IR 05000336/2021010
| ML21137A170 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/17/2021 |
| From: | Mel Gray Division of Operating Reactors |
| To: | Stoddard D Dominion Energy |
| Gray M | |
| References | |
| IR 2021010 | |
| Download: ML21137A170 (20) | |
Text
May 17, 2021
SUBJECT:
MILLSTONE POWER STATION, UNITS 2 AND 3 - DESIGN BASES ASSURANCE INSPECTION (TEAMS) INSPECTION REPORT 05000336/2021010 AND 05000423/2021010
Dear Mr. Stoddard:
On April 23, 2021, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station, Units 2 and 3, and discussed the results of this inspection with Mr.
John Daugherty, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.
Two findings of very low safety significance (Green) are documented in this report. One of these findings involved a violation of NRC requirements. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.
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 Senior 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 Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region I; and the NRC Senior 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, X
/RA/
Signed by: Melvin K. Gray
Mel Gray, Chief Engineering Branch 1 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:
Report Numbers:
05000336/2021010 and 05000423/2021010
Enterprise Identifier: I-2021-010-0025
Licensee:
Dominion Energy Nuclear Connecticut, Inc
Facility:
Millstone Power Station, Units 2 and 3
Location:
Waterford, CT 06385
Inspection Dates:
April 5, 2021 to April 23, 2021
Inspectors:
J. Ambrosini, Senior Emergency Preparedness Inspector
C. Bickett, Senior Reactor Inspector
J. Brand, Reactor Inspector
P. Cataldo, Senior Reactor Inspector
J. DeBoer, Senior Project Engineer
L. Dumont, Reactor Inspector
J. Schoppy, Senior Reactor Inspector
Approved By:
Mel Gray, Chief
Engineering Branch 1
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a design bases assurance inspection (teams) 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 Test the Beyond Design Basis FLEX 120 VAC Gensets in Accordance with Design Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000336,05000423/2021010-01 Open/Closed
[H.6] - Design Margins 71111.21M The team identified a Green finding in that Dominion did not test the beyond design basis 120 VAC gensets in accordance with ETE-CPR-2012-0009 (Unit 2) and ETE-CPR-2012-0008 (Unit 3), Beyond Design Basis - FLEX Strategy Basis Document and Final Integrated Plan. Specifically, Dominion did not complete periodic performance verification testing of the 120 VAC gensets at the loading and voltage specifications required by their system design calculations.
Failure to Identify and Correct 2A Service Water Strainer Outlet Nozzle Corrosion Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000336/2021010-02 Open/Closed
[P.1] -
Identification 71111.21M The team identified a finding of very low safety significance (Green) and an associated NCV of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action. Specifically, Dominion did not identify and correct exterior corrosion on the 2A service water (SW) strainer outlet nozzle.
Additional Tracking Items
Type Issue Number Title Report Section Status URI 05000336/2021010-03 Unit 2 Service Water Restoration Time following a Design Basis External Flood 71111.21M Open
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
Starting on March 20, 2020, in response to the National Emergency declared by the President of the United States on the public health risks of the coronavirus (COVID-19), inspectors were directed to begin telework. In addition, regional baseline inspections were evaluated to determine if all or portion of the objectives and requirements stated in the IP could be performed remotely. If the inspections could be performed remotely, they were conducted per the applicable IP. In some cases, portions of an IP were completed remotely and on site. The inspections documented below met the objectives and requirements for completion of the IP.
REACTOR SAFETY
===71111.21M - Design Bases Assurance Inspection (Teams)
The inspectors evaluated the following components and listed applicable attributes, permanent modifications, and operating experience:
Design Review - Risk-Significant/Low Design Margin Components (IP Section 02.02)
=
- (1) Unit 2 Shutdown Cooling Suction Header Containment Isolation Valve (MOV-2-SI-651)
- Material condition and installed configuration (e.g., visual inspection/walkdown)
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- System health report, maintenance effectiveness and records, and corrective action history
- Equipment/environmental controls and qualification
- Operator actions
- Design calculations
- Permissive interlocks
- Surveillance testing and recent test results
- Equipment protection (sealing of cable and conduits)
- Equipment protection from fire, flood, and water intrusion or spray
The team used Appendix B guidance for Valves, Instrumentation, and As-Built System.
