Study On Transformation Of Temperature And Humidity Control System For Radon Chamber

Radon and its daughters not only are the decay product of natural radioactive uranium series and thorium series, but also are one of natural radiation source. Meanwhile, study and utilization of radon and its daughters is one of the standard for gaseous substance of radioactive measurement in ionizing radiation metrology.So, accurate measurement of radon and its daughters is the necessary means to control pollution and ensure the human health, has great significance on carrying out scientific development view and constructing Harmonious Society.Radon chamber is a calibration and experimental device, which has usually used in instrument scale, performance test, controlled experiment. In Western China, a first mini-type radon chamber had constructed by Chengdu University of Technology, Subsequently, by means of cooperation with National Institute of Measurement and Testing Technology, we successfully developed the medium radon chamber which is the paper based on. It has been put into use. Moreover, it undertakes the tasks of testing calibration, instrument scale, performance test .However, in practical application, it is found that the temperature and humidity control system should be perfected further then improved the accuracy of measuring.The existing system lacks perfert temperature and humidity control system,so the variation of the temperature and humidity would occur when system working.The reasons for this phenomenon:heat exchange between metal container and ambient air ,heat produced by the fan and the calibrationing instrument,air convection leads to frictional heat,the steam in the liquid radon source and so on.A large number of experiments indicate that these parameters would affect the instrument function.The conditions of instrument is less than 40℃and 25%RH, only in this way,they work well accurate. Therefore, it is necessary to research on monitoring and control system. It is also important to scientific and ccuracy of the instrument scaling and performance test, will provide a experimental platform for the preceeding research of the charge of the radon and its daughters. Therefore, on the base of refering some former experience, this paper will strengthen theoretical research, proposed feasible scheme and test.This thesis presents the measuring and controlling system about temperature and humidity, considering the accuracy, efficiency and economy, we choose the digital temperature and Humidity Sensor and semiconductor chilling plate with high performance-price ratio, finally the system achieved accurate measurement and accuracy control. According to different parameters, it can be Input the preset value by the keyboard. When the parameter has exceeded the limit, including temperature and humidity, the MCU control the relay to actuate mechanism for compensation. The lower computer communicate with the host computer through RS232 and easy to Integrated Control. This software is written with language C and adopted modularity design. The modules are composed of data acquisition, keyboard and display, Serial communication and Data Processing and so on.By debugging on running, the experimental result is in well agreement with anticipated. This system is simple, reliable, stable and low cost. It can be applied in temperature and humidity measurement and control of radon chamber.