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Thread is about the various issues surrounding Japan in the aftermath of the recent earthquake. Don't bring the shit side of the internet to the thread, and post with the realization that this thread is very important, and very real, to your fellow members.
Do not post speculative and unconfirmed news you saw on TV or anywhere else. Generally the more dramatic it sounds the less likely it's true. |
On March 16 2011 07:20 johnnysokko wrote:Show nested quote +On March 16 2011 05:19 InFiNitY[pG] wrote:On March 16 2011 05:00 Ropid wrote:On March 16 2011 04:49 InFiNitY[pG] wrote:
This is obviously a rather stupid question for someone who knows about this stuff, but why is water the only or best way to cool the reactors? Why not use something much colder like liquid nitrogen? The reactor works by boiling water. The steam drives turbines. The whole machinery is built to work with water. Look at this graphic: http://www.spiegel.de/international/world/bild-750773-191928.html I know how it works. But wouldn't you agree that avoiding a meltdown is a little more important atm than keeping the output intact? Anyways thanks for the explanations. I had just thought that there should be SOMETHING more efficient for cooling these than water, at least temporarily. but apparently that's not the case. As was said above water is an excellent material for coolant, and is actually used as the coolant in almost every kind of power plant that there is, not just nuclear reactors. However in a nuclear reactor water is used very often because it serves two purposes. Not only does liquid water cool the core material, but water is a very strong neutron absorber. Thus the water surrounding the core dramatically reduces the spread of radioactvity from the core, and even the fuel rods that are not currently in a core (from reactors 4-6) are kept underwater both for cooling and to diminish the irradiation of the nearby area. This gets into the more technical aspects but the water moderation effect makes a light water reactor is actually less likely to meltdown under adverse conditions than say for example a graphite moderated core, such as was used in Chernobyl. My thesis advisor has spent 30 years on just these safety issues, and he says Tepco(?) is underplaying the situation and that it is almost certain likely all three active reactors have already experienced partial meltdown and will soon lose containment. Yesterday morning, he predicted the explosion at reactor 2 well ahead of time, so I'm becoming very inclined to accept his pretty negative outlook on the situation.
Partial meltdown is almost 100% for sure. They wouldn't have found Cesium and Iodine in the air around the complex without uranium degradation. Containment is still a question. They haven't yet breached, but I don't think these systems have ever been tested like this. It's still possible that they can just keep venting off the activated air / steam, if the systems are still functioning.
The IMA on reddit by the Nuclear Engineer was really good.
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It's being said the 50 or so workers are all Volunteers. 
Amid the horror and devastation of the nuclear crisis in Japan, it can be easy to miss the heroism of the 50 emergency workers trying to prevent the full meltdown of the Fukushima Daiichi nuclear facility. It's not exaggeration to say that the safety of thousands of Japanese citizens hinges on the efforts of the crew of cleanup workers left behind after the remainder of the facility's roughly 800 employees have been evacuated amid hazardous levels of radiation. Even in a culture that places a premium on self-sacrifice, these ordinary workers are being extraordinarily selfless -- and could conceivably make the ultimate sacrifice for their fellow citizens' well-being.
Who these 50 workers are remains something of a mystery. Their employer, the Tokyo Electric Company, has not provided their details. But after a new explosion at the plant this morning, their fate may be becoming more perilous by the minute. As nuclear power consultant Arnold Gundersen told the New York Times, it's likely the company has approached older plant retirees with a sobering invitation to reinforce the plant safety crew. Plant managers "may also be asking for people to volunteer to receive additional exposure," Gundersen told the Times' Henry Fountain.
Source
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On March 16 2011 07:20 johnnysokko wrote:
My thesis advisor has spent 30 years on just these safety issues, and he says Tepco(?) is underplaying the situation and that it is almost certain likely all three active reactors have already experienced partial meltdown and will soon lose containment. Yesterday morning, he predicted the explosion at reactor 2 well ahead of time, so I'm becoming very inclined to accept his pretty negative outlook on the situation.
While I agree with you that TEPCO has not the best PR, they are not downplaying the situation concerning the core damage in reactors #1 to #3. The latest press conference explicitly mentioned the amount of core damage that is suspected, except for reactor #3, because it suffered damage on the necessary measurement devices.
TEPCO currently estimates 70% core damage in reactor #1, with damaged fuel rods. #2 has suffered damage upwards of 33%.
There is still no damage reported to the containment, so I doubt that it will simply "lose containment" soon. The sea-water cooling procedures are still working, according to the press conference.
Things that are concerning: The fire in #4 and the side comment that pressure in #5 is rising as well (although they didn't clarify that statement).
