IR 05000424/2024004
| ML25036A017 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 02/11/2025 |
| From: | Alan Blamey NRC/RGN-II/DORS/PB3 |
| To: | Coleman J Southern Nuclear Operating Co |
| References | |
| IR 2024004 | |
| Download: ML25036A017 (1) | |
Text
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000424/2024004 AND 05000425/2024004
Dear Jamie Coleman:
On December 31, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Vogtle Electric Generating Plant, Units 1 and 2. On January 16, 2025, the NRC inspectors discussed the results of this inspection with J. Weissinger, 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. Two of these findings involved violations of NRC requirements. 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 II; the Director, Office of Enforcement; and the NRC Resident Inspector at Vogtle Electric Generating Plant, Units 1 and 2.
If you disagree with a cross-cutting aspect assignment 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 Vogtle Electric Generating Plant, Units 1 and 2.
February 11, 2025 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, Alan J. Blamey, Chief Reactor Projects Branch 3 Division of Operating Reactor Safety Docket Nos. 05000424 and 05000425 License Nos. NPF-68 and NPF-81
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000424 and 05000425
License Numbers:
Report Numbers:
05000424/2024004 and 05000425/2024004
Enterprise Identifier:
I-2024-004-0027
Licensee:
Southern Nuclear Operating Company, Inc
Facility:
Vogtle Electric Generating Plant, Units 1 and 2
Location:
Waynesboro, GA
Inspection Dates:
October 01, 2024 to December 31, 2024
Inspectors:
A. Alen Arias, Senior Project Engineer
K. Kirchbaum, Senior Operations Engineer
T. Morrissey, Senior Resident Inspector
J. Parent, Senior Resident Inspector
D. Willis, Team Leader
Approved By:
Alan J. Blamey, Chief
Reactor Projects Branch 3
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees
performance by conducting an integrated inspection at Vogtle Electric Generating 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
Failure to Identify a Condition Adverse to Quality on 1E Safety-Related 125 VDC Emergency
Battery
Cornerstone
Significance
Cross-Cutting
Aspect
Report
Section
Mitigating
Systems
Green
Open/Closed
[H.1] -
Resources
The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for the licensees failure to identify and
correct a condition adverse to quality (CAQ). Specifically, the licensee failed to recognize the
severe corrosion of the 1B battery's (1BD1B 1E safety-related battery) bus bars as a CAQ
that needed to be identified and promptly corrected.
Failure to Correct a Condition Adverse to Quality Resulted in Premature Failures of
Regulating Transformers
Cornerstone
Significance
Cross-Cutting
Aspect
Report
Section
Mitigating
Systems
Green
NCV 05000424,05000425/2024004-02
Open/Closed
[P.3] -
Resolution
The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for the licensees failure to implement
timely corrective actions for a condition adverse to quality (CAQ) involving manufacturing
deficiencies of safety-related regulating transformers (RTs), leading to premature transformer
failures and fires.
Additional Tracking Items
None.
PLANT STATUS
Unit 1 began the inspection period shutdown for a planned refueling outage (1R25) that began
September 8, 2024. On October 3, 2024, the unit was restarted and on October 7, 2024, the
unit was returned to rated thermal power (RTP). On November 3, 2024, power was reduced to
approximately 62 % RTP to replace the 1A heater drain pump mechanical seal. The unit
returned to RTP on November 5, 2024. On November 25, 2024, power was reduced to
approximately 92 % RTP for several hours to perform a planned main generator turbine valve
stroke test. The unit remained at or near RTP for the remainder of the inspection period.
