Discussion of the paper: “Dynamic decoupling of secondary systems, by A.K. Gupta and J.M. Tembulkar, in: Nucl. Engrg. Des. 18 (1984) 359”

Technical aspects of seismic isolation systems show merit for their use in nuclear power plants. Less quantifiable non-technical aspects must be evaluated in the decision to employ a seismic isolation system.First, non-technical aspects are discussed. An historical and applications perspective is given, and it is suggested that the number of applications of seismic isolation systems is correlated with the amount of research activity in this area. For nuclear plants, it is suggested that application of seismic isolation systems is in part related to standardized plant designs in high seismic regions. Also, for nuclear plants, it is suggested that direct capital cost, enhanced seismic safety, regulatory licensing and unknown locations of nearby active faults are all factors which can weigh in favor and/or not in favor for seismic isolation application.Second, technical aspects are discussed. The technical results show that seismic isolation reduces building response, and reduces floor response spectra/equipment response. These results combine in application to reduce seismic risk and thus enhance safety for nuclear plants.     

Seismic safety of nuclear power plants in eastern Europe

This paper summarizes the work performed by the International Atomic Energy Agency in the areas of safety review and applied research in support of programmes for the assessment and enhancement of seismic safety in Eastern Europe and in particular, WWER type nuclear power plants during the past seven years. Three major topics are discussed; engineering safety review services in relation to external events, technical guidelines for the assessment and upgrading of WWER type nuclear power plants, and the Coordinated Research Programme on "Benchmark study for the seismic analysis and testing of WWER type nuclear power plants". These topics are summarized in a way to provide an overview of the past and present safety situation in selected WWER type plants which are all located in Eastern European countries. The main conclusion of this paper is that even though there is now a thorough understanding of the seismic safety issues in these operating nuclear power plants, the implementation of seismic upgrades to structures, systems and components are lagging behind, particularly for those cases in which re-evaluation indicated the necessity to strengthen the safety related structures or install new safety systems.     

Seismic protection technology for nuclear power plants: a systematic review

Seismic protection systems (SPS) have been developed and used successfully in conventional structures, but their applications in nuclear power plants (NPPs) are scarce. However, valuable research has been conducted worldwide to include SPS in nuclear engineering design. This study aims to provide a state-of-the-art review of SPS in nuclear engineering and to answer four significant research questions: (1) why are SPS not adopted in the nuclear industry and what issues have prevented their deployment? (2) what types of SPS are being considered in nuclear engineering research? (3) what are the strategies for location of SPS within NPPs? and (4) how may SPS provide improved structural performance and safety of NPPs under seismic actions? This review is conducted following the procedures of systematic reviews, where possible.

The issues concerning the use of SPS in NPPs are identified: cost, safety, licensing and scarcity of applications. NPPs demand full structural integrity and reactor's safe shutdown during earthquake actions. Therefore, horizontal isolation may be insufficient in active seismic zones and isolation in the vertical direction may be required. Based on the results in this review, it is likely that next generation reactors in seismic zones will include state-of-the-art SPS to achieve full standardised design.     

Issues in seismic isolation of nuclear power plants

The paper covers the issues involved in considering seismic isolation for nuclear plants. The application of isolation techniques to non-nuclear installations is discussed. Its potential application to nuclear components and plants is considered and the lack of actual, experimental verification of novel techniques is portrayed. Finally a cost comparison, based on certain preliminary assumptions of isolated and non-isolated nuclear plants is made.     

核电组织错误的表现与类型

通过访谈和事件再分析的方法，对影响核电安全的组织因素-组织错误进行探索。根据访谈记录和事件分析报告的编码，将得到的数据进行聚类分析，得到影响核电安全的5类组织因素。它们分别为：技术管理因素、非技术管理因素、信息界面、全局思想缺乏和组织计划。研究同时发现，相对于技术管理因素．非技术管理因素对系统安全的影响较大，因此，非技术培训对于系统的安全不可或缺。     

Seismic re-evaluation of nuclear facilities worldwide: overview and status

Existing nuclear facilities throughout the world are being subjected to severe scrutiny of their safety in the event of an earthquake. In the United States, there have been several licensing and safety review issues for which industry and regulatory agencies have cooperated to develop rational and economically feasible criteria for resolving the issues. Currently, all operating nuclear power plants in the United States are conducting an Individual Plant Examination of External Events, including earthquakes beyond the design basis. About two-thirds of the operating plants are conducting parallel programs for verifying the seismic adequacy of equipment for the design basis earthquake. The U.S. Department of Energy is also beginning to perform detailed evaluations of their facilities, many of which had little or no seismic design. Western European countries also have been re-evaluating their older nuclear power plants for seismic events often adapting the criteria developed in the United States. With the change in the political systems in Eastern Europe, there is a strong emphasis from their Western European neighbors to evaluate and upgrade the safety of their operating nuclear power plants. Finally, nuclear facilities in Asia are also being evaluated for seismic vulnerabilities. This paper focuses on the methodologies that have been developed for re-evaluation of existing nuclear power plants and presents examples of the application of these methodologies to nuclear facilities worldwide.     

