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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Dr. Shark wrote ...
An equally worrying prospect is: what is happening with all the water 20.000 l or 5000 gallons per hour that are circulated between the compromised fuel rods and turned into steam? There is no way that all this steam can be quenched in the torus, so the plumes of smoke on the webcam are in all likelihood water that has been circulating the core, picking up all the nasty isotopes on the way. Are the radiation readings in line with this, or is there an error in my line of though?
Here we find what I'll call - politely - a lapse of journalistic curiousity. The BBC, for example, keeps refering to 'smoke or vapour' as if no one knew what it was, as if continuous real time analysis was not taking place - as if the movement of the radioactive plume was not being monitored by the Comprehensive Test Ban Treaty Organisation, who have more diagnostic gadgets at their disposal than you can shake a stick at.
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Patrick wrote ...
I did not mean to imply that natural gas be an infinite duration source. merely a 40-70 year "crutch" between now and when nuclear fusion is perfected.
EDIT: I would also like to say how stupid corn-ethanol is. We cant feed the people on the planet now... as is. and these Washington DC idiots want to turn the most valuable fuel source, difficult to grow, resource intensive fuel ...HUMAN FOOD... into something we burn by the gallon !?
No, not at all, didn't mean to sound like I was implying that. I'm well aware that there are certain kinds of people want consequence-free energy, not knowing that no such thing exists. Those people generally just demand that electricity with consequences be generated far away, so that if nothing else, they can ignore the consequences. It's funny how many people who claim to be supporters of renewable or cleaner energy get up in arms about their view being spoiled by wind farms or ugly power plants, and want their rivers and coastlines free of hydroelectric dams and tidal generating stations. I guess they expect that building a dozen wind turbines three counties over is going to fix everything.
Corn-ethanol is getting better in terms of overall efficiency. Last I checked, they were using species of corn unfit for human consumption. That's not to say that the land couldn't be used to grow edible corn, though. Still, they're doing clever things like turning the cornstalks into biomass fuel that runs the distillers, and last I saw there was actually more energy coming out of the process than going in. That doesn't really address the problems of limited crop space, potential crop failure, and so on, though.
There are some possibly more workable solutions on the horizon, such as algae reactors that produce both oil that could be used as fuel, and biomass that could be burned for energy. It needs a lot more research to even know if something like that could be commercially viable, though.
Patrick wrote ...
Dr. Shark wrote ...
...And never mind that the really bad stuff, Iodine and Cesium, are created by neutron radiation so a failing fusion plant would spew out just as much as Fukushima may be doing now.
I did'nt know that, shit.
Sad but true. Fusion (well, most kinds we know lots about) produces neutrons, so fusion reactors gradually become radioactive.
Patrick wrote ...
EDIT: Im not sure that a transmutation path exists for light elemental decompositions involving the metallic elements of a toroidal wall such that Cesium/iodine production would be possible in large quantities. Can others comment?
EDIT: I wonder if neutron nuclear cross section of fission reactor metals, vs fusion reactor metals would be different in terms of half-lives. Perhaps Vanadium instead of Chromium? Like hundreds of years versus several thousand years.
I'm not sure of that either. Just poking around, I see that ceramic is a fairly common choice to line the inside of fusion reactors. Taking a stab in the dark, let's say silicon carbide. Silicon is present in many ceramics; Si-28 is stable (and most common), Si-29 is stable, and Si-30 is stable. Si-31 has a half life of 170 years (not too good, that's short enough to be pretty active, long enough to make disposal a long-term problem). Decays to P-32 (half life 14.28 days) via beta decay, which then decays to S-32 (stable) via another beta decay. All in all, that's not too bad. It's a strong beta emitter, but shielding against beta decay is trivial.
The story for carbon looks similarly good; most carbon atoms will need to pick up two neutrons to become radioactive C-14. Half life of 5730 years (active, but not too active) and decays via beta decay to stable N-14.
