Neutron protection factor determination and validation for a vehicle surrogate using a Californium fission source

Abstract

This thesis describes the work completed to determine and validate the neutron protection factor (NPF) of an armored vehicle surrogate using the Lawrence Livermore National Laboratory's (LLNL) Cf-252 Radiation Calibration Laboratory (RCL). The NPF, a component of the total radiation protection factor (RPF), is used to evaluate the inherent shielding and radiation protection of military personnel from a polyenergetic neutron source. When the NPF is properly combined with the Gamma Protection Factor (GPF), which characterizes the effect of an associated gamma environment, the resultant RPF provides essential information of the total radiation protection afforded by a vehicle or structure to personnel within. To increase personnel survivability, the Navy, Army and Defense Threat Reduction Agency (DTRA) are interested in NPFs for applications involving forward-deployed vehicles or vessels in environments where neutron radiation is present. Such radiation environments can be the result from the detonation of a nuclear weapon or radiological dispersal device, or the conditions following a non-weapon radiation accident calling for humanitarian or disaster-relief missions. NPFs are focused only on the neutron radiation environment and exclude other nuclear weapon effects, such as the thermal destruction zone or firestorms created by nuclear weapons. The results from the fluence measurements at LLNL's Calibration Facility were used to validate computational models, namely the MCNP-6 Monte Carlo code. Through validation, DTRA, the Navy, and the other military services can use computational codes for determining NPFs for a diverse fleet of military vehicles.