共查询到18条相似文献,搜索用时 593 毫秒
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为建立基于现场可编程门阵列(FPGA)的反应堆保护系统的可靠性模型,以对系统安全提供有效的分析与验证手段。本研究采用故障树、随机Petri网模型,对CANDU堆1号停堆系统(SDS1)单通道进行可靠性建模与分析。对故障树模型分析得到最小割集,以顶事件发生概率作为系统故障概率,在考虑故障检测、维修与定期试验情况下对随机Petri网模型进行仿真得到系统的拒动概率。研究结果表明,故障树和状态空间方法存在一定局限性,随机Petri网能够反映故障检测与定期试验对反应堆保护系统的影响,可以动态地反映系统可靠性,并且避免了状态空间爆炸问题。因此,本研究建立的随机Petri网模型适用于反应堆保护系统的可靠性建模。 相似文献
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保护系统是保证中国先进研究堆(CARR)安全的重要系统之一,它的高可靠性是保证其完成预期功能的重要条件。本工作以保护系统为研究对象,利用故障模式及影响分析和故障树等可靠性分析方法,建立相应模型,对保护系统进行了定性和定量的分析,得到了保护系统发生故障的概率和最小割集,其可靠性水平达到了CARR工程的设计要求,验证了设计,为CARR其他系统分析和验证奠定了基础。 相似文献
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田湾核电站数字化反应堆保护系统可靠性分析 总被引:1,自引:0,他引:1
分析了田湾核电站数字化反应堆保护系统的结构和基本功能,以故障树分析方法为基础,确定了数字化反应堆保护系统故障树的顶事件,建立了以反应堆停堆子系统失效为顶事件的故障树,利用RISK-SPECTRUM程序,对所建的故障树进行了定量分析和计算,得到了系统故障树的失效概率和最小割集,为田湾核电站运行和维修提供了有益的指导. 相似文献
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未能紧急停堆的预期瞬态(ATWS)缓解系统是保证中国先进研究堆(CARR)安全的重要系统之一。当发生预期运行瞬态,反应堆未能紧急停堆时,通过ATWS缓解系统动作实现停堆,从而保护反应堆安全。ATWS缓解系统的高可靠性是保证其完成预期功能的重要条件,因此对该系统的可靠性给予了高度重视。本文以ATWS缓解系统为研究对象,利用故障模式及影响分析和故障树等可靠性分析方法,建立相应模型,对ATWS缓解系统进行了定性和定量的分析,得到了ATWS缓解系统发生故障的概率和最小割集,找出了薄弱环节,提出了改进措施和建议,其可靠性水平已达到CARR工程的设计要求,验证了设计,为CARR其他系统分析和验证奠定了基础。 相似文献
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设备冷却水系统(CCS)是一类具有双重冗余的可修复系统,冗余设备的交替运行以及故障设备的修复等因素对可靠性分析结果影响较大。传统故障树分析因缺乏对时间因素的描述,对于此类动态时序问题,分析假设过于保守。针对故障树分析的上述局限性,采用布尔逻辑驱动的马尔可夫过程(BDMP)方法对先进压水堆(AP1000)CCS进行了动态可靠性分析。然后基于BDMP模型导出了最简故障组合,计算了系统失效概率,并分析了系统失效的主要贡献因素。结果表明,CCS失效概率对设备冷却水泵的共因失效因子敏感,降低泵的共因失效可提高CCS可靠性。 相似文献
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本文给出了RBMK-1500反应堆事故检测系统(Accident Localization System,ALS)的可靠性和风险分析,以防止放射性向环境释放。系统的可靠性采用两种方法来估计和比较:传统的故障树方法和创新的基于随机微分方程的动态可靠性模型。对通过ALS的放射性释放的概率进行了估计。研究结果表明,在这个例子中传统的故障树模型方法在系统可靠性估计中存在高度的保守性。
对ALS进行可靠性研究的目的之一,就是证明动态可靠性分析方法与传统故障树,事件树方法相比较的优点。提出了对系统行为的动态方面进行处理的马尔科夫体系。虽然没有进行详细分析,但该体系仍然有能力解决非常多的部件失效的问题。简述了随机微分方程的计算方法,包括解析方法(仅适用相对小而简单的系统)和一些数值方法,如蒙特卡罗方法和对微分方程进行数值迭代的计算法。最后,对所研究系统的可靠性和使用的计算方法进行了评论和总结。 相似文献
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为了评估数字化仪表控制系统对核电厂安全的影响,以电厂停堆系统和专设安全设施驱动系统为例,参考西门子公司提供的故障树逻辑,对主泵流量低及功率量程中子通量高于整定值停堆故障和蒸汽发生器(SG)低-低水位和同一SG中主给水流量低故障进行了概率安全分析.分析中分别采用西门子公司提供的输入数据及通过失效率、试验时间以及β因子方法计算得到的数据,对西门子的分析结果进行了校算,在主要割集和失效概率上得到更为真实的结果.结果表明,考虑2种多样性的反应堆保护系统停堆I&C功能需求失效概率均值为5.5×10~(-8),符合分布式控制系统(DCS)合同中确定的可靠性目标值(1.0×10~(-7))和辅助给水电动泵驱动信号功能需求失效概率均值(5.21×10~(-6)与8.32×10~(-6)),也符合DCS合同中确定的可靠性目标值(1.0×10~(-5)). 相似文献
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Recently, digital instrumentation and control systems have been increasingly installed for important safety functions in nuclear power plants such as the reactor protection system (RPS) and the actuation system of the engineered safety features. Since digital devices consist of not only electronic hardware but also software that can control microprocessors, the functions specific to digital equipment such as self-diagnostic functions have been becoming available. These functions were not realized with conventional electric components. On the other hand, it has been found that it is difficult to model the digital equipment reliability in probabilistic risk assessment (PRA) using conventional fault tree analysis technique. OECD/NEA CSNI Working Group of Risk Assessment (WGRisk) set up the task group DIGREL to develop the basis of reliability analysis