DNA Radiation Environments Program Spring 1991 2-meter box experiments and analyses

Abstract

This report summarizes the Spring 1991 2-m Box experiments that were performed at the Army Pulse Radiation Facility (APRF) at Aberdeen Proving Ground. These studies were sponsored by the Defense Nuclear Agency (DNA) under the Radiation Environments Program to obtain measured data for benchmarking the Adjoint Monte Carlo Code System, MASH, Version 1.0. The MASH code system was developed for the Department of Defense and NATO for calculating neutron and gamma-ray radiation fields and shielding protection factors for armored vehicles and military structures against nuclear weapon radiation. In the 2-m Box experiments, neutron and gamma-ray dose rates and reduction factors were measured in the free-field and as a function of position on an anthropomorphic phantom that was placed outside and inside a borated polyethylene lined steel-walled 2-m box. The data were acquired at a distance of 400-m from the APRF reactor. The purpose of these experiments was to measure the neutron and gamma-ray dose rates as a function of detector location on the phantom for cases when the phantom was in the free-field and inside of the box. Neutron measurements were made using a BD-100R bubble detector and gamma-ray measurements were made using thermoluminescent detectors (TLD). Calculated and measured data were compared in terms of the C/M ratio. The calculated and measured neutron and gamma-ray dose rates and reduction factors agreed on the average within the {plus_minus}20% limits mandated by DNA and demonstrate the capability of the MASH code system in reproducing measured data in nominally shielded assemblies.