The practicality of using a liquid scintillation method with a nonvolatile liquid scintillation absorbent for the measurement of airborne 222Rn (radon) in a residence was examined. The relationship between the radioactivity absorbed by the liquid scintillation absorbent and the radon concentration in the air was investigated in a calibrated walk-in radon chamber. The equivalent radioactivity of radon was calculated for 214Po radioactivity immediately after radioactive equilibrium was attained using successive decay equations via alpha-particle spectrometry based on the 1 h, indirect, selective measurement of the 214Po alpha-particle spectrum generated after sampling radon. We confirmed that the amounts of radon absorbed in the liquid scintillation absorbent were proportional to the radon concentration in the air. The calibration curve that exhibited reliable quantitative linearity from 500 to 8,000 Bq m−3 in air was extrapolated to the region between 0 and 500 Bq m−3 using the least-squares method with data from 500 to 8,000 Bq m−3. The validity of the extrapolated curve at less than 500 Bq m−3 was confirmed by comparison of the measured radon concentrations in the room and atmosphere with those determined using an existing ionization chamber. Variations in the absorption of radon were observed due to changes in temperature and humidity. The health and environmental safety of nonvolatile liquid scintillation absorbent was also considered.
1Radioisotope Research Center, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan;
2National Institutes for Quantum and Radiological Sciences and Technology, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan;
3Department of Radiation Physics and Chemistry, Fukushima Medical University, Hikariga-oka 1, Fukushima, 960-1295, Japan;
4Faculty of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan.
The authors declare no conflicts of interest.
For correspondence contact: T. Kato, Radioisotope Research Center, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan, or email at email@example.com or firstname.lastname@example.org.
(Manuscript accepted 11 January 2018)