IR 05000369/2021010
| ML21076A113 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 03/17/2021 |
| From: | James Baptist Division of Reactor Safety II |
| To: | Teresa Ray Duke Energy Carolinas |
| References | |
| IR 2021010 | |
| Download: ML21076A113 (14) | |
Text
March 17, 2021
SUBJECT:
MCGUIRE NUCLEAR STATION - DESIGN BASIS ASSURANCE INSPECTION (TEAMS) INSPECTION REPORT 05000369/2021010 AND 05000370/2021010
Dear Mr. Ray:
On February 11, 2021, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at McGuire Nuclear Station and discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.
No findings or violations of more than minor significance were identified during this inspection.
This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely,
/RA/
James B. Baptist, Chief Engineering Branch 1 Division of Reactor Safety
Docket Nos. 05000369 and 05000370 License Nos. NPF-17 and NPF-9
Enclosure:
As stated
REGION II==
INSPECTION REPORT
Enclosure
Docket Numbers:
05000369 and 05000370
License Numbers:
Report Numbers:
05000369/2021010 and 05000370/2021010
Enterprise Identifier: I-2021-010-0032
Licensee:
Duke Energy Carolinas, LLC
Facility:
McGuire Nuclear Station
Location:
Huntersville, North Carolina
Inspection Dates:
January 25, 2021 to February 11, 2021
Inspectors:
A. Beasten, Resident Inspector
P. Braxton, Reactor Inspector
P. Carman, Senior Reactor Inspector
N. Morgan, Reactor Inspector
M. Riley, Reactor Inspector
M. Schwieg, Reactor Inspector
Approved By:
James B. Baptist, Chief Engineering Branch 1 Division of Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a design basis assurance inspection (teams) inspection at McGuire Nuclear Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations
No findings or violations of more than minor significance were identified.
Additional Tracking Items
None.
REPORT DETAILS
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) (4 Samples)
- (1) Unit 1 DC Bus EVDA & EVDD
- Operating Environment
- Compliance with updated final safety analyses report (UFSAR), technical specifications (TS), and TS bases
- Conformance with manufacturer instructions/recommendation
- Material condition and configuration (i.e., photos provided by licensee)
- Verification of system design requirements (loading, short circuit analysis, etc.)
- Coordination
- Preventive maintenance effectiveness and history
- (2) Emergency Diesel Generator 1B and Ventilation System
- Material condition and installed configuration
- Normal, abnormal, and emergency operating procedures
- Consistency among design and licensing bases and other documents/procedures
- Maintenance effectiveness and records, and corrective action history
- Design calculations
- Surveillance testing and recent test results
- System and component level performance monitoring*
- (3) Unit 2 4160V Bus 2ETB
- Compliance with UFSAR, including applicable design and licensing basis requirements
- Material condition and configuration
- Maintenance effectiveness
- System health reports
- Surveillance test results
- Calculations verifying system design requirements
- Emergency operating procedures
- Operator Actions
(4)2A and 2B Service Water Pumps and associated Discharge Check Valves, 2RN28/30
- UFSAR and other applicable design and licensing basis documents
- Design calculations
- Material condition
- Maintenance effectiveness
- System health reports
- Corrective maintenance records and corrective action history
- Consistency between station documentation and vendor specifications
- Surveillance and inservice testing results
- Power supply and available voltage
- Emergency operating procedures related to time critical operator actions
Design Review - Large Early Release Frequency (LERFs) (IP Section 02.02)===
- (1) Unit 2 Steam Generator Safety Relief Valves
- Normal, abnormal and emergency operation procedures
- UFSAR, design criteria, and other design and licensing basis requirements
- Maintenance effectiveness
- Component health reports, corrective maintenance records, and corrective action history
- Consistency between station documentation and vendor specifications
- Susceptibility to tornado missiles
- Surveillance and in-service testing results
Modification Review - Permanent Mods (IP Section 02.03) (5 Samples)
- (1) EC 416836, Emergency Diesel Generator Intercooler Drain Valve Position
- (4) EC 407983, Replace U2 Cold Leg Injection Check Valves on B and D Loops
Review of Operating Experience Issues (IP Section 02.06) (2 Samples)
- (1) NRC Information Notice 2013-17: Significant Plant Transient Induced by Safety-Related Direct Current Bus Maintenance at Power
- (2) NRC Information Notice 2019-02: Emergency Diesel Generator Excitation System Diode Failures
INSPECTION RESULTS
Very Low Safety Significance Issue Resolution Process: Capability of Diesel Building Ventilation System to Withstand the Effects of a Tornado 71111.21 M
This issue is a current licensing basis question and inspection effort is being discontinued in accordance with the Very Low Safety Significance Issue Resolution (VLSSIR) process. No further evaluation is required.
