Analysis of the Models in CISER2.0 Code
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摘要: 首先对熔融物堆内滞留策略有效性分析程序CISER2.0的模型进行了解析。CISER2.0程序包含4个3层熔融池模型：Esmaili & Khatib-Rahbar模型、Seiler模型、Salay & Fichot模型以及自主开发模型。对比发现，相比Esmaili & Khatib-Rahbar模型，Seiler模型更为保守；而Salay & Fichot模型虽然在计算氧化物层和重金属层成分时是基于热力学理论，但在确定轻金属层成分时采用的是用户假设的方法，且认为轻金属层是在熔融池顶部自动形成的；自主研发熔融池结构模型基于事故进程计算熔融池的结构，相对Salay & Fichot模型可自动计算轻金属层成分。本文以1000 MW先进反应堆为对象，基于程序中不同的熔融池分层模型，计算了主管道冷段小破口事故后熔融物在下腔室形成的熔融池的形态。但由于本研究对象的熔融物中的不锈钢含量太少，未能形成满足Seiler模型的三层结构。另外，本文还根据计算得到的三层熔融池结构给出了压力容器外壁面的热流密度分布。结果发现，各熔融池对应层中的熔融物成分的差异导致了压力容器外侧的热流密度分布的不同。即使在将Esmaili & Khatib-Rahbar模型和Salay & Fichot模型的对应层厚度设置成基本一致的情况下，两者的热流密度分布的差异也较大。同时，与前三种模型不同，自主研发模型还给出了熔融物跌落下腔室过程中压力容器外壁面的瞬态热流密度。
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关键词:
- 严重事故 /
- 堆内熔融物滞留 /
- CISER2.0程序 /
- 熔融池结构模型 /
- 瞬态热流密度
Abstract: This paper first analyzes the models of CISER2.0, a code of In-vessel retention (IVR) strategy effectiveness analysis. The CISER2.0 code consists of four three-layer melting pool models: Esmaili & Khatib-Rahbar model, Seiler model, Salay & Fichot model and self-developed model. It is found that compared with Esmaili & Khatib-Rahbar model, Seiler model is more conservative; Although the Salay & Fichot model is based on thermodynamic theory in calculating the composition of oxide layer and heavy metal layer, the method of user hypothesis is adopted in determining the composition of light metal layer, and it is considered that the light metal layer is formed automatically at the top of the melting pool; The self-developed melting pool structure model calculates the structure of the melting pool based on the accident process. Compared with the Salay & Fichot model, it can automatically calculate the composition of the light metal layer. In this paper, taking the 1000MW advanced reactor as an object, the morphology of the melting pool formed in the lower chamber after the accident of small break in the cold section of the main pipe is calculated based on the different layering models of the melting pool in the code. However, the content of stainless steel in the melt of this research object is too small to form a three-layer structure that meets the Seiler model. In addition, the heat flux distribution on the outer wall of the pressure vessel is given according to the calculated three-layer melting pool structure. The results show that the difference of melt composition in the corresponding layer of each melting pool leads to the difference of heat flux distribution on the outside of the pressure vessel. Even if the corresponding layer thickness of Esmaili & Khatib-Rahbar model and Salay & Fichot model is set to be basically the same, the difference of heat flux distribution between them is large. At the same time, different from the previous three models, the self-developed model also gives the transient heat flux of the outer wall of the pressure vessel when the melt falls down the chamber. -
图 1 CISER2.0程序自主研发模型计算流程图
Figure 1. Calculation Flowchart of the Self-Developed Model in CISER2.0 Code
图 3 压力容器外壁面热流密度对比（EKR模型和SFL模型）
Figure 3. Comparison of Heat Flux on Outer Wall of Pressure Vessel (EKR Model and SFL Model)
表 1 关键事故进程
Table 1. Key Accident Process
时间 进程 10 s SLOCA事故发生 0.92 h 堆芯开始裸露 1.21 h 堆芯出口气体温度超过923.15 K 1.33 h 安注箱投入 1.57 h 安注箱干涸 3.82 h 堆芯熔融物开始迁移到下腔室 7.30 h 堆芯熔融物完全跌落到下腔室 
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表 2 关键时间点熔融物积累信息
Table 2. Melt Accumulation at Critical Time
时间/h 熔融物质量/t UO2 Zr ZrO2 SS 3.825 5.680 4.150 3.946 3.064 3.839 14.880 4.666 4.476 3.092 5.495 70.407 16.458 8.215 7.874 5.637 82.177 16.777 8.265 23.463 5.651 90.966 16.777 8.276 26.638 7.460 92.252 16.777 8.276 27.942
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表 3 EKR模型三层熔融池结构计算值
Table 3. Structure of Three-Layer Melting Pool Calculated by EKR Model
成分 熔融物质量/t 轻金属层 氧化物层 重金属层 UO2 0 78.4 0 ZrO2 0 14.6 0 U 0 0 12.2 Zr 6.6 0 5.2 SS 27.9 0 0
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表 4 SF模型三层熔融池结构计算值
Table 4. Structure of Three-Layer Melting Pool Calculated by SF Model
成分 熔融物质量/t 轻金属层 氧化物层 重金属层 UO2 0 84.4 1.0 ZrO2 0 6.4 0.8 U 0 0 6.1 Zr 13.7 3.6 0.8 SS 19.6 0.6 1.8
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表 5 自主研发模型三层熔融池结构计算值
Table 5. Structure of Three-Layer Melting Pool Calculated by Self-Developed Model
时间/h 熔融池内
热量/MW成分 熔融物质量/t 轻金属层 氧化物层 重金属层 5.637 18.8 UO2 0.9 64.1 1.3 ZrO2 0 23.5 0 U 5.8 0 8.1 Zr 2.1 0 3.4 SS 14.4 1.6 7.5 5.651 18.7 UO2 1.3 68.7 1.3 ZrO2 0 22. 7 0 U 8.6 0 8.1 Zr 2.7 0 3.4 SS 17.8 1.5 7.5 7.460 17.6 UO2 1.4 67.5 1.3 ZrO2 0 22.1 0 U 9. 6 0 8.1 Zr 3.0 0 3.4 SS 19.1 1.4 7.5
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