Evaluation of nuclear facility decommissioning projects program-status

Major studies have been undertaken in recent years by the US Nuclear Regulatory Commission (NRC) and others on the technology, safety and costs associated with decommissioning nuclear facilities. The program described in this presentation is being undertaken by the NRC to compile and evaluate the activities of ongoing decommissioning projects. Assessment and evaluation of the methods, impacts, and costs will provide a basis for evaluating licensee's decommissioning proposals and for future decommissioning direction and regulation.Program participants include the US Nuclear Regulatory Commission (NRC) through the Office of Regulatory Research, UNC Nuclear Industries (UNC) through the Decommissioning Programs Department, and nuclear facility licensees.     

Multi-agent-based anticipatory control for enhancing the safety and performance of Generation-IV nuclear power plants during long-term semi-autonomous operation

The use of multi-agents and anticipatory control to improve the performance and safety of nuclear power plants is discussed. The propose program seeks to advance and test via simulation a new control approach for the long-term semiautonomous and economically competitive operation of Generation-IV nuclear power plants. The approach exploits a simple but potentially powerfull idea: In order to regulate themselves in a semi-autonomous manner and be protected from potential anomalies, Generation-IV plants should act proactively, that is, effect control in anticipation of (not just in response to) potential contingencies. It is proposed to envelop the plant with two anticipatory control blankets, one pertaining to problems emerging due to wear and fatigue, and the other pertaining to unanticipated design basis events. Nuclear power plants are by their design well suited for the application of intelligent agents to carry out the safety assurance functions as they are well instrumented for purpose of defining their safety status. Each of the monitoring and control subsystems can be “agentized; i.e., legacy (existing) codes can be encapsulated in an agent “wrapper”, enabling critical information to be autonomously distributed to any agent that needs it to perform its prescribed task.     

Graded approach to establish QA requirements for type B and fissile material transportation packagings

Abstract

The essence of the graded approach is the establishment of applicable quality assurance (QA) requirements to an extent consistent with the importance to safety of an item, component, system or activity. The genesis of the graded approach is a study conducted by the US Nuclear Regulatory Commission (NRC) for the US Congress in 1987 to assess the effectiveness of QA activities. That study demonstrated the need to improve the application of QA requirements for the nuclear industry in general. The conclusion of the study indicated that a graded approach for establishing QA requirements is the most viable method to satisfy federal safety standards that result in protecting public health and safety. The application of QA requirements for type B and fissile material transportation packagings is not based solely on importance to safety or safety related considerations. The operability of items, components, systems and activities is considered to be equally important. The nuclear industry, along with regulatory agencies, recognises the significance of operability considerations, as well as the evaluation of each item, component, system or activity for safety related considerations. The graded approach for QA requirements for type B and fissile material transportation packagings is based on Title 10, Part 71 of the US Code of Federal Regulations (CFR), ‘Packaging and transportation of radioactive material.’ Guidance for implementation of the QA requirements specified in §71 is provided in NRC Regulatory Guide 7·10, ‘Establishing quality assurance programmes for packaging used in transport of radioactive material,’ and ASME NQA-1, ‘Quality assurance requirements for nuclear facility applications’. The graded approach for QA requirements is based on criteria for containment, shielding and subcriticality specified in 10 CFR Part 71.     

VVER机组松脱部件监测系统设计差异及功能验证

介绍了田湾核电站水-水高能反应堆（VVER）机组松脱部件监测系统（LPMS）的设计和设备结构组成，描述了其设计与美国核管会（NRC）RG1.133相关条款要求的差异。基于这些差异以及VVER机组的特殊性，分析了拟采取的改进措施存在的困难和不利影响。为执行与NRC RG1.133中安全要求相当的功能，在田湾核电站3号机组调试阶段开展了LPMS系统的功能补充试验，获取与压力容器相关的传感器信号的响应，验证了目前的传感器布置方式能满足NRC RG1.133的设计要求。      

Implementation of maintenance rule for structures

The maintenance rule, 10 CFR 50.65, ‘Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants’, was published by the Nuclear Regulatory Commission (NRC) in the Federal Register (56 FR 31324) on July 10, 1991. The rule became effective on July 10, 1996, giving nuclear power plant licensees 5 years to implement it. During 1994–1995, NRC staff visited nine nuclear power plant sites to observe licensees’ preparations for implementation of the rule. The teams found that most of the licensees had not established goals, or performance criteria for monitoring structures at their sites. The licensees contended that the structures were inherently reliable and required no monitoring under the maintenance rule. On the basis of earlier site visits performed by NRC staff to assess the condition of structures, the NRC staff could not accept this contention, and clarified its position in Revision 1 of Regulatory Guide 1.160, ‘Monitoring the Effectiveness of Maintenance at Nuclear Power Plants’. This paper discusses the applicability of the maintenance rule criteria for structures and its usefulness in ensuring that the structures, systems, and components within the scope of the maintenance rule are capable of fulfilling their intended functions. Also discussed are the aspects of maintenance rule efforts that could be useful for license renewal applications.     

