A Monte Carlo Study on the Shielding Properties of a Novel Polyvinyl Alcohol (PVA)/WO3 Composite, Against Gamma Rays, Using the MCNPX Code

J Biomed Phys Eng. 2019 Aug 1;9(4):465-472. doi: 10.31661/jbpe.v0i0.1114. eCollection 2019 Aug.


Background: In recent years, there has been an increased interest toward non-lead radiation shields consisting of small-sized filler particles doped into polymer matrices. In this paper, we study a new polyvinyl alcohol (PVA)/WO3 composite in the presence of high-energy gamma photons through simulation via the Monte Carlo N-Particle (MCNP) simulation code.

Material and methods: An MCNP geometry was first designed in the software based on real-life conditions, and the generated geometry was validated by calculating the mass attenuation coefficient and making relative comparisons with standard tables. Using the lattice card in the MCNP input file, WO3 was considered as a filler dispersed in a PVA polymer at sizes of 10 µm and 30 nm with a weight concentration of 50 wt%. By defining 106-photons emitted from point sources corresponding to 662, 778, 964, 1112, 1170, 1130 and 1407 keV energy levels, and the F4 tally used to estimate the cell average flux, the values for mass attenuation coefficient and half-value layer (HVL) were calculated.

Results: The results show that PVA/WO3 composite can be considered to shield X and γ-rays in the mentioned energies. However, nano-WO3 has a better ability to shield in comparison with the micro-WO3 fillers. The differences in attenuation changed at different energy levels, ascribed to the dominance of pair production occurrence and photon interactions in the composite, which was in good agreement with previous studies.

Conclusion: Our finding showed that the composite can be considered as a lead-free shielding material.

Keywords: Gamma Rays; MCNP Code; Monte Carlo Method; Polyvinyl Alcohol (PVA); Radiation Protection; Tungsten Trioxide (WO3).