IR 05000275/2024001

Integrated Inspection Report 05000275/2024001 and 05000323/2024001

ML24113A066
Person / Time
Site:	Diablo Canyon
Issue date:	04/23/2024
From:	Patricia Vossmar NRC/RGN-IV/DORS/PBA
To:	Gerfen P Pacific Gas & Electric Co
References
IR 2024001
Download: ML24113A066 (29)

Text

April 23, 2024

SUBJECT:

DIABLO CANYON POWER PLANT, UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000275/2024001 AND 05000323/2024001

Dear Paula A. Gerfen:

On March 31, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Diablo Canyon Power Plant, Units 1 and 2. On April 4, 2024, the NRC inspectors discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.

Five findings of very low safety significance (Green) are documented in this report. Four of these findings involved violations of NRC requirements. One Severity Level IV violation without an associated finding is documented in this report. We are treating these violations as non-cited violations (NCVs) consistent with section 2.3.2 of the Enforcement Policy.

If you contest the violations or the significance or severity of the violations documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN:

Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; the Director, Office of Enforcement; and the NRC Resident Inspector at Diablo Canyon Power Plant, Units 1 and 2.

If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; and the NRC Resident Inspector at Diablo Canyon Power Plant, Units 1 and 2. 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, Patricia J. Vossmar, Chief Reactor Projects Branch A 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: 05000275/2024001 and 05000323/2024001

Licensee: Pacific Gas and Electric Company

Facility: Diablo Canyon Power Plant, Units 1 and 2

Location: Avila Beach, CA

Inspection Dates: January 1, 2024, to March 31, 2024

Inspectors: A. Athar, Resident Inspector C. Harrington, Operations Engineer M. Hayes, Senior Resident Inspector E. Lantz, Resident Inspector

Approved By: Patricia J. Vossmar, Chief Reactor Projects Branch A Division of Operating Reactor Safety

Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Diablo Canyon Power Plant, Units 1 and 2, 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

Inadequate Maintenance Rule Evaluations on Condenser Steam Dump System Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [H.7] - 71111.12 Systems NCV 05000275,05000323/2024001-01 Documentation Open/Closed The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65(a)(1), Requirements for monitoring the effectiveness of maintenance at nuclear power plants, for the licensees failure to monitor the performance of Unit 1 condenser steam dumps against licensee established goals to provide reasonable assurance the condenser steam dumps were capable of fulfilling their intended function. Specifically, the licensee failed to perform maintenance rule functional failure evaluations against the turbine steam supply system when the condenser interlock C-9 was lost due to high backpressure in the sensing line, and as a result failed to monitor the system under 10 CFR 50.65(a)(1).

Failure to Maintain Annunciator Response Procedure Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green None 71111.15 Systems NCV 05000275,05000323/2024001-02 Open/Closed The inspectors identified a Green finding and associated non-cited violation of technical specification 5.4.1.a for the licensees failure to maintain the annunciator response procedure (ARP) for Annunciator PK08-14, Condenser Available C-9. Specifically, the ARP failed to direct operations personnel to evaluate technical specification 3.3.1 when annunciator PK08-14 went out.

Failure to Remove Valve Parts Results in Reactor Trip at Low Power Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green None 71152A FIN 05000275/2024001-03 Open/Closed The inspectors reviewed a self-revealed Green finding for the failure to follow vendor manual instructions when rebuilding feedwater heater 1-5A dump valve 1-LCV-9 which led to a reactor trip at low power while shutting down for refueling outage 1R24.

Failure to Consider Appropriate Performance Criteria for Maintenance Rule Components Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.4] - Trending 71152A Systems NCV 05000275,05000323/2024001-04 Open/Closed The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65(a)(2), Requirements for monitoring the effectiveness of maintenance at nuclear power plants. Specifically, the licensee failed to appropriately consider the availability and reliability of the auxiliary building and fuel handling building roof drains when evaluating whether their performance or condition had been demonstrated to be effectively controlled under the structural monitoring program.

Failure to Maintain Original Design Specifications after Maintenance Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green None (NPP) 71152A Systems NCV 05000275,05000323/2024001-05 Open/Closed The inspectors identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion III,

Design Control, associated with the licensees failure to assure that design changes were subject to design control measures commensurate with those applied to the original design.

Specifically, the licensee made changes to the roofs of the auxiliary building and fuel handling building but failed to evaluate the reduction in roof drain overflow scupper opening size that resulted from the roof changes.

Failure to Make an Interim Part 21 Report Cornerstone Severity Cross-Cutting Report Aspect Section Not Applicable Severity Level IV Not Applicable 71152A NCV 05000275/2024001-06 Open/Closed The inspectors identified a Severity Level IV, non-cited violation of 10 CFR 21.21(a)(2),

Reporting of Defects and Noncompliance, for the licensees failure to make an interim report within 60 days after identification of a potential deviation in installed pipe snubbers.

Additional Tracking Items

Type Issue Number Title Report Section Status URI 05000323/2024001-07 Auxiliary Building Ventilation 71153 Open Inoperable Coincident with Redundant Train Diesel Generator Maintenance Outage

PLANT STATUS

Unit 1 operated at or near rated thermal power for the entire inspection period.

Unit 2 operated at or near rated thermal power for the entire inspection period.

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 performed activities described in IMC 2515, Appendix D, Plant Status, observed risk significant activities, and completed on-site portions of IPs. 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.

71111.01 - Adverse Weather Protection

Seasonal Extreme Weather Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of forecasted rain and high winds during an atmospheric river weather event for the following systems on January 31, 2024:

• transformer yard and switchyard

Impending Severe Weather Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the adequacy of the overall preparations to protect risk-significant systems from impending severe weather during a tornado and severe thunderstorm warning on February 7, 2024.

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (3 Samples)

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1) Unit 2 emergency diesel generator 2-2 while emergency diesel generator 2-3 was out of service for planned maintenance on January 31, 2024

(2) Unit 2 auxiliary feedwater pump 2-1 while auxiliary feedwater pump 2-2 was out of service for planned maintenance on February 12, 2024

(3) Unit 1 safety injection pumps 1-1 and 1-2 on February 28, 2024

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (5 Samples)

The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:

(1) Units 1 and 2 intake structure, fire zone 30-A-5, on January 3, 2024

(2) Unit 2 emergency diesel generator 2-3 room, fire zone 22-C-1, on January 5, 2024

(3) Units 1 and 2 cable spreading rooms on January 17, 2024

(4) Unit 2 turbine building component cooling water heat exchanger room, 85-foot elevation, on January 24, 2024

(5) Unit 1 turbine building component cooling water heat exchanger room, 85-foot elevation, on February 15, 2024

Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the onsite fire brigade training and performance during an announced fire drill on January 19, 2024.