Tungsten carbide looks popular as well. Tungsten would mostly be at risk of picking up neutrons to become W-185, decays via beta decay to Re-185 (stable). Half life is only 75 days, though, so storage until it becomes safe doesn't look too difficult. W-187 is possible as well, half life of about a day, decays via beta to Re-187, which has a half life of over 40 billion years, so is not very active at all. It ends up being about 1/7th as active as U-238, and again decays via beta (or rarely alpha) emission, so while it's not something you'd want around if you could help it, it wouldn't be a large hazard to store.
That's just a stab in the dark. It's hard to say what the lining of fusion reactors will be made of eventually, but the situation seems better by far than with fission. Future designs will probably end up balancing the durability of the lining against how bad the used lining will be.
Of course, aneutronic fusion promises to solve this problem completely, or at least greatly reduce it, but aneutronic fusion is really in its infancy and may be quite a long time away -- although to be honest, any kind of commercial power production from fusion seems a long way off at this point.
Proud Mary wrote ...
Here we find what I'll call - politely - a lapse of journalistic curiousity. The BBC, for example, keeps refering to 'smoke or vapour' as if no one knew what it was, as if continuous real time analysis was not taking place - as if the movement of the radioactive plume was not being monitored by the Comprehensive Test Ban Treaty Organisation, who have more diagnostic gadgets at their disposal than you can shake a stick at.
If it's steam coming from the spent fuel pools, it's not likely to be radioactive enough to worry about, unless the the fuel is badly damaged and fissioning again. Coming from the core, though, I'd imagine it could at least be picking up some of the more volatile iodide salts. Maybe hydrogen iodide? Anyone know enough to comment on what else steam might be hot enough to carry? If it's smoke, on the other hand, I'd imagine it could be carrying all sorts of nasty things. Hopefully most of it is blowing out to sea rather than falling back on Japanese soil, but the silence on the matter is rather eerie.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I'll expand on this a bit later, but, off the top of my head, a few points about fusion.
Firstly, the fusion reaction requires power in order to happen, so there is no possibility of a 'runaway reaction' in the event of failure. This is the main advantage.
secondly, I understand that the idea is to use the energy from the neutrons to heat lithium, this is then used to heat water, and also, the by-products from neutron-lithium reaction is tritium, which is used as a fuel.
Thirdly, I assume they are experimenting with boron and beryllium based compounds, although they are probably trying all sorts for sheilding/containment of lithium. This is where the research is focussed at the moment. the linings for the reactor and their resistance to neutron bombardment.
fourthly, aneutronic fusion like boron-proton or lithium-proton is not likely to happen for a very, very long time.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Chris Russell wrote ...
If it's steam coming from the spent fuel pools, it's not likely to be radioactive enough to worry about, unless the the fuel is badly damaged and fissioning again. Coming from the core, though, I'd imagine it could at least be picking up some of the more volatile iodide salts. Maybe hydrogen iodide? Anyone know enough to comment on what else steam might be hot enough to carry? If it's smoke, on the other hand, I'd imagine it could be carrying all sorts of nasty things. Hopefully most of it is blowing out to sea rather than falling back on Japanese soil, but the silence on the matter is rather eerie.
Might not the nanoparticles characteristic of spent uranium dioxide become entrained in a mixed-phase aerosol of water vapour produced by violent ebullition, and water vapour condensing around nano nuclei as it rises and cools?
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Japan explains the nuclear crisis... with poop. Yes, poop. See:
> Firstly, the fusion reaction requires power in order to happen, so there is no possibility of a 'runaway reaction' in the event of failure. This is the main advantage.
Quite true. A worst-case catastrophic failure of a D-T reactor could still vent significant amounts of tritium into the environment, presumably in the form of tritiated water. Fortunately, tritiated water should disperse through the environment pretty quickly, representing only a short-term hazard rather than a long-term contamination. (temporary evacuations instead of forbidden zones)
> secondly, I understand that the idea is to use the energy from the neutrons to heat lithium, this is then used to heat water, and also, the by-products from neutron-lithium reaction is tritium, which is used as a fuel.
That should take care of most of the neutrons, but unfortunately it seems likely that there will still be parts of the reactor lining that will become radioactive over time. Careful design should limit just how bad this waste will be, however.
