ML24198A106
| ML24198A106 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 01/16/2025 |
| From: | John Lamb Plant Licensing Branch II |
| To: | Coleman J Southern Nuclear Operating Co |
| References | |
| EPID L-2024-LLA-0031 | |
| Download: ML24198A106 (1) | |
Text
January 16, 2025 Ms. Jamie M. Coleman Regulatory Affairs Director Southern Nuclear Operating Co., Inc.
3535 Colonnade Parkway Birmingham, AL 35243
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - ISSUANCE OF AMENDMENT NOS. 227 AND 209, REGARDING REVISION TO SURVEILLANCE REQUIREMENTS FOR TECHNICAL SPECIFICATION 3.8.1, AC SOURCES - OPERATING, TO CHANGE EMERGENCY DIESEL GENERATOR FREQUENCY AND VOLTAGE RANGES (EPID L-2024-LLA-0031)
Dear Jamie Coleman:
The U.S. Nuclear Regulatory Commission (Commission) has issued the enclosed Amendment No. 227 to Renewed Facility Operating License NPF-68 and Amendment No. 209 to Renewed Facility Operating License NPF-81 for the Vogtle Electric Generating Plant (Vogtle), Units 1 and 2, respectively. The amendments consist of changes to the Technical Specifications (TSs) in response to your application dated March 20, 2024.
The amendments would revise Surveillance Requirements (SRs) for TS 3.8.1, AC [Alternating Current] Sources - Operating, to change the Emergency Diesel Generator (EDG) frequency and voltage ranges.
A copy of the related Safety Evaluation is also enclosed. A Notice of Issuance will be included in the Commission's monthly Federal Register notice.
If you have questions, you can contact me at 301-415-3100 or John.Lamb@nrc.gov.
Sincerely,
/RA/
John G. Lamb, Senior Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425
Enclosures:
- 1. Amendment No. 227 to NPF-68
- 2. Amendment No. 209 to NPF-81
- 3. Safety Evaluation for Vogtle cc: Listserv
SOUTHERN NUCLEAR OPERATING COMPANY, INC.
GEORGIA POWER COMPANY OGLETHORPE POWER CORPORATION MUNICIPAL ELECTRIC AUTHORITY OF GEORGIA CITY OF DALTON, GEORGIA DOCKET NO. 50-424 VOGTLE ELECTRIC GENERATING PLANT, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 227 Renewed License No. NPF-68
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment to the Vogtle Electric Generating Plant, Unit 1 (the facility) Renewed Facility Operating License No. NPF-68 filed by the Southern Nuclear Operating Company, Inc. (the licensee), acting for itself, Georgia Power Company, Oglethorpe Power Corporation, Municipal Electric Authority of Georgia, and City of Dalton, Georgia (the owners), dated March 20, 2024, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations as set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations set forth in 10 CFR Chapter I; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
- 2.
Accordingly, the license is hereby amended by page changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-68 is hereby amended to read as follows:
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 227, and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. Southern Nuclear shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
- 3.
This license amendment is effective as of its date of issuance and shall be implemented within 90 days.
FOR THE NUCLEAR REGULATORY COMMISSION Michael T. Markley, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to License No. NPF-68 and the Technical Specifications Date of Issuance: January 16, 2025 MICHAEL MARKLEY Digitally signed by MICHAEL MARKLEY Date: 2025.01.16 14:20:51 -05'00'
SOUTHERN NUCLEAR OPERATING COMPANY, INC.
GEORGIA POWER COMPANY OGLETHORPE POWER CORPORATION MUNICIPAL ELECTRIC AUTHORITY OF GEORGIA CITY OF DALTON, GEORGIA DOCKET NO. 50-425 VOGTLE ELECTRIC GENERATING PLANT, UNIT 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 209 Renewed License No. NPF-81
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment to the Vogtle Electric Generating Plant, Unit 2 (the facility) Renewed Facility Operating License No. NPF-81 filed by the Southern Nuclear Operating Company, Inc. (the licensee), acting for itself, Georgia Power Company Oglethorpe Power Corporation, Municipal Electric Authority of Georgia, and City of Dalton, Georgia (the owners), dated March 20, 2024, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations as set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations set forth in 10 CFR Chapter I; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
- 2.
Accordingly, the license is hereby amended by page changes to the Technical Specifications as indicated in the attachment to this license amendment, and the first paragraph of paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-81 is hereby amended to read as follows:
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 209, and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. Southern Nuclear shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
- 3.
This license amendment is effective as of its date of issuance and shall be implemented within 90 days.
FOR THE NUCLEAR REGULATORY COMMISSION Michael T. Markley, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to License No. NPF-81 and the Technical Specifications Date of Issuance: January 16, 2025 MICHAEL MARKLEY Digitally signed by MICHAEL MARKLEY Date: 2025.01.16 14:21:30 -05'00'
ATTACHMENT VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 TO LICENSE AMENDMENT NO. 227 RENEWED FACILITY OPERATING LICENSE NO. NPF-68 DOCKET NO. 50-424 AND TO LICENSE AMENDMENT NO. 209 RENEWED FACILITY OPERATING LICENSE NO. NPF-81 DOCKET NO. 50-425 Replace the following pages of the Licenses and the Appendix A Technical Specifications (TSs) with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.
Remove Pages Insert Pages License License License No. NPF-68, page 4 License No. NPF-68, page 4 License No. NPF-81, page 3 License No. NPF-81, page 3 TSs TSs 3.8.1-7 3.8.1-7 3.8.1-9 3.8.1-9 3.8.1-11 3.8.1-11 3.8.1-12 3.8.1-12 3.8.1-14 3.8.1-14 3.8.1-15 3.8.1-15 3.8.1-16 3.8.1-16 3.8.1-17 3.8.1-17 3.8.1-18 Renewed Operating License NPF-68 Amendment No. 227 (1)
Maximum Power Level Southern Nuclear is authorized to operate the facility at reactor core power levels not in excess of 3625.6 megawatts thermal (100 percent power) in accordance with the conditions specified herein.
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 227, and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. Southern Nuclear shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
(3)
Southern Nuclear Operating Company shall be capable of establishing containment hydrogen monitoring within 90 minutes of initiating safety injection following a loss of coolant accident.
(4)
Deleted (5)
Deleted (6)
Deleted (7)
Deleted (8)
Deleted (9)
Deleted (10)
Mitigation Strategy License Condition The licensee shall develop and maintain strategies for addressing large fires and explosions and that include the following key areas:
(a)
Fire fighting response strategy with the following elements:
- 1.
