L-2023-059, Subsequent License Renewal Application - Aging Management Requests for Additional Information (RAI) Set 4 Supplemental Response

Subsequent License Renewal Application - Aging Management Requests for Additional Information (RAI) Set 4 Supplemental Response

ML23111A129
Person / Time
Site:	Saint Lucie
Issue date:	04/21/2023
From:	Strand D Florida Power & Light Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-2023-059
Download: ML23111A129 (1)

Text

L-2023-059 10 CFR 54.17 April 21, 2023

~PL.

U.S. Nuclear Regulatoiy Commission Attn: Document Control Desk 11545 Rockville Pike One White Flint North Rockville, MD 20852-27 46 St. Lucie Nuclear Plant Units 1 and 2 Dockets 50-335 and 50-389 Renewed Facility Operating Licenses DPR-67 and NPF-16 SUBSEQUENT LICENSE RENEWAL APPLICATION -AGING MANAGEMENT REQUESTS FOR ADDITIONAL JNFORNIATION (RAD SET 4 SUPPLEMENTAL RESPONSE

References:

1. Florida Power & Light Company (FPL) letter L-2021-192, Subsequent License Renewal Application -Revision 1, October 12, 2021 (ADAMS Package Accession No. ML21285A106)

2. FPL letter L-2022-043, Subsequent License Renewal Application Revision 1 - Supplement 1, April 7, 2022 (ADAMS Accession No. ML22097A202)

3. FPL letter L-2022-044, Subsequent License Renewal Application Revision 1 - Supplement 2, April 13, 2022 (ADAMS Accession No. ML22103A014)

4. FPL letter L-2022-071, Subsequent License Renewal Application Revision 1 - Supplement 3 May 19, 2022 (ADAMS Accession No. ML22139A083)

5. Electronic memorandum from Mr. Brian Harris, U.S. Nuclear Regulatoiy Commission (NRC), to Mr. Robert Coffey, NextEra Energy Chief Nuclear Officer, dated November 18, 2022, SLRA Safety Review Set 4 RAJs (ADAMS Package Accession No. ML22325A067).

6. FPL letter L-2023-026, SUBSEQUENT LICENSE RENEWAL APPLICATION -AGING MANAGEMENT REQUESTS FOR ADDITIONAL JNFORNIATION (RAJ) SET 4, MARCH 27, 2023 (ADAMS ACCESSION No. ML23086B990)

In Reference 1, as supplemented by References 2 through 4, Florida Power & Light Company (FPL), submitted a subsequent license renewal application (SLRA) for the Facility Operating Licenses for the St. Lucie Nuclear Plant, Units 1 and 2 (PSL). In Reference 6, FPL responded to the NRC's set 4 of requests for additional information (RAJs) provided in Reference 5.

Subsequent to the Reference 6 submittal, FPL determined that the Set 4 RAJ responses required additional aging management information. Accordingly, Attachments 1, 2, and 3 to this letter supersede in their entirety the Set 4 RAJ responses in Attachments 1, 2 and 3 to Reference 6.

Florida Power & Light Company 15430 Endeavor Drive, Jupiter, FL 33478

St. Lucie Nuclear Plant Units 1 and 2 L-2023-059 Dockets 50-335 and 50-389 Page 2 of 3 For ease of reference, the index of attached information is provided on page 3 of this letter. Certain attachments include associated revisions to the SLRA (Enclosure 3Attachment1 of Reference 1, as supplemented by References 2 - 4) denoted by strikethrough (deletion) and/or bold red underline (insertion) text. Previous SLRA revisions are denoted by bold black text. SLRA table revisions are included as exce1pts from each affected table.

These RAI responses provide additional information that clarify the PSL SLRA, do not expand the scope of the SLRA as originally noticed, and should not change the NRC staffs original proposed no significant hazards consideration determination as published in the Federal Registe1:

Should you have any questions regarding this submission, please contact Mr. Michael Davis, Fleet Licensing Projects Manager, at 319-851-7032.

I declare under penalty of perjury that the foregoing is tme and correct.

Executed on the 21 st day of April 2023.

Sincerely,

'\)~ -::S /7 Dianne Strand General Manager Regulatory Affairs Florida Power & Light Company Cc: Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, St. Lucie Plant Chief, USNRC, Division of New and Renewed Licenses Senior Project Manager, USNRC, Division of New and Renewed Licenses Chief, Bureau of Radiation Control, Florida Department of Health

St. Lucie Nuclear Plant Units 1 and 2 L-2023-059 Dockets 50-335 and 50-389 Page 3 of 3 Attachments Index Atta.chment RAINo. Subject No.

1 B.2.3.23-1 Selective Leaching Environment 2 B.2.3.23-2 Selective Leaching Inspection 3 B.2.3.23-3 Selective Leaching Operating Experience

St. Lucie Nuclear Plant Units 1 and 2 L-2023-059 Dockets 50-335 and 50-389 Attachment 1 Response to RAI B.2.3.23-1 Selective Leaching Environment (12 pages follow)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 1 of 12 External Surfaces & Selective Leaching RAI B.2.3.23-1 Regulatory Basis:

Section 54.21 (a)(3) of Title 10 of the Code of Federal Regulations (10 CFR) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the U.S.

Nuclear Regulatory Commission (NRC) staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. In order to complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background:

SLRA Table 3.3.2-4, "Diesel Generators and Support Systems - Summary of Aging Management Evaluation," states the external surfaces of copper alloy with greater than 15 percent zinc heat exchanger radiator tubes exposed to air-indoor uncontrolled will be managed for reduction of heat transfer and cracking using the external surfaces monitoring of mechanical components program.

The staff recently became aware of operating experience at St. Lucie for an emergency diesel generator (EOG) radiator leak that occurred in June 2022. The cause of the leak was dezincification on the external surfaces of yellow brass EOG radiator tubes, which are exposed to an air - indoor uncontrolled environment. According to the NRC Resident Inspector, site personnel considered the leak to be a functional failure.

A subsequent review of historical operating experience by the NRC staff identified EOG radiator tube leaks in May and June of 2001 (Ref Licensee Event Report 335/2001-006 (ML012050195)). Although the radiator tube designs have been modified to eliminate the original soldered mechanical tube joints that had failed, the event report noted that corrosion of the radiator cooling fins was due to "humid salt-laden" air. The staff notes that the environment descriptions in SLRA Table 3.0-1 only includes salt-laden air for "Air - outdoor" and not for "Air indoor uncontrolled."

The air environment in the EOG rooms appears to be a more aggressive environment based on the presence of salt-laden air. Based on the air environment classification as "air-indoor uncontrolled," the staff seeks clarification for whether different aging management activities are warranted for this potentially more aggressive air environment and, if so, whether other locations in the plant are similarly exposed to a comparable environment.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.23-1 L-2023-059 Attachment 1 Page 2 of 12 Request:

Provide information regarding the need to adjust any aging management activities as a result of the potentially more aggressive air environment within the EOG rooms and whether other rooms would be similarly exposed to a comparable environment.

PSL Response:

The following discussion summarizes additional operating experience related to the St. Lucie Unit 1 and Turkey Point Unit 3 EOG radiators.

Several failures of the PSL Unit 1 EOG radiator tubing have occurred over the life of the plant.

Failures of the PSL 1 EOG radiator tubes were initially attributed to corrosion of the EOG radiator cooling fins from the humid salt-laden atmosphere that resulted in a loss of structural support of the radiator flat tubes. A summary of previous radiator tube failures and causes includes the following:

• June 1993-1A2/182 radiator failures (12-cylinder) were identified in CR 2007-36761 (AR 405699). No cause or detailed failure analysis of the radiator tube failure was found.

• May 1996- 1A2/182 radiator failures (12-cylinder) were identified in CR 2007-36761 (AR 405699). No cause or detailed failure analysis of the radiator tube failure was found.

• May and June 2001 - a 182 radiator failure (12-cylinder) was identified in St. Lucie Unit 1 Reportable Event 2001-006 (Reference 1). The cause of the failure was determined to be corrosion of the EOG radiator cooling fins from the humid salt-laden atmosphere which resulted in a loss of structural support of the radiator flat tubes. The loss of structural support, combined with the thermal and pressure cycles experienced by the radiator, allowed the flat tubes to swell and vibrate and ultimately caused the failure of the soldered mechanical tube. No detailed failure analysis of the radiator tube failure was found.

• November 2007 - a 1A1 radiator failure (16-cylinder) was identified in CR 2007-36761 (AR 405699). The cause of the radiator leak was attributed to a corrosion-induced failure. Environmental conditions were determined to be a contributing cause of the failure. From inspection, it appears the coating on the tubes were failing in areas around the highest air velocity passing through the radiator. It was suspected that particulates and air flow are damaging the coating. No detailed failure analysis was found.

The Turkey Point (PTN) Unit 3 EOG design includes an air cooled heat exchanger (truck-style radiator) similar in design to the PSL Unit 1 radiators. However, each PTN Unit 3 EOG cooling water system includes a single engine radiator as opposed to a total of two engine radiators (one radiator for the 16-cylinder engine and one for the 12-cylinder engine) for the larger PSL Unit 1 EDGs. A similar radiator leak occurred in 2008 at PTN Unit 3 and can be summarized as follows:

• April 2008 - a 3A engine radiator failure was identified in CR 2008-11134 (AR 405885),

The cause of the radiator leak was documented 'as a radiator core tube failure due to

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.23-1 L-2023-059 Attachment 1 Page 3 of 12 corrosion degradation from long-term exposure to moisture-laden air near a saltwater environment. No detailed failure analysis of the radiator tube failure was found.

The response to RAI 8.2.3.21-3 (Attachment 3 to this letter) provides a detailed evaluation of the July 2022 PSL Unit 1 182 EOG radiator tube failure. The evaluation includes the results of a detailed failure analysis which concludes that the July 2022 182 EOG tube failure was due to selective leaching. Specifically, the combination of damp conditions, elevated temperature during operation, and accumulation of corrosive deposits on the tube OD surface accelerated corrosion of the fan side fin and tubes. The copper fins were degraded by general corrosion.

The yellow brass tubes contained more than 15% zinc and were susceptible to selective leaching of the zinc, or dezincification. This process reduced the mechanical strength of the tube to the point where the remaining tube wall was unable to withstand the water pressure in the coolant system, resulting in the through wall crack.

This is the first documented failure of a PSL component located in an air-indoor uncontrolled or air-outdoor environment due to selective leaching. Further evaluation included in the response to RAI 8.2.3.21-3 concludes that the failure of the external surface of the 182 copper alloy with greater than 15 percent zinc radiator tubes exposed to air-indoor uncontrolled is a plant-specific aging effect unique to the PSL Unit 1 EOG radiators based upon the following:

• No other plant-specific OE regarding component failures due to selective leaching could be located,

• No failures of the PSL Unit 2 EOG Admiralty brass radiator tubes have occurred after approximately 39'years of service,

• The unique design of the PSL Unit 1 EOG radiators,

• The periodic rinsing of the PSL Unit 1 EOG radiators, and

• The severe environmental conditions the PSL Unit 1 EOG radiators are exposed to during EOG runs with radiator fans in operation.

As such, there is no need to adjust any aging management activities for other rooms or buildings containing structures and components within the scope of subsequent license renewal (SLR) as the more severe air-indoor uncontrolled environment is considered to be unique to the PSL Unit 1 EOG radiators. However, as discussed in the response to RAI 8.2.3.21-3 (Attachment 3 to this letter), ventilation flow rates through each PSL Unit 1 and 2 EOG room increases significantly due to EOG engine radiator fan operation. Therefore, structures and components within the scope of SLR that are located within the EOG rooms are exposed to increased amounts of humid salt-laden air during EOG operation. To address this unique environment, all metallic structures and components, including copper alloy and copper alloy with greater than 15 percent zinc components exposed to an air-indoor uncontrolled environment, may have aging effects requiring management during the SPEO. SLRA Table 3.2.2-4 is revised to include these changes and to add Plant Specific Note 2. Note that no changes are required for SLRA Table 3.5.2-6.

The response to RAI 8.2.3.23-2 (Attachment 2 to this letter) provides justification that since the Unit 1 EOG radiators are subject to replacement based on a specified time period, they are not

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 4 of 12 considered long-lived and are not subject to an aging management review in accordance with 10 CFR 54.21 (a)(1 )(ii). As such , the Unit 1 EOG radiators are deleted from SLRA Table 3.3.2-4 in the response to RAI B.2.3.23-2 (Attachment 2 to this letter).

Additionally, SLRA Table 3.0-1 is revised to clarify that some locations exposed to indoor uncontrolled air may also be exposed to humid salt-laden air in locations that have high velocity air flow rates in buildings that draw in outdoor air.

References:

1. FPL letter L-2001-169, St. Lucie Unit 1 Reportable Event 2001-006-00, Degraded EOG Radiator Lead to Operation of Facility Prohibited by Technical Specifications, dated July 19, 2001 (ADAMS Accession No. ML012050195)

Associated SLRA Revisions:

SLRA Table 3.0-1, page 3-5 is revised as follows:

Table 3.0-1 Mechanical System Service Environments Corresponding Environment Description NUREG-2191 Environments Air that has been treated to reduce its dew point well below the system operating temperature and treated to control Air- dry Air- dry lubricant content, particulate matter, and other corrosive contaminants.

An environment where the specified internal or external Air- indoor Air- indoor surface of the component or structure is exposed to a controlled controlled humidity-controlled (i.e., air conditioned) environment.-

This environment is for indoor locations that are sheltered/protected from weather. Surfaces of components in this environment may be wetted , but only rarely; equipment Air- indoor Air- indoor surfaces are normally dry. This environment may also uncontrolled uncontrolled include humid 1 salt-laden air in locations that have high velocity air flow rates in buildings that draw in outdoor air.

