Calculation of dose rate conversion factors for 238U, 232Th and 40K in concrete structures of various dimensions, with application to Nis, Serbia

Abstract

The absorbed gamma dose rate in indoor air due to natural radionuclides in concrete as a building material was determined in this work. The dose rate conversion factors for (238)U, (232)Th and (40)K, for standard rooms as well as rooms with different sets of dimensions, were evaluated by the point kernel technique, using Harima (geometric progression) build-up factors. The values of the conversion factors, in units (nGy h(-1) (Bq kg(-1))(-1)) calculated for the standard room are: 0.76, 0.91 and 0.070, respectively for (238)U, (232)Th and (40)K. The fitting formula was obtained for dose rate conversion factors, enabling them to be conveniently calculated for a room with arbitrary dimensions. For concrete block samples collected in the area of Niš, Serbia, the measurement of the radionuclide activity concentrations was also carried out. The evaluated absorbed dose rate conversion factors were then applied in the assessment of corresponding indoor gamma dose rates, finding that all the concrete samples fulfilled the usage requirement.

Radiation hazard indices in the application of phosphogypsum mixtures as a building material: proposal for a Brazilian regulation

“…The internal exposure indoors depends mainly on the activity concentration of 226 Ra and 228 Ra in the construction material and the radon exhalation rate, which can be determined by using theoretical models [8,9], measured experimentally or by employing an approach combining both modeling and experimental measurements indoors [10]. The exhalation rate is defined as the amount of activity released per unit surface area per unit time from the material.…”

The dose of gamma radiation from building materials and soil

“…The values of the conversion coeffi cients: absorbed dose (air kerma)  effective dose, E/K a (in SvGy -1 ), calculated for 238 U, 232 Th and 40 K, in the geometry of a standard room, are given in Table 3. The results were obtained assuming the equilibrium in the series, using the values of q U , q Th and q K in the standard room: 0.757, 0.910 and 0.0700 nGyh -1 / Bqkg -1 , respectively [10].…”

“…The content of 232 U, 226 Ra, 232 Th and 40 K, was previously measured in typical rocks, soil and common building materials in Serbia [4][5][6][7][8][9][10]. The results are around the averages of the worldwide ranges [1,[11][12][13].…”