Pre-defined coordinated fire response strategy and guidance
- 2.
Assessment of mutual aid fire fighting assets
- 3.
Designated staging areas for equipment and materials
- 4.
Command and control
- 5.
Training and response personnel (b)
Operations to mitigate fuel damage considering the following:
- 1.
Protection and use of personnel assets
- 2.
Communications
- 3.
Minimizing fire spread
- 4.
Procedures for Implementing integrated fire response strategy
- 5.
Identification of readily-available pre-staged equipment
- 6.
Training on integrated fire response strategy Renewed Operating License NPF-81 Amendment No. 209 (2)
Georgia Power Company, Oglethorpe Power Corporation, Municipal Electric Authority of Georgia, and City of Dalton, Georgia, pursuant to the Act and 10 CFR Part 50, to possess but not operate the facility at the designated location in Burke County, Georgia, in accordance with the procedures and limitations set forth in this license; (3)
Southern Nuclear, pursuant to the Act and 10 CFR Part 70, to receive, possess, and use at any time special nuclear material as reactor fuel, in accordance with the limitations for storage and amounts required for reactor operation, as described in the Final Safety Analysis Report, as supplemented and amended; (4)
Southern Nuclear, pursuant to the Act and 10 CFR Parts 30, 40, and 70 to receive, possess, and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (5)
Southern Nuclear, pursuant to the Act and 10 CFR Parts 30, 40, and 70, to receive, possess, and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; (6)
Southern Nuclear, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as my be produced by the operation of the facility authorized herein.
C.
This license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter 1 and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect, and is subject to the additional conditions specified or incorporated below.
(1) Maximum Power Level Southern Nuclear is authorized to operate the facility at reactor core power levels not in excess of 3625.6 megawatts thermal (100 percent power) in accordance with the conditions specified herein.
(2) Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 209 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. Southern Nuclear shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
The Surveillance requirements (SRs) contained in the Appendix A Technical Specifications and listed below are not required to be performed immediately upon implementation of Amendment No. 74. The SRs listed below shall be
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-7 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME I.
Required Action and associated Completion Time of Condition H not met.
I.1 Be in MODE 3.
AND I.2 Be in MODE 5.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 36 hours SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.1.1 Verify correct breaker alignment and indicated power availability for each required offsite circuit.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.2
NOTES--------------------------
- 1.
Performance of SR 3.8.1.7 satisfies this SR.
- 2.
All DG starts may be preceded by an engine prelube period and followed by a warmup period prior to loading.
- 3.
A modified DG start involving idling and gradual acceleration to synchronous speed may be used for this SR as recommended by the manufacturer. When modified start procedures are not used, the time, voltage, and frequency tolerances of SR 3.8.1.7 must be met.
Verify each DG starts from standby conditions and achieves steady state voltage 4040 V and 4330 V, and frequency 59.6 Hz and 60.4 Hz.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-9 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.7
NOTE----------------------------
All DG starts may be preceded by an engine prelube period.
Verify each DG starts from standby condition and achieves:
- a.
In 11.4 seconds, voltage 4025 V and frequency 58.8 Hz, and
- b.
Steady state voltage 4040 V and 4330 V, and frequency 59.6 Hz and 60.4 Hz.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.8
NOTE-----------------------------
Credit may be taken for unplanned events that satisfy this SR.
Verify each DG rejects a load its associated single largest post accident load, and:
- a.
Following load rejection, the frequency is 64.5 Hz;
- b.
Within 3 seconds following load rejection, the voltage is 3750 V and 4330 V or 4550 V when performing the test synchronized with offsite power; and
- c.
Within 3 seconds following load rejection, the frequency is 58.8 Hz and 61.2 Hz.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-11 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.10
NOTES--------------------------
- 1.
All DG starts may be preceded by an engine prelube period.
- 2.
This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the plant is maintained or enhanced. Credit may be taken for unplanned events that satisfy this SR.
Verify on an actual or simulated loss of offsite power signal:
- a.
De-energization of emergency buses;
- b.
Load shedding from emergency buses;
- c.
DG auto-starts from standby condition and:
- 1.
energizes permanently connected loads in 11.5 seconds,
- 2.
energizes auto-connected shutdown loads through automatic load sequencer,
- 3.
maintains steady state voltage 4040 V and 4330 V,
- 4.
maintains steady state frequency 59.6 Hz and 60.4 Hz, and
- 5.
supplies permanently connected and auto-connected shutdown loads for 5 minutes.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-12 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.11
NOTES--------------------------
- 1.
All DG starts may be preceded by an engine prelube period.
- 2.
This Surveillance shall not normally be performed in MODE 1 or 2. However, portions of the Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the plant is maintained or enhanced. Credit may be taken for unplanned events that satisfy this SR.
Verify on an actual or simulated Engineered Safety Feature (ESF) actuation signal each DG auto-starts from standby condition and:
- a.
In 11.4 seconds after auto-start and during tests, achieves voltage 3750 V and frequency 58.8 Hz;
- b.
Achieves steady state voltage 4040 V and 4330 V and frequency 59.6 Hz and 60.4 Hz;
- c.
Operates for 5 minutes;
- d.
Permanently connected loads remain energized from the offsite power system; and
- e.
Emergency loads are energized or auto-connected through the automatic load sequencer from the offsite power system.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-14 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.14
NOTES--------------------------
- 1.
This Surveillance shall be performed within 5 minutes of shutting down the DG after the DG has operated 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> loaded 6500 kW and 7000 kW.
Momentary transients outside of load range do not invalidate this test.
- 2.
All DG starts may be preceded by an engine prelube period.
Verify each DG starts and achieves:
- a.
In 11.4 seconds, voltage 4025 V and frequency 58.8 Hz, and
- b.
Steady State voltage 4040 V, and 4330 V and frequency 59.6 Hz and 60.4 Hz.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-15 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.15
NOTE-----------------------------
This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the plant is maintained or enhanced. Credit may be taken for unplanned events that satisfy this SR.
Verify each DG:
- a.
Synchronizes with offsite power source while loaded with emergency loads upon a simulated restoration of offsite power;
- b.
Transfers loads to offsite power source; and
- c.
Returns to ready-to-load operation.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.16
NOTE-----------------------------
This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, portions of this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the plant is maintained or enhanced. Credit may be taken for unplanned events that satisfy this SR.
Verify, with a DG operating in test mode and connected to its bus, an actual or simulated ESF actuation signal overrides the test mode by:
- a.
Returning DG to ready-to-load operation; and
- b.
