Re: Rn-222 progeny

["Dale E. Boyce" <dale@radpro.uchicago.edu>]

A few years ago we were successful in disposing a storage cabinet
that had been used to store a radium source.  It was in an equipment
attic and the Professor from whose lab it had been taken was
long since deceased.  We were unaware of its existence until the
building managers wanted to get rid of it.  Approximately three
years prior it had been disconnected from the exhaust duct and the
ventilation plugged.  Needless to say we had a mess.  Six thousand
pounds of concrete and about $13,000 later it was off our hands.

This cabinet used an electrostatic element to plate out the
radon progeny.  Unfortunatey the 100 volt battery failed after thirty
or so years.  In our cabinet this electrostatic plater was a small
unit in the lid of the lead shield inside the cabinet, so it would not
be the right design for you.  You might be successful with placing a grid
in the exhaust duct and applying a potential between wires in the grid.
A HEPA filter would probably do a better job if filter loading is not a
problem.

Dale Boyce
dale@radpro.uchicago.edu