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance

Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (1 Sample)

(1) The inspectors observed and evaluated licensed operator performance in the control room during initial startup testing of the emergency diesel generator after governor replacement on February 4, 2024.

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)

(1) The inspectors observed and evaluated a crew of licensed operators during simulator training on January 17, 2024.

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (1 Sample)

The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:

(1) condenser steam dumps on January 31, 2024

Quality Control (IP Section 03.02) (1 Sample)

The inspectors evaluated the effectiveness of maintenance and quality control activities to ensure the following SSC remains capable of performing its intended function:

(1) Unit 1 centrifugal charging pump 1-1 on February 26, 2024

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (5 Samples)

The inspectors evaluated the accuracy and completeness of risk assessments for the following planned and emergent work activities to ensure configuration changes and appropriate work controls were addressed:

(1) Unit 1 high risk for emergent maintenance on auxiliary saltwater pump 1-1 vault exhaust fan due to a hard ground on the exhaust fan motor on January 4, 2024

(2) Unit 2 emergency diesel generator 2-3 major maintenance outage window on February 3, 2024

(3) Unit 2 emergency diesel generator 2-1 major maintenance outage window on February 22, 2024

(4) Unit 1 high risk for swapping stator core cooling water pumps due to failure of service water cooling pump 1-1 on March 7, 2024

(5) Unit 2 Yellow risk during emergency diesel generator 2-2 maintenance outage window on March 18, 2024

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (6 Samples)

The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:

(1) Unit 1 loss of Annunciator C-9, "Condenser Available," on January 16, 2024

(2) Unit1 blackened bus bars on battery 1-2 on January 26, 2024

(3) Unit 2 safety injection valve SI-8883 mid position indication while closed on February 14, 2024

(4) Unit 2 emergency diesel generator 2-1 low lube oil pressure alarm relay fail on March 1, 2024

(5) Unit 1 resistance temperature detector excitation current value incorrect in eagle 21 rack15 on March 14, 2024

(6) Unit 1 containment vent ducting tape fraying on March 21, 2024

71111.18 - Plant Modifications

Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (1 Sample)

The inspectors evaluated the following temporary or permanent modifications:

(1) Unit 1 compensatory measure to close feedwater isolation valve FCV-441 on plant trip on January 10, 2024

71111.24 - Testing and Maintenance of Equipment Important to Risk

The inspectors evaluated the following testing and maintenance activities to verify system operability and/or functionality:

Post-Maintenance Testing (PMT) (IP Section 03.01) (6 Samples)

(1) Unit 1 auxiliary saltwater pump 1-1 and associated exhaust fan E-103 on January 19, 2024

(2) Unit 2 auxiliary feedwater pump 2-1 on January 23, 2024

(3) Unit 2 emergency diesel generator 2-3 after major maintenance on February 6, 2024

(4) Unit 1 centrifugal charging pump 1-1 after maintenance on February 26, 2024

(5) Unit 2 pressurizer heater 2-3 after breaker maintenance on March 5, 2024

(6) Unit 2 auxiliary building fan E-1 after emergent maintenance on March 18, 2024

Surveillance Testing (IP Section 03.01) (3 Samples)

(1) Unit 1 4 kV vital bus F relay calibration on January 30, 2024

(2) Unit 1 routine surveillance of steam-driven auxiliary feedwater pump 1-1 on February 9, 2024

(3) Unit 1 routine surveillance of safety injection pump 1-2 on March 15, 2024

71114.06 - Drill Evaluation

Required Emergency Preparedness Drill (1 Sample)

(1) The inspectors evaluated a tabletop emergency preparedness drill on February 29,

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification

The inspectors verified licensee performance indicators submittals listed below:

IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01)===

(1) Unit 1 (January 1, 2023, through December 31, 2023)

(2) Unit 2 (January 1, 2023, through December 31, 2023)

IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (2 Samples)

(1) Unit 1 (January 1, 2023, through December 31, 2023)

(2) Unit 2 (January 1, 2023, through December 31, 2023)

IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (2 Samples)

(1) Unit 1 (January 1, 2023, through December 31, 2023)

(2) Unit 2 (January 1, 2023, through December 31, 2023)

===71152A - Annual Follow-up Problem Identification and Resolution

Annual Follow-up of Selected Issues (Section 03.03)===

The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:

(1) review of feedwater heater 1-5A level out of sight high requiring reactor trip during down power on January 29, 2024

(2) review of auxiliary and fuel handling building roof drains and scuppers on March 8, 2024

(3) review of snubber Part 21 evaluation on March 11, 2024

71153 - Follow Up of Events and Notices of Enforcement Discretion

Notice of Enforcement Discretion (IP Section 03.04) (1 Partial)

(1) (Partial)

The inspectors evaluated the licensee actions surrounding Notice of Enforcement Discretion EA-24-033 which can be accessed at http://www.nrc.gov/reading-rm/doc-collections/enforcement/notices/noedreactor.html, on March 19,

INSPECTION RESULTS

Inadequate Maintenance Rule Evaluations on Condenser Steam Dump System Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [H.7] - 71111.12 Systems NCV 05000275,05000323/2024001-01 Documentation Open/Closed The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65(a)(1), Requirements for monitoring the effectiveness of maintenance at nuclear power plants, for the licensees failure to monitor the performance of Unit 1 condenser steam dumps against licensee established goals to provide reasonable assurance the condenser steam dumps were capable of fulfilling their intended function. Specifically, the licensee failed to perform maintenance rule functional failure evaluations against the turbine steam supply system when the condenser interlock C-9 was lost due to high backpressure in the sensing line, and as a result failed to monitor the system under 10 CFR 50.65(a)(1).

