IR 05000336/2022003

Integrated Inspection Report 05000336/2022003 and 05000423/2022003

ML22318A030
Person / Time
Site:	Millstone
Issue date:	11/14/2022
From:	Matt Young NRC/RGN-I/DORS
To:	Stoddard D Dominion Energy
References
IR 2022003
Download: ML22318A030 (1)

Text

November 14, 2022

SUBJECT:

MILLSTONE POWER STATION, UNITS 2 AND 3 - INTEGRATED INSPECTION REPORT 05000336/2022003 AND 05000423/2022003

Dear Daniel Stoddard:

On September 30, 2022, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station, Units 2 and 3. On October 27, 2022, the NRC inspectors discussed the results of this inspection with Michael J. O'Connor, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.

Three findings of very low safety significance (Green) are documented in this report. Two of these findings involved violations of NRC requirements. We are treating these violations as non-cited violations (NCVs) consistent with Section 2.3.2 of the Enforcement Policy.

If you contest the violation or the significance or severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN:

Document Control Desk, Washington, DC 20555- 0001; with copies to the Regional Administrator, Region I; the Director, Office of Enforcement; and the NRC Resident Inspector at Millstone Power Station, Units 2 and 3.

If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement 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 Co ntrol 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 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: 05000336/2022003 and 05000423/2022003

Enterprise Identifier: I-2022-003- 0037

Licensee: Dominion Energy Nuclear Connecticut, Inc.

Facility: Millstone Power Station, Units 2 and 3

Location: P.O. Box 128, Waterford, CT 06385

Inspection Dates: July 1, 2022, to September 30, 2022

Inspectors:

E. Allen, Resident Inspector E. Bousquet, Resident Inspector J. Brand, Reactor Inspector S. Elkhiamy, Senior Project Engineer J. Fuller, Senior Resident Inspector K. Mangan, Senior Reactor Inspector D. Werkheiser, Senior Reactor Analyst S. Wilson, Senior Health Physicist

Approved By: Matt R. Young, Chief Projects Branch 2 Division of Operating Reactor Safety

Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at 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.

List of Findings and Violations

Failure to Correct Degraded Isolation Dampers Associated with the Unit 3 Supplemental Leak Collection and Release System Cornerstone Significance Cross-Cutting Report Aspect Section Barrier Integrity Green [P.4] - Trending 71111.12 NCV 05000423/2022003-01 Open/Closed A finding of very low safety significance (Green) and an associated non-cited violation (NCV)of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, was self-revealed on April 6, 2022, when the 'B' train of the Unit 3 supplemental leak collection and release system (SLCRS) did not achieve the required drawdown resulting in a failure to meet Technical Specification (TS) 3.6.6.1, Supplementary Leak Collection and Release System. Specifically, the licensee did not assure that previously identified conditions adverse to quality, inadequate preventive maintenance (PM) procedures and inspection schedules associated with safety-related ventilation dampers, were corrected.

Failure to Establish Adequate Preventive Maintenance Strategy for Emergency Diesel Generator Exhaust Manifold Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.4] - Trending 71152A Systems FIN 05000423/2022003- 02 Open/Closed A finding of very low safety significance (Green) was self-revealed when operators manually shut down the '3A' emergency diesel generator (EDG) on July 16, 2022, and the '3B' EDG on July 25, 2022, when small fires were observed coming from under the exhaust manifold insulation during operational and post-maintenance testing. The licensee did not follow procedure ER-AA-PRS-1010, Preventive Maintenance Task Basis and Maintenance Strategy, when it did not initiate changes to maintenance strategies for the EDG exhaust manifolds based on corrective action program actions and industry operating experience.

Failure to Verify the Required Restoration Time of the Protected Service Water Pump Motor for a Postulated Probable Maximum Hurricane Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.1] - 71152A Systems NCV 05000336/2022003-03 Identification Open/Closed The inspectors identified a Green finding and associated NCV of 10 CFR Part 50, Appendix B,

Criterion III, "Design Control," because the licensee did not verify the adequacy of the design regarding the time to restore the protected service water (SW) pump motor during a postulated probable maximum hurricane (PMH).

Additional Tracking Items

Type Issue Number Title Report Section Status URI 05000336/2021010-03 Unit 2 Service Water 71152A Closed Restoration Time following a Design Basis External Flood

PLANT STATUS

Both Units 2 and 3 operated at or near rated thermal power for the entire 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.

71111.01 - Adverse Weather Protection

Impending Severe Weather (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the adequacy of the overall preparations to protect risk significant systems, at both units, from impending severe weather that had the potential for significant rainfall on September 5, 2022.

External Flooding (IP Section 03.03) (1 Sample)

(1) The inspectors evaluated that flood protection barriers, mitigation plans, procedures, and equipment were consistent with the licensees design requirements and risk analysis assumptions for coping with external flooding of the site fire pump enclosure on August 25, 2022.

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 2 instrument air system safety-related backup air supply on August 23 and 24, 2022

(2) Unit 3 accessible portions of the auxiliary feedwater system including demineralized water storage tank, piping, valves, and associated instrumentation on August 26, 2022

Complete Walkdown (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated system configurations during a complete walkdown of the Unit 2 'B' train 120-volt alternating current (AC) vital bus and 'B' train 125 -volt direct current bus on July 25 to 29, 2022.

71111.05 - Fire Protection

Fire Area Walkdown and Inspection (IP Section 03.01) (2 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 2 solid radwaste drumming storage area on the 14'-6" elevation (fire zone A-17)on August 1, 2022

(2) Unit 2 enclosure building filtration room EBFAS equipment area on the 14'-6" elevation (fire zone A-14D) on August 31, 2022

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

(1) The inspectors evaluated the onsite fire brigade performance during a small fire on the '3B' EDG exhaust manifold, which was quickly extinguished, on July 25, 2022.

71111.06 - Flood Protection Measures

Inspection Activities - Internal Flooding (IP Section 03.01) (1 Sample)

The inspectors evaluated internal flooding mitigation protections in the:

(1) Unit 2 'A' engineered safety features pump room 45'-6" elevation (flood zone A-8A) on July 7, 2022

71111.07A - Heat Exchanger/Sink Performance

Annual Review (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated readiness and performance of Unit 2 'C' reactor building closed cooling water heat exchanger on July 28, 2022.

