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#21
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...Nuclear MELTDOWN in Japan - a figment of an idiot's imagination
"Harold Burton" wrote in message ... In article , Sylvia Else wrote: On 13/03/2011 2:38 AM, Jonathan wrote: Look at this explosion at 47 seconds into the video. A violent hydrogen explosion, demolishing such a heavily reinforced containment building, must have been the result of a badly overheated reactor. A claim that appears to be wrong in almost every detail. What do you expect from an idiot like Jonathan? That statement is correct in every detail. Does anyone read the news? |
#22
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...Nuclear MELTDOWN in Japan, is US Threatened???
On Mar 12, 4:41*pm, Robert Clark wrote:
Battle to stabilise earthquake reactors 12 March 2011. UPDATE 6: 10.15 am GMT "Three of Fukushima Daiichi's six reactors were in operation when yesterday's quake hit, at which point they shut down automatically and commenced removal of residual heat with the help of emergency diesel generators. These suddenly stopped about an hour later, and this has been put down to tsunami flooding by the International Atomic Energy Agency (IAEA). "The loss of the diesels led the plant owners Tokyo Electric Power Company (Tepco) to immediately notify the government of a technical emergency situation, which allows officials to take additional precautionary measures. Even now, the primary focus of work at the site remains to connect enough portable power modules to fully replace the diesels and enable the full operation of cooling systems." http://www.world-nuclear-news.org/RS...e_earthquake_r... *If the main problem is just getting enough portable power there then there are portable gas turbine generators capable of putting out 10's of megawatts. You could also use the power from a nuclear aircraft carrier at a power range of 200 megawatts, though there might concern about bringing it off shore in a zone subject to tsunamis. Nuclear powered submarines would provide another means of providing portable power for the reactor cooling systems. The American Seawolf submarine uses 40 megawatt reactors and the Russian Akula class submarines operate at 190 megawatts. There would be less concern for tsunamis for submarines if operated off shore. You would still need likely to be hundreds of yards off shore for their required depth to operate. Then you would also need sufficient cabling to cover that distance. Bob Clark |
#23
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...Nuclear MELTDOWN in Japan, is US Threatened???
On Mar 12, 7:41*pm, Sylvia Else wrote:
On 13/03/2011 2:38 AM, Jonathan wrote: Look at this explosion at *47 seconds into the video. A violent hydrogen explosion, demolishing such a heavily reinforced containment building, must have been the result of a badly overheated reactor. A claim that appears to be wrong in almost every detail. Sadly, a public perception that the reactor suffered a catastrophic meltdown will probably persist, and spoil the chances of nuclear reactors being built in the future. Since power is still required, coal will be used instead. Sylvia, well japan now admits the pit at least partially melted down....... |
#24
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...Nuclear MELTDOWN in Japan, is US Threatened???
"Fred J. McCall" wrote in message ... bob haller wrote: On Mar 12, 7:41 pm, Sylvia Else wrote: On 13/03/2011 2:38 AM, Jonathan wrote: Look at this explosion at 47 seconds into the video. A violent hydrogen explosion, demolishing such a heavily reinforced containment building, must have been the result of a badly overheated reactor. A claim that appears to be wrong in almost every detail. Sadly, a public perception that the reactor suffered a catastrophic meltdown will probably persist, and spoil the chances of nuclear reactors being built in the future. Since power is still required, coal will be used instead. well japan now admits the pit at least partially melted down....... Reactors don't have "pits". You forgot to mention it might've melted in a direction other than exactly...down. (sarcasm) The whole point of this thread is the distinct lack of information due to the level of destruction from the earthquakes and tsunami which hit the area. Combined with a short timeline for any fallout to make it to the US. This is a worst case disaster, and it's entirely sensible to assume the worst case damage happened until we know differently. Ignorance is not always bliss. -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
#25
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...Nuclear MELTDOWN in Japan, is US Threatened???
Sadly, a public perception that the reactor suffered a catastrophic
meltdown will probably persist, and spoil the chances of nuclear reactors being built in the future. Since power is still required, coal will be used instead. Sylvia, Joe liberman on face the Nation today called for a moratorium on any new nuke plants till this is sorted out, in addition 23 US plants are like the japanese plants. at least 2 plants and possibly 3 are in meltdown... |
#26
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...Nuclear MELTDOWN in Japan, is US Threatened???
