IR 05000336/2023002

Integrated Inspection Report 05000336/2023002 and 05000423/2023002

ML23221A092
Person / Time
Site:	Millstone
Issue date:	08/09/2023
From:	Matt Young NRC/RGN-I/DORS
To:	Carr E Dominion Energy Co
References
IR 2023002
Download: ML23221A092 (1)

Text

August 9, 2023

SUBJECT:

MILLSTONE POWER STATION, UNITS 2 AND 3 - INTEGRATED INSPECTION REPORT 05000336/2023002 AND 05000423/2023002

Dear Eric Carr:

On June 30, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station, Units 2 and 3. On August 3, 2023, the NRC inspectors discussed the results of this inspection with Lori Armstrong, Director Nuclear Station Safety and Licensing, 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. All 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 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, Digitally signed by Matthew R. Matthew R. Young Date: 2023.08.09 Young 10:46:23 -04'00'

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: 05000336/2023002 and 05000423/2023002 Enterprise Identifier: I-2023-002-0034 Licensee: Dominion Energy Nuclear Connecticut, Inc.

Facility: Millstone Power Station, Units 2 and 3 Location: Waterford, CT Inspection Dates: April 1, 2023, to June 30, 2023 Inspectors: J. Fuller, Senior Resident Inspector E. Allen, Resident Inspector E. Bousquet, Resident Inspector K. Mooney, Acting Resident Inspector J. Ambrosini, Nuclear Engineer N. Eckhoff, Health Physicist E. Eve, Senior Project Engineer S. Mercurio, Emergency Preparedness Inspector E. Miller, Reactor Inspector A. Turilin, Reactor Inspector D. Werkheiser, Senior Reactor Analyst 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 Perform General Condition Monitoring Inspections and System Engineering Walkdowns of Portions of the Safety-Related Service Water System in Accordance with Documented Procedures Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.1] - 71111.12 Systems NCV 05000336/2023002-01 Identification Open/Closed The inspectors identified a Green finding and associated non-cited violation (NCV) of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion V, Instructions,

Procedures, and Drawings, when the licensee did not accomplish activities affecting quality in accordance with documented procedures. Specifically, for portions of the service water system piping located in the service water pipe tunnel, the licensee did not perform general condition monitoring inspections in accordance with ETE-MP-2013-1062, General Condition Monitoring Activities, License Renewal Aging Management Program, and did not perform system engineering walkdowns in accordance with ER-AA-101, System Engineering Walkdowns. Failure to implement these procedures resulted in reasonable doubt about the structural integrity of the service water piping in the service water pipe tunnel.

Failure to Maintain Operational Configuration Control of the Reactor Pressure Vessel Head Vent Path During Vacuum Fill of the Reactor Coolant System Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green [H.12] - Avoid 71111.20 NCV 05000336/2023002-02 Complacency Open/Closed A self-revealed Green finding and associated NCV of Millstone Unit 2 Technical Specification 6.8, Procedures, was identified when the licensee did not implement written instructions for filling and venting the reactor coolant system (RCS). Specifically, the licensee failed to ensure that the reactor pressure vessel head (RPVH) was properly vented prior to vacuum fill activities. As a result, during vacuum fill of the RCS, a void was formed in the RPVH, and actual RCS level was approximately 6 percent less than indicated level during decreased inventory operations.

Failure to Maintain Appropriate Instructions for Energizing and Filling the Reactor Coolant System Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green None (NPP) 71111.20 NCV 05000336/2023002-03 Open/Closed A self-revealed Green finding and associated NCV of Millstone Unit 2 Technical Specification 6.8, Procedures, was identified when the licensee did not maintain appropriate instructions for energizing (pressurizing) and filling the RCS after the system was drained for maintenance activities during the refueling outage. This resulted in a 7 gallon per minute intersystem leak from the RCS to the emergency core cooling system (ECCS) for approximately 5.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />.

Additional Tracking Items

None.

PLANT STATUS

Unit 2 began the inspection period at approximately 91 percent of rated thermal power as it coasted down to the planned refueling outage, which began on April 6, 2023. The unit remained shut down for the remainder of the inspection period.

Unit 3 began the inspection period at rated thermal power. On May 30, 2023, an automatic reactor trip occurred due to a main generator ground fault. The unit remained shut down for the remainder of the inspection period.

INSPECTION SCOPES

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

71111.04 - Equipment Alignment

Partial Walkdown (IP Section 03.01) (5 Samples)

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

(1) Unit 2 120-volt alternating current vital bus VA-10 and bus VA-20 during troubleshooting on safety-related inverter 1 on April 5, 2023

(2) Unit 3 'B' emergency diesel generator fuel oil system from the storage tank to the emergency diesel generator on April 18 to 20, 2023

(3) Unit 2 service water pipe tunnel on April 14 and 26, 2023

(4) Unit 2 high-pressure safety injection system inside containment from the containment vessel to the RCS on May 9 and 10, 2023

(5) Unit 3 auxiliary feedwater system after a plant trip on May 30, 2023

Complete Walkdown (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated system configurations during a complete walkdown of the Unit 2 'A' train of low-pressure safety injection on April 10 and 11, 2023.

71111.05 - Fire Protection

Fire Area Walkdown and Inspection (IP Section 03.01) (8 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 containment building on all elevations (fire area C-1) during the refueling outage (April 2023)

(2) Unit 2 west piping penetration area on the 5'-6" elevation (fire area A-8C) on April 10 and 11, 2023

(3) Unit 3 emergency diesel generator west fuel oil vault (fire area EG-2) on April 18, 2023

(4) Unit 2 service water piping tunnel (fire area Y-9) on May 3, 2023

(5) Unit 3 east motor control center and rod control air conditioning unit room on the 66'-6" elevation (fire area AB-8) on May 22, 2023

(6) Unit 3 hydrogen seal oil unit on the 14'-6" elevation (fire area TB-2B) on June 7, 2023

(7) Unit 3 sodium hypochlorite room storage enclosure on all elevations (fire area CWS-1B) and the service water valve access enclosure (fire area CWS-1C) on June 8, 2023

(8) Unit 3 liquid waste floor area and pipe tunnels on the 4'-6", 8'-6", and 16'-6" elevations (fire area WDB-1A) on June 26, 2023

===71111.08P - Inservice Inspection Activities (Pressurized-Water Reactor [PWR])

The inspectors verified that the RCS boundary, reactor vessel internals, risk-significant piping system boundaries, and containment boundary were appropriately monitored for degradation and that repairs and replacements were appropriately fabricated, examined, and accepted by reviewing the following activities from April 10 to 18, 2023:

PWR Inservice Inspection Activities - Nondestructive Examination and Welding Activities (IP Section 03.01) ===

The inspectors verified that the following nondestructive examination activities were performed appropriately at Unit 2:

(1) Ultrasonic Examination

• Automated phased array ultrasonic examination of the 'B' reactor coolant pump suction elbow to safe-end dissimilar metal weld, P-8-C-1 (WO53203243402)

