HPS Position Statement on Radiation Standards for Site Cleanup and Restoration

["Clement, Christopher" <clementc@aecl.ca>]

Radsafers:

I recently read with some interest the HPS Position Statement on
Radiation Standards for Site Cleanup and Restoration issued in May 1993.
In it, the HPS states that, "for unrestricted release of sites
containing radium 226, thorium 232 or radium 228, we recommend a soil
concentration limit of 5 pCi/g above the normal concentration in the
region to prevent excessive radon 222 or radon 220 concentrations in
indoor air"

Although I understand very clearly the concern about indoor radon
concentrations, and agree with the general approach of selecting a
numerical criterion, I do not have a good understanding of the basis for
picking 5 pCi/g.   I imagine that some of you out there were involved in
preparing this statement.  Perhaps you can help me out by describing the
basis for this particular value.

Similarly, averaging areas and depths were recommended for the criterion
of 5 pCi/g.  I definitely support this, as it is an important piece of
the puzzle which is often missing when trying to apply numerical
criteria to the real world.  The averaging areas and depths seem
reasonable, but is there more to justify the particular values which
were selected?

------------------------------------------------------------
Christopher H. Clement
Scientific Specialist / Radiation Protection Program Manager
Low-Level Radioactive Waste Management Office
Atomic Energy of Canada Limited
clementc@aecl.ca