Description:
The DBAI inspectors identified an issue of concern in that the diesel building ventilation system was not specifically shown to be designed to withstand the effects of a tornado re-pressurization. A tornado pressure increase could potentially damage all diesel building ventilation fans and cause failure of all of the emergency diesel generators (EDGs) to maintain their safety functions due to rapidly increasing room temperatures.
The diesel building ventilation system consist of two large 50 percent capacity ventilation fans, ducts, and diffusers that are arranged to maintain minimum ventilation requirements during diesel operation. The maximum temperature expected in the Diesel Building is 125°F.
During a previous inspection in 2006 (IR 05000369/2006007 and 05000370/2006007), the inspectors identified a concern regarding the impact of depressurizing the diesel building ventilation system (VD) in the event of a design basis tornado. Nuclear condition report NCR1599622 was issued and the licensee developed calculation MCC-1552.08-00-0373, Diesel Room Ventilation Dampers Response to a Design Basis Tornado Event. This calculation determined the pressure experienced within the VD system and the diesel generator room at the McGuire Nuclear Station during the postulated design basis tornado event. This analysis was primarily focused on the differential pressure developed at the inlet backdraft dampers and at the exhaust dampers.
The licensee evaluated the results under calculation MCC-1211.00-00-0145 and determined the inlet and exhaust dampers would remain operable during a design basis tornado event.
The inspectors reviewed these calculations and determined the licensee did not evaluate the impact on the ventilation fans. The re-pressurization would open the inlet dampers and allow air to flow through the intake ductwork and pass the inline ventilation fans to equalize pressure in the diesel generator room. The ventilation fans would be exposed to high differential pressure and the associated high wind velocity. The inspectors calculated the inlet volumetric flow and determined it would exceed the fans rated flow by a factor of 3 times during a design basis tornado. The inspectors considered the effects from smaller tornados
(< 200 miles per hour (mph)). However, the calculated volumetric flow was below the fan's rated flow, and the inspectors did not identify a concern on the impact of the diesel building ventilation fans in this scenario.
The licensee did not have formal calculation to evaluate the impact on the ventilation fans during a design basis tornado. The licensee used the Gothic Model results under calculation MCC-1211.00-00-0145 and estimated the inlet volumetric flow rate would be approximately 50,000 cubic feet per minute (CFM), which is greater than the fans rating of 28,050 CFM. The licensee determined the maximum blade speed could reach 3100 rpm. The vendor stated the design rating of the fan blades was 3200 rpm.
However, this estimate did not consider a scenario with the fans running or starting during the re-pressurization period. The fans normal running speed is 1800 rpm. With the additional inlet wind speed, the fans speed has the potential to increase above nominal and could exceed the blade design rating. Additionally, the licensee did not consider the possible effects of unbalance air flow on the ventilation fans.
The inspectors evaluated the potential impact of loss of the diesel building ventilation fans. Based on recent work orders, the estimated completion time to replace a fan was 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. With the loss of both ventilation fans, the emergency diesel generators would overheat within an hour. Given the close proximity of each units EDGs and offsite power, the design basis tornado event could potentially result in a complete loss of AC emergency power or a station blackout.
The licensee presented information on why they believed the issue of concern is not in their licensing basis. The main design and licensing basis information the inspectors reviewed is detailed in the Licensing Basis section, below. The licensees position was that the ventilation systems do not require tornado protection since they are located inside the diesel building structure which is protected against tornado wind and missile. The inspectors did not agree that the diesel generator ventilation system was protected from the effects of a design basis tornado. The intake dampers open during the re-pressurization phase, which exposes the ventilation fans to the high velocity winds that could damage the turbine blades and prevent the fans from performing their safety function.
