CNL-25-023, Application to Revise Technical Specifications to Adopt TSTF-599-A, Revision 1, Eliminate Periodic Surveillance Test of Simultaneous Start of Redundant Diesel Generators (SQN-TS-25-01 and WBN-TS-25-03)
| ML25231A300 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah, Watts Bar  |
| Issue date: | 08/19/2025 |
| From: | Hulvey K Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| CNL-25-023 | |
| Download: ML25231A300 (1) | |
Text
1101 Market Street, Chattanooga, Tennessee 37402 CNL-25-023 August 19, 2025 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-77 and DPR-79 NRC Docket Nos. 50-327 and 50-328 Watts Bar Nuclear Plant, Units 1 and 2 Facility Operating License Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391
Subject:
Application to Revise Technical Specifications to Adopt TSTF-599-A, Revision 1, "Eliminate Periodic Surveillance Test of Simultaneous Start of Redundant Diesel Generators" (SQN-TS-25-01 and WBN-TS-25-03)
In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) 50.90, Application for amendment of license, construction permit, or early site permit, Tennessee Valley Authority (TVA) is submitting a request for an amendment to Renewed Facility Operating License Nos. DPR-77 and DPR-79 for the Sequoyah Nuclear Plant (SQN), Units 1 and 2 and Facility Operating License Nos. NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively.
TVA requests adoption of Technical Specifications Task Force (TSTF)-599-A, Revision 1, "Eliminate Periodic Surveillance Test of Simultaneous Start of Redundant Diesel Generators," which is an approved change to the Standard Technical Specifications (STS),
into the SQN Units 1 and 2 Technical Specifications (TS) and the WBN Units 1 and 2 TS.
TSTF-599-A eliminates the periodic Surveillance Requirement (SR) to verify that all required diesel generators (DGs) achieve rated frequency and voltage within the specified time period when started simultaneously.
The enclosure provides a description and assessment of the proposed changes. provides the existing SQN Units 1 and 2 TS pages marked up to show the proposed changes. Attachment 2 provides the existing WBN Units 1 and 2 TS pages marked up to show the proposed changes. Attachment 3 provides the existing SQN Units 1 and 2 TS Bases pages marked up to show revised text associated with the proposed TS. provides the existing WBN Units 1 and 2 TS Bases pages marked up to show revised text associated with the proposed TS. Changes to the existing TS Bases are provided for information only and will be implemented under the TS Bases Control Program.
U.S. Nuclear Regulatory Commission CNL-25-023 Page 2 August 19, 2025 TVA requests that the amendment be reviewed under the Consolidated Line Item Improvement Process (CLIIP). Approval of the proposed amendment is requested within 6 months of completion of the NRCs acceptance review, with a 60-day implementation period.
TVA has determined that there are no significant hazards considerations associated with the proposed change and that the TS change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9). In accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and enclosure to the Tennessee State Department of Environment and Conservation.
There are no new regulatory commitments contained in this letter. Please address any questions regarding this request to Amber V. Aboulfaida, Senior Manager, Fleet Licensing, at avaboulfaida@tva.gov.
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 19th day of August 2025.
