ML22174A324
| ML22174A324 | |
| Person / Time | |
|---|---|
| Issue date: | 06/27/2022 |
| From: | Matthew Hiser Office of Nuclear Regulatory Research |
| To: | |
| J. Poehler | |
| Shared Package | |
| ML22174A322 | List: |
| References | |
| Download: ML22174A324 (18) | |
Text
NRC Harvesting Strategy, Coordination, and Activities Matthew Hiser NRC Office of Nuclear Regulatory Research June 27, 2022 Harvesting Public Meeting 1
Outline
- Background
- Strategy
- Priorities
- Previously Harvested Materials
- Opportunities
- Recent and Current Activities
- Coordination 2
Materials Harvesting Background
- Historically, NRC, industry and others have performed research on materials harvested from a broad range of components
- Current harvesting objectives focus on materials aging during long-term operation:
- Confirm results from laboratory experiments and analytical simulations to improve understanding of aging during highly representative service conditions
- Reduce uncertainty in current state of knowledge of aging and NDE effectiveness to enable informed NRC review of aging management programs 3
Figure: Control rod drive mechanism (CRDM) Nozzle 63 from the North Anna Unit 2 reactor (NUREG/CR-7142)
Current Situation
- In the past, harvesting efforts have generally been reactive as limited new opportunities arose
- Few plants shutting down led to more demand than supply
- In recent years, a significant number of plants have shut down and entered the decommissioning process
- Generally operated for a long period, which provides more highly aged components for harvesting
- Currently more supply of harvesting opportunities than in the past
- Current situation calls for a more proactive strategic approach 4
A Strategic Approach to Harvesting
- In 2015, NRC began an effort to develop a materials harvesting strategy
- NRC previously was very reactive to harvesting opportunities
- PNNL developed a report to help inform a harvesting strategy
- Harvesting challenges
- Expensive, complex, and time-consuming (particularly with irradiated materials)
- Documentation of component fabrication and aging conditions
- Decommissioning vs. harvesting 5
- Strategy: Focus on high-value harvesting opportunities
- Seek cooperation when possible to maximize limited NRC resources
Proactive Harvesting Strategy 6
- 1. Identify and prioritize harvesting interests
- Focused on the unique value of harvesting relative to other sources of information (e.g. accelerated aging, operating experience)
- 2. Consider use of previously harvested materials when possible
- Greatly reduced cost, time and complexity compared to new harvesting
- Limited in the range of materials and aging conditions represented
- 3. Gather information on harvesting opportunities
- Requires sufficient information to meaningfully compare to priorities
- Challenging to acquire across the population of decommissioning plants
Harvesting Interests Prioritization
- Identify and prioritize materials degradation issues best addressed by harvesting to focus limited resources on highest priority needs
- NRC staff performed review to prioritize harvesting interests for various components (metallic, electrical, and concrete)
- Identified interest by component / material, purpose or planned testing and knowledge to be gained
- Ranked harvesting interests by technical criteria relevant to NRC mission and priorities
- Binned interests based on results from ranking criteria 7
Technical Prioritization Criteria 8
Criticalness of Technical Issue Addressed
- Higher safety significance and less available data leads to higher ranking Importance of Harvested Materials over Laboratory Aging
- In-plant aging conditions or materials that are more difficult to replicate in the lab leads to higher ranking Applicability to US Operating Fleet
- Applicability to a greater number of plants leads to higher ranking Regulatory Considerations Related to Inspections and AMPs
- Greater availability and confidence in inspection methods or aging management approaches leads to lower ranking
High Priorities - Metals Interest Description Purpose / Testing Planned Technical Knowledge Gained Harvesting Status 600 thermally treated (TT) steam generator (SG) tubes with shallow flaws Non-destructive examination (NDE) and mechanical testing NDE assessment / detection and structural integrity for shallow flaws Seeking opportunities Thermally aged unirradiated cast stainless steel (CASS)
Fracture toughness and microstructure Fracture toughness data in real conditions to compare to accelerated aging data Identified and pursuing opportunity Bottom-mounted instrumentation (BMI) nozzles with known PWSCC indications Residual stress measurements and crack initiation/growth testing Confirm adequacy of current inspection requirements Seeking opportunities -
very few plants with known BMI indications Flaw characterization Confirm NDE effectiveness and flaw distribution Higher fluence stainless steel (SS) welds (>2 dpa)
Fracture toughness, IASCC CGR, and microstructure Properties to inform inspection scope and interval and flaw evaluation Addressed by SMILE*
and other opportunities Very high fluence SS welds from CE plants (>10 dpa)
Fracture toughness, IASCC, and microstructure Properties to inform inspection scope and interval and flaw evaluation Identified and pursuing opportunity 9
- SMILE = Studsvik Materials Integrity for Life Extension
High Priorities - Concrete/Structural and Electrical 10 Interest Description Purpose / Testing Planned Technical Knowledge Gained Harvesting Status Irradiated concrete Real life data, model verification.