Unit 2 began the inspection period at RTP. On November 15, 2024, power was reduced to
approximately 93 % RTP for several hours to perform a planned main generator turbine valve
stroke test. The unit remained at or near RTP for the remainder of the 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 DProperty "Inspection Manual Chapter" (as page type) with input value "NRC Inspection Manual 2515,</br></br>Appendix D" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process., 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
71111.04 - 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, turbine-driven auxiliary feed water (TDAFW) and train A motor-driven AFW
pump trains while train B motor-driven AFW pump was out of service (OOS) for
planned maintenance, on October 28, 2024
(2)
Unit 2, train B safety injection (SI) system while train A SI system was OOS for
planned maintenance, on November 14, 2024
(3)
Unit 1, train A emergency diesel generator (EDG) while train B safety-related
battery (1BD1B) and train B EDG were OOS for planned maintenance, on
November 18, 2024
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (4 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)
Fire zones 4 and 5, unit 2 containment spray pump rooms, on October 10, 2024
(2)
Fire zones 165, 166, unit 2 EDG fuel oil storage tank building, on November 1, 2024
(3)
Fire zones 91, 92, 97, 98, and 103, unit 2 control building level A 4.16 KV switchgear
and remote shutdown rooms, on November 13, 2024
(4)
Fire zones 145, 146, 160A, 160B, unit 1 train A and B nuclear service cooling water
(NSCW) pump rooms and associated electrical/mechanical tunnels, on November 24,
2024
71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance
Requalification Examination Results (IP Section 03.03) (1 Sample)
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
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.
(1)
The inspectors reviewed and evaluated the licensed operator examination failure
rates for the requalification annual operating exam administered on July 9, 2024 and
the biennial written examinations completed on November 21, 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 125V DC Class-1E power distribution system
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, elevated risk due to train B motor-driven AFW pump OOS for planned
maintenance, on October 28, 2024
(2)
Unit 2, elevated risk due to train A SI pump OOS for planned maintenance, on
November 14, 2024
(3)
Unit 1, elevated risk due to B train EDG OOS for planned maintenance with B train
safety-related battery 1DB1B, regulating transformer 1BBC42RX and "B" train nuclear
service cooling water individually OOS from November 18-21, 2024
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (4 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the
following operability determinations and functionality assessments:
(1)
Condition report (CR) 11118809 Unit 1 train A safety-related battery's (1AD1B)
capacity decreased from 97.63 % to 82.33 % during modified performance test, on
October 14, 2024
(2)
CR 11123823 Unit 1 train "B" safety-related battery (1BD1B) bank degradation, on
November 4, 2024
(3)
CR 11116010, maintenance and test equipment previously used for in-service testing
of both unit's component cooling water system pump 5 found failed, on November 25,
2024
(4)
CR 11134439, Unit 2 train A NSCW blowdown valve failed to close during
surveillance testing, on December 11, 2024
71111.20 - Refueling and Other Outage Activities
Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)
(1)
The inspectors evaluated unit 1 cycle 25 refueling outage (1R25) from October 1,
2024 to October 3, 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) (5 Samples)
(1)
14810-1, "TDAFW Pump & Check Valve in-service test (IST) Response Time Test,"
following controller replacement on October 2, 2024; work order (WO) SNC1024570
(2)
14825-1, "Quarterly Inservice Valve Test," following planned maintenance on valve
1HV5125, TDAFW discharge valve steam generator #2 on October 16, 2024; WO
SNC1324020
(3)
14825-2, "Quarterly Inservice Valve Test," on valve 2PV3000 (steam generator (SG)
- 1 atmospheric relief valve) following planned maintenance on October 19, 2024; WO
SNC1184682
(4)
14825-1, "Quarterly Inservice Valve Test," following planned maintenance on valves
1HV5132 and 1HV5134, B motor driven auxiliary feedwater pump discharge valves
on October 28, 2024; WO SNC1160655
(5)
13105-2, "Safety Injection System," following planned maintenance on SI system train
A on November 14, 2024; WO SNC1306854
Surveillance Testing (IP Section 03.01) (2 Samples)
(1)
14805A-2, "Train A Residual Heat Removal Pump IST and Response Time Test," on
October 15, 2024
(2)
14670B-2, "Diesel Generator 2B Hot Restart Test," on October 28, 2024
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) (2 Samples)
(1)
Unit 1 (October 1, 2023, through September 30, 2024)
(2)
Unit 2 (October 1, 2023, through September 30, 2024)
MS06: Emergency AC Power Systems (IP Section 02.05) (2 Samples)
(1)
Unit 1 (October 1, 2023, through September 30, 2024)
(2)
Unit 2 (October 1, 2023, through September 30, 2024)
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
(1)
Unit 1 (October 1, 2023, through September 30, 2024)
(2)
Unit 2 (October 1, 2023, through September 30, 2024)
71152A - Annual Follow-up Problem Identification and Resolution
Annual Follow-up of Selected Issues (Section 03.03) (2 Samples)
The inspectors reviewed the licensees implementation of its corrective action program
related to the following issues:
(1)
CR 11101526, August 13, 2024, regulating transformer 2BBA02RX fire
(2)
The inspectors conducted interviews and reviewed corrective actions associated with
the environment for reporting fatigue and safety concerns in a department. The
inspectors conducted interviews of 40 personnel in the department from three
different teams, reviewed corrective actions associated with the safety culture within
the department and reviewed Employee Concerns Program (ECP) assessments of
the department.
