Re: Cleanup standards

I seem to recall that folks in Goiania wanted their persons and their property to be certified as "cesium free". Now you and I know that's impossible, but I'd lay "a dime to a doughnut hole" (as we say here in the south) that the limit, as established not by us technical folks, but by "elected officials" and their appointees, is going to be a lot closer to "cesium free" than a level "where occupancy would be reasonably safe". Sure, a simple washing (or for that matter, the first good rain) will wash the bulk of the CsCl away ... well, actually, it won't wash it "away", it'll just move it to somewhere else. For those of us in cities with combined sewer overflows (CSO's), a lot of it may wind up in sewage treatment plants ... and wherever rainwater or washwater stands and evaporates, you can expect to find elevated concentrations. I'm sure our Russian colleagues can provide us with a lot of practical experience based on Chernobyl. They presented several reports on this very topic at an EPA Post-Emergency conference in September 1998 in Washington, DC. I think I've got a copy around my office somewhere (teleworking today) ... the proceedings of this conference MAY be available electronically.

Jim_Hardeman@dnr.state.ga.us

>>> "Jerry Cohen" <jjcohen@PRODIGY.NET> 2/28/2003 12:00:19 >>>
The difficulty in cleaning up of Cs-137 contaminated areas depends entirely
on the standards applied to determine adequacy. For cleanup to the point
where occupancy would be reasonably safe, Bernie is correct in assuming it
would be relatively easy. BUT, if EPA standards were to apply [maximum
individual dose <15. mrem/a, as determined by a scenario that includes
compounding worst case exposure assumptions] cleanup would be nearly
impossible. For example, we are still paying megabucks for cleanup of
Cs-137 residual contamination at Bikini and other
Marshall Islands from bomb tests that occurred over 50 years ago.

----- Original Message -----
From: John Andrews <andrewsjp@chartertn.net>
To: BERNARD L COHEN <blc+@PITT.EDU>
Cc: internet RADSAFE <radsafe@list.vanderbilt.edu>
Sent: Thursday, February 27, 2003 5:34 PM
Subject: Re: Dirty bombs

> BERNARD L COHEN wrote:
>
> > Can someone explain why dispersed CsCl in a city is a long term
> >hazard? Isn't it highly soluble in water? If so, it should be easy to
hose
> >away, using radiation detectors to locate hot spots. The water with CsCl
> >would go into the sewer system. Even without hosing, rain should wash
away
> >most of it.
> >
> >Bernard L. Cohen
> >Physics Dept.
> >University of Pittsburgh
> >Pittsburgh, PA 15260
> >Tel: (412)624-9245
> >Fax: (412)624-9163
> >e-mail: blc@pitt.edu
> >
> >
> >
> I cleaned up an old spill of Cs-137 once. The material had been cleaned
> up years earlier, but residual material remained on some of the
> concrete. It had penetrated into the concrete up to one inch in
> discrete spots. This indicated to me that actual grains of the spilled
> source material remained on the concrete and the cesium was sorbed by
> whatever reaction into the concrete. There was low level general
> contamination just above backround in adjacent areas indicating
> migration from the hot spots. Effective cleaning included jackhammering
> or intense needle-gun decon of the spots and scabbling the general areas
> to 1/2 inch.
>
> I would expect the same from any Cs-137 spill.
>
> John Andrews
> Knoxville, Tennessee
>
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