Natural radionuclides in building materials available in Israel

Most building materials contain naturally occuring 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 ²³²Th and radium ²²⁶Ra. 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 ²²⁶Ra increases the concentration of radon gas ²²²Rn and of its daughters in the house. Concentrations of natural radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K) 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.