<!--quoteo(post=1838362:date=Mar 22 2011, 12:35 PM:name=lolfighter)--><div class='quotetop'>QUOTE (lolfighter @ Mar 22 2011, 12:35 PM) <a href="index.php?act=findpost&pid=1838362"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->The reactor spiked to a thermal output of ten times what it was rated for, causing water to flash into steam, leading to massive overpressure, rupture of pipes and eventually the entire reactor casing splitting apart. The nuclear excursion came into play seconds later, possibly due to the almost total loss of coolant and moderator combined with the reactor type's positive void coefficient (which means that gaps or voids in the moderator (which the coolant in the reactor also served as) cause the reactor to increase in output, unlike safer reactor designs with negative void coefficients that cause a decrease in reactor output in such a situation).<!--QuoteEnd--></div><!--QuoteEEnd--> Cool, we're on the same page now. Well done.
<!--quoteo(post=1838362:date=Mar 22 2011, 01:35 PM:name=lolfighter)--><div class='quotetop'>QUOTE (lolfighter @ Mar 22 2011, 01:35 PM) <a href="index.php?act=findpost&pid=1838362"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->possibly due to the almost total loss of coolant and moderator combined with the reactor type's positive void coefficient (which means that gaps or voids in the moderator <b>(which the coolant in the reactor also served as)</b><!--QuoteEnd--></div><!--QuoteEEnd--> It was my understanding that the Chernobyl reactor used two different methods for moderating and cooling, namely it used water to cool and graphite to moderate. When the reactor failed the graphite(which is super radioactive at this point) caught fire and the resulting radioactive smoke is partly to blame for the level of devastation/irradiation that occurred. Newer reactors used purified water for both the coolant and moderator, which is good because water retains very little radioactivity, unlike the graphite those crazy russians used.
Correct, I got those mixed up. In fact, loss of moderator would have slowed down the reaction as far as I understand, because the moderator slows down neutrons and slow neutrons are more likely to be absorbed than fast neutrons (and neutrons being absorbed by the fissile material is what keeps the reaction going). I think this also makes reactors that use the coolant as moderator safer - if the reactor loses coolant, it also implicitly loses moderator, which slows the reaction.
It's not incorrect to say the water in RBMKs moderates; water can't help slow down neutrons if it's in the way. It's just not the primary moderation. In both RBMKs and LWRs, 'void' refers to absence (steam) of the water coolant, whether it's the primary moderator or not.
lolf is right about locking up moderation in the coolant to provide inherent safety; it's generally not about the radioactivity of graphite vs. water.
btw, moderation is one of the most commonly misunderstood aspects of reactor physics... something about people thinking slower neutrons means slower reactions. so if you understand it, you're special :D :D I was speaking with a navy nuclear guy once, and he clearly didn't understand, so...
<!--quoteo--><div class='quotetop'>QUOTE </div><div class='quotemain'><!--quotec-->Written by a Delta pilot on approach to Tokyo during earthquake.
I'm currently still in one piece, writing from my room in the Narita crew hotel. It's 8am. This is my inaugural trans-pacific trip as a brand new, recently checked out, International 767 Captain and it has been interesting, to say the least, so far. I've crossed the Atlantic three times so far so the ocean crossing procedures were familiar.
By the way, stunning scenery flying over the Aleutian Islands. Everything was going fine until 100 miles out from Tokyo and in the descent for arrival. The first indication of any trouble was that Japan air traffic control started putting everyone into holding patterns. At first we thought it was usual congestion on arrival. Then we got a company data link message advising about the earthquake, followed by another stating Narita airport was temporarily closed for inspection and expected to open shortly (the company is always so positive).
From our perspective things were obviously looking a little different. The Japanese controller's anxiety level seemed quite high and he said expect "indefinite" holding time. No one would commit to a time frame on that so I got my copilot and relief pilot busy looking at divert stations and our fuel situation, which, after an ocean crossing is typically low.
