IR 05000275/2024013

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– License Renewal Report 05000275/2024013 and 05000323/2024013
ML24298A129
Person / Time
Site: Diablo Canyon  
Issue date: 10/28/2024
From: Nick Taylor
NRC/RGN-IV/DORS/EB2
To: Peck A
Pacific Gas & Electric Co
References
IR 2024013
Download: ML24298A129 (48)
v • d • e


Text

October 28, 2024

SUBJECT:

DIABLO CANYON POWER PLANT - LICENSE RENEWAL REPORT 05000275/2024013 AND 05000323/2024013

Dear Adam Peck:

On September 16, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Diablo Canyon Power Plant and discussed the results of this inspection with Allen Wilson, Senior Director of Engineering, Projects, & Outages and other members of your staff.

The results of this inspection are documented in the enclosed report.

No findings or violations of more than minor significance were identified during this inspection.

This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, Nicholas H. Taylor, Chief Engineering Branch 2 Division of Operating Reactor Safety Docket Nos. 05000275, 05000323 License Nos. DPR-80, DPR-82

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000275 and 05000323

License Numbers:

DPR-80 and DPR-82

Report Numbers:

05000275/2024013 and 05000323/2024013

Enterprise Identifier:

I-2024-013-0003

Licensee:

Pacific Gas and Electric Company

Facility:

Diablo Canyon Power Plant

Location:

Avila Beach, CA

Inspection Dates:

August 19, to September 16, 2024

Inspectors:

P. Cooper, Senior Reactor Inspector

G. Pick, Senior Reactor Inspector

A. Siwy, Senior Project Manager

C. Smith, Senior Reactor Inspector

Approved By:

Nicholas H. Taylor, Chief

Engineering Branch 2

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a license renewal at Diablo Canyon Power Plant, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

List of Findings and Violations

No findings or violations of more than minor significance were identified.

Additional Tracking Items

None.

INSPECTION SCOPES

Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

OTHER ACTIVITIES

- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL

===71002 - License Renewal Inspection On November 17, 2010, the NRC issued an inspection report for the withdrawn license renewal application (ADAMS No. ML103220205). This previous inspection was performed using Inspection Procedure 71002, and evaluated the licensees aging management programs, the structures, systems, and components in the scope of license renewal, and the application itself.

This inspection report is the second in a series of inspections that will review the licensees recent preparations for the current license renewal application, specifically focused on evaluating the differences between the original license renewal application and the application currently under review (ADAMS No. ML23311A154).

The inspectors performed this partial inspection to evaluate whether aging management programs will be capable of managing identified aging effects in an appropriate manner. This inspection allowed the inspectors to review their assigned aging management programs, to assess the progress of the licensee implementation activities, and to perform walkdowns in the plant.

The inspectors reviewed the aging management program basis documents and compared them to NUREG-1801, Generic Aging Lessons Learned (GALL) Report, Revision 2 and appendices A and B of the licensee's license renewal application. The inspectors also reviewed selected implementing documents. The inspectors verified that aging management programs reflected the planned updated final safety analysis report supplement, verified the programs included industry and site-specific operating experience, and assessed site-specific information when designing the aging management programs described in the basis documents.

The inspectors will complete the review of aging management implementation activities during planned inspections in February 2025, and potentially other future inspections if the need arises.

These additional inspections will review the aging management program implementation, work orders, commitment changes, and other associated implementation activities. Additionally, the inspectors will review the annual license renewal application update, and document those results in future inspections reports.

The inspectors determined that the aging management program basis document for the programs listed below accurately reflected the license renewal application appendices A and B and the generic aging lessons learned report.

License Renewal Inspection===

Main article: IP 71002
(1) Scoping and Screening Review The team examined license renewal drawings, verifying that non-safety-related SSCs were accurately included within the scope of license renewal, as mandated by 10 CFR 54.4(a)(1), (a)(2), and (a)(3). This was accomplished by comparing color-coded license renewal drawings to the actual plant configuration determined by independent walkdowns.

The team interviewed personnel, reviewed program documents and independently walked down the following areas within the plant:

  • Units 1 and 2 turbine building
  • Diesel generator rooms 2-2, and 2-3
  • Units 1 and 2 closed cooling water heat exchanger rooms
  • Intake structure
  • Fuel oil storage bunker A previous NRC inspection, for the withdrawn license renewal application, flagged fire protection piping that could affect safety-related SSCs in the turbine building. The inspectors reviewed the associated drawings and a walkdown of the area confirmed these issues had been resolved.

The NRC did not identify any concerns with scoping and screening during the inspection.

(2) Area Walkdowns As noted in scoping and screening review, the inspectors performed the following area walkdowns:
  • Unit 1 and 2 turbine building
  • Diesel generator rooms 2-2, and 2-3
  • Units 1 and 2 closed cooling water heat exchanger rooms
  • Intake structure
  • Fuel oil storage bunker

===71013 - Site Inspection for Plants with a Timely Renewal Application The inspectors performed Phase 2 of inspection procedure 71013, "Site Inspection for Plants with A Timely Renewal Application", of Diablo Canyon Power Plant, Unit 1 the week of August 19, 2024. The inspection procedure recommended that the inspection be conducted shortly before the period of extended operation. The period of extended operation is the additional 20 years beyond the original 40-year licensed term. The period of extended operation for Diablo Canyon Power Plant, Unit 1, will begin after midnight on November 2, 2024.

The inspectors evaluated the adequacy and effectiveness of the implementation and completion of the aging management programs and activities described in the regulatory commitments proposed during license renewal, updated final safety analysis report supplement program descriptions, time limited aging analyses, and proposed license conditions as agreed to by the licensee while the application for renewal is -under review.

For each aging management program reviewed, the inspectors reviewed program documents, license renewal documents, the safety analysis report, and the safety evaluation report.

Supporting documents reviewed included implementing procedures, work orders, inspection reports, engineering evaluations, calculations, database entries, and condition reports. The inspectors interviewed program owners and license renewal program personnel.

The inspectors will complete the review of aging management implementation activities during planned inspections in February 2025, and potentially other future inspections if the need arises.

These additional inspections will review the aging management program implementation, work orders, commitment changes, and other associated implementation activities.

The inspectors paraphrased most of the proposed commitments listed in the aging management program reviews. For the actual wording refer to the safety evaluation report and any license basis changes. The inspectors listed specific documents reviewed in the attachment.

Site Inspection for Plants with a Timely Renewal Application===

Main article: IP 71013
(1) A.2.1.1 Fatigue Monitoring and Commitment 1 This existing condition monitoring program manages fatigue usage caused by anticipated cyclic strains. The program criteria ensure fatigue usage factors remain within allowable limits for components of the reactor coolant system.

Commitment 1 specified:

Continue the fatigue monitoring aging management program with enhancements to:

  • Include additional analyses and critical thermal and pressure transients for components that have been identified to have a fatigue time-limited aging analysis, which are not covered by the current program. Additional locations will include environmentally assisted fatigue analyses for the set of sample components or any more limiting than those in the listed NRC and industry documents.
  • Include acceptance criteria for transient definitions, cycle count action limits, and cumulative usage factor action limits.
  • Modify procedures to specify the periodic review at least once per fuel cycle of the monitored cycle count and cumulative usage factor data. This review will assess whether to update the fatigue analyses if
(a) an allowable cycle limit is approached,
(b) a transient definition has been changed,
(c) unanticipated new thermal events are discovered, or
(d) the geometry of components has been modified.
  • Revise procedures to include corrective actions if a component reaches a cycle count action limit or a fatigue usage action limit. The licensee will revise the fatigue analysis or repair/replacement 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.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(2) A.2.1.2 Environmental Qualification (EQ) of Electric Components and Commitment 2 This existing program manages the effects of aging of environmentally qualified equipment, such that the components maintain their intended function(s) for the period of extended operation.

Commitment 2 specified:

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(3) A.2.2.1 ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD and Commitment 3 This existing condition monitoring program and inspection manages the aging effects of cracking, loss of material, and reduction of fracture toughness by performing inspections on Class 1, 2, and 3 piping and components. The licensee performs periodic visual, surface, and volumetric examinations, as well as leakage tests of Class 1, 2, and 3 pressure-retaining components, including welds, pump casings, valve bodies, vessels, integral attachments, and pressure-retaining bolting.

Commitment 3 specified:

  • Continue the existing ASME Section XI Inservice Inspection, Subsections IWB, IWC and IWD aging management program with an enhancement to re-examine the unit 1 Pressurizer Spray Line Pipe Weld WIB-378 for three inservice inspection periods since identification of the weld flaw in 2015 in accordance with ASME Code, paragraph IWB-2420 for Successive Inspections.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(4) A.2.2.2 Water Chemistry and Commitment 4 This existing mitigation program manages the effects of aging caused by loss of material because of corrosion, cracking because of stress corrosion cracking and related mechanisms, and reduction of heat transfer because of fouling in components exposed to a treated water environment. The licensee monitors treated water to minimize loss of material, cracking, or fouling. The licensee follows industry guidance for both their primary and secondary water chemistry programs.

Commitment 4 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, corrective action documents, and chemistry trends. The inspectors verified that licensee procedures provide instructions and specifications for chemical species, impurities and additives, sampling and analysis frequencies, and corrective actions for out-of-specification primary and secondary water chemistry. The licensee established action levels to aid in maintaining their chemistry for the monitored parameters. The inspectors verified the control of selected parameters for both primary and secondary chemistry.

The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(5) A.2.2.3 Reactor Head Closure Stud Bolting and Commitment 5 This existing program manages the aging effects of cracking caused by stress corrosion cracking or intergranular stress corrosion cracking and loss of material caused by wear or corrosion for reactor vessel closure stud bolting.

