IR 05000348/2023002
| ML23220A208 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 08/10/2023 |
| From: | Alan Blamey Division Reactor Projects II |
| To: | Brown R Southern Nuclear Operating Co |
| References | |
| EA?23?080 IR 2023002 | |
| Download: ML23220A208 (1) | |
Text
August 10, 2023
SUBJECT:
JOSEPH M. FARLEY NUCLEAR PLANT-INTEGRATED INSPECTION REPORT 05000348/2023002 AND 05000364/2023002 AND APPARENT VIOLATION
Dear R. Keith Brown:
On June 30, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Joseph M. Farley Nuclear Plant. On August 2, 2023, the NRC inspectors discussed the results of this inspection with Mr. Dan Williams, Site Regulatory Affairs Manager, and other members of your staff. The results of this inspection are documented in the enclosed report.
Section 71152A of the enclosed report discusses a finding with an associated apparent violation for which the NRC has not yet reached a preliminary significance determination. This involved a self-revealed apparent violation of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion XVI, associated with the failure to identify and correct a condition adverse to quality associated with the installation instructions of a lube oil coupling assembly for the unit 1 B emergency diesel generator and resulting inoperability of the diesel.
We intend to issue our final safety significance determination and enforcement decision, in writing, within 90 days from the date of this letter. The NRCs significance determination process (SDP) is designed to encourage an open dialogue between your staff and the NRC; however, neither the dialogue nor the written information you provide should affect the timeliness of our final determination. We ask that you promptly provide any relevant information that you would like us to consider in making our determination. We are currently evaluating the significance of this finding and will notify you in a separate correspondence once we have completed our preliminary significance review. You will be given an additional opportunity to provide additional information prior to our final significance determination unless our review concludes that the finding has very low safety significance (i.e., Green).
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 Joseph M. Farley Nuclear Plant. 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 10 CFR 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely, Signed by Blamey, Alan on 08/10/23 Alan J. Blamey, Chief Reactor Projects Branch #2 Division of Reactor Projects Docket Nos. 05000348 and 05000364 License Nos. NPF2 and NPF8
Enclosure:
As stated
Inspection Report
Docket Numbers: 05000348 and 05000364 License Numbers: NPF-2 and NPF-8 Report Numbers: 05000348/2023002 and 05000364/2023002 Enterprise Identifier: I2023002-0015 Licensee: Southern Nuclear Operating Company, Inc.
Facility: Joseph M. Farley Nuclear Plant Location: Columbia, AL Inspection Dates: April 01, 2023, to July 01, 2023 Inspectors: A. Alen, Senior Project Engineer P. Gresh, Emergency Preparedness Inspector K. Kirchbaum, Senior Operations Engineer P. Meier, Senior Resident Inspector C. Scott, Senior Project Engineer S. Temple, Resident Inspector J. Walker, Sr Emergency Preparedness Inspector Approved By: Alan J. Blamey, Chief Reactor Projects Branch 2 Division of Reactor Projects Enclosure
SUMMARY The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Joseph M. Farley Nuclear Plant, 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 Emergency Diesel Generator Lube Oil Coupling Leak Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Pending [H.13] - 71152A Systems AV 05000348/202300201 Consistent Open Process EA23080 A self-revealed finding with its safety significance as yet to be determined (TBD) and an associated apparent violation (AV) of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, was identified for the licensees failure to identify nonconforming work instructions for installation of an emergency diesel generator (EDG) lube oil coupling following a unit 1 B EDG coupling assembly failure in November 2022. Specifically, the licensee failed to adhere to the troubleshooting standards when it did not evaluate available evidence surrounding the coupling assembly failure. This resulted in another coupling assembly failure and lube oil leak during a surveillance run on February 26, 2023, rendering the 1B EDG inoperable.