Description:

On January 11, 2024, the licensee wrote Notification 51222018 documenting pressure transmitter PT-175 failing high. In the notification, the pressure transmitter trended up during the day and eventually went high enough to cause the interlock for condenser availability (C-9) to clear. When C-9 clears, it prevents operation of the condenser steam dumps. The condenser steam dumps are relied upon in emergency operating procedure E-0 to control reactor coolant system (RCS) temperature after a plant trip. The inspectors reviewed the maintenance rule review task of the notification and noticed the task was marked as a maintenance rule functional failure against the main condenser. The inspectors expected a second maintenance rule functional failure evaluation against the turbine steam supply system, but the licensee had not completed one.

When the inspectors presented their concerns to the licensee, the licensee reperformed the maintenance rule functional failure analysis against the turbine steam supply system and concluded this failure did cause a maintenance rule functional failure against the turbine steam supply system. The inspectors also found past incidents where failures of PT-175 were only counted against the main condenser and not additionally against the turbine steam supply system. One occasion was on December 31, 2023, when PT-175 failed multiple times during the day. After correctly identifying each incident (1/11/2024 and 12/31/2023) as a maintenance rule functional failure, the licensee conducted an evaluation for each incident as a maintenance preventable function failure for comparison against established goals for the turbine steam supply system. Each incident was deemed as a maintenance preventable functional failure which exceeded the reliability goals set for the turbine steam supply system of less than two maintenance preventable functional failures in 24 months. Upon discovery, the licensee performed an evaluation for placing the turbine steam supply system in 50.65(a)(1) status.

The inspectors reviewed Procedure MA1.ID17, Maintenance Rule Monitoring Program, revision 34, step 5.4.2.a.5, and noted the step requires engineering to evaluate the impact of the problem against other systems and route the notification to the appropriate engineer.

Step 5.4.2.a.5 also lists systems that apply to multiple maintenance rule systems. Despite the impacts the steam dumps have on multiple systems, the step does not specifically mention that a failure of the condenser steam dumps to operate needs to be evaluated against both the main condenser and the turbine steam supply system.

Corrective Actions: The licensee completed maintenance rule functional failure evaluations against the turbine steam supply system and performed the appropriate evaluation for placing the system into 50.65(a)(1) status.

Corrective Action References: Notifications 51227383, 51221731, and 51220127

Performance Assessment:

Performance Deficiency: The failure to monitor the performance of the Unit 1 condenser steam dumps against licensee established goals in accordance with Procedure MA1.ID17, Maintenance Rule Monitoring Program, revision 34, was a performance deficiency.

Specifically, the licensee did not account for failures of PT-175 against the steam supply system.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment Performance attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the Unit 1 turbine steam supply system exceeding its maintenance rule performance criteria demonstrated the system was not being effectively controlled through appropriate preventive maintenance.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Exhibit 2, Mitigating Systems Screening Questions, the finding was screened as having very low safety significance (Green) because the finding did not affect the design or qualification of a mitigating SSC, did not represent a loss of PRA function of a single train technical specification system for greater than its technical specification allowed outage time, did not represent a loss of the probabilistic risk assessment (PRA) function of one train of a multi-train technical specification system for greater than its technical specification allowed outage time, did not represent a loss of the PRA function of two separate technical specification systems for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, did not represent a loss of a PRA system or function as defined in the PRIB or the licensees PRA for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and did not represent a loss of the PRA function of one or more non-technical specification trains of equipment designated as risk-significant in accordance with the licensees maintenance rule program for greater than 3 days.

Cross-Cutting Aspect: H.7 - Documentation: The organization creates and maintains complete, accurate, and up-to-date documentation. Specifically, the licensee failed to update procedure MA1.ID17 to include systems that require maintenance rule functional failure evaluations against multiple systems.

Enforcement:

Violation: Title 10 CFR 50.65(a)(1), requires, in part, each holder of an operating license for a nuclear power plant shall monitor the performance of systems, or components, against licensee-established goals, in a manner sufficient to provide reasonable assurance that such systems, or components, as defined in 10 CFR 50.65(b), can fulfill their intended functions.

These goals shall be established commensurate with safety and, when the performance of a system, or component does not meet established goals, appropriate corrective action shall be taken. Title 10 CFR 50.65(a)(2) states, in part, monitoring is not required where it has been demonstrated that the performance of a system, or component is being effectively controlled through the performance of appropriate preventive maintenance, such that the system, or component remains capable of performing its intended function.

Contrary to the above, from December 31, 2023, to February 29, 2024, the licensee failed to monitor the performance of systems, or components, against licensee-established goals, in a manner sufficient to provide reasonable assurance that such systems, or components, as defined in 10 CFR 50.65(b), can fulfill their intended functions. Specifically, when PT-175 failed above 10.0 in HgA on December 31, 2023, and January 12, 2024, which prevented the arming of condenser steam dumps, the licensee failed to monitor the turbine steam supply system against licensee-established goals. In particular, the licensee failed to count maintenance preventable functional failures against the turbine steam supply system, which when accounted for, exceeded the performance criteria set for the turbine steam supply system and should have prompted an evaluation for placing the system into 50.65(a)(1)status.

Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.

Failure to Maintain Annunciator Response Procedure Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green None 71111.15 Systems NCV 05000275,05000323/2024001-02 Open/Closed The inspectors identified a Green finding and associated non-cited violation of technical specification 5.4.1.a for the licensees failure to maintain the annunciator response procedure (ARP) for Annunciator PK08-14, Condenser Available C-9. Specifically, the ARP failed to direct operations personnel to evaluate technical specification 3.3.1 when annunciator PK08-14 went out.

Description:

On January 11, 2024, Unit 1 received a condenser not available alarm when annunciator PK08-14 went out. Annunciator PK08-14 is typically lit to announce to operators the main condenser is available. The operations crew reviewed ARP AR PK08-14, Condenser Available C-9, revision 2, for guidance. AR PK08-14, revision 2, only had the following guidance from steps 2.1.1, 3.1, and 3.2:

2.1.1 IF the 40% Steam Dumps are NOT available, THEN notify Power Trading of a loss of fast ramp capability PER Operations Policy B-1, Section 4, Notifications.

3.1 Above C-9 setpoint, the 40% Condenser Steam Dump valves are available for use.

3.2 Below C-9 setpoint, the 40% Condenser Steam Dump valves are blocked CLOSED in all modes of operation.

C-9 is an interlock that declares the condenser is available to allow systems transporting steam to discharge into the condenser during normal and emergency operations. One of those systems that discharges steam to the condenser is the condenser steam dumps. The inspectors were concerned that if the condenser steam dumps could not open, then the basis for the technical specification reactor trip system interlock P-9 was not met. P-9 provides an allowance to not trip the reactor if the turbine trips when reactor power is below 50 percent.

