ML25113A269
| ML25113A269 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 04/24/2025 |
| From: | Robert Williams NRC/RGN-II/DORS |
| To: | Flippin N Duke Energy Carolinas |
| References | |
| IR 2025040 | |
| Download: ML25113A269 (1) | |
Text
Nicole Flippin Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745-9635
SUBJECT:
CATAWBA NUCLEAR STATION - 95001 SUPPLEMENTAL INSPECTION SUPPLEMENTAL REPORT 05000414/2025040 AND FOLLOW-UP ASSESSMENT LETTER
Dear Nicole Flippin:
On March 13, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed a supplemental inspection using Inspection Procedure 95001, "Supplemental Inspection Response to Action Matrix Column 2 (Regulatory Response) Inputs, and discussed the results of this inspection and the implementation of your corrective actions with you and other members of your staff.
The NRC performed this inspection to review your stations actions in response to a White finding in the Mitigating Systems cornerstone which was documented and finalized in NRC Inspection Report 2024091. On February 21, 2025, you informed the NRC that your station was ready for the supplemental inspection.
The NRC determined that your staffs evaluation identified the cause of the White finding.
Specifically, the root cause of the licensees failure to implement measures to maintain functionality of the 2A diesel building ventilation system (VD) was: 1) the licensee failed to recognize that the alternate method to operate VD was not described in the Updated Final Safety Analysis Report (UFSAR), and 2) less than adequate actions were taken to ensure UFSAR defined testing was incorporated into VD surveillance test procedures.
The inspectors determined that the root cause evaluation was documented at a sufficient level of detail, included relevant operating experience, and identified the root causes, extents of condition, and extents of cause of the performance issue. Based on the results of the inspection, the inspectors concluded the objectives of the inspection procedure (IP) were met.
The NRC determined that completed or planned corrective actions were sufficient to address the performance issue that led to the White finding. Therefore, the finding is considered closed and will no longer be considered an Action Matrix item as of March 13, 2025. Based on the results of this inspection and our Action Matrix assessment, the NRC has determined that Catawba Nuclear Station Unit 2 transitioned to the Licensee Response Column (Column 1), as of March 13, 2025.
No findings or violations of more than minor significance were identified during this inspection.
April 24, 2025
N. Flippin 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, Robert E. Williams, Jr., Chief Projects Branch 1 Division of Operating Reactor Safety Docket No. 05000414 License No. NPF-52
Enclosure:
As stated cc w/ encl: Distribution via LISTSERV Signed by Williams, Robert on 04/24/25
SUNSI Review x
Non-Sensitive
Sensitive x
Publicly Available
Non-Publicly Available OFFICE RII/DORS RII/DORS RII/DORS NAME F. Young J. Seat R. Williams DATE 04/24/2025 04/24/2025 04/24/2025
Enclosure U.S. NUCLEAR REGULATORY COMMISSION Inspection Report Docket Number:
05000414 License Number:
NPF-52 Report Number:
05000414/2025040 Enterprise Identifier:
I-2025-040-0004 Licensee:
Duke Energy Carolinas, LLC Facility:
Catawba Nuclear Station Location:
York, South Carolina Inspection Dates:
March 10, 2025 to March 13, 2025 Inspectors:
J. Seat, Senior Project Engineer F. Young, Resident Inspector Approved By:
Robert E. Williams, Jr., Chief Projects Branch 1 Division of Operating Reactor Safety
2
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a 95001 supplemental inspection at Catawba Nuclear 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 No findings or violations of more than minor significance were identified.
