Nuclear Executive Update

Transcription

1 Nuclear Executive Update An EPRI Progress Report May 2008 The Nuclear Executive Update is published bi-monthly. If you have comments about the newsletter, please contact Brian Schimmoller, EPRI Research Not in a Vacuum Building off the March newsletter, where we touched on EPRI s engagement with nuclear-related business and operational entities, in this issue we ll explore our engagement with nuclear-related research entities. Active interaction with these organizations enables EPRI to clearly delineate its areas of responsibility, avoid duplication of effort, and identify opportunities for collaboration. Two 2008 EPRI initiatives capture the essence of our external engagement. EPRI interviews in late 2007 with more than 20 U.S. nuclear power plant owners/operators revealed that more than 85% believe plant operation beyond 60 years is not only extremely desirable, but at least somewhat likely. On the heels of an EPRI-INL (Idaho National Laboratory) effort documenting the strategic R&D needed to fulfill the promise of light water reactor technology as a near-zero emission electricity source, EPRI participated in a joint Nuclear Regulatory Commission/Department of Energy workshop in late February to examine research needs pertaining to life after 60. A steering committee comprising EPRI, the Department of Energy, INL, the Nuclear Regulatory Commission, and the Nuclear Energy Institute will be evaluating and prioritizing research opportunities. EPRI is launching a Long-Term Operation research program this year to maximize the use of existing nuclear assets, focusing on nuclear plant materials, instrumentation and information systems, and long-term asset management. The Materials Aging Institute, founded in January by EPRI, EDF and Tokyo Electric Power Company, concentrates nuclear and technical expertise at research organizations and universities around the world to examine the critical link between materials science and power plant component performance and degradation. This critical activity will support many broader strategic R&D goals, including new plant deployment and the Long-Term Operation program. EPRI will help guide research priorities, while gaining access to research findings with global impact. EPRI has assigned a full-time researcher, Dr. Mohamad Behravesh, to MAI on-site in France, and will be rotating additional staff through the facility for short-term assignments. External EPRI engagement with research organizations spans many other technical areas and many countries. Nuclear Regulatory Commission (NRC): Although research efforts by NRC and EPRI may be conducted for different purposes, the underlying data and results often have common value. To conserve resources and avoid duplication, NRC and EPRI have agreed to cooperate in selected research and to share information and costs related to this research where mutually beneficial. Nuclear Steam Supply System Owner s Groups: Dialogue and coordination with the PWR Owner s Group and the BWR Owner s Group to establish protocols for sharing intellectual property, to better integrate the competencies of each research organization, and to ensure research overlap is avoided. Nuclear Executive Update: 1

2 Korea Electric Power Research Institute (KEPRI): Collaboration on selected nuclear issues, including nondestructive evaluation and materials reliability, to capitalize on the two organizations complementary technical capabilities. In August 2007, KEPRI and EPRI signed a three-year agreement in which EPRI will provide technical support to Korean efforts to establish a performance demonstration system for dissimilar metal welds. Idaho National Laboratory: With EPRI and other industry partners, INL established the Center for Nuclear Fuels and Materials Research, which focuses on the evaluation and development of fuels and cores for light water reactors, leveraging unique fuel analysis facilities at INL. Joint efforts also are underway in digital instrumentation and control, nondestructive evaluation technology, and advanced fuel cycles. Nuclear Fuel Industry Research (NFIR): This ERPI-led international collaborative ensures safe and reliable use of nuclear fuel materials and reactor core components through fundamental understanding of in-reactor behavior. More than 50 organizations from 14 countries have participated in NFIR. Cooperative IASCC Research (CIR) Program: This EPRI-managed global research program increases technical understanding of irradiation assisted stress corrosion cracking. Membership includes utilities, regulators, vendors and research organizations from the United States, France, Spain, Sweden, Belgium, and Japan. EPRI engages many other nuclear research-related entities as well, including the Organization for Economic Cooperation and Development/Committee for Safety of Nuclear Installations, the French Atomic Energy Agency, the CANDU Owner s Group, and the Central Research Institute of Electric Power Industry (CRIEPI-Japan). As nuclear research priorities shift over time, EPRI will refine these relationships and develop new ones to ensure the most effective combination of resources are applied to identify and implement solutions. For more information on any of EPRI s external engagement efforts, please contact me or Dave Modeen, who is responsible for our external affairs activities. Sincerely, Chris Larsen Vice President and Chief Nuclear Officer EPRI Nuclear Sector EPRI will host a workshop on advanced cooling technologies for thermal power plants on July 8-9 in Charlotte, N.C. Attendees will discuss research and development opportunities to increase power plant water use efficiency and reduce water consumption. More information is available at: id= Nuclear Executive Update: 2

