Utilizing the AlphaGUARD emanometer and AquaKIT accessories which are often used as international calibration reference devices,we carried out a calibration experiment without radon source to two scintillation chambers of FD-125 emanometer.By changing the system volume,the readings of AlphaGUARD radon measurement instrument were kept in less than 1000 Bq/m3,1 000～2000 Bq/m3,et al,higher than 10000 Bq/m3 and total six different ranges.When the radon concentration were higher than 1000 Bq/m3,the deviations of K values are all less than 5 ％ relative to the average of all K values,and the K values relative to that using radon source were less than 5 ％.When the radon concentration were less than 1 000 Bq/m3,the K values deviations were all more than 5 ％ relative to the average of all K values.Therefore,the basic condition of the calibration without radon source was the radon concentration in the system needed higher than 1000 Bq/m3.According to the water vapor balance of radon in the closed system,the lowest water radon concentration could be required.This study not only verified the calibration with standard instrument can replace the calibration with radon source,but also determined the conditions needed for the calibration of standard instrument.This would lay the theoretical foundation for establishment and extension of method procedures.%利用AlphaGUARD测氡仪及AquaKIT水氡测量组件,使用水中溶解氡对FD-125测氡仪标配的两个闪烁室进行标准仪器校准.通过改变系统内体积,保证系统内AlphaGUARD测氡仪读数分别在＜1 000 Bq/m3,1 000～2000 Bq/m3,……,＞10000 Bq/m3等6个不同范围内.结果表明,当系统内氡体积活度大于1 000 Bq/m3时,所得到的K值相对于均值的偏差均≤5％,而且相对于氡气固体源校准得到的k值相对误差均≤5％;而当系统内氡体积活度小于1 000 Bq/m3时,所得到的K值相对于均值的偏差较大(10.2％与13.3％).因此,认为标准仪器校准需要的条件是系统内氡体积活度＞1 000 Bq/m3,再根据氡在闭合系统内的水气平衡公式,得到台站开展标准仪器校准所需的最低水氡体积活度.本工作进一步研究了利用水中溶解氡加标准仪器的标准仪器校准技术代替氡气固体源校准的方法,而且基本确定了开展标准仪器校准所需条件,为下一步该校准方法规程的制定与方法推广奠定理论基础.
展开▼
