L-2023-034, Relief Request 4RA-22-001, Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2)

Relief Request 4RA-22-001, Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2)

ML23055A289
Person / Time
Site:	Seabrook
Issue date:	02/24/2023
From:	Strand D NextEra Energy Seabrook
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2023-034
Download: ML23055A289 (1)

Text

NEXTera.,

EN~(§~~

February 24, 2023 10 CFR 50.55a L-2023-034 Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Seabrook Station Docket No. 50-443

Subject:

Relief Request 4RA-22-001, Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2)

In accordance with the provisions of 10 CFR 50.55a(z)(2), NextEra Energy Seabrook, LLC (NextEra) requests NRC approval of the attached reliefrequest for Seabrook Station (Seabrook).

Relief is requested from the applicable American Society of Mechanical EngineersSection XI Code (ASME Code) examination requirements identified in this request.

This relief is necessary to perform proactive modifications on the channel head bowl drain connection on each steam generator at Seabrook to alleviate future potential primary water stress conosion cracking concerns identified in Information Notice 2005-02, "Pressure Boundary Leakage Identified on Steam Generator Bowl Drain Welds." Implementation of these modifications is scheduled in the Seabrook refueling outage starting on April 1, 2023. The basis for the relief is that compliance with the specified ASME Code examination requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Enclosures 1, 3, and 4 to this letter supersede those provided in letter SBK-L-22094 dated October 26, 2022. It should be noted that the only difference is a new Enclosure 1 as Enclosures 3 and 4 are unchanged from October 26, 2022. Enclosure 2 is not included because it was previously submitted (ML22300A027). The details of the subject Relief Request 4RA-22-001 are provided in Enclosure 1. Enclosure 2 provides the proprietary proposed alternative design details, and Enclosure 3 contains the Affidavit of Mr. Zachary S. Harper of Westinghouse certifying that the material provided in Enclosure 2 is proprietary in nature. Enclosure 4 provides the non-proprietary proposed alternative design details. NextEra requests that the material provided in Enclosure 2 be withheld from public disclosure under the provisions of 10 CFR 2.390, Public Inspections, Exemptions, Requests for Withholding.

NextEra requests NRC review and approval of the proposed relief request prior to April 1, 2023 to allow its use in the upcoming refueling outage.

NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

United States Nuclear Regulatory Commission SBK-L-22094/Page 2 There are no commitments being made in this submittal.

If you have any questions regarding this submittal, please contact Mr. Kenneth Mack, Licensing Manager at (561) 904-3635.

Sincerely, Dianne Strand General Manager Regulatory Affairs Enclosures cc:

NRC Region I Administrator NRC Project Manager NRC Senior Resident Inspector

Enclosure 1 to Relief Request 4RA-22-001 Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2)

Page 1. of Z EC EVAL ENCLOSURE 1 ASME SECTION XI RELIEF REQUEST 4RA-22-001 REQUEST FOR RELIEF FROM THE REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) BOILER AND PRESSURE VESSEL CODE (CODE) CONCERNING REQUIREMENTS FOR TEMPER BEAD WELDS

Page J of Z Proposed Alternative In Accordance with 10 CFR 50.55a(z)(2)

--Hardship or Unusual Difficulty Without Compensating Increase in Level of Quality or Safety--

1. ASME Code Components Affected ASME Code Class I Steam Generators (SG's)

• 1-RC-E-11-A

• 1-RC-E-11-B

• 1-RC-E-11-C

• 1-RC-E-11-D Size: 1" NPS drain line Materials:

• SG Bottom Channel Head Bowl - ASME SA-533, Grade B, Class 1

• Coupling - See Enclosure 2

• Weld Metal - See Enclosure 2

• 3/8" Penetrating Tube - See Enclosure 2

2. Applicable Code Edition and Addenda

• ASME Section XI, 2013 Edition/No Addenda

• Seabrook Station is currently implementing its Fourth ASME Section XI 10-Year Interval, which began on 8/19/2020, and ends on 8/18/2030.

• ASME Section Ill, 1971 Ed through Summer 1973.

NOTE - Later editions of ASME Ill are specifically referenced in some sections, as the original code of record did not include provisions for temper bead welding.

3. Applicable Code Requirement

ASME Code,Section XI, Subsection IWA provides requirements for repair/replacement activities including the following:

• IWA-4633.1 (d) specifies the following pre-heat requirement for Temper Bead Welding of Dissimilar Materials with Shielded Metal-Arc Welding

Page J of Z o The area to be welded plus a band around the area of at least 1. 5 times the component thickness, or 5 in. (125 mm), whichever is less, shall be preheated and maintained at a minimum temperature of 350°F (175C). The maximum interpass temperature shall be 450°F (230C) .

• IWA-4634.1(b) provides the following examination requirement for Temper Bead Welding of Dissimilar Materials o For SMAW, the weld shall be examined after the completed weld has been at ambient temperature for at least 48hr. For GTAW, the nondestructive examinations shall be performed after the completed weld has cooled to ambient temperature. The examination of the welded region shall include both volumetric and surface examination.

