Early Kr-85 measurements

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

Historical FYI...

Some of you may or may not know that a huge amount of Radiochemical
and Health Physics work done during and shortly after WWII was
classified and never published.  Some of this stuff has been
declassified, and is finding its way into print (although because
of its age, journals are not anxious to publish it).

In the July 1997 Proceedings of The National Academy of Science,
work by Anthony Turkevich et. al. on atmospheric Kr-85 experiments
from 1949-1950 were published.  Tony was the P.I. on the first
chemical analysis of the moon with alpha backscattering on
the Surveyor lunar landers.  His colleague Tom Economou was one
of the investigators on the recent Mars Pathfinder APXS
instrument (alpha, proton, xray spectrometer).

In the early Kr-85 work Turkevich and co-workers demonstrated that
air sample from pre-war years had less than about 6 dpm of Kr-85
per STP liter of Kr.  By 1949-50 it had risen to the 100-200 dpm
per STP liter level, mostly attributable to releases from
Hanford.  The sampling sites were in the Northeastern United States.
Fluctuations in the specific activity demonstrated that it was
still in a plume as opposed to being well mixed vertically and horozontally
over this distance scale.  They also found that mixing times
between Northern and Southern hemispheres was long compared to the
production rate of the Kr-85.

Today Kr-85 is up to more than 10,000 dpm per STP liter.  According to
the publication the larest source of atmospheric Kr-85 is a fuel
reprocessing plant in France.

However, before anyone gets upset at this level of activity,
the health physics consequences of this activity is miniscule.
Since Krypton is about 1 ppm of the atmosphere, the air we breath
has of the order of .01 dpm per liter of Kr-85.

Cheers, and I for one am looking forward to seeing more of this
early work published.

Dale