IR 05000277/2024003
| ML24309A105 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/04/2024 |
| From: | Sarah Elkhiamy NRC/RGN-I/DORS |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| References | |
| IR 2024003 | |
| Download: ML24309A105 (1) | |
Text
November 4, 2024
SUBJECT:
PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3 -
INTEGRATED INSPECTION REPORT 05000277/2024003 AND 05000278/2024003
Dear David Rhoades:
On September 30, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Peach Bottom Atomic Power Station, Units 2 and 3. On October 10, 2024, the NRC inspectors discussed the results of this inspection with Martin Bonifanti, Site Vice President, 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, Sarah H. Elkhiamy, Chief Projects Branch 4 Division of Operating Reactor Safety
Docket Nos. 05000277 and 05000278 License Nos. DPR-44 and DPR-56
Enclosure:
As stated
Inspection Report
Docket Numbers: 05000277 and 05000278
License Numbers: DPR-44 and DPR-56
Report Numbers: 05000277/2024003 and 05000278/2024003
Enterprise Identifier: I-2024-003- 0041
Licensee: Constellation Energy Generation, LLC
Facility: Peach Bottom Atomic Power Station, Units 2 and 3
Location: Delta, PA 17314
Inspection Dates: July 1, 2024 to September 30, 2024
Inspectors: S. Rutenkroger, Senior Resident Inspector C. Dukehart, Resident Inspector J. Ayala, Senior Health Physicist J. Kepley, Operations Engineer
Approved By: Sarah H. Elkhiamy, Chief Projects Branch 4 Division of Operating Reactor Safety
Enclosure
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Peach Bottom Atomic Power Station,
Units 2 and 3, 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
None.
PLANT STATUS
Unit 2 began the inspection period at rated thermal power (RTP). On July 5, 2024, the unit was shut down for a maintenance outage to replace a degraded reactor recirculation pump seal. The unit was restarted on July 9, 2024. On July 10, 2024, the main generator turbine was manually tripped due to degrading main condenser vacuum which caused the reactor to automatically scram. After plugging main condenser tubes, the unit was restarted on July 11, 2024. The unit was restored to RTP on July 16, 2024, after the resolution of air in-leakage into the main condenser. On July 19, 2024, the unit was down powered to 61 percent for a control rod pattern adjustment and returned to RTP the following day. On July 28, 2024, the unit was down powered to 72 percent for a control rod pattern adjustment to fully withdraw all control rods and returned to RTP the following day. The unit remained at or near RTP for the remainder of the inspection period and ended the inspection period in end-of-cycle coastdown.
Unit 3 began the inspection period at RTP. On September 6, 2024, the unit was down powered to 67 percent for a control rod pattern adjustment and returned to RTP the following day. The unit remained at or near RTP for the remainder of the inspection period.
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html.
Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors performed activities described in IMC 2515, Appendix 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)
The inspectors evaluated readiness for seasonal extreme hot weather conditions for the following systems:
- (1) Units 2 and 3, emergency service water, high-pressure service water (HPSW),emergency diesel generator (EDG), and adjustable speed drive on July 15 and 16, 2024
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (4 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 2, high-pressure coolant injection system following unit start-up (SU) on July 17, 2024
- (2) Unit 2, reactor core isolation cooling system on July 31, 2024
- (3) Unit 3, B loop of residual heat removal (RHR) system during A loop maintenance on August 7, 2024
Complete Walkdown Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated system configurations during a complete walkdown of the Unit 2, A loop of the RHR system on September 24, 2024.
