IR 05000373/2024003
| ML24310A076 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/06/2024 |
| From: | Nestor Feliz-Adorno NRC/RGN-III/DORS/RPB1 |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| References | |
| IR 2024003 | |
| Download: ML24310A076 (1) | |
Text
SUBJECT:
LASALLE COUNTY STATION - INTEGRATED INSPECTION REPORT 05000373/2024003 AND 05000374/2024003
Dear David Rhoades:
On September 30, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at LaSalle County Station. On October 9, 2024, the NRC inspectors discussed the results of this inspection with John VanFleet, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.
Two findings of very low safety significance (Green) are documented in this report. Two of these findings involved violations of NRC requirements. We are treating these violations as non-cited violations (NCVs) consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violations or the significance or severity of the violations 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 III; the Director, Office of Enforcement; and the NRC Resident Inspector at LaSalle County Station.
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 III; and the NRC Resident Inspector at LaSalle County Station.
November 6, 2024 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, Néstor J. Féliz Adorno, Chief Reactor Projects Branch 1 Division of Operating Reactor Safety Docket Nos. 05000373 and 05000374 License Nos. NPF-11 and NPF-18
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000373 and 05000374
License Numbers:
Report Numbers:
05000373/2024003 and 05000374/2024003
Enterprise Identifier:
I-2024-003-0061
Licensee:
Constellation Nuclear
Facility:
LaSalle County Station
Location:
Marseilles, IL
Inspection Dates:
July 01, 2024, to September 30, 2024
Inspectors:
M. Abuhamdan, Reactor Inspector
J. Benjamin, Senior Resident Inspector
T. Iskierka-Boggs, Senior Operations Engineer
J. Meszaros, Resident Inspector
N. Shah, Senior Project Engineer
Approved By:
Néstor J. Féliz Adorno, Chief
Reactor 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 LaSalle County Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations
Failure to Ensure That No Floatable Material Could Migrate Towards Floor Drains in Areas Containing Safety-Related Equipment Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000373/2024003-01 Open/Closed
[P.3] -
Resolution 71111.06 The resident inspectors identified a finding of very low safety significance (Green) and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion V,
Instructions, Procedures, and Drawings, for the licensees failure to ensure that no floatable materials in the Unit 1A residual heat removal (RHR) pump room could migrate towards floor drains. Specifically, a bin containing used personal protective equipment (PPE) was overflowing with loose floatable items.
Failure to Verify Proper Breaker Operation Results in an Undetected Misaligned Mechanically Operated Contact Switch Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000373,05000374/2024003-02 Open/Closed
[H.12] - Avoid Complacency 71152A A self-revealed finding of very low safety significance (Green) and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified for the licensees failure to verify proper breaker operation in accordance with an approved work package. The licensee failed, as a result, to identify linkage misalignment on the Unit 1 air circuit breaker (ACB) 1422 mechanically operated contact (MOC) switch that occurred during maintenance. The misaligned linkage rendered the alternate Unit 2, division 2 qualified alternating current (AC) electrical circuit inoperable for approximately 1 year.
Additional Tracking Items
Type Issue Number Title Report Section Status LER 05000373,05000374/2023
-002-00 LER 2023-002-00 for LaSalle County Station,
Units 1 & 2, Air Circuit Breaker (ACB) Mechanically Operated Contacts (MOC)
Switch Failed to Actuate 71153 Closed
PLANT STATUS
Unit 1 began the inspection period at rated thermal power. On September 1, 2024, the unit was down powered to approximately 86 percent power to perform a control rod pattern adjustment and was restored to full power later that day. On September 28, 2024, the unit was down powered to approximately 60 percent power for a control rod pattern adjustment. The unit was restored to full power on September 29, 2024, and remained at rated thermal power for the remainder of the inspection period.
Unit 2 began the inspection period at rated thermal power. On July 15, 2024, the unit was down powered to approximately 93 percent following an unplanned 2A circulating water pump trip. The unit was returned to full power on July 16, 2024. On September 7, 2024, the unit was down powered to approximately 73 percent power for a control rod pattern adjustment. The unit was returned to rated thermal power on September 8, 2024, and remained at 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
71111.04 - 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) Unit common emergency diesel generator following surveillance testing run on August 6, 2024
- (2) Unit 2 reactor core isolation cooling system following August 29, 2024, surveillance testing
Complete Walkdown Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated system configurations during a complete walkdown of the Unit 1 core standby cooling system and equipment cooling water system July 23 thru 25, 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) Fire Zone 5D1, turbine building, elevation 687'-0", Unit 1 high pressure core spray switchgear area on August 7, 2024
- (2) Fire Zone 5D2, turbine building, elevation 687'-0", Unit 2 high pressure core spray switchgear area on August 8, 2024
- (3) Fire Zone 2H1, reactor building, elevation 694'-6", Unit 1 general area on September 23, 2024
- (4) Fire Zone 2G, reactor building, elevation 710'-6", Unit 1 general area and suppression pool entrance on September 23, 2024
- (5) Fire Zone 3B1, reactor building, elevation 820'-6", Unit 2 general area and standby gas treatment system on September 23, 2024
Fire Brigade Drill Performance Sample (IP Section 03.02) (2 Samples)
- (1) The inspectors evaluated the onsite fire brigade training and performance during an announced fire drill at the Unit 1 main power transformer on July 25, 2024.