• Manual ultrasonic examination of the pressurizer bottom head to shell circumferential weld, PR-BHS-1A (WO53203320621)

Visual Examination

• Bare metal visual examination of RCS loop '2A' cold leg instrument taps (Alloy 600), TE-122CA, TE-122CC, and TE-1235 (WO53203321167)

PWR Inservice Inspection Activities - Vessel Upper Head Penetration Inspection Activities (IP Section 03.02) (1 Sample)

The inspectors verified that the licensee conducted the following vessel upper head penetration inspections and addressed any identified defects appropriately:

(1) Bare metal visual re-examination of reactor vessel head penetrations 2, 55, 57, 65, 68, and 71 PWR Inservice Inspection Activities - Boric Acid Corrosion Control Inspection Activities (IP Section 03.03) (1 Sample)

The inspectors verified the licensee is managing the boric acid corrosion control program through a review of the following evaluations:

(1) CR1223587, Boric acid leak identified on 2-SI-854 CR1223647, Boric acid deposit on 2-CH-658 CR1223717, Boric acid deposit identified on 2-RC-443 CR1223863, Aging management walkdown identified boric acid leak on 2-CH-110Q

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 the comprehensive testing of the low-pressure safety injection pumps in Mode 5, when the pumps were providing decay heat removal function on April 7, 2023, and during RCS drain down activities on April 9, 2023.

(2) The inspectors observed and evaluated licensed operator performance in the Unit 3 control room during an emergent down power to 92 percent power due to feedwater heater level control valve oscillations on May 17, 2023, and during an unplanned turbine and reactor trip on May 30, 2023.

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

(1) The inspectors observed and evaluated licensed operator just-in-time training in the Unit 2 simulator on May 31, 2023.

(2) The inspectors observed and evaluated licensed operator requalification training in the Unit 3 simulator on June 13, 2023.

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (4 Samples)

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

(1) Unit 3 station blackout diesel after March 6, 2023, failure to start (CR1221101 and WO53203375886)

(2) Unit 2 condensate storage tank on April 24, 2023 (WO53102643085, CR1225776)

(3) Unit 2 general condition monitoring of the service water piping in the service water pipe tunnel on April 26, 2023 (CR1227813, CR1228436)

(4) Unit 3 maintenance rule (a)(1) action plan review for the July 13, 2022, 'A' emergency diesel generator overspeed trip during a hot restart surveillance (CR1203517)

Quality Control (IP Section 03.02) (1 Sample)

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

(1) Unit 2 safety-related battery charger replacement (201B) on May 10, 2023 (WO53203350965)

Aging Management (IP Section 03.03) (1 Sample)

The inspectors evaluated the effectiveness of the aging management program for the following SSCs that did not meet their inspection or test acceptance criteria:

(1) Unit 2 nonfunctional structural supports for both trains of service water piping in the service water pipe tunnel on April 26, 2023 (CR1225934, CR1226542, CR1226545, CR1226556, CR1226920)

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management (IP Section 03.01) (8 Samples)

The inspectors evaluated the accuracy and completeness of risk assessments for the following planned and emergent work activities to ensure configuration changes and appropriate work controls were addressed:

(1) Unit 2 elevated risk due to removing the reserve station service transformer from service for relocation of the motor operated disconnect control switches from the Unit 1 control room panel 909 to Unit 2 main control board panel C-07 on April 4, 2023 (WO53203364813)

(2) Unit 2 elevated risk and associated risk mitigation action associated with troubleshooting Inverter 1 on April 5, 2023

(3) Unit 2 elevated risk and associated risk mitigating actions during Unit 2 RCS draining and decreased inventory on April 9 and 10, 2023

(4) Unit 2 risk plan for freeze seal installation and removal in support of motor operated valve testing on low-pressure safety injection header to loop '2B' valve (2-SI-645) on April 19, 2023 (WO53203365663)

(5) Unit 2 elevated risk and associated mitigating actions during service water piping replacement near the inservice 'B' train piping on May 15, 2023

(6) Unit 3 elevated risk when the normal station service transformer was removed from service to support main generator ground fault troubleshooting on May 31, 2023

(7) Unit 3 high-risk plan and associated mitigating actions associated with the through-wall leak repair on the service water line 3-SWP-006-261-3(A) on June 5, 2023

(8) Unit 3 elevated risk due to electrical isolation for ongoing troubleshooting of 'B' phase from the main generator to the normal service station transformer phases on June 12, 2023

71111.15 - Operability Determinations and Functionality Assessments

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

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

(1) Unit 2 functionality assessment for the 'A' direct current switchgear room chiller (X169A), which was nonfunctional to support the east and west direct current switchgear room ventilation systems on April 4, 2023 (CR1223254)

(2) Unit 2 inoperable 120-volt vital bus VA-10 due to inverter 1 malfunction on April 5, 2023 (CR1223269)

(3) Unit 3 'A' service water piping evaluation of structural integrity after existing through-wall flaw increased in size on April 12, 2023 (CR1224202)

(4) Unit 2 structural integrity evaluations for corroded 'A' and 'B' train service water header pipe supports, flanges, and bolting in the service water piping tunnel on April 26, 2023 (ETE-MP-2023-1038, ETE-MP-2023-1040, ETE-MP-2023-1042)

(5) Unit 3 operability evaluation for surveillance SP3639.1-3, supplemental position verification test of steam generator chemical feed valves, which could not be performed by the required surveillance test frequency on April 29, 2023 (CR1218860)

(6) Unit 2 operational decision-making evaluation for pressurizer power operated relief valve (2-RC-402) leakage on June 21, 2023 (CR1231529, CR1230594, CR1227466)

71111.18 - Plant Modifications

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

(2 Samples)

The inspectors evaluated the following temporary or permanent modifications:

(1) Unit 2 service water pipe degradation permanent modifications (MP2-23-04060, MP2-23-01053, MP2-23-01054)

(2) Unit 2 auxiliary feedwater turbine supply check valve from the #2 steam generator (2-MS-4B) piping reconfiguration permanent modification (MP2-22-01094, WO53203358997)

71111.20 - Refueling and Other Outage Activities

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

(1) The inspectors evaluated Unit 2 refueling outage 2R28 activities from April 6 to July 2, 2023.

