IR 05000220/2024004
| ML25043A045 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 02/12/2025 |
| From: | Jason Schussler Division of Operating Reactors |
| To: | Rhoades D Constellation Energy Generation |
| References | |
| IR 2024004 | |
| Download: ML25043A045 (1) | |
Text
February 12, 2025
SUBJECT:
NINE MILE POINT NUCLEAR STATION, UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000220/2024004 AND 05000410/2024004 AND INDEPENDENT SPENT FUEL STORAGE INSTALLATION INSPECTION REPORT 07201036/2024004
Dear David Rhoades:
On December 31, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Nine Mile Point Nuclear Station, Units 1 and 2. On February 6, 2025, the NRC inspectors discussed the results of this inspection with Carl Crawford, Plant Manager, and other members of your staff. The results of this inspection are documented in the enclosed report.
No findings or violations of more than minor significance were identified during this inspection.
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, Jason E. Schussler, Chief Projects Branch 1 Division of Operating Reactor Safety Docket Nos. 05000220, 05000410, and 07201036 License Nos. DPR-63 and NPF-69
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000220, 05000410, and 07201036
License Numbers:
Report Numbers:
05000220/2024004, 05000410/2024004, and 07201036/2024004
Enterprise Identifier: I-2024-004-0039
I-2024-001-0104
Licensee:
Constellation Energy Generation, LLC
Facility:
Nine Mile Point Nuclear Station Units 1 and 2
Location:
Oswego, NY
Inspection Dates:
October 1, 2024 to December 31, 2024
Inspectors:
C. Kline, Senior Resident Inspector
B. Sienel, Resident Inspector
C. Borman, Health Physicist
R. Chan, Operations Engineer
M. Donithan, Senior Operations Engineer
T. Fish, Senior Operations Engineer
C. Hargest, Health Physicist
M. Henrion, Senior Project Engineer
Y. Kim, Senior Structural Engineer
K. Mangan, Senior Reactor Inspector
D. McHugh, Reactor Inspector
L. Sinclair, Operations Engineer
G. Stock, Reactor Operations Engineer
T. Winkel, Health Physicist
G. Zhao, Structural Engineer
Approved By:
Jason E. Schussler, Chief
Projects Branch 1
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Nine Mile Point Nuclear Station, 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
No findings or violations of more than minor significance were identified.
Additional Tracking Items
Type Issue Number Title Report Section Status LER 05000410/2024-002-00 Unit 2 Automatic Reactor Scram on Turbine Trip due to Failed Breaker 71153 Closed
PLANT STATUS
Unit 1 began the inspection period at rated thermal power. On October 25, 2024, operators reduced power to 66 percent for a planned rod pattern adjustment and turbine valve testing. The unit was returned to rated thermal power on October 27, 2024. On October 30, 2024, operators reduced power to 76 percent in response to indications of a fuel element defect. Operators increased reactor power to 90 percent following power suppression testing on November 6, 2024. On December 6, 2024, operators reduced power to 70 percent for a planned rod pattern adjustment. Power was restored to 90 percent the following day. Subsequently, several power adjustments of less than 1 percent were made in response to the fuel defect and Unit 1 completed the inspection period at 89 percent rated thermal power.
Unit 2 began the inspection period at rated thermal power. On November 23, 2024, operators reduced power to 64 percent for a planned rod pattern adjustment and feedwater pump realignment. Power was returned to rated thermal power on November 24, 2024, where it remained for the rest 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 D, Plant Status, observed risk significant activities, and completed on-site portions of IPs. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
REACTOR SAFETY
71111.01 - Adverse Weather Protection
Seasonal Extreme Weather Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal cold temperatures for the following systems: fire protection, reactor building ventilation, FLEX equipment, and circulating water on December 16, 2024.