It wasn't long, maybe ten minutes, before the first pilots started requesting diversions to other airports. Air Canada, American, United, etc. all reporting minimal fuel situations. I still had enough fuel for 1.5 to 2.0 hours of holding. Needless to say, the diverts started complicating the situation.
Japan air traffic control then announced Narita was closed indefinitely due to damage. Planes immediately started requesting arrivals into Haneada, near Tokyo, a half dozen JAL and western planes got clearance in that direction but then ATC announced Haenada had just closed. Uh oh! Now instead of just holding, we all had to start looking at more distant alternatives like Osaka, or Nagoya.
One bad thing about a large airliner is that you can't just be-pop into any little airport. We generally need lots of runway. With more planes piling in from both east and west, all needing a place to land and several now fuel critical ATC was getting over-whelmed. In the scramble, and without waiting for my fuel to get critical, I got my flight a clearance to head for Nagoya, fuel situation still okay. So far so good. A few minutes into heading that way, I was "ordered" by ATC to reverse course. Nagoya was saturated with traffic and unable to handle more planes (read- airport full). Ditto for Osaka.
With that statement, my situation went instantly from fuel okay, to fuel minimal considering we might have to divert a much farther distance. Multiply my situation by a dozen other aircraft all in the same boat, all making demands requests and threats to ATC for clearances somewhere. Air Canada and then someone else went to "emergency" fuel situation. Planes started to heading for air force bases. The nearest to Tokyo was Yokoda AFB. I threw my hat in the ring for that initially. The answer - Yokoda closed! No more space.
By now it was a three ring circus in the cockpit, my copilot on the radios, me flying and making decisions and the relief copilot buried in the air charts trying to figure out where to go that was within range while data link messages were flying back and forth between us and company dispatch in Atlanta. I picked Misawa AFB at the north end of Honshu Island. We could get there with minimal fuel remaining. ATC was happy to get rid of us so we cleared out of the maelstrom of the Tokyo region. We heard ATC try to send planes toward Sendai, a small regional airport on the coast which was later the one I think that got flooded by a tsunami.
Atlanta dispatch then sent us a message asking if we could continue to Chitose airport on the Island of Hokkaido, north of Honshu. Other Delta planes were heading that way. More scrambling in the cockpit - check weather, check charts, check fuel, okay. We could still make it and not be going into a fuel critical situation ... if we had no other fuel delays. As we approached Misawa we got clearance to continue to Chitose. Critical decision thought process. Let's see - trying to help company - plane overflies perfectly good divert airport for one farther away...wonder how that will look in the safety report, if anything goes wrong.
Suddenly ATC comes up and gives us a vector to a fix well short of Chitose and tells us to standby for holding instructions. Nightmare realized. Situation rapidly deteriorating. After initially holding near Tokyo, starting a divert to Nagoya, reversing course back to Tokyo then to re-diverting north toward Misawa, all that happy fuel reserve that I had was vaporizing fast. My subsequent conversation, paraphrased of course...., went something like this: "Sapparo Control - Delta XX requesting immediate clearance direct to Chitose, minimum fuel, unable hold." "Negative Ghost-Rider, the Pattern is full" <<< top gun quote <<<
"Sapparo Control - make that - Delta XX declaring emergency, low fuel, proceeding direct Chitose" "Roger Delta XX, understood, you are cleared direct to Chitose, contact Chitose approach....etc...." Enough was enough. I had decided to pre-empt actually running critically low on fuel while in another indefinite holding pattern, especially after bypassing Misawa, and played my last ace...declaring an emergency. The problem with that is now I have a bit of company paperwork to do but what the heck.
As it was - landed Chitose, safe, with at least 30 minutes of fuel remaining before reaching a "true" fuel emergency situation. That's always a good feeling, being safe. They taxied us off to some remote parking area where we shut down and watched a half dozen or more other airplanes come streaming in. In the end, Delta had two 747s, my 767 and another 767 and a 777 all on the ramp at Chitose.
We saw two American airlines planes, a United and two Air Canada as well. Not to mention several extra Al Nippon and Japan Air Lines planes.
