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Post by caucasoididiot on Mar 19, 2011 10:03:15 GMT -5
The IAEA site has now added a table of the various aspects of the situation, color-coded by present severity. Unfortunately it's not an image, so I can't cut and paste it. Te fuel elements are about half-covered with coolant water, and the containment vessels in units 2 & 3 are damaged. However, FNN's latest report says that the offsite power tap to this section of the plant has been completed, and workers are are presently working to bring the coolant systems back online, the time this may take dependent on how much damage they find. As to the spent fuel pools, diesel pumps are now running the circulation pumps in units 5 & 6 and their temperatures are stabilizing. The fire at unit 4 is still smoldering but not presently a major problem, and pumper trucks are still concentrating on unit 3. Small amounts of iodine-131 contamination of milk and spinach have been found in Ibaraki, more than 65km from the plant. No other isotopes have as yet been detected, and while the levels are above national food safety standards they are not high enough to constitute a present danger. However, this has prompted an order for evacuees under age 40 to be given prophylactic iodine in measured doses. The first two links in my sig are the source for most of this and include further details. Edit: Duh. Finally occurred to me to screen cap it:
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Post by caucasoididiot on Mar 20, 2011 9:57:26 GMT -5
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Post by caucasoididiot on Mar 21, 2011 11:41:55 GMT -5
The IAEA site doesn't yet mention it, but according to FNN they have released a statement saying that there are signs the situation at Fukushima is improving. By no means is the situation resolved, but it would appear the most dangerous phase may be behind us.
I've been concentrating on the nuclear situation, both because of its gravity and my particular knowledge, but that's only one aspect of the whole situation. Aside from the remaining problems of getting the plants safely shut down and a nasty local cleanup, there are still severe problems providing crucial services in the hardest hit areas, as well as questions about the long term effects of this on everything from agriculture to international finance.
I did hear a caution a few days ago that it may be better to make donations general rather than specific. Money which goes into specified relief funds is earmarked, but sometimes it takes time to sort out just what is needed there and the funds may sit idle for some time. In the meantime, assistance is also vitally needed in places as far flung as Libya and Haiti. It was suggested that donating generally to a reputable organization like the ICRC may be the most effective way to go.
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Post by caucasoididiot on Mar 21, 2011 15:35:10 GMT -5
Latest from World Nuclear News, a report on contamination:
Radiation trends in Japan 21 March 2011
ORIGINALLY PUBLISHED: 5.22pm GMT
UPDATE 1: Addition of data on Japanese average dose
Radiation levels in the wider area around the Fukushima Daiichi nuclear power plant trended downwards for several days, but have recently increased on rainfall. Contamination of food appears limited at present.
Conditions for workers on the plant site have been alleviated somewhat in the last few days thanks to successful efforts to refill fuel ponds. But safety considerations there are on a wholly different scale from those in nearby areas already evacuated or further afield in cities such as Tokyo.
According to the Research Organisation for Information Science and Technology, a typical person in Japan receives an average radiation dose of about 3750 microsieverts per year. Some 60% of this is voluntarily received from medical procedures - such as X-rays and CT scans. A CT scan of the chest can contribute some 7000 microsieverts, according to Japan's Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A nuclear worker by contrast is allowed to receive a dose of up to 20,000 microsieverts per year, although in practice they often receive very much less. In emergency situations it is acceptable for workers to receive up to 100,000 microsieverts. Below this it is statistically difficult to connect radiation dose to cancer rates, but above this the relationship starts to become apparent. An exception has been made in the current crisis to allow emergency workers to receive exposures up to 250,000 microsieverts. Only one worker involved in a steam venting operation some days ago has been confirmed to have received more than the 100,000 microsievert level.
Wider area
Radiation detectors in central Japan have shown elevated readings since the Fukushima accident worsened on 15 and 16 March, with venting from reactor containment, the apparent damage to unit 2's torus suppression chamber and fires and explosions at units 1, 3 and 4.
