IR 05000280/2024003

Integrated Inspection Report 05000280-2024003 and 05000281-2024003

ML24317A013
Person / Time
Site:	Surry
Issue date:	11/12/2024
From:	Matthew Fannon NRC/RGN-II/DORS/PB2
To:	Carr E Virginia Electric & Power Co (VEPCO)
References
EPID I-2024-003-0030 IR 2024003
Download: ML24317A013 (18)

Text

SUBJECT:

SURRY POWER STATION - INTEGRATED INSPECTION REPORT 05000280/2024003 AND 05000281/2024003

Dear Eric S. Carr:

On September 30, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Surry Power Station. On October 3, 2024, the NRC inspectors discussed the results of this inspection with David Wilson, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.

Two findings of very low safety significance (Green) are documented in this report. None of these findings involved a violation of NRC requirements.

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 II; and the NRC Resident Inspector at Surry Power Station.

November 12, 2024 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, Matthew S. Fannon, Chief Projects Branch 2 Division of Operating Reactor Safety Docket Nos. 05000280 and 05000281 License Nos. DPR-32 and DPR-37

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000280 and 05000281

License Numbers:

DPR-32 and DPR-37

Report Numbers:

05000280/2024003 and 05000281/2024003

Enterprise Identifier:

I-2024-003-0030

Licensee:

Virginia Electric and Power Company

Facility:

Surry Power Station

Location:

Surry, VA

Inspection Dates:

July 1, 2024 to September 30, 2024

Inspectors:

D. Johnson, Senior Emergency Preparedness Specialist

D. Jung, Resident Inspector

S. Kennedy, Senior Resident Inspector

M. Schwieg, Safety and Plant Systems Engineer

J. Walker, Senior Emergency Preparedness Inspector

A. Wang, Resident Inspector

Approved By:

Matthew S. Fannon, Chief

Projects Branch 2

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Surry Power Station, 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

Failure to Test Cables in Accordance with Aging Management Program Requirements Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000280,05000281/2024003-01 Open/Closed

[H.5] - Work Management 71111.12 The inspectors identified a Green finding of the licensee to test the C reserve station service transformer (RSST) medium voltage cables in accordance with the sites aging management program requirements as soon as practicable following exposure to significant moisture. This could have led to in-service cable insulation degradation and failure of C RSST to perform its function.

Failure to Implement Design Change Process during Turbine Control System Upgrade Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000280/2024003-02 Open/Closed

[H.12] - Avoid Complacency 71153 A self-revealed Green finding was identified when the licensee failed to provide design control measures for ensuring the adequacy of the turbine control system (TCS) upgrade project, which resulted in a flawed TCS trip logic to not be corrected and tested. This flawed TCS trip logic was the root cause of a reactor trip.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000280/2024-001-00 LER 2024-001-00 for Surry Power Station,

Troubleshooting Initiated Unknown Turbine Trip Feature in Control System 71153 Closed

PLANT STATUS

Unit 1 and 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

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 regarding a hazardous weather outlook on August 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 1 motor driven auxiliary feedwater (MDAFW) system following MDAFW pump performance testing on July 10, 2024

(2) Unit 2 low head safety injection system (LHSI) following LHSI pump periodic test on August 22, 2024

(3) Emergency diesel generator (EDG) no. 3 following EDG no. 3 monthly surveillance on September 5, 2024

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (3 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) Alternate alternating current (AAC) diesel room, fire zone 69, elevation 35 feet, on August 1, 2024

(2) Unit 1 relay room and emergency switchgear room, fire zones 3A, 3B, and 3C, elevation 9 feet - 6 inches, on August 9, 2024

(3) Unit 2 relay room and emergency switchgear room, fire zones 4A, 4B, and 4C, elevation 9 feet - 6 inches, on August 9, 2024

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

(1) The inspector evaluated the onsite fire brigade training and performance during an unannounced fire drill on September 5, 2024. The simulated fire location was on the air handling unit in the digital control equipment room.

71111.06 - Flood Protection Measures

Flooding Sample (IP Section 03.01) (2 Samples)

(1) The inspectors evaluated external flooding mitigation protections for manhole 0-EP-MH-DL2, intake canal duct line sump pit.

(2) The inspectors evaluated internal flooding mitigation protections for mechanical equipment room no. 3

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 Unit 1 turbine trip solenoid test and Unit 2 turbine driven auxiliary feedwater pump performance test on July 2 and 3, 2024.

