TEPCO Press Release (Mar 25,2011)—The results of nuclide analyses of radioactive materials in…air…

[OKIsItJustMe]

http://www.tepco.co.jp/en/press/corp-com/release/11032505-e.html

Press Release (Mar 25,2011)
The results of nuclide analyses of radioactive materials in the air at the site of Fukushima Daiichi Nuclear Power Station(4th release)

On March 22nd 2011, as part of monitoring activity of the surrounding 
environment, we conducted nuclide analysis of radioactive materials 
contained in the air which were collected on March 20th and 21st 2011 
at the site of Fukushima Daiichi Nuclear Power Station, which was 
damaged by Tohoku-Chihou-Taiheiyo-Oki Earthquake. As a result, 
radioactive materials were detected as shown in the attachment. 
Therefore, we summarized the results and reported them to Nuclear and 
Industry Safety Agency as well as to the government of Fukushima 
Prefecture today. (previously announced)

On March 24th, 2011, we conducted nuclide analysis of radioactive 
materials contained in the air which were collected on March 24th, 
2011 at the site of Fukushima Daiichi Nuclear Power Station. As a 
result, radioactive materials were detected as shown in the 
attachment. Therefore, we summarized the results and reported them 
to Nuclear and Industry Safety Agency as well as to the government 
of Fukushima Prefecture today.

We will continue the sampling survey same as this one.



attachment1:The result of the nuclide analysis of radioactive materials in the
            air at the site of Fukushima Daiichi Nuclear Power Station(PDF 64.0KB)
attachment2:The result of the nuclide analysis of radioactive materials in the
            air at the site of Fukushima Daini Nuclear Power Station(PDF 54.0KB)
attachment3:Nuclide analysis of radioactive materials in the air Fukushima Daiichi
            uclear Power Station(Main Gate) (PDF 10.5KB)
attachment4:Nuclide analysis of radioactive materials in the air Fukushima Daini
            Nuclear Power Station(MP-1)(PDF 12.8KB)

[FBaggins]

1. Finally some hard data.

Going to take some time to work through though.

[Statistical]

2. Lots of data there but first thing I noticed is the rapid fall off in detected I-131.

That is the isotope which currently has highest concentration.

So that would be some good news.

[CJvR]

3. It has a halflife of...

...about 8 days. IIRC, so it shouldn't stick around. Provided you have taken you iodine pills it should be a managable problem.

[FBaggins]

4. True, but it appears to be falling faster than that.

My guess is it's because steam releases are less and less frequent... so a smaller and smaller component of the detected level is "fresh".

[Statistical]

6. That would be my assumption also.

A good sign because if the source declines significantly then the short half life will make the levels in Japan (Tokyo) fall off rapidly (since less "new" material is replacing the amount that decays).

[Statistical]

5. It fell off too quickly to be half-life alone.

Half life will take care of it but it fell off massively in just 24 hours which would indicate less is being emitted by the plant.

The levels fell by 69% in 24 hours. Half-life of 8 days means we would expect levels to fall by ~12% a day due to decay.