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)

(1) Unit 2 'B' emergency diesel generator after replacement of #7 piston and other preventive maintenance work performed March 27 through April 3, 2023 (WO53203377184)

(2) Unit 2 battery performance discharge test after battery cell (201B) replacement on April 13, 2023 (WO53203231976)

(3) Unit 2 high-pressure safety injection header 'B' relief valve (2-SI-409) after lift failure and overhaul on April 15, 2023 (CR1224593, WO53203227897)

(4) Unit 2 pressure locking protection system test for 2-CS-16.1A ('A' containment sump outlet header isolation valve) after replacement of the rupture disk on April 29, 2023 (WO53203229978)

(5) Unit 2 turbine driven auxiliary feedwater pump after pump overhaul on June 10, 2023 (WO53102432912)

(6) Unit 2 auxiliary feedwater turbine supply check valve from the #2 steam generator on

June 29, 2023 (WO53203358997) Surveillance Testing (IP Section 03.01) (6 Samples)

(1) Unit 2 main steam safety valve testing on April 6, 2023 (SP 2730B)

(2) Unit 2 'A' and 'B' low-pressure safety injection pumps comprehensive surveillance test on April 7, 2023 (WO53203324753)

(3) Unit 2 integrated test of facility 2 components on April 8, 2023

(4) Unit 2 'A' and 'B' high-pressure safety injection comprehensive pump tests on April 11, 2023

(5) Unit 3 'A' emergency diesel generator operability test from the sequencer (fast start)on April 11, 2023 (SP 3646A.1)

(6) Unit 3 biennial comprehensive pump test on the 'A' safety injection cooling pump (3CCI*P1A) on June 7, 2023

Inservice Testing (IP Section 03.01) (1 Sample)

(1) Unit 2 'B' high-pressure safety injection pump inservice quarterly pump test on

April 3, 2023 Containment Isolation Valve Testing (IP Section 03.01) (1 Sample)

(1) Unit 2 containment leak test type 'C', 2-EB-99 and 2-EB-100, on April 8, 2023 (WO53102734088)

Diverse and Flexible Coping Strategies Testing (IP Section 03.02) (1 Sample)

(1) Units 2 and 3 annual test of beyond design basis auxiliary feedwater pump (MP-BDB-P2B) flex equipment on June 28, 2023 (WO53203360646)

71114.02 - Alert and Notification System Testing

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

(1) As a result of the 2020 COVID-19 Public Health Emergency, the licensee requested and received an exemption to reschedule their biennial emergency preparedness exercise from 2020 to 2021 (Agencywide Documents Access and Management System Accession No. ML20287A273). The inspectors performed the emergency preparedness program inspection scheduled for 2021 in its place, then performed emergency preparedness exercise inspections in 2021 and 2022.

The inspectors evaluated the licensee's maintenance and testing of the Alert and Notification System on May 22 through May 26, 2023, for the period of September 2020 through April 2023.

71114.03 - Emergency Response Organization Staffing and Augmentation System

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

(1) The inspectors evaluated the readiness of the licensee's Emergency Preparedness Organization on May 22 through May 26, 2023.

71114.04 - Emergency Action Level and Emergency Plan Changes

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

(1) The inspectors evaluated the following submitted Emergency Action Level and Emergency Plan changes:

• MP-23-03-0, Unit 2 Programmable Input Output System Radiation Monitors 2RM-9116 and 2RM-9049 Modification

• MP-22-11-0, OU-M3-201, Shutdown Safety Assessment Checklist, Revision 31

• MP-22-15-0, Replacement of Groton Town Siren #18 with Spare Siren (Former NL14 Siren)

• MP-23-09-0, 3RMS-RE01, 02, 03, 10, 12, 14, 31, 32, 35 Replacement

• MP-23-06-0, Emergency Response Data System Data Point Change Per Unit 2 Programmable Input Output System Radiation Monitors 2RM-9116 and 2RM-9049 Modification

• MP-23-03-0, Unit 2 Programmable Input Output System Radiation Monitors 2RM-9116 and 2RM-9049 Modification This evaluation does not constitute NRC approval.

71114.05 - Maintenance of Emergency Preparedness

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

(1) The inspectors evaluated the licensee's maintenance and testing of the emergency preparedness program on May 22 through May 26, 2023, for the period of September 2020 through April

71124.01 - Radiological Hazard Assessment and Exposure Controls

Radiological Hazard Assessment (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated how the licensee identifies the magnitude and extent of radiation levels and the concentrations and quantities of radioactive materials and how the licensee assesses radiological hazards.

Instructions to Workers (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated how the licensee instructs workers on plant-related radiological hazards and the radiation protection requirements intended to protect workers from those hazards.

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

The inspectors observed/evaluated the following licensee processes for monitoring and controlling contamination and radioactive material:

(1) Observed workers exiting the radiological controlled area checkpoint and technician response to alarming personnel contamination monitors

(2) Observed technicians surveying potentially contaminated material leaving the radiologically controlled area at Unit 2

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

The inspectors evaluated the licensee's control of radiological hazards for the following radiological work:

(1) Observed radiological technician briefing workers entering high radiation areas on dose rates in the area and checking that dosimeter set points were correct based on the most up-to-date surveys from the area

(2) Observed technicians perform radiation, contamination, and airborne monitoring during in-core-instrument underwater cutting

(3) Reviewed Radiation Work Permit 2230305, Cavity Decontamination High Radiation Area and Very High Radiation Area Controls (IP Section 03.05) (3 Samples)

The inspectors evaluated licensee controls of the following high radiation areas and very high radiation areas:

(1) Unit 2 Containment: Access to under reactor vessel

(2) Unit 2 Auxiliary Building: -45' elevation aerated waste tank room

(3) Unit 2 Auxiliary Building: -5' elevation spent fuel pool cooling heat exchanger Radiation Worker Performance and Radiation Protection Technician Proficiency (IP Section 03.06) (1 Sample)

(1) The inspectors evaluated radiation worker and radiation protection technician performance as it pertains to radiation protection requirements.

71124.05 - Radiation Monitoring Instrumentation

Walkdowns and Observations (IP Section 03.01) (6 Samples)

The inspectors evaluated the following radiation detection instrumentation during plant walkdowns:

(1) Small article monitor 12 (instrument #12155) at the Unit 3 control point

(2) Ludlum model 26-1 (serial #8045) at the Unit 3 control point

(3) Eberline R0-20 (instrument #0989) at the Unit 3 control point

(4) Ludlum model 177 (serial #208762) at the Unit 3 personnel hatch

(5) Thermo Scientific Radeye Gx (serial #606) at the radwaste reduction facility

(6) Telepole (serial #6601-041) at the radwaste reduction facility

Calibration and Testing Program (IP Section 03.02) (10 Samples)

The inspectors evaluated the calibration and testing of the following radiation detection instruments:

(1) Eberline AMS-4 (serial #1392)

(2) Ludlum 2241/2241-2 rate meter and scaler (serial #275158)

(3) Ludlum L-177 (serial #208778)

(4) Ludlum L-177 (serial #105127)

(5) Ludlum E-140N (serial #1925)

(6) MGP Telepole (serial #6616-037)

(7) Ludlum model 2241 (serial #195221)

(8) Eberline R0-20 (serial #12679)

(9) Mirion DMC 3000 (serial #A15F3C)

(10) Mirion DMC 3000 (serial #A179CB)

Effluent Monitoring Calibration and Testing Program (IP Section 03.03) (2 Samples)

The inspectors evaluated the calibration and maintenance of the following radioactive effluent monitoring and measurement instrumentation:

(1) Unit 2 stack gaseous processing radiation monitor RM-8132B

(2) Unit 3 ventilation vent stack (turbine building) radiation monitor 3HVR*RIY10A

OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:

IE01: Unplanned Scrams per 7000 Critical Hours (IP Section 02.01) ===

(1) Unit 2, April 1, 2022, through March 31, 2023

(2) Unit 3, April 1, 2022, through March 31, 2023

IE03: Unplanned Power Changes per 7000 Critical Hours (IP Section 02.02) (2 Samples)

(1) Unit 2, April 1, 2022, through March 31, 2023

(2) Unit 3, April 1, 2022, through March 31, 2023

IE04: Unplanned Scrams with Complications (IP Section 02.03) (2 Samples)

(1) Unit 2, April 1, 2022, through March 31, 2023

(2) Unit 3, April 1, 2022, through March 31, 2023

EP01: Drill/Exercise Performance (IP Section 02.12) (1 Sample)

(1) July 1, 2022, through March 31, 2023 EP02: Emergency Response Organization Drill Participation (IP Section 02.13) (1 Sample)

(1) July 1, 2022, through March 31, 2023

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

(1) July 1, 2022, through March 31, 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) Cause evaluation and corrective actions associated with the '3A' emergency diesel generator overspeed trip due to foreign material inside the governor (CA1122879)

(2) Unit 3 condensate surge tank (M33CNS-TK2) weld repair

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

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

(1) Unit 2 inverter condition reports and corrective actions

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

(1) Unit 2 degraded piping and supports in the service water pipe tunnel on April 26, 2023 (CR1225999)

INSPECTION RESULTS

Failure to Perform General Condition Monitoring Inspections and System Engineering Walkdowns of Portions of the Safety-Related Service Water System in Accordance with Documented Procedures Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [P.1] - 71111.12 Systems NCV 05000336/2023002-01 Identification Open/Closed The inspectors identified a Green finding and associated NCV of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, when the licensee did not accomplish activities affecting quality in accordance with documented procedures.

Specifically, for portions of the service water system piping located in the service water pipe tunnel, the licensee did not perform general condition monitoring inspections in accordance with ETE-MP-2013-1062, General Condition Monitoring Activities, License Renewal Aging Management Program, and did not perform system engineering walkdowns in accordance with ER-AA-101, System Engineering Walkdowns. Failure to implement these procedures resulted in reasonable doubt about the structural integrity of the service water piping in the service water pipe tunnel.

Description:

On April 14, 2023, when Unit 2 was in Mode 6, the NRC inspectors performed a walkdown of the Unit 2 service water piping in the service water pipe tunnel. During this inspection, the inspectors questioned several American Society of Mechanical Engineers, Class III, Seismic Category I, structural supports, and pipe flanges that showed signs of excessive corrosion. The service water system and associated piping is safety-related.

The licensee documented the inspectors concerns in the corrective action program as CR1224562 and took action to clean, inspect, and evaluate the as-found condition. On April 25, 2023, during post-cleaning inspections of the supports, the licensee noted that a safety-related support had experienced 26 percent outside diameter wall loss due to corrosion. The licensee wrote CR1225934 and initiated corrective actions to replace the support. The licensee did not intend to perform any further inspections of the service water pipe tunnel.

On April 25, 2023, the inspectors performed a follow-up walkdown with licensee engineering personnel to review the corrective actions taken to resolve the initial concerns. During this inspection, the inspectors questioned why additional extent-of-condition inspections of the service water piping system were not performed when the entire section of pipe and structural supports were subject to the same degradation mechanism (i.e., ground water intrusion, condensation, and high humidity). Follow-up extent-of-condition external piping inspections of both the 'A' and 'B' train service water piping identified numerous pipe supports, gland rings, and associated hardware, with various levels of degradation. Prior to final system close-out on May 9, 2023, a 6 drop per minute leak was discovered adjacent to a gland ring at a bell and spigot joint on the 'A' service water train. Further interrogation of the leak identified two through-wall flaws.

The licensee evaluated the degraded condition and could not demonstrate the structural integrity of the 'A' service water header piping. The licensee determined the magnitude of the flaw provided reasonable evidence that the flaw and loss of structural integrity existed during the past operating cycle for a period longer than the technical specification action statement allowed outage time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Therefore, the licensee submitted licensee event report 05000336/2023-001-00, Structural Integrity of 'A' Train Service Water Header Piping Could Not Be Demonstrated Causing the Unit to Operate in a Condition Prohibited by Technical Specifications, on July 7, 2023, pursuant to 10 CFR 50.73 (a)(2)(i)(B), as an operation or condition that was prohibited by the plant's technical specifications.

The license renewal aging management program for the service water system is described in ETE-MP-2013-1047, Service Water System (Open-Cycle Cooling), License Renewal Aging Management Program (MP-LR-3715/MP-LR-4715), Revision 0. One of the primary objectives of the program is to maintain protective coatings and service water system piping and components, such that performance is not adversely affected. This engineering technical evaluation further states: Today, system engineers perform regular walkdowns of the service water system and document their results in system health reports. Operations personnel also perform walkdowns during their daily rounds. These walkdowns are further discussed in ETE-MP-2013-1062, General Condition Monitoring Activities, License Renewal Aging Management Program (MP-LR-3736/MP-LR-4736) (Reference 6.2).

1, Section 2.1 of ETE-MP-2013-1062, states, in part, that system engineers perform comprehensive visual inspections during walkdowns of plant systems and components during both normal operation and refueling outages. The walkdown activities ensure that the system engineers maintain current awareness of system and plant material conditions and allow for the identification and resolution of discrepancies. Guidelines for the performance of these walkdowns are provided in ER-AA-SYS-1002, System Engineer Walkdowns, which was superseded by ER-AA-101, System Engineering Walkdowns.

Section 2.1 of ER-AA-101, System Engineering Walkdowns, Revision 7, states, This procedure is credited for performing general condition monitoring inspections and walkdowns as an aging management activity for license renewal. Performance of walkdowns and thorough documentation of identified aging effects is essential for managing aging for license renewal. Section 3.1.1 states, Individual system walkdowns should be scheduled and performed in a manner to ensure the entire system has undergone a complete walkdown for each specified period. Section 3.1.2 states, IF at any time during the walkdown it is determined that the required inspection cannot be performed, THEN CONTACT an engineering supervisor to establish methods to appropriately perform the walkdown.

Section 3.1.15 states, IF evidence of aging is observed during a walkdown, THEN INITIATE a condition report to ensure any follow-up evaluations are initiated and inspections are performed through the work management system.

ER-AA-101 provides a list of examples of walkdown inspection criteria related to aging management. This list included, in part, 1) surfaces do not have excessive rust, material wastage or signs of degradation, cracking, or aging; 2) there is no evidence of steam or water leakage; 3) there is no evidence of degradation (e.g., excessive corrosion or scaling);4) equipment foundations do not exhibit signs of unusual concrete or grout deterioration, erosion, corrosion, chipping, cracking, or spalling; 5) skids, foundations, supports, hangers, and fasteners are not loose, corroded, stressed, seized, or rusted; 6) there is no pitting, crevice corrosion, or heavy general corrosion on unpainted surfaces.