Respectfully, Kimberly D. Hulvey General Manager, Nuclear Regulatory Affairs & Emergency Preparedness
Enclosure:
Description and Assessment cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant NRC Project Manager - Sequoyah Nuclear Plant NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant Director, Division of Radiological Health - Tennessee Department of Environment and Conservation Digitally signed by Edmondson, Carla Date: 2025.08.19 09:09:47 -04'00'
Enclosure CNL-25-023 Description and Assessment
Subject:
Application to Revise Technical Specifications to Adopt TSTF-599-A, Revision 1, "Eliminate Periodic Surveillance Test of Simultaneous Start of Redundant Diesel Generators" (SQN-TS-25-01 and WBN-TS-25-03)
Table of Contents Contents 1.0
SUMMARY
DESCRIPTION............................................................................................... 1
2.0 ASSESSMENT
................................................................................................................... 1 2.1 Applicability of Safety Evaluation.................................................................................. 1 2.2 Variations...................................................................................................................... 1
3.0 REGULATORY ANALYSIS
................................................................................................ 1 3.1 No Significant Hazards Considerations Analysis.......................................................... 1 3.2 Conclusions................................................................................................................... 3
4.0 ENVIRONMENTAL CONSIDERATION
............................................................................. 3 Attachments
- 1. Proposed TS Changes (Mark-Ups) for SQN Units 1 and 2
- 2. Proposed TS Changes (Mark-Ups) for WBN Units 1 and 2
- 3. Proposed TS Bases Page Changes (Mark-Ups) for SQN Units 1 and 2 (For Information Only)
- 4. Proposed TS Bases Page Changes (Mark-Ups) for WBN Units 1 and 2 (For Information Only)
Enclosure CNL-25-023 E1 of 3 1.0
SUMMARY
DESCRIPTION In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) 50.90, Application for amendment of license, construction permit, or early site permit, Tennessee Valley Authority (TVA) is submitting a request for an amendment to Renewed Facility Operating License Nos. DPR-77 and DPR-79 for the Sequoyah Nuclear Plant (SQN), Units 1 and 2 and Facility Operating License Nos. NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively.
TVA requests adoption of Technical Specifications Task Force (TSTF)-599-A, Revision 1, "Eliminate Periodic Surveillance Test of Simultaneous Start of Redundant Diesel Generators,"
which is an approved change to the Standard Technical Specifications (STS), into the SQN Units 1 and 2 Technical Specifications (TS) and the WBN Units 1 and 2 TS. TSTF-599 eliminates the periodic Surveillance Requirement (SR) to verify that all required diesel generators (DGs) achieve rated frequency and voltage within the specified time period when started simultaneously.
2.0 ASSESSMENT
2.1 Applicability of Safety Evaluation TVA has reviewed the safety evaluation for TSTF-599-A provided to the Technical Specifications Task Force in a letter dated May 5, 2025 (ML25119A287). This review included the NRC staffs evaluation, as well as the information provided in TSTF-599-A. TVA has concluded that the justifications presented in TSTF-599-A and the safety evaluation prepared by the NRC staff are applicable to SQN Units 1 and 2 and WBN Units 1 and 2 and justify this amendment for the incorporation of the changes to the SQN Units 1 and 2 TS and the WBN Units 1 and 2 TS.
2.2 Variations The SQN Units 1 and 2 and the WBN Units 1 and 2 TS utilize different numbering than the STS on which TSTF-599 was based. Specifically, TSTF-599-A deletes Westinghouse STS SR 3.8.1.20 (including deleting the reference to Westinghouse STS SR 3.8.1.20 in Westinghouse SR 3.8.2.1). The corresponding SR for SQN Units 1 and 2 is SR 3.8.1.19 and the corresponding SR for WBN Units 1 and 2 is SR 3.8.1.21. These differences are administrative and do not affect the applicability of TSTF-599 to the SQN Units 1 and 2 and the WBN Units 1 and 2 TS.
While the wording of SQN Units 1 and 2 SR 3.8.1.19 and WBN Units 1 and 2 SR 3.8.1.21 has slightly different wording than STS SR 3.8.1.20, they still verify that the required diesel generators (DGs) achieve rated frequency and voltage within the specified time period when started simultaneously. Therefore, deletion of the SQN Units 1 and 2 SR 3.8.1.19 and WBN Units 1 and 2 SR 3.8.1.21 is appropriate and consistent with TSTF-599-A.
3.0 REGULATORY ANALYSIS
3.1 No Significant Hazards Considerations Analysis Tennessee Valley Authority (TVA) requests adoption of Technical Specifications Task Force (TSTF)-599-A, Revision 1, "Eliminate Periodic Surveillance Test of Simultaneous Start of
Enclosure CNL-25-023 E2 of 3 Redundant Diesel Generators," which is an approved change to the Standard Technical Specifications (STS), into the Sequoyah Nuclear Plant, Units 1 and 2 Technical Specifications (TS) and the Watts Bar Nuclear Plant, Units 1 and 2 TS. Technical Specification Task Force 599-A eliminates the periodic Surveillance Requirement to verify that all required diesel generators (DGs) achieve rated frequency and voltage within the specified time period when started simultaneously.
