IR 05000352/2020004

Integrated Inspection Report 05000352/2020004 and 05000353/2020004 and Independent Spent Fuel Storage Installation Inspection Report 07200065/2020002

ML21033A980
Person / Time
Site:	Limerick
Issue date:	02/02/2021
From:	Christopher Lally Reactor Projects Region 1 Branch 4
To:	Rhoades D Exelon Generation Co, Exelon Nuclear
Lally C
References
IR 2020002, IR 2020004
Download: ML21033A980 (18)

Text

February 2, 2021

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000352/2020004 AND 05000353/2020004 AND INDEPENDENT SPENT FUEL STORAGE INSTALLATION INSPECTION REPORT 07200065/2020002

Dear Mr. Rhoades:

On December 31, 2020, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Limerick Generating Station, Units 1 and 2. On January 15, 2021, the NRC inspectors discussed the results of this inspection with Mr. Frank Sturniolo, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.

No findings or violations of more than minor significance were identified during this inspection.

This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, X /RA/

Signed by: Christopher Lally

Chris M. Lally, Acting Chief

Reactor Projects Branch 4

Division of Reactor Projects

Docket Nos. 05000352, 05000353 and 07200065 License Nos. NPF-39 and NPF-85

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000352, 05000353, and 07200065

License Numbers:

NPF-39 and NPF-85

Report Numbers:

05000352/2020004, 05000353/2020004, and 07200065/2020002

I-2020-002-0094

Licensee:

Exelon Generation Company, LLC

Facility:

Limerick Generating Station, Units 1 and 2

Location:

Sanatoga, PA 19464

Inspection Dates:

October 1, 2020 to December 31, 2020

Inspectors:

A. Ziedonis, Senior Resident Inspector

S. Haney, Resident Inspector

E. Dipaolo, Senior Reactor Inspector

J. Brand, Reactor Inspector

H. Anagnostopoulos, Senior Health Physicist

J. Nicholson, Senior Health Physicist

K. Warner, Senior Health Physicist

M. Henrion, Health Physicist

P. Ott, Operations Engineer

Approved By:

Chris M. Lally, Acting Chief

Reactor Projects Branch 4

Division of Reactor Projects

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

No findings or violations of more than minor significance were identified.

Additional Tracking Items

None.

PLANT STATUS

Unit 1 began the inspection period at rated thermal power. On November 13, 2020, the reactor automatically scrammed on a valid high reactor pressure signal. The high reactor pressure signal was caused by the closure of the '1B' inboard main steam isolation valve (MSIV). The closure of the '1B' inboard MSIV was caused by a loss of primary containment instrument gas pneumatic supply to the valve. Following repairs, the unit was restarted on November 16, 2020, and returned to rated thermal power on November 18, 2020. On December 19, 2020, operators reduced power to approximately 40 percent to remove the 1B recirculation pump from service to repair a coolant leak on the motor adjustable speed drive unit. Following repairs, the unit was returned to rated thermal power on December 23, 2020 and remained at or near rated thermal power for the remainder of the inspection period.

Unit 2 began the inspection period at rated thermal power. On December 9, 2020, the unit was down powered to 60 percent for main turbine valve testing, control rod testing, and condenser bay entry for steam leak repairs. The unit was returned to rated thermal power on December 10, 2020 and remained at or near rated thermal power for the remainder of the inspection period.

INSPECTION SCOPES

Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors 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.

Starting on March 20, 2020, in response to the National Emergency declared by the President of the United States on the public health risks of the coronavirus (COVID-19), resident and regional inspectors were directed to begin telework and to remotely access licensee information using available technology. During this time the resident inspectors performed periodic site visits each week, increasing the amount of time on site as local COVID-19 conditions permitted. As part of their onsite activities, resident inspectors conducted plant status activities as described in IMC 2515, Appendix D, observed risk significant activities, and completed on site portions of IPs. In addition, resident and regional baseline inspections were evaluated to determine if all or portion of the objectives and requirements stated in the IP could be performed remotely. If the inspections could be performed remotely, they were conducted per the applicable IP. In some cases, portions of an IP were completed remotely and on site. The inspections documented below met the objectives and requirements for completion of the IP.

