IR 05000395/2023004

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Integrated Inspection Report 05000395/2023004
ML24026A161
Person / Time
Site: Summer South Carolina Electric & Gas Company icon.png
Issue date: 01/31/2024
From: David Dumbacher
NRC/RGN-II/DRP/RPB3
To: Carr E
Dominion Energy Co
References
IR 2023004
Download: ML24026A161 (14)


Text

January 31, 2024

SUBJECT:

VIRGIL C. SUMMER - INTEGRATED INSPECTION REPORT 05000395/2023004

Dear Eric S. Carr:

On December 31, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Virgil C. Summer. On January 25, 2024, the NRC inspectors discussed the results of this inspection with Mr. Robert Justice, Site Vice President, and other members of your staff.

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

One finding of very low safety significance (Green) is documented in this report. This finding did not involve a violation of NRC requirements.

If you disagree with 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 Virgil C. Summer. 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, Signed by Dumbacher, David on 01/31/24 David E. Dumbacher, Chief Reactor Projects Branch 3 Division of Reactor Projects Docket No. 05000395 License No. NPF-12

Enclosure:

As stated

Inspection Report

Docket Number: 05000395 License Number: NPF-12 Report Number: 05000395/2023004 Enterprise Identifier: I-2023-004-0061 Licensee: Dominion Energy Facility: Virgil C. Summer Location: Jenkinsville, SC Inspection Dates: October 01, 2023 to December 31, 2023 Inspectors: B. Bishop, Sr. Project Engineer T. McGowan, Resident Inspector K. Pfeil, Resident Inspector M. Read, Sr. Resident Inspector E. Rosario, Reactor Inspector Approved By: David E. Dumbacher, Chief Reactor Projects Branch 3 Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Virgil C. Summer, 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 Properly Assemble Main Feedwater Pump Bearing Wear Detector Resulting in Pump Trip and Manual Reactor Trip Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green None (NPP) 71153 FIN 05000395/2023004-01 Open A self-revealed Green finding was identified when the licensee failed to properly assemble the

'C' main feedwater pump (MFP) active thrust bearing wear detector in 2014. As a result of inadequate clearance, the margin to an automatic trip of the 'C' MFP was reduced. On April 5, 2023, the 'B' MFP had been secured as a part of normal shutdown procedures, and the 'C'

MFP tripped, forcing operators to manually trip the reactor.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000395/2023-001-00 LER 2023-001-00 for Virgil 71153 Closed C. Summer Nuclear Station (VCSN), Unit 1, Manual Reactor Trip Due to Loss of Main Feedwater Pump

PLANT STATUS

The unit operated at or near rated thermal power (RTP) 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.

REACTOR SAFETY

71111.01 - Adverse Weather Protection

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

(1) The inspectors evaluated readiness prior to the onset of seasonal cold temperatures for the following systems/areas:

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (2 Samples)

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

(1) 'B' EDG (protected train, electrical lineup, and valve lineup) on October 10, 2023
(2) 'A' EDG while the 'B' EDG was out of service for maintenance activities, on November 14, 2023.

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) Diesel Generator Building, elevation 436 (A and B EDG trains) on October 2, 2023
(2) Control Building, elevation 425 (cable spreading room area and below grade office spaces) on October 13, 2023
(3) Control Building, elevation 448 on October 17, 2023
(4) Control Building, elevation 412 on October 19, 2023
(5) Relay room and heat detector testing on November 6, 2023

71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance

Requalification Examination Results (IP Section 03.03) (1 Sample)

(1) The licensee completed the annual requalification operating examinations and biennial written examinations required to be administered to all licensed operators in accordance with Title 10 of the Code of Federal Regulations 55.59(a)(2),

"Requalification Requirements," of the NRC's "Operator's Licenses." The inspector performed an in-office review of the overall pass/fail results of the individual operating examinations, the crew simulator operating examinations, and the biennial written examinations in accordance with Inspection Procedure (IP) 71111.11, "Licensed Operator Requalification Program and Licensed Operator Performance." These results were compared to the thresholds established in Section 3.03, "Requalification Examination Results," of IP 71111.11.

The inspectors evaluated the licensed operator examination failure rates for the requalification annual operating examinations completed on August 24, 2023, and the biennial written examinations completed on August 24, 2023.

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 STP-106.001, "Moveable Rod Insertion Test," on November 2, 2023, and operator response to an unplanned reset of a group demand step counter.

Additionally, the inspectors observed and evaluated licensed operator performance in the control room while lowering reactor power from 100 percent to 90 percent RTP in preparation for main turbine valve stroke testing on November 27, 2023.