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my take on this...
a. water is the best coolant period. liquid nitrogen would fragilize the steel structures of containment making it much more prone to breaking thru mechanical shocks such as explosions or earthquakes.
b. there is a scientific paper somewhere on the internet (i'll find the link) that models the probability of loss of containment if corium (=melting radioactive matter) reaches the outer containment. that probability i'm afraid is 42%.
if that was to happen then this would definitely be a 6+ accident (for memory Three Mile Island was 4, Chernobyl 7), the second worst civil nuclear disaster in the history of mankind
Edited for link : http://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6920/cr6920.pdf
see tables of probabilities of failure as a function of inner pressure on pages 97+.
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On March 16 2011 07:37 TimeOut wrote:
There is still no damage reported to the containment, so I doubt that it will simply "lose containment" soon. The sea-water cooling procedures are still working, according to the press conference.
Things that are concerning: The fire in #4 and the side comment that pressure in #5 is rising as well (although they didn't clarify that statement).
The process he feels is going on is that when not enough water can be pumped in to cover the core, the steam reacts with the exposed core to produce hydrogen which can explode. This is the source of the explosions at all three reactors. The operators can mitigate the strength of these explosions this cycle by releasing steam and reducing the pressure in the containment. Reducing the pressure also reduces the boiling point of water increasing the required water flow to keep the core covered, causing more hydrogen to be produced. Thus venting steam becomes a pyhrric victory. Eventually the hydrogen explosions will compromise the core.
The excursion in radiations levels after the explosion at reactor #2 is completely consistent loss of containment. The first spike of radiation fell off because the rate of ejection decreases rapidly as the breached containment shell loses pressure. Once the containment is breached, it requires an enormous amount of water to try to keep the core covered.
Going to a briefing on the latest events plus analysis now. Will post again if anything, not publicly offered is said.
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On March 16 2011 07:53 johnnysokko wrote:Show nested quote +On March 16 2011 07:37 TimeOut wrote:
There is still no damage reported to the containment, so I doubt that it will simply "lose containment" soon. The sea-water cooling procedures are still working, according to the press conference.
Things that are concerning: The fire in #4 and the side comment that pressure in #5 is rising as well (although they didn't clarify that statement). The process he feels is going on is that when not enough water can be pumped in to cover the core, the steam reacts with the exposed core to produce hydrogen which can explode. This is the source of the explosions at all three reactors. The operators can mitigate the strength of these explosions this cycle by releasing steam and reducing the pressure in the containment. Reducing the pressure also reduces the boiling point of water increasing the required water flow to keep the core covered, causing more hydrogen to be produced. Thus venting steam becomes a pyhrric victory. Eventually the hydrogen explosions will compromise the core. The excursion in radiations levels after the explosion at reactor #2 is completely consistent loss of containment. The first spike of radiation fell off because the rate of ejection decreases rapidly as the breached containment shell loses pressure. Once the containment is breached, it requires an enormous amount of water to try to keep the core covered. Going to a briefing on the latest events plus analysis now. Will post again if anything, not publicly offered is said.
I think you meant to say that the hydrogen explosions will compromise the containment integrity, but regardless of that, I agree with you on the basic idea. I still think that the situation is manageable, if all their systems to regulate the pressure and the additional pumps are working correctly and especially since the necessary people are still at the site. I don't think that it is a foregone conclusion that the containment will be damaged in the end, as long as they manage to control the pressure and steam / water flow correctly and react to the necessary changes.
The latest official statement (that I've seen) regarding the radiation levels after the explosion at #2 attributed the sharp spike to the loss of the secondary containment integrity and the resulting discharge of steam from the building, not to damage to the primary containment. I guess we can't say for sure which theory might be true.
Thanks, keep us updated if you hear anything new during that briefing!
