Medical waste held for decay -Clarification

[Joelle Key <jkey@mail.state.tn.us>]

I appreciate everyones answers.... I would appreciate your indulgence
for a little more information.

I still have two parts of my question which I think are being answered but
I want to be really clear.

1)  In eference to the final surveylevel, I have heard "indistinguishable
from background,"  "twice background" and "essentially nothing left."  
That is really my question.  Is twice background generally accepted?  A
few answers have implied that this isn't enough.  But as we all know in
radiation there really isn't a zero.

2)  My second confusion has to do with isotope dependency.  What I
was trying to get at is in doing the final survey if you are looking at a beta
emitter like P-32 then the G-M survey is not appropriate. Someone
mentioned using an LSC to count for this isotope.  I haven't used liquid
scintillation outside of training courses, so my question here may be
really dumb.  The comment sounds as if any counts in LSC are
significant.  Does LSC not have a background rate?  Are we still looking
at twice background here or can we look for zero?  What do people
ususally do in this case?

Thanks again for all your answers.  I have included the original question
below if you missed it.

**********Original Question************
When a medical or research facility holds short-lived nuclides for 10
half-lives to decay, how much can still be left and still consider the
material "gone."  I would think that it should be completely gone to be
gone but isn't this impracticle?  Is this nuclide specific?  


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