Text

Integrated Inspection Report 05000220/2020003 and 05000410/2020003
	ML20315A403
Person / Time
Site:	Nine Mile Point
Issue date:	11/10/2020
From:	Erin Carfang; Reactor Projects Branch 1
To:	Bryan Hanson; Exelon Generation Co, Exelon Nuclear
	Carfang E
References
	IR 2020003
	Download: ML20315A403 (23)
	v • d • e

November 10, 2020

SUBJECT:

NINE MILE POINT NUCLEAR STATION - INTEGRATED INSPECTION REPORT 05000220/2020003 AND 05000410/2020003

Dear Mr. Hanson:

On September 30, 2020, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Nine Mile Point Nuclear Station. On October 19, 2020, the NRC inspectors discussed the results of this inspection with Mr. Peter Orphanos, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.

One finding of very low safety significance (Green) is documented in this report. This finding involved a violation of NRC requirements. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.

A licensee-identified violation which was determined to be of very low safety significance is documented in this report. We are treating this violation as an NCV 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 I; the Director, Office of Enforcement; and the NRC Resident Inspector at Nine Mile Point Nuclear 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 I; and the NRC Resident Inspector at Nine Mile Point Nuclear Station. 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: Erin E. Carfang

Erin E. Carfang, Chief Reactor Projects Branch 1 Division of Reactor Projects

Docket Nos. 05000220 and 05000410 License Nos. DPR-63 and NPF-69

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000220 and 05000410

License Numbers:

DPR-63 and NPF-69

Report Numbers:

05000220/2020003 and 05000410/2020003

Enterprise Identifier: I-2020-003-0020

Licensee:

Exelon Generation Company, LLC

Facility:

Nine Mile Point Nuclear Station

Location:

Oswego, NY

Inspection Dates:

July 1, 2020 to September 30, 2020

Inspectors:

G. Stock, Senior Resident Inspector

J. Dolecki, Resident Inspector

B. Sienel, Resident Inspector

C. Hobbs, Reactor Inspector

J. Rady, Emergency Preparedness Inspector

Approved By:

Erin E. Carfang, Chief

Reactor Projects Branch 1

Division of Reactor Projects

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Nine Mile Point Nuclear 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. A licensee-identified NCV is documented in report section: 71111.1

List of Findings and Violations

Inadequate Maintenance Procedure Results in Control Room Ventilation Circulation Fan Bearing Failure Cornerstone Significance Cross-Cutting Aspect Report Section Barrier Integrity Green NCV 05000220/2020003-01 Open/Closed

[H.1] -

Resources 71153 The inspectors documented a self-revealed finding of very low safety significance and an associated NCV of Title 10 of CFR Part 50, Appendix B, Criterion V, Instructions,

Procedures, and Drawings, for Exelons failure to prescribe appropriate work instructions for performing maintenance on the Unit 1 control room ventilation circulation fan. Specifically, mechanical maintenance procedure, N1-MPM-210-552, "Control Room Ventilation System," lacked sufficient detail which contributed to the failure of the circulation fan 11 pillow block bearing and the associated unplanned inoperability of the control room air treatment system on May 3, 2020.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000220/2020-001-01 Control Room Air Treatment System Inoperable 71153 Closed LER 05000220/2020-001-00 Control Room Air Treatment System Inoperable 71153 Closed

PLANT STATUS

Unit 1 began the inspection period at rated thermal power. On September 18, 2020, the unit was downpowered to approximately 68 percent to repair a steam leak on a reheater drain tank.

The unit was returned to rated thermal power on September 19, 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 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.