71111.01 - Adverse Weather Protection

Seasonal Extreme Weather Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal cold temperatures on December 15, 2020

71111.04 - Equipment Alignment

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

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

(1) Unit 2 four-kilovolt (kV) distribution alignment on October 14, 2020

(2) Unit 1 high pressure coolant injection (HPCI) following main steam supply line warm-up on November 16, 2020

(3) Unit 1 'D12' emergency diesel generator alignment and material conditions following a monthly run on December 4, 2020

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

(1) The inspectors evaluated system configurations during a complete walkdown of the direct current distribution system during the week of December 14, 2020

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 area 26, Unit common remote shutdown panel room on October 6, 2020

(2) Fire areas 12 through 15, Unit 1 4kV switchgear rooms on October 14, 2020

(3) Fire area 93, Unit 1 air compressor, electrohydraulic control power unit, and turbine lubricating oil storage tank rooms on October 19, 2020

(4) Fire area 25, Unit common auxiliary equipment rooms on November 10, 2020

(5) Fire areas 22 and 23, Unit 1 and 2 cable spreading rooms on December 22, 2020

Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the onsite fire brigade training and performance during an unannounced fire drill on December 17, 2020

===71111.07T - Heat Sink Performance

Triennial Review (IP Section 03.02)===

(1) Unit 1 A emergency diesel generator jacket water heat exchanger, cooled by emergency service water, Section 02.02 (b)

(2) Unit 2 C' residual heat removal pump motor oil cooler 2C-E220, cooled by emergency service water, Section 02.02 (b)

(3) Unit 1 residual heat removal heat exchanger, cooled by residual heat removal service water, Section 02.02 (c)

(4) Unit common ultimate heat sink which includes a review of the residual heat removal service water, and spray pond, Section 02.02 (d), Items 3, 4, 5, and Items 6 (a), (c),

(d), (f), and (g)

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 licensed operator annual requalification results for the annual operating exam on December 7, 2020

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance

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

(1) The inspectors observed and evaluated licensed operator requalification training on October 27, 2020

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (3 Samples)

The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components remain capable of performing their intended function:

(1) Unit 1 D14 emergency diesel generator loss of 480-volt auxiliary power on November 1, 2020

(2) Unit 1 reactor recirculation system (a)(1) monitoring plan on November 24, 2020

(3) Unit 1 fuel assemblies (a)(1) monitoring plan on December 8, 2020

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 emergent work in response to service water common header leak on October 20, 2020

(2) Unit common risk-informed completion time window for the 201 safeguards transformer replacement on November 2-22, 2020

(3) Unit 1 emergent work to replace the primary containment instrument gas tubing supply to the 'B' inboard MSIV on November 14, 2020

(4) Unit 1 risk assessment for one inoperable offsite source during start-up from forced outage 1F56 on November 15, 2020

(5) Unit 1 yellow risk condition in operational condition 2 with containment de-inerted on November 16, 2020

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (5 Samples)

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

(1) Unit 1 failed jet pump operability surveillance during single recirculation loop operation on September 26, 2020

(2) Unit 1 standby liquid control tank level trending up on November 1, 2020

(3) Unit 1 K safety relief valve automatic depressurization system trip logic lights out on November 11, 2020

(4) Unit 1 reactor core isolation cooling system during plant heat-up on November 16, 2020

(5) Unit 1 K safety relief valve with elevated tailpipe temperature on November 30, 2020

71111.18 - Plant Modifications

Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (2 Samples)

The inspectors evaluated the following permanent modifications:

(1) Unit common 201 safeguard transformer replacement on November 2, 2020

(2) Unit common third offsite power source manual alignment capability on October 31, 2020

71111.19 - Post-Maintenance Testing

Post-Maintenance Test Sample (IP Section 03.01) (6 Samples)

The inspectors evaluated the following post-maintenance test activities to verify system operability and functionality:

(1) Unit 1 'D14' emergency diesel generator following jacket water heating element repairs on November 2, 2020

(2) Unit 2 service water pipe header following weld repairs on November 2, 2020

(3) Unit common third offsite source transfer switch on November 19, 2020

(4) Unit common 201 safeguards transformer load tap changer following replacement on November 21, 2020

(5) Unit common 'D13' emergency diesel generator following eight-year overhaul on December 11, 2020

(6) Unit 1 'B' adjustable speed drive unit coolant hoses following replacement on December 21, 2020

