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Development of thermal conductivity model with use of a thermal resistance circuit for metallic UO2 microcell nuclear fuel pellets

  • Heung Soo Lee (LWR Fuel Technology Research Division, Korea Atomic Energy Research Institute) ;
  • Dong Seok Kim (LWR Fuel Technology Research Division, Korea Atomic Energy Research Institute) ;
  • Dong-Joo Kim (LWR Fuel Technology Research Division, Korea Atomic Energy Research Institute) ;
  • Jae Ho Yang (LWR Fuel Technology Research Division, Korea Atomic Energy Research Institute) ;
  • Ji-Hae Yoon (LWR Fuel Technology Research Division, Korea Atomic Energy Research Institute) ;
  • Ji Hwan Lee (LWR Fuel Technology Research Division, Korea Atomic Energy Research Institute)
  • Received : 2023.02.27
  • Accepted : 2023.07.02
  • Published : 2023.10.25

Abstract

A metallic microcell UO2 pellet has a microstructure where a metal wall is connected to overcome the low thermal conductivity of the UO2 fuel pellet. It has been verified that metallic microcell fuel pellets provide an impressive reduction of the fuel centerline temperature through a Halden irradiation test. However, it is difficult to predict the effective thermal conductivity of these pellets and researchers have had to rely on measurement and use of the finite element method. In this study, we designed a unit microcell model using a thermal resistance circuit to calculate the effective thermal conductivity on the basis of the microstructure characteristics by using the aspect ratio and compared the results with those of reported metallic UO2 microcell pellets. In particular, using the thermal conductivity calculated by our model, the fuel centerline temperature of Cr microcell pellets on the 5th day of the Halden irradiation test was predicted within 6% error from the measured value.

Keywords

Acknowledgement

This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT, No. RS-2022-00144431).

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