This P-9 interlock was instituted in 1988 following a study by Westinghouse that showed the pressurizer power operated relief valves would not be challenged on a turbine trip without a reactor trip at 50 percent power due to the operation of the steam dump system. The study was conducted with one group of condenser steam dumps not in operation. When interlock C-9 goes out both groups of condenser steam dumps are not available for use. Since both groups of condenser steam dumps were unavailable for use, the inspectors determined the licensee was not in compliance with the basis of the licensing change to add P-9 to the licensing basis. The inspectors presented their information to the licensee on January 16, 2024. The licensee agreed with the inspectors that when C-9 is not available during Mode 1, operations personnel are required to declare P-9 inoperable under Technical Specification (TS) 3.3.1, Function 18.d, Power Range Neutron Flux, P-9, and apply the appropriate technical specification action statement.

The inspectors reviewed recent cases where the licensee failed to enter the appropriate actions for TS 3.3.1, Function 18.d being inoperable, and did not identify any examples where the allowed outage time for the equipment was exceeded.

Corrective Actions: The licensee updated AR PK08-14 to include reviewing technical specifications associated with P-9 if C-9 is not lit.

Corrective Action References: Notifications 51226202, 51221731, 51222018, and 51222024

Performance Assessment:

Performance Deficiency: The failure to maintain the annunciator response procedure associated with PK08-14, Condenser Available C-9, in accordance with TS 5.4.1.a was a performance deficiency. Specifically, the licensee failed to update ARP PK08-14 to include reviewing TS 3.3.1, Function 18.d if PK08-14 is not lit.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Procedure Quality attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, due to not having guidance in ARP PK08-14, operations did not declare TS 3.3.1, Function 18.d, Power Range Neutron Flux, P-9, inoperable when PK08-14 went out.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Exhibit 2, Mitigating Systems Screening Questions, the finding was screened as having very low safety significance (Green) because the finding did not affect the design or qualification of a mitigating SSC, did not represent a loss of PRA function of a single train technical specification system for greater than its technical specification allowed outage time, did not represent a loss of the PRA function of one train of a multi-train technical specification system for greater than its technical specification allowed outage time, did not represent a loss of the PRA function of two separate technical specification systems for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, did not represent a loss of a PRA system or function as defined in the PRIB or the licensees PRA for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and did not represent a loss of the PRA function of one or more non-technical specification trains of equipment designated as risk-significant in accordance with the licensees maintenance rule program for greater than 3 days.

Additionally, the finding only affected a single RPS trip signal to initiate a reactor scram and all other redundant or diverse methods of reactor shutdown were maintained.

Cross-Cutting Aspect: None. Not indicative of current licensee performance.

Enforcement:

Violation: Technical specification 5.4.1.a, requires, in part, that written procedures shall be maintained covering the applicable procedures recommended in Regulatory Guide 1.33, revision 2, appendix A, February 1978. Regulatory Guide 1.33, revision 2, appendix A, section 5, states, in part, that each safety-related annunciator should have its own written procedure which should contain the long-range actions associated with the annunciator.

Contrary to the above, since June 2008, the licensee failed to maintain the safety-related annunciator response procedure for annunciator PK08-14. Specifically, the procedure did not contain the appropriate long-range action of reviewing technical specification 3.3.1, Function 18.d, Power Range Neutron Flux, P-9, when PK08-14 is not illuminated.

Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.

Failure to Remove Valve Parts Results in Reactor Trip at Low Power Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green None 71152A FIN 05000275/2024001-03 Open/Closed The inspectors reviewed a self-revealed Green finding for the failure to follow vendor manual instructions when rebuilding feedwater heater 1-5A dump valve 1-LCV-9 which led to a reactor trip at low power while shutting down for refueling outage 1R24.

Description:

On September 30, 2023, Unit 1 was shutting down in anticipation of starting to refuel outage 1R24. At 6:23 p.m., while lowering power, operators received annunciator PK10-21, FDWTR HTRS HIGH LVL TRIP. An operator was dispatched to investigate in accordance with annunciator response Procedure AR PK10-21, FDWTR HTRS HIGH LVL TRIP, revision 16. The operator observed that level for feedwater heater (FWH) 1-5A was high in the sight glass. The operator checked the controller outputs for the drip valve LC-35 and the dump valve LC-34 and observed them demanding the appropriate position for the condition. The operator did not check the associated valves locally to see if the valves were responding to the demanded position. Operations began a monitoring plan, which required observing level in the FWH 1-5A sight glass every 30 minutes and controller outputs for LC-35 and LC-34. At 7:38 p.m., operators reported FWH 1-5A level was at the top of the indicating range. At 8:00 p.m., operators reported FWH 1-5A dump valve 1-LCV-9 was closed despite having an open demand signal from LC-34. At 8:14 p.m., Unit 1 was manually tripped, from approximately 11 percent power, in accordance with procedure AR PK10-21, step 2.4.2.

During refueling outage 1R24, the licensee removed and inspected valve 1-LCV-9 to try to determine a cause for the valve to not open when demanded. During valve disassembly, the licensee discovered a wave spring and spring retainer washer installed in the valve.

Valve 1-LCV-9 was last rebuilt in 1994 with a retrofit kit and according to the vendor instruction manual, which was received by the licensee in 1983. According to the vendor instructions, during valve rebuilds with a retrofit kit the wave spring and the spring retainer washer should be removed before the valve is placed back in service. The inspectors reviewed the work instructions from the rebuild in 1994 and noted step 10 states, replace parts as required and reassemble valve per manufacturers instructions. The licensee ultimately determined the valve had incorrect parts installed since the valve was rebuilt in 1994. This caused excess friction and binding which resulted in valve 1-LCV-9 not opening when demanded.

Corrective Actions: The licensee rebuilt the valve in accordance with the vendor instructions, retested the valve, and placed valve 1-LCV-9 in service following completion of refueling outage 1R24.

