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Final Slides for Open Portion October 7 2021 NRC Meeting with SGTF
	ML21277A031
Person / Time
Issue date:	10/07/2021
From:	Leslie Terry; NRC/NRR/DNRL/NCSG
To:	;
	Terry L, 301-415-1167
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	Download: ML21277A031 (34)
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Agenda for Open Meeting 1:00 Introductions All Participants 1:10 Opening Remarks NRC and Industry 1:15 Standard Agenda Items Summary of Recently Published EPRI Reports Status of Industry Guidelines Interim Guidance NEI 03-08 Deviations Recent Operating Experience 2 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Agenda for Open Meeting (cont) 2:15 Industry Adoption of TSTF-577 Industry Enhanced Probe Inspections 2:25 Dents/Dings Definitions NRC / Industry 2:35 NUREG 2191 NRC / Industry 2:45 Address Public Questions/Comments NRC 3 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

EPRI Developed Process for Sharing Information with the NRC EPRI Staff should follow (in order) the methods when asked to share EPRI published products with the NRC.

1. Reading Room - Share the product with the NRC as Read Only (Preferred option)

2. Order Center Distribution - Share public material

3. Order Center Distribution - Share the proprietary product only, affidavit is required

4. Order Center Distribution - Share the Proprietary product and a Non-proprietary version, affidavit is required When this method is used, the proprietary version goes to the NRC Project Manager and EPRI provides a redacted non-proprietary version (containing only the product cover page and abstract) to be placed in ADAMS for public viewing.

Hydrazine Alternatives for the PWR Secondary Side System: Carbohydrazide for Operational Use and SG Layup with No Oxygen Scavenger (3002020980), July 2021 Hydrazine is a known carcinogen and EPRI is investigating alternatives This report discusses the following two different alternatives to the use of hydrazine:

Carbohydrazide use in the secondary system during power operations

Elevated pH with no oxygen scavenger during wet layup of steam generators Use considerations discussed in report include: procurement and handling issues, modeling and control issues, system compatibility, decomposition, corrosion, and interaction with other treatment chemicals.

The results will be incorporated in the next revision of EPRI Secondary Water Chemistry Guidelines

Several Documents Published Regarding Primary to Secondary Leak SGMP Primary-to-Secondary Leak Guidelines, Rev 5 (3002018267), December 2020

- This was provided to the NRC staff Estimating Probability of Burst at In Situ Pressure Test Conditions as a Function of Measured Primary-to-Secondary Leakage (3002018269) December 2020

- Not for integrity assessments, only provides relative risk discussion Primary-to-Secondary Leak Playbook (3002018271) December 2020

- Address topics outside Primary to Secondary Leak Guidelines such as very low leakage (<5 gpd) or outage planning Use of Fluorine-18 for Primary-to-Secondary Leak Rate Measurement (3002018662) November 2020

- Use is not required, only an alternative Primary-to-Secondary Leak Detection Limits for a Condenser Off Gas Rad Monitor System (3002019973) November 2020

Simulation Model for Eddy Current SG Inspection - Model Validation (3002013010) December 2020 The objective of this project is to develop a software tool that is capable of accurately simulating signals representing SG eddy current inspection data from various SG tube geometries, eddy current coil configurations, and tube degradation mechanisms.

This report presents the formulation of the computational model and the results of a simulation software tool, including a comparison of simulated eddy current data with acquired data.

- Describes features of the user interface The model was shown to be capable of predicting the signals generated by commercial SG eddy current probes for various tube flaws.