The outdoor environment consists of atmospheric air, Air - outdoor salt-laden air, ambient temperature and humidity, and Air - outdoor exposure to precipitation .

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 5 of 12 SLRA Table 3.3.2-4, page 3.3-119 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Svstems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manac:iement Piping Pressure Carbon steel Treated water Loss of material Closed Treated Vll.H2.AP-202 3.3-1 , 045 A boundary (int) Water Systems (8 .2.3.12)

Piping Pressure Carbon steel Underground Loss of material Buried and Vll.l.AP-284 3.3-1 , 109 A boundary (ext) Underground Piping and Tanks (B.2.3.27)

Piping Pressure Copper alloy Air - dry (int) Loss of material Compressed Air Vll.D.A-764 3.3-1, 235 A boundary Monitorinq (B.2.3.14)

Piping

• Pressure Copper alloy Air- indoor NGRe-Loss of NBAe External Vll.d.AF! ~ 44 d.d ~. ~~4 AH,2 boundary uncontrolled (ext) material Surfaces Monitoring of Mechanical Com~onents (8.2.3.23\

Piping Pressure Copper alloy Fuel oil (int) Loss of material Fuel Oil Chemistry Vll.H1.AP-132 3.3-1, 069 B boundary (B.2.3.18) A One-Time Inspection (8.2.3.20)

Piping Pressure Copper alloy Treated water Loss of material Closed Treated Vll.H2.AP-199 3.3-1, 046 A boundary (int) Water Systems (B.2.3.12)

Piping Pressure Stainless steel Air - dry (int) Loss of material Compressed Air Vll.D.A-764 3.3-1 , 235 A boundary Monitorinq (B.2.3.14)

Piping Pressure Stainless steel Air- indoor Cracking External Surfaces Vll.H1 .AP-209b 3.3-1, 004 A boundary uncontrolled (ext) Monitoring of Mechanical Components rn.2.3.23)

Piping Pressure Stainless steel Air- indoor Loss of material External Surfaces Vll.H1 .AP-221 b 3.3-1, 006 A boundary uncontrolled (ext) Monitoring of Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 6 of 12 Table 3.3.2-4: Diesel Generators and Support Systems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Piping Pressure Stainless steel Air- indoor Cracking Inspection of Internal Vll.D.AP-209b 3.3-1, 004 A boundary uncontrolled (int) Surfaces in Miscellaneous Piping and Ducting Components (8.2.3.24)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 7of12 SLRA Table 3.3.2-4, page 3.3-132 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Valve body Pressure Carbon steel Air- indoor Loss of material Inspection of Internal V.A.E-29 3.2-1, 044 A boundary uncontrolled (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Valve body Pressure Carbon steel Air - outdoor Loss of material External Surfaces Vll.l.A-77 3.3-1, 078 A boundary (ext) Monitoring of Mechanical Components (B.2.3.23)

Valve body Pressure Carbon steel Fuel oil (int) Loss of material Fuel Oil Chemistry Vll.H1.AP-105 3.3-1 , 070 B boundary (B.2.3.18) A One-Time Inspection (B.2.3.20)

Valve body Pressure Carbon steel Lubricating oil Loss of material Lubricating Oil Vll.H2.AP-127 3.3-1 , 097 A boundary (int) Analysis (B.2.3.25)

One-Time Inspection (B.2.3.20)

Valve body Pressure Carbon steel Treated water Loss of material Closed Treated Vll.H2.AP-202 3.3-1 , 045 A boundary (int) Water Systems (B.2.3.12)

Valve body Pressure Copper alloy Air - dry (int) Loss of material Compressed Air Vll.D.A-764 3.3-1 , 235 A boundary Monitorinq (B.2.3.14)

Valve body Pressure Copper alloy Air- indoor NGRe Loss of NGRe External VII.cl .AP ~44 d.d ~ . ~~4 AH,2 boundary uncontrolled (ext) material Surfaces Monitoring of Mechanical Com~onents (8.2.3.23)

Valve body Pressure Copper alloy Fuel oil (int) Loss of material Fuel Oil Chemistry Vll.H1.AP-132 3.3-1, 069 B boundary (B.2.3.18) A One-Time Inspection (B.2.3.20)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 8of12 Table 3.3.2-4: Diesel Generators and Support Svstems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Valve body Pressure Copper alloy Lubricating oil Loss of material Lubricating Oil Vll.H2.AP-133 3.3-1 , 099 A boundary (int) Analysis (B.2.3.25)

One-Time Inspection (B.2.3.20)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 9 of 12 SLRA Table 3.3.2-4, page 3.3-133 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Svstems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Valve body Pressure Copper alloy > Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1 , 106 A boundary 15%Zn uncontrolled (ext) Monitoring of Mechanical Components (B.2.3.23)

Valve body Pressure boundarv Copper alloy

> 15% Zn Air- indoor uncontrolled Loss of material External Surfaces Monitoring of

-- -- H,2 (ext) Mechanical Components lB.2.3.23\

Valve body Pressure Copper alloy > Air- indoor NGRe-Loss of NGRe-lnspection of Vll.d .AJ:! ~44 d.d ~ . ~~4 AH,2 boundary 15%Zn uncontrolled (int) material Internal Surfaces in Miscellaneous Piping and Ducting Components lB.2.3.24\

Valve body Pressure boundarv Copper alloy

> 15% Zn Air- indoor uncontrolled Cracking Inspection of Internal Surfaces in

-- -- H,2 (int) Miscellaneous Piping and Ducting Components fB.2.3.24\

Valve body Pressure Copper alloy > Treated water Cracking Closed Treated Vll.C2.A-473a 3.3-1, 160 c boundary 15% Zn (int) Water Systems

<B.2.3.12)

Valve body Pressure Copper alloy > Treated water Loss of material Closed Treated Vll.F1.AP-199 3.3-1 , 046 A boundary 15% Zn (int) Water Systems (8.2.3.12)

Valve body Pressure Copper alloy > Treated water Loss of material Selective Leaching Vll.H2.AP-43 3.3-1, 072 c boundary 15% Zn (int) <B.2.3.21 )

Valve body Pressure Stainless steel Air - dry (int) Loss of material Compressed Air Vll.D.A-764 3.3-1, 235 A boundary Monitorina <B.2.3.14)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 1O of 12 Table 3.3.2-4: Diesel Generators and Support Svstems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Valve body Pressure Stainless steel Air- indoor Cracking External Surfaces Vll .H1 .AP-209b 3.3-1 , 004 A boundary uncontrolled (ext) Monitoring of Mechanical Components (B.2.3.23)

Valve body Pressure Stainless steel Air- indoor Loss of material External Surfaces VII . H 1.AP-221 b 3.3-1 , 006 A boundary uncontrolled (ext) Monitoring of Mechanical Components

<B.2.3.23)

Valve body Pressure Stainless steel Air- indoor Cracking Inspection of Internal Vll.H1 .AP-209c 3.3-1, 004 A boundary uncontrolled (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 11 of 12 SLRA Table 3.3.2-4, page 3.3-134 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Svstems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Valve body Pressure Stainless steel Air- indoor Loss of material Inspection of Internal Vll.H1 .AP-221c 3.3-1 , 006 A boundary uncontrolled (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Valve body Pressure Stainless steel Fuel oil (int) Loss of material Fuel Oil Chemistry Vll.H1.AP-136 3.3-1, 071 B boundary (B.2.3.18) A One-Time Inspection

<B.2.3.20)

Valve body Pressure Stainless steel Lubricating oil Loss of material Lubricating Oil Vll.H2.AP-138 3.3-1, 100 A boundary (int) Analysis (B.2.3.25)

One-Time Inspection

<B.2.3.20)

General Notes A. Consistent with component, material , environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

B. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP has exceptions to NUREG-2191 AMP description.

C. Component is different, but consistent with material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

Plant Specific Notes

1. Plant experience shows a history of loss of material and fouling due to corrosion on fins.

2. Based on plant-specific operating experience, all metallic structures and components located in the PSL Uni 1 and 2 EOG rooms, including copper alloy and copper alloy with greater than 15 percent zinc components exposed to an air-indoor uncontrolled environment, may have aging effects requiring management during the SPEO.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-1 L-2023-059 Attachment 1 Page 12 of 12 Associated

Enclosures:

None.

St. Lucie Nuclear Plant Units 1 and 2 L-2023-059 Dockets 50-335 and 50-389 Attachment 2 Response to RAI B.2.3.23-2 Selective Leaching Environment (15 pages follow)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 1 of 15 External Surfaces & Selective Leaching RAI 8.2.3.23-2 Regulatory Basis:

Section 54.21 (a)(3) of Title 10 of the Code of Federal Regulations (10 CFR) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the U.S.

Nuclear Regulatory Commission (NRC) staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. In order to complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background:

SLRA Section B.2.3.23 includes enhancements to the external surfaces monitoring of mechanical components program to conduct periodic visual inspections or surface examinations on components made from various materials, including copper alloy with greater than 15 percent zinc. SLRA Table 3.3.2-4, "Diesel Generators and Support Systems - Summary of Aging Management Evaluation," credits the above program for managing cracking due to the external air environment of the emergency diesel generator (EOG) radiator tubes.

As part of the operating experience information associated with the recent EDG radiator leak at St. Lucie, NRC regional inspectors provided an lmperia Engineering Partners report, "Failure Analysis of 1B2 EOG Radiator," Revision 0, July 2022. Section 4.4 of the report notes that neither visual nor mechanical detection methods are useful in detecting the selective leaching observed in the radiator tubes due to inaccessibility. The report also notes that there was no report of seepage or slow leakage prior to the rapid leak of the radiator tube and that the tube ultimately failed by cracking due to overload.

Although the lmperia report's statement about inaccessibility only addressed the detection of selective leaching, the NRC staff believes it is comparably applicable to the detection of cracking of the EDG radiator tubes that are addressed in SLRA Table 3.3.2-4. Based on the apparent inaccessibility to the tube surface, it is also not clear how 20 percent of the radiator tube surface area can be either visually inspected or surface examined for cracking, as provided in an enhancement to the associated aging management program.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRG RAI No. 8.2.3.23-2 L-2023-059 Attachment 2 Page 2 of 15 Request:

Provide information regarding the ability to detect cracking of the EOG radiator tubes given the inaccessibility of the tube surfaces, using currently proposed enhancements to the external surfaces monitoring of mechanical components for surface examinations or ASME Code Section XI VT-1 inspections. In addition, for the EOG radiator tubes, provide the bases for conducting aging management activities to detect cracking on a 10-year frequency, given that the recent tube leaks occurred with less than 10 years of operation.

PSL Response:

As described in St. Lucie Unit 1 Licensee Event Report (LER) 2001-006 (Reference 1), on May 22, 2001 and June 11, 2001 during the performance of the monthly Technical Specification (TS) surveillance runs for the 18 EOG, FPL discovered that the 182 EOG had a radiator leak.

Corrosion of the EOG radiator cooling fins resulted in a loss of structural support of the radiator flat tubes that ultimately caused the failure of the soldered tube seam. Corrective actions in 2001 included replacement of the 182 EOG radiator and revision to the preventive maintenance program and procedures to provide cleaning and replacement of the Unit 1 EOG four (4) radiators ( 1A1, 1A2, 181, and 182) based on a specified time period.

10 CFR 54.21 states, in part, that each license renewal application must contain the following information:

(a) An integrated plant assessment (IPA). The IPA must--

1. For those systems, structures, and components within the scope of this part, as delineated in § 54.4, identify and list those structures and components subject to an aging management review. Structures and components subject to an aging management review shall encompass those structures and components--

(i) That perform an intended function, as described in § 54.4, without moving parts or without a change in configuration or properties; and (ii) That are not subject to replacement based on a qualified life or specified time period.

Section 2.1.3.2.2 of NUREG-2192 (Reference 2) provides additional guidance on this topic and states that:

"The applicant's methodology is reviewed to ensure that "long-lived" SCs are identified as those that are not subject to periodic replacement based on a qualified life or specified time period. Passive SCs that are not replaced on the basis of a qualified life or specified time period require an AMR.

Replacement programs may be based on vendor recommendations, plant experience, or any means that establishes a specific replacement frequency under a controlled program."

This section of NUREG-2192 goes on to state that structures and components that are replaced on the basis of performance or condition are not generically excluded from an aging management review (AMR). Rather, performance or condition monitoring may be evaluated later in the IPA as programs to ensure functionality during the subsequent period of extended

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.23-2 L-2023-059 Attachment 2 Page 3 of 15 operation. On this topic, Section f(i)(b) of the Statement of Considerations (SOC) accompanying 10 CFR 54 [60 FR 22478] (Reference 3) provides the following guidance:

"It is important to note, however, that the Commission has decided not to generically exclude passive structures and components that are replaced based on performance or condition from an aging management review. Absent the specific nature of the performance or condition replacement criteria and the fact that the Commission has determined that the components with "passive" functions are not as readily monitorable as components with active functions, such generic exclusion is not appropriate. However, the Commission does not intend to preclude a license renewal applicant from providing site-specific justification in a license renewal application that a replacement program on the basis of performance or condition for a passive structure or component provides reasonable assurance that the intended function of the passive structure or component will be maintained in the period of extended operation."

