IR 05000352/2024002: Difference between revisions

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One Severity Level IV violation without an associated finding is documented in this report. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.
One Severity Level IV violation without an associated finding is documented in this report. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.


No NRC- identified or self-revealing findings were identified during this inspection.
No NRC-identified or self-revealing findings were identified during this inspection.


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:
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 I; the Director, Office of Enforcement; and the NRC Resident Inspector at Limerick Generating Station, Units 1 and 2. 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.
Document Control Desk, Washington, DC 20555- 0001; with copies to the Regional Administrator, Region I; the Director, Office of Enforcement; and the NRC Resident Inspector at Limerick Generating Station, Units 1 and 2. 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, Jonathan E. Greives, Chief Projects Branch 4 Division of Operating Reactor Safety
Sincerely, Jonathan E. Greives, Chief Projects Branch 4 Division of Operating Reactor Safety


Docket Nos. 05000352 and 05000353 License Nos. NPF-39 and NPF- 85
Docket Nos. 05000352 and 05000353 License Nos. NPF-39 and NPF-85


===Enclosure:===
===Enclosure:===
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Docket Numbers: 05000352 and 05000353
Docket Numbers: 05000352 and 05000353


License Numbers: NPF-39 and NPF- 85
License Numbers: NPF-39 and NPF-85


Report Numbers: 05000352/2024002 and 05000353/2024002
Report Numbers: 05000352/2024002 and 05000353/2024002
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INSPECTION SCOPES
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.
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
REACTOR SAFETY
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Fire Brigade Drill Performance Sample (IP Section 03.02) (2 Samples)
Fire Brigade Drill Performance Sample (IP Section 03.02) (2 Samples)


  (1) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill in fire area F-CWP-001, circulating water pump house, on May 30, 2024 (2) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill in fire area F- GML-001, Graham Leitch Building, on June 18, 2024
  (1) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill in fire area F-CWP-001, circulating water pump house, on May 30, 2024 (2) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill in fire area F-GML-001, Graham Leitch Building, on June 18, 2024


71111.08G - Inservice Inspection Activities (BWR)
71111.08G - Inservice Inspection Activities (BWR)
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Minor Performance Deficiency: The inspectors performed a semiannual review to identify trends that might indicate the existence of a more significant safety issue, including issues that may have been documented outside the normal CAP. Overall, the inspectors determined that Constellation was appropriately identifying, evaluating, and resolving adverse trends. However, the inspectors identified one common trend that included two separate performance deficiencies. Specifically, the inspectors identified a trend of reactor enclosure (i.e., building) housekeeping and demobilization challenges, common to both units, following the transition to operational conditions (OPCONs) 2 and 1 after completion of Unit 1 refueling and maintenance outage 1R20.
Minor Performance Deficiency: The inspectors performed a semiannual review to identify trends that might indicate the existence of a more significant safety issue, including issues that may have been documented outside the normal CAP. Overall, the inspectors determined that Constellation was appropriately identifying, evaluating, and resolving adverse trends. However, the inspectors identified one common trend that included two separate performance deficiencies. Specifically, the inspectors identified a trend of reactor enclosure (i.e., building) housekeeping and demobilization challenges, common to both units, following the transition to operational conditions (OPCONs) 2 and 1 after completion of Unit 1 refueling and maintenance outage 1R20.


* For the first performance deficiency, the inspectors identified several outage- related items, such as trash bags, electrical cords, and temporary power cabling, were left in the reactor enclosure buildings without evaluation or transient combustible permits (Issue Report (IR) 4773918). The inspectors determined several of these items constituted non-compliances with OP- AA-201- 009, "Control of Transient Combustible Material," Revision 31.
* For the first performance deficiency, the inspectors identified several outage-related items, such as trash bags, electrical cords, and temporary power cabling, were left in the reactor enclosure buildings without evaluation or transient combustible permits (Issue Report (IR) 4773918). The inspectors determined several of these items constituted non-compliances with OP-AA-201- 009, "Control of Transient Combustible Material," Revision 31.


* For the second performance deficiency, the inspectors subsequently identified a tele-tower left in the vicinity of hydraulic control units following maintenance (IR 4773772). The inspectors determined this constituted a non- compliance with MA-LG-716- 026-1 001, "Additional Guidance for In-Plant / Yard Storage and Housekeeping at Limerick," Revision 23.
* For the second performance deficiency, the inspectors subsequently identified a tele-tower left in the vicinity of hydraulic control units following maintenance (IR 4773772). The inspectors determined this constituted a non-compliance with MA-LG-716- 026-1 001, "Additional Guidance for In-Plant / Yard Storage and Housekeeping at Limerick," Revision 23.


Subsequently, Constellation performed additional plant housekeeping walkdowns, and identified additional challenges related to 1R20 demobilization and general housekeeping (IRs 4773889, 4775610, and 4775579).
Subsequently, Constellation performed additional plant housekeeping walkdowns, and identified additional challenges related to 1R20 demobilization and general housekeeping (IRs 4773889, 4775610, and 4775579).


