| The wide applications of building materials produce serious pollution in indoor environment, and also bring a variety of diseases and serious harm to the health of the residents. In recent years, the radioactivity of building materials gradually cause people attention, becoming the global focus. Therefore, the study of the radioactivity level of building materials can guide people to the correct rational use of building materials and avoid health damage.In this study, with the method of the building materials market research, sample collection, processing, the measurement and analysis, safety assessment, the radioactivity of building materials in Nanjing was measured and in accordance with national building materials radionuclide limit, radium equivalent concentration and effective dose equivalent indicators, the safety evaluation was carried on. The conclusions of this paper as follows:(1) The radionuclide content of natural stone was14.65～181.35Bq/kg for226Ra, the average value was64Bq/kg, and the largest vaule was Fujian Red while the smallest was French beige; the Th activity ranged from:0.86～94.81Bq/kg and the average value was13.7Bq/kg, the largest of which was Fujian Red while smallest was Rosin Jade; the40K specific activity ranged from:5.67-1362Bq/kg and the average value was212.00Bq/kg, the largest value was Fujian Red while the smallest was grain stone. Among them, Fujian, Shandong, Guangdong and Jiangxi stone have high radioactivity levels.The content of radionuclides in tile tamples:the specific activity of226Ra ranged from:151.03～769.34Bq/kg, the average value was296.27Bq/kg, the largest of which was Tao Hui brand tile while the smallest was Sword brand tile; the range content of232Th was51.66～172.50Bq/kg, the average value was105.34Bq/kg,and the max value was Jinle brand tile while the smallest was JuYang brand tile; the40K specific activity range of503.10～1370.16Bq/kg, an average of831.69Bq/kg, the largest of which was the Tao Hui brand and the minimum was Dadi brand tile.In the main building materials, the226Ra specific activity ranged from:103.11～206.87Bq/kg, the average value was151.81Bq/kg and the largest was slag cement while the minimum was ordinary cement; the232Th specific activity ranged from:11.35～54.10Bq/kg and the biggest was slag cement while the smallest was the stone powder; the40K specific activity ranged from:92.57～734.24Bq/kg and the largest was gravel while the smallest was ordinary cement.(2) The radioactive content of fly ash and clay in raw materials were not excessive. The radioactive content of the slag from Fujian Province was more than limited value, and others were not excessive.The concentrations of radionuclides in the glaze was high, which was about100times than raw materials. It is show that the highly radioactive of tiles due to glaze. We should strictly control the amount of the glaze and take the appropriate way to reduce the radioactivity concentration of the glaze.(3) The radioactivity levels of the natural stone samples are in line with national standards for a Class A product. However, the annual effective dose equivalent of Blackstone, Fujian red, lychee red and India reddish brown stone was more than lmsv, which was need to be payed attention. Except Dadi brand tile, Liangjian brand tile and Haohua brand tile were Class A product, of which the use were unrestricted, other samples exceeded the value were the Class B and Class C product. It is noticed specially that the Taohui brand tiles were seriously overweight, belonging to the super-class C, which can only be used for sparsely populated area. The annual effective dose equivalent of the tile samples all exceeds the international limit value1msv. These should be draw attention to. The main building materials measured, expect the slag cement as the Class B product, was the Class A product which the use of was unrestricted. |
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