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (3 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 2 high pressure core spray system on October 22, 2024
- (2) Unit 1 emergency diesel generator (EDG) 103 on October 22, 2024
- (3) Unit 1 11 liquid poison system on October 29, 2024
Complete Walkdown Sample (IP Section 03.02) (1 Sample)
- (1) Unit 2 standby liquid control system on November 19, 2024
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (3 Samples)
The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:
- (1) Unit 2 turbine building 306', fire area 50, on October 9, 2024
- (2) Unit 2 control building 288', fire area 24, on October 16, 2024
- (3) Unit 1 reactor building northeast 198' to 237' containment spray areas, fire area 1, on December 18, 2024
71111.06 - Flood Protection Measures
Flooding Sample (IP Section 03.01) (1 Sample)
- (1) Unit 1 reactor building elevation 198' northeast corner room on December 18, 2024
71111.07A - Heat Exchanger/Sink Performance
Annual Review (IP Section 03.01) (1 Sample)
The inspectors evaluated readiness and performance of:
- (1) Unit 2 Division II standby diesel generator jacket water heat exchanger 2EGS*E2B
71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance
Requalification Examination Results (IP Section 03.03) (2 Samples)
- (1) The inspectors reviewed and evaluated the Unit 1 licensed operator examination failure rates for the requalification annual operating exams administered October - November 2024 and the biennial written examinations administered October - November 2024.
- (2) The inspectors reviewed and evaluated the Unit 2 licensed operator examination failure rates for the requalification annual operating exam completed on November 14, 2024.
71111.11B - Licensed Operator Requalification Program and Licensed Operator Performance
Licensed Operator Requalification Program (IP Section 03.04) (1 Sample)
- (1) Biennial Requalification Written Examinations
The inspectors evaluated the quality of the Unit 1 licensed operator biennial requalification written examinations administered October - November 2024.
Annual Requalification Operating Tests
The inspectors evaluated the adequacy of the Unit 1 annual requalification operating test administered week of October 28, 2024.
Administration of an Annual Requalification Operating Test
The inspectors evaluated the effectiveness of the facility licensee in administering requalification operating tests required by Title 10 of the Code of Federal Regulations (10 CFR) Part 55.59(a)(2) and that the facility licensee is effectively evaluating its licensed operators for mastery of training objectives.
Requalification Examination Security
The inspectors evaluated the ability of the facility licensee to safeguard examination material, such that the examination is not compromised.
Remedial Training and Re-examinations
The inspectors evaluated the effectiveness of remedial training conducted by the licensee, and reviewed the adequacy of re-examinations for licensed operators who did not pass a required requalification examination.
Operator License Conditions
The inspectors evaluated the licensees program for ensuring that licensed operators meet the conditions of their licenses.
Control Room Simulator
The inspectors evaluated the adequacy of the facility licensees control room simulator in modeling the actual plant, and for meeting the requirements contained in 10 CFR 55.46.
71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance
Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (2 Samples)
- (1) The inspectors observed and evaluated Unit 1 licensed operator performance in the control room during a downpower to 66 percent for rod pattern change and turbine stop valve testing on October 25, 2024.
- (2) The inspectors observed and evaluated Unit 2 licensed operator performance in the control room during a downpower to 62 percent for rod pattern adjustment and feed pump realignment on November 23, 2024.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (2 Samples)
- (1) The inspectors observed and evaluated a Unit 2 annual simulator examination with scenarios that included safety system failures, steam leaks in primary containment, and failures to scram on October 15, 2024.
- (2) The inspectors observed and evaluated a Unit 1 annual simulator examination with scenarios that included pressure regulator failures, pump and valve malfunctions, a fuel element failure, and an unisolable leak into secondary containment on November 5, 2024.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (3 Samples)
The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended functions:
- (1) Unit 2 'F' service water following failure of discharge check valve failure to close on August 29, 2024
- (2) Unit 1 diesel fire pump following failure on October 8, 2024
- (3) Unit 1 EDG 102 following circulating oil pump trip on October 31, 2024
Quality Control (IP Section 03.02) (2 Samples)
The inspectors evaluated the effectiveness of maintenance and quality control activities to ensure the following SSCs remain capable of performing their intended functions:
- (1) Commercial grade dedication of bearing installed in the Unit 2 Division I standby diesel generator fuel oil transfer system pump 2EGF*P1C on November 17, 2024