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NHK is reporting the flames at the No. 4 reactor are no longer visible
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On March 16 2011 07:35 Broodwich wrote:Show nested quote +On March 16 2011 07:20 johnnysokko wrote:On March 16 2011 05:19 InFiNitY[pG] wrote:On March 16 2011 05:00 Ropid wrote:On March 16 2011 04:49 InFiNitY[pG] wrote:
This is obviously a rather stupid question for someone who knows about this stuff, but why is water the only or best way to cool the reactors? Why not use something much colder like liquid nitrogen? The reactor works by boiling water. The steam drives turbines. The whole machinery is built to work with water. Look at this graphic: http://www.spiegel.de/international/world/bild-750773-191928.html I know how it works. But wouldn't you agree that avoiding a meltdown is a little more important atm than keeping the output intact? Anyways thanks for the explanations. I had just thought that there should be SOMETHING more efficient for cooling these than water, at least temporarily. but apparently that's not the case. As was said above water is an excellent material for coolant, and is actually used as the coolant in almost every kind of power plant that there is, not just nuclear reactors. However in a nuclear reactor water is used very often because it serves two purposes. Not only does liquid water cool the core material, but water is a very strong neutron absorber. Thus the water surrounding the core dramatically reduces the spread of radioactvity from the core, and even the fuel rods that are not currently in a core (from reactors 4-6) are kept underwater both for cooling and to diminish the irradiation of the nearby area. This gets into the more technical aspects but the water moderation effect makes a light water reactor is actually less likely to meltdown under adverse conditions than say for example a graphite moderated core, such as was used in Chernobyl. My thesis advisor has spent 30 years on just these safety issues, and he says Tepco(?) is underplaying the situation and that it is almost certain likely all three active reactors have already experienced partial meltdown and will soon lose containment. Yesterday morning, he predicted the explosion at reactor 2 well ahead of time, so I'm becoming very inclined to accept his pretty negative outlook on the situation. Partial meltdown is almost 100% for sure. They wouldn't have found Cesium and Iodine in the air around the complex without uranium degradation. Containment is still a question. They haven't yet breached, but I don't think these systems have ever been tested like this. It's still possible that they can just keep venting off the activated air / steam, if the systems are still functioning. The IMA on reddit by the Nuclear Engineer was really good.
That is not true, the cesium got out when they released pressure and obviously there is cesium in the reactor when there normally decays u235 ( two decay steps to cesium).
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On March 16 2011 08:02 TimeOut wrote:Show nested quote +On March 16 2011 07:53 johnnysokko wrote:On March 16 2011 07:37 TimeOut wrote:
There is still no damage reported to the containment, so I doubt that it will simply "lose containment" soon. The sea-water cooling procedures are still working, according to the press conference.
Things that are concerning: The fire in #4 and the side comment that pressure in #5 is rising as well (although they didn't clarify that statement). The process he feels is going on is that when not enough water can be pumped in to cover the core, the steam reacts with the exposed core to produce hydrogen which can explode. This is the source of the explosions at all three reactors. The operators can mitigate the strength of these explosions this cycle by releasing steam and reducing the pressure in the containment. Reducing the pressure also reduces the boiling point of water increasing the required water flow to keep the core covered, causing more hydrogen to be produced. Thus venting steam becomes a pyhrric victory. Eventually the hydrogen explosions will compromise the core. The excursion in radiations levels after the explosion at reactor #2 is completely consistent loss of containment. The first spike of radiation fell off because the rate of ejection decreases rapidly as the breached containment shell loses pressure. Once the containment is breached, it requires an enormous amount of water to try to keep the core covered. Going to a briefing on the latest events plus analysis now. Will post again if anything, not publicly offered is said. I think you meant to say that the hydrogen explosions will compromise the containment integrity, but regardless of that, I agree with you on the basic idea. I still think that the situation is manageable, if all their systems to regulate the pressure and the additional pumps are working correctly and especially since the necessary people are still at the site. I don't think that it is a foregone conclusion that the containment will be damaged in the end, as long as they manage to control the pressure and steam / water flow correctly and react to the necessary changes. The latest official statement (that I've seen) regarding the radiation levels after the explosion at #2 attributed the sharp spike to the loss of the secondary containment integrity and the resulting discharge of steam from the building, not to damage to the primary containment. I guess we can't say for sure which theory might be true.Thanks, keep us updated if you hear anything new during that briefing!
That sounds very plausible.