3 TECHNICAL HIGHLIGHTS Rapid Response to St. Lucie Pressurizer Indications Keeps Eight Units On-Line Nondestructive Evaluation of Pressurizer Nozzles Reveals Fabrication Defects in the Welds, but no Significant Stress Corrosion Cracking. EPRI provided a coordinated and rapid response to U.S. Nuclear Regulatory Commission concerns regarding ultrasonic indications in the safety nozzles of a retired pressurizer from the St. Lucie nuclear power plant. The effort avoided immediate, unscheduled shutdowns at eight U.S. pressurized water reactor (PWR) units. Florida Power & Light donated the pressurizer to the NRC Office of Regulatory Research, which planned to perform round-robin experiments and destructive evaluation to obtain information on NDE capabilities. A manual phased array ultrasonic (UT) procedure coordinated by EPRI in February 2008 identified 360 circumferential indications as possible primary water stress corrosion cracking (PWSCC) or stacked fabrication defects. A dye penetrant examination of the inside surfaces of the nozzles, on the other hand, identified only a few, short indications. The NRC Office of Nuclear Reactor Regulation (NRR) concluded that the indications if confirmed as PWSCC could invalidate the results of the advanced finite element analysis (FEA) performed by the Materials Reliability Program (MRP) in 2007, which established the basis for continued operation of nine PWRs until their scheduled Spring 2008 outages. On Friday, March 7, NRR senior management indicated their intention to shut down eight of the nine PWRs the following week for inspection or mitigation of the pressurizer nozzle welds (one of the nine PWRs was already in an outage). Beginning at midday on March 7, EPRI organized detailed characterizations of the three safety nozzles using diverse NDE techniques, to be followed by destructive examination. Quick action was critical to provide NRR with information that could justify a decision not to force the unscheduled shutdowns. Nondestructive Evaluation of the St. Lucie Pressurizer using Encoded Phased Array UT Studsvik, which operates the Memphis facility housing the St. Lucie pressurizer, mobilized to provide immediate, 24/7 facility and health physics support for the NDE activities. Three EPRI NDE staff arrived in Memphis on Saturday afternoon with ultrasonic, eddy current, and dye penetrant equipment; a fourth arrived on Sunday. Vendor LMT arrived on-site Saturday afternoon to perform a manually encoded, phased array ultrasonic examination. Vendor Ivey-Cooper arrived Sunday to perform single-wall and double-wall radiographic examinations. Vendor WesDyne arrived on Wednesday to perform an automated eddy current examination on the inside surface of the nozzles using a specially designed tool for control rod drive mechanism nozzles. A utility representative, an NRC representative, and an NRC NDE consultant were onsite to observe. By Monday, March 10, EPRI reported to the industry, and the industry to NRC, that the encoded UT imaging results clearly indicated that the three safety nozzles contained extensive fabrication defects in the welds, but no significant PWSCC. Radiographic and eddy current examination results on Tuesday and Wednesday confirmed this result. On Thursday, March 13, NRC held a public meeting in which EPRI and industry representatives explained the NDE findings. On Friday afternoon, one week after the start of the rapid-response effort, NRC approved continued operation of the eight affected PWR units until their scheduled Spring 2008 outages. Nuclear Executive Update: 3

