ML23033A666

Summary of Public Meeting with Constellation Energy Generation, LLC (Constellation) to Discuss Its Request for Alternatives for Certain Steam Generator Weld Inspections for Calvert Cliffs 1 & 2, Byron 1 & 2, Braidwood 1 & 2, and Ginna

ML23033A666
Person / Time
Site:	Calvert Cliffs, Byron, Braidwood, Ginna
Issue date:	02/09/2023
From:	Sujata Goetz Plant Licensing Branch 1
To:	Constellation Energy Generation
Goetz, S
References
Download: ML23033A666 (1)

Text

February 9, 2023 LICENSEE: Constellation Energy Generation, LLC FACILITY: Braidwood Station, Units 1 and 2; Byron Station, Units 1 and 2; Calvert Cliffs Nuclear Power Plant, Units 1 and 2; and R. E. Ginna Nuclear Power Plant

SUMMARY

OF JANUARY 30, 2023, PUBLIC MEETING WITH CONSTELLATION ENERGY GENERATION, LLC (CONSTELLATION)

TO DISCUSS ITS REQUEST FOR ALTERNATIVES FOR CERTAIN STEAM GENERATOR WELD INSPECTIONS On January 30, 2023, the U.S. Nuclear Regulatory Commission (NRC) staff held a public teleconference with representatives from Constellation Energy Generation (Constellation or the licensee) via the Microsoft TEAMS meeting application. The purpose of the meeting was to discuss NRCs review of the licensees submittal of alternative requests for Braidwood Station, Units 1 and 2 (Braidwood), Byron Station, Units 1 and 2 (Byron), Calvert Cliffs Nuclear Power Plant, Units 1 and 2 (Calvert Cliffs), and R. E. Ginna Nuclear Power Plant (Ginna). The meeting notice and agenda, dated January 30, 2023, are available in the Agencywide Documents Access and Management System at Accession (ADAMS) No. ML23019A021. A list of attendees is enclosed.

The NRC staff reinforced that the meeting was an information gathering dialogue only, no regulatory decisions would be made. Additionally, the staff stated that none of the information provided in the meeting was to be taken as a request by the licensee or a decision by the NRC staff.

The purpose of the meeting was to discuss the inspection sample size for the alternative requests for Braidwood, Byron, and Calvert Cliffs, and why Constellations proposed alternative did not meet the level of quality and safety required for an alternative approval. The licensee asked how the NRC staff made that determination and if it is considered a forward fit. The staff provided slides (attached) on how it made its determination including an example calculation supporting a performance monitoring program resulting in a 25 percent sampling size as an example of a potential path forward. The staff also stated that presentations from previous public meetings held on March 4, 2022 (ML22053A171); May 25-26, 2022 (ML22144A345); and August 22, 2022 (ML22234A046), also discussed the same topic.

Regarding the forward fit, the NRC staff stated that a response will be issued in the next couple of weeks.

The licensee stated that it will let the NRC staff know by Friday, February 3, 2023, on how it plans to proceed on the alternative requests that NRC has not issued.

Members of the public were not in attendance; no public meeting feedback forms were received.

Please direct any inquiries to me at 301-415-8004 or Sujata.Goetz@nrc.gov.

/RA/

Sujata Goetz, Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317, 50-318 and 50-224

Enclosures:

1. List of Attendees

2. Presentation Slides cc: Listserv

LIST OF ATTENDEES JANUARY 30, 2023, PUBLIC MEETING WITH CONSTELLATION REGARDING SUBMITTED ALTERNATIVE REQUESTS FOR BRAIDWOOD STATION, UNITS 1 AND 2; BRYON STATION, UNITS 1 AND 2; CALVERT CLIFFS NUCLEAR POWER PLANT, UNITS 1 AND 2; AND R. E. GINNA NUCLEAR POWER PLANT Name Organization Sujata Goetz U.S. Nuclear Regulatory Commission (NRC)