Screening: The inspectors determined the performance deficiency was minor. The inspectors reviewed these issues in accordance with IMC 0612, Appendix B, "Issue Screening Directions," effective date August 9, 2023, and determined the transient combustible loading was not of more than minor significance because it was within loading assumed in existing calculations, and determined the tele- tower would not have adversely impacted the safety function of any control rods during a seismic event.
Screening: The inspectors determined the performance deficiency was minor. The inspectors reviewed these issues in accordance with IMC 0612, Appendix B, "Issue Screening Directions," effective date August 9, 2023, and determined the transient combustible loading was not of more than minor significance because it was within loading assumed in existing calculations, and determined the tele-tower would not have adversely impacted the safety function of any control rods during a seismic event.


Minor Performance Deficiency 71152S Semiannual Trend Review: Inadequate Operability Screening for 'B' Control Enclosure Chiller
Minor Performance Deficiency 71152S Semiannual Trend Review: Inadequate Operability Screening for 'B' Control Enclosure Chiller


Minor Performance Deficiency: During review of the self-revealing adverse trend involving eight performance issues associated with the 'B' control enclosure chiller, discussed under the semiannual trend observation documented below, the inspectors identified a performance deficiency with respect to Constellation's operability screening in response to the first of the eight performance issues (IR 4767157). Specifically, the failure to start was attributed to a locked- in high bearing temperature protective trip feature, which was subsequently reset and determined to most likely be spurious - though no troubleshooting was performed. The inspectors noted that operators screened the 'B' chiller as operable, based on a historical engineering technical evaluation from 1998 (ECR 98- 00868). However, the conditions evaluated under the technical evaluation were different than the high bearing temperature protective trip feature, and therefore did not constitute an adequate basis to support operability. The inspectors subsequently reviewed OP-AA- 108- 115, "Operability Determinations," Revision 27, and noted that step 4.1.8 required that any use of previous evaluations should be validated, and the basis provided in the IR. Therefore, the inspectors concluded step 4.1.8 of OP- AA- 108-115 was not met.
Minor Performance Deficiency: During review of the self-revealing adverse trend involving eight performance issues associated with the 'B' control enclosure chiller, discussed under the semiannual trend observation documented below, the inspectors identified a performance deficiency with respect to Constellation's operability screening in response to the first of the eight performance issues (IR 4767157). Specifically, the failure to start was attributed to a locked-in high bearing temperature protective trip feature, which was subsequently reset and determined to most likely be spurious - though no troubleshooting was performed. The inspectors noted that operators screened the 'B' chiller as operable, based on a historical engineering technical evaluation from 1998 (ECR 98- 00868). However, the conditions evaluated under the technical evaluation were different than the high bearing temperature protective trip feature, and therefore did not constitute an adequate basis to support operability. The inspectors subsequently reviewed OP-AA-108-115, "Operability Determinations," Revision 27, and noted that step 4.1.8 required that any use of previous evaluations should be validated, and the basis provided in the IR. Therefore, the inspectors concluded step 4.1.8 of OP-AA-108-115 was not met.


Screening: The inspectors determined the performance deficiency was minor. The inspectors reviewed this issue in accordance with IMC 0612, Appendix B, "Issue Screening Directions,"
Screening: The inspectors determined the performance deficiency was minor. The inspectors reviewed this issue in accordance with IMC 0612, Appendix B, "Issue Screening Directions,"
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chiller whereby Constellation missed several opportunities to conduct troubleshooting and resolve deficiencies before they developed into an adverse trend. Specifically, between April 17 and May 17, 2024, the 'B' control enclosure chiller experienced seven trips and one failure to start on demand.
chiller whereby Constellation missed several opportunities to conduct troubleshooting and resolve deficiencies before they developed into an adverse trend. Specifically, between April 17 and May 17, 2024, the 'B' control enclosure chiller experienced seven trips and one failure to start on demand.


The inspectors reviewed all eight issues and noted that six of them had either no cause determined or were caused by a spurious high bearing temperature protective trip. Inspectors subsequently reviewed MA-AA- 716-004, "Conduct of Troubleshooting," Revision 21, and determined there was no requirement specifying when troubleshooting shall be conducted. The inspectors further noted the chiller was classified as safety -related, and subsequently reviewed Constellation's ability to promptly identify and correct conditions adverse to quality of the 'B' chiller. Specifically, the inspectors noted the chiller was declared inoperable after the second performance issue (trip with unknown cause) and was subsequently declared operable following corrective maintenance in response to the fourth performance issue (trip with a known cause other than high bearing temperature). The inspectors concluded these actions were reasonable to the circumstances. Following a fifth performance issue (another trip with an unknown cause), the chiller was declared inoperable again, with successful troubleshooting and corrective maintenance following three additional trips, and subsequently declared operable with no further performance issues for the remainder of the inspection period. The inspectors also concluded these actions were reasonable to the circumstances.
The inspectors reviewed all eight issues and noted that six of them had either no cause determined or were caused by a spurious high bearing temperature protective trip. Inspectors subsequently reviewed MA-AA-716-004, "Conduct of Troubleshooting," Revision 21, and determined there was no requirement specifying when troubleshooting shall be conducted. The inspectors further noted the chiller was classified as safety -related, and subsequently reviewed Constellation's ability to promptly identify and correct conditions adverse to quality of the 'B' chiller. Specifically, the inspectors noted the chiller was declared inoperable after the second performance issue (trip with unknown cause) and was subsequently declared operable following corrective maintenance in response to the fourth performance issue (trip with a known cause other than high bearing temperature). The inspectors concluded these actions were reasonable to the circumstances. Following a fifth performance issue (another trip with an unknown cause), the chiller was declared inoperable again, with successful troubleshooting and corrective maintenance following three additional trips, and subsequently declared operable with no further performance issues for the remainder of the inspection period. The inspectors also concluded these actions were reasonable to the circumstances.


