Monitoring tritium in air containing other beta-emitters using ion chambers

A flow-through ionization chamber instrument is described which is capable of measuring tritium in air containing high concentrations of other beta emitters. The instrument employs a separate concentric chamber with a thin common wall opaque only to tritium betas. Currents produced in the two chambers are subtracted leaving only the current due to tritium. With a 1.6-l sampling chamber and an 18-s time constant, tritium concentrations of 10-6 μCi/ml to 10-4 μCi/ml are measured with 2 sigma confidence in background beta concentrations of 4 x 10-5 μCi/ml to 0.4 muCi/ml, respectively. (auth)