Seismic analysis and design of electrical cable trays and support systems

Most cable trays in nuclear power plants are classified as seismic category I components. Current safety requirements dictate that all such components be adequately designed in order to remain functional during and after the most severe possible earthquake, so that a safe and orderly plant shut-down can be ensured. The design aspects of electrical cable trays and support systems are discussed from the seismic and structural standpoint. The effects of the inherent flexibility of commonly used cable trays is considered. A procedure for the selection of trays and the design of their support structure is recommended. The dynamic characteristics of typical trays are determined analytically and also from test results. The advantages of a rigid support system are discussed. Two procedures are presented for the design of the support systems, namely, static loading and spectral analysis. The interaction between trays and supports is discussed.     

Seismic isolation in New Zealand

Bridges, buildings, and industrial equipment can be given increased protection from earthquake damage by limiting the earthquake attack through seismic isolation. A broad summary of the seismic responses of base-isolated structures is of considerable assistance for their preliminary design. Seismic isolation as already used in New Zealand consists of a flexible base or support combined with some form of energy-dissipating device, usually involving the hysteretic working of steel or lead. This paper presents examples of the New Zealand experience, where seismic isolation has been used for 42 bridges, 3 buildings, a tall chimney, and high-voltage capacitor banks.Additional seismic response factors, which may be important for nuclear power plants, are also discussed briefly.     

集散控制系统在核电站保护系统中的应用

在核电站保护系统中应用基于数字化技术的安全级DCS已替代模拟技术成为主流,因为核电站的安全性要求很高,所以DCS技术的可靠性至关重要。为了确保应用DCS技术设计的可靠性,通过分析相关法规、标准的要求,总结了安全级DCS设计须进行的质量鉴定项及软件验证和确认过程,并结合当前主要应用的几个安全级DCS产品的技术特点,提出了安全级DCS设计开发中应考虑的控制器、智能IO模块、优选驱动模块以及通信等关键技术的要点。     

有关核电厂主给水系统设计的探讨

介绍了目前核电厂主给水系统隔离的几种设计方案，从事故进程和核电厂运行事件两个方面阐明了每种设计方案的优劣，得出了符合核安全原则的设计方案，这一分析对核电厂的设计和改造有一定的借鉴作用。     

浮动核电站跨界转运的安全和法律问题初步研究

浮动核电站具有模块化、多用途、可移动、运行灵活、适应性强等优势,受到了国际社会的广泛关注,具有广阔的应用前景和发展空间。然而,浮动核电站由于特殊的海外部署场景和可移动特性,不可避免地面临着跨越主权边界转运的安全和法律问题。结合浮动核电站不同的海外部署场景,重点对浮动核电站在不同部署场景下跨界转运可能面临的安全和法律问题进行梳理总结和讨论分析,并从法律、安保和应急层面提出可能的解决方案建议,对浮动核电站跨界转运相关的国际公约和规则制定具有一定参考意义。     

Nuclear Power Plant Compliance with the Principle of Power-System Indepedence from Safety Systems Operation

The purpose of this paper is to show that during the operation of safety systems at nuclear power plants the principle of independence from the power system, which is one of the basic principles inocrporated in the design of safety systems, is not satisfied and the power system, especially if it is deficient, cannot guarantee the required electricity and protection for safety systems from general failures. To satisfy the independence principle, guarantee the required quality of electricity, and protect the safety systems in nuclear power plants from general failures, it is proposed that the presently operative algorithm for starting up diesel generators be reexamined. When the safety systems at nuclear power plants perform their required functions, they should operate from autonomous diesel generators at the nuclear power plant, which are equipped with electricity quality regulators (frequency and voltage), and not from the power system. It is also suggested that the variant of the algorithm where diesel generators are started up as a preventative measure when the quality of the electricity in the power system drops below admissable limits be reexamined.     

不同法规关于核电厂设计地震动合成的技术要求比较

详细介绍了我国核电厂地震安全评价及抗震分析与设计中用到的多部国内外的法规、标准和导则的技术规定,对其技术背景和要求进行了深入比较和分析,结合工程实践给出了相关的评述和应用建议.     

New Zealand seismic base isolation concepts and their application to nuclear engineering

This paper describes recent New Zealand experience with seismic base isolation, and in particular, the distinguishing feature of the New Zealand system - that of using mechanical energy dissipators to control response.There are presently 22 structures in New Zealand which use base isolation concepts for seismic protection. Nuclear power plants are not used in New Zealand, but the principles adopted for the above buildings and bridge structures are appropriate for nuclear structures and, as shown by use of hypothetical examples, significant benefits can be achieved for these structures also. The most important is a marked reduction for the in-structure acceleration spectra with consequential implications for the enhanced safety of secondary structures and equipment.The paper also reviews the experimental and analytical studies undertaken to validate the technique and addresses the issues of reliability and cost.     

