Re: Medical waste held for decay -Clarification

["Andrew Karam" <akaram@safety.rochester.edu>]

After 10 half-lives we perform a survey on the waste.  We have not, have
not been asked to, and do not intend to do smear wipe surveys.  A G-M works
very well for P-32, actually, and we use it for S-35 as well.  With S-35 we
should be able to show that we can survey all of the waste reasonably well,
meaning we may have to smash the bag flat or open it up (although this is
not preferred).  We must verify that the waste has decayed to background
levels prior to disposal as non-radioactive.  Since there is a normal
fluctuation in background levels, we usually look for no consistent
increase in the average needle deflection or in the audible count rate.
Most of the time this is not a problem.  We also look at the amount of
activity in the bag - something that started off with several milliCuries
of P-32 won't be at background after 10 half lives, so we wait a little
longer.

I hope this helps.

Andy

Andrew Karam, MS, CHP				
RSO, University of Rochester			  
(716) 275-3781 (voice)						
(716) 256-0365 (fax)
akaram@safety.rochester.edu

"The mind is not a vessel to be filled  but a fire to be lighted" 
 Plutarch
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