Nuclear Executive Update

Transcription

1 Nuclear Executive Update An EPRI Progress Report November 2009 The Nuclear Executive Update is published bi-monthly. If you have comments about the newsletter, please contact Brian Schimmoller, The EPRI Nuclear Sector is a global collaboration. About one-third of our funding derives from international members, representing 20 countries and more than 80% of the world s nuclear units. With the addition of Korea Hydro & Nuclear Power as a full member in 2009, full membership now includes participants from Canada, France, Spain, Mexico, South Africa, Japan, Korea, Brazil, and the United Kingdom. Nuclear plants in many other countries participate through supplemental research programs. Global participation in the EPRI collaborative provides a two-way flow of information. Members gain access to EPRI s collaborative research results. Of equal value, EPRI gains access to the complementary research, global operating experience and industry expertise resident at these companies. For example, at the Materials Aging Institute, which EPRI launched with EDF and Tokyo Electric Power Co. in January 2008, research is underway to explain and anticipate the aging of materials in existing power production facilities. This information will help all nuclear plant operators in assessing the viability of long-term plant operations. The nuclear industry will also significantly benefit from the construction experience accumulated at EPRI member companies such as Korea Hydro & Nuclear Power Co., where the continued, repetitive deployment of new nuclear plants over the past two decades has led to substantial reductions in cost and schedule. To more effectively respond to the needs posed by our growing international membership, we have also increased our overseas technical interactions. Regional technical meetings and workshops have been organized for programs of interest to all international members, totaling more than 50 events in For example, in February, EPRI and UNESA jointly hosted a European technical workshop in Madrid to discuss materials and NDE needs for nuclear reactors. Attendees at this meeting represented nuclear utilities, engineering companies, and research agencies from Spain, Switzerland, Sweden, the Czech Republic, and the United Kingdom. A June workshop in Korea addressed multiple topics related to plant technology and equipment reliability. An October workshop in Tokyo addressed on-line maintenance for several Japanese nuclear utilities. To showcase the value of the EPRI global collaborative, this issue of Nuclear Executive Update contains several stories reflecting the value and extent of the nuclear sector s international engagement, from the transfer of U.S. experience with on-line maintenance to the global nuclear community to the capture of lessons learned in the United Kingdom on instrument calibration. For more information on EPRI s international outreach activities, please give me a call at Thank you for your continued support of EPRI. Sincerely, Tuan Nguyen Acting Vice President, Nuclear Sector Nuclear Executive Update: 1

2 European Utilities Tap EPRI to Support Qualification of Weld Inspection Procedures Spanish and Swiss nuclear utilities use nondestructive evaluation procedures developed through EPRI s Performance Demonstration program to qualify procedures for application in their countries. U.S. utilities established the Performance Demonstration Initiative (PDI) to qualify people, procedures and equipment for performing ultrasonic nondestructive evaluations (NDE) for major reactor cooling system components. While PDI was initially developed in response to U.S. needs, it is increasingly being adopted in countries in Europe and Asia to fully or partially satisfy their own performance demonstration requirements. PDI can assist international utilities and regulators in two key areas: (1) Helping other countries set up their own domestic qualification program, such as EPRI is doing in Korea; (2) Helping utilities use the PDI program to address local requirements, and to develop the technical justifications and procedures necessary to complete their compliance. Both types of assistance can save money and speed the process of developing qualified inspection procedures that ensure nuclear safety. The Spanish NDE Qualification, for example, UNESA CEX-120, is based on the European (ENIQ) qualification methodology, which is somewhat different than the American PDI methodology. We don t want to reinvent the wheel, so we take advantage of specific PDI capabilities and qualifications, said Lorenzo Francia, technology engineering manager for the Spanish utility consortium UNESA (Asociacion Española de la Industria Electrica) in Madrid. For example, we used a number of EPRI PDI procedures, including UT-1, UT-2, UT-3, to qualify our piping inspection procedures. We also used PDI UT-10 to qualify our procedures with respect to dissimilar metal welds. The PDI program is managed