An intercomparison of 222Rn measurement systems in European laboratories

Primary standards of radon

“…Dry air has typically been used as a carrier gas, but other gases (e.g. N 2 ) have proved to be more suitable when the resulting gas mixture is used for internal gas counting [6,9,12] or for filling electrostatic collection cells [11,13]. Significant efforts have been made to develop gas-handling and gaspurification equipment for, respectively, measuring secondary 222 Rn sources and for removing water vapour and oxygen from the gas stream [6].…”

“…Various types of 222 Rn detectors have been successfully adopted as 222 Rn reference measurement systems to meet general requirements such as long-term stability, good response reproducibility and the ability to carry out direct measurements of 222 Rn gas sources. The main types are pulse ionization chambers [6,12], large volume multiwire ionization chambers [14] and electrostatic cells [11,13].…”

“…Two international comparisons on 222 Rn measurements have been carried out involving several NMIs, one in 1990 [28] and a second one in 1992 [12] in the frame of a EUROMET project.…”