IR 05000336/2023003

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Integrated Inspection Report 05000336/2023003 and 05000423/2023003
ML23310A003
Person / Time
Site: Millstone  Dominion icon.png
Issue date: 11/06/2023
From: Matt Young
NRC/RGN-I/DORS
To: Carr E
Dominion Energy
References
05000336/2023003, 05000423/2023003, IR 2023003
Download: ML23310A003 (1)


Text

November 6, 2023

SUBJECT:

MILLSTONE POWER STATION, UNITS 2 AND 3 - INTEGRATED INSPECTION REPORT 05000336/2023003 AND 05000423/2023003

Dear Eric Carr:

On September 30, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station, Units 2 and 3. On October 12, 2023, the NRC inspectors discussed the results of this inspection with Michael O'Connor, 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 Millstone Power Station, Units 2 and 3.

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 Millstone Power Station, Units 2 and 3. 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 (10 CFR) 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, Matt R. Young, Chief Projects Branch 2 Division of Operating Reactor Safety

Docket Nos. 05000336 and 05000423 License Nos. DPR-65 and NPF-49

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000336 and 05000423

License Numbers:

DPR-65 and NPF-49

Report Numbers:

05000336/2023003 and 05000423/2023003

Enterprise Identifier: I-2023-003-0034

Licensee:

Dominion Energy Nuclear Connecticut, Inc.

Facility:

Millstone Power Station, Units 2 and 3

Location:

Waterford, CT

Inspection Dates:

July 1, 2023 to September 30, 2023

Inspectors:

J. Fuller, Senior Resident Inspector

E. Allen, Resident Inspector

E. Bousquet, Resident Inspector

K. Mooney, Acting Resident Inspector

N. Eckhoff, Health Physicist

M. Patel, Senior Reactor Inspector

Approved By:

Matt R. Young, Chief

Projects Branch 2

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Millstone Power Station, Units 2 and 3, 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 non-cited violation (NCV) is documented in report section: 71111.0

List of Findings and Violations

3A Emergency Diesel Generator Overspeed Switch Not Properly Secured Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000423/2023003-01 Open/Closed

[P.2] -

Evaluation 71111.04 The inspectors identified a finding of very low safety significance (Green) and associated NCV of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion XVI,

Corrective Action, when the licensee failed to identify a condition adverse to quality related to the 'A' emergency diesel generator (EDG) at Unit 3. Specifically, the licensee failed to identify that the overspeed switch was not properly secured to its mounting bracket, which could cause the EDG to inadvertently trip during a seismic event or during the EDGs 30-day mission time.

Additional Tracking Items

None.

PLANT STATUS

Unit 2 began the inspection period increasing reactor power after its planned refueling outage.

Unit 2 operated at rated thermal power from July 4 to July 11, 2023. On July 11, Unit 2 reduced power to approximately 86 percent to troubleshoot and repair the turbine driven auxiliary feedwater steam supply check valve from the #2 steam generator. Unit 2 returned to rated thermal power on July 26, 2023. On September 6, 2023, Unit 2 reduced power to approximately 82 percent due to condenser fouling. On September 11, 2023, Unit 2 decreased reactor power from 82 to 68 percent for removal and cleaning of the condenser waterbox and replacement of the 'C' circulating water pump. Unit 2 raised power to 92 percent on September 17, 2023, after cleaning the condenser waterbox. On September 20, 2023, Unit 2 decreased power to 60 percent due to issues with the 'A' circulating water pump and a 'C' intake bay outage. On September 23, 2023, Unit 2 raised power to 80 percent after cleaning the 'A' condenser waterbox and continued replacement of the 'C' circulating water pump. On September 24, 2023, Unit 2 reduced power back to 68 percent due to continued issues with the 'A' circulating water pump. Unit 2 returned to rated thermal power on October 5, 2023, and remained at or near rated thermal power for the remainder of the inspection period.

Unit 3 began the inspection period raising reactor power after an unplanned outage to repair a ground fault on the main generator output breaker. Unit 3 operated at rated thermal power from July 3 to August 31, 2023. On September 1, 2023, Unit 3 reduced power to 92 percent due to a feedwater heater transient. On September 2, 2023, Unit 3 reduced power to 80 percent due to thermal well leakage associated with a temperature element for the first point feedwater heater.

