Decay in storage for mixed waste

[james.tracy@nist.gov]

I'm looking for guidance on disposal of short half life mixed waste.   
Our license currently permits us to store the waste for 10 half lives,
survey with a meter, and dispose as clean if radiation levels are at
background.

The waste is currently in a 20 liter carboy with P-32 activity of 0.025
microcurie/ml (500 microcurie total).  It's in a DNA rinse solution which
is normally (when not radioactive) disposed of as chemically hazardous
waste (sent to an incinerator).  What I'd like to do is let the P-32 decay
and dispose of it as a chemical waste.  Sounds easy right.  Well here's my
problem.

1)  The carboy has a thick plastic wall and the solution is self
shielding.  Thus my survey method will not be very sensitive.

2)  If I analyze via liquid scintillation, I will see positive numbers. 
By calculation the activity will be 2E-5 microcurie per ml (0.5 microcurie
total).  Readily detected via liquid scintillation.  How hard do I have to
look?

There are release limits for sewer disposal and in liquid effluents but I
want to send the material as "non-radioactive" to a chemical waste
facility.  Is there anyone out there who disposes of the same or similar
material as "clean"?  If so, what procedures do you use?   Any advice or
suggestions on handling this problem would be appreciated.



James Tracy
NIST
Gaithersburg, MD 20899
301-975-5800
email: james.tracy@nist.gov

***The content of this message has not been reviewed or endorsed by my
employer*** -----------------------------------------------------------
james.tracy@nist.gov
-----------------------------------------------------------