TVA evaluated whether or not a significant hazards consideration is involved with the proposed amendments by focusing on the three standards set forth in Title 10 of the Code of Federal Regulations (10 CFR) 50.92, "Issuance of amendment," as discussed below:
- 1. Does the proposed amendment involve a significant increase in the probability or consequence of an accident previously evaluated?
Response: No.
The proposed change eliminates a periodic Surveillance test which verifies that all required diesel generators (DGs) achieve rated frequency and voltage within the specified time period when started simultaneously. Simultaneous start of the redundant DGs is not an initiator of any accident previously evaluated. The fast start of the DGs is verified by other Surveillance tests and industry survey of successful historical performance of the simultaneous test. As a result, the DG reliability and the attendant effect on the consequences of any accident previously evaluated are not affected.
Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
- 2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No.
The proposed change eliminates a periodic Surveillance test which verifies that all required DGs achieve rated frequency and voltage within the specified time period when started simultaneously. No new or different accidents result from the proposed change. The changes do not involve a physical alteration of the plant (i.e., no new or different type of equipment will be installed) or a change in the methods governing normal plant operation.
In addition, the changes do not impose any new or different requirements. The changes do not alter assumptions made in the safety analysis. The proposed changes are consistent with the safety analysis assumptions and current plant operating practice.
Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
- 3. Does the proposed change involve a significant reduction in a margin of safety?
Response: No.
The proposed change eliminates a periodic Surveillance test which verifies that all required DGs achieve rated frequency and voltage within the specified time period when started simultaneously. The proposed change does not adversely affect existing plant safety margins, or the reliability of the equipment assumed to operate in the safety analysis. As
Enclosure CNL-25-023 E3 of 3 such, there are no changes being made to safety analysis assumptions, safety limits or limiting safety system settings that would adversely affect plant safety as a result of the proposed change.
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, it is concluded that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of no significant hazards consideration is justified.
3.2 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
4.0 ENVIRONMENTAL CONSIDERATION
A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any radioactive effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b),
no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.
Enclosure CNL-25-023 Proposed TS Changes (Mark-Ups) for SQN Units 1 and 2
AC Sources - Operating 3.8.1 SEQUOYAH - UNIT 1 3.8.1-16 Amendment 334, SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.19
NOTE-------------------------------
All DG starts may be preceded by an engine prelube period.
Verify when started simultaneously from standby condition, each DG achieves, in 10 seconds, voltage 6800 V and frequency 58.8 Hz.
In accordance with the Surveillance Frequency Control Program
AC Sources - Shutdown 3.8.2 SEQUOYAH - UNIT 1 3.8.2-3 Amendment 334, 369, SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.2.1
NOTE------------------------------
The following SRs are not required to be performed:
SR 3.8.1.3, SR 3.8.1.9 through SR 3.8.1.11, and SR 3.8.1.13 through SR 3.8.1.17.
For AC sources required to be OPERABLE, the SRs of Specification 3.8.1, "AC Sources - Operating,"
except SR 3.8.1.12 and, SR 3.8.1.18, and SR 3.8.1.19, are applicable.
In accordance with applicable SRs
AC Sources - Operating 3.8.1 SEQUOYAH - UNIT 2 3.8.1-16 Amendment 327, SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.19
NOTE-------------------------------
All DG starts may be preceded by an engine prelube period.
Verify when started simultaneously from standby condition, each DG achieves, in 10 seconds, voltage 6800 V and frequency 58.8 Hz.
In accordance with the Surveillance Frequency Control Program
AC Sources - Shutdown 3.8.2 SEQUOYAH - UNIT 2 3.8.2-3 Amendment 327, 363, SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.2.1
NOTE------------------------------
The following SRs are not required to be performed:
SR 3.8.1.3, SR 3.8.1.9 through SR 3.8.1.11, and SR 3.8.1.13 through SR 3.8.1.17.
