Posted on 03/27/2011 10:26:43 PM PDT by SteveH
IAEA Briefing on Fukushima Nuclear Accident (27 March 2011, 13:30 UTC)
1. Current Situation
The situation at the Fukushima Daiichi plant remains very serious.
The restoration of off-site power continues and lighting is now available in the central control rooms of Units 1, 2 and 3. Also, fresh water is now being injected into the Reactor Pressure Vessels (RPVs) of all three Units.
Radiation measurements in the containment vessels and suppression chambers of Units 1, 2 and 3 continued to decrease. White "smoke" continued to be emitted from Units 1 to 4.
Pressure in the RPV showed a slight increase at Unit 1 and was stable at Units 2 and 3, possibly indicating that there has been no major breach in the pressure vessels.
At Unit 1, the temperature measured at the bottom of the RPV fell slightly to 142 °C. At Unit 2, the temperature at the bottom of the RPV fell to 97 °C from 100 °C reported in the Update provided yesterday. Pumping of water from the turbine hall basement to the condenser is in progress with a view to allowing power restoration activities to continue.
At Unit 3, plans are being made to pump water from the turbine building to the main condenser but the method has not yet been decided. This should reduce the radiation levels in the turbine building and reduce the risk of contamination of workers in the turbine building restoring equipment.
No notable change has been reported in the condition of Unit 4.
Water is still being added to the spent fuel pools of Units 1 to 4 and efforts continue to restore normal cooling functions.
Units 5 and 6 remain in cold shutdown.
We understand that three workers who suffered contamination are still under observation in hospital.
2. Radiation Monitoring
Dose rates at the Fukushima site continue to trend downwards.
In 28 of the 45 prefectures for which data are available, no deposition of radionuclides was detected in the period 18 to 25 March. In seven of the other 17 prefectures, the estimated daily deposition was less than 500 becquerel per square metre for iodine-131 and less that 100 becquerel per square metre for caesium-137.
On 26 March, the highest values were observed in the prefecture of Yamagata: 7 500 becquerel per square metre for iodine-131 and 1200 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, the daily range was from 28 to 860 becquerel per square metre. For caesium-137, the range was from 2.5 to 86 becquerel per square metre.
In the Shinjyuku district of Tokyo, the daily deposition of iodine-131 on 27 March was 220 becquerel per square metre, while for caesium-137 it was 12 becquerel per square metre.
No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday. In general, gamma dose-rates tend to decrease due to the decay of short-lived radionuclides such as iodine-131.
Two IAEA teams are currently monitoring in Japan. One team made gamma dose-rate measurements in the Tokyo region at 8 locations. Gamma dose-rates measured ranged from 0.08 to 0.15 microsievert per hour, which is within or slightly above the normal background. The second team made additional measurements at distances of 30 to 41 km from the Fukushima nuclear power plant. At these locations, the dose-rates ranged from 0.9 to 17 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 3.1 Megabecquerel per square metre.
The first results of aerial surveys of gamma dose-rates by the Japanese authorities have been received by the Incident and Emergency Centre. These are being analysed and will be presented when more detailed data have been received.
New data from monitoring of the marine environment, carried out from 24 March, 22:55 UTC to 25 March, 03:32 UTC about 30 km offshore, show a decrease in both caesium-137 and iodine 131. The contamination at these locations is influenced by aerial deposition of fallout as well as by the migration of contaminated seawater from the discharge points at the reactor. The measured radiation doses rates above the sea remain consistently low (between 0.04 and 0.1 microsievert per hour). The first results of model predictions received from the SIROCCO Group at the University of Toulouse are being assessed.
Recommendations relating to the restriction of drinking water consumption, based on measured concentrations of iodine-131, remain in place in seven locations (in one location for both adults and infants, and in six locations for infants).
As far as food contamination is concerned, samples taken from 23 to 25 March in five prefectures showed iodine-131 in unprocessed raw milk, but the levels were far below the regulation values set by the Japanese authorities. Caesium-137 was also detected in samples of unprocessed raw milk taken on 23 March in Chiba prefecture, but at levels far below the Japanese regulation values. Caesium-137 was not detected in any of the samples taken from 24-25 March in the other four prefectures.
Based on samples taken on 22 and 24-25 March, three prefectures (Chiba, Ibaraki and Tochigi) reported iodine-131 in celery, parsley, spinach and other leafy vegetables above the regulation values set by the Japanese authorities. Caesium-137 was also detected above the regulation values in one sample of spinach taken on 24 March in Tochigi prefecture, but in the remaining two prefectures, the results were below regulation values.
