Research On Continuous Plutonium Aerosol Monitor In High Radon Environment And Equipment Development

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.