Corrective Action References: Notification 51206375

Performance Assessment:

Performance Deficiency: The failure to follow vendor manual instructions while rebuilding valve 1-LCV-9 was a performance deficiency. Specifically, maintenance personnel did not remove the wave spring and spring retainer washer from retrofit kit while rebuilding valve 1-LCV-9.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Human Performance attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, on April 13, 1994, maintenance personnel failed to follow work order and vendor manual instructions to remove the wave spring and spring retainer washer from valve 1-LCV-9.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Exhibit 1, Initiating Events Screening Questions, the finding did cause a reactor trip and caused the loss of the condenser and main feedwater pumps when the main steam isolation valves were closed in accordance with annunciator response procedure AR PK10-21. The inspectors concluded a detailed risk evaluation was necessary. In performing the detailed risk evaluation, the regional senior reactor analyst assumed the event was a loss of condenser heat sink event and performed an initiating events analysis with the Diablo Canyon plant-specific SPAR model, Version 8.82, run on SAPHIRE, revision 8.2.9. Based on the nature of the equipment failure which caused this event, the analyst assumed that this failure would only occur at low power when a power change was initiated. The analyst was able to eliminate anticipated transient without scram sequences based on this assumption. Also, because the event could only originate at low power and its associated lower decay heat load, the analyst judged that more time would be available for operators to initiate feed and bleed. Accordingly, for basic event HPI-XHE-XM-FAB, Operators Fail to Initiate Feed and Bleed, the analyst adjusted the available time performance shaping factor from Barely Adequate to Nominal to reflect the additional time operators would have to initiate feed and bleed. This adjustment changed the HPI-XHE-XM-FAB human error probability to 2.0E-3.

The model with modifications yielded a conditional core damage probability of 7.0E-7 and a conditional large early release probability of 7.0E-8, characterizing the finding with very low safety significance (Green). Dominant sequences were losses of condenser heat sink mitigated by the auxiliary feedwater and high-pressure injection systems.

Cross-Cutting Aspect: None. Not indicative of current licensee performance.

Enforcement:

Inspectors did not identify a violation of regulatory requirements associated with this finding.

Failure to Consider Appropriate Performance Criteria for Maintenance Rule Components Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.4] - Trending 71152A Systems NCV 05000275,05000323/2024001-04 Open/Closed The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65(a)(2), Requirements for monitoring the effectiveness of maintenance at nuclear power plants. Specifically, the licensee failed to appropriately consider the availability and reliability of the auxiliary building and fuel handling building roof drains when evaluating whether their performance or condition had been demonstrated to be effectively controlled under the structural monitoring program.

Description:

The roof drains for the auxiliary building and fuel handling building were scoped into the stations maintenance rule program. Within the maintenance rule program, the subject drains were scoped under the structural monitoring program. In conjunction with scuppers, the drains were required to remove water at specified rates to protect the structures.

While reviewing the licensees maintenance rule scoping, classification, and performance evaluation of the roof drains, the inspectors identified that the licensee was failing to appropriately consider the availability and reliability of the subject roof drains when evaluating whether their performance or condition had been demonstrated to be effectively controlled.

The inspectors noted that the licensee was evaluating identified deficiencies (for example, obstructed drains) to determine if they would fail the associated structure, and not to determine if they would impact the availability and reliability of the roof drains. One such example was when the inspectors found ponding on the roof of the auxiliary building due to obstructed roof drains (SAPN 51219069 and 51219130) in December 2023. The licensee determined that there was no maintenance rule functional failure even though multiple roof drains were obstructed by debris causing water to pond on the roof of the auxiliary building.

The licensee only considered whether the auxiliary building remained functional and did not appropriately consider the availability and reliability of the drains when evaluating whether their condition had been demonstrated to be effectively controlled.

The inspectors determined that by evaluating roof drain deficiencies only to determine if they would fail the associated structure, the licensee was not appropriately monitoring the roof drains to ensure their performance or condition had been demonstrated to be effectively controlled.

Corrective Actions: The licensee initiated actions to evaluate adding criteria to the maintenance rule program.

Corrective Action References: Notifications 51231221 and 51231282

Performance Assessment:

Performance Deficiency: The failure to appropriately consider the availability and reliability of the auxiliary building and fuel handling building roof drains when evaluating whether their performance or condition had been demonstrated to be effectively controlled under the structural monitoring program was a performance deficiency.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Protection Against External Factors attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the failure to appropriately evaluate availability and reliability of the roof drains could result in the drains not being able to perform their intended function when required, thereby degrading the reliability and availability of the fuel handling buildings and the auxiliary buildings.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Exhibit 2, Mitigating Systems Screening Questions, the finding was determined to have very low safety significance (Green) because the finding did not involve the loss or degradation of equipment or function specifically designed to mitigate a flooding event for greater than 14 days.

Cross-Cutting Aspect: P.4 - Trending: The organization periodically analyzes information from the corrective action program and other assessments in the aggregate to identify programmatic and common cause issues. The inspectors noted multiple examples of obstructed roof drains being evaluated to not be maintenance rule functional failures; these examples were never considered in aggregate to identify that the structural monitoring programs performance criteria for roof drains was not appropriately considering availability and reliability.

Enforcement:

Violation: Title 10 CFR 50.65(a)(1) requires, in part, that holders of an operating license shall monitor the performance or condition of structures, systems or components against licensee-established goals, in a manner sufficient to provide reasonable assurance that such structures, systems, and components can fulfill their intended safety functions.

Title 10 CFR 50.65(a)(2) states, in part, that monitoring as specified in 10 CFR 50.65(a)(1) is not required where it has been demonstrated that the performance or condition of a structure, system, or component is being effectively controlled through the performance of appropriate preventive maintenance, such that the structure, system, or component remains capable of performing its intended function.

Contrary to the above, from initial maintenance rule scoping in 1996 to present, the licensee did not monitor the performance of systems and components against licensee-established goals in a manner sufficient to provide reasonable assurance that certain structures were capable of fulfilling their intended safety functions, and the licensee did not demonstrate that the performance of a system was being effectively controlled through the performance of appropriate preventive maintenance, such that the system remained capable of performing its intended function. Specifically, the licensee did not demonstrate that the performance of the roof drains was being effectively controlled such that the system remained capable of performing its intended function. The availability and reliability of the roof drains was not considered.

Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.

Failure to Maintain Original Design Specifications after Maintenance Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green None (NPP) 71152A Systems NCV 05000275,05000323/2024001-05 Open/Closed The inspectors identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, associated with the licensees failure to assure that design changes were subject to design control measures commensurate with those applied to the original design.