The Joint FAO/IAEA Food Safety Assessment Team arrived in Tokyo on Saturday. It will meet regulatory officials in various prefectures where food contamination has been detected. The team left for Fukushima early today. The Mission will assist and provide advice on sampling protocols, analytical procedures, data collected to date and actions taken by the Japanese authorities for the control of contaminated foods.
hey look! actual numbers. amazing (obviously not an American news source)
from this, i see the highest level of radiation being 17 uSv/hr. very low. of course, these readings are 30-40 km away from the plant, so i would expect them to be low. point being, it’s not chernobyl
i am unfamiliar with becquerel and how they relate to contamination... maybe someone that is familiar with it will chime in.
thanks for the post.
Thanks for the post even if it did aggravate me. Had researched and figured out “Sieverts” and they change units on me.
Sieverts is a unit of radiation dose, with weighting giving to different types of ionizing radiation sources and targets on the human body.
Bq is a unit of radioactive decay, whereby one Bq is the disintegration of one atomic nucleus per second.
Bq isn’t really meaningful unless we specify a) the point in time at which the measurement was taken, and b) the square area or cubic volume in which the measurement was taken. This is usually expressed as “Bq per square meter” or “Bq per cubic meter” for surface contamination or air volume, respectively, because a Becquerel is a “SI” (ie, Metric) unit of measurement.
NHK World Japan had a report that of the three reactor complexes that have radioactive water in their lower areas, two of the turbine reservoirs are already full of water. Only one has some room to store extra water. So they have to come up with a plan B for clearing the water from those two reactors. Believe that the three reactors with water in their lower areas are 1,2, and 3. Basically the reactors that were injected with seawater directly. Good to see water temps dropping.
Here’s some information on computing gamma-dose equivalents:
http://www.ornl.gov/info/reports/1982/3445603573381.pdf
They normalize the dose equivalence to mSv/h for a unit source of 1 MBq.
And here’s some background on computing dosimetry:
http://complex.gmu.edu/www-phys/phys407/RadiationSafety.pdf
The point of these two pieces being this:
“radiation” isn’t measured in uSv/hr. *Dose* is. You measure radioactive decay in Bq per area or volume unit. Effective dosage of radiation requires some computation.
Let’s back up a moment.
There are four things you’ll see mentioned when talking about exposure to radioactivity:
1. The radioactivity. This will be measured in Curies (’common’ units), Becquerel (SI units), and if we want to get precise, you’ll have to mention the nuclide doing the emitting. A “Curie” is a very large amount of radioactivity, so you’ll rarely seen anything other that fractional Curie measurements (milli, or micro, or smaller).
2. “Absorbed dose,” measured in rad (common unit, meaning “Radiation Absorbed Dose”), or “Gray” (abbreviated “Gy” in SI units).
3. “Dose equivalent,” measured in “rem” (common unit, meaning “Roentgen Equivalent Man”) or “Sievert” (in SI units).
4. Finally, we need to talk about “exposure.” The old unit for measuring exposure to ionizing radiation was the Roentgen, and the new SI measurement is SI charge (in Coulombs) per kilogram of mass.
“Dose equivalent” requires some computation. You need to know the energy and type of ionizing radiation (alpha, beta, gamma radiation, or neutrons/protons/electrons, and then the MeV energy level of same), you need to know the part of the body being irradiated and whether we’re talking bones, flesh, skin, bone marrow, brain, etc. Generally speaking, alpha emitters are weighted more heavily than gamma emissions in this computation.
Clear as mud?
We know this because we have the numbers.
The US Mass Media HATES the numbers. Because they point to specificity, and then that, while it still is a serious situation--and nobody but Almighty God, Praise His name, knows what tomorrow will bring us--there is no "there, there" in terms of the way they generally, with some exceptions, are talking and reporting over there. This takes their whole narrative away from them, therefore loses them viewership, therefore p*sses off their sponsors (who are largely big US PHarma to get people hooked on psychotropic drugs for depression to anxiety to sleeplessness with incessant ads) Believe me, I know by and large how US television works nowadays, the "Breaking News" Syndrome, the cycle--and what they have done to the people over 40 years (made not a few boob tube-hooked Americans neurotic). They want panic, pure and simple. Again, the numbers do not give it to them.
