DCL-25-023, Supplement and Annual Update - Diablo Canyon Power Plant License Renewal Application, Amendment 4

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Supplement and Annual Update - Diablo Canyon Power Plant License Renewal Application, Amendment 4
ML25069A508
Person / Time
Site: Diablo Canyon  
(DPR-080, DPR-082)
Issue date: 03/06/2025
From: Zawalick M
Pacific Gas & Electric Co
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
DCL-25-023
Download: ML25069A508 (1)
v • d • e


Text

Maureen R. Zawalick Vice President Business and Technical Services Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 805.545.4242 Maureen.Zawalick@pge.com A member of the STARS Alliance Callaway x Diablo Canyon x Palo Verde x Wolf Creek PG&E Letter DCL-25-023 ATTN: Document Control Desk 10 CFR 54 U.S. Nuclear Regulatory Commission 10 CFR 54.21(b)

Washington, DC 20555-0001 Diablo Canyon Units 1 and 2 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Supplement and Annual Update: Diablo Canyon Power Plant License Renewal Application, Amendment 4

References:

1. PG&E Letter DCL-23-118, License Renewal Application, dated November 7, 2023 (ML23311A154)
2. PG&E Letter DCL-24-092, Supplement and Annual Update: Diablo Canyon Power Plant License Renewal Application, Amendment 1, dated October 14, 2024 (ML24289A118)
3. PG&E Letter DCL-25-001, Response to Request for Additional Information by the Office of Nuclear Reactor Regulation Diablo Canyon Safety Review Pacific Gas and Electric Company Diablo Canyon Units 1 and 2 (Set 2),

dated January 2, 2025 (ML25002A050)

4. PG&E Letter DCL-25-022, Response to Request for Additional Information by the Office of Nuclear Reactor Regulation Diablo Canyon LRA Safety Review Pacific Gas and Electric Company Diablo Canyon Units 1 and 2 (Set 3), dated February 2025

Dear Commissioners and Staff:

In Reference 1, Pacific Gas and Electric Company (PG&E) submitted an operating license renewal application (LRA) for Diablo Canyon Power Plant (DCPP) Units 1 and 2 to extend the current Facility Operating Licenses an additional 20 years beyond their current expiration dates. In References 2, 3 and 4, PG&E amended the LRA. To support NRC's review of the LRA, PG&E is providing this voluntary supplement.

In addition, in accordance with 10 CFR 54.21(b), each year following submittal of the LRA and at least three months before scheduled completion of the NRC review, an update to the LRA must be submitted that identifies any current licensing basis changes that materially affect the contents of the LRA, including the Final Safety Analysis Report supplement. Reference 2 provided the first yearly 10 CFR 54.21(b) update through June 30, 2024. This submittal includes the 10 CFR 54.21(b) update at least three months before scheduled completion of the NRC review and includes updates through December 31, 2024.

Pacific Gas anti Elecmr: Company*

Document Control Desk PG&E Letter DCL-25-023 Page 2 A member of the STARS Alliance Callaway x Diablo Canyon x Palo Verde x Wolf Creek The Enclosure to this letter provides the LRA change descriptions and revisions, including those made pursuant to 10 CFR 54.21(b). For ease of reference, the index of attachment topics is provided in the Enclosure of this letter. In each attachment, unless otherwise noted, changes are described along with the affected section(s) and page number(s) of the docketed full LRA (Reference 1) where the changes apply. For clarity, revisions to the LRA are provided with deleted text by red strikethroughs and inserted text by blue underline. Bolded LRA text indicates portions that were previously amended by References 2, 3, or 4. Revisions to LRA tables are shown by providing excerpts from each affected table.

DCPP LRA, Appendix A, Table A-3, List of License Renewal Commitments and Implementation Schedules, provides the commitments made in the application.

This table is amended in Enclosure Attachment K.

If you have any questions or require additional information, please contact Mr. Philippe Soenen at (805) 459-3701.

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

Executed on ____________________.

Sincerely, Maureen R. Zawalick Vice President, Business and Technical Services Enclosure cc:

Diablo Distribution cc/enc:

Anthony Chu, Chief, California Department of Public Health Kim Conway, NRC Environmental Project Manager Lauren Gibson, NRC License Renewal Branch Chief Brian Harris, NRC Senior Project Manager Mahdi O. Hayes, NRC Senior Resident Inspector Delphine Hou, California Department of Water Resources Samson S. Lee, NRR Senior Project Manager John D. Monninger, NRC Region IV Deputy Administrator March 6, 2025 1

Enclosure PG&E Letter DCL-25-023 Diablo Canyon Power Plant, Units 1 and 2 License Renewal Application, Amendment 4, Change Descriptions and Revisions

Enclosure PG&E Letter DCL-25-023 Page 1 of 1 Enclosure Attachment Index Attachment Topics A

Miscellaneous Errata B

Saltwater and Chlorination System Scoping, Screening, and Aging Management Review (SSAMR) and Makeup Water System SSAMR C

Control Room HVAC System SSAMR D

Auxiliary Steam System SSAMR E

Reactor Coolant Pressure Boundary Piping Time-Limited Aging Analysis (TLAA)

F Bolting Integrity Aging Management Program (AMP)

G One-Time Inspection of ASME Code Class 1 Small Bore-Piping AMP H

Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements AMP I

Buried and Underground Piping and Tanks AMP J

Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP K

License Renewal (LR) Commitment Updates

Enclosure Attachment A PG&E Letter DCL-25-023 Page 1 of 12 Supplement - DCPP LRA, Amendment 4 Attachment A: Miscellaneous Errata Affected License Renewal Application (LRA) Sections: Section B.2.2.2; Tables 3.3.2-2, 3.3.2-4, 3.3.2-6, 3.3.2-8, 3.4.2-1, 3.5.2-1, 3.5.2-2, and 3.5.2-3 LRA Page Numbers: 3.3-104, 3.3-105, 3.3-135, 3.3-183, 3.3-249, 3.4-77, 3.4-81, 3.5-88, 3.5-93, 3.5-98 through 3.5-100, and B.2-8 Description of Change:

1. LRA Table 3.3.2-2 is revised to remove one duplicate row for each of the following:

x Stainless Steel Piping, Piping Components with a leakage boundary (spatial) intended function exposed to a plant indoor air internal environment.

x Stainless Steel Piping, Piping Components with a pressure boundary intended function exposed to a plant indoor air internal environment.

x Stainless Steel Piping, Piping Components with a pressure boundary intended function exposed to a treated borated water internal environment.

2. In DCL-24-092, Enclosure 1, Attachment K, LRA Table 3.3.2-4, Heat Exchanger (CCW Pump Casing Lube Oil Cooler) Tubes, was revised to reference NUREG-1801 item VIII.C2.AP-205. LRA Table 3.3.2-4 is updated to correct the NUREG-1801 item to VII.C2.AP-205 instead of VIII.C2.AP-205 to align with NRC guidance.
3. LRA Table 3.3.2-6 is revised to remove one duplicate row for Stainless Steel Piping, Piping Components with a leakage boundary (spatial) intended function exposed to a treated borated water internal environment.
4. LRA Table 3.3.2-8 is revised to correct the NUREG-1801 Item used for Carbon Steel Valve Body exposed to plant indoor air (int). NUREG-1801 Item VIII.B1.SP-60 is updated to V.A.E-29, which has no impact on the proposed aging effects requiring management or AMP.
5. In DCL-24-092, Enclosure 1, Attachment Y (change 3), LRA Table 3.4.2-1 was revised to reflect removal of a portion of components associated with the steam generator blowdown treatment demineralizer system from the scope of LR. LRA Table 3.4.2-1 is revised to correctly remove one additional row as part of that update: Cast Austenitic Stainless Steel Valve Body with a leakage boundary (spatial) intended function exposed to a demineralized water internal environment.

In addition, LRA Table 3.4.2-1 is revised to remove the following row to reflect actual plant configuration: Stainless Steel Valve Body with a structural integrity (attached) intended function exposed to a demineralized water internal environment.

Enclosure Attachment A PG&E Letter DCL-25-023 Page 2 of 12 Supplement - DCPP LRA, Amendment 4

6. LRA Table 3.5.2-1 is revised to remove one duplicate row for each of the following:

x Carbon Steel Support (ASME Class 1 Component) with a structural support intended function exposed to a borated water leakage external environment.

x Carbon Steel Support (ASME Class 1 Component) with a structural support intended function exposed to a plant indoor air (structural) external environment.

7. LRA Table 3.5.2-2 is revised to remove one duplicate row for Concrete (Inaccessible Areas): All exposed to a plant indoor air (structural) external environment.
8. LRA Table 3.5.2-3 is revised to remove one duplicate row for each of the following:

x Concrete (Accessible Areas): Interior and Above-Grade Exterior exposed to a plant indoor air (structural) external environment.

x Concrete (Inaccessible Areas): All exposed to a plant indoor air (structural) external environment.

9. LRA Section B.2.2.2 is revised to add the close parenthesis in the section title.

Enclosure Attachment A PG&E Letter DCL-25-023 Page 3 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-2 on pages 3.3-104 and 3.3-105 is revised as follows:

Table 3.3.2-2: Spent Fuel Pool Cooling System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes

Piping, Piping Components Leakage Boundary (spatial)

Stainless Steel Plant Indoor Air (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

V.A.EP-81 3.2-1, 048 B

Piping, Piping Components Leakage Boundary (spatial)

Stainless Steel Plant Indoor Air (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

V.A.EP-81 3.2-1, 048 B

Piping, Piping Components Pressure Boundary Stainless Steel Plant Indoor Air (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

V.A.EP-81 3.2-1, 048 B

Piping, Piping Components Pressure Boundary Stainless Steel Plant Indoor Air (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

V.A.EP-81 3.2-1, 048 B

Piping, Piping Components Pressure Boundary Stainless Steel Treated Borated Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VII.A3.AP-79 3.3-1, 125 A

Piping, Piping Components Pressure Boundary Stainless Steel Treated Borated Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VII.A3.AP-79 3.3-1, 125 A

Enclosure Attachment A PG&E Letter DCL-25-023 Page 4 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-4 on page 3.3-135 (as modified by DCL-24-092, Encl. 1, Att. K) is revised as follows:

Table 3.3.2-4: Component Cooling Water System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Heat Exchanger (CCW Pump Casing Lube Oil Cooler)

Tubes Heat Transfer Copper Alloy

(>15% Zinc)

Closed-Cycle Cooling Water (Int)

Reduction of Heat Transfer Closed Treated Water Systems (B.2.3.12)

VIII.C2.AP-205 3.3-1, 050 B

Enclosure Attachment A PG&E Letter DCL-25-023 Page 5 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-6 on page 3.3-183 is revised as follows:

Table 3.3.2-6: Nuclear Steam Supply Sampling System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes

Piping, Piping Components Leakage Boundary (spatial)

Stainless Steel Treated Borated Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VII.E1.AP-79 3.3-1, 125 A

Piping, Piping Components Leakage Boundary (spatial)

Stainless Steel Treated Borated Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VII.E1.AP-79 3.3-1, 125 A

Enclosure Attachment A PG&E Letter DCL-25-023 Page 6 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-8 on page 3.3-249 is revised as follows:

Table 3.3.2-8: Chemical and Volume Control System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Valve Body Leakage Boundary (spatial)

Carbon Steel Plant Indoor Air (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

V.A.E-29VIII.B1.SP-60 3.2-1, 0443.4-1, 037 B

Enclosure Attachment A PG&E Letter DCL-25-023 Page 7 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.4.2-1 on pages 3.4-77 and 3.4-81 is revised as follows:

Table 3.4.2-1: Turbine Steam Supply System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Valve Body Leakage Boundary (spatial)

Cast Austenitic Stainless Steel Demineralized Water (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

VIII.D1.SP-87 3.4-1, 016 E, 1 Valve Body Structural Integrity (attached)

Stainless Steel Demineralized Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VIII.D1.SP-87 3.4-1, 016 A

Enclosure Attachment A PG&E Letter DCL-25-023 Page 8 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.5.2-1 on page 3.5-88 (as modified by DCL-24-092, Encl. 1, Att. DD) is revised as follows:

Table 3.5.2-1: Containment Building - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Support (ASME Class 1 Component)

Structural Support Carbon Steel Borated Water Leakage (Ext)

Loss of Material Boric Acid Corrosion (B.2.3.4)

III.B1.1.T-25 3.5-1, 089 A

Support (ASME Class 1 Component)

Structural Support Carbon Steel Borated Water Leakage (Ext)

Loss of Material Boric Acid Corrosion (B.2.3.4)

III.B1.1.T-25 3.5-1, 089 A

Support (ASME Class 1 Component)

Structural Support Carbon Steel Plant Indoor Air (Structural) (Ext)

Loss of Material ASME Section XI, Subsection IWF (B.2.3.30)

III.B1.1.T-24 3.5-1, 091 B

Support (ASME Class 1 Component)

Structural Support Carbon Steel Plant Indoor Air (Structural) (Ext)

Loss of Material ASME Section XI, Subsection IWF (B.2.3.30)

III.B1.1.T-24 3.5-1, 091 B

Enclosure Attachment A PG&E Letter DCL-25-023 Page 9 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.5.2-2 on page 3.5-93 (as modified by DCL-24-092, Encl. 1, Att. EE) is revised as follows:

Table 3.5.2-2: Control Room (Located in Auxiliary Building) - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Concrete Fire Barrier Concrete Plant Indoor Air Cracking Structures Monitoring III.A1.TP-204 3.5-1, A, 1 (Inaccessible HELB (Structural) (Ext)

Program (B.2.3.33) 043 Areas): All Shielding

Shelter, Protection Structural Pressure Boundary Structural Support Concrete Fire Barrier Concrete Plant Indoor Air Cracking Structures Monitoring III.A1.TP-204 3.5-1, A, 1 (Inaccessible HELB (Structural) (Ext)

Program (B.2.3.33) 043 Areas): All Shielding

Shelter, Protection Structural Pressure Boundary Structural Support

Enclosure Attachment A PG&E Letter DCL-25-023 Page 10 of 12 Supplement - DCPP LRA, Amendment 4 LRA Table 3.5.2-3 on pages 3.5-98 through 3.5-100 (as modified by DCL-24-092, Encl. 1, Att. EE) is revised as follows:

Table 3.5.2-3: Auxiliary Building - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Concrete (Accessible Areas):

Interior and Above-Grade Exterior Fire Barrier Flood Barrier HELB Shielding Missile Barrier Shelter, Protection Shielding Structural Pressure Boundary Structural Support Concrete Plant Indoor Air (Structural) (Ext)

Cracking Loss of Bond Loss of Material (Spalling, Scaling)

Structures Monitoring Program (B.2.3.33)

III.A3.TP-26 3.5-1, 066 A, 2 Concrete (Accessible Areas):

Interior and Above-Grade Exterior Fire Barrier Flood Barrier HELB Shielding Missile Barrier Shelter, Protection Shielding Structural Pressure Boundary Structural Support Concrete Plant Indoor Air (Structural) (Ext)

