Atmospheric Moisture Sampling

Atmospheric moisture is collected by pulling air through a column of absorbent material (i.e., silica gel) to absorb water vapor. The water is then extracted from the absorbent material by heat distillation. The resulting water samples are then analyzed for tritium using liquid scintillation. Starting in 2002 the ESER program began an evaluation of Drierite (anhydrous calcium sulfate) as an absorbent material. Twenty-six atmospheric moisture samples were obtained during the second quarter of 2002 from Atomic City, Blackfoot CMS, Idaho Falls, and Rexburg CMS. However, seventeen of the samples, all collected using drierite, yielded invalid results at the ISU analytical laboratory. It was determined by ISU that the drierite contains a contaminant, yet unidentified, that is released during the extraction process and produces increasing counts during liquid scintillation analysis (Claver and Arndt 2003). For this reason, drierite will no longer be used as a collection medium

Eleven valid results were reported for the second quarter: five from Atomic City and six from Idaho Falls.  Each result, shown in Table C-4, was greater than its 2s uncertainty.  The results were all well below the DOE DCG for tritium in air of 1 ´ 10^-7 mCi/mL (3.7 ´ 10^-3 Bq/mL).  The maximum value was 9.3 ´ 10^-12 mCi/mL of air (3.4 ´ 10^-7 Bq/mL of air), collected at Idaho Falls on 5/31/02.