Natural radioactivity in bricks used in Sri Lanka

The objective of the present study was to determine the specific radioactivity concentrations of Ra sup 226, Th sup 232 and K sup 40 in brick samples collected from different areas and compare with the corresponding results for bricks of different countries.Sixteen clay and four cement brick samples were collected from kilns in different areas in Sri Lanka. The gamma ray spectra of the prepared samples were measured using a typical high resolution gamma spectrometer based on a shielded HpGe detector.The spectrometer was calibrated for energy and efficiency over the experimental energy range 186-2700 keV using IAEA reference material RGU-1, RGTH-1 and RGK-1.GANAAS software was used to analyse the photopeaks. The measured average specific radioactivity concentrations of Ra sup 226, Th sup 232, K sup 40 in the clay bricks were 35, 69 and 604 Bq per kg respectively. For cement bricks these values were 17, 42, 525 Bq per kg. The corresponding world average values are 50,50 and 500 Bq per kg for the said radionuclides.All three radionuclides were greater than the world average in clay bricks measured from Mahiyangana. Clay bricks from Ampitiya, Anuradhapura and Nikaweratiya measured values are less than the world average for all three radionuclides. Data on concentrations of natural radionuclides can be used to determine dose rates in relation to building materials