ML21217A260

11 - NRC - Ni-Alloy Crack Growth

ML21217A260
Person / Time
Issue date:	08/10/2021
From:	Jay Collins, Eric Focht NRC/NRR/DNRL, NRC/RES/DE
To:
Hiser A
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Download: ML21217A260 (13)

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Industry / NRC Materials Programs Technical Information Exchange Nickel-Based Alloy Crack Growth Rates Jay Collins Eric Focht Senior Materials Engineer Senior Materials Engineer Piping and Head Penetration Branch Materials Engineering Branch Division of New and Renewed Plant Licensing Division of Engineering Office of Nuclear Reactor Regulation Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission

Discussion Points

• History of the development of Alloy 690 crack growth rates (CGR)

• Update Office on Nuclear Regulatory Research (RES) User Need Request

• Moving Forward 08/11/2021 Industry / NRC Annual Technical Exchange 2

History

• EPRI Crack Growth Expert Panel

-Data analysis

-Application group

• EPRI Report, MRP-386

-Recommended Factors of Improvement for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) Growth Rates of Thick-Wall Alloy 690 Materials and Alloy 52, 152, and Variants Welds

• ASME Code Case N-909-x

• EPRI crack growth database collection 08/11/2021 Industry / NRC Annual Technical Exchange 3

Impacted Areas

• New reactors

• Replaced components

• ASME Code Case N-770-x, Weld Inspections

-Weld overlays

-Inlays/Onlays

-Excavate and Weld Repair

• ASME Code Case N-729-x, Reactor Pressure Vessel Upper Head Nozzles and Welds

-Replaced heads

-Repaired nozzle penetrations and welds 08/11/2021 Industry / NRC Annual Technical Exchange 4

NRC Contractor Final CGR Testing

• Weld overlay testing

-Crack growth into overlay

-Crack turning at interface along boundary

• Alloy 690 CRDM mockup testing

-Dilution zone (152/SS, 152/LAS)

-Alloy 690 heat affected zone

• Multiple repairs in weld testing

-Testing in 40% & 20% repaired Alloy 52 weld

-Dilution zone (52/LAS) 08/11/2021 Industry / NRC Annual Technical Exchange 5

RES User Need Topics

• Crack Growth Rate

-Alloy 690/52/152 CGR testing and analysis

-MRP-386 Open Items

-Alloy 690 Aging

• PWSCC Initiation 08/11/2021 Industry / NRC Annual Technical Exchange 6

Crack Growth Rate Testing & Analysis

• Alloy 690/52/152 CGR testing:

-Closeout generic validation crack growth rate testing for Alloy 690 materials (Complete).

-Final NUREG/CRs being prepared for publication.

-Develop a current basis of knowledge recommendation for factors of improvement.

08/11/2021 Industry / NRC Annual Technical Exchange 7

Crack Growth Rate Testing & Analysis

• CGR NUREG/CRs

- ANL Final NUREG/CR: Primary Water Stress Corrosion Cracking of High-Chromium Nickel-Base Welds At or Near Interfaces - 2020 [NUREG/CR #

pending]

- PNNL Final NUREG/CR: Pacific Northwest National Laboratory Investigation of Stress Corrosion Cracking in Nickel-Base Alloys: Dissimilar Metal Interface Regions and Assessment of Program Results, NUREG/CR-7103, Volume 5.

- ANL 2018 NUREG/CR: Primary Water Stress Corrosion Cracking of High-Chromium Nickel-Base Welds - 2018, NUREG/CR-7276.

08/11/2021 Industry / NRC Annual Technical Exchange 8

Crack Growth Rate MRP-386 Open Items Review

• Alloy 690/52/152

-Model parameter dependencies

• Examples: heat-to-heat variability, deformation, orientation, weld metal variants, dilution effects, etc.

-Reviewing available data

• More data anticipated following the up-coming Expert Panel review/scoring of new data

-Make recommendations

• Action plans for base and weld metals (2022) 08/11/2021 Industry / NRC Annual Technical Exchange 9

Crack Growth Rate Alloy 690 Aging

• Aged Material Effects

-Literature review

-Evaluate recent work on Alloy 690 and 52/152 through extended plant lifetime potentials.

-Develop action plan (2021).

08/11/2021 Industry / NRC Annual Technical Exchange 10

PWSCC Initiation

• Crack Initiation Testing

-Support xLPR and other probabilistic tools by validating initiation model, parameters and dependencies (stress, temp, hydrogen)

-Validate yield strength initiation threshold

-Alloy 690/52/152 crack initiation FOI 08/11/2021 Industry / NRC Annual Technical Exchange 11

Moving Forward

• Continued updates as work progresses

-ASME Code

-EPRI Alloy 690 Meetings

• Regulatory changes considered

-Ongoing activities (i.e., relief requests)

• Determine adequate technical basis

• Utilize risk informed/insight processes

-Probabilistic approaches anticipated

-Future rulemakings 08/11/2021 Industry / NRC Annual Technical Exchange 12

Questions 08/11/2021 Industry / NRC Annual Technical Exchange 13