For AC sources required to be OPERABLE, the SRs of Specification 3.8.1, "AC Sources - Operating,"
except SR 3.8.1.12 and, SR 3.8.1.18, and SR 3.8.1.19, are applicable.
In accordance with applicable SRs
Enclosure CNL-25-023 Proposed TS Changes (Mark-Ups) for WBN Units 1 and 2
AC Sources-Operating 3.8.1 Watts Bar-Unit 1 3.8-15 Amendment 89, 102, 110, 132, SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.19
NOTE--------------------------------
For DGs 1A-A and 1B-B, this Surveillance shall not be performed in MODE 1, 2, 3, or 4. However, 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;
- c.
DG auto-starts from standby condition and:
- 1.
energizes permanently connected loads in 10 seconds,
- 2.
energizes auto-connected emergency loads through load sequencer,
- 3.
achieves steady state voltage:
6800 V and 7260 V,
- 4.
achieves steady state frequency 59.8 Hz and 60.1 Hz, and
- 5.
supplies permanently connected and auto-connected emergency loads for 5 minutes.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.20 Verify during idle operation that any automatic or emergency start signal disables the idle start circuitry and commands the engine to full speed.
In accordance with the Surveillance Frequency Control Program (continued)
AC Sources-Operating 3.8.1 Watts Bar-Unit 1 3.8-16 Amendment 102, 103, 132, 136, SURVEILLANCE REQUIREMENTS (continued)THIS PAGE INTENTIONALLY LEFT BLANK SURVEILLANCE FREQUENCY SR 3.8.1.21 Verify when started simultaneously from standby condition, each DG achieves, in 10 seconds, voltage 6800 V and frequency 58.8 Hz. Verify after DG fast start from standby conditions that the DG achieves steady state voltage 6800 V and 7260 V, and frequency 59.8 Hz and 60.1 Hz.
In accordance with the Surveillance Frequency Control Program
AC Sources-Shutdown 3.8.2 Watts Bar-Unit 1 3.8-20 Amendment SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.2.1
NOTE-----------------------------
The following SRs are not required to be performed:
SR 3.8.1.3, SR 3.8.1.6, SR 3.8.1.9 through SR 3.8.1.16, SR 3.8.1.18 and SR 3.8.1.19.
For AC sources required to be OPERABLE, the SRs of Specification 3.8.1, "AC Sources-Operating,"
except SR 3.8.1.8, and SR 3.8.1.17 and SR 3.8.1.21, are applicable.
In accordance with applicable SRs
AC Sources - Operating 3.8.1 Watts Bar - Unit 2 3.8-13 Amendment 36, 41, SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.20 Verify during idle operation that any automatic or emergency start signal disables the idle start circuitry and commands the engine to full speed.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.21 Verify when started simultaneously from standby condition, each DG achieves, in 10 seconds, voltage 6800 V and frequency 58.8 Hz. Verify after DG fast start from standby conditions that the DG achieves steady state voltage 6800 V and 7260 V, and frequency 59.8 Hz and 60.1 Hz.
In accordance with the Surveillance Frequency Control Program
AC Sources - Shutdown 3.8.2 Watts Bar - Unit 2 3.8-17 Amendment SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.2.1
NOTE------------------------------
The following SRs are not required to be performed:
SR 3.8.1.3, SR 3.8.1.6, SR 3.8.1.9 through SR 3.8.1.16, SR 3.8.1.18 and SR 3.8.1.19.
For AC sources required to be OPERABLE, the SRs of Specification 3.8.1, "AC Sources-Operating,"
except SR 3.8.1.8 and, SR 3.8.1.17, and SR 3.8.1.21, are applicable.