71111.20 - Refueling and Other Outage Activities

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

(1) The inspectors evaluated Unit 1 forced outage (1F56) activities from November 13 through 17, 2020

71111.22 - Surveillance Testing

The inspectors evaluated the following surveillance tests:

Surveillance Tests (other) (IP Section 03.01)

(1) ST-6-043-321-1, Unit 1 daily jet pump operability for single loop operation, on October 20, 2020

(2) ST-6-092-311-2, Unit 2 D21 emergency diesel generator slow start operability test run on November 23, 2020

(3) ST-6-001-765-2, Unit 2 main turbine control valve exercise and reactor protection system functional test on December 9, 2020

Reactor Coolant System (RCS) Leakage Detection Testing (IP Section 03.01) (1 Sample)

(1) ST-6-107-596-1/2, Unit 1 and Unit 2 drywell floor drain sump and equipment drain tank surveillance log on December 10, 2020

71114.06 - Drill Evaluation

Drill/Training Evolution Observation (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated a simulator training evolution on October 13,

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 radiological protection-related instructions to plant workers

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

The inspectors evaluated licensee processes for monitoring and controlling contamination and radioactive material.

(1) Observed the control, survey, and release of personnel and material at the 41 Line radiologically controlled area access point

(2) Observed the control, survey, and release of personnel and material to main turbine deck radiologically controlled area access point

Radiological Hazards Control and Work Coverage (IP Section 03.04) (3 Samples)

The inspectors evaluated in-plant radiological conditions during facility walkdowns and observation of radiological work activities.

(1) Flushing of the '2D' residual heat removal motor oil cooler in a posted High Radiation Area (2)

'1C' main condenser inspection and repair (ALARA plan 20-035)

(3) The inspectors monitored pre-job briefings for control rod drive mechanism removal and the removal and cutting of local power range monitors

High Radiation Area and Very High Radiation Area Controls (IP Section 03.05) (2 Samples)

The inspectors evaluated licensee controls of the following High Radiation Areas and Very High Radiation Areas:

(1) Unit 1 and Unit 2 drywell access shielded doors (2)

'2D' residual heat removal motor oil cooler scaffolding

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

71124.03 - In-Plant Airborne Radioactivity Control and Mitigation

Permanent Ventilation Systems (IP Section 03.01) (1 Sample)

The inspectors evaluated the configuration of the following permanently installed ventilation systems:

(1) Unit 2 'B' Reactor Enclosure Equipment Compartment Ventilation Exhaust

Temporary Ventilation Systems (IP Section 03.02) (1 Sample)

The inspectors evaluated the configuration of the following temporary ventilation systems:

(1) Portable high-efficiency particulate air filtration unit in the hot machine shop area

Use of Respiratory Protection Devices (IP Section 03.03) (1 Sample)

(1) The inspectors evaluated the licensees use of respiratory protection devices

Self-Contained Breathing Apparatus for Emergency Use (IP Section 03.04) (1 Sample)

(1) The inspectors evaluated the licensees use and maintenance of self-contained breathing apparatuses

71124.04 - Occupational Dose Assessment

Source Term Characterization (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated licensee performance as it pertains to radioactive source term characterization

External Dosimetry (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated licensee performance as it pertains to external dosimetry that is used to assign occupational dose

Internal Dosimetry (IP Section 03.03) (1 Sample)

The inspectors evaluated the following internal dose assessments for actual internal exposures:

(1) Dose Assessments for three workers who received internal dose during Unit 1 'C' condenser work in April 2020

Special Dosimetric Situations (IP Section 03.04) (1 Sample)

The inspectors evaluated the following special dosimetric situations:

(1) There were no declared pregnant workers or other special dosimetric situations in the past 24 months

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification

The inspectors verified licensee performance indicators submittals listed below:

MS10: Cooling Water Support Systems (IP Section 02.09)===

(1) Unit 1 for the period of October 1, 2019 through September 30, 2020

(2) Unit 2 for the period of October 1, 2019 through September 30, 2020

BI01: Reactor Coolant System (RCS) Specific Activity Sample (IP Section 02.10) (2 Samples)

(1) Unit 1 for the period of October 1, 2019 through September 30, 2020

(2) Unit 2 for the period of October 1, 2019 through September 30, 2020

BI02: RCS Leak Rate Sample (IP Section 02.11) (2 Samples)