Following the inspectors identification of the concern, the licensee entered the issue into their corrective action program as nuclear condition report NCR 02370670, and will evaluate for additional actions.
Licensing Basis: The NRC staff reviewed the licensing basis documents, regulatory requirements, and regulatory correspondence related to the diesel building tornado protection criterion. The main documents reviewed are detailed below.
- UFSAR Section 3.1, Criterion 2: "Structures, systems, and components important to safety are designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions."
- UFSAR Section 3.3.2, Tornado Loading: Defines the tornado loading on Cat 1 structures. Section 3.3.2.1, Applicable Design Parameters, states "The design tornado used in calculating tornado loadings is in conformance with Regulatory Guide 1.76 with the following exceptions: 1. Rotational wind speed is 300 mph. 2.
Translational speed of tornado is 60 mph. 3. Radius of maximum rotational speed is 250 feet. 4. Tornado induced negative pressure differential is 3 psi."
- UFSAR Table 3-4. Summary of Criteria - Mechanical System Components, Diesel Building Ventilation: Fans and filters are protected by virtue of location in the structure designed for tornado wind.
- 10 CFR 50, Appendix A, I. Overall Requirements, Criterion 2Design bases for protection against natural phenomena: Structures, systems, and components important to safety shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions. The design bases for these structures, systems, and components shall reflect:
- (1) Appropriate consideration of the most severe of the natural phenomena that have been historically reported for the site and surrounding area, with sufficient margin for the limited accuracy, quantity, and period of time in which the historical data have been accumulated,
- (2) appropriate combinations of the effects of normal and accident conditions with the effects of the natural phenomena and
- (3) the importance of the safety functions to be performed.
- 10 CFR 50, Appendix B, Criterion III, Design Control: Measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in 10 CFR 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies are correctly translated into specifications, drawings, procedures, and instructions.
- Regulatory Issue Summary (RIS) 2006-23: Notifies licensees of its regulatory position regarding loading effects caused by natural phenomena to safety related systems and components housed inside a structure partially exposed to the outside environment, specifically ventilating and air-conditioning (VAC) systems housed in the EDG room.
- Regulatory Guide 1.76 (issued in March 2007): Provides licensees and applicants with new guidance that the NRC staff considers acceptable for use in selecting the design-basis tornado and design-basis tornado-generated missiles that a nuclear power plant should be designed to withstand to prevent undue risk to the health and safety of the public.
The inspectors were not able to conclude whether the issue of concern was part of the current licensing basis. The inspectors concluded following a reasonable review of the requirements and documentation that the issue could be closed without immediate enforcement action and treated under the very low safety significance issue resolution process.
Significance: A risk evaluation was performed by a regional senior reactor analyst using SAPHIRE Version 8.2.2 and NRC McGuire SPAR model Version 8.57. The conditional analysis assumed failure of the diesel building ventilation fans for tornado initiating events with wind speeds
- (1) greater than 200 mph, and
- (2) 166 - 200 mph, both with a one-year exposure time. The dominant sequences were a tornado initiator accompanied by a loss of offsite power with failures of the emergency diesel generators, the turbine driven auxiliary feedwater (AFW) pump, and operator actions to recover offsite power. The analysis determined that if a performance deficiency was assumed to have existed, it would have resulted in an increase in core damage frequency of <1E-06/year and an estimated increase in large early release frequency of <1E-07/year, representing very low safety significance (Green).
Technical Assistance Request: A technical assistance request (TAR) was not initiated.
