Development of EPDM-based polymer nanocomposite barrier coating for radioactive waste storage containers

This research focused on developing a protective coating with improved radiation and corrosion resistance properties for nuclear waste disposal containers. The coating was developed by using radiation-resistant polymeric binder, ethylene propylene diene monomer as the base matrix, zinc oxide nanoparticles, and other reagents. Rheological parameters of coating formulations were analyzed to ensure that it could be applied by spray technique. Prepared coating formulations were applied on mild steel panels, and corrosion studies were performed in a salt spray chamber. To study the effect of gamma radiation on coating formulations, coated mild steel panels were irradiated at different radiation doses (up to 1800 kGy) using cobalt-60 as a radiation source. The dose and intensity of the radiation source were estimated based on the life of the waste package containing major radionuclide, such as Cs-137 and Sr-90, for simulating the disposal environment. The characterization of the coated panels was carried out before and after radiation exposure for dry film thickness, adhesion, and mechanical properties such as cross-cut adhesion, scratch hardness, pull off strength, tensile strength, and elongation. Thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy were also studied to see the effective changes in the coating after radiation exposure. The results showed that the high dose of radiation affecting the coating was in the marginal range, and it could withstand a radioactive as well as corrosive environment. The developed coating was found suitable to use for radioactive waste storage containers for long-term storage of low-level radiation waste.