- (2) The inspectors evaluated the onsite fire brigade training and performance during an unannounced fire drill at Unit 2 232X bus on September 25, 2024.
71111.06 - Flood Protection Measures
Flooding Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated internal flooding mitigation protections in the Unit 1A residual heat removal pump corner room.
71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance
Requalification Examination Results (IP Section 03.03) (1 Sample)
- (1) The inspectors reviewed and evaluated the results of the requalification operating exam administered on October 1, 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) (2 Samples)
- (1) The inspectors observed and evaluated licensed operator performance in the control room during a Unit 1 turbine lube oil heat exchanger swap on August 8, 2024.
- (2) The inspectors observed and evaluated licensed operator performance in the control room during Unit 1 down power for a planned rod pattern adjustment on September 28, 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 August 6, 2024.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (4 Samples)
(1)periodic evaluation of maintenance rule program (2)station 'A' and 'B' train fire pumps
- (3) Unit 1 failed fuel and associated monitoring and conditioning plan (4)failure of the Unit 1 1412 air circuit breaker to facilitate fast transfer from the station auxiliary transformer to the unit auxiliary transformer on April 20, 2024
Aging Management (IP Section 03.03) (1 Sample)
- (1) Unit 2 drywell coating inspections performed during outage L1R20 under license renewal commitment 016032204-36-04
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (1 Sample)
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) July 8, 2024 - Unit 2 Action Green - hot weather grid alert with out of service (OOS)service water pump
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (6 Samples 1 Partial)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
- (1) Unit 1 residual heat removal (RHR) and Unit 2 RHR and low-pressure core spray water leg pumps operability with ball bearings lacking evidence of critical characteristic inspection during commercial grade dedication, as documented in Action Requests (ARs) 4786376, 4786379, and 4786380 (2)10 CFR 50 Part 21 Report: RSCC wire and cable LLC insulated conductor non-compliance - failure of insulation tensile and elongation at break test following air over aging
- (3) AR 4795718, Unit 2 Suppression Pool Level Lowering
- (4) AR 4796010, 1A Emergency Diesel Generator Air Compressor Degraded (5)
(Partial)
AR 4797522, Unit 2 Reactor Core Isolation Cooling Flow Controller Degraded in Both Manual and Automatic Control Modes
- (6) Westinghouse 10 CFR Part 21 notification dated July 21, 2024, related to control rod blade 3-CR 99 CRB wing separation and cracking
- (7) AR 4801891, 1B DG A HDR Starting Air Press at Rounds Minimum
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)temporary modification Engineering Change (EC) 405948 to increase cooling to the reactor recirculation #1 and #2 seals
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) (3 Samples)
- (1) Unit 1A service water pump per LOP-WS-02 after rebuild maintenance on July 3, 2024
- (2) Unit 1 division 3 emergency cooling water pump PMT on September 17, 2024, after planned work window
- (3) Unit 2 instrument nitrogen compressor week of September 23, 2024 (AR 4791947 and WR 1551035)
Surveillance Testing (IP Section 03.01) (1 Sample)
- (1) Unit 1A RHR system operability and response time testing per LOS-RH-Q1 on September 30, 2024
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
- (1) Unit 1 1B standby liquid control pump in-service test on September 12, 2024
Diverse and Flexible Coping Strategies (FLEX) Testing (IP Section 03.02) (1 Sample)
- (1) FLEX diesel generator run on July 18, 2024, per LOS-FSG-SR1
71114.06 - Drill Evaluation
Additional Drill and/or Training Evolution (1 Sample)
The inspectors evaluated:
(1)performance indicator drill with technical support center/outage support center participation on September 4,
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
MS06: Emergency AC Power Systems (IP Section 02.05)===
- (1) Unit 1 (July 1, 2023, through June 30, 2024)
- (2) Unit 2 (July 1, 2023, through June 30, 2024)
MS07: High Pressure Injection Systems (IP Section 02.06) (2 Samples)
- (1) Unit 1 (July 1, 2023, through June 30, 2024)
- (2) Unit 2 (July 1, 2023, through June 30, 2024)
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
- (1) Unit 1 (July 1, 2023, through June 30, 2024)
- (2) Unit 2 (July 1, 2023, through June 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) The inspectors evaluated the licensee response to failure of the Unit 1 division 2 crosstie (ACB 1424) to close on February 24, 2023, as documented in AR 4557105.
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 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) Licensee Event Report (LER) 05000373, 05000374/2023-002-00, LaSalle County Stations Unit 1 & 2, Air Circuit Breaker (ACB) Mechanically Operated Contacts (MOC) Switch Failed to Actuate (ADAMS Accession No. ML23115A157). The inspection conclusions associated with this LER are documented in this report under the Inspection Results section. This LER is closed.
