共查询到19条相似文献,搜索用时 215 毫秒
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介绍了非安全级DCS平台的结构,将预期瞬态不停堆系统按功能划分,每个功能由输入模块、控制器模块、输出模块组成。研究了各种模块组合结构的可靠性参数及其串联组成的系统可靠性。针对多模块组合结构的马尔可夫模型过于复杂,计算量大的问题,提出了优化的建模方法。基于优化的马尔可夫模型,计算了3种数字量输入模块组合结构的拒动率和误动率指标,得出相同模块类型和数量的情况下,有软件表决逻辑的2种组合结构可靠性指标较高,而由硬件实现的组合结构可靠性指标较低的结论,为组合结构的选择提供了设计依据。 相似文献
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对百万千瓦级核电厂停堆运行事故进行内部事件1级概率安全评价(PSA),根据不同的停堆进程分别建立停堆PSA模型,分析经历余热排出系统(RRA)低运行区间(LOI-RRA)水位对电厂风险水平构成的影响;同时采用事故系列先兆标准电厂风险分析模型人员可靠性分析(SPAR-H)方法进行人员可靠性分析,评价其定量化结果的适用性。分析结果表明,停堆工况下的电厂风险不可忽视,在停堆工况下的事故规程有待完善之处,冷停堆工况下由LOI-RRA水位导致堆芯损坏频率明显增加,人因失误是造成停堆高风险的关键因素。 相似文献
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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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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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一、引言反应堆安全保护系统是确保反应堆安全运行的重要系统,一般由反应堆保护参数测量通道、通道综合逻辑单元和停堆继电器(或断路器)接点综合逻辑单元组成.合理设计反应堆保护系统的通道综合逻辑和停堆继电器接点综合逻辑对提高核电站运行的安全性和经济性有重大的现实意义.本文从可靠性角度对三种类型的反应堆保护进行分析比较,可供反应堆安全保护系统设计参考.为了简化定量计算工作量,作下列假定: 相似文献
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吸收球停堆系统在高温气冷堆中起到相当重要的反应性控制和调节作用。而驱动装置是吸收球停堆系统中控制吸收球下落的关键运动部件。高约5m、呈细长结构的吸收球停堆系统驱动装置通过贮球罐底座与金属堆内构件的上支承板安装面相连。吸收球停堆系统贮球罐和驱动机构均为抗震Ⅰ级设备,故驱动装置连接螺栓的抗震校核计算是非常重要的。在本文中,通过将复杂的驱动装置简化为3段变截面结构,分析结构的超静定问题,对驱动装置内贮球罐底部与顶部的螺栓进行了校核计算。计算结果表明:贮球罐底部与顶部螺栓均在抗拉强度的安全范围内,同时给出了驱动机构薄弱处的支承力。 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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高温气冷堆示范工程反应堆保护系统故障树模型的建立和分析 总被引:4,自引:4,他引:0
数字化保护系统正逐步取代模拟系统,应用于新建和升级的核电厂中,数字化保护系统的可靠性分析已成为仪控领域的热点研究课题。本工作以高温气冷堆示范工程(HTR-PM)的反应堆保护系统为研究对象,研究数字化保护系统故障树模型的建立和分析方法,主要研究内容包括:故障树顶事件的选取;基于失效模式与影响分析(FMEA)的故障树搭建方法,重点研究保护系统冗余通道的“2/4”表决逻辑以及通道旁通的处理方法;对故障树模型进行定性分析,并根据故障树的最小割集讨论保护系统的薄弱环节。该研究对于分析数字化保护系统的可靠性并改进系统设计具有重要意义。 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
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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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A level 1 probabilistic risk assessment of the Experimental Breeder Reactor 11 has recently been completed. Seismic events are among the external initiating events included in the assessment. The analysis indicated that the reactor shutdown system had a high reliability of operation in response to internally initiated events. One of the major tasks within the seismic assessment concentrated on the ability to shut down the reactor under seismic conditions. A comprehensive analysis of the shutdown system, including the development of a finite element model of the reactor control rod drive system, has been used to estimate the system response when subjected to input seismic accelerations. The results indicate the control rod driven system has a high seismic capacity and that the overall reactor shutdown system is capable of maintaining its high reliability under seismic conditions. The estimated seismic fragility for the overall reactor shutdown system is dominated by the primary tank failure. 相似文献
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从安全级数字化仪控系统(DCS)平台主控制器的功能特点、设备特点以及应用特点出发,结合相关法律法规及标准要求,对高可靠主控制器设计的诊断、冗余、通信、嵌入式软件开发等关键技术进行了研究,并将其应用于中国核工业集团有限公司安全级DCS平台——龙鳞系统(NASPIC)的主控模块设计中,同时搭建了华龙一号模拟件,并以停堆、专设、定期试验等典型样例对模拟件进行了功能测试和性能测试,这些测试和核安全局鉴定试验的结果表明,诊断覆盖率达到98%,超出标准要求;实测通信误码率小于10-11,达到甚至超过其他主流厂家安全级DCS产品指标;热备冗余架构、嵌入式软件均满足1E级设备要求,实现了主控制器的高可靠性。 相似文献
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《Annals of Nuclear Energy》2005,32(1):63-87
This paper presents the results of reliability analysis of Shutdown System (SDS) of Indian Prototype Fast Breeder Reactor. Reliability analysis carried out using Fault Tree Analysis predicts a value of 3.5 × 10−8/de for failure of shutdown function in case of global faults and 4.4 × 10−8/de for local faults. Based on 20 de/y, the frequency of shutdown function failure is 0.7 × 10−6/ry, which meets the reliability target, set by the Indian Atomic Energy Regulatory Board. The reliability is limited by Common Cause Failure (CCF) of actuation part of SDS and to a lesser extent CCF of electronic components. The failure frequency of individual systems is <1 × 10−3/ry, which also meets the safety criteria. Uncertainty analysis indicates a maximum error factor of 5 for the top event unavailability. 相似文献