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On March 16 2011 08:04 aqui wrote:Show nested quote +On March 16 2011 07:35 Broodwich wrote:On March 16 2011 07:20 johnnysokko wrote:On March 16 2011 05:19 InFiNitY[pG] wrote:On March 16 2011 05:00 Ropid wrote:On March 16 2011 04:49 InFiNitY[pG] wrote:
This is obviously a rather stupid question for someone who knows about this stuff, but why is water the only or best way to cool the reactors? Why not use something much colder like liquid nitrogen? The reactor works by boiling water. The steam drives turbines. The whole machinery is built to work with water. Look at this graphic: http://www.spiegel.de/international/world/bild-750773-191928.html I know how it works. But wouldn't you agree that avoiding a meltdown is a little more important atm than keeping the output intact? Anyways thanks for the explanations. I had just thought that there should be SOMETHING more efficient for cooling these than water, at least temporarily. but apparently that's not the case. As was said above water is an excellent material for coolant, and is actually used as the coolant in almost every kind of power plant that there is, not just nuclear reactors. However in a nuclear reactor water is used very often because it serves two purposes. Not only does liquid water cool the core material, but water is a very strong neutron absorber. Thus the water surrounding the core dramatically reduces the spread of radioactvity from the core, and even the fuel rods that are not currently in a core (from reactors 4-6) are kept underwater both for cooling and to diminish the irradiation of the nearby area. This gets into the more technical aspects but the water moderation effect makes a light water reactor is actually less likely to meltdown under adverse conditions than say for example a graphite moderated core, such as was used in Chernobyl. My thesis advisor has spent 30 years on just these safety issues, and he says Tepco(?) is underplaying the situation and that it is almost certain likely all three active reactors have already experienced partial meltdown and will soon lose containment. Yesterday morning, he predicted the explosion at reactor 2 well ahead of time, so I'm becoming very inclined to accept his pretty negative outlook on the situation. Partial meltdown is almost 100% for sure. They wouldn't have found Cesium and Iodine in the air around the complex without uranium degradation. Containment is still a question. They haven't yet breached, but I don't think these systems have ever been tested like this. It's still possible that they can just keep venting off the activated air / steam, if the systems are still functioning. The IMA on reddit by the Nuclear Engineer was really good. That is not true, the cesium got out when they released pressure and obviously there is cesium in the reactor when there normally decays u235 ( two decay steps to cesium).
What is not true? For caesium to get out there must be a partial meltdown of the core as it will only diffuse into the air when the fuel molten.
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On March 16 2011 08:18 hugman wrote:Show nested quote +On March 16 2011 08:04 aqui wrote:On March 16 2011 07:35 Broodwich wrote:On March 16 2011 07:20 johnnysokko wrote:On March 16 2011 05:19 InFiNitY[pG] wrote:On March 16 2011 05:00 Ropid wrote:On March 16 2011 04:49 InFiNitY[pG] wrote:
This is obviously a rather stupid question for someone who knows about this stuff, but why is water the only or best way to cool the reactors? Why not use something much colder like liquid nitrogen? The reactor works by boiling water. The steam drives turbines. The whole machinery is built to work with water. Look at this graphic: http://www.spiegel.de/international/world/bild-750773-191928.html I know how it works. But wouldn't you agree that avoiding a meltdown is a little more important atm than keeping the output intact? Anyways thanks for the explanations. I had just thought that there should be SOMETHING more efficient for cooling these than water, at least temporarily. but apparently that's not the case. As was said above water is an excellent material for coolant, and is actually used as the coolant in almost every kind of power plant that there is, not just nuclear reactors. However in a nuclear reactor water is used very often because it serves two purposes. Not only does liquid water cool the core material, but water is a very strong neutron absorber. Thus the water surrounding the core dramatically reduces the spread of radioactvity from the core, and even the fuel rods that are not currently in a core (from reactors 4-6) are kept underwater both for cooling and to diminish the irradiation of the nearby area. This gets into the more technical aspects but the water moderation effect makes a light water reactor is actually less likely to meltdown under adverse conditions than say for example a graphite moderated core, such as was used in Chernobyl. My thesis advisor has spent 30 years on just these safety issues, and he says Tepco(?) is underplaying the situation and that it is almost certain likely all three active reactors have already experienced partial meltdown and will soon lose containment. Yesterday morning, he predicted the explosion at reactor 2 well ahead of time, so I'm becoming very inclined to accept his pretty negative outlook on the situation. Partial meltdown is almost 100% for sure. They wouldn't have found Cesium and Iodine in the air around the complex without uranium degradation. Containment is still a question. They haven't yet breached, but I don't think these systems have ever been tested like this. It's still possible that they can just keep venting off the activated air / steam, if the systems are still functioning. The IMA on reddit by the Nuclear Engineer was really good. That is not true, the cesium got out when they released pressure and obviously there is cesium in the reactor when there normally decays u235 ( two decay steps to cesium). What is not true? For caesium to get out there must be a partial meltdown of the core as it will only diffuse into the air when the fuel molten.
Well i would have imagined that in the steam cesiumoxid for example could be created which could be parted from the rod with not to much force.
edit:
apart from that, why don't emit decays at the surface of the rods radioactive barium->cesium in the surroundings normally?
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I just hope my grandparents are okay this situation has made me very nervous for my family members in Natori. I really wish I was there to help right now.
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On March 16 2011 08:31 socommaster123 wrote:
I just hope my grandparents are okay this situation has made me very nervous for my family members in Natori. I really wish I was there to help right now.