Additional Tracking Items Type Issue Number Title Report Section Status LER 05000348/2023001-00 LER 2023001-00 for Joseph 71153 Closed M. Farley Nuclear Plant, Unit 1, Automatic Reactor Trip due to DC Ground on Turbine Trip Solenoid
PLANT STATUS Unit 1 began the report period at approximately 100 percent rated thermal power (RTP) and remained at or near 100 percent RTP through the end of the report period.
Unit 2 began the inspection period at approximately 100 percent RTP. On April 10, 2023, the unit was powered down to approximately 88 percent RTP for turbine valve testing. On April 11, 2023, the unit was returned to approximately 100 percent RTP following the turbine valve testing. On June 2, 2023, an unplanned power reduction to approximately 68 percent RTP was performed due to bus duct cooling issues. Following restoration of bus duct cooling, the unit was restored to approximately 100 percent RTP on June 3, 2023. On June 13, 2023, the licensee performed a planned shutdown of the unit to replace a leaking pressurizer safety valve. On June 14, 2023, the unit entered Mode 5 and on June 19, 2023, the unit was restarted and reached approximately 100 percent RTP on June 23, 2023. Unit 2 remained at approximately 100 percent RTP through the end of the report 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 onsite 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 for seasonal extreme weather conditions prior to the onset of seasonal hot temperature for the following systems during the month of May 2023:
Service water system Isophase bus cooling Cooling towers River water intake 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 thunderstorms and ensure the ability of personnel to respond to an emergency on June 14, 2023 (procedure FNP0AOP21.0).
71111.04 - Equipment Alignment Partial Walkdown Sample (IP Section 03.01) (3 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
(1) Unit 2 auxiliary building vital direct-current (DC) battery charger alignment with the
'2B' battery charger unavailable on April 11, 2023, (dwgs. D207083, D207082)
(2) Unit 2 B train high head safety injection system with the swing pump aligned to the B train during the C pump maintenance outage on April 25, 2023, (D205038, D205039)
(3) Emergency diesel generator 2C while the 12A emergency diesel generator is out of service for a planned maintenance outage during the week of May 7, 2023, (procedure FNP0SOP38.0 and dwg. A181005)
71111.05 - Fire Protection Fire Area Walkdown and Inspection Sample (IP Section 03.01) (6 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) Service water intake structure pump room (FA 72) during the week of April 17, 2023 (procedure FNP0FPP3.0)
(2) Service water intake structure 'B' train switchgear room (FA 75) during the week of April 17, 2023 (FNP0FPP3.0)
(3) Emergency diesel generator '2B' room (FA 59) on May 30, 2023 (FNP0FPP2.0)
(4) Emergency diesel generator '12A' room (FA 61) on June 27, 2023 (FNP0FPP2.0)
(5) Unit 1 'B' DC switchgear room (FA 1019) on June 27, 2023 (FNP1FPP1.0)
(6) Unit 1 and 2 main control room (FA 044) on June 27, 2023 (FNP1FPP1.0)
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 for the following activities:
Unit 2 main turbine valve testing on April 10, 2023 Unit 2 operator testing of the 'B' motor-driven auxiliary feedwater pump utilizing the hot shutdown panel May 2, 2023 (procedure FNP2STP73.1)
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (2 Samples)
(1) The inspectors observed licensed operator continuing training 'as-left exam' (233 AsFound Exam Scenario #1000) on May 1, 2023.
(2) The inspectors observed and evaluated operator training on the simulator for an emergency exercise with offsite participation involving a reactor trip and small break loss of coolant accident on May 16, 2023.