Reporting from Tokyo, live.....
can anyone give me a logical answer as to why heat is still being generated at these plants? we were told that heat generation ceased at SCRAM, it was just ‘cooling down’ that was required. Two weeks of contaminating seawater by cooldown efforts seems very reasonable to bring these reactors to temperature. So why aren’t they?
A friend of mine, whose grandson is living in Tokyo, has been complaining to her that he is having trouble obtaining bottled water as he claimes the shelves are empty every time he tries to purchase some. Of course, this is worrying to her and I wanted to ask you your assessment of the situation as to how true this is.
They have now found high levels of radioactive Iodine in the seawater near the plant for three days in a row. Interesting video in report.
More radioactive substances found in seawater
That higher then normal radioactive Iodine reading was from the effluent near reactor 5 and 6. Later.
Replace stem with steam.
BTTT
I’d call it a slowmo Cherry. The time of contamination release is becoming much longer and more widespread than Cherry, having traveled 9,000 miles so far via jetstream express. Also, instead of getting way up there and circling around in the strato or mesosphere where it would be relatively harmless and could start degrading, it’s coming down already in rainfall with degradation incomplete. Not worrisome yet, because like a time machine, this contamination is from Japan 2 weeks ago, but definitely something to watch in the coming weeks.
CNN reports ‘barely detectible’ isotopes being now measured in Mass. rainfall. This is brand new data that will have to be incorporated into future nuclear planning. This type of farreaching contamination was hinted at during Blue Sky in the 50’s/60’s but the Feds buried that data fast (and left it’s populace to pay for their own cancer treatments over the following decades) - now it’s verified beyond a shadow of a doubt and there’s no more denying it.
This new data does makes me question, if it’s still measurable in rainfall in Pennsylvania and Mass, 9000 miles from Japan, and, if it was supposed to be already totally diluted “5-days’ old barely measureable” when it was hit in my location 6000 miles across the pond from Japan, then what in blazes is the REAL measurement where those farmers are sitting in Japan?
CNN has been reporting where isotopes have been measured (from Seattle to San Diego last week;yesterday it was Nevada, this morning it’s Penn/Mass.) and has been labeled a ‘fearmonger’ for doing so, including by Fox. I don’t think they are, I’d rather know than not know, but the bottom line is, not a dam thing we can do about it, especially considering ‘radioactive isotopes’ is such a broad brush description. I’d go out on a limb and say, iodine isotopes always travel with friends but I’m guessing we’re left to figure that part out by ourselves.
I completely lost faith in Tepco last week when they announced the Tokyo tapwater wasn’t suitable for babies for a few days because of radioactive isotopes but told people they could still bathe in that same water. Not a lot of rocket scientists on board there, I guess, seeing as how iodine is absorbed through the skin. Tepco had also issued a ‘don’t swim in the ocean’ warning but never said why.
Yesterday Tepco reported 10 million/hr reading in Reactor 2, then took over FIVE hours to revise that decimal place to “only” 100,000/hr (this was measured inside reactor 2, not reactor 3 where the radioactive water that the contractors weren’t told about and waded through was). Radioactivewater has been leaking into the ocean all along, either from direct runoff or via shallow water table. The local-area seawater has gone from 1250 to 1850 (although the claim was made that the sea level measurement had ‘gone down slightly’ from 1850.
My understanding is ionizing radiation is cumulative. 17 an hour is supposed to sound all comfy and low - until you multiply it. 1850 in seawater doesn’t sound bad, either, unless you’re a 6-ounce fish.
Maybe Tepco can tell us - with currents, tides and waves, how can seawater be ‘local’ ?? and what is local? 1 mile? 50 miles? 6 miles? 50 feet?)
Decay heat.
You’ll need to look it up on your own, as I have to go, but a BWR doesn’t go from operating heat production to “nothing” instantly. There’s a decay heat that tapers off over the ensuing hours to weeks after shut-down. Immediately after shutdown, the decay heat might be 6 to 7% of the operational power output, which then tapers down.
check. I understand - like a car engine has to cool down after you turn the key off.
But it has been weeks and they keep getting overheats and now have a problem with where to put the water. (is it the mox that’s the overheating problem child?)
I was thinking about that problem and wondered about the other, what ,56? plants in Japan - They must have holding pools, yes? so why not transport as many rods as they can to the other plants?
Less rods mean less total heat, right? which means less water needed onsite.
With the water they’re running out of places to store, can they somehow distill it into containers instead of releasing steam? The result being a lesser-radioactive water that can be also carted away to the other reactor sites and then concentrated particulate that can be thrown back into the reactor to be cleaned up with the rest of the radioactive soup?
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