Fig. 1. Optical morphology of fuel in intact fuel rod

Fig. 2. Optical morphology of fuel in leaked fuel rod

Fig. 3. Influence of 100 mW laser power on sample surface

Fig. 4. Effect of different laser power on Raman spectrum of fuel pellet

Fig. 5. Images of Raman spectra of D05 and D13 intact fuel rod

Fig. 6. Images of Raman spectra of E05 and J05 leak fuel rod

Fig. 7. Change of 1150 cm⁻¹ intensity of fuel pellet