IR 05000461/2021003

Integrated Inspection Report 05000461/2021003

ML21301A126
Person / Time
Site:	Clinton
Issue date:	10/29/2021
From:	Kenneth Riemer NRC/RGN-III/DRP/B1
To:	Rhoades D Exelon Generation Co
References
IR 2021003
Download: ML21301A126 (14)

Text

October 28, 2021

SUBJECT:

CLINTON POWER STATION - INTEGRATED INSPECTION REPORT 05000461/2021003

Dear Mr. Rhoades:

On September 30, 2021, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Clinton Power Station. On October 14, 2021, the NRC inspectors discussed the results of this inspection with Mr. T. Chalmers, 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, Signed by Riemer, Kenneth on 10/28/21 Kenneth R. Riemer, Chief Branch 1 Division of Reactor Projects Docket No. 05000461 License No. NPF-62

Enclosure:

As stated

Inspection Report

Docket Number: 05000461 License Number: NPF-62 Report Number: 05000461/2021003 Enterprise Identifier: I-2021-003-0068 Licensee: Exelon Generation Company, LLC Facility: Clinton Power Station Location: Clinton, IL Inspection Dates: July 01, 2021 to September 30, 2021 Inspectors: J. Beavers, Senior Resident Inspector J. Kutlesa, Physical Security Inspector A. Muneeruddin, Reactor Engineer J. Murphy, Illinois Emergency Management Agency D. Sargis, Resident Inspector Approved By: Kenneth R. Riemer, Chief Branch 1 Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Clinton Power Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

List of Findings and Violations

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 September 27, 2021, the unit was shut down for Refueling Outage C1R20 and remained shut down 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 on-site activities, resident inspectors conducted plant status activities as described in IMC 2515, Appendix D, Plant Status, and conducted routine reviews using IP 71152, Problem Identification and Resolution, 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 a 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.

71111.04 - 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) high pressure core spray system on July 16, 2021

(2) remote shutdown panels on July 26, 2021

(3) service air system on August 16, 2021

(4) Division 2 1E electrical alignment on September 29, 2021

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (3 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) diesel generator Division 1 diesel fuel tank room prefire plan on August 12, 2021

(2) diesel generator Division 2 diesel fuel tank room prefire plan on August 12, 2021

(3) drywell prefire plan on September 27, 2021

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 September 8, 2021.

71111.06 - Flood Protection Measures

Inspection Activities - Internal Flooding (IP Section 03.01) (2 Samples)

The inspectors evaluated internal flooding mitigation protections in the:

(1) auxiliary building basement general area

(2) turbine building basement general area

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 initial entry into a risk-informed completion time modification of the emergency reserve auxiliary transformer on August 28, 2021.

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

(1) The inspectors observed and evaluated simulator performance on July 20, 2021.

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (2 Samples)

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

(1) reactor core isolation cooling vacuum breaker isolation valve

(2) emergency reserve auxiliary transformer

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (4 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) Work Order 5109314, "Reactor Core Isolation Cooling Exhaust Vacuum Breaker Outboard Isolation Valve Torque Switch Emergent Maintenance"

(2) Work Order 5177741, "Emergency Reserve Load Tap Changer Motor Change Out"

(3) Work Order 4900885, "Emergency Reserve Aux Transformer Static Volts Reactive Compensator Modification During Single Credited Offsite Power Condition Under Risk Informed Completion Time"

(4) Work Order 5069172, "Fuel Pool Cooling Pump 'B' Degraded Seal Repair"

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) reactor core isolation cooling exhaust vacuum breaker outboard isolation valve on July 15, 2021

(2) fuel handling building sumps on August 20, 2021

(3) level transmitter 1B21-N091E on August 24, 2021

(4) emergency reserve auxiliary transformer failed to control voltage within the required band on September 25, 2021

(5) 'A' source range monitor on September 27, 2021

71111.18 - Plant Modifications

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

(4 Samples)

The inspectors evaluated the following temporary or permanent modifications:

