Simulation of Cosmic Radiation Transport Inside Aircraft for Safety Applications

Abstract

During the flight, an aircraft is submitted to a radiation environment composed of cosmic-ray-induced particles (CRIP) of which neutrons are responsible for approximately 40% of the crew effective dose and are the main cause of Single Event Effects (SEE) in avionics systems at flight altitudes. A model of Learjet aircraft was developed on Monte Carlo simulation using the MCNPX code in order to detail the CRIP field inside the aircraft. The radiation source modeling was previously developed by a computational platform that simulates the energy and angular distributions of the CRIP along the atmosphere. In this work, we determined the variation of the neutron radiation field in several positions inside the aircraft at 11km and 18 km altitudes and for both equatorial and polar regions. The results suggest that the maximum variation of neutron fluence rate between different positions inside the aircraft shows a tendency of higher differences for a lower energy threshold (thermal and E > 1 MeV) in comparison with those differences for a higher energy threshold (E > 10 MeV). Moreover, the angular distribution results show relevant differences between positions inside aircraft, mainly for thermal neutrons close to the fuel. The general tendency is to enhance these discrepancies for devices with new technologies, due to their lower energy threshold for SEE occurrences.

Comparative Analysis of the Aeronautical Certification Process Against Nonionizing Radiation and the Management Proposal for Ionizing Radiation

“…Part of SEE steps (3) and ( 4) are somewhat related to step (3) of the HIRF/L process, which finds its equivalence in the SEE process in determining the aircraft's internal radiation profile, taking into account geometric factors and shields. An interesting dissertation on that subject, although limited to neutrons, can be found in Prado (2020).…”