Measurement of natural levels of tritium in water.

This paper describes equipment and techniques used in the tritium laboratory at the Australian Atomic Energy Commission Research Establishment for the determination of low level activities of tritium in water samples. Samples are enriched by electrolysis in sixteen glass cells connected in series. An enrichment of about 25 times and an enrichment factor of about 0.85 are obtained. A calibrated ampere-hour meter in series with a precision shunt measures the weight of water electrolysed and a preset counter is used to shut off the current when 20 g of electrolyte remains in each cell. After distillation the enriched samples are counted in Teflon vials using emulsion liquid scintillation techniques. The accuracy of measurements is discussed and applied to routine measurements. The overall standard deviation for samples having an activity greater than 5 'tritium units' is less than 10%