(1) temporary modification of the electrical insulating properties affecting reactor core isolation cooling exhaust vacuum breaker outboard isolating valve

(2) permanent modification and replacement of 'A' diesel driven fire pump

(3) permanent modification of emergency reserve aux transformer load tap changer motor and over-volt protection

(4) permanent modification of emergency reserve aux transformer static volts reactive compensator

71111.19 - Post-Maintenance Testing

Post-Maintenance Test Sample (IP Section 03.01) (5 Samples 1 Partial)

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

(1) Work Order 5109314-16, "Reactor Core Isolation Cooling Exhaust Vacuum Breaker Outboard Isolation Valve Post-Maintenance Test Activities to Verify Operability" (2) (Partial)

Work Order 4982387-01, "'A' Fire Pump Post Replacement Test Activities to Verify Functionality"

(3) Work Order 4982387-01, "'B' FLEX Diesel Generator Output Breaker Following Replacement to Verify Functionality"

(4) Work Order 4900885-07, "Emergency Reserve Aux Transformer Load Tap Changer Motor Post-Maintenance Test Following Replacement"

(5) Work Order 4912019-02, "Emergency Reserve Aux Transformer Startup and 1E Bus Shift Following Short Term Modification Solution"

(6) Work Order 5069172-02, "Fuel Pool Cooling Pump 'B' Post-Maintenance Test Following Pump Seal Repair"

71111.20 - Refueling and Other Outage Activities

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

(1) (Partial)

The inspectors evaluated Refueling Outage C1R20 activities from September 27, 2021 to September 30, 2021.

71111.22 - Surveillance Testing

The inspectors evaluated the following surveillance tests:

Surveillance Tests (other) (IP Section 03.01)

(1) CPS 2007.01, ERAT mechanically switched capacitor bank system post-modification testing on September 19, 2021

(2) CPS 9000.06, reactor coolant and vessel metal/pressure/temperature limit logs on

September 29, 2021 FLEX Testing (IP Section 03.02) (1 Sample)

(1) 'B' flex diesel generator full load testing on August 11, 2021

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:

Eval No. 20-73 Emergency Action Levels for Clinton Station, EP-AA-1003, Addendum 3 This evaluation does not constitute NRC approval.

71114.06 - Drill Evaluation

Drill/Training Evolution Observation (IP Section 03.02) (2 Samples)

The inspectors evaluated:

(1) emergency preparedness drill on September 2, 2021

(2) emergency preparedness drill on September 8,

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) ===

(1) July 1, 2020 through June 30, 2021

MS09: Residual Heat Removal Systems (IP Section 02.08) (1 Sample)

(1) July 1, 2020 through June 30, 2021

MS10: Cooling Water Support Systems (IP Section 02.09) (1 Sample)

(1) July 1, 2020 through June 30, 2021

BI02: RCS Leak Rate Sample (IP Section 02.11) (1 Sample)

(1) July 1, 2020 through June 30, 2021

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 multiple issues with 1E51F077, reactor core isolation cooling exhaust vacuum breaker outboard isolation valve, position during quarterly testing that might be indicative of a more significant safety issue.

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

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

(1) closing of 1E51F063 for troubleshooting drywell unidentified leakage (2) (Partial)reactor coolant sulfate increase following down power

INSPECTION RESULTS

Minor Performance Deficiency 71152 Minor Performance Deficiency: The inspectors performed a review of plant issues, particularly those entered into the licensee's corrective action program, associated with the indication and positioning of 1E51-F077, reactor core isolation cooling exhaust vacuum breaker outboard isolation valve, per 9054.02. Valve 1E51-F077 is required to isolate containment during a design basis accident. A failure to isolate the containment penetration could result in exceeding radioactive release rates.

Consecutive quarters during this surveillance identified an issue with positioning the valve into the closed position. Each time, the valve issue was inspected and resolved to be operable with no additional maintenance required. The final problem identification effort identified a torque switch that is only present when the test circuit is in use. The failure to prioritize the intermittent failure mechanism of this valve in the test mode extended unavailability of the system and overall risk impact to the plant, which also impacted the performance of preventative and corrective maintenance on other systems during these troubleshooting efforts.