Unit 3 returned to rated thermal power on September 8, 2023. On September 22, 2023, Unit 3 reduced power to 85 percent to support service water pipe inspection. Unit 3 returned to rated thermal power on September 23, 2023, 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 performed activities described in IMC 2515, Appendix D, Plant Status, conducted routine reviews using IP 71152, Problem Identification and Resolution, observed risk-significant activities, and completed on-site portions of IPs. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

REACTOR SAFETY

71111.04 - Equipment Alignment

Partial Walkdown (IP Section 03.01) (2 Samples)

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

(1) Unit 3 chemical volume control system from volume control tank to containment wall, including chemical volume control charging pumps and supporting systems, on July 31, 2023
(2) Unit 3 control building chiller room, control building chilled water, and service water piping from August 30 to September 11, 2023

71111.05 - Fire Protection

Fire Area Walkdown and Inspection (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 3 engineered safety features building, south air conditioning unit cubicle, on the 36'-6" elevation (fire area ESF-11) on July 21, 2023
(2) Unit 2 waste gas compressor and surge tank area (fire area A-1F) and boric acid batch tank (fire area A-12A) on July 24, 2023
(3) Unit 3 east motor control center and rod control area cable tunnel pit on the 4'-6" and 24'-6" elevations (fire area AB-5) on August 7 and 8, 2023
(4) Unit 3 turbine building equipment mezzanine on the 38'-6" elevation (fire area TB-2, Zone C) on August 18, 2023
(5) Unit 3 west switchgear area (fire area CB-1), east switchgear area (fire area CB-2),and cable spreading area (fire area CB-8) after identification of missing fire seals on August 29, 2023

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

(1) The inspectors evaluated the on-site fire brigade training and performance during an unannounced fire drill on July 31, 2023

71111.06 - Flood Protection Measures

Flooding (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated internal flooding mitigation protections in the Unit 3 control building chiller room (flood compartment CB-13) on August 30 and September 11, 2023

71111.07A - Heat Exchanger/Sink Performance

Annual Review (IP Section 03.01) (1 Sample)

The inspectors evaluated readiness and performance of:

(1) Unit 2 'B' EDG heat exchangers from July 18 to 20, 2023

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance

Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (2 Samples)

(1) The inspectors observed and evaluated licensed operator performance in the Unit 2 control room during control element assembly partial movement testing on August 10, 2023.
(2) The inspectors observed and evaluated licensed operator performance in the Unit 3 control room for reactivity manipulations and feedwater heater control during periods of heightened activity following an unplanned down power to 92 percent on September 1, 2023.

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

(1) The inspectors observed and evaluated licensed operator requalification training in the Unit 3 simulator on August 29, 2023.
(2) The inspectors observed and evaluated licensed operator requalification training in the Unit 2 simulator on September 19, 2023.

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) Units 2 and 3 periodic evaluations for the period of July 1, 2021, through December 31, 2022, as required by 10 CFR 50.65(a)(3)
(2) Unit 3 charging pump area discharge damper, 3HVR*MOD49B, failure on July 12, 2023

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management (IP Section 03.01) (2 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) Units 2 and 3 high risk plan and associated mitigating actions for maintenance on the

'A' fire water storage tank from August 15 to 21, 2023

(2) Protected equipment walkdown due to elevated risk associated with the failure of the Unit 2 'C' circulating water pump and the Unit 3 'C' service water pump strainer on September 14, 2023

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 3 operability evaluation for the '3B' motor driven auxiliary feedwater pump outboard motor oil leak on June 22, 2023 (CR1231577 and CR1230446)
(2) Unit 2 turbine driven auxiliary feedwater pump operability determination for isolation of steam traps and associated compensatory action on July 12, 2023 (CR1232437)
(3) Unit 3 'B' train of emergency core cooling system inoperable due to a degraded damper associated with the ventilation support system for the 'B' charging pump on July 12, 2023 (CR1232966)
(4) Unit 3 operational decision-making evaluation for the reserve station service transformer due to degrading trend in dissolved hydrogen on July 21, 2023 (CR1233146)
(5) Unit 3 turbine driven auxiliary feedwater control valve cycled closed and re-opened without demand signal on September 4, 2023 (CR1236949)

71111.18 - Plant Modifications

Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (1 Sample)

The inspectors evaluated the following temporary or permanent modifications:

(1) Temporary replacement of Unit 2 swing check valve (2-MS-4B) with a normally open nozzle check valve (MP2-23-01077)

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 (IP Section 03.01) (7 Samples)