Cracking Loss of Bond Loss of Material (Spalling, Scaling)

Structures Monitoring Program (B.2.3.33)

III.A3.TP-26 3.5-1, 066 A, 2 Concrete (Inaccessible Areas): All Fire Barrier Flood Barrier Missile Barrier Shelter, Protection Structural Pressure Boundary Structural Support Concrete Plant Indoor Air (Structural) (Ext)

Cracking Structures Monitoring Program (B.2.3.33)

III.A3.TP-204 3.5-1, 043 A, 2

Enclosure Attachment A PG&E Letter DCL-25-023 Page 11 of 12 Supplement - DCPP LRA, Amendment 4 Table 3.5.2-3: Auxiliary Building - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Concrete (Inaccessible Areas): All Fire Barrier Flood Barrier Missile Barrier Shelter, Protection Structural Pressure Boundary Structural Support Concrete Plant Indoor Air (Structural) (Ext)

Cracking Structures Monitoring Program (B.2.3.33)

III.A3.TP-204 3.5-1, 043 A, 2

Enclosure Attachment A PG&E Letter DCL-25-023 Page 12 of 12 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.2.2 on page B.2-8 is revised as follows:

B.2.2.2 Environmental Qualification (EQ) of Electric Components

Enclosure Attachment B PG&E Letter DCL-25-023 Page 1 of 6 Supplement - DCPP LRA, Amendment 4 Attachment B: Saltwater and Chlorination System SSAMR and Makeup Water System SSAMR Affected LRA Sections: Section 3.2.2.2.3; Tables 3.2-1, 3.3.2-3, and 3.3.2-5 LRA Page Numbers: 3.2-7, 3.2-13, 3.3-112, 3.3-119, 3.3-122, 3.3-131, 3.3-152, 3.3-154, 3.3-156, 3.3-157, 3.3-160, 3.3-171, and 3.3-173 Description of Changes

1. To align aging management review tables with the Diablo Canyon Power Plant (DCPP) Bolting Integrity AMP (B.2.3.9) enhancement to inspect submerged bolting, LRA Tables 3.3.2-3 (Saltwater and Chlorination System) and 3.3.2-5 (Makeup Water System) are revised to include management of loss of material for stainless steel closure bolting exposed to water environments by the DCPP Bolting Integrity AMP (B.2.3.9). Plant-specific notes are added to reference NUREG-2191 item VII.I.A-423 as the basis for the changes.
2. LRA Table 3.3.2-3 is revised to remove the following row to reflect actual plant configuration: Copper Alloy (15% Zinc and 8% Aluminum) Piping, Piping Components with a pressure boundary intended function exposed to a plant indoor air external environment. The in-scope Copper Alloy (15% Zinc and 8%

Aluminum) Piping, Piping Components with a pressure boundary intended function are all underground, and therefore, are captured by an existing AMR line that credits the Buried and Underground Piping and Tanks AMP (B.2.3.26).

3. LRA Table 3.3.2-3 is revised to reflect replacement of the Pump Casing (Screen Refuse Pumps) identified as part of the annual update review. The previous pumps were carbon steel while the new pumps are stainless steel.
4. LRA Table 3.3.2-5 is revised to correct a valve material from stainless steel to carbon steel. This correction results in the deletion of the AMR line for Stainless Steel Valve Body with a pressure boundary intended function exposed to a plant indoor air external environment managed by the Buried and Underground Piping and Tanks AMP.
5. LRA Table 3.3.2-5 is revised to add new AMR lines for management of carbon steel and cast iron (gray cast iron) abandoned in place piping, piping components and valve bodies exposed to raw water (int) with the DCPP Inspection of Internal Surfaces of Miscellaneous Piping and Ducting Components (B.2.3.24).
6. LRA Table 3.3.2-5 is revised to update NUREG-1801 Items from V.D2.EP-107, 3.2-1, 004 to VII.C1.AP-221, 3.3-1, 006, to more closely align with the Makeup Water System being an Auxiliary System. Corresponding changes are made to LRA Section 3.2.2.2.3, item 2, and Table 3.2-1.

Enclosure Attachment B PG&E Letter DCL-25-023 Page 2 of 6 Supplement - DCPP LRA, Amendment 4 LRA Section 3.2.2.2.3 on page 3.2-7 is revised as follows:

3.2.2.2.3 Loss of Material due to Pitting and Crevice Corrosion

2.

Loss of material due to pitting and crevice corrosion could occur for stainless steel piping, piping components, piping elements, and tanks exposed to outdoor air. The possibility of pitting and crevice corrosion also extends to components exposed to air which has recently been introduced into buildings, i.e., components near intake vents. Pitting and crevice corrosion is only known to occur in environments containing sufficient halides (primarily chlorides) and in which condensation or deliquescence is possible. Condensation or deliquescence should generally be assumed to be possible. Applicable outdoor air environments (and associated indoor air environments) include, but are not limited to, those within approximately 5 miles of a saltwater coastline, those within 1/2 mile of a highway which is treated with salt in the wintertime, those areas in which the soil contains more than trace chlorides, those plants having cooling towers where the water is treated with chlorine or chlorine compounds, and those areas subject to chloride contamination from other agricultural or industrial sources. This item is applicable for the environments described above.

GALL AMP XI.M36, External Surfaces Monitoring, is an acceptable method to manage the aging effect. The applicant may demonstrate that this item is not applicable by describing the outdoor air environment present at the plant and demonstrating that external pitting or crevice corrosion is not expected. The GALL Report recommends further evaluation to determine whether an aging management program is needed to manage this aging effect based on the environmental conditions applicable to the plant and requirements applicable to the components.

As summarized in item 3.2-1, 004, there are no stainless steel piping, piping components, piping elements, or tanks exposed to atmosphere/weather in ESF Systemsloss of material of stainless steel piping and piping components exposed to atmosphere/weather is managed by the DCPP External Surfaces Monitoring of Mechanical Components AMP (B.2.3.22).

Enclosure Attachment B PG&E Letter DCL-25-023 Page 3 of 6 Supplement - DCPP LRA, Amendment 4 LRA Table 3.2-1 on page 3.2-13 is revised as follows:

Table 3.2-1: Summary of Aging Management Evaluations for the ESF Item Number Component Aging Effect/Mechanis m

Aging Management Programs Further Evaluation Recommended Discussion 3.2-1, 004 Stainless steel Piping, piping components, and piping elements; tanks exposed to Air -

outdoor Loss of material due to pitting and crevice corrosion Chapter XI.M36, "External Surfaces Monitoring of Mechanical Components"

Yes, environmental conditions need to be evaluated (See subsection 3.2.2.2.3.2)

Not applicable.

There are no stainless steel piping, piping components, piping elements, or tanks exposed to atmosphere/weather in ESF Systems.

Consistent with NUREG-1801.

Loss of material of stainless steel piping and piping components exposed to atmosphere/weather is managed by the DCPP External Surfaces Monitoring of Mechanical Components AMP (B.2.3.22).

Further evaluation is documented in Section 3.2.2.2.3, Item 2.

Enclosure Attachment B PG&E Letter DCL-25-023 Page 4 of 6 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-3 on pages 3.3-112, 3.3-119, 3.3-122, and 3.3-131 (as modified by DCL-24-092, Encl. 1, Att. D and J; DCL-25-001, Encl. 1, Att. A) is revised as follows:

Table 3.3.2-3: Saltwater and Chlorination System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Bolting (Closure)

Mechanical Closure Stainless Steel Raw Water (Ext) Loss of Material Bolting Integrity (B.2.3.9)

None None E, 7 Bolting (Closure)

Mechanical Closure Stainless Steel Raw Water (Ext) Loss of Preload Bolting Integrity (B.2.3.9)

VII.I.AP-264 3.3-1, 015 A

Piping, Piping Components Pressure Boundary Copper Alloy (15% Zinc and 8%

Aluminum)

Plant Indoor Air (Ext)

Loss of Material Buried and Underground Piping and Tanks (B.2.3.26)

VII.I.AP-284 3.3-1, 109x B, 1 Piping, Piping Components Pressure Boundary Copper Alloy (15% Zinc and 8%

Aluminum)

Plant Indoor Air (Ext)

None None VIII.I.SP-6 3.4-1, 054 A

Pump Casing (Screen Refuse Pumps)

Leakage Boundary (spatial)

Stainless SteelCarbon Steel Plant Indoor Air (Ext)

NoneLoss of Material NoneExternal Surfaces Monitoring of Mechanical Components (B.2.3.22)

VII.J.AP-17VII.I.A-77 3.3-1, 120078 A

Pump Casing (Screen Refuse Pumps)

Leakage Boundary (spatial)

Stainless SteelCarbon Steel Raw Water (Int) Loss of Material; Fouling Open Cycle Cooling Water System (B.2.3.11)

VII.C1.A-54VII.C1.AP-194 3.3-1, 040037 A

Plant-Specific Notes 7.

Consistent with the guidance in NUREG-2191 Item VII.I.A-423, loss of material for submerged bolting (in raw water) will be managed by the DCPP Bolting Integrity AMP (B.2.3.9).

f------

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Enclosure Attachment B PG&E Letter DCL-25-023 Page 5 of 6 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-5 on pages 3.3-152, 3.3-154, 3.3-156, 3.3-157, 3.3-160, 3.3-171, and 3.3-173 (as modified by DCL 092, Encl. 1, Att. D, E, and L) is revised as follows:

Table 3.3.2-5: Makeup Water System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Bolting (Closure)

Mechanical Closure Stainless Steel Demineralized Water (Ext)

Loss of Material Bolting Integrity (B.2.3.9)Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

NoneVIII.E.SP

-87 None3.

4-1, 016 E,

11C Bolting (Closure)

Mechanical Closure Stainless Steel Demineralized Water (Ext)

Loss of Preload Bolting Integrity (B.2.3.9) V.E.EP-122 3.2-1, 015 A

Piping, Piping Components Leakage Boundary (spatial)

Carbon Steel Raw Water (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

VII.C1.A-408 3.3-1, 134 B, 3 Piping, Piping Components Leakage Boundary (spatial)

Stainless Steel Atmosphere/

Weather (Ext)

Loss of Material External Surfaces Monitoring of Mechanical Components (B.2.3.22)

VII.C1.AP-221V.D2.EP-107 3.3-1, 0063.2-1, 004 A

Piping, Piping Components Pressure Boundary Stainless Steel Atmosphere/

Weather (Ext)

Loss of Material External Surfaces Monitoring of Mechanical Components (B.2.3.22)

VII.C1.AP-221V.D2.EP-107 3.3-1, 0063.2-1, 004 A

Piping, Piping Components Structural Integrity (attached)

Stainless Steel Atmosphere/

Weather (Ext)

Loss of Material External Surfaces Monitoring of Mechanical Components (B.2.3.22)

VII.C1.AP-221V.D2.EP-107 3.3-1, 0063.2-1, 004 A

Screen Filter Stainless Steel Atmosphere/

Weather (Ext)

Loss of Material External Surfaces Monitoring of Mechanical Components (B.2.3.22)

VII.C1.AP-221V.D2.EP-107 3.3-1, 0063.2-1, 004 A

Valve Body Leakage Boundary (spatial)

Carbon Steel Raw Water (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous VII.C1.A-408 3.3-1, 134 B, 3

Enclosure Attachment B PG&E Letter DCL-25-023 Page 6 of 6 Supplement - DCPP LRA, Amendment 4 Plant-Specific Notes 3.

Components are associated with the boric acid evaporator subsystem which is abandoned-in-place. Thus, aging of the components will be managed by the DCPP Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components AMP (B.2.3.24).

11.

Consistent with the guidance in NUREG-2191 Item VII.I.A-423, loss of material for submerged bolting (in treated water) will be managed by the DCPP Bolting Integrity AMP (B.2.3.9).

Table 3.3.2-5: Makeup Water System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Piping and Ducting Components (B.2.3.24)

Valve Body Leakage Boundary (spatial)

Cast Iron (Gray Cast Iron)

Raw Water (Int)

Loss of Material Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (B.2.3.24)

VII.C1.A-408 3.3-1, 134 B, 3 Valve Body Pressure Boundary Stainless Steel Plant Indoor Air (Ext)

Loss of Material Buried and Underground Piping and Tanks (B.2.3.26)

VII.I.AP-284 3.3-1, 109x B, 7

Enclosure Attachment C PG&E Letter DCL-25-023 Page 1 of 3 Supplement - DCPP LRA, Amendment 4 Attachment C: Control Room HVAC System SSAMR Affected LRA Sections: Section 3.3.2.1.10; Table 3.3.2-10 LRA Page Numbers: 3.3-12 and 3.3-275 Description of Change:

LRA Table 3.3.2-10 is revised to reflect a replaced valve. The previous valve body was stainless steel while the replacement valve body is polyvinyl chloride (PVC). AMR lines are added for PVC valve bodies. LRA Section 3.3.2.1.0 is revised with corresponding changes.

Enclosure Attachment C PG&E Letter DCL-25-023 Page 2 of 3 Supplement - DCPP LRA, Amendment 4 LRA Section 3.3.2.1.10 on page 3.3-12 is revised as follows:

3.3.2.1.10 Control Room HVAC Materials The materials of construction for the CRHVAC System components are:

x Carbon Steel x

Carbon Steel (Galvanized) x Copper Alloy ( 15% Zinc and 8% Aluminum) x Copper Alloy (> 15% Zinc) x Elastomer x Glass x

Polyvinyl Chloride (PVC) x Stainless Steel

Enclosure Attachment C PG&E Letter DCL-25-023 Page 3 of 3 Supplement - DCPP LRA, Amendment 4 LRA Table 3.3.2-10 on page 3.3-275 is revised as follows:

Table 3.3.2-10: Control Room HVAC System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Valve Body Structural Integrity (attached)

Polyvinyl Chloride (PVC)

Plant Indoor Air (Ext)

None None VII.J.AP-268 3.3-1, 119 A

Valve Body Structural Integrity (attached)

Polyvinyl Chloride (PVC)

Ventilation Atmosphere (Int)

None None VII.J.AP-269 3.3-1, 119 A

Enclosure Attachment D PG&E Letter DCL-25-023 Page 1 of 4 Supplement - DCPP LRA, Amendment 4 Attachment D: Auxiliary Steam System SSAMR Affected LRA Sections: Tables 2.3.4-2 and 3.4.2-2 LRA Page Numbers: 2.3-104, 3.4-88, and 3.4-89 Description of Change:

LRA Tables 2.3.4-2 and 3.4.2-2 are revised to reflect removal of the Boric Evap Condenser Sample Cooler and Building Heating Reboiler Sample Cooler from the plant.

Interfacing piping was cut and capped and remains in the scope of LR. These removals were identified as part of the annual update review.

