Georadiological Barrier Gamma Attenuation Model for Waste Containment. I: Model Formulation

摘要

Emission of gamma rays from buried and exposed radioactive materials poses health risks at radiologically contaminated sites. Covering the source material with a barrier of adequate thickness and physicochemical composition can reduce the intensity of transmitted gamma rays (__-y), thereby reducing such risks. Herein, the Geo-Radiological Barrier Gamma Attenuation Model (GRBGAM) is developed to quantify __-y attenuation by earthen covers. The model allows variation of barrier and radioactive source input parameters and comparison of emitted y intensities and attenuation ratios of different barrier designs for virtually any radioactive isotope decay chain. The model calculates the activities of successive amounts of decaying isotopes within a decay chain and temporally couples the results with an exponential absorption equation to estimate the exit intensity of y radiation from barriers. A Weibull function integrated into the absorption equation, scales temporal changes in barrier density (p')-during long service times. This model can be used to optimize georadiological (georad) barrier mix composition and thickness to increase y attenuation ratio to acceptable levels.