4 EPRI delivered a written report of the NDE activities to NRC on Wednesday, March 19, as MRP communication A destructive examination report, documenting the results of hot lab testing conducted on one of the nozzles removed from the pressurizer head, will be completed in May. EPRI is also conducting a self assessment of the St. Lucie experience to identify lessons learned and implement improvements through EPRI s quality program and continuous improvement processes. Contact: Greg Selby, , gselby@epri.com EPRI Completes Materials Management Matrix for ESBWR Matrix Information Guides Materials-Related Design Improvements; AP1000 and EPR Designs are Next. Operating plant experience can guide design improvements for advanced light water reactors to better manage materials performance issues. Implementing mitigation or management technologies can significantly reduce operating costs over the life of these new plants by avoiding degraded conditions, facilitating more efficient and accurate inspections, and reducing repair and replacement costs. The Advanced Nuclear Technology Program s materials management initiative identifies gaps and opportunities that, if addressed at appropriate times in the life cycle of the new plants, will significantly improve plant materials performance. In April 2008, EPRI published the Materials Management Matrix for GE-Hitachi s ESBWR design. This matrix provides information guiding identification and evaluation of materials issues, and identifies mitigation and management opportunities from the design phase through component fabrication and plant construction to operations and maintenance. In a series of tables, the ESBWR report prioritizes 58 gaps and opportunities to mitigate or manage potential material degradation issues. The results highlight two primary strategic materials performance issues associated with advanced light water reactor deployment: improved materials processing and fabrication technologies that may retard initiation of stress corrosion cracks; and a comprehensive and integrated strategy for component nondestructive evaluation, from pre-service inspections through periodic in-service inspections. EPRI will develop similar Materials Management Matrix products for the Westinghouse AP1000, AREVA EPR, GE-Hitachi ABWR, and Mitsubishi Heavy Industries U.S. APWR designs. The AP1000 and EPR projects should be completed by December The ESBWR Materials Management Matrix, EPRI Report , is available for download at EPRI.com. Contact: Tom Mulford, , tmulford@epri.com. Buried Pipe Initiative Tackles Multiple Age-Related Degradation Issues Plant License Renewal and Economic Issues are Highlighting the Need for Advanced Inspection, Repair, Replacement, and Mitigation Technologies for Buried Pipe. Concerns about the health of buried piping have spurred increased regulatory attention related to license renewal activities, and increased plant attention due to the cost and time required for repairing or replacing pipe with excessive degradation. Unlike above-ground piping systems, buried pipes can corrode and foul from the fluid side and corrode or experience mechanical damage from the soil side. Also, although the corrosion mechanisms are generally slow, they are cumulative, with leak frequency increasing as plants reach 30 years of operation. EPRI s Buried Pipe Initiative targets research spanning inspection, repair and replacement options for buried piping. Ongoing activities include: Nuclear Executive Update: 4