Automatically energizing the emergency load from offsite power.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-16 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.17
NOTE-----------------------------
This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the plant is maintained or enhanced. Credit may be taken for unplanned events that satisfy this SR.
Verify interval between each sequenced load block is within 10% of design interval for each load sequencer.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-17 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.18
NOTES---------------------------
- 1.
All DG starts may be preceded by an engine prelube period.
- 2.
This Surveillance shall not normally be performed in MODE 1, 2, 3, or 4. However, portions of this Surveillance may be performed to reestablish OPERABILITY provided an assessment determines the safety of the plant is maintained or enhanced. Credit may be taken for unplanned events that satisfy this SR.
Verify on an actual or simulated loss of offsite power signal in conjunction with an actual or simulated ESF actuation signal:
- a.
De-energization of emergency buses;
- b.
Load shedding from emergency buses; and
- c.
DG auto-starts from standby condition and:
- 1.
energizes permanently connected loads in 11.5 seconds,
- 2.
energizes auto-connected emergency loads through load sequencer,
- 3.
achieves steady state voltage:
4040 V and 4330 V,
- 4.
achieves steady state frequency:
59.6 Hz and 60.4 Hz, and
- 5.
supplies permanently connected and auto-connected emergency loads for 5 minutes.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources - Operating 3.8.1 Vogtle Units 1 and 2 3.8.1-18 Amendment No. 227 (Unit 1)
Amendment No. 209 (Unit 2)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.19 Verify fuel transfer pump transfers fuel from each fuel storage tank to the day tank of each diesel via the installed cross-connection lines.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.20
NOTE--------------------------
All DG starts may be preceded by an engine prelube period.
Verify when started simultaneously from standby condition, each DG achieves:
- a.
In 11.4 seconds, voltage 4025 V and frequency 58.8 Hz, and
- b.
Steady state voltage 4040 V and 4330 V, and frequency 59.6 Hz and 60.4 Hz.
In accordance with the Surveillance Frequency Control Program
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 AMENDMENT NO. 227 TO RENEWED FACILITY OPERATING LICENSE NPF-68 AMENDMENT NO. 209 TO RENEWED FACILITY OPERATING LICENSE NPF-81 SOUTHERN NUCLEAR OPERATING COMPANY, INC.
DOCKET NOS. 50-424, AND 50-425
1.0 INTRODUCTION
By letter dated March 20, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24080A455), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) to the U.S. Nuclear Regulatory Commission (NRC, the Commission) for changes to the technical specifications (TSs) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2.
The proposed amendments would revise Surveillance Requirements (SRs) for TS 3.8.1, AC
[Alternating Current] Sources - Operating, to change the Emergency Diesel Generator (EDG) frequency and voltage ranges.
2.0 REGULATORY EVALUATION
2.1 Description of the Onsite Emergency AC Power System In Section 2.1 of the Enclosure to its submittal dated March 20, 2024, the licensee stated:
The onsite standby power source for each 4.16 kV [kilovolt] ESF [Engineered Safety Feature] bus is a dedicated DG [Diesel Generator]. DGs A and B are dedicated to ESF buses A and B, respectively. A DG starts automatically on a safety injection (SI) signal or on an ESF bus degraded voltage or undervoltage signal. After the DG has started, it will automatically tie to its respective bus after offsite power is tripped as a consequence of ESF bus undervoltage or degraded voltage, independent of or coincident with an SI signal. The DGs will also start and operate in the standby mode without tying to the ESF bus on an SI signal alone. Following the trip of offsite power, in response to the undervoltage signal, a sequencer strips nonpermanent loads from the ESF bus. When the DG is tied to the ESF bus, loads are then sequentially connected to its respective ESF bus by the automatic load sequencer. The sequencing logic controls the permissive and starting signals to motor breakers to prevent overloading the DG by automatic load application.
Each diesel generator is rated at 7000 kW for continuous operation and 7700 kW for a short-term (2-hour) period every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The voltage and frequency recovery characteristics meet or exceed the requirements of Regulatory Guide 1.9 [Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1E Onsite Electric Power Systems at Nuclear Power Plants, Revision 3, July 1993 (ML003739929)].
2.2 Reason for the Proposed Change In Section 2.3 of the Enclosure to its submittal dated March 20, 2024, the licensee stated, in part, that:
Additionally, this change is necessary based on the discovery that some safety related pumps could not be demonstrated to perform as specified in the design basis over the full range of DG voltages and frequencies allowed by the Technical Specifications without more detailed analysis. Subsequent SNC evaluations utilizing the methodologies approved in WCAP-17308 determined that more conservative operating ranges for DG voltage and frequency TS Surveillance Requirements are appropriate to assure design basis assumptions for equipment performance.
This LAR is required to resolve a non-conservative TS and is not a voluntary request. As such, it is not subject to 'forward fit' considerations. Therefore, this request is not subject to 'forward fit' considerations as described in the letter from S. Burns (NRC) to E. Ginsberg (NEI), dated July 14, 2010 (ML101960180).
2.3 Proposed TS Changes
The LAR would revise SRs 3.8.1.2, 3.8.1.7, 3.8.1.10, 3.8.1.11, 3.8.1.14, 3.8.1.18, and 3.8.1.20 to change the EDG steady state frequency and voltage ranges.
Changes to TS SRs are indicated in BOLD font below.
2.3.1 SR 3.8.1.2 Current SR 3.8.1.2 states:
Verify each DG starts from standby conditions and achieves steady state voltage > 4025 V and < 4330 V, and frequency > 58.8 Hz and < 61.2 Hz.
Revised SR 3.8.1.2 would state:
Verify each DG starts from standby conditions and achieves steady state voltage > 4040 V and < 4330 V, and frequency > 59.6 Hz and < 60.4 Hz.
2.3.2 SR 3.8.1.7 Current SR 3.8.1.7 states:
Verify each DG starts from standby condition and achieves in < 11.4 seconds, voltage > 4025 V and < 4330 V, and frequency > 58.8 Hz and < 61.2 Hz.
Revised SR 3.8.1.7 would state:
Verify each DG starts from standby condition and achieves:
- a. In < 11.4 seconds, voltage > 4025 V and frequency > 58.8 Hz, and
- b. Steady state voltage > 4040 V and < 4330 V, and frequency > 59.6 Hz and
< 60.4 Hz.