and operated by EPRI at its Charlotte, North Carolina facility. The lab has accumulated an inventory of more than 400 test samples, consisting of an assortment of piping (from 2 inches to 50 inches in diameter), nozzles, reactor vessel sections, reactor head bolts, dissimilar metal welds, and weld overlay repairs. These components contain a variety of weld types and some contain flaws such as thermal fatigue cracking, mechanical fatigue cracking and stress corrosion cracking. For UNESA, EPRI has assisted with two types of technical justifications. The first one is to check that the Spanish inspection area configurations are covered by the mockups that PDI used when it developed a procedure, said Francia. The second type ensures that the procedure itself PDI UT-1, UT-2, UT-10 or now the UT-8 meets the CEX-120 requirements. The information is then provided to the Spanish regulator as supporting evidence for qualifying the inspection procedures. Switzerland s four nuclear utilities and its regulatory agency are also working with EPRI on performance demonstration activities. Kernkraftwerk Leibstadt (KKL), which operates the country s largest reactor, a 3,600 MW BWR, often makes use of existing PDI qualifications and justifies their use with the help of technical support material provided by EPRI. In addition, KKL taps EPRI personnel during outages to review test results before they present them to the regulator. It helps to have EPRI s technical expertise in assessing the NDE results, which are open to interpretation, said Rudi Schwammberger, KKL s in-service inspection section head. It also strengthens our position in front of the regulator, if we have an independent expert to present our results. For more information, contact Greg Selby, or gselby@epri.com. Nuclear Executive Update: 2

3 A SMARTer Approach to Plant Chemistry Through its SMART ChemWorks software application, user group meetings, and on-site assessments, EPRI helps nuclear power plants optimize chemistry conditions, protecting plant equipment and increasing personnel productivity. EPRI s SMART ChemWorks software application provides nuclear power plants with the ability to rapidly evaluate and model chemistry programs using a simple consistent desktop application. A five-year project to significantly upgrade the software will increase functionality and enable international implementation. Complementary site visits help program participants derive maximum value from the software applications, as well as evaluate other chemistry improvement opportunities such as zinc injection and shutdown chemistry evaluations. SMART ChemWorks offers real-time plant water chemistry monitoring and alerts. The online system continuously monitors plant and chemistry parameters with data provided from plants via a simple data transfer tool installed locally. The real-time intelligence engine performs virtual sensing, identifies normal and off-normal conditions, and compares in-line instrument output to grab sample analyses. By automating routine but necessary functions, plant staff can concentrate on more important tasks. If an anomaly is detected while the chemist is engaged in another activity, SMART ChemWorks issues an alert to call attention to the problem. Further, the software trends current data to capture small changes, giving plants time to plan and implement a solution. SMART ChemWorks is in use at 22 plants in the United States. Entergy uses it to optimize instrument calibrations, providing valuable insights not available through its Chemistry Data Management System. The automatic alerting and diagnosis capabilities calls the chemist s attention to secondary events while he is performing other tasks, and the plant summary information automatically tracks which in-line instruments are in service. The SMART ChemWorks upgrade project features several important revisions: (i) improved data transfer tool to reduce time spent monitoring and maintaining data transfer at the plant site; (ii) upgraded data engine to rapidly enable application of EPRI technology and accommodate changes to technology, guidelines, and calculations; (iii) ability to accept non-chemistry data from other systems while applying the same alerting and calculation tools; and (iv) redesign of the SMART ChemWORKS website to provide a better user interface. In addition to developing software enhancements, EPRI has significantly increased chemistry engagements with international utilities. Such interactions help utilities optimize their chemistry programs, but also provide valuable data and operating experience that EPRI can integrate into future software upgrades and other chemistry-related research. In the past four years, EPRI chemistry staff has visited plants in 12 countries on four continents. Highlights include: Annual visits to Eletronuclear (Brazil) for ongoing operational and shutdown chemistry technical exchanges and ChemWorks training. The 2007 visit included a Primary-to-Secondary Leak Rate Program Assist Visit. Four trips to Eskom s Koeberg nuclear plant in South Africa since 2005 to assess long-term steam generator health, evaluate shutdown chemistry, perform benchmarking analyses, and conduct a hideout return evaluation. Several trips to Japan, culminating in Japan Atomic Power Company signing a three-year agreement in June 2009 to join the EPRI Zinc Users Group and access expert EPRI assistance related to zinc injection. Nuclear Executive Update: 3