The controlled performance and condition monitoring program activities implemented for the PSL 1 EOG radiators includes the following:

• During PSL Unit 1 EOG monthly surveillance runs, each engine radiator is monitored for cooling water leaks and engine cooling water temperatures are recorded to ensure radiator pressure boundary and heat transfer functions are maintained.

• Additional PSL Unit 1 EOG radiator cleaning and inspection preventive maintenance activities are performed every 6 months.

• During PSL Unit 1 EOG 36 month preventive maintenance, each radiator is inspected for leaks and the radiator fins are inspected for corrosion, delamination of fin coatings, and particulate fouling. Quantitative functional criteria is specified and recorded for the radiator fins to confirm adequate heat transfer surface area.

• The current PSL Unit 1 EOG radiator replacement interval is every 6 years and is performed during every other EOG 36 month preventive maintenance activity discussed above. This replacement interval is based PSL Unit 1 EOG site-specific OE and radiator performance and condition monitoring activities.

Therefore, based on the FPL evaluation included in LER 2001-006 and the above controlled performance and condition monitoring program activities, the Unit 1 EOG radiators are subject to replacement based on a specified time period, are not considered long-lived, and are not subject to an aging management review in accordance with 10 CFR 54.21(a)(1)(ii). Accordingly, the Unit 1 EOG radiators are now deleted from SLRA Table 3.3.2-4 and the External Surfaces Monitoring of Mechanical Components AMP is no longer credited for managing the aging effects of the Unit 1 EOG radiators. New commitment 52 is added to SLRA Appendix A 1, Table 19-3, to continue replacement of the PSL Unit 1 EOG radiators on a frequency of 6-years (not to exceed 6.5 years) during the SPEO. The commitment includes provisions to modify the PSL Unit 1 EOG radiator 6-year replacement frequency (not to exceed 6.5 years) during the SPEO based on additional site-specific and industry operating experience (OE) or implementation of design changes that increase the PSL Unit 1 EOG radiator life.

Note that the Unit 2 EOG radiator design is significantly different than Unit 1. The Unit 1 EOG radiators are a "truck-style", copper fin and brass tube radiator (Unit 1 UFSAR Table 9.5-3)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 4 of 15 while the Unit 2 EOG design incorporates an air-cooled heat exchanger constructed of heavy-wall round Admiralty brass tubes with aluminum fins that are designed in accordance with the ASME Section VIII Code (Unit 2 UFSAR Table 9.5-3). The Unit 2 EOG radiators are designed for the life of the plant and have not been replaced. Therefore, the Unit 2 EOG radiators are considered long-lived and are subject to an aging management review in accordance with 10 CFR 54.21(a)(1)(ii). SLRA Table 3.3.2-4 originally credited the External Surfaces Monitoring of Mechanical Components AMP for managing cracking of the Unit 2 EOG radiator Admiralty brass tubes exposed to an air-indoor uncontrolled environment. However, based on a review of the Admiralty brass tube and aluminum fin design, visual examinations for loss of material and cracking in accordance with the requirements of the External Surfaces Monitoring of Mechanical Components AMP do not appear to be feasible. An alternate examination approach will be utilized to manage loss of material and cracking of the Admiralty brass tubes exposed to an air-indoor uncontrolled environment requiring volumetric examination of the tubes in accordance with the PSL One-Time Inspection AMP. Note that the External Surfaces Monitoring of Mechanical Components AMP will continue to manage the reduction of heat transfer due to fouling aging effect for the Admiralty brass tubes.

SLRA Tables 2.3.3-4 and 3.3.2-4 and SLRA Appendix A1, Section 19.4, Table 19-3, page A1-110, Appendix A2, Section 19.2.2.21, page A2-27, SLRA Appendix A2, Section 19.4, Table 19-3, page A2-89, and SLRA Section B.2.3.20, page B-173 have been revised below to incorporate these changes.

References:

1. FPL letter L-2001-169, St. Lucie Unit 1 Reportable Event 2001-006-00, Degraded EOG Radiator Lead to Operation of Facility Prohibited by Technical Specifications, dated July 19, 2001 (ADAMS Accession No. ML012050195)

2. NUREG-2192, "Standard Review Plan for Review of Subsequent License Renewal Applications for Nuclear Power Plants," United States Nuclear Regulatory Commission, July 2017 (ADAMS Accession No. ML16274A402)

3. Federal Register I Vol. 60, No. 88 I Monday, May 8, 1995 I Rules and Regulations I Page 22478

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 5 of 15 Associated SLRA Revisions:

SLRA Table 2.3.3-4, page 2.3-37 is revised as follows :

Table 2.3.3-4 Diesel Generators and Support System Components Subject to Aging Management Review Component Type Component Intended Function(s)

Air motor Pressure boundary Air motor lubricator Pressure boundary Bolting Mechanical closure Expansion joint Pressure boundary Flame arrestor Flame suppression Filter (Unit 2 only) Filter Flexible hose Pressure boundary Heat exchanger (lube oil) Heat transfer Pressure boundary Heat exchanger (Unit 2 radiator)1 Heat transfer Pressure boundary Orifice Pressure boundary Throttle Piping Pressure boundary Piping and piping components Pressure boundary Structural inteqrity (attached)

Pump casing (cooling water) Pressure boundary Pump casing (engine-driven fuel) Pressure boundary Pump casing (fuel oil transfer) Pressure boundary Pump casinq (lube oil) Pressure boundary Pump casing (priming) Pressure boundary Sight glass Pressure boundary Silencer Pressure boundary Strainer Filter Pressure boundary Tank (air start) Pressure boundary Tank (day) Pressure boundary Tank (diesel oil storage) Pressure boundary Tank (expansion) Pressure boundary Therm owe II Pressure boundary Valve body Pressure boundary

1. The Unit 1 EOG heat exchangers (radiators) are subject to replacement based on a specified time period. This replacement interval is based on a controlled radiator performance and condition monitoring program, which provides reasonable assurance that the intended function of the radiators will be maintained in the subsequent period of extended operation. As described in SLRA Section 2.1.5, 10

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 6 of 15 CFR 54.21(a)(1)(ii) states that structures and components subject to an aging management review shall encompass those structures and components that are not subject to periodic replacement based on a qualified life or specified time period. Therefore, the Unit 1 EOG heat exchangers (radiators) are not considered long-lived and are not subject to an aging management review.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 7 of 15 SLRA Table 3.3.2-4, pages 3.3-114 and 3.3-115 are revised as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaqement Heat exchanger Pressure Copper alloy > Treated water Loss of material Closed Treated Vll.H2.AP-199 3.3-1 , 046 c (lube oil tubes) boundary 15% Zn (int) Water Systems (B.2.3.1 2)

Heat exchanger Pressure Copper alloy > Treated water Loss of material Selective Leaching Vll.H2.AP-43 3.3-1, 072 c (lube oil tubes) boundary 15% Zn (int) (B.2.3.21 )

Heat exchanger Pressure Copper alloy > Lubricating oil Loss of material Lubricating Oil VII. H2.AP-133 3.3-1, 099 c (lube oil tubesheet) boundary 15% Zn (int) Analysis (B.2.3.25)

One-Time Inspection (B.2.3.20)

Heat exchanger Pressure Copper alloy > Treated water Cracking Closed Treated VI I. C2.A-4 73a 3.3-1, 160 c (lube oil tubesheet) boundary 15% Zn (int) Water Systems (B.2.3.12)

Heat exchanger Pressure Copper alloy > Treated water Loss of material Closed Treated Vll.H2.AP-199 3.3-1, 046 c (lube oil tubesheet) boundary 15% Zn (int) Water Systems (8.2.3.12)

Heat exchanger Pressure Copper alloy > Treated water Loss of material Selective Leaching Vll .H2.AP-43 3.3-1, 072 c (lube oil tubesheet) boundary 15%Zn (int) (B.2.3.21 )

Heat exchanger Pressure Carbon steel Air- indoor Loss of material External Surfaces Vll.l.AP-41 3.3-1 , 080 A (Unit 2 radiator boundary uncontrolled (ext) Monitoring of headers) Mechanical Components (B.2.3.23)

Heat exchanger Pressure Carbon steel Treated water Loss of material Closed Treated Vll .H2.AP-202 3.3-1 , 045 c (Unit 2 radiator boundary (int) Water Systems headers) (B.2.3.1 2)

Heat exchanger Heat transfer Copper alloy > Air- indoor Reduction of heat External Surfaces Vll.l.A-716 3.3-1 , 151 A (Unit 2 radiator 15% Zn uncontrolled (ext) transfer Monitoring of tubes) Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 8 of 15 Table 3.3.2-4: Diesel Generators and Support Systems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaqement Heat exchanger Heat transfer Copper alloy > Treated water Reduction of heat Closed Treated Vll.C2.AP-205 3.3-1, 050 A (Unit 2 radiator 15% Zn (int) transfer Water Systems tubes) (8 .2.3.12)

Heat exchanger Pressure Copper alloy > Air- indoor Cracking e*teFAal ;1::1Ffases Vlll.H.S-454 3.4-1, 106 GE,3 (Unit 2 radiator boundary 15%Zn uncontrolled (ext) Monitoring of tubes) Mesl=lanisal Components

~ B . ~ . a . ~a ~ One-Time Inspection lB.2.3.20)

Heat exchanger (Unit 2 radiator Pressure boundarv Copper alloy

> 15% Zn Air- indoor uncontrolled Loss of material One-Time Inspection

-- -- H,3 tubes\ (ext\ lB.2.3.20l Heat exchanger Pressure Copper alloy > Treated water Cracking Closed Treated Vll.C2.A-473a 3.3-1 , 160 c (Unit 2 radiator boundary 15% Zn (int) Water Systems tubes) (8.2.3.12)

Heat exchanger Pressure Copper alloy > Treated water Loss of material Closed Treated Vll.H2.AP-199 3.3-1, 046 c (Unit 2 radiator boundary 15% Zn (int) Water Systems tubes) (8.2.3.12)

Heat exchanger Pressure Copper alloy > Treated water Loss of material Selective Leaching Vll .H2.AP-43 3.3-1 , 072 c (Unit 2 radiator boundary 15% Zn (int) (8.2.3.21 )

tubes)

Heat exchanger Pressure Gray cast iron Air- indoor Loss of material External Surfaces Vll.l.AP-41 3.3-1, 080 A (Unit 1 lube oil boundary uncontrolled (ext) Monitoring of channel header) Mechanical Components (8.2.3.23)

Heat exchanger Pressure Gray cast iron Treated water Loss of material Closed Treated Vll.H2.AP-202 3.3-1, 045 c (Unit 1 lube oil boundary (int) Water Systems channel header) rn.2.3.12)

Heat exchanger Pressure Gray cast iron Treated water Loss of material Selective Leaching Vll.F4.AP-31 3.3-1 , 072 c (Unit 1 lube oil boundary (int) (8.2.3.21 )

channel header)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 9 of 15 Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type I Intended Material I Environment I Aging Effect I Aging Management I NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Heat exchan9er Hoeit trnnsfor Copper alloy l\ir insoor Loss of meitorieil External Surfaces Vlll.H.S 420 3.4 1, 075 G;-4 (Unit 1 radiator fins) uncontrolled (ext) Monitoring of Moohanioeil Components (8 .2.3.23)

Heat exchan9er Heat transfer Copper alloy Air indoor I Reduction of heat External Surfaces V.E.E 424 3.2 1, 081 G (Unit 1 radiator fins) uncontrolled (ext) I transfer Monitoring of Mocheiniceil Components (B.2.3.23)

SLRA Table 3.3.2-4, page 3.3-116 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item ManaQement Heat exchanger Heat transfer Aluminum Air- indoor Loss of material External Surfaces Vll.F4.A-771b 3.3-1 , 242 A;-4 (Unit 2 radiator fins) uncontrolled (ext) Monitoring of Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 10 of 15 SLRA Table 3.3.2-4, page 3.3-134 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Valve body Pressure Stainless steel Air- indoor Loss of material Inspection of Internal Vll.H1 .AP-221c 3.3-1 , 006 A boundary uncontrolled (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Valve body Pressure Stainless steel Fuel oil (int) Loss of material Fuel Oil Chemistry Vll.H1.AP-136 3.3-1 , 071 B boundary (B.2.3.18) A One-Time Inspection (B.2.3.20)

Valve body Pressure Stainless steel Lubricating oil Loss of material Lubricating Oil Vll.H2.AP-138 3.3-1, 100 A boundary (int) Analysis (B.2.3.25)

One-Time Inspection (B.2.3.20)

General Notes A. Consistent with component, material , environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

B. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP has exceptions to NUREG-2191 AMP description.

C. Component is different, but consistent with material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

E. Consistent with NUREG-2191 material, environment, and aging effect but a different AMP is credited or NUREG-2191 identifies a plant-specific AMP.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 11 of 15 Plant Specific Notes

1. Plant experience shows a history of loss of material and fouling due to corrosion on fins. Deleted

2. Added per RAI B.2.3.23-1 (Refer to Attachment 1 to this letter)

3. Volumetric examinations consistent with Table Xl.M32-1 of NUREG-2191 Xl.M32 One-Time Inspection program will be utilized to examine PSL Unit 2 EOG heat exchanger (radiator tubes) for the loss of material and cracking aging effects.

