Determination of natural activity in building materials by direct gamma spectrometry

Seven types of Malaysian made building materials have been analysed fur the presence of natural radionuclides (U, Th, K) using a direct gamma-counting method. The specific activities measured for radionuclides U and K were gr eater than the world average activity for soil (U: 25 Bq kg(-1) and K: 370 Bq kg(-1)). The specific activities of Th were found to exceed the world av erage value of 28 Bq kg(-1) for soil in the case of red-clay brick and ceil ing asbestos sheet materials. The calculated radium equivalent (Ra-eq) acti vities for all seven materials are higher than the world average value for soil(89 Bq kg(-1)). For red-clay brick and ceiling asbestos, the Ra-eq, val ues exceed the limit of 370 Bq kg(-1), a value equivalent to gamma-dose of 1.5 mSv per year.