IR 05000483/2024004
| ML25027A299 | |
| Person / Time | |
|---|---|
| Site: | Callaway  (NPF-030) |
| Issue date: | 01/30/2025 |
| From: | Ami Agrawal NRC/RGN-IV/DORS/PBB |
| To: | Diya F Union Electric Co |
| References | |
| IR 2024004 | |
| Download: ML25027A299 (1) | |
Text
January 30, 2025
SUBJECT:
CALLAWAY PLANT - INTEGRATED INSPECTION REPORT 05000483/2024004
Dear Fadi Diya:
On December 31, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Callaway Plant and discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.
One finding of very low safety significance (Green) is documented in this report. This finding involved a violation of NRC requirements. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violation or the significance or severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN:
Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; the Director, Office of Enforcement; and the NRC Resident Inspector at the Callaway Plant.
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 IV; and the NRC Resident Inspector at the Callaway 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 Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely Ami N. Agrawal, Chief Reactor Projects Branch B Division of Operating Reactor Safety Docket No. 05000483 License No. NPF-30
Enclosure:
As stated
Inspection Report
Docket Number:
05000483
License Number:
Report Number:
Enterprise Identifier:
I-2024-004-0006
Licensee:
Union Electric Company
Facility:
Callaway Plant
Location:
Steedman, Missouri
Inspection Dates:
October 1 to December 31, 2024
Inspectors:
N. Brown, Acting Senior Resident Inspector
S. Schwind, Acting Branch Chief
Approved By:
Ami N. Agrawal, Chief
Reactor Projects Branch B
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at the Callaway 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
Failure to Promptly Identify and Correct a Significant Condition Adverse to Quality Regarding Safety -Related Air Conditioning Compressors Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000483/2024004-01 Open/Closed
[P.2] -
Evaluation 71153 The inspectors reviewed a self-revealed Green finding and associated non-cited violation of 10 CFR Part 50 Appendix B, Criterion XVI, Corrective Action, for the licensees failure to promptly identify and correct a significant condition adverse to quality. On August 2, 2024, the licensee concluded that control room air conditioner train A would not have been able to support its 30-day mission time during a period when emergency diesel generator train B had been declared inoperable for planned maintenance. This resulted in a condition prohibited by technical specifications.
Additional Tracking Items
Type Issue Number Title Report Section Status LER 05000483/2024-002-00 LER 2024-002-00 for Callaway Plant, Unit 1,
Concurrent Inoperability of Control Room Air Conditioning System Train and Opposite Train Emergency Diesel Generator Results in Condition Prohibited by Technical Specifications Limiting Conditions for Operation 3.7.11, 3.8.1, and 3.0.3 71153 Closed LER 05000483/2024-001-00 LER 2024-001-00 for Callaway Plant, Unit 1,
Reactor Trip Due to Turbine Trip 71153 Closed
PLANT STATUS
The Callaway Plant began the inspection period at rated thermal power and remained at or near rated thermal power 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)
- (1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal cold weather on November 12, 2024.
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
(1)turbine -driven auxiliary feedwater and auxiliary feedwater system train A during planned maintenance on auxiliary feedwater system train B on October 2, 2024 (2)high head safety injection train B following planned maintenance on November 1, 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)auxiliary feedwater pump rooms on October 1, 2024 (2)turbine building 2000' and 1974' elevation including auxiliary boiler room, fire areas TB-1 and AB-1 on October 16, 2024 (3)auxiliary building 1974' elevation, fire area A-4 on October 29, 2024 (4)intake structure on October 29, 2024 (5)reactor building, elevation 2000', fire area RB-1 on November 6, 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 performance of solid state protection system train B slave relay K634 and K744 surveillance testing and containment spray pump train B surveillance on October 7, 2024, and centrifugal charging pump train B inservice testing on October 18, 2024.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated reactor and secondary off normal operations on November 5, 2024.
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 remain capable of performing their intended function:
(1)failure of PA032811B1, reactor coolant pump A under-frequency relay during surveillance testing on November 14, 2024 (2)hydrogen analyzer B on December 9, 2024
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (2 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
(1)discolored boric acid residue on isolation valve BGV0633 on October 14, 2024 (2)auxiliary building train B negative pressure test on October 14, 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)modification of PA032811B1, reactor coolant pump A under-frequency relay on November 15, 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 (IP Section 03.01) (4 Samples)
- (1) ALHV0020, essential service water to motor -driven auxiliary feed pump valve, stroke time testing and valve position indication testing following planned maintenance on October 2, 2024 (2)motor -driven auxiliary feedwater pump A testing following pump and motor oil change on October 16, 2024 (3)emergency diesel generator A testing following planned maintenance on October 23, 2024
- (4) EFHV0043, train A essential service water to service air compressor A isolation valve testing following planned maintenance on October 23, 2024
Surveillance Testing (IP Section 03.01) (2 Samples)
(1)safety injection pump B surveillance on October 28, 2024
- (2) containment personnel hatch local leak rate testing on November 7, 2024
Inservice Testing (IP Section 03.01) (1 Sample)
- (1) ALV0003, condensate storage tank to motor -driven auxiliary feed pump check valve inservice testing on October 2, 2024
71114.06 - Drill Evaluation
Required Emergency Preparedness Drill (1 Sample)
(1)emergency preparedness 2024 annual ERO drill on October 3,
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01)===
- (1) October 2023 through September 2024 IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (1 Sample)
- (1) October 2023 through September 2024
IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (1 Sample)
- (1) October 2023 through September 2024
MS09: Residual Heat Removal Systems (IP Section 02.08) (1 Sample)
- (1) October 2023 through September 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 issue:
(1)auxiliary building flooding issues on December 31, 2024
71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02)
- (1) The inspectors reviewed the licensees corrective action program to identify potential issues encountered while implementing Maximo software for use in the corrective action program on November 20, 2024.