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

(1) The inspectors observed and evaluated licensed operator performance in the classroom and simulator during their performance improvement training on July 23, 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) Unit 1 and 2 reactor coolant system hot leg narrow range temperature detectors on September 6, 2024 (Condition Report (CR) 1257674)

Aging Management (IP Section 03.03) (1 Sample)

The inspectors evaluated the effectiveness of the aging management program for the following SSCs that did not meet their inspection or test acceptance criteria:

(1) C reserve station service transformer (RSST) medium voltage cable submergence due to duct line sump pump 5B failure on March 7, 2024 (CR1267581)

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (3 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 operational risk assessment associated with investigation of condenser tube cooling water in-leakage on July 12, 2024

(2) Unit 1 and Unit 2 operational risk assessment associated with the AAC diesel maintenance during the week of July 28, 2024

(3) Unit 1 and Unit 2 operational risk assessment associated with 'B' spent fuel pit pump casing repair on September 20, 2024

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (3 Samples)

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

(1) CR1264526, 1-SW-P-1B-PUMP, B emergency service water pump, test flow in alert range with negative trend on July 18, 2024

(2) CR1265115, Trip hook engagement on 2-MS-TV-220, Unit 2 auxiliary feedwater pump turbine trip valve operator, on July 26, 2024

(3) CR1266240, 1-SW-P-10B, Unit 1 charging pump service water pump, seal leak on September 19, 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) SU-13-01168, Beyond Design Basis Diverse and Flexible Coping Strategy Support Modification

71111.20 - Refueling and Other Outage Activities

Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated Unit 1 refueling outage 1R32 activities from April 7, 2024, to June 8, 2024. The inspectors completed inspection procedure 71111.20, Sections 03.01(c)(11)(d) and 03.01(e).

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)0-ECM-1404-04, Motor Verification and Load Checks, following 1-VS-AC-06, Unit 1 main control room air handling unit, air handler check on July 2, 2024 (Work Order (WO) 38204301606)

(2)2-OP-CH-002, Charging Pump A Operations, following 2-CH-1-P-1A, Unit 2 A charging pump, motor leads inspection and repair on July 11, 2024 (WO38204346938)

(3)2-PT-41.1, Component Cooling Water Performance Test, following 1-CC-P-1D, D component cooling pump, mechanical seal replacement on August 2, 2024 (WO38204321009)

(4)0-OSP-AAC-001, Quarterly Test of 0-AAC-DG-0M, Alternate Alternating Current Diesel Generator, following AAC diesel generator 6-year planned maintenance on August 5, 2024 (WO38204199490)

(5)0-GMP-008, Drive Belt Inspection and Adjustment, following planned maintenance on 1-VS-F-41, main control room emergency ventilation fan motor, on September 17, 2024 (WO38204321477)

(6)0-OP-FC-004, Operating Spent Fuel Pit Pumps, following 1-FC-P-1B, B spent fuel pit cooling pump, casing leak repair on September 28, 2024 (WO38203873208)

Surveillance Testing (IP Section 03.01) (3 Samples)

(1)1-OPT-CS-002, Containment Spray System Test, on July 2, 2024 (2)2-OPT-FW-003, Turbine Driven Auxiliary Feedwater Pump 2-FW-P-2, and 2-OPT-FW-007, Turbine Driven AFW Pump Steam Supply Line Check Valve Test, on July 3, 2024 (3)1-OPT-RX-005, Control Rod Assembly Partial Movement, on September 9, 2024

Diverse and Flexible Coping Strategies (FLEX) Testing (IP Section 03.02) (1 Sample)

(1)0-MPM-1960-06, Beyond Design Basis High Capacity Pump Triennial Functional Testing 0-BDB-P-7, on July 16, 2024

71114.02 - Alert and Notification System Testing

Inspection Review (IP Section 02.01-02.04) (1 Sample)

(1) The inspectors evaluated the maintenance and testing of the alert and notification system during the week of September 23, 2024.

71114.03 - Emergency Response Organization Staffing and Augmentation System

Inspection Review (IP Section 02.01-02.02) (1 Sample)

(1) The inspectors evaluated the readiness of the emergency response organization (ERO) during the week of September 23, 2024.

71114.04 - Emergency Action Level and Emergency Plan Changes

Inspection Review (IP Section 02.01-02.03) (1 Sample)

(1) The inspectors evaluated submitted emergency action levels (EALs), emergency plan, and emergency plan implementing procedure changes during the week of September 23, 2024. This evaluation does not constitute NRC approval.