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 hot temperatures for the following systems:

Unit 2 Division I, II, and III emergency diesel generators

Unit 2 Division I, II, and III 125-volt batteries

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (4 Samples)

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

(1) Unit 1 emergency condenser loop 12 on July 30, 2020

(2) Unit 1 emergency diesel generator 102 on August 18, 2020

(3) Unit 2 Division III diesel generator on September 10, 2020

(4) Unit 1 115-kilovolt system on September 15, 2020

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

(1) Unit 2 service water system on August 13, 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) Unit 1 reactor building 281 east, fire area 1, on August 3, 2020

(2) Unit 1 reactor building 281 west, fire area 2, on August 3, 2020

(3) Unit 2 diesel building 261', fire area 28, on September 24, 2020

(4) Unit 2 diesel building 261', fire area 29, on September 24, 2020

(5) Unit 2 diesel building 261', fire area 30, on September 24, 2020

71111.06 - Flood Protection Measures

Cable Degradation (IP Section 03.02) (1 Sample)

The inspectors evaluated cable submergence protection in:

(1) Unit 2 manhole 3 on August 14, 2020

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 Unit 1 operations personnel disconnect 345-kilovolt output Line 8 from the grid due to elevated cable temperatures in the Unit 1 switchyard on August 28, 2020

(2) The inspectors observed Unit 2 operations personnel during low pressure core spray system and diesel generator timing relay testing on September 17, 2020

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (2 Samples)

(1) The inspectors observed a Unit 1 simulator evaluation that included a medical emergency, stuck open relief valve, seismic event, loss of a non-safety-related power board, trip of recirculation pumps, anticipated transient without a scram, and an unisolable leak inside the reactor building on August 11, 2020

(2) The inspectors observed a Unit 2 simulator evaluation that included loss of recirculation flow indications to an average power range monitor, trip of an instrument air compressor, control rod drifting out, an unisolable leak inside the reactor building, loss of the electro-hydraulic control pumps, and failure of automatic depressurization safety relief valves on August 11, 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 (SSCs) remain capable of performing their intended function:

(1) Unit 2 standby gas treatment system

(2) Unit 2 service water system

(3) Unit 1 control room emergency ventilation system

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (7 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 1 elevated risk during planned containment spray 122 maintenance on July 8, 2020

(2) Unit 1 elevated risk during planned instrument air 11 maintenance on July 13, 2020

(3) Unit 1 elevated risk during emergent emergency cooling 12 maintenance on July 27, 2020

(4) Unit 1 elevated risk during planned instrument air 12 maintenance on July 30, 2020

(5) Unit 2 elevated risk during planned 'B' instrument air maintenance on August 10, 2020

(6) Unit 2 elevated risk during planned removal of manhole 3 shield plug on August 14, 2020

(7) Unit 2 elevated risk during planned 115-kilovolt Line 5 maintenance on September 10, 2020

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (6 Samples)

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

(1) Unit 2 Division II emergency diesel generator following increased fuel dilution detected in lubricating oil sample on July 16, 2020

(2) Unit 1 liquid poison 11 due to gap in structural support on pump discharge accumulator on July 17, 2020

(3) Unit 1 high pressure core spray system following condensate storage tank test return valve, 2CSH*MOV110, failure to close on July 22, 2020

(4) Unit 1 emergency diesel generator 103 following lowering lube oil pressure on August 8, 2020

(5) Unit 1 remote shutdown panel reactor water level indication due to missed surveillance on September 8, 2020

(6) Unit 2 service water system due to failure to perform non-destructive examination on welding following replacement/repair of the 'C' strainer, 2SWP*STR4C, drain line on September 29, 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 temporary or permanent modifications:

(1) Permanent Modification - Unit 1 Engineering Change Package ECP-20-000342, MTU-36-03A-M & MTU-36-06B-M Need to be Relocated Due to a Suspected Backplane Issue in the Card File

(2) Permanent Modification - Unit 2 Engineering Change Package ECP-17-000569, Replace 2CNM-LV137 and Add Volume Boosters 2CNM-FV38A/B/C

71111.19 - Post-Maintenance Testing

Post-Maintenance Test Sample (IP Section 03.01) (7 Samples)

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

(1) Unit 1 containment spray 122 following suction isolation valve, IV-80-22, rebuild on July 9, 2020

(2) Unit 1 emergency condenser 12 high steam flow master trip unit following emergent troubleshooting on July 28, 2020

(3) Unit 2 scram discharge volume drain valve, 2RDS*AOV130, following emergent stroke time adjustment on August 3, 2020

(4) Unit 1 instrument air compressor 12 following preventive maintenance on August 3, 2020

(5) Unit 2 Division II emergency diesel generator following control air maintenance on August 27, 2020