> fourthly, aneutronic fusion like boron-proton or lithium-proton is not likely to happen for a very, very long time.
Definitely. It's the most promising in the very long term, but we've got to learn to crawl before we can walk.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
What about the LDX? this has been proven by research to be far more effective at containing plasma than a tokamak but receives 1/1000th the funding. If you ask me ITER is a huge money sink and this could be better spent financing 10 or so different designs and picking the best two for further financing.
EDIT:- someone suggested possible nickel/deuterium hot fusion as the reactions are very similar and a N-D plasma could be contained without anywhere near as much hassle as a D-T plasma in an LDX-like device due to favourable geometry with the reactions occurring at "hot spots" rather than the plasma volume as with a conventional tokamak.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Should a discussion on types of fusion be in a new thread?
From what I've briefly read about LDX, it is still in the embryonic stage and, because deuterium is used as a fuel, it will have the same problems with neutron bombardment of the reactor as tokamaks do. (although the neutrons are not as energetic)
Other 'so called' fusion experiments, like the Z-Pinch funded by the US government are just covers for weapons research, since the ban on testing.
All of the tokamak technology has now been proven by JET and other facilities. ITER will produce 500Mw output for 50Mw input. The only problems remaining to be overcome are the linings/lithium containment.
All the other fusion systems (polywells, laser systems) still have other huge problems to be overcome.
Fission reactors were a by-product of the atomic weapons program, this is why they recieved the funding to be developed so quickly.
Maybe the events in Japan will result in the accelerated development of materials for lining ITER and will result in the ITER program being 'speeded up'.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Radiation data from Japanese disaster starts to filter out Confidential data held by nuclear test ban organization emerging as key to monitoring Fukushima radiation.
Declan Butler Nature News Published online 17 March 2011 | Nature | doi:10.1038/news.2011.16
Nature revealed earlier this week than an international agency set up to detect nuclear tests, the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), is transmitting detailed data on the spectrum of radionuclides and their levels in the air in and around Japan and the Asia-Pacific region to its member states each day, but that the CTBTO could not release these data to the public because it lacked a mandate to do so.
Now, at least one CTBTO member state, Austria, intends to make some of the data public in the form of summary reports and forecasts of global radiation spread.
Nature has also learned that initial CTBTO data suggest that a large meltdown at the Fukushima power plant has not yet occurred, although that assessment may change as more data flow in during the coming days. Lars-Erik De Geer, research director of the Swedish Defence Research Institute in Stockholm, which has access to the CTBTO data and uses it to provide the foreign ministry and other Swedish government departments with analyses, says that the data show high amounts of volatile radioactive isotopes, such as iodine and caesium, as well the noble gas xenon. But so far, the data show no high levels of the less volatile elements such as zirconium and barium that would signal that a large meltdown had taken place — elements that were released during the 1986 reactor explosion in Chernobyl in the Ukraine.
Rather, the data sit well, he says, with a scenario wherein the main release of radioactivity has come from the release of excess pressure in the containment vessels of affected reactors, and the subsequent explosion of the evacuated hydrogen-laden steam within the reactor buildings. The radioactive plume will spread around the hemisphere within weeks, he predicts, but the levels of radioactivity outside Japan will not be dangerous. The levels in Japan itself, outside the immediate vicinity of the Fukushima power plant, "wouldn't scare me", he adds. Watchful waiting
De Geer and other scientists are keenly awaiting the fresh data that they will receive from CTBTO over the next few days. Initial data from a station near Tokyo were corrupted because the collection filters used in the sensors were contaminated earlier this week during handling when a plume of radioactivity fanned over the station building, according to Gerhard Wotawa, a researcher at Austria's weather service, the Central Institute for Meteorology and Geodynamics in Vienna. That situation has now been resolved and better data are expected from tomorrow, he says.