4. Reason for Request

NextEra requests relief from the ASME Section XI IWA-4633.1 (d) requirement to maintain a minimum preheat temperature of 350°F, and the IWA-4634.1 (b) requiremer.it to perform volumetric examination of the welded region, as they would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

The design and manufacture of Seabrook Station's four Steam Generators included a drain line coupling at the center of the channel head bowl. The drain line was fabricated by filling a machined cavity with Alloy 182 weld metal and subsequently post weld heat treated . A through-the-shell hole was subsequently drilled in the channel head, and an Alloy 600 tube was hard rolled into the hole to provide a primary water flow path and seal welded at the ID and OD of the SG. The weld buildup was then machined for installation of a stainless-steel coupling, which was welded with a partial penetration weld joint and reinforcing fillet weld .

Additional description and illustrations of the original design and fabrication of the Seabrook Station steam generator bowl drains is provided in Enclosure 1.

Industry OE has shown that the Alloy 600 Alloy 82/182 weld filler material is susceptible to Primary Water Stress Corrosion Cracking (PWSCC), as several plants with similar designs have experienced boric acid leakage through this connection.

(REFERENCE 1)

This safety risk is currently mitigated by performing a visual VT-2 inspection each outage .

Seabrook Station is currently planning an ASME Section XI Repair and Replacement activity that will fully remove the Alloy 600 leak path by removing the existing Alloy 182 weld metal and replacing it in accordance with Enclosure 2.

Page .1 of z Welding will be performed with the SMAW temper bead process, and in accordance with all other requirements specified in ASME Section XI IWA-4633.1. The welding application will be similar to ASME Section XI Figure IWA-4623.1-1 and will include a butter layer applied to the P3 surfaces of the channel head bowl. The weld bead crown is then removed , and subsequent temper layers are applied followed by a post weld elevated temperature soak. The remaining layers are then applied and the weld is prepared for the coupling .

Additional description and illustration of the planned modification are also provided in Enclosure 1.

• Note that Attachment B of Enclosure 1 states that the temper bead welding technique will be in accordance with ASME Section Ill Paragraph NB-4622.9(d), and ASME Section XI Paragraph IWA-4630. The reference to NB-4622.9(d) applies to editions of ASME Ill that are later than the original code of record, as the original code did not include provisions for temper bead welding. A typical edition of ASME Ill that contains the paragraph is specified in Reference 4.

Completion of this activity will eliminate the concern associated with PWSCC cracking of the Steam Generator Bowl Drain.

5. Proposed Alternative and Basis for Use

5.1 Proposed Alternative Proposed Alternative to IWA-4634.1 (b):

As an alternative to final volumetric inspection NextEra proposes to perform progressive surface exams with the Liquid Dye Penetrant Examination (PT) process.

Three bead layers will be applied. PT examination will be performed on 100% of each layer's surface. PT of the third layer will be performed following the post weld soak and 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold. The weld area will then be prepared for installation of the coupling. A detailed weld and NOE sequence is provided in Enclosure 1. All NOE exams will be performed with examiners and procedure qualified in accordance with ASME Section XI.

Proposed Alternative to IWA-4633.1(d):

As an alternative to maintenance of a 350°F degree preheat for the entirety of the temper bead process, NextEra proposes to allow for a reduction of preheat to not less than 300°F to facilitate the progressive dye penetrant examinations proposed above. The 350°F preheat will be maintained during all temper bead welding.

Page .2. of Z 5.2 Basis For Use Due to a variety of factors, including the weld joint configuration, materials and accessibility, the use of the Radiographic or Ultrasonic volumetric examination methods are not suitable for this application. The impracticality of each volumetric method is described below.

Impracticality of Radiographic & Ultrasonic Inspection As described in Enclosure 1, attempts to develop an ultrasonic examination method have been unsuccessful, largely due to the geometry of the bowl drain, and the partial fill design. These attempts resulted in an inability to accurately detect and characterize identified indications.

As noted in Enclosure 1, the configuration of the channel head also results in an inability to obtain meaningful results with the radiographic examination method.

This inability is due to the following:

• Optimum source placement would be inside the channel head bowl, which has access limitations.

• The thickness of the repair region requiring radiography is significantly thinner than the overall thickness of the shell, and requires a source-side plaque Image Quality Indicator (IQI) designation 10 per Table IX-3325-1 of ASME Ill.

Use of this ASME Ill required IQI would result in an unachievable IQI image .

• If a larger source-side IQI designation for the entire shell thickness were utilized, indications in the temper bead weld and associated HAZ would likely be missed.

Suitability of Proposed Alternative The original owner's code requirement for the steam generator bowl drain was ASME Section Ill Division 1, 1971 Edition with Addenda up to and including Summer 1973. Later editions of this code allow for progressive surface examination for temper bead repairs to partial penetration welds, in lieu of volumetric examination if meaningful results cannot be obtained. (Example Provided in Reference 3, NB-4622.11 (d)(3)) This provides a precedent for the suitability of progressive surface exams in lieu of volumetric exams for partial penetration joints, when meaningful results cannot be obtained with volumetric methods. Although the bowl drain joint is not a partial penetration groove weld, it has joint complexity that prevents the ability to obtain meaningful volumetric inspection results.

