Isotope gas analysis of tritium-labelled water by means of an automatic apparatus

Abstract

A procedure and an automatic apparatus designed for the radioactivity measurement of tritium-labelled water in the gaseous phase are described. The method is based on the conversion of water to hydrogen, methane and carbon monoxide in a carbon-packed quartz reactor. The reaction products are swept by hydrogen carrier gas into a piston-type counter tube. Methane is fed to the radioactive gaseous mixture, and the radioactivity of the hydrogen-methane-carbon monoxide mixture is measured in the limited proportional region. The radioactivity values are correlated with the weight of the sample taken and the results are corrected for the ‘memory effect’ obtained in the measurement of inactive water samples. The standard deviation of the procedure, characteristic of its reproducibility, is lower than ±0.5% rel. at preset number of counts.