Concrete Characterization Using Gamma-ray Interaction Methods

This research focused on utilizing photon interaction methods for the characterization of concrete. A Concrete composition is needed for computer simulations used to determine the effects concrete has on the gamma background detected by Radiation Portal Monitors. The goal of the project was to produce photon interaction experiments which employed common, portable equipment, thus producing inexpensive methods that could be performed for on-site characterization. Resulting in largely reduced time and cost versus other approaches. Six core-drilled concrete cylinders from three different composition concrete slabs acquired from Oak Ridge National Laboratory were used during this research. Several techniques were experimented with in attempts at finding a way to consistently discern differences in the mass attenuation coefficients. A High-Purity Germanium (HPGe) detector and GenieTM 2000 spectral analysis software were employed for obtaining and investigating the acquired spectra. All methods tested were some derivation of either a transmission or backscatter experiment. Transmission experiments utilized the photopeaks of multiple check sources and compared the original source intensity with the intensity of gammas which transmuted through the concrete samples. Whereas, the backscatter method, using a Cs137 check source, observed the increase in 184 keV photons resulting from the 180° scatter of 662 keV gammas off the concrete samples. Backscatter proved to be inconclusive in finding discrepancies between compositions and mass attenuation coefficients; however transmission observed separation between samples and was therefore simulated with Monte Carlo N-Particle (MCNP) transport code for comparison of results.