INSPECTION RESULTS
Failure to Ensure That No Floatable Material Could Migrate Towards Floor Drains in Areas Containing Safety-Related Equipment Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000373/2024003-01 Open/Closed
[P.3] -
Resolution 71111.06 The resident inspectors identified a finding of very low safety significance (Green) and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for the licensees failure to ensure that no floatable materials in the Unit 1A residual heat removal (RHR) pump room could migrate towards floor drains. Specifically, a bin containing used personal protective equipment (PPE) was overflowing with loose floatable items.
Description:
On July 25, 2024, the resident inspectors observed a bin used to hold used PPE at the exit of a marked contaminated area in the Unit 1A RHR pump room. The bin was overflowing with PPE, including rubber gloves and anti-contamination clothing comprising of fabric. The resident inspectors brought the overflowing bin to the attention of the shift manager that same day. The resident inspectors followed up on the state of the bin on August 27, 2024, and again observed that it was overflowing.
The Unit 1A RHR pump room contains a pump as well as instruments and controls that could be rendered inoperable by flooding in the room. These components are integral to the safety-related low pressure coolant injection (LPCI) function of the 'A' RHR system. The LPCI function is credited in the Updated Final Safety Analysis Report (UFSAR) for mitigating the consequences of a postulated loss of coolant accident (LOCA).
The room is below-grade in a flood-controlled area within the reactor building. UFSAR section 3.4.1 states that flood-controlled areas can be flooded via large internal sources of water (e.g., the suppression pool or service water lines connected to the cooling lake) and describes flood protection measures for safety-related systems, structures, and components (SSCs) located in such areas. Per the UFSAR, flood protection measures include floodwalls/bulkhead doors to keep floodwater sources contained, an alarm and indication system for key sumps, and the formulation of abnormal operating procedures for station operators to use when responding to indications of flooding.
A 1550-gallon sump is located at the floor level in the Unit 1A RHR pump room. The sump is covered but is not leak-tight. Two floor drains in the room are also available to transport water to the sump during a hypothetical flooding event. During such an event, a control room alarm alerts operators to the condition of flood water in the room once water level in the sump reaches a predefined hi-hi level as measured by installed switches. Operators would then respond to stop the source of the flood.
The resident inspectors toured the Unit 1A RHR pump room and noticed that a 20-inch RHR service water line traverses over a bin used to hold used PPE. The bin is also located within 5 feet of one of two floor drains located in the room. The resident inspectors were concerned that a hypothetical break of this line could wash away loose floatable material overflowing the bin. The contents could block the nearby floor drain, impact the flow of floodwater to the sump, delay the associated hi-hi sump level control room annunciator and, thus, delay operator action to terminate pump room flooding prior to impacting safety-related equipment.
The other floor drain in the pump room was located behind a caged area such that it would be less likely to be blocked by floatable material from the overflowing bin.
Internal flooding analyses identify a 20-minute maximum allowable time for operator action to identify and isolate a postulated leak in the room. The analyses also note that the maximum leak rate associated with such a piping failure should result in a sump alarm within 1 minute.
At the time of this inspection, the licensee did not have a technical basis for the extent to which one blocked floor drain in the Unit 1A RHR pump room would impact the time to a sump alarm and subsequent operator action.
The licensee established procedure LAP-100-56, revision 11, Equipment/Parts Storage in Plant Areas Containing Safety-Related Equipment, to address flood-controlled area material storage. This procedure says, loose floatable items shall not be stored in flood-controlled areas. The definition of loose floatable items in LAP-100-56 includes items comprised primarily of fabric, foam, paper, plastic, rubber, or wood. While this procedure allows placing these items in permanent storage containers provided by Radiation Protection, such as the overflowing bin, the overflowing material was considered loose since it was not secured inside the bin. Similarly, procedure MA-AA-716-026, revision 22 Station Housekeeping/Material Condition Program, states ENSURE no floatable materials in lower elevations of reactor/turbine building(s) that could migrate towards floor drain(s).
Corrective Actions: The licensee emptied the overflowing bin on August 28, 2024. On September 30, 2024, the licensee documented the resident inspectors concerns in the corrective action system.
Corrective Action References: AR 4805518
Performance Assessment:
Performance Deficiency: The licensees failure to ensure that no floatable materials in the Unit 1A RHR pump room could migrate towards floor drains was contrary to procedures LAP-100-56 and MA-AA-716-026 and was a performance deficiency.
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 failure to ensure that no floatable materials in the Unit 1A RHR pump room could migrate towards floor drains does not ensure the availability of the Unit 1A RHR system to respond to initiating events because it had the potential to block one of two sump drains during a postulated internal flood. Also, the licensee did not have a technical basis at the time of the inspection demonstrating that one of two blocked drains would not impact the operator response time to an internal flooding event.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The resident inspectors used Exhibit 2, Section B, External Event Mitigating Systems, and were routed to Exhibit 4 because the finding involved the degradation of equipment specifically designed to mitigate flooding for greater than 14 days by having the potential to impact one of two floor drains in the Unit 1A RHR corner room. The finding screened as having very low safety significance (Green) because all questions in Exhibit 4 were answered no.