(1) Unit 2 auxiliary feedwater supply check valve (2-FW-12B) after overhaul on May 8, 2023 (WO53102980392)
(2) Unit 3 'A' EDG operability test following replacement of the overspeed limit switch on July 14, 2023 (WO53203385226)
(3) Unit 3 containment recirculation spray system cooler outlet valve stroke test after removal and reinstallation of the SWP*MOV57B control breaker from July 19 to 21, 2023 (WO53102708449)
(4) Unit 3 fan 5B engineered safety features building emergency ventilation system test following repairs to the breaker on August 13, 2023 (WO53203387447, WO53203387128)
(5) Unit 2 service water valve 3.2B (turbine building service water isolation valve) after repair from September 4 to12, 2023 (WO53203388764)
(6) Unit 3 service water piping to the 'B' HVK chiller (control building temperature control system) after new pipe was welded in place on September 13, 2023 (WO53203388069)
(7) Unit 3 'D' containment recirculation system after planned maintenance on the heat exchanger service water supply relief valve on September 14, 2023 (WO53203346725)

Surveillance Testing (IP Section 03.01) (3 Samples)

(1) Unit 3 charging pump cooling pump (3CCE*P1A) operational readiness test on August 1, 2023
(2) Unit 2 'A' EDG loss of load test (SP 2613I-001) on August 3, 2023
(3) Unit 3 semiannual protection set cabinet II operational test on the reactor protection system on September 30, 2023

71114.06 - Drill Evaluation

Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01) (2 Samples)

(1) Unit 3 emergency planning drill and event classification in the simulator and emergency operations facility on July 25, 2023
(2) Unit 2 emergency preparedness drill on August 23,

RADIATION SAFETY

71124.08 - Radioactive Solid Waste Processing and Radioactive Material Handling, Storage,

and Transportation

Radioactive Material Storage (IP Section 03.01)

The inspectors evaluated the licensees performance in controlling, labeling, and securing the following radioactive materials:

(1) Warehouse 9 radwaste storage facility
(2) Millstone radwaste reduction facility

Radioactive Waste System Walkdown (IP Section 03.02) (2 Samples)

The inspectors walked down the following accessible portions of the solid radioactive waste systems and evaluated system configuration and functionality:

(1) Unit 2 solid radioactive waste system
(2) Unit 3 liquid radioactive waste system

Waste Characterization and Classification (IP Section 03.03) (2 Samples)

The inspectors evaluated the following characterization and classification of radioactive waste:

(1) Classification of the Unit 3 2022 Dry Active Waste Analysis
(2) Classification of the Unit 2 2021 Spent Resin Tank Liner Analysis

Shipping Records (IP Section 03.05) (4 Samples)

The inspectors evaluated the following non-excepted radioactive material shipments through a record review:

(1) Radioactive waste shipment number 23-036, UN3321, radioactive material 7, low specific activity (LSA-II)
(2) Radioactive waste shipment number 23-046, UN3321, radioactive material 7, low specific activity (LSA-II)
(3) Radioactive waste shipment number 23-071, UN3321, radioactive material 7, low specific activity (LSA-II)
(4) Radioactive waste shipment number 23-057, UN3321, radioactive material 7, low specific activity (LSA-II)

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification

The inspectors verified licensee performance indicators submittals listed below:

MS05: Safety System Functional Failures (IP Section 02.04)===

(1) Unit 2, July 1, 2022 through June 30, 2023
(2) Unit 3, July 1, 2022 through June 30, 2023

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

(1) Unit 2, July 1, 2022 through June 30, 2023
(2) Unit 3, July 1, 2022 through June 30, 2023

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

(1) Unit 2, July 1, 2022 through June 30, 2023
(2) Unit 3, July 1, 2022 through June 30, 2023

MS08: Heat Removal Systems (IP Section 02.07) (2 Samples)

(1) Unit 2, July 1, 2022 through June 30, 2023
(2) Unit 3, July 1, 2022 through June 30, 2023

MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)

(1) Unit 2, July 1, 2022 through June 30, 2023
(2) Unit 3, July 1, 2022 through June 30, 2023

MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)

(1) Unit 2, July 1, 2022 through June 30, 2023
(2) Unit 3, July 1, 2022 through June 30, 2023

===71152A - Annual Follow-up Problem Identification and Resolution

Annual Follow-up of Selected Issues (Section 03.03)===

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

(1) Corrective actions associated with digital rod position indication (DRPI) urgent and non-urgent alarms (CR1204084)

71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02)

(1) The inspectors reviewed the licensees corrective action program for potential adverse trends in the Unit 3 engineered safety features building ventilation equipment performance and reliability that might be indicative of a more significant safety concern.