Page_§_ of z Also, Precedent 1 documents the NRC staff's approval of progressive PT in lieu of volumetric inspection of temper bead welds on a reactor vessel head repair.

Impracticality of maintaining 350 °F preheat The minimum preheat temperature of 350°F is also the maximum allowable temperature for dye penetrant testing. If heating machines are set to 350°F it is highly likely that the actual metal temperature in several locations will exceed 350 °F by several degrees. To avoid compromising the accuracy and integrity of the NOE process, the material temperature will be lowered to a temperature not less than 300°F.

Suitability of Proposed Alternative The reduction of preheat will not occur until after the completed weld layer has cooled to 350°F, meaning the cooling rate and associated stresses will not be impacted. Similarly, the preheat will be fully restored from 300 °F to 350 °F and maintained for a minimum of 15 minutes prior to resuming welding .

Additionally, testing performed by the Electric Power Research Institute (Reference

2) concluded that SMAW temper bead welding at ambient temperature resulted in welds with acceptable HAZ toughness properties, and did not increase susceptibility to delayed hydrogen cracking as the main pathway for diffusible hydrogen is the SMAW electrode coating, which is mitigated by using low hydrogen techniques prescribed by ASME Section XI, IWA-4633. This is further supported by NRC Approved ASME Section XI Code Case N-839, which allows for ambient temperature SMAW temper bead welding . Seabrook Station is not implementing code case N-839, however, the basis of the case provides assurance that a controlled reduction to 300°F followed by a controlled restoration to 350°F will not impact weld quality.

Conclusion The geometry of the steam generator bowl drain modification results in an inability to obtain meaningful results with either the ultrasonic or radiographic examination method. Precedence in the ASME Section Ill code for partial penetration groove welds, as well as a precedent approval provide a basis for concluding that the use of progressive liquid penetrant examination for the Seabrook Station steam generator bowl drain modification is a suitable alternative to volumetric inspection and provides reasonable assurance of structural integrity because sound welds are deposited.

Page Z of Z Additionally, the methods proposed to lower and restore preheat will be sufficient to ensure the final weld will not be impacted. This is also supported by EPRI tests results, and approved ASME Section XI Code Cases.

6. Duration of Proposed Alternative

The duration of this proposed alternative will be the remaining life of the plant.

7. Precedents

1. Safety Evaluation Report (SER) by the Office of Nuclear Reactor Regulation, "lnservice Inspection Program Relief Request PWR-R&R-001 Entergy Operations Inc, Arkansas Nuclear One, Units 1 And 2 (ANO-1 AND ANO-2) AND Waterford Steam Electric Station Unit 3 (Waterford 3)." (ML031060501)

8. References

1. Westinghouse Technical Bulletin TB-04-19, "Steam Generator Channel Head Bowl Drain Line Leakage", 10/18/2004.

2. Electric Power Research Institute Welding and Repair Technology Center Technical Report 3002005536, "Shielded Metal Arc Temper Bead Welding",

October 2015.

3. ASME Section Ill, Rules for Construction of Nuclear Facility Components Division 1, Article NB-4622.11 (d)(3) 1998 Edition, No Addenda.

4. ASME Section Ill, Rules for Construction of Nuclear Facility Components Division 1, Article NB-4622.9(d) 2010 Edition, No Addenda.

9. Enclosures

1. Affidavit

2. Westinghouse Non-Proprietary Technical Summary

Enclosure 3 to SBK-L-22094 Relief Request 4RA-22-001 Proprietaiy Information Affidavit Supporting Request for Withholding

Westinghouse Non-Proprietary Class 3 AFFIDAVIT CA W-22-053 Page 1 of3 COMMONWEALTH OF PENNSYLVANIA:

COUNTY OF BUTLER:

(1) I, Zacha1y S. Harper, have been specifically delegated and authorized to apply for withholding and execute this Affidavit on behalf of Westinghouse Electric Company LLC (Westinghouse).

(2) I am requesting the proprietaty portions ofLTR-CECO-22-086-P, Revision 0,"Supporting Information for Seabrook Steam Generator Channel Head Drain Modification Relief Request," be withheld from public disclosure under 10 CFR 2.390.

(3) I have personal knowledge of the criteria and procedures utilized by Westinghouse in designating info1mation as a trade secret, privileged, or as confidential commercial or financial infonnation.

(4) Pursuant to 10 CFR 2.390, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.

(i) The infonnation sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse and is not customarily disclosed to the public.

(ii) The inf01mation sought to be withheld is being transmitted to the Commission in confidence and, to Westinghouse's knowledge, is not available in public sources.

(iii) Westinghouse notes that a showing of substantial harm is no longer an applicable criterion for analyzing whether a document should be withheld from public disclosure. Nevertheless, public disclosure of this proprietary information is likely to cause substantial hann to the competitive position of Westinghouse because it would enhance the ability of competitors to provide similar technical evaluation justifications and licensing defense services for commercial power reactors without commensurate expenses. Also, public disclosure of the infotmation would enable

... This record was final approved on 10/13/2022, 7:48:43 AM . (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 AFFIDAVIT CA W-22-053 Page 2 of3 others to use the information to meet NRC requirements for licensing documentation without purchasing the right to use the information.

