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Meeting Summary for September 8 2022 NRC Meeting with Steam Generator Task Force
	ML22277A799
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Issue date:	10/06/2022
From:	Leslie Terry; NRC/NRR/DNRL/NCSG
To:	;
	Terry L
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ML22277A798	List: ML22277A799;
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	Download: ML22277A799 (5)
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October 6, 2022 U.S. Nuclear Regulatory Commission Public Meeting Summary

Title:

Meeting with the Industry Steam Generator Task Force Meeting Identifier: 20220866 Date of Meeting: September 8, 2022 Location: Webinar Type of Meeting: Partially Closed Meeting Purpose of the Meeting: The purpose of this meeting was for the U.S. Nuclear Regulatory Commission (NRC) staff to discuss steam generator (SG) issues with the industry Steam Generator Task Force (SGTF).

General Details: The industry SGTF met with NRC staff on September 8, 2022, by webinar.

The purpose of the meeting was to discuss a variety of SG issues. The NRC and industry slides are available in the Agencywide Documents Access and Management System (ADAMS) under Accession Nos. ML22245A082 and ML22244A049, respectively. This meeting was noticed as a public meeting and the agenda is available in ADAMS under Accession No. ML22245A006.

LISTING OF ATTENDEES U.S. NRC MEETING WITH THE INDUSTRY STEAM GENERATOR TASK FORCE September 8, 2022 Participant Affiliation Participant Affiliation Bill Cullen EPRI Russell Wells TVA Dan Mayes Duke Energy Tom Peacock Rolls-Royce Helen Cothron EPRI Tim Thulien Duke Energy James Benson EPRI Veena Gubbi Jasmyn Bone Entergy Jerry Humphrey Jeff Raschiatore Westinghouse Sasan Bakhtiari ANL John Arhar PG&E Andrew Johnson NRC Kester Thompson FPL Mekonen Bayssie NRC Lee Friant Constellation Nuclear Greg Makar NRC Michael Stark Dominion Energy Jason Daniel NRC Rich Guill EPRI Leslie Terry NRC Russell Cipolla Intertek Patrick Purtscher NRC Thomas Bipes Zetec Paul Klein NRC Sean Kil EPRI Steven Bloom NRC Michael Frotscher Entergy Joel Jenkins NRC Jay Smith Westinghouse Reena Boruk NRC Brad Carpenter Westinghouse Allen Hiser NRC Phil Rush MPR Isaac Anchondo-Lopez NRC Kalynn Rios Entergy Craig Kelley Framatome Cotasha Blackburn Southern Company Daniel Folsom TVA Jeremy Mayo TVA Steve Brown Entergy Rick Williams EPRI Summary of Presentations: Industry representatives made presentations on recently published Electric Power Research Institute (EPRI) reports, the status of revisions to industry guidelines, axial outside diameter stress corrosion cracking (ODSCC) at dents and dings, U-bend stress corrosion cracking (SCC), a status update on the laboratory-cracked SCC tube samples supplied by Equipos Nucleares, S.A. (ENSA), and development of a transfer function relating +Point' probe voltage to array probe voltage.

The NRC staff presented feedback on industry implementation of Appendix G, Template for TSTF-577 180-Day Steam Generator Inspection Report, in EPRI Steam Generator Management Program: Steam Generator Integrity Assessment GuidelineRevision 5 (IAGL).

Additional details of the information exchanged during the open portion of the meeting is provided below.

Recently published EPRI reports were discussed including the Steam Generator Performance and Reliability Database, the effect of amines (pH control) on steam turbine materials, and the use of Diethylhydroxylamine as a secondary side hydrazine alternative.

Additional prescriptive guidance is also being considered for the EPRI Steam Generator Management Program: Pressurized Water Reactor Steam Generator Examination Guidelines, Appendix N, Noise Measurement and Monitoring, including spike and median filters, average versus maximum noise measurements, and the need for Alloy 690 tube noise monitoring, etc.

An industry representative described how freespan dents and dings could be formed by the stainless steel quatrefoil tube support plates during the tube insertion process. These geometric discontinuities result in large, localized noise components. Dent or ding cracking results in a complex eddy current signal formed from the combined crack and noise signals.

An industry representative continued discussion of recent domestic operating experience related to thermally treated Alloy 600 (Alloy 600TT) U-bend SCC of Model D5 and Model 44F SGs that was discussed at the March 3, 2022, meeting between the NRC and the industry SGTF (ML22074A312). The Steam Generator Management Program members believe these indications are axial outside diameter stress corrosion cracking (ODSCC).

Axial primary water stress corrosion cracking (PWSCC) was reported in a Row 1 Alloy 600TT tube in 2009. Industry believes this may have been axial ODSCC at a ding based on the recent U-bend experience; therefore, the industry plans to perform additional investigation in 2023.

An industry representative provided a status update on the ENSA tube samples with laboratory-produced SCC. Fabricating and destructively analyzing flaw samples assists with nondestructive examination technique development. In 2019, the industry started developing axial ODSCC lab-induced crack samples at a U.S. vendor facility. Currently, efforts are being made to produce circumferential ODSCC lab-induced cracks. The information from the destructive analyses will be used to support Model Assisted Probability of Detection (MAPOD) calculations. Several axial PWSCC samples will be added to existing EPRI Examination Technique Specification Sheet (ETSS) to support MAPOD calculations.

Qualification of array probes is based on lab-generated flaws and +Point' probe ETSSs are based mostly on pulled tube specimens. An industry representative stated that the amplitude versus depth response for lab-generated flaws may not be as consistent as for pulled tube flaws, and this inconsistency can affect the A-hat function and probability of detection simulations for the array probe. In 2017, using flaws in array probe and +Point probe ETSSs, a transfer function concept was developed. The transfer function was described as a linear regression of array signal amplitude on +Point' signal amplitude. The industry completed work on a transfer function for ODSCC in 2020 and will investigate a transfer function for PWSCC in 2023. The NRC staff stated that the transfer function needs additional validation.

Technical specifications require a SG tube inspection report (SGTIR) be submitted to the NRC. Appendix G of the EPRI IAGL provides a SGTIR template that is required for plants adopting Technical Specifications Task Force (TSTF) Traveler TSTF-577 or converting to Revision 5 of the Standard Technical Specifications. The EPRI IAGL recommends that plants not adopting TSTF-577 consider using the template. The NRC staff highlighted some good examples of information provided in recent SGTIR reports and some areas where additional information may be needed based on the industry template. The NRC staff provided an ADAMS accession number for a well written example, ML22108A224. This example included a detailed explanation of dents and dings and provided photographs to help communicate information in the SGTIR.

The final portion of the meeting was closed due to the proprietary information related to the transfer function from +Point probe voltage to array probe voltage, EPRI SG guidelines, and EPRI ETSS program.

If you have any questions regarding this meeting summary, please feel free to contact Leslie Terry by phone at 301-415-1167, or by email at Leslie.Terry@nrc.gov.

Attachments:

1. Meeting Notice:

2. NRC Slides:

3. Industry Slides:

4. Package:

Package: ML22277A798 Meeting Summary: ML22277A799 Meeting Notice: ML22245A006 NRC Slides: ML22245A082 Industry Slides: ML22244A049