The inspectors concluded that with no direct procedure requirement for when to enter troubleshooting, and based on Constellation's actions to identify the conditions adverse to quality described above, and declare the chiller inoperable until corrective maintenance was completed, there was no performance deficiency for Constellation's overall actions in response to the adverse trend of 'B' chiller performance described above.
The inspectors concluded that with no direct procedure requirement for when to enter troubleshooting, and based on Constellation's actions to identify the conditions adverse to quality described above, and declare the chiller inoperable until corrective maintenance was completed, there was no performance deficiency for Constellation's overall actions in response to the adverse trend of 'B' chiller performance described above.


Condition Prohibited by TSs (LER 2024-001-00) due to MSIV Local Leak Test Results Cornerstone Severity Cross- Cutting Report Aspect Section Not Severity Level IV Not 71153 Applicable NCV 05000352,05000353/2024002- 01 Applicable Open/Closed A self -revealed Severity Level IV NCV of T S 3.6.3, " PCIV, was identified when a review of the
Condition Prohibited by TSs (LER 2024-001-00) due to MSIV Local Leak Test Results Cornerstone Severity Cross-Cutting Report Aspect Section Not Severity Level IV Not 71153 Applicable NCV 05000352,05000353/2024002- 01 Applicable Open/Closed A self -revealed Severity Level IV NCV of T S 3.6.3, " PCIV, was identified when a review of the
  'B' outboard MSIV LLRT result history revealed that the valve was inoperable as a PCIV for greater than the allowable TS LCO time.
  'B' outboard MSIV LLRT result history revealed that the valve was inoperable as a PCIV for greater than the allowable TS LCO time.


Description : On April 9, 2024, during LLRT conducted during 1R20, as - found leakage for the B outboard MSIV (HV- 041 - 1F028B) was 208.9 standard cubic feet per hour (scfh), which exceeded the TS 3.6.1.2.c limit of 100 scfh for each individual MSIV. Based on the as - found condition and valve leakage history (see FIN 05000352,05000353/2022004- 03 under ADAMS Accession No. ML23041A388), there was firm evidence that the leakage rate for HV - 041-1F028B exceeded 100 scfh during the most recent operating cycle. Since the 'B' outboard MSIV is classified as a PCIV, Constellation subsequently determined the valve was inoperable as a PCIV due to the failure to meet its single valve TS limit. With one or more PCIVs inoperable, TS 3.6.3a requires the affected penetration be isolated by use of at least one de- activated automatic valve secured in the closed position within four hours or be in at least Hot Shutdown within the next 12 hours and Cold Shutdown in the following 24 hours.
Description : On April 9, 2024, during LLRT conducted during 1R20, as - found leakage for the B outboard MSIV (HV- 041 - 1F028B) was 208.9 standard cubic feet per hour (scfh), which exceeded the TS 3.6.1.2.c limit of 100 scfh for each individual MSIV. Based on the as - found condition and valve leakage history (see FIN 05000352,05000353/2022004- 03 under ADAMS Accession No. ML23041A388), there was firm evidence that the leakage rate for HV - 041-1F028B exceeded 100 scfh during the most recent operating cycle. Since the 'B' outboard MSIV is classified as a PCIV, Constellation subsequently determined the valve was inoperable as a PCIV due to the failure to meet its single valve TS limit. With one or more PCIVs inoperable, TS 3.6.3a requires the affected penetration be isolated by use of at least one de-activated automatic valve secured in the closed position within four hours or be in at least Hot Shutdown within the next 12 hours and Cold Shutdown in the following 24 hours.


Since the required TS actions were not met, this issue was determined to be reportable in
Since the required TS actions were not met, this issue was determined to be reportable in
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Severity: The inspectors determined this issue constitutes a Severity Level IV violation. The NRC Enforcement Policy, Section 2.2.1, states, in part, that, whenever possible, the NRC uses risk information in assessing the safety significance of violations. In accordance with IMC 0609, Appendix A, inspectors determined the issue was of very low safety significance because it did not result in an actual open pathway in the physical integrity of reactor containment. Accordingly, after considering that the condition represented very low safety significance, the inspectors concluded that the violation would be best characterized as Severity Level IV under the traditional enforcement process.
Severity: The inspectors determined this issue constitutes a Severity Level IV violation. The NRC Enforcement Policy, Section 2.2.1, states, in part, that, whenever possible, the NRC uses risk information in assessing the safety significance of violations. In accordance with IMC 0609, Appendix A, inspectors determined the issue was of very low safety significance because it did not result in an actual open pathway in the physical integrity of reactor containment. Accordingly, after considering that the condition represented very low safety significance, the inspectors concluded that the violation would be best characterized as Severity Level IV under the traditional enforcement process.


