U-Zr-Fe-O系の凝固時偏析挙動
The Segregation behavior in U-Zr-Fe-O system during solidification process
須藤 彩子 ; 水迫 文樹*; 星野 国義*; 佐藤 拓未 ; 永江 勇二 ; 倉田 正輝
Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
With a view to investigating the tendency of segregation of constituents of fuel debris, liquefaction/solidification tests of simulated corium (UO, ZrO, FeO, BC and sim-FP oxides) were performed. Simulated corium was heated up to 2600C under Ar atmosphere and then cooled down with two different cooling processes; furnace cooling and slow cooling. Cross sectional images of both samples showed that the oxide layer and metallic layer were separately solidified. EDX analysis of oxide layer of samples revealed three oxide phases and Fe metal. Solubility of FeO in these oxide phases was mostly fixed to be 125at% in all phases, which is in reasonable accordance with the value estimated from UO-ZrO-FeO phase diagrams. The tendency of re-distribution of oxide elements observed in the sample with slow cooling was similar to that of quick cooling, however, the grain-growth of one oxide phase, rich in Zr-oxide, occurred at the bottom region of the oxide layer. The composition of this Zr-oxide phase is comparable to the initial average composition. The condensation is considered to be caused by the connection of remaining liquid agglomerates during slow solidification.