This standard applies to all types of water. The described method determines beta particles with an energy > 60 keV. The method is therefore unsuitable for the determination of the beta activity concentration in water containing relatively high concentrations of radionuclides with low maximum beta energy, such as 3H, UC and 36S. 3H will not be detected at all. For the determination of 3H, see NEN 6420. The lowest measurable concentration depends on the residue content of the water sample, the radionuclides present and the counting time. With a residue content of 0.5 kg/m3, a counting specimen with a diameter of 50 mm, a zero effect of 0.5 counting pulse/s, a counting efficiency of 25% and a counting time of 1800 s, 0.5 kBq/m3 can be are determined with a standard deviation of 50%. It is emphasized that this determination method involves a definition of total beta activity concentration. The results should therefore also explicitly refer to this standard.
NEN 6421-1987 history
1987NEN 6421-1987 Water- Determination of the gross-bèta-activity concentration and rest-bèta-activity concentration of non-volatile compounds