| Nuclear technology is widely used in various social production practices such as industry,agriculture,medicine,and scientific research,and has greatly promoted the progress of national science and technology and the development of the national economy.However,the development of nuclear technology will inevitably produce radioactive waste.If radioactive waste cannot be managed safely,it will restrict the development of nuclear technology.The Jiangsu urban radioactive waste repository is a regional temporary repository of solid radioactive waste and waste radioactive sources.The comprehensive monitoring of the radiation environment quality is of great significance to the development of nuclear technology in the province.This paper takes the radioactive waste repository as the research object,monitors the air,water,soil and biological radiation environment in each area of the radioactive waste repository,and compares the monitoring data in the past seven years to analyze the reasons for the changes.The main research contents are as follows:（1）Comprehensive monitoring data were obtained for the surface pollution,γ-radiation air absorbed dose rate and neutron dose rate monitoring in various areas of the radioactive waste repository.After the high,medium and low dose areas in the radioactive waste repository are closed for 15 days,theγ-radiation air absorbed dose rate rises to a dose rate balance.Under ventilated conditions,theγ-radiation air absorbed dose rate in the low and medium dose areas can quickly drop to the dose rate balance.After the high dose area is closed for 15 days,it takes20-25 min to drop to the dose rate balance.Through continuous monitoring and analysis of distribution cloud diagrams outside the radioactive waste repository,the radiation level outside the radioactive waste repository is mainly affected by the prevailing wind direction,rainfall and ventilation.The total radioactivity detection of aerosols and sediments outside the radioactive waste repository showed that the total radiation levels of aerosols and sediments have basically the same trend.The main reasons for the changes are seasonal changes and differences in regional locations.（2）The radioactivity detection of the water sources around the radioactive waste repository shows that the total radioactivity level during the wet season is less than that in the dry season,and decreases with the increase of the distance from the radioactive waste repository.The radioactivity level of the soil at different distances and azimuths around the waste storage was tested.The results showed that as the distance from the radioactive waste repository increased,the specific activities of 238U,232Th,226Ra and grossαdecreased,while the specific activities of 40K and grossβincreased.This is mainly related to the distance from the radioactive waste repository and human factors.The total radioactivity level of the plants in the radioactive waste repository increases with the exposure time,and the growth rate of the grossαcontent of the plants in the radioactive waste repository is much greater than the grossβ.The main reason is that the influence of the irradiation on the grossαis greater than the grossβ.The radioactivity level of plants outside the radioactive waste repository decreases as the distance increases.The maximum value of pine needles at 150 m is mainly related to the uncertainty of atmospheric circulation.（3）From 2015 to 2021,a longitudinal comparison ofγ-radiation air dose rate,aerosol,water and soil total radioactivity levels showed that the monitoring results over the years have all changed within the background range.The main factors causing the changes are the distance from the radioactive waste repository,meteorological conditions,the number of waste sources,and the management of waste sources. |
PDF Full Text Request