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World’s First Thorium Reactor Designed

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Re: World’s First Thorium Reactor Designed

#41

Post by swatkat »

Gravityloss wrote: post #4

Note that this very different to the molten salt LFTR design. With solid fuel it is very hard to prevent protactinium capturing neutrons, which means problems for breeding and waste and probably operational constraints as well. The LFTR is such a beautiful consistent design but it is very different from ordinary reactors. Also the title is inaccurate as different thorium reactors have been designed, built and operate…

The one mentioned in the article is Heavy Water Reactor with Thorium fuel. Here's its whitepaper: http://www.barc.gov.in/reactor/ahwr.pdf

Re: World’s First Thorium Reactor Designed

#42

Post by orbifold »

Tuna-Fish wrote: post #26
orbifold wrote: post #15

Earlier quoted context omitted.

Roughly 3-4 times as abundant as Uranium, according to http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pd... . To give you an idea on how much energy could be produced with this: A rough estimate shows that if all our current electric energy demand would be satisfied with Uranium, the reserves would run out in roughly 10 years. See http://johncarlosbaez.wordpress.com/2010/09/03/how-long-woul... .

> rough estimate shows that if all our current electric energy demand would be satisfied with Uranium, the reserves would run out in roughly 10 years. While strictly correct, this is extremely misleading. Current resources would be exhausted in a decade, but resources are defined as the known deposits extractable under current market prices. Should we actually start using a lot of uranium, the price would spike, whic…

The total known ground resources are estimated to be roughly seven times larger than the current mining reserves. So this gives you at most a factor of ten. Of course there are other unrealistic assumptions in those estimates. Realistically you would use other sources of electric energy for instance. I don't now if the Thorium reserves are roughly four times larger than the current Uranium reserves or four times larger than the amount of Uranium that could feasibly be extracted from the ground. In any case, both are only a solution for the near future, that is the next 50-100 years or so. With current technology it would not make sense to extract Uranium from the Ocean, its concentration is $10^{-9}$, it can be commercially extracted from rocks with $10^{-4}$ concentration. It does not possible to filter huge amounts of seawater for such insignificant quantities of Uranium.

Re: World’s First Thorium Reactor Designed

#43

Post by warfangle »

JohnHaugeland wrote: post #37
warfangle wrote: post #25

Earlier quoted context omitted.

The big problem with a molten salt LFTR is the materials necessary for the plumbing. Any metal will become brittle as it is exposed to the radiation emitted from the reactor core. And manufacturing ceramics into the precision pieces called for is not a solved problem. LFTR designs are fantastic, amazing, and solve a lot of problems. There is a lot of materials science to be done to make them viable, though.

You're confusing issues from pressurized reactors with LFTRs. The reason manufacturing ceramics for pressurized reactors is hard is the pressure and size involved. LFTR can be run at normal pressure at small scale; you can use a kiln as the pressure vessel if you want to. Also, no, not any metal gets brittle; inconel and hastelloy handle radiation quite well for decades at a time, as does good old fashioned nickel. B…

>You're confusing issues from pressurized reactors with LFTRs.

Nope, pretty sure I'm not. I'm well aware that LFTRs run at low (even sub-atmosphere) pressures.

>We built and ran LFTRs commercially in the 1950s in New York State and Pennsylvania

We never ran LFTRs commercially. If you know otherwise, please cite. I only know of two experimental reactors at the Oak Ridge facility: the Aircraft Reactor Experiment and the Molten-Salt Reactor Experiment.

> I don't know where you got that idea.

I got that idea from some pretty simple facts about nickel alloys (like Hastelloy N) under neutron bombardment.

When you bombard nickel with neutrons, you produce helium. When the helium builds up irregularly, the alloy becomes brittle. You can dope Hastelloy N with titanium or niobium to even out the distribution of helium deposits (this is what ORNL did) but that brings the maximum temperature down to 650C.

As well, tellurium (one of the fission products of a LFTR reactor) corrodes the grain boundaries of Hastelloy N. You can reduce this effect by doping it with niobium and keeping the UF4/UF3 ratio to less than 60.

You have to trade off lower temperatures with whether or not you want to deal with beryllium toxicity. You can replace BeF2 with a eutectic lithium fluoride/thorium fluoride composition, but that requires an increased temperature of the reactor salts. There are other problems with using beryllium, though - it produces lithium-6, which is a strong neutron poison.

You also have to filter out noble element deposits, because they don't form fluorides.