- (2) Unit 3 Refueling Water Storage Tank (QSS*TK1)
- Material condition and installed configuration (e.g., visual inspection/walkdown)
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- System health report, maintenance effectiveness and records, and corrective action history
- Modifications
- Operator actions
- Design calculations
- Instrumentation (range, accuracy, and setpoint)
- Surveillance testing and recent test results
- Process medium (water level and temperature)
The team used Appendix B guidance for Instrumentation and As-Built System.
- (3) Unit 2 125 Vdc Battery 201B (DB1-201B) and 125 Vdc Bus 201B
- Material condition and installed configuration (e.g., visual inspection/walkdown)
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- System health report, maintenance effectiveness and records, and corrective action history
- Control logic
- Design calculations
- Surveillance testing and recent test results
- Equipment protection (sealing of cable and conduits)
- Environmental conditions
- Contactor and fuse ratings; Component adequacy for minimum voltage
- Protection coordination; Load in-rush and full load current
- Range, accuracy, and setpoint of installed instrumentation
- Equipment protection from fire, flood, and water intrusion or spray
The team used Appendix B guidance for Instrumentation, Circuit Breakers and Fuses, Cables, Electric Loads, and Motor Control Centers (MCCs).
- (4) Unit 2 Service Water Strainer Common Cause Failure
- Material condition and installed configuration (e.g., visual inspection/walkdown)
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- System health report, maintenance effectiveness and records, and corrective action history
- Modifications
- Protection coordination (thermal overloads)
- Operator actions
- Design calculations
- Surveillance testing and recent test results
- Process medium The team used Appendix B guidance for Instrumentation, Circuit Breakers and Fuses, and As-Built System.
- (5) Unit 3 Emergency Generator Load Sequencer B (3RPSSEQB)
- Material condition and installed configuration (e.g., visual inspection/walkdown)
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- Maintenance effectiveness and records, and corrective action history
- Control logic
- Design calculations
- Surveillance testing and recent test results
- Equipment protection (sealing of cable and conduits)
- Environmental conditions
- Protection coordination; Load in-rush and full load current
- Range, accuracy, and setpoint of installed instrumentation
- Equipment protection from fire, flood, and water intrusion or spray
The team used Appendix B guidance for Instrumentation, Circuit Breakers and Fuses, Cables, Electric Loads, and Motor Control Centers (MCCs).
Design Review - Large Early Release Frequency (LERFs) (IP Section 02.02) (1 Sample)
- (1) Unit 3 Quench Spray Pump Discharge Containment Penetration Isolation Valve 34A (3QSS*MOV34A)
- Material condition and installed configuration (e.g., visual inspection/walkdown)
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- System health report, maintenance effectiveness and records, and corrective action history
- Equipment/environmental controls and qualification
- Operator actions
- Design calculations
- Permissive interlocks
- Surveillance testing and recent test results
- Equipment protection (sealing of cable and conduits)
- Equipment protection from fire, flood, and water intrusion or spray
The team used Appendix B guidance for Valves, Instrumentation, and As-Built System.
Modification Review - Permanent Mods (IP Section 02.03) (6 Samples)
- (1) MP2-14-01130, MP2 Inverter Replacements (INV1, INV3, INV5); Operating Experience Smart Sample (OpESS) 2019/01 was used to inform the inspection sample
- (2) MP2-18-00126, Containment Spray System Valves 2-CS-16.1A/B Stem Assembly Upgrades
- (3) MP3-15-01093, Replacement of the Unit 3 RPCCW Pump (3CCP*P1A/B/C) Bearing Trico Constant Oilers
- (4) ETE-MP-2017-1100, Emergency Diesel Generator Heat Exchanger Down Tube Coating - Millstone Unit 3
- (5) ETE-MP-2018-1020, Update MP3 EDG Loading Information as a Result of the EDG Calculation NL-033 Rev. 5, Add. D
- (6) ETE-MP-2020-1024, Acceptance of Motor Overhaul for 3SWP*M1C, S/N CPJ301018
Review of Operating Experience Issues (IP Section 02.06) (3 Samples)
- (1) NRC Information Notice 2018-07: Pump/Turbine Bearing Oil Sight Glass Problems
- (2) NRC Information Notice 2020-02: FLEX Diesel Generator Operational Challenges; NRC Operating Experience Smart Sample (OpESS) 2020/01 was used to inform the inspection sample
- (3) MPR Associates Part 21 - Basler Electric SBSR AVR Card Solder Joints
INSPECTION RESULTS
Failure to Test the Beyond Design Basis FLEX 120 VAC Gensets in Accordance with Design Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems
Green FIN 05000336,05000423/2021010-01 Open/Closed
[H.6] - Design Margins 71111.21M The team identified a Green finding in that Dominion did not test the beyond design basis 120 VAC gensets in accordance with ETE-CPR-2012-0009 (Unit 2) and ETE-CPR-2012-0008 (Unit 3), Beyond Design Basis - FLEX Strategy Basis Document and Final Integrated Plan. Specifically, Dominion did not complete periodic performance verification testing of the 120 VAC gensets at the loading and voltage specifications required by their system design calculations.