Post-script - 9 hours later, Japan air lines finally got around to getting a boarding ladder to the plane where we were able to get off and clear customs. That however, is another interesting story. By the way - while writing this - I have felt four additional tremors that shook the hotel slightly - all in 45 minutes.<!--QuoteEnd--></div><!--QuoteEEnd--> Re-quoted from another forum, no source available.
<a href="http://www.bbc.co.uk/news/world-asia-pacific-13045341" target="_blank">http://www.bbc.co.uk/news/world-asia-pacific-13045341</a> <!--quoteo--><div class='quotetop'>QUOTE </div><div class='quotemain'><!--quotec-->Japanese authorities have raised the severity rating of their nuclear crisis to the highest level, seven.<!--QuoteEnd--></div><!--QuoteEEnd-->
I like how TEPCO have said every day since the original quake and the tsunami, the plant has become more and more stable... yet more and more dangerous.
I hope it all explodes at nighttime. Im sure it will the most watched clip for a longtime :P. The 2000+ test nukes in air, sea, ground and atmosphere over the course of 50 years by various countries has probably done more damage compared anyway. Crisis? For that area sure. But for the rest? Nah.
<!--quoteo(post=1840655:date=Apr 12 2011, 01:42 PM:name=Thaldarin)--><div class='quotetop'>QUOTE (Thaldarin @ Apr 12 2011, 01:42 PM) <a href="index.php?act=findpost&pid=1840655"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->I like how TEPCO have said every day since the original quake and the tsunami, the plant has become more and more stable... yet more and more dangerous.<!--QuoteEnd--></div><!--QuoteEEnd--> It's like in Red Dwarf, they're accelerating but the acceleration rate is decreasing, so they're slowing down but they're still going faster. <!--quoteo(post=1840666:date=Apr 12 2011, 03:33 PM:name=lolfighter)--><div class='quotetop'>QUOTE (lolfighter @ Apr 12 2011, 03:33 PM) <a href="index.php?act=findpost&pid=1840666"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->lolfighter confused.<!--QuoteEnd--></div><!--QuoteEEnd--> Everything is fine, media is just being media again.
It's a finite value scale, and despite having the same maximum number on the scale, it doesn't mean that it has the same magnitude.
edit: as for the stability/acceleration analogy, I would say it's more like danger = distance and stability = speed. It's slowing down, but damage done has already been done.
<!--quoteo(post=1840702:date=Apr 12 2011, 09:50 PM:name=lolfighter)--><div class='quotetop'>QUOTE (lolfighter @ Apr 12 2011, 09:50 PM) <a href="index.php?act=findpost&pid=1840702"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->Erm, if your acceleration rate is decreasing but still positive, you're not actually slowing down. You're still speeding up.<!--QuoteEnd--></div><!--QuoteEEnd--> That's the joke, lolf.
Red Dwarf is comedy, and in this case is told from the perspective of a senile (3 million year old) AI, so it goes something along the lines of
"...that didn't make much sense to Holly. Another thing was that the ship's engines when told to stop could only do so slowly, so they were still accelerating, but the rate was dropping. So they were slowing down, but still going faster. That didn't make much sense to Holly, either."
Anyway, back to the disaster at hand. <a href="http://www.theregister.co.uk/2011/04/12/fu" target="_blank">http://www.theregister.co.uk/2011/04/12/fu</a> kushima_ffs/ (cursed censoring... just remove the space) Everything is fine, media just being media.
edit Anyways its true that people are afraid of and do not well understand radiation, that is part of the reason why the ######ushima plant is leading the news but it would be anyways. Really bad things that happen are always big news but people learn all they care to know about it and then lose interest. But bad things that happen and are still on going and have the potential for getting worse hold people's attention much longer and will always dominate the news, ######ushima plant, economic mess, wars, Gulf oil spill, Chile mine collapse.
Comments
Cool, we're on the same page now. Well done.
It was my understanding that the Chernobyl reactor used two different methods for moderating and cooling, namely it used water to cool and graphite to moderate. When the reactor failed the graphite(which is super radioactive at this point) caught fire and the resulting radioactive smoke is partly to blame for the level of devastation/irradiation that occurred.
