Eco-friendly BaO-enriched zinc-calcium-erbium-borate glasses as dual radiation barriers for small modular reactors

This study reports the eco-friendly BaO-enriched zinc-calcium-erbium-borate glasses with the nominal composition xBaO-(79-x)B 2 O 3 -13ZnO-7CaO-1Er 2 O 3 (x=23, 27, 31 and 35 mol% and labelled as BaE1, BaE2, BaE3, and BaE4) developed via the conventional melt-quenching method. The amorphous nature of the glasses was confirmed by X-ray diffraction (XRD) analysis. The doping of BaO composition on density, radiation attenuation and neutron moderation properties was thoroughly examined to explore its potential as a dual nuclear radiation barrier for small modular reactors (SMRs). Experimental gamma ray shielding properties were assessed in narrow beam geometry using gamma sources ( 133 Ba, 22 Na, 60 Co and 137 Cs) and a NaI(Tl) detector. The linear attenuation coefficients were experimentally determined and validated with Phy-X/PSD data, showing good agreement with a relative difference of less than 8%. The prepared glasses demonstrate superior lower HVL and MFP values at 662 keV compared to other glasses. Neutron moderation parameters, such as logarithmic energy decrement (ξ), required number of collisions (η), relative thermal lethargy (Z th ), energy transfer per collision ( E s h a r e ) and macroscopic removal cross-sections ( ∑ R ) at neutron energies of 4 MeV and 25.4 meV were also investigated. This study’s findings reveal that increasing BaO composition improves the nuclear radiation shielding capabilities. Lower BaO content glasses (BaE1 and BaE2) show better neutron moderation, while higher BaO glasses (BaE3 and BaE4) give superior gamma attenuation. The optimised composition exhibited dual radiation shielding efficiency, promoting it as a potential material for nuclear reactor systems