reason to move to breeder reactors. However, they are a much better long term solution to waste than simply storing the stuff in the ground. Also, because the LWR to Breeder cycle spends so much time on the Breeder side of the equation a fixed number of LWR can feed a growing number of Breeder reactors over time. Thus you need to map out what happens over long time periods to get the balance correct.

Edit: If a LWR extracts 2% of total energy in 0.2% of the time, a breeder would need 10x the fuel to produce that much power and it would take 500 times as long to use up that fuel. Thus the stable ratio of LWR to breeders would be 1:50 relative to power output, but it would take ~750 LWR fuel cycles to reach that balance assuming you did not start wait for a huge stockpile to begin. (Breeders are not 100% efficient but the math is not all that far from reality.)

And that gets us to the central problem of our energy policy.

Utilities are moving towards a short-term thinking model where they install natural gas turbine with a low capital cost and use electricity deregulation to offload the risk of volatile natural gas prices to the consumer. "Renewables" are also driven by short-term motives: making a quick buck by exploiting government subsidies.

Nuclear energy can give us a sustainable energy source the thousand-year timescale (energy-wise, breeders can certainly consume seawater U238 profitably,) but we need to be thinking on the timescale of decades, not the next quarter, to get there.

> 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.

That should be "GWe" not "MWe".

Also, I dispute your choice of statistic. Why not show what happens if you start fast breeders on mined uranium, just like LWRs?

Sorry I missed a factor of 1000. Fast breeders on mined uranium have the same problem as plutonium breeders... Except you can breed plutonium faster (but less efficiently) in LWRs!

I mean, it's an odd statistic. You can use U-235 directly, or you can burn it in an LWR, getting back just 1/5th its equivalent in Pu-239, and use that. If you're trying to maximize fissile input for fast breeders, LWR spent fuel isn't an efficient way.

And moreover, with mined uranium there's no limit to your rate of expansion other than mining. You don't have to sit and wait for your atoms to reproduce (doubling time 20-40 years), when you can just dig up new ones.

Some back of the envelope numbers:

Assuming 3% enriched fuel burned to 40 GWd/ton, and 33% thermodynamic efficiency, the US nuclear fleet (~100 GWe) consumes around 100 tons/year of U-235 in fuel. At about 10 kg/MWe fissile inventory, just 10 years' of present US uranium consumption would be enough (1,000 tons) to start up a 100 GWe fleet of fast breeders -- same as the current LWR fleet.

I found a table of fissile inventories here:

http://nuclear.inl.gov/deliverables/docs/msr_deliverable_doe...

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.

Resource usage tends to follow a http://en.wikipedia.org/wiki/Logistic_function not pure exponential growth. Picking a good limit is hard but assuming energy use per person is stays around 5x our current value and US population is limited to 1 billion people 1000 years is an extremely conservative estimate.

Conceder: Between 1980 and 2006, the worldwide annual growth rate was 2%. (http://en.wikipedia.org/wiki/World_energy_resources_and_cons...) If you assume world energy usage will grow 2% per year for the next thousand years you end up with 400,000 times current energy usage however, the sun only supplies the earth with ~10,000 times our current energy use so we would fry the planet with waste heat far before that level. (Think global warming to 800 degrees Fahrenheit.)

PS: In 2009, world energy consumption decreased for the first time in 30 years (-1.1%) or 130Mtoe, as a result of the financial and economic crisis (GDP drop by 0.6% in 2009) so growth is not necessarily even guaranteed.

Your assumption that we will stay exclusively on this planet for the next 1000 years is even more silly.

At no point did I assume that. If, I extrapolate based on something that is not true (aka we stop mining uranium) and look at it in a given area (aka the land area currently occupied by the USA or the Earth) then clearly I am not trying to predict human behavior in some other location.

If you want a prediction of human behavior, fine. I suspect that we will move to a mixture of fusion, wind, and solar power long before our supply’s of fissile materials become an issue. I also expect that our initial expansion into space will primarily involve exporting technology into space and collecting raw materials from space. However, initial space exploration is going to have minimal impact on life on earth with few material goods being sent back and forth. I also suspect that it’s going to take far longer than 1000 years before 1 billion people live outside the earths atmosphere.

Edit: The Americas where "discovered" 518 years ago and dispite being there for the taking and far more hospitable than space 200 million more people live in India than all of the Americas put together.

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.

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 ...)

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.

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.

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.

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.

As soon as the market has to bear the cost of long-term storage of waste, they'll be interested in thorium.

That "waste" is still perfectly usable fuel. You could extract the plutonium and uranium and use that to make more fuel rods. You could burn it in fast breeder reactors, in a hypothetical future where mined uranium becomes expensive enough to warrant the use of fast breeders. Or you could just ship it to Canada, where they have heavy-water-moderated reactors that can use regular nuclear waste directly as fuel, without any chemical reprocessing.

I keep saying that nuclear waste storage shouldn't be thought of as permanent disposal. It should be thought of as keeping a reserve of nuclear fuel for the future.

To add, http://en.wikipedia.org/wiki/Nuclear_reprocessing - see the last two paragraphs in history for some problematic decisions.

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.

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.

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.

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.

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.

No, that's wrong. The claim is that the bred U-233 will be contaminated with U-232, which is very hard to get rid of, and has the hard gamma emitter Thallium-208 in its decay chain.

Where would the U-232 contamination come from, if it's bred U-233? Does thorium also just sometimes decay into the lighter isotope?

Sometimes the thorium, when it absorbs a neutron, will emit two neutrons and turn into thorium-231, which decays (though a couple more isotopes) into U-232. It can also be formed when U-233 absorbs a neutron and emits two, forming U-232.

How hard this would be to separate depends on the type of LFTR design you're using. However, you could also include some thorium-230 in the fuel mix to denature any protactinium produced, so there's really no way around having U-232 mixed with the bred U-233. Here's a blog post with more details on the entire process:

http://energyfromthorium.com/2006/10/06/denaturing-thorium-w...

What about this?

http://www.technologyreview.com/blog/arxiv/25855/?ref=rss

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.

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.

Realistic breeder fuel cycles also use a mix of actinides that would be unattractive for bomb makers: you're going to start with fuel that's been through an LWR once or twice, so contamination with Pu240 and Pu241/Am241 will be high to begin with and will just get worse the more cycles you spend in a fast spectrum.

Now, hypothetically, a country like Iran could develop a fast reactor that's optimized for producing plutonium for military purposes, but practically this would be much more difficult than developing a heavy water reactor like the U.S. used at Savannah River.

The isotope which is most problematic in commercial fuel cycles would actually be Np237. It's easy to separate Np chemically from other elements, and Np237 is longer lived than other isotopes of Np, so it can be prepared in a very pure form. Np237 has a low spontaneous fission cross section and a critical mass close to pure U235 -- it would be an attractive material for primitive gun-type bombs.

Note that Np237 is produced from U235 by the chain of absorbing two neutrons, making U237, and then beta decay to Np237. A plutonium-fueled or thorium-fueled reactor isn't going to make as much of it as our current reactors do.

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).

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.

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

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

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.

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.

Isn't it wonderful how we've barely scratched the surface on what potential fission has?

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.

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

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

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

Incidentally, comments like that are why it's so irritating to try to have discussions of thorium on Reddit. Of the people who post in those threads, a significant fraction are just there to make WoW references.

I have the same problem with discussions of Uranus.

Haha. That went completely over my head. Woosh!

Reply on news.ycombinator.com