Westinghouse AP1000 advanced passive plant

The Westinghouse AP1000 Program is aimed at making available a nuclear power plant that is economical in the US deregulated electrical power industry in the near-term. The AP1000 is a two-loop 1000 MWe pressurizer water reactor (PWR). It is an uprated version of the AP600. Passive safety systems are used to provide significant and measurable improvements in plant simplification, safety, reliability, investment protection and plant costs. The AP1000 uses proven technology, which builds on over 35 years of operating PWR experience. The AP1000 received Final Design Approval from the United States Nuclear Regulatory Commission in September 2004; the AP1000 has also received Design Certification by the USNRC in December 2005. The AP1000 and its predecessor AP600 are the only nuclear reactor designs using passive safety technology licensed anywhere in the world. The safety performance of AP1000 has been verified by extensive testing, safety analysis and probabilistic safety assessment. AP1000 safety margins are large and the potential for accident scenarios that could jeopardize public safety is extremely low.Simplicity is a key technical concept behind the AP1000. It makes the AP1000 easier and less expensive to build, operate, and maintain. Simplification also provides a hedge against regulatory driven operations and maintenance costs by eliminating equipment subject to regulation. The AP1000's greatly simplified design complies with NRC regulatory and safety requirements and the EPRI advanced light water reactor (ALWR) utility requirements document.Plans are being developed for implementation of the AP1000 plant. Key factors in this planning are the economics of AP1000 in the de-regulated US electricity market, and the associated business model for licensing, constructing and operating these new plants.     

Condition telemonitoring and diagnosis of power plants using web technology

The monitoring and diagnostic systems currently installed in power plants generally supply information for control room displays and for on-site personnel. Telemonitoring is also frequently used. In this case, relevant diagnostic data are transmitted remotely to a special laboratory for analysis using highly specialized equipment and software.

The appearance of the terms “Monitoring” and “Diagnosis” alongside the term “Web Technology” in the title of this paper does not mean that remote access to diagnostic systems over the Internet is being presented here as a simple extension of the existing situation.

Condition telemonitoring and diagnosis based on Web technology is a new departure in diagnostic system design philosophy. It is the technology used to integrate diagnostic systems into a customer's IT infrastructure (Intranet or Internet).

Siemens has started to use Web-based condition telemonitoring and diagnosis in some power plants (nuclear and fossil-fueled) to provide a global source of specialist support.     

Safety of ocean shipments of plutonium between Europe and Japan

Abstract

Sandia National Laboratories (SNL) has conducted an extensive study of emergency response planning applicable to sea transport of plutonium for the Japan Nuclear Cycle Development Institute (JNC). This work covered four separate areas to better define the accident environment for long range sea transport of nuclear materials. A probabilistic safety analysis evaluated technical issues for the transport of plutonium between Europe and Japan. An engine room fire aboard a purpose built ship was used to analyse the vulnerability of plutonium packaging designed to International Atomic Energy Agency (IAEA) standards. A comprehensive corrosion study estimated the time required for sea water to breach a containment boundary in submerged generic plutonium packaging. A survey of worldwide commercial recovery capabilities provided a compilation of information on the capabilities of salvaging high value cargo from sunken ships. This paper addresses salvage modes from harbour depths to the deepest ocean trenches. Previous studies (J. L. Sprung et al., SNL reports SAND98-1171/1 and SAND98-1171/2, May 1998) included a probabilistic risk assessment of the overall safety, source term evaluations and finite element structural dynamics calculations to determine the effects of ship to ship collisions on nuclear material containers and the effects of ship fires on transport packaging as determined by actual fire experiments conducted on board a test ship. The previous studies, together with this work, form a comprehensive technical basis that encompasses the overall safety of sea transport of plutonium between Europe and Japan. Based on these technical analyses, transport of nuclear materials by sea in Type B packaging, approved in accordance with US Nuclear Regulatory Commission (NRC) and IAEA regulations, and carried in purpose built ships with adequate surveillance, has a very high degree of safety for the failure modes studied. Non-purpose built ships do not have the redundancy in safety features provided by the newer purpose built ships. However, SNL studies on non-purpose built ships have shown accident environments to be within NRC and IAEA regulatory assumptions for Type B packaging. These studies were carried out for both structural ship to ship collisions and engine room fires by analysis (for the collisions) and direct experimentation and analysis (for the fires). Thus, land transport mode regulations are applicable for sea transport accident conditions.     