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 alarm response to the power plant computer uninterruptible power supply and unplanned entry in TS action statements for 120V AC and 125V direct current (DC) power distribution on July 19, 2022. The inspectors observed and evaluated licensed operator performance in the Unit 2 control room during reactor building closed cooling water system trouble shooting and post-maintenance testing of the 'C' charging pump on July 27, 2022.

(2) The inspectors observed and evaluated operator performance in the Unit 3 control room during reactivity manipulations and shift turnover on September 1, 2022.

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

(1) The inspectors observed and evaluated licensed operator annual requalification exams in the Unit 3 simulator on August 30, 2022

(2) The inspectors observed and evaluated licensed operator annual requalification exams in the Unit 2 simulator on September 15, 2022

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) Unit 3 maintenance rule evaluation of the station blackout EDG failure to load on July 20, 2022 (CR1203990)

(2) Unit 3 'A' SLCRS fan (HVR*FN12A) tripped during 'B' SLCRS monthly surveillance resulting in an entry into TS 3.0.3 on July 21, 2022 (CR1204017 and CR1204109)

Quality Control (IP Section 03.02) (1 Sample)

The inspectors evaluated the effectiveness of maintenance and quality control activities to ensure the following structure, system, and component remains capable of performing its intended function:

(1) Control of the Unit 3 'C' component cooling water heat exchanger (3CCP*E1C) in long-term storage prior to installation on August 2, 2022 (WO53203236885)

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management (IP Section 03.01) (6 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 3 elevated risk associated with failure of the A' EDG to start on July 13, 2022 (CR1203517)

(2) Unit 2 increased risk due to thunderstorms in conjunction with elevated risk due to the

'A' reactor building component cooling water heat exchanger and 'B' EDG out of service on July 18, 2022 (WO53203320085 and WO53203338833)

(3) Unit 3 risk assessment and associated mitigating actions associated with station blackout EDG outage for maintenance activities on July 20, 2022 (WO53102819616)

(4) Unit 3 high risk plan for emergent entry into a 4-hour and 72-hour shutdown action statement associated with foreign material retrieval from the gearbox associated with

'B' containment recirculation system suction isolation valve (3RSS*MOV23B) on August 16, 2022 (CR1205650 and WO53203361560)

(5) Unit 3 high risk plan for planned work in switchyard that resulted in single path for generation on September 1, 2022

(6) Unit 2 elevated trip risk due to the 310 line out of service for optical ground wire pulls on September 24, 2022

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (8 Samples)

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

(1) Unit 3 'C train component cooling water pump due to oil leakage exceeding the 30-day mission time on June 30, 2022 (CR1202339)

(2) Unit 2 'A' EDG operability assessment due to degraded condition of flexible coupling on June 30, 2022 (CR1202655)

(3) Unit 2 'A' facility one control room air conditioning operability assessment due to abnormal pressure in the control room on July 6, 2022 (CR1202982)

(4) Unit 2 operability of the direct current bus (201B) due to DC switchgear temperature exceeding temperature limit on July 19, 2022 (CR1203841)

(5) Unit 3 station blackout EDG operability assessment due to output breaker trip during 2-hour loaded run on July 21, 2022 (CR1203990)

(6) Unit 3 prompt operability determination for pinhole through-wall leak in SW piping between 3SWP*V298 ('A' EDG heat exchanger return) and 3SWP*RO123A ('A' EDG cooler outlet restricting orifice) in the 'A' EDG enclosure on August 9, 2022 (CR1205299, CR1205369, CR1205386, and CR1206746)

(7) Unit 2 'A' train reactor building closed cooling water pump due to low oil level in bubbler August 11, 2022 (CR1204765)

(8) Unit 3 operational decision making for increased reactor coolant system leakage past the '3B' pressurizer power -operated relief valve and subsequent closure of the pressurizer power-operated relief block valve on August 19, 2022 (CR1206027 and CA11258470)

71111.19 - Post-Maintenance Testing

Post-Maintenance Test (IP Section 03.01) (9 Samples)

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

(1) Unit 2 'A' SW pump and facility 1 discharge check valve inservice test following the replacement of the 'A' SW pump discharge strainer flush valve (M22-SW-90A) on July 6, 2022 (WO53102773049)

(2) Unit 3 A EDG after replacement of the governor after an overspeed trip on July 13, 2022 (CR1203517)

(3) Unit 2 motor control center load center breaker cycling (M2B6115) following molded case breaker megger and resistance checks on July 25, 2022 (WO53102393249)

(4) Unit 3 containment recirculation system motor operated valve 3RSS*MOV23B/L after removal of tie wrap from the motor operator, which was disassembled on August 16, 2022 (CR1205650 and WO53203361560)

(5) Unit 3 repair of '3A' feed regulating bypass valve after failure on August 31, 2022 (CR1206530 and WO53203362890)

(6) Unit 3 engineered safeguards building air conditioning unit after heat exchanger inspection and replacement of compressor mechanical seal on September 2, 2022 (WO53203341803 and WO53203363095)

(7) Unit 3 SW heat exchangers fouling determination following replacement of the 'B' EDG engine air cooler drain valve (3SWP*V111) on September 21, 2022 (WO53203364279)

(8) Unit 2 containment isolation valve stroke, timing, and supplemental position verification indication in-service test on 2-AC-528 following repair of radiation monitor (RM-8262A/B) and return isolation valve (2-AC-528) on September 23, 2022 (WO53203364302)

(9) Unit 2 engineered safety features actuation surveillance of the west DC switch gear chiller (M2X169B) following the replacement of the noise suppression diodes on September 27, 2022 (WO53203315766)

71111.22 - Surveillance Testing

The inspectors evaluated the following surveillance testing activities to verify system operability and/or functionality:

Surveillance Tests (other) (IP Section 03.01) (2 Samples)

(1) Unit 2 high pressure safety injection pump (M2-P41A) operational readiness and quarterly inservice test on August 2, 2022 (WO53203339960)

(2) Unit 3 diesel fire pump monthly and annual operability test on August 12, 2022 (WO53203340747 and WO53203315574)

71114.06 - Drill Evaluation

Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01) (1 Sample)

(1) Unit 3 emergency preparedness drill on September 27,

71124.07 - Radiological Environmental Monitoring Program

Environmental Monitoring Equipment and Sampling (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated environmental monitoring equipment and observed collection of environmental samples.