Sounds patriotic but wanting to be in Japan right now is just plain ridic
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contact japan for free (at&t, sprint, verizon and others)
For those who have been calling family, friends and loved ones in Japan over the last few days... According to Engadget, here's some helpful news: AT&T, Sprint, Verizon, Comcast and Cox Communications are all waiving fees for international long distance calls and texts to Japan (with various limits and restrictions) through the end of the month. And Dish Networks and FiOS TV are both offering free access to TV Japan.
Go here http://www.engadget.com/2011/03/14/atandt-makes-calling-japan-free-until-the-end-of-march/
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I wonder what this means to economy of USA and all other country that japan have borrow money to. Pretty sure the want their money back soon...
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On March 16 2011 08:18 hugman wrote:Show nested quote +On March 16 2011 08:04 aqui wrote:On March 16 2011 07:35 Broodwich wrote:On March 16 2011 07:20 johnnysokko wrote:On March 16 2011 05:19 InFiNitY[pG] wrote:On March 16 2011 05:00 Ropid wrote:On March 16 2011 04:49 InFiNitY[pG] wrote:
This is obviously a rather stupid question for someone who knows about this stuff, but why is water the only or best way to cool the reactors? Why not use something much colder like liquid nitrogen? The reactor works by boiling water. The steam drives turbines. The whole machinery is built to work with water. Look at this graphic: http://www.spiegel.de/international/world/bild-750773-191928.html I know how it works. But wouldn't you agree that avoiding a meltdown is a little more important atm than keeping the output intact? Anyways thanks for the explanations. I had just thought that there should be SOMETHING more efficient for cooling these than water, at least temporarily. but apparently that's not the case. As was said above water is an excellent material for coolant, and is actually used as the coolant in almost every kind of power plant that there is, not just nuclear reactors. However in a nuclear reactor water is used very often because it serves two purposes. Not only does liquid water cool the core material, but water is a very strong neutron absorber. Thus the water surrounding the core dramatically reduces the spread of radioactvity from the core, and even the fuel rods that are not currently in a core (from reactors 4-6) are kept underwater both for cooling and to diminish the irradiation of the nearby area. This gets into the more technical aspects but the water moderation effect makes a light water reactor is actually less likely to meltdown under adverse conditions than say for example a graphite moderated core, such as was used in Chernobyl. My thesis advisor has spent 30 years on just these safety issues, and he says Tepco(?) is underplaying the situation and that it is almost certain likely all three active reactors have already experienced partial meltdown and will soon lose containment. Yesterday morning, he predicted the explosion at reactor 2 well ahead of time, so I'm becoming very inclined to accept his pretty negative outlook on the situation. Partial meltdown is almost 100% for sure. They wouldn't have found Cesium and Iodine in the air around the complex without uranium degradation. Containment is still a question. They haven't yet breached, but I don't think these systems have ever been tested like this. It's still possible that they can just keep venting off the activated air / steam, if the systems are still functioning. The IMA on reddit by the Nuclear Engineer was really good. That is not true, the cesium got out when they released pressure and obviously there is cesium in the reactor when there normally decays u235 ( two decay steps to cesium). What is not true? For caesium to get out there must be a partial meltdown of the core as it will only diffuse into the air when the fuel molten.
the only fact available at that time was that some caesium and iodine was initially detected. there was no further detail of the report. a news agency summised that a meltdown had occured but of course they had no further information just like the rest of us.
but also consider the fact that the reactors are now under control and cooling, so the meltdown was highly unlikely. as always we can only assume and guess - im guessing the detection of the elements had something to do with the venting of the reactor vessel.
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
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Here's one that has all that info as well as the location of the most recent earthquake marked as a red X on the map of Japan.
Link is here!
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On March 16 2011 08:18 hugman wrote:
What is not true? For caesium to get out there must be a partial meltdown of the core as it will only diffuse into the air when the fuel molten.
The question is: Is it possible, that the earthquake shaking itself caused a partial damage of the fuel rod pipes?
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On March 16 2011 09:40 Desti wrote:Show nested quote +On March 16 2011 08:18 hugman wrote:
What is not true? For caesium to get out there must be a partial meltdown of the core as it will only diffuse into the air when the fuel molten. The question is: Is it possible, that the earthquake shaking itself caused a partial damage of the fuel rod pipes?
Not likely, the earth rumbles in Japan over ten times a month, the 9.0 quake barely caused any damage to buildings and nuclear reactors are with no doubt built to handle way more than skyscrapers. It would be immensely unlikely that the quake had any impact on the plants or their equipment at all.
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EPT