Description:
ETE-CPR-2012-0009 (Unit 2) and ETE-CPR-2012-0008 (Unit 3), Beyond Design Basis - FLEX Strategy Basis Document and Final Integrated Plan, Section 17.2, contains the requirements for periodic testing and preventive maintenance of portable equipment that directly performs a FLEX mitigation strategy for the core, including the beyond design basis 120 VAC generator sets (gensets). Because this equipment is not tested in the plant during normal operation, the combination of analyses, periodic equipment maintenance, testing, and training provides high assurance of beyond design basis equipment operational readiness. Dominion documented periodic performance verification testing acceptance criteria and its corresponding bases for the gensets in engineering technical evaluation ETE-CCE-2014-1013. The purpose of this periodic testing was to ensure that the 120 VAC gensets would perform within sufficient margin to meet the electrical requirements of their associated FLEX strategies.
Per ETE-CCE-2014-1013, test acceptance criteria for the 120 VAC gensets (MP-BDB-1UA/1UB/1UC) was operation on resistive load banks at 23 KW for two hours while maintaining output voltage of 124 VAC (within +1.2/-0 volts) and frequency of 60 Hz (within
+/-
.15 Hz) in isochronous mode. Maximum output voltage greater than +5% above nominal
under loaded conditions. The voltage specification was based on the FLEX electrical AC system loading analysis calculations, which assumed a generator output voltage of 125 VAC to ensure a minimum operating voltage at the load when accounting for the voltage drop between the gensets and the instrument panels. Additionally, the FLEX support guidelines directed operators to adjust output voltage to 125 - 126 VAC for Unit 2 and 124 VAC for Unit 3 when restoring power using these gensets during an actual event.
The team reviewed the periodic performance verification testing of the 120 VAC gensets as described in procedures C OP 200.24-002, BDB 120/240 VAC Generator Triennial Functional Testing (MP-BDB-1UA/1UB/1UC), and MA-MP-BDB-101, Semi-Annual or Annual Test of FLEX Equipment. In both procedures, Dominion staff tested the gensets to 20 KW and 120 VAC, which is less than what was required by ETE-CCE-2014-1013. The team also discovered that Dominion staff revised their triennial test procedure on May 30, 2018, which changed output voltage from 246.8 - 249.2 VAC (123.4 - 124.6 VAC line-to-ground) to 238.8 - 241.2 VAC (119.4 - 120.6 VAC line-to-ground). Dominion staff could not locate a documented basis for this procedure change. Based on the lack of documentation, the team concluded that Dominion staff did not apply the appropriate configuration control process for this change as described in their CM-AA-BDB-101, Beyond Design Basis FLEX Program Maintenance. Based on the above review, the team concluded that the 120 VAC gensets had not been tested at the required design specifications since initial site acceptance testing in 2014.
At the time of this inspection, Dominion staff determined that the 120 VAC gensets should be tested to 126 VAC because this value bounded the actual operating requirements specified in the Unit 2 and Unit 3 FLEX support guidelines. Dominion engineering staff also reperformed the voltage drop calculations and demonstrated that when margins related to loading and cable impedance were reduced, the minimum voltage requirements would be met at a generator output voltage of 120 VAC.
NRC Operating Experience Smart Sample 2020-01, FLEX Equipment Design Control, Maintenance, and Testing, contributed to the identification of this finding.
Corrective Actions: Dominion personnel entered the issue into their corrective action program for further evaluation and contacted the vendor. Additionally, Dominion completed loaded and unloaded test runs of the 120VAC gensets at 126 VAC line-to-ground voltage during the week of April 19, 2021.