Cross-Cutting Aspect: P.3 - Resolution: The organization takes effective corrective actions to address issues in a timely manner commensurate with their safety significance. Specifically, the licensee did not take corrective action until the inspectors noted the condition continued to exist approximately a month after it was first identified.
Enforcement:
Violation: Title 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, states that: Activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures, or drawings.
Procedure LAP-100-56, revision 11, Equipment/Parts Storage in Plant Areas Containing Safety-Related Equipment, states loose floatable items shall not be stored in flood-controlled areas. LAP-100-56 defines floatable items as items comprised primarily of fabric, foam, paper, plastic, rubber, or wood. Procedure MA-AA-716-026, Rev. 22, Station Housekeeping/Material Condition Program, states ENSURE no floatable materials in lower elevations of reactor/turbine building(s) that could migrate towards floor drain(s).
Contrary to the above, since at least July 25, 2024, to August 28, 2024, the licensee failed to accomplish an activity affecting quality in accordance with procedures. Specifically, the licensee stored loose floatable items in the Unit 1A RHR pump room, a flood-controlled area, contrary to procedure LAP-100-56. A bin used to hold used PPE was overflowing with loose floatable items, including rubber gloves and anti-contamination clothing comprising of fabric.
Additionally, the licensee failed to ensure that the overflowing floatable material could not migrate towards a floor drain, which was contrary to MA-AA-716-026. The pump room in question is in a lower elevation of the reactor building and contains safety-related SSCs such as the 'A' RHR pump and motor as well as instrument and control equipment.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
Failure to Verify Proper Breaker Operation Results in an Undetected Misaligned Mechanically Operated Contact Switch Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000373,05000374/2024003-02 Open/Closed
[H.12] - Avoid Complacency 71152A A self-revealed finding of very low safety significance (Green) and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified for the licensees failure to verify proper breaker operation in accordance with an approved work package. The licensee failed, as a result, to identify linkage misalignment on the Unit 1 air circuit breaker (ACB) 1422 mechanically operated contact (MOC) switch that occurred during maintenance. The misaligned linkage rendered the alternate Unit 2, division 2 qualified alternating current (AC) electrical circuit inoperable for approximately 1 year.
Description:
On February 24, 2023, the licensee performed surveillance testing on ACB 2424, which serves as the Unit 2, division 2 tie breaker. During this test, the Unit 1, division 2 tie breaker, ACB 1424, failed to close. The licensee performed troubleshooting and determined that the issue was caused by a misalignment in the linkage of a MOC switch tied to the Unit 1, division 2 system auxiliary transformer (SAT) circuit breaker, ACB 1422. This MOC switch provides position indication (i.e., open/closed) of ACB 1422 to other breaker logic systems, including ACB 1424. Due to the misalignment, the contacts on the ACB 1422 MOC switch that are normally closed when the breaker is in the closed position were not making contact. This impacted the closing circuit of ACB 1424, preventing its closure during testing.
Further investigation by the licensee revealed that this condition had existed since March 5, 2022, when corrective maintenance was last performed that could have affected the MOC switch. As documented in AR 4482708, the licensee was aligning SAT feed breakers when they determined they were unable to close the breaker via the local control switch. The work package developed to repair the control switch issue (i.e., Work Package 5236695)included steps to perform troubleshooting, replacement of the local control switch, and adjustment of the test switch control (TSC). Although the work package included a step to verify proper breaker operation per Attachment 1 of LES-GM-103D, Bus I.T.E. Breaker and TSC Switch Operational Test, Rev. 11, this step was marked N/A. Steps 12 and 14 of the attachment required a visual inspection of the MOC switch contacts to ensure proper engagement. The omission of this verification step led to the oversight of the misalignment of the MOC switch linkage before declaring the breaker operable.
Step 4.8.4 of procedure MA-AA-716-011, revision 27, Work Execution & Close Out, specifies that certain changes, including those involving safety-related components or PMT, cannot be made in the field as minor. If a change impacts these items, the procedure states that work shall not CONTINUE until the Work Package has been UPDATED by Planning and reviewed by either a Planning Supervisor or a First-line Supervisor and approved by a Senior Reactor Operator (SRO). In this case, the step included in the work package to perform LES-GM-103D, was marked N/A in the field. However, work continued despite this change not being reviewed by either the planning or first-line supervisor and approved by an SRO before this change in work scope.
Step 4.2.4 of procedure MA-AA-716-012, revision 26, Post Maintenance Testing, further states that post maintenance testing shall be performed following any corrective maintenance activities. Step 4.2.2 notes that a satisfactory test verifies a particular component or system is able to perform its intended function, the original deficiency has been corrected, and no new or related problems were created by the maintenance activity or configuration change. Because LES-GM-103D was not completed as planned, the licensee failed to verify that no new or related problems were created by the corrective maintenance activity.
Corrective Actions: The licensee implemented corrective actions to address the ACB 1422 MOC switch misalignment and completed the surveillance prior to exiting the 2023 Unit 2 outage.