Detectors in several regions, but especially to the south in neighbouring Ibaraki prefecture, have shown clear spikes in radiation. At around 7.30am on 15 March these showed 5 microsieverts per hour in Tokai village as a short-term peak, but this decreased (with some oscillation) to less than 0.2 microsieverts per hour around 20 March. This has risen again to just less than 0.5 microsieverts per hour today, most likely due to the widespread rainfall in the area. Measurement of background radiation for Ibaraki provided by MEXT show a range of 0.036 microsieverts per hour to 0.056 microsieverts per hour.
These readings are caused by the passage overhead of a mixture of gases and possibly fine particles from the nuclear power plant, which disperse with distance. In addition the radionuclides involved are also decaying, and thus reducing in potency. The readings represent a value for a single location at a single time and so give only a rough idea of what any member of the public in that area may have actually been exposed to. At the rates described above the passage of the materials will have had no measurable effect on the general public's health.
The possibility of higher exposure to the public nearer the power plant has been precluded by the early evacuation of the people closest to the plant. An evacuation of the first two kilometres was ordered within hours of the earthquake and tsunami when it was clear that the Fukushima Daiichi plant was in trouble. Among the evacuees would have been most power plant workers as well as their families, along with other residents.
This zone was subsequently widened to three kilometres, then ten, then to 20 kilometres as people were cleared from the highest priority areas and the situation developed. Currently the zone stands at 20 kilometres with people in a further ten kilometres recommended to stay indoors. The Japanese government has given advice to populations in the wider area to help avoid contamination during rain showers.
Despite unhelpful contradictory comments from some overseas nuclear regulators, the World Health Organisation backed the Japanese authorities, saying "These recommendations are in line with those based on accepted public health expertise."
Monitoring of food
The presence of certain radioisotopes in food has been confirmed by government checks for iodine-131 and caesium-137. Some have been noted to be above the Nuclear Safety Commission of Japan's conservative indices, which are for the time being enforced as regulation in Japan.
The indices are based on a person's consumption of the foods at elevated levels for a whole year, not simply a single meal. Iodine-131 has a half-life of eight days, meaning its risk passes in a brief period after a release. Caesium-137, however, has a half life of almost 31 years and so could potentially present a longer-term risk to agriculture. Both of these would be subject to the action of water over time, which may wash contaminants to sea depending on the kind of ground upon which they were deposited.
In Ibaraki prefecture some samples of leaf vegetables, such as spring onions and spinach, have been measured above index levels of 2000 becquerels per kilogram for iodine-131, or of 500 becquerels per kilogram of caesium-137.
In the town of Kawamata, three milk samples showed above 300 becquerels per kilogram in iodine. Caesium-137 was detected in one sample but in concentrations below the indices.
As yet, 40 of 46 tests of drinking water have shown no detection of iodine-131 or caesium-137. Six have exhibited signs of iodine-131, said the International Atomic Energy Agency, though the concentration was below emergency monitoring criteria.
It is possible that current rainfall will bring contaminants to earth more quickly than would happen in dry conditions. This could of course result in more finds of contamination above the index levels in coming days.
Potassium-iodide pills have been distributed to evacuation centres to protect against the possibility that iodine-131 could be absorbed by a person's thyroid gland, which is the clearest risk of cancer following this kind of radioactive release. People leaving the 20 kilometre zone to travel through the further ten kilometre zone have been recommended to take the appropriate dose of potassium iodide since 16 March.
Researched and written
by World Nuclear News
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Post by caucasoididiot on Mar 22, 2011 9:21:00 GMT -5
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Post by caucasoididiot on Mar 23, 2011 9:35:59 GMT -5
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Post by caucasoididiot on Mar 24, 2011 9:42:58 GMT -5
The latest news is that the iodine levels in tap water have receded, and the caution against use lifted.