Corrective Action References: CR1170194
Performance Assessment:
Performance Deficiency: The team determined that failure to test the 120 VAC beyond design basis gensets in accordance with ETE-CPR-2012-0009 (Unit 2) and ETE-CPR-2012-0008 (Unit 3), Beyond Design Basis - FLEX Strategy Basis Document and Final Integrated Plan, was a performance deficiency that was reasonably within Dominions ability to foresee and prevent.
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, since Dominion staff had not tested the 120 VAC gensets at the required load and voltage since initial site acceptance testing in 2014, there had been no verification that the equipment has maintained the reliability and capability to perform within sufficient margin to meet the electrical requirements of their associated FLEX strategies. Additionally, these testing deficiencies and inconsistencies in the documented voltage requirements between the FLEX support guidelines, design calculations, and test procedures, led the team to conclude that this performance deficiency was similar to IMC 0612, Appendix E, Examples of Minor Issues, Example 3.a, in that there was reasonable doubt as to the functionality of the 120 VAC gensets. Example 3.a is specifically applicable because Dominion engineering staff performed a calculation to show that minimum voltage requirements would be met at 120 VAC genset output. However, this calculation required assumptions to be changed to obtain favorable results as conservatisms related to actual loading and cable impedance values were reduced.
Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The team evaluated this finding in accordance with IMC 0609, Significance Determination Process. Because the finding impacted the Mitigating Systems cornerstone, the team screened the finding through IMC 0609, Appendix A, The Significance Determination Process for Findings At-Power, using Exhibit 2, Mitigating Systems Screening Questions. The finding screened as of very low safety significance (Green) because it did not involve equipment, training, procedures, and/or other programmatic aspects credited in any Phase 1 or 2 FLEX strategy such that any FLEX function (such as extended HPCI/RCIC/AFW operation, providing FLEX DC power, FLEX AC power, or FLEX RCS feed) could not be completed in accordance with existing plant procedures within the time allotted for an exposure period of greater than 21 days.
Cross-Cutting Aspect: H.6 - Design Margins: The organization operates and maintains equipment within design margins. Margins are carefully guarded and changed only through a systematic and rigorous process. Special attention is placed on maintaining fission product barriers, defense-in-depth, and safety related equipment. On May 30, 2018, Dominion personnel lowered the voltage acceptance criteria for the triennial test procedure without applying the appropriate configuration control process, as described in CM-AA-BDB-101, Beyond Design Basis FLEX Program Maintenance.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
Failure to Identify and Correct 2A Service Water Strainer Outlet Nozzle Corrosion Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems
Green NCV 05000336/2021010-02 Open/Closed
[P.1] -
Identification 71111.21M The team identified a finding of very low safety significance (Green) and an associated NCV of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action. Specifically, Dominion did not identify and correct exterior corrosion on the 2A service water (SW) strainer outlet nozzle.
Description:
On April 7, 2021, during a walkdown of the Unit 2 intake structure, the team identified damaged protective paint and carbon steel corrosion on the exterior bottom portion of the 2A SW strainer outlet nozzle. The team noted pieces of paint and flakes of carbon steel corrosion product on the floor beneath the strainer outlet nozzle. In response to this observation, Dominion operations and engineering personnel performed a walkdown of the Unit 2 SW system in the intake area and initiated condition report (CR) 1169729. Dominion personnel generated work order (WO) 53203309786 to clean the corrosion area and perform an ultrasonic test (UT) of the bounded area (approximately 1 by 1).
Dominion in-service inspectors (ISI) performed the UT and determined that the general wall thickness adjacent to the pitting was between 0.342 to 0.360 and the worst/deepest pit was 0.125 deep. This resulted in a remaining wall thickness of 0.228 which was less than the minimum wall thickness in the strainer design documentation. Engineering staff determined that the 2A SW strainer was operable but not fully qualified (non-conforming). In order to justify the structural integrity of the as-found strainer condition, Dominion engineering staff used a different methodology because the original approach resulted in unfavorable margin (the as-found minimum wall thickness was less than the strainer design minimum wall thickness for this localized wall thinning area). Dominion staff used the branch reinforcement method described in ASME Code Section VIII to achieve favorable margin.
