Uranium Is So Last Century — Enter Thorium, the New Green Nuke

[tinrobot]

At the time, in 2000, Sorensen was just 25, engaged to be married and thrilled to be employed at his first serious job as a real aerospace engineer. A devout Mormon with a linebacker’s build and a marine’s crew cut, Sorensen made an unlikely iconoclast. But the book inspired him to pursue an intense study of nuclear energy over the next few years, during which he became convinced that thorium could solve the nuclear power industry’s most intractable problems. After it has been used as fuel for power plants, the element leaves behind minuscule amounts of waste. And that waste needs to be stored for only a few hundred years, not a few hundred thousand like other nuclear byproducts. Because it’s so plentiful in nature, it’s virtually inexhaustible. It’s also one of only a few substances that acts as a thermal breeder, in theory creating enough new fuel as it breaks down to sustain a high-temperature chain reaction indefinitely. And it would be virtually impossible for the byproducts of a thorium reactor to be used by terrorists or anyone else to make nuclear weapons.

Weinberg and his men proved the efficacy of thorium reactors in hundreds of tests at Oak Ridge from the ’50s through the early ’70s. But thorium hit a dead end. Locked in a struggle with a nuclear- armed Soviet Union, the US government in the ’60s chose to build uranium-fueled reactors — in part because they produce plutonium that can be refined into weapons-grade material. The course of the nuclear industry was set for the next four decades, and thorium power became one of the great what-if technologies of the 20th century.

.....

Even better, Weinberg realized that you could use thorium in an entirely new kind of reactor, one that would have zero risk of meltdown. The design is based on the lab’s finding that thorium dissolves in hot liquid fluoride salts. This fission soup is poured into tubes in the core of the reactor, where the nuclear chain reaction — the billiard balls colliding — happens. The system makes the reactor self-regulating: When the soup gets too hot it expands and flows out of the tubes — slowing fission and eliminating the possibility of another Chernobyl. Any actinide can work in this method, but thorium is particularly well suited because it is so efficient at the high temperatures at which fission occurs in the soup.

In 1965, Weinberg and his team built a working reactor, one that suspended the byproducts of thorium in a molten salt bath, and he spent the rest of his 18-year tenure trying to make thorium the heart of the nation’s atomic power effort. He failed. Uranium reactors had already been established, and Hyman Rickover, de facto head of the US nuclear program, wanted the plutonium from uranium-powered nuclear plants to make bombs. Increasingly shunted aside, Weinberg was finally forced out in 1973.

http://www.wired.com/magazine/2009/12/ff_new_nukes/all/1

---

I'm usually not a nuclear advocate, but this seems interesting.

[FreakinDJ]

1. Indeed

[Statistical]

2. We will shift to Thorium eventually.

Main issue w/ Thorium today is an established Uranium fuel cycle, higher cost of Thorium reactors, and lack of economies of scale.

If Uranium fuel was unlimited we likely would never use Thorium but it isn't. As uranium supply dries up cost will exceed Thorium also a reactor operating building a new reactor designed to run 50 years (plus another 50 years after rebuild) will want a stable supply of fuel.

I expect Thorium reactors to be used for commercial power in next couple decades.

[FreakinDJ]

3. Why - by that time will be building Nuke Fusion Plants

[Ian David]

4. We'll need the fusion plants to reduce all the fission waste to plasma. n/t

[FreakinDJ]

5. You WIN the Prize

[formercia]

6. Convert the waste into fuel for thermoelectric generators.

I'd be glad to take a SNAP reactor. Free electricity for the next couple of generations.

[Ian David]

8. I was wondering how many smoke detectors I'd need to buy to build a nuclear cellphone recharger. n/t

[MH1]

10. Cost - what if government didn't subsidize nuke insurance?

would that make thorium reactors more competitive?

[Statistical]

11. Thorium reactors would need the same insurance "subsidy".

You are aware that the govt "subsidy" simply pays any claims beyond $10 billion (which has never happened).

Each plant has a private insurance policy in amount of $300 million (costs about $400K per reactor per yer).
All the plants pay into a collective fund to cover damages up to $9.7 billion
Any claims that exceed the private insurance and fund which would be a claim greater than $10 billion will be paid by the govt.

Seeing as this has never happened to date it has cost taxpayers exactly $0.00.

Thorium reactors would require the same coverage and would have the same "cost".

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/funds-fs.html

[MH1]

13. Why would thorium reactors require that coverage if they don't have the same risks?

Disclaimer: I am not a nuclear engineer, I don't play one on TV, and I didn't stay at a Holiday Inn Express last night.