71114.05 - Maintenance of Emergency Preparedness

Inspection Review (IP Section 02.01 - 02.11) (1 Sample)

(1) The inspectors evaluated the maintenance of the emergency preparedness program during the week of September 23, 2024.

71114.06 - Drill Evaluation

Additional Drill and/or Training Evolution (1 Sample)

The inspectors evaluated:

(1) A simulator-based licensed operator requalification training evolution involving a manual reactor trip due to reactor coolant pump high vibration, and a small break loss of coolant accident without safety injection on August 13,

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:

MS06: Emergency AC Power Systems (IP Section 02.05)===

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

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

MS07: High Pressure Injection Systems (IP Section 02.06) (2 Samples)

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

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

MS08: Heat Removal Systems (IP Section 02.07) (2 Samples)

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

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

MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)

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

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

MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)

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

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

EP01: Drill/Exercise Performance (DEP) Sample (IP Section 02.12) (1 Sample)

(1) April 1, 2023, through June 30, 2024 EP02: Emergency Response Organization (ERO) Drill Participation (IP Section 02.13) (1 Sample)

(1) April 1, 2023, through June 30, 2024 EP03: Alert And Notification System (ANS) Reliability Sample (IP Section 02.14) (1 Sample)

(1) April 1, 2023, through June 30, 2024

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) Conservative decision to shutdown Unit 2 due to leaking pressurizer safety valve, 2-RC-SV-2551B (CR1230580)

(2) Results of Surry Unit 2 materials reliability program 227 Phase II (Spring 2023)

(CR1228568)

(3) Transient combustible program corrective actions (CR1236765, CA12171950, CA12157842, CA12195331, CA12195332)

71153 - Follow Up of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)

The inspectors evaluated the following licensees event reporting determinations to ensure it complied with reporting requirements.

(1) LER 05000280/2024-001-00, Troubleshooting Initiated Unknown Turbine Trip Feature in Control System, ADAMS Accession No. ML24212A077. The inspection conclusions associated with this LER are documented in this report under the Inspection Results Section. This LER is Closed.

INSPECTION RESULTS

Failure to Test Cables in Accordance with Aging Management Program Requirements Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000280,05000281/2024003-01 Open/Closed

[H.5] - Work Management 71111.12 The inspectors identified a Green finding of the licensee to test the C reserve station service transformer (RSST) medium voltage cables in accordance with the sites aging management program requirements as soon as practicable following exposure to significant moisture. This could have led to in-service cable insulation degradation and failure of C RSST to perform its function.

Description:

Each unit has two 4160 volt alternating current (AC) emergency buses. Each train is normally energized continuously from the switchyard external grid system. This primary source of power is available from the RSSTs via the transfer buses and is the preferred source during all plant modes of operation. The RSSTs that comprise the primary source are designated as A RSST, B RSST, and C RSST. The primary source is one of two credited physically independent offsite AC circuits in accordance with Technical Specification 3.16, Emergency Power System.

On March 7, 2024, the inspectors observed the licensees inspection of manhole 0-EP-MH-DL2, intake canal duct line sump pit. When the mechanics removed the cover, excessive water collection was discovered in the manhole and the 34.5 kilovolt (kV) cables for the C RSST were submerged. There are two duct line sump pumps in the manhole. Duct line sump pump 5B (1-PL-43-P5B) was in AUTO but there was no evidence of flow. Duct line sump pump 5A (1-PL-43-P5A) was caution tagged OFF due to a previous issue associated with the pump continuously running in AUTO. Operators placed duct line sump pump 5A in HAND (manual operation) and the pump operated as expected. Once the manhole was dewatered, the licensee proceeded with the inspection of the manhole and the cables. The licensee identified that the intake canal duct line sump pit high level alarm did not function in the control room to alert operators of the high-water level in the manhole. As a result of the deficient sump pumps and the high-level alarm, the licensee initiated a compensatory action to pump down the sump once a shift (every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />).

The licensee documented the as-found conditions of the manhole and equipment deficiencies in condition reports (CR)1252855, CR1253206, and CR1252880. In addition, the licensee initiated CR1253924 to request diagnostic testing of the C RSST 34.5 kV cables to assess cable health during 1R32 refueling outage, which was scheduled to start in April 2024.