The inspectors determined that all personnel interviewed stated that they would feel
free to raise a nuclear safety or security concern to their management or ECP. Also,
while most personnel were knowledgeable of the corrective action program (CAP),
they generally preferred to raise a concern to their supervisors for resolution.
When it comes to reporting fatigue, the majority of personnel interviewed stated that
they believed they could receive a negative reaction from management if they
reported fatigue. In addition, when asked if they believe others are afraid of reporting
fatigue, the majority still believed other employees within the department may be
hesitant to report fatigue. In the area of respectful work environment, most personnel
stated that the department was not respected at the site and that morale was low
within the department. The ECP had identified that the environment had improved in
the department over the summer, however, several challenges such as back-to-back
outages, attrition of personnel, and a hurricane stressed the department for
resources. Additionally, the NRC previously established minimum staffing levels and
fitness for duty requirements, that ensure sufficient staffing levels and rest periods to
prevent fatigue. The licensee continues to meet these requirements, and the NRC will
continue to independently inspect this area to confirm the required minimum staffing
and fitness for duty requirements are met. The inspectors observations were shared
with the stations management who will continue to work with ECP to identify
additional corrective actions, as necessary, to address these perceptions.
71152S - Semiannual Trend Problem Identification and Resolution
Semiannual Trend Review (Section 03.02) (1 Sample)
(1)
The inspectors reviewed the licensees CAP for potential adverse trends associated
with regulating transformer failures/fires that might be indicative of a more significant
safety issue.
INSPECTION RESULTS
Failure to Identify a Condition Adverse to Quality on 1E Safety-Related 125 VDC Emergency
Battery
Cornerstone
Significance
Cross-Cutting
Aspect
Report
Section
Mitigating
Systems
Green
Open/Closed
[H.1] -
Resources
The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for the licensees failure to identify
and correct a condition adverse to quality (CAQ). Specifically, the licensee failed to recognize
the severe corrosion of the 1B battery's (1BD1B 1E safety-related battery) bus bars as a CAQ
that needed to be identified and promptly corrected.
Description: On October 24, 2024, the inspectors observed maintenance personnel
performing preventive maintenance (PM) on the 1B battery per procedure 28912B-1,
"184Day Unit 1 B Train Safety Related Battery and Charger Inspection and
Maintenance. The maintenance included removal of bus bar corrosion to the extent practical,
use of a neutralizing agent and application of a non-oxide grease to limit further
corrosion. Following the completed PM, the inspectors inspected the 1B battery and
observed extensive deterioration of the two positive bus bars of cell #25. The inspectors
reviewed recent 1B battery condition reports (CRs) and determined that the licensee had not
documented this severe bus bar corrosion in the corrective action program (CAP) as required
per NMP-GM-002-001, Corrective Action Program Instructions. On October 30, 2024, after
the inspectors discussed this issue with the licensee, the licensee entered the issue into the
CAP (CR 11123823).
As part of the operability evaluation, the licensee measured the physical dimensions of the
two bus bars and determined that half of the cross-sectional area of the two bus bars had
corroded away. The licensee evaluation concluded, that the 1B battery remained operable
with margin.
