核电厂风险指引型安全分级方法对比分析

核电厂物项安全分级是核电厂构筑物、系统和设备(SSCs)相关的各项管理和规定的基础。随着核电厂运维经验积累,逐渐发现传统确定论分级方法过于保守,存在优化的空间。风险指引型安全分级在传统分级的基础上应用概率安全分析技术,明确安全重要物项,优化核电厂物项分级。研究国内外风险指引型安全分级方法及其技术路线,梳理总结为设备分级方法、非能动管道部件分级方法,并开展方法对比分析与可行性分析。初步研究表明,我国核电厂具备开展风险指引型安全分级的基础,基于合理可行的方法实现物项分级的优化,在确保核电厂安全水平的前提下提升运维经济性。     

基于风险指引安全分级的维修规则实施方案

近年来,美国核电厂的业绩始终保持世界领先水平,维修规则的实施起了很大的作用.本文研究了美国核电厂实施维修规则的法规要求以及实施方法,结合我国正在研究中的风险指引安全分级及其处理方法,提出了适用于我国的核电厂维修规则实施方案.     

核电厂概率安全目标发展概述

定量的概率安全目标作为衡量技术安全目标是否被满足的重要指标,反映了各种假想事故情况下核电厂的可接受水平。目前,我国用于核电厂的风险衡量指标主要是堆芯损坏频率和大量释放频率,还没有针对三级概率安全分析的风险可接受性准则。本文梳理了国内外核电厂概率安全目标的发展动态,推荐了我国核电厂风险可接受水平的建议值,可为我国审管部门制定风险指引型管理导则提供参考,也可为全范围三级概率安全分析的开展提供评价依据。     

风险依据型决策方法在核电厂维修中的应用

分析了核电厂建立在事故分析确定论方法基础之上的运行技术规范 ,对维修实施过程进行核安全管理的局限性。介绍了 90年代后期在核电发达国家提出的风险依据 (Risk Informed)安全管理的决策原则 ,提出了在核电厂维修管理中应用风险依据决策的范畴和建议     

核电厂异常重要性判定(SDP)方法及其应用

在核电厂的日常安全管理过程中,核安全管理人员会遇到大量的安全事项,正确、快速和有效地处理这些事件和异常是保证核电厂安全运行的关键。目前核电厂和核安全监管机构都应用分级分类管理的方式来处理这些核安全相关事项,这样做可以使得安全重要度高的事项能够得到足够的关注,保证核电厂的总体安全水平。这种分级分类管理方式的重要的一环是能够正确地确定安全事项的安全重要程度。随着以概率安全分析(PSA)为代表的风险指引型安全管理方法的广泛应用,核安全管理人员可以利用风险重要程度来确定安全相关事项的重要程度。本文主要讲述了目前广泛使用的核电厂异常重要性判定方法(SDP)在开发及核安全管理中的应用,以及其对未来我国核安全管理带来的影响。     

非能动核电厂风险指引管理中的风险接受准则研究

由于非能动核电厂的风险水平较低,所以目前风险指引管理中的风险接受准则对其存在适用性问题.本文首先对现有的风险接受准则进行分析,然后针对非能动核电厂可能的风险可接受准则方案和现有接受准则的充分性进行描述,并对非能动核电厂风险准则中存在的大量放射性释放(LRF)问题进行研究,最后提出非能动核电厂风险指引管理中风险接受准则的...     

风险指引型技术在核电厂维修策略优化中的应用探索

利用概率安全分析技术来支持核电厂的日常风险管理及安全决策,已成为目前国际上的主流分析方法。本文采用概率论和确定论相结合的风险指引综合决策方法对RRI/SEC热交换器维修策略调整的可行性、合理性和安全影响进行论证,结果表明RRI/SEC热交换器的预防性维修项目可以在功率运行期间实施。应用风险指引型技术对维修策略调整,有助于提高维修工作安排的灵活性、优化大修资源配置、增强维修质量和设备可靠性,对机组安全稳定运行具有重要意义。     

风险指引型技术在核电厂设备检修策略优化中的应用研究

为了提高核电厂的经济性,核电厂通过对运行管理进行优化以提高其能力因子和运行灵活性,如优化大修期间设备检修策略以缩短大修工期。本文引入风险指引型理念对核电厂设备检修策略优化方法进行研究,并以某核电厂的余热排出系统热交换器检修策略调整为例,即内部表面目视检查由当前的每2年一列交叉检查变更为每4年检查顺序检查。使用该方法进行了详细的论证与计算。通过分析认为通过风险指引型技术方法对该电厂余热排除系统热交换器检查策略调整是合适的,能继续遵守纵深防御原则且不挑战核电厂的安全裕量,变更所引入的风险是可接受的。     