The inspectors determined the licensee failed to perform an adequate risk assessment required by WC-AA-101, "On Line Work Control Process," Section 4.11, which states, "During the planning and scheduling process, the following factors should be considered when assessing risk," to include the effect of performing elevated operational risk activities. Specifically, the work process did not include the identification and management of risk commensurate to the work such that multiple unsuccessful efforts were incurred to resolve this issue. Each such case delayed other necessary scheduled maintenance that moved the lower priority maintenance out of the weekly schedule to accommodate the unforeseen recurrent risk of the emergent 1E51-F077 failure. The NUREG 2165 behavior of issues was identified as WP.1 Work Management, the organization implements a process of planning, controlling, and executing work activities such that nuclear safety is the overriding priority was identified. Corrective Action Request 4435094, 1E51-F077 Will Not Stroke Closed IAW 9054.02, appropriately assessed the risk impact on system out of service time as well as the impact to other work week activities. This assessment led to the proper and final problem identification and resolution of this reoccurring issue.

Screening: The inspectors determined the performance deficiency was minor. The mitigating systems cornerstone objectives were not adversely affected because the overall corrected risk assessment would not result in a higher licensee-established risk category and would not require additional risk-management actions under licensee procedures.

Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power.

Observation: Closing of 1E51F063 for Troubleshooting Drywell Unidentified 71152 Leakage The inspectors performed a detailed review of Action Request 4394349, "Closing of 1E51F063 for Troubleshooting Drywell Unidentified Leakage."

The sample was selected as a potential degradation of the reactor core isolation cooling drywell inboard steam isolation valve with the valve electronically torqued on its open seat. The function of the 1E51F063, in combination with other accident mitigation systems, is to limit fission product release during and following postulated design basis accidents to within limits. Primary containment isolation within the time limits specified for those valves designed to close automatically ensures that the release of radioactive material to the environment will be consistent with the assumptions used in the analyses for a design basis accident.

The licensee's evaluation of unidentified leakage in the drywell increasing determined one possible source for the leakage was through the packing gland on the 1E51F063 valve. As a contingency action, an evaluation, Engineering Change 631686 R/001, was performed to determine if it was acceptable for the electrical maintenance department to electrically backseat the 1E51F063 in an effort to mitigate concerns due to the possible packing gland leakage. The electrical backseating was performed by the electrical maintenance department in accordance with MA-AA-723-303, Procedure for Electrically Backseating Motor-Operated Valves Remotely from a Motor Control Center (Reference 1). Per 3.3.1 of the procedure, an engineering evaluation was required to demonstrate the acceptability of electrically backseating the affected motor-operated valve prior to performing MA-AA-723-303. The evaluation documented that it was permissible and considered the effect of electrical backseating on Technical Specifications and whether inservice testing from the backseat was required. Work planning received engineerings recommendation for post-maintenance testing following the backseating activity.

On January 6, 2021, the 1E51F063 was cycled closed and then electrically torqued to its open seat. A prompt drop of approximately 0.03 psi [pound-force per square inch] concurrent with the closed indication on the valve, and then resumed the normal increasing trend. The level indication showed leakage decreasing from 0.78 gallons per minute (gpm) to 0.56 gpm over approximately a 1-hour period. Leakage continued to trend down over the next 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and stabilized at approximately 0.47 gpm. Based on the results, the station made the decision to proceed with electrically backseating the valve to isolate the packing. Upon completion of the evolution, unidentified drywell leakage lowered and stabilized out to 0.14 gpm for the duration of the plant cycle.

The inspectors identified no performance issues with the engineering calculation assumptions or implementation of the overall effort. Testing of the 1E51F063 during the plant refueling shutdown on September 27, 2021, demonstrated acceptable performance of the valve to close within the required time.