(6) Unit 1 electric fire pump following discharge check valve maintenance on August 28, 2020

(7) Unit 2 low pressure core spray system following offline motor testing on September 17, 2020

71111.22 - Surveillance Testing

The inspectors evaluated the following surveillance tests:

Surveillance Tests (other) (IP Section 03.01)

Main article: IP 71111.22

(1) N1-ST-M4B, Emergency Diesel Generator 103 and Power Board 103 Operability Test, on July 7, 2020

(2) N1-ST-Q8A, Liquid Poison Pump 11 and Check Valve Operability Test, on July 13, 2020

(3) N2-TTP-RHS-4Y003, Residual Heat Removal System Heat Exchanger (2RHS*E1A)

Performance Monitoring (Suppression Pool Cooling Mode), on July 20, 2020

RCS Leakage Detection Testing (IP Section 03.01) (1 Sample)

(1) CY-NM-170-341, Primary Containment Sampling and Analysis (Unit 1), on August 31, 2020

FLEX Testing (IP Section 03.02) (1 Sample)

(1) S-PM-003, FLEX 450KW Portable Diesel Generator Test, on August 4, 2020

71114.02 - Alert and Notification System Testing

Inspection Review (IP Section 02.01-02.04) (1 Sample)

(1) The inspectors evaluated Exelon's maintenance and testing of the Nine Mile Point alert and notification system on July 13-16, 2020, for the period of July 2018 through June 2020

71114.03 - Emergency Response Organization Staffing and Augmentation System

Inspection Review (IP Section 02.01-02.02) (1 Sample)

(1) The inspectors evaluated the readiness of Exelon's emergency preparedness organization on July 13-16, 2020

71114.04 - Emergency Action Level and Emergency Plan Changes

Inspection Review (IP Section 02.01-02.03) (1 Sample)

(1) The inspectors evaluated the following submitted Emergency Action Level and Emergency Plan changes onsite on July 13-16, 2020

Evaluation No.: 19-79, EP-AA-1013, Exelon Nuclear Radiological Emergency Plan Annex for Nine Mile Point Station, Revision 7

Evaluation No.: 19-87, EP-AA-1013, Exelon Nuclear Radiological Emergency Plan Annex for Nine Mile Point Station, Revision 8

Evaluation No.: 19-90, EP-AA-1013, Addendum 1, Nine Mile Point Nuclear Station Units 1 and 2 On-Shift Staffing Technical Basis, Revision 1

This evaluation does not constitute NRC approval

71114.05 - Maintenance of Emergency Preparedness

Inspection Review (IP Section 02.01 - 02.11) (1 Sample)

(1) The inspectors evaluated the maintenance of the emergency preparedness program on July 13-16, 2020, for the period of July 2018 through June 2020

71114.06 - Drill Evaluation

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

The inspectors evaluated:

(1) Unit 2 simulator evaluation which included an unisolable reactor core isolation cooling system leak inside the reactor building, and the associated declaration of a Site Area Emergency, due to a loss or potential loss of two fission product barriers on August 11,

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification

The inspectors verified licensee performance indicators submittals listed below:

EP01: Drill/Exercise Performance (IP Section 02.12)===

Main article: IP 71151

(1) October 1, 2019 - March 31, 2020

EP02: ERO Drill Participation (IP Section 02.13) (1 Sample)

(1) October 1, 2019 - March 31, 2020

EP03: Alert & Notification System Reliability (IP Section 02.14) (1 Sample)

(1) October 1, 2019 - March 31, 2020

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

(1) Unit 1 (July 1, 2019 - June 30, 2020)

(2) Unit 2 (July 1, 2019 - June 30, 2020)

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

(1) Unit 1 (July 1, 2019 - June 30, 2020)

(2) Unit 2 (July 1, 2019 - June 30, 2020)

MS07: High Pressure Injection Systems (IP Section 02.06) (2 Samples)

(1) Unit 1 (July 1, 2019 - June 30, 2020)

(2) Unit 2 (July 1, 2019 - June 30, 2020)

71152 - Problem Identification and Resolution

Annual Follow-up of Selected Issues (IP Section 02.03) (2 Samples)

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

(1) Unit 1 and Unit 2 Operator Work-Around Program

(2) Unit 2 Fuel Cladding Defect Identified by Routine Offgas Surveillance

71153 - Followup of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)

Main article: IP 71153

The inspectors evaluated the following licensee event reports (LERs):

(1) LER 05000220/2020-001-00 and LER 05000220/2020-001-01, Control Room Air Treatment System Inoperable (ADAMS Accession Nos. ML20192A074 and ML20269A248, respectively). The inspection conclusions associated with these LERs are documented in this report under Inspection Results.

