<i>A “fast breeder” version of a molten salt reactor has fast neutrons in the reactor core. These neutrons easily interact with the actinides, transmuting them into fissile isotopes and then fissioning them to produce energy. In other words, molten salt reactors burn actinides. The same is not true for traditional uranium reactors because they have thermal (slow-moving) neutrons in the reactor core. Neutrons at these slower speeds don’t interact with the actinides, so you can’t burn actinides in a traditional uranium reactor.</i><p>This is no different from a panoply of fast breeder reactors which are NOT molten salt reactors, particularly liquid-sodium cooled (solid-fuel) reactors. The difference is that liquid sodium reactors have dozens of commercial-scale demonstrations, and hundreds of billions of $$$ of R&D investment -- whereas the molten salt fast breeders (chloride salt reactors) are nothing more than paper models to date.<p><i>As a side note, it looks like using thorium as a fuel is not actually critical. Thorium can be used as fuel in molten salt fast breeder reactor, which is a benefit for long-term sustainability, but thorium has little relation to the cost of constructing a new reactor today.</i><p>There's a plausible suggestion that liquid-fuelled reactors could be cheaper than LWRs. E.g.: they are far more compact (smaller), and the nuclear components apparently have less complexity. (Speculative)<p>But the point is an important one. The "big" selling points of thorium -- fuel efficiency, and spent fuel -- are very long-term issues. It's safe to argue they can be deferred. ("Thorium is premature optimization")<p><i>As of this past month, China now has a $350m institute with 140 PhDs plugging away on molten salt fast breeder reactors.</i><p>Actually they are thermal reactors (not fast breeders), and the focus is on solid-fuel reactors with molten salt as a coolant (although they are also considering molten-fuel reactors, as a lower priority).
Great article, I would love to see more of this kind of stuff on HN.<p>The 350 million dollar question is why the government <i>has</i> to be the sole source of funding. Obviously the cost is very high, the regulations are very intense, but where are the VCs willing to tackle this kind of "startup" (in reality it would likely be more of a public/private partnership). It's a longer view with higher cost but the payoff could be massive. Big innovation isn't going to happen if it requires congress to agree on supporting it for 10-20 years.
I'm not any kind of nuclear expert, but it sounds like the author is comparing Molten Salt Reactors to 1970s era traditional reactors:<p>"and the decay heat from these products requires continuous cooling for weeks even after core shutdown. That cooling process also must be human managed and actively powereed."<p>My understanding is the reactors currently under construction in the US are being built with passive fail-safes that make them much safer than the 1960s/70s reactors. Is this incorrect?<p><a href="http://www.world-nuclear.org/info/inf41.html#New_build" rel="nofollow">http://www.world-nuclear.org/info/inf41.html#New_build</a>
One issue with the review of previous nuclear disasters: Chernobyl was qualitatively different than Three Mile Island and Fukushima. The latter 2 designs were both water cooled and water moderated; both suffered loss of coolant (LOC) events which resulted in the core melting from residual decay heat as described in the article, with Fukushima experiencing subsequent detonations of hydrogen gas formed from reactions with the heated fuel rods (some have claimed that this happened at TMI as well, but clearly not to the same scale). The Chernobyl design (<a href="http://en.wikipedia.org/wiki/RBMK" rel="nofollow">http://en.wikipedia.org/wiki/RBMK</a>) is also water cooled, but is moderated by graphite, which is much more dangerous (and scary that there are still many of these in operation). Instead of a loss of coolant event, Chernobyl experienced an exponential power spike which pushed operating power up to 10 times normal, resulting in a series of steam explosions in the coolant lines that blew off the 2000 ton cover of the reactor, sprayed part of the core out the top to contaminate the immediate vicinity (i.e. large chunks of the graphite moderator lying on the ground outside the reactor building), and set the graphite moderator on fire. The fire then spread many more fission products into the atmosphere with the smoke to share the fun with people in a much wider area.<p>Despite what has been written about Fukushima recently, I expect that it was a couple of orders of magnitude worse than Three Mile Island, which did not result in significant amounts of radioactive material escaping from the site (depending on whose analysis you believe); Chernobyl was between 1 and 2 orders of magnitude more severe than what we know about what happened at Fukushima at this point as far as I can tell.
Thorium has an enormous potential, but R&D + regulations cost will be huge. In case of the nuclear energy, they were covered partly by military, but that would not be the case for Thorium.<p>I would be extremely happy, if instead of paying for war we would bet on that technology, but unfortunately it is rather unlikely that it will became commercial available soon. Still looks more promising than fusion reactor - ITER.
There plenty of good things about Thorium, however the advantages are generally overstated. Yes it's more common but uranium is plentiful and a small fraction of operating costs. Yes, it produces less waste but The difference is minimal. In theory it's safer, but current designs are vary safe with a multi decade track record where Thorium's is unproven.<p>So, while there are benefits the ROI on a multi billion dollor Thorium R&D progect are probably negative.
