Simplified Methods for Calculating the Penetration of Neutron and gamma Radiation into Underground Concrete Structures

摘要

The analysis of two experiments performed at the Oak Ridge National Laboratory's Tower Shielding Facility provides a basis for the development and evaluation of simplified methods for predicting the prompt weapons radiation intensities inside underground concrete structures. Using the TSR-II in a special shield to simulate a nuclear weapon radiation environment, one experiment mapped the radiation inside two concrete bunkers with an interconnecting tunnel located in a hillside approximately 700 feet from the source. The other experiment mapped the radiation in concrete-lined cylindrical holes at distances of 100, 228 and 450 feet from the reactor. In both experiments the openings of the underground structures were shielded with various thicknesses of concrete. Albedo methods were developed for calculating neutron and gamma-ray reflection from the concrete walls of the structures and for calculating gamma dose rates due to thermal neutrons captured in the walls. Penetration calculation methods which consider the energy and angular distributions of the incident and emergent radiations were also developed.