The modular high temperature gas-cooled reactor (MHTGR) in the U.S.

The MHTGR is an advanced nuclear reactor concept being developed in the USA, under a cooperative program involving the U.S. Government, the nuclear industry, and the utilities. As its objective, this program is developing a safe, reliable, and economic nuclear power option for the USA, and the other nations of the world to consider in meeting their individual nationalistic electrical generation or process heat needs by the turn of the century. The design is based on a concept of modularization that can meet the various power needs by combining any number of 350 MW(t) reactor modules in parallel with a selected number of turbine plants in a variety of arrangements. Basic HTGR features of ceramic fuel, helium coolant, and graphite are sized and configured to provide a low power density core with passive safety features such that no operator action or external source of power is needed for the plant to meet 10CFR100 or Protective Action Guidelines limits at the 425 m site boundary. This precludes the necessity to plan for the evacuation or sheltering of the public during any licensing basis event. The safe behavior of the reactor plant is not dependent upon operator action and it is insensitive to operator error. The Conceptual Design is presently being vigorously reviewed by the U.S. Nuclear Regulatory Commission (NRC). A safety evaluation report and a licensability statement are scheduled for issuance by the NRC in January 1988.     

基于国产化PXI模块的松脱部件监测系统软件开发

基于国产化PXI（面向仪器系统的PCI扩展）模块,利用中国核动力研究设计院（NPIC）研制的国产化松脱部件监测系统（LPMS）进行了16通道LPMS软件的开发,本文主要介绍了软件设计要求、设计原则、设计流程,以及主界面的设计,并重点对国产化PXI控制模块接口程序的软件实现进行了详细阐述。开发的基于国产化PXI模块的LPMS软件经测试满足设计要求,并已成功应用在出口国外某核电厂的LPMS中,为保障核电厂安全经济的运行起到了积极的作用。      

核电厂功率工况异常重要性判定模型的开发

核电厂异常重要性判定程序（SDP）是由美国核管会（NRC）首先使用的一种基于风险指引型的安全事项重要性判定工具。运用此方法,核安全监管人员对核安全相关事项进行筛选和评估,进而给出其风险重要性程度。本文对已有的PSA模型进行简化,开发了功率工况SDP第2阶段判定模型,对该模型进行了验证。验证结果表明,该模型满足核安全监管人员的使用要求,能够对核电厂事项进行快速有效的风险重要性判定。     

Seismic qualification of systems, structures, equipment and components

The purpose of this paper is to give an overview of the various qualification procedures available to the vendors of nuclear power plants and equipment for hopefully achieving NRC (Nuclear Regulatory Commission) plant licensing and overall guaranteed safe operation. These procedures usually involve computer-aided analyses for large systems and structures, but trend toward shaking table tests for small equipment and components.The dynamic analysis and testing required for seismic qualification can be covered in a practical manner by reference to several pertinent Regulatory Guides and Standards. They have been issued by the NRC on specific subjects, but often represent a consensus of more general standards prepared by ASME, IEEE, ASCE, ANSI and NEMA. These documents cover such diverse subjects as (a) reactor site criteria, (b) seismic design limits and loading combinations, (c) system damping values, and (d) recommended vibration test practices.The author has been directly concerned with IEEE Std 344 on seismic qualification practices and has therefore included the latest ideas and suggestions for revising this document. In general, there has been a continuing escalation in the g-level of seismic requirements. This present overview indicates a need for R&D work and re-examination of published documents to counterbalance unwarranted conservatism.     

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.     

