^220Rn子体结合态放射性气溶胶粒径分布实验研究

Measurement of Size Distribution for ^(220)Rn Progeny Attached Aerosols

放射性气溶胶粒径分布是评价环境中Rn、Tn子体所致呼吸道内照射剂量的重要参数。采用CR-39作探测器,ThB作示踪粒子,反推计算得到了Tn子体结合态气溶胶的中位径(CMD)和方差(GSD)。在广东省阳江市(高本底地区)进行的现场测量结果表明,CMD分布为30~130 nm,GSD分布为1.9~3.3。与北京大学技术物理楼的实验结果相比较可知,潮湿的农村的CMD较小,且环境越潮湿,CMD一般会越小。另外,通风对气溶胶粒径的影响也很明显,砖房在通风状况好的情况下有较大的CMD。砖房的CMD普遍比水泥房间的小。

The size distribution of radioactive aerosols is a very important factor for evaluating the inner exposure dose contributed by radon and thoron progeny in environments. In order to measure the size distribution of thoron progeny attached radioactive aerosols, a device was developed using wire screens. The count median diameter （CMD） and the geometric standard deviation （GSD） of attached radioactive aerosols were calculated by collecting ThB and using CR-39 as detector. Field measurement results at Yangjiang City in Guangdong Province show that the CMDs distribute between 30 and 130 nm, and the GSDs are between 1.9 and 3.3. It also shows that the more humid country, the smaller CMDs, and the ventilation has great influence on the size distribution of aerosols. The CMDs of adobe house are smaller than that of the concrete houses.