Additional Tracking Items Type Issue Number Title Report Section Status LER 05000414,05000413/20 24-001-00 LER 2024-001-00 for Catawba Nuclear Station, Units 1 and 2, Condition Prohibited by Technical Specifications and Loss of Safety Function due to Failed Damper Controller for the 2A1 Emergency Diesel Generator Room Ventilation Fan 71153 Closed NOV 05000414/2024001-01 Failure to Implement Measures to Maintain Functionality of the 2A Diesel Building Emergency Ventilation System EAF-RII-2024-0049 95001 Closed
3 INSPECTION SCOPES Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
OTHER ACTIVITIES - TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL 71153 - Follow Up of Events and Notices of Enforcement Discretion Follow Up of Events and Notices of Enforcement Discretion (1 Sample)
(1)
The inspectors evaluated the following licensee event report (LER):
LER 2024-001-00 for Catawba Nuclear Station, Units 1 and 2, Condition Prohibited by Technical Specifications and Loss of Safety Function due to Failed Damper Controller for the 2A1 Emergency Diesel Generator Room Ventilation Fan (ADAMS Accession Number: ML24064A190). The circumstances surrounding this LER were documented in inspection report 05000414/2024090 (Accession Number ML24166A010). This LER is closed.
95001 - Supplemental Inspection Response to Action Matrix Column 2 (Regulatory Response)
Inputs The inspectors reviewed and selectively challenged aspects of the licensees problem identification, causal analysis, and corrective actions in response to a White finding and associated Notice of Violation (NOV) of 10 CFR Part 50, Appendix B, Criterion III, "Design Control," for the licensee's failure to establish measures to assure that diesel building ventilation (VD) system design bases were translated into applicable licensing basis documents, as documented in NRC inspection reports 05000414/2024001 (ADAMS Accession Number:
ML24129A196) and 05000414/2024090 (Accession Number: ML24166A010). The NRC's final significance determination was communicated in NRC inspection report 05000414/2024091 (Accession Number: ML24234A291).
Objective: Ensure that the root and contributing causes of individual and collective White performance issues are understood.
Under this objective, the inspectors reviewed the root cause evaluation (RCE) the licensee conducted for the failure to establish measures to assure the design basis for the VD system was correctly translated into procedures and instructions (Aspect 1); and failure to apply design control measures for delineating acceptance criteria for VD system testing to ensure it remained functional (Aspect 2). Their review consisted of an evaluation of the following: the licensee's identification of the issues, when and how long the issues existed, prior opportunities for identification, documentation of significant plant-specific consequences and compliance concerns, use of a systematic methodology to identify
4 causes with a sufficient level of supporting detail, consideration of prior occurrences, identification of extent-of-condition (EOCo) and extent-of-cause (EOCa), and identification of any potential programmatic weaknesses in performance.
NRC Assessment: The team concluded that this objective was met. The licensee's RCE identified two root causes (RCs). The licensee determined that Catawba failed to recognize that the alternate method to operate VD, as described in the design basis document (i.e.
operation with only one of two trains of VD available given specific ambient outdoor temperatures), was not described in the Updated Final Safety Analysis Report (UFSAR)
(RC1); and during creation of operational phase emergency diesel generator (EDG) surveillance test procedures, less than adequate actions were taken to ensure UFSAR defined testing was incorporated (RC2). Additionally, the licensee identified the following six contributing causes (CCs): inadequate implementation of Technical Specification (TS)
Interpretation Manual review during the EOCo for nuclear condition report (NCR) 02275149
- 1B CA motor driven pump pit sump pump failure incorrect operability determination (OD)
(CC1); review of Waterford operating experience (OE) (NRC Letter EA-13-233) was too narrowly scoped and not informed by a review of the UFSAR (CC2); inappropriate acceptance of reduced design margin for an EDG support system led to one of two EDG ventilation fans being unavailable for an extended period (CC3); inappropriate response to abnormal room conditions allowed a failed VD controller to remain undetected following EDG surveillance testing (CC4); prior actions regarding design basis documents (DBDs) as the sole input into OD were not durable (CC5); and Love 54 commercial grade dedication (CGD) plan did not include circuit board workmanship inspection (CC6).
a.
Identification: The RCE stated that the NRC identified the failure to implement measures to maintain the functionality of the VD system, as described in the UFSAR, in NRC Inspection Report 05000414/2024090.
b.