In accordance with applicable SRs
Enclosure CNL-25-023 Proposed TS Bases Page Changes (Mark-Ups) for SQN Units 1 and 2 (For Information Only)
AC Sources - Operating B 3.8.1 SEQUOYAH - UNIT 1 B 3.8.1-31 Revision 45 59, BASES SURVEILLANCE REQUIREMENTS (continued)
This SR is modified by two Notes. The reason for Note 1 is to minimize wear and tear on the DGs during testing. For the purpose of this testing, the DGs must be started from standby conditions, that is, with the engine coolant and oil continuously circulated and temperature maintained consistent with manufacturer recommendations for DGs. The reason for Note 2 is that the performance of the Surveillance would remove a required offsite circuit from service, perturb the electrical distribution system, and challenge safety systems. This restriction from normally performing the Surveillance for DGs 1A-A and 1B-B in MODE 1 or 2 is further amplified to allow portions of the Surveillance to be performed for the purpose of reestablishing OPERABILITY (e.g., post work testing following corrective maintenance, corrective modification, deficient or incomplete surveillance testing, and other unanticipated OPERABILITY concerns) provided an assessment determines plant safety is maintained or enhanced. This assessment shall, as a minimum, consider the potential outcomes and transients associated with a failed partial Surveillance, a successful partial Surveillance, and a perturbation of the offsite or onsite system when they are tied together or operated independently for the partial Surveillance; as well as the operator procedures available to cope with these outcomes. These shall be measured against the avoided risk of a plant shutdown and startup to determine that plant safety is maintained or enhanced when portions of the Surveillance are performed in MODE 1 or 2. Risk insights or deterministic methods may be used for the assessment. Credit may be taken for unplanned events that satisfy this SR.
SR 3.8.1.19 This Surveillance demonstrates that the DG starting independence has not been compromised. Also, this Surveillance demonstrates that each engine can achieve proper speed within the specified time when the DGs are started simultaneously.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
This SR is modified by a Note. The reason for the Note is to minimize wear on the DG during testing. For the purpose of this testing, the DGs must be started from standby conditions, that is, with the engine coolant and oil continuously circulated and temperature maintained consistent with manufacturer recommendations.
AC Sources - Shutdown B 3.8.2 SEQUOYAH - UNIT 1 B 3.8.2-5 Revision 45, BASES ACTIONS (continued)
LCO 3.8.10 must be immediately entered. This Note allows Condition A to provide requirements for the loss of the offsite circuit, whether or not a train is de-energized. LCO 3.8.10 would provide the appropriate restrictions for the situation involving a de-energized train.
SURVEILLANCE SR 3.8.2.1 REQUIREMENTS SR 3.8.2.1 requires the SRs from LCO 3.8.1 that are necessary for ensuring the OPERABILITY of the AC sources in other than MODES 1, 2, 3, and 4. SR 3.8.1.8 is not required to be met since only one offsite circuit is required to be OPERABLE. SR 3.8.1.12 and SR 3.8.1.18 are not required to be met because the ESF actuation signal is not required to be OPERABLE. SR 3.8.1.19 is excepted because starting independence is not required with the DG(s) that is not required to be OPERABLE.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DG(s) from being paralleled with the offsite power network or otherwise rendered inoperable during performance of SRs, and to preclude deenergizing a required 6.9 kV shutdown board or disconnecting a required offsite circuit during performance of SRs. With limited AC sources available, a single event could compromise both the required circuit and the DGs. It is the intent that these SRs must still be capable of being met, but actual performance is not required during periods when the DGs and offsite circuit is required to be OPERABLE.
Refer to the corresponding Bases for LCO 3.8.1 for a discussion of each SR.
REFERENCES None.
AC Sources - Operating B 3.8.1 SEQUOYAH - UNIT 2 B 3.8.1-31 Revision 45 59, BASES SURVEILLANCE REQUIREMENTS (continued)
This SR is modified by two Notes. The reason for Note 1 is to minimize wear and tear on the DGs during testing. For the purpose of this testing, the DGs must be started from standby conditions, that is, with the engine coolant and oil continuously circulated and temperature maintained consistent with manufacturer recommendations for DGs. The reason for Note 2 is that the performance of the Surveillance would remove a required offsite circuit from service, perturb the electrical distribution system, and challenge safety systems. This restriction from normally performing the Surveillance for DGs 2A-A and 2B-B in MODE 1 or 2 is further amplified to allow portions of the Surveillance to be performed for the purpose of reestablishing OPERABILITY (e.g., post work testing following corrective maintenance, corrective modification, deficient or incomplete surveillance testing, and other unanticipated OPERABILITY concerns) provided an assessment determines plant safety is maintained or enhanced. This assessment shall, as a minimum, consider the potential outcomes and transients associated with a failed partial Surveillance, a successful partial Surveillance, and a perturbation of the offsite or onsite system when they are tied together or operated independently for the partial Surveillance; as well as the operator procedures available to cope with these outcomes. These shall be measured against the avoided risk of a plant shutdown and startup to determine that plant safety is maintained or enhanced when portions of the Surveillance are performed in MODE 1 or 2. Risk insights or deterministic methods may be used for the assessment. Credit may be taken for unplanned events that satisfy this SR.