The inspectors noted the licensee initially screened CR 11123823, "NRC identified 1BD1B
battery bank degradation," as a non-CAP issue instead of a CAQ. CAP procedure NMP-GM-
002-001, "Corrective Action Program Instructions," version 51.0, step 4.2.2, requires, in part,
to initiate a CR to identify a condition or problem that needs correcting. Additionally,
Section 3.1 of Attachment 2 of the procedure identifies examples of CAQs, that includes, in
part, a condition with a risk of inhibiting a safety related component from satisfactorily
performing its safety-related function. Conditions adverse to quality require corrective action
WOs that are tracked to completion and elevate the priority of the WO needed to correct the
condition in a timely manner. The extent of the battery bus bars degradation, noted by
previous maintenance activities, and identified by the NRC inspectors on October 29, 2024,
coupled with the active and accelerated corrosion rate affecting the bus bars had the potential
to inhibit the safety-related battery from satisfactorily performing its function, if not corrected
in a timely manner. This should have been captured in the licensee's CAP as a CAQ as
required by NMP-GM-002-001.
Corrective Actions: The licensee later re-screened CR 11123823 as a Priority 2 CAQ. On
November 18, 2024, WO SNC2121192, replaced seven pairs of bus bars including those for
cell #25.
Corrective Action References: CR 11123823, CR 11113493, CR 11027185
Performance Assessment:
Performance Deficiency: The licensees failure to implement NMP-GM-002-001, Corrective
Action Program Instructions, to identify a CAQ associated with severe degradation of a 1E
safety-related batterys bus bars and its potential effect on the operability of the battery was a
performance deficiency.
Screening: The inspectors determined the performance deficiency was more than minor
because if left uncorrected, it would have the potential to lead to a more significant safety
concern. Specifically, uncorrected accelerated corrosion of the 1B batterys bus bars with no
corrective actions would eventually reach a point where there would not have been enough
cross-sectional area material to carry the design basis event current required of the battery.
Significance: The inspectors assessed the significance of the finding using IMC 0609
Appendix AProperty "Inspection Manual Chapter" (as page type) with input value "NRC Inspection Manual 0609</br></br>Appendix A" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process., The Significance Determination Process (SDP) for Findings At-Power. Utilizing
Exhibit 2, the inspectors screened the finding as Green because the mitigating system
maintained its operability.
Cross-Cutting Aspect: H.1 - Resources: Leaders ensure that personnel, equipment,
procedures, and other resources are available and adequate to support nuclear safety.
Specifically, the licensee failed to ensure battery preventive maintenance would adequately
identify and trend battery degradation.
Enforcement:
Violation: Title 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, requires, in
part, that measures shall be established to assure that conditions adverse to quality, such as
failures, malfunctions, deficiencies, deviations, defective material and equipment, and
nonconformances are promptly identified and corrected.
Contrary to the above, from October 24, 2024, to October 30, 2024, the licensee failed to
assure that conditions adverse to quality, such as failures, malfunctions, deficiencies,
deviations, defective material and equipment, and nonconformances were promptly identified
and corrected. Specifically, the licensee failed to identify the condition of the 1B battery as a
CAQ to initiate prompt corrective action, in accordance with CAP procedure NMP-GM-002-
001, during maintenance activities.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with
Section 2.3.2 of the Enforcement Policy.
Failure to Correct a Condition Adverse to Quality Resulted in Premature Failures of
Regulating Transformers
Cornerstone
Significance
Cross-Cutting
Aspect
Report
Section
Mitigating
Systems
Green
NCV 05000424,05000425/2024004-02
Open/Closed
[P.3] -
Resolution
The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for the licensees failure to implement
timely corrective actions for a condition adverse to quality (CAQ) involving manufacturing
deficiencies of safety-related regulating transformers (RTs), leading to premature transformer
failures and fires.
Description: The inspectors reviewed equipment performance issues associated with the 480
to 120-volt RT (equipment identification number: 2BBA02RX) that experienced a small
internal fire due to a fault on August 13, 2024 (condition report (CR) 11101526, see
Section 71153 of NRC Inspection Report 05000424-425/2024003: ADAMS Accession
No. ML24296A052). The RT failure resulted in the inoperability of the unit 2 B trains of the
emergency safety features chiller and the control room environment filtration system because
the trains lost control power. This RT had been in service for approximately 6 years.