(5) Westinghouse has policies in place to identify proprieta1y information. Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows:

(a) The infonnation reveals the distinguishing aspects of a process (or component, stmcture, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies.

(b) It consists of suppotiing data, including test data, relative to a process (or component, stmcture, tool, method, etc.), the application of which data secures a competitive economic advantage (e.g., by optimization or improved marketability).

(c) Its use by a competitor would reduce his expenditure ofresources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing a similar product.

(d) It reveals cost or price information, production capacities, budget levels, or commercial strategies of Westinghouse, its customers or suppliers.

(e) It reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.

(f) It contains patentable ideas, for which patent protection may be desirable.

(6) The attached documents are bracketed and marked to indicate the bases for withholding. The justification for withholding is indicated in both versions by means of lower-case letters (a) through (f) located as a superscript immediately following the brackets enclosing each item of

• • • This record was final approved on 10/13/2022, 7:48:43 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 AFFIDAVIT CA W-22-053 Page 3 of3 information being identified as proprietary or in the margin opposite such information. These lower-case letters refer to the types of information Westinghouse customarily holds in confidence identified in Sections (S)(a) through (f) of this Affidavit.

I declare that the averments of fact set f01th in this Affidavit are tme and correct to the best of my knowledge, information, and belief.

I declare under penalty of petjuty that the foregoing is ttue and correct.

Executed on: 10/13/2022

~

Zachaty S. Harper, Manager Licensing Engineering

• • • This record was final approved on 10/13/2022, 7:48:43 AM. (This statement was added by the PRIME system upon its validation)

Enclosure 4 to SBK-L-22094 Relief Request 4RA-22-001 Westinghouse Non-Proprietaiy Technical Summary

Westinghouse Non-Proprieta1y Class 3

@Westinghouse To: Shane Webb (NextEra Energy) Date: October 12, 2022 cc: Tim O'Connor Nathan Lang Michael Tronosky Michael Mudawar From: Michael A. Roth Your Ref. NIA Ext: (724) 722-5082 Our Ref. LTR-CECO-22-086-NP, Rev. 0

Subject:

Supporting Information for Seabrook Steam Generator Channel Head Drain Modification Relief Request This letter serves to transmit information to support NextEra Energy's planned submittal of a relief request to the United States Nuclear Regulato1y Commission (USNRC) for the Seabrook steam generator channel head drain modification program. The relief request will request permission to use a progressive liquid penetrant examination technique in lieu of volumetric examination during execution of the field modifications.

Attachment A of this letter provides information on the original design and fabrication of the Seabrook Westinghouse Model F steam generators. Attachment B of this letter provides infonnation on the design of the modified Seabrook steam generator channel head drain configuration. Attachment C of this letter provides the planned sequence for the removal of the original channel head drain couplings and installation of the replacement drain couplings.

Attachment D of this letter describes the impracticality of radiographic examination of the modified steam generator channel head drain. Attachment E of this letter provide the basis for a reduction in preheat temperature during liquid penetrant examination of the modified channel head drain.

Finally, Attachment F of this letter provides a summaiy of the results of a program perfo1med by Westinghouse to determine the feasibility of inspecting the modified channel head drain configuration using ultrasonic (UT) techniques.

© 2022 Westinghouse Electric Company LLC All Rights Reserved

... This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 2 of 17 Ow- ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 If there are any questions, please contact the undersigned.

Author: Electronically Approved

• Michael A. Roth Component Engineering & Chemishy Operations Electronically Approved

• David S. Taylor (Attachments A & B)

Component Engineering & Chemishy Operations Electronically Approved

• David Batton (Attachments C & E)

WWM Engineering Electronically Approved

• Mark Kirby (Attachments D & F)

Reactor & BOP Inspection Resources Verifier: Electronically Approved

• Luke M. Vorce (Attachments A & B)

Component Engineering & Chemishy Operations Electronically Approved

• Michael Barrett (Attachments C & E)

Design Engineering Electronically Approved

• David Barton (Attachments D & F)

WWM Engineering Approved: Electronically Approved

• Robert S. Chappo /for Nicole D. Vitale, Manager Component Engineering & Chemishy Operations

• Electro11ically approved records are authenticated ill the e/ectro11ic doc11me11t ma11ageme11t system.

... This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 3 of 17 Om ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Attachment A Original Design and Fabrication of Seabrook Steam Generator Channel Head Drain To drain reactor coolant (i.e., prima1y side water) from the channel heads of the Seabrook steam generators after plant shutdown but prior to primaiy side maintenance operations, a through-the-shell drain configuration was provided at the bottom center of the Model F steam generator channel heads. The drain configuration consists of an Alloy 600 pipe that provides a flow path for reactor coolant through the channel head's wall thickness. The entty end of the drain (within the channel head bowl) is located directly under the divider (partition) plate which separates the hot leg chamber from the cold leg chamber. A semi-circular opening in the divider plate (commonly refe1Ted to as a 'mouse hole') allows for drainage from both the hot leg and cold leg chambers simultaneously. A stainless-steel coupling is welded at the lower (i.e., outlet) end of the drain pipe external to the channel head. Drain line piping and valves are then welded to this coupling to provide any residual reactor coolant with a flow path out of the steam generator. Figure IA shows the original drain configuration in the Seabrook steam generators.