Exposure Time: The RCE determined that the failure to ensure measures (design basis documents, calculations, procedures, etc.) to demonstrate functionality of EDG systems with only one train of VD available, as described in the UFSAR, existed since at least 1986. Specifically, though the UFSAR did not support operability of an EDG with only one train of VD available, regardless of outside temperature, calculation CNC 1211.00-00-0013 (Diesel Generator Building Calculations), revision 6, contained a calculation for the maximum outside ambient temperature, for which one train of VD could still support EDG operability, was approved in 1986.
c.
Identification Opportunities: In general, the licensee appropriately identified prior occurrences and identification opportunities. The licensee determined that opportunities existed to identify the issue during the transition to Improved Technical Specifications, during the EOCo for NCR 02275149 - 1B CA Motor Driven Pump Pit Sump Pump Failure Incorrect Operability Determination, and during review of Waterford Operating Experience (NRC Letter EA-13-233).
d.
Risk and Compliance: The inspectors determined the licensee appropriately understood the risk and compliance implications of the White finding. The RCE identified that the failure to implement measures to ensure functionality of the VD system consistent with UFSAR requirements, resulted in loss of regulatory margin; and failure to apply design control measures for delineating acceptance criteria for VD system testing to ensure it remained functional, could allow equipment malfunctions to remain un-diagnosed and
5 further challenge the ability to satisfactorily perform its specified safety function.
e.
Methodology: The inspectors determined the RCE employed a systematic evidence-based methodology to determine the root and contributing causes of the White finding.
The methodology included the Why Staircase, Event and Causal Factor Chart, and Organizational & Programmatic Evaluation Matrix.
f.
Level of Detail: The inspectors determined the RCE was performed commensurate with the safety significance and complexity of the performance issue and was sufficiently detailed to identify the root and contributing causes, extent of conditions, and extent of causes. The RCE team utilized a formal cause analysis process to identify the problems and determine corrective actions.
g.
Operating Experience: The inspectors determined that the licensee appropriately considered prior occurrences and operating experience during the RCE. The RCE reviewed similar events that occurred in the nuclear industry, as well as some internal events and determined that this was not a repeat event, nor was it preventable by reviewing operating experience.
h.
Extent of Condition and Cause: The inspectors determined that the licensee's evaluation identified the EOCo and EOCa of the performance issues. To evaluate the EOCo of the issues, the root cause team applied the Same-Similar evaluation technique. The inspectors reviewed the safety culture traits in NUREG-2165, Safety Culture Common Language, referenced in IMC 0310-06, to determine if these were appropriately considered during the licensees evaluations of the root causes, extents of condition, and extents of cause.
Objective: Ensure that the extent-of-condition and extent-of-cause of individual and collective White performance issues are identified.
Under this objective, the inspectors independently reviewed the licensee's EOCa evaluation and Same-Similar review in the licensee's EOCo evaluation, to assess the licensee's extent-of-condition and extent-of-cause review efforts.
NRC Assessment: The team concluded that this objective was met. The inspectors review determined the licensees evaluations were documented at a sufficient level of detail, included relevant operating experience, and identified the root causes, contributing causes, extents of condition, and extents of cause of the performance issue. Additionally, the inspectors determined the licensees causal evaluations appropriately considered the safety culture aspects related to the risk significant performance issue.
a.
Extents of Condition and Cause: The licensee used the Same-Similar technique to evaluate the EOCo. All Maintenance Rule (MR) high safety significant (HSS) systems not associated directly with Technical Specification Surveillance Requirements (TS SRs) were included, to determine if the licensing basis information contained in the UFSAR was aligned with plant procedures, processes, and other documentation used to configure, control, and test those system. MR HSS systems with direct association with TS SRs were excluded, because established surveillance tests are aligned with the UFSAR, since TSs are part of the operating license. Additionally, reviews were performed for the other engineered safety feature (ESF) ventilation systems and other EDG support systems. The licensee took credit for a previous EOCa evaluation
6 performed in NCR 02275149, because it involved a similar performance gap.
b.
