Oxygen potentials and defect chemistry in nonstoichiometric (U,Pu)O

不定比性(U,Pu)Oの酸素ポテンシャルと欠陥化学

加藤 正人   

Kato, Masato

蛍石構造を有する(U,Pu)Oは、広い範囲で安定に存在する不定比性化合物である。(U,Pu)Oの酸素ポテンシャルの測定結果と測定方法をレビューし、測定結果をもとに欠陥化学により解析を行った。得られた結果からO/Mを評価する式を導いた。

Uranium and plutonium mixed oxide (U,Pu)O is substitutional solid solution compound having CaF type fluorite structure, which is used as nuclear fuels. The (U,Pu)O is stable in wide range region of hyper- and hypo-stoichiometric composition. The oxygen potential of (U,Pu)O drastically changes with slight O/M change in near stoichiometric region. The drastically change may cause large uncertainty in oxygen potential measurement, and the data measured were scattered in region of more than 100 kJ/mol. Recently the data were accurately measured and the value at stoichiometric composition was determined as functions of temperature and plutonium content based on point defect chemistry. In this report the measurement data were reviewed, and the data were analyzed based on point defect chemistry.