Posted on 04/20/2011 2:52:34 PM PDT by ransomnote
Thank You. No one seems to have an argument left. I do not trust the #s, it’s my nature.
http://atmc.jp/school/
“The radiation dose to the public schools of Fukushima Prefecture Fukushima disaster headquarters is distributed on the map.”
Google takes longer to translate this page into English.
Hmmmm...that link lists schools in the prefecture and has a map with readings but I do not understand the information. I imagine that this kind of transparency is welcomed by the locals. It looks like this info became available on the 18th of April.
So if we have a quick complete meltdown in reactor 1 or 2 or a major meltdown in #4, the site will have to be abandoned due to high radiation levels. In the case of Chernobyl, the Russians sacrificed some workers to contain the break out. The dynamic nature of this event with multiple problems and future aftershocks, will make any future plan more difficult then just sacrificing some of the workers. And a complete meltdown would make the land near the plant a Chernobyl no-go zone. The rest of the world will have to deal with long term exposure issues.
The readings are in micro sieverts per hour which means avoid exposure. Readings in milli sieverts per hour mean get out of the area and they only occur within a mile or two of the plant and are not shown. Interesting that the highest micro sievert readings shown are located quite a bit inland from the plant.
It must be true because I read it on the internet (FreeRepublic).
:)
Here’s a Wikipedia link to ‘melt down’.
http://en.wikipedia.org/wiki/Nuclear_meltdown
I’ll post my comments based on what I’ve read on various internet sites and videos.
Looks like Wiki refers to reactors - in the Fukushima case, each reactor also has a pool of water suspended above it that contains ‘spent fuel’. In March, some experts were saying that if the fuel in spent fuel ponds was not covered with water, it would heat up, possibly catch fire (and the ‘smoke’ would be radioactive) and/or melt and drop to the bottom of the pool. If fuel were to drop to the bottom of the spent fuel ponds in small dispersed droplets, the theory is that there would be sufficient exposure to water to cool the droplets. The other concern though was, if the spent fuel rods melt and enough of the melted fuel mounds up on the bottom, it can have a ‘cooling geometry’ that prevents it from being cooled (if it’s in a big lump there’s no way to get coolant (water) into the heated areas.) In that scenario, it is theoretically possible that largish lumps of melted fuel on the bottom of the tank would had sufficient heat to melt through the bottom of the pond. (draining the rest of the water and exposing the rest of the fuel) Thus far, the fuel doesn’t appear to have caught fire in a significant way (if it has, I didn’t see anything about it) although it can still give off radiative contaminants into the air as long as it is exposed. We want the fuel in the spent fuel ponds to be be cool, covered, and if melted, in such a way that the drops reaching the bottom of the ponds can themselves be cooled and do not melt through the bottom of the pond.
If a ‘melt down’ occurs in the reactor, there are various scenarios, some of them theoretical. The Soviets did have a melt down (Chernobyl), so to speak. Their fuel rods did melt through the bottom of the reactor (And Soviets did not have a containment vessel surrounding the reactor like the ones in Japan do so the Soviets were operating without a net, so to speak). And the fact that Soviets had a fuel melt down is not what directly caused the contamination and deaths. (Fatalities, illness, contamination was due to the fact that the Soviet reactor exploded and without a true containment structure, a significant amount of radioactive contents (fuel rods and graphite blocks) were ejected into the air and surrounding countryside.) But the Japanese do have a ‘containment structure’ designed to contain radioactive material in this kind of situation.
Predicting what melted fuel will do in a ‘melt down’ is difficult, it seems. By the time the Soviets were able to stick a camera down into the reactor - they were surprised to see no fuel there. The melted fuel had melted down through some levels of the basement (melted due to radioactive heat)under the reactor. The Soviets believed it was resting on a cement slab at the lowest level of construction. Their theory at the time was that the molten fuel could melt through the concrete slab and if the molten fuel contacted the water table below, it could explode and force the rest of the radioactive material into the air and surrounding countryside (they believed this would devastate much of the Ukraine and ‘half of Europe’). They also theorized that some fuel would remain sufficient to contaminate the water table for Russia and parts of Europe.