The team noted that Dominion procedures MP-PROC-OPS-SP 2669A, Plant Equipment Operator Rounds, Revision 22, and MP-PROC-000-ER-AA-101, System Engineer Rounds, Revision 4, included steps to verify no evidence/signs of degradation. The team noted that the as-found exterior corrosion appeared to be age-related and evident for a sufficient duration for plant equipment operators and/or engineers to identify the adverse condition before the team identified it on April 7, 2021. In addition, the team observed that Dominion personnel initiated numerous corrective action CRs dating back to April 2015 for excessive packing leakage on the 2A SW strainer. Although Dominion took action on several occasions to repaint external portions of the strainer, the team noted that the adverse impact of the strainer packing leakage was evident to Dominion personnel. Specifically, the plant impact description in many of the associated CRs included phrases such as:
- (2) past experience has shown that if this leakage is not taken care of that water will collect on the underside and lead to corrosion of the strainer bottom, and
- (3) continued wetting of the area however is a precursor to exterior corrosion. Based on the above, the team concluded that it was reasonable for Dominion personnel to identify and correct the degraded condition prior to the teams identification of such during the inspection.
Corrective Actions: Dominion personnel entered the issue into their corrective action program and performed walkdowns, UT exams, and structural integrity evaluations.
Dominions evaluation provided reasonable assurance that the Unit 2 SW system was operable but non-conforming with the design and licensing bases. Dominion used the branch reinforcement method described in the Section VIII Code to achieve favorable margin for the localized wall thinning area only. Dominion staff planned to engage with the strainer vendor to revise the design analysis of the subject strainer to restore full qualification.
Corrective Action References: CR 1169729
Performance Assessment:
Performance Deficiency: The team determined that failing to identify and correct corrosion on the Unit 2 A service water strainer outlet nozzle was a performance deficiency that was reasonably within Dominions ability to foresee and prevent.
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 wall thickness of the strainer outlet nozzle was less than the design minimum wall thickness. Additionally, the performance deficiency is similar to IMC 0612, Appendix E, Example of Minor Issues, Example 3.f. in that Dominion staff used a different method described in ASME Section VIII code to achieve favorable wall thickness margin.
Significance: The inspectors assessed the significance of the finding using Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The finding was evaluated using the significance determination process in accordance with IMC 0609, Significance Determination Process, Attachment 0609.04, Initial Characterization of Findings. Because the finding impacted the Mitigating Systems cornerstone, the team screened the finding through IMC 0609, Appendix A, The Significance Determination Process for Findings At-Power, using Exhibit 2, Mitigating Systems Screening Questions. The finding screened as of very low safety significance (Green) because it did not result in the loss of operability or functionality of mitigating systems. Because the finding also had the potential to impact the Initiating Events cornerstone, the team screened the finding through IMC 0609, Appendix A, The Significance Determination Process for Findings At-Power, using Exhibit 1, Initiating Events Screening Questions. The finding screened as of very low safety significance (Green)because the degraded condition did not result in an actual or complete loss of the SW support system and did not increase the likelihood of a complete loss of a SW that would result in a plant trip.
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. Dominion personnel did not promptly identify visible corrosion on the 2A SW strainer outlet nozzle.
Enforcement:
Violation: The team identified a violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, which states, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and non-conformances are promptly identified and corrected. Contrary to the above, Dominion did not identify the 2A SW strainer outlet nozzle corrosion before the team identified this condition on April 7, 2021.