4 EPRI has also begun conducting international ChemWorks meetings. In 2007, EPRI and UNESA hosted the first International ChemWorks /SMART ChemWorks meeting in Vandellos, Spain. The meeting, attended by representatives from Brazil, Spain, and France, focused on application of the ChemWorks codes. Several action items from this meeting laid the groundwork for the improvements that are part of the ChemWorks five-year upgrade plan. For more information, contact David Perkins at or Application of On-Line Maintenance Spreads Overseas EPRI is supporting the implementation of on-line maintenance in Japan and other countries to encourage regulatory and operational changes that can provide safety, economic and performance benefits to nuclear power plants. U.S. experience has shown that on-line maintenance programs if properly designed, implemented, and supported by an appropriate regulatory framework can enable nuclear plants to improve equipment reliability, reduce risks of component failures, extend fuel cycles, shorten refueling outages, and optimize work planning. Moreover, this can be accomplished without compromising plant and personnel safety. In the United States, more than 70% of the total maintenance conducted at nuclear plants is performed on-line, according to a 2008 EPRI electronic survey. Several other countries are now applying on-line maintenance practices, and as more countries consider implementation, the potential for further collaboration grows. During the last year, EPRI has supported several nuclear companies in Asia in their consideration of on-line maintenance. Historically, as international organizations incorporated on-line maintenance into their plant practices, they adapted it to meet country-specific regulatory and operational preferences. Surveys and discussions with some of these organizations indicate that this has resulted in a more diverse set of implementation approaches than used in the United States. For example, U.S. plants use common elements such as a rolling 12- or 13-week work management process and PRA-based (probabilistic risk assessment) configuration risk management tools. While such elements are effective in the United States, their full implementation is not necessarily essential in achieving success with on-line maintenance. EPRI will be conducting benchmarking studies later this year and next year to better understand how the processes developed internationally differ from those in the United States and how they have been adapted from U.S. processes. Such information could lead to additional guidance regarding different but effective levels of on-line maintenance work scope. An article in early 2010 will address these benchmarking surveys in greater detail. For more information, contact Ken Huffman at or khuffman@epri.com. Nuclear Executive Update: 4

5 On-Line Monitoring at Sizewell Saves Millions by Extending Instrument Calibration Intervals An on-line monitoring program for certain safety-related and non-safety-related instruments enabled the Sizewell B nuclear plant in the United Kingdom to reduce its critical path outage schedule by about five days. The implementation of on-line monitoring for calibration interval extension of safety-related transmitters at Sizewell B is the first commercial application of this technology, and is expected to serve as a guide for other utilities pursuing similar extensions. To drive greater application of on-line monitoring, EPRI is currently working with several utilities and the Westinghouse Owner s Group to engage the Nuclear Regulatory Commission in finalizing a standardized licensing submittal for upcoming applications. Through on-line monitoring, British Energy s Sizewell B plant extended the calibration intervals of all pressure and differential pressure transmitters in the primary system and some in the secondary system, and also automated cross-calibration of resistance temperature detectors during cool-down and/or heat-up. Outage savings from these actions are estimated at $5 million per operating cycle, through a direct reduction in the critical path outage schedule of about five days. Additional savings are achieved from reducing other direct and indirect costs such as manpower, radiation exposure, and the risk of calibration errors. Sizewell B s long-term goal is to expand on-line calibration monitoring from the initial set of about 200 transmitters to nearly 2500 transmitters, including many in the secondary side of the plant. On-line monitoring