Enclosure Attachment D PG&E Letter DCL-25-023 Page 2 of 4 Supplement - DCPP LRA, Amendment 4 LRA Table 2.3.4-2 on page 2.3-104 (as modified by DCL-24-092, Encl. 1, Att. Z) is revised as follows:

Table 2.3.4 Auxiliary Steam System Components Subject to Aging Management Review Component Type Component Intended Function Heat Exchanger (Auxiliary Steam Drain Receiver Pump Discharge Sample Cooler) Shell Side Components Leakage Boundary (Spatial)

Heat Exchanger (Auxiliary Steam Drain Receiver Pump Discharge Sample Cooler) Tube Side Components Leakage Boundary (Spatial)

Heat Exchanger (Boric Evap Condenser Sample Cooler) Shell Side Components Leakage Boundary (Spatial)

Heat Exchanger (Boric Evap Condenser Sample Cooler) Tube Side Components Leakage Boundary (Spatial)

Heat Exchanger (Building Heating Reboiler Sample Cooler) Shell Side Components Leakage Boundary (Spatial)

Heat Exchanger (Building Heating Reboiler Sample Cooler) Tube Side Components Leakage Boundary (Spatial)

Heat Exchanger (Building Heating Reboiler) Shell Side Components Leakage Boundary (Spatial)

Heat Exchanger (Building Heating Reboiler) Tube Side Components Leakage Boundary (Spatial)

Enclosure Attachment D PG&E Letter DCL-25-023 Page 3 of 4 Supplement - DCPP LRA, Amendment 4 LRA Table 3.4.2-2 on pages 3.4-88 and 3.4-89 is revised as follows:

Table 3.4.2-2: Auxiliary Steam System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Heat Exchanger (Boric Evap Condenser Sample Cooler) Shell Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Closed-Cycle Cooling Water (Int)

Loss of Material Closed Treated Water Systems (B.2.3.12)

VIII.E.SP-8 3.4-1, 027 D

Heat Exchanger (Boric Evap Condenser Sample Cooler) Shell Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Plant Indoor Air (Ext)

None None VIII.I.SP-6 3.4-1, 054 C

Heat Exchanger (Boric Evap Condenser Sample Cooler) Tube Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Plant Indoor Air (Ext)

None None VIII.I.SP-6 3.4-1, 054 C

Heat Exchanger (Boric Evap Condenser Sample Cooler) Tube Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Secondary Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VIII.A.SP-101 3.4-1, 016 C

Heat Exchanger (Building Heating Reboiler Sample Cooler) Shell Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Closed-Cycle Cooling Water (Int)

Loss of Material Closed Treated Water Systems (B.2.3.12)

VIII.E.SP-8 3.4-1, 027 D

Heat Exchanger (Building Heating Reboiler Sample Cooler) Shell Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Plant Indoor Air (Ext)

None None VIII.I.SP-6 3.4-1, 054 C

Heat Exchanger (Building Heating Leakage Boundary Copper Alloy (15% Zinc and Plant Indoor Air (Ext)

None None VIII.I.SP-6 3.4-1, 054 C

Enclosure Attachment D PG&E Letter DCL-25-023 Page 4 of 4 Supplement - DCPP LRA, Amendment 4 Table 3.4.2-2: Auxiliary Steam System - Summary of Aging Management Evaluation Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Item Table 1 Item Notes Reboiler Sample Cooler) Tube Side Components (spatial) 8% Aluminum)

Heat Exchanger (Building Heating Reboiler Sample Cooler) Tube Side Components Leakage Boundary (spatial)

Copper Alloy (15% Zinc and 8% Aluminum)

Secondary Water (Int)

Loss of Material Water Chemistry (B.2.3.2) and One-Time Inspection (B.2.3.19)

VIII.A.SP-101 3.4-1, 016 C

Enclosure Attachment E PG&E Letter DCL-25-023 Page 1 of 3 Supplement - DCPP LRA, Amendment 4 Attachment E: Reactor Coolant Pressure Boundary Piping TLAA Affected LRA Sections: Sections 4.3.2.7 and 4.9 LRA Page Numbers: 4.3-13 and 4.9-3 Description of Change:

As discussed in LRA Section 4.3.2.7, in 2018, Pacific Gas and Electric Company (PG&E) obtained NRC approval of an alternative for application of a full structural weld overlay (SWOL) for the residual heat removal suction pipe-to-elbow in Units 1 and 2.

The 2018 approval applied through the operating license dates of November 2, 2024, for Unit 1, and August 26, 2025, for Unit 2. In 2024, to address continued operations, PG&E requested NRC to extend the approval of the subject SWOLs to the end of the fifth 10-year inservice inspection (ISI) interval as an extension of alternative request REP-RHR-SWOL (ML24180A205).

In the 2024 safety evaluation (new LRA Reference 4.9.24), NRC confirmed the SWOL design, installation, and continued inspections provide reasonable assurance of SWOL structural integrity for the extended service life.

LRA Sections 4.3.2.7 and 4.9 are updated to provide NRC this additional information related to the SWOL TLAA. There were no changes to the design or analysis as part of the extension of alternative request REP-RHR-SWOL.

Enclosure Attachment E PG&E Letter DCL-25-023 Page 2 of 3 Supplement - DCPP LRA, Amendment 4 LRA Section 4.3.2.7 on page 4.3-13 is revised as follows:

4.3.2.7 Reactor Coolant Pressure Boundary Piping TLAA Evaluation Residual Heat Removal Suction Pipe-to-Elbow Structural Weld Overlays Full Alloy 52M (nickel alloy) structural weld overlays were completed on the Unit 1 suction pipe-to-elbow weld WIB-228 in 2019 and on the Unit 2 suction pipe-to-elbow weld WIB-245 in 2018, to provide long-term mitigation of future crack growth in the original stainless steel welds. The results of the inspection and repairs were reported to the NRC in letters DCL-18-050 (Reference ML18254A426) and DCL-19-054 (Reference ML19182A361). The weld overlays were designed to ASME Code,Section XI, Code Case N-740-2, as approved by NRC in 2018 and 2024 (References 4.9.11 and 4.9.24, respectively) for this specific application at DCPP. The overlays were supported by a fatigue analysis and crack growth analysis, both of which are TLAAs.

The weld overlays were analyzed for fatigue with a resulting CUF less than 1.0. The fatigue results qualify the overlays to the 50-year design basis number of transients as described in UFSAR Table 5.2-4 (see Table 4.3-1).

The crack growth analysis also uses the 50-year design basis number of transients as described in UFSAR Table 5.2-4 and indicates the allowable flaw depth will not be reached for the assumed number of transients.

Enclosure Attachment E PG&E Letter DCL-25-023 Page 3 of 3 Supplement - DCPP LRA, Amendment 4 LRA Section 4.9 on page 4.9-3 (as modified by DCL-24-092, Encl. 1, Att. PP) is revised as follows:

4.9 REFERENCES

4.9.11 US NRC Letter. From Robert J. Pascarelli, Chief, Plant Licensing Branch IV, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation; to Mr. Edward D. Halpin, Senior Vice President, Generation and Chief Nuclear Officer, DCPP. Diablo Canyon Power Plant, Units 1 and 2 - Relief Request REP-RHR-SWOL, Request for Approval of Alternative for Application of Full Structural Weld Overlay (EPID L-2017-LLR-0092). 2 January 2018. (ADAMS Accession No. ML17338A131).

4.9.24 Not Used.US NRC Letter. From Jennivine K. Rankin, Chief, Plant Licensing Branch IV, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation; to Adam Peck, Acting Chief Nuclear Officer and Senior Vice President, DCPP. Diablo Canyon Nuclear Power Plant, Units 1 and 2 - Authorization and Safety Evaluation for Alternative Request No. REP-RHR-SWOL (EPID L-2024-LLR-0043). 9 October 2024.

(ADAMS Accession No. ML24270A166).

Enclosure Attachment F PG&E Letter DCL-25-023 Page 1 of 2 Supplement - DCPP LRA, Amendment 4 Attachment F: Bolting Integrity AMP Affected LRA Sections: Section B.2.3.9 LRA Page Numbers: B.2-48 Description of Change:

LRA Section B.2.3.9 is revised to combine the Element 6 enhancement with LRA Table A-3, item 11(g) so these address both submerged bolting and piping systems that contain air or gas for which leakage is difficult to detect. This change aligns with NUREG-2191,Section XI.M18, Element 6, which is the source of the proposed enhancement.

Corresponding changes to the enhancement wording are made to LRA Table A-3, item 11(g), in Enclosure Attachment K.

Enclosure Attachment F PG&E Letter DCL-25-023 Page 2 of 2 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.3.9 on page B.2-48 (as modified by DCL-24-092, Encl. 1, Att. UU) is revised as follows:

B.2.3.9 Bolting Integrity Enhancements The DCPP Bolting Integrity AMP will be enhanced as follows, for alignment with NUREG-1801.

The enhancements will be implemented prior to November 2, 2024 and August 26, 2025 for Units 1 and 2, respectively.

Element Enhancement 6 - Acceptance Criteria DCPP-specific acceptance criteria will be established when alternative inspections or testing is conducted for submerged closure bolting or closure bolting where the piping systems that contain air or gas for which leakage is difficult to detect.

Enclosure Attachment G PG&E Letter DCL-25-023 Page 1 of 6 Supplement - DCPP LRA, Amendment 4 Attachment G: One-Time Inspection of ASME Code Class 1 Small Bore-Piping AMP Affected LRA Sections: Sections A.2.2.1, A.2.2.21, B.2.3.1, and B.2.3.21 LRA Page Numbers: A.2-2, A.2-11, B.2-12, B.2-104, and B.2-106 Description of Change:

LRA Section B.2.3.21 is revised to include inspection results from the One-Time Inspection of ASME Code Class 1 Small Bore-Piping AMP. In addition, the plant-specific operating experience (OE) is corrected to add an instance of 2022 socket weld indication. Corresponding changes are made to LRA Sections A.2.2.1, A.2.2.21, and B.2.3.1 and LRA Table A-3, item 3, (see Enclosure Attachment K) to augment the DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC, and IWD AMP during the period of extended operation (PEO).

Enclosure Attachment G PG&E Letter DCL-25-023 Page 2 of 6 Supplement - DCPP LRA, Amendment 4 LRA Section A.2.2.1 on page A.2-2 is revised as follows:

A.2.2.1 ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD The DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC, and IWD AMP is an existing AMP that manages cracking, loss of fracture toughness, and loss of material in Class 1, 2, and 3 piping and components within the scope of LR. The AMP includes periodic visual, surface, volumetric examinations, and leakage tests of Class 1, 2, and 3 pressure-retaining components, including welds, pump casings, valve bodies, vessels, integral attachments, and pressure-retaining bolting. This AMP is in accordance with the ASME Code Section XI Edition and Addenda approved in accordance with the provisions of 10 CFR 50.55a. The DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD AMP is augmented to perform periodic outside diameter inspection of the susceptible population of ASME Code Class 1 small-bore piping socket welds (10 percent with a maximum of 25 welds per Unit) in each ISI interval in the PEO.

Enclosure Attachment G PG&E Letter DCL-25-023 Page 3 of 6 Supplement - DCPP LRA, Amendment 4 LRA Section A.2.2.21 on page A.2-11 is revised as follows:

A.2.2.21 One-Time Inspection of ASME Code Class 1 Small Bore-Piping The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP is a new condition monitoring AMP that will augment the existing ASME Code,Section XI requirements.

The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP is applicable to small-bore ASME Code Class 1 piping and systems less than NPS 4 inches and greater than or equal to NPS 1 inch. The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP will perform one-time volumetric, opportunistic destruction examination, or another approved inspection of a sample of this Class 1 piping focused on full (butt) and partial penetration (socket) welds. The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP will include measures to verify that degradation is not occurring, thereby either confirming that there is no need to manage age-related degradation or validating the effectiveness of any existing AMP for the PEO. The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP will include locations that are susceptible to cracking and will be applicable to systems that have not experienced cracking of ASME Code Class 1 small-bore piping. The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP will also be applicable to systems that have experienced cracking but then implemented design changes to effectively mitigate cracking. Should evidence of cracking be revealed by a one-time inspection, the need for a periodic inspection will be addressed by the CAP and a new plant-specific AMP developed, as warranted. The DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD AMP is augmented to perform periodic outside diameter inspection of the susceptible population of ASME Code Class 1 small-bore piping socket welds (10 percent with a maximum of 25 welds per Unit) in each ISI interval in the PEO.

This new DCPP One-Time Inspection of ASME Code Class 1 Small-Bore AMP will be implemented prior to November 2, 2024 and August 26, 2025 for Units 1 and 2, respectively.

Industry and plant-specific OE will be evaluated in the development and implementation of this program.

Enclosure Attachment G PG&E Letter DCL-25-023 Page 4 of 6 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.3.1 on page B.2-12 is revised as follows:

B.2.3.1 ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD Enhancements The DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC, and IWD AMP will be enhanced as follows, for alignment with NUREG-1801. The enhancements areis to be implemented in accordance with the schedule provided in the Commitment Tableprior to November 2, 2024.

Element Enhancement 1 - Scope of Program Augment the program scope to include a plant specific small-bore piping outside diameter inspection of 10 percent of the susceptible ASME Code Class 1 socket weld population greater than or equal to NPS 1 inch and less than NPS 4 inches with a maximum of 25 welds per unit using visual and penetrant examinations in each ISI interval in the PEO.

7 - Corrective Actions Re-examine the Unit 1 Pressurizer Spray Line Pipe Weld WIB-378 for three ISI periods since identification of the weld flaw in 2015 in accordance with ASME Code, paragraph IWB-2420 for Successive Inspections as described in PG&E Letter DCL-16-043, response to NRC question 5. The first two exams showed the flaw as unchanged in size. If during the third successive exam the flaw has reached 50 percent through wall depth, PG&E will reanalyze the current acceptability and projected flaw growth rate for the remainder of the PEO and continue monitoring it on a periodic basis.

Enclosure Attachment G PG&E Letter DCL-25-023 Page 5 of 6 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.3.21 on pages B.2-104 and B.2-106 is revised as follows:

B.2.3.21 One-Time Inspection of ASME Code Class 1 Small Bore-Piping Program Description The one-time inspections will be completed prior to November 2, 2024 and August 26, 2025 for Units 1 and 2 respectively. Evaluation of the inspection results may indicate the need for additional or periodic examinations and may warrant development of a new plant-specific AMP.

As discussed in the OE section below, evaluation of the one-time inspection results led to augmentation of the DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD AMP to perform periodic outside diameter inspection of the susceptible population of ASME Code Class 1 small-bore piping socket welds (10 percent with a maximum of 25 welds per Unit) in each ISI interval in the PEO.