Disposition: Because this violation is of very low safety significance and has been entered into Dominions corrective action program as CR 1169729, this violation is being treated as an NCV consistent with Section 2.3.2 of the NRC Enforcement Policy.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
Unresolved Item (Open)
Unit 2 Service Water Restoration Time following a Design Basis External Flood URI 05000336/2021010-03 71111.21M
Description:
Unit 2 Updated Final Safety Analysis Report (UFSAR) Section 2.5.4.2.3, Intake Structure Flood Protection, states, in part, The maximum water level inside the intake structure caused by the standing wave condition is calculated to reach elevation 26.5 feet MSL. The analysis was performed utilizing an unsteady state mathematical model that takes into account the profile of the incident wave, in leakage through the louvers and system head loss. One service water pump motor is protected. Based on the as-built configuration, the continued operability of the Unit 2 SW pump motors would be adversely impacted if the intake water level increased beyond 22 feet main sea level (MSL). UFSAR Section 2.5.4.2.1, Study of Flooding Potential from Design Basis Hurricane, states, in part, If the water level within the Intake Structure rises to 22 feet MSL, thereby endangering the service water pump motors, the diesel operating on service water would be secured and the Service Water Pumps would be tripped in accordance with plant procedures. The justification for the duration of time without SW included the following in UFSAR Section 2.5.4.2.1.B.3.c, Service water will be maintained, except for a maximum period of 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. This is based on the duration of the intake water level above 22 feet MSL which is calculated to be 2.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> plus the time to recommission the previously protected motor which is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
The team noted that procedure MP-PROC-OPS-AOP 2560, Storms, High Winds and High Tides, Step 4.3 directs personnel to Step 4.5 if water level, including wave crest height, exceeds grade level (14.0 feet above MSL). In addition, Step 4.4 directs personnel to Step 4.5 if certain specified severe storm conditions exist simultaneously. Step 4.5.f directs personnel to install the portable can on one of the operable SW pump motors in accordance with MP 2721C, Protection and Restoration of Service Water Pump and Strainer Motor During a PMH. Subsequently, MP-PROC-OPS-AOP 2560 Step 5.1 states, in part, When water recedes to less than 14 feet, remove the can and electrically connect the service water pump.
Based on a walkdown of the Unit 2 SW intake area and a procedure review, the team identified an apparent disconnect between the UFSAR description and the implementing procedure (AOP 2560). Specifically, AOP 2560 does not direct restoration of the protected SW pump motor until water level recedes to 14 feet, otherwise the intake structure would still be flooded to some degree. However, the UFSAR description appears to imply that the restoration activities can commence once water level recedes below 22 feet MSL. Based on a review of procedure MP 2721C, the team concluded that the restoration activities could be reasonably completed within two hours; however, this time estimate is predicated on the water receding to approximately 14 feet MSL in the intake area to allow workers to safely accomplish the required tasks (vice working with 8 feet of water in the room). The team noted that this apparent disconnect has the potential to extend the coping duration without SW beyond the previously analyzed maximum time of 4.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
Planned Closure Actions: The team determined that more information is needed to resolve the teams concerns regarding the timely restoration of the Unit 2 SW system following a design basis external flood during hurricane conditions. Specifically, additional information is needed to determine if there is an associated performance deficiency, if there is an associated violation of NRC requirements, and if there is an associated finding of more than minor significance. To support that determination, NRC inspectors will review the results of Dominions evaluation and applicable corrective actions including any revisions to Dominions UFSAR and plant procedures. Based on review of the currently available documentation, the team determined that the issue did not represent an immediate safety concern.
Licensee Actions: Dominion entered this issue into its corrective action program (CR1171836). Dominions short-term actions included a continued search of their licensing basis for the supporting calculation of the bounding times stated in the UFSAR (2.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> with water level above 22 MSL, and 2.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> to restore the protected SW pump) and evaluating any identified inaccuracies and/or deficiencies in the UFSAR description or plant procedures.