Commitment 5 specified:

  • Continue the reactor head closure stud bolting aging management program with an enhancement to ensure the actual measured yield strength of replacement reactor head closure stud material purchased in the future is limited to <150 ksi.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(6) A.2.2.4 Boric Acid Corrosion and Commitment 6 This existing condition monitoring program covers structural components (e.g.,

carbon or low alloy steel, copper alloy >15% zinc, and aluminum) and electrical components onto which borated reactor water may leak. This program is intended to be consistent with NRC Generic Letter 88-05 and assures detection of leakage before the loss of the intended function of the affected components.

Commitment 6 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(7) A.2.2.5 Cracking of Nickel-Alloy Components and Loss of Material Due to Boric Acid-Induced Corrosion in Reactor Coolant Pressure Boundary Components and Commitment 7 This existing condition monitoring program manages loss of material caused by boric acid-induced corrosion in susceptible safety-related components in the vicinity of nickel-alloy reactor coolant pressure boundary components, as well as cracking of nickel-alloy components and associated welds in reactor coolant pressure boundary components. The program provides inspection requirements for the reactor pressure vessel and reactor coolant pressure boundary piping components if they contain primary water stress corrosion cracking susceptible materials designated alloys 600/82/182. The program also includes inspection requirements for the reactor pressure vessel upper head.

Commitment 7 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(8) A.2.2.6 Thermal Aging Embrittlement of Cast Austenitic Stainless Steel (CASS)and Commitment 8 This new condition monitoring program manages embrittlement of ASME Code Class 1 cast austenitic stainless steel components caused by thermal aging. The licensee identified those cast austenitic stainless steel components for which thermal aging embrittlement is potentially significant based on casting method, molybdenum content, and percent ferrite.

Commitment 8 specified:

  • Implement the thermal aging embrittlement of cast austenitic stainless steel aging management program.

The inspectors reviewed the aging management program basis document, implementing procedures, engineering evaluations, flaw tolerance evaluations and corrective action documents.

The inspectors determined that the licensee had two sets of components, reactor coolant loop elbows and reactor coolant pump bowls, in their reactor coolant system made of cast austenitic stainless steel. The components are SA-351 CF8M that the licensee determined were susceptible to thermal aging embrittlement. The licensee evaluated the ferrite content of components using the using Hulls Equivalent Factor Method from NUREG/CR-4513, Estimation of Fracture Toughness of Cast Stainless Steels During Thermal Aging in LWR Systems, revision 2. The inspectors determined that the component-specific flaw tolerance evaluations completed in accordance with ASME,Section XI demonstrated the elbow and pump bowls remain flaw tolerant through the end of the period of extended operation.

The inspectors confirmed the licensee completed the required commitments and performed the required evaluations associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(9) A.2.2.7 PWR Vessel Internals and Commitment 9 This new condition monitoring program manages the effects of age-related degradation mechanisms that are applicable to PWR reactor vessel internals components and implements the guidance in industry standards, which include:
  • Loss of material caused by wear;
  • Loss of fracture toughness caused by thermal aging and neutron irradiation embrittlement;
  • Change in dimension caused by void swelling or distortion; and
  • Loss of preload caused by thermal and irradiation-enhanced stress relaxation or creep.

The licensee applies the guidance of MRP-227, Materials Reliability Program:

Pressurized Water Reactor Internals Inspection and Evaluation Guidelines, Revision 1-A for selecting, inspecting, evaluating, and, if applicable, dispositioning non-conforming reactor vessel internals components.

Commitment 9 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, engineering evaluations, examination results, industry operating experience, work orders, and corrective action documents. The inspectors reviewed past inspection results that demonstrated the licensee implemented actions to manage the effects of aging of the reactor vessel internal components. The licensee replaced the originally installed Alloy X-750 guide tube support pins (split pins) with strain hardened (cold worked) 316 stainless steel pins in 1999 and 2006 for Units 1 and 2, respectively. During refueling outage1R20, the licensee performed ultrasonic evaluation of the full population of unit 1 baffle-former bolts that identified one bolt with an indication. As a conservative measure, the licensee replaced 61 bolts.

The licensee had not scheduled their 10-year core barrel inservice inspections and any associated MRP 227 inspections because the inspections would occur after the shutdown of each units 40-year license expiration. Because of the actions to extend their license, the licensee reinitiated the required inspections. The inspectors determined that, for unit 1, the licensee plans to perform the core barrel inservice inspection, review seven of the nine MRP 227 required inspections and perform clevis bolt inspections during refueling outage 1R25 in April 2025. The licensee has scheduled the baffle former assembly baffle-edge and baffle-former bolt inspections in refueling outage 1R26. For unit 2, the licensee plans to perform the core barrel inservice inspection, review the eight required MRP 227 inspections (unit 2 has no thermal shield) and perform clevis bolt inspections during refueling outage 2R25 in October 2025.

The inspectors determined that the replacement reactor heads will exceed 20 EFPY in 2034 for unit 1 and 2033 for unit 2. Once the reactor vessel heads exceed 20 EFPY the licensee plans to inspect the control rod drive mechanism thermal sleeves, as required.

The inspectors confirmed the licensee completed the required commitments, developed a program procedure, and scheduled the mandatory inspections within appropriate time frames to manage the effects of aging.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(10) A.2.2.8 Flow-Accelerated Corrosion and Commitment 10 This existing monitoring program manages wall thinning caused by flow accelerated corrosion and various erosion mechanisms. This program includes performing
(a) an analysis to determine critical locations,
(b) limited baseline inspections to determine the extent of thinning at these locations, and
(c) follow-up inspections to confirm the predictions or repairing or replacing components as necessary.

Commitment 10 specified:

Continue the flow-accelerated corrosion program with enhancements to:

  • Include piping, components, and piping elements susceptible to erosion wall-thinning mechanisms such as cavitation, flashing, droplet impingement, or solid particle impingement and include erosion as an aging mechanism for susceptible components.
  • Identify locations susceptible to erosion based on the extent of condition reviews in response to plant-specific and industry operating experience.

Include guidance from industry documents for potential damage locations, including cavitation erosion.

  • Trend wall thickness measurements at locations susceptible to erosion mechanisms to adjust the monitoring frequency and to predict the remaining service life for scheduling repairs. Evaluate results to ensure assumptions in the extent-of-condition review remain valid. If degradation results from operational alignments, then trending considers the number or duration of these occurrences. Perform periodic wall thickness measurements of replaced components until the effectiveness of corrective actions has been confirmed.
  • Control and independently update the plant predictive models by a second qualified flow-accelerated corrosion engineer.
  • Ensure long-term corrective actions to eliminate the cause of erosion mechanisms will consider adjusting operating parameters or changing component designs, and the effectiveness of these corrective actions will be verified. Continue periodic monitoring for any replaced components.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(11) A.2.2.9 Bolting Integrity and Commitment 11 This existing inspection program manages cracking, loss of material, and loss of preload for pressure retaining closure bolting. The program includes preload control, selection of bolting material, use of lubricants or sealants, and performance of periodic inspections for indication of aging effects consistent with industry and NRC guidance.

Commitment 11 specified:

Implement the bolting integrity aging management program, including enhancements to:

  • Procedures and/or specifications to minimize any future use of high strength bolts (yield strength greater than or equal to 150 ksi). If high strength bolts are used, bolting will be monitored for cracking, with volumetric examinations performed in accordance with ASME Code Section XI.
  • Explicitly ban the use of molybdenum disulfide on bolts.
  • Ensure the program is consistent with the listed industry guidelines and the additional recommendations of NUREG1339, Resolution of Generic Safety Issue 29: Bolting Degradation or Failure in Nuclear Power Plants, to prevent or mitigate degradation and failure of closure bolting.
  • Inspect pressure retaining closure bolting in piping systems that contain air or gas. Integrity of the bolted joint will be demonstrated by one of the following methods:
(a) perform inspections consistent with that of submerged closure bolting;
(b) visually inspection for discoloration when leakage would discolor the surfaces;
(c) monitor and trend pressure decay when the connection is located within an isolated boundary;
(d) perform soap bubble testing;
(e) use thermography testing when the fluid temperature is higher than ambient; or
(f) other inspection methods capable of detecting leakage for air or gas systems. At a minimum, in each 10-year interval, inspect a representative sample of at least 20 percent of the population (with the same material and environmental combination) at each unit, up to a maximum of 19.
  • Visually inspect a representative sample of submerged closure bolting for loss of material when bolt heads are made accessible and bolt threads when joints are disassembled. If opportunistic activities do not result in 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 specify 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 demonstrate that the pumps maintain sump levels.
  • Manage reactor coolant pump flange high strength bolting. Perform volumetric examinations in accordance with ASME Code Section XI. Specified bolting material properties may be used to determine if identified bolting exceeds the threshold to be classified as high strength.
  • Establish specific acceptance criteria when alternative inspections or testing is conducted for submerged closure bolting.
  • 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, additional inspections will be conducted if the acceptance criteria are not met. Use the corrective action program to determine the number of increased inspections; however, conduct no fewer than five additional inspections or 20 percent of each applicable material, environment, and aging effect combination, whichever is less. If these subsequent inspections do not meet acceptance criteria, conduct an extent of condition and extent of cause analysis to determine additional inspections required.

Inspect for any recurring degradation at both units to ensure corrective actions address the associated causes. 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.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(12) A.2.2.10 Steam Generators and Commitment 12 This existing inspection program manages the degradation of steam generator components including tubes, plugs, and sleeves.

Commitment 12 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(13) A.2.2.11 Open Cycle Cooling Water and Commitment 13 This existing preventive, mitigative, condition monitoring, and performance monitoring program manages hardening and loss of strength caused by elastomer degradation; loss of material caused by corrosion; and reduction of heat transfer caused by fouling for components in the auxiliary saltwater system. The licensee manages aging of component materials including carbon steel, cast iron, stainless steel, nickel alloys, copper alloys, cast austenitic stainless steel, ductile iron, and elastomers.

The licensee uses surveillance and control techniques to manage aging effects in auxiliary service water system components. Inspections detect signs of elastomer degradation, corrosion, and fouling. Heat exchanger testing verifies flow and heat transfer capability meet system design requirements.