Operating Experience Plant Specific Operating Experience A recent DCPP OE search was performed for LR which covered a date range of March 1994 through February 2023. The results of the DCPP OE search did not identifiedy one applicable 2022 instanceexamples of cracking in ASME Code Class 1 small-bore piping greater than or equal to NPS 1 inch and less than NPS 4 inches. The DCPP OE search did further identifiedy the followingtwo examples from 1994 that demonstrate ASME Code Class 1 piping deficiencies are entered into the corrective action program and appropriate actions are taken to evaluate and correct the deficiencies, including performing extent of condition evaluations as necessary.

x In 1994, a cracked weld coupling on a pressurizer level instrument capillary fill line (less than NPS 1 inch) was identified. It was determined that the crack was due to a lack of fusion in the tubing weld and previous metal removal resulting in fatigue cracking. The corrective action was to install new tubing.

x In 1994, an excess letdown piping reducer segment socket weld showed a crack indication. The evaluation determined that the likely cause was due to inter-granular stress corrosion cracking caused by sensitization of the base metal as a result of the initial welding process. Further review concluded that this stress corrosion crack occurred on the ASME Class 2 portion of the piping. The corrective action was to replace the piping and use a fatigue-resistant weld, which is considered a design change to mitigate cracking.

x In 2022, a through-wall indication was identified on a RCS loop cold leg vacuum refill piping socket weld. The cause of the degradation was vibration-induced fatigue propagation of a flaw initiated at a weld defect. Corrective actions consisted of a design change to reconfigure the piping to increase fatigue margin. Extent of condition examinations were performed on similar welds and did not identify any weld cracking indications.

Enclosure Attachment G PG&E Letter DCL-25-023 Page 6 of 6 Supplement - DCPP LRA, Amendment 4 In 2024, during implementation of this AMP, a flaw was identified on the exterior of a Unit 2 RCP injection seal line socket weld. The weld was removed, and destructive examination identified the flaw was caused by SCC on the outside diameter of the pipe. Extent of condition examinations were performed on seven similar welds with no weld cracking indications identified. PG&E is augmenting the DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD AMP to perform periodic outside diameter inspection of the susceptible population of ASME Code Class 1 small-bore piping socket welds (10 percent with a maximum of 25 welds per Unit) in each ISI interval in the PEO.

The DCPP OE provides objective evidence that the measures in place to monitor cracking of ASME Code Class 1 small-bore piping have been effective. These examples also demonstrate that ASME Code Class 1 piping deficiencies are entered into the CAP and appropriate actions are taken to evaluate the deficiencies, determine their cause, and correct them.

AMP effectiveness will be assessed at least every five years per NEI 14-12.

The DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping 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 periodically evaluated.

Enclosure Attachment H PG&E Letter DCL-25-023 Page 1 of 4 Supplement - DCPP LRA, Amendment 4 Attachment H: Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements AMP Affected LRA Sections: Sections A.2.2.38 and B.2.3.38 LRA Page Numbers: A.2-19, A.2-20, B.2-173 through B.2-176, and B.2-179 Description of Change:

LRA Sections A.2.2.38 and B.2.3.38 are revised to clarify that the pre-PEO pull box inspections are baseline inspections with recurring inspections occurring in the PEO via the DCPP Structures Monitoring AMP (B.2.3.33). In addition, the plant-specific OE in LRA Section B.2.3.38 is updated to add new examples of recent pull box sump pump performance deficiencies and associated corrective actions.

A corresponding change to the enhancement wording is made to LRA Table A-3, item 40(c) in Enclosure Attachment K.

Enclosure Attachment H PG&E Letter DCL-25-023 Page 2 of 4 Supplement - DCPP LRA, Amendment 4 LRA Section A.2.2.38 on pages A.2-19 and A.2-20 is revised as follows:

A.2.2.38 Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements A one-timebaseline inspection of pull boxes, including cables and cable support structures, will be performed prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively, with periodic and opportunistic inspections via the DCPP Structures Monitoring AMP (A.2.2.33) during the PEOand will include inspection of cables and cable support structures. The frequency of inspections may increase and repair/replacement may be implemented as determined by the plant corrective action program if adverse conditions are identified. The cables and cable support structures associated with the intake structure pull boxes will be inspected prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively, and every refueling outage thereafter.

Enclosure Attachment H PG&E Letter DCL-25-023 Page 3 of 4 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.3.38 on pages B.2-173 through B.2-176 and B.2-179 (as modified by DCL-24-092, Encl. 1, Att. LLL) is revised as follows:

B.2.3.38 Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Program Description A one-timebaseline inspection of pull boxes, including cables and cable support structures, will be performed prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively.,

which will include inspection of cables and cable structures Periodic and opportunistic inspections will be conducted via the DCPP Structures Monitoring AMP (B.2.3.33) during the PEO. The frequency of inspections may increase and repair/replacement may be implemented as determined by the plant corrective action program if adverse conditions are identified. The intake structure pull boxes are inspected prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively, and every refueling outage thereafter.

Exceptions to NUREG-1801 Exception 1 to Element 2, Preventive Actions Exception is taken to the Preventive Action element for annual direct observation of cables and cable supports: The periodic inspections of pull boxes for water accumulation will ensure the cables, splices, and cable supports are not submerged. However, these inspections will not include direct inspection of accessible cable conduit ends or direct inspection of cables and cable support structures. Instead, a one-timebaseline inspection of pull boxes will be performed prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively, which will include inspection for excessive drooping or sagging of cables and for visible indications of damage or degradation to cables and cable supports. Further, periodic and opportunistic inspections will be conducted via the DCPP Structures Monitoring AMP (B.2.3.33) during the PEO. The frequency of inspections may increase and repair/replacement may be implemented as determined by the plant corrective action program if adverse conditions are identified during the one-time inspection.

Justification for Exception Justification for Exception 1 The in-scope electrical pull boxes between the intake structure and turbine building are designed with drain conduits that drain to pull boxes at the intake and turbine building. The end pull boxes drain to a building sump or to an in-ground drain sump, which is separate from the pull boxes. The in-ground drain sump has an automatic sump pump and high-level alarm, which provides indication of pump failure before water in the sump backs up into pull boxes. The pull box sump pump and alarm features are tested annually prior to the rainy season. The DCPP pull box layout and sump pumps minimize the potential for submergence of cables, splices, and cable supports. The periodic pull box water inspections and dewatering system further reduce the potential for submergence of cables and cable support structures and reduce the potential for cable degradation. Review of DCPP OE did not identify adverse trends

Enclosure Attachment H PG&E Letter DCL-25-023 Page 4 of 4 Supplement - DCPP LRA, Amendment 4 of cable degradation. Hence periodic annual inspections consisting of direct observation of cables, cable support structures, and accessible conduit ends are not necessary. Any degradation of cables and cable support structures are expected to be detected during the pre-PEO baselineone-time and periodic and opportunistic inspections of pull boxes in the PEO, which will prompt repair/replacement of cables and cable supports and more frequent inspections of cables and cable supports as determined by the plant corrective action program.

Furthermore, engineering evaluation will be conducted if cables are found to be submerged in pull boxes to assess the impact of submergence on cable degradation and determine the cause of water accumulation, including any potential drain conduit blockage with appropriate corrective actions taken.

Enhancements The DCPP Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements AMP will be enhanced as follows, for alignment with NUREG-1801.

The enhancements are to be implemented prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively.

Element Enhancement 2 - Preventive Actions A baselineone-time inspection of pull boxes will be performed prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively, which will include inspections for excessive drooping or sagging of cables, and visible indications of damage or degradation of cables and cable supports.

Operating Experience Plant Specific Operating Experience From its OE review, PG&E found examples where water accumulation in pull boxes was identified and corrective actions were taken, such as dewatering and initiating requests for evaluations when required by procedures. Examples include instances iIn 2018 and 2024, two where pull boxes were identified with higher than expected water level due to.

An engineering evaluation was performed, which determined the cause was less than adequate performance of the sump pumps in a downstream pull box. Corrective actions were taken to pump out water, restore sump pump performance through maintenance or pump motor replacement, and enhance personnel response time to sump pump alarmsresulted in replacing the affected sump pump/motor and float switch. No recurrence of this issue was noticed during the operating experience search. The annual sump pump testing conducted prior to the rainy season will continue to identify any sump pump inadequacies prior to long-term wetting of cables.

Enclosure Attachment I PG&E Letter DCL-25-023 Page 1 of 3 Supplement - DCPP LRA, Amendment 4 Attachment I: Buried and Underground Piping and Tanks AMP Affected LRA Sections: Section B.2.3.26 LRA Page Numbers: B.2-125 Description of Change:

In the justification for Exception 1 in LRA Section B.2.3.26, PG&E cites the OE review discussed in DCL-16-032 (Reference ML16141A837) for the 10 years prior to 2016, and the subsequent post-2016 OE review, which concluded that no externally degraded conditions occurred that would not have met the acceptable criteria of this AMP. These conclusion statements in the justification for Exception 1 in LRA Section B.2.3.26 are revised to clarify the installed auxiliary saltwater system cathodic protection (CP) survey results are the only aspect that did not meet AMP acceptance criteria (i.e., -850mV relative to a copper/copper sulfate reference electrode, instant off). The conclusion statements remain accurate regarding findings for age-managed components in that no externally degraded conditions occurred that would not have met the acceptable criteria of this AMP. This historical CP performance informs the sample size requirements consistent with LR-ISG-2015-01, Appendix B, Table XI.M41-2.

Enclosure Attachment I PG&E Letter DCL-25-023 Page 2 of 3 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.3.26 on page B.2-125 (as modified by DCL-24-092, Encl. 1, Att. DDD) is revised as follows:

B.2.3.26 Buried and Underground Piping and Tanks Exceptions to NUREG-1801 Exception 1: Element 2, Preventive Actions The DFOSTs, makeup water cast iron valves, and some of the buried steel discharge and supply piping in the ASW system, do not have cathodic protection as recommended by LR-ISG-2015-01 Table XI.M41-1.

Justification for Exception Justification for Exception 1:

The buried DFOSTs are double walled steel with the exterior surface wrapped in a corrosion resistant fiberglass reinforced plastic. Due to the tanks being double walled, the internal pressure boundary wall is not subject to the aging effects from the tanks being buried. The tanks are equipped to monitor the space between the inner and outer walls for leakage. Per LR-ISG-2015-01 Appendix B Section 4.f, double wall tanks may be examined by monitoring the annular space for leakage. DCPP Procedures provide direction to drain, clean, and visually inspect the inside of both storage tanks at least every ten years. As noted in the program enhancements, PG&E has committed to installing cathodic protection on portions of the buried steel auxiliary saltwater piping no later than December 1, 2028. This 5-year window (December 2023 through December 2028) allows for design change package development and adequate planning and scheduling around and within outage windows to ensure effective and safe implementation. For the entire length of buried ASW supply and discharge piping, approximately 5,960 feet will be cathodically protected and a total of approximately 24 feet of piping will not be cathodically protected. DCL-16-032 (Reference ML16141A837) provides the results of soil resistivity testing performed in the vicinity of the ASW supply and discharge piping. The soil closest to the turbine building was characterized as corrosive since the resistivity was less than 1000 ohm-cm; however, the ASW supply and discharge piping is coated with a fiber wrapped petroleum-based epoxy coating providing substantial external corrosion protection for those short portions where CP is technically infeasible. DCL-16-032 (as updated by a 2024 CP evaluation) also provides a review of OE that was conducted for the 10 years prior to 2016, which concluded that, except for CP, no externally degraded conditions occurred that would not have met the acceptable criteria of this AMP. In addition, an OE search was performed which included the time period afterEvaluations of OE since 2016, concluded that, except for CP, did not identify anyno degraded conditions occurred that would not have met the acceptance criteria of this AMP for any components with similar materials, coating systems, and soil environments (including components that are not in scope of LR). Non-cathodically protected buried steel (including cast iron makeup water valves) will be inspected in accordance with LR-ISG-2015-01, Appendix B, Table XI.M41-2, Preventive Action Category F, as follows: (1) extent of inspection for the coated pipe will be 10 percent of the piping length with a maximum of 6 locations (each location being a 10-foot length of pipe), as defined in XI.M41, Section 4.c; (2) inspections

Enclosure Attachment I PG&E Letter DCL-25-023 Page 3 of 3 Supplement - DCPP LRA, Amendment 4 of valves will be 10 percent of the valves, with a maximum of 6 valves, where the entire valve surface in contact with soil will be inspected.

Enclosure Attachment J PG&E Letter DCL-25-023 Page 1 of 2 Supplement - DCPP LRA, Amendment 4 Attachment J: Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP Affected LRA Sections: Section B.2.3.42 LRA Page Numbers: B.2-192 and B.2-193 Description of Change:

The LRA Section B.2.3.42 Program Description and Element 1 are revised to clarify the scope of the DCPP Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP is up to (not inclusive of) switchyard breakers 532/632 and 542/642. The breakers are active components and, therefore, do not require aging management review.

Enclosure Attachment J PG&E Letter DCL-25-023 Page 2 of 2 Supplement - DCPP LRA, Amendment 4 LRA Section B.2.3.42 on pages B.2-192 and B.2-193 is revised as follows:

B.2.3.42 Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators Program Description The scope of the DCPP Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP is an existing AMP that includes the 230 kV and 500 kV components required for SBO recovery. The 230 kV components include the overhead transmission conductors and connections from the unit startup transformers to disconnects 217 and 219, the 230 kV high-voltage insulators, and the switchyard bus and connections between disconnects 217 and 219. The 500 kV components include the overhead transmission conductors and connections from the main transformers to disconnects 533/631 and 543/641, the 500 kV high-voltage insulators, and the switchyard bus and connections 533/631 and 543/641 and up to switchyard breakers 532/632 and 542/642.

Element 1 - Scope of Program The scope of the DCPP Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP includes the 230 kV and 500 kV components required for SBO recovery.

The 230 kV components include the overhead transmission conductors and connections from the unit startup transformers to disconnects 217 and 219, the 230 kV high-voltage insulators, and the switchyard bus and connections between disconnects 217 and 219.

The 500 kV components include the overhead transmission conductors and connections from the main transformers to disconnects 533/631 and 543/641, the 500 kV high-voltage insulators, and the switchyard bus and connections 533/631 and 543/641 and up to switchyard breakers 532/632 and 542/642.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 1 of 48 Supplement - DCPP LRA, Amendment 4 Attachment K: LR Commitment Updates Affected LRA Sections: Table of Contents, Appendix A Cover Page, and Table A-3 LRA Page Numbers: 18, A-1, and A.4-1 through A.4-37 Description of Change:

1. LRA Table A-3 is updated with the implementation status for each commitment as of February 4, 2025. A revised due date is added for LRA Table A-3, item 17(h).
2. The LRA Table of Contents and Appendix A Cover Page are revised for alignment with the remainder of the LRA terminology for the Updated Final Safety Analysis Report.
3. LRA Table A-3, item 3, is revised to augment the DCPP ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD AMP to perform periodic inspection of the susceptible population of ASME Code Class 1 small-bore piping in the PEO.

Corresponding changes are made in Enclosure Attachment G.

4. LRA Table A-3, item 11(g), is revised to combine with the Element 6 enhancement so these address both submerged bolting or closure bolting where the piping systems that contain air or gas for which leakage is difficult to detect. This change aligns with NUREG-2191,Section XI.M18, Element 6, which is the source of the proposed enhancement. Corresponding changes are made in Enclosure Attachment F.
5. In DCL-24-092, Enclosure 1, Attachment HHH, PG&E revised LRA Section B.2.3.33 since it was a duplicative of another enhancement: In addition, specify the acceptance criteria for sliding surfaces are no indications of excessive loss of material due to corrosion or wear and no debris or dirt that could restrict or prevent sliding of the surfaces as required by design.

