AW: [ RadSafe ] Chernobyl Exclusion Zone Radioactive Longer ThanExpected

Wed Dec 16 16:10:04 CST 2009

Dear Cary and RADSAFErs having participated in the discussion so far,

There seems to be a profound problem with you.....

The amount of Cs-137 deposited in the vicinity of the Chernobyl NPP is well
known. It decays with the half life of Cs-137. Furthermore the Cs-137 is
"rather" mobile. The mobility and the transfer of (not only) Cs-137 is the
topic of "radioecology"!!!! 

Having  been involved with some projects on Cs-137 in the environment after
the Chernobyl accident I can only comment on these "relevation" in that way:

The deposition of Cs-137 (and other radionuclides) is clearly defined and
has been measured. The deposition is one factor, many other ones are the
various factors which govern the adsorption on soil (clay), which itself is
governed by the presence of many other elements like K, Ca, Mg etc. This is
a very complicated puzzle, which is in contrary to commercial puzzles very
difficult to solve. 

The conclusion of the journal that the concentrations have increased are
therefore ridiculous - The Cs-137 has just been transferred to another
compartment of the ecosystem. Neglecting this fact only shows the non
existing scientific education of the distributors......

The decay formulas are still valid!

Thanks to Dan McCarn, who provided the most reasonable contribution to this
thread.   

Franz Schoenhofer, PhD
MinRat i.R.
Habicherg. 31/7
A-1160 Wien/Vienna
AUSTRIA

-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag
von Cary Renquist
Gesendet: Mittwoch, 16. Dezember 2009 00:11
An: radsafe at radlab.nl
Betreff: [ RadSafe ] Chernobyl Exclusion Zone Radioactive Longer
ThanExpected

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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