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Renewal of the measuring devices: relocation of radon metrology

01.02.2011

Radon metrology at PTB moves to another location: After 20 years of successful work in the setting-up, investigation and development of new procedures, the laboratory area so far used is becoming too small. The extension of radon metrology in the past few years from radon-222 to radon-220 (thoron) and, recently, to the sector of low-level measurements, has brought about an increase in measuring devices.

In the basement of the new building - the renovated Elster Geitel Building - a new radon standard chamber RNK-II with a volume of approx. 21 m3 and a partly renewed thoron progenies chamber TFK-II with a volume of approx. 6 m3 have been established.

The new RNK-II has a welded insulating cell to guarantee optimal gas tightness. The minimum temperature now amounts to -40 °C. The climate area covers a temperature range from +10 °C to +60 °C and a relative humidity range from 10 % to 95 %. The RNK is controlled and regulated via a commercial program.

The new TFK-II maintains the specifications. The climate area covers a temperature range from +10 °C to +70 °C at a relative humidity range from 10 % to 95 %.

The basement of the Elster Geitel Building is equipped with an air-conditioning system which is operated 100 % with external air and has fine-particle filters in the supply air pipe. This guarantees a reduction in the natural background by radon and radon progenies and, thus, a reduction in the measurement uncertainties, in particular in the field of thoron and thoron progenies measurements.

After the laboratory had been relocated and reconstructed in the new building at the end of 2010, the new air-conditioned testing chambers have been run with respect to the specifications and environmental parameters, the aerosol concentration and the radon activity concentration preferably desired by the customers, so that calibration operation could be resumed as smoothly as possible.