But I did read the article (in the op) and I do have some experience with the concept of risk management. I am not asking about what it costs to the taxpayer. I am asking a question about the risk factors influencing investment. The high risk associated with uranium reactors has been backstopped by the US government.

But the article you linked does not mention thorium, so I presume it doesn't get into the differences. I am also presuming that thorium reactors would not necessarily be covered by Price-Anderson. Based on the Wired article, it sounds like they wouldn't need to be. Or maybe they would, but the risk would be substantially less.

Anyway the point is that investment in new plants incurs substantial risks. The risk to investors for uranium reactors is capped by the government, so the true cost of insuring for potential accidents will not be used when an investor assesses the risks of investing in uranium vs. thorium reactors.

Maybe that's irrelevant in the overall scheme of things. But - assuming the Wired article is basically correct in the benefits of using thorium vs uranium - it seems we should be aware of all the barriers to investment.

Disclaimer #2: I work for a company that profits substantially from the power industry, including nukes. To my exceedingly limited knowledge, it would probably make no difference to our company if new nukes being built were uranium or thorium based; but any new nukes (or conversion to seed-and-blanket, for example) would be good for my job security. That said, I am not particularly pro-nuke, but I am anti-proliferation and anti-waste.

[Statistical]

15. Any reactor can melt down. The article is somewhat polyanna in that case.

Modern Gen III+ reactors like AP1000 can scram with no human interaction, and cool the reactor using natural forces (gravity, convection, circulation).

With no humans, and no electricity an AP1000 will shut itself down. However it is still subject to same insurance requirements older Gen II reactors are.

The frequency of core damage (cdf) varies massively between reactor designs.
Core damage doesn't necessarily mean a meltdown but rather an event that *could* lead to a meltdown.

Compare cdf of a typical Gen II reactor (BWR/4) with newest gen III+ reactors
BWR/4 1e-5 (one every 100,000 years)

AP1000 reactor 2e-7 (one every 7 million years)
EPR reactor 6e-7 (one every 20 million years)
ESBWR reactor 3e-8 (one every 300 million years)

however in most peoples minds all reactors are equally dangerous. There is no need for reactors like AP1000 to be treated the same as 5 decade old BWR reactors however they are.

While Thorium reactor designs *may* be even safer they still can fail. Nothing is failure proof just failure resistant.

I am 100% convinced any Thorium based reactor would be subject to Price-Anderson same as all other power generation reactors in the US.

[tialsedov]

17. Yes, but you have to examime what "failure" is for LFTR.

The fuel in LFTR is *already melted*...thus "Liquid" in the name.

It runs at operating atmospheric pressure so there is no chance of a pressure explosion.

It has no water only hot gas so there is no chance of a steam explosion.

If it gets to hot, the chain reaction goes away.

So...I think it's fair to predict that the rules have to be rewritten based on what *could* occur, P-A probably wouldn't be needed.

P-A, which is actually a very good deal, IMO, is part of the belief that if there is a meltdown, it would irradiate an area the size of the state of Maryland. We already had a meltdown and it was contained very well and no on died. So...the rules should change that nuclear reactor should be self-insured for only the reactor and the very close surrounding area, period. In effect...the way it is now...Price Anderson hasn't paid a penny. LFTRs will be even easier to insure.

[struggle4progress]

7. By 1977, Weinberg had written "Can the sun replace uranium?" in which he considers

the prospects for uranium or thorium fission and solar energy. Weinberg took the view, still corroborated by experience to date, that fusion will never be viable. He also dismisses geothermal energy sources as inadequate. It is clear from "Can the sun replace uranium?" that the global warming issue associated with CO2 from fossil carbon was already appreciated in those days. Among the issues associated with fission, he notes wastes disposal, remarking that nobody really considered the long-term issues in the early days of fission power; after some discussion, he concludes that 7000 working reactors would be needed worldwide, and that 150 would be built every year for replacement purposes; he considers the waste disposal problem formidable

The paper can be downloaded in pdf format here: http://www.osti.gov/servlets/purl/5248737-yrhSb1/

[madokie]

9. This could be something that many of us could live with

Why aren't we building them now instead of the potential bomb making by product kind like they're using today. Nuclear power will or has not anyway shown that it can ever be self supporting so if we're gonna have to pick up the tab lets pick up a little bit bigger but way safer one.

Our present nuclear power plants have to go though as soon as we can do it. Enough poison already

[Statistical]

12. Thorium isn't a magic bullet.

http://en.wikipedia.org/wiki/Thorium_fuel_cycle



1) Thorium by weight is mostly Th isn't fissable. It requires some enriched uranium to "start" the chain reaction (turning Th231 ->U233). The U233 is what actually "runs" the reactor. So you insert Th231 and spare neutrons from seed Uranium converts it to U233 which can then under go fusion (producing heat -> steam -> electricity).

