ML22074A313
| ML22074A313 | |
| Person / Time | |
|---|---|
| Issue date: | 03/03/2022 |
| From: | NRC/NRR/DNRL/NCSG |
| To: | |
| Terry L | |
| Shared Package | |
| ML22074A312 | List: |
| References | |
| 20220146, econcurrence 20220315-40007, ML22048B328, ML22059A082, ML22059A817 | |
| Download: ML22074A313 (6) | |
Text
March 17, 2022 U.S. Nuclear Regulatory Commission Public Meeting Summary
Title:
Meeting with the Industry Steam Generator Task Force Meeting Identifier: 20220146 Date of Meeting: March 3, 2022 Location: Webinar Type of Meeting: Observation 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 March 3, 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 Package Accession No. ML22074A312. This meeting was noticed as a public meeting and the agenda is available in ADAMS under Accession No. ML22048B328.
Package: ML22074A312 Meeting Summary: ML22074A313 Meeting Notice: ML22048B328 NRC Slides: ML22059A082 Industry Slides: ML22059A817 *via e-mail NRR-106 OFFICE NRR/DNRL/NCSG NRR/DNRL/NRLB/LA NRR/DNRL/NCSG/BC NAME LTerry SGreen SBloom DATE 03/15/2022 03/16/2022 3/17/2022 LISTING OF ATTENDEES U.S. NRC MEETING WITH THE INDUSTRY STEAM GENERATOR TASK FORCE March 3, 2022 Participant Affiliation Participant Affiliation Alan Brown Intertek Brian Mann Excel Services Bill Cullen EPRI Richard Coe Intertek Brent Capell EPRI Greg Energy Harbor Kammerdeiner Dan Mayes Duke Energy Sasan Bakhtiari ANL Helen Cothron EPRI Allen Hiser NRC James Benson EPRI Andrew Johnson NRC Jasmyn Bone Entergy Bernie Thomson NRC Jeff Raschiatore Westinghouse Mekonen Bayssie NRC John Arhar PG&E Greg Makar NRC Kester Thompson FPL Jason Daniel NRC Lee Friant Exelon Nuclear Tony Gardner NRC Michael Stark Dominion Energy Leslie Terry NRC Pat Wagner Wolf Creek Nuclear Operating Patrick Purtscher NRC Corp.
Rich Guill EPRI Paul Klein NRC Russell Cipolla Intertek Steven Bloom NRC Thomas Bipes Zetec Matthew Yoder NRC Scott Redner Xcel Energy, Inc. Lydiana Alvarado NRC Sean Kil EPRI Clinton Ashley NRC John Conly Certrec Michael Frotscher Entergy Enclosure
Summary of Presentations: Industry representatives made presentations on recently published Electric Power Research Institute (EPRI) reports, the status of revisions to industry guidelines, recent domestic and international operating experience, and potential new methods of foreign object wear sizing. Industry also provided feedback on proposed changes to Aging Management Program (AMP) XI.M19, Steam Generators, in Volume 2 of NUREG-2191, Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report (ADAMS Accession No. ML17187A204), that the NRC staff shared only for discussion purposes during the October 7, 2021, meeting between the NRC and industry SGTF (ADAMS Package Accession No. ML21293A117).
The NRC staff presented a draft response to the industry request for clarification on the inspection requirements in Technical Specifications Task Force (TSTF), TSTF-577, Revision 1, Revised Frequencies for Steam Generator Tube Inspections (ADAMS Accession No. ML21060B434), and standardizing titles of SG tube inspection reports submitted to the NRC.
Additional details of the information exchanged during the meeting is provided below.
- Recently published EPRI reports were discussed related to divider plate cracking, primary water chemistry guidelines, a qualification program protocol for the Automated Analysis Performance Demonstration Database, a +Point' Probe to X-Probe amplitude transfer function, operating experience on tube denting at the top-of-tubesheet, justification requirements for extending eddy current examination techniques, a leak rate estimation methodology for partial through-wall circumferential cracking, secondary side dispersant effects on flow accelerated corrosion, impacts of film-forming products on chemistry instrumentation, primary water reactor secondary side hydrazine alternatives, and an eddy current simulation model. In addition, Revision 5 of the Steam Generator Integrity Assessment Guidelines and an update to the Technical Basis for the Integrity Assessment Guidelines were published in December 2021.
- Industry representatives noted that recent in situ pressure testing data is being gathered to determine whether revisions to the Steam Generator In Situ Pressure Test Guidelines are needed and that a revision to the Steam Generator Examination Guidelines is in progress.
- An overview of industry activities in response to recent international operating experience related to dense scale spalling and wearing SG tubes was presented. This first-of-a-kind international experience was initially discussed during the October 7, 2021, meeting between the NRC and industry SGTF. Industry activities include characterizing tube scale removed from domestic SGs, determining the extent of tube scale that could result in tube wear, assessing the capabilities of eddy current techniques with tube scale, and identifying actions that may reduce tube scale leading to tube wear.