a,c,e Figure lA Ol"iginal Configuration of Seabrook Steam Generator Channel Head Drain In order to install the channel head drain during steam generator manufacture, channel head base metal was removed from the outer diameter surface of the channel head in the bottom center location to create a cavity with a [ ]a.c,e_inch nominal depth. The cavity was then completely filled in using [

]3,c,e filler metal. For the first

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprieta1y Class 3 Page 4 of 17 Ow- ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 layer of weld material, a preheat temperature was maintained in the range of[ ]a,c,eoF to [ ]a,c,eoF. For the remaining layers of weld material, preheat was not required unless the temperature was below [ ]a,c,eoF, which then required preheat to raise the temperature to within the range of [ ]a,c,coF to [ ]",c,coF_

Following completion, the weld build-up was post-weld heat treated (PWHT) for a minimum of [ ]a,c,e hour at [ ]a,c,eoF. Liquid penetrant examination was performed on the final weld joint following PWHT.

After completion of welding, a nominal [ ]",c,c inch through-wall hole was then machined in the channel head and the [ ]a,c,e weld build-up was machined for fit-up of the drain coupling, including preparations for a pa1tial penetration weld to attach the drain coupling.

Following machining, the final machined surfaces of the preparations for the paitial penetration weld were liquid penetrant examined. Figure 2A shows the drain cavity after welding and preparatory machining.

a,c,e Figure 2A Channel Head Drain Cavity after Welding and Preparatory Machining Next, an [ ]"*c,c pipe was inse1ted into the channel head's through-wall hole and hard-rolled into position. The top (i.e., inlet) end of the drain pipe was then seal welded around its perimeter to the stainless-steel cladding on the inner diameter surface of the channel head using [

]",c,e filler metal and the final surface of the weld was liquid penetrant examined. Likewise, the lower (i.e., outlet) end of the drain pipe was welded around its perimeter to the [ ]a,c,e weld build-up in the previously machined cavity using [ ]",c,e filler metal and the weld was subsequently liquid penetrant examined. Both the welds at the upper and lower ends of the drain pipe had a minimum preheat temperature of [ ]a,c,cop with no PWHT required. The installed drain pipe, which is shown in Figure 3A, provides a batTier between the reactor coolant and the carbon steel base metal of the channel head.

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprieta1y Class 3 Page 5 of 17 Ow- ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 a,c,e Figure 3A Insertion of ASME SB-167 Drain Pipe Finally, an [ ]a,c,e stainless steel drain coupling was welded to the

[ ]",c,e weld build-up on the channel head's outer diameter using a paitial penetration weld that was capped by a fillet weld, as shown in Figure 4A. Both the paliial penetration weld and fillet weld were made using [ Ja,c,e filler metal with a minimum [ ]a,c,eoF preheat temperature. The welding of the drain coupling occurred after all major PWHTs affecting the channel head were completed. Liquid penetrant examination was performed on the partial penetration J-groove surface prior to the sta1t of welding, on the root pass of the pa1tial penetration weld, on the completed partial penetration weld prior to installation of the fillet weld, and on the final fillet weld.

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 6 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 a,c,e Figure 4A Installation of Drain Coupling

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 7 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Attachment B Design of Modified Seabrook Steam Generator Channel Head Drain In order to mitigate the potential of primary water stress corrosion cracking (PWSCC) in the Seabrook steam generator channel head drains, the drains will be modified to replace the existing drain coupling and American Society of Mechanical Engineers (ASME) [ ]",c,e weld build-up with a new drain coupling and partial thickness weld build-up. The drain modification has been designed and qualified in accordance with the design requirements of Section III of the 1971 Edition through Summer 1973 Addenda of the ASME Boiler and Pressure Vessel (B&PV) Code, which is the original code of constrnction for the Seabrook steam generators. The drain modification shall be performed in accordance with Westinghouse Drawing 10166D84.

The channel head drain modification process will begin with the complete removal of the existing (i.e.,

original) drain coupling, [ ]",c,e weld build-up, and the weld build-up's entire heat affected zone. During the removal of the weld build-up and the weld build-up's heat affected zone, a short length of the lower (i.e., outlet) end of the existing drain pipe will be trimmed such that it is flush with the base metal of the channel head. Note that this process will also remove the existing seal weld between the lower end of the drain tube and the [

]",c,c weld build-up. Following machining, the surfaces of the channel head base metal will be acid etched to verify that all weld build-up material and the weld build-up's heat affected zone have been removed. Figure IB shows the drain configuration following completion of machining operations.

a,c,e Figure lB Drain Configuration Following Removal of Drain Coupling and Weld Build-up

... This record was final approved on 10/13/2022, 8:53:33 AM . (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprieta1y Class 3 Page 8 of 17 Ow- ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Following the removal of the weld build-up and the weld build-up's heat affected zone, the lower end of the drain coupling will be seal welded around its perimeter to the adjacent channel head base metal using [

