Ahmet E. Osmanlioglu
Professor, Istanbul University, Turkey
Professor Ahmet Erdal OSMANLIOGLU received the B.Sc. degree in Mining Engineering, the M.Sc. in soil mechanics and the Ph.D. degree in Nuclear Engineering from Hacettepe University, in 1990, 1992 and 1996, respectively. He started to work as a Research Assistant at Hacettepe University in Ankara. He joined the Turkish Atomic Energy Authority in 1993 as a Research Engineer. He has worked as Coordinator, Deputy Director and Director General of the National Nuclear Center in Istanbul. Since 2015, he has worked as Professor (full) and Deputy Head of the Department at Istanbul University. He has received education in Nuclear Plant Safety at Massachusetts Institute of Technology, MIT, Boston MA USA. He has worked as a Waste Safety Committee (WASSC) Member at International Atomic Energy Agency (IAEA), Vienna, Austria and he has worked as a Radioactive Waste Management Committee (RWMC) Member at OECD Nuclear Energy Agency (NEA), Issy-les-Moulineaux, France.
Various types of radioactive wastes are generated from nuclear facilities and especially contamination of waste is a significant issue for the safety and the environment because of their potential health effects. Various immobilization technologies exist for stabilizing the radioactive waste in a stable matrix. Ordinary Portland Cement (OPC) is a commonly used encapsulant for nuclear waste. OPC is generally mixed with additives and radioactive liquid waste is immobilized it this matrix.
Various polymers were investigated instead of OPC. Such as; Vinyl Ester Styrene (VES), Advanced Polymer System (APS) epoxy and another type of epoxies. Most of these new immobilization technologies have some advantages to OPC. They have better compressive, tensile, flexural strength and they are stronger than cement. Polymer achieves maximum strength quickly with gelation behavior. Setting time of polymer matrix depends on process temperature. Generally, viscosity properties comply with Newtonian behavior. Research results show that exponential increase in viscosity as curing progress and dimensional changes of polymers shrink during the curing period. Polymers have better leaching performance than OPC matrix. They have lower heat capacity and thermal conductivity than cement. These properties are important for long-term isolation of nuclear waste.
The main reason for immobilization of nuclear waste is to prevent contamination. Contamination occurs basically in two mechanisms. These are; migration by water and dissemination by air. By these mechanisms, radioactive particles from the waste matrix cause contamination in water or air. An important reason for using polymers is polymers do contain water. Polymers have many desirable features as encapsulants. Such as; High strength, Low permeability, Compatibility with ‘difficult’ wastes, Radiation tolerant level. For these reasons, polymers are more suitable material for immobilization of nuclear waste in long-term.