Corrective Action References: ARs 4482708, 4557105, 4780035, 1214832, and 1546110
Performance Assessment:
Performance Deficiency: The failure to verify proper breaker operation in accordance with the approved work package was contrary to licensee procedures MA-AA-716-011 and MA-AA-716-012 and was a performance deficiency.
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 licensees failure to verify proper breaker operation in accordance with the approved work package allowed misalignment of the ACB 1422 MOC switch linkage to go undetected. This resulted in the inability of ACB 1424 to close on demand, and the unavailability of the Unit 2 division 2 alternate qualified AC circuit, which is credited to support mitigating systems, for approximately 1 year.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process for Findings At-Power, dated January 1, 2021. The inspectors answered Question 3 of Exhibit 2, Mitigating Systems Screening Questions, YES because the degraded condition represents a loss of the PRA function of one train of a multi-train TS system for greater than the allowed Technical Specification outage time. Since this question was answered YES, a detailed risk evaluation was required.
A senior reactor analyst performed a detailed risk evaluation using SAPHIRE version 8.2.10, the LaSalle SPAR model version 8.82, and results from the licensees fire probabilistic risk assessment (PRA) model to assess the significance of the finding. The following assumptions and factors were considered in the quantification:
- The exposure time for the finding was 355 days.
- The finding resulted in ACB 1424 being non-functional when energized from the Unit 1 system auxiliary transformer but was available when powered from the Unit 1 diesel generator due abnormal operating procedure actions to place jumpers that remove the degraded condition from the ACB 1424 control logic.
- Credit was given for the hardened containment vent system (HCVS) and for diverse and flexible coping strategies (FLEX).
- Common cause failure was considered as a result of the finding.
- No recovery probabilities were applied.
The resultant change in core damage frequency was estimated to be less than 1E-6/year.
Therefore, the finding was determined to be of very low safety significance (Green). The change in large early release frequency (LERF) was evaluated in accordance with IMC 0609, Appendix H, and was determined to be of very low safety significance (Green). The dominant core damage sequences were driven by fire and included high energy arc fault events originating from the 6.9 kV balance of plant bus in the division 1 switchgear room of the auxiliary building. These events involved a fire-induced loss of offsite power due to damage of switchyard control power cables, failure of division 1 emergency core cooling and reactor core isolation cooling systems due to fire damage, failure of emergency power systems, and late failure of high-pressure core spray leading to core damage. Core damage sequences for internal events included a switchyard centered loss of offsite power with a failure of emergency power systems, failure of high-pressure injection, and failure to recover power sources within 30 minutes, leading to core damage.
Cross-Cutting Aspect: H.12 - Avoid Complacency: Individuals recognize and plan for the possibility of mistakes, latent issues, and inherent risk, even while expecting successful outcomes. Individuals implement appropriate error reduction tools. Specifically, the licensee did not recognize for the possibility of mistakes being introduced by their choice of not verifying proper breaker operation as originally planned.
Enforcement:
Violation: 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, states that Activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures, or drawings.
Procedure MA-AA-716-011, revision 27, Work Execution & Close Out, outlines requirements for work scope changes during execution. Step 4.8.4 specifies that certain changes, including those involving safety-related components, cannot be made in the field as minor. If a change impacts these items, the procedure states that work shall not CONTINUE until the Work Package has been UPDATED by Planning and reviewed by either a Planning Supervisor or a First-line Supervisor and approved by a Senior Reactor Operator (SRO).
Procedure MA-AA-716-012, revision 26, Post Maintenance Testing, outlines requirements for PMT. Step 4.2.4 states that post maintenance testing shall be performed following any corrective maintenance activities. Step 4.2.2 notes that a satisfactory test verifies a particular component or system is able to perform its intended function, the original deficiency has been corrected, and no new or related problems were created by the maintenance activity or configuration change.
The licensee established Work Package 5236695 to provide instructions to repair various components associated with the ACB 1422 breaker cubicle. It included a step to perform 1 of LES-GM-103D, Bus I.T.E. Breaker and TSC Switch Operational Test, revision 11. Steps 12 and 14 of the attachment required a visual inspection of the MOC switch contacts to ensure proper engagement.
Contrary to the above, on March 5, 2022, the licensee failed to accomplish an activity affecting quality in accordance with documented instructions and procedures. Specifically, the licensee did not verify proper breaker operation per Attachment 1 of LES-GM-103D as required by Work Package 5236695. Instead, the licensee marked the step as N/A. Work continued without this work scope change being updated into the work package by Planning and reviewed by either a Planning Supervisor or a First-line Supervisor and approved by an SRO as required by MA-AA-716-011. The licensee also failed to verify no new or related problems were created by the corrective maintenance activity on the ACB 1422 breaker cubicle, as required by MA-AA-716-012. Consequently, the licensee did not visually inspect the MOC switch contacts to ensure proper engagement allowing a misalignment of the ACB 1422 MOC switch linkage to go undetected. This resulted in the inability of ACB 1424 to close on demand, and the unavailability of the Unit 2 division 2 alternate qualified AC circuit for approximately 1 year.
