Novel metallic Bi-Pb–Cd-Ag alloys for shielding against neutrons and gamma rays
A. M. Reda, A.A. El-Daly
Abstract
Abstract Obtaining high-performance shielding alloys against mixed neutrons and γ -rays is vital in the field of nuclear radiation. In this work, shielding Bi-Pb–Cd-Ag alloys with superior thermal neutron shielding and high ability to attenuate γ -rays were developed. The microstructure, melting behavior, and mechanical properties of the prepared alloys were characterized. The γ -rays mass attenuation coefficients ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> <mml:mo>/</mml:mo> <mml:mi>ρ</mml:mi> </mml:math> ) were obtained using WinXCom program in the energy range of 0.015–15 MeV. The shielding parameters including atomic and electronic cross-sections ( σ a and σ e ), effective atomic number ( Z eff ), effective electron density ( N eff ) were calculated. The exposure buildup factor (EBF) using a geometric progression (GP) fitting method was estimated. The experimental measurements were carried out at 662 and 1173, 1332 keV of 137 Cs and 60 Co isotope sources, respectively using a scintillation gamma spectrometer NaI(Tl) detector. The calculated results of WinXCom are consistent and in agreement with the experimental values of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> <mml:mo>/</mml:mo> <mml:mi>ρ</mml:mi> <mml:mo>.</mml:mo> </mml:math> The macroscopic effective removal cross-section ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:msup> <mml:mo>∑</mml:mo> <mml:mspace width="-0.3em"/> </mml:msup> </mml:mrow> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) of the samples for fast neutrons were calculated. Also, the attenuation of thermal neutrons through the prepared alloys has been investigated. It was found that the alloy containing 30% Cd complies with the compromise between superior thermal neutron attenuation besides its superior ability to attenuate γ -rays with good mechanical strength and high ductility.