Thermophysical characterization of building materials due to radioactive decay

This study aims to provide a thermophysical characterization of crushed stone, sand, brick, and cement due to radioactive decay. The 28 sand samples, 23 cement samples, 30 crushed stone samples, and 29 brick samples were analyzed by X-Ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) to screen samples for the presence of uranium, potassium, and thorium. HPGe gamma spectrometers were applied to determine the activity concentrations of 226 Ra, 40 K, and 232 Th in Bq kg −1 , which were subsequently converted to ppm for radiogenic heat calculations. For the samples, 226 Ra ranges from 0.68 ± 0.04–21.7 ± 0.47 ppm, 40 K ranges from 428 ± 92–37172 ± 1651 ppm, and 232 Th ranges from 0.86 ± 0.11–171 ± 0.24 ppm. 21 sand samples, 19 cement samples, 29 crushed stone and stone dust samples, and 13 brick samples presented activity concentration values above the world average for 226 Ra, 232 Th, and/or 40 K. The average annual effective dose value of 0.95 ± 0.02 mSv y −1 exceeds the exemption limit of 0.3 mSv y −1 for the public and is below the dose limit of 1 mSv y −1 established by the ICRP 103. The I∼H∼ varied from 6.27 × 10 −4 to 0.34, and the radiogenic heat production rate across the analyzed materials varied from 0.04 to 0.88 μW m −3 , exceeding the average value of 0.5 μW m −3 observed by [1] . The temperature generated (T trmc ) due to the radioactive decay of these materials in use in a standard room in a house was 7.54 × 10 −5 °C. The thermal power generated in the wall, the heat generation produced by the consumed mass, the linear power density, and the heat flux that passes through the wall surface from these materials were 3.65 μW, 1.98 nW kg −1 , 0.46 µW m −1 , and 0.23 µW m −2 , respectively. The primary chemical components in the samples are SiO 2 , Fe 2 O 3 , K 2 O, and Al 2 O 3 . The findings from this research will be useful to assess the radiation hazards posed by building materials to building occupants.