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 Har vesting Strategy, Coordination, and Activities
Matthew Hiser NRC Office of Nuclear Regulatory Research June 27, 2022 Har vesting Public Meeting
1 Outline
- Background
- Strategy
- Priorities
- Previously Har vested Materials
- Opportunities
- Recent and Current Activities
- Coordination
2 Materials Har vesting Background
- Historically, NRC, industry and others have performed research on materials har vested from a broad range of components
- Current har vesting 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 ser vice conditions
- Reduce uncertainty in current state of knowledge of aging and NDE effectiveness to enable informed NRC review of aging management programs
Figure: Control rod drive mechanism (CRDM) Nozzle 63 from the North Anna Unit 2 reactor (NUREG/CR-7142) 3 Current Situation
- In the past, har vesting 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 har vesting
- Currently more supply of har vesting opportunities than in the past
- Current situation calls for a more proactive strategic approach
4 A Strategic Approach to Har vesting
- In 2015, NRC began an effort to develop a materials har vesting strategy
- NRC previously was very reactive to har vesting opportunities
- PNNL developed a repo r tto help inform a har vesting strategy
- Har vesting challenges
- Expensive, complex, and time-consuming (particularly with irradiated materials)
- Documentation of component fabrication and aging conditions
- Decommissioning vs. har vesting
- Strategy: Focus on high-value har vesting opportunities
- Seek cooperation when possible to maximize limited NRC resources
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- 1. Identify and prioritize har vesting interests
- Focused on the unique value of harvesting relative to other sources of information (e. g. accelerated aging, operating experience)
Pr oactive 2. Consider use of previously har vested materials when possible Har vesting
- Greatly reduced cost, time and complexity compared to new harvesting Str ate g y
- Limited in the range of materials and aging conditions represented
- 3. Gather information on har vesting opportunities
- Requires sufficient information to meaningfully compare to priorities
- Challenging to acquire across the population of decommissioning plants
6 Har vesting Interests Prioritization
- Identify and prioritize materials degradation issues best addressed by har vesting to focus limited resources on highest priority needs
- NRC staff performed review to prioritize har vesting interests for various components (metallic, electrical, and concrete)
- Identified interest by component / material, purpose or planned testing and knowledge to be gained
- Ranked har vesting interests by technical criteria relevant to NRC mission and priorities
- Binned interests based on results from ranking criteria
7 Criticalness of Technical Issue Addressed
- Higher safety significance and less available data leads to higher ranking
Importance of Har vested Materials over Laboratory Aging Technical
- In-plant aging conditions or materials that are more difficult to replicate in the lab leads to higher ranking Prioritization Applicability to US Operating Fleet Criteria
- 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
8 High Priorities - Metals
Interest Description Purpose / Testing Planned Technical Knowledge Gained Harvesting Status 600 thermally treated (T T) Non-destructive examination NDE assessment / detection and structural steam generator (SG) tubes (NDE) and mechanical testing integrity for shallow flaws Seeking opportunities with shallow flaws Thermally aged unirradiated Fracture toughness and Fracture toughness data in real conditions Identified and pursuing cast stainless steel (CASS) microstructure to compare to accelerated aging data opportunity Bottom-mounted Residual stress measurements Confirm adequacy of current inspection instrumentation (BMI) and crack initiation/growth requirements Seeking opportunities -
nozzles with known PWSCC testing very few plants with indications Flaw characterization Confirm NDE effectiveness and flaw known BMI indications distribution Higher fluence stainless Fracture toughness, IASCC Properties to inform inspection scope and Addressed by SMILE*
steel (SS) welds (>2 dpa) CGR, and microstructure interval and flaw evaluation and other opportunities
Very high fluence SS welds Fracture toughness, IASCC, Properties to inform inspection scope and Identified and pursuing from CE plants (>10 dpa) and microstructure interval and flaw evaluation opportunity
- SMILE = Studsvik Materials Integrity for Life Extension 9 High Priorities - Concrete/Structural and Electrical
Interest Description Purpose / Testing Planned Technical Knowledge Gained Harvesting Status Real life data, model verification. Damage characterization, model Identified and Mechanical properties and Verification, reduce uncertainty, evaluate pursuing opportunity.
Irradiated concrete characterization. Potential further structural performance. Gain insight for rate irradiation. effects, scale effects compared to accelerated testing.
Reactor supports Embrittlement, fracture toughness, Structural integrity and performance. Inform Identified and microstructure inspection scope. pursuing opportunity.
Electrical Cables Comparison of service aged specimen Confirm technical basis for aging Seeking opportunities.
(low and medium with accelerated-aged samples. Assess management programs.
voltage) NDE effectiveness. Assess fire spread and thermal failure criteria.
10 Previously Har vested Materials
- NRC staff have catalogued previously har vested 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 har vested materials:
- U.S. Department of Energy (DOE) Nuclear Fuels and Materials Library (NFML)
- Studsvik - SMILE-related and other har vested materials
- Halden Reactor Project
11 Examples from PNNL
12 Har vesting Opportunities
- NRC has worked with EPRI to develop a har vesting opportunities table
- Covers domestic and international har vesting opportunities (decommissioning or announced shutdown date plants)
- Examples of column headings shown below:
13 Recently Shutdown U.S. Plants
Plant Design Size (MWt ) Ye a r s 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 Har vesting Coordination
- For har vesting cooperation and leveraging, coordination with potential partners is essential
- Past NRC cooperation on har vesting 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 Har vesting Activities
Plant Components Harvested Status Bellefonte Electrical enclosures N U REG-2180; NUREG/CR-7197 Neutron absorber materials ML19155A215 Zion Electrical cables Testing ongoing Electrical bus ducts OECD/NEA/CSNI/R(2017)7 Crystal River 3 Electrical bus ducts Testing planned Zo r i ta Reactor internals ML22132A039; ML20198M503 SONGS 2 Unirradiated concrete ML22119A092 Ringhals 2 RPV, internals, RPV penetrations, SG tubes, piping OECD/NEA SMILE ongoing through Oskarshamn RPV, internals, piping 2025
16 Path Forward
- NRC will maintain and update as appropriate its har vesting 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 har vesting opportunities from domestic and international sources in accordance with the har vesting strategy
- NRC staff are expecting to brief the Advisory Committee on Reactor Safeguards (ACRS) on har vesting activities in fall 2022
17 Acronym List
- A N L Argonne National Laboratory
- MWt Megawatt-thermal
- B&W Babcock and Wilcox
- N E A Nuclear Energy Agency
- BWR Boiling water reactor
- NWC Normal water chemistry
- CE Combustion Engineering
- OECD Organization for Economic Co-operation
- CGR Crack growth rate and Development
- DOE Department of Energy
- PNNL Pacific Northwest National Laboratory
- EPRI Electric Power Research Institute
- PWR Pressurized water reactor
- FT Fracture toughness
- PWSCC Primary water stress corrosion cracking
- HAZ Heat-affected zone
- IASCC Irradiation-assisted stress corrosion
- SEM Scanning electron microscopy cracking
- SMILE Studsvik Materials Integrity for Life
- MRP Materials Reliability Program
- SS Stainless steel
- NMCA Noble metal chemistry addition
- TEM Transmission electron microscopy
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