71111.12 - Maintenance Effectiveness Maintenance Effectiveness (IP Section 03.01) (2 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) Emergency diesel generator 1-2A maintenance outage that included a turbo charger replacement and circulating oil pump discharge line modifications during the week of May 8, 2023 (work orders (WO) SNC1462848; SNC785001)
(2) Extent of condition for all of the station's emergency diesel generators associated with the Flexmaster coupling leaks as a result of a major oil leak on the unit 1 'B'
emergency diesel generator on February 26, 2023, and a 1C emergency diesel generator oil leak identified on May 17, 2023, (condition report (CR) 10972464)
Quality Control (IP Section 03.02) (1 Sample)
The inspectors evaluated the effectiveness of maintenance and quality control activities to ensure the following SSC remains capable of performing its intended function:
(1) Safety-related components received, handled, stored, and issued for maintenance by the warehouse on April 5, 2023, (procedures SCM005, NMP-MA009)
71111.13 - Maintenance Risk Assessments and Emergent Work Control Risk Assessment and Management Sample (IP Section 03.01) (4 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 2 turbine-driven auxiliary feedwater system planned maintenance outage on April 3 and April 4, 2023 (procedure NMP-OS010)
(2) Unit 2 risk during planned maintenance on the 'B' charging pump and unit 1 S motor control center on April 11 and April 12, 2023 (3) Unit 1 planned maintenance on the 'B' residual heat removal pump with a planned
'yellow' risk condition on April 25, 2023 (NMP-OS010)
(4) Emergency diesel generator '12A' planned maintenance outage and associated risk for unit 1 and unit 2 during the week of May 7, 2023 (NMP-DP001)
71111.15 - Operability Determinations and Functionality Assessments Operability Determination or Functionality Assessment (IP Section 03.01) (5 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
(1) Emergency diesel generator 1-2A with scaffolding erected near the turbo charger on May 3, 2023 (procedure NMP-MA010)
(2) Unit 2 'B' battery charger multiple fault alarms identified on April 10, 2023, (CR 10963469)
(3) Unit 1 component cooling water leak identified on April 22, 2023, (CR 10966335)
(4) Emergency diesel generator 1C lube oil leak identified on May 17, 2023, (CR 10972464)
(5) Unit 1 'B' accumulator relief valve nitrogen leak identified on May 26, 2023, (CR 10974885)
71111.20 - Refueling and Other Outage Activities Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)
(1) The inspectors evaluated the unit 2 force outage for replacement of the 'A' pressurizer safety valve from June 13 to June 20, 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) (6 Samples)
(1) Unit 2 turbine-driven auxiliary feedwater valve testing from the hot shutdown panel following a planned pump maintenance outage on April 4, 2023 (procedure FNP2STP73.1)
(2) Unit 1 'S' motor control center (supplies various support loads for the 1-2A emergency diesel) planned maintenance outage for breaker testing and inspection during the week of April 10, 2023 (FNP0EMP1323.01)
(3) Unit 2 'B' charging pump testing following planned maintenance during the week of Aril 10, 2023 (WOs SNC788624; SNC1390807)
(4) Unit 2 'C' charging pump testing following balancing line repairs on April 27, 2023, (WO SNC1162964and FNP2STP4.3)
(5) Unit 1 'A' charging pump testing following inboard seal replacement on May 23, 2023, (WO SNC1448127, and FNP1STP4.1)
(6) Unit 2 'A' pressurizer safety valve testing following valve replacement on June 19, 2023, (WO SNC1348879 and FNP0MP-3.3)
Surveillance Testing (IP Section 03.01) (5 Samples)
(1) Emergency diesel generator '12A' 24-hour surveillance run on May 15, 2023, (FNP0STP80.6)
(2) Emergency diesel generator '1C' 1-hour surveillance run on May 17, 2023, (FNP0STP80.2)
(3) Emergency diesel generator '2B' fast-start test on May 26, 2023, (FNP2STP80.1)
(4) Unit 2 'B' component cooling water pump quarterly testing on June 12, 2023 (FNP-STP223.2)
(5) Unit 1 turbine-driven auxiliary feedwater pump steam supply valve testing on June 26, 2023, (FNP1STP21.3)
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
(1) Unit 2 'B' motor-driven auxiliary feedwater pump quarterly inservice testing on May 2, 2023 (FNP2STP22.2)
71114.02 - Alert and Notification System Testing Inspection Review (IP Section 02.0102.04) (1 Sample)
(1) The inspectors evaluated the maintenance and testing of the alert and notification system during the week of June 5, 2023.
