Thomas Beck
Due to the change in the policy of PTB regarding the traceability of radon quantities, it was necessary for BfS to set up a facility for the realization and transmission of the measurement quantity radon activity concentration. The basic component of the facility is a radon-tight chamber with a certified volume traced back to a standard volume at PTB. The facility is equipped with instruments for monitoring temperature and air pressure. This basic setup is extended by an additional volume as well as by devices for monitoring online the actual radon activity concentration and for extraction of a defined quantity of radon-loaded air.
The facility can be used flexibly to fulfill different measurement tasks, and to improve the traceability of the measurement quantity. First results show that the measurement uncertainties achieved correspond excellently to the uncertainties of the former calibrations carried out by PTB. In extension to PTB which provided calibrations only in the range above 1000 Bq/m³, the facility of BfS can calibrate instruments even down to 100 Bq/m³.
The purpose of the facility established at BfS is not only to ensure and improve the traceability for the BfS radon calibration laboratory itself, but also to transmit the quantity radon activity concentration to external interests. With this facility, BfS contributes towards international harmonization and comparability of radon measurements.