- (2) In-process controls during Unit 2 Division III standby diesel generator system outage window on November 22, 2024
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (5 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 elevated risk during high pressure core spray system outage window on October 21, 2024
- (2) Unit 1 elevated risk during planned 102 EDG maintenance on October 22, 2024
- (3) Unit 1 elevated risk during planned 12 liquid poison system maintenance on October 29, 2024
- (4) Unit 2 elevated risk during planned Division II standby diesel generator maintenance on October 30, 2024
- (5) Unit 2 elevated risk during planned Division III standby diesel generator maintenance on November 21, 2024
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) Unit 1 turbine stop valve 11 input to reactor protection system following failure to respond during testing on October 8, 2024
- (2) Unit 1 EDG 102 following the trip of the circulating oil pump breaker on October 31, 2024
- (3) Unit 2 safety relief valve 2MSS*PSV122 following increased tailpipe temperature on November 13, 2024
- (4) Unit 2 Division I diesel generator room area cooler 2HVP*UC1A test failure on November 13, 2024
- (5) Unit 1 emergency condenser (EC) radiation monitoring following prolonged degradation of EC radiation monitor 121 on November 19, 2024
71111.18 - Plant Modifications
Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (1 Sample)
The inspectors evaluated the following temporary or permanent modifications:
- (1) Permanent Modification: ECP-24-000154, Replacement of RCIC [reactor core isolation cooling] Division II Differential Pressure Transmitter
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) N1-PM-M9, Operation of Fire Pumps, following fuel injector replacement and governor adjustment, on October 9, 2024
- (2) N1-ST-M4A, Emergency Diesel Generator 102 and PB 102 Operability Test, following planned maintenance, on October 23, 2024
- (3) N1-ST-Q8B, Liquid Poison Pump 12 and Check Valve Operability Test, following planned 12 liquid poison pump preventive maintenance, on October 31, 2024
- (4) N2-PM-@026, Diesel Generator Start - Division I and II, following maintenance, on November 6, 2024
- (5) N2-OSP-EGS-M@001, Diesel Generator and Diesel Air Start Valve Operability Test - Division I and II, following maintenance, on November 13, 2024
- (6) N2-OSP-EGS-R005, Diesel Generator Emergency Core Cooling System Start -
Division III, following planned maintenance, on November 22, 2024
Surveillance Testing (IP Section 03.01) (1 Sample)
- (1) N2-OSP-EGS-M@001, Unit 2 Division I Diesel Slow Start, on November 13, 2024
Inservice Testing (IST) (IP Section 03.01) (2 Samples)
- (1) N1-ST-Q6A, Containment Spray System Loop 111 Quarterly Operability Test, on October 2, 2024
- (2) N2-OSP-CSH-Q@002, High Pressure Core Spray Pump and Valve Operability Test, on October 23, 2024
Containment Isolation Valve (CIV) Testing (IP Section 03.01) (1 Sample)
- (1) N1-ST-Q4, Reactor Coolant System Isolation Valves Operability Test, on November 14,
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification
The inspectors verified licensee performance indicators submittals listed below:
MS08: Heat Removal Systems (IP Section 02.07)===
- (1) Unit 1 for the period of October 1, 2023 through September 30, 2024
- (2) Unit 2 for the period of October 1, 2023 through September 30, 2024
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
- (1) Unit 1 for the period of October 1, 2023 through September 30, 2024
- (2) Unit 2 for the period of October 1, 2023 through September 30, 2024
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
- (1) Unit 1 for the period of October 1, 2023 through September 30, 2024
- (2) Unit 2 for the period of October 1, 2023 through September 30, 2024
OR01: Occupational Exposure Control Effectiveness Sample (IP Section 02.15) (1 Sample)
- (1) Units 1 and 2 for the period of October 1, 2023 through September 30, 2024
PR01: Radiological Effluent Technical Specifications/Offsite Dose Calculation Manual Radiological Effluent Occurrences (RETS/ODCM) Radiological Effluent Occurrences Sample (IP Section 02.16) (1 Sample)
- (1) Units 1 and 2 for the period of October 1, 2023 through September 30, 2024
71152A - Annual Follow-up Problem Identification and Resolution Annual Follow-up of Selected Issues (Section 03.03)
The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:
- (1) Issue Reports (IRs) 04774076, 04758780, and 04762854 - Review of Corrective Actions for Unit 1 Diesel Fire Pump
- (2) IR 04803847 - Breaker 41M-2EXSX01 Generator Exciter Field Breaker Failure
- (3) IR 04813728 - Review of Corrective Actions for Unit 1 EDG Lube Oil Pump Failures
- (4) IR 04723637 - Review of Corrective Actions for Unit 2 Service Water Pump 'D' Inboard Bearing Failure
71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02)
- (1) The inspectors reviewed Constellations corrective action program to identify potential trends that might be indicative of a more significant safety issue.
71153 - Follow-up of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)
The inspectors evaluated the following licensees event reporting determinations to ensure it complied with reporting requirements.