(1) Unit 1 for the period of October 1, 2019 through September 30, 2020

(2) Unit 2 for the period of October 1, 2019 through September 30, 2020

OR01: Occupational Exposure Control Effectiveness Sample (IP Section 02.15) (1 Sample)

(1) Unit 1 November 2019 through November 2020 Unit 2 November 2019 through November 2020

PR01: Radiological Effluent Technical Specifications/Offsite Dose Calculation Manual Radiological Effluent Occurrences (RETS/ODCM) Radiological Effluent Occurrences Sample (IP Section 02.16) (1 Sample)

(1) Unit 1 November 2019 through November 2020 Unit 2 November 2019 through November 2020

71152 - Problem Identification and Resolution

Semiannual Trend Review (IP Section 02.02) (1 Sample)

(1) The inspectors reviewed the licensees corrective action program for potential adverse trends in human performance that might be indicative of a more significant safety issue

Annual Follow-up of Selected Issues (IP Section 02.03) (1 Sample)

The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:

(1) Jet pump surveillance test acceptance criteria for single loop operation (Issue Report (IR) 4389127)

71153 - Follow-up of Events and Notices of Enforcement Discretion Event Follow-up (IP Section 03.01)

(1) Unit 1 reactor pressure raised above 200 psig during plant start-up with the high-pressure coolant injection system isolated and inoperable on November 16, 2020 (Event Notification 55000)

Personnel Performance (IP Section 03.03) (1 Sample)

(1) Unit 1 high pressure reactor scram due to B inboard MSIV closure on November 13, 2020 (EN 54996)

OTHER ACTIVITIES

- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL

===60854.1 - Preoperational Testing of Independent Spent Fuel Storage Facility Installation at Operating Plants

Preoperational Testing of Independent Spent Fuel Storage Facility Installation at Operating Plants===

(1) The inspectors evaluated Limerick Generation Stations performance during NRC observed preoperational dry run activities that were performed in order to fulfill requirements in the Certificate of Compliance No. 1032, Amendment 1, Condition

9. The inspectors observed dry run activities on August 3, 2020 through August 5,

2020. Specifically, the inspectors observed or reviewed the following activities:

• Hydrostatic testing of the closure weld

• Blowdown and vacuum drying of the canister

• Simulated radiological field surveys and radiation protection coverage of canister processing activities

• Helium backfilling of the canister

INSPECTION RESULTS

Minor Violation 71152 Minor Violation: Surveillance test procedure ST-6-043-321-1/2, Daily Jet Pump Operability for Single Loop Operation, Revision 12/13, monitors recirculation loop flow, total core flow, and jet pump diffuser-to-lower plenum differential pressure, to detect significant degradation in jet pump performance in accordance with Technical Specification (TS) Surveillance Requirement (SR) 4.4.1.2b. During Unit 1 single loop operation on September 26, 2020, the performance of this surveillance was unsatisfactory because it did not meet the acceptance criteria for total core flow and jet pump diffuser-to-lower plenum differential pressure. Exelon performed a test results evaluation and determined the results were acceptable following additional engineering review.

TS SR 4.4.1.2b originally required Exelon to compare jet pump performance curves to performance curves that were generated from initial plant start-up data. The original performance curves are not likely to match the current performance curves of the jet pumps due to conditions such as fouling, wedge wear, and maintenance modifications that are anticipated to change the jet pump overall performance characteristics. Exelon received a TS amendment in 2008 (ML082831463) to eliminate the use of start-up data to allow for re-baselining jet pump performance data and generation of new performance curves. Following the license amendment, Exelon revised, or re-baselined, the Unit 2 surveillance test acceptance criteria for dual recirculation loop operation to enable a more accurate comparison of expected jet pump performance. Exelon determined that Unit 1 re-baselining for dual recirculation loop operation was not needed because jet pump performance continued to trend similar to original performance, and the SR acceptance criteria continued to be met. Exelon elected not to revise the surveillance test for single recirculation loop operation due to the infrequent and emergent nature of single loop operations.

