Natural radionuclides in building materials available in Israel

Most building materials contain naturally occurring radioactive elements, the most important of which are potassium 40K and the members of two natural radioactive series, which can be represented by the isotopes of thorium Th-232 and radium Ra-226. The presence of these radioisotopes in the materials causes external exposure to the people who live in the building. In addition, the disintegration of radium Ra-226 increases the concentration of radon gas Rn-222 and of its daughters in the house. Concentrations of natural radionuclides (Ra-226, Th-232, K-40) in the samples of building products, building binders, in lightweight aggregates, normal-weight aggregates and in industrial by-products used in the construction industry in Israel were determined by a gamma-ray spectrometer with a Ge-detector. A methodology was introduced to regulate the use of building materials that causes an increase in indoor radiation exposure. The results indicate that a radium equivalent varies within the range of 158.8-18.8 Bq/kg in the samples of building products, 74.3-17.5 Bq/kg in the samples of building binders, 164.5 - 17.7 Bq/kg in the samples of aggregates, and 761.4-241.6 Bq/kg in the samples of industrial by-products used in construction. (C) 2002 Elsevier Science Ltd. All rights reserved.