On Mar 12, 8:00*pm, "Androcles"
wrote: "Sylvia Else" wrote in message ... | On 13/03/2011 2:38 AM, Jonathan wrote: | Look at this explosion at *47 seconds into the video. | A violent hydrogen explosion, demolishing such a | heavily reinforced containment building, must have | been the result of a badly overheated reactor. | | A claim that appears to be wrong in almost every detail. | | Sadly, a public perception that the reactor suffered a catastrophic | meltdown will probably persist, and spoil the chances of nuclear | reactors being built in the future. Since power is still required, coal | will be used instead. | The reactor suffered a catastrophic earthquake in a region known to be prone to catastrophic earthquakes. And where did this "hydrogen" come from to produce a chemical reaction with oxygen, rather than high pressure steam? Hype hype hype hydrogen bad, hydrogen bombs and Hindenbergs. Green good. An earthquake is going to hit Los Angeles. Are they rushing to leave? No, of course not, they haven't been discovered as great movie stars yet. But when it does, please help, we need your money. Lots of money. the hydrogen gas came from the overheated reactor thats now confirmed in at least partial meltdown. historically japan hasnt been honest about nuclear accidents,and besides they dnt want to cause additional panic |
#27
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...Nuclear MELTDOWN in Japan, is US Threatened???
On Sun, 13 Mar 2011 07:49:28 -0700 (PDT), bob haller wrote:
Sadly, a public perception that the reactor suffered a catastrophic meltdown will probably persist, and spoil the chances of nuclear reactors being built in the future. Since power is still required, coal will be used instead. Sylvia, Joe liberman on face the Nation today called for a moratorium on any new nuke plants till this is sorted out, in addition 23 US plants are like the japanese plants. at least 2 plants and possibly 3 are in meltdown... A politician called for less action, more study. You needed to watch a "news" program to learn that? Does it matter which one said it? How much progress was encouraged by a politician putting the brakes on in 1979? The news says "23 US plants are like the japanese plants." It makes a scary sound bite. In what ways are they "like the japanese plants?" Are they situated near an 8+ magnitude earthquake? You want to stop burning fossil fuels (with their emission of evil CO2), and reduce dependence on foreign oil? Build nuclear power plants. |
#28
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...Nuclear MELTDOWN in Japan...look at the video again!
Compare the size of the smoke plume at the start of this video to the point before the explosion at 47 seconds. The smoke plume grows by some four times in size in just 40 seconds. Then bang! It fits the worst case scenario sequence cited below. And the govt statement a pipe burst. http://www.youtube.com/watch?v=LvC4WQrQwTs Fukushima Reactor This reactor is a Boiling Water Reactor (BWR), an early BWR mark 2 with the earliest mark 1 outer containment. Built in 1967. Most reactors today are Pressurized Water Reactors (PWR). And btw, a BWR doesn't have top mounted control rods which automatically fall if power is lost. They're bottom mounted and hydraulically inserted. And it may be the large suppression pools described below they're trying to fill with sea-water now I would guess. And it should be noted, below it states the outer containment building is designed to ...contain...a meltdown. List of BWR's http://en.wikipedia.org/wiki/List_of_BWRs Safety Systems A BWR is similar to a Pressurized Water Reactor (PWR) in that the reactor will continue to produce heat even after the fission reactions have stopped, which could make a core damage incident possible if there were not several redundant safety features built into the design of the reactor. BWRs generally have N-2 redundancy on their major safety-related systems, which normally consist of four "trains" of components. This generally means that up to two of the four components of a safety system can fail and the system will still perform if called upon. http://en.wikipedia.org/wiki/Boiling_Water_Reactor From Wiki.... Boiling water reactors In a BWR, the containment strategy is a bit different. A BWR's containment consists of a drywell where the reactor and associated cooling equipment is located and a wetwell. The drywell is much smaller than a PWR containment and plays a larger role. During the theoretical leakage design basis accident the reactor coolant flashes to steam in the drywell, pressurizing it rapidly. Vent pipes or tubes from the drywell direct the steam below the water level maintained in the wetwell (also known as a torus or suppression pool), condensing the steam, limiting the pressure ultimately reached. Both the drywell and the wetwell are enclosed by a secondary containment building, maintained at a slight sub-atmospheric or negative pressure during normal operation and refueling operations. The containment designs are referred to by the names Mark I (oldest; drywell/torus), Mark II, and Mark III (newest). All three types house also use the large body of water in the suppression pools to quench steam released from the reactor system during transients. Design and testing requirements In the event of a worst-case emergency, called a "design basis accident" in NRC regulations, the containment is designed to seal off and contain a meltdown. Redundant systems are installed to prevent a meltdown, but as a matter of policy, one is assumed to occur and thus the requirement for a containment building. For design purposes, the reactor vessel's piping is assumed to be breached, causing a "LOCA" (loss Of coolant accident) where the water in the reactor vessel is released to the atmosphere inside the containment and flashes into steam. The resulting pressure increase inside the containment, which is designed to withstand the pressure, triggers containment sprays ("dousing sprays") to turn on to condense the steam and thus reduce the pressure. A SCRAM ("neutronic trip") initiates very shortly after the break occurs. The safety systems close