The inspectors noted that the as-found condition of the service water piping tunnel contained many examples of the unacceptable conditions listed above. After the NRCs initial inspections in the service water piping tunnel in April 2023, the licensee created over 30 condition reports to identify and correct these unacceptable conditions.

The inspectors noted that a system engineer had performed a walkdown of the service water pipe tunnel on August 24, 2022, but the inspection attributes were marked as satisfactory and no new condition reports were written. Based on the extent of degradation observed in April 2023, the inspectors concluded that the walkdown performed on August 24, 2022, was not performed in accordance with ETE-MP-2013-1062 and ER-AA-101.

Corrective Actions: The licensee completed a root cause evaluation, three design changes, three use-as-is engineering technical evaluations, and made numerous repairs to piping and supports in the service water pipe tunnel. Additionally, the organization will develop recurring training on early identification of degrading conditions, aging management program implementation, and general condition monitoring.

Corrective Action References: CR1224562, CR1225934, CR1225999, CR1226131 (Root Cause Evaluation), CR1226250, CR1226507, CR1226542, CR1226545, CR1226550, CR1226556, CR1226658, CR1226781, CR1226890, CR1226895, CR1226917, CR1226920, CR1226926, CR1227003, CR1227004, CR1227258, CR1227356, CR1227418, CR1227525, CR1228259, CR1228299, CR1228313, CR1228721, CR1228727, CR1228961, CR1228991, CR1229021, CR1229050

Performance Assessment:

Performance Deficiency: The licensee's failure to perform inspections of the service water system inside the service water pipe tunnel in accordance with ETE-MP-2013-1062 and ER-AA-101 is a performance deficiency. Specifically, portions of the 'A' and 'B' train service water piping and associated structural supports experienced age-related degradation that did not meet established acceptance criteria and was not identified during system engineering walkdowns.

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 'A' service water piping and degraded seismic category I supports resulted in reasonable doubt about the equipments seismic qualifications, which reduced assurance in the equipments availability and reliability. As described by Example 3.e in IMC 0612, Appendix E, the as-found condition was unacceptable, and the licensee had to perform permanent plant modifications to replace the corroded piping and repair or install new seismic category I supports.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process for Findings At-Power, Exhibit 2, Mitigating Systems. While this finding was identified when the plant was shut down in Mode 6, the inspectors used Appendix A because the licensee assumed that the through-wall flaw and degraded structural supports existed prior to the current refueling outage. Based on consultation with a regional senior reactor analyst (SRA), Appendix A best captures the majority fraction of the overall risk. Based on Appendix A, Exhibit 2, Question 3, a detailed risk evaluation was performed by an SRA because the degraded condition, a through-wall flaw in the 'A' service water header piping, represented a loss of the probabilistic risk assessment function of one train of a multi-train technical specification system for greater than its technical specification allowed outage time. The degraded condition affects a portion of service water piping that may impact the functionality and potential diversion of 'A' train service water flow and internal flooding from the pipe tunnel in the turbine building. The SRA used the Systems Analysis Program for Hands-On Integrated Reliability Evaluations (SAPHIRE), Version 8.2.8, and the Millstone Unit 2 Standardized Plant Analysis Risk Model, Version 8.81, which includes turbine building internal flood event trees.

The SRA made the following assumptions based on the degraded condition, a review of the licensee event report, and discussions with the inspectors and licensee. The 'A' service water header was degraded and operated until discovery but considered nonfunctional for all seismic events, the 'A' header had an increased residual failure probability, and the exposure period is bounded at the maximum of 1 year since the degraded condition may have existed since the previous cycle. The SRA used the Service Water Major Flood Catastrophic Rupture of Header 'A' Piping in Turbine Building (FLI-T1ABSW-MF4A) event tree to quantify the residual risk increase and upper bound. The residual increase was determined by increasing the rupture frequency by 5x to account for potential vibration, water hammer, and surges during operation and testing. The mean conditional core damage probability (CCDP)was estimated at 1.5E-7/year (5 percent 3.6E-8/year, 95 percent 4.4E-7). This resulted in a mean delta core damage probably (CDP) increase estimate of [1.5E-7/year (CCDP) -

2.9E-8/year (baseline)] = 1.3E-7/year (CDP). The dominant cutset was a rupture of 'A' service water header, failure to isolate rupture, and operator fails to initiate feed and bleed cooling. The upper bound estimate is enveloped by the most frequent seismic event (BIN-1, 0.1g to 0.3g) frequency (1.060E-4 per year) assuming a rupture failure of the 'A' header (failure probability = 1.0); the mean CCDP estimate of 'A' service water header rupture is 8E-3/year (5 percent 1.8E-3, 95 percent 2.2E-2). This resulted in a mean CDP estimate of

[(8E-3/year (CCDP) - 2.9E-8/year (baseline)]

• 1.06E-4 per year) = 8.5E-7/year (CDP). The dominant cutset was a seismic event, rupture of 'A' service water header, and loss of feedwater and once-thru cooling. No other external events were considered applicable. The SRA used SAPHIRE to calculate large early release frequency (LERF). None of the factors were greater than zero, hence a separate consequential steam generator tube rupture screening was not performed. Therefore, LERF was estimated less than 1E-7/year. The total increase in CDP associated with this performance deficiency is estimated less than 1E-6/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, individuals from multiple departments did not ensure recurring and persistent water intrusion; and excessive corrosion in the service water pipe tunnel were reported in the corrective action program at a low threshold.

Enforcement:

Violation: 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, states, in part, that activities affecting quality shall be accomplished in accordance with instructions, procedures, or drawings.

Section 2.1 of Attachment 1 of ETE-MP-2013-1062, states, in part, that system engineers perform comprehensive visual inspections during walkdowns of plant systems and components during both normal operation and refueling outages. The walkdown activities ensure that the system engineers maintain current awareness of system and plant material conditions and allow for the identification and resolution of discrepancies. Guidelines for the performance of these walkdowns are provided in ER-AA-SYS-1002, System Engineer Walkdowns, which was superseded by ER-AA-101, System Engineering Walkdowns.

Section 3.1.1 of ER-AA-101, System Engineering Walkdowns, Revision 7, states, Individual system walkdowns should be scheduled and performed in a manner to ensure the entire system has undergone a complete walkdown for each specified period. Section 3.1.2 states, IF at any time during the walkdown it is determined that the required inspection cannot be performed, THEN CONTACT an engineering supervisor to establish methods to appropriately perform the walkdown. Section 3.1.15 states, IF evidence of aging is observed during a walkdown, THEN INITIATE a condition report to ensure any follow-up evaluations are initiated and inspections are performed through the work management system.

