Feasibility Study on Thickness Measurement of Coated ZrO2 Using Optical Coherence Tomography

ZrO2 is coated on nuclear fuel rod to protect it from high temperature steam oxidation and erosion, the degeneracy of the coated $\mathrm{Z}\mathrm{r}\mathrm{O}_{2}$ is inevitable and needs to be measured in-situ periodically to ensure a qualified performance and meet the safety standard. The existing magnet-based method involves complex calibration procedure, which is sensitive to the radiation of the environment, and the sensor module can hardly be placed in the tiny gap between array of the fuel rods. Here, we demonstrated an extended industrial application of 1310 nm wavelength-based spectral domain optical coherence tomography for the non-destructive in-situ thickness measurement of the aforementioned $\mathrm{Z}\mathrm{r}\mathrm{O}_{2}$ materials coated on the fuel rod. The nature of optical fiber overcomes the aforementioned challenges for magnet-based methods. The acquired data show a high signal to noise ratio and distinct difference between different thickness, and thus confirms the potential applicability of optical coherence tomography for in-situ thickness measurement of coated $\mathrm{Z}\mathrm{r}\mathrm{O}_{2}$ materials.