measuring natural radioactivity of bricks used in the constructions of tehran

naturally occurring radionuclides have different amount of activity concentration for 226 ra, 232 th and 40 k in building materials. in this study, natural radioactivity has been measured for bricks used in tehran. for this work, 9 samples of three types of bricks, clay brick (cb), making the facade brick (mfb) and firebrick (fb) has been selected from different regions and factories in tehran. gamma rays analyzed by high purity germanium (hpge) detector and spectroscopy system. as the results show, the maximum value of the mean 226 ra, 232 th and 40 k for clay brick has been 17, 9 and 422bq/kg respectively. maximum of radium equivalent activities (ra eq ) were calculated 62.81bq/kg that less than the level has been determined 370bq/kg for building materials. other type of bricks had low amounts compared to clay bricks. the calculation results show that the bricks are safe for inhabitants because hazard indexes for gamma were below the standard was been introduced. the results of this research compared with other studies in different countries