Corrective Action References: CR1171836
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On April 23, 2021, the inspectors presented the design bases assurance inspection (teams) inspection results to Mr. John Daugherty, Site Vice President, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
71111.21M Calculations
2013-ENG-
04383E2
Millstone Station Unit 2 Beyond Design Basis - FLEX
Electrical 4160V, 480V, and 120V AC System Loading
Analysis
Revision 2
2013-ENG-
04503E3
Millstone Station Unit 3 Beyond Design Basis - FLEX
Electrical 4160V, 480V, and 120V AC System Loading
Analysis
Revision 2
97-CMP-01930C2 Seismic Qualification of Lubricating Oil Bubblers on
Containment Spray Pumps and HPSI Pumps
Revision 0
97-ENG-01775E2
Battery 201B and Charger Associated Cable Device
Electrical Verification Calculation
Revision 4
MP-CALC-ENG-
04430M2
MP2 Service Water Strainer Degraded Bottom Shell Flange
Compliance with ASME Section VIII at Maximum Allowable
Working Pressure of 100 Psig
Revision 0
NM-027-ALL
MP3 Active Valve Response Times
Revision 4
QSS-MOV-
001381M3
3QSS*MOV34A and B System and Functional Design Basis
Review
Revision 0
US(B)-295
RWST Draw-Down Rates and Switchover Levels
Revision 8
Corrective Action
Documents
CR0377456
CR0576590
CR0578071
CR0581961
CR0581962
CR1016480
CR1027433
CR1059586
CR1104624
CR1104933
CR1106001
CR1107828
CR1108358
CR1109224
CR1125092
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR1135879
CR1147140
CR1151093
CR1151722
CR1152050
CR1152520
CR1153395
CR1154062
CR1157196
CR1159100
CR1160269
CR1161149
CR1164363
CR1165544
Corrective Action
Documents
Resulting from
Inspection
CR1169475
CR1169618
CR1169641
CR1169644
CR1169649
CR1169654
CR1169656
CR1169657
CR1169660
CR1169703
CR1169729
CR1169731
CR1169732
CR1169735
CR1169747
CR1169760
CR1169763
CR1170080
CR1170173
CR1170181
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CR1170194
CR1170196
CR1170280
CR1170281
CR1170626
CR1170639
CR1170646
CR1170647
CR1170677
CR1171836
Engineering
Evaluations
ETE-CCE-2014-
1013
Site Acceptance Testing and Periodic Performance
Verification Testing Acceptance Criteria for BDB FLEX
Strategy Generators - Millstone Station Units 2 and 3
Revision 2
ETE-CPR-2012-
0008
Unit 3 Beyond Design Basis - FLEX Strategy Basis
Document and Final Integrated Plan
Revision 7
ETE-CPR-2012-
0009
Unit 2 Beyond Design Basis - FLEX Strategy Basis
Document and Final Integrated Plan
Revision 7
ETE-MP-2018-
1037
Acceptance of Motor Overhaul for 3SWP*M1B, S/N CP
J301019
Revision 0
MP2-14-01130
MP2 Inverter Replacements (INV1, INV3, INV5)
Revision 10
MP2-18-00126
Containment Spray System Valves 2-CS-16.1A/B Stem
Assembly Upgrade
Revision 0
Miscellaneous
Site Acceptance Testing Results - BDB FLEX Generators
dated
10/8/14
BCT-2000
Unit 2 201B Battery Performance Test
performed
10/16/18
C OP 200.24-001
BDB 480VAC Generator Triennial Functional Testing (MP-
BDB-2UA/2UB/2UC)
performed
6/4/18
C OP 200.24-002
BDB 120/240 VAC Generator Triennial Functional Testing
performed
6/4/18
MA-MP-BDB-101
Semi-Annual or Annual Test of FLEX Equipment
performed
6/30/20 &
2/10/20
MB-2007-01
Maintenance Bulletin Potential for Solder Joint Cracks on
Revision 1
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Basler SBSR AVR Cards
MP-DBS-000-
Design Basis Document for Quench Spray System
Revision 1
Operating
Experience Smart
Sample (OpESS)
2019/01
Commercial Grade Dedication, Procurement, and Design
Control, Maintenance, and Testing
dated
7/10/19
Operating
Experience Smart
Sample (OpESS)
20/01
FLEX Equipment Design Control, Maintenance, and Testing
dated
10/21/20
PIR1100118
IN1807 Pump/Turbine Bearing Oil Sight Glass Problems
dated
2/4/18
SP 3609.9
Quench Spray Pump 3A Header Isolation Valve Stroke Time
Test
performed
10/22/20
V-EC-1869
Applicability of BWROG Magnesium Rotor Inspection Report
to PWRs
Revision 2
Procedures
ARP 2592B.3
Alarm Response for Inverter 3
Revision 7
CM-AA-BDB-101
Beyond Design Basis FLEX Program Maintenance
Revision 6
EOP 25 FSG-05
Initial Assessment and FLEX Equipment Staging
Revision 5
MA-MP-BDB-101
BDB Preventive Maintenance
Revision 7
MP-PROC-OPS-
AOP 2560
Storms, High Winds and High Tides
Revision 20
MP-PROC-OPS-
AOP 2565
Loss of Service Water
Revision 7
Corrective Action
Revision 36
Cause Evaluation
Revision 17
Work Orders
53102295104
53102428562
53102723898
53102749312
53102806464
53102841635
53102852965
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
53102878636
53102878637
53102878639
53162852964
53102958670
53103071865
53103104640
203148330
203148331
203162198
203228845
203232411
203232412
203232567
203238189
203240164
203245131
203269929
203309786
53M29910467