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (5 Samples)
The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:
- (1) Unit 2, fire area PF-5D, '2B' & '2D' core spray rooms on July 23, 2024
- (2) Unit 2, fire area PF-5K, reactor building general area, elevation 195 on August 26, 2024
- (3) Unit common, fire area PF-144, circulating water pump structure, general area on August 29, 2024
- (4) Unit 2, fire area PF-5H/-5P, reactor building general area, elevation 135 on September 23, 2024
- (5) Unit 2, fire area PF-1, reactor building, '2A' & '2C' RHR pump and heat exchanger room on September 30, 2024
71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance
Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (1 Sample)
- (1) The inspectors observed and evaluated licensed operator performance in the control room during SU preparations, reactor SU, criticality, and heat-up on July 8 and 9, 2024
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated licensed operator requalification training in the simulator on September 9, 2024
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (4 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) Unit common, 'A' emergency service water system through July 23, 2024
- (2) Unit 3, standby liquid control system through August 16, 2024
- (3) Unit 2, B loop of core spray system through August 22, 2024
- (4) Unit 3, 'A' loop of RHR system through September 11, 2024
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, number 2 SU and emergency auxiliary transformer planned maintenance outage on July 1, 2024
- (2) Unit common, 'A' emergency service water system planned maintenance on July 23, 2024
- (3) Unit 3, '3A' and '3C' HPSW pump planned replacements on August 5, 2024
- (4) Unit 3, A loop of RHR system planned maintenance outage on August 6, 2024
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (8 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
- (1) Unit 2, waterbox issues and high offgas flow impacting steam jet air ejector operation and main condenser vacuum on July 10, 2024
- (2) Unit 2, new fuel receipt identified water rod locking pin outside of acceptance criteria on July 17, 2024
- (3) Unit 2, 'E-32' 4kV emergency bus undervoltage degraded voltage high setting time delay relay 127z-1701 outside of acceptance criteria on July 18, 2024
- (4) Unit 2, next generation controller failure on B channel of the A recirculation pump adjustable speed drive on July 28, 2024
- (5) Unit 3, 'C' HPSW pump opening sleeve section fell into the pump bay, was not retrieved, and was evaluated to remain until the next refueling outage on August 9, 2024
- (6) Unit 3, monitoring well elevated tritium levels on August 15, 2024
- (7) Unit 3, HPSW leak on drain line on September 6, 2024
- (8) Unit 2, 2A leading edge flow meter string going from normal to fail on September 8, 2024
71111.20 - Refueling and Other Outage Activities
Refueling/Other Outage Sample (IP Section 03.01) (2 Samples)
- (1) The inspectors evaluated a planned Unit 2 maintenance outage from July 5 through July 9, 2024.
- (2) The inspectors evaluated an unplanned Unit 2 outage on July 10 and 11, 2024.
71111.24 - Testing and Maintenance of Equipment Important to Risk
The inspectors evaluated the following testing and maintenance activities to verify system operability and/or functionality:
Post-Maintenance Testing (PMT) (IP Section 03.01) (5 Samples)
- (1) Unit 2, '2A' recirculation pump seal replacement on July 7, 2024
- (2) Unit common, solenoid valve, SV-0-36B-00475-01, instrument air inlet tubing repair on August 27, 2024
- (3) Unit 3, 'C' HPSW system drain line repair on September 12, 2024
- (4) Unit common, 'E-4' EDG governor booster pump replacement on September 18, 2024
- (5) Unit 3, A RHR pump room cooler opening, cleaning, and reassembly on September 25, 2024
Surveillance Testing (IP Section 03.01) (8 Samples)
- (1) Unit 3, A RHR loop pump, valve, flow and unit cooler functional and in-service test on July 2, 2024
- (2) Unit 2, zero pressure control rod drive scram insertion timing of selected control rods on July 8, 2024
- (3) Unit 2, functional test of 'E-32' 4kV undervoltage relays on July 18, 2024
- (4) Unit common, 00G310 diverse and flexible coping strategies (FLEX) generator run on July 30, 2024
- (5) Unit common, 'E-2' EDG 24-hour endurance test on September 3, 2024
- (6) Unit common, E-2 EDG cardox system simulated actuation and air flow test on September 23, 2024
- (7) Unit common, 'E-4' EDG cardox system simulated actuation and air flow test on September 23, 2024
- (8) Unit 2, 'A' RHR loop pump, valve, flow and unit cooler functional and in-service comprehensive test on September 26, 2024
71114.06 - Drill Evaluation
Additional Drill and/or Training Evolution (2 Samples)
The inspectors evaluated:
- (1) The inspectors observed an emergency preparedness drill on August 8, 2024.