71153 - Follow Up of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)
The inspectors evaluated the following event reporting determinations to ensure they complied with reporting requirements.
- (1) The inspectors reviewed Licensee Event Report (LER) 2024-001-00 for Callaway Plant, Unit 1, Reactor Trip Due to Turbine Trip (ADAMS Accession No. ML24095A326). The inspectors determined that the cause of the condition described in the LER was not reasonably within the licensee's ability to foresee and correct, and therefore was not reasonably preventable. No performance deficiency or violation of NRC requirements was identified. This LER is Closed.
- (2) The inspectors reviewed LER 2024-002-00 for Callaway Plant, Unit 1, Concurrent Inoperability of Control Room Air Conditioning System Train and Opposite Train Emergency Diesel Generator Results in Condition Prohibited by Technical Specifications Limiting Conditions for Operation 3.7.11, 3.8.1, and 3.0.3 (ADAMS Accession No. ML24275A213). The circumstances surrounding this LER are documented in the Inspection Results section of this report. This LER is Closed.
INSPECTION RESULTS
Observation: The inspectors performed a review of a negative trend in implementation issues associated with new corrective action program software.
71152S The inspectors performed a review of a potential adverse trend in the licensees corrective action program with an emphasis on the implementation of the software suite used to manage their corrective action program. A search for the term Maximo between July and November of 2024 revealed 17 condition reports documenting different software issues after implementation of the new suite. An additional five condition reports during the same period documented issues with processes or procedures after implementation of the new software.
The inspectors considered this to constitute a negative trend in software implementation issues. The licensee concurrently identified a similar trend which they documented in condition report 204407239.
Failure to Promptly Identify and Correct a Significant Condition Adverse to Quality Regarding Safety-Related Air Conditioning Compressors Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000483/2024004-01 Open/Closed
[P.2] -
Evaluation 71153 The inspectors reviewed a self-revealed Green finding and associated non-cited violation of 10 CFR Part 50 Appendix B, Criterion XVI, Corrective Action, for the licensees failure to promptly identify and correct a significant condition adverse to quality. On August 2, 2024, the licensee concluded that control room air conditioner A would not have been able to support its 30-day mission time during a period when emergency diesel generator train B had been declared inoperable for planned maintenance. This resulted in a condition prohibited by technical specifications.
Description:
On August 2, 2024, the oil pump drive segment within the compressor for the control room air conditioning system (CRACS) train A unit was replaced to address a material issue. Based on review of the removed part and unit operation prior to its replacement, the licensee concluded that CRACS train A would have failed to support its 30-day mission time starting on June 29, 2024. From July 8-18, emergency diesel generator (EDG) train B was out of service for planned maintenance. Technical Specification (TS) 3.8.1, AC Sources - Operating, requires features supported by an inoperable EDG to be declared inoperable when the required redundant features are inoperable. With CRACS train A and EDG train B concurrently inoperable, CRACS train B would also be inoperable. As such, both CRACS trains were inoperable during the period of EDG train B inoperability, placing the plant in a condition prohibited by technical specifications.
Both trains of CRACS (SGK04A/B) as well as both trains of class 1E switchgear room cooling (SGK05A/B) use Carlyle/Carrier model 06E9299610 compressors. Between April 11, 2021, and July 5, 2024, five of these compressors failed due to a loss of lubrication.
According to the vendor manual, loss of lubrication could be caused by one of three issues:
1) a material defect in the oil pump drive segment, 2) electrical issues causing surges on the motor and leading to oil pump wear, or 3) issues with the thermal expansion valves causing refrigerant flood-back resulting in oil pump component wear. Each of the failed compressors showed excessive wear of the oil pump drive segment. Following the first of these failures, the licensee refuted electrical issues due to satisfactory testing. They also ruled out a material defect with the oil pump drive segment even though they observed excessive wear on the part. This conclusion was based on a hardness test of a spare part compared to the hardness of the failed component. The spare part that was tested was also not properly heat treated so the test did not provide an adequate basis for this conclusion. Left with only the thermal expansion valves in question, they established corrective actions to rebuild or replace these valves in all four units. It was not until the failure of SGK04B on May 24, 2024, and subsequent discussions with the vendor, that the licensee determined the actual failure mechanism was the oil pump drive segment due to improper heat treatment which rendered the part too soft. The vendor indicated that this issue existed in compressors manufactured within a date range which encompassed those purchased by the licensee.
