Kato Takahisa, Janik Miroslaw, Kanda Reiko, Ishikawa Tetsuo, Kawase Masaya, Kawamoto Takuo
Radioisotope Research Center, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
National Institutes for Quantum and Radiological Sciences and Technology, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
Health Phys. 2018 Aug;115(2):203-211. doi: 10.1097/HP.0000000000000851.
The practicality of using a liquid scintillation method with a nonvolatile liquid scintillation absorbent for the measurement of airborne Rn (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 Po 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 Po 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 in air was extrapolated to the region between 0 and 500 Bq m using the least-squares method with data from 500 to 8,000 Bq m. The validity of the extrapolated curve at less than 500 Bq m 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.
研究了使用带有非挥发性液体闪烁吸收剂的液体闪烁法测量住宅中空气中氡（Rn）的实用性。在经过校准的步入式氡室中，研究了液体闪烁吸收剂吸收的放射性与空气中氡浓度之间的关系。在对氡进行采样后，通过α粒子光谱法基于对产生的钋α粒子光谱进行1小时间接选择性测量，利用连续衰变方程在达到放射性平衡后立即计算钋的放射性，进而计算出氡的等效放射性。我们证实，液体闪烁吸收剂中吸收的氡量与空气中的氡浓度成正比。利用500至8000 Bq/m³的数据通过最小二乘法将在空气中显示出从500至8000 Bq/m³可靠定量线性的校准曲线外推至0至500 Bq/m³的区域。通过将室内和大气中测得的氡浓度与使用现有电离室测定的氡浓度进行比较，证实了外推曲线在低于500 Bq/m³时的有效性。观察到由于温度和湿度的变化，氡的吸收存在差异。还考虑了非挥发性液体闪烁吸收剂的健康和环境安全性。