There are also serious design challenges with modifying current turbines to work with supercritical CO2 or helium. You can use supercritical steam instead, but it isn't nearly as efficient.

You also have to worry about tritium diffusion. It's small enough that it leaks through the heat exchangers.

There are issues with the rapid expansion/contraction the graphite moderator, but some are working on graphite pebble designs.

Once you throw the corrosive salts, strange reaction byproducts, and neutron bombardment into the mix, I highly doubt that 'the average body shop' could pull off the fabrication of a LFTR style molten salt reactor that could run safely for longer than a week.

Re: World’s First Thorium Reactor Designed

#44

Post by Gravityloss »

warfangle wrote: post #43
JohnHaugeland wrote: post #37

Earlier quoted context omitted.

You're confusing issues from pressurized reactors with LFTRs. The reason manufacturing ceramics for pressurized reactors is hard is the pressure and size involved. LFTR can be run at normal pressure at small scale; you can use a kiln as the pressure vessel if you want to. Also, no, not any metal gets brittle; inconel and hastelloy handle radiation quite well for decades at a time, as does good old fashioned nickel. B…

>You're confusing issues from pressurized reactors with LFTRs. Nope, pretty sure I'm not. I'm well aware that LFTRs run at low (even sub-atmosphere) pressures. >We built and ran LFTRs commercially in the 1950s in New York State and Pennsylvania We never ran LFTRs commercially. If you know otherwise, please cite. I only know of two experimental reactors at the Oak Ridge facility: the Aircraft Reactor Experiment and th…

I was surprised to hear from GE that a CO2 working fluid power plant using turbine waste heat is a thing nowadays. They have a contractor, Echogen, who provides that part.

http://www.cospp.com/articles/print/volume-14/issue-01/featu...

http://www.echogen.com/documents/why-sco2-can-displace-steam...

In ships, when fuel costs just keep on rising, that starts making sense. (There are other reasons why it might not be good though.) On land power plants, it might make natural gas electricity more competitive against coal with this better efficiency.

Though I don't see the keyword supercritical on the Echogen site yet...

Re: World’s First Thorium Reactor Designed

#45

Post by seanflyon »

luckyno13 wrote: post #21
madaxe_again wrote: post #17

Earlier quoted context omitted.

I don't understand the whole "it has to be capable of making bombs to be viable" thing. I mean, the local coal power plant can't make artillery shells, but we're not shutting it down...

Only an assumption here, but I would say its due to what to do with the waste. If the waste is useless, then we have to have a place to put it. If it has another use, then obviously we dont have to stick it in a hole somewhere. Again, totally non-researched, off the top of my head assumption.

Thorium reactors breed U-233, but not as a waste product. The U-233 is consumed to generate power. I'm not sure what the U-233 produces when it undergoes fission but I don't think the result is weaponizable.

Re: World’s First Thorium Reactor Designed

#46

Post by warfangle »

Gravityloss wrote: post #44
warfangle wrote: post #43

Earlier quoted context omitted.

>You're confusing issues from pressurized reactors with LFTRs. Nope, pretty sure I'm not. I'm well aware that LFTRs run at low (even sub-atmosphere) pressures. >We built and ran LFTRs commercially in the 1950s in New York State and Pennsylvania We never ran LFTRs commercially. If you know otherwise, please cite. I only know of two experimental reactors at the Oak Ridge facility: the Aircraft Reactor Experiment and th…

I was surprised to hear from GE that a CO2 working fluid power plant using turbine waste heat is a thing nowadays. They have a contractor, Echogen, who provides that part. http://www.cospp.com/articles/print/volume-14/issue-01/featu... http://www.echogen.com/documents/why-sco2-can-displace-steam... In ships, when fuel costs just keep on rising, that starts making sense. (There are other reasons why it might not be go…

Oh neat, I didn't know about that either.

Re: World’s First Thorium Reactor Designed

#47

Post by Jach »

Tloewald wrote: post #27
madaxe_again wrote: post #18

Earlier quoted context omitted.

Disagree. Religion is the vehicle. Inequality is the driver.

There were/are religious conflicts in communities where it's impossible to tell the belligerents apart -- ethnically, economically, you name it. "For every complex problem there is an answer that is clear, simple, and wrong." Inequality is definitely a contributing factor, perhaps even _the_ contributing factor, but don't count out religion.