The inspectors reviewed associated conditions reports; licensee logs and evaluations; licensee aging management program procedures; Surry Power Station Updated Final Safety Analysis Report, Revision 55.02 dated January 24, 2024; and NUREG-1766, Safety Evaluation Report Related to the License Renewal of North Anna Power Station, Units 1 and 2, and Surry Power Station, Units 1 and 2, to determine if the licensees response was in accordance with the licensees aging management program requirements and NRC commitments.

Based on the inspectors review, the cables were potentially submerged for 8 days. This is based on the period between the last known operation of the sump pumps on February 28, 2024, and the discovery of the water collection in the manhole on March 7, 2024. The concern for submerged cable is water-related insulation degradation (e.g., water treeing),which could lead to failure of the cable. In the review of CR1253924 regarding the request to perform diagnostic testing, the inspectors found that the Outage and Planning department did not scope the C RSST cable testing in 1R32 refueling outage as requested by the Engineering department. Following this decision, the licensee did not initiate a corrective action to schedule the testing at the next practicable opportunity.

The inspectors concluded that the cables were not tested as soon as practicable in accordance with the requirements of the licensees aging management program. ER-AA-CBL-103, Evaluation and Testing of Medium Voltage Cables, Attachment 5, Action Required for High Risk Cables Exposed to Adverse Environment, for wet conditions, shielded cables, no splices, required that MV [medium voltage] cables that are in scope of Subsequent License Renewal and are exposed to Significant Moisture shall be tested as soon as practicable following the Significant Moisture event to determine cable condition.

Contrary to this requirement, the licensee did not test the C RSST cable as soon as practicable following exposure to significant moisture for potentially 8 days from February 28, 2024, through March 7, 2024. The licensees aging management program defined significant moisture as long-term wetting or submergence for more than three days.

Corrective Actions: The licensee entered this issue into their corrective action program and scoped the C RSST cable testing into the next Unit 1 refueling outage.

Corrective Action References: CR1267581

Performance Assessment:

Performance Deficiency: The inspectors determined that the licensee's failure to test the C RSST medium voltage cables following exposure to significant moisture as soon as practicable in accordance with the requirements of their aging management program was a performance deficiency that was reasonably within the licensee's ability to foresee and correct.

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 failure of the licensee to perform testing to assess cable condition affected the cornerstone objective of ensuring reliability. The performance deficiency could have led to in-service degradation of the cable insulation and resultant failure of C RSST to perform its function. The inspectors used IMC 0612, Appendix E, Examples of Minor Issues, dated November 1, 2023, to inform answers to the more than minor screening questions and found this condition consistent with more than minor example 13.a.

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 screens as very low safety significance (Green) because it was a design or qualification deficiency of a mitigating SSC that maintained its probabilistic risk assessment function.

Cross-Cutting Aspect: H.5 - Work Management: The organization implements a process of planning, controlling, and executing work activities such that nuclear safety is the overriding priority. The work process includes the identification and management of risk commensurate to the work and the need for coordination with different groups or job activities. Specifically, the licensee did not implement a work process that emphasized nuclear safety as the overriding priority and did not coordinate with different groups to ensure that the C RSST cables were tested as soon as practicable.

Enforcement:

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

Failure to Implement Design Change Process during Turbine Control System Upgrade Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000280/2024003-02 Open/Closed

[H.12] - Avoid Complacency 71153 A self-revealed Green finding was identified when the licensee failed to provide design control measures for ensuring the adequacy of the turbine control system (TCS) upgrade project, which resulted in a flawed TCS trip logic to not be corrected and tested. This flawed TCS trip logic was the root cause of a reactor trip.

Description:

On June 2, 2024, at 1708, Surry Unit 1 experienced an uncomplicated automatic reactor trip due to a turbine trip at approximately 13 percent reactor power, during power ascension following a refueling outage. The turbine tripped while the operators were attempting to reset the TCS after identifying that the TCS did not transition from speed control mode to load control mode following synchronization to the electrical grid.

Operators placed the unit online at 1428 on June 2, 2024, and noted that turbine load was slowly increasing, the TCS was in the speed control mode, and the main generator output breaker cycling test mode was enabled. Normally, the TCS transitions automatically to the load control mode following synchronization. However, with the breaker cycling test mode enabled, the TCS could not automatically transition to speed control mode (see NCV 05000280/2024002-01, "Failure to Maintain Adequate Procedure to Ensure Plant Stability," in SURRY POWER STATION-INTEGRATED INSPECTION REPORT 05000280/2024002 AND 05000281/2024002 DATED AUGUST 1, 2024). The licensee performed troubleshooting to disenable the test mode. However, the licensee was unaware that the turbine trip logic was partially made up, and the troubleshooting efforts to reset the TCS resulted in completing the logic for a turbine trip. This led to a turbine trip and subsequent reactor trip.

