Research On Environmental Parameters Monitoring And Technology Of Sampling Flux Controlling In Airborne Radioactive Measurement

The airborne radiomaterial is some radiomaterial which is carried by air or other gaseous medium. It is composed of radioactive gas and radioactive aerosol. There is airborne radiomaterial pollution problems in all walks of life, but only differ in degree. Our country needs airborne radiomaterial monitoring in more and more fields, and the demand for the monitoring equipment will be higher and higher. Researchers gradually pay more and more attention to such studies. However, only a few production enterprises are able to produce those radioactive monitoring equipment in our country, the majority rely on imports. Therefore, it is of great significance to provide a practical scheme for airborne radiomaterial sampling control, and realize the real-time monitoring of temperature, humidity, pressure and flux and the flux control in the sampling process.Based on single-chip microcomputer of series Intel51, the equipment is proposed to study monitoring and sampling of environmental parameter in airborne radiomaterial measurement in this paper. Hardware design are explained the choosing and usage of sensors-chips, A/Dconvertor-chip, keyboard and nixietube drive-chips, photoelectric coupling isolation-chips and the drive circuit of direct current pump-chips and USB interface-chip in detail separately. Software design is composed by software of SCM and software of PC. The software of PC is programmed by the soft of Visual Basic, achieved data transfer between SCM and PC, and design of interface of consumer. The soft of MCU is programmed by assemble language, involved the part of data transfer between USB and PC, keyboard and display by nixietube, data acquired and converted, speed regulated of direct current pump, PID control arithmetic programme. The PID control arithmetic programme is introduced in detail. In this work, one-wire bus digital temperature sensors-chip DS18B20 is chose. It is able to converts the measured temperature to a digital signal direct, and achieve 9 to 12 precision reading. The humidity sensors-chip is HIH-4000, it could output linear voltage which is proportional to the humidity and input the voltage values to controllers directly. Pressure sensors-chip is adopted by MPX4100A, which possesses the temperature compensation function. AWM5104 is adopted as the flux sensor. USB port is the data communication element between singlechip and computer, and MM74C922 is keyboard management chip that have the function of elimination dithering and output the BCD code directly. MAX7219 is used as the digital display-chip. In view of the instability of pump possibly affect the measurement results in airborne radioactive sampling process, PID algorithm is used to keep flow constantly.