Specifically, the licensee made changes to the roofs of the auxiliary building and fuel handling building but failed to evaluate the reduction in roof drain overflow scupper opening size that resulted from the roof changes.

Description:

DCPP Final Safety Analysis Report (FSAR), section 2.4.11, states, Roofs of PG&E Design Class I buildings have a drainage system designed in accordance with the Uniform Plumbing Code for an adjusted regional probable maximum precipitation (PMP) of 4 inches/hour. In addition, overflow scuppers are provided in parapet walls at roof level to prevent ponding of accumulated rainwater in excess of drain capacity.

While performing inspections to verify the adequacy of features designed to protect Design Class I buildings against external flooding hazards, the inspectors asked the licensee what assurance there was that the roof drain overflow scuppers on the auxiliary building and fuel handling building could remove 4 inches per hour of precipitation, which is the PMP per the stations FSAR. In response to this question, station personnel reviewed drawings and walked down overflow scuppers on the roofs of the auxiliary building and fuel handling building. The licensee informed the inspectors that the applicable design code of record for the auxiliary building and the fuel handling building was the Uniform Building Code (UBC)1967, as documented in Design Control Memorandum (DCM) T-2, Auxiliary Building, revision 10, and DCM T-3, Structural Design of the Fuel Handling Building Steel Superstructure, revision 12. However, the licensee determined the as-found size of the scuppers was smaller than that specified in UBC 1967.

Upon investigation, the licensee determined that the auxiliary building roof membrane was replaced in 2013 by facility maintenance, which may have contributed to the identified reduction in scupper opening size. The roof modification was completed without the knowledge of plant engineering staff, so a 50.59 evaluation was not completed. An engineering evaluation at the time of the roof modification would likely have identified the reduction in scupper opening size. Without an engineering evaluation, the licensee failed to ensure that the changes to the auxiliary building roof were subject to design control measures commensurate with those applied to the original design, and the scupper opening requirements of the 1967 UBC were not maintained.

Furthermore, the licensee determined that the fuel handling building was re-roofed in 1993, and the scuppers were modified as part of the fuel handling building re-roofing. While a 50.59 evaluation was performed as part of the design change, the scupper opening size was not addressed. As such, the licensee failed to ensure that the changes to the fuel handling building roof were subject to design control measures commensurate with those applied to the original design, and the scupper opening requirements of the 1967 UBC were not maintained.

To address the fact that the auxiliary building and fuel handling building roof scuppers are not sized to the specifications of the 1967 UBC, the licensee performed a calculation to demonstrate that the scuppers are able to remove 4 inches per hour of precipitation. The licensee determined that the fuel handling building roof scuppers can remove approximately 10 inches per hour of precipitation. However, upon reviewing the calculation, the inspectors found a mathematical error. After correcting the mathematical error, the licensee determined the fuel handling building scuppers can remove 5 inches per hour of precipitation. While this is more than the PMP of 4 inches per hour, it is a significant reduction in the margin that the licensee originally believed to have. The licensee found that the auxiliary building roof scuppers can remove 20 inches per hour of precipitation.

Corrective Actions: The licensee reperformed the calculation which demonstrated less margin than original construction.

Corrective Action References: Notifications 51220120 and 51220121

Performance Assessment:

Performance Deficiency: The failure to ensure that changes to the facility were subject to design control measures commensurate with those applied to the original design was a performance deficiency that was within the licensees ability to foresee and prevent.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Protection Against External Factors attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, based on the code of record (UBC 1967) and plant drawings, at the time of discovery, there was a reasonable doubt that the roof drain overflow scuppers could still remove a PMP rate of 4 inches per hour from the roofs of the auxiliary building and the fuel handling building - representing a potential decrease in reliability and availability of the fuel handling building and the auxiliary building. Furthermore, this case is similar to example 3.e from IMC 0612, Appendix E, Examples of Minor Issues. Because the licensee had to perform a separate calculation to address the rainwater removal capabilities of the new scupper dimensions, there was initially reasonable doubt about the scuppers capability to support removal of the PMP and the revised calculation showed there was a sizeable reduction in margin for performing their safety function.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Exhibit 2, Mitigating Systems Screening Questions, the finding was determined to have very low safety significance (Green) because the finding did not involve the loss or degradation of equipment or function specifically designed to mitigate a flooding event for greater than 14 days.

Cross-Cutting Aspect: None. Not indicative of current licensee performance.

Enforcement:

Violation: Title 10 CFR Part 50, Appendix B, Criterion III, Design Control, requires, in part, that, design changes shall be subject to design control measures commensurate with those applied to the original design.

Contrary to the above, in 1993 and 2013, the licensee did not ensure that design changes to the roofs of the auxiliary building and fuel handling building were subject to design control measures commensurate with those applied to the original design. Specifically, the licensee did not ensure that design changes to the roofs of the auxiliary building and fuel handling building maintained the roof overflow scupper opening requirements of the 1967 UBC.

Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.

Failure to Make an Interim Part 21 Report Cornerstone Severity Cross-Cutting Report Aspect Section Not Severity Level IV Not 71152A Applicable NCV 05000275/2024001-06 Applicable Open/Closed The inspectors identified a Severity Level IV, non-cited violation of 10 CFR 21.21(a)(2),

Reporting of Defects and Noncompliance, for the licensees failure to make an interim report within 60 days after identification of a potential deviation in installed pipe snubbers.

Description:

During refueling outage 1R24, the licensee discovered test anomalies associated with pipe snubbers installed in the plant starting on October 4, 2023. The licensee was performing Procedure MP M-55.3, PSA Snubber Maintenance, revision 22, and completing snubber functional testing when the tested snubber showed indication of not releasing in the tension direction of the test. The snubber met the acceptance criteria of the test by preventing acceleration of greater than 0.0029 g in the tension direction, but the snubber would lock up and not return to its pre-test position. The snubber would release only after the test was aborted and the test switch was taken from tension to compression. This behavior repeated itself over multiple different tested snubbers.