uses non-intrusive techniques to evaluate instrument channel performance and equipment health by assessing its consistency with other plant indications. This provides a more accurate assessment of instrument calibration and component health for a given operating point, which enables calibration or maintenance to be performed less often, based on the instrument s or plant equipment s actual condition rather than a purely time-based schedule. At Sizewell B, EPRI assisted plant staff in developing a plan for the staged implementation of on-line monitoring and in-situ testing techniques. After gaining approval from the British Nuclear Installation Inspectorate to extend calibration intervals, British Energy implemented on-line monitoring at Sizewell B over three fuel cycles. EPRI has actively supported the development and use of on-line monitoring in nuclear power plants for instrument calibration reduction and equipment condition monitoring since the early 1980s. For example, EPRI helped obtain U.S. Nuclear Regulatory Commission (NRC) approval to use on-line monitoring to optimize the frequency of calibration of pressure, level, and flow transmitters in nuclear power plants. The NRC granted official approval in a July 2000 Safety Evaluation Report, which provides generic approval, but requires a site-specific license amendment for each plant to switch from the traditional calibration approach to the on-line approach. EPRI s monitoring technology activities have advanced to the application of large-scale centralized monitoring of plant assets. Current developments include automated diagnostic capabilities and a new Monitoring Interest Group to support nuclear plant monitoring programs and technology development. A final report on the Sizewell B application will be available in late December (report number ). For more information, contact Rick Rusaw at or rrusaw@epri.com. Nuclear Executive Update: 5

6 Global Benchmarking Effort Captures Modular Construction Best Practices Incorporating lessons learned from visits to Electric Boat, Hitachi, and Mitsubishi Heavy Industries, the report focuses on methods for qualifying and testing modules for use in new nuclear plant construction. Modular design and construction will play a large role in the development and deployment of new nuclear plants. Recognizing that many companies have already incorporated modular techniques into nuclear-related design and construction, EPRI s Advanced Nuclear Technology Program conducted a benchmarking project to capture best practices. The project focused on methods for qualifying and testing modules in the factory: how modules can be qualified and tested and how qualification and test results can be preserved as the modules are shipped to the plant site and installed. The benchmarking project team visited three companies on the cutting edge of modular construction: Electric Boat, which builds nuclear submarines; and Hitachi and Mitsubishi Heavy Industries, which have been using modularization techniques for nuclear plant construction since the 1990s. The site visits collected information on a number of critical modularization elements, including: Extent of final qualification being conducted at the module manufacturing facility (where qualification refers to items such as weld inspection, stress analysis, stress reports based on as-built condition, and continuity checks for electrical equipment). Extent of testing conducted at the module manufacturing facility (where testing refers to items such as as-built validation, integrity tests, and performance tests). Methods used to document the results of qualification and testing. Methods for maintaining control of shipping and storage. Several similarities emerged from observing the three organizations that should be considered when evaluating the use of modules for new nuclear plant construction: All had metrics to define the cost savings when a task was moved from the site to the fabrication facility and again when a task was moved to the shop. All had experience showing that lower costs and better quality were achieved the earlier the task was performed. All had cultural philosophies involving cleanliness in construction. Components were built clean, and that cleanliness was maintained throughout construction. All treated off-site facilities as extensions of the construction site. This included sharing workers among the different locations. All tried to perform any single task or test only once. For instance, after receiving a valve from a vendor, it would take an off-normal situation to prompt anyone to reopen that valve to work on the internals. Findings from the benchmarking trips are compiled in EPRI report number EPRI will use the results of the benchmarking project in developing recommendations for the testing and qualification of modules for nuclear plant application. These recommendations will be compiled in a report, Testing, Shipping, and Storage of Modular Equipment, to be completed in early For more information, contact Ken Barry at or kbarry@epri.com. Nuclear Executive Update: 6

