Radon leakage as a source of additional uncertainty in simultaneous determination of ²²6Ra and ²²8Ra by gamma spectrometry--validation of analysis procedure.

A series of validation experiments was carried out to assess robustness, repeatability, and trueness of an analysis procedure for simultaneous determination of (226)Ra and (228)Ra in water samples. The study revealed instabilities in the radon holding capacity of the sample matrix (epoxy resin). The discovered effect is a new additional component in the uncertainty budget which should be considered when (226)Ra is measured via its progeny in similar sample matrices.