LRA Table A-3, item 35(e), was also updated to remove this same wording; however, it should have been retained since it was not duplicative in the table. Therefore, PG&E revises LRA Table A-3, item 35(e) to add in the previously deleted wording.

6. In DCL-25-001, Enclosure 1, Attachment A, PG&E revised LRA Table A-3, item 35, to add new item (t). The implementation schedule for LRA Table A-3, item 35, is revised to clarify the item (t) due date was January 30, 2025.
7. LRA Table A-3, item 40(c), is revised to clarify pre-PEO inspections are baseline.

Corresponding changes are made in Enclosure Attachment H.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 2 of 48 Supplement - DCPP LRA, Amendment 4 LRA Table of Contents on page 18 is revised as follows:

LIST OF APPENDICES Appendix A Updated Final Safety Analysis Report Supplement Appendix B Aging Management Programs Appendix C Additional Plant-Specific Information (Optional)

Appendix D Technical Specification Changes Appendix E Applicants Environmental Report

Enclosure Attachment K PG&E Letter DCL-25-023 Page 3 of 48 Supplement - DCPP LRA, Amendment 4 LRA Appendix A cover page on page A-1 is revised as follows:

APPENDIX A UPDATED FINAL SAFETY ANALYSIS REPORT SUPPLEMENT DIABLO CANYON POWER PLANT UNITS 1 & 2 LICENSE RENEWAL APPLICATION

Enclosure Attachment K PG&E Letter DCL-25-023 Page 4 of 48 Supplement - DCPP LRA, Amendment 4 LRA Table A-3 on pages A.4-1 through A.4-37 (as modified by DCL-24-092, Encl. 1, Att. M, PP, UU, VV, XX through III, KKK, LLL, NNN, and OOO; DCL-25-001, Encl. 1, Att. A; and DCL-25-022, Encl. Att. A) is revised as follows:

No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule 1

Fatigue Monitoring (A.2.1.1)

X.M1 Continue the existing DCPP Fatigue Monitoring AMP, including enhancements to:

(a) The AMP will be modified to include additional analyses and critical thermal and pressure transients for components that have been identified to have a fatigue TLAA, which are not covered by the current Fatigue Monitoring program. Additional locations will also include EAF analyses for the set of sample components from NUREG/CR-6260, Revision 0, and those components evaluated and determined to be more limiting than the components specified in NUREG/CR-6260 based on the methodology in EPRI Report 3002018262, Environmentally Assisted Fatigue Screening Methods.

(b) The AMP will be modified to include acceptance criteria for transient definitions, cycle count action limits, and CUF/CUFen action limits, which will invoke appropriate corrective actions if a component reaches a cycle count action limit or a CUF/CUFen action limit. Action limits permit completion of corrective actions before the design limits are exceeded.

(c) The procedures governing the DCPP Fatigue Monitoring AMP will be modified to specify the frequency of periodic reviews of the monitored cycle count and cumulative usage factor data at least once per fuel cycle. This review will determine whether fatigue analyses updates are needed if (a) an allowable cycle limit is approached, (b) where a transient definition has been changed, (c) 11/02/2024 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 5 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule unanticipated new thermal events are discovered, or (d) the geometry of components has been modified.

(d) The procedures governing the DCPP Fatigue Monitoring AMP will be revised to include appropriate corrective actions if a component reaches a cycle count action limit or a fatigue usage action limit.

The corrective action options for a component that has reached action limits include a revised fatigue analysis or repair or replacement of the component. Corrective actions for approaching fatigue crack growth analysis action limits include re-analyzing the fatigue crack growth analysis consistent with or reconciled to the originally submitted analysis. The reanalysis will receive the same level of regulatory review as the original analysis.

2 Environmental Qualification of Electric Components (A.2.1.2)

X.E1 Continue the existing DCPP Environmental Qualification of Electric Components AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 3 ASME Section XI Inservice Inspection, Subsections IWB, IWC, and IWD (A.2.2.1)

XI.M1 Continue the existing DCPP ASME Section XI, Subsection IWB, IWC, and IWD AMP, including an enhancement to:

(a) Re-examine the Unit 1 Pressurizer Spray Line Pipe Weld WIB-378 for three ISI periods since identification of the weld flaw in 2015 in accordance with ASME Code, paragraph IWB-2420 for Successive Inspections as described in PG&E Letter DCL-16-043, response to NRC question 5. The first two examsshowed the flaw as unchanged in size. If during the third successive exam the flaw has reached 50 percent through wall depth, PG&E will reanalyze Except for item (b),

enhancements are implemented by 11/02/2024 (Complete)

Enhancement (b) is implemented by 08/26/2025.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 6 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule the current acceptability and projected flaw growth rate for the remainder of the PEO and continue monitoring it on a periodic basis.

(b) Augment the program scope to include a plant specific small-bore piping outside diameter inspection of 10 percent of the susceptible ASME Code Class 1 socket weld population greater than or equal to NPS 1 inch and less than NPS 4 inches with a maximum of 25 welds per unit using visual and penetrant examinations in each ISI interval in the PEO.

4 Water Chemistry (A.2.2.2)

XI.M2 Continue the existing DCPP Water Chemistry AMP.

Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete) 5 Reactor Head Closure Stud Bolting (A.2.2.3)

XI.M3 Continue the existing DCPP Reactor Head Closure Stud Bolting AMP, including an enhancement to:

(a) Ensure the actual measured yield strength of replacement reactor head closure stud material purchased in the future is limited to

<150ksi.

11/02/2024 (Complete) 6 Boric Acid Corrosion (A.2.2.4)

XI.M10 Continue the existing DCPP Boric Acid Corrosion AMP.

Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete) 7 Cracking of Nickel-Alloy Components and Loss of XI.M11B Continue the existing Cracking of Nickel-Alloy Components and Loss of Material Due to Boric Acid-Induced Corrosion in Reactor Coolant Pressure Boundary Components AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 7 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule Material Due to Boric Acid-Induced Corrosion in Reactor Coolant Pressure Boundary Components AMP (A.2.2.5) 8 Thermal Aging Embrittlement of Cast Austenitic Stainless Steel (A.2.2.6)

XI.M12 Implement the new DCPP Thermal Aging Embrittlement of Cast Austenitic Stainless Steel AMP.

11/02/2024 (Complete) 9 PWR Vessel Internals (A.2.2.7)

XI.M16A Implement the new DCPP PWR Vessel Internals AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 10 Flow-Accelerated Corrosion (A.2.2.8)

XI.M17 Continue the existing DCPP Flow-Accelerated Corrosion AMP, including enhancements to:

(a) Include piping, piping components, and piping elements that are susceptible to erosion wall-thinning mechanisms such as cavitation, flashing, droplet impingement, or solid particle impingement and include erosion as an aging mechanism for all components that are susceptible. This will include guidelines for measuring wall thickness due to erosion during the PEO.

(b) Ensure that identification of locations susceptible to erosion is based on the extent of condition reviews from corrective actions in 11/02/2024 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 8 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule response to plant-specific and industry OE. Components may be treated in a manner similar to susceptible-not-modeled lines discussed in NSAC-202L. Additionally, include guidance from EPRI 1011231 for identifying potential damage locations and EPRI TR-112657 and/or NUREG/CR-6031 (April 1993) guidance for cavitation erosion.

(c) Include trending of wall thickness measurements at locations susceptible to erosion mechanisms to adjust the monitoring frequency and to predict the remaining service life of the component for scheduling repairs or replacements. Inspection results will be evaluated to determine if assumptions in the extent-of-condition review remain valid. If degradation is associated with infrequent operational alignments, such as surveillances or pump starts/stops, then trending activities may consider the number or duration of these occurrences. The program will be enhanced to consider periodic wall thickness measurements of replacement components, which would continue until the effectiveness of corrective actions has been confirmed.

(d) Ensure that updates to the plant predictive models are controlled and independently reviewed by a second qualified flow-accelerated corrosion engineer, consistent with NSAC-202L recommendations.

(e) For erosion mechanisms, ensure long-term corrective actions to eliminate the cause will consider adjusting operating parameters or changing component designs, and the effectiveness of these corrective actions will be verified. Periodic monitoring activities should continue for any components replaced with an alternate material, since a material that is completely erosion resistant is not

Enclosure Attachment K PG&E Letter DCL-25-023 Page 9 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule available.

11 Bolting Integrity (A.2.2.9)

XI.M18 Implement the existing DCPP Bolting Integrity AMP, including enhancements to:

(a) Procedures and/or specifications will be enhanced to minimize any future use of bolting material greater than 2 inches (i.e., not spare components currently on site) with an actual yield strength greater than or equal to 150 ksi in portions of systems within the scope of the Bolting Integrity program. If bolting greater than 2 inches with an actual yield strength greater than or equal to 150 ksi is used (including bolting with an unknown actual yield strength with the potential to be greater than or equal to 150 ksi), bolting will be monitored for cracking, with volumetric examinations performed in accordance with ASME Code Section XI, Table IWB-2500-1, Examination Category B-G-1.Specified bolting material properties (e.g., design and procurement specifications, fabrication and vendor drawings, material test reports) may be used to determine if identified bolting exceeds the threshold to be classified as high strength.

(b) Explicitly ban the use of MoS2 as a lubricant for use on bolts.

(c) DCPP Bolting Integrity AMP implementing procedures will be enhanced to incorporate the applicable guidance of EPRI NP-5769, EPRI Report 104213, and the additional recommendations of NUREG-1339 (June 1990) to prevent or mitigate degradation and failure of closure bolting.

(d) Perform inspections during the PEO of pressure retaining closure bolting in piping systems that contain air or gas for which leakage Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 10 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule is difficult to detect. Integrity of the bolted joint will be demonstrated by one of the following methods: (a) inspections are performed consistent with that of submerged closure bolting; (b) a visual inspection for discoloration is conducted when leakage of the air or gas inside the piping systems would discolor the external surfaces; (c) monitoring and trending of pressure decay is performed when the bolted connection is located within an isolated boundary; (d) soap bubble testing is performed; (e) when the temperature of the fluid is higher than ambient conditions, thermography testing is performed; or (f) inspection methods capable of detecting leakage for systems containing air or gas. At a minimum, in each 10-year interval during the PEO, inspections shall be completed on a representative sample of at least 20 percent of the population of bolt heads and threads (defined as bolts with the same material and environmental combination) at each unit, up to a maximum of 19 for each unit, for each material/environment combination.

(e) Ensure that submerged closure bolting is visually inspected for loss of material during PEO maintenance activities. Bolt heads will be inspected when made accessible, and bolt threads will be inspected when joints are disassembled. In each 10- year period during the PEO, a representative sample of bolt heads and threads will be inspected. If opportunistic maintenance activities will not provide access to 20 percent of the population (for a material/environment combination) up to a maximum of 19 bolt heads and threads over a 10-year period, then it will be documented how integrity of the bolted joint will be demonstrated.

For example: (a) periodic pump vibration measurements are taken and trended; or (b) sump pump operator walkdowns are performed

Enclosure Attachment K PG&E Letter DCL-25-023 Page 11 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule demonstrating that the pumps are appropriately maintaining sump levels.

(f) Deleted.

(g) DCPP-specific acceptance criteria will be established when alternative inspections or testing is conducted for submerged closure bolting or closure bolting where the piping systems contain air or gas for which leakage is difficult to detect.

(h) For sampling-based inspections, if the cause of the aging effect for each applicable material and environment is not corrected by repair or replacement for all components constructed of the same material and exposed to the same environment, additional inspections will be conducted if the results for one of the inspections does not meet acceptance criteria. The number of increased inspections will be determined in accordance with the DCPP CAP; however, there will be no fewer than five additional inspections for each inspection result that did not meet acceptance criteria, or 20 percent of each applicable material, environment, and aging effect combination will be inspected, whichever is less.

If the results of subsequent inspections do not meet acceptance criteria, an extent of condition and extent of cause analysis will be conducted to determine the further extent of inspections.

Additional samples will be inspected for any recurring degradation to ensure corrective actions appropriately address the associated causes. Additional inspections will include inspections at both units with the same material, environment, and aging effect combination. The additional inspections will be completed within the interval (e.g., refueling outage interval, 10-year inspection interval) in which the original inspection was conducted. If any projected inspection results will not meet acceptance criteria prior

Enclosure Attachment K PG&E Letter DCL-25-023 Page 12 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule to the next scheduled inspection, sampling frequencies will be adjusted as determined by DCPPs CAP.

12 Steam Generators (A.2.2.10)

XI.M19 Continue the existing DCPP Steam Generators AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 13 Open-Cycle Cooling Water AMP (A.2.2.11)

XI.M20 Continue the existing DCPP Open-Cycle Cooling Water System AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 14 Closed Treated Water Systems (A.2.2.12)

XI.M21A Continue the existing DCPP Closed Treated Water Systems AMP, including enhancements to:

(a) Include corrosion monitoring of CCW, SCW, and ICW system components by inspecting the condition of corrosion coupons installed in the CCW, SCW, and ICW systems. These methods will verify that wetted material exposed to the chemistry of the closed cooling water systems are not experiencing corrosion. The corrosion coupons are strips of metal (i.e., copper, carbon steel, stainless steel, etc.) that are installed in the closed cooling water systems in a manner such that they are exposed to the cooling water. Periodically these coupons will be removed and their condition will be evaluated. This inspection will provide DCPP an indication if significant corrosion is occurring in the system. Plant procedures will be enhanced to include inspections, guidelines, and acceptance criteria.

(b) For those components that do not have material represented by Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

I ________

I ________

I

Enclosure Attachment K PG&E Letter DCL-25-023 Page 13 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule the corrosion coupons, enhance procedures to include visual inspection of surfaces exposed to the closed treated water environment for evidence of loss of material, cracking, or fouling whenever the system boundary is opened. At a minimum, in each 10-year period during the PEO, a representative sample (20 percent of the population, up to a maximum of 25 components) of piping and components that do not have material represented by the corrosion coupons will be inspected by qualified personnel using visual or volumetric techniques capable of detecting loss of material, cracking, and fouling, as appropriate. The representative sample will be selected based on the likelihood of corrosion or cracking. Inspections will be conducted in accordance with applicable ASME code requirements. If there are no ASME code requirements, such as for SCW components, inspections will be conducted in accordance with the EPRI guideline. Guidance will be included to report and evaluate any detectable loss of material, cracking, or fouling associated with the surfaces exposed to the closed treated water environment per the DCPP CAP.

Components will meet system design requirements, such as minimum wall thickness. If visual examination identifies adverse conditions, additional examinations, including ultrasonic testing, are to be conducted. Inspection results will be trended so that the progression of any corrosion or cracking can be evaluated and predicted.

