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Is Safe, Green Thorium Power Finally Ready For Prime Time?
MrSeb writes "If you've not been tracking the thorium hype, you might be interested to learn that the benefits liquid fluoride thorium reactors (LFTRs) have over light water uranium reactors (LWRs) are compelling. Alvin Weinberg, who invented both, favored the LFTR for civilian power since its failures (when they happened) were considerably less dramatic — a catastrophic depressurization of radioactive steam, like occurred at Chernobyl in 1986, simply wouldn't be possible. Since the technical hurdles to building LFTRs and handling their byproducts are in theory no more challenging, one might ask — where are they? It turns out that a bunch of U.S. startups are investigating the modern-day viability of thorium power, and countries like India and China have serious, governmental efforts to use LFTRs. Is thorium power finally ready for prime time?"
Yeah, Global Warming and Peak Energy are going to fuck NIMBY in the ass soon.
You'd be surprised what people will put up with when basic survival is on the line.
Linux, you magnificent bastard, I read the fucking manual!
Chernobyl was a graphite moderated water-cooled reactor. Any commercial nuclear plant in the U.S. is a water-moderated and water-cooled reactor.
Despite the normal perception of the word, a "moderator" actually increases the nuclear activity in a fission plant since it slows-down ("moderates") neutrons and therefore increases the probability that the neutrons cause a fission event. In Chernobyl, the coolant (water) was blown away in the pressure explosion, but the moderator (graphite) remained in place which led to the runaway meltdown.
By contrast at Three Mile Island & Fukushima, the loss of coolant led to a meltdown (literally heat causing melting to occur), but since the water moderator was also missing, the accidents did not lead to a runaway that was anywhere near as severe as Chernobyl. If Fukushima had included a pressure vessel of the same caliber as the one used at TMI, then hardly any radioactivity would have been released during the Fukushima accident.
AntiFA: An abbreviation for Anti First Amendment.
So there is a trope in the engineering world that the safest reactors are the ones that are confined to paper studies, or, to put it more timely, to PowerPoint slides.
It's true that the LFTR reactors don't have the same failure modes as the pressurized light-water reactors, but they still have the same basic issue, namely that there is a very large amount of power-generating capacity in a relatively small volume. Even pebble-bed reactors, similarly touted as "intrinsically safe" during their design phase, have had a radiation-release accident -- scroll down to "Criticisms of the design" on that Wikipedia page. The lesson (which I learned from Charles Perrow and Fukushima) is that complex systems with high power densities are intrinsically hazardous, because unexpected interactions (which arise from the complexity) tend to be highly destructive (because of the power density). LFTRs are less complex, and so less dangerous, than PLWRs, and that's good, but it doesn't make them safe.
The stupid cliche you hear over and over again is true -- safety is a process. You can design reactors so that the safety process is easier to implement, but what actually makes things safe is conservative management schemes that retain the redundancy and margin for error that the process demands, and not cutting them out because of the money, or, worse, because of complacency induced by faith in the design.
There's another industrial safety joke, particularly applicable to complex systems -- accident analysis consists of filling in X and Y in the phrase, "Nobody imagined X could happen whlie Y was true."
2*3*3*3*3*11*251
Indeed, another great advantage of nuclear power is that whenever there's a catastrophic meltdown, we get hundreds of square kilometers of new wooded nature preserve.
Weinbergs team at Oak Ridge managed to work with the Fluoride salts. They used high-nickel alloys (Hastelloy N) which were able to resist the F salts. Other manufacturers have alloys of similar make up - I believe a Czech group are developing their own at the moment due to difficulty of supply from Haynes - google MONICR. The problems are not trivial, but they are surmountable.
So, what you're saying is, you don't like living next to a building site? What makes you think that subcontractors on wind farms are any worse in traffic than subcontractors on any other building site?
#shakes head#
I have the misfortune of living at ground zero for an ongoing wind farm build. 24/7 truck traffic, massive clouds of dust, hour plus highway shutdowns while they move their superloads, obnoxious subcontractors that ignore traffic laws, etc, etc. Then there's the ecological impact -- acres upon acres of wooded hilltops have been deforested. I truly had no idea how obnoxious it was until Google Earth got updated images. Take a look at some before and after photos of a large wind farm and see for yourself how bad it is.
Where is this exactly? Come on, don't just give us an unverifiable anecdote, give us hard facts that can be verified.
A properly designed wind farm shouldn't require mass deforestation or environmental damage.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Prohibitive corrosion is a common misconception about this type of reactor. The U.S. built an experimental MSR in the 60's and ran it for 5 years. According to the results section of the wikipedia article about the experiment, the corrosion was negligible: http://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment#Results
The article indicates that Adm. Rickover didn't like molten salt / sodium cooled reactors because the "Navy knew how to handle water". In reality, Rickover's nuclear program tried both approaches. The Nautilus (SSN-571) used a boiling water reactor, and the Seawolf (SSN-575) used a sodium cooled reactor. Both were built, both went to sea, and both performed reasonably well. But the sodium-cooled reactor turned out to be harder to maintain than the boiling water reactor, and couldn't be run at full capacity because of some design problems. so after a year, Seawolf was returned to the yards and converted to a boiling water reactor.
