The Study Of Continuous Momitoring Method Of Radon Emission Rate In Uranium Mine Ventilation Shaft

With the development of technology, the nuclear power and industry has been attracted increasing attention, the development of uranium resources exploitation is gradually becoming faster and deeper in our country. Studies show that the gaseous radioactive effluents account for 76.6% in public's collective radiation dose of uranium system.85% radiation hazards which underground workers suffered was caused by the internal irradiation of radon and its daughter from uranium ventilation airflow.The radon emissions and concentration in ventilation shaft is one of mine radioactive gaseous effluent monitoring program,which is mentioned in GB23726?2009 "Uranium mining and environmental radiation monitoring provisions" ? GB23727?2009 "Uranium radiation protection and environmental protection provisions" and other national standards, but national standards of emission limitsuranium gaseous effluent has no relevant provisions yet in our country.Ventilation shaft emission of radon concentration has a certain distribution, but people is simply sample to measure the radon concentration and wind speed from any wellhead of shaft in practical work and estimate the radon emission rate, which will be a great deviation. Therefore the distribution of radon concentration of uranium ventilation shaft should be researched necessarily, and accordingly established the method of testing radon emissions rate rapidly and accurately.Using single?point sampling method to measure the radon concentration and wind speed distribution of discharge port of a uranium mine ventilation, and calculating the rate of radon row with integral interpolation procedure, the results found that wind speed distribution and radon concentration is approximately acess to axisymmetrical distribution of uranium radon ventilation on wellhead 2m depth profile. That is to say that the distance from the middle to well sides become closer and closer and the radon concentrations and wind speed become lower and lower at the highest center. At the based of above, an mixing average radon measurement method of unattended monitoring has been proposed. At the end of single?point sampling measurement, using mixing average radon measurement method for 12 hours continuous monitoring at the same uranium vents, theexperimental results show that at beginning of the measurement period,the concentration of radon is relatively stable,the average concentration of radon is about 6.36×104Bq / m3, the radon emission rate is about7.414× 106 Bq / s, while the average concentration of radon with single?point sampling method is approximately about 6.35×104Bq / m3, the radon emission rate is about7.419×106Bq/s, the relative deviation of average concentration of radon measurement results with this two ways is about0.1% or less, two end results are very close, which indicates the effectiveness of the mixing average radon measurement method. It can be seen that single?point sampling method is more accurate to measure distribution of radon concentration of uranium ventilation shaft. While mixing average concentration of radon measurement method is more suitable for the average concentration of radon measurement,which not only ensures the measurement accuracy, but also saves a lot of manpower and resources. Therefore mixing average method is an important means to develop the continuous monitoring for radon emission rate of uranium ventilation shaft.This research established the foundation of continuous and accurate monitoring the radon emission rate of uranium mine ventilation shaft in the future.