辐射监测气溶胶制样方法测试对比

Test and comparison of aerosol sample preparation methods in radiation monitoring

利用高纯锗(HPGe)γ谱仪对4种放射性气溶胶制样方法(灰化法、压片法、打孔法和折叠法)制得的样品进行了分析测试研究,4种制样方法对同一活度样品的分析结果的标准偏差在5%以内,验证了此4种方法的可靠性。利用标准源实验刻度和蒙特卡罗模拟计算,得到4种制样方法的探测效率从高到低依次是:灰化法、压片法、打孔法和折叠法,对于辐射监测常用的260 mm′210 mm滤膜,4种制样方法的探测效率最大相差55%;对于570 mm′470 mm的滤膜,则相差120%。以^(137)Cs为例,对比计算了4种制样方法的最小探测活度,分析了4种制样方法的适用范围。

Background： There are four common methods to prepare radioactive aerosol samples for the purpose of gamma-spectroscopy involving an HPGe detector： ashing method, compressing method, holing method, and folding method. However, their counting characteristics have never been studied and compared. Purpose： This study aims to provide a comprehensive evaluation of these four sample preparation methods. Methods： An HPGe gamma spectrometer was used in the study to evaluate and confirm the reliability of these four radioactive aerosol sample preparation methods. Monte Carlo simulations were used to calculate the gamma-spectroscopic counting efficiency. Results： The four preparation methods were found to be generally reliable, with assessed activity differing less than 5%. The ashing method was found to yield the highest counting efficiency, followed by compressing method, holing method, and folding method. For the 260mm×210mm and 570mm×470mm sized filter, the variation range of gamma detection efficiency was found to be 55% and 120%. Conclusion： The analyses of these sample preparation methods provide useful suggestions on the suitability and conditions, thus offering a useful reference on how to choose, prepare and count radioactive aerosols samples.