Measurement of natural radioactivity in building materials of Namakkal, Tamil Nadu, India using gamma-ray spectrometry

The natural level of radioactivity in building materials is one of the major causes of external exposure to γ-rays. The primordial radionuclides in building materials are one of the sources of radiation hazard in dwellings made of these materials. By the determination of the radioactivity level in building materials, the indoor radiological hazard to human health can be assessed. This is an important precautionary measure whenever the dose rate is found to be above the recommended limits. The aim of this work was to measure the specific activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in commonly used building materials from Namakkal, Tamil Nadu, India, using gamma-ray spectrometer. The radiation hazard due to the total natural radioactivity in the studied building materials was estimated by different approaches. The concentrations of the natural radionuclides and the radium equivalent activity in studied samples were compared with the corresponding results of different countries. From the analysis, it is found that these materials may be safely used as construction materials and do not pose significant radiation hazards.     

The radon emanation power of building materials, soils and rocks

The ²²²Rn emanation power of building materials, soil and rock samples is determined by collecting exhalated radon on activated charcoal. Median values are 0.2 for dry soils and stones, 0.06 for sand, 0.025 for bricks, 0.006 for ceramic tiles, 0.008 for mineral slag and 0.3 for gypsum. The emanation power of soil rises with water content, in accordance with literature. For water content above 10% the emanation power of soil is about twice as high as for dry soil.     

建筑材料样品中放射性核素γ能谱测量比对

目的 通过全国省级疾病预防控制中心γ能谱实验室对建筑材料中放射性核素的测量比对,检验其测量结果的精确度和准确度,提高其对放射性核素的分析水平。方法 依据IAEA 2002年放射性核素国际比对方法,于2007年组织了15个单位对我国建筑材料样品中放射性核素γ能谱测量比对。结果 各参加比对单位提供的测量值与参考值符和较好,其中有50%的参加单位相对偏差小于5%,相对偏差小于10%的单位超过80%。结论 γ能谱分析建筑材料样品中放射性核素含量的方法是准确可靠的,可以满足GB 6566-2001《建筑材料放射性核素限量》标准的要求。     

Uncertainty of gamma-ray spectrometry measurement of environmental samples due to uncertainties in matrix composition,density and sample geometry

This paper is intended to identify the uncertainties of activities in environmental samples measured with gamma-ray spectrometry that result from uncertainties in matrix composition, density and geometrical dimensions of the sample. For that purpose efficiencies were calculated for a wide range of environmental matrices such as fresh and ashed food samples, water samples and soil samples. Compositions were mainly taken from literature. Densities and geometry parameters were varied in a range occurring in practice. Considered energies cover a range from 46.5 keV to 2000 keV. Finally, a couple of recommendations in respect to gamma-ray spectrometric measurements of environmental samples are given.