OTHER ACTIVITIES

- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL

92709 - Licensee Strike Contingency Plans

Licensee Strike Contingency Plans (1 Partial)

(1) The contract between Exelon and IBEW Local 97 was set to expire at midnight on September 30, 2020. In preparation for a potential strike, the NRC inspectors evaluated the adequacy of Exelons contingency plan's post-strike staffing levels, staff qualifications, safety conscious working environment, and site access in meeting operational and security requirements. Prior to September 30, the contract expiration date was extended to October 30,

INSPECTION RESULTS

Licensee-Identified Non-Cited Violation 71111.15 This violation of very low safety significance was identified by the licensee and has been entered into the licensee corrective action program and is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy.

Violation: Title 10 of the Code of Federal Regulations (CFR) Section 50.55a, Codes and Standards, and American Society of Mechanical Engineer (ASME) Boiler and Pressure Vessel Code,Section III, Rules for Construction of Nuclear Facility Components, requires non-destructive examination on the surface of repair welds. Contrary to the above, on June 19, 2020, Exelon identified that a June 2019 Unit 2 service water system repair weld between the C strainer, 2SWP*STR4C, and C strainer drain line was not examined using magnetic particle or liquid penetrant methods.

Significance/Severity: Green. The inspectors determined this issue to be Green in accordance with IMC 0609 Appendix A, Exhibit 2, Mitigating Systems Screening Questions, because the service water system remained operable.

Corrective Action References: IR 04351358 Observation: Unit 2 Fuel Cladding Defect Identified by Routine Offgas Surveillance 71152 The inspectors reviewed Exelon's evaluation and corrective actions associated with the Unit 2 reactor fuel defect that was identified on June 11, 2018, through elevated offgas readings during fuel cycle 17. As a result of elevated offgas readings, power suppression testing was conducted June 15-17, 2018. Power suppression testing results indicated that a single defect existed within control cell 10-15. Control rod 10-15 was fully inserted to suppress reactor power in the four fuel assemblies in this core location. Immediate corrective actions taken by Exelon included convening a failed fuel monitoring team in accordance with NF-AA-430, Failed Fuel Action Plan," and implementing an adverse condition monitoring plan to monitor offgas and reactor coolant system activity levels for the remainder of the fuel cycle. A technical evaluation was performed under Engineering Change Package 18-000413 in July 2018 to evaluate control rod 10-15 exceeding its nuclear end of life before the end of fuel cycle 17. Shutdown margin was evaluated for the remainder of the fuel cycle, and shutdown margin was determined to be well below the Technical Specification 3.1.1 limit. Control rod blade 10-15 was discharged and replaced in the March 2020 refueling outage. Following power suppression testing activities on June 17, 2018, offgas and reactor coolant system activity levels remained stable for the rest of the fuel cycle.

Unit 2 was shut down for refueling in March 2020. As part of extent-of-condition corrective actions, Exelon examined all fuel assemblies that resided in the Unit 2 core through in-mast sipping during the refueling outage. Bundle YLJ300, which resided in control cell 10-15, was determined to contain the fuel cladding defect through in-mast sipping and visual inspection in the spent fuel pool. A foreign material exclusion (FME) hit team was formed to increase FME walkdowns and observations throughout the plant during the refueling outage.

Following the refueling outage, Exelon revised procedure NF-AB-431, Power Suppression Testing, to include more detailed instructions for power suppression testing based on lessons learned from testing activities conducted at Unit 2 in June 2018. In addition, Exelon revised procedure OP-AA-400-1001, Cladding Operational Reliability Excellence (CORE)

Program, to include lessons learned from the Unit 2 fuel defect in 2018, as well as operating experience from other nuclear plants in the Exelon fleet that have experienced fuel defects in recent years.