2) There are still "poisons". The spent fuel is radioactive and must be stored safely. The main advantage is the composition of the fuel making producing weapons extremely difficult. Also less actinides means you end up with less bizarre combination of isotopes.

3) It would be wasteful beyond comprehension to shut down existing reactor and then build a Thorium reactor to replace it. Rather the transition will take a century. As uranium stockpiles dwindle Thorium reactors will be built. Over time as existing reactors reach end of life (next 20-60 years) they will be scrapped and Thorium reactors built to replace capacity.

The only one pushing Th reactors right now India and the only reason is they have essentially no Uranium and the world largest deposit of Thorium.

[MH1]

14. There's a lot of good news in your post

I agree that it doesn't make much sense to shut down existing (well-functioning) reactors. But there are calls for new reactor production and it seems that thorium should get a look, if only for the non-proliferation aspect alone. And less waste is also a good thing even if it isn't "no waste". (C'mon, next you're going to tell me unicorns don't exist!)

For India to get behind the R&D is very good. I'd like to see the US there too, but if not well at least India has the chops to get it done.

[madokie]

16. When I said they have to go I didn't mean to go shut them down today

but like all mechanical things they have a lifetime and when its reached replace them with something less dangerous as it sounds like TH reactors would be. Thats if we really think we can't do without that type of power production. I'm of the mind that if we let it happen we will come up with solutions to all these energy problems. Man has done some amazing things when backed up against the wall like we're at now. Fossil fuels has to go as the bulk of our generating base though, I agree with that. :hi:

[tialsedov]

18. Not, not really...

Thorium does NOT have to be enriched.

The LFTR requires only 'raw' uranium, that is, uranium that his been milled like iron ore and simply all the 'spoil', non-Th, removed: that is, dirt, rocks, gravel, sand. It can them be powered, mixed with fluoride and *poured* into the LFTR. About 7lbs a day to light a city the size of San Francisco. 7lbs. That's it. No enrichment.

Yes, the U233, the eventual decay product of Th is what actually fissiles and generates heat. But...the advantage of LFTR is that because the fuel is in a liquid or "melted" state, an inline fuel reprocessing is possible where those fission "poisons" can be removed and the burnables wants reinjected and burned up, the bad ones that are fission products, can be cleaned out of the fuel and stored.

The Indians are indeed building Th reactors right now, unfortunately they are building solid-fueled ones, but hey, it's a start.

energyfromthorium.com

DW

[Statistical]

19. I never said Th needs to be enriched.

Natural Thorium is Th 232 which is NOT fissable. Th232 is what is called fertile not fissable. It can't sustain a fission reaction however with outside neutrons it can convert into U233 which is fissable (can sustain a reaction).

Pour a bunch of Th 232 in a reactor and it will sit there for a million years and do absolutely nothing.

Th 232 requires a neutron source to transmute into U233.



So how do you get Th 232 to convert into U233?

Well a couple of methods.
a) use a neutron emitter to increase neutron density in reactor.
b) have a some enriched uranium as part of the fuel to provide initial neutron source.
c) use existing (U-235) enriched uranium reactors as breeders. Current reactors can be modified to become U233 breeders. By placing a "blanket" of Th232 around the core, some of the neutrons from the reactor will transmute the Th232 -> U233. This requires some modification of reactor and fuel though as you are no "siphoning off" neutrons from the reactor.

So my point wasn't that Th232 needs to be enriched. There is no enriching Thorium as it only has one natural isotope which is Th232. My point is that Th232 by itself is useless as a fuel source. Somehow Th232 needs to be transmuted into U233.

This requires energy and reduces available neutrons (neutron economy) in the reactor. Artificially adding neutrons to the reactor (method a) is incredibly costly (in terms of energy) and likely will never be used in a commercial power reactor.

Method b has issues in that by mixing U235 into the reaction mix you gain back all the problems of weapons proliferation, also it makes the Thorium reactor more complex. It may be used by countries with high reactor sophistication and no ploferation risk (like US).

For "risky countries" the most likely source of U233 for Thorium reactors will be a seed & blanket method in existing reactors.

Thus current uranium reactors can be modified as breeders and they will burnup U235 (enriched from raw uranium) and in the process produce power and also transmute Th232->U233.

Then "thorium" reactors will purchase U233 from the uranium reactors.

So the idea that I was addressing is that the belief we can go 100% pure Thorium is flawed. Uranium reactors aren't going anywhere if you want a large low cost source of U233.