High-temperature interaction between zirconium and UO

ジルコニウムとUOの高温反応

白数 訓子  ; 鈴木 晶大*; 永江 勇二 ; 倉田 正輝 

Shirasu, Noriko; Suzuki, Akihiro*; Nagae, Yuji; Kurata, Masaki

ジルカロイ被覆管とUO燃料の高温における溶融過程解析モデルの高度化に資するため、ZrとUOの高温反応試験を実施した。UOるつぼに、Zr試料を装荷し2173K近傍で加熱を行い、生成した反応相の成長状況や溶融状態、組織変化の観察を行った。試料の中間領域には、上方へ直線状に伸びる相が観測された。この相は、U-Zrの金属溶体相と考えられ、Zr試料中、酸素濃度が少ない方へ選択的に成長したと考えられる。

High temperature interaction tests between UO and Zr were performed at around 2173 K, to make clear the UO/ -Zr(O) interaction and the mechanism of degradation, for developing the improved models for advanced severe accident analysis codes. A Zr plate was inserted in a UO crucible, and heat treated at 2173 K in stream of Ar. After the heat-treatment, the samples were subjected to surface microanalysis. The middle region of Zr sample shows streak-like structures which are extended towered the top. It is confirmed that the streak-like structures were mainly consist of U from the EDX results, and the structures revealed that the U-rich phase was liquid during the heat-treatment. It seems that the U-rich liquid grew selectively toward the area where the oxygen concentration was low.