71114.03 - Emergency Response Organization Staffing and Augmentation System Inspection Review (IP Section 02.0102.02) (1 Sample)
(1) The inspectors evaluated the readiness of the Emergency Response Organization during the week of June 5, 2023.
71114.04 - Emergency Action Level and Emergency Plan Changes Inspection Review (IP Section 02.0102.03) (1 Sample)
(1) The inspectors evaluated submitted emergency action level, emergency plan, and emergency plan implementing procedure changes during the week of June 5, 2023.
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 June 5, 2023.
71114.06 - Drill Evaluation Drill/Training Evolution Observation (IP Section 03.02) (1 Sample)
The inspectors evaluated:
(1) Licensed operator response during a simulator exam involving manual actuation of safety injection and a failed emergency diesel generator. This simulator exam represented a drill and exercise performance opportunity (233 As-Found Exam Scenario #1000) on May 1, 2023.
OTHER ACTIVITIES-BASELINE 71151 - Performance Indicator Verification
The inspectors verified licensee performance indicators submittals listed below:
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
(1) Unit 1 (April 1, 2022 - March 31, 2023)
(2) Unit 2 (April 1, 2022 - March 31, 2023)
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
(1) Unit 1 (April 1, 2022 - March 31, 2023)
(2) Unit 2 (April 1, 2022 - March 31, 2023)
EP01: Drill/Exercise Performance (DEP) Sample (IP Section 02.12) (1 Sample)
(1) January 1, 2022, through December 31, 2022.
EP02: Emergency Response Organization (ERO) Drill Participation (IP Section 02.13)
(1 Sample)
(1) January 1, 2022, through December 31, 2022.
EP03: Alert And Notification System (ANS) Reliability Sample (IP Section 02.14) (1 Sample)
(1) January 1, 2022, through December 31, 2022.
71152A - Annual Follow-up Problem Identification and Resolution Annual Follow-up of Selected Issues (Section 03.03) (1 Sample)
The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:
(1) Unit 1 'B' emergency diesel generator major oil leak identified on February 27, 2023, (CR 10951589)
71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02) (1 Sample)
(1) Emergency diesel generators oil leaks identified over the last five years (CRs 10920545, 10951589, 10557856)
71153 - Follow Up of Events and Notices of Enforcement Discretion Event Report (IP section 03.02) (1 Sample)
The inspectors evaluated the following licensee event reports (LERs):
(1) LER 05000348/2023001-00, "Automatic Reactor Trip due to DC Ground on Turbine Trip Solenoid" (ADAMS Accession No. ML23089A356). The inspectors determined
that it was not reasonable to foresee or correct the cause discussed in the LER; therefore, no performance deficiency was identified. The inspectors did not identify a violation of NRC requirements. The inspectors reviewed the circumstances regarding the trip in the first quarter of 2023 under the Farley baseline inspection report 2023001 (ADAMS Accession No. ML23122A168) as maintenance effectiveness (71111.12) sample 1 and plant modification (71111.18) sample 1.
INSPECTION RESULTS Emergency Diesel Generator Lube Oil Coupling Leak Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Pending [H.13] - 71152A Systems AV 05000348/202300201 Consistent Open Process EA23080 A self-revealed finding with its safety significance as yet to be determined (TBD) and an associated apparent violation (AV) of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, was identified for the licensees failure to identify nonconforming work instructions for installation of an emergency diesel generator (EDG) lube oil coupling following a unit 1 B EDG coupling assembly failure in November 2022. Specifically, the licensee failed to adhere to the troubleshooting standards when it did not evaluate available evidence surrounding the coupling assembly failure. This resulted in another coupling assembly failure and lube oil leak during a surveillance run on February 26, 2023, rendering the 1B EDG inoperable.
Description: While unit 1 was operating (Mode 1) on February 26, 2023, an oil leak of approximately 22 to 50 gallons per minute (gpm) occurred on the 1B EDG oil circulating pump discharge pipe coupling during a technical specification (TS) one hour surveillance run.