5 Buried Pipe Integrity Group EPRI organized this group to promote buried pipe experience sharing, provide training to plant personnel, compile information from industry experts, and sponsor related research projects. The next meeting will be July 22-23, 2008 in Jacksonville, Fla. Programmatic Recommendations EPRI has developed draft what-to-do guidance for plant personnel in controlling buried pipe degradation (Technical Report ). A multi-stage review by nuclear industry experts will facilitate final document release by late 2008 or early Risk Ranking Software Because nuclear plants contain 15 to 30 buried piping systems, each potentially encountering tens to hundreds of different conditions (e.g., burial conditions, soil properties, cathodic protection, coatings, linings, materials, joints, applied loads, fluid conditions, etc.), it is not practical or necessary to inspect each system under every condition. EPRI is developing software to apply risk-informed ranking in prioritizing inspection locations. A beta release is scheduled for late summer High-Density Polyethylene Piping High-density polyethylene (HDPE) represents an attractive option for repair and replacement of corroding metal pipe as compared to carbon steel, exhibiting no tendency to corrode, foul, or host tubercles or bi-valves. HDPE can also be installed much faster and less expensively than metal pipe. In January 2007, ASME approved Code Case N-755, which contains rules for the installation of HDPE in Class 3 systems. EPRI is supporting NRC approval of Code Case N-755 for HDPE installation in Class 3 piping systems through materials property development, fusing and repair standards, and nondestructive evaluation methods. Condition Assessment of Buried Pipe EPRI is developing an inspection vehicle to examine buried pipe in typical nuclear plant conditions. In 2007, laboratory testing confirmed the ability of sensors to detect pits down to ½ wide and 50% through-wall, as well as preferential weld attack (EPRI Technical Report No ). A field test is planned for September 2008, and technology development in 2009 and beyond will focus on application to medium-diameter pipes (12-36 inches in diameter), water-filled pipes, and small-diameter pipes. Contact: Shane Findlan, , sfindlan@epri.com. Large-Diameter Remote Field Eddy Current Inspection Vehicle EPRI Adapts Prognostics and Health Management to Nuclear Plants Although used successfully in the Defense Industries, Prognostics and Health Management Techniques must be Adapted to the Unique Challenges Faced by Nuclear Plants. As components age, advanced information processing capabilities can support detailed equipment health assessments, enabling nuclear plants to achieve equipment reliability goals. Prognostics and health management (PHM) techniques used successfully in the defense industries monitor equipment degradation over time and provide informed estimates of remaining useful life. EPRI is evaluating PHM s applicability to the nuclear industry. As a first step, EPRI is developing guidance for sensor requirements, monitoring, and prognostic algorithms that would provide health assessment data for a pump motor. Subsequent development plans include a 2009 PHM demonstration on a medium-voltage motor and horizontal pump. Nuclear Executive Update: 5

6 To apply PHM in the nuclear power industry, improvements will be needed in several areas, followed by integration with maintenance management processes. Sensors and Data Processing: As diagnostics are performed in a more automated fashion, uncertainty can be reduced with sensors that address specific failure modes. Further, since wiring costs for new sensors can be significant, wireless sensors with on-board data processing may offer a low-power, lowmaintenance, lower-cost solution. On-board processing can also reduce the amount of data transferred to the plant network, reducing the typical data flood experienced when new sensors are added to the plant. Failure Modes and Effects Analysis (FMEA): FMEA supports improved diagnostics, but advances are needed to align observable failure symptoms with early warning indications from sensors, predictive maintenance tasks, operator rounds, and component health assessments. Diagnostics: Diagnostics are typically performed once a failure mode has progressed to a level affecting equipment performance. Advanced diagnostic algorithms including statistical processing, artificial intelligence, and model-based reasoning could accelerate detection of performance degradation and increase equipment reliability. Prognostics: While diagnostics indicate when a failure either has occurred or is near, prognostics provide an estimated time to failure. Failure prediction before degradation, or without an indication, is based primarily on prior knowledge of failure modes. Failure prediction after degradation is based on useful life projections. Prognostic techniques that incorporate ongoing research and lessons learned related to the physics of degradation are essential for remaining useful life calculations. The accompanying figure depicts how a fully developed PHM program can predict remaining useful life. The vertical axis depicts theoretical degradation of a particular component, with degradation increasing over time. The dashed red line represents the level of degradation at which a failure is imminent. The future pathway (light blue line) represents a prediction (prognostic) based on the observed pathway and degradation model. This future pathway is bounded by uncertainty bands to represent the inaccuracy inherent to predictions. Contact: Aaron Hussey, , ahussey@epri.com. Technology Innovation: From Nano Particles to Wavy Welding Technology Innovation Projects for 2008 Address Advanced Fuel Cycles, High-Temperature Gas Reactors, On-Line Monitoring, and Nano-Scale Crack Characterization. Technology Innovation (TI) projects, funded with about 15% of annual membership dues, consistently result in technology breakthroughs. Recent successes include: nondestructive evaluation inspection methods for wavy welded surfaces, a vacuum device for removing debris at the base of fuel assemblies, magnetic organic molecules for radiological cleanup of fluid systems, nano-particle addition to cooling systems to enhance heat transfer properties, and improved earthquake hazard models for design of new plants and risk management of existing plants. Projects selected for 2008 include modeling of closed nuclear fuel cycle options, technical contributions to next-generation high-temperature gas reactors, and advances in online monitoring and prognostics for longterm high performance of nuclear plant equipment. Nuclear Executive Update: 6