Inspectors interviewed reactor engineering and FME coordinator staff, reviewed the work group evaluation completed under IR 04146080, and reviewed the completed corrective actions taken associated with the June 2018 fuel defect. Exelon determined the cause of the fuel defect was debris fretting in a fuel rod located in the lower 1/3 height of bundle YLJ300 due to foreign material of unknown origin. Inspectors determined that Exelon appropriately classified and evaluated the June 2018 fuel defect and prioritized corrective actions commensurate with the safety significance of the issue. No performance deficiencies were identified.

Observation: Review of Unit 1 and Unit 2 Operator Work-Around Program 71152 The inspectors reviewed the current Unit 1 and Unit 2 operator work-arounds, operator challenges, defeated annunciator alarms, and main control room deficiencies to identify any effect on special and emergency operating procedure operator actions, and any impact on possible initiating events and mitigating systems. The inspectors evaluated whether station personnel had identified, prioritized, tracked, and resolved operator work-arounds and operator challenges as specified in OP-AA-102-103, Operator Work-Around Program. The inspectors also toured the control rooms and discussed the current operator work-arounds and burdens with the licensed operators to ensure deficiencies were being addressed consistent with OP-AA-102-103.

After a deficiency with the safety-related B train motor operated valve for emergency service water makeup to the spent fuel pool, 2SWP*MOV21B, was identified in September 2019, as stated in IR 04277608, Exelon operators isolated the B train emergency service water to spent fuel pool inlet isolation valve, 2SWP*V245B. Under this configuration, Exelon operators are required to perform the compensatory action of opening 2SWP*V245B prior to the performance of Step 4.3.4 of N2-SOP-38, Attachments 2 and 6, and Step 4.1 of N2-SOP-39. The inspectors questioned whether this was in accordance with procedure OP-AA-102-103. As a result of the inspectors challenge, Exelon subsequently revised N2-SOP-38 and N2-SOP-39 to include a step to verify open 2SWP*V245B prior to opening 2SWP*MOV21B.

This issue did not involve the failure to meet an NRC requirement, so no violation exists.

Inadequate Maintenance Procedure Results in Control Room Ventilation Circulation Fan Bearing Failure Cornerstone Significance Cross-Cutting Aspect Report Section Barrier Integrity

Green NCV 05000220/2020003-01 Open/Closed

[H.1] -

Resources 71153 The inspectors documented a self-revealed finding of very low safety significance and an associated NCV of Title 10 of CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for Exelons failure to prescribe appropriate work instructions for performing maintenance on the Unit 1 control room ventilation circulation fan. Specifically, mechanical maintenance procedure, N1-MPM-210-552, "Control Room Ventilation System,"

lacked sufficient detail which contributed to the failure of the circulation fan 11 pillow block bearing and the associated unplanned inoperability of the control room air treatment system on May 3, 2020.

Description:

The control room air treatment system, which is a part of the control room emergency ventilation system, is a safety-related system that provides clean, filtered air mixed with recirculated air for heating and cooling the control complex during abnormal operations. The recirculated air is supplied by the control room ventilation circulation fan.

The fan is unique in that a single fan is run by one of two redundant motors, 11 and 12. This configuration results in one motor being the drive motor while the other is driven. The fan has pillow block bearings on both sides of the fan that provide support to the fan where it is attached to the motors.

On April 22, 2020, the circulation fan was taken out of service due to elevated vibrations on the 11 motor. The 11 motor was replaced, and the motor sheave and key, which hold the belt that drives the fan, were reused. During post-maintenance testing, only the 11 motor was run and vibration analysis at the fan and 11 motor was performed with satisfactory results.

