[ RadSafe ] Chernobyl Exclusion Zone Radioactive Longer Than Expected

[John R Johnson]

 Cary

The fact that Cs-137 is stored in trees and other vegetation is well known. 
What (I think) we will get from this data is beter information in the 
effect.

John
***************
John R Johnson, PhD
CEO, IDIAS, Inc.
4535 West 9th Ave
604-676-3556
Vancouver, B. C.
V6R 2E2, Canada
idias at interchange.ubc.ca



----- Original Message ----- 
From: "Cary Renquist" <cary.renquist at ezag.com>
To: <radsafe at radlab.nl>
Sent: Tuesday, December 15, 2009 3:10 PM
Subject: [ RadSafe ] Chernobyl Exclusion Zone Radioactive Longer Than 
Expected


> Sounds like Cesium is moving around...
>
> Could something like deciduous trees be serving as a cesium store and
> then releasing cesium via their leaves?
>
>
> Cary
> --
> Cary.renquist at ezag.com
>
>
> Chernobyl Exclusion Zone Radioactive Longer Than Expected | Wired
> Science | Wired.com
> Short URL:
> http://bit.ly/7xDfHE
>
>
> SAN FRANCISCO - Chernobyl, the worst nuclear disaster in the human
> history, created an accidental laboratory to study the impacts of
> radiation - and more than twenty years later, the site still holds
> surprises.
>
> Reinhabiting the large dead zone around the accident site may have to
> wait longer than expected. Radioactive cesium isn't disappearing from
> the environment as quickly as predicted, according to new research
> presented here Monday at the meeting of the American Geophysical Union.
> Cesium 137's half-life - the time it takes for half of a given amount of
> material to decay - is 30 years, but the amount of cesium in soil near
> Chernobyl isn't decreasing nearly that fast. And scientists don't know
> why.
>
> It stands to reason that at some point the Ukrainian government would
> like to be able to use that land again, but the scientists have
> calculated the cesium's ecological half-life - the time for half the
> cesium to disappear from the local environment - is between 180 and 320
> years.
>
> "Normally you'd say that every 30 years, it's half as bad as it was. But
> it's not," said Tim Jannick, nuclear scientist at Savannah River
> National Laboratory and a collaborator on the work. "It's going to be
> longer before they repopulate the area."
>
> In 1986, after the Chernobyl accident, a series of test sites was
> established along paths that scientists expected the fallout to take.
> Soil samples were taken at different depths to gauge how the radioactive
> isotopes of strontium, cesium and plutonium migrated in the ground.
> They've been taking these measurements for more than 20 years, providing
> a unique experiment in the long-term environmental repercussions of a
> near worst-case nuclear accident.
>
> In some ways, Chernobyl is easier to understand than DOE sites like
> Hanford, which have been contaminated by long-term processes. With
> Chernobyl, said Boris Faybishenko, a nuclear remediation expert at
> Lawrence Berkeley National Laboratory, we have a definite date at which
> the contamination began and a series of measurements carried out from
> that time to today.
>
> "I have been involved in Chernobyl studies for many years and this
> particular study could be of great importance to many [Department of
> Energy] researchers," said Faybishenko.
>
> The results of this study came as a surprise. Scientists expected the
> ecological half-lives of radioactive isotopes to be shorter than their
> physical half-life as natural dispersion helped reduce the amount of
> material in any given soil sample. For strontium, that idea has held up.
> But for cesium the the opposite appears to be true.
>
> The physical properties of cesium haven't changed, so scientists think
> there must be an environmental explanation. It could be that new cesium
> is blowing over the soil sites from closer to the Chernobyl site. Or
> perhaps cesium is migrating up through the soil from deeper in the
> ground. Jannik hopes more research will uncover the truth.
>
> "There are a lot of unknowns that are probably causing this phenomenon,"
> he said.
>
> Beyond the societal impacts of the study, the work also emphasizes the
> uncertainties associated with radioactive contamination. Thankfully,
> Chernobyl-scale accidents have been rare, but that also means there is a
> paucity of places to study how radioactive contamination really behaves
> in the wild.
>
> "The data from Chernobyl can be used for validating models," said
> Faybishenko. "This is the most value that we can gain from it."
>
>
> Citation: "Long-Term Dynamics of Radionuclides Vertical Migration in
> Soils of the Chernobyl Nuclear Power Plant Exclusion Zone" by Yu.A.
> Ivanov, V.A. Kashparov, S.E. Levchuk, Yu.V. Khomutinin, M.D. Bondarkov,
> A.M. Maximenko, E.B. Farfan, G.T. Jannik, and J.C. Marra. AGU 2009
> poster session.
>
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