Corrective Action Reference: CR
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On February 11, 2021, the inspectors presented the design basis assurance inspection (teams) inspection results to Tom Ray and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
71111.21M Calculations
DPC-1552.08-00-
0133
RSG FSAR Analyses - 15.1.4 - Inadvertent Opening of a
Steam Generator Relief or Safety Valve
Rev. 1
DPC-1552.08-00-
0165
Peak Secondary Pressure Analyses with Inoperable Main
Steam Safety Valves
Rev. 3
MCC -1381.05-00-
214
U1/2, 125V DC Vital I&C Power System (EPL) Short
Circuit Analysis
Rev.9
MCC -1381.05-00-
230
U1/2, 125V DC Vital I&C Power System (EPL)
Voltage Drop Analysis
Rev.9
MCC -1381.05-00-
0335
Unit1/2, NFPA 805 Circuit Breaker and Fuse
Coordination Study
Rev. 33
MCC 1201.05-00-
0011
Nuclear Service Water (RN) Pump and Motor Oil Leak Rate
Operability
Rev. 1
MCC 1205.09-00-
0007
Evaluation of MSSV Set Pressure Uncertainty
Rev. 1
MCC-1206.02-84-
21
Analysis Problem RN-307
Rev. 101
MCC-1211.00-00-
0145
Analysis of VD Damper Response during a Design Basis
Tornado
Rev. 0
MCC-1223.24-00-
0096
RN System flow Balance Acceptance Criteria Calculation
Rev. 18
MCC-1223.24-00-
0102
RN Pump NPSH and Runout Analysis
Rev. 4
MCC-1223.24-00-
0118
Selected RN Flushes - Acceptance Criteria
Rev. 3
MCC-1223.43-00-
0003
Rev. 7
MCC-1381.05-00-
200
U1/2, 125VDC Vital &C Power System (EPL) Battery Sizing
and Battery Charger Sizing
Rev. 11
MCC-1381.05-00-
263
U2, 6.9KV, 4.16KV & 600V Auxiliary Power Systems Safety-
Related Voltage Analysis
Rev. 12
MCC-1381.05-00-
269
Voltage Analysis for SOER 99-01 Loss of Voltage
Conditions - Transferred from Catawba to Nuclear General
Office on 9/22/10
Rev. 3
MCC-1552.08-00-
Diesel Generator Room Ventilation Dampers Response to a
Rev. 0
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
0373
Design Basis Tornado Event
MCM 1320.00-
0005.001
BALDOR (RELIANCE) ELECTRIC COMPANY
QUALIFICATION OF CLASS 1 E MOTORS
Rev. 9
Corrective Action
Documents
239025, AR
279736, AR
286821, AR
296069, NCR
01903670, NCR
2102868
Corrective Action
Documents
Resulting from
Inspection
21 MNS DBAI Identified Error on MCTC-1574.RN-P0001-
01/27/2021
21 MNS DBAI-Teams Identified Minor Editorial Error
2/01/2021
21 DBAI Inspection - IST Program Document
Discrepancy
2/02/2021
21 MNS DBAI Inspection: 5HK Breaker Procedure
Improvement Item
2/08/2021
21 NRC DBAI-TEAM Inspection - UFSAR Ch. 3
Numbering Error
2/10/2021
21 MNS DBAI Inspection-NRC Observation MCC-
1381.05-00-0263
2/11/2021
21 NRC DBAI EDG VD fan tornado concern
2/18/2021
Drawings
MC -1579-01.00
FLOW DIAG DIESEL BLDG VENTILATION SYS VD
Rev. 16
MC -1705-01.00
One Line Diagram 125 VDC/120VAC Vital Instr &
Cont Power Sys
Rev. 123
MCCD-1702-
2.00
4160V Essential Auxiliary Power System
Rev. 13
MCCD-1702-
2.00
One Line Diagram 4160V Essential Auxiliary Power System
Rev. 13
MCFD-2575-01.01 Flow Diagram of Nuclear Service Water System (RN)
Rev. 42
MCFD-2593-01.00 Flow Diagram of Main Steam Sys (SM) Main Steam Vent to
Atmos (SV)
Rev. 20
MCFD-2593-01.03 Flow Diagram of Main Steam Sys (SM) Main Steam Vent to
Atmos (SV)
Rev. 19
MCM-1205.09-
0002.001
Nozzle Type Safety Valve
Rev. D01
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
MCM-1205.09-
0003.001
Nozzle Type Safety Valve
Rev. D-L
MCM-1205.09-
2.001
Nozzle Type Safety Valve
Rev. 0
MCM-1205.09-