Radiological Environmental Monitoring Program (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the implementation of the licensees radiological environmental monitoring program.

Groundwater Protection Initiative Implementation (IP Section 03.03) (1 Sample)

(1) The inspectors evaluated the licensees implementation of the Groundwater Protection Initiative program to identify incomplete or discontinued program elements.

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification

The inspectors verified licensee performance indicators submittals listed below:

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

(1) Unit 2 (July 1, 2021, to June 30, 2022)

(2) Unit 3 (July 1, 2021, to June 30, 2022)

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

(1) Unit 2 (July 1, 2021, to June 30, 2022)

(2) Unit 3 (July 1, 2021, to June 30, 2022)

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

(1) Unit 2 (July 1, 2021, to June 30, 2022)

(2) Unit 3 (July 1, 2021, to June 30, 2022)

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

(1) Unit 2 (July 1, 2021, to June 30, 2022)

(2) Unit 3 (July 1, 2021, to June 30, 2022)

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

(1) Unit 2 (July 1, 2021, to June 30, 2022)

(2) Unit 3 (July 1, 2021, to June 30, 2022)

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

(1) Unit 2 (July 1, 2021, to June 30, 2022)

(2) Unit 3 (July 1, 2021, to June 30, 2022)

===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) Unit 3 'A' and 'B' EDG exhaust system candle fires on July 16 and July 25, 2022 (CR1203703 and CR1204234)

(2) Unit 2 SW restoration time following a design basis external flood (CR1171836)

(3) Reactor coolant system leakage from check valve 2-Sl-227, loop '1B' non-return check valve (CR1185111)

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

(1) The inspectors reviewed the circumstances surrounding a potential report issue involving a failure of the Unit 3 'B' train of the SLCRS negative pressure verification test on April 7, 2022 (CR1195831).

INSPECTION RESULTS

Failure to Correct Degraded Isolation Dampers Associated with the Unit 3 Supplemental Leak Collection and Release System Cornerstone Significance Cross-Cutting Report Aspect Section Barrier Integrity Green [P.4] - Trending 71111.12 NCV 05000423/2022003 - 01 Open/Closed A finding of very low safety significance (Green) and an associated NCV of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, was self - revealed on April 6, 2022, when the

'B' train of the Unit 3 SLCRS did not achieve the required drawdown resulting in a failure to meet TS 3.6.6.1, Supplementary Leak Collection and Release System.

Specifically, the licensee did not assure that previously identified conditions adverse to quality, inadequate PM procedures and inspection schedules associated with safety - related ventilation dampers, were corrected.

Description:

The SLCRS mitigates the radiological consequences of postulated accidents by filtering the exhaust air from the secondary containment. SLCRS is comprised of two redundant trains of exhaust fans and filter units. The secondary containment is an area that includes the containment enclosure building, engineered safety features building (partial),auxiliary building, main steam valve building (partial), and hydrogen recombiner building (partial). The safety function of SLCRS is to maintain a negative pressure in the secondary containment to ensure there is no unfiltered leakage to the outside environment from these areas in the event of a loss of coolant accident other than those releases from SLCRS bypass and damper leakage accounted for in the dose analyses.

The TS operability of the system is verified, in part, by a negative pressure surveillance test performed every refueling outage on both trains. The surveillance verifies that the system can maintain a minimum vacuum pressure for 2 minutes.

On April 6, 2022, the licensee conducted the Unit 3 TS required Surveillance Procedure SP3614I.3, Supplementary Leak Collection and Release System Negative Pressure Verification, and determined that the 'B' train of SLCRS did not meet the acceptance criteria.

The licensee subsequently conducted the same surveillance on the 'A' train of SLCRS which successfully passed its surveillance test.

Upon failure of the train 'B' SLCRS drawdown test, operators entered TS 3.6.6.1, which requires the system to be restored to OPERABLE within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

This surveillance test was performed while Unit 3 was in the process of conducting a plant shutdown for refueling outage 3R21. Unit 3 entered Mode 5 (cold shutdown) prior to the required TS action time expiration.

After discovery of the system degradation, the licensee conducted extensive walkdowns and analysis to determine the cause of the degradation. The licensee determined that the auxiliary building air inlet damper (3HVR*AOD35A) and the main steam valve building ventilation support damper (3HVV*MOD51C) were degraded and did not fully close during the surveillance test, which was identified to be the direct cause of the test failure. Repairs were conducted on all components of the system where degradation was observed.

Surveillance Procedure SP 3614I.3 was conducted again on both trains of SLCRS prior to the plant reaching a TS required mode of applicability and both trains of SLCRS met the acceptance criteria. The licensee determined that this issue was not reportable per 10 CFR 50.73.

The inspectors noted that SLCRS dampers have had a history of poor performance resulting in similar surveillance test failures in 2016 and 2020.

On April 9, 2016 (CR1033408), both the 'A' and 'B' trains of SLCRS failed surveillance testing, which represented a failure to meet TS Limiting Condition for Operation 3.6.6.2 (Secondary Containment Operability) and a loss of safety function. The licensee reported this event to the NRC in LER 05000423/2016-003- 00, Loss of Safety Function - Supplementary Leak Collection and Release System.

The NRC documented a self-revealing Green NCV of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, because the licensee did not develop a Unit 3 SLCRS damper PM procedure that was adequate to prevent the inoperability of the system (NCV 05000423/2016002- 01, Secondary Containment Inoperability Due to Inadequate Procedures). The licensees root cause evaluation for this event (RCE3029256) identified that the SLCRS damper PM program was not adequate to identify declining damper performance trends before negative pressure surveillance test failures.

On November 4, 2020 (CR1160128), the 'B' train of SLCRS failed the negative pressure verification surveillance. The licensee determined that this failure was due to boundary leakage through several ventilation dampers (3HVV*MOD51B/51C) and several SLCRS boundary doors. Repairs were made and the surveillance was successfully completed on November 5, 2020.