71153 - Follow-up of Events and Notices of Enforcement Discretion Reporting (IP Section 03.05)

(1) Unit 3 event notification (EN) retraction for EN 56620 associated with the 'B' charging system pump ventilation system on July 31,

INSPECTION RESULTS

3A Emergency Diesel Generator Overspeed Switch Not Properly Secured Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000423/2023003-01 Open/Closed

[P.2] -

Evaluation 71111.04 The inspectors identified a finding of very low safety significance (Green) and associated NCV of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, when the licensee failed to identify a condition adverse to quality related to the 'A' EDG at Unit 3. Specifically, the licensee failed to identify that the overspeed switch was not properly secured to its mounting bracket, which could cause the EDG to inadvertently trip during a seismic event or during the EDGs 30-day mission time.

Description:

On July 11, 2023, during a routine walkdown of the Unit 3 EDGs, the inspectors identified that the safety-related, overspeed switch for the 3A EDG was not properly secured to its mounting bracket as indicated by a noticeable gap in the contact between the limit switch arm and the overspeed knob. There was also a noticeable gap between the upper and lower parts of the limit switch housing. The inspectors questioned whether this condition could adversely impact the reliability of the EDG. The licensee wrote CR1232887 and created WO53203385226 to further investigate and repair or replace the switch. The condition report noted that the mounting screw had come loose most likely due to vibration. Moreover, the licensee noted that this same switch was found loose on March 2, 2022 (CR1192679) and retightened. The 3A EDG had successfully been run on July 9, 2023, 2 days prior to the identification of this issue.

On July 13, 2023, the licensee tagged out the EDG and entered Technical Specification (TS)3.8.1.1.b. for one inoperable EDG. Upon further review, the licensee-identified that the mounting screw was completely stripped and declared the EDG inoperable, because the condition of the overspeed switch could not ensure the 3A EDG could perform its safety function after a design basis earthquake or during the EDGs 30-day mission time. Condition report, CR1233096, was written to document this additional information, and the licensee replaced the switch.

Following the switch replacement, the licensee verified proper operation of the switch with post-maintenance testing and verified that the 3B EDG overspeed switch was properly secured.

The EDG is designed to withstand the effects of natural phenomenon such as earthquakes without loss of capability to perform its safety function. As described by ETE-MP-2015-1083, the mission time for the EDGs is 30 days. Mission time is defined as that period of time when safety-related equipment is expected to operate post-accident without preventive or corrective maintenance. The overspeed switch is activated by movement of the overspeed valve and gives a pneumatic signal that will shut down the EDG when it is running. When the switch was found to be secured with only one of two mounting screws, its seismic qualification was questioned.

The inspectors noted that a plant equipment operator identified the same limit switch fastener was loose on March 2, 2022, during rounds. This was documented in CR1192679, and the screw was tightened on March 3, 2022. The condition report stated that the screw had most likely come loose due to vibration. When tightening the screw, the licensee noted in the work order that the screw did not feel stripped. No additional corrective actions were taken to investigate the cause of the loose screw or to check that it didnt loosen after additional engine operation. From March 2, 2022, to July 11, 2023, the 3A EDG recorded approximately 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br /> of satisfactory performance during routine testing; therefore, the inspectors noted that the EDG would have operated for its 24-hour probabilistic risk assessment mission time.

The licensee performed a maintenance rule functional failure evaluation (CA12025803) and a structural assessment to determine whether the limit switch would have remained mounted to the base with one screw when subjected to a Safe Shutdown Earthquake. The licensee determined that the 3A EDG overspeed switch would remain sufficiently secured to the base after a seismic event.

The inspectors noted that Section 12, Equipment Monitoring and Routine Inspections, of 2, Shift Operations, of administrative procedure OP-AA-100, Conduct of Operations, Revision 46, states in part, that Each shift operator performs a thorough, general inspection of assigned areas. Abnormal conditions are corrected on the spot, or the proper corrective action initiated and reported to the Shift Manager. Although it is unknown exactly when the screw became stripped, the inspectors determined that it most likely occurred on July 9, 2023, when the 3A EDG was operated for routine surveillance testing.

Because the same screw had previously come loose, the inspectors determined that it was reasonable for the licensee to foresee and correct this condition prior to the NRCs identification of the issue on July 11, 2023.