2.3.3 SR 3.8.1.10 Current SR 3.8.1.10.c. states:
- c. DG auto-starts from standby condition and:
- 3. maintains steady state voltage > 3750 V and < 4330 V,
- 4. maintains steady state frequency > 58.8 Hz and < 61.2 Hz, and Revised SR 3.8.1.10.c. would state:
- c. DG auto-starts from standby condition and:
- 3. maintains steady state voltage 4040 V and 4330 V,
- 4. maintains steady state frequency 59.6 Hz and 60.4 Hz, and 2.3.4 SR 3.8.1.11 Current SR 3.8.1.11.a. and 3.8.1.11.b, state:
- a. In 11.4 seconds after auto-start and during tests, achieves voltage 3750 V and 4330 V;
- b. In 11.4 seconds after auto-start and during tests, achieves frequency 58.8 Hz and 61.2 Hz;
Revised SR 3.8.1.11.a. and 3.8.1.11.b. would state:
- a.
In 11.4 seconds after auto-start and during tests, achieves voltage 3750 V and frequency 58.8 Hz;
- b.
Achieves steady state voltage 4040 V and 4330 V and frequency 59.6 Hz and 60.4 Hz; 2.3.5 SR 3.8.1.14 Current SR 3.8.1.14 states:
Verify each DG starts and achieves, in 11.4 seconds, voltage 4025 V, and 4330 V and frequency 58.8 Hz and 61.2 Hz.
Revised SR 3.8.1.14 would state:
Verify each DG starts and achieves:
- a.
In 11.4 seconds, voltage 4025 V and frequency 58.8 Hz, and
- b.
Steady State voltage 4040 V, and 4330 V and frequency 59.6 Hz and 60.4 Hz.
2.3.6 SR 3.8.1.18 Current SR 3.8.1.18.c.3 and 3.8.1.18.c.4 states:
- 3.
achieves steady state voltage: 3750 V and 4330 V,
- 4.
achieves steady state frequency: 58.8 Hz and 61.2 Hz, and Revised SR 3.8.1.18.c.3 and 3.8.1.18.c.4 would state:
- 3.
achieves steady state voltage: 4040 V and 4330 V,
- 4.
achieves steady state frequency: 59.6 Hz and 60.4 Hz, and 2.3.7 SR 3.8.1.20 Current SR 3.8.1.20 states:
Verify when started simultaneously from standby condition, each DG achieves, in 11.4 seconds, voltage 4025 V and 4330 V, and frequency 58.8 Hz and 61.2 Hz.
Revised SR 3.8.1.20 would state:
Verify when started simultaneously from standby condition, each DG achieves:
- a.
In 11.4 seconds, voltage 4025 V and frequency 58.8 Hz, and
- b.
Steady state voltage 4040 V and 4330 V, and frequency 59.6 Hz and 60.4 Hz 2.4 Regulatory Requirements and Guidance The NRC staff applied the following NRC regulations in its review of this LAR:
Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36, Technical specifications, requires, in part, that the operating license of a nuclear power facility include TSs (10 CFR 50.36(b)). The regulation at 10 CFR 50.36(c)(3) requires that the TSs include SRs, which are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.
10 CFR Part 50, Appendix A, General Design Criterion (GDC) 17, Electric power systems, states, in part, that:
An onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety. The safety function for each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.
The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.
GDC 18, Inspection and testing of electric power systems, states that:
Electric power systems important to safety shall be designed to permit appropriate periodic inspection and testing of important areas and features, such as wiring, insulation, connections, and switchboards, to assess the continuity of the systems and the condition of their components. The systems shall be designed with a capability to test periodically (1) the operability and functional performance of the components of the systems, such as onsite power sources, relays, switches, and buses, and (2) the operability of the systems as a whole and, under conditions as close to design as practical, the full operation sequence that brings the systems into operation, including operation of applicable portions of the protection system, and the transfer of power among the nuclear power unit, the offsite power system, and the onsite power system.
According to the Vogtle, Units 1 and 2, Updated Final Safety Analysis Report (UFSAR) 1.2.12 (ML22326A062), Vogtle, Units 1 and 2, are designed to comply with the intent of the General Design Criteria for Nuclear Power Plants contained in Appendix A to 10 CFR Part 50.
The NRC staff also considered the following NRC-approved guidance documents in its review:
Regulatory Guide (RG) 1.9, Revision 3, July 1993, (ML003739929) Selection, Design, and Qualification of Diesel Generator Units Used as Class 1E Onsite Electric Power Systems at Nuclear Power Plants (ML12305A253).
Pressurized Water Reactor Owners Group (PWROG) prepared Topical Report (TR)
WCAP-17308-NP-A, Revision 0, Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances (ML17215A232).
Technical Specification Task Force (TSTF) traveler TSTF-163, Revision 2, Minimum vs.
Steady State Voltage and Frequency (ML040500733).
3.0 TECHNICAL EVALUATION
In Section 3 of the Enclosure to its submittal dated March 20, 2024, the licensee stated, in part, that:
The TSTF-163 related changes to VEGP [Vogtle Electric Generating Plant] Units 1 and 2 TS SRs 3.8.1.7, 3.8.1.11, 3.8.1.14, and 3.8.1.20 to only require achieving a minimum voltage and frequency within 11.4 seconds. This confirms the ability of the DG to reach the conditions necessary to accept load. The minimum values for voltage and frequency are unchanged and remain acceptable since these SRs do not require the DG to be loaded at 11.4 seconds. The proposed change does not involve any departures (other than VEGP-specific values) from TSTF-163.
The NRC staff notes that the proposed changes to Vogtle, Units 1 and 2, TS SRs 3.8.1.7, 3.8.1.11, 3.8.1.14, and 3.8.1.20 to require achieving a minimum voltage and frequency within 11.4 seconds are consistent with the NRC-approved TSTF-163, Revision 2, and are, therefore, acceptable.
In Section 3 of the Enclosure to its submittal dated March 20, 2024, the licensee also stated, in part, that:
The performance of the required equipment is dependent on the DG voltage and frequency. The current analyses generally assume that the steady-state DG voltage is 4160 V and the steady-state DG frequency is 60 Hz. However, equipment powered from the DGs are allowed voltage and frequency variations up to the limits specified in the TS SRs. The current VEGP Units 1 and 2 TS 3.8.1 allows steady state voltage range of 4025 V to 4330 V and steady state frequency range of 58.8 Hz to 61.2 Hz. These allowed steady-state ranges represent tolerances for voltage of +4/-3.2% around a nominal 4160 V and for frequency of +/-2% around a nominal 60 Hz. The proposed revised DG voltage and frequency ranges have been analyzed assuming steady state voltage range of 4040 V to 4330 V and frequency range of 60 Hz +/-0.4 Hz for frequency.
