Analysis of Mal-Operation Accidents of Nuclear Power Plant I&C System
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摘要: 为全面评价核电厂仪控系统误动作事故,提出基于简化分析的方法,该方法基于功能组概念对仪控误动作假设始发事件(PIE)进行了系统化地识别和归并,得到不能被已有事故分析包络的潜在新增事故工况,并根据保守的分析假设和准则,针对识别出的潜在新增事故进行了定性评价和定量分析。研究结果表明,核电厂保护系统能够对仪控系统误动作事故提供多样化保护,事故后果满足验收准则,并建议增设“2个热管段实际压力与饱和压力之差低2信号触发安注启动以及所有主泵停运”功能。
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关键词:
- 仪控系统误动作 /
- 假设始发事件(PIE) /
- 事故分析 /
- 多样化保护
Abstract: A method based on the simplified analysis was proposed in order to comprehensively evaluate the accidents of spurious actuation of Instrumentation and Control (I&C) systems of the Nuclear Power Plant (NPP). Based on the concept of “functional group”, the Postulated Initiating Events (PIEs) of spurious I&C actuation were systematically identified and grouped to obtain the potential additional accidents that cannot be bounded by the existing accident analysis. Then these potential additional accidents were qualitatively assessed and quantitatively analyzed according to the conservative analysis assumptions and rules. The results show that the protection systems of the NPP can provide diverse protection against the spurious I&C accidents and the consequences meet the acceptance criteria. Besides, the function of “startup of safety injection and trip of the main pumps triggered by the low 2 signal of the difference between the local pressure and saturation pressure in two hot legs” was suggested to be added. -
表 1 系统功能筛选准则
Table 1. Screening Criteria for System Functions
序号 准则 说明 1 就地操作功能 不需要仪控系统控制 2 非能动功能 不需要仪控系统控制 3 指示功能 不直接驱动设备 4 允许信号功能 不直接驱动设备 5 不改变设备状态 不会造成AOS 表 2 PIE瞬态分组
Table 2. Groups of PIEs by Transients
分组 瞬态说明 PIE数量 A 二次侧排热增加 13 B 二次侧排热减少 30 C 反应堆冷却剂流量减少 5 D 反应性与功率分布异常 8 E 反应堆冷却剂装量增加 20 F 反应堆冷却剂装量减少 23 G 反应堆冷却剂系统压力升高/下降 6 H 乏燃料水池相关事故 4 表 3 PIE归并结果
Table 3. Grouping Results of PIEs
触发系统 PIE总数 极限PIE数量 潜在新增事故数量 RPS 26 10 8 KDS 12 0 0 SAS 26 4 2 KDA 0 0 0 PSAS 42 1 0 非集中式系统 3 2 0 表 4 潜在新增事故
Table 4. Potential Additional Accidents
序号 触发系统 事故 核电厂状态 1 RPS 应急给水误启动 1~4 2 RPS 蒸汽大气排放阀误开启 1~6 3 RPS RHR管线误隔离 5~6 4 RPS 主蒸汽隔离阀误关闭 1~4 5 RPS 下泄管线误隔离 1~6 6 RPS 中压安注误启动 5~6 7 RPS 稳压器安全阀误开启 5~6 8 SAS 下泄管线误全开 1~6 9 SAS 稳压器电加热器误启动 1~6 10 RPS 乏燃料水池冷却系统管线误隔离 1~6 表 5 瞬态事件序列
Table 5. Transient Event Sequence
瞬态事件 时间/s 情况1 情况2 瞬态开始 0 0 产生ΔPsat低2信号 672 672 RHR泵停运 677 — 主泵停运 678 678 安注启动 701 701 安注流量与破口流量平衡 2236 2615 “—”表示不发生此事件 -
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