7 Each year, 25% of TI funding is directed to a single showcase project. For 2007 and 2008, the showcase project is investigating nano-scale characterization methods to define crack initiation mechanisms in Fe-Ni-Cr alloys. Researchers are evaluating three techniques for assessing crack growth mechanisms for stress corrosion cracking in boiling water (BWRs) and pressurized water reactors (PWRs): Atom probe tomography of silicon segregation in BWRs In-situ Raman spectroscopy of surface films in PWRs Secondary ion mass spectroscopy at grain boundaries in PWRs. Experiments incorporating these analytical tools will guide development of two crack growth models, a slip dissolution model for BWR environments and an internal oxidation model for PWR environments. Contact: John Gaertner, , (jgaertner@epri.com). Electron Microscope Image of a Milled Specimen Containing a Grain Boundary ready for Atom Probe Tomography Switchyard End-of-Life Guide Will Inform Long-Term Planning The Fourth in EPRI s Series of End-Of-Life Guides, the Switchyard Report Includes Component-Level Recommendations Related to Failure Likelihood, Condition Monitoring, and Logistics. As part of its series of end-of-life (EOL) guides for key nuclear plant equipment, EPRI s Plant Support Engineering Program will issue an EOL report on switchyard equipment in fourth quarter The guide will enable plant managers and component/system engineers to identify the point in life when long-term planning or contingency planning is desirable to preclude end-of-life failures or to manage their impact. The report assumes that reasonable maintenance is being performed and that minor problems are being corrected as needed during the life of the components. The components addressed in the switchyard guide include air blast and SF6 circuit breakers, bus insulators, bus work, disconnect and ground switches, current and potential transformers, lightning arrestors, and associated structural components. The EOL report provides component-level recommendations in three areas: Failure likelihood: Identify the time period after which the likelihood of catastrophic or high-impact failure increases significantly for switchyard components. The guide will also identify major end-of-life failure mechanisms and describe factors that can accelerate their effects. Condition monitoring: Examine condition monitoring methods that can identify degradation leading to end of life. While many condition monitoring methods exist, they may not provide sufficient lead time for planning, procurement and replacement before failure occurs. Logistics: Actions must be taken in response to condition monitoring indications to validate the end-of-life recommendations. The switchyard guide will describe various logistical issues involved in effective longterm planning, including the availability of replacement components, lead time for procurement, and preparation and installation of a replacement component. Nuclear Executive Update: 7

8 The switchyard EOL report will be the fourth in the EPRI series of EOL guides. EOL guides are already available on large electric motors (EPRI Technical Report No ), power transformers (EPRI Technical Report No ), and main generators (EPRI Technical Report No ). A fifth EOL guide, on buried piping, is scheduled for completion by end of 2008, and the Plant Support Engineering Program is developing a three-year plan for additional guides. Contact: Rick Easterling, , rneaster@epri.com. Together...Shaping the Future of Electricity EPRI 3420 HILLVIEW AVENUE PALO ALTO, CA Electric Power Research Institute, Inc All rights reserved Nuclear Executive Update: 8