Atmospheric tritium and carbon-14 monitoring system

Atmospheric monitoring of gaseous 3H and 14C in and around nuclear facilities is of interest because these nuclides may contribute to the environmental dose commitment. A sampling system has been designed to measure 3H and 14C at concentrations on the order of 10-6 pCi/cm3 of air. This system, which may run unattended for periods up to two weeks at a controlled flow of 80 cm3/min is small, portable, and only requires electrical power. The air sample is pulled through silica gel and molecular sieve adsorbent columns at a rate determined by small orifices. Part of the air stream passes through a heated catalytic oxidizer prior to the adsorbent columns. The adsorbent columns are returned to the laboratory for analysis. Tritium is counted as HTO, and 14C as CO2, by liquid scintillation techniques. The analysis reveals the concentration of these radionuclides originally present as HTO and CO2, as well as the concentration in other forms which are oxidizable to these species