Study of New Polymeric/Ilmenite Composites as Shields for Neutron Sources

Abstract

This thesis is concerned with the investigation of the physical, thermomechanical, and radiation attenuation properties of some shielding materials. Selected shields of Acrylamide, Acrylic acid, and Polyvinyl Alcohol hydrogel composites were chosen to fulfill certain applications and are concerned for the present work. Both hydrogels (Acrylamide, Acrylic acid, and Polyvinyl Alcohol) were filled with ilmenite and as well as, boric acid for homogeneous shields. In general, polymeric substances are hydro carbonic substances which guarantee good neutron moderation and attenuation. Furthermore, ilmenite was employed for gamma-rays attenuation. Any material used for shielding purposes should fulfill some design criterion which includes physical and thermomechanical proficiency beside their main role as nuclear radiations attenuator. Therefore, physical properties as density, water absorption, and porosity were tested. Also, thermomechanical analysis as a linear thermal expansion and glass transition was performed to monitor the usefulness of the composites as radiation shields. Radiation attenuation properties have been carried out using different thicknesses of the investigated composite samples vary from 3 to 18 cm and collimated radiation beams emitted from radioactive Pu-α- Be (5 Ci) neutron source. Fast neutron and gamma-ray spectra were measured by a neutron-gamma spectrometer with a stilbene organic scintillator based on the zero crossover method of the Pulse Shape Discrimination (PSD) technique. This technique was used to discriminate