DECAY-IN-STORAGE

["Michael P. Grissom" <MIKEG%SLACVM.bitnet@vmd.cso.uiuc.edu>]

Forwarded-from: MIKEG

1.  A Decay-In-Storage Program for a medical license might be supported
(in part, without all the details):

    a.  Identification of the radionuclides allowed for DIS under the terms
of the license as requested and approved (half-lives less than 60 days,
possibly allowing I-125).  In general, most licenses require holding for
10 half-lives, some licenses allowed 5 half-lives for certain radionuclides.
(Please note that this is based on PAST experience and not necessarily the
current regulatory environment.)

    b.  Typical production rate at a 250 bed hospital with a Clinical
Investigation Program (P-32 and I-125 eligible), as much as a full barrel
(55 gal) containing very short half-lived materials and general class A
wastes (Tc-99m, absorbant pads, alcohol swabs) and possibly one or two
small sharps containers.  Longer lived radionuclides could go into the
same container as long as the bag with all associated waste is properly
identified for removal at a latter time (Tl-201, Ga-67, etc.).

    c.  For I-125 from diagnostic procedures, we maintained separate
storage facilities since we ran a RIA based drug screening laboratory
at Oak Knoll.  We produced about 10 x 55 gal drums per calendar quarter
of I-125 vials and associated waste doing about 10,000 RIA tests per month.
This required a separate storage building with a floor space sufficient
to store a set of 30 barrels and necessary barrel handling equipment
(with another row of 30 barrels--double stacked).  We halved the barrel
production rate by low-level waste compacting, but that made processing
the barrels during the end of DIS clearance phase VERY difficult (vials
crushed together almost into a solid mass!).  Eventually we hired a
contractor maintaining a DIS approved facility in Illinois to deal with
this, but a lower level of production would be more manageable
without resort to compacting.

    d.  For the nuclear medicine and clinical investigations material,
an identified member of the radiation safety organization (we used a
licensed radiopharmacist to keep control of the process for nuclear
medicine and a lead biomedical technician for the CI material) logged
the bags entered into the barrels and periodically removed end of DIS
material for confirmatory clearance surveys and assignment to appropriate
waste streams as non-rad material.  The approved license conditions for
conducting release surveys had to be met, of course.  The space required
in the nuclear pharmacy was enough for about 4 barrels (55-gal) with 2
("fresh" material) behind a shield and two in general area of radiopharmacy
(older material so decayed that counting rates on gamma spectrometry
equipment were not impacted--an occasional problem could be found with
sharps containers with incompletely delivered or badly assessed post-dose
materials in them since they are normal stored on bench tops--a few lead
bricks came in handy).  Volumes of waste produced vary widely from
institution to institution, you need to know what your customers do or
will do to estimate your license quantities, etc.

    e.  In sum, you have to specify the radionuclides (or a range of
potential radionuclides if research in a University general science
research program), terms of DIS, criteria for end of DIS release,
adequate storage space (in some cases with shielding--especially waste
from I-131 patients which I didn't mention above), maybe separate
warehouse floor space, handling equipment, and administrative controls
(who is responsible for what)--this latter is the key for regulators,
i.e., adequate tracking of radwaste well documented by logs/sign-offs/
tear tag labels, etc.

2.  This is, of course, just the tip of the iceberg.  But there are
good reasons (economic and for conservation of limited LLRW disposal
space--if you can get any under the developing radwaste compact
situation) for doing DIS for many (if not most) facilities handling
shorter lived radionuclides.


                         - - - - Forwarded Text - - - -


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From: Lynn Dobbs <D020219@UNIVSCVM.CSD.SCAROLINA.EDU>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Subject:      DECAY-IN-STORAGE
X-Listserver-Version: 6.0 -- UNIX ListServer by Anastasios Kotsikonas
X-Comment:  Radiation Safety Distribution List

We are in the process of writing a proposal to our administration for
establishing a decay-in-storage program for our radioactive waste.  If
any other institution has recently started such a program, we are interested
 in any information you may care to share.  What kind of building, estimating
 square footage needed, equipment needs, segregating waste in the laboratories,
 what to store the waste in while in decay....  We know a few things that
must be looked at, but where to start is the problem.  Thanks in advance for
any information provided.

LYNN B. DOBBS
RADIATION SAFETY OFFICE
UNIVERSITY OF SOUTH CAROLINA
D020219@UNIVSCVM
STANDARD DISCLAIMER---THESE OPINIONS ARE NOT
NECESSARILY THE OPINIONS OF THIS INSTITUTION.