Study On The Variation Characterristics Of Radon Exhalation Rate And Its Application In Uranium Tailings Reservoir

In order to solve the environmental assessment problem of some specific places, such as large nuclear facilities, uranium tailings, a reliable estimation method of annual radon release must be set up. However, radon exhalation rate changes with some complex meteorological parameters such as atmospheric pressure, temperature, humidity and so on, and exits a nonuniform distribution. Therefore, the key way evaluating radon annual release accurately is at measuring the characterristics of the regional distribution and variations with time of radon exhalation rate on the surface of uranium tailings reservoir.Based on the optimum setection of radon exhalation rate methods, the activated carbon gamma energy spectrum method was selected for measuring the characterristics of the regional distribution and the electrostatic collection method measuring the variation with time. Based on the activated carbon gamma energy spectrum method, some sorts of active carbon sample devices whose basal area, height, active carbon and air contact area are different were reseached. The experimental results show that the effective contact area of active carbon and the air in the sampling device can affect the reliability of the sampling device.In the condition of sufficient and effective contact area,sampling devices with different bottom area and different height are selected,the relative deviation between the measurement value of sampling device and the reference value is not more than 5%. In order to solve the defect about standard of activated carbon box measuring radon exhalation rate of uranium tailings reservoir,a new type of radon exhalation rate sampling device was designed and realized the convenient, reliable, and fixed-point measurement of the relative distribution of radon exhalation rate of uranium tailings reservoir.The new type of activated carbon sampling device and the apparatus for continuous measurement of radon exhalation rate based on the method of electrostatic collection are used for measuring radon exhalation rate in tailings area and clay area of uranium tailings reservoir.The results show that under the condition that the sampling time of the new type of active carbon sampling device is greater than 24 h, the water content of activated carbon is less than 10% after sampling,the impact of humidity on site measurements of activated carbon method can be ignored. The radon exhalation rate of uranium tailings reservoir changes with some complex meteorological parameters and exits a nonuniform distribution, radon exhalation rate is increased with the increase of air temperature in one measurement result, it is shown that the measured values are significantly increased from noon.Estimating the radon exhalation rate of the measured surface accurately in combination with the relative characterristics of the regional distribution using activated carbon method to measure the radon exhalation rate of uranium tailing surface and the continuously change characterristics of the selected comparative measuring points, a reliable estimation model for the annual release of radon in uranium tailings reservoir is established and the accurate radon release rate of object area is obtained, and then provide technical support for the monitoring and evaluation of environmental radon pollution in typical places.