- (1) LER 05000410/2024-002-00, Unit 2 Automatic Reactor Scram on Turbine Trip due to Failed Breaker (ADAMS Accession No. ML24326A058). The inspection conclusions associated with this LER are documented in this report under Inspection Results. This LER is Closed.
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
60853 - Onsite Fabrication of Components and Construction of an Independent Spent Fuel Storage Installation (ISFSI)
- (1) The inspectors observed and evaluated the licensees activities related to concrete placement for the expansion of their ISFSI pad, which will eventually store spent fuel previously generated by the licensee, on October 30-31,
INSPECTION RESULTS
Minor Performance Deficiency 71152A Breaker 41M-2EXSX01 Generator Exciter Field Breaker Failure
Minor Performance Deficiency: In response to operating experience from LaSalle Station, Constellation created a work order at Nine Mile Point Station, (WO) C93855815, to check the main generator field breaker for high resistance. Constellation completed the WO at Nine Mile Point Station on March 26, 2024. The inspectors noted the WO did not contain step by step instructions, specifically it did not identify the location of the resistance measurements, or the instrument to be used. Upon review the inspectors noted the acceptance criteria in the WO was greater than 150 micro ohms and a digital voltage meter was used for the measurement. The inspectors noted the appropriate acceptance criterion is less than 150 micro ohms and the appropriate instrument is a digital low resistance ohm meter as stated in preventative maintenance document N2-EPM-EXS-V553, "Main Generator/Exciter Field Breaker PM." As a result of not having specific step by step work order instructions the inspectors noted one resistance measurement was recorded as 0.09 ohms. Also, the inspectors reviewed the completed work order instructions and concluded the exact measurement location is not clearly specified. Consequently, the inspectors could not determine if a high resistance connection existed in March 2024. Notably, 6 months following these measurements and work order completion, on September 23, 2024, the field breaker failed and caught fire. The breaker failure lead in a reactor scram and the fire was extinguished by onsite personnel. The inspectors noted that no safety related components were impacted by the fire.
Following the breaker failure and fire Constellation performed a root cause evaluation (RCE). The RCE concluded that a mechanical fault internal to the breaker caused a high resistance connection to develop. The RCE provided computer plot trends which indicated that the voltage and current were within normal values up to the time of the failure. These recorded plot trends are an indication that the circuit breaker did not have a high resistance connection until just before the failure.
Maintenance procedure MA-AA-716-010-10, "Writers Guide for Maintenance Work Order Instructions," requires that work orders have step by step instructions to accomplish scope of the WO task and to identify appropriate acceptance criteria. Contrary to this, the previously cited, WO C93855815 did not provide step by step instruction or appropriate acceptance criteria to complete the scope of the WO task. Specifically, the WO only took one resistance measurement when a minimum of two was required and the acceptance criterion should have specified the requirement of less than 150 micro ohms.
Screening: The inspectors determined the performance deficiency was minor. Constellation determined that it was unlikely that a high resistance connection existed until just prior to failure of the breaker that caused the reactor scram on September 23, 2024. The conclusion is support by computer plot data noting voltage and current trends. Therefore, the performance deficiency of inaccurate work instructions and acceptance criteria was not a clear contributor to the breaker failure. This minor performance deficiency is captured in IR 04803847.
Observation: Review of Corrective Actions for Unit 1 Diesel Fire Pump 71152A The inspectors reviewed Constellations cause determination associated with the degraded performance of the Unit 1 diesel fire pump engine and evaluated the effectiveness of intermediate and long-term corrective actions that were performed following the diesel failing to start or run on multiple occasions between October 2023 and July 2024. The inspectors noted that the pump is credited as a fire suppression water source and is also credited in the probabilistic risk assessment to mitigate several accident scenarios assuming the failure of multiple safety-related equipment.
The inspectors observed that following preventive maintenance, which replaced the six engine fuel injectors in September 2023, the diesel engine failed to run on two occasions (October 2023 and March 2024) due to engine malfunction. Constellation staff determined the failures were caused by the fuel injectors. Following an investigation, Constellation staff concluded the fuel injector degraded performance was due to inadequate fuel injector refurbishment that had been performed at an offsite facility. Once identified, Constellation, using a different vendor, refurbished and witnessed testing of 18 injectors. Six injectors, chosen based on test results, were then installed in the engine. The inspectors noted that the injectors were refurbished because injectors for this engine are no longer manufactured.
