Login / RegisterRadioactive cesium levels rise sharply in Fukushima, according to citizen watchdog
A Japanese citizen watchdog has reported that cesium-137 levels rose more than five times in Fukushima over a 24-hour period between March 15 and 16.
The online Fukushima Diary pointed out that there were no megabecquerels per square kilometre of cesium-137 detected between March 8 and March 11. But it rose to 17.8 MBq per kilometre from March 11 to March 12. The following day, it reached 25.1, before rising to 128 on the next day.
The Fukushima Diary—which carries the statement "We are against media blackout"—said there was no explanation for the sudden increase from the Tokyo Electric Power Company, which owns the nuclear-power plant in Fukushima.
Cesium-137 has a half-life of 30 years and exists in tiny amounts in soil and water. According to the U.S. Environmental Protection Agency, cesium-137 is produced when uranium and plutonium undergo fission and absorb neutrons in the creation of nuclear power.
"Exposure to waste materials, from contaminated sites, or from nuclear accidents can result in cancer risks much higher than typical environmental exposures," the EPA states on its website. "If exposures are very high, serious burns, and even death, can result. Instances of such exposure are very rare. One example of a high-exposure situation would be the mishandling a strong industrial cesium-137 source."
Levels of cesium-134, which has a half-life of just over two years, also shot up over the same period. It went from from zero MBq per kilometre on March 10 to 88.6 MBq per kilometre between March 15 and March 16, according to the Fukushima Diary.
In November, it reported that cesium-134 and cesium-137 releases from Fukushima were already at 95 percent of what was discharged from the Chernobyl nuclear reactor when it exploded in Ukraine in 1986.
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A square kilometer is a million square meters. So 128 MBq per square kilometer is 128 Bq per square meter, right?
One Becquerel (Bq) is a tiny amount of radioactivity. You are walking around right now with about 8000 Bq in your body from naturally occurring Potassium-40 and Carbon-14.
We can convert Cs-137 and Cs-134 activity on the ground into lifetime dose in Sieverts by looking at slide 24 of this presentation:
http://www.ans.org/misc/FukushimaSpecialSession-Caracappa.pdf
The conversion factor is 160 milliSieverts (mSv) per MBq per square meter, not per square kilometer. So: 160 * 128 / 1,000,000 = 0.02 mSv. Normal background in North America is around 2.4 mSv/year.
So this guy is getting all excited about a *lifetime* dose which is about 1% of your *annual* background dose.
With respect to the Chernobyl comparison, he's just flat wrong. The Chernobyl release was easily more than 100x greater (slide 25).
Almost a year ago, I gave a talk at my kids' elementary school in the wake of Fukushima entitled "A Rational Environmentalist's Guide to Nuclear Power". A greatly expanded version is available here:
http://www.scribd.com/doc/54904454
When you say "zero MBq/km2", that's incorrect. The actual MEXT table says "ND", for "not detectable". In other words, the readings cited are just barely above minimum detection limits. And modern radiation detectors are incredibly sensitive devices. There are very few other technologies capable of counting individual atoms.
its idiots like you that make everything sound so safe.
radiation is safe everyone because DiogenesNJ says so.
no one will get hurt no one will die at all just ignore the npp it wont harm you. idiot
Perhaps it's idiots like you with a clearly limited scientific knowledge who make the other idiots even more ignorant. Idiot.
well, the measurements show, that "seismic shaking" – or whatever was the primary cause for the latest rise/peak – "still" leads to increased airborne releases... which is a sign for a metastable cooling/fuel arrangement situation at the cores and/or in the SFP's. Which is not a big surprise, regarding the far-from-stable reactor/SFP rescuing situation on site.
You're correct, some of the Cs-137 and Cs-134 in the soil can be re-suspended in the air. Caracappa's dose estimates account for that, and for some level of ingestion in the food chain (slides 14-20). It is entirely possible that the readings of 128 Mbq/km2 could be from aftershocks. But that is simply stirring up Cs-137 in dust, and has nothing to do with any "metastable cooling/fuel arrangement", which is (without meaning offense) nonsense.
My point is that even the highest reading cited here represents an extremely low lifetime dose. Comparing this amount of radioactivity with the EPA's warning about a "high intensity industrial Cs-137 source", as the article does, is like comparing a Diet Coke to a tank car of hydrofluoric acid.
There is no question that significant radiation exposure carries risk. Several of the workers had significant exposures. About 30 workers had doses at or above 100 mSv in a short time as of the end of April 2011. The "Fukushima 50" were brave men and deserve our respect -- all the more so because they knew exactly what their risk was.
But the general population has not suffered significant exposure, and it is unfair to people already traumatized by the real catastrophe of the tsunami to frighten them with misinformation about their actual level of radiation risk.
Where possible, get your information from certified radiation safety professionals instead of activist websites. The Health Physics Society ( http://www.hps.org ) is the body responsible for radiation safety in medicine, among other things. Health physics is a medical specialty requiring board certification. Every hospital has health physicists on staff, monitoring all use of ioniziing radiation, from X-rays to cancer treatment. I recommend taking a look at the HPS website's coverage of Fukushima. (Yes, you too, racerfuku, assuming you can read the big words.)
"But that is simply stirring up Cs-137 in dust, and has nothing to do with any "metastable cooling/fuel arrangement", which is (without meaning offense) nonsense. "
Can you give a link or a reference with a model, that shows, how dust gets re-aired ("stirring up") by seismic aftershocks (~≥4m) in big-enough amounts to explain the 128 Mbq/km²? It doesn't fit in my perception of reality, that such aftershocks (with their relatively low vertical amplitude) can build up such "clouds of dust"... never heard about that from other earthquakes below 7m neither, sorry. (No offense. -.-)
And THX in advance. :)
Flo
Here you go on mechanisms of re-suspension (published a year before Fukushima). I don't have a citation on aftershocks; it was just a logical supposition. Earthquakes shake things, which might dislodge Cs-137 particles which had settled on buildings and cause them to float to the ground.
These monitors are generally in settled areas, with surrounding buildings. But it turns out that the most likely mode of resuspension is just wind over dry soil, aided by industrial (i.e. recovery reconstruction) or agricultural activity:
http://www.niaes.affrc.go.jp/sinfo/publish/bulletin/niaes27-2.pdf
Also: https://na22.nnsa.doe.gov/prod/researchreview/2011/PAPERS/04-15.PDF
Note the line on page 6 (which is page 720 of the journal):
"... re-suspension causes spurious increases of mainly Cs-137 levels."
And this one is rather old but might have some interesting information. It's subjection is re-suspension of Cs-137 from Chernobyl:
http://www.scribd.com/doc/61307334/Re-Suspension-and-Deposition-of-Radio...
I'll take a look in it, and reevaluate, when the next distinct spike co-occurs with a larger quake in the area. :)
Greetings,
Flo