Assessment of Radioactivity Concentration and Radiation Hazards Index for Building Materials Used in Babadogo Estate, Nairobi City County, Kenya
Oborah, Amukah Kenneth
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Natural radioactive materials in certain conditions can get to hazardous radiological level. Some of these hazards are not prone to control as well as, they are usually referred to as the background radiation. The aim of my research work is to evaluate natural radioactivity concentration and radiological impacts on representative sampled building materials collected from different locations in Babadogo estate within Nairobi City County. The selected samples were crushed, sieved dried and store for four weeks after which, analysis done using gamma ray spectrometer was put into action for spectral data acquisition then analysis. The activity concentration levels of 238U, 232Th and 40K for the selected samples of building materials was measured by the use of gamma- ray spectrometry method. Radiological parameters were evaluated based on the prerequisite activity concentration obtained. The analyzed data compared with the standard acceptable values. The activity concentration in 40K varied from 55±3 to 2647±132 Bq/kg giving average value of 831 ±42 Bq/kg, 238U varied from 39±2 to 3602±180Bq/kg giving average figures of 378±19Bqkg¯1and 232Th ranged from 5.000±0.300 to 4213±211Bqkg¯1 giving mean figure of 290±15Bq/kg . Calculated mean figures for activity concentration surpassed the world mean figures of 420Bq/kg, 33Bq/kg, 45Bq/kg in 40K, 238U and 232Th respectively. Absorbed dose rate calculated ranges between 73±4 and 4777±239nGyh¯1 having average value of 540±27nGyh¯1 .The mean number for the absorbed dose rate was above the world acceptable mean value of 54nGyh¯1. The calculated annual effective dose rate varied from 0.040±0.002mSvy¯1 to 2.340±0.117mSvy¯1 having average figure of 0.260±0.013mSvy¯1 ,which was above the world average of 0.070mSvy¯1but below the maximum dose constraint of 1mSvy¯1.These results show that building materials in Babadogo estate are safe and can be used for construction of buildings and thus can be continued using as further research is done on other building materials not covered in my research work.