This rendered the 1B EDG inoperable based on the rate of the oil leak. The 1B EDG was restored to an operable status on March 3, 2023, following repairs and a modification to mitigate future failures.
A similar failure at the same location on the 1B EDG occurred while unit 1 was shutdown (Mode 5) on November 4, 2022, following a planned coupling replacement. The event was less significant because the 1B EDG was not required to be operable in Mode 5 and the oil leak was identified during a maintenance run before crediting the EDG for operability.
However, the approximate leak rate and failure mode were the same as the February 26, 2023, event.
The oil circulating pump discharge coupling is designed to absorb a certain amount of vibration and accommodate some misalignment between the two adjoining pipes. However, the vendor instructions provide limits on torquing, allowable misalignment, and minimum pipe insertion depth. When the coupling is installed in accordance with the vendor instructions, the coupling is rated for 200 psig with sufficient external restraints to account for end loads developed by internal pressure. The coupling sees head pressure developed by the circulating oil pump because it is located at the discharge side. The pump is normally running, whether the EDG is on or off, to provide constant oil filtration and keep the engine internals warm while the EDG is in the standby condition. When the EDG is off, the circulating oil is at approximately 25 psig. When the EDG is running, the oil pressure increases to approximately 114 psig due to the engine driven main oil pump. When the EDG was at normal operating speed and oil pressures, the vertical pipe run at the discharge of the coupling was pulled out
of the top in an upward angular direction, with the pipe assembly center of rotation located downstream at a 90-degree elbow and threaded connection to a three-way valve. The inspectors determined the failure was most likely caused by inadequate installation, inadequate external restraints, or a combination of both combined with the increased oil pressure during the 1B EDG run.
Due to the similar failure modes of both coupling assembly events, Southern Nuclear Company (SNC) had an opportunity to prevent the occurrence in February 2023. The original work order (WO SNC1091597) that replaced the coupling as part of the planned maintenance in November 2022 appeared to be sufficient. However, during the November post maintenance test the coupling failed which provided evidence of the couplings new failure mode. SNC had an opportunity to evaluate the available evidence via their corrective action program (CAP) to identify the nonconforming work order instructions that led to the coupling assembly failure. The CAP includes the use of WOs, such as troubleshooting WOs, to evaluate available evidence and disposition conditions adverse to quality. The following three paragraphs discuss the link between Criterion XVI and the troubleshooting process.
The SNC Quality Assurance Topical Report (QATR) describes the methods and establishes quality assurance program and administrative control requirements that meet Title 10 of the Code of Federal Regulations10 CFR 50, Appendix B. Section 16, Corrective Action, of the QATR describes the methods to meet Criterion XVI. It states in part, when complex issues arise where it cannot be readily determined if a condition adverse to quality exist, SNC documents establish the requirements for documentation and timely evaluation of the issue.
This process starts when a condition report (CR) is written. In accordance with the SNC CAP procedure that fulfills the regulatory requirements of Criterion XVI (NMP-GM002, version 16), a CR is defined in part, as a document that is initiated to identify any condition potentially adverse to quality.
The SNC Quality Assurance Program as described in the QATR is also applied to certain equipment and activities that are not safety related but support safe plant operations. These activities include those pertaining to maintenance and the assessment and evaluation of failed items while restoring to their intended condition, such as troubleshooting. As described in the QATR, SNC commits to compliance with ASME NQA11994. Subpart 2.18 of the NQA11994 requires that an assessment of failure cause and required maintenance shall be consistent with the type of item failure and the importance of the item. It further requires that for failures identified that could have serious effect on safety or operability, an engineering evaluation shall be performed and documented to substantiate or revise the failure assessment and corrective action planning.