Extent of Condition: For Aspect 1, the licensee's Same/Same review did not identify any additional instances where design basis information for the VD system was previously not translated into applicable procedures. The Same/Similar review identified one gap associated UFSAR section 9.4.4.2, as it related to normal ventilation fan dampers, which had been modified per Minor Modification CNCE-61116 and CNCE-61115, as discussed in the VD DBD (CNS-1579.VD-00-0001). The licensee initiated EOC-AS2 to update the UFSAR. The Similar/Same review did not identify any condition where the design basis information in the UFSAR was not translated into appropriate procedures. The Similar/Similar review identified one gap associated with NF (Ice Condenser Refrigeration). There was a mismatch between UFSAR section 6.7.6, TS 3.6.12, and the DBD, related to the minimum total weight of ice columns. The licensee initiated EOC-AS3 to reconcile the design documents.
For Aspect 2, the licensee's Same Object/Same Defect review identified that the monthly EDG performance tests contained a gap in their ability to validate outside air damper performance, because they could not be seen with the return air dampers closed in once-through ventilation mode. RC2-AS1 was generated to resolve this issue. The Same Object/Similar Defect review identified no additional components in the VD system that were not adequately tested. The Similar Object/Same Defect identified no other HSS systems that did not have adequate steps in surveillance procedures to ensure essential electrical components are operating properly. The Similar Object/Similar Defect review did not identify any other MR HSS systems that did not have adequate steps in surveillance procedure to ensure all components are operating properly.
The licensee also performed additional EOCo reviews of systems that were not part of the sample used with the Same-Similar review, and used insights gained from performance of additional EOCo reviews performed as part of the previously completed Flex Cause Evaluation (FCE).
c.
Extent of Cause: The licensee determined that both root causes were legacy performance issues associated with VD system operational allowances and testing. For RC1, the licensee determined that a similar performance gap was identified previously in NCR 02275149, and the EOCa performed in this NCR, adequately captured the EOCa for this issue. The licensee determined from that EOCa, that there were additional actions needed to review DBDs (EOCa-RC1-AS1), Operations Training Lesson Plans (EOCa-RC1-AS2), clearances (EOCa-RC1-AS3) and Operations procedures (EOCa-RC1-AS4) to validate that the guidance aligned with the UFSAR. RC2 determined that the VD testing inconsistencies have existed since the EDG testing was developed during plant commissioning. The site failed to recognize the gap between the UFSAR and implemented testing procedures. As with RC1, the licensee determined that the processes used to create the surveillance procedures prior to plant operation differed from current procedural development practices and guidance, and thus, reviewing other work activities from that timeframe was not warranted.
Objective: Ensure that completed corrective actions to address and preclude repetition of White performance issues are timely and effective.
Under this objective, the inspectors assessed the appropriateness and timeliness of the licensee's corrective actions.
7 NRC Assessment: The team concluded that this objective was met. The inspectors determined that these corrective actions were both timely and adequate to prevent recurrence.
a.
Completed Corrective Actions to Prevent Recurrence (CAPRs)
(1) RC1-AS1: "Revise AD-EG-ALL-1137, Engineering Change Product Selection, to indicate that Instruction 3 on Attachment 7 is a CAPR. Additionally, this instruction is to be revised to clearly state that this instruction applies to DBDs as well."
The inspectors determined that this CAPR was both appropriate and timely in addressing aspects of RC1, "failure to recognize that the alternate method to operate VD as described in the DBD was not described in the UFSAR," because the procedural changes had already been implemented. The licensee's effectiveness review plan for RC1 (RC1-EREV1) incorporates appropriate qualitative measures of success for this CAPR.
(2) RC1-AS2: "Revise AD-LS-ALL-0007, Applicability Determination Process, step 5.5 (UFSAR Review) to state that new methods of operating equipment that perform a design function should be considered for inclusion in the UFSAR. Specifically, when a significantly new system alignment is proposed, or reduction in the amount of margin or redundancy credited, then an UFSAR change should be pursued prior to implementing. Ensure CAPR commitment is flagged."