EXIT MEETINGS AND DEBRIEFS

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

On October 14, 2021, the inspectors presented the integrated inspection results to Mr. T. Chalmers, Site Vice President, and other members of the licensee staff.

On October 1, 2021, the inspectors presented the EPlan and EAL change inspection results to Mr. D. Moore, Senior Manager, Emergency Preparedness, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.04 Procedures CPS High Pressure Core Spray Valve Lineup 11b

3309.01V001

CPS 4610V Bus 1A1 Outage Restoration Electrical Lineup 4c

3514.01E005

CPS Remote Shutdown Panel - Hard Card 'A' 0c

4003.01H003

71111.05 Fire Plans CPS 723 - 778 Dry Well: Prefire Plan 5

1893.04M200

CPS 712' Diesel Generator; Division 1 Diesel Fuel Tank Room 5b

1893.04M501 Prefire Plan

CPS 712' Diesel Generator; Division 2 Diesel Fuel Tank Room 6a

1893.04M502 Prefire Plan

71111.06 Calculations 3C10-0485-001 Internal Flooding Analysis 10

Procedures CPS 4304.01 Flooding 6e

71111.13 Work Orders WO 4900885 Emergency Reserve Aux Transformer Static Volts Reactive 0

Compensator Modification

WO 5069172 Fuel Pool Cooling Pump 'B' Degraded Seal Repair 0

WO 5109314-01 Reactor Core Isolation Cooling Exhaust Vacuum Breaker 0

Outboard Isolation Valve Torque Switch Emergent

Maintenance

WO 5177741 Emergency Reserve Aux Transformer Load Tap Changer 0

Motor Replacement

71111.15 Corrective Action AR 4448556 ERAT LTC Failed to Control Voltage Within the Required 09/25/2021

Documents Band

Corrective Action AR 4427652 1E51-F077 Will Not Stroke Closed IAW 9054.02 07/15/2021

Documents

Resulting from

Inspection

Work Orders WO 5064723 Outage Contingent Repair Work Order for SRM 'A' 0

71111.18 Engineering EC 625900 'A' Fire Pump Replacement 0

Changes EC 634673 1AP74E-12D Tape Repair for Control Circuit 0

71111.19 Work Orders WO 4900885-07 Emergency Reserve Aux Transformer Load Tap Changer 08/31/2021

Inspection Type Designation Description or Title Revision or

Procedure Date

Motor Post Maintenance Test Following Replacement

WO 4912019-02 Emergency Reserve Aux Transformer Startup and 1E Bus 09/01/2021

Shift Following Short Term Modification Solution

WO 4982387-01 'A' Fire Pump Post Replacement Test Activities to Verify 0

Functionality

WO 5069172-02 1FC02PB Contingent Repair of Pump 09/30/2021

WO 5109314-16 Reactor Core Isolation Cooling Exhaust Vacuum Breaker 09/27/2021

Outboard Isolation Valve Post Maintenance Test Activities to

Verify Operability

71111.22 Procedures CPS 2007.01 ERAT Mechanically Switched Capacitor (MSC) Bank System 0b

Post Modification Testing

CPS 9000.06 Reactor Coolant and Vessel Metal/Pressure/Temperature 32d

Limit Logs

CPS Heat Up/Cooldown, Inservice Leak and Hydrostatic Testing 30b

9000.06D001 30 Minute Temperature Log

Work Orders WO 5172516-03 Flex - Diesel Generator Functional 08/11/2021

71114.04 Miscellaneous Eval 20-73 Emergency Action Levels for Clinton Station, EP-AA-1003, 09/21/2020

Addendum 3

71114.06 Procedures CL-PI-21-03, Scenario Information 09/02/2021

Section 2

CL-PI-21-03, Scenario Information 09/08/2021

Section 2

71152 Corrective Action AR 4394349 Result of Closing 1E51F063 01/06/2021

Documents AR 4435094 1E51-F077 Will Not Stroke Closed IAW 9054.02 07/15/2021

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