SNC initiated CR 10920885 to identify the November 4, 2022, 1B EDG lube oil leak and coupling assembly failure. The licensee closed the CR to WO SNC1399361 to implement corrective actions in accordance with procedure NMP-GM002001, version 43.0, Corrective Action Program Instructions. Therefore, the WO was a part of the CAP as defined in NMP-GM002001. Based on the WO description and inspector interviews with Farley maintenance and engineering personnel, the purpose of WO SNC1399361 was to provide instructions for identifying the cause and correct the failed coupling assembly. The specific repair activities required to address the failure were unknown thus requiring more evidence about what happened and how it happened in accordance with NMP-MA012003, Maintenance Standards and Guidelines, for troubleshooting. NMP-MA012003 refers to NMP-AD002, Conduct of Problem Solving and Troubleshooting, for more specific troubleshooting performance standards. Due to the unknown repair activities to address the coupling
assembly issue related to a failure of a risk significant safety related EDG, at minimum, NMP-AD002 requires simple troubleshooting. The amount of troubleshooting rigor increases if the immediate cause of the failure is not identified.
SNC did not implement the troubleshooting standards when completing WO SNC1399361.
Based on the completed WO record and interviews, maintenance personnel did not identify an immediate cause of the coupling assembly failure before restoring 1B EDG to operable status. The corrective actions to address the failure consisted of disassembling and inspecting the coupling and the circulating oil pump discharge check valve for foreign material. Maintenance personnel did not identify foreign material or issues with the operation of the check valve or coupling. Even without a specific cause, the coupling and check valve were replaced with new like-for-like replacements. The WO lacked any additional information or documentation to support potential causes or mitigative actions and no engineering evaluations were performed. If an immediate cause cannot be identified, NMP-AD002 requires operational decision-making per procedure NMP-OS003, Operational Decision Making Issue Evaluation Process, before restoring the equipment to operable status. One purpose of the operational decision-making process is for evaluating decisions, such as potential mitigative actions, affecting the reliability of safety related equipment like the 1B EDG.
Following the February 26, 2023, 1B EDG coupling assembly failure, the licensee performed a more rigorous evaluation in which they determined more specific instructions were required to address the coupling assembly failure. The WO used to repair the failure (SNC1447993)
provided specific guidance for asfound data collection and documentation. Additional steps required asleft data regarding the adequacy of the piping arrangement to ensure a correct coupling piping insertion depth. Nothing conclusive was found regarding the immediate cause. Therefore, the licensee implemented WO SNC1449078 to modify the external restraints. This solution was developed to mitigate the lube oil piping from pulling out of the top of the coupling. The modification consisted of adding a welded restraint to the existing rigid structure and replacing the original conduit clamps with ubolts to increase the rigidity of the lube oil piping.
If the mitigative actions discussed above were implemented following the November 2022 coupling assembly failure, it is reasonable to assume the February 2023 failure would have been prevented or minimized to maintain the availability or operability of the 1B EDG. The licensees causal analysis (CAR 3922914) completed on July 3, 2023, further supports this conclusion. The analysis determined the 1B EDG coupling assembly failure was directly caused by the loosening and retightening of the piping during the coupling replacement which resulted in some loss of pipe thread engagement. This reduced the pipe assembly rigidity such that the end loads created from the upward motion of the lube oil flow and pressure created a moment arm that rotated the pipe assembly such that the upper vertical run of pipe dislodged from the coupling. The analysis also determined that additional restraints would have prevented the failure.
Corrective Actions: Following the February 2023 event, the licensee added additional external restraints to the 1B EDG circulation pump lube oil pipe before restoring it back to an operable status. An extent of condition was performed on all the other EDGs. The concern identified in this report only applied to the 12A and 2B EDG as they have the same coupling in the same configuration as the 1B EDG. The licensee evaluated the 12A and 2B EDGs coupling for adequate installation and monitored for movement during runs. In May 2023, the vulnerability
of the coupling failure was eliminated on the 12A and 2B EDG following a modification that replaced the coupling with hard pipe. The same modification for the 1B EDG is planned for July 2025.