SLRA Appendix A 1, Section 19.4, Table 19-3, page A 1-110, adds new commitment 52 as follows:

Table 19-3 List of Unit 1 SLR Commitments and Implementation Schedule No. Aging Management NUREG-2191 Commitment Implementation Schedule Program or Activity Section (Section) 52 NIA NIA Continue replacement of the PSL Unit 1 EOG radiators on a No later than 6 months prior freguenc~ of 6-~ears {not to exceed 6.5 ~ears} during the SPEO. to the SPE0 1 or no later than The PSL Unit 1 EOG radiator 6-~ear replacement freguenc~ {not the last refueling outage prior to exceed 6.5 ~ears} can be modified during the SPEO based on to the SPEO i.e.:

additional site-specific and industrt operating experience {OE}

or implementation of design changes that increase the PSL Unit PSL 1: 0910112035 1 EOG radiator life.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 12 of 15 SLRA Appendix A2, Section 19.2.2.21 , page A2-27, is revised as follows :

The elements of the PSL One-Time Inspection AMP include: (a) determination of the sample size of components to be inspected based on an assessment of materials of fabrication, environment, plausible aging effects, and OE, (b) identification of the inspection locations in the system or component based on the potential for the aging effect to occur, (c) determination of the examination technique, including acceptance criteria that would be effective in managing the aging effect for which the component is examined, and (d) an evaluation of the need for follow-up examinations to monitor the progression of aging if age-related degradation is found that could jeopardize an intended function before the end of the SPEO.

The PSL One-Time Inspection AMP is used to verify the effectiveness of the PSL Water Chemistry, Fuel Oil Chemistry, and Lubricating Oil Analysis AMPs. For carbon steel components exposed to water environments that do not include corrosion inhibitors as a preventive action (e.g., raw water and waste water) or carbon steel components that do not have wall thickness measurement examinations conducted of a representative sample of each environment between the 50 1h and 601h year of operation, the program is used to verify that long-term loss of material due to general corrosion will not cause a loss of intended function [e.g., pressure boundary, leakage boundary (spatial) , and structural integrity]. In addition, volumetric examinations consistent with Table Xl.M32-1 of NUREG-2191 Xl.M32 One-Time Inspection program will be utilized to examine PSL Unit 2 EOG heat exchanger (radiator tubes) for the loss of material and cracking aging effects.

Periodic inspections are used instead of the PSL One-Time Inspection AMP for structures or components with known age-related degradation mechanisms or when the environment in the SPEO is not expected to be equivalent to that in the prior operating period. Inspections not conducted in accordance with ASME Code Section XI requirements are conducted in accordance with plant-specific procedures, including inspection parameters such as lighting, distance, offset, and surface conditions.

Selective Leaching The PSL Selective Leaching AMP is a new AMP that includes inspections of components that may be susceptible to loss of material due to selective leaching by demonstrating the absence of selective leaching (dealloying) of materials. The scope of this AMP includes components constructed of gray cast iron, ductile iron, and copper alloys (except for inhibited brass) containing greater than 15% Zn or greater than 8% Al in susceptible environments. One-time inspections for components exposed to a closed-cycle cooling water or treated water environment will be conducted, based on PSL plant-specific OE which has not revealed selective leaching in these environments. Opportunistic and periodic inspections will be conducted for selective leaching susceptible components exposed to raw water, waste water, soil , and groundwater environments. Opportunistic inspections will be performed whenever components are opened , or whenever buried or submerged surfaces are exposed . The periodic inspections are conducted at an interval of no greater than every 1O years during the SPEO.

Visual inspections coupled with mechanical examination techniques, such as chipping or scraping , will be conducted . Periodic destructive examinations of components for physical properties (i.e., degree of dealloying, depth of dealloying, through-wall thickness, and chemical composition) will be co*nducted for components exposed to raw water, waste water, soil , and

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 13 of 15 SLRA Appendix A2, Section 19.4, Table 19-3, page A2-89, is revised as fo!lows:

Table 19-3 List of Unit 2 SLR Commitments and Implementation Schedule No. Aging Management NUREG-2191 Commitment Implementation Schedule Program or Activity Section (Section) 23 One Time inspection Xl.M32 a) Implement the new PSL One-Time Inspection AMP. The new No later than 6 months prior to (19.2.2.20) AMP will include volumetric examinations consistent with the SPEO, or no later than the Table Xl.M32-1 of NUREG-2191 Xl.M32 One-Time lnsj;!ection last refueling outage prior to j;!rogram to examine the PSL Unit 2 EOG heat exchanger the SPEO i.e. :

{radiator tubes} for the loss of material and cracking aging effects. PSL2: 10/06/2042 Implement the AMP and start the one-time inspections no earlier than 1O years prior to the SPEO (04/06/2033).

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.23-2 L-2023-059 Attachment 2 Page 14of15 SLRA Section B.2.3.20, page B-173 is revised as follows:

appropriate standards, design basis information, or vendor-specified requirements and recommendations (e.g. , ultrasonic thickness measurements are compared to predetermined limits); however, crack-like indications are not acceptable. Where it is practical to project observed degradation to the end of the SPEO, the projected degradation will not: (a) affect the intended function of a system, structure, or component; (b) result in a potential leak; or (c) result in heat transfer rates below that required by the CLB to meet design limits. Where measurable degradation has occurred , but acceptance criteria have been met, the inspection results are entered into the corrective action program for future monitoring and trending .

The PSL One-Time Inspection AMP is used to verify the effectiveness of the PSL Water Chemistry (Section B.2.3.2), Fuel Oil Chemistry (Section B.2.3.18), and Lubricating Oil Analysis (Section B.2.3.25) AMPs . For steel components exposed to water environments that do not include corrosion inhibitors as a preventive action or steel components that do not have wall thickness measurement examinations conducted of a representative sample of each environment between the 50 1h and 601h year of operation, the PSL One-Time Inspection AMP will be used to verify that long-term loss of material due to general corrosion will not cause a loss of intended function [e.g., pressure boundary, leakage boundary (spatial) , and structural integrity]. For components susceptible to long-term loss of material due to general corrosion , wall thickness will be measured with a volumetric (UT) technique. The PSL One-Time Inspection AMP will also include volumetric examinations consistent with Table Xl.M32-1 of NUREG-2191 Xl.M32 One-Time Inspection program to examine the PSL Unit 2 EOG heat exchanger (radiator tubes) for the loss of material and cracking aging effects.

The PSL One-Time Inspection AMP will address potentially long incubation periods for certain aging effects and will provide a means of verifying that an aging effect is either not occurring or progressing so slowly as to have a negligible effect on the intended function of the structure or component. Situations in which additional confirmation is appropriate include: (a) an aging effect is not expected to occur, but the data are insufficient to rule it out with reasonable confidence; or (b) an aging effect is expected to progress very slowly in the specified environment, but the local environment may be more adverse than generally expected. For these cases, confirmation demonstrates that either the aging effect is not occurring or that the aging effect is occurring very slowly and does not affect the component or structure intended function during the SPEO based on prior OE data.

The components to be inspected shall be chosen from the various systems within the scope of the PSL Water Chemistry (Section B.2.3.2) AMP , the PSL Fuel Oil Chemistry AMP, and the PSL Lubricating Oil Analysis (Section B.2.3.25) AMP . From these lists of components, a sample of the population will be selected for inspection as part of the PSL One-Time Inspection AMP. The inspections will be scheduled as close to the end of the current operating license as practical with margin provided to ensure completion prior to commencing the SPEO. Any corrective actions will be implemented through the Corrective Action Program. The AMP may include a review of routine maintenance, repair, or inspection records to confirm that selected

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.23-2 L-2023-059 Attachment 2 Page 15 of 15 components have been inspected for aging degradation within the recommended time period for the inspections related to the SPEO, and that significant aging degradation has not occurred.

The PSL One-Time Inspection AMP does not address loss of material due to selective leaching.

Loss of material due to selective leaching is addressed in the PSL Selective Leaching (Section B.2.3.21 ) AMP. The PSL One-Time Inspection AMP also does not address Class 1 piping less than 4 inches nominal pipe size Associated

Enclosures:

None.

St. Lucie Nuclear Plant Units 1 and 2 L-2023-059 Dockets 50-335 and 50-389 Attachment 3 Response to RAI B.2.3.23-2 Selective Leaching Operating Experience (41 pages follow)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 1 of 41 External Surfaces & Selective Leaching RAI 8.2.3.21-3 Regulatory Basis:

Section 54.21 (a)(3) of Title 10 of the Code of Federal Regulations (1 O CFR) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the U.S.

Nuclear Regulatory Commission (NRC) staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. In order to complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background:

SLRA Table 3.3.2-4, "Diesel Generators and Support Systems - Summary of Aging Management Evaluation," states the external surfaces of copper alloy with greater than 15 percent zinc heat exchanger radiator tubes exposed to air-indoor uncontrolled will be managed for reduction of heat transfer and cracking using the external surfaces monitoring of mechanical components program. The staff notes that the external surfaces of the subject components are not being managed for loss of material due to selective leaching.

SLRA Section B.2.3.21, "Selective Leaching," states the following (in part):

"[t]he PSL Selective Leaching AMP [aging management program] includes inspections of components made of gray cast iron, ductile iron, and copper alloys (except for inhibited brass) that contain greater than 15% Zn or greater than 8% Aluminum exposed to a raw water, closed-cycle cooling water, treated water, waste water, soil, or groundwater environment."

The staff recently became aware of operating experience at St. Lucie for an emergency diesel generator (EOG) radiator leak that occurred in June 2022. The cause of the leak was dezincification on the external surfaces of yellow brass EDG radiator tubes, which are exposed to an air-indoor uncontrolled environment.

Based on its review of the SLRA, the staff noted loss of material due to selective leaching is being managed for components exposed to water or soil environments. However, based on the operating experience noted above, the staff seeks clarification with respect to why loss of material due to selective leaching is not being managed for copper alloy with greater than 15 percent zinc components exposed to air-indoor uncontrolled or more aggressive air

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 2 of 41 environments (i.e., air-outdoor and condensation). The staff's issue is not applicable to less aggressive air environments (i.e., air-indoor controlled and air-dry).

Request:

1. Provide any additional clarifying information with respect to the operating experience noted above and revise the SLRA (as appropriate).

2. State the basis for why loss of material due to selective leaching is not an aging effect requiring management for copper alloy with greater than 15 percent zinc components exposed to air-indoor uncontrolled, air-outdoor, or condensation environments.

Alternatively, revise the SLRA (as appropriate) to reflect that the subject components will be managed for loss of material due to selective leaching.

PSL Response:

The numbered responses below correspond to numbered requests in the RAI.

1. Additional information regarding the July 2022 failure of the 182 EOG radiator is provided below in the revision to the Plant Specific Operating Experience portion of SLRA Section B.2.3.21.

2. Based on a detailed review of the July 2022 failure of the 182 EOG radiator tubes, it is reasonable to conclude that the loss of material due to selective leaching is an aging effect unique to the external surfaces of the Unit 1 1A1, 1A2, 181, and 182 EOG radiators exposed to an air-indoor uncontrolled environment. The bases for this conclusion are as follows:

a) PSL Site-specific Operating Experience for Selective Leaching SLRA Section B.2.3.21 discusses plant-specific OE associated with the new Selective Leaching AMP and states an OE search from October 1, 2010 through October 1, 2020 did not identify any instances of component failure on either Unit 1 or 2 as a result of selective leaching. The recent July 2022 182 EOG radiator tube failure appears to be the first documented instance of a PSL component failure resulting from selective leaching.

b) Unit 1 and 2 EOG Radiator Design Differences There are significant differences between the Unit 1 and 2 EOG radiator designs.

The Unit 1 EOG radiators are a "truck-style", copper fin and brass tube radiator consisting of 4 cores bolted together which are bolted to upper and lower headers. Each core contains 5 rows of tubes; the outer row tubes are 0.012" thick, the inner row tubes are 0.008" thick, and the copper fins are 0.0035" thick.

The radiators are approximately 8 inches thick. The Unit 1 EOG radiator core surface area is more compact than the Unit 2 EOG radiators. This radiator design has very efficient thermal performance but plant-specific OE has shown these radiators to be susceptible to external corrosion.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.21-3 L-2023-059 Attachment 3 Page 3 of 41 The Unit 2 EOG radiators are an air-cooled heat exchanger using an extended fin surface to remove heat. The heat exchanger is constructed of 1 inch heavy-wall round Admiralty tubes with aluminum fins and each tube is pluggable. The heat exchangers are much larger than the Unit 1 EOG radiators The heat exchangers are designed in accordance with the ASME Section VIII Code (Unit 2 UFSAR Table 9.5-3). These heat exchangers are designed for the life of the plant and they have not experienced a tube failure in 39 years of operation.

c) Unit 1 EOG Radiator Periodic Rinsing Corrective actions implemented after the 2001 failure of the 182 EOG radiator tube included revisions to the preventive maintenance program and procedures to provide cleaning and time-based replacement of the Unit 1 EOG radiators.

Inspection ports were cut into the Unit 1 EOG radiator shrouds to facilitate visual inspection and PMs were developed to inspect and document radiator fin corrosion using detailed functional criteria. This PM was originally performed every 24 months and is now performed every 36 months during EOG critical maintenance activities.

Radiator cleaning and inspection PMs with a 6-month frequency were also implemented. Note that the PMs recommend washing the Unit 1 EOG radiators from the inside, or fan side of the radiator, to the outside of the EOG room if particulate fouling buildup was identified. A review of the Unit 2 EOG radiator PMs indicate that periodic rinsing of the Unit 2 EOG radiator tubes is not performed, so the radiator rinsing activity is unique to Unit 1.

