ML23152A180

13 - NRC - Materials Harvesting Activities

ML23152A180
Person / Time
Issue date:	06/14/2023
From:	Jeffrey Poehler, Robert Tregoning NRC/RES/DE
To:
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Download: ML23152A180 (1)

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Update on NRC Materials Harvesting Activities Jeffrey Poehler and Robert Tregoning NRC Office of Nuclear Regulatory Research Industry/NRC Materials Technical Information Exchange Meeting June 14 - 15, 2023 NRC Headquarters, Rockville, MD

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 Control rod drive mechanism (CRDM) aging by testing materials aged in operating plants Nozzle 63 from the North Anna Unit 2 reactor (NUREG/CR-7142)

- Reduce uncertainty in current state of knowledge of aging and NDE effectiveness to enable informed NRC review of aging management programs 2

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 3

Proactive Harvesting Strategy

1. Identify and prioritize harvesting Focused on the unique value of harvesting relative to other sources of interests information (e.g. accelerated aging, operating experience)

2. Consider use of previously Greatly reduced cost, time and complexity compared to new harvesting harvested materials when possible Limited in the range of materials and aging conditions represented

3. Gather information on harvesting Requires sufficient information to meaningfully compare to priorities Challenging to acquire across the population of decommissioning plants opportunities 4

Technical Prioritization Criteria Criticalness of Technical Issue Importance of Harvested Applicability to US Operating Regulatory Considerations Addressed Materials over Laboratory Aging Fleet Related to Inspections and AMPs Higher safety significance and less available In-plant aging conditions or materials that Applicability to a greater number of plants Greater availability and confidence in data leads to higher ranking are more difficult to replicate in the lab leads to higher ranking inspection methods or aging management leads to higher ranking approaches leads to lower ranking 5

High Priorities - Metals Interest Description Purpose / Testing Planned Technical Knowledge Gained Harvesting Status 600 thermally treated (TT)

Non-destructive examination NDE assessment / detection and structural steam generator (SG) tubes Seeking opportunities (NDE) and mechanical testing integrity for shallow flaws 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 Residual stress measurements Bottom-mounted Confirm adequacy of current inspection and crack initiation/growth Seeking opportunities -

instrumentation (BMI) requirements testing very few plants with nozzles with known PWSCC known BMI indications Confirm NDE effectiveness and flaw indications Flaw characterization 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

• SMILE = Studsvik Materials Integrity for Life Extension 6

Previously Harvested Materials

• NRC staff have catalogued previously harvested materials from prior NRC-sponsored research, including:

- PNNL - large array of components from 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 7

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:

8

NRC Recent and Current Metals Harvesting

• Neutron absorber materials from Zion (ML19155A215)

• Reactor internals base and weld materials from Zorita (ML22132A039; ML20198M503)

• Various metallic components through OECD/NEA Studsvik Materials Integrity for Life Extension (SMILE) Project

- Harvesting from Ringhals 2, 3 and Oskarshamn 2 reactors in Sweden

- Highly leveraged program with 7 other countries participating along with EPRI from U.S.

• Pursuing additional opportunities for more targeted harvesting from domestic and international plants

- Focused on high-value components in alignment with NRC priorities

- Working in cooperation with DOE and EPRI 9

Harvesting Coordination and Outreach

• Partnering and information sharing is essential to manage the costs and complexity associated with harvesting activities

• With respect to harvesting, NRC cooperates with:

- U.S. Department of Energy (DOE)

- Electric Power Research Institute (EPRI)

- International organizations

• NRC periodically holds public meetings on harvesting to solicit feedback from stakeholders: 6/27/2022 (public meeting) and 10/6/2022 (presentation to ACRS)

• NEA/NRC held international workshops on metals harvesting in 2020 and 2022

- Understand common harvesting priorities among participants

- Discuss planned and ongoing activities with each participating country

- Identify opportunities to collaborate or share information among organizations 10

Conclusions and Key Messages

• Harvesting is an important tool for enhancing our understanding of materials and component aging

• NRC is pursuing a proactive harvesting strategy that includes:

- Maintaining and updating harvesting priorities

- Seeking harvesting opportunities from domestic and international sources that align with priorities

• NRC maximizes collaboration with other organizations such as EPRI and DOE to gain the maximum benefit for the lowest possible cost 11

Acronym List

• ACRS Advisory Committee on Reactor Safeguards

• NEA Nuclear Energy Agency

• ANL Argonne National Laboratory

• OECD Organization for Economic Co-operation and

• B&W Babcock and Wilcox Development

• BWR Boiling water reactor

• PNNL Pacific Northwest National Laboratory

• CE Combustion Engineering

• PWR Pressurized water reactor

• CGR Crack growth rate

• PWSCC Primary water stress corrosion cracking

• DOE Department of Energy

• RPV Reactor Pressure Vessel

• EPRI Electric Power Research Institute

• SCC Stress corrosion cracking

• FT Fracture toughness

• SEM Scanning electron microscopy

• IASCC Irradiation-assisted stress corrosion cracking

• SMILE Studsvik Materials Integrity for Life Extension

• INL Idaho National Laboratory

• SONGS San Onofre Nuclear Generating Station

• XRF Micro X-ray fluorescence

• SS Stainless steel

• MWt Megawatt-thermal

• TEM Transmission electron microscopy

• NDE Nondestructive examination

• UPV Ultrasonic pulse velocity

• XRD X-ray diffraction 12