Posted on 04/30/2011 9:10:22 AM PDT by ransomnote
The operator of the stricken Fukushima nuclear plant in Japan's northeast said today that two of its workers at the crisis-hit facility had been exposed to radiation levels close to legal yearly limit of 250 millisieverts.
The operator, Tokyo Electric Power Power Company (TEPCO), found that the amount of internal and external radiation that two of its employees had been exposed to exceeded 200 millisieverts. The reading for one of the men reached 240.8 millisieverts, while another received 226.6 millisieverts of radiation exposure.
The power company had last month measured the internal radiation exposure of the workers whose external exposure exceeded 100 millisieverts, national broadcaster NHK reported.
The Health Ministry recently raised the legal radiation limit that workers can be exposed to in an emergency from 100 to 250 millisieverts.
On March 24, the two workers, without wearing proper protective gear, stood in highly radioactive water while working in the basement of the Number 3 reactor building.
TEPCO said it took about one month to measure their internal exposure levels.
It said its workers are transferred out of the Fukushima plant once their external exposure reaches 150 millisieverts, and that 8 workers in total have been relocated.
(Excerpt) Read more at smartinvestor.in ...
I have never trusted Tepco or anything they say.
Yeah. At first I idealized the situation “We got the best in the world dealing with it” and then TEPCO’s history started coming to light. And then TEPCO was scolded for failing to give some workers dosimeters. And then I read this article: http://japanfocus.org/-Makiko-Segawa/3516
Near the bottom of the page - the way that TEPCO controls media.
I can’t how the workers must feel about this...all of this. Tsunami, deathtoll, earthquake, radiation...too much for a person to deal with in short order.
Let's just say it involves jars and is not very pleasant. The jars' contents are then analyzed by gamma spectroscopy primarily, although I would expect they would also be doing alpha monitoring as well since reactor fuel could possibly have been taken internally.
The reason it takes so long is because of the biological half life, i.e. the time it takes the body to eliminate half of the radioactive elements through normal bodily functions.
Quite a contrast to 134 Chernobyl workers in the first few hours recieving 800m/Sv-16000m/sv.
Thank you for the insight. I completely forgot about the biological half life. I thought ‘uptake’ isotopes like Strongtium would not be eliminated from the body well. Strontium to the bones - cesium to the muscle etc. So is there a rule of thumb how much the body eliminates - ie is it really half or in general half? Thanks in advance.
Wow!...wow....I knew exposure had to be terrible but I never saw the numbers before. Somewhere I bookmarked an article detailing first person accounts from that time period. One was the wife of a fireman (sound like one of the 800-1600m/Sv guys you talked about. He was in a hospital you couldn’t get in unless you had a special badge - his wife bribed her way in to see him. They told her we was so contaminated that he was a ‘living reactor’ or ‘human reactor’. She would learn later that as this hospital received highly irradiated rescue workers - doctors and nurses who worked at the hospital were abruptly dying and being replaced. It’s likely most of those 134 workers made their way to the ‘nearest’ hospital where her husband was and basically flooded the place with contamination. I can’t imagine it...
If that is all of the over exposure, so far, it is a testament to the overall plant design. We just lost 300 or so people in one weather event, and Japan lost something north of 20K in the earthquake/tsunami, that had nothing to do with nuclear power.
Agree that plant design held up fairly well, I attribute these radiation exposures to human decision making errors.
Agree that tornado, tsunami, and earthquake fatalities are unrelated to nuclear power.
“Internal” exposure is exposure from radioactives inhaled/ingested/absorbed through the skin.
Measuring internal dose is done by a number of methods, including measuring the radioactivity of waste matter, blood, perspiration, etc. You can also use a whole-body counter to measure gamma ray activity inside the body.
Why did it take a month? They may have been too busy dealing with the reactors to stop and hang around inside a whole-body counter. Or, perhaps they wanted to evaluate how long the radioactives were hanging around in the body, the better to get an integrated dose.
The biological half life has nothing to do with radioactivity, and is specific to the element.
You can get a good idea how an element will behave in the body by looking at a periodic chart and finding element in the same period. For instance cesium is in the same period as potassium and sodium so it will behave similarly. Likewise, strontium is in the same period as calcium and iodine is in the same period as chlorine.
Every healthy body eliminates these elements pretty much at the same rate, so the biological half life is close for most people.
I mention iodine and cesium specifically because I-131, Cs-134, and Cs-137 were found in the environment outside of the reactor plants.
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