#564719 - 09/16/1109:44 PMRe: Possible meltdown in Japan
[Re: lanovami]
lanovami This space for rent
Registered: 05/02/05
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Even after months and the months, the same catch 22 that prevailed at Fukushima Daiichi still prevails. Even at these greatly reduced temperatures in the cores/slag heaps, they still need constant inflows of water or they will immediately start to heat up again. This means the water will continue to leak out and continue to feed the pools of water beneath the containment. This water in turn makes it too radioactive for anyone to get near and find and seal the leaks. This means years of doing basically the exact same thing. Even properly spent fuel rods - let alone fuel rods suddenly deprived of cooling capacity in a crisis - have to be kept in water for at least a year after use before they can be put in sealed dry storage. TEPCO's time table for national bliss says they will proceed to seal the leaks at such and such a time if things proceed, but I have heard nothing about HOW they plan to seal them.
Meanwhile, we have to sit around and hope nothing big comes along to shake things up and release this mess to the surrounding environment again. I suppose the rain season is behind us, so at least no more residual water will be added to the leaking water.
I don't even want to talk about the food. It is in many ways the issue for all of us outside the exclusion zone, but there are so many unknowns that I'd rather concentrate on signs of progress at the site itself.
_________________________ We are what we repeatedly do - Aristotle
#564720 - 09/16/1110:00 PMRe: Possible meltdown in Japan
[Re: lanovami]
lanovami This space for rent
Registered: 05/02/05
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But of course, I can't stop reading about it, so here is another sobering article from an expert in Japan. If you don't read it all, at least read the last line.
As a radiation metrology and nuclear safety expert at Kyoto University's Research Reactor Institute, Hiroaki Koide has been critical of how the government and Tokyo Electric Power Co. (TEPCO) have handled the nuclear disaster at the Fukushima No. 1 nuclear plant. Below, he shares what he thinks may happen in the coming weeks, months and years.
The nuclear disaster is ongoing. Immediately after the crisis first began to unfold, I thought that we'd see a definitive outcome within a week. However, with radioactive materials yet to be contained, we've remained in the unsettling state of not knowing how things are going to turn out.
Without accurate information about what's happening inside the reactors, there's a need to consider various scenarios. At present, I believe that there is a possibility that massive amounts of radioactive materials will be released into the environment again.
At the No. 1 reactor, there's a chance that melted fuel has burned through the bottom of the pressure vessel, the containment vessel and the floor of the reactor building, and has sunk into the ground. From there, radioactive materials may be seeping into the ocean and groundwater.
The use of water to cool down the reactors immediately after the crisis first began resulted in 110,000 cubic meters of radiation-tainted water. Some of that water is probably leaking through the cracks in the concrete reactor buildings produced by the March 11 quake. Contaminated water was found flowing through cracks near an intake canal, but I think that's just the tip of the iceberg. I believe that contaminated water is still leaking underground, where we can't see it. Because of this, I believe immediate action must be taken to build underground water barriers that would close off the nuclear power plant to the outside world and prevent radioactive materials from spreading. The important thing is to stop any further diffusion of radioactive materials.
The government and plant operator TEPCO are trumpeting the operation of the circulation cooling system, as if it marks a successful resolution to the disaster. However, radiation continues to leak from the reactors. The longer the circulation cooling system keeps running, the more radioactive waste it will accumulate. It isn't really leading us in the direction we need to go.
It's doubtful that there's even a need to keep pouring water into the No.1 reactor, where nuclear fuel is suspected to have burned through the pressure vessel. Meanwhile, it is necessary to keep cooling the No. 2 and 3 reactors, which are believed to still contain some fuel, but the cooling system itself is unstable. If the fuel were to become overheated again and melt, coming into contact with water and trigger a steam explosion, more radioactive materials will be released.
