用αβ谱仪测量人工αβ放射性气溶胶体积活度的试验研究  

Studies on Measuring Activity Concentration of αβArtificial RadiologicaI Aerosols with αβSpectrometry

作　　者：刘伯学 张清容 李郁 王英 朱中梅 毛用泽 

出　　处：《核电子学与探测技术》1996年第5期368-373,共6页Nuclear Electronics & Detection Technology

摘　　要：本文介绍了用αβ谱仪系统同时测量αβ谱、实现Ｒｎ／Ｔｈ子体补偿、确定超铀α核素气溶胶体积活度及人工放射性气溶胶总β体积活度的技术途径。利用ＲａＡ、ＲａＣ′ａ峰的二段时间计数可确定空气中ＲａＡ、ＲａＢ、ＲａＣ的气溶胶体积活度，相应的，也能给出ＲａＢ、ＲａＣ对总β计数的贡献。根据一般环境条件下的平衡比，用ＴｈＣ′的。计数修正Ｔｈ子体对αβ测量的影响。￣［２３９］ｐｕ或／和￣［２４１］Ａｍ人工核素的α计数，可通过两段时间分别扣除ＲａＡ、ＲａＣ′拖尾的方法确定；β计数分别扣除Ｒｎ／Ｔｈ子体β贡献即可确定。在本文规定的测量条件下，对室内天然Ｒｎ子体水平在１５Ｂｑ／ｍ￣３以下，超铀α核素气溶胶体积活度的测量下限可达到０．１Ｂｑ／ｍ￣３；即使在７５Ｂｑ／ｍ￣３环境下，人工核素总β的测量下限也可达ｌＢｑ／ｍ￣３以下。The paper introduces a method to determine the volume activity concentration of α transuranic elements and totalβartificial radionuclides in the environment.and Rn/Th daughters background-conpensation by αβspec-trometry.By measuring the a counts of RaA and RaC′in two intervals,the activity concentration of RaA,RaBand RaC can be evaluated,meanwhile,the totalβcounts of RaB, RaC aerosol can also be determined.Theαcounts of transuranic aerosols can be determined by substracting the trail counts of RaA and RaC α peaks in eachintetval.Under average equilibrium factor of Th daughters in general environment,the αcounts can be correctedby ThC′peak counts。The total βcounts ofβartificial radionuclides can be determined by substracting the βcounts of RaB,RaC and ThB,ThC,Sampling 20 min,waiting 2 min, and measuring 2～15 and 1 5～40 mincan keep the expanded uncertainty of Rn daughters concentration less than l5%. If the Rn daughters concetra-tion is less than l 5Bq/m￣3, the lower limit of detection(LLD)will be less than 0.1Bq/m￣3.The lower Rndaughters concentration, the lower the LLD will be,Even if the Rn daughters concel1tration is as high as 75Bq/m￣3,the LLD of totalβaerosol activity concentration will be less than lBq/m￣3.(

关 键 词：Α谱仪 超铀核素 放射性气溶胶 αβ放射性 

分 类 号：X591.02[环境科学与工程—环境工程] TL817.2[核科学技术—核技术及应用]