- (2) The inspectors observed an emergency preparedness drill on August 27,
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification The inspectors verified Constellation's performance indicators submittals listed below for the period of July 1, 2023 through June 30, 2024:
MS07: High-Pressure Injection Systems (IP Section 02.06)===
- (1) Unit 2, high-pressure injection systems
- (2) Unit 3, high-pressure injection systems
MS08: Heat Removal Systems (IP Section 02.07) (2 Samples)
- (1) Unit 2, heat removal systems
- (2) Unit 3, heat removal systems
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
- (1) Unit 2, RHR systems
- (2) Unit 3, RHR systems
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
- (1) Unit 2, cooling water support systems
- (2) Unit 3, cooling water support systems
===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) Unit common, review of operator response time program and validation of time critical operator actions; information from Operating Experience Smart Sample (OpESS)2023-002 Probabilistic Risk Assessment Configuration Control, was used to inform this sample
- (2) Unit common, review of corrective actions associated with medium voltage cable failures
71153 - Follow-Up of Events and Notices of Enforcement Discretion Event Follow-Up (IP Section 03.01)
- (1) The inspectors evaluated the Unit 2 scram caused by the manual trip of the main turbine in response to degrading main condenser vacuum on July 10,
INSPECTION RESULTS
Minor Performance Deficiency 71152A Operator Action Time Validation Methodology Not Consistent with Probabilistic Risk Assessment
Minor Performance Deficiency: The inspectors performed a review of the completeness and accuracy of Time Critical Operator Actions as specified in OP -PB-102-106, Operator Response Time Program at Peach Bottom. The inspectors reviewed Time Sensitive Action -
30 (OP-PB-102-106 TSA-30) which performs d irect current load shedding in the event of a station blackout (SBO). During the review, the inspectors identified that the validation plan for TSA-30 used a validation methodology not consistent with the associated probabilistic risk assessment (PRA) calculation assumptions.
The station procedure to implement SBO load shedding is SE-11, Attachment T, DC Load Shed.
These actions were validated to ensure that they could be performed within the 60-minute timeframe assumed in the plant PRA. The validated action timeframe as documented in OP-PB-102-106, Operator Response Time Program at Peach Bottom, to perform SE-11, T, is 42 minutes and 14 seconds which is less than the maximum allowable time.
However, Fire PRA PB-PRA-021.59, Revision 1, sequence EHULS-ACDXI2-F, provides a detailed risk assessment of the SE-11, Attachment T, actions that states, Operator action success criterion: Complete the SE-11 Attachment T load shed steps before 60 minutes from the loss of AC power to the battery chargers.
The plant validation performed by Operations in 2018 states that the validation timing starts when the equipment operators are directed to perform the SE-11 actions.
The time assumed in Fire PRA PB-PRA-021.59, Revision 1, sequence EHULS-ACDXI2-F, for delay and cognitive recognition of the SBO, performing the required trip procedures and then directing the appropriate Attachments of SE-11, Loss of Off -Site Power, is 15 minutes. This timeframe was not included in the Operations TSA-30 validation.
Screening: The inspectors determined the performance deficiency was minor. The inspectors determined sufficient time to perform the task successfully exists since validations were performed with one field operator, and the PRA assumes two would be available. Further, adding the unaccounted -for time of 15 minutes to the validated action timeframe of 42 minutes resulted in an operator response time within the allowable 60- minute timeframe assumed in the plant PRA. IR 04802578 was written to address the discrepancy between the PRA calculation assumptions and the validation plan methodology.