method of the digital safety system and is now discussing about several issues including quantitative dynamic modeling. This paper shows that, taking account of the relationship among the RPS failures, demand after the initiating event, detection of the RPS fault by self-diagnostic or surveillance tests, repair of the RPS components and plant shutdown operation by the plant operators as a stochastic process, the anticipated transient without scram (ATWS) event can be modeled by the event logic fault tree and Markov state-transition diagrams assuming the hypothetical 1-out-of-2 digital RPS. 相似文献
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Methodology for reliability allocation based on fault tree analysis and dualistic contrast 总被引:1,自引:0,他引:1
Reliability allocation is a difficult multi-objective optimization problem.This paper presents a methodology for reliability allocation that can be applied to determine the reliability characteristics of reactor systems or subsystems.The dualistic contrast,known as one of the most powerful tools for optimization problems,is applied to the reliability allocation model of a typical system in this article.And the fault tree analysis,deemed to be one of the effective methods of reliability analysis,is also adopted.Thus a failure rate allocation model based on the fault tree analysis and dualistic contrast is achieved.An application on the emergency diesel generator in the nuclear power plant is given to illustrate the proposed method. 相似文献
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“在线自诊断”作为数字化仪控系统的重要特征,对核电厂反应堆保护系统(RPS)停堆功能的可靠性分析具有重要作用。通过分析自诊断对人因、定期试验等因素的影响,建立设备级误动模型;以典型RPS TX为例,通过马尔科夫方法建立动态的TX序列级和系统级模块误动模型;利用系统级模块误动模型定量计算TX停堆功能可靠度与自诊断的关系。通过定性分析与定量计算论证了综合考虑自诊断对RPS停堆功能可靠性分析的必要性,为后续国内RPS停堆功能的可靠性评价提供了借鉴。 相似文献
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Reliability of the digital reactor protection system (RPS) is intensively researched as it is designed and installed to ensure the safety and economy which can be measured respectively by the probability of failure on demand (PFD) and probability of spurious trip (PST). Meanwhile, by analyzing the failure modes of the digital RPS, the failure on demand and spurious trip are the two main modes that should be evaluated for the reliability of digital RPS. Therefore, this paper develops the PFD and PST calculation formulas considering the module repair time as the repair takes some time, and during the repair duration, the digital system is operated in the degraded configuration and the common cause failure (CCF) which would severely impact the system in the event of occurrence. Considering the failure phenomenon of the digital RPS, the binomial failure rate (BFR) model is adopted for CCF. And the fault-tolerance techniques and their fault coverage are considered when calculating the PFD and PST. The quantitative results show that, in the example, CCF dominates the PFD while CCF is one of the major factors that result in PST but the main contributor is the independent failure. Also it can be concluded that the discovery time for the undetected failures dominates the PFD and PST when it costs long time to discover the failures even though the uncovered failures are very few. Thus, the failures should be covered by the fault-tolerance techniques as much as possible when designing the digital RPS. 相似文献