Commitment 13 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, system flow tests, heat exchanger inspections and performance tests, eddy current examinations, coatings inspections, intake bay cleaning and coating activities, and corrective action documents.

The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(14) A.2.2.12 Closed Treated Water Systems and Commitment 14 This existing preventative and condition monitoring program manages aging effects related to: reduction of heat transfer caused by fouling; loss of material caused by general, pitting, crevice, galvanic, and microbiologically influenced corrosion; and cracking caused by stress corrosion cracking in chemistry controlled (treated) closed cooling water systems. This program includes the component cooling water, service cooling water, intake cooling water, and diesel engine jacket cooling water systems.

The licensee implements chemical treatments, including the use of corrosion inhibitors, to modify the chemical composition of the water to maintain the equipment functions. The diesel engine jacket cooling water systems will be visually inspected for the presence of corrosion during routine maintenance since there are no corrosion coupons.

Commitment 14 specified:

Continue the closed treated water systems aging management program, including enhancements to:

  • Periodically inspect the condition of installed corrosion coupons to determine if significant corrosion is occurring.
  • For components without corrosion coupons, visually inspect, report, and evaluate (if needed) exposed surfaces for evidence of loss of material, cracking, or fouling whenever the system boundary is opened. At a minimum, in each 10-year period, inspect a representative sample (20 percent of the population, up to a maximum of 25 components) of components by qualified personnel.

The inspectors reviewed the aging management program basis document, flow testing, coupon testing, diesel generator 18-month, 6-year, and 8-year maintenance activities, implementing procedures, closed treated water chemistry trends, and corrective action documents. The inspectors verified that the licensee maintained the chemistry with the required ranges and the systems had little corrosion. The inspectors determined that the licensee implemented controls in accordance with their exceptions that resulted in no adverse effects.

The licensee took three exceptions to the requirements specified in NUREG-1801, Generic Aging Lessons Learned (GALL) Report, revision 2, section XI.M21A, Closed Treated Water Systems. Specifically, the licensee took the following exceptions to the EPRI Closed Cooling Water Chemistry Guideline with the described basis:

Exception 1: The licensee does not monitor or analyze the diesel jacket water system chlorides, fluorides, and sulfates, as required by the EPRI closed treated water guideline. The licensee used demineralized water for makeup and ensured there were no pathways to introduce chlorides, fluorides, or sulfates to enter the jacket cooling water because it is cooled by the air-cooled diesel engine radiator. The licensee maintains chromates at a concentration level that prevents the onset of pitting corrosion caused by chlorides, fluorides, and sulfates.

Exception 2: The licensee performs quarterly monitoring of the diesel jacket water system control parameters instead of monthly. The licensee maintained a stable high chromate concentration that resulted in a powerful, protective oxide layer. Quarterly sampling reduced the amount of hazardous waste. The quarterly monitoring complies with the GALL report.

Exception 3: The licensee limits the maximum amount of Azole in (Tolytriazole/Nitrite/Molybdated) systems to 20 ppm maximum contrary to the recommended greater than 25 ppm in the EPRI closed treated water guideline. The licensee limits the amount of Azole to comply with their approved National Pollutant Discharge Elimination (NPDES) wastewater requirements.

The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(15) A.2.2.13 Inspection of Overhead Heavy Load and Light Load (Related to Refueling) Handling Systems and Commitment 15 This existing condition monitoring program manages loss of material and loss of preload for bolting for all cranes, trolley and hoist structural components, fuel handling equipment and applicable rails within the scope of license renewal. Visual inspections managed loss of material caused by corrosion of structural members and bolting, loss of materials caused by wear of rails, and loss of preload for bolted connections.

Commitment 15 specified:

Continue to implement the overhead heavy and light load handling systems aging management program, including procedure enhancements to specify that:

  • Visual inspections for loose bolts, missing or loose nuts, or other indications of loss of preload and cracking are performed for the containment dome service crane bolted connections.
  • 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 appropriate standards.
  • All visual indications of aging are evaluated for associated system/component adjustment, repair, or replacement, as necessary, in accordance with ASME B30.2, 2005 Edition, or other appropriate standards.
  • System/component repairs are performed in accordance with ASME B30.2, 2005 Edition, or other appropriate standards.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(16) A.2.2.14 Fire Protection and Commitment 16 This existing condition monitoring program manages loss of material for fire rated doors, fire dampers, and the carbon dioxide fire suppression system; cracking, spalling, and loss of material for fire barrier walls, ceilings, and floors; and hardness and shrinkage of fire barrier penetration seals. The program includes inspections and testing to ensure component integrity and functionality.

Commitment 16 specified:

  • Continue the fire protection aging management program and to enhance the program to include qualification criteria for individuals performing inspection of fire dampers and fire doors.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(17) A.2.2.15 Fire Water Program and Commitment 17 This existing condition monitoring program manages loss of material and flow blockage due to corrosion, including MIC, RIC, or fouling; flow blockage because of fouling; and loss of integrity for internal coatings for water-based fire protection systems. Components in the program include fire hose stations, standpipes, piping (above ground, buried and underground), piping components, hydrants, fire pump casings, valve bodies, fittings, spray nozzles, fire hoses, sprinklers, sprinkler heads, and the fire water storage tanks, including coatings. The program includes the internal surfaces of water-based fire protection system piping that is normally drained, such as dry-pipe or pre-action sprinkler system piping and valves.

Commitment 17 specified:

Continue the fire water system aging management program, including enhancements to:

  • Require that strainers and screens in the makeup water system that support the fire water system they are cleaned and inspected every 24 months.
  • Test/replace sprinkler heads in accordance with NFPA 25, section 5.3.1.
  • 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) Test eight hose stations in the turbine building to represent one hose station per elevation for each unit;
(2) Test two hose stations in the auxiliary building to represent one hose station for each unit;
(3) Test two hose stations in the containment buildings to represent one hose station for each unit; and
(4) Test one hose station in the common intake structure.
  • Perform and trend main drain testing every 18-months, include the 10 percent acceptance criteria from NFPA 25, section 13.2.5.
  • Maintain hydrant flow for not less than 1 minute in accordance with NFPA 25, section 7.3.2.2.
  • Perform at least one flow test of the buried portions of the fire water system in accordance with NPFA 25, section 7.3.
  • Ensure interior and exterior surface inspections of the fire water storage tank include the following criteria:
(1) Inspect surfaces every five years, consistent with NFPA 25, section 9.2.6. Enter degradation not meeting acceptance criteria into the corrective action program and evaluate to determine whether additional actions required. Record via camera, take nodule measurements, and record the corrosion depth;
(2) Use appropriate tools to adequately conduct the inspection;
(3) Personnel will be qualified in accordance with ASTM D7108-05, Standard Guide for Establishing Qualifications for a Nuclear Coatings Specialist. Acceptance criteria and corrective actions will meet LR-ISG-2013-01, appendix C, New Program: Gall Report AMP XI.M42, Internal Coatings/Linings for In-Scope Piping, Piping Components, Heat Exchangers, and Tanks; and
(4) Perform a one-time ultrasonic test inspection of the tank bottom prior to November 2, 2024.
  • Test the turbine building deluge valves consistent with NFPA 25. Every three years (every second visual inspection) test the downstream dry piping with air, smoke, or other medium.
  • Clean deluge system nozzles and retest the respective systems if obstructions are identified during flow testing.
  • Update existing procedures to:

1. Inspect wet sprinkler systems internally using a method to detect flow

blockage caused by fouling in addition to loss of material as described in NFPA 25, section 14.2;

2. Investigate obstructions consistent with NFPA 25, section 14.3; and

3. Not allow external wall thickness measurements in lieu of prescribed

internal visual examinations (or flow test) for managing flow blockage.

  • Create a new procedure to implement the following activities:

1. Prior to November 2, 2024, after identifying any portions of the normally

dry fire water deluge system piping and periodically wetted, but unable to be drained, perform either:

(a) a flow test or flush sufficient to detect potential flow blockage, or
(b) a 100 percent internal surface inspection on those portions unable to be drained. Conduct this activity in each 5-year period. If the results are acceptable and the segment is not subsequently wetted, no further augmented tests or inspections are necessary.

2. During each 5-year period, volumetrically inspect 20 percent of the

identified portion so that after 25 years, 100 percent has been volumetrically tested. Obtain measurements to ensure each potential degraded condition can be identified (e.g., general corrosion, microbiologically influenced corrosion).

3. If the turbine building deluge system spray piping becomes wetted,

determine if any portions of the spray piping cannot be drained or water collects, then apply the flow testing and inspection criteria for normally dry wet sprinkler systems.

  • Include the following requirements for monitoring recurring internal corrosion:

1. Monitor for loss of material using ultrasonic testing examinations. Select

representative inspection sites based on pipe configuration, flow conditions, and operating history (known degradation or leakage);

2. Compare ultrasonic test measurements to the nominal pipe wall thickness

(for initial measurements) or to previous thickness measurements to determine the estimated time to reach minimum wall thickness;

3. If results do not meet acceptance criteria or reduced wall thickness

greater than 50 percent, enter the issue into the corrective action program.

Consider multiple locations in the structural integrity technical evaluation of the pipe;

4. Evaluate the effectiveness of the corrective actions taken to address the

previous instances. Annually, conduct a minimum of five ultrasonic test examinations until the rate of corrosion no longer meets the definition for recurring internal corrosion. For multiple deficiencies in an annual inspection period, perform five additional examinations over the following 12-month period for each occurrence identified. The total number of inspections need not exceed 25 per year;

5. Enter any newly identified recurring internal corrosion deficiency into the

corrective action program; and

6. Perform internal visual inspections during opportunistic inspections.

7. Require trending of test data.

8. Require supplemental volumetric testing when early indications of wall

thinning are identified to ensure that minimum wall thickness is maintained.

