Analysis of Station Blackout Accident in Nuclear Power Plant Based on Dynamic Event tree
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摘要: 为解决传统事件树分析中缺少动态时间参数影响和较多依赖专家判断的不足,本研究使用动态事件树(DET)方法建立中国改进型三环路压水堆(CPR1000)核电厂全厂断电(SBO)事故响应模型。针对汽动辅助给水系统、交流电源恢复等分支节点建立时间相关分支,全面仿真事故分支结果,并计算分支概率与SBO事故下堆芯损伤的失效概率。计算结果表明,不同的汽动辅助给水系统运行时间与交流电源恢复时间对事故后果有明显影响,汽动辅助给水系统运行时间的增长可以延长电源恢复的时间窗口,但电源恢复时间存在上限,超过上限值则堆芯损伤不可避免。相比于传统事件树中计算得到的失效概率,动态事件树方法降低了失效概率值,挖掘出了潜在的安全裕度。
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关键词:
- 动态事件树(DET) /
- 全厂断电(SBO)事故 /
- 动态方法 /
- 分支建模
Abstract: Traditional event tree analysis ignores the dynamic time parameters and heavily relies on expert judgement. To tackle these issues, this study utilizes dynamic event tree (DET) method to to establish a response model for station blackout (SBO) accidents of China's improved three-loop PWR (CPR1000) nuclear power plant. Time-dependent branching is established for branch nodes such as turbine-driven auxiliary feedwater system and AC power recovery, and the accident branching results are comprehensively simulated, and the branching probability and the failure probability of core damage under SBO accident are calculated. The calculation results show that different running time of turbine-driven auxiliary feedwater system and recovery time of AC power supply have obvious influence on the accident consequences. The increase of running time of turbine-driven auxiliary feedwater system can prolong the time window of power supply recovery, but there is an upper limit for power supply recovery time, beyond which core damage is inevitable. Compared with the failure probability calculated by the traditional event tree, the dynamic event tree method reduces the failure probability value and develops the potential safety margin.-
Key words:
- Dynamic event tree (DET) /
- Station blackout (SBO) /
- Dynamic method /
- Branch modelling
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表 1 SBO-DET-R模型分支名称及对应分支时间
Table 1. Branch Name and Corresponding Branch Time for SBO-DET-R Model
汽动辅助给水
系统运行时间/h分支名称 交流电源
恢复时间/h分支名称 0.5 TAFW_0 1.5 AC_0 1.0 TAFW_1 2.0 AC_1 1.5 TAFW_2 3.0 AC_2 2.0 TAFW_3 4.0 AC_3 2.5 TAFW_4 5.0 AC_4 3.0 TAFW_5 6.0 AC_5 8.0 TAFW_6 交流电源未恢复 AC_6 表 2 SBO-DET-N分支节点概率
Table 2. Probability of SBO-DET-N Branching Nodes
分支节点 汽动辅助给
水系统启动失败主泵轴封
发生泄漏交流电源
恢复失败节点概率 8.17×10−6 9.89×10−3 9.19×10−1 表 3 运行型分支概率分布类型及对应分布参数
Table 3. Types of Probability Distributions and Corresponding Distribution Parameters of Running Branches
概率参数 汽动辅助给水系统
运行时间概率分布外电网恢复
时间概率分布应急柴油发电机组
恢复时间概率分布分布类型 指数分布 对数正态分布 对数正态分布 分布参数 $ \mathrm{\lambda }=7.89\times {10}^{-7} $ h−1 $ \mu =10.57 $
$ \sigma =0.7 $$ \mu =9.66 $
$ \sigma =0.756 $ -
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