Subsequent to the recent 2022 182 EOG radiator tube failure, the core section of the radiator containing the failed brass tube was sent off site for independent failure analysis. Results of the radiator tube failure analysis identified the failure mechanism to be a crack in the seamless tube material at a location weakened by low zinc content. The failure analysis report identified several key facts about the specific mechanism that caused the seamless tube to fail. The report states the following:

"During operation of the diesel generator, the 182 EOG radiator was subjected saltwater vapor rich air passing through the radiator from the fan side to the exhaust side. The air flow resulted in corrosive deposit accumulation on the fan side fins and tubes. PSL reported that regular maintenance included rinsing the radiator every 6-12 months using potable water. The rinsing action is suspected to have contributed to increased accumulation of corrosive deposits on the fan side of the radiator, particularly toward the bottom of the radiator as the water ran down the fan side of the radiator."

"Laboratory analysis of the failed tube crack tips revealed the zinc was leached from the brass material, leaving behind a porous, copper-rich structure with zinc content ranging from 6.55% to 15.75% as compared with the zinc content of 32.53% in the smooth (non-corroded) tube area. Zinc leaching was assisted by the corrosive deposit accumulations at the bottom half of the radiator. The leaching process removed zinc from the alloy and allowed the zinc to form a porous white zinc oxide deposit layer on the tube OD surfaces. The remaining porous copper-rich structure of the tube wall possessed reduced mechanical strength. As the corrosion process

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 4 of 41 continued, with resulting reduction of mechanical strength, the tube wall eventually became unable to withstand the water pressure in the coolant system and cracked."

The report concluded:

"The combination of damp conditions, elevated temperature during operation, and accumulation of corrosive deposits on the tube OD surface accelerated corrosion of the fan side fin and tubes. The copper fins were degraded by general corrosion. The yellow brass tubes contained more than 15% zinc and were susceptible to selective leaching of the zinc, or dezincification. This process reduced the mechanical strength of the tube to the point where the remaining tube wall was unable to withstand the water pressure in the coolant system, resulting in the through wall crack."

Unlike the Unit 1 EOG radiators, PSL copper alloy with greater than 15 percent zinc components within the scope of license renewal that are located indoors in Class 1 structures, including the Unit 2 EOG radiators, are not exposed to periodic wetting.

d) Unit 1 and 2 EOG Radiator Environmental Conditions Unit 1 and 2 Technical Specification surveillance testing requires each EOG to be started monthly on a staggered test basis and also started, loaded, and run for 24-hours every 18 months during refueling outages. Conservatively assuming a full day of EOG operation for each bi-monthly EOG test and 7 days of operation for each 24-hour outage test every 18 months equates to a total of 16 days of EOG operation during a typical 18-month (548 day) fuel cycle. Therefore, the EOG buildings are exposed to normal operating ventilation conditions for (548-16)/548, or greater than 97% of the time.

During this period of EOG standby operation, normal ventilation for the Unit 1 and 2 EOG buildings is provided by a single roof ventilator fan with capacity of 5000 cfm for Unit 1 (UFSAR Table 9.4-7) and 6600 cfm for Unit 2 (UFSAR Table 9.4-12). The roof ventilators pull outside air into the EOG buildings through the building outside air intakes and radiator exhaust openings.

During the approximate 3% EOG test condition, both the 16-cylinder and 12-cylinder engine radiator fans are in operation and ventilation flow rates through each EOG room increases significantly due to EOG engine radiator fan operation. EOG radiator fan flow rates for the 16-cylinder and 12-cylinder engines are provided in Table 9.5-3 of each of the Unit 1 and 2 UFSARs and are included in the table below. This EOG test radiator fan total ventilation flow rate (255,000 cfm for Unit 1 and 157 ,491 cfm for Unit 2) is significantly higher than the 5000 cfm and 6600 cfm normal ventilation flow rate through the Unit 1 and 2 EOG buildings, respectively.

During these test conditions, the fan side of the Unit 1 EOG 16-cylinder and 12-cylinder engine radiators are exposed to significantly higher air velocity than Unit 2 due to higher radiator fan flow rates and smaller radiator face surface area (between 24.2 and 28.2 feet per second for Unit 1 and between 6.3 and 6.4 feet per second for Unit 2). The combination of a more torturous flow path for radiator fan ventilation flow thorough the EOG radiators, significantly higher air velocity on the

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 5 of 41 EOG fan side radiator faces, and periodic wetting of the EOG radiators during PMs, provides a much greater potential for contaminants (salt) to accumulate on the fan side face of the Unit 1 EOG radiators. This is confirmed by photographs in the July 2022 failure analysis report that show significant accumulation of contaminants and corrosion located on the bottom of the fan side of 182 radiator where the EOG radiator tube failure occurred.

Radiator Core Size Radiator Radiator Fan Radiator Face EOG Engine (Width x Height) Core Area Air Flow Air Velocity Unit 1 1A1and181 16 cylinder 10ftx10ft 100 ft2 145,000 cfm 24.2 ft/sec 1A2 and 182 12 cylinder 10 ft x 6.5 ft 65 ft2 110,000 cfm 28.2 ft/sec Total radiator fan flow 255,000 cfm Unit2 2A1 and 281 16 cylinder 19 ft x 12.5 ft 237.5 ft2 90,000 cfm 6.3 ft/sec 2A2 and 282 12 cylinder 16ftx11 ft 176 ft2 67,491 cfm 6.4 ft/sec Total radiator fan flow 157,491 cfm Based on the information presented above, the PSL plant specific OE regarding selective leaching and the significant differences between the Unit 1 and 2 EOG radiator design, preventive maintenance procedures requiring periodic rinsing, and radiator environmental conditions, it is reasonable to conclude that the July 2022 failure of the 182 EOG radiator tube due to loss of material due to selective leaching is an aging effect unique to the external surfaces of the Unit 1 EOG radiators that are exposed to an air-indoor uncontrolled environment.

To confirm that loss of material due to selective leaching is an aging effect unique to the external surfaces of the Unit 1 EOG copper alloy with greater than 15 percent zinc radiator tubes, PSL will perform a one-time inspection of a representative sample of copper alloy with greater than 15 percent zinc components exposed to an air-outdoor environment. In addition, PSL will perform a one-time inspection of a representative sample of the PSL Unit 2 EOG Admiralty brass radiator tubes exposed to an air-indoor uncontrolled external environment . These inspections will be performed prior to the SPEO in accordance with the Selective Leaching AMP described in SLRA Section B.2.3.21 and will be considered two separate inspection populations.

SLRA Tables 3.3.2-4, 3.3.2-5, 3.3.2-7, 3.3.2-8, and 3.4.2-1, Appendices A 1 and A2 Section 19.2.2.21, Appendices A 1 and A2 Section 19.4 Table 19-3, and Section B.2.3.21 are revised to incorporate these changes.

Note that the revision to page 3.3-110 of SLRA Table 3.3.2-4 includes the changes made by Attachment 1 of Supplement 1 to SLRA Revision 1 (Reference 1). That

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 6 of 41 change added the new component type "Filter (Unit 2 only)" and two corresponding rows to Table 3.3.2-4. A subsequent review of the filter design indicates that, while it is a copper alloy > 15% Zn material, it is wire mesh screen and is therefore -is not exposed to an "Air - outdoor (int)" environment. Therefore, this revision to page 3.3-110 of SLRA Table 3.3.2-4 deletes this line item.

References:

1. FPL letter L-2022-043, Subsequent License Renewal Application Revision 1 -

Supplement 1, dated April 7, 2022 (ADAMS Accession No. ML22097A202)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 7 of 41 Associated SLRA Revisions:

SLRA Table 3.3.2-4, page 3.3-110 is revised to include the new row as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaqement Expansion joint Pressure Stainless steel Diesel exhaust Cracking Inspection of Internal Vll.H2.AP-128 3.3-1 , 083 A boundary (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Expansion joint Pressure Stainless steel Diesel exhaust Loss of material Inspection of Internal Vll.H2.AP-104 3.3-1 , 088 A boundary (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Filter (Unit 2 only) Filter Copper alloy

> 15% Zn Air - outdoor (ext)

Loss of material Selective Leaching (B.2.3.21)

-- -- H,5 Filter (Unit 2 only) Filter Copper alloy Air - outdoor Cracking External Surfaces Vlll.H .S-454 3.4-1, 106 A

> 15% Zn (ext) Monitoring of Mechanical Components (B.2.3.23) 11.*

Filter (Unit 2 only) ~ Gopper alloy nlr outdoor N&Re- N&Re- '!11.J.AP 144 3.3 1, 114 A

> 15% ~n AA#

Flame arrestor Fire Aluminum Air - outdoor Cracking External Surfaces Vll.H2.A-451 b 3.3-1 , 189 A prevention (ext) Monitoring of Mechanical Components (B.2.3.23)

Flame arrestor Fire Aluminum Air - outdoor Loss of material External Surfaces Vll.H2.A-763b 3.3-1 , 234 A prevention (ext) Monitoring of Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 8 of 41 Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Mana~ement Flame arrestor Fire Aluminum Air - outdoor (int) Cracking Inspection of Internal VI I. H2.A-451 c 3.3-1 , 004 A prevention Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Flame arrestor Fire Aluminum Air - outdoor (int) Loss of material Inspection of Internal Vll.H2.A-763c 3.3-1 , 234 A prevention Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 9 of 41 SLRA Table 3.3.2-4, page 3.3-115 is revised to include the new row as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summarv of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item ManaQement Heat exchanger

{Unit 2 radiator Pressure boundarv Copper alloy

> 15% Zn Air- indoor uncontrolled Loss of material Selective Leaching

{B.2.3.21)

-- -- H,4 tubes) text\

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 10 of 41 SLRA Table 3.3.2-4, page 3.3-134 is revised as follows:

Table 3.3.2-4: Diesel Generators and Support Systems - Summary of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Mana~ement Valve body Pressure Stainless steel Air- indoor Loss of material Inspection of Internal Vll.H1.AP-221c 3.3-1 , 006 A boundary uncontrolled (int) Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Valve body Pressure Stainless steel Fuel oil (int) Loss of material Fuel Oil Chemistry Vll .H1 .AP-136 3.3-1, 071 B boundary (B.2.3.18) A One-Time Inspection (B.2.3.20)

Valve body Pressure Stainless steel Lubricating oil Loss of material Lubricating Oil Vll.H2.AP-138 3.3-1 , 100 A boundary (int) Analysis (B.2.3.25)

One-Time Inspection (B.2.3.20)

General Notes A. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

B. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP has exceptions to NUREG-2191 AMP description.

C. Component is different, but consistent with material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

Plant Specific Notes

1. Deleted per RAI B.2.3.23-2 (Refer to Attachment 2 to this letter)

2. Added per RAI B.2.3.23-1 (Refer to Attachment 1 to this letter)

3. Added per RAI B.2.3.23-2 (Refer to Attachment 2 to this letter)

4. Based on plant-specific operating experience discussed in SLRA Section B.2.3.21, a one-time inspection of a representative sample of PSL Unit 2 EOG Admiralty brass radiator tubes using the elements of the Selective Leaching AMP will be performed to determine if this aging effect is present in the air-indoor uncontrolled (ext) environment.

5. Based on plant-specific operating experience discussed in SLRA Section B.2.3.21, a one-time inspection of a representative sample of

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 11 of 41 components using the elements of the Selective Leaching AMP will be performed to determine if this aging effect is present in the air-outdoor (ext) and air-outdoor (int) environments, as applicable.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 12 of 41 SLRA Table 3.3.2-5, page 3.3-141 is revised as follows:

Table 3.3.2-5: Fire Protection I Service Water - Summary of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Hose reel Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll .G.AP-197 3.3-1 , A boundary Flow blockage (B.2.3.16) 064 Hose reel Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1 .A-409 3.3-1, E, 1 boundary erosion (B.2.3.16) 126 Hose reel Pressure Copper alloy Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary > 15% Zn uncontrolled (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

Hose reel Pressure Copper alloy Air- indoor None None Vll .J.AP-144 3.3-1 , A boundary > 15% Zn uncontrolled (int) 114 Hose reel Pressure Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll .H.S-454 3.4-1, A boundary > 15% Zn Monitoring of 106 Mechanical Components (B.2.3.23)

Hose reel Pressure boundarv Copper alloy

> 15% Zn Air - outdoor text\

Loss of material Selective Leaching lB.2.3.21)

-- -- H, 6 Hose reel Pressure Copper alloy Air - outdoor (int) NGReLoss of NGReSelective Vll.J.AP 144 ~ AH,6 boundary > 15% Zn material Leaching

-- 444 (8.2.3.21) -

Nozzle Pressure Copper alloy Air- indoor None None Vll.J.AP-144 3.3-1 , A boundary uncontrolled (ext) 114 Nozzle Pressure Copper alloy Air- outdoor (ext) None None Vll.J.AP-144 3.3-1 , A boundary 114 Nozzle Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.A-403 3.3-1, A boundary Flow blockaqe (B.2.3.16) 130 Nozzle Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1.A-409 3.3-1 , E, 1 boundary erosion (B.2.3.16) 126 Nozzle Pressure Copper alloy Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary > 15% Zn uncontrolled (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 13 of 41 Table 3.3.2-5: Fire Protection I Service Water - Summarv of Agim Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Mana~ement Nozzle Pressure Copper alloy Air- indoor None None Vll.J.AP-144 3.3-1 , A boundary > 15% Zn uncontrolled (int) 114

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 14 of 41 SLRA Table 3.3.2-5, page 3.3-142 is revised as follows:

Table 3.3.2-5: Fire Protection I Service Water - Summary of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Mana~ement Nozzle Pressure Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll.H.S-454 3.4-1 , A boundary > 15% Zn Monitoring of 106 Mechanical Components (B.2.3.23)

