Thermodynamic evaluation of the solidification phase of molten core–concrete under estimated Fukushima Daiichi nuclear power plant accident conditions
Thermodynamic evaluation of the solidification phase of molten core–concrete under estimated Fukushima Daiichi nuclear power plant accident conditions
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福岛第一核电站事故工况下熔融芯混凝土凝固阶段的热力学评估
DOI：
10.1016/j.jnucmat.2017.01.032
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发表时间：
2017
影响因子：
3.1
通讯作者：
T. Washiya
中科院分区：
文献类型：
--
作者：
T. Kitagaki;K. Yano;H. Ogino;T. Washiya
使用热力学平衡计算工具 FactSage 6.2 和 NUCLEA 数据库，预测了福岛第一核电站 1 号机组在估计的熔融核心-混凝土相互作用 (MCCI) 条件下熔融核心-混凝土的凝固阶段，以便为 1F 退役工作做出贡献，并通过 1F MCCI 产品的分析结果了解事故进展。我们发现，熔融核混凝土中的大部分 U 和 Zr 形成 (U,Zr)O2 和 (Zr,U)SiO4，而这些元素形成的其他相是有限的。然而，(Zr,U)SiO4的形成需要相对较长的时间，因为它涉及晶体结构从fcc-(U,Zr)O2转变为tet-(U,Zr)O2，然后与SiO2反应形成(Zr,U)SiO4。因此，淬火条件下(Zr,U)SiO4的形成受到限制。其他常见相包括氧化物相、CaAl2Si2O8、SiO2 和 CaSiO3，以及 Fe-Si 和 Fe-Ni 合金的金属相。讨论了1F MCCI级数中淬火条件下结皮的凝固现象和热力学平衡条件下熔池的凝固现象。
The solidification phases of molten core–concrete under the estimated molten core–concrete interaction (MCCI) conditions in the Fukushima Daiichi Nuclear Power Plant Unit 1 were predicted using the thermodynamic equilibrium calculation tool, FactSage 6.2, and the NUCLEA database in order to contribute toward the 1F decommissioning work and to understand the accident progression via the analytical results for the 1F MCCI products. We showed that most of the U and Zr in the molten core–concrete forms (U,Zr)O2and (Zr,U)SiO4, and the formation of other phases with these elements is limited. However, the formation of (Zr,U)SiO4requires a relatively long time because it involves a change in the crystal structure from fcc-(U,Zr)O2to tet-(U,Zr)O2, followed by the formation of (Zr,U)SiO4by reaction with SiO2. Therefore, the formation of (Zr,U)SiO4is limited under quenching conditions. Other common phases are the oxide phases, CaAl2Si2O8, SiO2, and CaSiO3, and the metallic phases of the Fe–Si and Fe–Ni alloys. The solidification phenomenon of the crust under quenching conditions and that of the molten pool under thermodynamic equilibrium conditions in the 1F MCCI progression are discussed.