The inspectors reviewed historical performance of the single recirculation loop surveillance and noted that Exelon performed engineering evaluation to accept unsatisfactory test results on four separate occasions since 2012: Unit 1 in 2012 (IR 1409892), Unit 1 in 2018 (IR 4145666), Unit 2 in 2019 (IR 4251891), and Unit 1 in 2020 (IRs 4372305 and 4381634). The inspectors noted that while TS SR 4.4.1.2b bases does allow engineering judgement to detect abnormalities which could indicate a jet pump failure while re-baselining new established patterns (as well as NUREG-1433, Revision 4, Standard TS SR 3.4.2.1 Bases),the inspectors determined that Exelon was not actively re-baselining the single recirculation loop performance curves. Despite the generation of multiple IRs and action items, no action had been completed to re-baseline the performance curves in the single recirculation loop surveillance test. Therefore, in the absence of any action to re-baseline, the inspectors determined this issue constituted a violation of TS 6.8.1d, "Procedures and Programs,"

because the surveillance test for single loop operation no longer included adequate acceptance criteria to cover TS SR 4.4.1.2b, due to changes in jet pump performance since initial plant start-up data.

The inspectors reviewed RT-1-043-231-1/2, "Reactor Recirculation System Baseline Data - Single Loop Operation," Revision 3/3, Section 1.0, "Purpose," and noted the purpose of the procedure was to obtain operating data if single loop operation is expected to last more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The inspectors noted that during three of the four examples described above, Exelon operated in a single loop configuration for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Additionally, the inspectors reviewed request for additional information responses (ML082120098) from the 2008 TS amendment, and noted Exelon stated re-baselining would be initiated upon entry into single loop operation which is outside of previously operated single loop operation ranges. Based on this review, the inspectors determined the repeated nature of unsatisfactory SR 4.4.1.2b test results was reasonably within Exelon's ability to foresee and correct, and should have been prevented, and therefore constituted a performance deficiency.

Screening: The inspectors determined the performance deficiency was minor. The inspectors screened this performance deficiency in accordance with Inspector Manual Chapter (IMC) 0612, Appendix B, "Additional Issue Screening Guidance," effective date January 1, 2021, and determined it was minor, because on each occasion engineering had performed adequate reviews of the single loop operation data within the 24-hour required surveillance frequency; and therefore the issue could not be reasonably viewed as a precursor to a significant event, the issue would not reasonably have the potential to lead to a more significant safety concern, and there was no adverse effect to any cornerstone objective.

Enforcement:

Limerick Unit 1 and Unit 2 TS 6.8.1d, "Procedures and Programs," requires that written procedures shall be established, implemented, and maintained to cover surveillance and test activities of safety-related equipment. Contrary to this, ST-6-043-321-1/2, Daily Jet Pump Operability for Single Loop Operation, which was established and implemented with acceptance criteria to cover SR 4.4.1.2b during single loop operation, was not maintained to cover SR 4.4.1.2b. Exelon generated IR 4389127 to capture the issue in the corrective action program. This failure to comply with TS 6.8.1d constitutes a minor violation that is not subject to enforcement action in accordance with the NRCs Enforcement Policy.

Observation: Semiannual Trend Review 71152 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 corrective action program. In particular, the inspectors noted an adverse trend associated with five human performance issues within an approximately one-month period:

• Bumping a radiation monitor mode selector switch in the auxiliary equipment room on November 21, resulting in an unexpected main control room alarm and a non-functional rad monitor (IR 4385776)

• Failure to un-isolate the HPCI and reactor core isolation cooling (RCIC) systems prior to entering the OPERATIONAL CONDITION required in the Unit 1 TSs during plant heat-up from forced outage 1F56 on November 16 (IR 4384739, EN 55000, and LER 2020-002)

• Misuse of welding purge material and failure to enter stop work during the week of November 5, when excessive leak-by was experienced during reactor water clean-up B train planned valve maintenance, resulting in significant delays to return the B train to service (IR 4386863)

• Failure to adequately review the ground grid map and enter stop work, resulting in the uncovering a ground cable during outside excavation on October 26 (IR 4379630)

• Inadequate review of station drawings and inadequate oversight of contractor work force, resulting in Unit 2 non-safety-related service water pipe breach during outside excavation on October 20 (IR 4377981).

