prEN ISO 13169

Scope

This document specifies a method to measure uranium isotopes in non-saline waters by extraction and liquid scintillation counting. This method covers the measurement of soluble uranium isotopes in water in activity concentrations between approximately 2·10−3 Bq·kg-1 and 10 Bq·kg-1 when analysing a 1 l test sample volume with a 60 000 s counting time with a LSC instrument with α/β discrimination function. The ratio 234U/238U can also be determined. This method has not been tested for the measurement of other uranium isotopes. The method is applicable to test samples of non-saline waters after proper sampling, handling, and preparation. The detection limit depends on the sample volume, the instrument used, the background count rate, the detection efficiency, the counting time, and the chemical yield. The limit of detection of the method described in this document, using currently available liquid scintillation apparatus, is approximately 0,03 Bq·l-1, which is lower than the WHO criteria for safe consumption of drinking water (10 Bq·l-1 for 238U and 1 Bq·l-1 for 234U).[4] This value can typically be achieved with a counting time of 30 000 s for a test sample volume of 1 l. The method described in this document is also applicable in the event of an emergency situation.