Development of neutron-proof ultra-high-performance concrete

The increasing demand for high-performance radiation shielding materials in nuclear infrastructure, medical facilities, and industrial radiography applications has intensified interest in advanced radiation shielding concrete. Herein, we present the development of a novel, sustainable, Neutron-Proof Radiation Shielding Ultra-High-Performance Concrete (NP-RS-UHPC) by harnessing the separate and synergistic effects of silica sand, magnetite, and ferroboron on neutron shielding performance. NP-RS-UHPCs were designed by coupling particle packing and response optimizations to achieve optimum flowability, density, compressive strength, and neutron shielding performance. NP-RS-UHPCs with up to 50 % improvement in fast-neutron removal cross-section were developed. Ferroboron-rich NP-RS-UHPCs exhibited thermal-neutron absorption cross-sections exceeding 3000 % of those in magnetite- and silica-sand-only systems while distinctly manifesting what we define as the Neutron Absorption Saturation Threshold ( NAST ), which marks a characteristic material thickness where nearly all absorbable thermal neutrons are captured. A bivariate exponential decay model was developed to predict thermal-neutron transmission in Ferroboron-rich NP-RS-UHPC. Results confirmed NP-RS-UHPC’s potential to deliver both improved mechanical performance and multi-spectrum radiation shielding efficiency, demonstrating its suitability for neutron-rich environments including small modular reactors.