Re: DECAY-IN-STORAGE

[Sue Dupre <DUPRE%PUCC.bitnet@vmd.cso.uiuc.edu>]

Lynn, I would be happy to discuss this with you at more length if you wish.
At the moment, I only have time for a cursory reply.  We are in the early
stages of decay-in-storage:  got our license amendment to store < 65 day
halflife isotopes in '92 and only recently have begun collecting segregated
wastes for the Decay-in-storage (DIS) facilities.  Certain procedures are
still evolving and I suspect the types of collection and storage containers
we use may change as time goes on.

What may be a little different here than other institutions is that the DIS
facilities are operated by the biological sciences department which generates
most (90%) of the rad waste on campus.  My office (the Occupational Health &
Safety Office) applies for license amendments, administers our licenses, does
certain surveys around the DIS facilites, audits the DIS operations, but we
don't handle the day-to-day operation of the DIS program or make all the deci-
sions about the operating procedures (though we are consulted).

There are two separate rooms for the DIS program: one for solid waste, one for
liquids.  Liquids are segregated in the lab by isotope and collected in Nalgene
containers of varying size (up to 2 liters, I think).  Acceptable isotopes have
half-lives of <90 days, are held for 10 half-lives, assayed, and if the conc'n
is less than the NRC's sewer release limits, then it goes into the sewers.  We
hold S-35 liquids in the DIS program because the NRC told us that sewer dispos-
al of liquids was permitted: it's not the same thing as holding solid waste
until it can be regarded as nonradioactive.  Solid wastes (isotopes of <65
days) are collected in the lab in 5-gallon pails and stored on shelves in the
same pails.  Not the most space-efficient thing to do but there's no concern
about space yet.  The dept plans to send out decayed solid waste for incinera-
tion as medical waste.  We believe we will reduce the volume of waste that will
need to go into interim storage for eventual disposal by at least 90% once we
get a license amendment to also do DIS for S-35 solid waste.

I'd be happy to discuss other details: facility size, reasons for the storage
containers we've chosen, survey details, etc., if you call me at (609)258-5294.
I'll be gone for the month of August so please call before or after, if it will
be helpful.

Best wishes,

Sue Dupre/Health Physicist/Princeton University