Thermal conductivity of beginning-of-life uranium-plutonium mixed oxide fuel for fast reactor (Secondary report)

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Thermal conductivity of uranium-plutonium mixed oxide fuel for fast reactor at beginning-of-life was re-correlated in order to apply to the fuel design and the fuel pin performance analysis. Thermal conductivity of actual fuel with porosity (), that of fully dense fuel () and porosity correction factor (F) has theoretically the following correlation : = F, The database (221 points) were selected by adopting following criteria: "validated by different authors and methods" and "high density fuel specimens around 95% of theoretical density". The database were corrected to fully dense condition by modified Loeb equation : F=1-2.5P (P: fractional porosity) and then correlated by the least square method program. The electron conduction term of uranium dioxide reported by Harding was used in order to compensate for the lack of the high temperature range data. New correlation for fully dense fuel was developed again and shown below, which the data base used in the analysis ranged from 20 to 30% for plutonium content in heavy metal atoms, 1.98 and 2.00 for oxygen to metal ratio, from 94.3 to 96.4% of theoretical density and from 64 to 2279C for temperature. = + exp() where...: Thermal conductivity of fully dense MOX fuel for fast reactor (W/mK). T: Temperature (K). O/M: Oxygen-to-metal ratio (-). The above correlation could be applied for fully dense and typical MOX fuel pellet of fast reactor ranging from room temperature up to melting point.