There was an interesting study by the national nuclear laboratory of the UK comparing thorium and uranium:<p><a href="http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/nuclear/6300-comparison-fuel-cycles.pdf" rel="nofollow">http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/...</a><p>the article is difficult to understand for a layman as myself but an important fact (among others) is that the uranium reserves on earth are considered to last for 100 years at 2008 levels of consumption. furthermore if demand rises, higher prices will make accessing more reserves economically viable. hence resource availability doesn't appear to be a concern for the near term future.
Back in May 2012, I happened to be on a drive while National Public Radio here in the United States was broadcasting a Science Friday story, "Is Thorium A Magic Bullet For Our Energy Problems?"<p><a href="http://www.npr.org/2012/05/04/152026805/is-thorium-a-magic-bullet-for-our-energy-problems" rel="nofollow">http://www.npr.org/2012/05/04/152026805/is-thorium-a-magic-b...</a><p>Many of the issues considered in that story are glossed over by advocates of thorium reactors. The author of the blog post kindly submitted here explicitly admits, "My last article about thorium as an alternative nuclear reactor fuel drew way more readers than I expected. I intentionally glossed over the complexities of specific reactor designs for the sake of simplicity, but in this article I want to go deeper." He mentions a number of interesting technical trade-offs involved in using thorium reactor fuel and the latest reactor designs as compared to earlier nuclear reactor designs, but the tone is still largely a tone of credulity, without a lot of examination of non-nuclear means of generating electrical power.<p>The Physics Stack Exchange discussion of thorium reactors is interesting,<p><a href="http://physics.stackexchange.com/questions/20034/what-practical-issues-remain-for-the-adoption-of-thorium-reactors" rel="nofollow">http://physics.stackexchange.com/questions/20034/what-practi...</a><p>as is the article from The Guardian in June 2011, "Don't believe the spin on thorium being a greener nuclear option."<p><a href="http://www.guardian.co.uk/environment/2011/jun/23/thorium-nuclear-uranium" rel="nofollow">http://www.guardian.co.uk/environment/2011/jun/23/thorium-nu...</a><p>Advocacy groups are already mobilizing to cast doubt on thorium reactors, with webpages like "Thorium Fuel – No Panacea for Nuclear Power"<p><a href="http://ieer.org/resource/factsheets/thorium-fuel-panacea-nuclear-power/" rel="nofollow">http://ieer.org/resource/factsheets/thorium-fuel-panacea-nuc...</a><p>(with a link to an interesting fact sheet,<p><a href="http://ieer.org/wp/wp-content/uploads/2012/04/thorium2009factsheet.pdf" rel="nofollow">http://ieer.org/wp/wp-content/uploads/2012/04/thorium2009fac...</a><p>that gets into the practicalities and economics of using thorium as a reactor fuel).<p>It's not clear yet that thorium offers any economic or political advantages over the uranium that fuels the nuclear reactor that provides much of my home electricity. The two nuclear reactors here in Minnesota result in lower-than-average cost for electricity here, compared to the rest of the United States, and have had a perfect safety record. Ongoing concern about where to store high-level radioactive waste on a long-term basis has made many politicians here reluctant ever to approve another nuclear plant in this state, despite the perfect safety record and inexpensive electricity we enjoy with the current plants. Minnesota, as a matter of state policy, is strongly promoting wind energy, fitting the wind-swept prairie geography of much of the state. I'm not aware of any part of the world where local politics would make a thorium plant more likely than another wind power plant or natural-gas-fired power plant. So maybe thorium power generation is a technical solution looking for a problem.
The troubling attitude in TR advocacy is the claims of inherent safety.<p>A sustainable energy-positive reaction can't be inherently safe. You can argue if it has better failure modes than the alternatives but it's harmful to ignore a multitude of factors which could be not yet considered.<p>The previous catastrophic failures with other reactor designs were also not exactly forethought. For instance, xenon poisoning was little studied in the beginning of nuclear era. It is not implausible some critical piece of knowledge is missing in the current evaluation of "safe" designs.<p>Another thing is too much reliance on the neat presentations. E.g. this blog refers to a freeze plug as a kind of panacea of any mismanagement. What if freeze plug fails for whatever reason? Like, tectonic activity breaks the pipework, or it's sabotaged, or groundwater leaks into the dump tanks?
I recommend the Thorium Remix 2011 for a good overview: <a href="http://www.youtube.com/watch?v=P9M__yYbsZ4" rel="nofollow">http://www.youtube.com/watch?v=P9M__yYbsZ4</a>
Apologies for the off-topic comment, but I really love the layout and style of this blog. Any chance it's not a custom jobby and someone knows where it's from?
Indian Thorium Breeding Technology: <a href="http://large.stanford.edu/courses/2011/ph241/bhattacharyya1/" rel="nofollow">http://large.stanford.edu/courses/2011/ph241/bhattacharyya1/</a> Since we don't have enough Uranium and no one would sell us, It's pretty much our only strategy.