7 EPRI Report Examines Health Effects of Low-Dose Radiation Multi-year review of more than 200 publications indicates that the risks associated with low-dose exposure may be over-estimated, although further research is needed to quantify the health response at low doses. An extensive multi-year review of published literature related to the health effects of low-dose radiation indicates that the risks associated with low-dose exposure may be over-estimated. Further research is needed, however, to quantify the health response at low doses and to fully account for the complexity of biological mechanisms. The analysis of the health effects of radiation at low dose is included in a new report titled, Evaluation of Updated Research on the Health Effects and Risks Associated with Low-Dose Ionizing Radiation. EPRI examined more than 200 peer-reviewed publications in developing the report, with special emphasis on new information not included in previous analyses. The report is intended to inform the regulatory community and other stakeholders in evaluating the basis for personnel dose limits and in assessing risk-based criteria for decommissioning and low-level waste disposal. The analysis yielded a number of key conclusions: Recent radiobiological studies in the low-dose region demonstrate that the mechanisms of action for many biological impacts are different than those seen in the high-dose region. When radiation is delivered at a low dose-rate (i.e., over a longer time period), it is much less effective in producing biological changes than when the same dose is delivered in a short time period. Therefore, the risks due to low dose-rate effects may be over-estimated. From an epidemiological perspective, individual radiation doses of less than 10 rem in a single exposure are too small to allow detection of any statistically significant excess cancers in the presence of naturally occurring cancers. The doses received by nuclear power plant workers fall into this category because exposure is accumulated over many years, with an average annual dose about 100 times less than 10 rem. Research into the health effects of low-dose radiation should continue and should use holistic, systemsbased approaches to develop models that define the shape of the dose-response relationships in the low-dose regions. Risk models should fuse the latest radiobiology and epidemiology results to produce a comprehensive understanding of radiation risk that addresses both damage (likely with a linear effect) and response (possibly with non-linear consequences). While recent scientific advances have provided much new information in the low-dose region, they have also raised additional research questions. New research in areas such as systems biology can provide mechanistic understandings of low-dose and low dose-rate effects needed to estimate human cancer risks. Therefore, it is essential that research into low-dose radiation biology, dose reconstruction, and epidemiology continue in order to provide opportunities for continuous improvement in the scientific support of future regulatory and policy actions. For more information, contact Phung Tran at or ptran@epri.com. Nuclear Executive Update: 7

8 EPRI to Establish Technical Bases for Very Long-Term Storage of Used Fuel Recognizing the likelihood that used nuclear fuel will have to be stored on-site for many decades, EPRI is gathering stakeholder input to define the research and analysis pathways necessary to ensure very long-term safe storage, transportation, and monitoring. In most countries with a commercial nuclear power industry, nuclear plants will have to manage used fuel for decades prior to final disposition. To ensure this can be done safely, the technical bases for very longterm (at least 60 years) storage must be established. The 2010 research portfolio for EPRI s Used Fuel and High-Level Waste Program includes projects that will begin addressing this issue. A November workshop with representatives from EPRI, nuclear utilities, the regulatory community, government agencies, used fuel storage vendors, and other stakeholders began defining critical gaps and research needs. Very long-term management of used fuel must address multiple components in developing a defensible technical basis: wet and dry storage, as well as both storage and transportation. In the United States, for example, most used fuel is stored on-site in a combination of pools (wet storage) and dry storage casks (dry storage). While the pools are licensed for at least the life of the reactor (typically 40 to 60 years), used fuel in dry storage is stored under separate certificates for an initial 20-year period. These license and certificate time periods will likely have to be extended. Further, at some point in time, the used fuel will need to be transported somewhere away from the reactor sites. When this occurs, it