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RE: Decay on site question
Hi Eileen,
35S and 33P have maximum beta energies of 168 and 249 KeV respectively, and
those emissions would be two weak to punch their way out of a sturdy plastic
bag, sharps container, jug, etc. So I wouldn't worry about any additional
shielding in your waste room for those two radioisotopes.
32P with it's 1710 KeV max beta energy is a whole other matter, so that
radioisotope should be collected and packaged separately by the lab staff.
You will want to shield 32P - although it doesnt take much - about 8 mm of
plastic or 3.4 mm glass to totally absorb all the betas. I always look for
the cheapest solution - Have you considered cruising your local Walmart -
seems to me some of the those Rubbermaid storage containers (the larger
ones have hinged lids) or giant-size plastic picnic coolers might fit the
bill. I've seen some quite large and very sturdy (heavy plastic) ones that
were intended for storing garden equipment that would probably meet your
needs quite well - and they are pretty cheap to boot, especially on Sale
Days!!. These could be stacked or placed on their ends (to open like a
fridge).
I manage all our radiopharmacy, nuclear medicine and biomedical research lab
radwaste on a decay in storage basis at our two university teaching
hospitals. Beyond my salary which they have to pay anyway(peanuts!!) and the
relatively modest one-time capital cost of building the special radwaste
storage rooms (usually in a corner of the basement) and equipping them with
new freezers, scavenged shelving and some simple plumbing, our hospitals
have never spent a nickel on radwaste disposal. Years ago I designed a
very heavy duty plastic bag, clear so you can see the contents, but also
printed on one side with a yellow panel featuring magenta radiation trefoil
symbols, lines to enter info about radioisotope content, lab or origin,
date, activity or count rate. The ink used on the pre-printed panel is
alcohol soluble, so when there is no longer any appreciable radioactivity in
the bag (either calculated or detected, depending on the radioisotope), all
of the warning symbols and info are easily wiped off (takes about 2 seconds)
with a guaze swab soaked in 95% alcohol. Then the bag goes into the regular
hospital waste stream. I have rigorously trained all our lab staff to
remove or deface radiation warning symbols from anything they put INTO the
bags - so that when I eventually remove the external bag markings and
release the bags to regular garbage, there are no visible radiation warning
symbols left to needlessly frighten subsequent waste handlers at the
hospital or municipal landfill site. If they forget and leave radiation
warning marks on stuff inside the bag, I return the bag to the offending
lab with an order to repackage the waste. Usually only happens once!
We have the bags custom manufactured in 10K lots and sell them to all our
users from the hospital warehouse. The plastic in the bags is so thick
(4-mil) we found that twist-ties or tape didn't work well, so instead we
use commonly available plastic cable bundling ties to be quite effective
and secure bag closure devices. Radioactive sharps, glassware, are captured
in standard hospital issue sharps containers labelled with rad warning tape.
Small dead "hot" critters or parts thereof are packaged in the
aforementioned radwaste bags and kept in my radwaste freezers.
I also work pretty closely with my permit holders and always suggest they
use relatively short-lived radioisotopes - since taking this approach, we
have significantly reduced the use of long -lived radioisotopes like C-14.
Hope this is helpful
Karin
********************************************
Karin Gordon RTR, RTNM, RTT
Radiation Safety Coordinator
Winnipeg Regional Health Authority
Health Sciences Centre
GC-214, 820 Sherbrook Street
Winnipeg, Manitoba
CANADA, R3A 1R9
phone (204) 787-2903
fax (204) 787-1313
e-mail kgordon@hsc.mb.ca
*******************************************
-----Original Message-----
From: Eileen de Feo [mailto:ESDEFEO@CLONTECH.COM]
Sent: Thursday, June 29, 2000 3:49 PM
To: Multiple recipients of list
Subject: Decay on site question
Hi,
we usually decay on-site our 32P, 33P and 35S. We are looking at upgrading
our decay facilities and would like to find something along the lines of a
"bank of lockers". Ideally we would be able to put waste with different
start dates into different cubbies and then be able to remove just the
one(s) that are ready for disposal and not be exposed to the ones that are
still decaying. We would prefer an off-the-shelf type set up, but any
suggestions are welcome. My email address is esdefeo@clontech.com
thanks very much for your time.
Sincerely,
Eileen
Eileen S. G. de Feo, Ph. D.
Quality Manager
CLONTECH Laboratories, Inc
1290 Terra Bella Ave.
Mountain View, California
esdefeo@clontech.com
1-650-424-8222 x4461
1800-662-2566 x 4461
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information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html