Contamination Incident (anecdotes)

["Michael P. Grissom" <mikeg@SLAC.Stanford.EDU>]

It has been quite awhile, but I remember one in a hospital
environment that was of some interest.

We were using carbon-14 labeled nutrient bottles for doing
blood culturing with the Johnston Lab CO<sub>2 C-14
analyzer system.  A bottle was being taken from a venipuncture
area to microbiology when the aide dropped it on the floor.

(Fortunately, we were a poor facility and had tile rather
than carpeted hallways!)

Radiation safety responded and blocked off the area (also
fortunately a low traffic area).  Although only about 20
uCi of C-14 was involved, we had no difficulty locating hot
spots near the locations where fragments of the bottle had
been using a thin window, pancake, low-background GM detector.

We decontaminated the area using simple soap and water until
no meter responses were found above background.  We then swipe
surveyed the area (tiles make great grid references for the
survey map) and located the remaining "hot" spots (not very
really!) using beta swipes (swipes that are readily digestible
in liquid scintillation cocktail media while yielding low
quench factors).  We decontaminated those spots, which
were several points close to the original impact point of the
bottle (not too much jet spraying in this instance!), using
masking tape over the entire area, letting it adhere for a
few minutes, and then stripping it back up.

The follow-up survey detected nothing above background.  I
suspect for much of this we were dealing with nCi (a few
tens of Bq's) quantities.  So the laboratory survived without
significant health effects to members of the general population!

Long term changes included:  blood culture venipunctures were
done in the microbiology laboratory area or were specially
handled if taken at the walk-in clinical laboratory bioassay
area or taken on in-patient wards.  There were no more bottles
broken in hall-ways (for at least the next five years).  The 
autoclave in microbiology, of course, was another story...

Another observation...
-----------------------
Michael P. Grissom
mikeg@slac.stanford.edu
Phone:  (415) 926-2346
Fax:    (415) 926-3030