NPR mentioned two plant workers having been hospitalized for radiation exposure after having stood in contaminated water while making electrical repairs. So far that hasn't shown up on the official pages, but is exactly the kind of danger they face during this cleanup phase. NPR also had a piece echoing Tokyo Cooney's observation that the foreign media have panicked over the nuclear situation far more than the Japanese themselves.
Yesterday there was also a revised estimate that the crest of the tsunami at the Daiichi plant was as high as 14 meters. Wow.
Edit: FNN confirms the hospitalized workers, claiming that they received 170~180 mSv (17~18 REM). Thankfully that's not enough to produce acute radiation sickness, but plenty to raise the spectre of later cancer.
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Post by crowschmo on Mar 24, 2011 20:42:24 GMT -5
There was another quake in Myanmar. It's situations like this that make you feel so helpless. Feels like the world is coming apart at the seems, there seems to be so much seismic activity of late. There was even a small quake in Connecticut today - my state. Didn't feel it. I gave to the Red Cross, that seems kind of like a drop in a bucket, but every little bit helps, I guess. Those people over in Japan are very strong and resilient. They should be saluted for how they are handling this catastrophe. How are they ever going to clean this up? Day by day, a little at a time, I guess. This was just horrible.
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Post by caucasoididiot on Mar 25, 2011 12:07:11 GMT -5
World Nuclear News has posted a good update. The situation remains generally stable, with offsite power restored and restoration of monitoring and control equipment progressing. There's now some detail on the two hospitalized workers. They were standing in ankle deep water in one of the turbine buildings, and some warning alarms seem to have been ignored because they weren't in a reactor area. The result was what's called a "beta burn," localized damage to the skin surface of their feet. Better news comes from monitoring of the evacuees. All children have now had thyroid exams, and none show signs of significant contamination. www.world-nuclear-news.org/RS_Fukushima_Daiichi_two_weeks_on_2503111.htmlA friend living in Chiba says that the aftershocks are still so frequent that he feels like he's in a ship at sea, and people are starting to call the resulting stress "earthquake sickness."
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Post by caucasoididiot on Mar 27, 2011 10:06:55 GMT -5
There hasn't been anything too startling over the last couple of days, but there are a few random sweepings.
The situation at Daiichi units 1~3 remains "serious," thought work continues to restore monitoring and control. They're shifting over to fresh water injection to get around the corrosion and salt buildup issues of the seawater. They continue to punmp water into spent fuel pools 1~4.
I did see a headline or two the other day presenting the "hot" water in the basement level of unit 3 as a major new development. It really isn't. From shortly after the explosion there these many days ago there's been reason to suspect that something was leaking there. Latest reports are that all three reactor vessels appear intact, but both units 1 & 3 have compromised piping leading to such contaminated water in the basement, and efforts to pump it into the condensers are a major actvity just now.
In the short term, this is mainly a danger to the workers trying to restore the plant, as the two hospitalized the other day show. As an aside, their beta burned feet seem to have been the result of contaminated water having gotten inside the rubber boots they were wearing. In the longer term that water raises the issue of ground-water contamination in the area, and is one of the things to watch for in coming weeks.
As to external contamination, 28 of the 45 proximate prefectures have registered no deposition in the last reported week, and in the others rates have continued to be pretty low. The highest dose rates yet measured in Tokyo are comparable to normal background in Denver. IAEA does not specify where, but drinking water warnings for infants have been issued in six locations and for adults in one. Note that these are precautionary. Unacceptable levels of contamination have cropped up in produce in Chiba, Ibaraki and Tochigi (basically the region between the plant and Tokyo) but again, the levels are such as to indicate precautionary measures rather than real danger.
The real victims remain those in the evacuation centers in the tsunami struck north. My friend in Chiba reports that the sorts of food that last without refrigeration are still hard to come by as it's being shipped there, along with critical supplies like batteries. The weather continues cold and wet, but endurance is a Japanese strong point.
