Comparison of radium-228 determination in water among Australian laboratories

The National Health and Medical Research Council and Natural Resource Management Ministerial Council of Australia developed the current Australian Drinking Water Guidelines which recommend an annual radiation dose value of 1 mSv year^-1. One of the potential major contributors to the radiation dose from drinking water is radium-228, a naturally occurring radionuclide arising from the thorium decay series. Various methods of analysing for radium-228 in water have been established and adapted by analytical radiochemistry laboratories. Seven laboratories in Australia participated in analysing radium-228 spiked water samples with activity concentrations ranging from 6 mBq L^-1 to 20 Bq L^-1. The aim of the exercise was to compare and evaluate radium-228 results reported by the participating laboratories, the methods used and the detection limits. This paper presents the outcome of the exercise.