Corrective Action References:
CR 10951589: Identified the 1B EDG leak in February 2023 WO SNC1449078: Implementation of modification to the 1B EDG external supports TE 1123337: Extent of condition evaluation WO SNC1462848 & SNC1462849: Implementation of the modification to eliminate the coupling on the 12A and 2B EDGs CAR 392214: 1B EDG lube oil leak Equipment Reliability Checklist (causal evaluation)
Performance Assessment:
Performance Deficiency: The failure to adhere to the troubleshooting standards as required by procedure NMP-MA012003, version 7.1, Maintenance Standards and Guidelines, and NMP-AD002, version 13.8, Conduct of Problem Solving and Troubleshooting following a substantial 1B EDG lube oil leak on November 4, 2022, was a performance deficiency. As a result, the licensee failed to identify the nonconforming work order instructions used to address the November 2022 coupling assembly failure which resulted in another failure that rendered the 1B EDG inoperable on February 26, 2023.
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 condition affected the reliability of the 1B EDG to perform its design basis function.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The finding could not be screened to be of very low safety significance (i.e., Green because the condition represented a loss of the PRA function of one train of a multi-train TS system for greater than its TS allowed outage time, therefore a detailed risk evaluation was required.
The significance determination for the finding is pending a detailed risk assessment that will be conducted by a regional Senior Reactor Analyst in accordance with IMC 0609 Appendix A.
Cross-Cutting Aspect: H.13 - Consistent Process: Individuals use a consistent, systematic approach to make decisions. Risk insights are incorporated as appropriate. The licensee made assumptions about the acceptability of the coupling repair in November 2022 without formally evaluating the available evidence. In addition, in making the decision to restore the 1B EDG to operable status following the November 2022 repairs, the licensee failed to consider the risk significance of a potential similar failure while in Mode 1. (DM.1)
Enforcement:
Violation: 10 CFR 50 Appendix B Criterion XVI Corrective Action, states, in part, measures shall be established to assure that conditions adverse to quality, such as nonconformances are promptly identified and corrected.
Technical Specification (TS) Limiting condition for operations (LCO) 3.0.1 requires, in part, that LCOs shall be met during the modes of applicability. TS LCO 3.8.1, AC Sources,
requires, in part, two operable diesel generator sets capable of supplying the onsite Class 1E distribution systems while in Modes 1, 2, 3, or 4.
Contrary to the above, on November 4, 2022, the licensee failed to identify and correct a condition adverse to quality associated with nonconforming work instructions for the installation of a lube oil coupling assembly for the unit 1B EDG following a coupling assembly failure and substantial lube oil leak. In addition, between December 7, 2022, to March 3, 2023, while the plant was in the modes of applicability, the 1B EDG was inoperable.
Specifically, the licensee did not adequately disposition the failure via troubleshooting WO SNC1399361 used to implement corrective actions in accordance with procedure NMP-GM002001, Corrective Action Program Instructions, version 43.0. The disposition was inadequate because the licensee failed to adhere to its troubleshooting standards and did not evaluate available evidence surrounding the coupling assembly failure after the immediate cause of the failure could not be identified during implementation of WO SNC1399361. As a result, following the failure on November 4, 2022, repairs to the EDG were limited to replacement of the coupling assembly in accordance with the existing nonconforming work instructions. This resulted in the inoperability of the EDG due to a similar failure on February 26, 2023, during a surveillance run. With the 1B EDG inoperable, the licensee failed to meet the LCO in accordance with TS 3.0.1 and 3.8.1 between December 7, 2022, and March 3, 2023.
Enforcement Action: This violation is being treated as an apparent violation pending a final significance (enforcement) determination.
EXIT MEETINGS AND DEBRIEFS The inspectors verified no proprietary information was retained or documented in this report.
On August 2, 2023, the inspectors presented the integrated inspection results to Mr. Dan Williams, Site Regulatory Affairs Manager, and other members of your staff.
On July 18, 2023, the inspectors presented the integrated inspection results to Mr.
Delson Erb, Site Vice President, and other members of the licensee staff.
On June 8, 2023, the inspectors presented the emergency preparedness program inspection results to Mr. Delson Erb, Site Vice President, and other members of the licensee staff.
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