Re: S35 DIS Surveys

["Wesley M. Dunn" <WDUNN@brc1.tdh.texas.gov>]

There are several posible answers to the question.  However, the
first one revolves around identification.  By instituting a top-notch
inventory program (which is NOT merely recording where you think
everything is), you can have a very high degree of certainty of what
is in the waste.

Is S-35 the only possible isotope present?  If so, you know you only
have to worry about the 87 day halflife.  The main concern is whether
the S-35 could have been mixed with long lived, low energy isotopes
(e.g., H-3, C-14).

Do you know the activity (reasonably well)?  If so, you can calc it
down to very low (e.g., < 0.1 uCi) so you know there is little chance
of detectable amounts available.

How is it going to finally be disposed of?  and How are you going
to take care of the labels?  If you can incinerate, it cleans up a
lot of problems.  (1) it defaces the labels; (2) you only have to
meet the emission concentrations.  However, you still have to worry
about the ash (which can be a Hazardous waste, regardless of
radioisotopes).

Also, if you are in Texas, you can apply for the "300 day half-life
rule", which can permit disposal of short lived wastes into
Type I landfills.

I would suggest reviewing your inventory program to see how certain
you are of your waste stream.  Decay it back to very low activities
(always greater than 10 half-lives).  Set up a rig that allows you to
scan the waste for labels and other baddies (biohazards, lead, vials
labeled Pu-238, etc...) and survey for "unexpected unknowns".
Surveying with an LEG probe and a pancake probe is very good at
picking up things that aren't supposed to be there.

If you are a simple lab with one isotope and no "odd balls", simplify
the process to meet your needs.  If everything is clean, document it
and dispose of it.

And make sure you have a documented procedure that states how
everything is done.  SOPs are very good documentation.

Wes