Case Study of Lessons Learned from the Operation of the Fast Flux Test Facility

Transcription

1 Case Study of Lessons Learned from the Operation of the Fast Flux Test Facility D. W. WOOTAN, R. P. OMBERG Pacific Northwest National Laboratory C. GRANDY Argonne National Laboratory IAEA/OECD Third International Conference on Nuclear Knowledge Management Challenges and Approaches 7-11 November, 2016, Vienna, Austria October 13,

2 Organizational Context and Objectives PNNL s fast reactor data preservation program is sponsored by U.S. Department of Energy (DOE) Office of Nuclear Energy (DOE-NE) Advanced Reactor Technology (ART) program, Pacific Northwest National Laboratory (PNNL) is operated for U.S. DOE by Battelle ART-AFR Program Objective - Develop advanced fast reactor technology solutions to allow commercial deployment by 2050 timeframe Train next generation engineers and scientists by engaging them in advanced reactor concept design and analysis and fundamental studies that support fast reactor R&D Allow transfer of knowledge from seasoned reactor professionals to younger staff Design and develop scalable advanced technologies for reducing the cost and/or increasing the performance of fast reactor technology Preserve and manage data, knowledge, and experience related to past U.S. DOE fast reactor design, operations, tests, and component technology Re-establish the U.S. infrastructure to support the testing of advanced technologies for fast reactor applications Collaborate internationally on advanced reactor R&D through bilateral or multilateral agreements and utilize international collaborations to leverage and expand R&D investments IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

3 FFTF Lessons Learned Process Primary objective of FFTF data preservation program Document the current effort to retrieve, secure, and preserve critical lessons learned that could influence advanced reactor designs Knowledge Management preserves past R&D results and counters loss of key infrastructure and expertise Usually not practical to replicate past experiments or conduct new ones US has long time horizons Expense of facilities and new integrated measurements may be prohibitive Prevents losing context of collected data Importance of minor elements may not be recognized by future users of data Results of tests may be used many years after generation Equipment may change dramatically over the years Quality assurance pedigree of data difficult to re-establish IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

4 FFTF - 10 Years of Successful Operation IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

5 FFTF Lessons Learned Approach Domain experts develop a short report (4-5 pages) on each lesson learned topic Longer reports can be developed as needed Each lessons learned summary discusses the problem and the resolution Topics selected are applicable to future design or operating problems All are supported by more detailed documents references and unpublished tribal knowledge Captures the essential tacit knowledge associated with each topic in a focused manner IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

6 Lessons Learned Approach Lessons Learned Topics Acceptance and Startup Testing Heat Exchanger Performance Startup Testing Sodium Natural Circulation and Decay Heat Removal Secondary Sodium Flow Oscillations Cesium Release from Failed Fuel and Transport within the Reactor Plant Gas Entrainment and Accumulation in Sodium and NaK Systems Sodium Spills and Fires Primary System Pressure Drop Increase Bowing in Reflector Assemblies Thermal Transient Usage Sodium and NaK System Deactivation Sodium Thermal Stratification Sodium Pump Flooding/Shaft Bowing/Seizure Sodium Vapor Trap Design and Operation Monitoring and Tracking of System and Component Performance Sodium and NaK Fill Process Deactivation of Primary Loop Isolation Valves Digital Display and Data Handling System Integrated Leak Rate Testing Control Rod Pin Design and B 4 C Performance Design for Ease of Decommissioning IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

7 FFTF Lessons Learned Process Overcomes knowledge management challenges by preserving the past, capturing current progress, and making knowledge available Preserves the past by identifying backlogs and prioritizing preservation efforts to concentrate on those areas that are of current interest Protects the information from destruction by capturing existing experiences from experts who were involved or knowledgeable about the issue Reduces backlog by focusing the efforts on manageable topics that can be summarized quickly Archives the relevant references IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

8 Challenges and Achievements: Swelling of FFTF Reflector Assemblies Problem LMRs should be designed to perform predictably Solution During design, reflector assemblies were assumed to exhibit low swelling behavior in a neutron flux based on a collection of high nickel alloy data available at the inception of FFTF Lessons Learned The degree of difficulty in withdrawing outer row driver fuel was observed to be a function of the peak fast fluence of neighboring reflector assemblies Swelling of Inconel-600 components impacted performance of reflector assemblies and the degree of restraint transmitted to neighboring fuel assemblies during refueling Highlights the peril of completing a design without sufficient material properties data since swelling data on Inconel-600 not available when reflector assemblies designed or to warn of refueling operations difficulty IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

9 Knowledge Derived FFTF acceptance and startup testing Applicable to future nuclear plant startups Demonstrated natural circulation decay heat removal Secondary sodium flow oscillations Straight forward system design configurations can result in unexpected behavior Cesium contamination Worker dose can be limited to relatively low values through system design/operation Gas entrainment Attention must be paid when designing future LMRs Liquid metal spills Probability and consequences can be limited through proper design, construction and operation of plant systems Primary pressure drop increase Design with sufficient margins so that there is little impact on plant operations. Swelling of reflector assemblies Highlights the perils of completing a design without sufficient material properties data IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

10 Knowledge Derived Thermal Transient Usage Design Duty Cycle was appropriate, although number of some events approached the design allowance on some components and was well below it on others Sodium Thermal Stratification Consider potential to cause significant thermal gradients, thermal transients and resulting stresses in the design and operation of plant systems and components Sodium Pump Flooding/Shaft Bowing/Seizure Avoid moving sodium into undesirable locations during manipulation of plant systems Some impacts of inadvertent sodium movement may remain hidden until later Confidence in the ability to replace and repair major sodium wetted plant equipment Sodium Vapor Trap Design and Operation Significant quantities of sodium aerosol (not just vapor) can be in the cover gas Alternate cover gas monitoring equipment while reactor shut down Change operating conditions to improve cesium removal efficiency or consider adding separate cesium vapor traps Deactivation of Primary Loop Isolation Valves Potential impacts of equipment failures must be fully understood and carefully evaluated during the design of the plant IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,

11 Conclusions FFTF was highly successful, demonstrated outstanding performance during the 10 years of reactor operation and nearly 20 years of plant system operation Technology employed in designing, constructing, and operating FFTF can significantly influence the development of new advanced reactor designs FFTF Lessons Learned Approach has been successful in capturing essential tacit knowledge about key events in FFTF history and providing a context for interpreting the existing data and references. IAEA Knowledge Management 7-11 November 2016 Vienna Austria October 13,