Violation: Limerick Generating Station, Unit 1, TS 3.6.3, "PCIVs," section 3.6.3a, requires that with one or more of the PCIVs inoperable, the affected penetration to be isolated by use of at least one de- activated automatic valve secured in the closed position within four hours or be in at least Hot Shutdown within the next 12 hours and Cold Shutdown in the following 24 hours. Contrary to this, from an indeterminate date during operational cycle 20 (commenced on April 22, 2022), until shutdown for refueling and maintenance outage 1R20 on April 8, 2024, the 'B' outboard MSIV was inoperable as a PCIV, without the required actions of TS 3.6.3a being completed.
Violation: Limerick Generating Station, Unit 1, TS 3.6.3, "PCIVs," section 3.6.3a, requires that with one or more of the PCIVs inoperable, the affected penetration to be isolated by use of at least one de-activated automatic valve secured in the closed position within four hours or be in at least Hot Shutdown within the next 12 hours and Cold Shutdown in the following 24 hours. Contrary to this, from an indeterminate date during operational cycle 20 (commenced on April 22, 2022), until shutdown for refueling and maintenance outage 1R20 on April 8, 2024, the 'B' outboard MSIV was inoperable as a PCIV, without the required actions of TS 3.6.3a being completed.


Enforcement Action: This violation is being treated as a NCV, consistent with Section 2.3.2 of the Enforcement Policy.
Enforcement Action: This violation is being treated as a NCV, consistent with Section 2.3.2 of the Enforcement Policy.

Revision as of 07:39, 4 October 2024

Integrated Inspection Report 05000352/2024002 and 05000353/2024002
ML24225A103
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 08/12/2024
From: Jon Greives
NRC/RGN-I/DORS
To: Rhoades D
Constellation Energy Generation, Constellation Nuclear
References
IR 2024002
Download: ML24225A103 (1)
v • d • e


Text

August 12, 2024

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000352/2024002 AND 05000353/2024002

Dear David Rhoades:

On June 30, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Limerick Generating Station, Units 1 and 2. On July 30, 2024, the NRC inspectors discussed the results of this inspection with Matthew Bonanno, Plant Manager, and other members of your staff. The results of this inspection are documented in the enclosed report.

One Severity Level IV violation without an associated finding is documented in this report. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.

No NRC-identified or self-revealing findings were identified during this inspection.

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 I; the Director, Office of Enforcement; and the NRC Resident Inspector at Limerick Generating Station, Units 1 and 2. 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, Jonathan E. Greives, Chief Projects Branch 4 Division of Operating Reactor Safety

Docket Nos. 05000352 and 05000353 License Nos. NPF-39 and NPF-85

Enclosure:

As stated

Inspection Report

Docket Numbers: 05000352 and 05000353

License Numbers: NPF-39 and NPF-85

Report Numbers: 05000352/2024002 and 05000353/2024002

Enterprise Identifier: I-2024-002- 0032

Licensee: Constellation Energy Generation, LLC

Facility: Limerick Generating Station, Units 1 and 2

Location: Sanatoga, PA 19464

Inspection Dates: April 1, 2024 to June 30, 2024

Inspectors: A. Ziedonis, Senior Resident Inspector L. Grimes, Resident Inspector K. Barnes, Senior Health Physicist G. Dipaolo, Senior Resident Inspector B. Edwards, Health Physicist A. Kostick, Technical Assistant J. Kulp, Senior Reactor Inspector E. Miller, Senior Reactor Inspector

Approved By: Jonathan E. Greives, 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 Limerick Generating Station, Units 1 and 2, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

List of Findings and Violations

Condition Prohibited by Technical Specifications (Licensee Event Report (LER) 2024-001-00)

due to Main Steam Isolation Valve Local Leak Test Results Cornerstone Severity Cross-Cutting Report Aspect Section Not Applicable Severity Level IV Not Applicable 71153 NCV 05000352,05000353/2024002- 01 Open/Closed A self-revealed Severity Level IV non-cited violation (NCV) of Technical Specification (TS) 3.6.3, "Primary Containment Isolation Valves" (PCIV), was identified when a review of the 'B'

outboard main steam isolation valve (MSIV) local leak-rate test (LLRT) result history revealed that the valve was inoperable as a PCIV for greater than the allowable TS limiting condition for operation (LCO) time.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000352/2024-001-00 LER 2024-001-00 for 71153 Closed Limerick Generating Station, Unit 1, Leakage for the Unit 1 `B' Outboard MSIV Exceeded TS Limit

PLANT STATUS

Unit 1 began the inspection period at approximately 87 percent rated thermal power (RTP) in end of cycle coastdown status. On April 8, 2024, the unit was shut down for a planned refueling and maintenance outage (1R20). The unit was returned to near RTP on April 30, 2024, and remained at or near RTP for the remainder of the inspection period.