The NRC staff notes that steady state EDG operation at the extremes of the frequency and voltage limits can have an impact on the performance of ESF equipment, including:
Performance of safety related systems which include Emergency Core Cooling Systems (ECCS)
DG loading calculations DG fuel oil consumption calculations Motor-operated valve (MOV) performance In its LAR, SNC provided justifications for the proposed changes to the steady state frequency and voltage limits of the EDGs in the various SRs, which are also listed in Section 2.3 of this Safety Evaluation. The NRC staffs evaluation of the licensees proposed changes to the TS SRs is discussed next.
3.1 WCAP-17308-NP-A Methodology The NRC staff independently evaluated the impact of change in EDG voltage and frequency bands, using the information provided in the LAR and through a regulatory audit, to examine non-docketed calculations and analyses to verify information to support the basis of the licensing or regulatory decision.
In Section 3 of the Enclosure to its LAR, the licensee stated that it evaluated the proposed TS SR changes consistent with TR WCAP-17308-NP-A. The TR is approved for determining the impact of DG steady state frequency and voltage variations on essential motor loads such as ECCS pumps, MOVs, and fans/blowers.
In its submittal, the licensee stated, in part, that SNC analyzed the allowable steady state variations in voltage and frequency proposed in the TS SRs following the methods provided by WCAP-17308-NP-A, utilizing Vogtle-specific inputs to demonstrate the capability of equipment to meet intended safety performance. The evaluation calculates the surveillance uncertainty which is a combination of the operational uncertainty (i.e., manufacturer voltage regulator and speed governor design control uncertainties) and the indication uncertainties (i.e.,
metering/indication circuit uncertainties).
SNC further stated that the calculated surveillance uncertainty provides a tighter band around nominal than the 10% and 2% previously specified in the TS. The selected TS ranges are slightly larger than the surveillance uncertainties to allow some design margin for the future. The proposed tighter bands (which bound those uncertainties) are then evaluated against the design basis accident analyses to show that, within those tolerances, the proposed DG steady state voltages and frequencies are sufficient to support the required plant equipment operation.
The NRC staff identified the need for a regulatory audit to examine the SNCs non-docketed information with the intent to gain understanding, verify information, or identify information that would be required to support the licensees requested regulatory decision. The NRC staff performed an audit in accordance with the Audit Plan, dated June 5, 2024 (ML24155A177), as supplemented by letters dated July 1 (ML24176A163) and September 9, 2024 (ML24250A204).
The Audit Summary was issued on December 10, 2024 (ML24337A122). The NRC staffs audit of the licensees operational uncertainty calculation for EDGs at Vogtle, Units 1 and 2, found that the methodology used in the calculation is consistent with WCAP-17308-NP-A, including
the method of calculating the operational voltage uncertainty and operational frequency uncertainty.
The NRC staff concludes that the proposed changes will not have an impact on SNCs application of the WCAP-17308-NP-A methodology for EDG evaluations. Because the new proposed EDG voltage and frequency limits lead to a tighter tolerance band and are consistent with those addressed by the TR WCAP-17308-NP-A, the NRC concludes it is, therefore, acceptable.
3.2 Impact on EDG Capacity In Section 3 of the Enclosure to the LAR, the licensee stated, in part, that the current Vogtle, Units 1 and 2, TS 3.8.1 allows steady state voltage range of 4025 V to 4330 V and steady state frequency range of 58.8 Hz to 61.2 Hz. These ranges represent tolerances for voltage of +4/-
3.2% around a nominal 4160 V and for frequency of +/-2% around a nominal 60 Hz. The proposed steady state EDG voltage range (4040 to 4330 V) and frequency range (59.6 to 60.4 Hz) are conservative with respect to the current TS SR ranges for EDG voltage and frequency.
Since the EDGs were designed to operate within these current tolerances, limiting the tolerances to a tighter band is considered acceptable for EDG operation.
The NRC staffs independent review finds that the proposed EDGs steady state operating voltage and frequency ranges are conservative and within the EDG rating. The proposed change would not adversely impact the EDGs capability of providing its intended safety function. Therefore, the Vogtle, Units 1 and 2, would continue to meet the intent of GDC 17 with respect to equipment capability. Based on the above, the NRC staff concludes that the proposed voltage and frequency ranges are acceptable with respect to their impact on EDG operation.
3.3 Impact on EDG Loadings In Section 3 of the Enclosure to the LAR, the licensee stated, in part, that the maximum impact on EDG loading is observed when both the voltage and frequency are at the upper TS limits of 4330 V and 60.4 Hz, where the steady state loading on the EDG does not exceed the continuous rating of the EDG. Each units onsite standby power source consists of Train A and Train B DGs. SNC selected EDG 1A (Unit 1 Train A) for its study of impact on EDG loading since it has the heaviest steady state load at the end of automatic sequencing. In the study, the EDG load increases by 3.2 % when both the voltage and frequency to be at their upper limits of 4330 V and 60.4 Hz. The steady state loading shows that Vogtle, Units 1 and 2, EDGs continuous rating of 7000 kW and 8750 kVA is not exceeded due to the voltage and frequency variations.
The NRC staffs independent review finds that the proposed TS changes to voltage and frequency range are acceptable with respect to their impact on EDG loadings. The NRC staff finds that the proposed change does not adversely impact the EDG loading capability. Based on the above, the NRC concludes that Vogtle, Units 1 and 2, would continue to meet the intent of GDC 17 with respect to equipment capability.
3.4 EDG Steady State Allowable Voltage Variation Evaluation In Section 3 of the Enclosure to the LAR, the licensee stated, in part, that SNC analyzed the allowable steady state variations in voltage and frequency proposed in the TS SRs following the
methods provided by WCAP-17308-NP-A utilizing plant-specific inputs to demonstrate the capability of equipment to meet intended safety performance.
The LAR further states that SNCs current analyses generally assume that the steady state EDG voltage is 4160 V and the steady state DG frequency is 60 Hz. However, equipment powered from the EDGs are allowed voltage and frequency variations up to the limits specified in the TS SRs. The current Vogtle, Units 1 and 2, TS 3.8.1 allows steady state voltage range of 4025 V to 4330 V and steady state frequency range of 58.8 Hz to 61.2 Hz. These allowed steady-state ranges represent tolerances for voltage of +4/-3.2% around a nominal 4160 V and for frequency of +/-2% around a nominal 60 Hz. The proposed revised EDG voltage and frequency ranges have been analyzed assuming steady state voltage range of 4040 V to 4330 V and frequency range of 60 Hz +/-0.4 Hz for frequency.
