S-35 volatility

["George Rawls" <GEORGE@pliny.ehs.ufl.edu>]

Lost the original post, so....

Since it doesn't seem"unreasonable", as in the ALARA concept, we 
require that any opening of stock solution or thawing of labeled 
samples be done in a fume hood.

We also require that any incubation of labeled material at 37 degrees 
centigrade be performed with a trap.  Again, not unreasonable.  One 
of the main reasons for this is the tendency of S-35 to transfer to 
the interior surfaces of the incubator at levels far higher than our 
contamination limit of 100 dpm per 100 square centimeters, as proven 
by numerous surveys.  Also the condensate in the water pan can and 
will become contaminated above release limits.  This may routinely be 
emptied down the drain if investigators are not warned of the problem.

As an aside, contamination of surfaces and condensate does not occur 
every time when not trapped.  Why?  I don't know.  Perhaps others can 
help.

On another front.....Is your house vacuum system being contaminated 
with some of the "longer lived" radioisotopes such as H-3, C-14, I-
125?  Are surveys being performed when maintenance and/or repairs 
must be done on the system?  I have found several investigators using 
the house system on the bench over the years.

George Rawls
University of Florida
grawls@pliny.ehs.ufl.edu 

George Rawls
University of Florida
Health Physicist