The domestic CANDU nuclear power plants have been operated for a long time and various unforeseen spent fuel defects have been discovered. As the spent fuel defects are important factors in the safety of the nuclear power plant, a study on the analysis of the spent fuel defects to prevent their recurrence is necessary. However, in cases where the fuel rods inside the fuel assembly are defected, it is difficult to dismantle the fuel assembly owing to their welded structure and the facility conditions of the plant. Therefore, it is impossible to analyze the spent fuel defect because it is difficult to visually check the shape of the fuel defect. To resolve these problems, an analysis technology that can predict the number of defected fuel rods and defect size was developed. In this study, we developed a methodology for investigating the root cause of spent fuel defects using a database of the earlier fuel defects in the plants. It is anticipated that in the future this analysis technology will be applied when spent fuel defects occur.

1. Introduction
2. Development of analysis technologyfor fuel defect
    2.1 Fission product of nuclear fuel
    2.2 Diffusion of the fission product
    2.3 Nuclides for evaluation of the defectivefuel
    2.4 Simulation of the fission productsbehavior
3. Results and discussion
    3.1 Prediction for the number of defectivefuel rod
    3.2 Prediction for the defect size
    3.3 Prediction of defect causes
4. Conclusions
REFERENCES

• Jong-Hyeon Lee(Chungnam National University) Corresponding Author
• Yong-Chan Kim(Chungnam National University/KEPCO Nuclear Fuel)