After installing the injectors, Constellation implemented a condition monitoring program to monitor diesel performance. In August 2024, the engine was determined to not meet performance monitoring standards and was declared non-functional. Maintenance staff with vendor support performed engine tuning activities to restore performance. Following adjustments to the engine, on October 10, 2024, Constellation staff completed a 12-hour endurance run on the diesel fire pump with satisfactory results.
The inspectors also reviewed Constellation staffs evaluations of two additional engine-failed-to-start and/or -run events. In one case, the diesel air inlet manifold emergency close damper had repositioned closed prior to the engine start, and in the second case the air start motor failed to operate. The inspectors reviewed the causes and corrective actions associated with these failures and determined the actions corrected the condition and associated cause.
Inspectors noted that during the periods the diesel fire pump was not functional, Constellation staff opened the cross-connect between the Unit 1 and Unit 2 fire headers. This action allowed Unit 1 to credit the use of the Unit 2 fire pumps in order to comply with regulatory requirements for fire protection and to reduce overall risk for design basis events. During the inspection, the inspectors questioned if the configuration complied with fire protection standards for separate water supply sources. Constellation staff identified a potential hot short location for the motor operated valve opened as part of the compensator action. The issue was entered into the corrective action program for resolution. The inspectors determined that the fire scenario that could cause a hot short on the motor operated valve would not impact the other credited fire pump.
The inspectors reviewed the condition reports, corrective actions, and other documentation.
The inspectors noted that Constellations evaluation and corrective actions were in accordance with site procedures. The inspectors did not identify any performance deficiencies or violations as a result of this inspection.
Observation: Review of Corrective Actions for Unit 1 EDG Lube Oil Pump Failures 71152A The inspectors reviewed Constellations corrective action program evaluations and corrective actions regarding Unit 1 EDGs 102 and 103 circulating lube oil pump failures. The purpose of the pumps is to maintain a constant flow of lubricating oil throughout the EDGs when they are in standby, and in conjunction with the standby lube oil heater, to keep the lube oil warm.
They are not a support function for EDG lubrication, are not safety-related, and are not covered by technical specifications (TSs). In accordance with N1-OP-45, "Emergency Diesel Generators," if this lube oil pump is inoperable, the affected EDG remains operable as long as lube oil temperature remains above 85 degrees Fahrenheit. If sump temperatures fall below 85 degrees Fahrenheit, the EDG is inoperable.
Since 2021 there have been seven trips of the circulating lube oil pumps on EDGs 102 (four trips) and 103 (three trips). The licensee documented those trips in IRs 04427748, 04467177, 04479221, 04528148, 04673045, 04809936, and 04813728. They determined that the probable cause of the pump motor failures was a vibration-induced degradation to the motor brush holders, which restricted brush motion, resulting in arcing between the brush contact surfaces and the commutator.
After both motors were replaced with new ones in late 2022 (WOs C93841969 and C93824032), they tripped again after approximately 6 months (EDG 102) and 22 months (EDG 103). The same failure mechanism was identified in each, but with a new hypothesis: Vibration readings on the motors have always been normal, but it was noted that the pumps keep running while the EDG is running, a possible contributing factor is that the vibrations from the EDG skid are causing the brush holder degradation. In discussion with the system engineer it was determined that the original equipment vendor changed the configuration of the motors mounting plate. Proper fitting in the current configuration requires modification to the holes in the mounting plate and shimming the motor upwards in relation to the pump.
An action was established to query the vendor for pumps with a more robust design, and evaluate using a brushless direct current motor, which would eliminate motor brushes as a failure mechanism. As a compensatory measure, the licensee has established a crash cart with a new pump and motor and a planned WO to quickly respond to a motor failure on either EDG. This pre-planning should help prevent EDG TS inoperability time due to the engines lube oil cooling to below 85 degrees Fahrenheit.
The licensee also has a compensatory action to raise the temperature in the EDG rooms if a circulating lube oil pump fails. This should slow the rate of cooling of the lube oil in the engine sump, and delay TS entry, but hasnt been invoked yet, so its efficacy is unknown at this time.
The inspectors reviewed the condition reports, corrective actions, and other documentation.
The inspectors noted that Constellations evaluation and corrective actions were in accordance with site procedures. The inspectors did not identify any performance deficiencies or violations as a result of this inspection.