1*,c,c weld material. Following completion of the seal weld, the seal weld and newly machined surfaces of the channel head will be liquid penetrant examined in accordance with the requirements of Section III, Subsection NB-5350 of the 1971 Edition through Summer 1973 Addenda of the ASME B&PV Code. (Note: The seal weld is to be completed prior to the liquid penetrant examination of the channel head base metal surfaces in order to prevent the repo1ting of false indications at the annular gap between the outer diameter of the drain pipe and the inner diameter of the machined bore in the channel head base metal.) Figure 2B shows the drain configuration following completion of the drain pipe seal weld.

a,c,e Figure 2B Drain Configuration Following Installation of Drain Pipe Seal Weld Next, a buttering will be applied to the surfaces of the newly machined channel head cavity using [

1*,c,e weld material. The buttering will be applied using a half bead temper bead weld technique in accordance with Paragraph NB-4622.9( d) of Section III of the ASME B&PV Code and Paragraph IWA-4630 of Section XI of the ASME B&PV Code. Thus, field-implemented post-weld heat treatment (PWHT) of the buttering is not required. Each layer of buttering applied will be liquid penetrant examined in accordance with the requirements of Section III, Subsection NB-5350 of the 1971 Edition through Summer 1973 Addenda of the ASME B&PV Code. Figure 3B shows the drain configuration following completion of the channel head base metal buttering.

• • • This record was final approved on 10/13/2022, 8:53:33 AM. {This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 9 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 a,c,e Figure 3B Drain Configuration Following Installation of Channel Head Base Metal Buttering Following the application of the buttering, the buttering will be manually prepared for the installation of the replacement drain coupling. Then, the replacement drain coupling will be installed via a partial penetration weld designed in accordance with Paragraph NB-3352.4(d) of Section III of the ASME B&PV Code. The pattial penetration weld will be installed using [

)",c,c or [ ]a,c,c weld material.

(Note: The pa1tial penetration weld will not require PWHT as the weld will attach the replacement drain coupling to the previously installed [ ]a,c,e buttering and will not directly contact the channel head's carbon steel base metal.) In accordance with Paragraph NB-3352.4( d) of Section III of the ASME B&PV Code, the partial penetration weld will be liquid penetrant examined progressively at an interval of eve1y 3/16 inch of weld thickness in accordance with the requirements of Section III, Subsection NB-5350 of the 1971 Edition through Summer 1973 Addenda of the ASME B&PV Code. Upon completion of the partial penetration weld, the final surface of the weld will be liquid penetrant examined in accordance with the requirements of Section III, Subsection NB-5350 of the 1971 Edition through Summer 1973 Addenda of the ASME B&PV Code.

Finally, the pattial penetration weld will be capped with a fillet weld using [

]a,c,e or [

]a,c,c weld material. (Note: The fillet weld will not require PWHT as the weld will attach the

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 10 of 17 Om ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 replacement drain coupling to the previously installed [

t ,c,e or [ ]a,c,e partial penetration weld and will not directly contact the channel head's carbon steel base metal.) Upon completion, the final surface of the fillet weld will be liquid penetrant examined in accordance with the requirements of Section III, Subsection NB-5350 of the 1971 Edition through Summer 1973 Addenda of the ASME B&PV Code. Figure 4B shows the final modified drain configuration.

a,c,e Figure 4B Final Modified Drain Configuration

... This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 11 of 17 Om ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Attachment C Weld Removal and Steam Generator Drain Coupling Installation Sequence The sequence for the weld removal and steam generator drain coupling is below:

• Machine out the existing coupling and existing Alloy 600 material

• Verify all Inconel has been removed using Acid Etch

• Preheat challllel head to 350°P

• Petfonn seal weld between the tube and channel head - necessaty to permit the PT of the excavation

• Cool to 300°P to support high temp PT

• PT the excavation and seal weld

• Increase preheat to 350°P

• Install Layer 1 Temperbead with 3/32" Alloy 152M

• Surface condition the weld surface to remove crowns

• Reduce temperature to 300°P to support PT (assuming progressive PT is accepted)

• PT Layer 1

• Increase temperature back to 350°P

• Install Layer 2 using 1/8" Alloy 152M

• Surface condition the weld surface to remove crowns

• Reduce temperature to 300°P to suppott PT (assuming progressive PT is accepted)

• PT Layer 2

• Increase temperature back to 350°P

• Install Layer 3 using 1/8" Alloy 152M

• Surface condition

• Reduce temperature to 300°P to support PT (assuming progressive PT is accepted)

• PT Layer 3

• Post Hydrogen Soak 450 to 550°P for a minimum of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

• Cool to room temperature

• Hold for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />

• PT Temperbead installation

• Temperbead operation is now complete

• Condition pocket bottom (proximate to the drain tube) to install the coupling

• Weld install the coupling using either GTAW or SMAW Alloy 52M/152M

• Smface condition for PT of the weld surface

• PT weld surface

• Install Fillet weld

• PT fillet weld and VT

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 12 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Attachment D Impracticality of Radiographic Examination of Modified Steam Generator Channel Head Drain The geometty of the channel head and the new weld does not lend itself to optimum film and source placement.

