Assessment of Natural Radioactivity Levels and Potential Radiological Risks of Radioactive Tailings and Common Building Materials in Hunan Dwellings.

Abstract

Objective: The purpose of this study is to determine the radiation hazards of building materials to humans through multivariate statistical analysis based on these radioactive nuclides and parameters.

Design: An experimental study was conducted by collecting materials from different parts of Hunan and using experimental analysis and statistical calculation methods to determine the degree of harm that materials pose to humans.

Results: Among all the sample materials, the brick samples made from soil without a pollution background have the lowest activity concentration values of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K, which are far below the average level in Hunan. The radiological hazards are calculated as the external and internal hazard indices (H_ex, H_in), alpha index (I_α), gamma index (I_γ), and indoor and outdoor annual effective dose, all of which are much less than 1. The value of Ra_eq is well below the prescribed safe limit of 370 Bq/kg, indicating no radiological hazards to the population from the samples. (II) Through pilot experiments, it has been found that the radioactive content of bricks made by mixing associated slag with local background soil should be considered based on the proportion of the mixture, especially the radioactive level before the associated slag. To a certain extent, it is of great significance for the impact or magnitude of safety hazards in later judgment. (III) This study revealed that there is radioactive equilibrium between ²³⁸U and ²²⁶Ra, and between ²³⁸U and ²³²Th, and that a functional relationship was observed. At the same time, it is noted that a strong correlation was found between ²³⁸U and ²²⁶Ra, and between ²³⁸U and ²³²Th, indicating a good positive correlation. The radiological parameters of the bricks made from the natural background in soil are the smallest; the products of naturally occurring radioactive materials are the highest. This is due to the issue of proportion between the natural soil and tailings.

Conclusions: The results have shown that the proportion of mixture in the natural soil and tailings must be reasonable in building materials. Therefore, the results of this study will help evaluate the radiation hazards of building materials to humans and the environment.