9. Remove and inspect water system mainline strainers every 5 years in

accordance with NFPA 25, section 10.2.1.7.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(18) A.2.2.16 Aboveground Metallic Tanks and Commitment 18 This new program manages cracking and loss of material for the condensate storage tank, the refueling water storage tank, and the transfer tank. This program requires that the licensee inspect the tanks for damage, conduct thickness measurements of the walls of the tanks, and measure the thickness of the bottom of the tanks Commitment 18 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(19) A.2.2.17 Fuel Oil Chemistry and Commitment 19 This existing mitigation and condition monitoring program manages loss of material in tanks, components, and piping exposed to diesel fuel oil. The program includes periodic removal of accumulated water found in tanks, periodic draining, cleaning, and inspection of fuel oil storage tanks.

Volumetric examinations are used to assess identified degradation or where internal visual inspection is not possible. Fuel oil quality is maintained by monitoring and controlling fuel oil contamination. Technical specifications provide limits for both new and stored fuel oil for use in the emergency diesel generators. Manufacturer fuel oil quality recommendations are used for the portable diesel driven fire water pump tanks, portable diesel electric generator fuel oil tanks, and the portable caddy fuel oil tanks.

Commitment 19 specified:

Continue the fuel oil chemistry aging management program, including enhancements to:

  • 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.
  • Drain, clean, and visually inspect the internal surfaces of the in-scope tanks every 10 years. Volumetrically inspect the tanks if degradation is observed or if visual inspection is not possible.
  • Add biocide to the portable diesel electric generator and caddy fuel oil tanks.
  • Periodically sample the fuel oil stored in the fuel oil tanks for the portable tanks. Perform multilevel samples or, if tank design does not allow, take a sample from the lowest point in the tank. If accumulated water is found, remove using the corrective action program.
  • Sample new fuel oil prior to adding to the in-scope tanks. Annually monitor and trend water and sediment content, total particulates, and the levels of microbiological organisms for the portable in-scope equipment fuel oil tanks.

Establish acceptance in accordance with industry standards and equipment manufacturer or fuel oil supplier recommendations.

  • Credit the fuel oil storage tank inspections as a one-time sample if the material and environment are the same.
  • Control trending of water and particulate levels in accordance with technical specifications and procedures for the emergency diesel generator diesel fuel oil storage and day tanks.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors observed a chemistry sample of a diesel fuel storage tank, in addition to walking down the unit 2 emergency diesel rooms and portable caddy fuel oil tanks.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(20) A.2.2.18 Reactor Vessel Surveillance and Commitment 20 This existing surveillance and testing program manages (monitors) loss of fracture toughness for the reactor vessel caused by exposure to neutron fluence. The licensee had removed and tested surveillance capsules containing specimens of the limiting beltline material and associated weld metal and weld heat affected zone metal. The program provides sufficient data for monitoring irradiation embrittlement at the end of the period of extended operation and determines the need for any operating restrictions on the inlet temperature, neutron spectrum, and neutron flux.

Commitment 20 specified:

The inspectors reviewed the aging management program basis document, engineering evaluations, drawings, implementing procedures, and corrective action documents. The inspectors determined that the licensee had analyses for their pressure temperature limits report that supported operation of unit 1 until refueling outage 1R25. The licensee indicated that they would update their pressure-temperature limits report prior to startup from refueling outage 1R25 that will support operation through the period of extended operation. The licensee submitted a license amendment request by Letter DCL-24-018, Revision to Technical Specification 5.6.6,

'Reactor Coolant System (RCS) Pressure and Temperature Limits Report (PTLR)',

dated February 28, 2024, to permit the use of a newer, more advanced neutron fluence calculational methodology to support determining the reactor coolant system pressure and temperature limits. The licensee requested approval for using the revised methodology by February 28, 2025.

On July 20, 2023, NRC approved removal of capsule B from unit 1 during refueling outage 1R24 or 1R25. The licensee will analyze capsule B to ensure that the neutron fluence at the end of the period of extended operation does not exceed one to two times the peak reactor vessel wall neutron fluence. The inspectors determined that the licensee had withdrawn unit 2 capsule V in 1999. This capsule had a predicted end-of-life exposure of 52.51 EFPY of operation. Although less than 54 EFPY, the inspectors confirmed that this exposure remained within the 20 percent specified in Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(21) A.2.2.19 One-Time Inspection and Commitment 21 This new program conducts visual examinations of components in the water chemistry, fuel oil chemistry, and lubricating oil analysis programs to verify the effectiveness of the aging management activities performed by those programs. The licensee selected a representative sample size of 20 percent of the population (defined as components having the same material, environment, and aging effect combination) or a maximum of 25 components. This sample will be based on criteria such as the longest service period, most severe operating conditions, lowest design margins, lowest or stagnant flow conditions, high flow conditions, and highest temperature.

Commitment 21 specified:

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(22) A.2.2.20 Selective Leaching and Commitment 22 This new one-time condition monitoring program evaluates whether loss of material has been caused by selective leaching for gray cast iron, ductile iron, and copper alloys (except for inhibited brass) containing greater than 15 percent zinc or greater than 8 percent aluminum components that are exposed to raw water, treated water, closed cooling water, or ground water.

The program includes visual inspection and hardness measurement or other industry-accepted mechanical inspection techniques such as destructive testing, scraping, or chipping of selected components to determine whether selective leaching affects the component intended functions. If the licensee identifies selective leaching, the licensee will expand the sample to include locations for follow-up examinations or evaluations.

Commitment 22 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, examination sheets, destructive examination reports, engineering evaluations, and corrective action documents. The inspectors reviewed the sampling plan and technical basis document that established the sample populations and evaluation samples for each material and environment combination.

The inspectors determined for identified selective leaching the licensee performed destructive examinations and engineering evaluations that demonstrated the components would have remained functional through the end of the period of extended operation.

At the time of this inspection, the licensee had not completed all the selective leaching inspections and examinations. The licensee indicated that they would complete their initial sample inspections prior to the expiration of the current operating licenses, which are November 2, 2024, for Unit 1 and August 26, 2025, for Unit 2. As described in letter DCL-23-020, Responses to NRC Questions Regarding Diablo Canyon Power Plant License Renewal Efforts, dated March 17, 2023, the licensee will complete any needed follow-up or expansion inspections by December 1, 2028.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(23) A.2.2.21 One-time Inspection of ASME Code Class 1 Small Bore-Piping and Commitment 23 This new one-time inspection program provides assurance that aging of ASME Code Class 1 small-bore piping is not occurring, or that the aging effects are not significant, such that a plant-specific aging management program is not warranted.

Commitment 23 specified:

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(24) A.2.2.22 External Surfaces Monitoring of Mechanical Components and Commitment 24 This new condition monitoring program includes inspection for corrosion and material wastage (loss of material), leakage from or onto external surfaces (loss of material),worn, flaking, or oxide-coated surfaces (loss of material), corrosion stains on thermal insulation (loss of material), protective coating degradation (cracking, flaking, and blistering), and leakage for detection of cracks on the external surfaces of stainless steel components exposed to an air environment containing halides.

Commitment 24 specified:

  • Implement the external surfaces monitoring of mechanical components aging management program.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(25) A.2.2.23 Flux Thimble Tube Inspection and Commitment 25 This existing inspection program manages loss of material caused by to wear by performing wall thickness eddy current testing of all flux thimble tubes that form part of the reactor coolant system pressure boundary during each refueling outage.

Commitment 25 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(26) A.2.2.24 Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components and Commitment 26 This new condition monitoring and testing program manages cracking, loss of material, hardening and loss of strength. The program also manages loss of coating integrity on components with an internal coating. The licensee inspects internal surfaces of metallic piping, piping components, ducting, heat exchanger components, tanks, polymeric and elastomeric components, and other components that are exposed to plant indoor air, outdoor air, ventilation atmosphere, atmosphere/weather, condensation, air with borated water leakage, diesel exhaust, lubricating oil, fuel oil, and water system environment not managed by the open-cycle cooling water system, closed treated water system, fire water system, and water chemistry aging management programs.

Commitment 26 specified:

Implement the inspection of internal surfaces in miscellaneous piping and ducting components aging management program, including the following to:

  • Replace domestic water system copper alloy piping with a corrosion-resistant material or install shielding to prevent adverse spatial interactions upon failure.
  • Perform additional recurring internal corrosion inspections if any sample-based inspections in the saltwater system do not meet the acceptance criteria.

The number of inspections will be increased; however, no fewer than five additional inspections or 20 percent of each applicable material, environment, and aging effect combination are conducted for each inspection that did not meet acceptance criteria, whichever is less.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(27) A.2.2.25 Lubricating Oil Analysis and Commitment 27 This existing program manages the quality of lubricating and hydraulic oil in mechanical systems to maintain contaminants within specified limits. The program provides for sampling and analysis to maintain lubricating and hydraulic oil contaminants, primarily water and particulates, within acceptable limits, thereby preserving an environment that is not conducive to loss of material or reduction of heat transfer. Testing activities include sampling analysis of lubricating and hydraulic oil for contaminants that could indicate in-leakage and corrosion product buildup.

Commitment 27 specified:

Continue the lubricating oil analysis aging management program, including the following enhancements:

  • Periodically sample and analyze to maintain oil contaminants, primarily water and particulates, within acceptable limits.
  • Sampling for water, particles and other parameters to detect evidence of moisture or excessive corrosion contamination.
  • Include acceptance criteria for lubricating and hydraulic oil associated with the in-scope equipment, Derive acceptance criteria for lubricating and hydraulic oil analysis from equipment vendor manuals, ASTM D 6224-02, Standard Practice for In-Service Monitoring of Lubricating Oil for Auxiliary Power Plant Equipment, and plant-specific operating experience.
  • Monitor water and particles in lubricating and hydraulic oil to check for unusual trends.
  • Clarify that phase-separated water in any amount is not acceptable.
  • When action limits are reached or exceeded evaluate and address.

The inspectors reviewed the aging management program basis document, implementing procedures, oil analysis reports, maintenance records, and corrective action documents. The inspectors walkdown the oil storage warehouse and interviewed chemistry and maintenance personnel. In addition, the inspectors observed maintenance perform an oil analysis collection on the electro-hydraulic system for turbine control valves.

