Study on Influence of Material Physical Properties Change on Containment Performance under Severe Accident
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摘要: 安全壳作为压水堆核电厂的最后一道屏障，其在严重事故工况下的完整性既取决于严重事故现象发生情况，也取决于安全壳性能特点。目前在华龙一号安全壳性能分析时仅考虑了材料的常温物性特征，无法反映严重事故下安全壳本身的升温升压影响。本文根据严重事故下安全壳的响应情况，考虑事故下材料物性的变化，分析基于事故高温的材料性能对安全壳性能的影响，并对比常温和事故高温下的安全壳性能差异，分析不同温度下严重事故风险的差异，评估对早期大量放射性释放频率、大量放射性释放频率和严重事故管理的影响。分析结果表明，严重事故下随着安全壳内温度逐步升高，安全壳性能有所降低，但安全壳薄弱环节依然在设备闸门处；对照常温和高温两条安全壳失效概率曲线，由于华龙一号安全壳自由容积较大，直接安全壳加热（DCH）和等容绝热完全燃烧（AICC）产生的载荷均不会威胁安全壳完整性，且不会颠覆原安全壳过滤排放系统开启整定值。Abstract: As the last barrier of PWR nuclear power plant, the integrity of containment in severe accident condition depends not only on the occurrence of severe accident phenomenon, but also on the performance characteristics of containment. At present, in the performance analysis of HPR1000, only the physical characteristics of materials at normal temperature are considered, which cannot reflect the influence of temperature rise and pressure rise of the containment itself under severe accidents. In this paper, according to the response of containment under severe accident and considering the change of material properties under accident, the influence of material properties on containment performance under accident high temperature is analyzed, and the difference of containment performance between normal temperature and accident high temperature is compared. The difference of severe accident risk at different temperatures is analyzed, and the influence on early massive radioactive release frequency, massive radioactive release frequency and severe accident management is evaluated. The analysis results show that the performance of the containment decreases with the increase of the temperature in severe accidents, but the vulnerability of containment is the equipment hatch as before. Compared with the two curves of the containment failure probability distribution at normal temperature and high temperature, due to the large free volume of HPR1000 containment, the loads generated by DCH and AICC will not threaten the integrity of the containment. The original operation setpoint of containment filtration and exhaust system is not challenged.
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图 2 极限承载力下混凝土和钢衬里环向应力云图
Figure 2. Circumferential Stress Nephogram of Concrete and Steel Lining under Ultimate Bearing Capacity
图 4 人员闸门内筒有限元模型和内筒应变分布图
Figure 4. FE Model and Strain Distribution of Inner Personnel Air-lock Door
图 6 高压熔堆快速序列安全壳事件树
1、2—代表不同事故情况下“未发生蠕变诱发SGTR”题头的不同输入
Figure 6. Containment Event Tree of Fast Sequences for High Pressure Core Meltdown
表 1 安全壳各位置极限承载力 MPa
Table 1. Ultimate Baring Capacity of Containment Positions
序号 安全壳筒体 设备闸门 人员闸门 应急闸门 1 1.27377 0.884 1.108 1.108 2 1.21719 0.849 1.133 1.133 3 1.24030 0.853 1.133 1.133 4 1.19127 0.867 1.133 1.133 5 1.13979 0.792 1.133 1.133 6 1.21568 0.872 1.158 1.158 7 1.20699 0.845 1.158 1.158 8 1.22610 0.808 1.158 1.158 9 1.23041 0.864 1.158 1.158 10 1.25219 0.820 1.158 1.158 11 1.23563 0.813 1.183 1.158 12 1.23647 0.855 1.183 1.158 13 1.22033 0.830 1.183 1.183 14 1.22516 0.835 1.183 1.183 15 1.24266 0.839 1.183 1.183 16 1.25135 0.845 1.183 1.183 17 1.23111 0.837 1.183 1.183 18 1.14726 0.859 1.208 1.208 19 1.14177 0.822 1.208 1.208 20 1.22934 0.828 1.208 1.208 
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表 2 安全壳失效概率曲线特征值
Table 2. Characteristic Values of Containment Failure Probability Curves
温度/℃ 中值压力/MPa 5%分位值压力/MPa 20 1.035 0.962 165 0.941 0.902
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表 3 不同序列DCH压力载荷结果
Table 3. DCH Pressure Loads of Different Sequences
事故序列 DCH压力载荷/bar 累积概率0.50 累积概率0.99 累积概率1.00 15 mm LOCA 3.79 4.68 5.41 LOFW 3.76 4.69 5.22 MSLB 4.06 4.96 5.48 SBO 3.71 4.64 5.36 丧失给水 ATWS 4.01 4.97 5.53 25 mm LOCA 5.22 6.09 7.03 注：1 bar=105 Pa
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