In response to the 2022 failure, the licensee performed a level of effort evaluation and determined that previous corrective actions from the 2016 root cause evaluation were not effectively implemented. Specifically, the licensee determined that the PM strategy (procedures and inspection schedules) for these ventilation dampers remained inadequate to identify declining damper performance trends before negative pressure surveillance test failures.

Corrective Actions: The licensee repaired the ventilation dampers and successfully re-performed the SLCRS draw down surveillance test during the refueling outage. The licensee's cause evaluation resulted in corrective action assignments to enhance the PM program for these dampers and to revise procedures to ensure damper blade position is verified through direct inspection.

Corrective Action References: CR1195831, CR1195979, CR1195829, CR1197073

Performance Assessment:

Performance Deficiency: The licensee did not correct a condition adverse to quality, deficient PM procedures, and inspection schedules for safety-related ventilation dampers 3HVR*AOD35A and 3HVV*MOD51C. This deficiency was previously identified and documented in the licensee's corrective action program after both the 'A' and 'B' trains of SLCRS failed surveillance testing in 2016 (RCE 302256). The licensee also had an opportunity to identify that the maintenance strategy remained inadequate when the 'B' train of SLCRS similarly failed in 2020 (CR1160128).

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 protect the public from radionuclide releases caused by accidents or events. Specifically, the SLCRS damper PM strategy was not adequate to ensure SLCRS damper degradation was identified and corrected before it could prevent the B train of SLCRS from performing its safety function. This issue was also like example 4.f of NRC IMC 0612, Appendix E, Examples of Minor Issues.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process for Findings At-Power. The inspectors determined the violation to be of very low safety significance since it only represented a degradation of the radiological barrier function provided for the auxiliary building.

Cross-Cutting Aspect: P.4 - Trending: The organization periodically analyzes information from the corrective action program and other assessments in the aggregate to identify programmatic and common cause issues. Specifically, when the B train of SLCRS failed the same surveillance in 2020, the licensee did not recognize the repeated failure of these dampers to close was an indication that previous corrective actions had not been effectively implemented.

Enforcement:

Violation: 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants, Criteria XVI, Corrective Action, requires in part, Measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected.

Contrary to the above, from approximately April 2016 to April 2022, the licensee failed to assure that conditions adverse to quality associated with safety-related ventilation dampers were corrected. Specifically, corrective actions prescribed by root cause evaluation RCE302256 did not correct the inadequate PM procedures and inspection schedule associated with 3HVR*AOD35A and 3HVV*MOD51C, which resulted in the 'B' train of the SLCRS system failing to meet its technical specification surveillance testing requirements on April 6, 2022.

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

Failure to Establish Adequate Preventive Maintenance Strategy for Emergency Diesel Generator Exhaust Manifold Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P. 4 ] - Trending 71152A Systems FIN 05000423/2022003- 02 Open/Closed A finding of very low safety significance (Green) was self -revealed when operators manually shut down the '3A' EDG on July 16, 2022, and the '3B' EDG on July 25, 2022, when small fires were observed coming from under the exhaust manifold insulation during operational and post-maintenance testing. The licensee did not follow procedure ER-AA-PRS-1010, Preventive Maintenance Task Basis and Maintenance Strategy, when it did not initiate changes to maintenance strategies for the EDG exhaust manifolds based on corrective action program actions and industry operating experience.

Description:

In July 2022, both Unit 3 EDGs experienced fires within their exhaust manifolds during planned surveillance or post - maintenance testing. During each event, Emergency Operating Procedures 3509.15 and 3509.16 were entered for a fire within the EDG enclosure.

This resulted in activation of the fire brigade, emergently shutting down the EDG, and entry into a 72 - hour shutdown action statement. Additionally, this has resulted in an increase in unplanned EDG unavailability and emergent EDG maintenance.

Unit 3 relies on EDGs to provide emergency AC power in response to loss of offsite power (LOOP) events, and the EDGs are required to be operable as specified in plant TSs. The inspectors noted that although these EDG exhaust manifold fires did not disable the EDGs, the fires caused the licensee to shut down the EDGs, rendering them unavailable until the licensee could correct the causes of the fires.

After the fire on the ' 3B' EDG exhaust manifold, the licensee performed a collective significance review which determined that the direct cause of the fire events was flange-to-flange exhaust manifold leaks that allowed unburned combustion product to leak onto hot exhaust piping. In addition to the direct cause, the licensee identified that the current inspection frequency (8 years) of the exhaust manifold, exhaust bellows, and exhaust piping is too infrequent to effectively identify and prevent exhaust leakage from the engine.

The inspectors noted that step 3.2.1.f of ER-AA-102, Preventive Maintenance Program, Revision 16, states DETERMINE performance frequency [of PM] in accordance with ER-AA-PRS-1010, and Section 3.2, Maintenance Strategy, of ER - AA-PRS-1010, Preventive Maintenance Task Basis and Maintenance Strategy, Revision 16, provides direction to initiate changes to maintenance strategies based on corrective action program actions and industry operating experience.

Based on internal and external operating experience, the licensee had previously documented in its corrective action program that the existing PM strategy for the Unit 3 EDG exhaust manifold was not adequate to identify possible precursors or conditions that may have contributed to a 2015 exhaust fire on the '3A' EDG. Specifically, in CR525696, prior to the 2015 fire, the system engineer recommended that the EDG maintenance procedure be revised to include inspections of the upper exhaust lines, joints, heat shield, and insulation and look for any evidence of cracks, leaks, or smoky and/or oily residue every 2 years; but this recommended action was not fully implemented. Instead, an 8-year PM schedule was established. After the 2015 fire, CR1023209 identified that the recommendations from CR525696 were not fully implemented; however, the licensee did not take action to revise the maintenance procedure or shorten the PM schedule.

From 2016 to 2022, after the fire on the '3A' EDG in 2015, the licensee continued to identify exhaust leaks that required replacement of gaskets and bellows and tightening of exhaust manifold flange connections on a frequency that indicated that an 8-year PM was not appropriate. Moreover, the licensee did not take action to evaluate the overall effectiveness of its PM actions related to the EDG exhaust components.