The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(28) A.2.2.26 Buried and Underground Piping and Tanks and Commitment 28 This existing condition and performance monitoring program manages cracking, loss of material, and change in surface conditions of buried and underground components in the auxiliary saltwater system, diesel generator fuel transfer system, fire protection system, and the makeup water system. The program includes preventive measures (i.e., coatings, backfill quality, and cathodic protection), inspections, and, as appropriate, performance monitoring activities. Visual inspections monitor the condition of protective coatings and wrappings and directly assess the surface condition of components with no protective coatings or wraps. Evidence of wall loss beyond minor scale observed during visual inspections of buried piping will require a supplemental surface examination and/or volumetric non-destructive testing. The program includes opportunistic inspection of buried piping and tanks as they are excavated or on a planned basis if opportunistic inspections have not occurred.

Commitment 28 specified:

Continue the buried and underground piping and tanks program, including enhancements to:

  • Close valve MU-0-881, Water Supply to Firing Range 2nd Off (Alt. Supply), for any pressure boundary failure further along the flow path or when the raw water storage reservoirs provide long-term cooling.
  • Install impressed current cathodic protection for remaining portions of the buried auxiliary saltwater system discharge and supply piping in contact with soil.
  • Revise the backfill procedure to include the requirements related to backfill material quality.
  • Include qualification requirements for individuals evaluating coating degradation.
  • Align the inspection scope with LR-ISG-2015-01, Changes to Buried and Underground Piping and Tank Recommendations, Table XI.M41-2, Preventive Actions for Buried Piping and Tanks.
  • Require an annual firewater system flow test.
  • Specify that for steel components, where the acceptance criteria for 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, Revised AMP XI.M41, Buried and Underground Piping and Tanks, Section 6.m.
  • Revise program and backfill procedures to include the following: Cracks in controlled low strength material backfill that could admit groundwater are not acceptable. Where significant coating damage caused by non-conforming backfill is identified, evaluate the extent of condition to ensure the as-left condition will not lead to further degradation.
  • Include the corrective actions recommended by LR-ISG-2015-01, appendix B, section 7.

The inspectors reviewed the aging management program basis document, implementing procedures, inspections performed for each in-scope system in accordance with the guidance for NEI 09-14, Guideline for the Management of Underground Piping and Tank Integrity, revision 4, planned commitment changes, and corrective action documents. The inspectors determined that the licensee planned the following changes to their commitments as originally submitted:

  • Revise the fifth bullet to add and Section 4.c at the end of the sentence.
  • Add enhancements to the buried piping procedure to:

o Specify that the limiting critical potential should not be more negative than -1200 mV.

  • Include the following acceptance criteria:

o Blistering, gouges, or wear of nonmetallic piping is evaluated.

o Measured wall thickness projected to the end of the period of extended operation meets minimum wall thickness requirements.

o Manage indications of cracking in metallic pipe with the corrective actions program.

o Cementitious piping may exhibit minor cracking and spalling provided there is no evidence of leakage, exposed or rust staining from rebar or reinforcing hoop bands.

The inspectors selected the last inspection performed by the licensee for each system for review from their buried piping asset management plant and determined that the licensee had not identified any issues. The inspectors determined that the licensee planned to implement their baseline buried piping inspections for each buried system prior to December 1, 2028, as described in Letter DCL-23-020, Responses to NRC Questions Regarding Diablo Canyon Power Plant License Renewal Efforts, dated March 17, 2023. Subsequent inspections will be performed during the first 10 years of the period of extended of operation and at a 10-year frequency thereafter.

At the time of this inspection, the licensee had not incorporated their commitments and enhancements into their program. The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(29) A.2.2.27 Internal Coatings/Linings for In-Scope Piping, Piping Components, Heat Exchangers, and Tanks and Commitment 29 This new program consists of periodic visual inspections of internal coatings/linings exposed to closed-cycle cooling water, raw water, treated water, treated borated water, waste water, fuel oil, and lubricating oil. Where the visual inspection of the coated/lined surfaces determines that the coating/lining is deficient or degraded, physical tests are performed, where physically possible, in conjunction with the visual inspection.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

Commitment 29 specified:

  • Implement the internal coatings/linings for in-scope piping, piping components, heat exchangers, and tanks aging management program. Perform initial coatings/linings inspections and follow-up periodic inspections.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(30) A.2.2.28 ASME Section IWE and Commitment 30 This existing condition monitoring program manages loss of material, and loss of sealing, and leakage through containment and provides aging management of the steel liner of the concrete containment building (including the containment liner plate and its integral attachments), containment hatches and airlocks, and pressure-retaining bolting.

Commitment 30 specified:

Continue the ASME Section IWE aging management program with enhancements to:

  • Identify the listed documents to form a basis for the bolting program.
  • Prohibit the use of molybdenum disulfide as a lubricant for structural bolts.
  • Ensure replacement and maintenance activities for structural bolting include appropriate preload and proper tightening (torque or tension) as recommended in EPRI documents, ASTM standards, AISC Specifications, and in Section 2 of RCSC publication "Specifications for Structural Joints Using ASTM A325 or A490 Bolts," as applicable.
  • Inspect non-coated surface examinations for arc strikes.
  • Require a one-time volumetric examination of metal liner surfaces that are inaccessible from one side, only if triggered by plant-specific operating experience. The trigger includes any plant-specific occurrence of measurable metal liner corrosion (material loss exceeding 10 percent of nominal) initiated on the inaccessible side or areas.
  • Perform a one-time inspection using methods capable of detecting cracking caused by stress corrosion cracking of a representative sample, which would be 2 stainless steel penetrations or dissimilar metal welds associated with high-temperature (above 140 F) stainless steel piping systems in frequent use. These inspections are intended to confirm the absence of stress corrosion cracking. If cracking is detected, additional inspections will be conducted in accordance with the corrective action process. Periodic inspection of subject penetrations with dissimilar metal welds for cracking may be added to this program, depending on the inspection results.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(31) A.2.2.29 ASME Section IWL and Commitment 31 This existing condition monitoring program manages aging of the reinforced concrete containment building in accordance with ASME Section XI, Subsection IWL.

Commitment 31 specified:

Continue the ASME Section IWL aging management program with enhancements to:

  • Evaluate examination results that do not meet the acceptance standards and document the results in an engineering report to identify the cause and the extent, nature, and frequency of additional examinations. Include whether the concrete containment is acceptable without repair and, if repair is required, the extent, method, and completion date of the repair.
  • Update the acceptance criteria guidance to be consistent with ACI 349.3R-02.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(32) A.2.2.30 ASME Section IWF and Commitment 32 This existing condition monitoring program manages loss of material, cracking, and loss of mechanical function that could result in loss of intended function for supports for Class 1, 2, and 3 piping and components.

Commitment 32 specified:

Continue the ASME Section IWF aging management program with enhancements to:

  • Prohibit the use of molybdenum disulfide as a lubricant for structural bolts.
  • Enhance bolting practice procedures to explicitly identify the listed documents as a portion of the basis for the bolting program.
  • 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 and include appropriate preload and proper tightening (torque or tension) as recommended in the listed documents.
  • Monitor high-strength structural bolting (measured yield strength greater than or equal to 150 ksi), using volumetric examination comparable to applicable code categories in addition to the VT-3 examination.
  • Enter and evaluate any adverse results of high-strength structural bolting examinations into the corrective action program.
  • Include the following conditions as unacceptable unless the technical basis for their acceptance is documented:
(a) Loss of material caused by corrosion or wear, which reduces the load bearing capacity of the component support;
(b) Debris, dirt, or excessive wear that could prevent or restrict sliding of the sliding surfaces as designed;
(c) Cracked or sheared bolts, including high-strength bolts, and anchors; and
(d) Arc strikes, weld splatter, paint scoring, roughness, or general corrosion on close tolerance machined or sliding surfaces.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(33) A.2.2.31 10 CFR Part 50, Appendix J and Commitment 33 This existing testing program manages loss of sealing, leakage through containment, loss of leak tightness, and loss of material. The program provides for detection of pressure boundary degradation caused by aging effects such as loss of leakage tightness, loss of material, cracking, loss of sealing, or loss of preload in various systems penetrating containment. The program also provides for detection of age-related degradation in material properties of gaskets, seals, expansion bellows, and flexible seal assemblies for the containment pressure boundary access points.

Commitment 33 specified:

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(34) A.2.2.32 Masonry Walls and Commitment 34 This existing condition monitoring program includes inspections to detect age-related degradation including shrinkage, separation, gaps, loss of material, and cracking for in-scope masonry walls. Visual inspections monitor for significant cracking, coating damage, loss of material, missing or broken blocks, deterioration of penetrations, discoloration efflorescence, separation, and shrinking.

The program includes masonry walls in the auxiliary and turbine buildings that support safety-related piping or equipment, or whose failure could prevent a safety-related system from performing its safety function. The fire protection aging management program evaluates that fire protection function of masonry walls considered fire barriers.

Commitment 34 specified:

Continue the masonry walls program, including enhancements to:

  • Monitor for evidence of shrinkage and/or separation of masonry walls and gaps between the supports and masonry walls that could impact the intended function.
  • Require inspections to be performed at least every five years for masonry walls.

The inspectors reviewed the aging management program basis document, implementing procedures, design information, drawings, prior inspections, and corrective action documents. The inspectors could not review the baseline inspection results since the licensee had not completed their review at the time of this inspection. The inspectors determined that the licensee had not included their commitments in procedure AWP E-016, Inspection Guide - Maintenance Rule Structural Monitoring Programs - Civil, but tracked the action using SAPN 51204892, section 10 of the aging management program basis document, and chapter 7 of the aging management binder.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(35) A.2.2.33 Structures Monitoring and Commitment 35 This existing condition monitoring program manages the condition of in-scope structures and structural supports that are not covered by other structural aging management programs. The program implements the requirements of 10 CFR 50.65, including the implementing industry and regulatory documents as described in updated final safety analysis report section 13.5.2.19.