That was very typical of the military approach of the period - fully develop several alternatives, operate them, then dump the losers. The history of 1950s jet fighters is a striking example.
Oh no. Nation states might do bad things using their custom designed expensive reactors.
In the production of U233 from thorium-232, it is unavoidable that one will invariably produce small amounts of uranium-232 as an impurity, because of parasitic (n,2n) reactions on uranium-233 itself, or on protactinium-233. Uranium 232 is really, really bad stuff.
The decay chain of U232 quickly yields a number of different strong gamma radiation emitters, which makes manual handling in a glove box with only light shielding (as commonly done with plutonium) too hazardous. Not only will it kill you dead, its presence will also poison your weapon yield, and it will alert anyone who cares to look exactly where your weapon site is.
The thing is, any nation (or terrorist group?) with the money and the resources needed could produce weapons more cheaply and with less risk to their workers by enriching U238 into Plutonium 239, which is much better for making weapons anyway.
I think the article is fear mongering at best. Is their a proliferation risk? Sure. An exceedingly impractical risk imho.
According to wikipedia:
Quote:
The United States detonated an experimental device in the 1955 Operation Teapot "MET" test which used a plutonium/U-233 composite pit; this was based on the plutonium/U-235 pit from the TX-7E, a prototype Mark 7 nuclear bomb design used in the 1951 Operation Buster-Jangle "Easy" test. Although not an outright fizzle, MET's actual yield of 22 kilotons was significantly enough below the predicted 33 that the information gathered was of limited value. In 1998, as part of its Pokhran-II tests, India detonated an experimental U-233 device of low-yield (0.2 kt) called Shakti V.
So it has been attempted, and seems to have badly fizzled with both efforts. The bomb makers with deep pockets have quite rightly given up in disgust. If some well funded terrorist group or nation state is going to bother with trying to make a bomb, they are going to buy or steal U239 or they will build themselves a uranium reactor, then frequently load and unload fresh fuel rods so they can extract plutonium. Nobody is likely to ever again give bomb making with U233 much additional effort.
Anybody trying to extract the Protactinium from a LFTR in the hope of making U233 will find the neutron economy is such that they simply have to load all that U233 right back into the reactor or the thing will shut down.
U-232 is also produced in LFTR reactors, and is HELLACIOUSLY radioactive. You can't work around U-232 with just a glove-box - you're gonna get a tan that way. It also poisons the reaction of a U-233 bomb, so you've got to separate it out, so you're back to centrifuges and the like, and you're gonna have to throw out the contaminated and radioactive centrifuges when you're done as well.
Meldroc, Waster of Electrons
Interesting article.
One unexpected finding was shallow, inter-granular cracking in all metal surfaces exposed to the fuel salt. The cause of the embrittlement was tellurium - a fission product generated in the fuel. This was first noted in the specimens that were removed from the core at intervals during the reactor operation. Post-operation examination of pieces of a control-rod thimble, heat-exchanger tubes, and pump bowl parts revealed the ubiquity of the cracking and emphasized its importance to the MSR concept. The crack growth was rapid enough to become a problem over the planned thirty-year life of a follow-on thorium breeder reactor.
So not quite as problem free and viable in the long term as you were hoping. Long term operation is in fact one of the biggest problems for thorium reactors. Even if the salt doesn't damage them the reactor vessel itself becomes highly radioactive and thus difficult to examine and maintain. Decommissioning is similarly problematic.
That's one reason no-one has built a commercial scale plant. It's a long term investment and there are many uncertainties about reliability over 40+ years, where as current designs are at least proven to mostly work at reasonable cost for that kind of lifetime.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Wow man, chicken little much? Yes a liquid sodium reactor would react in a very violent way to a water intrusion... but the whole system isn't PRESSURIZED. The byproducts of a LFTR reactor are orders of magnitude LESS radioactive than the byproducts of a LWR, and ALL the fuel is used. None of it is left to lanquish in your vaunted zirconium steel (which by the way, are cracked and fissured by end of life due to the temp and flux in the core). The whole concept of the LFTR is it's 'safe mode' is to freeze like you intimate. You simply heat it back up to unplug the channels. The chemical separation portion of the reactor is a fairly simple and non-complex affair, unlike the current enrichment facilities for uranium processing and could easily be managed by a small group of chemists at about the level of complexity used to make freaking beer. There's also NO possibility of a 'china syndrome', and it can't go BOOM no matter what you do. If Fukishima had been an LFTR reactor we would never have even heard about it, because when the power went out, the freeze plug would melt and the entire contents of the core would have drained into the safety tank and cooled into a solid. When they were ready, you just heat it back up and start pumping again. Hell, even the quantity of reactants in the core at any one time is miniscule compared to a LWR, so even if there WERE a catastrophic event and the fissionables were released they effect would be marginal compared to the radioactive MESS you have with a plant like Fukishima. Bottom line man.. they freaking guy that owned the patent (read that as the acclaimed inventor of) nuclear power said LFTR was far better, both in efficiency and safety. And that was with 1950's tech. I imagine we could do a bit better now.
If I sound stupid, it's not me talking....