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (3 Samples)

(1) The inspectors observed and evaluated simulator (crew D) using simulator exercise guide (SEG), ID #O-LOR-SIM-SA-10R on October 18, 2023
(2) The inspectors observed licensed operator requalification simulator training exercise involving response to high reactor coolant pump vibrations, inadvertent reactor building spray actuation, and reactor trips involving stuck control rods on November 21, 2023
(3) Inspectors observed licensed operator requalification simulator training exercise involving the loss of a main feedwater pump, failure of the steam generator level controller, and response to a steam generator tube leak on December 13, 2023

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (3 Samples)

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

(1) 'B' chiller compressor replacement degraded condition on heating, ventilation, and air conditioning system mechanical water chiller 'B' completed on October 26, 2023
(2) Fire service system, review completed on November 3, 2023
(3) Cycle 27 periodic assessment per 10 CFR 50.65(a)(3), review completed on December 1, 2023

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (1 Sample)

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) Elevated risk during 'A' residual heat removal system maintenance on October 30, 2023

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) CR 1240688, turbine driven emergency feedwater (TDEFW) pump lube oil pressure did not engage with the trip level with TDEFW pump running (STP-220.002), review completed on October 20, 2023
(2) CR1240383, testing equipment found out of calibration, review completed on October 20, 2023
(3) CR1245223, diesel-driven fire pump did not trip on overspeed during testing, review completed on December 4, 2023

71111.18 - Plant Modifications

Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (2 Samples)

The inspectors evaluated the following temporary or permanent modifications:

(1) ECR-51010, safety-related battery racks modification to increase seismic resilience, review completed on November 2, 2023
(2) ECR-50863, service water pump flow improvements, review completed on October 19, 2023

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)

(1) PTP-113.002, 'A' chiller testing following preventative maintenance, on October 12, 2023.
(2) SOP-115, running the residual heat removal pump and stroking valves, following pump, valve, and breaker maintenance on October 30, 2023.
(3) 'C' component cooling water pump, following motor maintenance, on November 2, 2023.
(4) PTP-114.101, testing of the diesel-driven fire service pump, following minor instrumentation and control maintenance activities, on November 30, 2023.
(5) ERMP-100.012, FLEX heat sink lift pump, following pump oil change, on December 12, 2023

Surveillance Testing (IP Section 03.01) (2 Samples)

(1) Solid state protection system actuation logic and master relay test, 'A' train, categorized as medium risk on October 13, 2023
(2) STP-125.013B, Diesel Generator 'B' Semiannual Operability Test, review completed on October 18, 2023

Inservice Testing (IST) (IP Section 03.01) (2 Samples)

(1) STP-220.001A, motor-driven emergency feedwater pump and valve test, on October 3, 2023
(2) STP-225.001A, testing 'B' emergency diesel generator fuel oil system transfer pump and air start system valves, on October 18, 2023

71114.06 - Drill Evaluation

Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated a drill involving a loss of charging, seismic event, and release of radioactive materials on October 25,

OTHER ACTIVITIES - BASELINE

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

MS05: Safety System Functional Failures (SSFFs) Sample (IP Section 02.04) ===

(1) Unit 1 (October 1, 2022, through September 30, 2023)

MS08: Heat Removal Systems (IP Section 02.07) (1 Sample)

(1) Unit 1 (October 1, 2022, through September 30, 2023)

MS10: Cooling Water Support Systems (IP Section 02.09) (1 Sample)

(1) Unit 1 (October 1, 2022, through September 30, 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) CR1221359, emergency declaration and notification drill and exercise failures from interim emergency directors during periodic testing. Inspectors reviewed licensee corrective actions, procedural changes which may have affected some of the drill performance by participants, and interviewed training and emergency preparedness staff. Inspectors did not identify a violation of regulatory requirements because the failures were self-identified and corrective actions were established. The review was completed on October 27, 2023.
(2) CR1226494 and CR1232796, welds completed with incorrect filler material.

Inspectors assessed the licensees evaluation of the issue to determine if appropriate corrective actions were established following multiple human performance errors that resulted in incorrect performance of non-safety-related welds in the main steam system. In addition, the inspectors reviewed the licensee's extent of condition and corrective actions that were intended to improve procedure compliance and training for supplemental personnel. The review was completed on November 3, 2023. The inspection conclusions associated with this review are documented in this report under Inspection Results section 71152A.

71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02)

(1) The inspectors reviewed the licensees corrective action program for potential adverse trends in electrical subcomponents associated with the EDG that might be indicative of a more significant safety issue. The review was completed on December 12, 2023.

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

The inspectors evaluated the following licensee event reports (LERs):

(1) LER 05000395/2023-001-00, Manual Reactor Trip Due to Loss of Main Feedwater Pump (ADAMS Accession No. ML23150A162). The inspection conclusions associated with this LER are documented in this report under Inspection Results Section 71153. This LER is closed.