Observation: Breaker 41M-2EXSX01 Generator Exciter Field Breaker Failure 71152A On September 23, 2024, at 0720, with Unit 2 in mode 1 at 100 percent power, the reactor automatically scrammed due to turbine stop valve closure on a turbine trip. The scram was not complex. The turbine trip was caused from the loss of field relay actuation. The loss of field was caused by a high resistance connection on the negative poll of the main generator field breaker which resulted in a fire. The fire was extinguished by on-site personnel and did not impact any safety-related components.
The main generator field breaker provides the current path from the exciter to the main field. Field current is adjusted using the voltage regulator. Normal field current is approximately 4500 amps. Due to the large current through the field breaker, small resistance in the connections would cause a large amount of heat.
Constellation PowerLabs performed a failure analysis and concluded that the cause of the initial high resistance between the negative pole contacts is unknown. Based on the evidence, it may have been attributed to 1) low contact force due to the missing stationary contact springs; and/or 2) foreign or displaced material in the contact path.
Constellation performed an RCE. The RCE concluded that a mechanical fault internal to the breaker caused a high resistance connection to develop, ultimately resulting in loss of the generator field. Constellation provided voltage and current trends that indicate that the failure did not occur over time which supports the RCE conclusion. The corrective action to prevent recurrence is to eliminate the main generator field breaker.
The inspectors identified a minor performance deficiency associated with the prior work activities on the breaker which is documented within this report; the inspectors did not identify any additional findings or violations as a result of this inspection.
Observation: Unit 2 Service Water Pump 'D' Inboard Bearing Failure 71152A The inspectors reviewed Constellation's evaluation and corrective actions associated with failure of Unit 2 service water pump 'D' inboard bearing on December 14, 2023. Specifically, inspectors focused on the failure analysis and corrective actions completed under IR 04723637.
On December 14, 2023, operators were alerted to rising service water pump 'D' inboard bearing temperature by alarm 3601202, "Service Water Pump 1B/1D/1F Pump/Motor BRG Temp High." Operations personnel took alarm response procedure actions and field personnel reported increased seal leakage and an acrid odor in the Division II service water bay. The subsequent rise and fall of bearing temperature were consistent with bearing failure. The pump was secured and the bearing was replaced.
Subsequent material failure analysis identified foreign material (lead, iron, aluminum and silicon) in the oil, in the displaced Babbitt material, and embedded in the bearing surface. Constellation determined that the most likely source of the foreign material was from the accumulation of wear products in the oil reservoir. The wear materials were disturbed during the oil replacement preventive maintenance action which had been completed two weeks prior to bearing failure. The oil reservoir drain is approximately 1/4 inch above the bottom of the oil reservoir and complete reservoir draining is not possible without more intrusive disassembly. Access to the reservoir requires rolling out the lower bearing, a task which normally occurs every six years, during pump refurbishment by contracted personnel. To prevent reoccurrence, Constellation revised the refurbishment contracting standard to include a witness point for Constellation personnel to inspect the oil reservoir during bearing inspection. The bearing inspection is an existing quality control point conducted by Constellation personnel as part of refurbished pump receipt and is conducted at contractor facilities. The inspectors noted that the current inspection requirement assumes skill-of-the-trade as the inspection standard and would benefit from inclusion of an explicit inspection standard.
The inspectors reviewed the evaluation, extent of condition review, procedures, manufacturers failure analysis and relevant IRs, and interviewed the licensee subject matter expert on the topic. The inspectors noted that Constellations evaluation and corrective actions were in accordance with site procedures. The inspectors did not identify any performance deficiencies or violations as a result of this inspection.
Observation: Semiannual Trend 71152S The inspectors evaluated a sample of issues and events that occurred from July 2024 through December 2024 to determine whether issues were appropriately considered as emerging or adverse trends. The inspectors verified issues were appropriately evaluated by Constellation staff for potential trends and addressed within the scope of the corrective action program or through department review. The inspectors did not identify any new trends that could indicate a more significant safety issue. The inspectors determined that Constellation personnel identified trend issues at a low threshold and entered them into the corrective action program for resolution. The inspectors noted licensee-identified trends in grounds experienced on the Unit 1 battery 11 and Unit 1 electromatic relief valve battery elevated cell temperatures. Neither trend currently impacts system operability and Constellation personnel are monitoring these conditions. The inspectors independently evaluated the deficiencies noted above for significance in accordance with the guidance in IMC 0612, Appendix B, "Issue Screening," and Appendix E, "Examples of Minor Issues." The inspectors determined that none of the conditions were deficiencies of greater than minor significance and, therefore, are not subject to enforcement action in accordance with the NRC's Enforcement Policy.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
x On February 6, 2025, the inspectors presented the integrated inspection results to Carl Crawford, Plant Manager, and other members of the licensee staff.
