Assessment of natural radiactivity from building materials in Spain

Abstract

The industrial construction sector is very important in Spain. Building materials used in this industry are sources of radiation from natural radionuclides they contain. The aim of this work is to measure the natural radioactivity in building materials. The relevance of the contribution of natural radiation that they generate implies their analysis taking into account the limitations imposed by national and international regulations and legislations. The studies about this subject have increased notably during last years. This, probably, can be associated with the increase interest from natural radiation radiological risk on indoor exposure. Radioactivity of some building materials could be increase, during the manufacturing processes, as results of the addition of NORM products to improve their properties.

All building materials have varying amounts of natural radionuclides. They belong to natural radionuclides of uranium (238U) and thorium (232Th) series, together with the radioactive isotope of potassium (40K). The concentration of the natural radioactivity in the selected cements and ceramics were conducted with a coaxial ReGe detector. The energy an absolute efficiency calibration of the spectrometer was made using a sample certificated by IAEA-312 and IAEA-385. Software use to analyze the spectrum is the Cenie-2000 v.2.0 Canberra Nuclear. The activity concentrations from 226Ra, 232Th and 40K respectively from samples of Portland cements, tiles, ceramic and natural stones were determined.

To compare the radiological effects of the materials used in the building which contain 226Ra, 232Th and 40K, a common index is required to obtain the sum of activities and according to RP 112 the absorbed dose in air can be calculated. Some indices dealing with the assessment of the excess gamma radiation arising from building materials such as Radium Equivalent Activity (Raeq); External Hazard Index (Hex),;the Activity Concentration Index(I); Absorbed Gamma Dose Rate in indoor air (D); and Annual Effective Dose Equivalent (AEDE).

In this paper 150 samples from granitic, calcareous, sedimentary zones of Spain have been evaluated

Concentration of natural radionuclides (226Ra, 232Th and 40K) are in usual range (except few exceptions) and below maximal permitted values, so that examined materials could be used for construction of new buildings (for interior and external works) as well as for covering of pavements, floors, etc.