Interlaboratory comparison of gross alpha/beta activity of drinking water over a decade

Interlaboratory comparison exercises for determining the gross alpha and beta activity concentrations in drinking water, organized by the National Institute for Radiological Protection (NIRP), China CDC, have been carried out since 2012. The purpose of this study is to assess the accuracy and precision of gross alpha and beta analyses of low-level radioactivity concentrations. Natural water samples were used for the comparison, and the performance of the participating laboratories was evaluated with respect to the reference values using the Z-score performance indicator. The comparison data from 2012 to 2022 were analyzed, where the percentage of laboratories with acceptable results was 80-92%, and the dispersion of the measurement results across laboratories became smaller over time. The results demonstrate that these exercises can help laboratories to resolve issues in gross α/β analysis and improve the consistency of the measurement results.