Corrective Actions: The licensee entered the issue into its corrective action program as CR1232887 and CR1233096, replaced the overspeed limit switch under WO53203385226, and performed extent of condition inspections of the other EDGs.

Corrective Action References: CR1232887, CR1233096, CA12025803

Performance Assessment:

Performance Deficiency: The inspectors determined that the licensees failure to perform thorough inspections of plant areas, as required by procedures OP-AA-100, resulted in its failure to identify the loose overspeed limit switch housing, a condition adverse to quality, in a timely manner.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment Performance attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the as-found condition of the overspeed limit switch resulted in reasonable doubt about the ability of the switch to perform its function after a seismic event or during the EDGs 30-day mission time. This reduced assurance in the reliability of the 3A EDG. As described by Example 3.e in IMC 0612, Appendix E, regardless of the conclusion of the operability determination, there was reasonable doubt about the seismic qualification because the overspeed microswitch was not properly secured in accordance with the Millstone maintenance procedures for threaded fasteners and the licensee had to replace the switch to resolve the seismic concern.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process for Findings At-Power. The finding is a deficiency affecting the qualification of a mitigating SSC, but the SSC maintained its operability and probabilistic risk assessment functionality; therefore, it screens to Green.

Cross-Cutting Aspect: P.2 - Evaluation: The organization thoroughly evaluates issues to ensure that resolutions address causes and extent of conditions commensurate with their safety significance. Specifically, the licensee did not thoroughly evaluate the cause of the loose mounting screw in March 2022 to ensure that tightening the screw would correct the condition adverse to quality. The licensee did not remove the screws in March 2022 to determine whether they showed any sign of vibration induced damage.

Enforcement:

Violation: 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective equipment, and non-conformances are promptly identified and corrected.

Contrary to the above, from approximately July 9 to 11, 2023, the licensee did not identify and correct a condition adverse to quality associated with the 3A EDG. Specifically, the overspeed switch was not properly secured to its mounting bracket, which could have adversely impacted the ability of the EDG to perform its safety function after a seismic event or during its 30-day mission time.

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

Licensee-Identified Non-Cited Violation: Unit 2 Control Room Ventilation Access Door Panel Discovered Open 71111.04 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: 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, states in part, Measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and non-conformances are promptly identified and corrected. Section 3.5.3 of Dominion procedure PI-AA-200, Corrective Action, Revision 41, states in part, NOTE: Corrective actions are completed in a timely manner commensurate with issue significance/priority.

Contrary to the above, between October 23, 2018, and July 25, 2023, the licensee failed to correct a condition adverse to quality associated with the design of the closure latch of the 'B' control room air conditioning supply fan filter housing cover. Specifically, CR1108287 written on October 23, 2018, identified that the filter housing cover came unlatched. The licensee created a corrective action to improve the design of the upper cover levers, since the original design had the potential to vibrate or be bumped downward, which could cause the filter housing door to open. However, the licensee did not implement the corrective action, and on July 25, 2023, the filter housing cover came open, rendering both trains of the control room air conditioning system inoperable due to an inoperable control room envelope boundary.

Significance/Severity: Green. The inspectors evaluated this finding using IMC 0609.04, Initial Characterization of Findings, and IMC 0609, Appendix A, Exhibit 3, Barrier Integrity Screening Questions. The inspectors determined that the finding impacted the control room barrier integrity but, based on a detailed engineering evaluation completed by the licensee, did not represent a degradation of the barrier for radiological exposure to operators and did not represent degradation of the barrier against smoke or a toxic atmosphere. Therefore, the finding was of very low safety significance (Green).

Corrective Action References: CR1233966

Observation: Digital Rod Position Indication Urgent and Non-Urgent Alarms 71152A The inspectors reviewed condition reports associated with DRPI urgent and non-urgent alarms for Unit 3. The inspectors reviewed the recent non-urgent failure alarm associated with control bank A, rod L11. For the L11 non-urgent failure alarm, troubleshooting was carried out, and the cause was identified as the cable degradation associated with the L11 coil stack. The inspectors reviewed the planned corrective action to replace the degraded cable during the upcoming outage, and they also reviewed the interim temporary modification to disable the non-urgent failure alarm. The inspectors also reviewed the temporary interim actions associated with monitoring other non-urgent DRPI alarms.

The inspectors did not identify any violations or performance deficiencies.