SNC further stated that the EDG frequency range was reduced to minimize the impact of frequency variation on the operation of connected loads. The EDG voltage regulator is capable of maintaining steady state voltage within the proposed tolerance and the EDG governor is capable of maintaining EDG speed within the narrower tolerance as demonstrated by design analyses and supported by manufacturer design tolerances. The licensee also stated that the surveillance test data review over the past three years provides assurance that the revised voltage and frequency limits will be achievable.
The NRC staffs independent review of the licensees submittal and information gathered in the regulatory audit confirmed that limiting the tolerances to a tighter band is considered acceptable for EDG operation, and the proposed change does not adversely impact the equipment powered by the EDG. Based on the above, the NRC concludes that the licensee continues to meet the intent of GDC 17 with respect to equipment capability and GDC 18 with respect to testing and the proposed TS changes are, therefore, acceptable.
3.5 Impact on EDG Fuel Oil Consumption In Section 3 of the Enclosure to the LAR states, the licensee states, in part, that the increase in EDG loading due to EDG voltage and frequency variation is used as input into the existing diesel fuel oil consumption and storage tank capacity calculation to verify that the increase in fuel oil consumption remains bounded.
SNC further stated that, due to substantial margin available above the 68,000 gallons required in each EDG fuel storage tank by TS 3.8.3, Diesel Fuel Oil, Lube Oil, Starting Air, and Ventilation, SR 3.8.3.1 for a 7-day fuel oil supply for one EDG, this TS value is not affected by the small increased EDG loading. Similarly, the greater than 52,000 gallons fuel oil supply required for entering TS 3.8.3 Action A continues to support the current licensing basis. The licensee states that the SR 3.8.1.4 requirement that each EDG day tank contains 650 gal of fuel oil also continues to support the necessary volume to meet the current licensing basis requirement to ensure adequate fuel oil for a minimum of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of EDG operation at full load plus 10%.
The NRC staffs independent review finds that the proposed change does not adversely impact the EDG fuel oil consumption. Based on the above, the NRC staff concludes that the licensee would continue to meet the intent of GDC 17 with respect to equipment capability and that the proposed TS changes are, therefore, acceptable.
3.6 Impact on EDG Pumps In Section 3 of the Enclosure to the LAR, SNC stated that the fuel oil transfer pumps are used to provide makeup to the day tanks. The licensee stated that the day tanks were designed to provide 25 gallons per minute (gpm) compared to a maximum EDG consumption rate of 8.51 gpm; therefore, the day tanks have significant margin for degradation and EDG uncertainty.
Based on the licensees submittal and information reviewed during the regulatory audit, the NRC staff finds that the proposed change does not adversely impact the operation of the EDG pump. Based on the above, the NRC concludes the licensee would continue to meet the intent of GDC 17 with respect to equipment capability and that the proposed TS changes are, therefore, acceptable.
3.7 ECCS and Containment Spray Pump Evaluation SNC stated that it used the methods described in TR WCAP-17308-NP-A to address the EDG voltage and frequency variances. Per TR WCAP-17308-NP-A Section 2.1, the total pump head uncertainty is calculated at discrete flow rates as a function of the combined uncertainties for frequency, voltage, and various other measurements including flow and pressure. Therefore, flow variability due to measurement uncertainties and the effects of frequency and voltage on pump speed are statistically factored into the pump head uncertainty. For the simultaneous underfrequency and undervoltage event, the decrease in pump flow rates is evaluated to ensure ECCS acceptance criteria remain acceptable. For the simultaneous overfrequency and overvoltage event, the increase in pump flow rates is evaluated to ensure net positive suction head requirements are met and MOV operation is acceptable.
The licensee evaluated the performance of the ECCS and containment spray pumps to generate revised minimum and maximum test curves that account for the effects of steady state EDG voltage and frequency variations, as well as evaluating flow and pressure measurement uncertainties. The licensee stated that adjustments are applied to the existing pump curves of record using the plant-specific EDG and instrument uncertainties. The licensee also stated that, upon approval of its LAR, adjustments to the Inservice Testing (IST) surveillance test acceptance criteria will be made to ensure that design basis safety analysis limits of equipment loaded on the EDG will be met at the extremes of steady state EDG voltage and frequency variations and due to flow and pressure measurement uncertainties.
During the regulatory audit, the NRC staff independently reviewed calculations performed to assess the impact of the variation in EDG powered motor speed on the ECCS pumps and other safety related pump when the EDG is operating at highest or lowest allowable frequency and voltage limits, along with the motor speed uncertainty.
Based on the licensees submittal and information reviewed during the regulatory audit, the NRC staff finds that the proposed changes in EDG frequency and voltage will continue to meet the intended safety performance for the ECCS and containment spray pumps and are, therefore, acceptable.
3.8 Evaluation of Miscellaneous Pumps Power by EDGs SNC performed evaluation of various miscellaneous pumps powered by the EDGs for the effects of the over and under frequency and voltage allowed by the proposed TS utilizing plant specific inputs in accordance with the methodology prescribed in WCAP-17308-NP-A. During
the regulatory audit, the NRC staff reviewed the impact of the variation in EDG powered motor speed on the following pumps:
Component Cooling Water (CCW) Pumps Nuclear Safety Cooling Water (NSCW) Pumps Essential Chilled Water (ECW) Pumps NSCW Transfer Pumps Boric Acid Transfer (BAT) Pumps Spent Fuel Pit Pumps Diesel Fuel Oil Transfer Pumps Based on the licensees submittal and information reviewed during the regulatory audit, the NRC staff finds that the evaluation performed is in accordance with the methodology prescribed in WCAP-17308-NP-A and that the pumps analyzed show the design basis requirements can be met for the system at the revised voltage and frequency ranges with a significant margin for degradation and EDG uncertainty and is, therefore, acceptable.
3.9 Impact on MOV Performance Section 3 of the Enclosure to the LAR states, in part, that four effects on MOV motor speeds uncertainties were evaluated when the EDG is operating at highest or lowest allowable voltage and frequency limits: (1) the increased inertia of the motor due to increased EDG frequency; (2) the potential effect of higher pump motor frequency on the differential pressure across the MOVs; (3) the impact of decreased voltage below nominal on the motor operator capability; and (4) the potential for increased stroke time.
SNC further stated that, in addition to the normal limits, the potential for the opening force to be limited by the effects of pressure locking and thermal binding (PL/TB) were evaluated to include the effects of EDG voltage and frequency on those limits. SNCs evaluation concluded that the existing PL/TB evaluation does not require any additional limits be place on the opening (pullout) force from the valve. Analyses results show that MOV performance is not adversely affected by the proposed EDG voltage and frequency ranges.