15 Inspection of Overhead Heavy Load and Light Load (Related to Refueling)

XI.M23 Continue the existing DCPP Inspection of Overhead Heavy Load and Light Load (Related to Refueling) Handling Systems AMP, including enhancements to:

(a) Enhance applicable procedures to specify visual inspections for loose bolts, missing or loose nuts, or other indications of loss of 11/02/2024 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 14 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule Handling Systems (A.2.2.13) preload and cracking for bolted connections of the containment dome service crane.

(b) Enhance applicable procedures to specify that visual inspection frequencies are in accordance with ASME B30.2, Overhead and Gantry Cranes (Top Running Bridge, Single or Multiple Girder, Top Running Trolley Hoist), American Society of Mechanical Engineers, 2005 Edition, or other ap propriate standards in the ASME B30 series.

(c) Enhance applicable procedures to specify that all visual indications of aging are evaluated for associated system/component adjustment, repair, or replacement, as necessary, in accordance with ASME B30.2, Overhead and Gantry Cranes (Top Running Bridge, Single or Multiple Girder, Top Running Trolley Hoist),

American Society of Mechanical Engineers, 2005 Edition, or other appropriate standards in the ASME B30 series.

(d) Enhance applicable procedures to specify that system/component repairs are performed in accordance with ASME B30.2, Overhead and Gantry Cranes (Top Running Bridge, Single or Multiple Girder, Top Running Trolley Hoist), American Society of Mechanical Engineers, 2005 Edition, or other appropriate standards in the ASME B30 series.

16 Fire Protection (A.2.2.14)

XI.M26 Continue the existing DCPP Fire Protection AMP, including an enhancement to:

(a) Include qualification criteria for individuals performing inspection of fire dampers and fire doors.

11/02/2024 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 15 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule 17 Fire Water Program (A.2.2.15)

XI.M27 Continue the existing DCPP Fire Water System AMP, including enhancement to:

(a) Update the preventive maintenance activities for strainers STR-97 and STR-98 in the makeup water system that support the Fire Water System to require that they are cleaned and inspected on a 24-month frequency during the period of extended operation.

(b) Test/replace sprinkler heads in accordance with NFPA 25, Section 5.3.1. Sprinklers that have been in service for greater than 50 years prior to the program implementation date will be replaced or tested consistent with NFPA 25 prior to the program being implemented.

(c) Develop new procedure(s) to conduct flow tests at hydraulically most remote locations to address NFPA 25 Section 6.3.1. The procedures will measure flow, static pressure, and residual pressure at the hydraulically most remote fire water hose station in major structures.

(1) The turbine building is divided into two sections (Unit 1 and Unit 2) with four elevations per unit. DCPP will test a total of eight hydraulically most remote hose stations in the turbine building to represent one hose station per elevation for each unit.

(2) The auxiliary building (including the fuel handling buildings

[FHBs]) is divided into two sections (Unit 1 and Unit 2).

Flow in the radiologically controlled areas increases the amount of liquid radwaste. To minimize the amount of liquid radwaste and sufficiently represent the fire water Except for items (g)(1), (g)(3), (h),

(n), (o), (p), (q), and (r), enhancements are implemented by 11/02/2024.

(Complete)

Enhancements (g)(1) (g)(3), (n), (o),

(p), (q), and (r) are implemented by 01/30/2025.

(Complete)

Enhancement (h) is implemented by 03/30/2025.

Augmented inspections to address recurring internal corrosion and inspections (identification, visual inspections, and flow tests) of wetted normally dry piping segments that cannot be drained or that allow water to

Enclosure Attachment K PG&E Letter DCL-25-023 Page 16 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule loop, DCPP will test a total of two hydraulically most remote hose stations in the auxiliary building to represent one hose station for each unit.

(3) The containment buildings are supplied from the auxiliary building and turbine building fire water loops. DCPP will test a total of two hydraulically most remote hose stations in the containment buildings to represent one hose station for each unit.

(4) DCPP will test a total of one hydraulically most remote hose station in the common intake structure.

(d) Update procedures that perform main drain testing to include the 18-month testing frequency, the 10 percent acceptance criteria from NFPA 25, Section 13.2.5, and tracking/trending of test results.

(e) Update existing procedures to include maintaining hydrant flow for not less than 1 minute in accordance with NFPA 25, Section 7.3.2.2.

(f) Update existing procedures to perform a periodic flow test for the buried portions of the fire water system in accordance with NPFA 25, Section 7.3, at a frequency of at least one test in each one-year period.

(g) Update procedures so that interior and exterior surface inspections of the FWST are consistent with the following criteria:

(1) Inspect the internal and external surfaces of the FWST every five years, consistent with NFPA 25, Section 9.2.6 collect begin prior to Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete)

Volumetric inspections of wetted normally dry piping segments that cannot be drained or that allow water to collect begin after Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete for Unit

1)

Internal lining baseline inspections begin no later than Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete)

The program's remaining inspections begin after Unit 1: 11/02/2024 Unit 2: 8/26/2025

Enclosure Attachment K PG&E Letter DCL-25-023 Page 17 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule (with exception to Section 9.2.6.4). Any degradation that does not meet the acceptance criteria will be entered into the CAP for tracking and trending, and engineering evaluation. Degradation shall be documented via camera with nodule measurements and corrosion depth recorded.

Deficiencies will be entered into CAP and an engineering evaluation shall be performed to determine whether further actions are required in accordance with NFPA 25, Section 9.2.7, LR-ISG-2012-02, Table 4a, Note 4, and LR-ISG-2013-01, Appendix C (for coatings), and may include augmented inspections or inspection interval changes (increased in frequency) to monitor degradation. Procedures will be revised to allow the use of a variety of NDE methods, including enhanced visual (EVT-1 or equivalent), volumetric (radiographic testing or UT), and surface (magnetic particle, liquid penetrant) techniques as discussed in NUREG-1801, Revision 2, Table XI.M32-1, rather than vacuum box testing to meet NFPA-25, Section 9.2.7.6.

(2) The inspections will include use of tools necessary to adequately conduct inspection for aging mechanisms (e.g., adequate lighting will be provided).

(3) Inspections of FWST coatings will be in accordance with the training and qualification of personnel, acceptance criteria (except for cementitious coatings/linings), and corrective actions from LR-ISG-2013-01, Appendix C.

Individuals responsible for conducting coating inspections will be qualified in accordance with ASTM D4537-12.

Individuals responsible for assessing the type and extent (Complete for Unit

1)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 18 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule of coating degradation will be qualified in accordance with ASTM D7108-05.

(4) A one-time UT inspection of the tank bottom will be performed prior to November 2, 2024.

(h) Update existing procedures so that testing of the turbine building deluge valves is consistent with NFPA 25. Dry piping downstream of the deluge valves will be tested with air, smoke, or other medium during every second visual inspection (i.e., every three years) to ensure that the piping and nozzles are clear.

(i) Update existing procedures to state that deluge system nozzles will be cleaned and the respective systems retested when obstructions are identified during flow testing.

(j) Update existing procedures to:

(1) Internally inspect wet sprinkler systems using a method capable of detecting flow blockage due to fouling in addition to loss of material as described in NFPA 25, Section 14.2.

(2) Perform obstruction investigations as required by and consistent with NFPA 25, Section 14.3.

(3) Specify that external wall thickness measurements will not be used in lieu of prescribed internal visual examinations (or flow test) for managing flow blockage.

(k) Create a new procedure to implement the following activities:

Enclosure Attachment K PG&E Letter DCL-25-023 Page 19 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule (1) After identifying any portions of the fire water deluge system piping that are normally dry and periodically subject to flow, but are unable to be drained, perform either: (a) a flow test or flush sufficient to detect potential flow blockage, or (b) an inspection of 100 percent of the internal surface on those portions unable to be drained.

This activity shall be conducted in each 5-year period during the PEO. If the results of a 100-percent internal visual inspection are acceptable, and the segment is not subsequently wetted, no further augmented tests or inspections are necessary.

(2) During each 5-year period in the PEO, 20 percent of the identified portion will be volumetrically tested so that after 25 years, 100 percent has been volumetrically tested.

Measurement points are obtained to the extent that each potential degraded condition can be identified (e.g.,

general corrosion, MIC).

(3) If and when the turbine building deluge system spray piping becomes wetted, an inspection will be conducted to determine if any portions of the spray piping cannot be drained or allow water to collect, and the flow testing and inspection criteria for normally dry wet sprinkler systems above will be applied.

(l) Include the following requirements for monitoring recurring internal corrosion (RIC):

(1) Loss of material will be monitored using ultrasonic testing (UT) examinations. Representative inspection sites will be selected based on pipe configuration, flow conditions,

Enclosure Attachment K PG&E Letter DCL-25-023 Page 20 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule operating history (known degradation or leakage), and will be updated periodically based on operating experience.

(2) The UT measurements will be compared to the nominal pipe wall thickness for initial measurements or to previous thickness measurements to determine rates of corrosion and the estimated time to reach minimum wall thickness.

(3) If UT examination results indicate that the component does not meet DCPP acceptance criteria or is experiencing a reduction in wall thickness greater than 50 percent regardless of the minimum wall thickness, the issue will be entered into the CAP for resolution. PG&E will consider multiple RIC locations in the technical evaluation of the structural integrity of the pipe when RIC is identified by the volumetric RIC inspections.

(4) The effectiveness of the corrective actions taken to address the previous RIC operating experience will be evaluated. A minimum of five RIC UT examinations will be conducted per year until the rate of RIC occurrences no longer meets the criteria for RIC. If more than one RIC caused leak or wall thickness less than minimum allowable wall thickness is identified in the annual inspection period, an additional five RIC UT examinations over the following 12-month period will be performed for each RIC leak or finding of wall thickness less than minimum allowable wall thickness. The total number of inspections need not exceed 25 RIC inspections per year.

(5) The cause of any newly identified RIC will be entered into

Enclosure Attachment K PG&E Letter DCL-25-023 Page 21 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule the CAP for further evaluation and corrective actions.

(6) Perform internal visual inspections during opportunistic inspections.

(m) Update inspection and test procedures to require trending of data.

(n) Update existing procedures to ensure visual inspections used to detect loss of material use inspection techniques capable of detecting surface irregularities that could indicate wall loss to below nominal pipe wall thickness due to corrosion and corrosion product deposition. Where such irregularities are detected, follow-up volumetric wall thickness examinations are performed.

(o) Create a new procedure or revise preventive maintenance activities to remove and inspect water system mainline strainers every 5 years in accordance with NFPA 25 Sections 10.2.1.7, 10.2.7.3, and 10.2.7.4.

(p) Update procedures to require that mainline strainers be flushed after each operation or flow test in accordance with NFPA-25 Section 10.2.7.1.

(q) Update existing procedures such that DCPP's CLB (License Amendments 225 and 227) for performance-based inspection, testing, and maintenance frequencies will not be applied to the FWST inspections/tests, underground flow tests, and inspections of normally dry but periodically wetted piping that will not drain due to its configuration.

(r) Update existing procedure acceptance criteria to include the

Enclosure Attachment K PG&E Letter DCL-25-023 Page 22 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule following:

x The ability of the fire protection system to maintain required pressure and flow rates.

x Minimum design wall thickness is maintained.

x No fouling exists in the sprinkler system that could cause blockage in the sprinkler heads.

18 Aboveground Metallic Tanks (A.2.2.16)

XI.M29 Implement the new DCPP Aboveground Metallic Tanks AMP.

AMP is implemented and inspections start by:

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 19 Fuel Oil Chemistry (A.2.2.17)

XI.M30 Continue the existing DCPP Fuel Oil Chemistry AMP, including enhancements to:

(a) Include the emergency diesel generator diesel fuel oil day tanks, portable diesel electric generator fuel oil tanks, portable diesel-driven fire water pump tanks, emergency diesel fuel oil pump head (priming) tanks, and portable caddy fuel oil tanks.

(b) Drain, clean, and visually inspect the internal surfaces of the emergency diesel generator fuel oil day tanks, portable diesel-driven fire water pump fuel oil tanks, portable diesel electric generator fuel oil tanks, emergency diesel fuel oil pump head (priming) tanks and portable caddy fuel oil tanks every 10 years. Volumetrically inspect the tanks, if evidence of degradation Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Implement the enhancements and start the one-time and 10-year interval inspections no earlier than 10 years prior to the PEO.

(Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 23 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule is observed during visual inspection, or if visual inspection is not possible.

(c) Include the addition of biocide to the portable diesel electric generator fuel oil tanks, and portable caddy fuel oil tanks.

(d) Include periodic sampling of the fuel oil stored in the portable diesel-driven fire water pump fuel oil tanks, the portable diesel electric generator fuel oil tanks and the portable caddy tanks.. The periodic samples will be multilevel samples or, if tank design features do not allow for multilevel sampling, a representative sample from the lowest point in the tank will be used. If accumulated water is found in one of the fuel oil tanks, it will be promptly removed via the CAP.

(e) Provide for sampling of new diesel fuel oil prior to introduction into the portable diesel-driven fire water pump tanks and the portable diesel electric generator fuel oil tanks. Include annual monitoring and trending of water and sediment content, total particulate concentration, and the levels of microbiological organisms in the fuel oil for the portable diesel-driven fire water pump tanks and the portable diesel electric generator fuel oil tanks. Testing for microbiological organisms will be performed annually.

Acceptance criteria will be in accordance with industry standards and equipment manufacturer or fuel oil supplier recommendations.

(f) Credit the fuel oil storage tank inspections for the one-time inspection of the fuel oil system components, if the material and environment are the same.

(g) State that trending of water and particulate levels is controlled in accordance with DCPP Technical Specifications and plant

Enclosure Attachment K PG&E Letter DCL-25-023 Page 24 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule procedures for the emergency diesel generator diesel fuel oil storage tanks and the emergency diesel generator diesel fuel oil day tanks.

(h) Plant procedures will be enhanced to check and drain water from the portable diesel electric generators and portable diesel driven fire water pumps filtration devices prior to use which will minimize any water entry.

20 Reactor Vessel Surveillance (A.2.2.18)

XI.M31 Continue the existing DCPP Reactor Vessel Surveillance AMP.

11/02/2024 (Complete) 21 One-Time Inspection (A.2.2.19)

XI.M32 Implement the new DCPP One-Time Inspection AMP.

The AMP will be completed by 03/31/2026.

22 Selective Leaching (A.2.2.20)

XI.M33 Implement the new DCPP Selective Leaching AMP.

Complete initial sample size inspections prior to 03/31/2026.

Complete follow-up or expansion inspections by 12/1/2028.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 25 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule 23 One-Time Inspection of ASME Code Class 1 Small-Bore Piping (A.2.2.21)

XI.M35 Implement the new DCPP One-Time Inspection of ASME Code Class 1 Small-Bore Piping AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 24 External Surfaces Monitoring of Mechanical Components (A.2.2.22)

XI.M36 Implement the new DCPP External Surfaces Monitoring of Mechanical Components AMP.