Commitment 35 specified:

Continue the structures monitoring program, including enhancements to:

  • Notify appropriate personnel to allow them to decide whether to perform an opportunistic inspection whenever opening a pull box.
  • Add embedments, jet impingement shields, racks, and sliding surfaces to the scope.
  • Include appropriate preload and proper tightening (torque or tension) for structural bolting replacement and maintenance activities as recommended in listed industry standards and to explicitly prohibit the use of molybdenum disulfide as a lubricant for structural bolts.
  • Monitor groundwater samples at least every five years for pH, sulfates, and chlorides, including seasonal variations, and assess the impact of changes on below grade concrete.
  • Monitor accessible sliding surfaces for indication of significant loss of material caused by wear or corrosion, debris, or dirt and specify the acceptance criteria that could restrict or prevent sliding of the surfaces as required by design.
  • Conduct a one-time video inspection of the Unit 2 spent fuel pool leak chase within one year prior to August 26, 2025.
  • Monitor all structures on a frequency not to exceed 5 years upon entering the period of extended operation.
  • Conduct a baseline inspection of all safety and non-safety related concrete elements in accordance with ACI 349.3R-02, Evaluation of Existing Nuclear Safety-Related Concrete Structures, acceptance criteria.
  • Align the inspector qualifications with the guidance in ACI 349.3R-02.
  • Specify that structural sealants remain acceptable if the observed loss of material, cracking, and hardening will not result in loss of sealing.

The inspectors reviewed the aging management program basis document, implementing procedures, drawings, inspection reports, planned commitment changes, and corrective action documents. The inspectors determined that the licensee planned the following changes to their commitments as originally submitted:

  • change the one-time video inspection to a periodic inspection (bullet 6),
  • perform rodding/snaking of all Units 1 and 2 SFP leak chase tell-tale drains to identify potential blockages prior to the period of extended operation.

Subsequent periodic tell-tale drain internal inspections will be performed based on monitoring and trending tell-tale drain data for indication of potential blockage,

  • add a periodic inspection requirement as follows SFP leak chase tell-tale sampling frequency, parameters and acceptance criteria will be enhanced consistent with site operating experience and EPRI 3002007348, Aging Management for Leaking Spent Fuel Pools.

Add these enhancements to the structures monitoring program:

  • Provide guidance for identifying and managing aging of fiberglass roofing panels.
  • For parameters monitored; add structural sealants to scope enhancement.
  • Manage the effects of aging caused by interaction between the spent fuel pool and transfer canal leakage and adjacent reinforced concrete.
  • Evaluate industry and site-specific operating experience related to reactor cavity and refueling canal liner leaks to determine appropriate inspection and maintenance activities for the reactor cavity and refueling canal.

The licensee began performing site wide inspections to obtain baseline data prior to entering the period of extended operation. The licensee had not completed the inspections and issued the inspection reports at the time of this inspection. The licensee initiated SAPN 51204892 to track revisions to procedure AWP E-016, Inspection Guide - Maintenance Rule Structural Monitoring Programs - Civil, revision 12, that will incorporate the commitments for the structures monitoring, masonry walls, and water control structures aging management programs.

The inspectors determined that the licensee had not included their commitments in procedure AWP E-016 but tracked the action using SAPN 51204892, section 10 of the aging management program basis document, and chapter 7 of the aging management binder.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(36) A.2.2.34 RG 1.127, Inspection of Water-Control Structures Associated with Nuclear Power Plants and Commitment 36 This existing condition monitoring program manages cracking, movement (e.g.,

settlement, heaving, deflection), loss of material, loss of form, loss of bond, loss of strength, and increase in porosity and permeability caused by extreme environmental conditions, and the effects of natural phenomena on water-control structures.

Although not committed to Regulatory Guide 1.127, Inspection of Water-Control Structures Associated with Nuclear Power Plants, the program includes all structural components within the scope of license renewal addressed by the regulatory guides, as well as their attributes. The scope includes monitoring of structural steel and structural bolting associated with water-control structures, and miscellaneous steel (e.g., bar racks).

The water-control structures included in this aging management program include the:

intake structure, discharge structure, circulating water conduits, earth slopes over the auxiliary saltwater pipes, wave protection measures over the auxiliary saltwater pipes and electrical conduits, east and west breakwaters, and raw water reservoirs.

Commitment 36 specified:

Continue the water control structures program, including enhancements to revise implementing procedures to:

  • Include miscellaneous steel (e.g., bar racks) for water control structures.
  • Specify:
(1) Structural bolting replacement and maintenance will include appropriate preload and proper tightening (torque or tension) as recommended in the listed industry standards; and
(2) Molybdenum disulfide will not be used.
  • Monitor structural concrete for movements (e.g., heaving, deflection),conditions at junctions with abutments and embankments, loss of material, and increase in porosity and permeability.
  • Develop the requirements for future discharge conduit inspections 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).
  • Align the inspector qualifications with the guidance in ACI 349.3R-02.
  • Perform baseline inspections of all concrete water-control structures in accordance with ACI 349.3R-02 acceptance criteria.

The inspectors reviewed the aging management program basis document, implementing procedures, design information, drawings, prior inspections, and corrective action documents. The inspectors determined that the licensee had completed detailed inspections of their water control structures every 5 years. The inspections demonstrated no blockage resulted from degraded concrete and determined that little degradation had occurred from one inspection to another. The inspectors could not review the license renewal baseline inspection results since the licensee had not completed their review at the time of this inspection.

The inspectors determined that the licensee had not included their commitments in procedure AWP E-016 but tracked the action using SAPN 51204892, section 10 of the aging management program basis document, and chapter 7 of the aging management binder.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(37) A.2.2.35 Protective Coating Monitoring and Maintenance and Commitment 37 This existing condition monitoring program manages the condition of the Service Level I coatings inside containment so that the intended functions of post-accident safety systems that rely on water recycled through the containment sump/drain system are maintained.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

Commitment 37 specified:

  • Continue the protective coatings monitoring and maintenance aging management program, including enhancement to specify performing a pre-inspection review of the previous two monitoring reports.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, and corrective action documents. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(38) A.2.2.36 Insulation Material for Electric Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements and Commitment 38 This new program provides reasonable assurance that the intended functions of insulation material for electrical cables and connections that are not subject to the environmental qualification requirements and exposed to adverse localized environments (temperature, radiation, or moisture) are maintained consistent with the current license basis. An adverse localized environments exists in a limited plant area that is significantly more severe than the plant design basis environment for the cable or connections insulation material.

Commitment 38 specified:

  • Implement the insulation material for electrical cables and connections not subject to environmental qualification requirements aging management program.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(39) A.2.2.37 Insulation Material for Electrical Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Used in Instrumentation Circuits and Commitment 39 This existing program manages the aging effects of the cables and connections used in instrumentation circuits with sensitive, high-voltage, low-level current signals within the nuclear instrumentation and radiation monitoring systems.

Commitment 39 specified:

Continue the insulation material for electrical cables and connections not subject to environmental qualification requirements used in instrumentation circuits aging management program, including enhancements to:

  • Develop procedures for the cables and connections used in nuclear instrumentation channels (source, intermediate, and power ranges).
  • Specify the parameters that require monitoring for indications of age-related degradation for nuclear instrumentation channels.
  • Develop procedures for calibration/surveillance tests of radiation monitors to require evaluating the test results and to determine whether the associated circuits remain functional. Complete baseline calibration/surveillance test results for each unit prior to the license expiration and at least every 10 years thereafter. Review calibration/ surveillance results that do not meet acceptance criteria for aging effects.
  • Implement cable system testing for the nuclear instrumentation monitors using a proven method for detecting deterioration of the insulation system. Complete baseline cable insulation system testing for nuclear instrumentation monitors for each unit prior to the license expiration and at least every 10 years thereafter.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(40) A.2.2.38 Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements and Commitment 40 This existing program manages the aging effects of inaccessible power cables (greater than or equal to 400 volts) located in conduit, cable trenches, cable troughs, duct banks, and pull boxes or directly buried in soil and potentially exposed to adverse localized environments caused by significant moisture. Significant moisture is defined as periodic exposures to moisture that last more than a few days (e.g., cable wetting or submergence in water).

Commitment 40 specified:

Continue the inaccessible power cables not subject to environmental qualification requirements aging management program, including the following enhancements to:

  • Ensure procedures implement actions to manage aging of inaccessible and underground in-scope power cables (greater than or equal to 400 volts).
  • Enhance maintenance plans to require:
(1) annual inspection of susceptible pull boxes for water accumulation, and
(2) for submerged cables (i.e., cable exposed to significant moisture), corrective actions to keep the cable dry, assess cable degradation, and determine the cause of water accumulation.
  • Perform one time inspection of pull boxes, which will review for excessive drooping or sagging of cables and for visible indications of damage or degradation of cables and their supports.
  • Enhance maintenance plans to require:
(1) inspecting the intake structure pull boxes every refueling outage, inspect accessible conduit ends for water collection and cables and cable support structures for visible signs of degradation and
(2) an engineering evaluation to assess cable degradation and to determine the cause of water accumulation for cables found submerged.
  • Enhance maintenance plans to test sump alarm features annually prior to the rainy season.
  • Implement testing of power cables to assess the condition of cable insulation, using a proven test for detecting deterioration caused by wetting or submergence. Trend test results to determine the rate of cable insulation degradation. More frequent testing may occur based on test results and operating experience.
  • Define acceptance criteria for pull box inspections and cable testing The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.
(41) A.2.2.39 Metal Enclosed Bus and Commitment 41 This existing program manages aging of in-scope nonsegregated phase and isolated phase buses. Specifically, this program manages the degradation for electrical bus bar bolted connections, bus bar insulation, bus bar insulating supports, bus enclosure assemblies (internal and external), and elastomers. The licensee evaluates the effects of loose connections, embrittlement, cracking, melting, swelling, or discoloration of insulation, loss of material of bus enclosure assemblies, hardening of boots and gaskets, and cracking of internal bus supports to ensure the intended function remains.

