Energy demands have led many countries to expand their use of nuclear power, making the development of effective radiation shielding materials more important than ever. Recent research revealed significant advancements in the design of heavy-density mortars aimed at mitigating radiation from nuclear facilities. This study, published by researchers from the University of Jordan, introduces a novel approach to enhancing the efficiency of mortar through the co-incorporation of lead and boron compounds, along with calcium chloride.
The primary focus of this study was to create mortars fortified with inorganic additives capable of effectively attenuating various types of nuclear radiation, particularly gamma rays and fast neutrons. Traditional methods of radiation shielding frequently employ heavy metals, with lead being the standard due to its high density and effectiveness. The innovative advantage presented by this new research lies in the combination of lead oxide (PbO), borax decahydrate (Na2B4O7·10H2O), and calcium chloride (CaCl2) to improve binding, hydration kinetics, and overall performance against radiation.
The study initially characterized the effects of lead oxide and boron on hydration kinetics, showing how these additives influence setting times and compressive strengths. The results indicated optimal compositions, with the ideal proportions found to be 1.5% lead oxide and 0.5% boron, both enhanced by the presence of calcium chloride. This blend significantly improved the mechanical properties and shielding effectiveness of the mortar.
Testing involved evaluating various physical properties over extended curing periods—7, 28, 56, and 90 days—and measuring radiation parameters, including the effective removal cross-section for different isotopes. The incorporation of calcium chloride not only accelerated hydration processes but also facilitated the retention of lead within the matrix, reducing leaching risks. "The inclusion of calcium chloride provides significant enhancement to the hydration reaction, promoting higher strength values across all curing periods," stated the authors of the article.
Compressive strength tests showed progressive improvements over time, with the calcium chloride-blended mortars outperforming their lead or boron-free counterparts at all intervals. Remarkably, these new formulations did not just meet but exceeded performance expectations for radiation attenuation, with the lead oxide-boron mix demonstrating superior protective qualities when exposed to gamma radiation emitted from isotopes like cesium-137 and cobalt-51.
Results from the attenuation studies revealed the linear attenuation coefficients increased consistently with the inclusion of PbO. The mixture containing both lead oxide and calcium chloride reportedly achieved the best results, showing up to 1.41 times higher attenuation capability compared to control mixes without chemical additives. "Results indicate the co-incorporation of lead oxide and boron compounds yield superior shielding against gamma rays and fast neutrons," underline the researchers. This enhanced performance is largely attributed to the mortar's increased density.
The incorporation of boron is particularly noteworthy. Its high neutron-capture cross-section makes it exceptionally effective at moderanging fast neutrons, producing lower half-value and tenth-value layer metrics. These findings suggest the blend of borax not only contributes to radiation shielding but also plays a role in managing hydration properties, which, when balanced with calcium chloride, leads to more rapid setting and recovery of strength without significant delays.
Through these findings, the authors provide compelling evidence supporting the implementation of this novel mortar formulation as an industry standard for radiation shielding. Given the increasing reliance on nuclear power for energy production globally, advancements such as these are pivotal, ensuring safety and efficacy within radiation-prone environments.
Future research may explore varying the percentages of boron and lead compounds to hone the balance between strength, setting time, and radiation shielding efficacy even more. Collaborations with industries focused on nuclear construction might pave the way for practical applications of this innovative mortar, enhancing safety regulations and standards.