FAST SURVEY FOR KEY NUCLIDES AND GROUP PARAMETERS IN DRINKING WATER

ABSTRACT. A rapid procedure is presented for determining radioactive key nuclides and group parameters in drinking water using α/β discriminating liquid scintillation (LS) spectrometry for final counting. The nuclides measured are 226Ra, 228Ra, 224Ra, 222Rn, and 210Pb. Key parameters include short-, medium-, and long-lived gross α/β activity concentrations. Sample preparation procedures include filtration through selective Rad Disks ™ (3M™), followed by various elution steps, α/β discriminating LS spectrometry, and also evaporation or freeze-drying and cocktail extraction. The whole procedure is simple, rapid, and available on site, but sensitive enough to meet the regulations concerning natural radionuclides in drinking water. If a 222Rn ingrowth period of 1 to 2 weeks can be accepted, a lower limit of detection of down to 0.5 mBq/L for 226Ra may be reached. We applied the overall procedure for water samples of various origins and salinity. Results are discussed and compared with those obtained by other methodologies or reference values. It turned out, and this has been confirmed during the recent pilot intercomparisons, that selective Rad filter disks provide more reliable and faster results not only for 226Ra but also for other nuclides, compared to most other methods that have been applied by the partici-pating approved laboratories