Unit 2 began the inspection period at RTP. On May 18, 2024, operators lowered thermal power to approximately 85 percent for planned testing activities and a control rod pattern adjustment. The unit was restored to RTP on May 19, 2024, and 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)

(1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal extreme hot weather conditions during the weeks of May 27 and June 3, 2024

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (3 Samples)

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1) Unit 1 reactor core isolation cooling (RCIC) system following 1R20 refueling outage (RFO) on May 9, 2024 (2) Unit 1 high-pressure coolant injection (HPCI) system alignment during the performance of ST-6-055-360- 1, inservice inspection valve indicator verification test during the week of May 20, 2024 (3) Unit 2 hardened containment vent system alignment on June 18, 2024

Complete Walkdown Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated system configurations during a complete walkdown of the residual heat removal (RHR) service water system alignment during the weeks of June 10 and 17, 2024

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (6 Samples)

The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:

(1) Unit 1 (fire area 34) HPCI pump room on April 1, 2024 (2) Unit 2 (fire area 68) control rod drive equipment and neutron monitoring areas on April 13, 2024 (3) Unit 1 reactor building various fire areas on April 29, 2024 (4) Unit 2 (fire area 23) cable spreading room on May 14, 2024 (5) Unit 1 (fire areas 3 and 4) class 1E battery room during the week of June 17, 2024 (6) Unit 2 (fire areas 5 and 6) class 1E battery room during the week of June 17, 2024

Fire Brigade Drill Performance Sample (IP Section 03.02) (2 Samples)

(1) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill in fire area F-CWP-001, circulating water pump house, on May 30, 2024 (2) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill in fire area F-GML-001, Graham Leitch Building, on June 18, 2024

71111.08G - Inservice Inspection Activities (BWR)

BWR Inservice Inspection Activities Sample - Nondestructive Examination and Welding Activities (IP Section 03.01) (1 Sample)

The inspectors evaluated boiling water reactor nondestructive testing by reviewing the following examinations from April 8 - April 12, 2024:

(1)

1. Visual Examination (VT-1) of Jet Pump 2 Set Screw (JP 02 AS-1 VS) (Li1R20 IVVI 24-04)

2. IWL General Visual Examination of Suppression Pool Concrete in Safeguards Room 289 (CISI-24-VT-026)

3. IWE General Visual Examination of 295 Level Drywell Liner (CISI-24-VT-005)

4. IWE General Visual Examination of 303 Level Drywell Liner (CISI-24-VT-006)

5. IWE General Visual Examination of 313 Level Drywell Liner (CISI-24-VT-008)

6. Manual Ultrasonic Examination of RHR System 12 inch Pipe to Elbow Weld RHB-001 (Li1R20- UT-005)

7. Manual Ultrasonic Examination of RHR System 12 inch Valve to Pipe Weld RHB-003 (Li1R20-UT-002)

8. Manual Ultrasonic Examination of RHR System 12 inch Pipe to Elbow Weld RHB-004 (Li1R20- UT-003)

9. Automated Ultrasonic Examination of Reactor Pressure Vessel Weld AF (Flange to Shell, 436-499 segment) (LIM-1-600170)

10. Automated Phased Array Examination of the N2H Nozzle to Safe End Weld (LIM-1-601930)

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 shutdown of Unit 1 for refueling and maintenance on April 8, 2024; and also during Unit 1 reactor startup on April 26, 2024

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)

(1) The inspectors observed and evaluated licensed operator training in the digital glass-top simulator on June 26, 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 (SSCs) remain capable of performing their intended function:

(1) Unit 1 HPCI major inspection during the weeks of April 15 and 22, 2024 (2) Unit common 'B' control enclosure chiller following multiple trips from April 17 to May 17, 2024

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (5 Samples)

The inspectors evaluated the accuracy and completeness of risk assessments for the following planned and emergent work activities to ensure configuration changes and appropriate work controls were addressed:

(1) Unit 2 work controls and risk management actions during D21 emergency diesel generator (EDG) slow start run and 4kV bus UV testing during the week of April 2, 2024 (2) Unit common risk assessment and emergent work in response to seismic activity felt on-site on April 5, 2024 (3) Unit 1 risk assessment and emergent work control in response to the loss of the 'B'

reactor protection system distribution panel 1BY160 on April 11, 2024 (4) Unit 1 time to boil and risk management actions during cavity drain down on April 21, 2024

(5) Unit common high burnup lead use fuel assembly inspections in the spent fuel pool on June 7, 2024

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (7 Samples)

The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:

(1) Unit common 201 off-site power source following the failure of breaker 252-10303CS to open during the weeks of March 11 and 18, 2024 (2) Unit 1 'A' recirculation pump seal leakage and associated adverse condition monitoring plan during the week of April 1, 2024 (3) Unit common 'B' main control room chiller with pressure control valve set to manual control during the week of April 1, 2024 (4) Unit 1 fuel assembly water rod inspections in response to Part 21 notification (event notification 57088) during the weeks of April 8 and April 15, 2024 (5) Unit 1 EDG D14 forward voltage testing of the voltage regulator during the week of May 20, 2024 (6) Unit 1 safety / relief valve (SRV) pilot stage instrumentation functionality review on June 12, 2024 (7) Units 1 and 2 equipment impacts associated with elevated main steam line tunnel temperatures on June 12 and 20, 2024

71111.18 - Plant Modifications

Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (3 Samples)

The inspectors evaluated the following temporary or permanent modifications:

(1) Unit 1 SRV pressure instrumentation installation during the weeks of April 7 and 14, 2024 (2) Units 1 and 2 TS bases change associated with HPCI and RCIC system surveillance requirements during the weeks of April 8 and 15, 2024 (3) Units 1 and 2 hydrogen water chemistry controls upgrade during the week of April 29, 2024

71111.20 - Refueling and Other Outage Activities

Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated Unit 1 refueling and maintenance outage (1R20) activities from April 8, 2024 through April 27, 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) (6 Samples)

(1) Unit common 'B' control enclosure chiller following corrective maintenance on April 15, 2024 (2) Unit 1 HPCI operability verification ST-6-055-321-1 following major system inspection during the week of April 22, 2024 (3) Unit 1 control rods 34-51 and 30-31 following corrective maintenance during the week of April 22, 2024 (4) Unit 1 'B' outboard MSIV HV-041-1F028B as-left LLRT following corrective maintenance during the week of April 22, 2024 (5) Unit 1 reactor pressure vessel leakage test GP-10 following RFO maintenance on April 23, 2024 (6) Unit common motor driven fire pump following power cable replacement on June 11, 2024

Surveillance Testing (IP Section 03.01) (3 Samples)

(1) ST-6-041-202-1, Unit 1 MSIV cold shutdown valve test on April 8, 2024 (2) ST-6-092-116-1, Unit 1 D12 EDG 4 KV safeguard loss of power logic system functional / safeguards automatic actuation and outage testing during the week of April 14, 2024 (3) ST-6-092-118-1, Unit 1 D14 EDG 4 KV safeguard loss of power logic system functional / safeguards automatic actuation and outage testing during the week of April 14, 2024

Inservice Testing (IST) (IP Section 03.01) (1 Sample)

(1) ST-6-055-231-1, Unit 1 HPCI pump comprehensive test during the weeks of April 22 and 29, 2024

Containment Isolation Valve (CIV) Testing (IP Section 03.01) (1 Sample)

(1) ST-4-LLR-031/041/051/061-1, Unit 1 main steam line A/B/C/D during the week of April 8, 2024

RADIATION SAFETY

71124.01 - Radiological Hazard Assessment and Exposure Controls

Radiological Hazard Assessment (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated how the licensee identifies the magnitude and extent of radiation levels and the concentrations and quantities of radioactive materials and how the licensee assesses radiological hazards

Instructions to Workers (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated how the licensee instructs workers on plant-related radiological hazards and the radiation protection requirements intended to protect workers from those hazards

Contamination and Radioactive Material Control (IP Section 03.03) (2 Samples)

The inspectors observed/evaluated the following licensee processes for monitoring and controlling contamination and radioactive material:

(1) Licensee surveys of potentially contaminated material leaving the radiologically controlled area (2) Workers exiting the contaminated area at Unit 1 during a RFO

Radiological Hazards Control and Work Coverage (IP Section 03.04) (4 Samples)

The inspectors evaluated the licensee's control of radiological hazards for the following radiological work:

(1) Unit 1 turbine deck sandblasting activity (2) Unit 1 suppression pool diving (3) Unit 1 refuel floor activity (4) Unit 1 turbine reassembly

High Radiation Area and Very High Radiation Area Controls (IP Section 03.05) (3 Samples)

The inspectors evaluated licensee controls of the following high radiation areas and very high radiation areas:

(1) Unit 1 drywell (2) Unit 1 control rod drive mechanism hatch (3) Unit 1 radiation protection control point for the condenser bays

Radiation Worker Performance and Radiation Protection Technician Proficiency (IP Section 03.06) (1 Sample)

(1) The inspectors evaluated radiation worker and radiation protection technician performance as it pertains to radiation protection requirements

OTHER ACTIVITIES - BASELINE

71151 - Performance Indicator Verification

The inspectors verified licensee performance indicators submittals listed below:

MS05: Safety System Functional Failures (SSFFs) Sample (IP Section 02.04) (2 Samples)

(1) Unit 1 for the period of April 1, 2023 through March 31, 2024 (2) Unit 2 for the period of April 1, 2023 through March 31, 2024

MS06: Emergency AC Power Systems (IP Section 02.05) (2 Samples)

(1) Unit 1 for the period of April 1, 2023 through March 31, 2024 (2) Unit 2 for the period of April 1, 2023 through March 31, 2024

71152S - Semiannual Trend Problem Identification and Resolution

Semiannual Trend Review (Section 03.02) (1 Sample)

(1) The inspectors reviewed the licensees corrective action plan (CAP) for potential adverse 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) (1 Sample)

The inspectors evaluated the following licensees event reporting determinations to ensure it complied with reporting requirements.

