一种确定活性炭滤盒源中碘活度分布的方法

I-131是一种重要的人工放射性核素，是核设施的重要检测对象。目前主要利用均匀分布的Ba-133源代替碘源对I-131的检测仪器进行校准。但在量值传递过程中，I-131校准标准源的分布情况直接影响标准源的定值，对检测仪器的校准产生影响。利用平面源确定不同深度的探测效率，建立效率深度曲线，拟合结果为η(x)=0.007 655e^{-0.020 6x}。由此通过数学分析建立I-131的活度效率方程，利用正反测量结果进行求解，确定其活度分布情况。三个待测I-131源的分布情况为均匀分布、指数分布以及平面分布，均匀分布的源正反测量结果偏差不超过1%，平面分布的源正反测量结果偏差大于50%，指数分布源的偏差介于两者之间。结果表明，通过源分布的快速求解判断，便于校准标准源的准确制备以及现场校准流程的建立。

Method for Determining Iodine Activity Distributionin Activated Carbon Filter Cartridge Source

I-131 is an important artificial radionuclide and an important detection object in nuclear facilities.The current mainstream method is to use a uniformly distributed Ba-133 source instead of an iodine source to calibrate the I-131 detection instrument.However,in the process of value transmission,the distribution of the I-131 calibration standard source directly affects the setting value of the standard source and affects the calibration of the testing instrument.The plane source is used to determine the detection efficiency at different depths,and the depth efficiency curve is established.The fitting result isη(x)=0.007655e-0.0206 x.Therefore,the activity efficiency equation of I-131 was established through mathematical analysis,and the positive and negative measurement results were used to solve it to determine its activity distribution.The distribution of the three I-131 sources is uniform distribution,exponential distribution and plane distribution.The deviation of exponential distribution source is between the deviation of the positive and negative measurement results of the uniform distribution source,which does not exceed 1%,and the deviation of the positive and negative measurement results of the planar distribution source,which exceeds 50%.By judging the quick solution of the source distribution,it is easy to prepare the calibration standard source and establish the on-site calibration process.