Radiographic examination (RT) relies on a sufficiently large change in density, along the path taken by the radiation, to show up in the film. Just as with an x-ray of a broken bone, one takes images at multiple angles and only ce1iain views show the break. The geometty of the modified channel head drain weld makes obtaining the necessaiy multiple angles virtually impossible. The geometry will also complicate the sizing of any given indication. Any indication in the film will be a projection, based on the angle that the radiation passes it.

Foreshortening will occur and calculating what the actual length is from the projected view will ve1y likely yield e1rnnt results. These e1rnnt results could result in an acceptable indication being perceived as unacceptable and leading to the unnecessary removal and re-application of weld material, which will subsequently increase radiological dose received by the field crew.

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 13 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Attachment E Preheat Reduction for Liquid Penetrant Examination The temper bead repair will be performed in accordance with the requirements of ASME Section XI, IWA-4630, 'Temper Bead Welding of Dissimilar Materials" except as approved by the reliefrequest As pati of the requirements, IWA-4633.l(d) specifies a 350°F preheat shall be applied and maintained during the temper bead po1iion of the welding. As part of the relief request for the use of progressive liquid penetrant examination in lieu of volumetric examination, the requirement to maintain a 350°F preheat creates a hardship. Specifically, maintaining a minimum preheat temperature of 350°F provides no margin to apply the liquid penetrant materials which have a maximum temperature of 350°F.

To be able to perform the liquid penetrant examination, the preheat temperature would need to be lowered to a temperature below 350°F for the period required to perform the examination. A temperature of 300°F is proposed to provide a suitable temperature for the examination and maintain good low hydrogen practice. The Engineering basis for this reduction considers the following three specific topics which address heat affected zone cracking potential.

1. ASME Section III Subsection NB, which is followed for the manufacture of steam generators and other nuclear vessels, recommends (in Paragraph NB-4611) the use of ASME Section III Appendices, Nonmandato1y Appendix D as a basis for preheating materials by P-number. ASME Section III Appendices, Nonmandatory Appendix D recommends the use of 250°F preheat for the welding of P3 Group 3 materials, which were used in the fabrication of the Seabrook steam generator channel heads. As noted in Paragraph NB-4611, the preheat is a recommended preheat but may require additional heat based on constraint. The proposed reduction of preheat to 300°F for the examination time period only exceeds the welding preheat of 250°F as recommended in Appendix D with additional margin for constraint. It is impo1iant to note that no welding will be performed at the reduced preheat value. All welding for the temper bead p01iion of the repair will be perf01med at the required minimum preheat of 350°F.

2. The filler metal to be used for the repair is ENiCrFe-7, which is a fully austenitic material. Any local hydrogen produced during welding will remain preferentially in solution in the austenitic filler metal where it is soluble.

3. The welding filler metal will be stored and maintained in accordance with the requirements of Paragraph IWA-4633 .1.

The planned duration for each Liquid Penetrant examination is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. This time includes the cool down ramp, surface preparation, examination and heat up ramp to 350°F. The ramp rates for both heating and cooling will not exceed 200°F /hour. When the minimum preheat temperature of 3 50°F is re-established, it will be held for 15 minutes and re-checked to assure the 350°F minimum preheat is established prior to welding.

The reduction of preheat to 300°F for liquid penetrant examination only provides adequate margin to assure that the maximum temperature for the materials used for the examination are not exceeded while maintaining good low hydrogen practice to avoid heat affected zone cracking. All welding will be perf01med in accordance with the Paragraph IWA-4633 requirements of 350°F minimum preheat.

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 14 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Attachment F Ultrasonic Inspection of SIG Drain Line Repair Limitations A project was initiated to develop an ultrasonic inspection method to perfo1m a volumetric inspection of the proposed repair of the SIG drain line at Millstone unit 3.

1. Sample Development A review of the ASME Code was performed to identify the applicable flaw type and dimensions applicable for this repair. These were located in the samples to provide the basis for demonstrating the UT technique was suitable for the application.

In addition, volumetric type ofreflectors, which would be acceptable in the field repair, were included.

Three different samples were made, ofvaiying depth of fill : 0.75", l.O", and a full fill.

2. Probe Development Work with multiple vendors was initiated to design and develop applicable probes for this application. Since the paiiial fill designs would preclude scanning a probe, in the traditional sense, a phased array technique was selected to allow for the steering of the beam to insonify the weld volume and the heat effected zone of the base metal.

CIV A modeling was performed to assist in the probe design and the flaws present in the samples were placed in the CIVA model to assist in finalizing the probe design.

3. Technique Development The probes and phased array UT instrnment were used to scan the samples and develop a procedure for the scanning and interpreting the data obtained.

4. Demonstration A demonstration was given to Dominion representatives the week of August 15 11\ and limitations to the technique were identified.

Those limitations, and proposed additional eff01is that could address them, are summarized below.

1. Coverage.

Inspection must be 100% of the weld volume. At present, there is a volume close to the inspection surface, at the radial minimum and extremes, where there does not appear to have coverage.

