【作者】 李惠彬；

【导师】 李君利；

【作者基本信息】 清华大学 ， 核科学与技术， 2013， 博士

【摘要】 放射性气溶胶主要通过吸入的途径对人体产生内照射损伤，一种常用的监测手段是使用放射性气溶胶连续监测仪（简称连续监测仪）在现场进行连续监测。目前有多款商品化连续监测仪可供选择。但是这些仪器仅适用于天然氡浓度环境；在氡浓度很高的环境中，氡子体对测量的干扰很严重，这些商品化仪器对钚气溶胶的监测判断限（简称判断限）很高，远超过其浓度限值。本文系统分析了影响连续监测仪判断限的各种因素，在此基础上，提出了高灵敏度连续监测仪的设计方案，解决了相关关键技术，最终研制成功HS-CAM连续监测仪，并监测了一个山体坑道内的钚气溶胶浓度。主要内容包括：（1）系统分析了影响连续监测仪判断限的各种因素。包括五个方面：氡子体能谱拖尾程度、氡子体分离技术、运行模式、监测时间设置、能谱处理技术。（2）通过理论分析和实验解决了仪器研制所涉及的三个关键技术问题，包括：滤纸性能测试及选型、真空室设计及测试、氡子体粒度分离采样器研制。（3）在解决关键技术问题的基础上，完成了仪器总体设计、机械设计加工、电路测控系统研制、控制软件开发四项工作。研制了实用化的连续监测仪。（4）在不同的氡浓度环境下，设置不同的监测模式，对仪器的本底能谱进行测试。以此为基础，建立了可变拖尾比例系数法和能谱拟合剥离法相结合的氡子体扣除算法，编写了完整的能谱处理程序。（5）使用该能谱处理程序对获取的本底能谱进行处理，得到了该仪器在不同氡浓度和监测模式下的判断限指标。并根据多次重复测量的统计结果检验了算法的正确性。最后，使用该仪器监测了一个山体坑道内的钚气溶胶浓度，达到了预期效果。HS-CAM连续监测仪在借鉴国内外已有研究成果的基础上，采用了一些新技术，其判断限指标达到了目前为止该类仪器的世界最优水平。在天然氡浓度环境下，监测周期1hour，判断限约为0.003Bq/m3，相当于一般商用仪器的1/30-1/150。在氡浓度10000~20000Bq/m3的环境下，设置相同的监测周期，判断限也可以达到0.03Bq/m3。目前，该仪器的相关技术已经成熟，可以推广应用到地下仓库、坑道等氡浓度很高的环境，用于监测各类人工α气溶胶。更多还原

【Abstract】 Radioactive aerosols can cause internal exposure to human by inhalation, acommonly used monitoring technology is in-situ monitored by continuous radioactiveaerosol monitor(CAM). At present, there are many commercial CAMs can be used, butthose equipment can only be used in normal radon environment. in high radonenvironment, interference due to radon progeny is serious, decision limit of plutoniumaerosols(LCfor short) is too high, and exceeds the concentration limit. This articlesystemically analyze the factors influence LCfor CAM. Based on the analysis, designscheme of high sensitive CAM was made, key technologies were solved, finally,HS-CAM was developed, and plutonium aerosol concentration in a cave was monitoredby the the equipment.(1) Factors influence LC, and degrees of the influence were analyzed. There arefive factors: spectrum tailing of radon progeny, separation of radon progeny, runningmode, monitoring time set, spectrum analysis technology.(2) Three key technologies were solved by theoretical analysis and experiments,including: filter testing and selection, vacuum chamber design and testing, sizediscrimination sampler for radon progeny development.(3) Based on the key technologies that have been solved, four parts of work weredone, including: overall design, mechanical design and machining, electric circuit andcontrol software development. Finally, practical CAM was manufactured.(4) Background spectra of the HS-CAM were tested in different radonconcentration environments and in different running modes. Based on the acquiredspectra, methods used to deduct interference of radon progeny were established, it is thecombination of variable tailing parameters method and spectra fitting method, andcomplete program was written(5) The background spectra were processed by the spectra analysis program, andtheir accuracy was tested by the statistical results. LClevels in different radonconcentrations and running modes were acquired. Finally, the HS-CAM was used tomonitor plutonium aerosol in a cave, and achieve the anticipated results.HS-CAM absorbed research results that have been applied to commercial CAMs,and developed several new technologies, LCof the equipment is the best all over the world. In normal radon environment level, and the monitoring cycle is one hour, LCisabout0.003Bq/m3, about1/30~1/150of the LCof commercial CAMs. If radonconcentration is10000~20000Bq/m3, LCcan also reach0.03Bq/m3in the samemonitoring cycle.At present, technologies in the equipment have mature, it can be used in high radonenvironment to monitor artificial α aerosols. Such as underground storage, mountaincave, and so on.更多还原