Re: Source of regs/policy on decay in storage

[Dave Derenzo <dave@uic.edu>]

In response to the original question asked by Stephen A. Doerfler, I 
believe the NRC used to put a DIS condition in most medical and research 
licenses, and the standard dividing line in the condition was 65 days.  In 
more recent years, the need to establish different values has increased, so 
at least here in Illinois, setting the long/short half-life dividing line 
is usually a matter of licensing.  I think that is also why the Suggested 
State Regs do not establish a value.  As you might expect, ours was 
originally  65 days when we had our NRC license (before Illinois became an 
agreement state), but since then we have increased it to 90 days so that we 
can categorize S-35 as short-lived.  I have seen others establish it at 120 
days.  Holding waste for a minimum of 900 (2.5 y) or 1200 days (3.3 y) is a 
LONG time for a medical or research facility, but if you have the storage 
space, it is worth it.  My guess is that NRC licensees can establish a 
limit other than 65 days if they ask and justify the practice.  I would be 
surprised to find any waste broker with a license permitting DIS of 
materials with such a long half-life as Co-57 since a minimum holding time 
of 7.4 years could be longer than the half-life of the broker itself.

With regard to your comment about holding them until they reach "exempt 
limits," the only sources that are exempt (by activity or concentration) 
are those that are manufactured and distributed by authority of a license 
that permits this.  Just because a source decays below a value established 
in the regulations for exempt sources or concentrations does not 
automatically qualify it as exempt.  Even if this were the case, the 
exemption extends only to receipt, possession, use, and transfer.  Disposal 
is not exempted, exempt sources still must be disposed of in an authorized 
manner.  At least that's how I understand it.  I am sure if my 
interpretation is not totally correct, someone else will jump in and help 
me out on this one.

Dave Derenzo

At 05:33 PM 04/18/2000 -0500, you wrote:
>Doug
>
>Neither Section D.1001 (Waste Disposal - General Requirements), nor Section
>G.30 (Decay-In-Storage), of the Suggested State Regulations for Control of
>Radiation, proposes a limit on the length of the half-life.  Section G.30a
>simply reads: "Before disposal in ordinary trash, a licensee shall hold
>radioactive material for decay-in-storage and is exempt from the waste
>disposal requirements of Part D of these regulations if the licensee: i.
>Holds radioactive material for decay a minimum of 10 half-lives."
>Contrastingly, 10 CFR 35.92(a) reads: "A licensee may hold byproduct
>material with a physical half-life of less than 65 days for
>decay-in-storage before disposal in ordinary trash . . ."
>
>Perhaps the Conference of Radiation Control Program Directors, in its
>wisdom, thought it best to leave it to the individual States to write a
>half-life limitations, should they so desire. I recommend that you consult
>your own regs.
>
>Many licensees do have line-items that permit nuclides with longer
>half-lives to be decayed-in-storage. However, the halflife of Co57 is 271
>days. I don't know of any regular licensee allowed that much time (2710 d =
>7.4 y). I suppose that one of the waste disposal companies might be able to
>D-I-S it for you. If they could it'd probably be a darn sight cheaper than
>disposing of it as radwaste (i.e., land burial).
>
>good luck
>cja
>
>
>At 04:28 PM 4/18/00 -0500, you wrote:
> >But Co-57 is State-regulated, and not NRC-regulated!
> >
> >Doug
> >
> >At 03:56 PM 4/18/00 -0500, you wrote:
> >>Stephen -
> >>
> >>Try 10CFR35.92.
> >>
> >>Steve
> >>
> >>At 03:09 PM 4/18/00 -0500, you wrote:
> >> >Does anyone know the source of the often used limit for decay and
> >> storage of
> >> >radioactive materials not exceeding a half life of 65 
> days?  Licensees are
> >> >having a difficult time in getting rid of old cobalt 57 dose calibrator
> >> >reference sources if the manufacturer will not take them back in
> >> exchange by
> >> >new sources.  One choice being used is to hold these sources for "storage
> >> >only" until they have reached exempt limits.  Any suggestions?
> >> >
> >> >
> >> >
> >> >Thanks in advance,
> >> >
> >> >Stephen A. Doerfler
>************************************************************************
>The RADSAFE Frequently Asked Questions list, archives and subscription
>information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html


Dave Derenzo, RSO (dave@uic.edu)
UIC Radiation Safety Section, M/C 932
Phones: Voice (312) 996-1177  Fax: (312) 996-8776

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html