Interlaboratory comparison of passive radon measuring devices

Since 2003 the German Federal Office for Radiation Protection (BfS) regularly conducts interlaboratory comparisons of passive radon measurement devices using

• track-etch detectors (SSNTD) or
• electret ion chambers

in order to assure the quality of radon measurements. The measurement devices will be exposed in the calibration chambers of the German Federal Office for Radiation Protection. The BfS Radon Calibration Laboratory is accredited by the German accreditation body Deutsche Akkreditierungsstelle GmbH (DAkkS) for measuring the activity concentration of radon-222 in air and the potential alpha energy concentration of short-lived decay products.

Implementation

The participants submit their devices to BfS for testing. Submitted sets will be divided at random into a certain number of exposure groups and will be exposed to different radon-222 activity concentrations of up to 10 kilobecquerel per cubic metre under normal room conditions (temperature: 20 to 25 degrees Celsius, relative humidity: 30 to 60 per cent). The exposures to radon reach values of up to 3,500 kilobecquerel-hours per cubic meter.

One supplementary group is used to determine the effects of transportation and storage during the comparison (transit group). This transit group comprises devices which are transported and stored under the same conditions as the other devices but are not exposed in reference atmospheres. The devices will be returned after all exposures have been accomplished.

Evaluation

The participants will be asked to evaluate their devices and report the measurement results to the Federal Office for Radiation Protection. BfS prepares the final assessment after it has received all measurement results. To this end, the measurement results are compared with the reference exposures.

All laboratories which participate in the intercomparison will obtain

• a certificate of participation stating their measurement results and the corresponding reference exposures as well as
• a final report which includes the results of all participants in anonymous form with detailed information on the conditions of exposure.

BfS is committed to treating the data received and established confidentially. Results will be disclosed exclusively in anonymous form.

Numbers of measurement devices and exposure data

The intercomparison is arranged such that the requirements of the different detector types are taken into account. Please find the numbers of exposure groups and devices as well as exposure data in the following tables.

Participants

German as well as foreign laboratories can take part in these interlaboratory comparisons:

• Radon measuring services which provide measurement devices for monitoring occupational radiation exposures to radon or radon decay products in Germany are obliged to take part regularly in the interlaboratory comparisons according to the guideline “Richtlinie für die Überwachung der Strahlenexposition bei Arbeiten nach Teil 3 Kapitel 2 Strahlenschutzverordnung”.
• We also recommend the participation of radon measuring services which quantify radon activity concentration indoors and outdoors and are not associated with occupational radiation exposures. The participation should enhance business confidence in the performed measurements and the acceptance of results.
• Laboratories which posess or wish to acquire an accreditation for measuring the activity concentration of radon-222 fulfil the obligation to validate their measuring method in accordance with DIN EN ISO/IEC 17025 by participating in the intercomparison.

The German Federal Office for Radiation Protection (BfS) conducts the next interlaboratory comparison for passive radon measurement devices using track-etch detectors (SSNTD, in diffusion chambers) or electret ionisation chambers in the 1st quarter of 2018.