So the Soviets had miners dig under the cement slab to install another protective layer. When they finally were able to photograph the melted fuel in the basement, it looked like a lava flow and it had blended or mixed with the large amounts of sand that the Soviets had surrounding the reactor core so it formed a sort of glass. They were delighted because they believed the fuel/glass mixture ‘sealed’ the uranium in glass and would therefore not be likely to explode if it reached water. Note that Japan does not have the same reactor design (Japan has a containment structure) and it also doesn’t have this big store of sand. Over time, the glass/fuel mix in Chernobyl has become pitted and some scientists believe it is potentially explosive if water flows through the pores of the pitted glass mixtures. So the Soviet story of ‘what happens in a melt down’ is not quite complete yet.
The Japanese have a different reactor and different access to technology to address it. They have a containment vessel (safety net) that the Soviets didn’t have. They have asked for help cooling the reactor and are receiving assistance (unmanned helicopters, robots, special remote pumps etc)that the Soviets did not ask for or receive. The fuel melting in a reactor would have to remain hot enough and resist cooling (form a big hard-to-cool lump) to melt through the containment vessel (which is designed to combat this) and I don’t know how many levels of construction underneath it before it could contact the ‘outside’ or possibly the water table. Theoretically, if it somehow got past containment and whatever other levels exist below it, then there’s a theory that it could contact the water table and explode. That would be a worst case scenario as would anything that happens to a reactor or spent fuel pond that prevents access (ability to cool) fuel in the other ponds. Since melted fuel has never broken through the bottom of a containment structure nor reached the water table before, some scientists point out that it could simply cool in place or mix the way the Soviet fuel did with surrounding rock and cement. Wiki has nice detailed drawings and a more scientific explanation. Rooting for the Japanese people to win their battle.
Hey I think I read that on FR too!!! *smiling*
Hey I think I read that on FR too!!! *smiling*
Would suggest you research what happened to the eastern Polish regions during the Chernobyl fallout. We hope the most significant short term release from Fukushima will be much less then Chernobyl, but the exposure period with Fukushima is already much longer then Chernobyl. So in the end they will probably be comparatively equivalent and that is probably why they raised total radiation exposure to a Level 7 event.
I guess if we see them starting to dump truckloads of sand onto a reactor we will know the jig is up ?
I was wondering about TMI. Thanks for the overview - I needed it as I mulled this situation this evening. I can’t picture the region you are referring to - nor the seals. I think I need to do some reading on TMI.
I was wondering about TMI. Thanks for the overview - I needed it as I mulled this situation this evening. I can’t picture the region you are referring to - nor the seals. I think I need to do some reading on TMI.
Hey thanks for the help!
Hey I like your reply to Redshawk much better than mine (concise and yet a good overview). I would not have bothered with my drivel if I had seen yours - I mistakenly thought no one had replied so I gave it a shot. Thanks.
The liklihood of a catastrophic “meltdown” is, IMO, remote and growing more so as the mass of steel/rods, etc cool. Exposure of the rods means slow neutrons can escape, further reducing reaction events and consequent heat generation. Barring something unforseen, (like another major quake nearby) what’s going to result is a protracted clean up of the site. I suspect most of the contamination surrounding the plant will degrade to safe levels within a few years at most.
The Japanese/GE design in no way is remotely akin to Chernobyl, being a light water moderator, not combustible graphite and built within a containment structure. >PS
The containment issue that you've described, reminds me of microwaving a cup of water to boiling. When you attempt to remove the cup of superheated water from the microwave, and the water touches the sides of the coffe cup, the water ‘explodes’.
I also appreciate your explaination of how the Japanese containment is better that Chernobyl. I was saddened to here that Chernobyl is still could be/ or is still, a danger.
Dang, the Japanese folks seem like they are in for a big hurt for a long time.
Thank you again ransomnote.
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