On the global scene, Japan has long positioned itself as a global supplier of precision machine parts. These are often made in little "mom'n'pop" machine shops, and especially in older neighborhoods you'll find these little family businesses tucked into random corners of residential areas. With the supply od raw materials disrupted they've been unable to produce at anything like the world demand level. China is moving to fill that global demand.
That's the sort of fallout which will probably be Japan's greatest burden in the months and years to come.
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Post by caucasoididiot on Mar 28, 2011 12:44:50 GMT -5
OK, I'm far from clear on a lot of the details of this, as the English technical sites hadn't described it last I checked. I'm basing this on what I can piece together from Fuji News and some slightly dodgy English language reports from Tepco and JAIF. Reactor bldg far left, turbine bldg center, trench, ocean. The issue is that in apparently all three of the problematic reactor areas water is seeping through piping channels in the turbine rooms into an outside trench. Unit 2 is apparently the one of great concern as the water is nearing the top of that structure and has a high exposure rate at its surface (greater than 1 Sv/hr, ie 100 REM/hr). That is a significant rate, because 100 REM is the roughly the level for acute rad sickness. This is complicating continuing efforts to cool that reactor as further water injection risks causing spillover from the trench and drainage into the sea some 55m away. At present they are trying to pump out the contaminated water and are discussing sandbagging and cofferdams to limit spillage, but have not yet begun constructing these. With that high a radiation field it will be a tricky operation. At this time all the actual reactor vessels seem to be intact, but the toroidal suppression tank in two appears to be damaged, releasing fuel contaminated water. This is the apparent reason for the high rate in this water and is suggested by the isotopes present there. I wish I were clearer on this myself and will provide more substantive information as I find it. Edit: Here's NHK's report on the trench: www3.nhk.or.jp/daily/english/28_h37.htmlAlso, there are reports of Plutonium having been found in soil at the plant. This may have come from the fuel pool fires, but the amount is so low as to be typical of that found "in the environment": www3.nhk.or.jp/daily/english/29_02.html
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Post by caucasoididiot on Mar 29, 2011 9:56:15 GMT -5
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Post by caucasoididiot on Mar 30, 2011 18:58:25 GMT -5
And the latest is that they now believe the water in the trenches, and perhaps the internal flooding as well, came from the tsunami. This would make the high radioactivity of that associated with reactor 2 difficult to explain, however: www.world-nuclear-news.org/RS_Tsunami_likely_filled_trenches_3003112.htmlOtherwise, not much has changed. They're getting the water of the areas under repair, either into local condensers or a large surge tank nearby. Temperatures are coming down in unit 1, and while slightly up in unit 2 aren't terribly high. The situation on external contamination hasn't changed much, though some of the drinking water warnings have been lifted. Oh, I'm not sure how much this has been reported, but on the topic of the plutonium found at the site. Reports stated that it was comparable to the pre-existing background levels. These levels are the result of fallout from nuclear testing in the '50s and '60s. They can tell that some of the material is recent, however, by looking at the isotopic concentrations. The upshot of that is that while their has been some plutonium contamination locally its level is comparable to that left by testing in the South Pacific and Kazakhstan decades ago and is thus thankfully small.
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Post by caucasoididiot on Mar 31, 2011 10:16:44 GMT -5
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Post by caucasoididiot on Apr 1, 2011 9:46:42 GMT -5
The current issue at Fukushima is contaminated water management. They have to keep injecting it into the hot reactors and pools but are running out of places to store the contaminated water accumulating therein. Leakage of such water into the sea also seems to be the greatest current source of external contamination. Tepco is arranging for an extensive system to store and treat both the water in the plant and the runoff from the ground at the site: www.world-nuclear-news.org/RS_Tepcos_plans_for_water_issues_0104112.htmlAnd while it's true that it's 1 April, I kid you not, the model of the high volume concrete pumper that saved the day at fuel pool 4 was a "Putzmeister 58." www.world-nuclear-news.org/RS_Concrete_pumps_to_Fukushima_0104111.html
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