- Domestic operating experience discussed by industry representatives included thermally treated Alloy 600 (Alloy 600TT) U-bend stress corrosion cracking of Model D5 and Model 44F SGs. The indication in the Model D5 SG was initially reported as axial primary water stress corrosion cracking by the licensee. After review of the 2021 and historical eddy current data, the Steam Generator Management Program members determined that the indication was axial outside diameter stress corrosion cracking (ODSCC) at a ding.
Determination of the degradation mechanism was complicated by the axial ODSCC originating within the ding. The Steam Generator Management Program members also 2
reviewed the eddy current data from a recent indication in a Model 44F SG and agreed that the degradation was axial ODSCC at a ding.
- Industry representatives provided a project update on foreign object wear sizing. The objective of the project is to develop a method to accurately measure, from the secondary side of the SG, the depth size of tube wear due to foreign objects. The goal for the secondary sizing method is to alleviate the need to enter the primary side if new foreign object wear is detected during refueling outages where primary side eddy current inspections are not performed. It was noted that utilities may request relief from the foreign object wear technical specification repair limit when the foreign object has been removed.
- After approval of TSTF-577, the industry identified a potential conflict between TSTF-577 and AMP XI.M19 in Volume 2 of NUREG-2191 related to the requirement to inspect the SG divider plate assemblies, tube-to-tubesheet welds, heads, and tubesheets at least every 72 effective full power months or every third refueling outage, whichever results in more frequent inspections. During the March 3, 2022, meeting between the NRC and industry SGTF, industry representatives provided comments on the proposed changes to AMP XI.M19 that the NRC staff shared only for discussion purposes during the October 7, 2021, meeting between the NRC and industry SGTF. Specifically, the industry stated that the phrase or every third refueling outage, whichever results in more frequent inspections should be removed to be consistent with TSTF-577. Industry also noted that not all plants include divider plate assembly inspection in the degradation assessment and recommended deleting the phrase so long as the degradation assessments for these latter components also support such inspection intervals. The NRC staff noted that the NRC now plans on issuing a new revision to NUREG-2191 instead of issuing interim staff guidance.
- In a letter from C. Lee Friant, SGTF Chairman, to Steve Bloom, Branch Chief of the Corrosion and Steam Generator Branch, dated December 9, 2021 (ADAMS Accession No. ML22006A030), the industry requested clarification on the inspection requirements in TSTF-577. Specifically, the industry requested clarification on the scope of the next inspection after crack indications are found and whether inspections for Alloy 600TT units on a 72 effective full power month (EFPM) inspection interval can be staggered once the initial 100 percent enhanced probe inspection is performed.
With regards to the scope of the inspection after crack indications are found, the NRC staff noted that the standard technical specifications1 require that the inspection at the next refueling outage after crack indications are found is for the degradation mechanism that caused the crack indication in the affected and potentially affected SGs. The staff noted that the plant-specific degradation assessment would determine if inspection for the degradation mechanism is needed at multiple tube elevations/locations and the expectation is that a licensees determination of the next refueling outage inspection scope will have a strong technical basis that considers fleet operating experience.
1 NUREG-1430, Revision 5, Standard Technical Specifications -Babcock and Wilcox Plants, dated September 2021 (ML21272A363 (Volume 1) and ML21272A370 (Volume 2)); NUREG-1431, Revision 5, Standard Technical Specifications -
Westinghouse Plants, dated September 2021 (ML21259A155 (Volume 1) and ML21259A159 (Volume 2)); and NUREG-1432, Revision 5, Standard Technical Specifications -Combustion Engineering Plants, dated September 2021 (ML21258A421 (Volume
- 1) and ML21258A424 (Volume 2)).
3
With regards to staggered inspections after the initial 100 percent enhanced probe inspection is performed, the NRC staff noted that the standard technical specifications do not prohibit switching SG tube inspections to a staggered approach after the initial 100 percent enhanced probe inspection is completed. The staff discussed several example scenarios of how Alloy 600TT units on a 72 EFPM inspection interval would be affected by the detection of cracking for the first time during a staggered inspection. Once cracking is found in any SG in a unit, the maximum inspection interval for all SGs is limited to 54 EFPM, and inspections would move to earlier refueling outages to meet the maximum inspection interval. The NRC plans to respond to the SGTF letter in writing.
- To standardize the titles of the SG tube inspection reports that are required by the licensees technical specifications to be submitted to the NRC, the NRC staff requested that the title include Steam Generator Tube Inspection Report, which is the same title used in the standard technical specifications. The staff noted that standardizing the titles would improve distribution to appropriate NRC staff and improve ADAMS searches related to SG tube inspections.
If you have any questions regarding this meeting summary, please feel free to contact Leslie Terry by phone at 301415-1167, or by e-mail at Leslie.Terry@nrc.gov.
Attachments:
- 1. Meeting Notice: ML22048B328
- 2. NRC Slides: ML22059A082
- 3. Industry Slides: ML22059A817
- 4. Package: ML22074A312 4