As a result of the misaligned MOC switch, the following Technical Specification (TS) were not met:
- TS 3.8.1, AC Sources-Operating, requires two qualified circuits between the offsite transmission network and the onsite Class 1E AC electric power distribution system.
When one required offsite circuit inoperable, Condition A requires, in part, that the circuit is restored to operable within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Additionally, Condition E requires that when both a required qualified circuit and a division 1, 2 or 3 EDG are inoperable, either the qualified circuit or the division 1, 2, or 3 EDG be restored within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. If these required actions of either Condition A or E are not met within the specified time(s), Condition H requires Unit 2 to be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Contrary to this, between March 5, 2022, and February 23, 2023, the licensee failed to have two qualified circuits between the offsite transmission network and the onsite Class 1E AC electric power distribution system and failed to meet the required actions of Conditions A and H. Specifically, since the alternate qualified circuit is normally supplied via the opposite unit SAT via a unit crosstie and unit tie breakers and ACB 1424 could not be closed due to the misaligned MOC switch linkage, one of the two qualified circuits for Unit 2, division 2 was inoperable for approximately 1 year. In addition, there were seven work periods when both a required qualified circuit and an EDG were inoperable, and the licensee failed to meet the required actions of Conditions E and H.
These work periods ranged from approximately 0.75 to 5 days and occurred within the timeframe that Condition A and H were not met.
- TS 3.3.8.1, Loss of Power (LOP) Instrumentation, states The LOP instrumentation for each Function in Table 3.3.8.1-1 shall be OPERABLE. With one or more channels inoperable, Condition A requires that the inoperable channel be placed in trip within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. If Condition A is not met within the associated completion time, Condition B requires that the associated emergency diesel generator (EDG) be declared inoperable immediately. Contrary to this, on March 18, 2022, the licensee failed to have the LOP instrumentation for each function in Table 3.3.8.1-1 operable and to meet the required actions of Conditions A and B. Specifically, the ACB 1422 MOC switch provides a permissive to enable the degraded voltage protection for the Unit 1, division 2 EDG, which is a function included in Table 3.3.8.1-1. There was an approximately 3-hour surveillance on March 18, 2022, during which this degraded voltage function was inoperable due to the licensees alignment of AC power during the surveillance. This AC power alignment caused the degraded condition (i.e., the misaligned MOC switch) to impact the Unit 1, division 2 EDG degraded voltage function. However, the channel was not tripped and the associated EDG not declared inoperable.
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 October 9, 2024, the inspectors presented the integrated inspection results to John VanFleet, Site Vice President, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
Service Water Tunnel Condition (2SW01AA)
01/30/2024
NRC Identified Degraded Insulation
07/25/2024
NRC ID: Valve 1FC040B Norm. Pos. Does Not Match Dwg.
M-87
07/25/2024
NRC ID: Damaged Insulation Downstream of Valve
1FC045B
07/25/2024
NRC ID: Corrosion Inside 1C RHR SW Pump Casing
07/25/2024
NRC ID: Valve 1E22-F319 Position Indication Offscale
07/25/2024
Corrective Action
Documents
Resulting from
Inspection
NRC ID'd - Div 1 FC EMU Pump Support Base Corroded
07/26/2024
M-87, Sheet No.
P & ID Core Standby Cooling System Equipment Cooling
Water System
BT
M-87, Sheet No.
P & ID Core Standby Cooling System Equipment Cooling
Water System
BL
Drawings
M-87, Sheet No.
P & ID Core Standby Cooling System Equipment Cooling
Water System
T
LOP-DG-03M
Unit 0 Diesel Generator Mechanical Checklist
Procedures
LTS-600-19
Corbicula and Zebra Mussel Inspections
EWP MM (LR) Inspect South End of WS Tunnel for
Corbicula & Silt
01/30/2024
LRA OP LOS-RH-Q1 U1 A RHRWS Inservice Test Att 1D
07/02/2024
OP LOS-DG-Q3 U1 HPCS DG Cooling Water Pump Att A5
07/22/2024
LRA OP LOS-RH-Q1 U1 B RHRWS Inservice Test Att 1E
06/25/2024
OP LOS-DG-Q2 Att A5: 1A DG CWP Inservice Test
07/29/2024
Work Orders
OP LOS-DG-Q1 0 DG CWP In Service Test Att A5
08/06/2024
NRC Identified Pre-Fire Plan Change Needed
08/08/2024
Corrective Action
Documents
Resulting from
Inspection
NRC Identified Fire Report Discrepancy
08/14/2024
FZ 2G
RX Bldg. 710-6 Elev. U1 General Area and Suppression
Pool Entrance
003
Fire Plans
FZ 2H1
RX Bldg. 694-6 Elev. U1 General Area
003
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
FZ 3B1
RX Bldg. 820-6 Elev. U2 General Area and SBGTS Area
003
FZ 5D1
TB. Bldg. 687'-0" Elev. U1 HPCS Switchgear Area
003
FZ 5D2
TB. Bldg. 687'-0" Elev. U2 HPCS Switchgear Area
004
FZ T
Unit 1 and Unit 2 Transformers
2
Corrective Action
Documents
1A RHR Pump Room Door
04/04/2021
Corrective Action
Documents
Resulting from
Inspection
NRC ID - Floatable Material in Flood Control Area
09/30/2024
Drawings
M-104-3
P & ID Reactor Building Floor Drains
L
LOA-FLD-001
Flooding
Procedures
LOP-RF-01T
Reactor Building Floor Drain Sumps
Work Orders
Inspection of Magnetrol for the U-1 A RHR Room
11/22/2019
Procedures
TQ-AA-150-F25,
LORT Annual
Exam Status
Report
LaSalle County Generating Station Licensed Operator
Requalification Status Report for the Annual Licensed
Operator Examination Given in 2024.