核电厂地震PSA中的风险定量化研究

论述了核电厂地震概率安全评价（PSA）定量化方法和工具的现状,指出了定量化工具面临的挑战和存在的问题。根据定量化的概率论本质,提出了计算方法。以我国某核电厂厂址多方案概率地震危险性分析（PSHA）结果和核电厂地震响应分析给出的最小割集为例,展示了计算方法的应用过程,分析了地震动参数和置信度参数对定量化计算结果的影响。结果表明,针对置信度参数进行拉丁超立方采样,采样次数较小时即可给出地震导致的核电厂堆芯损坏频率（SCDF）的稳定估计值;通常情况下,设备失效对SCDF的贡献最大,厂房失效的影响相对较小;地震动年发生率对SCDF的贡献需要根据工程场地的位置进行具体分析。      

Recent tendency of the practice of soil-structure interaction design analysis in Japan and its theoretical background

Many methods of soil-structure interaction analysis for design calculations of nuclear power plants are available. The validity of methods has often been examined by their application to simulation analysis of shaker tests or seismic observations of nuclear power plant buildings, and forced vibration tests of large-scale foundation blocks. In this paper, such simulation analyses performed in Japan are reviewed and discussed for their practical applications.     

利用HHT产生与多阻尼楼板谱匹配的地震波

美国原子能管理委员会（USNRC）规范规定了用于核电厂抗震分析和设计的地震波要求。在抗震分析和设计中，采用的地震波可与多阻尼目标反应谱匹配，也可与单阻尼目标反应谱匹配。然而，在对核电设备和部件进行动力时程分析时，则需要与多阻尼目标楼板谱匹配的地震波。基于此问题，提出利用希尔伯特-黄变换（HHT）方法，通过修改种子地震波的频率和振幅信息，使之与多阻尼目标楼板谱匹配，且完全符合USNRC规范的匹配标准，从而为核电设备和部件的地震安全评估提供合适的地震激励。      

核电站应急指挥中心基底隔震技术方案

日本福岛核电站事故之后,中国国家核安全局正式发布《福岛核事故后核电厂改进行动通用技术要求》,提高了核电站应急指挥中心的抗震安全要求。本文以防城港核电站应急指挥中心示范项目为分析对象,探讨了采用橡胶支座作为隔震装置的基底隔震方案,并进行了隔震效果评价。通过采用43个橡胶隔震支座,可以显著地削弱地震响应,提高应急指挥中心的抗震裕量。通过该技术方案可以保护应急指挥中心的人员、设备和系统的安全,从而提升核电站震后应急能力。分析研究成果和工程实践经验可在后续核电站建设中推广应用。     

核电厂地震易损性分析模型研究

福岛核事故发生后,我国要求开展外部事件对核电厂影响的评价,“十二五”核安全规划要求2015年之前开展外部事件概率安全分析工作。地震是需要重点评价的外部事件之一,而地震易损性分析是地震概率安全评价（SPSA）的一项重要内容,易损性分析模型是地震易损性分析的基础。本文介绍了地震易损性的概念,研究了美国核管会（NRC）和电力研究院（EPRI）推荐的地震易损性模型,并从数学上对该模型进行推导。给出易损性模型的应用实例,讨论随机性和不确定性对易损度的影响。结果表明,进行易损性分析时,需拥有丰富的知识和经验,以减少不确定性,使得到的分析结果更接近实际。     

Soil-structure interaction of nuclear reactor structures considering through-soil coupling between adjacent structures

The theoretical problem concerning the influence of through-soil coupling between adjacent structures on the seismic loading of nuclear reactors has been investigated by considering a soil-structure interaction model in which several three-dimensional flexible structures are bonded to an elastic half-space. These structures, which are allowed to be either similar or dissimilar, are modeled as conventional discrete systems mounted on separate base slabs of close proximity. For the purpose of this study, it is assumed that the stiffness of any structure such as piping connecting the adjacent buildings is negligible.For purposes of comparison, the seismic responses of structural masses are determined both with and without the influence of nearby structures. Both transient and steady-state results are presented and discussed for some typical simplified two- and three-structure complexes. Emphasis is placed on the effects of through-soil coupling on the dynamic response of the system rather than actual magnitudes of response which have previously been treated for plants erected on a single base slab. The significant findings are that nuclear power plants can be designed to achieve a reduction in seismic loads due to interaction with neighboring structures. Conversely, improper plant design and layout may result in mutual reinforcement of resonances with increased loads.