Evaluation of a radon-in-water pilot-proficiency test

A pilot proficiency test (PT) on measurements of the massic activity of 222Rn in drinking water was organised by JRC-Geel. Fourteen environmental radioactivity monitoring laboratories were invited to participate. The key aim of the study was to test, optimise and stream-line the complete process for conducting such a PT in order to perform a large scale Europe-wide PT in a robust manner. The process involved using all state-of-the art knowledge on sampling, transporting and measuring 222Rn in water. It was found that the majority of the participants’ results (92%) were within the ±15% reference range. The pilot-PT showed that the applied process was suitable and can be used for the large scale European PT planned for the third quarter of 2018. •A radon-in-water pilot-proficiency test was organised.•Our main aims were to optimise the complete process and secure radon tightness.•The process was proved to be suitable for large scale European proficiency test.•The performance of the participating laboratories was also evaluated.•92% of the measurement results were within the 15% reference range.