Nuclear regulation in transition

This article examines the current state of nuclear regulation. Since Three Mile Island the regulation of the nuclear power industry has been undergoing a noticeable transition. It will be argued here that the transition is characterized by two indicia. First, the primary focus of state and federal regulators has been on the financial aspects of the industry: this is best seen in the context of decisions allocating the costs of nuclear plant cancellations. Second, decisionmaking power has been decentralized: although the regulatory history of nuclear power demonstrates the tradition of centralized decisionmaking power (i.e., formerly the primary decisionmaking body was the Atomic Energy Commission), now states share decisionmaking power with the Nuclear Regulatory Commission. In Section 1 a brief legislative history of nuclear regulation is presented to establish the assertion that nuclear regulation, both de jure and de facto, was centralized. Next, Section 2 canvasses recent United States Supreme Court opinions regarding nuclear regulation. The Court frequently acts as policymaker through the consequences of its opinions, if not by its intent. In the area of nuclear policymaking, the Court has paid allegiance recently both to the tradition of centralization and to the movement toward decentralization. This dualism is reflected in other federal court decisions as well which will be briefly mentioned. Continuing the analysis of federal regulation, Section 3 examines the current reform efforts of the NRC. Section 4 presents an examination of state responses to nuclear plant cancellations. In this section, state administrative agency and court decisions will be examined and recent state legislation will be discussed.     

日本福岛第一核电站事故源项及后果评价

根据已有的日本福岛第一核电站相关资料,利用美国核管理委员会《轻水堆核电厂事故源项》中的假设条件,计算出事故后安全壳内的放射性源项,综合考虑各种不确定性因素,得出较为保守的环境释放源项。采用美国核管理委员会RG 1.4中大气扩散模式的假设计算大气弥散因子,并应用ICRP 71号出版物F、GR 12号报告等资料中的剂量计算...     

U.S. regulatory perspectives on the back end of the fuel cycle: EUROSAFE 2013 proceeding

For the United States Nuclear Regulatory Commission and the reactor licensees it regulates, there are a number of contemporary issues associated with the back end of the fuel cycle including, the agency's revision to its “Waste Confidence” decision and the path-forward for high-level waste disposal. Additionally, the 2012 Blue Ribbon Commission on America's Nuclear Future recommendations, the future of reprocessing, consolidated interim spent fuel storage, and maintaining technical competence within the NRC in challenging budgetary conditions are addressed. I conclude that there is confidence in the feasibility of safe storage of spent nuclear fuel following the licensed operational life of a reactor and any change in high-level waste policy will require Congressional action to amend the Nuclear Waste Policy Act.     

The Stuttgart positron beam, its performance and recent experiments

A monoenergetic MeV positron (e⁺) beam, with a flux at present of 6 × 10⁴ e⁺/s in the energy range of 0.5 to 6.5 MeV, has been installed at the Stuttgart Pelletron accelerator. The stabilization and the absolute calibration of the energy E is monitored by a Ge detector with real-time feedback; a relative energy stability of ΔE/E 10⁻⁴ is obtained. So far, e⁺e⁻ scattering and annihilation-in-flight experiments for investigating the low-energy e⁺e⁻ interaction as well as β⁺ γ positron lifetime measurements in condensed matter have been performed. The advantages of the β⁺ γ method compared to the conventional γγ coincidence technique have been demonstrated. Recently, triple-coincidence positron “age-momentum correlation” measurements have been carried out on fused quartz. A brief account is given on the development of a “positron clock” aiming at a substantial improvement of the time resolution of the β⁺ γ positron lifetime measurements.     

先进轻水反应堆核电厂取消运行基准地震的原因和措施

在先进轻水反应堆业主文件(ALWR-URD)中提出对核电厂抗震设计取消运行基准地震(OBE)的要求,其观点是没有必要执行OBE和SSE两套完整的抗震分析方法.美国核管理委员会(NRC)有关部门也讨论了从安全停堆地震(SSE)如何消除OBE影响的问题,认为OBE不应当控制安全系统的设计,并根据过去核电厂抗震设计研究与经验编制了相应的备忘录,于1993年得到NRC批准.本文根据该备忘录内容整理了两大问题:取消OBE的背景和原因,取消OBE后所采用的措施和方法.并从核电厂构筑物、管道、支承件、设备以及电厂震后决策等几方面的抗震要求进行了论述.     

Risk-informed inservice inspection program

The Nuclear Regulatory Commission (NRC) has developed draft guidance for power reactor licenses on acceptable methods for using probabilistic risk assessment (PRA) information and insights in support of plant-specific applications to change the current licensing basis (CLB) for inservice inspection (ISI) of piping. This process is also known as risk-informed inservice inspection programs (RI-ISI). The risk-informed inservice inspection process for operating nuclear power plants provides an alternative method for selecting and categorizing piping components that are inspected for the purposes of meeting the requirements of ASME Section XI. A RI-ISI approach will incorporate probabilistic techniques to help define the scope, type and frequency of inservice inspection. The risk-informed process may support a decrease in the number of inspection and inspection intervals but will also identify areas where increased resources should be allocated to enhance safety. The approach discussed in this paper follows the method developed by NRC staff.