Determination of natural radionuclides in drinking water; a tentative protocol

Routine analysis of drinking water is in general limited to artificial radionuclides although some naturally occurring radionuclides have radiotoxicities well comparable to those of the worst artificial ones. This unsatisfactory situation is mainly due to problems with traditional radiochemical preparation methods. They are very time consuming and the chemistry involved is too high a hurdle for many laboratories. A simplified protocol for the determination of natural radionuclides in drinking water has been setup and tested. It makes full use of the gamma-spectrometry's analyzing power and of state-of-the-art liquid scintillation alpha-spectrometry combined with extractive scintillators. It also includes the use of metal-adsorbing thin layers for direct alpha-spectrometry. The protocol does not offer record-low detection limits, but allows for a rapid check that no individual natural radionuclide present in the water will contribute more than 50 microS v to the annual dose.