GAMMA-RAY ACTIVITY AND DOSE-RATE OF BRICK SAMPLES FROM SOME AREAS OF NORTH-WEST FRONTIER PROVINCE (NWFP), PAKISTAN

It is important to measure natural radioactivity due to gamma-rays fro m building materials and consequently to determine the dose rate from these materials. This helps to implement precautionary measures whenev er the dose rate is found to be above the recommended limits. A knowle dge of gamma radioactivity is required by the building construction as sociation to adopt preventive measures to mitigate or minimize the har mful effects of ionizing radiation. The aim of this work was to measur e the gamma activity due to Ra-226, Th-232 and K-40 in bricks from the Peshawar, Nowshera and Mardan districts of NWFP of Pakistan. The radi ological doses to the occupants from the brick floor of a wooden house were calculated. The average gamma dose equivalent rate was calculate d to be 0.14 mSv per year, which is well below the external gamma dose limit of 0.46 mSv per year as given in UNSCEAR [2].