Assessment of the uncertainties in the Radiological Protection Institute of Ireland (RPII) radon measurements service

The RPII radon (Rn) laboratory holds accreditation for the International Standard ISO/IEC 17025. A requirement of this standard is an estimate of the uncertainty of measurement. This work shows two approaches to estimate the uncertainty. The bottom–up approach involved identifying the components that were found to contribute to the uncertainty. Estimates were made for each of these components, which were combined to give a combined uncertainty of 13.5% at a Rn concentration of approximately 2500 Bq m−3 at the 68% confidence level. By applying a coverage factor of k = 2, the expanded uncertainty is ±27% at the 95% confidence level. The top–down approach used information previously gathered from intercomparison exercises to estimate the uncertainty. This investigation found an expanded uncertainty of ±22% at approximately 95% confidence level. This is good agreement for such independent estimates.