Contrary to the above, prior to April 2023, activities affecting quality were not accomplished in accordance with documented instructions. Specifically, system engineering walkdowns of safety-related service water piping in the service water pipe tunnel were not accomplished in accordance with the general condition monitoring aging management program (ETE-MP-2013-1062) and system engineering walkdown procedure (ER-AA-101) when engineers did not 1) provide evidence that they inspected and documented all walkdown attributes specified by ER-AA-101, 2) write condition reports after discovering external degradation or water in the service water pipe tunnel, and 3) work with their supervisor to establish methods to perform inspections of piping and supports that were located under long-term scaffolding in the area. The failure to implement these procedures resulted in reasonable doubt about the structural integrity of the service water piping in the service water pipe tunnel.

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

Failure to Maintain Operational Configuration Control of the Reactor Pressure Vessel Head Vent Path During Vacuum Fill of the Reactor Coolant System Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green [H.12] - Avoid 71111.20 NCV 05000336/2023002-02 Complacency Open/Closed A self-revealed Green finding and associated NCV of Millstone Unit 2 Technical Specification 6.8, Procedures, was identified when the licensee did not implement written instructions for filling and venting the RCS. Specifically, the licensee failed to ensure that the RPVH was properly vented prior to vacuum fill activities. As a result, during vacuum fill of the RCS, a void was formed in the RPVH, and actual RCS level was approximately 6 percent less than indicated level during decreased inventory operations.

Description:

On June 16, 2023, with the plant in Mode 5, after completing repairs to a reactor coolant pump seal, which required draining of the RCS to reduced inventory conditions, the licensee filled the RCS using procedure OP 2301G Vacuum Fill of the Reactor Coolant System. At 3:58 a.m., control room operators began filling the RCS with the 'A' containment spray pump. At 6:35 a.m., RCS level instrumentation indicated that pressurizer water level was 90.3 percent. At 7:00 a.m., control room operators recognized the volume of water added to the RCS was lower than expected, and they also noted that during the vacuum fill evolution the reactor vessel level monitoring system in the RPVH had not turned Green, which indicated that there was a possible void in the RPVH.

An operator was sent to the field to reverify valve positions listed on the previous valve line up. At 7:45 a.m., the licensee discovered that the RPVH vent valve (2-RC-039) was in the closed position when it was required to be in the locked open position. The valve alignment had previously been signed as verified locked open by two different field operators, which was incorrect. The formation of the void in the RPVH resulted in inaccurate RCS level indication during the fill of the RCS including when the RCS was in decreased inventory (pressurizer level less than 10 percent).

At 10:56 a.m., the licensee terminated OP 2301G activities because the termination criteria in 1 of the procedure, unexpected plant conditions or response, had been met. At 1:31 p.m., the licensee took action to restore proper configuration of the RPVH vent path by locking open 2-RC-039. When 2-RC-039 was opened, water filled the void and the pressurizer level decreased by approximately 6 percent. The licensee estimated that approximately 678 gallons of water moved from the pressurizer to fill the vessel head. At no time during this evolution were any of the shutdown key safety functions (e.g., inventory control or decay heat removal) significantly challenged.

The licensee conducted a human performance review board to investigate why the valve was incorrectly signed off as locked open. The licensees review discovered that on June 15, 2023, the day before the event, the plant equipment operator (PEO) assigned to work on the OP 2301G-001 valve alignment was instructed by the supervisor to only verify valves that were already in the required configuration to support vacuum fill of the RCS. On June 15, 2023, 2-RC-039 was supposed to be closed because the RPVH vent spool piece had not been installed yet. The valve alignment form stated that the Current Configuration of 2-RC-039 is CLOSED and the Required Configuration is LOCKED OPEN. The PEO incorrectly thought that the Required Configuration was CLOSED because the vent spool piece was not installed and signed the valve alignment form. The PEO should have left the step for 2-RC-039 unsigned for the current plant conditions.

This valve alignment also requires that an independent verifier confirm that the valves are in the required position. The independent verifier saw the first PEO in the field. The first PEO told the verifier that they had just verified that 2-RC-039 was closed. The independent verifier went to the valve, checked that it was closed, and incorrectly signed off the form that the valve was in its required position. Both PEOs failed to follow the licensees administrative procedures PI-AA-500, Verification Practices, and PI-AA-5000, Human Performance.

Because 2-RC-039 had been signed off as in its required position, no additional valve alignment checks were performed prior to the start of vacuum refill. The PEOs mindset shifted to what is correct for the current plant condition versus what is required for the upcoming plant condition as directed by the valve lineup procedure.

Corrective Actions: The licensee entered this event in its corrective action program and performed a human performance review board to determine the cause of the mispositioning event.

Corrective Action References: CR1231182

Performance Assessment:

Performance Deficiency: The licensee did not implement OP 2301G-001, Vacuum Fill of the Reactor Coolant System, and PI-AA-5000, Human Performance, which represented a failure to meet Millstone Unit 2 Technical Specification 6.8, Procedures.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Human Performance attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, this human performance event was similar to Example 4.b in IMC 0612, Appendix E, because the failure to properly establish the RPVH vent path in accordance with plant procedures, adversely affected the accuracy of RCS level instrumentation during decreased RCS inventory operations.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix G, Shutdown Safety Significance Determination Process and determined the finding was of very low safety significance, Green, because it did not require a quantitative assessment per Exhibit 2 - Initiating Events Screening Questions.

Cross-Cutting Aspect: H.12 - Avoid Complacency: Individuals recognize and plan for the possibility of mistakes, latent issues, and inherent risk, even while expecting successful outcomes. Individuals implement appropriate error reduction tools. Specifically, the performer of the valve lineup procedure incorrectly assumed that 2-RC-039 was supposed to be closed and signed off the form stating that the valve was in its required position. The performer then communicated this incorrect assumption to the independent verifier, who failed to perform a thorough review of the valve position and instead inappropriately relied on assumptions made by the other operator.

Enforcement:

Violation: Millstone Unit 2 Technical Specification 6.8.1.a requires that written procedures be established, implemented, and maintained for activities described in Appendix A of Regulatory Guide 1.33, Quality Assurance Program Requirements, February 1978.

Section 3 of Regulatory Guide 1.33, Appendix A, requires instructions for filling, venting, and draining the RCS.

Operating procedure OP 2301G-001, Vacuum Fill of the RCS, Revision 3, requires that vent valve, 2-RC-039, be locked open.

Contrary to the above, on June 16, 2023, Unit 2 operations personnel did not implement written procedures for the filling and venting of the RCS. Specifically, operators failed to ensure that RCS vent valve 2-RC-039 was locked open prior to commencing vacuum fill of the RCS, which resulted in the formation of a void in the RPVH causing actual RCS level to be approximately 6 percent less (678 gallons) than indicated level during decreased inventory operations.

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

Failure to Maintain Appropriate Instructions for Energizing and Filling the Reactor Coolant System Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green None (NPP) 71111.20 NCV 05000336/2023002-03 Open/Closed A self-revealed Green finding and associated NCV of Millstone Unit 2 Technical Specification 6.8, Procedures, was identified when the licensee did not maintain appropriate instructions for energizing (pressurizing) and filling the RCS after the system was drained for maintenance activities during the refueling outage. This resulted in a 7 gallon per minute intersystem leak from the RCS to ECCS for approximately 5.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />.