SR 3.8.1.19 This Surveillance demonstrates that the DG starting independence has not been compromised. Also, this Surveillance demonstrates that each engine can achieve proper speed within the specified time when the DGs are started simultaneously.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
This SR is modified by a Note. The reason for the Note is to minimize wear on the DG during testing. For the purpose of this testing, the DGs must be started from standby conditions, that is, with the engine coolant and oil continuously circulated and temperature maintained consistent with manufacturer recommendations.
AC Sources - Shutdown B 3.8.2 SEQUOYAH - UNIT 2 B 3.8.2-5 Revision 45, BASES ACTIONS (continued)
LCO 3.8.10 must be immediately entered. This Note allows Condition A to provide requirements for the loss of the offsite circuit, whether or not a train is de-energized. LCO 3.8.10 would provide the appropriate restrictions for the situation involving a de-energized train.
SURVEILLANCE SR 3.8.2.1 REQUIREMENTS SR 3.8.2.1 requires the SRs from LCO 3.8.1 that are necessary for ensuring the OPERABILITY of the AC sources in other than MODES 1, 2, 3, and 4. SR 3.8.1.8 is not required to be met since only one offsite circuit is required to be OPERABLE. SR 3.8.1.12 and SR 3.8.1.18 are not required to be met because the ESF actuation signal is not required to be OPERABLE. SR 3.8.1.19 is excepted because starting independence is not required with the DG(s) that is not required to be OPERABLE.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DG(s) from being paralleled with the offsite power network or otherwise rendered inoperable during performance of SRs, and to preclude deenergizing a required 6.9 kV shutdown board or disconnecting a required offsite circuit during performance of SRs. With limited AC sources available, a single event could compromise both the required circuit and the DGs. It is the intent that these SRs must still be capable of being met, but actual performance is not required during periods when the DGs and offsite circuit is required to be OPERABLE.
Refer to the corresponding Bases for LCO 3.8.1 for a discussion of each SR.
REFERENCES None.
Enclosure CNL-25-023 Proposed TS Bases Page Changes (Mark-Ups) for WBN Units 1 and 2 (For Information Only)
AC Sources - Operating B 3.8.1 BASES (continued)
Watts Bar-Unit 1 B 3.8-35 Revision 162, Amendment 132, SURVEILLANCE SR 3.8.1.21 REQUIREMENTS (continued)
This Surveillance demonstrates that the DG starting independence has not been compromised. Also, this Surveillance demonstrates that each engine can achieve proper speed within the specified time when the DGs are started simultaneously. The minimum voltage and frequency stated in the SR are those necessary to ensure the DG can accept DBA loading while maintaining acceptable voltage and frequency levels. Stable operation at the nominal voltage and frequency values is also essential to establishing DG OPERABILITY, but a time constraint is not imposed. This is because a typical DG will experience a period of voltage and frequency oscillations prior to reaching steady state operation if these oscillations are not dampened out by load application. This period may extend beyond the 10 second acceptance criteria and could be a cause for failing the SR. In lieu of a time constraint in the SR, WBN will monitor and trend the actual time to reach steady state operation as a means of ensuring there is no voltage regulator or governor degradation which could cause a DG to become inoperable.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
For the purpose of this testing, the DGs shall be started from standby conditions, that is, with the engine coolant and oil being continuously circulated and temperature maintained consistent with manufacturer recommendations. The DG engines for WBN have an oil circulation and soakback system that operates continuously to preclude the need for a prelube and warmup when a DG is started from standby.
