Analysis of Blockage Accident of Lead-Based Fast Reactor Single-Box Fuel Assembly Based on CFD
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摘要: 铅基快堆在运行过程中产生的腐蚀产物有可能会在堆内沉积，导致堵流事故的发生。基于计算流体力学（CFD）软件 Ansys Fluent 分析了不同堵块面积、堵块厚度、堵块类型以及堵块位置对堵流事故中传热以及流场性质的影响规律。结果显示，堵块面积的增加会增加回流区域面积，使得温度回落更慢，传热恶化显著；堵块厚度的增加将导致冷却剂和包壳最高温度上升，极易导致包壳损坏；多孔介质堵块内冷却剂以较低流速通过，缓解了堵块造成的影响，其危害小于实心堵块；堵流发生在组件活性区中部与发生在活性区出、入口相比所造成的局部温升更加明显，危害更大。
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关键词:
- 铅基快堆 /
- 堵流事故 /
- 计算流体力学（CFD）
Abstract: The corrosion products produced during the operation of the lead-based reactor may be deposited in the reactor, resulting in the occurrence of flow plugging accident. Based on the computational fluid dynamics software Ansys Fluent, the effects of different blockage area, thickness, type and position on the deterioration of heat transfer and the properties of flow field in current plugging accident are analyzed. The results show that the increasing of blockage area will increase the reflux area, which makes the temperature fall more slowly and the heat transfer worsen obviously; the increasing of the blockage thickness will lead to the increasing of the maximum temperature of coolant and cladding, which can easily lead to cladding damage; the coolant in the porous medium blockage passes at a lower flow rate, which alleviates the influence of blockage and does less harm than the solid blockage. The local warming caused by the blockage located in the middle of the active area is more obvious and more harmful than that caused by the blockage in the entrance and exit of the active area. -
图 1 堵块面积影响1号燃料棒包壳轴向温度分布
Figure 1. Block Area Affects Axial Temperature Distribution of No. 1 Fuel Rod Shell
图 2 堵块厚度影响1号燃料棒包壳轴向温度分布
Figure 2. Thickness of Block Affects Axial Temperature Distribution of No. 1 Fuel Rod Shell
图 3 堵块类型影响1号燃料棒包壳轴向温度分布
Figure 3. Block Type Affects Axial Temperature Distribution of No. 1 Fuel Rod Shell
图 4 堵块位置影响1号燃料棒包壳轴向温度分布
Figure 4. Block Position Affects Axial Temperature Distribution of No. 1 Fuel Rod Shell
表 1 单盒燃料组件主要参数
Table 1. Main Parameters of a Single-Box Fuel Assembly
参数名 参数值 棒束排列方式 三角形 燃料棒数量 19 燃料棒外径/mm 15 棒间距与棒径比 1.07 组件盒内对边距/mm 76.50 活性区长度/mm 800 芯块直径/mm 12.7 包壳-燃料芯块间隙/mm 0.25 包壳厚度/mm 0.9 包壳材料 316钢 燃料材料 UO2 
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表 2 液态金属LBE材料物性表
Table 2. Liquid Metal LBE Material Properties
参数名 参数值 定压比热容 159−2.72×10−2T+7.12×10−6T2 密度 11096−1.1944T 热导率 9.2+0.011T 粘性 4.56×10−3−7.03×10−6T+3.61×10−9T2 T—温度
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表 3 计算输入
Table 3. Calculation Input
项目 条件 湍流模型 Realizable $k - \varepsilon $ 冷却剂入口温度/K 533 冷却剂入口流速/(m·s−1) 0.123 燃料组件外壁面 绝热 出口设置 压力出口
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表 4 拟定的堵流工况
Table 4. Selected Cases of Blockage Accident
工况
编号堵块介质 堵块厚
度/mm子通道
编号堵块中心
高度/mm占总流道的
面积/%P1 实心堵块 10 1~6 400 11.6 P2 实心堵块 10 1~7、10、13、
16、19、22400 23.1 P3 实心堵块 10 1~24 400 46.4 P4 实心堵块 20 1~6 400 11.6 P5 实心堵块 40 1~6 400 11.6 P7 实心堵块 10 1~24 795 46.4 P8 实心堵块 10 1~24 5 6.4 B1 多孔介质
（30%孔隙率）10 1~6 400 11.6
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