The inspectors determined that the failure to initiate appropriate changes to the EDG exhaust manifold maintenance strategy based on the recurrent exhaust manifold leaks documented in the corrective action program and industry operating experience is a performance deficiency that was within the licensee's ability to foresee and prevent.

Corrective Actions: The licensee entered this issue in its corrective action program as CR1203703 and CR1204234 and performed a collective significance review that evaluated the Unit 3 'A' EDG exhaust manifold fire as well as the Unit 3 'B' EDG exhaust manifold fire and examined the corrective actions from a similar fire on the '3A' EDG in November 2015 (CR1017050).

Corrective Action References: CR1203703, CR1204234

Performance Assessment:

Performance Deficiency: The license did not perform an adequate evaluation of the effectiveness of the PM actions on the Unit 3 EDG exhaust manifold in accordance with Dominion Nuclear Fleet Procedure ER-AA-PRS-1010, "Preventive Maintenance Task Basis and Maintenance Strategy, after condition reports CR525696 and CR1023209 identified that the scope and frequency of PM inspection for the Unit 3 EDG exhaust manifold was not adequate.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Procedure Quality 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 failure to develop adequate PM procedures that would identify and correct degraded EDG exhaust manifold connections resulted in fires that led to operators shutting down the EDGs rendering the safety-related components unavailable until the licensee could investigate and correct the cause of the fire.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined the finding to be of very low safety significance because the finding was not a design deficiency or represent a loss of probabilistic risk assessment function because the small candle fires did not disable either EDG, and the emergency operating procedure would have directed operators to continue running the EDG if it were supplying power to a vital bus during an event.

Cross-Cutting Aspect: P.4 - Trending: The organization periodically analyzes information from the corrective action program and other assessments in the aggregate to identify programmatic and common cause issues. Specifically, the licensee did not analyze recurrent EDG exhaust manifold leaks, which provided evidence that the PM strategy was deficient.

Enforcement:

The inspectors did not identify a violation of regulatory requirements associated with this finding.

Failure to Verify the Required Restoration Time of the Protected Service Water Pump Motor for a Postulated Probable Maximum Hurricane Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.1] - 71152A Systems NCV 05000336/2022003 - 03 Identification Open/Closed The inspectors identified a Green finding and associated NCV of 10 CFR Part 50, Appendix B, Criterion III, "Design Control," because the licensee did not verify the adequacy of the design regarding the time to restore the protected service water (SW) pump motor during a postulated probable maximum hurricane (PMH).

Description:

The Millstone Power Station, Unit 2 current licensing basis assumes a hurricane and accompanying storm surge would cause water level to be greater than 22 feet mean sea level (MSL) at the SW intake structure.

Flood levels above 22 feet MSL would impact all SW pump motors. The current licensing basis is to shut down prior to hurricane arrival and install a portable can on one SW pump motor to protect it until water recedes below 22 feet MSL. After flood waters recede, the SW motor is reconnected, and the pump is placed back in service to provide its SW cooling function. The plant current licensing basis credits decay heat removal by supplying condensate storage tank water via the auxiliary feedwater pumps to the steam generators to feed and steam from the steam generator atmospheric valves.

Additionally, the plant current licensing basis assumes one EDG remains in service without SW cooling by preemptively cross - tying SW to a fire water source and placing the diesel-driven fire pump in service to maintain cooling to one EDG. Per Millstones safety evaluation,

SE-EV-99- 0043, dated 02/22/1999, restoration of the protected SW pump motor is needed for spent fuel pool cooling in 9.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> when the spent fuel pool would be expected to reach 212° F.

The Millstone licensing and design basis identifies a total of 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> with no SW cooling function (2.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> for water level above 22 feet MSL + 2.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> to remove the portable can and reconnect the motor). The SW cooling function is restored after this time period.

In June 2021, the NRC design bases assurance inspection team opened an unresolved item (URI) for procedural and Updated Final Safety Analysis R eport (UFSAR) discrepancies regarding the restoration time of the protected SW pump motor. Specifically, UFSAR Section 2.5.4.2.1 and the implementing Millstone Unit 2 maintenance procedure stated that restoration of the protected SW pump motor could begin once water level recedes below 22 feet MSL. The NRC team determined SW restorations could not be started because the intake structure floor would still be flooded with 8 feet of water preventing access to the SW pump motor and portable can. The team noted the Unit 2 intake ground level elevation is 14 feet MSL. This called into question the Millstone Unit 2 current licensing technical basis that credits restoration of the protected SW motor to be performed within 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> as described in the UFSAR and docketed correspondence to the NRC.

Dominion staff entered the issue into their corrective action program (CR1171836) and performed a new calculation (21-ENG-04081CG) to determine the additional time it would take the water to recede from El 22.0 to El 14 feet MSL and issued an engineering technical evaluation (ETE-MP-2021-1131) to resolve discrepancies between the UFSAR and operating and maintenance procedures.

On June 30, 2022, during a follow-up inspection of the SW restoration URI, the inspectors observed that per new calculation 21-ENG-04081CG, dated 09/01/2021, it would take an additional 4.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for the water to recede from 22 feet MSL to 14 feet MSL. Therefore, unavailability of the protected SW pump motor was extended from 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> to 9.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, (2.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> for water above 22 feet MSL + 4.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for water to recede to 14 feet MSL for a total of 7.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> + 2.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> restoration of the motor = 9.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> total).

Additionally, the inspectors observed that Dominions evaluations documented in their condition report and associated engineering technical evaluation had not documented the overall impact the extended SW pump outage (9.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) would have on the stations PMH mitigating strategies. To address the inspectors questions, Dominion staff provided an impact statement which determined that as a result of the extended SW outage time of 9.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, the fire water system would have insufficient capacity, by about three hours, to support EDG operation. Dominions evaluation showed fire water cooling to maintain the EDG function was increased from 9.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to 10.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> because the fire water system was assumed to be preemptively placed in service to cool an EDG for 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> as flood waters rise to 22 feet MSL. However, there was only an estimated 7.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of fire water cooling capacity. The inspectors further observed Dominion staff identified there was 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of fuel oil storage vs 10.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> needed. The inspectors concluded the shortfall in fire water and fire pump fuel capacity was not consistent with the Millstone Unit 2 design and current licensing basis because it did not maintain the EDG function, which would result in a station blackout, during a postulated PMH as described in UFSAR Section flood event (PMH).