THIRD PARTY REVIEWS
Inspectors reviewed Institute of Nuclear Power Operations reports that were issued during the inspection period.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
N1-OP-64
Meteorological Monitoring
21
N2-OP-102
Meteorological Monitoring
28
Procedures
N1-OP-12
Liquid Poison System
03000
N1-OP-45
2
N2-OP-36A
Standby Liquid Control System
2
N2-OP-36A-
Lineups
Standby Liquid Control System - Lineups
001
Fire Plans
N1-PFP-0101
Unit 1 Pre-Fire Plans
00700
N2-FPI-PFP-0201 Unit 2 Pre-Fire Plans
007
Corrective Action
Documents
04806541
Procedures
N1-IPM-104-001
Reactor Building Floor/Equipment Drain Sump Level and
Wall Mounted Level Switch Instrument Calibration
completed
07/22/2023
and
06/21/2021
71111.07A Corrective Action
Documents
04813443
NDE Reports
WO-01456-090
Work Orders
C93934972
Corrective Action
Documents
04718185
04718539
04718736
04774366
Miscellaneous
Unit 1 Fire Protection a(1) Action Plan
09/03/2024
03790
PREF [procurement requirements evaluation form[
97-0884
Nuclear Procurement Test and Inspection Report
Procedures
Maintenance Rule Implementation per NEI 18-10
Maintenance Rule - (a)(1) and (a)(2) Requirements
N2-OSP-EGF-
Q@001
D.G. Fuel Oil Transfer Pump and Valve Operability Test and
ASME XI Functional Pressure Test
00700
Work Orders
C93949157
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
Resulting from
Inspection
04813350
Procedures
OP-AA-201-012-
1001
Operations On-line Fire Risk Management
OP-NM-201-012-
1001
Operations On-line Fire Risk Management at NMP
200
Corrective Action
Documents
04722262
04785411
04786004
04790485
04801863
04804263
04805206
04812434
04813728
Miscellaneous
Safety Relief Valve 2MSS*PSV122 Leaking By
10/02/2024
Procedures
N1-OP-50B
Process Radiation Monitoring System
01600
Engineering
Changes
ECP-24-000154
Replacement of RCIC Division II Differential Pressure
Transmitter
000
Corrective Action
Documents
04806124
04813584
Procedures
N1-PM-M9
Operation of Fire Pumps
019
N1-ST-M4A
Emergency Diesel Generator 102 and PB 102 Operability
Test
033
N1-ST-Q25
Emergency Diesel Generator cooling Water Quarterly Test
035
N1-ST-Q6A
Containment Spray System Loop 111 Quarterly Operability
Test
23
N1-ST-Q8B
Liquid Poison Pump 12 and Check Valve Operability Test
01600
N2-OSP-EGF-
Q@001
D.G. Fuel Oil Transfer Pump and Valve Operability Test and
ASME XI Functional Pressure Test
008
N2-OSP-EGS-
Diesel Generator and Diesel Air Start Valve Operability Test
26
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
M@001
- Division I and II
N2-OSP-EGS-
R005
U2 Diesel Generator ECCS Start Division III
006
N2-PM-@026
Diesel Generator Start Following Maintenance - Division I
and II
006
Work Orders
C93794734
C93934972
C93949313
C93957061
71151
Miscellaneous
Regulatory Assessment Performance Indicator Guideline
Corrective Action
Documents
04427748
04467177
04479221
04528148
04673045
04710571
04723637
04758100
04758780
04762854
04774076
04774366
04780622
04780806
04785641
04793583
04794402
04803847
04807780
04809936
04813728
Drawings
C-18030-C
Fire Protection Water System Piping and Instrumentation
Diagram
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Engineering
Evaluations
S0-FLOOD-F001
Internal Flooding Hazard Analysis
Procedures
N1-MPM-100-851 Diesel Fire Pump Engine Preventive Maintenance
00800
N1-OP-21A
Fire Protection System - Water
2600
Work Orders
C93809476
C93823235
C93946369
Corrective Action
Documents
04779953
04782058
04784717
04784908
04788195
04796362
04800026
04800111
04802058
04803976
04806900
04807958
04813704
04815161
04815162
04819350
04821372