Observation: Unit Common, Review of Corrective Actions Associated with 71152A Medium Voltage Cable Failures The inspectors reviewed and evaluated Constellations corrective actions following the failure of several medium voltage cables. In 2018, a conductor in the 'C' phase of the 1 SU bus feeder failed to ground. In 2019, the 'E-1' EDG tripped during routine surveillance testing due to the failure of two conductors on a cable. In 2023, SBO transformer feeder breaker tripped because of a fault in the 'B' phase of the feeder cable. In all three instances, water intrusion was a contributing factor to the failures. These issues were documented in Constellations corrective action program as IR s 4202988, 4252679, and 4667649, respectively.
Constellation identified that cable testing had not been conducted on these cables. The cables were subsequently tested using the Tan Delta method, revealing degradation or failure. Tan Delta is a diagnostic technique that assesses cable insulation quality by applying an alternating current sinusoidal waveform at a frequency of 0.1 Hz to measure real power dissipation (or losses) in the dielectric material. This method is outlined in Constellations Cable Condition Monitoring Program procedure for evaluating cables.
Constellation implemented engineering changes to address cable failures. Specifically, two sections of feeder cables to the 1 SU feed bus were replaced, sourced from the 2 SU and 3 SU switchgears. Following the 2019 EDG cable failure, Constellation identified that planned preventive maintenance cable testing for the EDG cables had been deferred multiple times since 2012. As part of their corrective actions, Constellation replaced the power cables in all four EDGs and reclassified preventive maintenance work requests related to cable testing to require management approval, thereby preventing future deferments.
Cable testing of the SBO line identified several cables with either failures or potential issues.
The SBO line consists of seven cables. Two cables (Cables 6 and 7) were assessed and found to have no impact on the site. Cable 6 passed a withstand test but failed the overall test; it serves as a feed cable to the PECO South Substation and is not under Peach Bottom Atomic Power Stations control. Cable 7 has been abandoned by PECO and it was deemed unnecessary for the station. Two cables (Cables 3 and 5) were replaced in 2023. Cable 2, although it tested satisfactorily, failed the partial discharge test and is scheduled for replacement in 2024. Cable 1, tested in 2019, was identified for further evaluation, necessitating additional testing. It is scheduled for retesting in 2024 using specialized equipment capable of testing approximately nine miles of cable. Cable 4, tested in 2021, indicated a potential issue. It was placed under increased oversight and scheduled for T an Delta testing in 2024. However, a visual inspection in 2024 revealed partial discharge damage at a ground wire connection at the termination. An engineering change request was performed to remove the failed Raychem termination and re-splice the cable with a copper bus bar. The cable subsequently passed the T an Delta test successfully.
The inspectors reviewed engineering change documents, work orders, condition reports, and causal evaluations, and conducted interviews with engineers. As all replaced cables are buried and inaccessible, a walkdown to assess their material condition was not feasible. The original licensee deficiencies were addressed in previous inspections. The inspectors did not identify any findings or violations of more than minor significance during their review of the licensee's corrective actions.
Observation: Verify Completeness and Accuracy of Time Critical Operator Action 71152A Validations The inspectors performed a review of the completeness and accuracy of Time Critical Operator Actions as specified in OP-PB-102-106, Operator Response Time Program at Peach Bottom. Team inspection activities previously noted that validation activities for time critical and time sensitive actions are not always being performed in accordance with the program requirements and consistent with PRA calculations as documented in IR 4673437.
OP-AA-102-106, Operator Response Time Program, requires re-validation to be performed for certain activities every six years. The inspectors noted some re-validations were performed outside this frequency. The licensee generated IR 04802581 to address this issue.
The inspectors reviewed Time Sensitive Action - 30 (OP-PB-102-106 TSA-30) which performs direct current load shedding in the event of a SBO. During the review, the inspectors identified that operator training frequencies assumed in the PRA calculations were not consistent with current operator training task frequency for this task. Specifically, the plant PRA assumed a two-year training frequency for TSA-30 to inform human reliability analysis calculations of human error probability values. Since the last PRA revision, the training frequency has been changed to be performed every six years.
