Nuclear shielding characteristics of newly developed composite metal foams: Role of CeO2 addition and foam type

Abstract

In present study, new composite materials which were produced by filling open-cell aluminum foams of different thickness and pore size with various additives were surveyed with respect to photon and fast neutron shielding effectiveness. The metal foam samples were prepared in two different series (A: 30 mm thick with a pore size of 2 pores/cm and B: 10 mm thick with a pore size of 16 pores/cm) according to thickness and pore sizes, and the foams were filled with different mixtures which include Epoxy(60)-B2O3(20)-CaO(20-x)-CeO2(x); (x; 0, 5, 10, 15 and 20 wt%) chemical compositions. Gamma, X-ray and neutron measurements of the produced samples were performed using Ultra-Ge detector, linear accelerator (LINAC) and BF3 neutron detector, respectively. The gamma-transmission measurements were achieved for 30.9, 59.54, 75, 81, 276, 303, 356, 384, and 662 keV photon energies using radioactive sources of 241Am, 137Cs, 133Ba. Linear Attenuation Coefficients (LAC) of the samples were figured out with the data acquired from the measurements and MAC, HVL, Zeff and Ne values were found by way of these values. The MAC, Zeff and Ne values of the samples increased with the rising in the percentage of CeO2 added to the mixture. The energy absorption (EABF) buildup factors of the composite metal foam samples were also determined for the energy range of 0.015–15 MeV at 1–40 mfp penetration depths. It was found that the A5 and B5 samples with 20% CeO2 additive had the least EABF values. Lastly, the shielding capability of the fabricated samples against fast neutrons was specified by executing equivalent dose measurements (EAD) and calculated macroscopic cross section (∑R) values. It was established that the A2 sample had the highest absorption dose rate of 49%. The largest of the theoretically calculated ∑R values belongs to the B5 sample with 20% CeO2 additive. Generally, it was concluded that the samples in the B series, which are thinner and have more pores, have better radiation attenuation capabilities.