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Objective:To study the levels and variation of equilibrium factor in indoor environment.Methods:A one-year continuous measurement of radon concentration and equilibrium equivalent radon concentration was carried out in an indoor office building of Nanning city. The effective data acquisition rates of radon gas and radon progeny were 99.9% and 86.7%, respectively.Results:The annual average activity concentration and equilibrium equivalent radon concentration in indoor environment were (50.9±20.7)and (15.5±10.1)Bq/m 3, both of which had the same diurnal and seasonal variation. The average annual value of equilibrium factor was 0.30±0.12, showing no obvious diurnal variation. The distribution of monthly mean value of equilibrium factor showed a similar trend to that of radon and radon progeny. The highest and the lowest value appeared in November and June, respectively, with 0.47±0.24 and 0.19±0.06. Conclusions:Due to the large variation range of monthly mean value of equilibrium factor in indoor environment, when annual effective dose of radon exposure was estimated based on radon gas concentration, attention should be paid to choose the quantity value of equilibrium factor and the uncertainty caused by the change of equilibrium factor should be considered.
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Objective The radioactivity level survey was carried out in Weizhou Island area of Beihai, to comprehensively master the radiation environment status in the area, understand the natural radioactivity level and its distribution law, and provide basic data for scientific evaluation of radiation environment quality. Methods According to the relevant standards and technical specifications, the air absorbed dose rate of gamma radiation in Weizhou Island area was monitored from April 2020 to March 2021, the concentrations of radionuclides in water, soil and other environmental samples were sampled and analyzed, and the monitoring results were analyzed and discussed in combination with the regional characteristics. Results The results show that the air absorbed dose rate of gamma radiation in Weizhou Island area ranges from 0.2～122 nGy/h; the activity concentrations of 238U, 226Ra, 232Th, 40K and 137Cs in solid samples range 17.0～37.3 Bq/kg, < 0.501～29.5 Bq/kg, < 0.766～54.3 Bq/kg, 18.7～369 Bq/kg and < 0.212～1.48 Bq/kg, respectively, the concentrations of U and Th in well water and reservoir water range 0.065～0.25 μg/L, 0.046～0.079 μg/L, the activities of 226Ra, 40K, total α and total β range 1.42～3.08 mBq/L, 0.069～0.231 Bq/L, 0.025～0.163 Bq/L, 0.082～0.572 Bq/L, respectively, the concentrations of U and Th in seawater samples range 1.81～2.25 μg/L, 0.634～0.648 μg/L, and the activities of 226Ra, 40K, 90Sr and 137Cs range 9.38～19.7 mBq/L, 11.3～11.8 Bq/L、0.193～0.866 mBq/L、1.13～1.42 mBq/L. Conclusion The environmental ionizing radiation level in Weizhou island of Beihai is in the range of background fluctuation and at a relatively low level, indicating that the radiation environmental quality of Weizhou Island and its surrounding areas is good.
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The investigation of environmental radioactivity level is an important basic work of ecological environment protection. It can provide basic data and scientific basis for the evaluation of radioactive environment quality and the formulation of radiation safety regulations and standards. Based on many years of practical experience of environmental radioactivity level investigation, combined with relevant regulations and standards, this paper summarizes the common investigation methods in the investigation and research of environmental radioactivity level at home and abroad, summarizes a set of environmental radioactivity level investigation scheme with strong applicability, and gives detailed suggestions on the ideas, methods, technical routes and other key points of the investigation scheme. The research results of this paper can provide a reference for the preparation of environmental radioactive level investigation scheme.