In the heart of the Czech Republic, at the Research Centre Rež, a groundbreaking study led by Ondřej Libera is shedding new light on the behavior of concrete under extreme conditions. The research, recently published in ‘Acta Polytechnica CTU Proceedings’ (Acta Polytechnica CTU Proceedings), focuses on the nanomechanical properties of concrete exposed to neutron irradiation, a critical issue for the nuclear energy sector.
Concrete, a ubiquitous material in construction, is also a key component in nuclear reactors, where it provides essential shielding and structural support. However, the intense radiation environment within a reactor can significantly degrade the material’s mechanical properties over time. This degradation is primarily due to the influence of neutrons, secondary gamma rays, and associated gamma heating, which cause atomic-level damage.
Libera and his team at the Department of Material and Mechanical Properties set out to quantify this damage. They prepared concrete samples using blended Portland cement and siliceous aggregates, then subjected them to neutron irradiation in the LVR-15 research reactor. The samples were exposed to a neutron fluence of 1.6–1.8 · 1019 n cm−2 (E>0.1MeV) and a gamma dose of approximately 500 MGy, with temperatures maintained between 50–60 °C.
To assess the mechanical properties of the irradiated concrete, the researchers employed nanoindentation, a technique that allows for precise measurement of a material’s hardness and elastic modulus at the nanoscale. “Nanoindentation provides a unique window into the material’s behavior at the atomic level,” Libera explained. “By comparing the mechanical properties of irradiated and pristine concrete, we can track the evolution of damage under radiation.”
The findings reveal that neutron irradiation indeed decreases the mechanical properties of concrete, with the cementitious matrix showing significant degradation. This has profound implications for the nuclear energy sector, where the structural integrity of concrete is paramount. As Libera noted, “Understanding these changes is crucial for predicting the lifespan of nuclear facilities and ensuring their safe operation.”
The research also highlights the potential for developing more radiation-resistant concretes. By identifying the specific phases within the cementitious matrix that are most susceptible to degradation, scientists can work towards enhancing the durability of concrete in nuclear environments.
This study is a significant step forward in our understanding of concrete’s behavior under extreme conditions. As the nuclear energy sector continues to evolve, with new reactor designs and extended operational lifetimes, the insights gained from this research will be invaluable. It paves the way for future developments in radiation-resistant materials, ensuring the safety and longevity of nuclear facilities worldwide.