On August 24, 2022, Dominion staff submitted a refined assessment, using assumptions they concluded, based on operator training and oversight, reflected likely operator performance (delayed start of fire water operation and operator throttling of flow to a value of about 725 GPM) which determined that EDG cooling would have been lost for only 16 minutes assuming no fire water storage tank make-up capability. Additionally, the refined assessment stated that cooling to the EDG would not have been lost if using current flood methodologies and more recent hydraulic studies, with respect to the PMH scenarios, developed as part of the Dominions response to the post-Fukushima flood assessment Near Term Task Force.

This is discussed further in the significance determination section below.

Corrective Actions: The licensee entered the issue into the corrective action program (CR1171836 and CR1202916), performed a new calculation (21-ENG-04081CG) to determine the additional time it would take the water to recede from elevation 22.0 feet to 14.0 feet, and issued an engineering technical evaluation (ETE-MP-2021-1131) to resolve discrepancies between the UFSAR and operating and maintenance procedures. In addition, the licensee revised the UFSAR and various procedures to maximize the available fire water inventory (extended inventory to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />), and to increase fire pump fuel tank inventory to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Further, the licensee performed an evaluation to determine the overall plant PMH mitigating strategies impact due to the extended SW pump motor outage.

Corrective Action References: CR1171836 and CR1202916

Performance Assessment:

Performance Deficiency: The licensees failure to verify the adequacy of the design in respect to restoration of the protected SW pump motor is a performance deficiency that was reasonably within the licensee's ability to foresee and prevent. Specifically, the MS2 UFSAR and maintenance procedure stated that restoration of the protected SW pump motor can commence once flood water level recedes below 22 feet MSL. The inspectors considered SW restorations could not likely be started because there would be approximately 8 feet of water in the area until the water receded to 14 feet MSL.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control 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 licensee had not performed design reviews, calculations or testing to assess the additional time it would take for postulated water in the SW pump house to recede from 22 feet to 14 feet MSL, which was necessary for personnel to timely restore the SW pump to perform its required safety function during and after, a design basis flood event. Additionally, this issue is similar to example 3.g of NRC IMC 0612, Appendix E, Examples of Minor Issues, in that based on design conditions there was reasonable doubt of operability/functionality of the SW system with respect to the stations capability of restoring the protected service pump motor within the specified 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> for a PMH.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using IMC 0609.04, Initial Characterization of Findings, and Exhibit 2 of IMC 0609, Appendix A, the inspectors screened this finding for safety significance and based on the complex flood mitigation strategy and discussions with a regional Senior Reactor Analyst (SRA), determined that a detailed risk evaluation was appropriate.

Specifically, the performance deficiency challenged the success of a complex flood mitigation strategy that could potentially adversely impact multiple systems.

The regional SRA used the Systems Analysis Programs for Hands-On Evaluation (SAPHIRE)

Revision 8.2.6 and the Standardized Plant Analysis Risk (SPAR) Model for Millstone Unit 2, Model Version 8.80, to conduct the external events detailed risk evaluation. In addition, recent information was reviewed regarding the PMH /flood meteorological conditions, scenarios, and station response documented in Dominions response and the NRCs assessment of Millstone Unit 2 and Unit 3 flooding focused evaluation / integrated assessment (FE/IA). Specifically, the Millstone Unit 2 and Unit 3 FE/IA (ADAMS Accession No. ML20042D996, Section 7.2.3) describes the 1E -4 per year annual exceedance probability ( AEP) scenario, Dominion calculations 18- 075 and 18-110 that document the combined effects and duration of the storm s (particularly storm CE2 that represents 1E-4 AEP scenario on Unit 2 ), and the NRCs assessment of Dominions submittal (ML20171A534, Sections 3.3.2 and 3.3.3) of the combined storm effects and expected plant response.

The limiting condition (condition case) related to the performance deficiency is the potential loss of firewater cooling and subsequent failure of the single operating EDG (while operating on firewater cooling during the PMH scenario). This event is modeled as a hurricane with a LOOP and loss of the only operating EDG during mode 3 (no structural damage, other than that in the switchyard which caused the LOOP, is postulated).

The SRA made the following assumptions with respect to the analysis and system performance impact:

• The risk of this event can be estimated by assuming that the success criteria for a LOOP event at-power applies. This assumption has both conservative and non-conservative aspects that are deemed to be balancing from a risk point of view.

Namely,

Since the unit is already shutdown, the decay heat is lower than at power. This gives a larger time window for operator actions, both for starting systems, or recovering power, and

Some mitigating safety systems, if needed, may require operator action to start; they may not be available for automatic actuation in Mode 3. One example of this is auxiliary feedwater cooling for the steam generators). Thus, the plant condition/event importance estimates using the at-power LOOP event tree are expected to be on the conservative side.

• Unit 2 is shutdown and in M ode 3 in advance of the storm with plant line-up consistent with PMH hurricane response when projected intake water heights are to exceed 19.5 feet; Component cooling and SW pumps (one-protected by portable can) secured, one EDG secured and one EDG operating on firewater cooling.

• Unit 2 event of concern is a PMH storm at the 1E-4 / year AEP. (Use of HCN-BIN-1, Hurricane High Wind Event BIN 1, 111MPH-129MPH, with an initiating event frequency set to 1E-4); Incorporates LOOP/Station blackout event trees.

• Maximum wind speeds associated with the 1E-4 AEP storm are approximately 100 mph and not expected to cause structural damage to Category 1 system, structures, and components and not present a significant missile hazard to other systems; Use of Event Tree HWD-96MPH, Straight line High Winds in Excess of 96MPH)

• The condition case is represented by the loss of the running EDG, with the potential of recovery of the other EDG (SW restored) or mitigation by the station blackout diesel generator.

Other considerations and modifications to the Unit 2 SPAR were performed:

• Reactor protection system failure is removed; No anticipated transient without scram.

• Reactor coolant system temperature and pressure conditions are such that no reactor coolant pump seal loss of cooling accident challenge exists; Disabled in the SPAR model.

