Development and evaluation of PU@PbO/B4C composite for gamma and neutron radiation shielding

In the current study, we investigate the performance of polyurethane foam loaded with an equal combination of boron carbide (B₄C) and lead oxide (PbO) to develop a dual functional polymer composite for radiation shielding applications. The fabricated composite was investigated using a customized gamma setup with a ¹³⁷Cs gamma source, and the results were validated through Monte Carlo-based simulations employing MCNP6 and GEANT4 codes. In addition, the samples were examined using a designed neutron setup to evaluate their thermal neutron and secondary gamma attenuation properties. The secondary gamma rays, originating from the Am-Be neutron spectrum (up to approximately 4.4 MeV), were modeled using the MCNP6 code. Both gamma and neutron setups showed consistent results regarding the radiation attenuation ability of the polyurethane@B₄C/PbO composite. In the gamma experiments, adding only 0.5% of each filler increased the linear attenuation by more than 30%, and increasing the filler concentration up to 5% raised this improvement to over 80%. Similarly, the half-value layer decreased from 5.5 cm for pure polyurethane to 2.25 cm for the composite with 5% filler concentration, representing a 60% reduction. In the simulated neutron setup, the linear attenuation coefficient of neutron increased by 20% with 5% filler, and the mean free path decreased 17%. Meanwhile, the linear attenuation coefficient of secondary gamma increased by 30% (from 0.15 to 0.195), and the mean free path decreased by approximately 23%. Overall, both simulation and experiment results demonstrated promising neutron and gamma attenuation, confirming the potential of the PbO/B₄C-PU composite as a dual-purpose shielding material for both gamma and neutron protection in various applications.