摘要
采用局部静态法测量介质表面的氡析出率时 ,受表面同时析出 土气的影响 ,测量值可能偏高。由于土气子体 2 16Po的半衰期T1/2 =0 .1 5s,在设计氡析出率测量装置时 ,合理选择采样器高度可有效减小甚至克服 土气对氡析出率的测量影响。用采样截面为1 88mm、高 1 2 5mm、内加静电场 (由直流电源或驻极体产生 )的采样器 ,采样周期分别为 1、2和 3h ,被测介质表面 土气析出率比氡的高 2个数量级条件下 ,研究了氡析出率受 土气干扰的程度。理论计算结果表明 :采用CR 39固体核径迹探测器的驻极体多功能快速测氡仪和电源式多功能快速测氡仪测量氡析出率时 ,测量结果受 土气的干扰可能偏大 35 5 % ,而采用金硅面垒作探测器的PCMR 1连续测氡仪测量 ,氡析出率受 土气的干扰可忽略不计。
Because of thoron exhalation, the measurement results of radon exhalation rate using a local still method is usually larger than the true value of radon flux rate of the monitored material surface. The influence of 216 Po(ThA) on radon exhalation rate can be eliminated for sensitive radon monitors. Theoretical evaluations of the influence of 212 Bi(ThC) and 212 Po(ThC′) on radon exhalation rate are carried out in a sampler with diameter of 188 mm, and height of 125 mm, and supplied electrostatic field inside (generated by high voltage and electret ) under following conditions: the sampling time are 1, 2, 3 h, respectively, thoron exhalation rate is 100 times of radon's. The calculation results indicate that the measurement results of radon flux rate are possibly 35.5% larger than true value due to the influence of thoron for fast and multifunctional radon monitors with electret, high voltage, respectively and using CR-39 SSNTD as detector, but this influence is negligible for PCMR-1 passive and continuous radon monitor using a silicon surface barrier as detector .
出处
《原子能科学技术》
EI
CAS
CSCD
2002年第6期543-547,共5页
Atomic Energy Science and Technology
基金
国家自然科学基金资助项目 (10 0 75 0 83)