Newer reactors used purified water for both the coolant and moderator, which is good because water retains very little radioactivity, unlike the graphite those crazy russians used.
I think this also makes reactors that use the coolant as moderator safer - if the reactor loses coolant, it also implicitly loses moderator, which slows the reaction.
lolf is right about locking up moderation in the coolant to provide inherent safety; it's generally not about the radioactivity of graphite vs. water.
btw, moderation is one of the most commonly misunderstood aspects of reactor physics... something about people thinking slower neutrons means slower reactions. so if you understand it, you're special :D :D I was speaking with a navy nuclear guy once, and he clearly didn't understand, so...
I'm currently still in one piece, writing from my room in the Narita crew hotel. It's 8am. This is my inaugural trans-pacific trip as a brand new, recently checked out, International 767 Captain and it has been interesting, to say the least, so far. I've crossed the Atlantic three times so far so the ocean crossing procedures were familiar.
By the way, stunning scenery flying over the Aleutian Islands. Everything was going fine until 100 miles out from Tokyo and in the descent for arrival. The first indication of any trouble was that Japan air traffic control started putting everyone into holding patterns. At first we thought it was usual congestion on arrival. Then we got a company data link message advising about the earthquake, followed by another stating Narita airport was temporarily closed for inspection and expected to open shortly (the company is always so positive).
From our perspective things were obviously looking a little different. The Japanese controller's anxiety level seemed quite high and he said expect "indefinite" holding time. No one would commit to a time frame on that so I got my copilot and relief pilot busy looking at divert stations and our fuel situation, which, after an ocean crossing is typically low.
It wasn't long, maybe ten minutes, before the first pilots started requesting diversions to other airports. Air Canada, American, United, etc. all reporting minimal fuel situations. I still had enough fuel for 1.5 to 2.0 hours of holding. Needless to say, the diverts started complicating the situation.
Japan air traffic control then announced Narita was closed indefinitely due to damage. Planes immediately started requesting arrivals into Haneada, near Tokyo, a half dozen JAL and western planes got clearance in that direction but then ATC announced Haenada had just closed. Uh oh! Now instead of just holding, we all had to start looking at more distant alternatives like Osaka, or Nagoya.
One bad thing about a large airliner is that you can't just be-pop into any little airport. We generally need lots of runway. With more planes piling in from both east and west, all needing a place to land and several now fuel critical ATC was getting over-whelmed. In the scramble, and without waiting for my fuel to get critical, I got my flight a clearance to head for Nagoya, fuel situation still okay. So far so good. A few minutes into heading that way, I was "ordered" by ATC to reverse course. Nagoya was saturated with traffic and unable to handle more planes (read- airport full). Ditto for Osaka.
With that statement, my situation went instantly from fuel okay, to fuel minimal considering we might have to divert a much farther distance. Multiply my situation by a dozen other aircraft all in the same boat, all making demands requests and threats to ATC for clearances somewhere. Air Canada and then someone else went to "emergency" fuel situation. Planes started to heading for air force bases. The nearest to Tokyo was Yokoda AFB. I threw my hat in the ring for that initially. The answer - Yokoda closed! No more space.
By now it was a three ring circus in the cockpit, my copilot on the radios, me flying and making decisions and the relief copilot buried in the air charts trying to figure out where to go that was within range while data link messages were flying back and forth between us and company dispatch in Atlanta. I picked Misawa AFB at the north end of Honshu Island. We could get there with minimal fuel remaining. ATC was happy to get rid of us so we cleared out of the maelstrom of the Tokyo region. We heard ATC try to send planes toward Sendai, a small regional airport on the coast which was later the one I think that got flooded by a tsunami.
Atlanta dispatch then sent us a message asking if we could continue to Chitose airport on the Island of Hokkaido, north of Honshu. Other Delta planes were heading that way. More scrambling in the cockpit - check weather, check charts, check fuel, okay. We could still make it and not be going into a fuel critical situation ... if we had no other fuel delays. As we approached Misawa we got clearance to continue to Chitose. Critical decision thought process. Let's see - trying to help company - plane overflies perfectly good divert airport for one farther away...wonder how that will look in the safety report, if anything goes wrong.
