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Re: Dirty bombs - radionuclide mobility
Dear colleagues,
I am not an expert on this issue, however I had to take decisions on Cesium
contamination. In Goiania, the source characteristics, together with the
meteorological conditions favored the dispersion of Cs-137 from the primary
contaminated sites. Heavy rains increased its dispersion from the broken
source source into the environment. In addition, the high temperatures
dried out the ground and strong winds caused resuspension and dispersion.
Contamination deposited on roofs was the major contributor to dose rate
indoors and for some houses the roof tiles had to be removed.
Soil profiles were determined, based on the radiation dose-rate value and
the Cs137 activity for each layer was measured. The soil profiles were
determined after removing all stones and grass...............
I gave some reference on this issue, very easy to obtain to those
interested, and I'll repeated it again:
*Rosenthal JJ, de Almeida CE, Mendonca AH. 1991. The radiological accident
in Goiania: The initial remedial actions. Health Phys 60(1):7-15.
*Amaral EC, Vianna ME, Godoy JM, et al. 1991. Distribution of Cs-137 soils
due to the Goiania accident and decisions for remedial action during the
recovery phase. Health Phys 60(1):91-98.
*Godoy JM, Guimaraes RJ. Pereira JC, et al. 1991. Cesium-137 in the Goiania
waterways during and after the radiological accident. Health Phys
60(1):99-103.
Jose Julio Rozental
joseroze@netvision.net.il
Israel
----- Original Message -----
From: "George J. Vargo" <vargo@physicist.net>
To: "'Van Dorp Frederik (vdf)'" <frits.vandorp@nagra.ch>; "'BERNARD L
COHEN'" <blc+@PITT.EDU>; "'Tom Hazlett'" <tomhaz@AOL.COM>
Cc: "'Tom Mohaupt'" <tom.mohaupt@WRIGHT.EDU>; "'internet RADSAFE'"
<radsafe@list.vanderbilt.edu>
Sent: Saturday, March 01, 2003 4:32 AM
Subject: RE: Dirty bombs - radionuclide mobility
I started this before Jim Dukelow's reply posted earlier today, but I
still think it adds something to the body of knowledge on the subject.
As I recall, the sorption of cesium depends somewhat on the soil type;
however, it is almost always tightly bound. As an example, Cs deposited
on surface soil test plots at Hanford (100F Area) showed virtually no
movement over 40 years, while Sr was observed to move (downward) at ~1
cm/year. Most of the Pu compounds in the Hanford processes also bound
very tightly to soil, making their recovery and cleanup a very difficult
problem - even microwave-assisted acid digestion was essentially
ineffective. Significant portions of the careers of several very
distinguished chemists were spent trying to find methods to recover Pu
that was chemically bound in soil.
As for Cs mobility in concrete, after ~25 years exposure in the K-East
fuel basin, an unpainted concrete structure having typical Cs-137
concentrations of 3-5 uCi/L, the contaminants migrated between 3-5 cm
below the surface. That was conformed by a combination of MCNP analyses
and confirmatory core samples. The mobility of the Cs in concrete
certainly depends on the porosity, surface roughness (all concrete is
not created equally), pH and a whole bunch of other variables. It's
been nearly 10 years since I worked on that project, but that's the data
as best I recall. The analogy to NaCl deposition for ice removal is
probably not an appropriate comparison
Any Cs that ends up in a sewage treatment system would almost certainly
be bound in sludge.
George J. Vargo, Ph.D., CHP
vargo@physicist.net
610-925-1954
610-925-5545 (fax)
-----Original Message-----
From: owner-radsafe@list.vanderbilt.edu
[mailto:owner-radsafe@list.vanderbilt.edu] On Behalf Of Van Dorp
Frederik (vdf)
Sent: Friday, February 28, 2003 10:39 AM
To: 'BERNARD L COHEN'; Tom Hazlett
Cc: Tom Mohaupt; internet RADSAFE
Subject: AW: Dirty bombs
Diffusion of cesium might be less of a problem than sorption of cesium.
Cesium does sorb on many materials much stronger and by different
mechanisms than sodium. Quite some research has been done in Europe on
decontamination of urban environments and results have been published,
in particular after Chernobyl.
Frits van Dorp
Nagra
Wettingen
Switzerland
e-mail: vandorp@nagra.ch
> -----Ursprüngliche Nachricht-----
> Von: BERNARD L COHEN [SMTP:blc+@PITT.EDU]
> Gesendet am: Freitag, 28. Februar 2003 15:30
> An: Tom Hazlett
> Cc: Tom Mohaupt; internet RADSAFE
> Betreff: Re: Dirty bombs
>
>
> On Thu, 27 Feb 2003, Tom Hazlett wrote:
>
> > My understanding is that Cs diffuses into concrete. That makes it
> > impossible to wash away.
>
> --Does cesium diffuse into concrete more rapidly than sodium? We
> spread enormous quantities of NaCl for de-icing purposes, and it seems
> to wash away rapidly, even without human effort such as hosing.
> Do you know a reference on Cs diffusing into concrete?
>
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