Radiation attenuation by porous media containing spherical glasses

In this thesis, gamma radiation attenuation properties of a porous medium that includes spherical glasses were investigated by using the gamma transmission technique. Spherical glasses have various diameters such as 10, 5 and 1 mm. Porous media were obtained from spherical glasses inserted in a container at different models as regular, dispersed and mixed forms. Gamma transmission method based on a gamma radiation emitting from source of photons can pass through the material with the penetrated material to be inspected which is obtained by comparing the radiation data. The gamma-ray transmission method is used for the study of porous media properties. The porosity and linear attenuation coefficient are measured by using gamma attenuation data. Porous media is encountered in everyday life, in technology, and in nature. Examples of porous materials in daily life are sand, soil, ceramic, lungs as well as bread. The application fields of porous media are automotive, ship building, construction, air and space industries, as well as manufacture of insulation materials, and filters. There are many examples where porous media play important roles in technology and, conversely, many different types of technology that depend on or make use of porous media. Porous media can be used for shielding of radiation since they are lightweight and cost-efficient materials. Aim of this study is to examine the radiation attenuation properties of the porous media which includes spherical glasses and to search the ability of shielding of materials. Also, it is aimed that the porosity distributions of these materials are determined. The basis of this master's thesis is the investigation of structures of various porous media by using gamma transmission technique. The experimental works were performed on the existing narrow beam geometry in ITU Energy Institute 60 Co gamma-ray source and gamma permeability apparatus are used. The gamma transmission measurements were carried out with dry porous materials which include spherical glasses inserted into the Plexiglas container. In another part of the experiments, the porosity of the porous media with spherical glasses was determined. For this reason, all porous materials were saturated by water and gamma transmissions from saturated materials were measured in the same experimental conditions. In all of the experiments, the measurements were performed for eight points of the container which includes spherical glasses. It was formed seven porous medium models with spherical glasses in this study. Through the use of radiation attenuation data for dry and saturated materials and basic equations, the porosities of porous media which contain spherical glasses were calculated. Local porosity values of porous model were performed by saturated medium. For this aim, the water was poured on the surface of porous medium in the Plexiglas container. The porous models were saturated means that the samples had 1 cm water content above the surface of porous medium. After saturation process, the gamma transmission measurements were taken at the same conditions that of dry medium. The experimental set-up consist of a NaI(Tl) detector (Ortec Model 802) and 60Co gamma source with 1250 keV gamma photons.