• Weather-related loss of offsite power initiator was conservatively set to 1.0.

• A protected SW pump is recoverable and supports recovery of one EDG.

• The engine-driven fire water pump remains functional with increased nominal failure probability.

• Station blackout diesel generator is available for emergency AC power with increased nominal failure probability.

• FLEX equipment is not credited.

For the base case, weather-related LOOP (IE-LOOPWR) was set to 1.0 and one EDG was set to 0.25 (as a surrogate for SW /EDG recovery). The change set also included expected component cooling and SW alignments. In the condition case, IE-LOOPWR was set to 1.0 and EDGs were set to 0.5 (failed firewater to EDG and surrogate for recovery) and 0.25 (as a surrogate for SW/EDG recovery). Generic severe-weather recovery distributions were used.

The performance deficiency existed since 1999 hence the exposure time is set to the maximum one year.

Based on these assumptions and model changes, the calculated delta core damage frequency (delta CDF) is estimated at 2E-7 per year (5% 3E-10, 95% 8E-7). The dominant accident sequence includes hurricane event (PMH), LOOP due to high winds, loss of both EDGs and station blackout diesel generator, and failure to recover an EDG, and failure of auxiliary feedwater. This is a bounding estimate and does not account for additional margin afforded by the availability of city water make-up (automatic or manual) to the fire water tanks (extends cooling to the EDG), pre-staged FLEX equipment, and additional resources available from the site during a pre-planned shutdown for a storm event.

The most significant risk impact is the margin provided by a shorter probable storm inundation time (5.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> vs 7.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> current licensing basis estimated duration) for a 1E -4 AEP storm as documented in the recent flooding focused evaluation / integrated assessment. This margin is contingent on correctly setting the firewater throttle valve to the EDG during the PMH.

Based on additional discussions with NRC license operator inspectors and licensee training staff, there is high confidence in this setting. The shorter site inundation time lessens the likelihood of depleting the firewater tanks (cooling to the single EDG) before the restoration of SW to the other EDG. Though this is considered best available information for this analysis, it is not the licensees current design basis. It can also be subsequently concluded that this time margin would support screening to very low risk in I MC 0609, Appendix A, Exhibit 2, Question 1.

The analyst also used SAPHIRE and IMC 0609, Appendix H, "Containment Integrity Significance Determination Process," dated March 23, 2020, and determined there was not a significant increase in large early release frequency and hence a separate consequential steam generator tube rupture (C-SGTR) screening was not performed. Also, no additional concurrent external events are assumed to occur during the PMH.

The total increase in CDF associated with the performance deficiency is estimated at 2E-7 per year. Therefore, this finding is characterized as an issue of very low safety significance (Green).

Cross-Cutting Aspect: P.1 - Identification: The organization implements a corrective action program with a low threshold for identifying issues. Individuals identify issues completely, accurately, and in a timely manner in accordance with the program. Specifically, the licensee did not identify that additional time was necessary for flood water level to recede such that the SW pump motor could be restored following a PMH event. Although this issue existed since at least 1999 when the current cross-connect fire water pipe was installed, the licensee documented in their 2020 integrated assessment (ML200042D996) procedural enhancements to ensure 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of diesel fuel for the fire water pump was available but did not discuss the capacity of the fire water storage tanks for the similar duration.

Enforcement:

Violation: 10 CFR Part 50, Appendix B, Criterion III, "Design Control," requires, in part, that measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in § 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies, are correctly translated into specifications, drawings, procedures, and instructions. Criterion III further states that the design control measures shall provide for verifying or checking the adequacy of design, such as, by the performance of design reviews, by the use of alternate or simplified calculational methods, or by the performance of a suitable testing program.

Contrary to the above, from 1999 to August 2022, the licensees design control measures did not provide for verifying or checking the adequacy of design, such as by the performance of design reviews, by the use of alternate or simplified calculational methods, or by the performance of a suitable testing program. Specifically, the licensee did not check the adequacy of design to include the additional time it would take flood water to recede from 22 feet MSL to 14 feet MSL and thus failed to verify whether restoration of the protected SW pump motor could be performed within the 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> as stated in their design and licensing basis documentation for a postulated PMH.

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

The disposition of this finding and associated violation closes URI 05000336/2021010-03.

URI Unit 2 Service Water Restoration Time following a Design 71152A Basis External Flood URI 05000336/2021010-03 Closed

Description:

As documented in design bases assurance inspection report 05000336/2021010 (ML21137A170), inspectors identified during a Unit 2 intake structure walkdown an apparent disconnect between the UFSAR description for a PMH flood response and the implementing procedure (AOP 2560). Specifically, AOP 2560 did not direct restoration of the protected SW pump motor until water level recedes to 14 feet. However, the UFSAR description implied that the restoration activities can commence once water level recedes below 22 feet MSL. The inspectors noted that this disconnect had the potential to extend the coping duration without SW beyond the previously analyzed maximum time.

Inspectors conducted additional onsite reviews and walkdowns of affected plant systems and assessed the licensee's recalculation that supported a PMH flood response. In addition, the licensee revised UFSAR and affected procedures to address identified discrepancies and to extend available firewater support during extended SW outage time during a storm.

The inspectors identified a performance deficiency regarding design control that was reasonability within the licensee's ability to foresee and correct and should have been prevented. This URI is closed to NCV 05000336/2022003- 03, documented in this report.

Corrective Action References: CR1171836, CR1202916

EXIT MEETINGS AND DEBRIEFS

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

• On September 22, 2022, the inspectors presented the radiological environmental monitoring program inspection results to Michael J. OConnor, Site Vice President, and other members of the licensee staff.

• On October 27, 2022, the inspectors presented the integrated inspection results to Michael J. O'Connor, Site Vice President, and other members of the licensee staff.