Mechanical properties and characterization. Potential further irradiation.
Damage characterization, model Verification, reduce uncertainty, evaluate structural performance. Gain insight for rate effects, scale effects compared to accelerated testing.
Identified and pursuing opportunity.
Reactor supports Embrittlement, fracture toughness, microstructure Structural integrity and performance. Inform inspection scope.
Identified and pursuing opportunity.
Electrical Cables (low and medium voltage)
Comparison of service aged specimen with accelerated-aged samples. Assess NDE effectiveness. Assess fire spread and thermal failure criteria.
Confirm technical basis for aging management programs.
Seeking opportunities.
Previously Harvested Materials
- NRC staff have catalogued previously harvested materials from prior NRC-sponsored research, including:
- PNNL - large array of components from smaller penetrations up to large piping sections used for NDE research
- Battelle - large primary system piping and elbows
- ANL - smaller irradiated reactor internals materials
- Other sources of previously harvested materials:
- U.S. Department of Energy (DOE) Nuclear Fuels and Materials Library (NFML)
- Studsvik - SMILE-related and other harvested materials
- Halden Reactor Project 11
Examples from PNNL 12
Harvesting Opportunities
- NRC has worked with EPRI to develop a harvesting opportunities table
- Covers domestic and international harvesting opportunities (decommissioning or announced shutdown date plants)
- Examples of column headings shown below:
13
Recently Shutdown U.S. Plants Plant Design Size (MWt)
Years in Operation Shutdown Date SONGS 2/3 PWR (CE) 3,438 31/30 2012 Kewaunee PWR (W 2-loop) 1,772 39 2013 Crystal River 3 PWR (B&W) 2,609 36 2013 Vermont Yankee BWR-4/Mark-1 1,912 42 2015 Fort Calhoun PWR (CE) 1,500 43 2016 Oyster Creek BWR-2/Mark-1 1,930 49 2018 Pilgrim BWR-3/Mark-1 2,028 47 2019 Three Mile Island 1 PWR (B&W) 2,568 45 2019 Indian Point 2/3 PWR (W 4-loop) 3,216 48/46 2020/2021 Palisades PWR (CE) 2,565 51 2022 Diablo Canyon 1/2 PWR (W 4-loop) 3,411 40 2024-5*
- planned shutdown date 14
Harvesting Coordination
- For harvesting cooperation and leveraging, coordination with potential partners is essential
- Past NRC cooperation on harvesting has involved:
- U.S. Department of Energy (DOE)
- Electric Power Research Institute (EPRI)
- International partners
- Coordination has occurred via recurring calls and meetings with domestic and international researchers 15
Recent and Current Harvesting Activities Plant Components Harvested Status Bellefonte Electrical enclosures NUREG-2180; NUREG/CR-7197 Zion Neutron absorber materials ML19155A215 Electrical cables Testing ongoing Electrical bus ducts OECD/NEA/CSNI/R(2017)7 Crystal River 3 Electrical bus ducts Testing planned Zorita Reactor internals ML22132A039; ML20198M503 SONGS 2 Unirradiated concrete ML22119A092 Ringhals 2 RPV, internals, RPV penetrations, SG tubes, piping OECD/NEA SMILE ongoing through 2025 Oskarshamn RPV, internals, piping 16
Path Forward
- NRC will maintain and update as appropriate its harvesting priorities and seek opportunities that align with priorities
- Studsvik Materials Integrity for Life Extension (SMILE) project continues through 2025
- Covers a wide variety of metallic components
- Pursuing harvesting opportunities from domestic and international sources in accordance with the harvesting strategy
- NRC staff are expecting to brief the Advisory Committee on Reactor Safeguards (ACRS) on harvesting activities in fall 2022 17
Acronym List ANL Argonne National Laboratory B&W Babcock and Wilcox BWR Boiling water reactor CE Combustion Engineering CGR Crack growth rate DOE Department of Energy EPRI Electric Power Research Institute FT Fracture toughness HAZ Heat-affected zone HWC Hydrogen water chemistry IASCC Irradiation-assisted stress corrosion cracking INL Idaho National Laboratory MRP Materials Reliability Program NMCA Noble metal chemistry addition MWt Megawatt-thermal NEA Nuclear Energy Agency NWC Normal water chemistry OECD Organization for Economic Co-operation and Development PNNL Pacific Northwest National Laboratory PWR Pressurized water reactor PWSCC Primary water stress corrosion cracking RPV Reactor Pressure Vessel SCC Stress corrosion cracking SEM Scanning electron microscopy SMILE Studsvik Materials Integrity for Life Extension SS Stainless steel TEM Transmission electron microscopy 18