Plastic materials as a radiation shield for beta- sources: a comparative study through Monte Carlo calculation.

We have developed a Monte Carlo simulation in Geant4 to compare the attenuation properties and the bremsstrahlung radiation yield of different types of plastic materials employed as shields for beta- radioactive sources. Code validation results against Sandia and NIST data are presented. For polypropylene (C3H6), polystyrene (C2H3), polyamide nylon-6 (C6H11ON), poly-methyl methacrylate (C5H8O2), polycarbonate (C16H6O3), polyethylene terephthalate (C10H8O4), polyvinyl chloride (C2H3Cl) and polytetrafluoroethylene (C2F4) we evaluated the mean and maximum ranges for electrons originating from 90Sr and 90Y, as well as the number and spectrum of the bremsstrahlung x-rays produced. Significant differences appear between the various materials, and the choice of the best one also depends on the physical properties requested for each specific application.