Intercomparison Excises of Radon Measurementin the Radon Reference Chamber of PTB

摘要

While numeroush radon measurements have been widely carried out by using various types ofmeasurement devices so far, intercomparison exercises have been also conducted in order to establishtraceability on radon evaluation among major research laboratories all over the world. Recently, theNational Institute of Radiological Sciences (NIRS), one of standard facilities of radon measurements andcalibration in Japan, has initiated some intercomparison exercises with several institutions of the UnitedStates and European countries.The Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany is the standard radonfacility which has provided calibrated radon activity concentrations for the several laboratories in Europeand is now collaborated with NIRS for radon calibration in a couple of years. In 2003 and 2005, NIRS andPTB carried out the radon exposure experiments of the NIRS radon measuring devices under threeexposure conditions: Low concentration (approx. 1500 Bq m-3), Medium concentration (3000-4000 Bq m-3) and High concentration (9000-10000 Bq m-3) in the radon reference chamber of PTB. The JapanNuclear Cycle Development Institute (JNC, present JAEA), which also possesses its own practical radonchamber, participated in the experiment held in 2003.In total, the experimental results by three institutes were in good agreement with each other Althoughthere is still room for further discussion from a viewpoint of uncertainty for calibration factor among threeinstitutes, these experiments provided important information for quality of radon measurements carried outin Japan.