There was a TEDx talk I saw a while back by two MIT graduates working on a "Waste Annihilating Molten Salt Reactor".<p><a href="https://www.youtube.com/watch?&v=AAFWeIp8JT0" rel="nofollow">https://www.youtube.com/watch?&v=AAFWeIp8JT0</a><p>It looks promising and they have formed a start-up,
<a href="http://transatomicpower.com" rel="nofollow">http://transatomicpower.com</a><p><a href="http://www.forbes.com/sites/pikeresearch/2012/09/27/a-pair-of-mit-scientists-try-to-transform-nuclear-power/" rel="nofollow">http://www.forbes.com/sites/pikeresearch/2012/09/27/a-pair-o...</a>
Blake Masters has a great overview from Peter Thiel's Stanford CS183 class about the future of Thorium and why it may be a very promising cleantech energy solution:<p><a href="http://blakemasters.com/post/23787022006/peter-thiels-cs183-startup-class-14-notes-essay" rel="nofollow">http://blakemasters.com/post/23787022006/peter-thiels-cs183-...</a>
As far as I know, there are no (public) models on Th reactors. The most advanced is an analytic simulation (without CFD) from a Chinese nuclear engineering lab, but nobody has a real clue about the precise input variables anyway, therefore no MC is even in sight, as of today. But marketing is well advanced.<p>And as the Japanese say, assuming we do have a functionally correct model and a Th reactor design (or designs, since there are several configurations), that still doesn't say anything about the economic aspect (I do not mean the old economic model, where the byproduct of plutonium factories were sold as energy).
See this recent EnergyFromThoriumFoundation facebook album for a historic brochure about ORNL's Molten Salt Reactor Experiment between 1965-1972.<p><a href="https://dl.dropbox.com/u/15726934/Historic_Molten_Salt_Reactor_Experiment_Brochure_ORNL_1965-1972.pdf" rel="nofollow">https://dl.dropbox.com/u/15726934/Historic_Molten_Salt_React...</a><p><a href="http://www.facebook.com/media/set/?set=a.10152449471560377.951501.10150132132910377&type=1&l=91f3ea2327" rel="nofollow">http://www.facebook.com/media/set/?set=a.10152449471560377.9...</a>
s/weapons//g<p>hmmm..
thorium reactors would still produce unmanagable high level nuclear waste (tho not as bad, not as much), and would still open up significant weapons proliferation vectors, both material and capacity. As for safety, these designs merely substitute one catastrophic failure mode (meltdown) for another (volatility of the continuous onsite reprocessing)<p>inarguably, thorium designs offer stepwise improvements to the major disqualifications of catastrophic failure, unmanagable waste production and WMD prolifertaion. But I'm concerned that we should judge the nuclear industry on its present day detriments and hazards, not the promises of future designs.<p>there's a big thorium mine down the road from me - well, a big rare earths mine, where the dominant product is thorium. They're planning to come and bury all the (enriched) thorium back on site after extracting the lucrative rare earths. I read that as a pretty clear indication of the state of the market. (incidentally, and as far as minesite impacts go, the thorium mine is going to be at least as hazardous as a comparable uranium mine)<p>When Chernobyl went off, we were told don't worry, it's an outdated design, the new reactors would never do that. When Fukushima went off, we were told don't worry, it's an outdated design, the new reactors would never do that. Who can guess what they'll tell us when Indian Point goes off?<p>this is an industry that has consistently over-promised and under-delivered. Remember "energy too cheap to meter"?<p>by their deeds, not their words. let's try to manage the industry by the realities of today, not the promises for tomorrow.
Of course thorium reactors is not a proven technology but if there is a scientific consensus saying it is promising, I don't see why utility companies and civil nuclear reactor manufacturers try to make it viable. They have everything to gain, in my opinion.<p>Tldr of the article: <a href="http://tldr.io/tldrs/50f73bbe983c81b86a00012b/thorium-reactors" rel="nofollow">http://tldr.io/tldrs/50f73bbe983c81b86a00012b/thorium-reacto...</a>
I've got one question...<p>The main issue is that now at Fukushima there are products like Cesium-90 in the sea, contaminating the entire sealife, which have crazy long half-life (ninety years). Thankfully they're "heavy" so they go down towards the center of the earth, but only at about 5 cm per year. So in ten years the're going to be highly radioactive Cesium-90 at 50 cm behind rocks still polluting the sealife.<p>In case the worst sh<i>t happens: the worst SNAFU conceivable...<p>Would MSRs also generate highly products like Cesium-90?<p>I mean: I don't care about all the security and the great design meaning an uncontrolled reaction shall never happen.<p>I know: it won't happen. Just like Fukushima. It didn't happen because it couldn't.<p>We got your point. It IS safe.<p>But I tell you: a sh</i>t you didn't expect is going to happen (maybe an asteroid striking your reactor or whatever).<p>What then?<p>Would MSRs pollute less than Uranium based reactors in the worst of the worst scenario?<p>If so I'm all for it.