Commitment 41 specified:

  • Continue the metal enclosed bus aging management program, including an enhancement to formalize the existing inspection and testing of the metal enclosed buses.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(42) A.2.2.40 Electrical Cable Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements and Commitment 42 This new one-time program manages the effects of increased resistance of connections caused by thermal cycling, ohmic heating, electrical transients, vibration, chemical contamination, corrosion, and oxidation. The program requires testing a representative sample of electrical connections prior to the period of extended operation to identify whether the existing preventive maintenance program is effective such that a periodic inspection program is not required. Testing may include thermography, contact resistance testing, or other appropriate testing methods without removing the connection insulation.

Commitment 42 specified:

  • Implement the electrical cable connections not subject to environmental qualification requirements aging management program.

The inspectors reviewed the aging management program basis document, implementing procedures, completed work activities, electrical testing inspection reports, and corrective action documents. The inspectors previously observed cable connection testing during the unit 2 outage inspection. The inspectors interviewed the electrical maintenance personnel and program owner. The inspectors confirmed the licensee completed the required commitments and implemented the procedures associated with this program prior to the period of extended operation.

Based on the review of the procedures, records, and discussions with licensee personnel, the inspectors did not identify any findings or violations of more than minor significance for this aging management program.

(43) A.2.2.41 Periodic Inspections for Selective Leaching (Plant Specific) and Commitment 43 This new plant-specific condition monitoring program manages the loss of material caused by selective leaching identified in gray cast iron components subject to a soil environment and identified in aluminum-bronze components in a raw water environment. The licensee performs visual inspections coupled with mechanical examinations (scraping), and destructive examinations to determine if loss of material caused by selective leaching has occurred. The licensee will complete the initial inspections for each unit prior to their entry into the period of extended operation.

Commitment 43 specified:

  • Implement the periodic inspections for selective leaching aging management program.

The inspectors reviewed the aging management program basis document, implementing procedures, examination reports, and corrective action documents. The inspectors reviewed some inspection results but determined that the licensee had not completed the baseline examinations for this program. The licensee established a schedule to complete the required unit 1 and unit 2 inspections prior to each unit entering their period of extended operation.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

(44) A.2.2.42 Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators (Plant Specific) and Commitment 44 This existing program manages the aging effects of the 230 kV and 500 kV components required for station blackout recovery that include transmission conductors and connections, insulators, and switchyard bus and connections to ensure that these components remain capable of performing their intended functions.

Infrared thermography inspection of transmission and bus connections for indications of loose or degraded connections, inspection of transmission conductors for corrosion and fatigue, and inspection of insulator supports for corrosion and wear will be conducted at a frequency based on plant-specific operating experience. The licensee will complete their baseline inspections and determine the extent of future degradation prior to entering the period of extended operation.

Commitment 44 specified:

Continue the transmission conductor and connections, switchyard bus and connections, and high-voltage insulators plant specific aging management program including enhancements to:

  • Identify components required to support station blackout recovery in the 230 kV and 500 kV switchyards between the listed transformers and disconnects/breakers.
  • Reviewing completed inspection results to identify adverse trends.
  • Evaluate any degraded condition that considers the extent of condition, reportability, potential causes, probably of recurrence, and the corrective actions required.

The inspectors will review this program during a future inspection, and document the results in an inspection report. This aging management program remains open.

INSPECTION RESULTS

Observation: Inaccessible Evaluation of Below Grade Concrete Containment 71013 In August 2024, the NRC inspectors reviewed the licensees May 2024 results associated with the 100% visual examination of accessible surfaces for the exterior concrete containment structure. The licensee noted relevant conditions for the concrete containment structure such as, active cracks, delamination, voids, efflorescence, and spalls.

10 CFR Part 50.55a(b)(2)(viii) Section XI condition: "Concrete containment examinations" requires licensees applying Subsection IWL (2007 Edition up to and including the 2008 Addenda) to evaluate the acceptability of inaccessible areas when conditions exist in accessible areas that could indicate the presence of or result in degradation to such inaccessible areas.

The inspectors identified that an evaluation of the inaccessible portion of the below-grade concrete surfaces of the containment shell had not been performed. In response to this issue, the licensee performed an evaluation on the below-grade concrete surfaces. This evaluation considered insights such as, the non-aggressive groundwater samples, the significance of leaching observed on accessible surfaces, the french drains that provide a protective barrier system, and future enhancements to the IWL Inspection program required by a renewed license. As a result of the evaluation the licensee determined that the inaccessible area was acceptable and did not require an enhanced inspection frequency. The inspectors determined that this performance deficiency was a minor violation of 10 CFR Part 50.55a(b)(2)(viii). The licensee entered this issue into the corrective action program as SAPNs 51253137 and

EXIT MEETINGS AND DEBRIEFS

The inspectors verified no proprietary information was retained or documented in this report.

  • On September 16, 2024, the inspectors presented the license renewal results to Allen Wilson, Senior Director of Engineering, Projects, & Outages and other members of the licensee staff.

The following commitments were closed during this inspection after review of the aging management program implementation and associated commitments: 3, 4, 5, 6, 7, 8, 9, 12, 13, 14, 15, 16, 18, 24, 25, 26, 27, 29, 33, 37, and 42 The following commitments remain open and will be reviewed during future inspection(s): 1, 2, 10, 11, 17, 19, 20, 21, 22, 23, 28, 30, 31, 32,34, 35, 36, 38, 39, 40, 41, 43, and 44.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

71002

Corrective Action

Documents

Resulting from

Inspection

SAPN -

251531

71002

Drawings

LR-DCPP-09-

106709-02

"License Renewal Scoping, Screening and Aging

Management Review Results, Fire Protection System,

3: Boundary Drawings

23.1

71002

Drawings

LR-DCPP-09-

106709-02

"License Renewal Scoping, Screening and Aging

Management Review Results, Fire Protection System,

3: Boundary Drawings

71013

Calculations

9000041674

Buried Piping and Tanks Program Asset Management

Plan

71013

Corrective Action

Documents

SAPN -

50123904, 50252917, 50313081, 50500443, 50581755,

50581757, 50595631, 50608728, 50620709, 50633704,

50654359, 50655097, 50754298, 50805534, 50841979,

50861775, 50863342, 50864573, 50864574, 50865731,

50866614, 50868534, 50874928, 50915722, 50923268,

50944920, 50962926, 50980285, 50980794, 50992490,

50995366, 51004443, 51004503, 51007314, 51022232,

51022555, 51035993, 51037746, 51064736, 51071499,

51073314, 51078443, 51086178, 51095179, 51110876,

51113425, 51117667, 51118825, 51124954, 51139925,

51149745, 51163854, 51167544, 51167547, 51172023,

51182877, 51182878, 51209234, 51211955, 51220689,

223508, 51226585, 51227856

71013

Corrective Action

SAPN -

204893, 51251466, 51251531, 51251558, 51251722,

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Documents

Resulting from

Inspection

253137, 51254177

71013

Drawings

438120

Longitudinal Section and Details of Discharge Structure

Circulating Water System

71013

Drawings

438132

Civil - Sections & Detail Discharge Structure Modification

Circulating Water System

71013

Drawings

515213

Unit 1 Safety Related Masonry Walls Turbine Building

Elev 85'0", 107'-0", 119'-0", 140'-0"

71013

Drawings

515214

Unit 2 Safety Related Masonry Walls Turbine Building

Elev 85'0", 104'-0", 107'-0", 119'-0", 140'-0"

71013

Drawings

515215, sheet 1

Safety Related Masonry Walls Auxiliary Building Elev

85'0", 100'-0", 115'-0", 140'-0", 154'-0"