The centre this week published maps of radioactive spread based on atmospheric transport models, which incorporate weather forecasts. (See this animation of the predicted course.) Given prevailing winds, plumes of low levels of radiation are expected to travel across the Pacific Ocean and reach the western seaboard of the United States by the end of the week. Stations in Russia are starting to pick up increases in radioactive noble gases, says Wotawa, and stations outside Japan are likely to start detecting higher radionuclides levels in the coming days.
The CTBTO data come from a worldwide network of radionuclide particulate monitoring stations operated by the Preparatory Commission of the CTBTO, a Vienna-based body set up to build a verification regime for a global ban on the testing of nuclear weapons, so that this network will be operational when enough of the organization's member states have ratified the treaty for it to enter force. The organization monitors radionuclide, seismic, hydroacoustic and infrasound characteristics at stations across the globe to check for the tell-tale signals of a nuclear bomb test.
The CTBTO has 60 radionuclide particulate monitoring stations in operation, and two of these are in Japan, near Tokyo, with dozens of others, often on islands, throughout the Asia-Pacific region (see map ). It also has instruments to monitor noble gases, such as xenon. These stations monitor the air continuously, and so have extensive data on any radionuclides projected into the atmosphere during the ongoing nuclear disaster.
Animated plume forecast:
The data would be of enormous public interest as they would provide a far fuller picture of the extent and spread of any current or future radioactive release from the major Japanese nuclear accident now under way. But although the data are being made available to member states and their radiation protection services, the CTBTO cannot make them public.
The CTBTO does make available its hydroacoustic and seismic data — among the most reliable and rapid around — for the purposes of tsunami warnings, and indeed these data contributed to the rapid alerts issued by tsunami warning systems following the 9.0-magnitude earthquake. The agency's member states agreed to this after the 2004 Indian Ocean tsunami. But the CTBTO has no mandate for making radionuclide data publicly available for the purposes of monitoring nuclear accidents, because its member states have not yet agreed for it to have this role — although it does have a mandate to release radionuclide data on nuclear tests (see, for example, 'North Korea's ignoble blast').
Yet its radionuclide network is also well adapted to monitoring levels of radiation in the fallout from nuclear accidents — it is still picking up radioactive caesium-137 (which has a 30-year half-life) from the 1986 Chernobyl reactor explosion in the Ukraine, for example — and its website lists such work as one of the civil benefits of its network of monitoring stations.
Each particulate monitoring station sends one γ-ray spectrum per day, a two-dimensional plot showing which radionuclides, and how much of each, occur in its sampling. Nuclear accidents produce a spectrum of radioactive fission products, including various radioisotopes of iodine, caesium and zirconium. The network can pick up all of them, says Lassina Zerbo, director of the CTBTO Preparatory Commission's International Data Centre Division in Vienna.
De Geer criticizes the secrecy surrounding CTBTO data. "For me it is absolutely clear: all this should be totally open," he says. "The CTBTO is a complicated organization; certain member states want all data to be classified, so they are not allowed to be given out, " says De Geer, who was formerly head of the CTBTO's Radionuclide Development Unit. Even freeing the tsunami-relevant data "took years of discussion", he says.
He believes that the national laws of Sweden, a CTBTO member state, give it the right legally to "do what we want with the data", adding that the issue of the confidentiality of the data is nonetheless still a "grey zone". Wotawa likewise believes that Austria has the right to use the data, and says that his centre will be publishing CTBTO data in the daily updates of the Fukushima fallout that it is providing on its website.
Zerbo says that the CTBTO's radionuclide monitoring service would be well placed to take on any international role in monitoring nuclear accidents for radiation protection purposes. "Japan and other countries have their own national radiation protection services, but where we could be useful is the worldwide nature of our monitoring network", he says. "We are the only truly worldwide radionuclide monitoring network." In a step towards that role, the CTBTO and the International Atomic Energy Agency in Vienna yesterday agreed to cooperate.
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______________________________________________ Stella says: Watching the animation of the radioactive plume snaking out over the sea, who couldn't help but recall the terrible fate of the Japanese fishing boat Lucky Dragon 5 all those years ago? They won't have forgotten about it in Japan.
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Nuclear events taking place in Japan.