Nozzle Pressure boundarv Copper alloy

> 15% Zn Air - outdoor text\

Loss of material Selective Leaching lB.2.3.21\

-- -- H,6 Nozzle Pressure Copper alloy Air - outdoor (int) Nef\eLoss of Nef\eSelective Vll.J.AP 144 ~ AH,6 boundary > 15% Zn material Leaching

-- 444 (B.2.3.21\ -

Nozzle Pressure Copper alloy Raw water (int) Cracking Fire Water System Vll.C1.A-473b 3.3-1 , E, 3 boundary > 15% Zn (B.2.3.16) 160 Nozzle Pressure Copper alloy Raw water (int) Loss of material Selective Leaching Vll.G.A-47 3.3-1 , A boundary > 15% Zn (B.2.3.21 ) 072 Nozzle Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.A-403 3.3-1 , A boundary > 15% Zn Flow blockage (B.2.3.16) 130 Nozzle Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System VI I. C 1.A-409 3.3-1 , E, 1 boundary > 15% Zn erosion (B.2.3.16) 126 Nozzle Spray Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.A-403 3.3-1 J A Flow blockage (B.2.3.16) 130 Nozzle Spray Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1 .A-409 3.3-1 J E, 1 erosion (B.2.3.16) 126 Nozzle Spray Copper alloy Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1 J A

> 15% Zn uncontrolled (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

Nozzle Spray Copper alloy Air- indoor Flow blockage Fire Water System Vll.G.A-404 3.3-1 , A

> 15% Zn uncontrolled (int) (B.2.3.16) 131 Nozzle Spray Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll.H .S-454 3.4-1 J A

> 15% Zn Monitoring of 106 Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 15 of 41 Table 3.3.2-5: Fire Protection I Service Water - Summary of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Nozzle Spray Copper alloy

> 15% Zn Air - outdoor text)

Loss of material Selective Leaching (8.2.3.21)

-- -- H,6 Nozzle Spray Copper alloy Air - outdoor (int) Flow blockage Fire Water System Vll.G.A-404 3.3-1 , A

> 15% Zn (B.2.3.16) 131 Nozzle ~ Copper alloy

> 15% Zn Air - outdoor (int) Loss of material Selective Leaching (8.2.3.21)

-- -- H, 6 Nozzle Spray Copper alloy Raw water (int) Cracking Fire Water System Vll.C1 .A-473b 3.3-1 , E, 3

> 15% Zn (B.2.3.16) 160

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 16 of 41 SLRA Table 3.3.2-5, page 3.3-147 is revised as follows:

Table 3.3.2-5: Fire Protection I Service Water - Summarv of Aain' Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Piping Pressure Copper alloy Air- indoor None None Vll.J.AP-144 3.3-1 , A boundary uncontrolled (ext) 114 Piping Pressure Copper alloy Air- outdoor (ext) None None Vll.J.AP-144 3.3-1, A boundary 114 Piping Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.AP-197 3.3-1 , A boundary Flow blockaqe (B.2.3.16) 064 Piping Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1 .A-409 3.3-1 , E, 1 boundary erosion (B.2.3.16) 126 Piping Pressure Copper alloy Air-indoor Cracking External Surfaces Vlll.H .S-454 3.4-1 , A boundary > 15% Zn uncontrolled (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

Piping Pressure Copper alloy Air- indoor None None Vll.J.AP-144 3.3-1 , A boundary > 15% Zn uncontrolled (int) 114 Piping Pressure Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll.H.S-454 3.4-1 , A boundary > 15% Zn Monitoring of 106 Mechanical Components (B.2.3.23)

Piping Pressure boundarv Copper alloy

> 15% Zn Air - outdoor text\

Loss of material Selective Leaching (8.2.3.21)

-- -- H,6 Piping Pressure Copper alloy Air - outdoor (int) NeAeLoss of NeAeSelective Vll.J.,A,P ~ 44 ~ AH,6 boundary > 15% Zn material Leaching

-- 444 lB.2.3.21\ -

Piping Pressure Ductile iron Air- outdoor (ext) Loss of material External Surfaces Vll.l.A-77 3.3-1 , A boundary Monitoring of 078 Mechanical Components (B.2.3.23)

Piping Pressure Ductile iron Concrete (ext) Loss of material Buried and Vll.l.AP-198 3.3-1 , AB boundary Underground Piping 109 and Tanks (B.2.3.27)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 17 of 41 Table 3.3.2-5: Fire Protection I Service Water - Summary of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Piping Pressure Ductile iron Raw water (int) Long-term loss One-Time Inspection Vll.G.A-532 3.3-1 , A boundary of material (B.2.3.20) 193 Piping Pressure Ductile iron Raw water (int) Loss of material Selective Leaching Vll.G.A-51 3.3-1, A boundary (B.2.3.21 ) 072 Piping Pressure Ductile iron Raw water (int) Loss of material Fire Water System Vll.G.A-33 3.3-1, A boundary Flow blockaqe (B.2.3.16) 064 Piping Pressure Ductile iron Raw water (int) Wall thinning - Fire Water System Vll.C1 .A-409 3.3-1 , E, 1 boundary erosion (B.2.3.16) 126

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 18 of 41 SLRA Table 3.3.2-5, page 3.3-156 is revised as follows:

Table 3.3.2-5: Fire Protection I Service Water - Summarv of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Strainer Filter Gray cast iron Raw water (int) Loss of material Fire Water System Vll.G.A-33 3.3-1 , A Flow blockaqe (B.2.3.16) 064 Strainer Filter Gray cast iron Raw water (int) Wall thinning - Fire Water System Vll .C1.A-409 3.3-1 , E, 1 erosion (B.2.3.16) 126 Strainer Filter Stainless steel Raw water (int) Loss of material Fire Water System Vll.G.A-55 3.3-1 , A Flow blockaqe (B.2.3.16) 066 Strainer Filter Stainless steel Raw water (int) Wall thinning - Fire Water System Vll.C1 .A-409 3.3-1 , E, 1 erosion (B.2.3.16) 126 Strainer Pressure Copper alloy Air- indoor None None Vll.J.AP-144 3.3-1 , A boundary uncontrolled (ext) 114 Strainer Pressure Copper alloy Air - outdoor (ext) None None Vll.J .AP-144 3.3-1 , A boundary 114 Strainer Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.AP-197 3.3-1 , A boundary Flow blockaae (8.2.3.16) 064 Strainer Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1.A-409 3.3-1, E, 1 boundary erosion (B.2.3.16) 126 Strainer Pressure Copper alloy Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1 , A boundary > 15% Zn uncontrolled (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

Strainer Pressure Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary > 15% Zn Monitoring of 106 Mechanical Components (B.2.3.23)

Strainer Pressure boundarv Copper alloy

> 15% Zn Air - outdoor lext\

Loss of material Selective Leaching (8.2.3.21\

-- -- H, 6 Strainer Pressure Copper alloy Raw water (int) Cracking Fire Water System Vll.C1.A-473b 3.3-1 , E, 3 boundary > 15% Zn (B.2.3.16) 160 Strainer Pressure Copper alloy Raw water (int) Loss of material Selective Leaching Vll.G.A-47 3.3-1 , A boundary > 15% Zn (B.2.3.21 ) 072 Strainer Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.AP-197 3.3-1, A boundary > 15% Zn Flow blockage (B.2.3.16) 064

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 19 of 41 Table 3.3.2-5: Fire Protection I Service Water - Summary of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Strainer Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1.A-409 3.3-1 , E, 1 boundary > 15% Zn erosion (B.2.3.16) 126

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 20 of 41 SLRA Table 3.3.2-5, page 3.3-161 is revised as follows:

Table 3.3.2-5: Fire Protection I Service Water - Summary of Agin~ Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Mana~ement Valve body Pressure Copper alloy Raw water (int) Loss of material Fire Water System Vll.G.AP-197 3.3-1 , A boundary Flow blockage (B.2.3.16) 064 Valve body Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll.C1 .A-409 3.3-1, E, 1 boundary erosion (B.2.3.16) 126 Valve body Pressure Copper alloy Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1 , A boundary > 15% Zn uncontrolled (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

Valve body Pressure Copper alloy Air- indoor None None Vll.J.AP-144 3.3-1, A boundary > 15% Zn uncontrolled (int) 114 Valve body Pressure Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary > 15% Zn Monitoring of 106 Mechanical Components (B.2.3.23)

Valve body Pressure boundarv Copper alloy

> 15% Zn Air - outdoor (ext)

Loss of material Selective Leaching lB.2.3.21\

-- -- H,6 Valve body Pressure Copper alloy Raw water (int) Cracking Fire Water System Vll.C1.A-473b 3.3-1 , E, 3 boundary > 15% Zn (B.2.3.16) 160 Valve body Pressure Copper alloy Raw water (int) Cracking Inspection of Internal Vll.C1 .A-473b 3.3-1, E, 4 boundary > 15% Zn Surfaces in 160 Miscellaneous Piping and Ducting Components (B.2.3.24)

Valve body Pressure Copper alloy Raw water (int) Loss of material Selective Leaching Vll.G.A-47 3.3-1, A boundary > 15% Zn (B.2.3.21 ) 072 Valve body Pressure Copper alloy Raw water (int) Wall thinning - Fire Water System Vll .C1 .A-409 3.3-1, E, 1 boundary > 15% Zn erosion (B.2.3.16) 126

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 21 of 41 Table 3.3.2-5: Fire Protection I Service Water - Summary of Aging Management Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Mana~ement Valve body Pressure Copper alloy Raw water (int) Wall thinning - Inspection of Internal Vll.C1.A-409 3.3-1, E, 2 boundary > 15% Zn erosion Surfaces in 126 Miscellaneous Piping and Ducting Components (B.2.3.24)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.21-3 L-2023-059 Attachment 3 Page 22 of 41 SLRA Table 3.3.2-5, page 3.3-164 is revised as follows:

Table 3.3.2-5: Fire Protection I Service Water - Summarv of Aaino Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaaement Valve body (halon) Pressure Carbon steel Gas (int) None None Vll .J.AP-6 3.3-1 , A (Unit 1 only) boundary 121 Valve body (Unit 2 Leakage Stainless steel Air- indoor Cracking External Surfaces Vll.G.AP-209b 3.3-1 , A only) boundary uncontrolled (ext) Monitoring of 004 (spatial) Mechanical Components

<B.2.3.23)

Valve body (Unit 2 Leakage Stainless steel Air- indoor Loss of material External Surfaces Vll.G.AP-221 b 3.3-1 , A only) boundary uncontrolled (ext) Monitoring of 006 (spatial) Mechanical Components

15% Zn material Leaching (B.2.3.21\

-- 444 Valve body (Unit 2 Pressure Stainless steel Air- indoor Cracking External Surfaces Vll.G.AP-209b 3.3-1, A only) boundary uncontrolled (ext) Monitoring of 004 Mechanical Components (8 .2.3.23)

Valve body (Unit 2 Pressure Stainless steel Air- indoor Loss of material External Surfaces Vll.G.AP-221 b 3.3-1 , A only) boundary uncontrolled (ext) Monitoring of 006 Mechanical Components

<B.2.3.23)

Vortex breaker Vortex Carbon steel Raw water (ext) Long-term loss One-Time Inspection Vll.G.A-532 3.3-1, A prevention of material <B.2.3.20) 193 Vortex breaker Vortex Carbon steel Raw water (ext) Loss of material Fire Water System Vll.G.A-412 3.3-1, A orevention (8.2.3.16) 136

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 23 of 41 SLRA Table 3.3.2-5, page 3.3-165 is revised as follows:

C. Component is different, but consistent with material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

D. Component is different, but consistent with material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP has exceptions to NUREG 2191 AMP description.

E. Consistent with NUREG-2191 material, environment, and aging effect but a different AMP is credited or NUREG-2191 identifies a plant-specific AMP.

G. Environment not in NUREG-2191 for this component and material.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

Plant Specific Notes

1. The Fire Water System AMP is used to manage the wall thinning due to erosion aging effect for fire protection components exposed to raw water.

2. The Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components AMP is used to manage the wall thinning due to erosion aging effect for service water components exposed to raw water.

3. The Fire Water System AMP is used to manage the cracking aging effect for copper alloy >15% Zn components internally exposed to raw water.

4. The Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components AMP is used to manage the cracking aging effect for copper alloy >15% Zn components internally exposed to raw water.

5. The External Surfaces Monitoring of Mechanical Components AMP is used to manage loss of material for the external surfaces of the yard sump pump 2A.

