Abstract
The tritium survey meter consisting of gass flow counter with a large area thin window is developed. The large window (30mm×150mm) with extremely thin film made of alkyl benzene polymer (0.15mg/cm2) is installed at the counter. Argon including 10% methane was used for counting gas. A tritium check source was prepared to examine the characteristics of the survey meter. The source was made of a multi-layer film of [9, 10-3H] stearic acid on a metal plate. This film is thin enough to neglect the self-absorption of β-rays. Plateau characteristics and detection efficiency of the tritium survey meter are described. The sensitivity of this survey meter can be evaluated less than 1/20 of the maximum permissible surface contamination with tritium (10-3μCi/cm2) in Japan.