TEPCO says it is aiming to bring the No. 1, 2 and 3 reactors to cold shutdown by January 2012. Cold shutdown, however, entails bringing the temperature of sound nuclear fuel in pressure vessels below 100 degrees Celsius. It would be one thing to aim for this in April, when the government had yet to confirm that a meltdown had indeed taken place. But what is the point of "aiming for cold shutdown" now, when we know that fuel is no longer sound?
In the days ahead, the storage of enormous quantities of radiation-contaminated waste, including tainted mud resulting from the decontamination process, will become a major problem. Because the responsibility for spreading nuclear materials into the environment lies with TEPCO, it makes sense to bring all the radioactive waste to TEPCO headquarters in Tokyo.
Since that's not possible, the waste should be taken to the grounds of the nuclear power plant. If the plant is not large enough to accommodate all the waste, then a location close to the plant will also have to be designated as a nuclear graveyard. However, no one should take advantage of the chaos and force Fukushima to host interim radioactive waste repositories for spent fuel from other nuclear power plants.
Recovering the melted nuclear fuel is another huge challenge. I can't even imagine how that could be done. When the Three Mile Island accident took place in 1972, the melted nuclear fuel had stayed within the pressure vessel, making defueling possible. With Fukushima, however, there is a possibility that nuclear fuel has fallen into the ground, in which case it will take 10 or 20 years to recover it. We are now head to head with a situation that mankind has never faced before.
_________________________ We are what we repeatedly do - Aristotle
#564721 - 09/16/1110:10 PMRe: Possible meltdown in Japan
[Re: lanovami]
lanovami This space for rent
Registered: 05/02/05
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Loc: 東京都
The gists of his points:
TEPCO aims for a cold shutdown, but the definition of a cold shutdown means that the nuclear fuel is all completely inside the pressure vessels, which it is surely not.
The reactors, especially no. 1, have likely burned completely through to the ground. He is not even sure they need to be pumping water into no. 1 anymore. And this will or may already be seeping into ground water and the ocean.
He, an expert, can't even imagine how recovery of the nuclear fuel could be accomplished in the current situation.
_________________________ We are what we repeatedly do - Aristotle
It's a very bad situation that should be a counter example for other countries.
Maybe, i'm not sure, nuclear power plants should be phased out and new construction stopped. We are seeing the enormous risks present in the nuclear industry knowhow.
It is true that radioactive material is necessary for medical purposes and for other uses that do not imply great quantities of nuclear material be present. We can assume these uses will continue.
We need to admit that a similar nuclear accident, or whatever variations of them are possible, could happen in any part of the world, in the near or more distant future, given the actual climatic and geologic events that seem to be on the rise in number and severity.
We are risking contaminated hot spots wherever there is a nuclear power plant. That would mean a growing series of similar leakage problems could, eventually, be occurring around the world in the next decades, and consequently potentially creating those difficult to control nuclear pollution sources.
There are, also, the issues of the disposal and storage of spent fuel and other nuclear materials. [I will just mention, in passing, that wars, "conventional" or nuclear, have already contributed, are contributing to the factual radiation levels, and may contribute to them in the future.]
To me it's obvious that: for a living being to be able to exist; for it being able to reproduce and evolve; its food supply and the source of nourishment for new beings [from which it must necessarily draw matter and energy to grow] must exist previously to that being's existence.
The ultimate question is if Humans or at least our radiation contaminated descendants are going to be able to adapt to the rising radiation levels that appear to be going to be a part of our future and, be able to assimilate those rising future levels present in our future food supply.
I anyone thinks it would be interesting to know what Professor Hiroaki Koide thinks about the real possibilities of, —in face of the Japanese experience with the viabilities and risks of nuclear energy in general—, successfully continuing to pursue nuclear energy through these and other kind of power plants, they can read "Engineer dismantles facade of Japan's nuclear industry".