Snubbers exhibiting unexpected performance during testing were then disassembled and found to have similar issues. These issues included loose locking washers, excessive grease, out of tolerance parts, components installed incorrectly, loose tie-wires, and anomalies in the ball nut screw assembly. The licensee completed onsite troubleshooting on October 16, 2023. The licensee performed a failure mode analysis and determined the most likely cause of the unexpected snubber performance during testing was the anomalies in the ball nut screw assembly. The licensee informed the vendor and the vendor agreed to perform an analysis on the suspect snubbers. Due to the snubbers being contaminated, the licensee experienced delays in shipping the snubbers to the vendor for evaluation. The licensee initiated Notification 51214999 on November 16, 2023, tracking the vendors task to test the suspect snubbers. Within the notification the licensee initiated a task for a Part 21 evaluation to be completed on April 16, 2024, after the vendors evaluation was due to be completed.

The inspectors reviewed Procedure OM7.ID11, 10 CFR 21 Reportability Review Process, revision 5, step 5.12, which states, an interim report shall be coordinated with licensing and sent to the NRC when the evaluation cannot be completed within 60 calendar days. On February 29, 2024, the inspectors asked the licensee if an interim report had been made to the NRC. The inspectors were concerned that the date of discovery of the potential deviation was on October 16, 2023, and therefore the 60 days to complete the evaluation or submit an interim report ended on December 15, 2023. The licensee held an internal meeting on March 4, 2023, and determined they failed to make an interim Part 21 report to the NRC.

Corrective Actions: The licensee completed making the interim report on April 4, 2024.

Corrective Action References: Notifications 51214999 and 51227789

Performance Assessment:

The inspectors determined this violation was associated with a minor performance deficiency. Specifically, the failure to make a timely Part 21 interim report was contrary to licensee procedure OM7.ID11 and was a performance deficiency. This performance deficiency was minor because the inspectors answered No to all three screening questions in appendix B of IMC 0612.

Enforcement:

The ROPs significance determination process does not specifically consider the regulatory process impact in its assessment of licensee performance. Therefore, it is necessary to address this violation which impedes the NRCs ability to regulate using traditional enforcement to adequately deter non-compliance.

Severity: This is a Severity Level IV issue in accordance with the NRC Enforcement Policy.

Section 6.9.d.12 includes the example, A licensee fails to make an interim report required by 10 CFR 21.21(a)(2) or under 10 CFR 50.55(e).

Violation: Title 10 CFR 21.21(a)(2) requires, in part, each entity subject to the regulations in this part shall adopt appropriate procedures to ensure that if an evaluation of an identified deviation or failure to comply potentially associated with a substantial safety hazard cannot be completed within 60 days from discovery, an interim report is prepared and submitted to the Commission. This interim report must be submitted in writing within 60 days of discovery of the deviation or failure to comply.

Contrary to the above from December 15, 2023, to April 4, 2024, the licensee, an entity subject to the regulations above, did not submit an interim report to the Commission within 60 days from discovery of a potential identified deviation when an evaluation of the deviation could not be completed within 60 days from discovery. Specifically, the licensee did not submit an interim report for snubber deviations identified during refueling outage 1R24 due to delays in the vendors ability to receive contaminated parts. These delays were not resolved within 60 days from the date of discovery and prevented the vendor from completing a timely evaluation.

Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.

Unresolved Item Auxiliary Building Ventilation Inoperable Coincident with 71153 (Open) Redundant Train Diesel Generator Maintenance Outage URI 05000323/2024001-07

Description:

On March 18, 2024, during a planned maintenance outage of Unit 2 emergency diesel generator (DG) 2-2, auxiliary building ventilation system (ABVS) fan E-1 tripped off on thermal overload and was declared inoperable. The redundant ABVS fan E-2 started automatically and was supported by DG 2-2, which was inoperable due to the planned maintenance outage. Technical specification (TS) limiting condition for operation (LCO) 3.8.1, condition B, required action B.2 requires declaring equipment supported by the inoperable DG inoperable when the redundant equipment on the other train is inoperable, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of discovery of the condition. After condition B, required action B.2 was applied, operators declared ABVS fan E-2 inoperable in accordance with TS LCO 3.7.12 (the TS for ABVS). TS LCO 3.7.12 does not describe a required action for two inoperable ABVS trains. Therefore, TS LCO 3.0.3 was entered, and the licensee was required to be in Mode 3 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> of applying TS 3.8.1.B.2.

The licensee stated that after ABVS fan E-1 failed, their troubleshooting investigation identified slight discoloration of the C phase contactor between the breaker and the contactor on the load side downstream of the breaker. Voltage, current, and thermography measurements indicated the cause of the condition was most likely local to the connections between the breaker and the contactor. The licensee stated their course of action was to repair the contactor through refurbishment of the copper bar connecting the breaker to the contactor, replacement of the copper bar bolting, inspection and repair of the contactor components, and post-maintenance testing. The licensee stated the proposed course of action was likely to result in a successful resolution of the problem and could be completed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Planned Closure Actions: Further NRC inspection is required to determine if a performance deficiency exits. If a performance deficiency is identified, a more than minor assessment and review of potential NRC violations will be conducted.

Licensee Actions: The licensee requested and was granted a NOED to complete the additional repairs (ML24082A259) on March 19, 2024 (EA-24-033). The licensee returned fan E-1 to operable status on March 19, 2024, and exited both TS LCO 3.8.1.B.2 and TS LCO 3.0.3. In accordance with the NRC Enforcement Manual, the inspectors opened an unresolved item to track inspector review of potential causes and licensee review of the issue.

Corrective Action References: Notification

EXIT MEETINGS AND DEBRIEFS

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

• On April 4, 2024, the inspectors presented the integrated inspection results to Paula A.