Based on the licensees submittal and information reviewed during the regulatory audit, the NRC staff finds that the proposed TS changes would not adversely impact the MOV performance and are, therefore, acceptable.
3.10 Impact on Other Equipment Section 3 of the Enclosure to the LAR states that SNCs analysis demonstrates that the components connected to the EDGs have sufficient margin to allow for the voltage and frequency variations proposed in the TS. The licensee discussed its evaluation of the impact of the proposed voltage and frequency tolerances on other equipment loads as follows:
Battery chargers, inverters and similar type loads power demand are based on downstream conditions and are not impacted by upstream voltage and frequency variations. The battery chargers are maintained within their rated range even at a conservative +/-10% voltage range to account for voltage loss in the circuit, therefore SNC states that there will be no impact on the battery chargers ability to function as designed.
HVAC heaters: SNCs calculations determined that the HVAC heaters are capable of performing their required design function at the derated voltages that bound the proposed minimum steady state EDG voltage.
Pressurizer heaters: Since the heaters are controlled to reduce power and then turn off when the pressurizer is hot enough, overvoltage is not a concern and requires no additional analysis. At the lower steady state EDG voltage limit, the actual wattage for each group is well above the TS 3.4.9, Pressurizer, requirement of 150 kW. Therefore, the licensee concluded that the DG voltage variance would not have an adverse effect on the pressurizer heater requirements, and that EDG frequency variances do not impact heater performance.
Miscellaneous 120 V AC Loads: The adequacy of safety-related devices energized from the 120 V distribution panels to perform their intended safety related function at degraded voltage is calculated by the licensee based on voltages lower than the EDG minimum steady state voltage. The maximum steady state EDG output voltage is bounded by the maximum 120 V buses rating. The licensee states that the effect of EDG frequency variances is negligible on the 120 V loads as the loads do not include major rotating equipment (i.e., Motor Operated Valves (MOVs), large pumps, or large fans) that are subject to adverse performance based on frequency variances.
Miscellaneous DC Loads: The battery chargers allowable input voltage and frequency range is much greater than the allowable EDG output range. The battery chargers are maintained within their rated range; therefore, the licensee states that there will be no impact on the battery chargers ability to function as designed. Consistent output voltage will be provided to supported DC loads. Furthermore, the licensee states that there are no adverse impacts on the DC loads due to EDG voltage or frequency variances.
Relief Valve and Pressure Switches: SNCs evaluation assessed the effect of increased EDG frequency and voltage on pumps potentially receiving power from the EDGs to assure that pressure relief valve or pressure switch actuation would not impact the ability of the plant to safely shutdown. The licensees evaluation indicated that EDG frequency and voltage uncertainty impacts on pump performance would not result in inadvertent pressure switch actuations that could impact the ability of the plant to safely shut down. There may be alarm actuations in certain alignments on low pressure in Auxiliary Feedwater, but flow delivery would still be met.
Based on the above, SNC stated that the proposed changes to the TS SR voltage and frequency tolerances would not impact the performance of safety-related equipment.
Based on the licensees submittal and information reviewed during the regulatory audit, the NRC staff finds that the proposed change does not adversely impact the equipment powered by the EDG. Based on the above, the NRC concludes that the licensee, would continue to meet the intent of GDC 17 with respect to equipment capability and that the proposed TS changes are, therefore, acceptable.
3.11 NRC Staff Review of Calculations In its LAR, SNC evaluated the performance of pumps, valves, and other equipment that are powered from the EDGs for the effects of the over and under frequency and voltage allowed by the proposed TS change at Vogtle, Units 1 and 2. The licensees evaluation addressed the performance of ECCS pumps, containment spray pumps, component cooling water pumps,
nuclear safety cooling water pumps, essential chilled water pumps, nuclear safety cooling water transfer pumps, boric acid transfer pumps, spent fuel pit pumps, diesel fuel oil transfer pumps, MOVs, and ventilation fans. SNC stated that the analysis demonstrated that the components connected to the EDGs have sufficient margin to allow for the voltage and frequency variations for the proposed TS change.
The LAR states that the evaluation of the EDG voltage and frequency variations followed the methods in WCAP-17308-NP-A (Revision 0, July 2017), Treatment of Diesel Generator (DG)
Technical Specification Frequency and Voltage Tolerances (ML17215A232). In an NRC safety evaluation dated April 17, 2017 (incorporated into WCAP-17308-NP-A), the NRC staff found that WCAP-17308-NP, Revision 0, is acceptable for referencing in licensing applications for nuclear power plants to the extent specified and under the limitations delineated in WCAP-17308-NP and in the final NRC safety evaluation. In response to NRC staff questions during the regulatory audit, SNC confirmed that there were no deviations from the methods or implementation specified in WCAP-17308-NP-A.
As described in Section 3.1 of this Safety Evaluation, the NRC staff conducted a regulatory audit to review the proprietary calculations performed by SNC and Westinghouse to evaluate the impact of the proposed changes for the TS voltage and frequency tolerances on safety-related equipment powered by the EDGs at Vogtle, Units 1 and 2. As described in the Audit Summary dated December 10, 2024, the licensees calculations and other documents reviewed by the NRC staff in evaluating the current LAR are summarized below:
SNC Calculation X3CE11, Evaluation of the Effects of Emergency Diesel Generator Voltage and Frequency Variations, Version 3.0, dated September 28, 2023, and its appendices provide details of the calculations for the impact of the EDG voltage and frequency variations on pumps, MOVs, fans, chillers, air conditioning units, coolers, static loads, EDG loading, instrument uncertainty for pumps, heat loads, and relief valve and pressure switches. The calculations found that the evaluated components could perform their safety functions with the EDG voltage and frequency variations, but recommended adjustments to specific documentation.
Westinghouse Letter LTR-SEE-19-101, A.W. Vogtle Units 1 & 2 Pump Evaluations for Emergency Diesel Generator Frequency and Voltage, Revision 0, dated June 14, 2021, describes the evaluation of the performance of the applicable pumps at Vogtle, Units 1 and 2, and the revised minimum and maximum test curves for steady-state EDG frequency and voltage variations and flow and pressure measurement uncertainties. The pumps within the scope of the calculation included the high head centrifugal charging pumps, intermediate head safety injection pumps, residual heat removal pumps, and containment spray pumps. SNC used the calculation results to adjust the IST surveillance test acceptance criteria to ensure that the design-basis safety analysis limits of equipment loaded on the EDGs will be met for the frequency and voltage variations and uncertainties.
SNC VNP-1HV5118, Thrust and Torque Calculation 1HV5118 (VNPS-1), AC Motor Operated GL 96-05 Butterfly Valve, Revision 4, describes the revision of the MIDAS calculation as recommended by SNC Calculation X3CE11 to resolve a structural limit finding for MOV 1HV5118.
