Investigations on the natural radioactivity and gamma attenuation properties of building materials

Abstract

Natural radioactivity refers to the spontaneous decay of unstable atomic nuclei found in nature, primarily in radionuclides such as uranium (238U), thorium (232Th), and potassium (40K). These elements, present in the Earth’s crust, emit alpha particles, beta particles, and gamma rays, with gamma rays being the most penetrating and hazardous. Understanding natural radioactivity is vital for assessing environmental radiation levels, which vary due to geological and geographical factors. This research evaluates potential radiological hazards, ensuring safety in human habitation and related activities. Radiogenic heat, generated by the natural decay of radioactive isotopes, significantly influences the Earth’s thermal field. Long-lived radionuclides contribute to heat production, impacting crustal temperature distribution and the lithosphere’s mechanical strength. Understanding this heat generation is essential for studies on Earth’s structure. Gamma rays, a high-energy form of electromagnetic radiation, pose health risks such as DNA damage and cancer due to their deep penetration capabilities. Effective gamma ray shielding is critical and involves materials like lead, concrete, and high-density composites. Recent advancements focus on developing innovative materials that combine superior radiation protection with desirable mechanical properties. The objectives of this thesis are: (1) measuring natural radioactivity in rock and soil samples, analysing radiogenic heat production, and evaluating radiological parameters; (2) developing optimized gamma ray shielding materials with cost-effective and durable properties, focusing on epoxy-based coatings; and (3) using numerical simulations to predict gamma attenuation properties and validating these through experiments. This thesis, structured into seven chapters,begins with an overview of natural radioactivity and radiation shielding materials. It reviews existing literature, details experimental methodologies, and explains the theoretical framework. The results highlight measurements in unexplored regions of Kerala, India, contributing to global radiation mapping efforts. Additionally, the study advances gamma ray shielding technologies with potential applications in medical, nuclear, and industrial fields. The findings ensure safety and provide insights for future research and practical applications.