田湾核电厂3、4号机组风险指引型防水淹设计改进措施研究

针对内部水淹的防护,传统的确定论安全评价是从维持安全功能的角度定性分析内部水淹对机组核安全的影响,无法给出定量的风险评价。而核电厂风险指引型管理是以确定论分析为基础,利用概率安全评价的分析结果进行风险影响评价,以此来论证决策的合理性和必要性。本文基于田湾核电厂3、4号机组内部水淹概率安全评价分析结果,针对内部水淹风险贡献最大的汽轮机厂房循环水母管破裂的水淹情景,提出了3种设计改进方案,然后通过对各种改进方案进行了对比研究和评估,给出3种改进方案的优缺点及实施后对内部水淹堆芯损坏频率的影响,并给出了推荐的设计改进建议。     

核电厂维修规则分析与探讨

为满足核电厂实际生产及可持续发展的需要,更好地解决安全性与经济性之间的矛盾是关键,其中风险指引型技术是构建核电高效发展体系的重要支撑。2022年6月9日,新版HAF103正式发布,明确要求核电厂营运单位应当建立维修有效性评价体系,以保证核电厂构筑物、系统和设备能在设计基准规定的所有条件下有效执行其预定的安全功能。维修规则(MR)是核电厂风险指引型应用的一块重要基石,本文调研了核电厂维修规则的提出和发展,分析了MR与核电厂运维策略、MR与核电厂设备可靠性管理之间的关系,探讨了MR与大修优化之间的关系,相关内容可为MR的开发以及MR与现有体系的融合提供参考。     

浅谈风险指引型核安全法规体系

简要介绍了我国核安全法规的来历和发展现状,分析了现行核安全法规存在的不足。同时介绍了风险指引型安全管理方法的发展、现状以及所取得的成就,说明风险指引是核安全法规未来改进的方向。结合美国正在进行的构建风险指引型核安全法规体系的发展计划,讨论了新法规体系的原则及其特点。最后根据现实情况,就我国推行风险指引型安全管理和构建风险指引型核安全法规体系,提出了一些建议。     

Risk managed technical specifications

Application of probabilistic risk assessment (PRA) technology has become an essential component in the decision-making processes associated with the operation and regulation of commercial nuclear power plants (NPPs). As PRA technology has matured, it increasingly has been utilized to provide risk insights in the support of both operational and regulatory decision-making. This paper describes the next significant application of PRA technology to risk inform NPP operation. This Risk Managed Technical Specification (RMTS) application utilizes the results of the plant PRA to determine risk-informed technical specification (TS) allowed out of service times (AOTs). The RMTS process utilizes the PRA results to specify appropriate configuration specific TS AOTs and ensures the risk of events that could result in core damage or large early release are maintained below acceptable levels. In addition, RMTS requires development of integrated risk management actions to actively mitigate risks associated with the inoperability of TS structures, systems and components (SSCs). RMTS has been approved for implementation at commercial NPPs in the United States with the South Texas Project Electric Generating Station (STPEGS) serving as the initial application. In this paper we describe the programmatic requirements necessary to implement RMTS and provide several examples illustrating its application; thus demonstrating the applicability of RMTS to manage nuclear safety risk while simultaneously enhancing operational flexibility.     

A priori risk-informed approach to ensure the compliance with discharge limits for liquid radioactive effluent to be discharged from APR 1400

ABSTRACT

In order to develop a methodology to guarantee the conformance to operational discharge limits for liquid effluent from a NPP at an early stage of design, a risk-informed approach was proposed and its applicability was verified for APR 1400. Existing methodology to calculate risk-based detection limit for a single radionuclide was improved by incorporating a new model to derive more realistic pathway dose factors. A new simple expression was also proposed to adjust risk-based detection limits for multiple radionuclides mixture if necessary. In addition, a new procedure to warrant the compliance with discharge limits by controlling detection limits of only a few principal radionuclides was established in accordance with risk-informed concept. Through case studies for APR 1400 to be commissioned at a hypothetical site, it was shown that calculated pathway dose factors are more realistic for majority of radionuclides. It also turns out that neither present detection limits nor unadjusted risk-based detection limits can be justified when the radionuclide composition is unknown, however further adjustment of detection limits or increasing additional dilution factor resolves the problem. Finally, ten principal radionuclides were identified and shown to be enough for liquid effluent control at APR 1400 from a risk-informed point of view.     