The inspectors determined that this CAPR was both appropriate and timely in addressing aspects of RC1, because the procedural changes had already been implemented. The licensee's effectiveness review plan for RC1 incorporates appropriate qualitative measures of success for this CAPR.
(3) RC1-AS3: Summary: Revise VD System Licensing Basis Documents (UFSAR) to discuss suitability of the VD system meeting its design requirements with the current alternate fan strategy, providing an accurate description of VD fan capacity requirements, including discussion of the outside temperature requirements, needed to maintain EDG room temperature.
The inspectors determined that this CAPR was both appropriate and timely in addressing aspects of RC1, because the documentation changes had already been implemented. The licensee's effectiveness review plan for RC1 incorporates appropriate qualitative measures of success for this CAPR.
(4) RC1-AS4: "Revise OP/1(2)/A/6350/002 - Add Enclosure for control of VD System alignments in accordance with UFSAR revision made in RC1-AS2. Note that the enclosure for removal and return to service of a VD fan was previously created as documented in action request (AR) 02499589-37. This assignment is to ensure the enclosure is identified as a CAPR for this root cause evaluation."
The inspectors determined that this CAPR was both appropriate and timely in addressing aspects of RC1, because the procedural changes had already been implemented. The licensee's effectiveness review plan for RC1 incorporates appropriate qualitative measures of success for this CAPR.
8 (5) RC2-AS2: "Install cameras to provide visual indication of outside air damper performance. Additionally, flag all emergency ventilation functional verification steps in the associated EDG PTs as CAPRs. (PT/1/A/4350/002A, PT/1/A/4350/002B, PT/2/A/4350/002A, and PT/2/A/4350/002B)"
The inspectors determined that this CAPR was both appropriate and timely in addressing aspects of RC2, "during creation of operational phase Emergency Diesel Generator surveillance test procedures, less than adequate actions were taken to ensure UFSAR defined testing was incorporated," because the cameras had already been installed and were being monitored. The licensee's effectiveness review plan for RC2 (RC2-EREV2:) incorporates appropriate qualitative measures of success for this CAPR.
b.
Other Completed Corrective Actions (CORRs)
(1) In addition to the CAPRs, the licensee implemented the following CORR to address RC1:
i.
RC1-AS5: "Update and deliver Current Licensing Basis (CLB) training to include this Root Cause as OE and use it as a case study. Emphasize the importance of maintaining alignment between the UFSAR and other licensing/non-licensing documents, especially DBDs. The goal of the training is to present valuable operating experience and reinforce a culture of literal compliance with the licensing basis as well as the importance of maintaining alignment between the licensing basis, plant operation and other documents. Reinforce literal reading of the UFSAR. Training population will include accredited Engineering personnel."
The inspectors determined that this CORR was both appropriate and timely in addressing aspects of RC1, because the training was updated and had already been performed.
(2) In addition to the CAPRs, the licensee implemented the following CORRs to address RC2:
i.
RC2-AS3: "Revise EDG Room Temperature OAC Alarm Response from 110F to 105F to allow for detection of degraded VD system performance during EDG operation."
ii.
RC2-AS4: "Develop and implement a method to measure VD Fan air flow rate to monitor long term health of the fans."
iii.
RC2-AS5: "Implement a change to Operator Rounds to perform periodic monitoring of emergency VD damper controller indications. (This assignment is to capture objective evidence of rounds changes which had previously occurred)"
The inspectors determined that these CORRs were both appropriate and timely in addressing aspects of RC2, because the procedural changes were already implemented.
(3) In addition, the licensee implemented the following CORRs to address contributing causes:
i.
CC5-AS1: "Revise AD-OP-ALL-0200, Clearance and Tagging, to state that non-Current License Basis documents are validated against CLB documents when
9 providing any instructions or guidance in a clearance regarding potential equipment operability."
ii.
CC5-AS2: "Revise OMP 2-29, LCO Tracking, to state that non-Current License Basis documents are validated against CLB documents when performing any activity involving Operability Determinations."
iii.
