Is Safe, Green Thorium Power Finally Ready For Prime Time? 258
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?"
Chernobyl was not a light-water reactor (Score:5, Informative)
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.
Hot, liquid fluorine is too corrosive (Score:4, Informative)
Molten salt has a lot of advantages as a working fluid over water, unfortunately the major big disadvantage outweighs all the positives.
Viz. the conditions inside these reactors would be absurdly corrosive. F salts are chemically aggressive, and that aggressive increases with temperature. That is compounded by the fact that the reactor materials will also be bombarded with significant neutron fluxes, and by the presence of all dissolved decay products in the working fluid.
We simply don't have materials that can stand up for any length of time to that kind of abuse.
nuclear > "green" energy (Score:4, Informative)
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.
All of this might be worth it if wind energy scaled the same as nuclear, or could provide the same power density, but both of those are utterly impossible. You'll never match nuclear reactions for power density, and the footprint of a nuclear power plant is no larger than that of any other modern industrial concern.
Everything in life is a tradeoff, but having lived near Three Mile Island, and now living in the midst of a wind farm, I'd take the former any day of the week. You simply didn't know TMI was there, unless you happened to have cause to drive by it. Contrast that to dozens of wind turbines, visible for miles around, along with the obnoxiousness of their build process.
Nuclear and low impact hydro are the way to go for base load. Natural gas, along with wind, and solar for the peak load.
Re:NO (Score:4, Informative)
Unfortunately, by the time the evidence is clear enough for even the most ardent skeptic to take seriously, it will be too late to reverse the effects.
Re:What's-his-name's Law (Score:5, Informative)
The title of your post asks a question, that question is What's-his-name law.
Since the law in question is "If the title asks a question, then the answer is no."
Therefor it is No's Law.
Re:Hot, liquid fluorine is too corrosive (Score:5, Informative)
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.
Re:Hot, liquid fluorine is too corrosive (Score:5, Informative)
Re:Chernobyl was not a light-water reactor (Score:3, Informative)
Article wrong on sodium-cooled reactors (Score:5, Informative)
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.
Only if you can separate it from the U-232 (Score:5, Informative)
Re:What's-his-name's Law (Score:4, Informative)
In this case, Dr. No is Ian Betteridge, who coined Betteridge's Law [wikipedia.org] (though obviously the idea has been around long before him).
Re:Chernobyl was not a light-water reactor (Score:5, Informative)
Wrong in all aspects.
The spent fuel pools at Fukushima were not compromised at all during the earthquake and the tsunami or indeed after the hydrogen explosions although it was suspected they had sustained some damage at the time of the accident. After engineers gained access to the top of the reactors a month or two after the accident cameras were lowered into the pools and the fuel rod bundles appeared to be totally undamaged. Two rod bundles were recently removed from reactor 4's pool for much closer examination (they were unused with no fission products and so could be handled without the shielding precautions exposed rods would need). Those rod bundles showed no noticeable damage or deformation and only a little surface corrosion from the use of seawater to top up the pool water levels just after the accident.
The explosions were caused by overheating of the fuel elements within the reactors themselves after cooling stopped resulting in a catalytic reaction that produced hydrogen and oxygen gas via disassociation of steam. Pressure relief valves released this gas mix plus significant amounts of volatile radioactive fission products such as I-131 and Cs-134 and Cs-137 into the upper parts of the reactor buildings where the explosions occurred. Continued heating from the uncovered fuel rods in the reactors compromised the bottom of the reactor pressure vessels and some melted fuel may have made its way down into the primary containments, mixed with water and contributed to the releases.
The spent fuel rods in the pools on the reactors and in the site central pool did not contribute at all to the contamination that resulted as far as anyone can tell. The site plan posted by TEPCO states they expect to empty reactor 4's spent fuel pool by the end of 2013 after building a weather shield and a crane system on top of the damaged reactor building, and then move on to deal with the spent fuel in the pools in the other reactor buildings in turn.
Re:NO - well mabe (Score:1, Informative)
Please define 'a lot of R&D'!
We know that breeding fissle from T90 will work.
We know the heat expansion characteristics of LF coolant/moderator.
We understand most of the implications around shutdown.
We understand far to little about the chemistry of making the reactor survive for a resonable length of time.
We understand only part of the chemistry required to seperate out various byproducts (required for a LFTR to operate)
We know there is plenty of T90 around to convert.
So yes there is a LOTS of chemical engineering to be done but there are no known show stoppers at this time.
From this we can be sure that radiation leaks are very unlikely.
Whereas is would be VERY difficult for a group of raiders to swoop in and steal the fissle material.
It would be easy for, say a government, to stockpile the fissle after it cools down. Say 6 weeks or so.
What a LFTR really means (Score:5, Informative)
You have a very caustic liquid at hundreds of degrees which is infused with very large amounts of high level radioactive waste. Fission daughter products which in a regular reactor are solid and encased in zirconium steel and treated with utmost care are now free floating in something very hot, flowing and caustic. What if if there's an accident and it rains. Or a flood. The fission products are very water soluble.
Every power plant also has to be a very nasty chemical separation and reprocessing plant. Consider the contamination just in "normal" operation. And consider the people running them.
What happens if it cools off and solidifies? You've frozen radioactive waste in the pipes a multi-billion dollar plant, and you can't go in there for decades.
There aren't some failure modes of existing reactors, but there are other failure modes and problems.
It might be a good idea to have one or two, very highly regulated and operated with the utmost skill (i.e. not for profit) used to burn up actinides wastes from other reactors.
Re:Only if you can separate it from the U-232 (Score:4, Informative)
Not only that, but 232U and 233U are far more difficult to separate in a centrifuge than 235U and 238U are, by virtue of being far closer together in mass.
Besides, given how much hard radiation 232U kicks out, i'd be surprised if your average centrifuge could use it as an input without premature, costly failures. 235U isn't a particularly hard emitter of anything, it's just fissile. 232U is fucking nasty.
Re:What a LFTR really means (Score:5, Informative)
LFTR uses liquid Fluoride, not liquid Sodium. More than likely, the water would vaporize due to the extreme heat. If you want to be paranoid about liquid sodium, take a look at the US government and nuclear industry's preferred reactor type, the IFR (integral fast reactor) which uses both high pressure and liquid sodium.
Re:nuclear "green" energy (Score:4, Informative)
Coal power has rendered a good sized area including a whole town [wikipedia.org] uninhabitable for the foreseeable future. A fire started in a coal seam and just won't go out. The CO levels in the town range from harmful to deadly depending on the wind at the time. Eventually, it will all fall into a sinkhole and burn.
Re:What a LFTR really means (Score:3, Informative)
Fluoride salt used in the LFTR is not caustic. It is in fact chemically very inert. Fission products dissolved in the salt are not water soluble either.
If it cools off and solidifies, you just heat up the salt again (e.g. using electric heaters) and continue operating the reactor. Oh, and if the solidified salt comes into contact with water, nothing will happen (as it is not water soluble).
Flibe Energy is working with the U.S. military on making a small reactor that can be deployed at Forward Operating Bases during war. You don't think they would be doing that unless the reactor design is fairly resilient?