Use of Stochastic Geometry in MCNP Model of Novel Heterogeneous Radiation Shielding Material

摘要

This paper describes our efforts to accurately characterize the performance of a novel radiation shielding material using MCNP5. [1] The large hydrogen and carbon content of tire rubber (principally C_5H_8 and C_4H_6) makes it ideally suited to downscatter neutrons over a broad range of energies. The attenuation of gamma photons is most readily accomplished with high-Z metals such as lead or bismuth. Moreover, lead possesses a substantial inelastic scattering cross-section for neutrons with energies above 1 MeV. These two materials can be combined into heavy-metal coated rubber granules which can then be readily dispersed homogeneously into a concrete binder. [2] In 2007 (the last year for which data is available), 303,200,000 scrap tires were generated in the US. Of these, roughly 13% end up in landfills. [3] The remainder are recycled into a variety of products, including finely ground "crumb" rubber particles. Crumb rubber is available in a wide variety of particle sizes, and is commercially available in large quantities at low cost.