福岛核事故后对我国核电厂应急控制中心抗震设防的思考

结合福岛核事故后对我国核电厂进行的核安全检查,分析了我国核安全法规关于核电厂应急控制中心的要求以及福岛核事故的经验教训,提出目前我国核电厂应急控制中心采用民用抗震设防标准进行抗震设防,无法保证在由地震引发的应急事故工况下应急控制中心的功能,应该适当提高其抗震设防级别。     

Implication of PSA uncertainties on risk-informed decision making

Nuclear power plants risk-informed policy is introduced in order to improve safety decision making and regulatory efficiency. The corresponding regulatory guides define the acceptable risk measures and their changes resulting from the modifications in the licensed design of the nuclear power plant. The risk measures used in the acceptance guidelines are the core damage frequency and large early release frequency.The risk measures and their corresponding changes are assessed by the Probabilistic Safety Assessment. The uncertainties of Probabilistic Safety Assessment should be appropriately addressed in the context of the decision making, considering their implication on the obtained results. The Probabilistic Safety Assessment uncertainties include epistemic uncertainties resulting from parameter, model, and completeness uncertainties.The paper presents the obtained results from the uncertainty analysis of the Probabilistic Safety Assessment of the reference nuclear power plant and their implication on risk-informed decision making. The paper focuses particularly on parameter and model uncertainties. The analysed modification is extension of the test interval of the emergency diesel generators. The core damage frequency is the used risk measure in the analysis.The need for the appropriate consideration of the uncertainties in the Probabilistic Safety Assessment in order to adequately support the risk-informed decision making is identified. The deficiency of usage of percentile measures is identified and acknowledged. The need for the adaptation of the risk-informed decision-making principles considering new nuclear power plants is recognized.     

我国核电厂规划限制区设置现状分析

本文简要概述了我国核电厂规划限制区的立法和管理文件情况,分析了现有核电厂规划限制区设置情况,提出了重视规划限制区的双面属性、推动规划限制区的管理条例建立、做好核电厂应急及事故环境影响评价分析和规划限制区整体区域规划等建议。     

Recent applications of PSA for managing nuclear power plant safety

The safety design and regulation of nuclear power plants has traditionally been based upon deterministic approaches that consider a set of challenges to safety, e.g. design basis accidents, and determine how those challenges should be handled. The approach has been very successful since no plant designed or regulated to United States standards has ever harmed a member of the public. The arbitrary nature of these safety criteria, the potential inconsistencies in the judgments on relative probabilities, and the lack of definition for ‘safety’ became increasingly evident during the 1960s. Probabilistic approaches to reactor safety were proposed ^1,2,3 but did not take off in the United States until publication of the Reactor Safety Study ⁴ in 1975. Even as the methodology matured, there remained a challenge to integrate it into the regulatory process. This article will describe this integration process. A probabilistic approach to regulation enhances and extends the traditional deterministic approach by introducing the concept of safety (risk) significance that allows the designer/operator to focus on important issues. Emphasis was initially placed on relative risk but now regulatory decision-making is employing both relative and absolute risk. Measures of importance will be defined. Risk information can be used to prioritize the allocation of resources and three examples will be described. Equipment configuration control systems are being installed and used at nuclear power plants to enhance safety and to reduce Operating and Maintenance costs; they will be described. Finally, the US Nuclear Regulatory Commission's introduction of risk-informed decision-making into the regulatory process will be discussed.     

事故状态评价在核事故应急决策中的应用

事故评价是核电厂应急状态下进行防护行动决策的重要技术基础.事故评价包括事故状态评价和事故后果评价两个方面.本文主要介绍事故状态评价技术在核事故应急决策中的应用情况.     

压水堆核电厂实时传输重要安全参数的规范化初步研究

核电厂实时安全参数传输和交换对于核电厂日常管理和应急响应都有重要的意义.基于相关法规标准要求和应急响应需要,结合各机组类型的具体参数,并考虑参数的可获得性,提出了相对统一的PWR核电厂实时传输安全重要机组参数和实时环境监测参数,为核电厂安全相关参数传输标准化工作提供了一定的技术基础.     

Safety management in NPPs using an evolutionary algorithm technique

The general goal of safety management in Nuclear Power Plants (NPPs) is to make requirements and activities more risk effective and less costly. The technical specification and maintenance (TS&M) activities in a plant are associated with controlling risk or with satisfying requirements, and are candidates to be evaluated for their resource effectiveness in risk-informed applications. Accordingly, the risk-based analysis of technical specification (RBTS) is being considered in evaluating current TS. The multi-objective optimization of the TS&M requirements of a NPP based on risk and cost, gives the pareto-optimal solutions, from which the utility can pick its decision variables suiting its interest. In this paper, a multi-objective evolutionary algorithm technique has been used to make a trade-off between risk and cost both at the system level and at the plant level for loss of coolant accident (LOCA) and main steam line break (MSLB) as initiating events.