6. Based on plant-specific operating experience discussed in SLRA Section B.2.3.21, a one-time inspection of a representative sample of components using the elements of the Selective Leaching AMP will be performed to determine if this aging effect is present in the air-outdoor (ext) and air-outdoor (int) environments, as applicable.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 24 of 41 SLRA Table 3.3.2-7, page 3.3-182 is revised as follows:

Table 3.3.2-7: Instrument Air I Miscellaneous Bulk Gas Suoolv - Summarv of Aain1 Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Manaqement Valve body Pressure Copper alloy > Air- indoor Cracking External Surfaces Vlll.H .S-454 3.4-1, 106 A boundary 15%Zn uncontrolled (ext) Mon itoring of Mechanical Components

<B.2.3.23)

Valve body Pressure Copper alloy > Air- indoor None None Vll.J .AP-144 3.3-1, 114 A boundary 15% Zn uncontrolled (int)

Valve body Pressure Copper alloy > Air - outdoor Cracking External Surfaces Vll l. H.S-454 3.4-1 , 106 A boundary 15% Zn (ext) Monitoring of Mechan ical Components (8.2.3.23)

Valve body Pressure boundarv Copper alloy

> 15% Zn Air - outdoor text\

Loss of material Selective Leaching (B.2.3.21)

-- -- .!:h1 Valve body Pressure Stainless steel Air - dry (int) Loss of material Compressed Air Vll.D.A-764 3.3-1, 235 A boundary Monitoring

<B .2.3.14)

Valve body Pressure Stainless steel Air- indoor Cracking External Surfaces Vll.D.AP-209b 3.3-1, 004 A boundary uncontrolled (ext) Monitoring of Mechanical Components (8.2.3.23)

Valve body Pressure Stainless steel Air- indoor Loss of material External Surfaces Vll.D.AP-221 b 3.3-1 , 006 A boundary uncontrolled (ext) Monitoring of Mechanical Components (8.2.3.23) '

Valve body Pressure Stainless steel Air- indoor Cracking Inspection of Vll.D.AP-209c 3.3-1, 004 A boundary uncontrolled (int) Internal Surfaces in Miscellaneous Piping and Ducting Components

<B.2.3.24)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 25 of 41 SLRA Table 3.3.2-7, page 3.3-183 is revised as follows:

Table 3.3.2-7: Instrument Air I Miscellaneous Bulk Gas Supply - Summarv of Aaim Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Valve body Pressure Stainless steel Air- indoor Loss of material Inspection of Vll.D.AP-221c 3.3-1 , 006 A boundary uncontrolled (int) Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

Valve body Pressure Stainless steel Air - outdoor Cracking External Surfaces Vll.D.AP-209b 3.3-1, 004 A boundary (ext) Monitoring of Mechanical Components (B.2.3.23)

Valve body Pressure Stainless steel Air - outdoor Loss of material External Surfaces Vll.D.AP-221 b 3.3-1 , 006 A boundary (ext) Monitoring of Mechanical Components (B.2.3.23)

Valve body Pressure Stainless steel Gas (int) None None Vll.J.AP-22 3.3-1, 120 A boundary General Notes A. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

Plant Specific Notes Nooe,.

1. Based on plant-specific operating experience discussed in SLRA Section B.2.3.21, a one-time inspection of a representative sample of components using the elements of the Selective Leaching AMP will be performed to determine if this aging effect is present in the air-outdoor (ext) environment.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 26 of 41 SLRA Table 3.3.2-8, page 3.3-190 is revised as follows:

Table 3.3.2-8: Intake Coolina Water I Emeraenc, Coolina Canal - Summary of Aaina Manaaement Evaluation Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Piping Pressure Coating Raw water (int) Loss of coating or Internal Vll.G.A-416 3.3-1 , A boundary (cementitious) lining integrity Coatings/Linings for 138 (cementitious) In-Scope Piping, Piping Components, Heat Exchangers, and Tanks (B.2.3.28)

Piping Pressure Copper alloy Air - outdoor None None Vll.J.AP-144 3.3-1, A boundary (ext) 114 Piping Pressure Copper alloy Air - outdoor None None Vll.J.AP-144 3.3-1 , A boundary (int) 114 Piping Pressure Copper alloy > Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1 , A boundary 15% Zn uncontrolled Monitoring of 106 (ext) Mechanical Components (B.2.3.23)

Piping Pressure Copper alloy > Air - outdoor Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary 15% Zn (ext) Monitoring of 106 Mechanical Components (B.2.3.23)

Piping Pressure boundarv Copper alloy >

15%Zn Air - outdoor text)

Loss of material Selective Leaching

{8.2.3.21)

-- -- H, 3 Piping Pressure Copper alloy > Raw water (int) Cracking Open-Cycle Cooling Vll.C1 .A-473b 3.3-1 , A boundary 15% Zn Water System 160 (B.2.3.11 )

Piping Pressure Copper alloy > Raw water (int) Loss of material Selective Leaching Vll.C1 .A-47 3.3-1, A boundary 15%Zn (B.2.3.21 ) 072 Piping Pressure Copper alloy > Raw water (int) Loss of material Open-Cycle Cooling Vll.C1.AP-196 3.3-1 , A boundary 15% Zn Flow blockage Water System 034 (B.2.3.11 )

Piping Pressure Copper alloy > Raw water (int) Wall thinning - Open-Cycle Cooling Vll.C1.A-409 3.3-1 , E, 1 boundary 15% Zn erosion Water System 126 (B.2.3.11 )

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.21-3 L-2023-059 Attachment 3 Page 27 of 41 Table 3.3.2-8.: Intake Cooling Water I Emergenc Cooling Canal - Summary of Aging Management Evaluation 11 Component Type Intended Material Environment Aging Effect Aging Management NUREG-2191 Table 1 Notes Function Requiring Program Item Item Management Piping Pressure Copper alloy > Air- indoor Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary 8%AI uncontrolled Monitoring of 106 (ext) Mechanical Components (B.2.3.23)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 28 of 41 SLRA Table 3.3.2-8, page 3.3-202 is revised as follows:

General Notes A. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

B. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP has exceptions to NUREG-2191 AMP description.

E. Consistent with NUREG-2191 material, environment, and aging effect but a different AMP is credited or NUREG-2191 identifies a plant-specific AMP.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

Plant Specific Notes

1. The Open-Cycle Cooling Water AMP is used to manage wall thinning due to erosion for the interior surfaces of components within the service water system exposed to raw water within the scope of the GL 89-13 program.

2. The Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components AMP is used to manage wall thinning due to erosion for the interior surfaces of components within the intake cooling water system exposed to raw water not within the scope of the GL 89-13 program.

~- Based on plant-specific operating experience discussed in SLRA Section B.2.3.21, a one-time inspection of a representative sample of components using the elements of the Selective Leaching AMP will be performed to determine if this aging effect is present in the air-outdoor (ext) environment.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 29 of 41 SLRA Table 3.4.2-1, page 3.4-52 is revised as follows:

Table 3.4.2-1: Main Steam - Summary of Aain ct Manaaement Evaluation Component Intended Material Environment Aging Effect Aging NUREG-2191 Table 1 Notes Type Function Requiring Management Item Item Management Program Valve body Pressure Carbon steel Air - outdoor (ext) Loss of material External Surfaces Vlll.H.S-29 3.4-1 , A boundary Monitoring of 034 Mechanical Components (8.2.3.23)

Valve body Pressure Carbon steel Steam (int) Loss of material Water Chemistry Vlll.81 .SP-71 3.4-1 , A boundary (8.2.3.2) 014 One-Time Inspection (8.2.3.20)

Valve body Pressure Carbon steel Steam (int) Wall thinning - Flow-Accelerated Vlll.81 .S-408 3.4-1 , A boundary erosion Corrosion (8.2.3.8) 060 Valve body Pressure Carbon steel Steam (int) Wall thinning - Flow-Accelerated Vlll.81 .S-15 3.4-1 , A boundary FAC Corrosion (8.2.3.8) 005 Valve body Pressure Carbon steel Treated water (int) Loss of material Water Chemistry Vlll.81 .SP-74 3.4-1 , A boundary (8.2.3.2) 014 One-Time Inspection (8.2.3.20)

Valve body Pressure Carbon steel Treated water (int) Wall thinning - Flow-Accelerated Vlll.01 .S-408 3.4-1 , A boundary erosion Corrosion (8.2.3.8) 060 Valve body Pressure Carbon steel Treated water (int) Wall thinning - Flow-Accelerated Vlll.01.S-16 3.4-1 , A boundary FAC Corrosion (8.2.3.8) 005 Valve body Pressure Copper alloy Air - dry (int) Loss of material Compressed Air Vll.O.A-764 3.3-1 , A boundary > 15% Zn Monitoring 235 (8.2.3.14)

Valve body Pressure Copper alloy Air - outdoor (ext) Cracking External Surfaces Vlll.H.S-454 3.4-1, A boundary > 15% Zn Monitoring of 106 Mechanical Components (8.2.3.23)

Valve body Pressure boundarv Copper alloy> 15%

Air - outdoor (ext)

Loss of material Selective Leaching

-- -- .!:h.1 Zn lB.2.3.21\

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 30 of 41 Table 3.4.2-1: Main Steam - Summary of Agin~ Management Evaluation Component Intended Material Environment Aging Effect Aging NUREG-2191 Table 1 Notes Type Function Requiring Management Item Item ManaQement ProQram Valve body Pressure Low-alloy Steam (int) Loss of material Water Chemistry Vlll.81 .SP-71 3.4-1 , A boundary steel (B.2.3.2) 014 One-Time Inspection (B.2.3.20)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.21-3 L-2023-059 Attachment 3 Page 31 of 41 SLRA Table 3.4.2-1, page 3.4-55 is revised as follows:

Table 3.4.2-1: Main Steam - Summary of Aging Management Evaluation Component Intended Material Environment Aging Effect Aging NUREG-2191 Table 1 Notes Type Function Requiring Management Item Item Management Program Valve body Pressure Stainless Air- indoor Cracking External Surfaces Vlll.H.S-452c 3.4-1 , A (insulated) boundary steel uncontrolled (ext) Monitoring of 104 Mechanical Components (8 .2.3.23)

Valve body Pressure Stainless Air- indoor Loss of material External Surfaces Vlll.H.S-451c 3.4-1 , A (insulated) boundary steel uncontrolled (ext) Monitoring of 103 Mechanical Components (8.2.3.23)

Valve body Pressure Stainless Air - outdoor (ext) Cracking External Surfaces Vlll.H.S-452c 3.4-1 , A (insulated) boundary steel Monitoring of 104 Mechanical Components (8.2.3.23)

Valve body Pressure Stainless Air - outdoor (ext) Loss of material External Surfaces Vlll.H.S-451c 3.4-1 , A (insulated) boundary steel Monitoring of 103 Mechanical Components (8 .2.3.23)

Valve body Pressure Stainless Gas (int) None None Vlll.l.SP-15 3.4-1 , A (Unit 1 only) boundary steel 058 General Notes A. Consistent with component, material, environment, aging effect, and AMP listed for NUREG-2191 line item. AMP is consistent with NUREG-2191 AMP description.

H. Aging effect not in NUREG-2191 for this component, material, and environment combination.

Plant Specific Notes NeR&.-1. Based on plant-specific operating experience discussed in SLRA Section B.2.3.21, a one-time inspection of a representative sample of components using the elements of the Selective Leaching AMP will be performed to determine if this aging effect is present in the air-outdoor (ext) environment.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21 -3 L-2023-059 Attachment 3 Page 32 of 41 SLRA Appendix A1, Section 19.2.2.21 , page A1 -26 is revised as follows :

loss of material will not cause a loss of intended function for steel components exposed to environments that do not include corrosion inhibitors as a preventive action .

The elements of the PSL One-Time Inspection AMP include: (a) determination of the sample size of components to be inspected based on an assessment of materials of fabrication, environment, plausible aging effects, and OE, (b) identification of the inspection locations in the system or component based on the potential for the aging effect to occur, (c) determination of the examination technique, including acceptance criteria that would be effective in managing the aging effect for which the component is examined, and (d) an evaluation of the need for follow-up examinations to monitor the progression of aging if age-related degradation is found that could jeopardize an intended function before the end of the SPEO.

The PSL One-Time Inspection AMP is used to verify the effectiveness of the PSL Water Chemistry, Fuel Oil Chemistry, and Lubricating Oil Analysis AMPs. For carbon steel components exposed to water environments that do not include corrosion inhibitors as a preventive action (e.g ., raw water and waste water) or carbon steel components that do not have wall thickness measurement exam inations conducted of a representative sample of each environment between the 50 1h and 60 1h year of operation, the program is used to verify that long-term loss of material due to general corrosion will not cause a loss of intended function [e.g ., pressure boundary, leakage boundary (spatial) , and structural integrity].

Periodic inspections are used instead of the PSL One-Time Inspection AMP for structures or components with known age-related degradation mechanisms or when the environment in the SPEO is not expected to be equivalent to that in the prior operating period. Inspections not conducted in accordance with ASME Code Section XI requirements are conducted in accordance with plant-specific procedures, including inspection parameters such as lighting, distance, offset, and surface conditions .

19.2.2.21 Selective Leaching The PSL Selective Leaching AMP is a new AMP that includes inspections of components that may be susceptible to loss of material due to selective leaching by demonstrating the absence of selective leaching (dealloying) of materials. The scope of this AMP includes components constructed of gray cast iron, ductile iron, and copper alloys (except for inhibited brass) containing greater than 15% Zn or greater than 8% Al in susceptible environments. One-time inspections for components exposed to a closed-cycle cooling water or treated water environment will be conducted, based on PSL plant-specific OE which has not revealed selective leaching in these environments. In addition, based on PSL plant-specific OE, to confirm that loss of material due to selective leaching is an aging effect unique to the external surfaces of the Unit 1 EOG copper alloy with greater than 15 percent zinc radiator tubes, PSL will perform a one-time inspection

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8 .2.3.21-3 L-2023-059 Attachment 3 Page 33 of 41 of a representative sample of Unit 1 and 2 copper alloy with greater than 15 percent zinc components exposed to an air-outdoor external and air-outdoor internal environments, as applicable, prior to the SPEO.