CC5-AS3: "Revise AD-OP-ALL-0105, Operability Determination, to state that non-Current License Basis documents are validated against CLB documents when performing any activity involving Operability Determinations."
iv.
CC5-AS4: "Revise AD-TQ-ALL-0101, Conduct of the Systematic Approach to Training, to state that if training material provides instruction or guidance on equipment operability, it must be accompanied by a reference to current license basis documents, not DBDs."
v.
CC5-AS5: "Review NRC Violation and Root/Contributing Causes with station leadership and other key stakeholders (i.e. personnel whose job function requires referencing the CLB such as Licensed operators, Operations Training Instructors, Procedure Writers) emphasizing literal compliance with the UFSAR and other licensing documents to help establish the correct cultural mindset regarding literal compliance."
vi.
CC5-AS6: "Conduct Teaching and Learning sessions with Operations Training instructors and Licensed Operators that all operability determinations, including supporting guidance in lessons plans and clearances, are to be supported via current license basis documents (i.e., UFSAR). If they come across an item which cannot be supported by the CLB, then stop and expand the team. That a DBD alone is NOT to be used to make operability determinations. Ensure these discussions focus on literal compliance with the UFSAR."
vii.
CC6-AS1: "Update receipt inspection requirements or commercial grade dedication plan to require detailed inspection of all wire terminations and solder joints to ensure workmanship/quality is in good condition. Also, consider any additional inspections that could improve the dedication process for this piece part such as a 3rd party vendor testing or dedication."
The inspectors determined that these CORRs were both appropriate and timely in addressing aspects of the CCs, because the procedural changes, reviews, and training were already implemented.
Objective: Ensure that pending corrective action plans direct prompt and effective actions to address and preclude repetition of White performance issues.
Under this objective, the inspectors assessed the appropriateness and timeliness of the licensee's planned corrective actions.
NRC Assessment: The team concluded that this objective was met.
a.
Planned Corrective Actions to Prevent Recurrence (1) RC2-AS1: Install positive indication on the outside air dampers and add criteria for damper monitoring to surveillance procedures PT/1(2)/A/4350/002 A(B).
The inspectors determined that this CAPR was both appropriate and timely in addressing aspects of RC2, because the change had a reasonable implementation date. The inspectors do not plan any additional follow-up of this CAPR outside of the
10 baseline inspection program. The licensee's use of cameras to monitor air damper performance, as currently implemented, is adequate to address RC2.
Conclusion The inspectors concluded the corrective actions to preclude repetition of the root and contributing causes (causal factors) of the White performance issue were effective and adequately prioritized considering safety significance and regulatory compliance. In addition, the inspectors determined that evaluations were documented at a sufficient level of detail, included relevant operating experience, and identified the root causes, extent of conditions, and extent of causes of the performance issue. Based on the results of the inspections, the inspectors concluded that the objectives of the inspection procedure were met and that the finding will be closed.
INSPECTION RESULTS No findings were identified.
EXIT MEETINGS AND DEBRIEFS The inspectors verified no proprietary information was retained or documented in this report.
On March 13, 2025, the inspectors presented the 95001 supplemental inspection results to Nicole Flippin and other members of the licensee staff.
11 DOCUMENTS REVIEWED Inspection Procedure Type Designation Description or Title Revision or Date Corrective Action Documents NCR 2516761, 2499589 Corrective Action Documents Resulting from Inspection NCR 2546871 AD-EG-ALL-1137 Engineering Change Product Selection, Rev 13 AD-EG-ALL-1202 Preventive Maintenance and Surveillance Testing and Administration Rev 13 AD-EG-ALL-1206 Equipment Reliability Classification Rev 7 AD-LS-ALL-0007 Applicability Determination Process Rev 12 AD-OP-ALL-0105 Operability Determinations Rev 9 AD-TQ-ALL-0101 Conduct of the Systematic Approach to Training Rev 17 95001 Procedures AD-WC-ALL-0200 Online Work Management Rev 23