(1) The implementation schedule for initiating inspections is consistent with LR-ISG-2012-02, Aging Management of Internal Surfaces, Fire Water Systems, Atmospheric Storage Tanks, and Corrosion Under Insulation.

AMP is implemented by 05/02/2024.

(Complete)

Inspections begin after(1):

Unit 1: 11/02/2024 Unit 2: 08/26/2025 25 Flux Thimble Tube Inspection (A.2.2.23)

XI.M37 Continue the existing DCPP Flux Thimble Tube Inspection AMP.

Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete).

26 Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components (A.2.2.24)

XI.M38 Implement the new DCPP Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components AMP including the following:

(a) Replace in-scope domestic water system copper alloy piping with a material that is more corrosion-resistant or install pipe shielding to ensure that no adverse 10 CFR 54.4 a(2) spatial interactions AMP is implemented by 05/02/2024 (Complete);

inspections begin after:

Enclosure Attachment K PG&E Letter DCL-25-023 Page 26 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule could occur.

(b) Based on operating experience, loss of material due to RIC will be managed such that additional inspections will be performed if any sample-based inspections in the Saltwater System do not meet the acceptance criteria, unless the cause of the aging effect for each applicable material and environment is corrected by repair or replacement. The DCPP Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components AMP will also state that the number of inspections will be increased in accordance with the DCPP CAP; however, no fewer than five additional inspections are conducted for each inspection that did not meet acceptance criteria, or 20 percent of each applicable material, environment, and aging effect combination is inspected, whichever is less.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 Copper alloy piping of the domestic water system that are in the scope of license renewal will be replaced or pipe shielding will be installed prior to 12/01/2028.

27 Lubricating Oil Analysis (A.2.2.25)

XI.M39 Continue the existing DCPP Lubricating Oil Analysis AMP, including the following enhancements:

(a) Include periodic sampling and analysis to maintain lubricating and hydraulic oil contaminants, primarily water and particulates, within acceptable limits; (b) Perform sampling for water, particle count, and other parameters to detect evidence of contamination by moisture or excessive corrosion; (c) Include acceptance criteria for lubricating and hydraulic oil associated with the equipment within the scope of the Lubricating Oil Analysis AMP. The acceptance criteria for lubricating and hydraulic oil analysis will be derived from original equipment 11/02/2024 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 27 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule manufacturer vendor manuals, industry guidance ASTM D 6224-02, and plant-specific operating experience; (d) Monitor water and particle concentration of the lubricating and hydraulic oil and check for unusual trends; (e) Clarify that phase-separated water in any amount is not acceptable for any component within the scope of License Renewal; (f) Conditions where action limits are reached or exceeded are put into the corrective action program to be evaluated and addressed.

28 Buried and Underground Piping and Tanks (A.2.2.26)

XI.M41 Continue the existing DCPP Buried and Underground Piping and Tanks AMP, including enhancements to:

(a) Enhance operating procedures to provide direction to evaluate and close Makeup Water isolation valve MU-0-881 as appropriate in case of a pressure boundary failure further along the flow path or in the event the RWSRs are in use for long-term cooling.

(b) Install cathodic protection for remaining portions of the buried auxiliary saltwater system discharge and supply piping in contact with soil.

(c) Revise DCPP backfill procedure to include the guidance in LR-ISG-2015-01, Appendix B, Section 2.f, including a maximum size that meets ASTM D 448-08 size number 67 (size number 10 for polymeric materials) for backfill that is located within 6 inches of the component.

Except for items (e), (j), and (k),

enhancements are implemented by 11/02/2024 (Complete)

Enhancements (e),

(j), and (k) are implemented by 01/30/2025 (Complete)

Initial inspections completed and additional cathodic

Enclosure Attachment K PG&E Letter DCL-25-023 Page 28 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule (d) Incorporate the qualification recommendations in LR-ISG-2015-01, Appendix B, Section 6.a for individuals evaluating coating degradation.

(e) Revise the inspection plan to align with the recommendation from LR-ISG-2015-01 Table XI.M41-2 and Section 4.c.

(f) Revise the firewater system flow test to align with the annual frequency recommended in LR-ISG-2015-01.

(g) Revise DCPP cathodic protection procedure to specify that for steel components, where the acceptance criteria for the effectiveness of the cathodic protection is other than -850 mV instant off, loss of material rates will be measured per the recommendations in LR-ISG-2015-01, Appendix B, Section 6.m.

(h) Revise DCPP buried piping program procedure and backfill procedure to include the following: Cracks in controlled low strength material backfill that could admit groundwater to the surface of the component are not acceptable. Where significant coating damage due to non-conforming backfill is identified, the extent of condition will be evaluated to ensure the as-left condition of the backfill in the vicinity of the observed damage will not lead to further degradation.

(i) Revise the DCPP buried piping program procedure to include the corrective actions recommended by LR-ISG-2015-01, Appendix B, Section 7.

(j) Enhance procedure(s) to state the limiting critical potential should not be more negative than -1200 mV.

protection installed by 12/01/2028

Enclosure Attachment K PG&E Letter DCL-25-023 Page 29 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule (k) Revise the DCPP buried piping program procedure acceptance criteria to include the following:

1. Blistering, gouges, or wear of nonmetallic piping is evaluated.
2. The measured wall thickness projected to the end of the PEO meets minimum wall thickness requirements.
3. Indications of cracking in metallic pipe are managed in accordance with the CAP.
4. Cementitious piping may exhibit minor cracking and spalling provided there is no evidence of leakage, exposed or rusted staining from rebar reinforcing hoop bands.

29 Internal Coatings/

Linings for In-Scope Piping, Piping Components, Heat Exchangers, and Tanks (A.2.2.27)

XI.M42 Implement the new DCPP Internal Coatings/Linings for In-Scope Piping, Piping Components, Heat Exchangers, and Tanks AMP.

(a) Perform initial coatings/linings inspections and follow-up periodic inspections.

AMP implemented by 11/02/2024.

(Complete)

Initial inspections completed by 12/01/2028.

30 ASME Section XI, Subsection IWE (A.2.2.28)

XI.S1 Continue the existing DCPP ASME Section XI, Subsection IWE AMP, including enhancements to:

(a) Identify the selection of bolting material, installation torque or 11/02/2024 for all items except item (f).

Enclosure Attachment K PG&E Letter DCL-25-023 Page 30 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule tension, and the use of lubricants and sealants is in accordance with the guidelines of EPRI NP-5769, EPRI TR-104213, and the additional recommendations of NUREG-1339 (June 1990), to prevent or mitigate degradation and failure of structural bolting. If the structural bolting consists of ASTM A325, ASTM F1852, and/or ASTM A490 bolts, the preventive actions for storage, lubricants, and stress corrosion cracking potential discussed in Section 2 of RCSC (Research Council for Structural Connections) publication Specification for Structural Joints Using ASTM A325 or A490 Bolts, need to be considered.

(b) Explicitly prohibit the use of MoS2 as a lubricant for structural bolts to prevent SCC.

(c) Deleted.

(d) Identify that non-coated surface examinations include arc strikes as an inspection element.

(e) Supplement the requirements of the DCPP ASME Code Section XI, Subsection IWE AMP to require a one-time volumetric examination of metal liner surfaces that are inaccessible from one side, only if triggered by plant-specific OE. The trigger for this supplemental examination is a plant-specific occurrence of measurable metal liner corrosion (base metal material loss exceeding 10 percent of nominal plate thickness) initiated on the inaccessible side or areas.

(f) A supplemental one-time inspection will be performed by qualified personnel using methods capable of detecting cracking due to SCC, such as volumetric (UT), surface (MT), or enhanced (Complete)

Item (f) will be completed prior to completion of first refueling outage after 11/02/2024 and 08/26/2025 for each unit, respectively.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 31 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule visual (EVT-1), comprising a representative sample (2 penetrations) of the ten stainless steel penetrations or DMWs associated with high-temperature (above 140°F) stainless steel piping systems per unit in frequent use. These inspections are intended to confirm the absence of SCC aging effects. If cracking is detected as a result of the supplemental one-time inspections, additional inspections will be conducted in accordance with the sites corrective action process. Periodic inspection of subject penetrations with dissimilar metal welds for cracking will be added to the ASME Section XI, Subsection IWE AMP if necessary, depending on the inspection results.

31 ASME Section XI, Subsection IWL (A.2.2.29)

XI.S2 Continue the existing DCPP ASME Section XI, Subsection IWL AMP including enhancements to:

(a) Evaluate items for which examination results do not meet the acceptance standards in accordance with IWL-3300, "Evaluation,"

and document the evaluation results in an engineering report. The report is to include an evaluation of whether the concrete containment is acceptable without repair of the item and, if repair is required, the extent, method, and completion date of the repair or replacement. The report shall identify the cause of the condition and the extent, nature, and frequency of additional examinations.

(b) Update the acceptance criteria guidance to be consistent with ACI 349.3R-02.

(c) Revise implementing procedures to inspect accessible concrete for visual indications of potential ASR, such as map or patterned cracking, alkali silica gel exudations, surface staining, expansion causing structural deformation, Except for item (c),

enhancements are implemented by:

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enhancement (c) is implemented by 01/30/2025.

(Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 32 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule relative movement or displacement, or misalignment/distortion of attached components.

32 ASME Section XI, Subsection IWF (A.2.2.30)

XI.S3 Continue the existing DCPP ASME Section XI, Subsection IWF AMP, including the following enhancements:

(a) Bolting procedures will be enhanced to explicitly prohibit the use of MoS2 as a lubricant for structural bolts to prevent SCC.

(b) Bolting practice procedures will be enhanced to identify that the selection of bolting material, installation torque or tension, and the use of lubricants and sealants is in accordance with the guidelines of EPRI NP-5769, EPRI TR-104213, and the additional recommendations of NUREG-1339 (June 1990), to prevent or mitigate degradation and failure of structural bolting. If the structural bolting consists of ASTM A325, ASTM F1852, and/or ASTM A490 bolts, the preventive actions for storage, lubricants, and stress corrosion cracking potential discussed in Section 2 of RCSC (Research Council for Structural Connections) publication Specification for Structural Joints Using ASTM A325 or A490 Bolts, need to be considered.

(c) Ensure replacement and maintenance activities for high-strength structural bolting specify that the replaced bolting material has an actual measured yield strength less than 150 ksi or 1,034 MPa.

(d) Perform monitoring of high-strength structural bolting (actual measured yield strength greater than or equal to 150 ksi or 1,034 MPa and greater than one inch nominal diameter), using volumetric examination comparable to that of ASME Code, Section 11/02/2024 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 33 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule XI, Table IWB-2500-1, Examination Category B-G-1 to detect cracking in addition to the VT-3 examination.

(e) Any adverse results from the examinations of high-strength structural bolting will be entered into the CAP and will be evaluated to determine if additional actions are warranted such as expansion of inspection scope, and frequency of any additional supplemental visual or volumetric examinations.

(f) ISI Examination procedures for Class 1, 2, and 3 supports will include the following conditions as unacceptable unless the technical basis for their acceptance is documented:

(1) Loss of material due to corrosion or wear, which reduces the load bearing capacity of the component support; (2) Debris, dirt, or excessive wear that could prevent or restrict sliding of the sliding surfaces as intended in the design basis of the support; (3) Cracked or sheared bolts, including high-strength bolts, and anchors; and (4) Arc strikes, weld splatter, paint scoring, roughness, or general corrosion on close tolerance machined or sliding surfaces.

33 10 CFR Part 50, Appendix J (A.2.2.31)

XI.S4 Continue the existing DCPP 10 CFR Part 50, Appendix J AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 34 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule 34 Masonry Walls (A.2.2.32)

XI.S5 Continue the existing DCPP Masonry Walls AMP, including enhancements to:

(a) Include condition monitoring for evidence of shrinkage and/or separation of masonry walls and gaps between the supports and masonry walls that could impact the intended function or potentially invalidate its evaluation basis.

(b) Require inspections to be performed at least every five years for masonry walls.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 35 Structures Monitoring (A.2.2.33)

XI.S6 Continue the existing DCPP Structures Monitoring AMP, including enhancements to:

(a) Revise procedures to require that whenever an in-scope pull box is going to be opened, the appropriate personnel will be notified to allow them to determine whether an opportunistic inspection of the pull box should be performed. The criteria for determining whether an opportunistic inspection will be performed may include (1) previous inspection results for the subject pull box, or (2) consideration of new industry or DCPP-specific OE for pull boxes.

(b) Add embedments, jet impingement shields, racks, structural sealants (including weatherproofing boots), and sliding surfaces to the scope of the DCPP Structures Monitoring AMP.

(c) Include preventive actions delineated in NUREG-1339 and in EPRI NP-5769, NP-5067, and TR-104213 to ensure structural bolting integrity. These actions emphasize proper selection of Enhancements (a),

(d), (e), (h), (i), and (j) are implemented by:

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enhancements (b),

(c), (f), (g), (k), (l),

and (m), and (t) are implemented by 01/30/2025.

(Complete)

Enhancement (o) walkdowns completed and

Enclosure Attachment K PG&E Letter DCL-25-023 Page 35 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule bolting material, lubricants, and installation torque or tension to prevent or minimize loss of bolting preload and cracking of structural bolting. If the structural bolting consists of ASTM A325, ASTM F1852, and/or ASTM A490 bolts, the preventive actions for storage, lubricants, and stress corrosion cracking potential discussed in Section 2 of RCSC publication Specifications for Structural Joints Using ASTM A325 or A490 Bolts, will be used. Molybdenum disulfide will explicitly be prohibited as a lubricant for structural bolts to prevent SCC.

(d) Monitor groundwater samples at least every five years for pH, sulfates, and chloride concentrations, including consideration for potential seasonal variations, and assess the impact of changes in its chemistry on below grade concrete structures.

(e) Monitor accessible sliding surfaces for indication of significant loss of material due to wear or corrosion, debris, or dirt. In addition, specify the acceptance criteria for sliding surfaces are no indications of excessive loss of material due to corrosion or wear and no debris or dirt that could restrict or prevent sliding of the surfaces as required by design.

(f) Monitor/inspect structural sealants (including weatherproofing boots) for cracking, loss of material, and hardening.

(g) Monitor all structures on a frequency not to exceed 5 years such that all structures will be inspected within the five years after 11/02/2024 for Unit 1 and 08/26/2025 for Unit 2.

(h) Conduct a baseline inspection of all safety and non-safety related structures concrete elements in accordance with ACI 349.3R-02 enhancements (n),

(o), (p), and (q) implemented prior to completion of first refueling outage after 11/02/24 and 8/26/25 for Units 1 and 2, respectively.

Enhancement (r) will be implemented prior to completion of the second Unit 1 refueling outage in the Unit 1 PEO.

Enhancement (s) will be completed six months following completion of the first Unit 2 refueling outage in the Unit 2 PEO.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 36 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule acceptance criteria.

(i) Align the inspector qualifications with the guidance in ACI 349.3R-

02.