Description:

At 8:50 a.m. on June 7, 2023, with Unit 2 in Mode 5, a PEO identified that 2-CS-153, 'A' ECCS Suction Header Relief Valve, was lifting. Control room operators entered AOP 2568A, RCS Leak, MODE 4, 5, 6, and Defueled, and started the 'C' charging pump to raise RCS level. Operators determined that the RCS leak rate was approximately 7 gallons per minute, and initiated actions in accordance with the AOP to locate the source of the leak.

At 9:47 a.m., the RCS leak was isolated by closing 2-SI-444, 'A' low-pressure safety injection pump suction isolation valve at which point all RCS parameters stabilized and operators exited AOP 2568A. Subsequent evaluation by the licensee determined that after the pressurizer bubble was drawn at approximately 2:50 a.m. on June 7, 2023, pressurizer pressure was raised to 50 psia and ECCS suction pressure rose at the same time. The licensee further noted in its review that pressurizer level began to saw tooth with a 7 gallon per minute lowering rate. This pattern continued for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 57 minutes until 2-SI-444 was fully closed.

Leakage from the relief valve 2-CS-153 was collected by the A safeguard room sump and transferred to the aerated waste tanks. There was no radiological release associated with this leak.

The NRC inspectors noted that a similar event occurred on May 12, 2014, when a 12 gallon per minute leak from the RCS into the ECCS suction header occurred due to 2-SI-444 and 2-SI-432, 'B' low-pressure safety injection pump suction isolation valve, not being fully closed during pressurization of the RCS. The licensee entered the 2014 event in its corrective action program as CR548574 and created a corrective action assignment for the operations department to review operating procedures associated with 2-SI-444 and 2-SI-432.

Specifically, the detailed assignment (CA284628) to operations stated, in part, Determine controls needed to verify these [2-SI-444 and 2-SI-437] valves are seated with sufficient force to seat. Also need a monitoring method to ensure that when RCS is pressurized, that the ECCS suction header pressure is monitored. This may include ensuring a containment spray pump is aligned with the suction valve open and recirculation isolated, or by installing a pressure gauge at 2-CS-33 to monitor pressure. Also need steps in plant startup procedures to monitor these pressures when drawing the pressurizer bubble and raising RCS pressure.

From this corrective action, the licensee revised several operating procedures associated with plant heat up (OP 2201), plant cooldown (OP 2207), and with operation of the shutdown cooling system (OP 2310) but failed to revise procedures associated with drawing the pressurizer bubble. Specifically, the licensee did not update OP 2301D, Filling and Venting the RCS, and OP 2301G, Vacuum Fill of the RCS, to ensure 2-SI-444 and 2-SI-432 were fully seated and did not add steps in the procedures to monitor ECCS suction header pressure when drawing the pressurizer bubble and raising RCS pressure. The failure to update OP 2301G with this guidance resulted in the loss of RCS inventory event that occurred on June 7, 2023.

At no time during this evolution were any of the shutdown key safety functions (e.g., inventory control or decay heat removal) significantly challenged.

Corrective Actions: When the licensee discovered 2-SI-444 not fully seated, PEOs closed the valve, which stopped the RCS leak. The licensee entered the issue in its corrective action program.

Corrective Action References: CR1230367, CR1233480

Performance Assessment:

Performance Deficiency: The licensee did not maintain appropriate procedures for pressurizing the RCS as required by Millstone Unit 2 Technical Specification 6.8.1.a.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Procedure Quality attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, it impacted the Procedure Quality attribute because the operating procedures for filling the RCS after being drained for maintenance activities did not provide instructions to ensure isolation between the RCS and ECCS and monitor ECCS suction header pressure during initial system pressurization. This resulted in a 7 gallon per minute intersystem leak from the RCS to ECCS.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix G, Shutdown Safety Significance Determination Process. The finding screened as Green because it did not require a quantitative assessment per Exhibit 2 - Initiating Events Screening Questions.

Cross-Cutting Aspect: Not Present Performance. No cross-cutting aspect was assigned to this finding because the inspectors determined the finding did not reflect present licensee performance.

Enforcement:

Violation: Millstone Unit 2 Technical Specification 6.8.1.a requires that written procedures be established, implemented, and maintained for activities described in Appendix A of Regulatory Guide 1.33, Quality Assurance Program Requirements, February 1978.

Section 3, Procedures for Startup, Operation, and Shutdown of Safety-Related Pressurized-Water Reactor Systems, of Regulatory Guide 1.33, Appendix A, requires the licensee to prepare appropriate instructions for energizing, filling, venting, draining, startup, shutdown, and changing modes of operation for the RCS.

Contrary to the above, prior to June 7, 2023, the licensee did not maintain appropriate instructions for energizing and filling the RCS. Specifically, the licensee did not maintain plant procedures used for initial pressurization of the RCS after it was drained for maintenance activities. Operating procedures 2301D, Filling and Venting the RCS, and 2301G, Vacuum Fill of the RCS, did not contain adequate instructions to 1) ensure isolation between the RCS and ECCS, and 2) monitor ECCS suction header pressure during initial system pressurization. This resulted in a 7 gallon per minute intersystem leak from the RCS to ECCS, which went unnoticed by control room operators for approximately 5.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />.

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

Observation: Unit 3 Condensate Surge Tank (M33CNS-TK2) Weld Repair 71152A The inspectors reviewed the licensee's evaluation and corrective actions to address the Unit 3 condensate surge tank (CNS-TK2) leak as documented in CR1161767. The inspectors determined that the licensee-initiated actions to sample and evaluate the leakage for reportability included the leakage in the monthly liquid release surveillance, installed a catch container to direct the leakage to a monitored pathway, applied a temporary repair, and completed a permanent repair in May 2022.

The inspectors reviewed the last condensate surge tank examinations results and independently walked down the condensate surge tanks and did not identify deficiencies. The inspectors reviewed the permanent repair welding procedures and work orders, including nondestructive examinations and post-maintenance testing results, and did not identify issues of concerns.

The inspectors reviewed the licensee's screening, prioritization, and adequacy of the implemented corrective actions to address the problem. Based on the documents reviewed, system repair walkdowns, and discussions with engineering personnel, the inspectors did not identify issues of concern regarding the licensees evaluation and associated corrective actions.

The inspectors did not identify any violations or performance deficiencies.

Observation: Unit 2 Inverter Condition Report Trend 71152S The inspectors reviewed 10 condition reports associated with intermittent alarms on the Unit 2 inverters, the majority of which were regarding the trouble and out of sync alarms on inverters 2 and 6. Inverter 6 stays in sync with inverter 2 and serves as a backup power supply for emergency alternating current systems. It was discovered that for a fraction of a second, inverter 6 would fall out of sync with inverter 2 and bring in the alarms. Other CRs associated with the Unit 2 inverters had similar events unfold with other inverters involved.

