To non-destructively determine the burnup of a spent nuclear fuel assembly, it is essential to analyze the nuclear isotopes present in the assembly and detect the neutrons and gamma rays emitted from these isotopes. Specifically, gamma-ray measurement methods can utilize a single radiation measurement value of 137Cs or measure based on the energy peak ratio of Cs isotopes such as 134Cs/137Cs and 154Eu/137Cs. In this study, we validated the extent to which the results of gamma-ray measurements using cadmium zinc telluride (CZT) sensors based on 137Cs could be accurately simulated by implementing identical conditions on MCNP. To simulate measurement scenarios using a lead collimator, we propose equations that represent radiation behavior that reaches the detector by assuming “Direct hit” and “Penetration with attenuation” situations. The results obtained from MCNP confirmed an increase in measurement efficiency by 0.47 times when using the CZT detector, demonstrating the efficacy of the measurement system.

1. Introduction
2. Materials and Methods
    2.1 Selection of Gamma-ray Detector: CZT
    2.2 Comparison of Gamma-ray MeasurementExperiment and MCNP Simulation
3. Evaluation of Gamma-ray AttenuationRate
    3.1 Pb Plate With a Collimeter (hole) Modeling:Direct Hit
    3.2 Penetration With Attenuation
4. Geometry Modeling in Cylindrical Conceptsand Corresponding Result
5. Conclusion
Conflict of Interest
Acknowledgements
REFERENCES

• Sohee Cha(Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea)
• Kwangheon Park(Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea) Corresponding author