(1) LER 05000352/2024-001-00, Leakage for the Unit 1 `B' Outboard MSIV Exceeded TS Limit (ADAMS Accession No. ML24162A324). The enforcement aspects of this LER are discussed in the Results section of this report. This LER is closed.

INSPECTION RESULTS

Minor Performance Deficiency 71152S Semiannual Trend Review: Reactor Enclosure Housekeeping / Demobilization During Start-up from RFO

Minor Performance Deficiency: The inspectors performed a semiannual review to identify trends that might indicate the existence of a more significant safety issue, including issues that may have been documented outside the normal CAP. Overall, the inspectors determined that Constellation was appropriately identifying, evaluating, and resolving adverse trends. However, the inspectors identified one common trend that included two separate performance deficiencies. Specifically, the inspectors identified a trend of reactor enclosure (i.e., building) housekeeping and demobilization challenges, common to both units, following the transition to operational conditions (OPCONs) 2 and 1 after completion of Unit 1 refueling and maintenance outage 1R20.

  • For the first performance deficiency, the inspectors identified several outage-related items, such as trash bags, electrical cords, and temporary power cabling, were left in the reactor enclosure buildings without evaluation or transient combustible permits (Issue Report (IR) 4773918). The inspectors determined several of these items constituted non-compliances with OP-AA-201- 009, "Control of Transient Combustible Material," Revision 31.
  • For the second performance deficiency, the inspectors subsequently identified a tele-tower left in the vicinity of hydraulic control units following maintenance (IR 4773772). The inspectors determined this constituted a non-compliance with MA-LG-716- 026-1 001, "Additional Guidance for In-Plant / Yard Storage and Housekeeping at Limerick," Revision 23.

Subsequently, Constellation performed additional plant housekeeping walkdowns, and identified additional challenges related to 1R20 demobilization and general housekeeping (IRs 4773889, 4775610, and 4775579).

Screening: The inspectors determined the performance deficiency was minor. The inspectors reviewed these issues in accordance with IMC 0612, Appendix B, "Issue Screening Directions," effective date August 9, 2023, and determined the transient combustible loading was not of more than minor significance because it was within loading assumed in existing calculations, and determined the tele-tower would not have adversely impacted the safety function of any control rods during a seismic event.

Minor Performance Deficiency 71152S Semiannual Trend Review: Inadequate Operability Screening for 'B' Control Enclosure Chiller

Minor Performance Deficiency: During review of the self-revealing adverse trend involving eight performance issues associated with the 'B' control enclosure chiller, discussed under the semiannual trend observation documented below, the inspectors identified a performance deficiency with respect to Constellation's operability screening in response to the first of the eight performance issues (IR 4767157). Specifically, the failure to start was attributed to a locked-in high bearing temperature protective trip feature, which was subsequently reset and determined to most likely be spurious - though no troubleshooting was performed. The inspectors noted that operators screened the 'B' chiller as operable, based on a historical engineering technical evaluation from 1998 (ECR 98- 00868). However, the conditions evaluated under the technical evaluation were different than the high bearing temperature protective trip feature, and therefore did not constitute an adequate basis to support operability. The inspectors subsequently reviewed OP-AA-108-115, "Operability Determinations," Revision 27, and noted that step 4.1.8 required that any use of previous evaluations should be validated, and the basis provided in the IR. Therefore, the inspectors concluded step 4.1.8 of OP-AA-108-115 was not met.

Screening: The inspectors determined the performance deficiency was minor. The inspectors reviewed this issue in accordance with IMC 0612, Appendix B, "Issue Screening Directions,"

effective date August 9, 2023. Specifically, the inspectors determined the inadequate operability screening documentation did not adversely impact the M itigating System cornerstone objective to ensure the availability, reliability, and capability of the control enclosure chiller system. The inspectors reviewed IMC 0612, Appendix E, "Examples of Minor Issues," effective date November 1, 2023, and determined the inadequate operability screening was similar to example 3.k, because the issue of concern was focused on the inadequate documentation and the chiller ultimately remained operable after the spurious trip was reset.

Observation: Semiannual Trend Review: Adverse Trend of 'B' Control Enclosure 71152S Chiller Adverse Performance The inspectors performed a semiannual review to identify trends that might indicate the existence of a more significant safety issue, including issues that may have been documented outside the normal CAP. Overall, the inspectors determined that Constellation was appropriately identifying, evaluating, and resolving adverse trends. However, the inspectors observed one self-revealing adverse trend involving the 'B' control enclosure

chiller whereby Constellation missed several opportunities to conduct troubleshooting and resolve deficiencies before they developed into an adverse trend. Specifically, between April 17 and May 17, 2024, the 'B' control enclosure chiller experienced seven trips and one failure to start on demand.