For each of these alarms, troubleshooting was carried out. Corrective actions included verifying an adjustable potentiometer was set at factory settings during the most recent outage and installing an AstroNova monitoring system to gather data the next time a similar event occurs.

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 April 18, 2023, the inspectors presented the inservice activities inspection results to Lori Armstrong, Director, Safety and Licensing, and other members of the licensee staff.

• On April 20, 2023, the inspectors presented the radiological hazard assessment exposure controls inspection results to Michael O'Connor, Site Vice President, and other members of the licensee staff.

• On May 23, 2023, the inspectors presented the Unit 2 direct current power inverters inspection results to Daniel Beachy, Licensing and NRC Coordinator Supervisor, and other members of the licensee staff.

• On May 25, 2023, the inspectors presented the Unit 3 condensate surge tank weld defects resulting in leakage inspection results to Daniel Beachy, Licensing and NRC Coordinator Supervisor, and other members of the licensee staff.

• On May 25, 2023, the inspectors presented the emergency preparedness program inspection results to Michael O'Connor, Site Vice President, and other members of the licensee staff.

• On June 8, 2023, the inspectors presented the radiation monitoring instrumentation inspection results to Michael O'Connor, Site Vice President, and other members of the licensee staff.

• On August 3, 2023, the inspectors presented the integrated inspection results to Lori Armstrong, Director Nuclear Station Safety and Licensing, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.04 Drawings 25203-26014 PI&D Reactor Coolant System Sheets 1 Revision 43

203-26015 PI&D Low-Pressure Safety Injection Sheets 1 Revision 50

71111.04 Procedures OP 2310 Shutdown Cooling System Revision 37

71111.12 Corrective Action CR1224562

Documents CR1225934

Resulting from CR1225999

Inspection CR1226098

CR1226131

CR1226249

CR1226250

CR1226253

CR1226285

CR1226542

CR1226545

CR1226550

CR1226556

CR1226598

CR1226658

CR1226664

CR1226781

CR1226888

CR1226895

CR1226915

CR1226917

CR1226918

CR1226920

CR1226926

CR1227003

CR1227004

CR1227005

CR1227101

CR1227258

Inspection Type Designation Description or Title Revision or

Procedure Date

CR1227356

CR1227460

CR1227464

CR1227602

CR1227758

CR1227787

CR1227813

CR1227908

CR1228299

CR1228436

CR1228721

CR1228727

CR1228772

CR1228920

CR1228991

CR1229021

CR1229050

CR1229064

CR1229098

71111.12 Procedures MA-AA-100 Conduct of Maintenance Revision 24

MS-AA-WHS-131 Storage and Handling Revision 14

71111.13 Engineering MP-DC-000-MP2- CRP-909 Panel Replacement Revision 1

Changes 21-01048

71111.13 Procedures OP 2351 Convex 345 KV Switchgear Revision 022

OP-MP-601 Protected Equipment Revision 37

WM-AA-301 Operational Risk Assessment, Attachment 2 Revision 24

71111.15 Engineering ETE-MP-2023- Use-As-Is Degraded Condition Assessment of 24"-KE-1 Revision 0

Evaluations 1038 Flanges, Bolting and 16"-KE-1 Tie Rod SW to RBCCW /

TBCCW

ETE-MP-2023- Concrete Anchor Supports for Baseplates with Less Than Revision 1

1040 Full Thread Engagement in the MPS Unit 2 Service Water

Tunnel

ETE-MP-2023- Unit 2 Structural Evaluation of Service Water Tunnel Revision 0

1042 Supports for Use As-Is Disposition

ETE-MP-2023- Unit 2 Functionality Assessment of Compensatory Cooling Revision 1

1043 for the East 125VDC Switchgear Ventilation Out of Service

for the X169A Vital Chiller

71111.18 Engineering MP2-23-01053 Unit 2 "B" Train Service Water Tunnel Pipe Support Revision 0

Changes Modifications (Line 24-KE-1)

MP2-23-01054 Unit 2 "A" Train Service Water Tunnel Pipe Support Revision 0

Modifications (Line 24-KE-1)

MP2-23-01060 Unit 2 "A" Train 24"-KE-1 Service Water Pipe Degradation Revision 1

Restoration

71111.20 Procedures MP 2704S1 Containment Equipment Hatch Emergency Closing Revision 5

OP 2264 Conduct of Outages Revision 15

OP 2301E Draining the RCS (ICCE) Revision 37

OP 2301G Vacuum Fill of the Reactor Coolant System (ICCE) Revision 9

OP 2310 Shutdown Cooling System Revision 37

OU-AA-200 Shutdown Risk Management Revision 13

71111.20 Work Orders 53203320868

71111.24 Procedures SP 2064AR-001 'A' HPSI Comprehensive Pump Test, Mode 6 and Defueled Revision 3

SP 2064AR-002 'B' HPSI Comprehensive Pump Test, Mode 6 and Defueled Revision 4

SP 2604AO-002 'B' HPSI Pump and Check Valve IST, Facility 1 Revision 5

SP 2604BO-002 'B' HPSI Pump and Check Valve IST, Facility 2 Revision 5

SP 2605D Containment Leak Test, Type "C" Revision 023

SP 2605D-061 Containment Leak Test Type "C," Penetration 83, 2-EB-99, Revision 01

100

SP 2613H Integrated Test of Facility 2 Components (ICCE) Revision 22

SP 2613H-01 Facility 2 ESF Integrated Test Data Sheet Revision 015

71114.05 Miscellaneous MP-PROC-EP- Millstone Station Emergency Plan Revision 65

MP-26-EPI-EPMP

71152A Corrective Action CR1161767

Documents CR1163736

CR1163893

CR1165636

CR1187236

CR1187876

CR1187996

CR1188075

CR1188078

CR1188081

CR1188807

CR1191419

CR1197940

CR1200068

CR1204598

CR1208382

CR1219984

CR390799

71152A Procedures EN 31154 Tank Inspection Plan 07/29/2022

MP-02-NO- Visual Weld Acceptance Criteria for Weldments and Brazed 07/14/2016

FAP04.3 Joints

PI-AA-200 Corrective Action Revision 41

71152A Work Orders 53102289817

53102787722

203251961

203259267

203302697

203304573

203306104

203306105

203335461

203355375

71152S Corrective Action CR1149942

Documents CR1153226

CR1154035

CR1160748

CR1164448

CR1166073

CR1190514

CR1206488

CR1211236

CR1211482

71152S Engineering MP2-14-01130 MP2 Inverter Replacements (INV1, INV3, INV5) Revision 010

Changes

MP2-14-01158 MP2 Inverter Replacements (INV2, INV4, INV6) Revision 2

MP2-23-01045 Temporary Testing Instrumentation for Unit 2 Inverter Revision 2

M2INV2

71152S Procedures CM-AA-TCC-204 Temporary Configuration Changes Revision 11

PI-AA-200 Corrective Action Revision 41

71152S Work Orders 53203307197 Revision 0

29