007
OBE-24-4-2
LORT Dynamic Simulator Scenario Guide
06/11/2024
Miscellaneous
Rema Plan
L1C21 September 2024 Sequence Exchange
09/17/2024
LGP 3-1
076
Procedures
LOP-TO-10
Turbine Oil Cooler Change-Over
1VY03C Failed to Auto Start
09/30/2016
Multiple Issues on A Diesel Fire Pump
2/10/2022
A Diesel Fire Pump Has Cracked Valve Cover
2/10/2022
Suspected Blown Head Gasket on 0B Diesel Fire Pump
09/05/2023
0B Diesel Fire Pump Will Not Be Restored within 7 Days
08/10/2023
Rebuild Removed 0FP25P Pump
2/20/2023
A Diesel Fire Pump Maintenance
04/18/2023
Corrective Action
Documents
Loss of Unit 1 SAT due to OCB 1-13 Tripped on Diff Current
04/20/2024
Corrective Action
Documents
Admin IR for A1DE IR 4767915 - Loss U1 SAT OCB 1-13
07/18/2024
Corrective Action
Documents
Resulting from
Inspection
NRC Identified: Missing Component Evaluation for A1DE
09/25/2024
Maintenance Rule (A)(1) and (A)(2) Requirements
003
Maintenance Rule Functions - Safety Significance
Classification
003
Maintenance Rule Implementation per NEI 18-10
000
Maintenance Rule 18-10 - Periodic (A)(3) Assessment
001
Procedures
Safety-Related Protective Coatings
017
Calculations
Curtiss Wright Seismic Report NUS-A056QA for Controller
Module Model CON2000-701-03/N
04560623
RCIC Pump Flow Controller Not Working in Manual
03/09/2023
04704146
U2 RCIC Pump Flow Controller Not Working in Manual
09/21/2023
04777334
U2 RCIC Pump Flow Controller Not Working in Manual
05/29/2024
04793031
RCIC Oil Leak
08/09/2024
04797522
U2 RCIC Controller Degraded in Auto and Manual
08/29/2024
04800683
U2 RCIC Nuclear Safety Concern
05/30/2024
04800685
U2 RCIC INOP Nuclear Concern Follow on
05/30/2024
CPS Commercial Grade Dedication (CGD) Extent of
Condition
07/11/2024
CPS Commercial Grade Dedication (CGD) Extent of
Condition
07/11/2024
CPS Commercial Grade Dedication (CGD) Extent of
Condition
07/11/2024
Corrective Action
Documents
1B DG A HDR STARTING AIR PRESS At Rounds Minimum
09/15/2024
Engineering
Changes
630084
Curtiss Wright Seismic Report NUS-A056QA for Controller
Module Model CON2000-701-03/N
Operability
Evaluations24-001
07/16/2024
LIS-RI-202
Unit 2 RCIC Pump Discharge Flow Indication Calibration
LIS-RI-215
Unit 2 RCIC Control System Calibration
Procedures
LOP-RI-06
Controlled Start of the Reactor Core Isolation Cooling
System in the CST Test Mode
LOS RI-Q3
Reactor Core Isolation Cooling (RCIC) System Pump
Operability and Valve Inservice Tests in Conditions 1,2, and
LOS-RI-Q5
Reactor Core Isolation Cooling (RCIC) System Pump
Operability, Valve Inservice Tests in Modes 1,2,3 and Cold
Quick Start
27
01814265
Perform EQ Inspect & Diagnostic Test 2E51-F019
03/01/2017
04611333
Perform EQ Inspection & Diagnostic Test 2E51-F045
03/09/2021
04611337
Perform EQ Inspection & Diagnostic Test 2E51-F013
2/27/2019
04898140
00090993-01, TS, U-2 DIV 1 RCIC Sys Relay Logic Test,
W:L02-LES-RI-201B
03/07/2023
04898141
U-2 RCIC SYS Relay Logic Test
03/10/2021
04900672
00091566-01, TS, LOS-RI-R3 U2 RCIC ATT 2A,
W:L02-LOS-RI-R3-2A
03/08/2023
05071863
00091393-01, TSEQ, RX VSL LVL 1 ECCS Init/Lvl 2 RCIC
Init Chans A&C, W:L02-LIS-NB-204A
08/12/2022
05083389
00091394-01, TSEQ, RX VSL LVL 1 ECCS Init/ Lvl 2 RCIC
Init Chans B&D, W:L02-LIS-NB-204B
09/15/2022
05087235
00081477-01, TSEQ, RX VSL HI LVL 8 RCIC Turb Trip &