The licensee performed a post-trip review and a root cause evaluation to determine the cause of the turbine trip/reactor trip. They determined that a flawed TCS trip logic design was introduced in 2022 during Unit 1 TCS digital upgrade, and it was not corrected during the engineering review process. The flawed TCS trip logic was associated with the remote input/output failure trip where a signal from two redundant remote node interfaces (RNI)

[primary and partner] and status signal from two main generator output breakers are used to decide on a turbine trip. This trip logic triggers when the partner RNI is in control and both main generator output breakers status are bad or open. The licensee was not aware of the existence of this trip logic, and subsequently from their troubleshooting effort to recover from the breaker cycling test mode, changed both main generator output breaker status to bad.

The partner RNI was already in control, which completed the trip logic.

The inspectors reviewed Surry Licensee Event Report 05000280/2024-001-00, Troubleshooting Initiated Unknown Turbine Trip Feature in Control System, and associated documents, including the root cause evaluation. The inspectors noted that during the design review, a licensee reviewer made a comment concerning the need for a TCS remote input/output failure trip feature. The vendor revised the trip feature and provided comment that the revised trip feature may not be needed anymore and suggested factory acceptance testing (FAT) to confirm. The resolution was accepted by the reviewer, but the trip feature was not tracked to ensure that it was updated in the functional design specification and included in the FAT procedure. Additionally, the requirements traceability matrix (an error reduction tool used to a prevent a design specification for a specified function being omitted in the FAT) was not updated to reflect the new testable trip feature.

The inspectors concluded that the licensee did not implement the requirements of licensee procedure DNES-AA-GN-1001, Engineering Review, Section 3.0, Instructions, during the Owners Review of the design change associated with the TCS digital upgrade project. The procedure requires [a]dequate identification and tracking of comments, resolutions, and dispositions is to be performed throughout the engineering review. Contrary to this requirement, the flawed logic, which was identified during the engineering review, was not documented and tracked. Specifically, this resulted in the flawed logic not being corrected and tested during the FAT and subsequently, was the root cause of a reactor trip.

Corrective Actions: The licensee completed immediate corrective actions to restore the plant configuration to the expected state and performed a root cause evaluation of the event to determine the root cause and contributing causes. The licensee initiated corrective action assignments to improve several design change procedures to mitigate future occurrence of potentially similar issues. Also, the licensee initiated corrective action assignments to implement a design change to remove the flawed TCS trip logic from Unit 1 and Unit 2 during their next respective refueling outage and perform additional reviews of existing digital upgrade project design changes.

Corrective Action References: CR1260948

Performance Assessment:

Performance Deficiency: The inspectors determined that the licensees failure to perform design reviews and acceptance testing in accordance with stations procedures was a performance deficiency that was reasonably within the licensees ability to foresee and correct.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control 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, the flawed TCS trip logic design was the root cause of a reactor trip. The inspectors used IMC 0612, Appendix E, Examples of Minor Issues, dated November 1, 2023, to inform answers to the more than minor screening questions and found this condition consistent with more than minor example 4.b.

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, Section B, Transient Initiators, the inspectors determined the finding was of very low safety significance (Green), because the finding did not result in a reactor trip AND the loss of mitigation equipment relied upon to transition the plant from the onset of the trip to a stable shutdown condition.

Cross-Cutting Aspect: H.12 - Avoid Complacency: Individuals recognize and plan for the possibility of mistakes, latent issues, and inherent risk, even while expecting successful outcomes. Individuals implement appropriate error reduction tools. Specifically, the licensee did not implement appropriate error reduction tools during the engineering review and did not track the accepted comment resolution. This allowed the flawed logic to be remain uncorrected and not tested during the FAT, and subsequently, was the root cause of a reactor trip.

Enforcement:

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

EXIT MEETINGS AND DEBRIEFS

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

• On October 3, 2024, the inspectors presented the integrated inspection results to David Wilson, Site Vice President, and other members of the licensee staff.

• On September 26, 2024, the inspectors presented the emergency preparedness baseline program inspection results to David Wilson, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

71114.04

Procedures

Surry Power Station Emergency Plan

Rev. 74