The inspectors noted these issues spanned across multiple departments, and noted several corrective actions performed by Exelon, including:

• Conducting human performance review boards

• Conducting corrective action program evaluations

• Performing clock resets to heighten awareness and reiterate the standards

• Conducting human performance, standards of the week, that place increased focus on HU tools at daily meetings and pre-job briefs

• Conducting a Performance Improvement Action Plan, which included a Streaming Analysis, to examine commonality and take actions across all the major departments

• Conducted benchmarking in the area of configuration control (IR 4393777)

Based on the overall results of the semiannual trend review, the inspectors determined that Exelon was appropriately responding with actions commensurate with the safety significance, and therefore determined this adverse trend was not indicative of a more significant safety issue. With respect to the bullet above regarding the failure to un-isolate HPCI and RCIC and the resulting LER, the inspectors noted that a root cause evaluation remained in progress at the close of the inspection period. Follow-up review of this event, as well as the root cause report, will be performed and documented in a subsequent inspection quarter during LER closeout review in accordance with IP

EXIT MEETINGS AND DEBRIEFS

The inspectors verified no proprietary information was retained or documented in this report.

• On January 15, 2021, the inspectors presented the integrated inspection results to Mr. Frank Sturniolo, Site Vice President, and other members of the licensee staff.

• On December 11, 2020, the inspectors presented the Triennial Heat Sink inspection results to Mr. Frank Sturniolo, Site Vice President, and other members of the licensee staff.

• On December 16, 2020, the inspectors presented the Independent Spent Fuel Storage Installation Inspection Results inspection results to Joseph Dougherty, Senior Program Manager Dry Cask Storage, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

60854.1

Miscellaneous

Certificate of

Compliance

(CoC) No. 1032

HI-STORM Flood/Wind (FW) Multipurpose Canister (MPC)

Storage System

Amendment

RRTI No. 2847-

006-R2,

Response to Request for Technical Information, Holtec

International, Holtec Project No.2847

11/24/2020

Procedures

HPP-2847-300

MPC Sealing, Drying, and Backfilling

Work Orders

WO C93736388

ISFSI Campaign Dry Run Phases 1 and 2 Cask Sealing,

Drying, and Backfilling

71111.01

Procedures

GP-7

Cold Weather Preparation and Operation

Revision 56

71111.04

Corrective Action

Documents

4389680

4389684

4390024

71111.05

Corrective Action

Documents

Resulting from

Inspection

4382473

Procedures

F-A-432/3/4/5

Unit 1 D11/2/3/4 Emergency 4kV Switchgear Rooms

2/3/4/5

Revisions

2/13/13/14

OP-LG-201-008

Limerick Generating Station Fire Protection Pre-Fire Plan

Strategies

Revision 5

OP-LG-201-008

Limerick Generating Station Fire Protection (F) Pre-Fire Plan

Strategies

Revision 5

71111.07T Calculations

LM-0640

RHR Heat Exchanger Min. RHRSW Flow/Fouling

Factor/Tube Plugging Limits for Shutdown Cooling

Corrective Action

Documents

2703751

2703751

4091177

4154379

Corrective Action

Documents

Resulting from

Inspection

4389601

4399620

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Miscellaneous

LM-0225

Performance Curves for Emergency Diesel Generator Heat

Exchangers to Support USNRC Generic Letter 89-13

ST-2-088-320-0

Evaluation of Test Results, performed 1/20/17

ST-2-088-320-0,

Remote Shutdown System ESW and RHRSW Operability

Test, completed 6/14/19

ST-6-012-206-0

Schuylkill River M/U to Spray Pond Manual Valve IST Test,

completed 4/24/19

Work Orders

4593228

4865606-01

4934717

71111.12

Corrective Action

Documents

202624

4332701

4370178

4372283

4373761

4377219

4377220

4379918

4391111

71111.13

Corrective Action

Documents

4377981

4393151

Corrective Action

Documents

Resulting from

Inspection

4390530

4390649

4390669

4390825

71111.15

Corrective Action

Documents

4381493

4383755

4384739

4385193

4386028

4386003

71111.18

Corrective Action

Documents

4383536

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Resulting from

Inspection

Engineering

Changes

EC 625788

201 Safeguard Transformer Replacement

Revision 0

EC 627742

Third offsite power source modification

Revision 0

71111.19

Corrective Action

Documents

4333172

Corrective Action

Documents

Resulting from

Inspection

4391879

4391979

71152

Corrective Action

Documents

Resulting from

Inspection

4381634

4389127

4390104

Miscellaneous

GE SIL 330

Jet Pump Beam Cracks

June 9, 1980

71153

Corrective Action

Documents

4384039

4384739