1.On-site calibration of measurement equipment in state-controlled atmosphere radiation environment automatic monitoring stations
Shaoting LI ; Lixiang XIAO ; Shuyu JIANG ; Chuanbo DAI ; Wenxiang ZHENG
Chinese Journal of Radiological Health 2025;34(3):402-407
Objective To perform on-site calibration of high-pressure ionization chambers and NaI(Tl) γ spectrometers in state-controlled atmospheric radiation environment automatic continuous monitoring stations and verify the reliability of the online radiation environment monitoring system. Methods 137Cs, 60Co, and 241Am were used as γ reference radiation sources to measure the metrological performance of high-pressure ionization chambers in nine state-controlled atmospheric radiation environment automatic monitoring stations in Hubei Province, China. The performance metrics included background radiation, response, and repeatability. Additionally, the correlation between dose rate and humidity was analyzed, and the energy resolution and activity response of NaI(Tl) γ spectrometers were measured. Results Among the nine state-controlled atmospheric radiation environment automatic monitoring stations, the background radiation of high-pressure ionization chambers ranged from 58.2 nGy/h to 82.6 nGy/h. The response of the high-pressure ionization chambers ranged from 0.94 to 1.08, fulfilling the requirement of 1.0 ± 0.2. The repeatability of high-pressure ionization chambers ranged from 0.43% to 3.80%, satisfying the requirement of not exceeding 10%. A significant correlation was observed between dose rate and humidity, with a correlation coefficient of 0.4476. For NaI(Tl) γ spectrometers, the energy resolution ranged from 6.8% to 7.9%, fulfilling the requirement of not exceeding 9% for the 661.7 keV energy peak of 137Cs. The NaI(Tl) γ spectrometers showed 1.4% to 1.8% s−1·Bq−1 activity response to 241Am and 6.6‰ to 8.4‰ s−1·Bq−1 activity response to 60Co. Conclusion The online monitoring systems in the nine state-controlled atmospheric radiation environment automatic monitoring stations are stable and reliable, providing accurate radiation environment monitoring data for public awareness.