Suddenly ATC comes up and gives us a vector to a fix well short of Chitose and tells us to standby for holding instructions. Nightmare realized. Situation rapidly deteriorating. After initially holding near Tokyo, starting a divert to Nagoya, reversing course back to Tokyo then to re-diverting north toward Misawa, all that happy fuel reserve that I had was vaporizing fast. My subsequent conversation, paraphrased of course...., went something like this:
"Sapparo Control - Delta XX requesting immediate clearance direct to Chitose, minimum fuel, unable hold."
"Negative Ghost-Rider, the Pattern is full" <<< top gun quote <<<
"Sapparo Control - make that - Delta XX declaring emergency, low fuel, proceeding direct Chitose"
"Roger Delta XX, understood, you are cleared direct to Chitose, contact Chitose approach....etc...."
Enough was enough. I had decided to pre-empt actually running critically low on fuel while in another indefinite holding pattern, especially after bypassing Misawa, and played my last ace...declaring an emergency. The problem with that is now I have a bit of company paperwork to do but what the heck.
As it was - landed Chitose, safe, with at least 30 minutes of fuel remaining before reaching a "true" fuel emergency situation. That's always a good feeling, being safe. They taxied us off to some remote parking area where we shut down and watched a half dozen or more other airplanes come streaming in. In the end, Delta had two 747s, my 767 and another 767 and a 777 all on the ramp at Chitose.
We saw two American airlines planes, a United and two Air Canada as well. Not to mention several extra Al Nippon and Japan Air Lines planes.
Post-script - 9 hours later, Japan air lines finally got around to getting a boarding ladder to the plane where we were able to get off and clear customs. That however, is another interesting story.
By the way - while writing this - I have felt four additional tremors that shook the hotel slightly - all in 45 minutes.<!--QuoteEnd--></div><!--QuoteEEnd-->
Re-quoted from another forum, no source available.
<!--quoteo--><div class='quotetop'>QUOTE </div><div class='quotemain'><!--quotec-->Japanese authorities have raised the severity rating of their nuclear crisis to the highest level, seven.<!--QuoteEnd--></div><!--QuoteEEnd-->
Image caption: "Hidehiko Nishiyama, spokesman for Japan's Nuclear and Industrial Safety Agency: 'This doesn't mean people's safety is in danger'"
lolfighter confused.
It's like in Red Dwarf, they're accelerating but the acceleration rate is decreasing, so they're slowing down but they're still going faster.
<!--quoteo(post=1840666:date=Apr 12 2011, 03:33 PM:name=lolfighter)--><div class='quotetop'>QUOTE (lolfighter @ Apr 12 2011, 03:33 PM) <a href="index.php?act=findpost&pid=1840666"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->lolfighter confused.<!--QuoteEnd--></div><!--QuoteEEnd-->
Everything is fine, media is just being media again.
edit: as for the stability/acceleration analogy, I would say it's more like danger = distance and stability = speed. It's slowing down, but damage done has already been done.
That's the joke, lolf.
"...that didn't make much sense to Holly.
Another thing was that the ship's engines when told to stop could only do so slowly, so they were still accelerating, but the rate was dropping. So they were slowing down, but still going faster.
That didn't make much sense to Holly, either."
Anyway, back to the disaster at hand.
<a href="http://www.theregister.co.uk/2011/04/12/fu" target="_blank">http://www.theregister.co.uk/2011/04/12/fu</a> kushima_ffs/ (cursed censoring... just remove the space)
Everything is fine, media just being media.
Anyways its true that people are afraid of and do not well understand radiation, that is part of the reason why the ######ushima plant is leading the news but it would be anyways. Really bad things that happen are always big news but people learn all they care to know about it and then lose interest. But bad things that happen and are still on going and have the potential for getting worse hold people's attention much longer and will always dominate the news, ######ushima plant, economic mess, wars, Gulf oil spill, Chile mine collapse.