Abstract
Targeting the development of advanced lightweight thermal and ballistic neutrons shields, a new hybrid composite was developed, for the first time, from Kevlar fibers, epoxy and boron carbide (B4C) particles. Kevlar fibers, as one of the strongest polymeric fillers, possess a high proportion of low Z atoms highly suitable for moderating neutrons. Meanwhile, these fibers can provide an additional efficient protection against high velocity projectiles. The B4C particles were added in various amounts, mainly for their excellent absorption of thermal neutrons. The nuclear shielding tests were performed at NUR research reactor using an optimized experimental setup. The obtained results confirmed the high shielding efficiency of all the developed materials. Meanwhile, the best performance was recorded at B4C amount of 20 wt.% with a macroscopic cross-section (Σ) of with a 3.638 cm−1 equivalent to a mean free path (λ) of 0.191 cm. The obtained results were compared with the most performant available shields and the data confirmed that superiority of the developed materials.
Highlights
Neutrons, as the most penetrating particles, have found applications in many sectors nuclear including but not limited to nuclear power plants, medical hospitals, radiography and aerospace
Before assessing the neutron shielding efficiency of the Kevlar/Epoxy/B4C hybrids, the number of neutrons passing through a thin Cadmium layer (0.5 mm) was counted
From the obtained results the neat Kevlar fibers showed remarkable shielding performances with a screening ratio of about 40% for a 12 mm thick sample. This is attributed to the atomic composition of these fibers containing a large proportion of low Z atoms, especially hydrogens which are well-known for their high interaction with neutrons of various energies
Summary
As the most penetrating particles, have found applications in many sectors nuclear including but not limited to nuclear power plants, medical hospitals, radiography and aerospace. Among low Z materials, polymeric fibers have gained a lot of attention in the field of nuclear shielding due to their exceptional lightweight and ease of transformation into various shapes Among these remarkable fillers, Ultra High Molecular Weight (UHMWPE) fibers have been proven to provide outstanding neutrons screening performances for various energies. Kevlar fibers start to decompose at temperatures in excess of 400°C and their atomic composition is somehow close to that of the UHMWPE fibers [11,12,13] It came to our attention the study of the neutrons shielding properties of Kevlar based materials. Another objective is to develop, for the first time ever, a dual ballistic and nuclear protection designed for soldiers and personnel working in contact of theses radiations. Where I0 refers to the initial neutron beam flux, I represents the neutron beam flux transmitted through a thickness x (cm) of the sample, Σ is the total neutron attenuation coefficient
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