Preparation of temporary protective coatings based on polyacrylic acid and its application on the surface of nuclear fuel rods

Addressing the issue of effective protection for nuclear fuel rod assemblies during the assembly process in the nuclear energy industry, this study developed a water-soluble protective coating suitable for nuclear fuel rod surfaces through water-based modification. The coating is based on methyl methacrylate (MMA) and styrene (St) as hard monomers, with butyl acrylate (BA) serving as the soft monomer. It was synthesized via seed emulsion polymerization to form a polyacrylate waterborne emulsion. The optimal ratio of soft to hard monomers in the emulsion is 1:1, with an emulsifier content of 1%, demonstrating excellent film-forming properties. The coating was characterized using differential scanning calorimetry (DSC), dynamic light scattering (DLS), laser scanning microscopy (LSM), and Fourier transform infrared spectroscopy (FT-IR). Thermogravimetric analysis (TGA) indicated that the coating exhibits good thermal stability at 200 °C. Sodium hydroxide modification reduced the water contact angle to 30.34°, enhancing the coating's hydrophilicity. After rinsing with 50 °C water at a flow rate of 300 mL/min for 1 min, EDS characterization and weight measurement confirmed that the coating was completely removed without any polymer residue. SEM analysis revealed a dense microstructure, and morphological assessment confirmed that the coating possesses strong scratch resistance, effectively preventing damage during fuel rod assembly. This coating holds significant potential for temporary protection of nuclear fuel rod surfaces.