(j) Specify that structural sealants (including weatherproofing boots) are acceptable if the observed loss of material, cracking, and hardening will not result in loss of sealing.

(k) Monitor structural sealants (including weatherproofing boots) on an interval not to exceed 5 years, except for those associated with the CSTs, RWSTs, PWSTs, and transfer tank that will be monitored on a refueling outage frequency.

(l) Clarify that fiberglass roofing is acceptable if there is no evidence of blistering, cracking, or loss of material that could cause a loss of function prior to the next scheduled inspection.

(m) Revise implementing procedures to inspect accessible concrete for visual indications of potential ASR, such as map or patterned cracking, alkali silica gel exudations, surface staining, expansion causing structural deformation, relative movement or displacement, or misalignment/distortion of attached components.

(n) Perform rodding, snaking or video inspections of all Units 1 and 2 SFP and TC leak chase tell-tale drains to identify potential blockages prior to PEO. Subsequent periodic tell-tale drain internal inspections will initially be performed in the PEO on a frequency of once per every 5 years. The long-term

Enclosure Attachment K PG&E Letter DCL-25-023 Page 37 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule frequency may be adjusted by evaluating internal and external operating experience.

(o) Periodic walkdowns of accessible interior walls and ceilings that are adjacent to the Reactor Cavity, Refueling Canal, SFPs, and TCs will be performed on an interval not to exceed 5 years to identify in-leakage into the structure in-accordance with EPRI 3002007348. Any newly identified leaks or changes in existing leak sites will be entered into CAP and evaluated to assure that Reactor Cavity, Refueling Canal, SFP, and TC leakage is being effectively managed.

(p) Reactor Cavity, Refueling Canal, SFP, and TC leak chase sampling parameters and acceptance criteria will be enhanced consistent with Table A-1 of EPRI TR-3002007348 as follows with initial frequencies provided. The long-term frequencies may be adjusted by evaluating internal and external operating experience.

The following is conducted for the SFP and TC:

x Chlorides (conditional if leak rate has increased by 3x previous value and total volume collected >300 ml):

<500 ppm x

Sulfates (conditional if leak rate has increased by 3x previous value and total volume collected >300 ml):

<1,500 ppm x

Integrated review (quarterly): compile and trend the integrated data to determine whether leakage conditions have changed.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 38 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule In addition, the following is conducted on a refueling outage frequency for the Reactor Cavity and Refueling Canal except for conditional sampling as noted below:

x Flow rate: 0 drips per minute unless identified as a known leaker. No discharge from a tell-tale that had previous leakage may indicate a blockage. New leakage may indicate a change to leakage pathways. Significant changes to the leak rate will be reviewed as part of the overall trend analysis.

x pH: >5 x

Boron: an additional information tool to monitor for ground water dilution and to provide context for leakage constituent. Therefore, a specific acceptance criterion for boron concentration is not warranted.

x Chlorides (conditional if leak rate has increased by 3x previous value and total volume collected >300 ml):

<500 ppm x

Sulfates (conditional if leak rate has increased by 3x previous value and total volume collected >300 ml):

<1,500 ppm x

Integrated review: compile and trend the integrated data to determine whether leakage conditions have changed.

x Iron: an additional information tool to monitor for changes in iron corrosion occurring behind the Reactor Cavity and Refueling Canal liner. Therefore, a specific acceptance criterion for iron concentration is not warranted.

x Tritium: an additional information tool to monitor for changes in leakage composition. Therefore, a specific acceptance criterion for tritium concentration is not warranted.

x Gamma Isotropic: an additional information tool to

Enclosure Attachment K PG&E Letter DCL-25-023 Page 39 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule inform the collected water source analysis. Therefore, a specific acceptance criterion for gamma isotropic concentration is not warranted.

(q) Procedure(s) will be developed or revised to manage the Reactor Cavity, Refueling Canal, SFP, and TC surveillance and maintenance activities consistent with Elements 1 and 3 through 6 of EPRI 3002007348. Analysis results of data collected from the Reactor Cavity, Refueling Canal, SFPs, and TCs that do not meet acceptance criteria will be entered into CAP and evaluated, including consideration of revisiting structural evaluations to determine whether any future observed indications of changes in the leakage conditions cause structural margin to become inadequate.

(r) During the first Unit 1 refueling outage in the PEO, PG&E will perform a Reactor Cavity and Refueling Canal leak chase internal inspection feasibility determination. Prior to completion of the second Unit 1 refueling outage in the PEO, PG&E will perform an internal inspection of all Unit 1 Reactor Cavity and Refueling Canal leak chases. During the first Unit 2 refueling outage in the PEO, PG&E will perform an internal inspection of all Unit 2 Reactor Cavity and Refueling Canal leak chases. Subsequent periodic telltale drain internal inspections will be performed in the PEO on an initial frequency of once per every 3 refueling outages for the Reactor Cavity and Refueling Canal leak chases. The long-term frequency may be adjusted by evaluating internal and external operating experience.

(s) Perform a structural evaluation of any identified degradation of concrete and structural steel due to leakage of borated

Enclosure Attachment K PG&E Letter DCL-25-023 Page 40 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule water from the Rx Cavity and RC and a conservative projection of the potential degradation of those surfaces for the PEO.

(t) Monitor fiberglass roofing panels for blistering, cracking, and loss of material.

36 RG 1.127, Inspection of Water-Control Structures Associated with Nuclear Power Plants (A.2.2.34)

XI.S7 Continue the existing DCPP RG 1.127, Inspection of Water-Control Structures Associated with Nuclear Power Plants AMP, including enhancements to:

(a) Revise implementing procedures to include miscellaneous steel (e.g., bar racks) in the scope of the DCPP RG 1.127, Inspection of Water-Control Structures Associated with Nuclear Power Plants AMP.

(b) Revise implementing procedures to specify:

(1) Structural bolting replacement and maintenance activities will include appropriate preload and proper tightening (torque or tension) as recommended in EPRI documents, American Society for Testing of Materials (ASTM) standards, American Institute of Steel Construction (AISC)

Specification, and in Section 2 of RCSC (Research Council for Structural Connections) publication Specifications for Structural Joints Using ASTM A325 or A490 Bolts, as applicable.

(2) Molybdenum disulfide will not be used.

(c) Revise implementing procedures to monitor structural concrete for Except for item (g),

enhancements are implemented by:

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enhancement (g) is implemented by 01/30/2025 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 41 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule movements (e.g., heaving, deflection), conditions at junctions with abutments and embankments, loss of material, and increase in porosity and permeability.

(d) Develop the requirements for future discharge conduit inspections, including those to be performed during the PEO, based on the findings from the 1R17/2R17 (2012/2013) inspections. These requirements will address the following:

(1) inspection interval (not to exceed 5 years);

(2) extent and frequency of marine growth removal; and (3) inspection extent (100 percent vs. sampling).

(e) Revise implementing procedures to align the inspector qualifications with the guidance in ACI 349.3R-02.

(f) Perform LR baseline inspections of all concrete water-control structures in accordance with ACI 349.3R-02 acceptance criteria.

(g) Revise implementing procedures to inspect accessible concrete for visual indications of potential ASR, such as map or patterned cracking, alkali silica gel exudations, surface staining, expansion causing structural deformation, relative movement or displacement, or misalignment/distortion of attached components.

37 Protective Coating Monitoring and XI.S8 Continue the existing DCPP Protective Coatings Monitoring and Maintenance AMP, including enhancement to:

Unit 1: 11/02/2024 Unit 2: 08/26/2025

Enclosure Attachment K PG&E Letter DCL-25-023 Page 42 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule Maintenance (A.2.2.35)

(a) Specify that a pre-inspection review of the previous two monitoring reports be performed.

(Complete) 38 Insulation Material for Electrical Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements (A.2.2.36)

XI.E1 Implement the new DCPP Insulation Material for Electrical Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements AMP.

(a) Implement a solution to prevent or divert oil from the cables affected by oil residue.

AMP is implemented by Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

A solution to prevent or divert oil from the cables affected by oil residue will be implemented prior to 12/31/2025.

39 Insulation Material for Electrical Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Used in XI.E2 Continue the existing DCPP Insulation Material for Electrical Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Used in Instrumentation Circuits AMP, including enhancements to:

(a) Procedures/work orders will be developed or revised to include the cables and connections used in nuclear instrumentation channels (source range, intermediate range, and power range).

(b) Procedures/work orders for cable testing will be developed to specify the parameters that require monitoring for indications of age-related degradation for nuclear instrumentation channels Unit 1: 11/02/2024 Unit 2: 8/26/2025 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 43 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule Instrumentation Circuits (A.2.2.37)

(source range, intermediate range, and power range).

(c) Procedures associated with calibration/surveillance tests of radiation monitors will be developed or revised to implement the review of results obtained during calibration or surveillance tests that fail to meet acceptance criteria, to determine whether the associated circuits continue to perform their intended function in light of any aging effects on cables and connectors insulation.

Review of the calibration/surveillance test results will be completed prior to November 2, 2024, and August 26, 2025 for Units 1 and 2, respectively, and at least every 10 years thereafter.

Calibration/ surveillance results that do not meet acceptance criteria are reviewed for aging effects when the results will be available.

(d) Procedures/work orders will be developed to implement cable system testing for the nuclear instrumentation monitors (SRM/IRM/PRM) using a proven test for detecting deterioration of the insulation system, such as insulation resistance tests, time domain reflectometry tests, or other testing judged to be effective in determining cable system insulation condition. Cable system testing will be performed at least once every 10 years, with the first tests completed prior to November 2, 2024, and August 26, 2025 for Units 1 and 2, respectively. Procedure/work orders will specify the parameters that require monitoring for indications of age-related degradation and acceptance criteria for the cable tests.

(e) Procedures/work orders will be developed to implement testing of nuclear instrumentation channels (source range, intermediate range, and power range) cables to specify the

Enclosure Attachment K PG&E Letter DCL-25-023 Page 44 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule test acceptance criteria.

40 Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements (A.2.2.38)

XI.E3 Continue the DCPP Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements AMP including enhancements to:

(a) Enhance procedure/work orders to implement aging effects management of the inaccessible and underground in-scope power cables (greater than or equal to 400 volts).

(b) Enhance maintenance plans for periodic inspection of pull boxes with potential for water intrusion that contain in-scope power cables (greater than or equal to 400 volts) to determine if water has accumulated at least once a year, except for intake structure pull boxes that are inspected every refueling outage. a. If cables are submerged (i.e., cable exposed to significant moisture),

corrective actions are taken to keep the cable dry, assess cable degradation, and to determine the cause of pull box water accumulation.

(c) Perform one timebaseline inspection of pull boxes, which will include inspections for excessive drooping or sagging of cables, and visible indications of damage or degradation of cables and cable supports.

(d) Enhance maintenance plans for intake structure pull boxes to revise the inspection frequency to every refueling outage, include inspection of accessible conduit ends for water collection, and include inspection of cables and cable support structures for visible signs of degradation. Enhance maintenance plans to initiate an Engineering evaluation to assess cable degradation and to Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete, except for enhancement (f) for Unit 2 first tests)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 45 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule determine the cause of water accumulation, when cables are found submerged.

(e) Enhance maintenance plans to perform testing of pull box sump and sump alarm features at least once annually prior to the rainy season, with the first tests completed prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively.

(f) Create procedure/work orders to implement testing of power cables (greater than or equal to 400 volts) to provide an indication of the condition of cable insulation, using a proven test for detecting deterioration of the insulation system due to wetting or submergence. The condition of cable insulation will be assessed with reasonable confidence using one or more of the following techniques: dielectric loss (dissipation factor or power factor), AC voltage withstand, partial discharge, step voltage, time domain reflectometry, insulation resistance and polarization index, line resonance analysis, or other testing that is state-of the-art at the time the tests are performed. Testing will be performed at least once every six years with the first test completed prior to November 2, 2024, and August 26, 2025, for Units 1 and 2, respectively. Test results that are trendable will be used to provide additional information on the rate of cable insulation degradation. More frequent testing may occur based on test results and operating experience.

(g) Create procedure/work orders to define acceptance criteria for pull box inspections and cable testing. The acceptance criteria for each test will be defined by the specific type of test performed and the specific cable tested.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 46 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule 41 Metal Enclosed Bus (A.2.2.39)

XI.E4 Continue the existing DCPP Metal Enclosed Bus AMP, including an enhancement to:

(a) Create procedure(s) to formalize the existing inspection and testing of the MEBs and include specific inspection scope, inspection methods, inspection frequencies, and actions to be taken when acceptance criteria are not met.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 42 Electrical Cable Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements (A.2.2.40)

XI.E6 Implement the new DCPP Electrical Cable Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements AMP.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 43 Periodic Inspections for Selective Leaching (A.2.2.41)

Plant-Specific Implement the new DCPP Periodic Inspections for Selective Leaching AMP.

AMP is implemented by:

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Complete initial inspections prior to 03/31/2026.

Enclosure Attachment K PG&E Letter DCL-25-023 Page 47 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule 44 Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators (A.2.2.42)

Plant-Specific Continue the existing DCPP Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP including enhancements to:

(a) Identify transmission and substation components required to support station blackout recovery which are in the scope of license renewal aging management. In the 230 kV switchyard, these are the components between the startup transformers and disconnects 217 and 219. In the 500 kV switchyard these are the components between the main transformers and switchyard breakers 532/632 (associated with Unit 1 and 542/642 (associated with Unit 2).

(b) Include gathering and reviewing completed maintenance and inspection results, by the plant staff, to identify adverse trends.

(c) Require that an engineering evaluation will be conducted when a degraded condition is detected that considers the extent of the condition, reportability of the event, potential causes, probably of recurrence, and the corrective actions required.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 45 Quality Assurance (A.1.3)

Appendix A Continue the existing QA Program, including enhancement, to include nonsafety-related SSCs that are subject to AMR for LR.

Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete) 46 Operating Experience (A.1.4)

N/A Continue the existing Operating Experience Program, including enhancement to:

(a) Require the review of internal and external OE for aging-related degradation or impacts to aging management activities, to Unit 1: 11/02/2024 Unit 2: 08/26/2025 (Complete)

Enclosure Attachment K PG&E Letter DCL-25-023 Page 48 of 48 Supplement - DCPP LRA, Amendment 4 No.

Aging Management Program or Activity (Section)

NUREG-1801 Section Commitment Implementation Schedule determine if improvements to aging management activities are warranted. NRC and industry guidance documents and standards applicable to aging management are considered part of this information.

(b) Provide procedural guidance for identifying and reviewing OE including descriptions of aging-related degradation. In general, the descriptions will be used to identify aging that is in excess of what would be expected, relative to design, previous inspection experience and the inspection intervals.

(c) Establish coding for use in identification, trending, and communication of age-related degradation.

(d) Establish guidelines for reporting plant-specific OE on age-related degradation and aging management to the industry.

(e) Provide training, on a periodic basis, to those responsible for AMP implementation and those responsible for reviewing, evaluating, and communicating OE items related to age-related degradation and aging management.

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