Two Reports Were Published to Provide Technical Bases for Longer Inspection Intervals for Alloy 600TT Tubing Both reports were subject of 2020 NRC audit

- NRCs comments were incorporated Extended Inspection Interval Analyses for Axial ODSCC at TSP Intersections on High Residual Stress Tubes for SGs with Alloy 600TT Tubing (3002019984) November 2020 Feasibility Study for Multi-cycle 600TT Operational Assessments (3002018258) November 2020 9 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

SGMP Guidelines Guideline Title Current Report # Last Pub Implementation Interim Review Comment Rev # Date Date(s) Guidance Date SG Integrity 4 3002007571 June 2016 8/31/17 None Rev 5 in Assessment Endorsement Guidelines Process EPRI SG In Situ 5 3002007856 Nov 2016 8/31/17 None This review will 2021 Pressure Test consider tests Guidelines completed since the last revision PWR SG 8 3002007572 June 2016 8/31/17 Published Revision in Examination 2019 and progress Guidelines 2021 PWR SG Primary- 5 3002018267 Dec 2020 12/22/2021 None 2024 to-Secondary Leakage Guidelines 11 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

SGMP Guidelines Guideline Title Current Report # Last Pub Implementation Interim Review Comments Rev # Date Date(s) Guidance Date Primary Water 7 3002000505 April 1/28/2015 2023 Reviewed in Chemistry 2014 2021, decided Guidelines not to start a revision Secondary Water 8 3002010645 Sept 6/27/2018 Published 2023 Reviewed in Chemistry 2017 in 2019 and 2021, decided Guidelines 2020 not to start a revision No active deviations 12 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Interim Guidance Secondary Water Chemistry Guidelines IG issued in February 2020 in letter SGMP-20-03 IG allows use of alternate measurement method for dispersant concentration to verify concentration does not exceed allowed value Instead of direct dispersant measurement, plants can develop correlation between steam generator blowdown cation conductivity and dispersant concentration Allowed method simplifies plant operation Conductivity provides adequate understanding of dispersant concentration 13 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Interim Guidance Examination Guidelines In support of TSTF 577, Interim Guidance SGMP-21-02 was published in September 2021 to address two issues:

- The expectation to analyze 100% of all acquired data

- Provide guidance for using single-pass automated data analysis for the Alloy 600TT fleet when employing enhanced probes (e.g., array or MRPC)

Interim Guidance Discussion:

Section 6.3.3 (Data Analysis Process) lacked clear guidance pertaining to the industry and regulatory expectation that 100% of all acquired eddy current data be analyzed in accordance with the Examination Guidelines

- This was revised to a shall requirement, and that all acquired data required by Technical Specifications and the Degradation Assessment is analyzed Discussion:

Section 6.3.3.2 excluded the ability of tubing alloys that had experienced service-induced cracking from employing a multiple algorithm single integrated automated analysis process, it became necessary to allow the application of the process for those plant(s) electing to utilize enhanced probes allowed by TSTF-577

- Provides a defense in depth using multiple techniques (array/bobbin or MRPC/bobbin) employing multiple algorithms for each technique 15 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

International SG Operating Experience Plant Details

- Commercial operation began in mid-1980s

- 600 TT SG tubes

- No chemical cleaning performed to date Eddy current testing identified indications on 4 tubes

- One tube in SG-A and three tubes in SG-C, suspected to be wear initiating on the tube OD All 4 indications were adjacent to 3rd TSP SG-A tube flaw depth by ECT: 33%TW SG-C tube flaw depth by ECT: 25%TW, 32%TW, 36%TW 17 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Event Description The affected SG tubes were visually inspected using a compact camera applied from the secondary side

- Wear on the tube OD was observed.

- Wear scar lengths ranged from 2 to 7 mm (0.08 to 0.28)

Analytical Results of the Retrieved Object An object was identified near the location of the eddy current indications on the affected tube in SG-A

- The object was retrieved

- A shiny area of the object was evidence of the object-to-tube contact location

- Radius measurement of the object revealed that the object had a curved shape closely matching the curvature of the tube OD The contact was shiny.

Analytical Results of the Retrieved Object Chemical composition analysis was performed on the object from SG-A

- The main constituent was ferric oxide (i.e., magnetite), the object was suspected to be tube scale

- Chemical composition analysis of the contact surface (corner) detected nickel and chromium components, which constitute the base metals of the tube.