The inspectors reviewed CRs, causal evaluations (CARs), and corrective actions (CA) taken
in response to the reduced service life experienced at Vogtle Units 1 and 2 for AMETEK SCI
RTs. Units 1 and 2 have approximately 50 of these RTs (7.5 / 15 / 30kVa) in both safety and
non-safety-related applications and have a service life of 20 years. The licensee has
experienced a much lower service life due to failures caused by winding shorts to ground,
typically via the transformer core, which have resulted in small plant fires and inoperability of
supported equipment. The inspectors determined that the licensee failed to take prompt CAs
to address premature failures of these RTs after identifying that the failures were associated
with vendor quality/manufacturing issues. Specifically, apparent cause evaluations in 2008,
2015, 2016, 2017, and 2023, identified that manufacturing deficiencies were causing the RTs
to operate at elevated temperatures, ultimately resulting in premature failure (i.e. short-
circuit).
In May 2008, the licensee documented in CAR 177330 that a manufacturing deficiency
(confirmed via failure analysis) that caused the failure (charred windings) of unit 1 safety-
related RT 1BBC42RX (13 yrs old) could affect all regulated transformers. Up until 2008, the
licensee had replaced 40 % of these types of RTs due to various reasons, including actual
failures, elevated noise, visible degradation, etc. The licensee initiated a long-term CA
(LTCA), tracked via corrective action program (CAP) technical evaluation (TE) 12937, to
replace all RTs with a more robust design. In the meantime, the vendor recommended that
noise levels and temperatures could be monitored and trended for signs of transformer
degradation and/or imminent failure. Therefore, the licensee initiated CAs to conduct routine
RT inspections (at or less than 12-month frequency), while in-service. The inspections were
limited to what could be observed via the vent on the RTs front panel and therefore, were
considered partly effective and an interim CA until a design change was implemented.
Four (4) additional premature RT failures occurred in 2011 (CR 355048), 2015 (CAR
261531), 2016 (CAR 262006), and 2017 (CAR 270452). The consolidated CAs from these
failures resulted in a licensee decision to cancel the 2008 LTCA to replace the RTs with a
more robust design (TE12937). Instead, RTs would be replaced at a shorter 12 to 18 year
frequency (depending on transformer importance) and as-needed, based on the routine
inspections established in 2008. However, in 2019, the licensee canceled both the
replacement and inspection preventive maintenance (PMs) activities without taking any
actions to ensure that the RTs operating experience and performance gaps were resolved.
In January 2023, a RT failed due to an internal fault and resulted in a small fire (2ABF13RX -
6.5 yrs old). The licensee identified the inappropriate cancellation of the replacement and
inspection PMs. The licensee reinstated and improved the routine inspections (now using
thermography with RT front panel removed) and created a new CA, similar to the CA in 2008,
to implement a design change (tracked by CAP TE1121583). The inspectors noted the
licensee did not schedule the inspections until August 2024, approximately 19 months after
the 2023 RT failure. The inspectors determined the implementation of this CA was not timely
considering that (1) no inspections had been conducted since the PM was canceled in 2019
and (2) given the RTs operating experience and importance of the routine inspections in
identifying premature failure. With respect to RT 2BBA02RX, which failed in August 2024, the
licensee identified the RT had elevated noise levels (CR10939767 - 1/15/2023) during extent
of condition walkdowns conducted immediately after the 2023 failure of 2ABF13RX, however,
no thermography inspections were conducted for 2BBA02RX before it failed. Additionally, in
May 2024, another RT (2ABB40RX) failed due to an internal fault, resulting in a small fire
(CRs 11079551 and 11079547). The RT was replaced but the licensee did not re-evaluate or
move up the routine inspections CA scheduled for August 2024. Following the failure of RT
2BBA02RX in August 2024, the licensee conducted the routine inspections and identified
several RTs operating loudly and/or at high temperatures, and took actions to either replace
the RT, de-energize it, or install supplemental cooling. While the timeliness of the inspections
following the August 2024 failure were prompt, in general, the licensee did not inspect RT
ANBU08RX, located in the equipment building of unit 1, because it incorrectly assumed that
the RT was normally de-energized. That transformer experienced a small fire due to internal
fault in November 2024 (CR 12345678).