2. Low angle usage.

The EPRJ PDI Weld Overlay Procedure (ERPI-WOL-PA-1 Rev. 5) Table 8.9-1 Coverage angle ranges list <4.0" Component Diameter Axial scans angle range for coverage are 45° to 80° For components > or = to 4.0" diameter Angle ranges for Axial scans are 25° to 80°.

• • • This record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 15 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 Thus, to comply with these requirements, sector sweep angles less than 25° cannot be used. Multiple flaws were only detected with angles less than 10°.

3. Relevant vs Non relevant Indications It is difficult to distinguish relevant (planar flaws) from non-relevant (volumettic) reflectors in coupons.

Per the ASME Code, a crack or lack of fusion, of any size, is rejectable.

Volumetric flaws are only rejectable if they exceed a specific length.

The fact that the technique cannot clearly distinguish between the two types of reflectors, could lead to false positives.

4. Volumett*ic Length Measurement As stated previously, volumetric indications below a specified length are acceptable.

At present, the technique overestimates the length of volumetric indications. This could result in false positives.

5. Flaw sample set in coupons One Dominion representative stated that there may be flaws that are "harder to find" in the field compared to the flaws in the coupons.

6. Transverse Flaws The ability of the technique to detect flaws in this 01ientation is marginal. In addition, length sizing is limited. It was even more difficult to detect these types of flaws in the full fill sample.

7. Field Ergonomics During the demonstration, the samples were laying on the ground and it was relatively easy for the operator to scan them. Work in the field will be overhead in a high dose zone. Not clear how this will affect the inspector' s performance.

5. Challenges Associated with the Full Fill

1. UT Issues It was noted during the development that the attenuation of the weld repair was sufficient that the full fill posed unique challenges over and above the partial fill samples.

Based on this experience, and based on other EPRI WOL applications, the use of a lower frequency probe is the solution to this attenuation issue. Thus, for the full fill, a lower frequency probe (1 MHz) would need to be investigated.

Initial evaluations could be performed using the CIVA model, however, a I MHz probe would need to be procured and the full fill sample scanned to benchmark the CIVA model results and demonstrate the ability to find, characte1ize, and length size the flaws in the full fill sample.

• 0 Th is record was final approved on 10/13/2022, 8:53:33 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 16 of 17 Our ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022

2. Welding Issues Full Fill One approach to the repair to the bowl drain is to repair in a like for like, full fill configuration. The welding repair in the field will require temper bead welding approach due to the Channel Head material. There are two Temperbead approaches which can be utilized; ASME Section XI, IWA-4630 which requires Preheat and Post Hydrogen Soak or Code Case N839/888 which is Ambient Temperbead. Both approaches require the application of 3 layers of weld metal in a controlled manner to excavation. With a full fill approach, to accomplish proper tempering at the comer junction of the channel head sw-face and the excavation, the temperbead layers will have to be installed up to the comer and then extended out onto the surface of the channel head. The width of the band of weld metal has to be wide enough to support the required 3 layers for proper tempering. After the 3 layers of temperbead have been applied to the sw-face of the excavation including the material applied to the surface of the channel head, and post temperbead welding requirements fulfilled, the coupling will be installed using a J-groove approach using normal welding practice followed by the installation of the fillet weld.

To support UT examination with a full fill approach, the temperbead material applied to the channel head surface will have to be ground off to facilitate a smoot h*ansition for the UT probe. Additionally, the material between the coupling and the temperbead will have to be ground to meet the radial dimensions of the channel head using templates as guidance to assure proper UT coverage and smooth probe traverse. UT and surface examinations will be performed after surface contouring has been complete.

After successful UT examination of the weld, the fillet weld between the coupling and ground surface will be installed.

Partial Fill The approach that has been successfully used on Pl Channel head drain line repairs is to partially fill the excavation to 5/8" depth followed by the installation of the fillet weld. With the P3 G3 Channel material will require Temperbead welding technique. Using Temperbead technique, the layers will be contained within the excavation and limited to the depth required to meet the mechanical requirement of the repair design. After the 3 layers ofTemperbead are installed and post Temperbead requirements fulfilled, the coupling will be installed using a J-Groove paitial peneh*ation weld using normal welding practice. The surface of the completed weld will require ve1y careful surface preparation to meet the smoothness and contour required for the UT probe.

Following the successful UT examination, the surface will be inspected with Liquid Penetrant (PT).

The fillet weld will then be installed and inspected with VT and PT.

False positives with either path, Full Fill or Partial Fill, will create repairs which may require the removal of the material within the Temperbead po1tion of the repair weld. This will require observance of the original Temperbead methodology used for the repair. Excavation to support Temperbead repair to the repair will result in additional material removal to fonn a suitable excavation to support proper tempering. Once completed, the surface will require additional blending to achieve a suitable surface

. .. This record was final approved on 10/13/2022, 8:53:33 AM . (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietaiy Class 3 Page 17 of 17 Om ref: LTR-CECO-22-086-NP, Rev. 0 October 12, 2022 to support the UT probe. Given the extent of the reported indication, full removal may be required due to the limited access within the repair excavation.

• • • This record was final approved on 10/13/2022, 8:53:33 AM . (This statement was added by the PRIME system upon its validation)