will be necessary to demonstrate that the used fuel can be safely transported (e.g., remain intact during storage such that the fuel is retrievable and will not become critical after a transportation accident). Because of the long-term nature of waste storage, detailed investigation may be required into a host of potential issues: Condition of the fuel in dry casks and of the fuel baskets in sealed canisters Condition of the fuel and pools in wet storage Environmental and handling conditions that could compel repackaging Repackaging at sites where reactor decommissioning has taken place (loss of wet pool storage, requirements for dry transfer) Long-term lead cask testing of high burnup fuel Long-term monitoring requirements Effect of long-term storage on transportability As a first step in scoping these issues, the November workshop focused on identifying the long-term aging issues for maintaining safe wet/dry storage and transportation that may require attention. Attendees identified options for addressing these aging issues, such as analysis and data collection, and began to identify additional data requirements or aging management activities that may be required. Input from the workshop will be used to develop a plan for addressing these aging issues, with the eventual goal of establishing the technical bases for very long-term storage followed by transportation. EPRI will pursue collaboration and potential co-funding with the Department of Energy, the Nuclear Regulatory Commission, its global membership, the vendor community, and others to enhance data collection efforts and to build on complementary activities related to long-term storage. For more information, contact John Kessler at or jkessler@epri.com. Nuclear Executive Update: 8

9 Redesign of EPRI fuel performance software code, FALCON, on schedule for 2010 release The upgraded software features a more intuitive user interface, enables quicker setup of typical fuel performance evaluations, and utilizes modern software architecture for agile development and maintenance. Increasing emphasis on complex fuel issues such as pellet cladding interaction, missing pellet surface, and other fuel defects has elevated interest in the application of EPRI s fuel performance software code. Originally programmed in Fortran 77, FALCON was not user-friendly or easily modified with new features for complex analysis applications. An upgrade of FALCON to modern software architecture standards is nearing completion, with FalconRD Beta release scheduled for late 2009 and full product delivery set for 2010 as FALCON Version 1. Despite its legacy software structure, FALCON has been frequently used to analyze fuel performance in steady-state and transient cases, assess reload design alternatives, verify fuel supplier calculations and recommendations, and analyze fuel margins based on post-irradiation fuel examinations. In addition, FALCON analyses have been used in responding to several regulatory issues: (i) rod pressure and cladding creep in long-term spent fuel storage and transportation, (ii) conditions related to reactivity initiated accidents, and (iii) loss of coolant accidents in nuclear reactors. Beginning in late 2006, FALCON was also instrumental in analyzing operating experience that contributed to the recommendations in EPRI s Pellet Cladding Interaction Guideline (Product No , Dec 2008). The modernized FALCON code will benefit all stakeholders: For users, the code will be more intuitive, featuring a graphical user interface for post-processing and a convenient method of creating input cases. For software licensees, the code will be able to address unique applications such as integrating fuel performance, neutronic, and thermal-hydraulics into a more comprehensive software system. Command line and linked input file support will facilitate the construction of automated tools where output from other software can be used as inputs for FALCON. For EPRI, the upgrade safeguards a significant multi-year intellectual property investment to increase research capability and efficiency; potentially expands the user base by tailoring the code to the expectations of the next generation of users; and affords customized licensing solutions for universities, fuel suppliers, contractors, and national labs. For the developer, the software code is easier to maintain, troubleshoot, and add new capabilities, and it enables the efficient release of product modifications and documentation; importantly, it also reflects the latest advances and experiences with nuclear fuel design and operation. A critical requirement for the software code redesign was that the core finite-element solver calculations in FALCON remain fixed. Within acceptable error limits, calculated verification solutions from the initial version will remain identical to the solutions calculated with the redesigned version. For more information, contact Suresh Yagnik at or syagnik@epri.com. Nuclear Executive Update: 9