SNC Technical Evaluations Quality Record TE1141907 (entry 11-29-2023), Update required for Calculation X4C1208V01, describes plans to update Calculation X4C1208V01 to account for nitrogen overpressure and maximum Volume Control Tank (VCT) level for the VCT flow paths.
SNC Calculation X4C1208V01, Chemical and Volume Control System Verification, describes an analysis demonstrating that the required minimum flow rates are obtained when taking these into account along with IST allowed degradation, pump performance uncertainty, and pump speed uncertainty. The calculation determined that the system is capable of performing its required functions. However, SNC Calculation X3CE11 indicated that the documentation in Calculation X4C1208V01 should be updated to account for nitrogen overpressure and maximum VCT level.
During the audit, the licensee reported that the revision of Calculation X4C1208V01 is in progress and is being tracked by Technical Evaluations Quality Record TE1141907.
Condition Report Quality Record CR 11027149 (entry 11-27-2023), 14982-2 Need Revision, tracks the updating of SNC Procedures 14982-1/2 to include the revised flow acceptance criteria of 18.2 gallons per minute as recommended in Calculation X4C2403V02.
SNC Calculation X4C1302V15 (Version 4, 11-13-2020), AFW Hydraulic Analysis, describes the evaluation of the flow capacity of the auxiliary feedwater (AFW) system for a variety of design-basis configurations. The calculation contains the results for both the current and proposed change to the TS governing the EDG frequency and voltage uncertainty. The calculation concludes that the AFW system is capable of meeting all of the design-basis flow requirements for both degraded and enhanced performance relative to the IST limits and EDG frequency and voltage uncertainty effects.
SNC Example White Paper describes the evaluation of the capability of MOV 1HV-5118 for the EDG frequency and voltage uncertainty effects performed under Appendix B of SNC Calculation X3CE11.
Technical Evaluations Quality Record TE1163836 (entry 10-16-2024), Surveillances Procedures Updates due to EDG UV/UF Impact, tracks the required revisions for SNC Procedures 14804A/B-1/2 (safety injection pumps), 14806A/B-1/2 (containment spray pumps), and 14808A/B-1/2 (centrifugal charging pumps) recommended in Westinghouse Letter LTR-SEE-19-101 based on the EDG frequency and voltage variations.
LDCR Impact Review 2024001, License Amendment Request to Revise Diesel Generator Frequency and Voltage Ranges for Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirements, is a new impact review form prepared to track TE1163836 for updating SNC Procedures 14804A/B-1/2, 14806A/B-1/2, and 14808A/B-1/2.
Based on its independent review of the SNC and Westinghouse calculations, the NRC staff requested the licensee to respond to several questions during the regulatory audit to clarify the calculations for the impact of the EDG voltage and frequency variations on safety-related
equipment. In the audit, the NRC staff also requested the licensee to describe its actions in response to the results of those calculations. From its review of the SNC and Westinghouse documentation and the audit information discussed in this Safety Evaluation, the NRC staff determined that the changes to the TS voltage and frequency tolerances proposed in the LAR will not adversely impact the capability of the safety-related equipment powered by the EDGs to perform their safety functions at Vogtle, Units 1 and 2, and is, therefore, acceptable.
3.12 Editorial Changes The following editorial changes were made due to the proposed TS changes:
SR 3.8.1.15 was moved from the bottom on TS page 3.8.1-14 to the top of TS page 3.8.1-15.
SR 3.8.1.16 was moved from the top of TS page 3.8.1-15 to the bottom of TS page 3.8.1-15.
SR 3.8.1-17 was moved from the bottom of TS page 3.8-15 to TS page 3.8.1-16.
SR 3.8.1-18 was moved from the bottom of TS page 3.8-16 to TS page 3.8.1-17.
SR 3.8-19 and SR 3.8-20 was moved TS page 3.8.1-17 to TS page 3.8.1-18.
There were no technical changes to SRs 3.8.1.15, 3.1.8.16, 3.8.1.17, 18, and 3.8.119. The NRC staff finds the editorial changes of moving the SRs to a different page acceptable, because there are no technical changes to the SRs. The technical changes to SR 3.8.1-20 were addressed above. The NRC staff finds the editorial change of moving from TS page 3.8.1-17 to TS page 3.8.1-18 to be acceptable.
3.13 Technical Conclusion Based on the above, the NRC staff finds that SNC has adequately evaluated the impact of the proposed conservative TS SRs changes of EDGs steady state voltage and frequency on the safety-related loads fed by the EDGs. The proposed TS changes would not affect the continued safe operation and shutdown capability of loads fed by the EDGs, and the licensee would continue to meet the regulatory requirements and guidance discussed in Section 2.4 of this Safety Evaluation.
The NRC staff also determined that there is reasonable assurance that the proposed changes to change the frequency and voltage of the various TS 3.8.1 SRs as stated above will not have an adverse impact on the (1) plant safety analyses; (2) EDG loadings; (3) impact on overvoltage of loads; (4) operating voltage range of EDGs; and (5) operation of safety-related Motors. The NRC staff finds the proposed TS changes to the various TS 3.8.1 SRs are conservative and the supporting analysis reasonable assurance of safe operation and shutdown capability at the revised TS SR values. Based on the above, the revised SRs would continue to meet 10 CFR 50.36(c)(3), GDC 17, and GDC 18. The proposed changes were evaluated in accordance with the WCAP-17308-NP-A guidance and other industrial standards described in this Safety Evaluation. Therefore, the NRC staff determined that the proposed TS SR changes are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Georgia State officials were notified on December 2, 2024, of the proposed issuance of the amendments. On January 9, 2025, the State officials informed the NRC that the State of Georgia has no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts and no significant change in the types of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, published in the Federal Register on May 14, 2024 (89 FR 42000), and there has been no public comment on such finding. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors: Khoi Nguyen, NRR Thomas Scarbrough, NRR Santosh Bhatt, NRR Date: January 16, 2025
ML24198A106 NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DSS/SNSB/BC JLamb KGoldstein Vijay Goel (A)
DMurdock (A) 11/26/2024 11/26/2024 11/24/2024 11/26/2024 NRR/DSS/STSB/BC NRR/DSS/SCPB/BC NRR/DEX/EMIB/BC OGC SMehta MValentin SBailey MChwedczuk - NLO 12/06/2024 12/06/2024 12/12/2024 01/10/2025 NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM MMarkley JLamb 01/16/2025 01/16/2025