Gerfen, Senior Vice President, Generation and Chief Nuclear Officer, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.01 Drawings 106719-6 Liquid Radwaste System 112

71111.01 Drawings 106719-7 Liquid Radwaste System 109

71111.01 Procedures CP M-12 Stranded Plant 8

71111.01 Procedures CP M-16 Severe Weather 22

71111.01 Procedures OP G-1:I Liquid Radwaste - Make Available and Place in Service 27

71111.04 Corrective Action Notifications 51126718, 51162242, 51163660, 51177529, 51177634,

Documents 51178045, 51178211, 51184195, 51184334, 51184378,

51195514, 51196071. 51197915, 51201914, 51201970,

205728, 51221434, 51221966, 51222290

71111.04 Drawings 106709-2 Unit 1, Safety Injection System 69

71111.04 Procedures OP D-1:II Auxiliary Feedwater System - Alignment Verification for Plant 32

Startup

71111.04 Procedures OP J-6B:II-A Diesel Generator 2-2 - Alignment Checklist 1A

71111.04 Procedures STP I-1D Routine Monthly Checks Required by Licensees 104

71111.05 Corrective Action Notifications 50378990, 51102944, 51143922, 51183571, 51212631,

Documents 51222460, 51223950

71111.05 Drawings 111805, Sheet 72 Intake Structure, Unit 1 & 2 5

71111.05 Drawings 111805, Sheet 73 Intake Structure, Unit 1 & 2 1

71111.05 Drawings 11805, Sheet 26 H Block Elevation 128', 154', and 164' 4

71111.05 Drawings 11805, Sheet 27 H Block Elevation 128', 154', and 164' 2

71111.05 Drawings 11805, Sheet 49 Turbine Building Elevation 85' 5

71111.05 Drawings 11805, Sheet 50 Turbine Building Elevation 85' and 76' Unit 1 2

71111.05 Drawings 11805, Sheet 60 Turbine Building Elevation 85' 7

71111.05 Drawings 11805, Sheet 61 Turbine Building Elevation 85' and 76' Unit 2 2

71111.05 Miscellaneous Transient 16279, 16391, 16431, 16957, 17007

Combustible

Permits

71111.05 Procedures CP M-6 Site Fire Response 44

71111.05 Procedures OP AP-27 Loss of Vital 4kV and/or 480 VAC Bus 8

71111.05 Procedures OP AP-34 Fire Response Initial Actions 2

71111.05 Procedures OP AP-34.2.6 Fire Response - 4kV Bus H Cable Spreading Room and 2

Inspection Type Designation Description or Title Revision or

Procedure Date

Switchgear Room

71111.11Q Procedures OP J-6B:VI Diesel Generators - Manual Operation of DG 2-3 35

71111.11Q Procedures STP M-21-RTS.1 Return Diesel Engine to Service Following Outage 27

Maintenance

71111.11Q Procedures STP M-9L Diesel Generator Shutdown Lockout Relay Test 32

71111.12 Corrective Action Notifications 51220429, 51220687

Documents

71111.12 Procedures CF5.ID1 Receipt of Materials 14A

71111.12 Procedures CF5.ID11 Lubricant Control 9D

71111.12 Work Orders WO 60144973

71111.13 Corrective Action Notifications 51223630, 51224195, 51226421, 51227749, 51227878

Documents

71111.13 Procedures AD7.DC6 On-Line Maintenance Risk Management 29

71111.13 Procedures AD7.ID14 Assessment of Integrated Risk 35

71111.13 Procedures AR PK12-02 Service Water Cooling 17

71111.13 Procedures OP J-4A:II Generator Stator Cooling Water - Normal Operation 36

71111.13 Procedures OP J-6B:IX Diesel Generator Extended On-Line Maintenance 14

71111.13 Procedures OP J-7A:VI-11D 480V Non-Vital System - 480V MCC 11D Compensatory 5

Measures

71111.13 Procedures OP O-36 Protected Equipment Postings 29 and 30

71111.15 Corrective Action Notifications 51218393, 51221731, 51222927, 51223174, 51225498,

Documents 51226611, 51228437, 51228624

71111.15 Procedures STP M-11B Station Battery Condition Monitoring 38

71111.15 Procedures STP V-3S5 Exercising Phase A Containment Isolation Valves (ECCS 15

Test)

71111.15 Work Orders WO 64253879, 64255404, 64259386, 64262640, 64265760,

268729, 64275385, 64277940, 64278481

71111.18 Corrective Action Notifications 51216861, 51228992

Documents

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.24 Corrective Action Notifications 51220825, 51224176, 51224177, 51224281, 51224507

Documents

71111.24 Procedures MP E-50.30B Agastat Type ETR Timing Relay Maintenance 27

71111.24 Procedures MP E-50.33A Westinghouse Type SSV-T One Unit Voltage Relay 14A

Maintenance

71111.24 Procedures MP E-50.61 Basler Type BE1-27 Medium Inverse Undervoltage Relay 8A

Maintenance

71111.24 Procedures MP E-50.62 Basler BE1-GPS100 Relay Maintenance 10

71111.24 Procedures MP E-53.1A Generic 115/480 VAC and 125/250 VDC Motor Swap 9

71111.24 Procedures OP B-1A:V CVCS - Transfer Charging Pumps 30

71111.24 Procedures OP E-5:IV Auxiliary Saltwater System-Swapping Pumps or HXs During 15

Single CCW HX Operation

71111.24 Procedures PEP M-81J Test DFO Day Tank Level Instruments 3

71111.24 Procedures STP I-1D Modes 1, 2, and 3 Monthly Checklist 84

71111.24 Procedures STP M-75F 4kV Vital Bus F Undervoltage Relay Calibration 11

71111.24 Procedures STP M-9D1 Diesel Generator Full Load Rejection Test 29

71111.24 Procedures STP P-AFW-11 Routine Surveillance Test of Turbine-Driven Auxiliary 40

Feedwater Pump 1-1

71111.24 Procedures STP P-AFW-21 Routine Surveillance Test of Turbine-Driven Auxiliary 33

Feedwater Pump 2-1

71111.24 Procedures STP P-SIP-12 Routine Surveillance Test of Safety Injection Pump 1-2 32

71111.24 Procedures STP V-3O2 Diesel Starting Air Receiver Leak Check and Check Valve 15A

Exercising

71111.24 Work Orders WO 60157228, 60160880, 64194743, 64194758, 64244292,

244293, 64249100, 64252644, 64256075, 64273777,

274875, 64278320, 64280805, 64282795, 64283105,

283709, 64284157

71151 Procedures AR PK10-21 FDWTR HTRS High Level 16

71151 Procedures EOP E-0 Reactor Trip or Safety Injection 45D

71151 Procedures EOP E-0.1 Reactor Trip Response 43

71151 Procedures OP L-7 Plant Stabilization Following Reactor Trip 26

71152A Corrective Action Notifications 51220120, 51220121, 51220507, 51220508

Documents

71153 Corrective Action Notifications 51229478, 51229578

Inspection Type Designation Description or Title Revision or

Procedure Date

Documents

24