Neutron shielding concrete incorporating B4C and PVA fibers exposed to high temperatures

Abstract

Traditionally, concrete has been used in radiotherapy rooms, in nuclear fuel containers, in nuclear power plant foundations and other structures using large thicknesses to shield the radiation. Currently, the development of concrete technology allows us to produce cement-based composite materials incorporating fibers, improving mechanical properties, additives and additions, increasing certain properties such as the shielding against ionizing radiation. This paper explores the possibility of building protective walls using different specialized concrete skins, which protect against neutron radiation generated by nuclear fuels. The paper validates a lightweight neutron protection concrete for high and low activity containers considering the worst conditions of use. It has been proven that the mechanical properties, durability and behavior under fast increases of temperature are suitable for purpose. The studied concrete incorporates natural limestone aggregate, polyvinyl alcohol fibers and boron carbide as a neutron absorber. After exposure to thermal gradients of 100 °C, 300 °C, 500 °C, 700 °C and 1000 °C, the concrete is characterized by its residual physical and mechanical properties and its microstructural topography. Results show a reduction in mechanical properties, a decrease in the continuity of the material detected by ultrasonic impulse propagation and an increase in the presence of voids in the microstructure.