Intercomparison of Rn-222 determination from groundwater.

An intercomparison exercise on Rn-222 determination in groundwater was organized between eight Nordic laboratories. The individual laboratory results were in most cases within 20% of the median value and within reported uncertainties. Considering the particular difficulties in preparing, transporting and analyzing Rn-222, being a gaseous radionuclide, the results indicate a high analytical capability among the Nordic laboratories. In order to maintain a high analytical quality, similar intercomparisons will also be needed in the future.