Re: TMI air data

[Bob Flood <bflood@SLAC.Stanford.EDU>]

>ARAC informed me that a summary of their involvement in the TMI
>incident is available on line at ...

I didn't any met data, just model output. I'd still be interested in seeing
stability class and wind data.

A point of meteorology: the "bouncing" plume phenomenon is called looping,
and happens only under a situation where stability class A, most unstable,
is widespread and extends vertically high enough to enclose the entire
plume. The plume begins an upward release that is modified by localized up-
and downdrafts that cause the looping effect. The amplitude of the loops
increase until the plume strikes the ground. The cycle then begins again
with the ground strike location being the point of origin for a new plume.
So the concept of a plume exhibiting a "bounce" bahavior does have
credibility. However ...

(There's always a "however," isn't there) Stability class A happens 99+% of
the time only under strong open sunshine, and rarely extend more than 10
meters vertically. It can be seen in places like Florida in the summer, and
a looping plume from an oil-burning power plant will happen infrequently. I
will reserve final judgement until I can see actual met data for the TMI
accident, but I'd be willing to wager up to a quarter that widespread and
deep class A stability hasn't happened in Pennsylvania in March.

If the plume released during the night was released into an inversion, it
would have risen to its effective stack height and stayed there under light
wind conditions until daylight. The surface heating in the morning could
have caused limited layer mixing, where heating allows the elevated plume to
mix downward while the remainder of the inversion prevents mixing upward.
This would permit a sudden "landing" of the plume at one location one time
and only for a short period - renewed dispersion would have begun
immediately. This is a much more likely scenario for the place and time of
year.
============================
Bob Flood
Dosimetry Group Leader
Stanford Linear Accelerator Center
bflood@slac.stanford.edu

-----Original Message-----
From: Kim Merritt <merritt9@llnl.gov>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Date: Wednesday, May 10, 2000 2:57 PM
Subject: TMI air data


><http://www.llnl.gov/tid/lof/documents/pdf/185726.pdf>.  I have not
>had a chance to read through it yet but it may answer some of the
>questions posed.  Curiously, the ARAC center started operations only
>2 weeks prior to TMI incident.  For those of you who have not heard
>of ARAC but have some involvement in emergency planning or response I
>recommend making yourself familiar with them.  You can see more about
>them at their web site at
><http://www-ep.es.llnl.gov/www-ep/atm/ARAC/arac.html>.   Hope this
>helps some.
>
>
>*********************************************
>*Kim Merritt, RRPT     *
>*Lawrence Livermore National Laboratory     *
>*Physics Directorate Safety Support Officer *
>*phone: (925)423-9668 fax: (925)422-7160    *
>*e-mail: merritt9@llnl.gov     *
>*     *
>*"If the only tool you own is a hammer,     *
>* every problem begins to resemble a nail." *
>* Abraham Maslow     *
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