Inequality is the wrong diagnosis. As msandford pointed out, it's more likely to be a minimum standard of living issue and having enough to lose. If inequality was a main factor, you would expect Pakistan to have similar crime rates as Sweden, when in reality they're not even close. (PG has an essay on inequality being a boon to a nation's economy: http://www.paulgraham.com/inequality.html) You could also look at the religiosity of a country, but the trend there is that lower standards of living correlate with higher religiosity. (http://www.gallup.com/poll/142727/religiosity-highest-world-...) I'm more inclined to think the causation goes from low standard of living --> religiosity rather than the other way around, given the United States. However there could be other deeper factors that give rise to a low standard of living, such as a nation's average IQ -- you're not going to see a nation with average IQ of 70 outperform let alone match a nation with average IQ of 100 in terms of standard of living.

Re: World’s First Thorium Reactor Designed

#48

Post by spenrose »

DennisP wrote: post #39
spenrose wrote: post #24

The problem with nuclear power is not the primary fuel; it's the economics, especially the economics of big engineering: http://www.carbontax.org/blogarchives/2013/11/21/why-officia... http://www.forbes.com/sites/energysource/2014/02/20/why-the-...

From the first link: "In those decades parts of plants were built, ripped out and rebuilt because of design and regulatory problems, leading to ruinous costs." I've read about this before. Companies start building plants based on existing regulations. Along the way, the NRC changes the regulations, requiring tear-down and rebuilding. Meanwhile interest on the loan keeps building up. Add further delays due to politica…

The interweaving of complex shifting regulations with the economics of $B plants that take decades to build and involve tremendous amounts of radiation and energy is not some random coincidence, nor is the absence of Buffets and Icahns lining up to make a killing on the erstwhile Future of Clean Energy (as opposed to wind and solar). If thorium can't solve the political economy problems, then thorium is dead. A small loud group of techies yelling "don't you get it?!" and upvoting thorium posts on HN is just part of the ??? between underpants and the profit we will never see.

Re: World’s First Thorium Reactor Designed

#49

Post by DennisP »

spenrose wrote: post #48
DennisP wrote: post #39

Earlier quoted context omitted.

From the first link: "In those decades parts of plants were built, ripped out and rebuilt because of design and regulatory problems, leading to ruinous costs." I've read about this before. Companies start building plants based on existing regulations. Along the way, the NRC changes the regulations, requiring tear-down and rebuilding. Meanwhile interest on the loan keeps building up. Add further delays due to politica…

The interweaving of complex shifting regulations with the economics of $B plants that take decades to build and involve tremendous amounts of radiation and energy is not some random coincidence, nor is the absence of Buffets and Icahns lining up to make a killing on the erstwhile Future of Clean Energy (as opposed to wind and solar). If thorium can't solve the political economy problems, then thorium is dead. A small…

As I implied above, it's a problem in particular jurisdictions, not necessarily everywhere. China for one is aggressively pro-nuclear. If thorium reactors are everything their advocates think they are, countries that throw too many obstacles in their path will disadvantage their economies.

Aside from that, nuclear reactors don't necessarily have to be gigawatt-size. Even in the U.S., smaller reactors are starting to make some regulatory headway.

But even conventional 1GW reactors don't have to take decades to build. China's first AP-1000s at Sanmen are being finished up this year and next for a construction time of five years.

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

http://www.world-nuclear-news.org/NN-First-Haiyang-AP1000-ta...

Re: World’s First Thorium Reactor Designed

#50

Post by spenrose »

DennisP wrote: post #49
spenrose wrote: post #48

Earlier quoted context omitted.

The interweaving of complex shifting regulations with the economics of $B plants that take decades to build and involve tremendous amounts of radiation and energy is not some random coincidence, nor is the absence of Buffets and Icahns lining up to make a killing on the erstwhile Future of Clean Energy (as opposed to wind and solar). If thorium can't solve the political economy problems, then thorium is dead. A small…

As I implied above, it's a problem in particular jurisdictions, not necessarily everywhere. China for one is aggressively pro-nuclear. If thorium reactors are everything their advocates think they are, countries that throw too many obstacles in their path will disadvantage their economies. Aside from that, nuclear reactors don't necessarily have to be gigawatt-size. Even in the U.S., smaller reactors are starting to…

China matters, and it can bypass procedural democracy. Large, slow-to-deploy nuclear still has to compete with quick-deploying, cost-decreasing solar and wind (and serious efficiency measures) while it is on the costs-rising-due-to-learning part of its rollout curve. Procedural democracy will not allow new nuclear of any kind in most of the rich democracies. We need everything, but solar PV, wind, and efficiency are the low-hanging fruit.
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