The inspectors reviewed all eight issues and noted that six of them had either no cause determined or were caused by a spurious high bearing temperature protective trip. Inspectors subsequently reviewed MA-AA-716-004, "Conduct of Troubleshooting," Revision 21, and determined there was no requirement specifying when troubleshooting shall be conducted. The inspectors further noted the chiller was classified as safety -related, and subsequently reviewed Constellation's ability to promptly identify and correct conditions adverse to quality of the 'B' chiller. Specifically, the inspectors noted the chiller was declared inoperable after the second performance issue (trip with unknown cause) and was subsequently declared operable following corrective maintenance in response to the fourth performance issue (trip with a known cause other than high bearing temperature). The inspectors concluded these actions were reasonable to the circumstances. Following a fifth performance issue (another trip with an unknown cause), the chiller was declared inoperable again, with successful troubleshooting and corrective maintenance following three additional trips, and subsequently declared operable with no further performance issues for the remainder of the inspection period. The inspectors also concluded these actions were reasonable to the circumstances.

The inspectors concluded that with no direct procedure requirement for when to enter troubleshooting, and based on Constellation's actions to identify the conditions adverse to quality described above, and declare the chiller inoperable until corrective maintenance was completed, there was no performance deficiency for Constellation's overall actions in response to the adverse trend of 'B' chiller performance described above.

Condition Prohibited by TSs (LER 2024-001-00) due to MSIV Local Leak Test Results Cornerstone Severity Cross-Cutting Report Aspect Section Not Severity Level IV Not 71153 Applicable NCV 05000352,05000353/2024002- 01 Applicable Open/Closed A self -revealed Severity Level IV NCV of T S 3.6.3, " PCIV, was identified when a review of the

'B' outboard MSIV LLRT result history revealed that the valve was inoperable as a PCIV for greater than the allowable TS LCO time.

Description : On April 9, 2024, during LLRT conducted during 1R20, as - found leakage for the B outboard MSIV (HV- 041 - 1F028B) was 208.9 standard cubic feet per hour (scfh), which exceeded the TS 3.6.1.2.c limit of 100 scfh for each individual MSIV. Based on the as - found condition and valve leakage history (see FIN 05000352,05000353/2022004- 03 under ADAMS Accession No. ML23041A388), there was firm evidence that the leakage rate for HV - 041-1F028B exceeded 100 scfh during the most recent operating cycle. Since the 'B' outboard MSIV is classified as a PCIV, Constellation subsequently determined the valve was inoperable as a PCIV due to the failure to meet its single valve TS limit. With one or more PCIVs inoperable, TS 3.6.3a requires the affected penetration be isolated by use of at least one de-activated automatic valve secured in the closed position within four hours or be in at least Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Cold Shutdown in the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Since the required TS actions were not met, this issue was determined to be reportable in

accordance with 10CFR50.73(a)(2)(i)(B), Any operation or condition which was prohibited by the plants TSs.

Corrective Actions: The valve was disassembled to perform repairs during 1R20 with the as-left leak-rate of 1.7 sfch.

Corrective Action References: Issue Reports (IRs) 4764696, 4553559, 4490449, 4331517 Performance Assessment: The NRC determined that this violation was associated with a previously documented finding assessed using the significance determination process.

Specifically, see FIN 05000352,05000353/2022004- 03 under ADAMS Accession No.

ML23041A388. No new performance deficiency was identified.

Enforcement: The Reactor Oversight Process significance determination process does not specifically consider violations of regulatory requirements without any new performance deficiency that is different from a recently issued finding. Therefore, it is necessary to address this violation using traditional enforcement.

Severity: The inspectors determined this issue constitutes a Severity Level IV violation. The NRC Enforcement Policy, Section 2.2.1, states, in part, that, whenever possible, the NRC uses risk information in assessing the safety significance of violations. In accordance with IMC 0609, Appendix A, inspectors determined the issue was of very low safety significance because it did not result in an actual open pathway in the physical integrity of reactor containment. Accordingly, after considering that the condition represented very low safety significance, the inspectors concluded that the violation would be best characterized as Severity Level IV under the traditional enforcement process.

Violation: Limerick Generating Station, Unit 1, TS 3.6.3, "PCIVs," section 3.6.3a, requires that with one or more of the PCIVs inoperable, the affected penetration to be isolated by use of at least one de-activated automatic valve secured in the closed position within four hours or be in at least Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Cold Shutdown in the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Contrary to this, from an indeterminate date during operational cycle 20 (commenced on April 22, 2022), until shutdown for refueling and maintenance outage 1R20 on April 8, 2024, the 'B' outboard MSIV was inoperable as a PCIV, without the required actions of TS 3.6.3a being completed.

Enforcement Action: This violation is being treated as a NCV, 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 July 30, 2024, the inspectors presented the integrated inspection results to Matthew Bonanno, Plant Manager, and other members of the licensee staff.

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