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?"
Technolopgy is not the problem. (Score:3, Interesting)
One of the units at San Onofre is indefinitely off line because an upgraded heat exchange system was designed incorrectly. This is not exactly new technology, but somehow a flawed design made it through all the review processes. This is ultimately a organizational failure, not a technical failure.
Going from uranium to thorium will not make any difference in the long term. Serious nuclear accidents are low probability events will hugely destructive outcomes. Any claims that a technology change will result in a safe system is dangerously naive thinking.
Re:Never? Well, hardly ever [Re:NO] (Score:5, Interesting)
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.
Re:NO (Score:5, Interesting)
Uranium-233 is produced in LFTR's. It is perfectly suitable for bombs. The neat thing is that it is "easy" to separate since it is chemically different from the rest of the molten salt.
Admittedly nothing is ever easy around molten salts, especially not anything involving fluorine, but that kind of reprocessing is an integral part of how an LFTR will work. If you do not have equipment that could be repurposed to separate uranium-233, you probably do not have a commercially viable LFTR.
Re:Technolopgy is not the problem. (Score:2, Interesting)
Technology CAN help. Problem with current reactors is that that when mismanaged or left alone when problems happen, they go hotter and hotter. Some of proposed reactor designs are opposite of that - if system breaks, they will calm down.
http://en.wikipedia.org/wiki/Passive_nuclear_safety [wikipedia.org]
If we ever plan to have sustainable civilisation, we need 4th+ generation atomic power AND reduce the population. Only then we can think about civilization surving and expanding for next thousand of years. Without reducing population, nothing will save us. Without proper atomic power, we will be energy starved and damage environment even more.
Re:Safety is relative (Score:5, Interesting)
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.
Yes. Here's the original source of that [ecolo.org], from Hyman Rickover, 1953:
"An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off-the-shelf components. (8) The reactor is in the study phase. It is not being built now."
"On the other hand a practical reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated."
Looking at the history of reactors, almost everything other than water-cooled reactors has been an operational failure. Pebble-bed reactors have pebble jams. Helium-cooled reactors leak. Sodium-cooled reactors have fires. Boiling water reactors are basically simple devices, and even they have problems. Complexity in the radioactive side of a reactor system has not worked well in practice. The environment is hostile and the required lifetime without maintenance is decades long.
Re:Hot, liquid fluorine is too corrosive (Score:5, Interesting)
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.
Re:nuclear "green" energy (Score:2, Interesting)
nuclear accidents are actually rather non-life-threatening.
Until they aren't. Their POTENTIAL deaths is massively higher than anything else.
The difference is operational issues which is what coal has (pollution, acid rain, etc) vs failure issues which is what nuclear has. When it goes bad, it can go very very very bad. When a coal plant blows up? Extremely localized damage and you can safely walk the site immediately after any fires etc.
We *could* make coal safe from a chemical standpoint and filter the emissions but choose not to because of the cost. Nuclear you can't 'choose' to not have a failure. They simply will happen.
Re:Safety is relative (Score:4, Interesting)
The British fleet of fourteen AGRs (Advanced Gas-cooled Reactors) have been running successfully for thirty years now and some of the fleet will probably operate for another ten to fifteen years with licence extensions. Based on the earlier Magnox design, they use carbon dioxide as coolant. They're a little bit more efficient than boiling-water or pressurised-water reactors since their cores run a bit hotter. The increased efficiency doesn't make up for the extra cost of construction though since the fuel costs are so low, and no-one else outside the UK licenced the design. The next generation of nuclear reactors built in the UK will be BWR or PWR designs.
Re:NO (Score:4, Interesting)
That is, to a large degree the fault of the AGW lobby. For decades we have heard how important it is for us to go green, and the two main areas that has been focused on is getting us into electric cars and putting solar panels onto our roofs. The latter is slowly becoming possible as an energy source, but is still significantly more carbon intensive than most alternatives, and the former is just a retarded idea. Electrical cars have a carbon foot print that is at least as high as gas guzzlers, and in most cases significantly higher. In addition, the gas guzzlers are close to totally irrelevant as CO2 sources, so the Electrical Car is a terrible solution to a non-problem.
These things are easy to show, so the anti-AGW crowd has a field day with the morons in the AGW crowd. Irrespective of whether AGW is a real problem or not.
Re:What a LFTR really means (Score:5, Interesting)
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.
Re:What a LFTR really means (Score:3, Interesting)
Umm, wrong there skippy. You do NOT need huge amounts of water cooling. No cooling towers needed at all. The whole system runs at a much higher temp altogether, that's part of the design issues we have to address when building a LFTR. Current steam generators use a very 'low quality' steam to extract energy to convert to electricity. A LFTR runs bets several times hotter than a LWR. The turbines for a LFTR would be immensely smaller and more efficient than the ones used in current reactor generators and you don't have the need to use that water as cooling for the core. One of the primary advantages of a LFTR is the efficiency of the design and the extreme hot temps it runs at. A 'byproduct' of LFTR would be the ability to use all that heat to do interesting things like make clean water from salt water, making fuel from captured CO2 in the air etc etc. A LFTR plant could at one location make electricity, butanol (for cars) and a methanol alternative for diesel vehicles (both of which are practically drop in replacements for gasoline and diesel btw, no blending or other issues like alcohol) AND make clean water.