Investigation of Scale Properties Tube deposit scales were retrieved from above the 1st and 2nd TSP inside SG-C for analysis.

- Similar to SG-A, the SG-C scales had traces of contact and detected nickel and chromium.

Summary One international PWR identified hard, dense scale that had spalled off the SG tubes and apparently resulted in tube wear The SGMP has been communicating with the utility and has informed SGMP member utilities of the operating experience Through continued discussions with the utility, EPRI hopes to learn additional details of the mechanism leading to dense scale formation and tube wear so that other utilities can consider if it could be a potential mechanism at their plants The SGMP is also considering performing research to improve our knowledge of the wear mechanism and its relevance to the industry 22 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

International Operating Experience One international PHWR identified significant flow accelerated corrosion of the primary moisture separators 10 pieces of material from the separators were identified on the top of the tubesheet in one steam generator The Cr content of one of the pieces retrieved was measured at 0.035% wt%

- In spec for A569 carbon steel but not resistant to flow accelerated corrosion This operating experience has been reviewed by the SGMP 23 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Industry Adoption of TSTF-577 Status of TSTF-577 LARs based on recent informal survey

- 29 units/17 plants/10 utilities have already submitted

- 4 units/3 plants/3 utilities have plans to submit this year

- 18 units/11 plants/7 utilities have plans to submit in 2022

- The remainder will be later than 2022 or will not submit Some of the 600TT fleet are planning or considering inspecting full length with advanced probes 25 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Definition of Dents and Dings Definition from the Examination Guidelines and the Integrity Assessment Guidelines

- Dent

A local reduction (plastic deformation) in the tube diameter due to corrosion products from carbon steel.

- Ding

A local reduction (plastic deformation) in the tube diameter caused by manufacturing, support plate shifting, vibration, or other mechanical means.

For inspection purposes, the technique and analysis methods are driven by the location of the deformation

NUREG 2191 In NUREG 2191,Section XI.M19 STEAM GENERATORS, Under paragraph 3, Parameters Monitored or Inspected, and in Table X1-01, FSAR Supplemental Summaries for GALL-SLR Report Chapter XI Aging Management Programs, the following requirement does not align with TSTF-577 primary side inspection frequencies and doesnt exclude material that are not susceptible to SCC In summary, the NEI 97-06 program provides guidance on parameters to be monitored or inspected except for steam generator divider plate assemblies, tube-to-tubesheet welds, heads (channel or lower/upper heads), and tubesheets. For these latter components, visual inspections are performed at least every 72 effective full power months or every third refueling outage, whichever results in more frequent inspections. These inspections of the steam generator head interior surfaces including the divider plate are intended to identify signs that cracking or loss of material may be occurring (e.g., through identification of rust stains).

Supplement to NUREG 1801 - LR-ISG-2016 For plants that applied for license renewal after this interim staff guidance, the same requirement that visual inspections are performed at least every 72 effective full power months or every third refueling outage, whichever results in more frequent inspections The interim staff guidance is specific to steam generators with susceptible materials Industry thinks the best way to handle this is with interim staff guidance 30 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Acronyms GALL - Generic aging lessons learned IG - Interim guidance ISG - Interim staff guidance LARs - License amendment requests MRPC - Motorized rotating pancake coil NEI - Nuclear Energy Institute NUREG - NRC Publication (Nuclear Regulatory)

OD - Outer diameter ODSCC - Outside diameter stress corrosion cracking PHWR - Pressurized heavy water reactor PWR - Pressurized water reactor 31 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

Acronyms SCC - Stress corrosion cracking SG - Steam generator SGMP - Steam Generator Management Program SLR - Subsequent license renewal TSP - Tube support plate TSTF - Technical Specification Task Force TT - Thermally treated TW - Through wall 32 www.epri.com © 2021 Electric Power Research Institute, Inc. All rights reserved.

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