Experiential Study On And The Application Of Equilibrium Factor Of Radon And Its Daughters In Some Fields

Radon and its daughters are one of the major sources of natural radiation to which humans are exposed.More particularly,radon is the greatest factor after smoking that contributes to lung cancer and has been recognized by the World Health Organization as one of the 19 most carcinogenic substances. Radon and its daughters are everywhere and,in terms of dosage contribution, the daughters are far more important than radon.Dose caused by environmental radon progeny is approximately estimated mainly by using the environmental radon exposure dose and the recommended equilibrium factor of radon and radon progeny. However, environmental conditions vary greatly in different places, and therefore the equilibrium factor of radon and radon progeny also vary greatly, resulting in a big estimation error in its estimation method. In order to improve the quality of the dose caused by radon progeny estimated based on radon exposure, it is necessary to measure the radon and radon progeny balance factor in some fields.By adopting the NRL-?continuous radon monitor and NR-200 A continuous radon daughters monitor developed by University of South China,the equilibrium factors of radon and its daughters in the air are measured in some fields:including A Nuclear Power Base, Hunan Xiangya Hospital, Hunan Provincial Tumor Hospital and Jinyuan Uranium Industry Company and so on.The results showed that the equilibrium factor of Radon and its Progenies in coastal areas and Radiation Therapy Center was 40% less than the recommended value.The regional equilibrium factors of Radon and its Progenies in some fields with good ventilation and air purification measures were even smaller, and the equilibrium factor of Radon and its Progenies in the indoor environment of inland provinces were similar with the recommended values.At the request of Phase II Works of Qinshan Nuclear Plan,CNNC Operation Management Co.,Ltd,Phase II works of this nuclear power base was evaluated for effective annual dosage received by the staff and contributed by radon and its daughters in certain plants and offices. According to the results,the effective dosages(below 1mSv without exception) contributed by radon and its daughters, as estimated from the equilibrium factor at the measurement points based on the concentration of radon and its daughters in the plants and offices.The study described in this paper,the necessity of improving the calculation reliability of the dosage contributed by environmental radon and its daughters as well as measuring the equilibrium factor of radon and its daughters in fields.