71013

Engineering

Evaluations

ATS Report 420DC-

2.21

Test and Analysis of Structural Concrete During 1R17

Inspection of the Discharge Conduits

5/10/2012

71013

Engineering

Evaluations

ATS Report 420DC-

13.8

Test and Analysis of Structural Concrete During 1R17

Inspection of the Discharge Conduits

5/2/2013

71013

Engineering

Evaluations

ATS Report 420DC-

23.22

DCPP CCW 1-1 and 1-2 Heat Exchanger Tests Pre-1R24

11/7/2023

71013

Engineering

Evaluations

ATS Report 420DC-

24.32

Selective Leaching Evaluation of 1R24 DCPP Brass Valve

GSC-1-477

1/1/2024

71013

Engineering

Evaluations

ATS Report 420DC-

24.34

Selective Leaching Evaluation of 1R24 DCPP Gray Cast

Iron Valve FP-1-663

2/11/2023

71013

Engineering

Evaluations

WCAP-13895-P

A Demonstration of Applicability of ASME Code Case N-

481 to the Primary Loop Pump Casings of Diablo

Canyon Units 1 and 2 for the 60-year Initial License

Renewal (ILR) Program

71013

Engineering

Evaluations

WCAP-17299-NP

Fast Neutron Fluence Update for Diablo Canyon Unit 1

and 2 Pressure Vessels

71013

Engineering

Evaluations

WCAP-17315-NP

Diablo Canyon Units 1 and 2 Pressurized Thermal Shock

and Upper-Shelf Energy Evaluations

71013

Engineering

Evaluations

WCAP-17451-P

Reactor Internals Guide Tube Wear - Westinghouse

Domestic Fleet Operational Projections

71013

Engineering

WCAP-17462-NP

Program Plan for Aging Management of Reactor Vessel

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Evaluations

Internals at Diablo Canyon Power Plant Unit 1

71013

Engineering

Evaluations

WCAP-17463-NP

Program Plan for Aging Management of Reactor Vessel

Internals at Diablo Canyon Power Plant Unit 2

71013

Engineering

Evaluations

WCAP-18145-P

Diablo Canyon Unit 2 - Upper Internals 17x17 Standard

Guide Tube - Guide Card Wear Evaluation

71013

Engineering

Evaluations

WCAP-18255-P

Diablo Canyon Unit 1 - Upper Internals 17x17 Standard

Guide Tube - Guide Card Wear Evaluation

71013

Engineering

Evaluations

WCAP-18566-NP

Ex-Vessel Neutron Dosimetry Program for Diablo Canyon

Unit 2 Cycle 21

71013

Engineering

Evaluations

WCAP-18655-NP

Ex-Vessel Neutron Dosimetry Program for Diablo Canyon

Unit 1 Cycle 22

71013

Engineering

Evaluations

WCAP-18892-P

Flaw Tolerance Evaluation for Susceptible Reactor

Coolant Loop Cast Austenitic Stainless Steel Piping

Components for Diablo Canyon Units 1 and 2 60 Year

License Renewal

71013

Miscellaneous

Strategic Primary Water Chemistry Plan

71013

Miscellaneous

Secondary Water Strategic Chemistry Plan Recirculating

Steam Generator Plant

71013

Miscellaneous

Closed Cooling Water Strategic Plan

71013

Miscellaneous

CMR-2.1

Maintenance Rule Monitoring Per 10CFR50.65 - Concrete

Structure

71013

Miscellaneous

CMR-2.2

Maintenance Rule Monitoring Per 10CFR50.65 - Auxiliary

Building

71013

Miscellaneous

CMR-2.3

Maintenance Rule Monitoring Per 10CFR50.65 - Fuel

Handling Building Steel Superstructure

71013

Miscellaneous

CMR-2.5

Maintenance Rule Monitoring Per 10CFR50.65 - Intake

Structure and Intake Control Building

71013

Miscellaneous

CMR-2.6

Maintenance Rule Monitoring Per 10CFR50.65 -

Discharge Structure and Circulating Water Discharge

Tunnels

71013

Miscellaneous

CMR-4.6

Maintenance Rule Monitoring Per 10CFR50.65 - Masonry

Walls

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.11 - Open-Cycle Cooling Water System

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

B.2.3.11

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.12

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.12 - Closed Treated Water Systems

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.18

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.11 - Reactor Vessel Surveillance

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.2

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.2 - Water Chemistry

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.20

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.20 - Selective Leaching

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.26

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.26 - Buried and Underground Piping and

Tanks

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.32

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.32 - Masonry Walls

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.33

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.33 - Structures Monitoring

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.34

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.34 - Regulatory Guide 1.127, Inspection of

Water-Control Structures Associated with Nuclear Power

Plants

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.41

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.41 - Periodic Inspections for Selective

Leaching

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

B.2.3.6

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.6 - Thermal Aging Embrittlement of Cast

Austenitic Stainless Steel (CASS)

71013

Miscellaneous

DCM T-43 License

Renewal Appendix B

Diablo Canyon Aging Management Program Evaluation

Report B.2.3.7 - PWR Vessel Internals

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

B.2.3.7

71013

Miscellaneous

Letter DCL-23-038

Revision to the Unit 1 Reactor Vessel Material

Surveillance Program Withdrawal Schedule

5/15/2023

71013

Miscellaneous

LTR-RIAM-17-53

Diablo Canyon Unit 1 Baffle-Former Bolt Re-Inspection

Recommendation

71013

Miscellaneous

MRP-191

Materials Reliability Program: Screening, Categorization,

and Ranking of Reactor Internals Components for

Westinghouse and Combustion Engineering PWR Design

71013

Miscellaneous

MRP-227

Materials Reliability Program: Pressurized Water Reactor

Internals Inspection and Evaluation Guidelines

1-A

71013

Miscellaneous

NSAL-16-1

Baffle-Former Bolts

71013

Miscellaneous

NSAL-20-1

Reactor Vessel Head Control Rod Drive Mechanism

Penetration Thermal Sleeve Cross-Sectional Failure

71013

Miscellaneous

NUREG/CR-4513

Estimation of Fracture Toughness of Cast Stainless

Steels during Thermal Aging in LWR Systems

71013

Miscellaneous

OG-21-160

NEI 03-08 Needed Guidance: PWR Lower Radial Support

Clevis Insert X-750 Bolt Inspection Requirements

9/1/2021

71013

Miscellaneous

PGEDCROLI-00005-

REPT-003

Diablo Canyon Units 1 and 2 Selective Leaching Aging

Management Program Sampling Plan

71013

Miscellaneous

PGEDCROLI-00005-

REPT-014

Selective Leaching Aging Management Program

Technical Basis Document

71013

Miscellaneous

REPORT #

VL_22005_041322

Inspection of the Circulating Water Conduits TS, CWP

and ASW Forebays Discharge Conduits Intake Structure

and Associated Structures

4/13/2022

71013

Miscellaneous

Report # VL_DCPP

2R23_22057_020223

Inspection of the Circulating Water Conduits TS, CWP

and ASW Forebays Discharge Conduits Intake Structure

and Associated Structures

2/2/2023

71013

Miscellaneous

Report#

VL_22022_082522

Diablo Canyon Power Plant Test and Analysis of Non-

Submerged Structural Concrete of the Intake Structure

8/25/2022

71013

Miscellaneous

TB-14-5

Reactor Internals Lower Radial Support Clevis Insert Cap

Screw Degradation

71013

Miscellaneous

TB-19-5

Westinghouse NSSS PWR Thermal Shield Degradation -

Thermal Shield Flexures and Support Block Cap Screws

71013

Miscellaneous

VL Project No. 23034

Diablo Canyon Power Plant 2023 Survey of Intake Basin

8/8/2023

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Breakwater Structures

71013

NDE Reports

Conco Job #31709

Unit 2 Component Cooling Water Heat Exchanger CCW

2-1

3/2021

71013

NDE Reports

Conco Job #33941

Unit 1 Component Cooling Water Heat Exchanger CCW

1-1

4/2022

71013

Procedures

AWP E-016

Inspection Guide - Maintenance Rule Structural

Monitoring Programs - Civil

71013

Procedures

CAP A-1

Primary Sampling and Analysis Schedules

71013

Procedures

CAP A-2

Secondary Cycle Sampling Schedule

71013

Procedures

CAP E-1

Primary Systems Sampling

71013

Procedures

CAP E-6

Secondary System Sampling

71013

Procedures

CY1.DC1

Analytical Data Processing Responsibilities

71013

Procedures

CY1.ID2

Closed Cooling Water Chemistry Program

71013

Procedures

MA1.ID20

Testing/Inspections for Aux Saltwater System NRC Generic Letter 89-13 Compliance

71013

Procedures

MA1.NE1

Maintenance Rule Monitoring Program - Civil

Implementation

71013

Procedures

MIP C-15.0

Excavation and Backfill

71013

Procedures

OP F-5:I

Chemical Control Limits and Action Guidelines for the

Primary Systems

71013

Procedures

OP F-5:II

Chemistry Control Limits and Action Guidelines for the

Secondary Systems

71013

Procedures

OP F-5:III

Chemistry Control Limits and Action Guidelines for the

Plant Support Systems

71013

Procedures

PEP 15-02

Flushing Low Flow SCW Components

71013

Procedures

PEP 72.1

Annual Survey of ASW Pipe Cathodic Protection

71013

Procedures

PEP C-17.13

Coatings Surveillance Program for the Saltwater Systems

71013

Procedures

PEP C-17.14

Concrete Surveillance Program for the Saltwater Systems

71013

Procedures

PEPL M-234

CCW Heat Exchanger Performance Test

71013

Procedures

PTLR-1

PTLR for Diablo Canyon

16A

71013

Procedures

STP M 26

ASW System Flow Monitoring

71013

Procedures

STP M-21-ENG.1

Diesel Engine Generator Inspection (Every Refueling

Outage)

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

71013

Procedures

STP M-21-ENG.6

Diesel Engine Generator Inspection (Every Sixth

Refueling Outage)

71013

Procedures

STP M-21-ENG.8

Diesel Engine Generator Inspection (Every Eighth

Refueling Outage)

71013

Procedures

STP M-235A

ASW Piping Inspection, CCW Heat Exchanger

71013

Procedures

STP M-235B

ASW Piping Inspection at Vacuum Breaker Vault

71013

Procedures

STP M-235C

ASW Piping Inspection at Intake Structure

71013

Procedures

STP M-71

Firewater System Flow Test

71013

Procedures

STP M-90B

Surveillance of Diablo Canyon Breakwaters

71013

Procedures

STP V-13A

CCW Flow Balancing

71013

Procedures

TS1.DC2

Selective Leaching Aging Management Program

71013

Procedures

TS1.DC4

Thermal Aging Embrittlement of Cast Austenitic Stainless

Steel Program

71013

Procedures

TS1.ID11

Reactor Internals Aging Management Program

71013

Procedures

TS1.ID4

Saltwater Systems Aging Management Program

71013

Procedures

TS1.ID6

Reactor Pressure Vessel Embrittlement Management

Program

71013

Procedures

TS5.ID3

Buried Piping and Tanks Program

71013

Work Orders

201059, 60069571, 60093150, 60152152, 60152153,

60152154, 60152155, 60152157, 60152281, 60152292,

60152300, 60152302, 60152312, 60152326, 60152327,

60154604, 60159520, 64003460, 64003461, 64003462,

64004791, 64005102, 64005103, 64005104, 64032588,

64048068, 64106847, 64131905, 64131981, 64131995,

64168933, 64173461, 64180980, 64181062, 64186691,

64199047, 64204604, 64213183, 64215733, 64215733,

216136, 64219075, 64221162, 64230849, 64232861,

236203, 64243129, 64249544, 64249545, 64252021,

253174, 64260500, 64260667, 64262928, 64263399,

263990, 64264268, 64265472, 64266165, 64266389,

268309, 64268477, 64269157, 64269652, 64269928,

271090, 64271131, 64274301, 64274303, 64274875,

275086, 64277421, 64277506, 64277999, 64278972,

283237, 64283739, 64283740, 64285581, 68046520

45

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