#565157 - 10/02/1106:50 AMRe: Possible meltdown in Japan
[Re: NucleusG4]
lanovami This space for rent
Registered: 05/02/05
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Loc: 東京都
In case you were on the edge of your seat for another update:
Good news: All three troubled reactors are now very securely under the boiling point of water, and though it hasn't been officially announced, they are in a state the gov't and TEPCO were aiming for "cold shutdown", and this is 3 months ahead of schedule. This means no more steam releasing more radiation.
Even this good news has a caveat. The actual pre-crisis definition of a "cold shutdown" expressly assumes the reactor is in it's containment vessel which is almost certainly not the case in either of the 3, especially in number 1, which has very likely leaked out near completely. There is however, something down there as it is still around 75 degrees.
Other good news: the government rescinded the 'in your own time" evacuation order for the 20-30 kilometer radius. I think this is premature. There may be no more spewing radiation, but there are definitely pockets in there that are at Chernobyl levels. But it is a sign of progress I guess. I don't think anybody is rushing back to live there just yet though. Private citizens have invested a lot of money in buying the best radiation detectors and are registering numbers that makes one scratch his head at why they have lifted the 20-30 km radius ban so easily.
Bad news: The sea was expected to disperse the cesium spilled into it far and wide around the world to the level of no danger to anyone or anything, but this has not appeared to be the case. For some reason is not dispersing like they thought it would and is largely staying put in a swath off of Fukushima. There is speculation that radioactive material may still be leaking into the sea and is keeping numbers from going down. Again, no one knows for sure.
In connection with this, it is not any surprise, but though Chernobyl released over 5 times the radioactivity over a much larger area, Daichi is by far the worst nuclear accident in terms of it's effect on the sea. Chernobyl comes nowhere near the impact Daichi wreaked or wreaks on the sea.
More bad: thought they have the core temperatures down, typhoon rains have raised the levels of water under the reactors to near overflowing again. There is also speculation that groundwater is leaking in. If groundwater is leaking in, the radioactive cocktail inside is sure to be leaking out.
And there you have it.
_________________________ We are what we repeatedly do - Aristotle
#566006 - 10/20/1111:32 AMRe: Possible meltdown in Japan
[Re: katlpablo]
lanovami This space for rent
Registered: 05/02/05
Posts: 7405
Loc: 東京都
I am still following things of course.
All three reactors are down to the 70s, very clearly no danger of any more hot particles, it remains to be see in the long run how secure whatever the mess down there in those three locations is, and if anything is slowly leaking out.
The gov't has opened up schools in some of the areas that had been evacuated inside the 20-30 km ring, area that have now been deemed safe enough by the government. Most of the schools have about a third of the students they did when they were closed. There is a lot of criticism that it was too early. Kids at these schools are only allowed outside for an hour or so and must wear masks when they do. Most kids are driven by their parents to avoid any increased exposure to outdoor radiation (driving one's kid to school is not at all a common practice in Japan normally).
The science club at my school took upon itself to measure the rad levels around our school. Some gutter areas etc. are measuring as high as .4 microsieverts per hour, a figure that legally requires decontamination, but no concrete moves yet. Again these numbers are lower than some areas people are living in closer to the plant, but my school's area just northeast of Tokyo is officially one of the hotspots, an area hundreds of kilometers from Daichi, but higher than areas just around it.
And I just heard on the news tonight that the Japanese government is will likely move on widening the legally mandated evacuation zone in any future nuclear disasters/scares from 10 kilometers to 30 kilometers. Ironically, this is the the number the gov't finally deemed was enough after several revisions of the evacuation zone in the days following the disaster. I can imagine the anger that must be felt by the people who sat for something like a month in the 20-30 km ring and were told to stay inside until further notice.
_________________________ We are what we repeatedly do - Aristotle
The gov't has opened up schools in some of the areas that had been evacuated inside the 20-30 km ring, area that have now been deemed safe enough by the government. Most of the schools have about a third of the students they did when they were closed. There is a lot of criticism that it was too early. Kids at these schools are only allowed outside for an hour or so and must wear masks when they do.
That just strikes a picture of complete absurdity in my mind....