Main Turb/FW PMP Trip, W;L02-LIS-RI-212
03/28/2023
05137971
00081234-01, TS, U-2 Feedwater/ Main Turbine Trip System
Relay Logic Test, W:L02-LES-FW-201
03/06/2023
05151005
RX VSL HI LVL 8 RCIC Turb Trip & Main Turb/Fw PMP Trip
03/28/2023
05194508
RCIC Equip Area/Pipe Tun HI AMB/DIFF Temp Isol CH B&D
2/09/2024
05194509
RCIC Equip Area/Pipe Tun Hi AMB/Diff Temp Isol CH A&C
2/09/2024
240282
RCIC Controller Not Stable during RCIC Low Press Run
2/11/2023
261146
RX VSL LVL 1 ECCS Init/Lvl 2 RCIC Init B&D
08/16/2023
285123
U2 CY Tank LO Level RCIC Suction Calibration
08/01/2024
05358236
RX VSL LVL 1 ECCS INIT/LVL 2 RCIC INIT
04/02/2024
05389146
U2 CY Tank LO Level RCIC Suction Functional
08/01/2024
05403690
U2 RCIC Troubleshoot/ Repair
11/29/2023
05422312
00091564-03, TS, Partial Stroke for IST Requirement,
W:L02-LOS-RI-Q5-2A
05/31/2024
Work Orders
05543439
00091558-01, TS, LOS-RI-Q6 ATT 2A, U2 RCIC System,
W:L02-LOS-RI-MI-2A
08/29/2024
05544265
00091564-01, TS, LRA_LOS-RI-Q5 U2 RCIC Cold Quick
Start ATT 2A, W:L02-LOS-RI-Q5-2A
08/29/2024
05544265
LRA-LOS-RI-Q5 U2 RCIC Cold Quick Start ATT 2A
08/29/2024
05576789
(Finish) LOS-AA-S201 TS Shiftly Surveillance ATT A
09/16/2024
FNM Rebuild the 2E21-C002 Pump for a Critical Spare
11/05/2021
EWP MM Rebuild the Removed RHR WL Pump
05/25/2022
EWP MM Rebuild Removed 2E12-C003 Pump for Use as
Spare
11/02/2023
Corrective Action
Documents
1B RR Pump Seal Temperature Trend
07/11/2024
1WS01PA Post Maintenance Testing Issues
07/03/2024
Corrective Action
Documents
1B DGCWP Strainer Would Not Rotate during BW
09/17/2024
LOP-WS-02
Service Water Pump and Service water Jockey Pump
Startup and Operation
LOS-FSG-SR1
FLEX Equipment Surveillance
Procedures
LOS-RH-Q1
RHR (LPCI) and RHR Service Water Pump and Valve
Inservice Test for Modes 1, 2, 3, 4, and 5
2
EWP MM 1B DG Cooling Water Strainer Coating Inspection
09/20/2024
EWP-EM 1E22-D300 (Contingency Repairs)
09/17/2024
1B D/G CW Pump Biennial Comprehensive IST Pump Test
09/17/2024
Flex Generator 0FF01KA Performance Test
07/18/2024
Work Orders
OP LOS-RH-Q1 Att 1a And Att I - U1 A RHR RTT
10/01/2024
EP-LAS-3QPI2024-OSC-Unsat DC
09/16/2024
EP-LAS-3QPI2024-OSC-Other Issues
09/16/2024
EP-LAS-3QPI2024-TSC-Unsat DC
09/16/2024
EP-LAS-3QPI2024-TSC-Other Issues
09/16/2024
EP-LAS-3QPI2024-Miscellaneous Issues
09/16/2024
Corrective Action
Documents
EP-LAS-3QPI2024-UNSAT-DC-Miscellaneous Issues
09/16/2024
Miscellaneous
LaSalle 3Q24 PI
Drill Package
LaSalle 3Q24 PI Drill Package
Emergency Response Organization (ERO)/Emergency
Response Facility (ERF) Activation and Operation
Procedures
Notifications
1A DG Output Bkr Failed to Close on First Attempt
09/02/2023
MSPI Reporting Review by NRC
09/27/2023
2A RHR Pump - Operating D/P Low
01/08/2024
U2 'A' RHR Pump disch press O.O.T. - B2 Trend Code
01/16/2024
Low Margin 2A RHR Pump D/P
2/07/2024
1E22-F023, HPCS Test to SP Valve Failed to Open
03/20/2024
IEMA ID: Missing Nut on 2B DG Exhaust Manifold
Connection
04/18/2024
Corrective Action
Documents
U2 HPCS Pump C/S Issue & Overcurrent Alarm on S/D
05/24/2024
Corrective Action
Documents
Resulting from
Inspection
MSPI Reporting Review by NRC - HPCS and RHR
10/15/2024
Mitigating Systems Performance Index Basis Document
71151
Procedures
Mitigating System Performance Index Data Acquisition &
Reporting
8