• On October 31, 2022, the inspectors presented the Unit 2 Service Water Restoration Following a Design Basis External Flood Problem Identification and Resolution Sample inspection results to Micha el O'Connor, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.04 Calculations MP-CALC-ENG-Determination of the Instrument Air Requirement for Certain

98-ENG-Safety

2621M2

Corrective Action CR1201294

Documents CR1205397

Drawings 25203-26005 Piping & Instrument Diagram Condensate Storage & Aux. Revision 60

Feed, Sheet 3

203-26009 Piping & Instrument Diagram Instrument Air System, Sheet 6 Revision 32

203-30022 125V DC and 120V AC Distribution Panel Schedule

203-30024 Single Line Diagram 125V DC Emergency and 120V AC Revision 49

Vital Systems

Procedures SP 2619C-001 Control Room Weekly Checks Revision

014-00

Work Orders 53203325593

71111.05 Calculations EPM-186 Millstone Nuclear Power Plant Unit 2 Combustible Loading Revision 2

Re-Analysis Calculation

Procedures MP-PROC-ENG-MP2 Fire Fighting Strategies Revision 3

U2-24-FFS-

BAP01-AB-14-38

MP-PROC-ENG-Aux Building Fire Strategy Map Revision 2

U2-24-FFS-

BAP01-AB-MAP

MP-PROC-OPS-Fire Hose Station Inspection Revision 1

C SP 600.18

MP-PROC-OPS-Fire Extinguisher Inspection Maintenance Revision 008

SFP 9

71111.06 Drawings 25203-24092 SH-00A8AW3 Penetration Seal Survey Revision 1

Miscellaneous MP-NOTEBK-Probabilistic Risk Assessment Model Notebook Flood Revision 6

PRA-MPS2-IF.2 Scenario

71111.07A Corrective Action CR1204481

Documents CR1204569

Procedures ER-AA-HTX-1002 Heat Exchanger Program Visual and Leak Testing Revision 6

Inspection Type Designation Description or Title Revision or

Procedure Date

SP-2670-003 'C' RBCCW HX D P Determination 06/18/2022

Work Orders 53203236470

203335956

71111.11Q Corrective Action CR1203841

Documents CR1204200

CR1204440

Procedures OP 2330A RBCCW System Revision 30

Work Orders 53203315766

203341541

203343258

71111.12 Corrective Action CA11233102

Documents CA11233106

71111.13 Miscellaneous Calculated Risk Assessment 09/24/2022

WM-AA-301 Attachment 14 07/20/2022

Procedures OP-MP-601 Protected Equipment Revision 38

WM-AA-301 Attachment 14 Medium Risk Action Plans 07/13/2022

71111.15 Corrective Action CA11233102

Documents CA11233106

CA11233120

CR1202467

CR1203990

CR1204130

CR1204831

CR1205154

CR1205213

Miscellaneous DBS-2315A Design Bases Summary Control Room Air Conditioning Revision 0

MP-DBS-000- Unit 3 Design Bases Summary for the Reactor Plant

3DBS-NSS-007 Component Cooling

Procedures ARP 2592G Alarm Response for Computer UPS Components Revision 1

ER-MP-CRH-10 Millstone Unit 2 Control Room Habitability Program Revision 4

ETE-MP-2022-Code Case N-513-4 Evaluation of Unit 3 Service Water Flaw Revision 0

1073 Located in Line 3-SWP-010-109-3, FW-64

OP-M2-MOP-West 125 Volt DC Vital Switchgear Room Cooling (2022-07) Revision

VEN-006 001-00

Inspection Type Designation Description or Title Revision or

Procedure Date

SP 3670.4-015 Quarterly SBO PM Revision

001-06

Work Orders 53203357652

203357809

203358066

203359239

203360121

203360847

203360848

71111.19 Corrective Action CR1177212

Documents CR1208134

CR1208220

Miscellaneous DBS-2344 A & B Design Bases Summary 480V AC Electrical Distribution

System

Procedures C MP 782AE Overcurrent Device Testing for MCC and Molded Case Revision 009

Breakers

MP-02-NO-Visual Weld Acceptance Criteria for Weldments and Brazed Revision 0

FAP04.3 Joints

SP 2604T Actuation Tests of Various ESF Components Revision 09

SP 2605G Containment Isolation Valve Stroke and Timing, IST Revision 29

SP 2612A 'A' SW Pump and Facility 1 Discharge Check Valve IST Revision 23

Work Orders 53102387693

203315766

71111.22 Calibration MP-RECORD- 02/26/2021

Records CAL-MTE-03547

Procedures CEN-103C Operation of Portable Ultrasonic Flowmeters Revision 5

SP 2604AO HPSI Pump Inservice Testing =1,750 psia Facility 1 Revision 012

71114.06 Corrective Action CR1209326

Documents CR1210126

CR1210145

Miscellaneous MSEP22FD 09/27/2022

Procedures EP-MP-26-EPI-Millstone Power Station Emergency Plan Revision 64

EPMP

Inspection Type Designation Description or Title Revision or

Procedure Date

MP-26-EPI-Unit 3 Emergency Action Level Matrix Revision 12

FAP06-003

MP-26-EPI-Protective Action Recommendations Revision 9

FAP06-006

71152A Calculations 21-ENG-

04081CG

MP-CALC-ENG-COMBINED EFFECTS FLOOD ANALYSIS FOR STORM Revision 0

18-110 SURGE ANNUAL EXCEEDANCE PROBABILITY 1.0E- 04

FOR MILLSTONE POWER STATION (BOB)

Corrective Action CR1111689

Documents CR1134682

CR1172773

CR1185111

Drawings 25203-26015, Safety Injection Tanks Revision 31

Sht. 3

Engineering ETE-MP-2021-

Evaluations 1131

Miscellaneous Standing Order Number SO-21-016 12/10/2021

ML20042D996 Dominion Energy Nuclear Connecticut, Inc. RESPONSE TO 02/10/2020

MARCH 12, 2012 REQUEST FOR INFORMATION

ENCLOSURE 2, RECOMMENDATION 2.1, FLOODING

FOCUSED EVALUATION/ INTEGRATED

ASSESSMENT SUBMITTAL

ML20171A534 MILLSTONE POWER STATION, UNITS 2 AND 3 - STAFF 08/13/2020

ASSESSMENT OF FLOOD HAZARD FOCUSED

EVALUATION AND INTEGRATED ASSESSMENT (EPID

NO. L-2020-JLD-0000)

Procedures AOP-2560 Storms, High Winds and High Tides Revision 022

BKG AOP 2560 AOP BKGND - Storms, High Winds and High Tides Revision 021

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