Effect of Radiation on Polymeric Binder for Development of Radiation Resistant Coating

Abstract

The application of radiation provides numerous benefits to people and society. It is a natural consequence of such applications that waste is generated. Radioactive wastes are generated during various operations of the nuclear fuel cycle. The waste remains radioactive for a few hours or several months or even hundreds of years depending upon the nature of radioisotopes present in the waste. The radioactive waste needs to be managed in a safe and secure manner. The primary objective is to isolate the radioactive waste from people and the environment for the period up to waste remains hazardous. The safe disposal of radioactive waste is a complex issue, not only because of the nature of the waste, but also because of the stringent structure for dealing with radioactive waste. The radioactive waste must be stored in environmentally sound containers to effectively isolate the waste from the environment. Most of the research done to date involves focused on the radioactive waste storage containers. For storage of low-level radioactive waste, metal containers are used; but due to corrosion they are not suitable for long term duration. A barrier coating has a great importance to be applied on metal surface to avoid its interaction with surroundings. These coatings have to be designed using stable polymeric binder that can sustain the radioactive environment. The polymeric binders used in these coatings can become degraded over time when subjected to radiation, compromising their protective abilities. In the study, polymers such as PU, HDPE, epoxy, EPDM are exposed to gamma radiation from 300 kGy to 1200 kGy and the effects are studied by checking the physical properties (water absorption and density), mechanical properties (Tensile strength & elongation, Hardness, Gel content, TGA) and surface properties (SEM) to differentiate the best possible binder for the corrosion and radiation resistant coating. It has been observed that EPDM is the most suitable polymeric binder to develop coating formulations for radioactive waste storage containers. Effect of radiation on surface of EPDM is not observed, whereas surface deterioration and cracks are seen in-case of epoxy, TPU and HDPE. The flexibility of EPDM retained well even after exposure. The physical and mechanical properties checked, well supports the choice of choosing EPDM as a polymer for radiation barrier coating.