On May 3, 2020, operators recognized an unusual noise and smell in the control room. When swapping drive fans did not improve the noise, operators secured the fan and declared the control room air treatment system inoperable. Investigation found that a pillow block bearing on the circulation fan had failed. Through troubleshooting activities, Exelon determined that vibrations on the 11 motor were significantly worse when being driven by the 12 motor. Also, maintenance personnel had difficulty aligning the belt with the fan and motor, requiring a number of motor starts and vibration readings to be taken. This was due to challenges with installing the sheave and key with the appropriate fit. Ultimately, the fan bearings were replaced as well as the sheave and key on the 11 motor and the system was returned to operable.

Exelon sent the failed pillow block bearing to Exelon Powerlabs for analysis, which found the bearing failed due to a moment load on the bearing. While the cause of this load could be either misalignment or a manufacturing defect, Exelon acknowledged in the corrective action program evaluation that procedure N1-MPM-210-552 lacked adequate belt alignment and sheave installation guidance and vibration analysis requirements.

Corrective Actions: Exelon replaced both fan pillow block bearings as well as the 11 motor sheave and key and restored the control room air treatment system to operable. Other corrective actions include a revision to N1-MPM-210-552 to improve the guidance for aligning the fan belt and installing the sheave and key, as well as incorporate instructions for taking both drive and driven vibration data for both motors. Maintenance personnel will also be given training on the fan and motors, specifically the installation of the motor sheave and key. Long-term corrective actions include evaluating a design change to have two distinct fan and motor assemblies to remove the current unique configuration.

Corrective Action References: IR 04340639

Performance Assessment:

Performance Deficiency: The failure to prescribe appropriate instructions for performing maintenance on the safety-related control room ventilation circulation fan was a performance deficiency reasonably within Exelons ability to foresee and correct and should have been prevented.

The disposition of this performance deficiency closes LERs 05000220/2020-001-00 and -01, Control Room Air Treatment System Inoperable.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Procedure Quality attribute of the Barrier Integrity cornerstone and adversely affected the cornerstone objective to provide reasonable assurance that physical design barriers to protect the public from radionuclide releases caused by accidents or events. Specifically, the inadequate procedure quality in N1-MPM-210-552 contributed to the unplanned inoperability of the control room air treatment system on May 3, 2020.

Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined this finding was of very low safety significance (Green) because the failure of the circulation fan pillow block bearing only represented a degradation of the radiological barrier function provided for the control room.

Cross-Cutting Aspect: H.1 - Resources: Leaders ensure that personnel, equipment, procedures, and other resources are available and adequate to support nuclear safety.

Specifically, N1-MPM-210-552 did not provide Exelon personnel complete instruction in the installation of the fan belts or that motor vibration data should be taken while driving as well as being driven.

Enforcement:

Violation: Title 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, requires, in part, activities affecting quality shall be prescribed by documented procedures of a type appropriate to the circumstances. Exelon established procedure N1-MPM-210-552 to perform preventive maintenance on the safety-related control room ventilation circulation fan and motors, including the alignment and tensioning of the fan belts and sheave installation.

Contrary to the above, on April 22, 2020, N1-MPM-210-552 failed to prescribe instructions appropriate to the circumstances. Specifically, N1-MPM-210-552 contained inadequate belt alignment and sheave installation instructions and did not direct maintenance personnel to perform vibration analysis on the motors in both the drive and driven modes. On May 2, 2020, these inadequate instructions contributed to a failure of the circulation fan 11 pillow block bearing and the associated unplanned inoperability of the control room air treatment system.

Enforcement Action: This violation is being treated as an 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 October 19, 2020, the inspectors presented the integrated inspection results to Mr. Peter Orphanos, Site Vice President, and other members of the licensee staff

On July 16, 2020, the inspectors presented the emergency preparedness program inspection results to Mr. Todd Tierney, Plant Manager, and other members of the licensee staff

On August 28, 2020, the inspectors presented the fuel cladding defect inspection results to Mr. Brandon Shultz, Regulatory Assurance Manager, and other members of the licensee staff

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

71111.01

Corrective Action

Documents

04346100

04350332

04350870

Procedures

N1-OP-64

Meteorological Monitoring

01900

N2-OP-102

Meteorological Monitoring

2600

71111.04

Corrective Action

Documents

Resulting from

Inspection

04362224

04363031

Drawings

C-18017-C, Sheet

Emergency Cooling System P&I Diagram

PID-11A