INSPECTION RESULTS

Minor Performance Deficiency 71152A Minor Performance Deficiency: The licensee failed to follow licensee procedure WM-1.0, Welding Manual Procedure, Revision 16, when incorrect filler material was used during welding activities on the main steam system. Specifically, the welding activities were governed by licensee procedure WM-1.0, and were controlled using properly approved weld travelers, welding procedures, and material requisition forms, however, supplemental welders and a quality control verifier did not recognize that one of the welds in a package required a different filler material. The use of an unapproved weld filler material was not in compliance with licensee procedure WM-1.0, Step 5.8.3, which stated, "Welding material shall conform to the requirements of the applicable construction code or specification and the applicable WPS(s). All welding material shall be issued and controlled in accordance with Welding Material Procedure WM-2.0." The inspectors did not identify any violations of regulatory requirements during the review.

Screening: The inspectors determined the performance deficiency was minor. Due to the welds being on a portion of the main steam system that would not cause a significant transient if the welds failed, the incorrect filler material would not be a precursor to a significant event, would not have the potential to lead to a more significant safety concern, and did not affect the cornerstone objectives documented in Inspector Manual Chapter 0612, Appendix B, dated August 9, 2023.

Failure to Properly Assemble Main Feedwater Pump Bearing Wear Detector Resulting in Pump Trip and Manual Reactor Trip Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green None (NPP) 71153 FIN 05000395/2023004-01 Open/Closed A self-revealed Green finding was identified when the licensee failed to properly assemble the 'C' MFP active thrust bearing wear detector in 2014. As a result of inadequate clearance, the margin to an automatic trip of the 'C' MFP was reduced. On April 5, 2023, the 'B' MFP had been secured as a part of normal shutdown procedures, and the 'C' MFP tripped, forcing operators to manually trip the reactor.

Description:

On April 5, 2023, the 'B' MFP had been secured as a part of normal shutdown procedures for a refueling outage. One hour later, while at 85 percent rated thermal power, the 'C' MFP automatically tripped, forcing operators to manually trip the reactor. The post-trip response by the plant and operators was as expected, with emergency feedwater automatically starting due to steam generator water levels.

Following disassembly of the 'C' MFP, the licensee identified that the active thrust bearing wear detector clearance was set too close, contrary to the manufacture's specifications. The thrust bearing wear device is comprised of a pair of oil nozzles ported into two blocks that are spaced over a sensing disk. The sensing disk is mounted on the turbine rotor. The oil nozzle blocks are fixed in place and are bolted to the turbine thrust bearing housing. The spacing of the nozzle blocks on each side of the sensing disk are established by the use of two shims. If the turbine rotor moves axially due to thrust bearing wear, the spacing between the sensing disk and the oil nozzle will decrease, causing the signal oil flow to be restricted, increasing the back pressure in the oil sensing line. On April 5, 2023, the sensing line pressure increased to the automatic trip setpoint.

The detector was last modified by a contractor during a refueling outage in 2014. Per the vendor manual 1MS-94B-0133, the thrust bearing wear device is set at the factory and should not require further adjustments. The 'C' MFP rotor was replaced in 2014, and the inspection report provided by the vendor following the replacement indicated that the thrust bearing wear device was inspected, although no values were provided to document the shim thickness or nozzle block clearances. The licensee utilized a vendor to perform the work with vendor supervisors and engineers. Inspectors could not determine what level of oversight was provided by licensee personnel.

Corrective Actions: Following the event, the licensee corrected the installation of the 'C' MFP active thrust bearing wear detector and ensured that 'A' and 'B' MFPs were within allowable tolerances. The licensee also implemented a design change to install pressure gauges on both the active and inactive thrust bearing wear detector oil sensing lines to allow for online monitoring.

Corrective Action References: CR1223268

Performance Assessment:

Performance Deficiency: The inspectors determined the failure to properly assemble the 'C' MFP active thrust bearing wear detector in 2014, following rotor replacement, was a performance deficiency. Specifically, the licensee failed to ensure that the active thrust bearing wear detector clearance was assembled in accordance with the vendor manual 1MS-94B-0133, which provided allowable clearances. This led to a reduction in margin to the trip setpoint. The trip of the 'C' MFP and due to plant conditions on April 5, 2023, caused operators to manually trip the reactor.

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 failure of the active thrust bearing wear detector for the 'C' MFP pump resulted in a reduction of the margin to the trip setpoint, and caused operators to manually trip the reactor.

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 Initiator", the inspectors determined the finding was of low safety significance (Green) because although the finding did cause a reactor trip and a loss of 'C' MFP with the 'B' MFP secured, there was no loss of main feedwater flow because the 'A' MFP remained running.

Cross-Cutting Aspect: Not Present Performance. No cross-cutting aspect was assigned to this finding because the inspectors determined the finding did not reflect present licensee performance.

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 January 25, 2024, the inspectors presented the integrated inspection results to Mr.

Robert Justice, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.11Q Miscellaneous SEG (Simulator Simulator Exercise Guide (scenario on file) - CREW D 5

Exercise Guide) -

LMS ID: O-LOR-

SIM-10R

71152A Miscellaneous Weld travelers for 7/12/2023

weld record

1907685-009

71152A Miscellaneous Work order 201695195

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