Threshold burnup for rim formation and its effect on the thermal conductivity degradation in high burnup UO{sub 2} fuel
Conference
·
OSTI ID:23142169
- Korea Atomic Energy Research Institute, Advanced Fuel Development Team, 150 Duckjin-dong Yusong-gu, Taejon 305-353 (Korea, Republic of)
Rim characteristics and its effect on the thermal conductivity was investigated in the high burnup UO{sub 2} fuel. Threshold burnup for rim formation was estimated as a function of the temperature and fission rate. The calculated threshold burnup shows the particular dependence on temperature. The threshold burnup ranges from 40 to 50 MWD/kg U at the intermediate temperature of 400 to 600 deg. C that is typical in the fuel periphery. On the contrary, the threshold burnup steeply increases as fuel temperature deviates from the intermediate temperature region. On the other hand, the fission rate does not cause any distinguishable variation of threshold burnup at low temperatures (400 and 500 deg. C), while the threshold burnup steeply decreases with fission rate at higher temperatures. To consider the additional thermal conductivity degradation in the rim region, our developed rim porosity model developed in the present paper was combined with the HALDEN's thermal conductivity model. Rim burnup and rim width were obtained by the statistical analysis of the data given in open literature. The rim porosity model was developed based on the assumption that rim pores are overpressurized and that all the produced fission gases are retained in rim pores. The thermal conductivity was additionally reduced by over 30% due to the porous rim structure, which contributes to increasing the fuel centerline temperature during steady and transient irradiation of high burnup fuel.
- Research Organization:
- American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 23142169
- Country of Publication:
- United States
- Language:
- English
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