Hipo Gonzalez NRC Joel Wiebe NRC Dan Widrevitz NRC David Dijamco NRC John Tsao NRC Daniel Lamond NRC David Rudland NRC Gregory Suber NRC Bernie Thomson NRC Isaac Anchonodo Lopez NRC Jay Collins NRC Joel Wiebe NRC John Wise NRC Matthew Mitchel NRC Michael Benson NRC Sunil Weekakkody NRC Ching Ng NRC Cory Parker NRC Thomas Loomis Constellation Nuclear Joseph Buchanan Constellation Nuclear Kevin Lueshen Constellation Nuclear David Gullott Constellation Nuclear Richard Schliessmann Constellation Nuclear Art Simpson Constellation Nuclear Christopher Azmeh Constellation Nuclear Antoinette Walter Constellation Nuclear Adriene Smith Constellation Nuclear Mark Weis, Constellation Nuclear Rebecca Rice, Constellation Nuclear Darani Reddick Constellation Nuclear Sheldon Waiters Constellation Nuclear Jacky Shoulders Constellation Nuclear Thomas Basso Constellation Nuclear, NEI Loanee Enclosure 1

- Presentation Slides ML23033A667 Enclosure 2

Performance Monitoring Performance monitoring is a necessary component of Risk-Informed Approach (otherwise it is likely risk-based).

When used for justification for inspection relief, performance monitoring relies heavily on volumetric inspection but also includes information from other monitoring techniques, operational experience, research, etc.

Acceptable performance monitoring approach must provide:

• Direct evidence of presence and/or extent of degradation

• Validation/confirmation of continued adequacy of analyses

• Timely method to detect novel/unexpected degradation 1/30/2023 1

Performance Monitoring Optimization ASME Code required ISI is a form of performance monitoring providing assurance of component integrity.

-Manages known and unknown (novel) degradation Risk insights were provided in the application regarding known degradation and ISI inspection scenarios using PFM.

- Leaves the appropriate vigilance regarding potential future novel degradation as the primary question regarding proposed future inspections.

2

Performance Monitoring - Managing Unknowns 1 In assessing the potential of proposed inspections to identify novel degradation, assurance stems from answering, Can the proposed performance monitoring program detect novel degradation in a timely manner?

This question can be addressed statistically.

The staff considered a number of scenarios to evaluate the applicants proposal.

3

Performance Monitoring - Managing Unknowns 2 The staff performed statistical analysis to identify an appropriate level of performance monitoring for the subject steam generators.

The staff believe that an acceptable statistical scenario would:

At a 5% population incidence of novel degradation, have a 90%

probability of detecting at least one occurrence in a steam generator sampled For the subject applications this suggests a reduction in the total number of inspections of SGs (not individual welds) can be reduced by 75% (e.g. 1/4 of the total inspections required by ASME)*

• - Previously the NRC has approved 50% reductions for a more significant component, RPVs 4

Performance Monitoring - Managing Unknowns 3 The applicants proposed number of inspections in the September, 2022, RAI supplement would result in nearly no chance of detecting novel degradation in a timely manner.

The proposal consisted of substantially less than a single SG.

1/25/2023 5

Performance Monitoring - Considerations 1 Qualitative considerations:

• Our statistical analysis was conducted on a per-SG basis, e.g. not counting individual welds

• This side-steps complex considerations of weld comparability and focused on the key interest: integrity of SG

• Later inspections are more likely to detect novel degradation (if it is growing), and consequently are more impactful

• Additional time likely to correlate to increased population incidence and detectability

• Early inspections may be more timely, but also less likely to detect rare novel degradation 6

Performance Monitoring - Considerations 2 Qualitative considerations:

• Staff credits multiple full ASME Code interval inspections on subject components

• Other consideration not addressed in this presentation, e.g., OE, other monitoring, are also important in the development of a PM plan

• This presentation presumes credit given for OE, other monitoring (e.g. leak detection), research, etc.

• This presentation presumes that if novel degradation is found, substantial inspection scope expansion would occur 7

Summary Based on the information presented here by the staff, one acceptable proposal could be:

• To perform 1/4 of the ASME Code-required inspections of a component type (SG, PZR) for all of the units covered under the proposed alternative (rounded up to one more component inspection, if necessary)

• To perform each of the remaining inspections on different components (i.e., to not inspect the same SG or PZR more than once), and

• To perform each of the remaining inspections in the 1st Period of the last ASME Code Interval for the unit at which the inspection is to be performed (based on current 10-year intervals).

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Package: ML23037A890 Meeting Summary: ML23033A666 Slides: ML23033A667 OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DORL/LPL1/BC NRR/DORL/LPL1/PM NAME SGoetz KEntz HGonzalez SGoetz DATE 02/02/2023 2/8/2023 2/9/2023 2/9/2023