EXIT MEETINGS AND DEBRIEFS

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

  • On August 24, 2023, the inspectors presented the radioactive solid waste processing and radioactive material handling, storage, and transportation inspection results to Guy Blackburn, Plant Manager, and other members of the licensee staff.
  • On September 8, 2023, the inspectors presented the DRPI urgent and non-urgent alarms inspection results to Jigar Patel, Nuclear Licensing/Compliance, and other members of the licensee staff.
  • On October 12, 2023, the inspectors presented the integrated inspection results to Michael O'Connor, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

71111.04

Corrective Action

Documents

CR1216351

71111.05

Calculations

COMBLOAD-

01325M3

Addendum: AE

Revision 1

Corrective Action

Documents

CR1233350

CR1236540

Miscellaneous

Impairment Number 35688-23-H

Procedures

CM-AA-FP-101

Control of Combustible and Flammable Material

Revision 15

MP-PROC-ENG-

U3-24-FFS-

BAP01

Fire Fighting Strategies

Revision 001

Work Orders

203310565

71111.06

Corrective Action

Documents

CR1223325

Work Orders

203388069

71111.07A Corrective Action

Documents

CR1233155

Corrective Action

Documents

Resulting from

Inspection

CR1233485

Engineering

Evaluations

ETE-MP-2016-

1136

RBCCW HX Inspection Frequency and Allowable Tube

Plugging

Revision 0

Miscellaneous

Issuance of Amendment Re: Ultimate Heat Sink Action

Requirements (TAC No. MB0867)

05/31/2001

VTM 25203-650-

001

Rosemount Temperature Sensors

Procedures

SP 2670

Saltwater Cooled HX D/P Determination

Revision 019

Work Orders

203357231

71111.12

Self-Assessments PIR1218891

Maintenance Ruler (a)(3) Self-Assessment for the Period of

July 1, 2021 to December 31, 2022

71111.13

Corrective Action

Documents

CR1235591

Procedures

PROC-OPS-SFP

Fire Water Backup Supply Plan

Revision 08

WM-AA-301

High Risk Plan Actions

08/09/2023

Work Orders

53102851316

71111.15

Engineering

Evaluations

ETE-MP-2023-

2003

Unit 3 3FWA*HV36A Closed and Then Opened without

Operator Action

Revision 1

71111.18

Miscellaneous

MP2-23-01077

Temporary Replacement of 2-MS-4B Swing Check with a

Normally Open Nozzle Check Valve

Revision 0

Procedures

EN 21221

MP2 Check Valve Inspections

Revision 11

71111.24

Corrective Action

Documents

CR1232685

CR1235602

CR1235610

CR1235776

CR1236951

CR1239060

Engineering

Evaluations

ETE-MP-2021-

1067

Drift Evaluation to Support the U3 Protection Set

Surveillance Extension

Miscellaneous

MP-EVAL-STI-

M3-2020-001

U3 7300 Protection Set Frequency Extension

Revision 0

Procedures

SP 2610CS-3

Remote Position Indication IST: 2-FW-5A/5B, 2-FW-12A/B,

2-FW-44

04/30/2023

SP 2610CS-5

AFW Pumps Discharge Check Valves Stroke IST

05/08/2023

SP 3443B21

Protection Set Cabinet II Operational Test

Revision 018

SP 3443B21-001

Protection Set Cabinet II Operational Test Data Sheet

Revision 29

and

Revision 30

SP 3626.3

3SWP*MOV57B and 3SWP*MOV57D RSS Cooler Outlet

Stroke Test

Revision 17

Work Orders

53102708449

203343600

203370438

71114.06

Miscellaneous

MAUG23FD

Full Scale Drill, Radiation Monitoring/HP Drill

08/23/2023

71152A

Corrective Action

Documents

CR1160151

CR1164375

CR1164639

CR1199806

CR1204084

CR1204866

CR1206743

CR345367

CR529307

CR564642

Miscellaneous

2309121155

CO Temp Log for DRPI Checks

09/10/2023

Procedures

AOP 3552

Malfunction of the Rod Drive System

Revision 018

OP 3353.MB4C

Main Board 4C Annunciator Response

Revision 025

71152S

Corrective Action

Documents

CA11265394

CR1106468

CA12053964

CR1150811

CR1236710

Drawings

212-26952

P&I Diagram ESF and MSV Building Ventilation

Revision 22

Miscellaneous

S3-EV-01-0015

ESF & HR Building Radiation Dose Calculation

Revision 0

Work Orders

203368231