Lastly, the inspectors determined that the routine in-service inspections conducted up until
2019, when the PM was canceled, were not effective, as evident by the 2015-17 failures,
because the data collected was not maintained as a quality record and could not be retrieved
to monitor, trend, and effectively identify signs of degraded performance. Also, the PM
instructions did not include objective criteria to determine when the RTs required immediate
replacement or increased monitoring. Also, the inspectors determined that the 2023 CA
(TE1121583) to implement a design change was not being tracked to completion in the
corrective action program (CAP). The CA TE was closed in April 2023, following the approval
of Long-Term Action Management (LTAM) V-23-0009 to replace the RTs. LTAMs are non-
CAP tracking actions that are addressed at a lower priority using processes outside the CAP
and, per licensee CAP procedure, cannot be used to close CAP TEs.
Corrective Actions: On August 14, 2024, the licensee replaced the 2BBA02RX transformer
(work order SNC1969566) and conducted extent of condition inspections of other RTs
resulting in closer monitoring, de-energizing, and replacement of additional RTs. It also
initiated an LTCA to replace the RTs with a different design (TEs 1164291 and 1164293) and
another CA to replace RTs at an increased frequency until implementation of the LTCA (TEs
1164292 and 1164294). Following the November 2024 RT failure, the licensee verified all
energized transformers were being monitored and began conducting weekly RT inspections.
Corrective Action References: CAR 743161
Performance Assessment:
Performance Deficiency: The failure to implement timely corrective actions for a condition
adverse to quality involving the reduced service life and in-service failures of safety-related
transformers was a performance deficiency.
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, failure to implement timely CAs led to additional RT
failures resulting in inoperability of supported safety-related equipment. The performance
deficiency was also associated with the Protection Against External Factors 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 because the resulting fire(s) represents an external
event initiator.
Significance: The inspectors assessed the significance of the finding using IMC 0609
Appendix AProperty "Inspection Manual Chapter" (as page type) with input value "NRC Inspection Manual 0609</br></br>Appendix A" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process., The Significance Determination Process (SDP) for Findings At-Power. The
inspectors screened the finding as having very low safety significance (i.e., Green) because,
for Exhibit 2 (Mitigating Systems), the finding did not represent a condition requiring a
detailed risk evaluation (i.e., all mitigating systems questions were answered No) and for
Exhibit 1 (Initiating Events), the finding did not impact the frequency of a fire initiating event.
Specifically, the small size of the transformers (i.e., below 45 KVA) are not expected to
produce challenging (i.e., potentially risk significant) fires based on current technical guidance
(NUREG-6850, Fire Probabilistic Risk Assessment Methods Enhancements).
Cross-Cutting Aspect: P.3 - Resolution: The organization takes effective corrective actions to
address issues in a timely manner commensurate with their safety significance. Specifically,
the licensee failed to implement effective CA plans since initially identifying the unreliability of
these transformers in 2008, and after subsequent failures in 2011, 2015, 2016, 2017, 2023,
and 2024.
Enforcement:
Violation: Title 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, requires, in
part, that measures shall be established to assure that conditions adverse to quality, such as
failures, malfunctions, deficiencies, deviations, defective material and equipment, and
nonconformances are promptly identified and corrected.
Contrary to the above, after identifying, as early as May 2008, that RTs were prematurely
failing due to, most likely, manufacturing quality issues, the licensee failed to assure that
corrective action plans were promptly implemented to identify and correct additional
transformers susceptible to premature failure.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with
Section 2.3.2 of the Enforcement Policy.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
On January 16, 2025, the inspectors presented the integrated inspection results to J.
Weissinger, Site Vice President, and other members of the licensee staff.