Opportunistic and periodic inspections will be conducted for selective leaching susceptible components exposed to raw water, waste water, soil, and groundwater environments. Opportunistic inspections will be performed whenever components are opened, or whenever buried or submerged surfaces are exposed. The periodic inspections are conducted at an interval of no greater than every 10 years during the SPEO. Visual inspections coupled with mechanical examination techniques, such as chipping or scraping, will be conducted. Periodic destructive examinations of components for physical properties (i.e., degree of dealloying, depth of dealloying, through-wall thickness, and chemical composition)

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.21-3 L-2023-059 Attachment 3 Page 34 of 41 SLRA Appendix A 1, Section 19.4, Table 19-3 commitment No. 24 (page A 1-89), is revised as follows:

Table 19-3 List of Unit 1 SLR Commitments and Implementation Schedule No. Aging Management NUREG-2191 Commitment Implementation Schedule Program or Activity Section (Section) 24 Selective Leaching Xl.M33 Implement the new PSL Selective Leaching AMP.,., including the No later than 6 months prior to (19.2.2.21 ) following additional action: the SPEO, or no later than the last refueling outage prior to the fil To confirm that loss of material due to selective SPEO i.e.:

leaching is an aging effect unigue to the external surfaces of the Unit 1 EOG coi;rner allo)l with greater PSL 1: 09/01/2035 than 15 Rercent zinc radiator tubes 1 PSL will Rerform a one-time insRection of a reRresentative samRle of Unit 1 Implement the AMP and start and 2 CORRer allo)l with greater than 15 Rercent zinc the one-time and 10-year comQonents exQosed to an air-outdoor external and air- interval inspections no earlier outdoor internal environments 1 as aQQlicable 1 Qrior to than 10 years prior to the SPEO the SPEO. This insQection will be Qerformed in (03/01/2026).

accordance with the Selective Leaching AMP and will be considered a seQarate insQection QOQUlation.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 35 of 41 SLRA Appendix A2, Section 19.2.2.21, page A2-26 is revised as follows:

The elements of the PSL One-Time Inspection AMP include: (a) determination of the sample size of components to be inspected based on an assessment of materials of fabrication, environment, plausible aging effects, and OE, (b) identification of the inspection locations in the system or component based on the potential for the aging effect to occur, (c) determination of the examination technique, including acceptance criteria that would be effective in managing the aging effect for which the component is examined, and (d) an evaluation of the need for follow-up examinations to monitor the progression of aging if age-related degradation is found that could jeopardize an intended function before the end of the SPEO.

The PSL One-Time Inspection AMP is used to verify the effectiveness of the PSL Water Chemistry, Fuel Oil Chemistry, and Lubricating Oil Analysis AMPs. For carbon steel components exposed to water environments that do not include

• corrosion inhibitors as a preventive action (e.g. , raw water and waste water) or carbon steel components that do not have wall thickness measurement examinations conducted of a representative sample of each environment between the 50 1h and 60 1h year of operation, the program is used to verify that long-term loss of material due to general corrosion will not cause a loss of intended function [e.g. , pressure boundary, leakage boundary (spatial), and structural integrity].

Periodic inspections ar13 used instead of the PSL One-Time Inspection AMP for structures or components with known age-related degradation mechanisms or when the environment in the SPEO is not expected to be equivalent to that in the prior operating period. Inspections not conducted in accordance with ASME Code Section XI requirements are conducted in accordance with plant-specific procedures, including inspection parameters such as lighting, distance, offset, and surface conditions .

19.2.2.21 Selective Leaching The PSL Selective Leaching AMP is a new AMP that includes inspections of components that may be susceptible to loss of material due to selective leaching by demonstrating the absence of selective leaching (dealloying) of materials. The scope of this AMP includes components constructed of gray cast iron, ductile iron, and copper alloys (except for inhibited brass) containing greater than 15% Zn or greater than 8% Al in susceptible environments. One-time inspections for components exposed to a closed-cycle cooling water or treated water environment will be conducted , based on PSL plant-specific OE which has not revealed selective leaching in these environments.

Based on PSL plant-specific OE, to confirm that loss of material due to selective leaching is an aging effect unique to the external surfaces of the Unit 1 EOG copper alloy with greater than 15 percent zinc radiator tubes, PSL will perform a one-time inspection of a representative sample of Unit 1 and 2 copper alloy with greater than 15 percent zinc components exposed to an air-outdoor external and air-outdoor internal environments, as

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 36 of 41 applicable, prior to the SPEO. In addition, PSL will perform a one-time inspection of a representative sample of the Unit 2 EOG Admiralty brass radiator tubes exposed to an air-indoor uncontrolled external environment.

These inspections will be performed prior to the SPEO in accordance with the Selective Leaching AMP and will be considered two separate inspection populations.

Opportunistic and periodic inspections will be conducted for selective leaching susceptible components exposed to raw water, waste water, soil, and groundwater environments. Opportunistic inspections will be performed whenever components are opened, or whenever buried or submerged surfaces are exposed. The periodic inspections are conducted at an interval of no greater than every 10 years during the SPEO. Visual inspections coupled with mechanical examination techniques, such as chipping or scraping, will be conducted. Periodic destructive examinations of components for physical properties (i.e., degree of dealloying, depth of dealloying, through-wall thickness, and chemical composition) will be conducted for components exposed to raw water, waste water, soil, and groundwater environments.

Inspections and tests will be conducted to determine whether loss of material will affect the ability of the components to perform their intended function for the SPEO.

Inspections will be conducted in accordance with

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8.2.3.21-3 L-2023-059 Attachment 3 Page 37 of 41 SLRA Appendix A2, Section 19.4, Table 19-3 commitment No. 24 (page A2-89), is revised as follows:

Table 19-3 List of Unit 1 SLR Commitments and Implementation Schedule No. Aging Management NUREG-2191 Commitment Implementation Schedule Program or Activity Section (Section) 24 Selective Leaching Xl.M33 Implement the new PSL Selective Leaching AMP.,., including the No later than 6 months prior to (19.2.2.21 ) following additional actions: the SPEO, or no later than the last refueling outage prior to the fil To confirm that loss of material due to selective SPEO i.e. :

leaching is an aging effect unigue to the external surfaces of the Unit 1 EOG coi;mer allo)l with greater PSL2: 10/06/2042 than 15 Rercent zinc radiator tubes 1 PSL will Rerform a one-time insRection of a reRresentative samRle of Unit 1 Implement the AMP and start and 2 CORRer allo)l with greater than 15 Rercent zinc the one-time and 10-year comRonents exRosed to an air-outdoor external and air- interval inspections no earlier outdoor internal environments 1 as aRRlicable 1 Rrior to than 10 years prior to the SPEO the SPEO. This insRection will be Rerformed in (04/06/2033).

accordance with the Selective Leaching AMP and will be considered a seRarate insRection RORUlation.

!tl In addition 1 PSL will Rerform a one-time insRection of the Unit 2 EOG Admiraltv brass radiator tubes exRosed to an air-indoor uncontrolled external environment Rrior to the SPEO. This insRection will be Rerformed in accordance with the Selective Leaching AMP and will be considered a seRarate insRection RORUlation.

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. 8 .2.3.21-3 L-2023-059 Attachment 3 Page 38 of 41 SLRA Section 8 .2.3.21, page 8-181 is revised as follows :

the pipe was representative of the fire water distribution system for the plant.

• On June 13, 2022, the 18 EOG was started for its monthly surveillance test. At approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 21 minutes into the unloaded portion of the surveillance run, Operations reported a significant coolant leak coming from the radiator on the 182 engine and requested the EOG be shut down. The 18 EOG remained out of service for approximately 3 days while the 182 EOG radiator was replaced. On June 16, 2022, the 18 EOG was satisfactorily tested and restored to Operable status.

The 182 radiator core section containing the failed brass tube was ,

sent off site for independent forensic analysis. Results of the radiator tube failure analysis identified the failure mechanism to be a crack in the seamless tube material at a location weakened by low zinc content. The failure analysis report identified several key facts about the specific mechanism that caused the seamless tube to fail. The report stated:

"Laboratory analysis of the failed tube crack tips revealed the zinc was leached from the brass material, leaving behind a porous, copper-rich structure with zinc content ranging from 6.55% to 15.75% as compared with the zinc content of 32.53%

in the smooth (non-corroded) tube area. Zinc leaching was assisted by the corrosive deposit accumulations at the bottom half of the radiator. The leaching process removed zinc from the alloy and allowed the zinc to form a porous white zinc oxide deposit layer on the tube OD surfaces. The remaining porous copper-rich structure of the tube wall possessed reduced mechanical strength. As the corrosion process continued, with resulting reduction of mechanical strength, the tube wall eventually became unable to withstand the water pressure in the coolant system and cracked. 11 The report concluded:

"The combination of damp conditions, elevated temperature during operation, and accumulation of corrosive deposits on the tube OD surface accelerated corrosion of the fan side fin and tubes. The copper fins were degraded by general corrosion. The yellow brass tubes contained more than 15%

zinc and were susceptible to selective leaching of the zinc, or dezincification. This process-reduced the mechanical strength of the tube to the point where the remaining tube wall was unable to withstand the water pressure in the coolant system, resulting in the through wall crack. 11

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 39 of 41 Other key take-aways from the report and discussions with in-house and metallurgists include:

• The crack developed and propagated rapidly based on the following:

o The crack was uniform in width.

o The tube wall thickness was relatively uniform (i.e., no wall thinning due to the identified corrosion mechanism).

o There was no evidence of tube swelling in the seamless tubes.

o There was no evidence of a pre-existing flaw or crack at the initiation site. (i.e., no prior leakage) o There was no evidence of a small flaw or crack that propagated over time due to vibration, fatigue, or wall thinning.

• De-alloying and selective leaching were OD-initiated and led to the failure.

• Dezincification of yellow brass tubes is a time-dependent corrosion mechanism with the corrosion rate based on several variables including humidity, salt concentration, effectiveness of coating material, effectiveness of rinsing, moisture in the core, etc. (but there are too many variables to predict the zinc oxide corrosion rates).

• Dezincification is localized with selective de-alloying in one area, and little or no de-alloying in nearby locations.

• Dezincification of yellow brass tubes is a different corrosion mechanism than the general corrosion mechanism of the copper fins.

• Tube corrosion is not dependent on fin corrosion.

• The selective leaching/dezincification rate is non-linear, non-uniform, and the rate is unpredictable. (i.e., it is not possible to estimate a threshold for tube failures.)

• The failure mechanism of the yellow brass tube required Scanning Electron Microscopy (SEM) to detect selective leaching, weakening and embrittlement of the base material.

Historically, a previous 182 EOG radiator tube leak failure occurred in 2001.

At that time, the yellow brass tubes were rolled and soldered; not seamless as is the current design. Similar to the 2022 182 EOG radiator failure, tube,

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 40 of 41 the tube failure occurred on the fan side of the radiator. A root cause evaluation of the 2001 failure, including forensic analysis, was performed and concluded:

"The root cause of the radiator tube failure was the result of the loss of the cooling fins due to corrosion that provided structural support for the radiator flat tubes. The Joss of the fins allowed the flat tubes to swell and vibrate combined with the thermal and pressure eve/es experienced by the radiator contributed to the failure of the soldered mechanical tube joint. The loss of the cooling fin was due to corrosion from humid, salt laden environment."

Therefore, this first-time failure of the 182 copper alloy radiator tube exposed to an air-indoor uncontrolled environment due to selective leaching is a PSL plant-specific aging effect. Further evaluation concludes that this plant-specific aging effect is unique to the Unit 1 EOG radiators based on the following:

• No other recent plant-specific OE regarding component failures due to selective leaching,

• No failures of the Unit 2 EOG radiators after approximately 39 years of service,

• Unique design of the Unit 1 EOG radiators,

• Periodic rinsing of the Unit 1 EOG radiators

• Severe environmental conditions the Unit 1 EOG radiators are exposed to during EOG runs with radiator fans in operation.

Based on this event, to confirm that loss of material due to selective leaching is an aging effect unique to the external surfaces of the Unit 1 EOG copper alloy with greater than 15 percent zinc radiator tubes, PSL will perform a one-time inspection of a representative sample of Unit 1 and 2 copper alloy with greater than 15 percent zinc components exposed to an air-outdoor external and air-outdoor internal environments, as applicable. In addition, PSL will perform a one-time inspection of a representative sample of the Unit 2 EOG Admiralty brass radiator tubes exposed to an air-indoor uncontrolled external environment. These inspections will be performed prior to the SPEO in accordance with the Selective Leaching AMP and will be considered two separate inspection populations.

• NRC Reviews and Inspections On November 20, 2015 and October 20, 2017, the NRC completed a Post-Approval Site Inspection for License Renewal at PSL Unit 1 and Unit 2, respectively, in accordance with NRC IP71003. The NRC inspectors did not identify any findings or violations of more than minor significance and determined

St. Lucie Units 1 and 2 Dockets 50-335 and 50-389 PSL Response to NRC RAI No. B.2.3.21-3 L-2023-059 Attachment 3 Page 41 of 41 that the overall implementation of aging management programs and time-limited aging analyses was consistent with the licensing basis of the facility. The inspectors also determined that the regulatory requirements of 10 CFR 54.37(b) were met, and commitment changes were evaluated and reported in accordance with the applicable requirements.

OE will be reviewed such that if there is an indication that the effects of aging are not being adequately managed, a corrective action will be initiated to either enhance the AMP or implement new AMPs, as appropriate. In addition, AMP effectiveness will be assessed at least every five years per NEI 14-12.

The PSL Selective Leaching AMP will be informed and enhanced when necessary through the systematic and ongoing review of both plant-specific and industry OE, including research and development, such that the effectiveness of the AMP is evaluated consistent with the discussion in NUREG-2191, Appendix B.

Conclusion The PSL Selective Leaching AMP will provide reasonable assurance that the effects of aging will be managed so that the intended function(s) of components within the scope of the AMP will be maintained consistent with the CLB during the SPEO.

Associated

Enclosures:

None.