0039.001
Nozzle Type Safety Valve
Rev. B
MCM-1205.09-
0039.002
Nozzle Type Safety Valve
Rev. DE
MCM-1205.09-
0041.001
Nozzle Type Safety Valve
Rev. C
Engineering
Changes
Replace U2 cold leg injection check valves on B and D
loops
Revs. 0, 1, 2
Doghouse tornado missile target TORMIS analysis docs
(LAR)
Rev. 0
Replacement of 2RN-89A
Rev. 0
1B1 KC Motor Stator Rewind
Rev. 4
Emergency diesel generator intercooler drain valve position
Rev. 0
MD101881 - 1ETA5 Relay Setting Changes - MOD
Rev. 1
Engineering
Evaluations
MCM 1320.00-
0005.001
BALDOR (RELIANCE) ELECTRIC COMPANY
QUALIFICATION OF CLASS 1 E MOTORS
09/18/2015
Miscellaneous
Maintenance Rule Program Function Scoping
DS-C-95151
Field Service Procedure: Determination of Safety Valve Set
Pressure with Crosby's SPVD/BCC System
Rev. 5
MCLL-1705-01.10
1EVDA LOAD LIST
Rev. 24
MCLL-1705-01.13
1EVDD Load List
Rev. 20
MCM 1205.09-
24.001
Vendor Manual, Installation, Operating and Maintenance
Instruction for Crosby Style HA Self-Actuated Nozzle Type
Safety Valve
06/08/1990
MCM 1301.00-
0183.005
Commercial Grade Dedication Report - EDG Excitation
System (Book 2 of 4)
Rev. 2
MCM 1312.02-
28.001
4160V Switchgear I/B
Rev. D20
MCM 1356.05-
21.001
Vital I&C Charger Instruction/Technical Manual
Rev. 11
MCM-1356.01-
0047.001
GNB Installation, Operation/Maint Vital Instrumentation
Rev. 4
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
MCS-105.18-EPL-
0001
Design Basis Specification For The 125 VDC Vital I
and C Power System (EPL)
Rev. 13
MCS-1318.00-00-
2
Motor Repair Specification
Rev. 2
MCS-1574.RN-00-
0001
Design Basis Specification for the RN System
Rev. 59
MCS-1593.SM-
00-0001
Design Basis Specification for the SM, SV and SB Systems
Rev. 33
MCTC-1593-
SM.V003-01
Valve Design Criteria/Operability Requirements and
Compensatory Measures
Rev. 5
OP-MC-STM-SM
Main Steam System (SM)
Rev. 34
Procedures
AD-EG-ALL-1451
Relief Valve Component Program
Rev. 0, 1
AP/2/A/5500/20
Loss of RN
Rev. 37
EP/1/A/5000/ECA-
0.0
Simulator Validation EP/1/A/5000/ECA-0.0
Rev. 45
IP/1/A/4971/001
Brown Boveri ITE 50 and ITE 51 Relays Test
Rev. 17
MP/0/A/7200/010
Crosby, Model HA, Main Steam Safety Valve Maintenance
Rev. 21
PT/0/A/4250/001
Main Steam Safety Valve Setpoint Test Using Crosby Airset
Device
Rev. 27
PT/0/A/4250/037
Main Steam Safety Valve Setpoint Test Using Set Pressure
Verification Device (SPVD)
Rev. 14
PT/0/A/4600/113
Operator Time Critical Task Verification (WO 20119469)
Rev. 25
PT/1/A/4350/002
B
DIESEL GENERATOR 1B OPERABILITY TEST
08/13/2019
PT/1/A/4350/002
B
DIESEL GENERATOR 1B OPERABILITY TEST
07/9/2019
PT/1/A/4350/002
B
DIESEL GENERATOR 1B OPERABILITY TEST
06/11/2019
PT/2/A/4200/009
B
Engineered Safety Features Actuation Periodic Test Train B
Rev. 18
PT/2/A/44 3/001 B
2B RN Pump Performance Test
Rev. 56
PT/2/A/4403/001
A
2A RN Pump Performance Test
Rev. 54
RE-3.02
Relaying - 600 and 480 VAC Auxiliary Systems - Equipment
Protection Settings
Rev. 5
Work Orders
01919110-42,
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
2044118-03,
20085165-03,
20104467-01,
20150584,
20154403,
20168580-01,
20168875-01,
20184067,
20184370,
20184371,
20184372,
20184373,
20184374,
20194635-03,
210551-01,
213773-01,
295493-01,
297203-01,
20309790-01,
20313538-01,
20315898,
20324018,
20343012-07,
20343012-12,
20348264,
20351796-01,
20399778,
20406452-01,
20410642-01,
20432729-01