Corrective Actions: Based on this information, the licensee replaced the oil pump drive segment in all four compressors with parts that were appropriately heat treated and had the correct hardness. In addition, they conducted a root cause investigation to determine why their organization did not identify the failure mechanism sooner.
Corrective Action References: Condition Report 202403828
Performance Assessment:
Performance Deficiency: The failure to promptly identify and correct a significant condition adverse to quality is a performance deficiency. It is a performance deficiency because it was reasonably within the licensees ability to identify and correct the condition prior to additional equipment failures.
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 availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, failure to promptly identify and correct the compressor failure mechanism resulted in five compressor failures over a four-year period.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined that the finding had very low safety significance (Green) because the finding did not represent an actual loss of the probabilistic risk assessment function provided by these four air conditioning units.
Cross -Cutting Aspect: P.2 - Evaluation: The organization thoroughly evaluates issues to ensure that resolutions address causes and extent of conditions commensurate with their safety significance. Specifically, the licensee had indications of material issues with the oil pump drive segments yet failed to adequately evaluate them and take corrective actions.
Enforcement:
Violation: Title 10 CFR 50, Appendix B, Criterion XVI, Corrective Action, requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected.
Contrary to the above, the licensee failed to determine and correct the cause of recurring failures of safety related air conditioner compressors due to inadequate heat treatment of the oil pump drive segment. Specifically, from April 11, 2021, until May 24, 2024, five compressors failed, and all five compressors showed signs of premature wearing of the oil pump drive segment.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On January 13, 2025, the inspectors presented the integrated inspection results to F.
Diya, Senior Vice President and Chief Nuclear Officer, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
OTN-QJ-00003
Plant Freeze Protection Heat Tracing Procedure
Work Orders
Job
23512782
Checklist 1
Train A Auxiliary Feedwater Valve Inservice Test
Checklist 1
Turbine Driven Auxiliary Feedwater Valve Inservice Test
Procedures
OTN-BG-00001,
Checklist 2
Letdown and Charging Valve Lineup
Fire Preplan Manual
OTO-KC-00001,
Addendum A-13
Auxiliary Building 2000' - Auxiliary Feedwater Pump Room B
OTO-KC-00001,
Addendum A-14
auxiliary building 2000' - auxiliary feedwater pump room A
Procedures
OTO-KC-00001,
Addendum A-15
auxiliary building 2000' - turbine-driven auxiliary feedwater
pump room
Miscellaneous
T61.0810 8 LOCT 24-6
Solid State Protection System Train B Relay K634 and K744
Test
Centrifugal Charging Pump A Inservice Test - Group B
Procedures
Train B Containment Spray Pump Inservice Test
Work Orders
Job
24501273, 23500771, 23502284, 24507414
Corrective Action
Documents
Condition Reports
2404258, 202400036, 202402041, 202403268,
2208484, 202404259
Work Orders
Jobs
24509201, 24002825, 21510700
Corrective Action
Documents
Condition Reports
2406532, 202406531
EDP-ZZ-01004
Boric Acid Corrosion Control Program
EDP-ZZ-04107
HVAC Pressure Boundary Control
Auxiliary Building Train A Negative Pressure Test
Procedures
Auxiliary Building Train B Negative Pressure Test
Work Orders
Jobs
21510700
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
Condition Reports
201606730, 201607365
ABB Power T&D Co. Instruction Leaflet for Type MDF
Microprocessor Frequency Relay
05/01/1992
Miscellaneous
MP 16-0038
Replacement Underfrequency Relay for Reactor Coolant
Pump Motor
Work Orders
Job
16005731
Corrective Action
Documents
Condition Reports
2406655
APA-ZZ-00322,
Appendix E
Post-Maintenance Test Program
Containment Leakage Rate Testing Program
Containment Personnel Access Hatch and Emergency
Access Hatch Door Seal Leak Rate Test
Motor Driven Auxiliary Feedwater Pump A Inservice Test -
Group A
Train B Auxiliary Feedwater Valve Inservice Test
Essential Service Water Train A Valve Operability
Safety Injection Train B Inservice Test - Group B
Procedures
Standby Diesel Generator A Periodic Tests
Work Orders
Job
23502760, 21508696, 19511335, 24508219, 21001452,
24509751
Miscellaneous
Emergency Preparedness 2024 Annual DRO Drill Scenario
Performance Indicator Data for Unplanned Scrams between
October 2023 and September 2024
Performance indicator data for scrams with complications
between October 2023 through September 2024
Performance indicator data for unplanned power changes
between October 2023 through September 2024
71151
Miscellaneous
Performance Indicator Data for Unplanned Power Changes
Between October 2023 through September 2024
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
Condition Reports
24405185, 2024405274, 202405313, 202405400,
2405400, 202405491, 202405516, 202405517,
2405528, 202405542, 202405544, 202405815,
2405855, 202405954, 202406017, 202406165,
2406282, 202406886, 202407076, 202407086,
2407107, 202407135