The inspectors noted that processes to inform the PRA staff of changes in credited operator action training frequencies are not clearly controlled. The governing corporate procedures, ER-AA-600- 1015, FPIE (Full Power Internal Event) PRA Model Update, ER-AA-600- 1061, Fire PRA Model Update and Control, and training task frequency change processes do not provide clear direction for the site risk management engineer or model owner to ensure that Operations training changes since the last PRA model update are evaluated for their impact. The licensee subsequently determined the reduction in training frequency in this instance does not change the calculation for the human reliability analysis calculation for human error probability associated with TSA-30. This issue was captured in IR 04806621. Information from OpESS 2023 -002, Probabilistic Risk Assessment Configuration Control, was used to inform this inspection sample.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On October 10, 2024, the inspectors presented the integrated inspection results to Martin Bonifanti, Site Vice President, and other members of the licensee staff.
- On July 19, 2024, the inspectors presented the PI&R medium voltage cables inspection results to Jennifer Krodel, Manager, Engineering, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection Type Designation Description or Title Revision or
Procedure Date
71111.15 Corrective Action IR 4793000
Documents
Miscellaneous Unit 2 Standing Order Log Number: 24-06, Limiting Unit 2
Reactor Power to ~20 Percent until Approved by PORC to
Proceed
1092-0044-LTR-Peach Bottom Steel Sleeve in the HPSW Intake Structure Revision 1
001
71111.24 Work Orders 05221032
221034
71114.06 Corrective Action IR 4797913
Documents IR 4798154
71152A Corrective Action IR 02662656
Documents IR 04202988
IR 04241082
IR 04282775
IR 04667649
IR 04760972
Corrective Action IR 04802578
Documents IR 04802581
Resulting from IR 04806621
Inspection
Drawings E-1 Single Line Diagram Station Revision 60
E-10 Single Line Meter & Relay Diagram Start-up & Emergency Revision 38
Power Systems
Inspection Type Designation Description or Title Revision or
Procedure Date
E-11 Single Lime Diagram Cooling Tower & Screen Structure - Revision 3
13.8KV System
E-12 Single Line Meter & Relay Diagram Standby Diesel Gens & Revision 13
4160 Volt Emer Power System-Unit 3
E-13 Single Line Diagram Remote Miscellaneous Building 13200 Revision 46
V Feeds and Associated 13200 V - 480 V Transformers
Engineering EC 0626878 #1 SU Feed Bus 00A006 Cable Replacement 02/15/2019
Changes EC 0632325 E1 EDG Cables (Exciter to Generator) Replacement 11/24/2021
Miscellaneous PB-PRA-021.5 Fire PRA Human Reliability Analysis Revision 1
PB-PRA-021.59 Fire PRA Human Reliability Analysis Revision 2
PEAM-EPU-124 Revision 2
PEAM-MUR-0903 SBO Revision 0
PMC-19-120892 Cable Condition Monitoring Program: EDG Output to E-Bus 07/18/2024
Cables
PNLO046P NLO JPM for SE-11.1 actions
Report 23-088 Forensic Analysis of A 750 KCMIL AL, 35 KV XLPE Insulated 07/14/2023
Cable Removed from Peach Bottom
Atomic Power Station
TCA-20 - TCOA validation work sheets
20160505 -
Validation
Worksheet
TCA-22 -
210113 -
Validation
Worksheet
TCA-27
20160505 -
Validation
Worksheet
TCA-41 -
240613 - -
Validation
Worksheet
Inspection Type Designation Description or Title Revision or
Procedure Date
Procedures AD-AA-101 Processing of Procedures, T&RMs, and Forms Revision 31
CC-AA-102 Design Input and Configuration Change Impact Screening Revision 35
ER-AA-300-150 Cable Condition Monitoring Program Revision 8
SE 11.1 Operating SBO Line During a Loop Event Revision 9
SE-11 DC Load Shedding Revision 22
T,
SE-11 Sheet 1 Loss of Off-site Power Revision17
SE-17 Main Control Room Atmosphere Non-Radioactive Revision 5
Contamination Procedure
Work Orders 04865134 1 SU Feeder 'C' Phase Differential Lockout 12/14/2018
13