non-essential lines into the air-tight containment by shutting the isolation valves. Emergency Core Cooling Systems are quickly turned on to cool the fuel and prevent it from melting. http://en.wikipedia.org/wiki/Containment_building Disadvantages (BWR) a.. Complex calculations for managing consumption of nuclear fuel during operation due to "two phase (water and steam) fluid flow" in the upper part of the core. This requires more instrumentation in the reactor core. The innovation of computers, however, makes this less of an issue. b.. Much larger pressure vessel than for a PWR of similar power, with correspondingly higher cost. (However, the overall cost is reduced because a modern BWR has no main steam generators and associated piping.) c.. Contamination of the turbine by short-lived activation products. This means that shielding and access control around the steam turbine are required during normal operations due to the radiation levels arising from the steam entering directly from the reactor core. This is a moderately minor concern, as most of the radiation flux is due to Nitrogen - 16, which has a half-life measured in seconds, allowing the turbine chamber to be entered into within minutes of shutdown. d.. Though the present fleet of BWRs are said to be less likely to suffer core damage from the "1 in 100,000 reactor-year" limiting fault than the present fleet of PWRs are (due to increased ECCS robustness and redundancy) there have been concerns raised about the pressure containment ability of the as-built, unmodified Mark I containment - that such may be insufficient to contain pressures generated by a limiting fault combined with complete ECCS failure that results in extremely severe core damage. In this double failure scenario, assumed to be extremely unlikely prior to the Fukushima I nuclear incident, an unmodified Mark I containment can allow some degree of radioactive release to occur. This is supposed to be mitigated by the modification of the Mark I containment; namely, the addition of an outgas stack system that, if containment pressure exceeds critical setpoints, is supposed to allow the orderly discharge of pressurizing gasses after the gasses pass through activated carbon filters designed to trap radionuclides[citation needed]. e.. Control rods are inserted from below for current BWR designs. There are two available hydraulic power sources that can drive the control rods into the core for a BWR under emergency conditions. There is a dedicated high pressure hydraulic accumulator and also the pressure inside of the reactor pressure vessel available to each control rod. Either the dedicated accumulator (one per rod) or reactor pressure is capable of fully inserting each rod. Most other reactor types use top entry control rods that are held up in the withdrawn position by electromagnets, causing them to fall into the reactor by gravity if power is lost. http://en.wikipedia.org/wiki/Boiling_Water_Reactor |
#29
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...Nuclear MELTDOWN in Japan...look at the video again!
On Sun, 13 Mar 2011 12:30:55 -0400, Jonathan wrote:
Compare the size of the smoke plume at the start of this video to the point before the explosion at 47 seconds. The smoke plume grows by some four times in size in just 40 seconds. Then bang! It fits the worst case scenario sequence cited below. And the govt statement a pipe burst. http://www.youtube.com/watch?v=LvC4WQrQwTs So your point is the government hasn't told all? Probably not. The "worst case" hasn't happened. Saying it has is hype. Fukushima Reactor This reactor is a Boiling Water Reactor (BWR), an early BWR mark 2 with the earliest mark 1 outer containment. Built in 1967. Most reactors today are Pressurized Water Reactors (PWR). And btw, a BWR doesn't have top mounted control rods which automatically fall if power is lost. They're bottom mounted and hydraulically inserted. And it may be the large suppression pools described below they're trying to fill with sea-water now I would guess. And it should be noted, below it states the outer containment building is designed to ...contain...a meltdown. Hence, the name, *containment* building. You don't want them to build nukes in a building that would do this? Snip Wiki quotes. |
#30
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...Nuclear MELTDOWN in Japan...look at the video again!
"Jacob" wrote in message ... On Sun, 13 Mar 2011 12:30:55 -0400, Jonathan wrote: Compare the size of the smoke plume at the start of this video to the point before the explosion at 47 seconds. The smoke plume grows by some four times in size in just 40 seconds. Then bang! It fits the worst case scenario sequence cited below. And the govt statement a pipe burst. http://www.youtube.com/watch?v=LvC4WQrQwTs So your point is the government hasn't told all? Probably not. The "worst case" hasn't happened. Saying it has is hype. Fukushima Reactor This reactor is a Boiling Water Reactor (BWR), an early BWR mark 2 with the earliest mark 1 outer containment. Built in 1967. Most reactors today are Pressurized Water Reactors (PWR). And btw, a BWR doesn't have top mounted control rods which automatically fall if power is lost. They're bottom mounted and hydraulically inserted. And it may be the large suppression pools described below they're trying to fill with sea-water now I would guess. And it should be noted, below it states the outer containment building is designed to ...contain...a meltdown. Hence, the name, *containment* building. You don't want them to build nukes in a building that would do this? The failure scenario design assumption is that a coolant pile to the steel reactor containment vessel broke, causing a melt-down and pressurizing the outer concrete containment building. But that outer building should survive even in this worst case. But it appears this early version outer building didn't have the added safety systems which would vent and filter the outer building when the pressure built up. It appears this is the worst case, in terms of level of accident /and/ lack of safety systems. Snip Wiki quotes. |
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