Study of radiation shielding efficacy of polyethylene and polyethylene-based composite against galactic cosmic rays and secondary neutrons

Abstract

Polyethylene and polyethylene-based composites increasingly draw researchers’ attention in space exploration applications because of their unique characteristics such as lightweight and radiation shielding. This study focuses on the space radiation shielding of polyethylene and polyethylene fiber reinforced polyethylene matrix composites for applications such as long duration human exploration beyond the low Earth orbit (LEO) to minimize crew and equipment exposure to the interplanetary radiation environment. Polyethylene-based composites with fiber reinforcements including ultra-high molecular weight polyethylene (UHMWPE) fibers are developed and their radiation shielding efficacy is evaluated. Specialized coating methods and incorporation of the coated substrate in the composite for shielding against secondary neutrons are presented. Results from the physics-based Particle and Heavy Ion Transport Code System (PHITS) are used to estimate the efficacy of the composite materials for shielding against Galactic Cosmic Rays (GCR). Simulation results for secondary neutrons in the energy range of thermal to 10 GeV is also discussed. Secondary neutron test results are obtained using a PuBe source in the energy range of 1 – 10 MeV. The radiation shielding results of the thermoplastic composite show its great potential for safe long duration human exploration beyond LEO.