Diesel Generator Test Schedule The DG test schedule (Table 3.8.1-1) implements the recommendations of Revision 3 to Regulatory Guide 1.9 (Ref. 3). The purpose of this test schedule is to provide timely test data to establish a confidence level associated with the goal to maintain DG reliability > 0.975 per demand.
According to Regulatory Guide 1.9, Revision 3 (Ref. 3), each DG should be tested at least once every 31 days. Whenever a DG has experienced 4 or more valid failures in the last 25 valid tests, the maximum time between tests is reduced to 7 days. Four failures in 25 valid tests is a failure rate of 0.16, or the threshold of acceptable DG performance, and hence may be an early indication of the degradation of DG reliability. When considered in the light of a long history of tests, however, 4 failures in the last 25 valid tests may only be a statistically probable distribution of random events. Increasing the test Frequency will allow for a more timely accumulation of additional test data upon which to base judgment of the reliability of the DG. The increased test Frequency must be maintained until seven consecutive, failure free tests have been performed.
AC Sources - Shutdown B 3.8.2 BASES Watts Bar-Unit 1 B 3.8-43 Revision Amendment ACTIONS A.2.1, A.2.2, A.2.3, A.2.4, B.1, B.2, B.3, and B.4 (continued)
Pursuant to LCO 3.0.6, the Distribution System's ACTIONS would not be entered even if all AC sources to it are inoperable, resulting in de-energization.
Therefore, the Required Actions of Condition A are modified by a Note to indicate that when Condition A is entered with no AC power to any 6.9 kV shutdown board, the ACTIONS for LCO 3.8.10 must be immediately entered. This Note allows Condition A to provide requirements for the loss of the offsite circuit, whether or not a train is de-energized. LCO 3.8.10 would provide the appropriate restrictions for the situation involving a de-energized train.
SURVEILLANCE SR 3.8.2.1 REQUIREMENTS SR 3.8.2.1 requires the SRs from LCO 3.8.1 that are necessary for ensuring the OPERABILITY of the AC sources in other than MODES 1, 2, 3, and 4. SR 3.8.1.8 is not required to be met since only one offsite circuit is required to be OPERABLE. SR 3.8.1.17 is not required to be met because the required OPERABLE DG(s) is not required to undergo periods of being synchronized to the offsite circuit. SR 3.8.1.21 is excepted because starting independence is not required with the DG(s) that is not required to be operable.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DG(s) from being paralleled with the offsite power network or otherwise rendered inoperable during performance of SRs, and to preclude deenergizing a required 6.9 kV bus or disconnecting a required offsite circuit during performance of SRs. With limited AC sources available, a single event could compromise both the required circuit and the DG. It is the intent that these SRs must still be capable of being met, but actual performance is not required during periods when the DG and offsite circuit is required to be OPERABLE.
Refer to the corresponding Bases for LCO 3.8.1 for a discussion of each SR.
REFERENCES
- 1.
Watts Bar FSAR, Section 8.0, "Electric Power."
- 2.
Title 10, Code of Federal Regulations, Part 50, General Design Criterion 17, "Electric Power Systems."
AC Sources - Operating B 3.8.1 BASES (continued)
Watts Bar - Unit 2 B 3.8-35 Revision 34, 40, Amendment 36, 41, SURVEILLANCE REQUIREMENTS (continued)
SR 3.8.1.20 This SR verifies that DG availability is not compromised by the idle start circuitry, when in the idle mode of operation, and that an automatic or emergency start signal will disable the idle start circuitry and command the engine to go to full speed.
SR 3.8.1.21 This Surveillance demonstrates that the DG starting independence has not been compromised. Also, this Surveillance demonstrates that each engine can achieve proper speed within the specified time when the DGs are started simultaneously. The minimum voltage and frequency stated in the SR are those necessary to ensure the DG can accept DBA loading while maintaining acceptable voltage and frequency levels. Stable operation at the nominal voltage and frequency values is also essential to establishing DG OPERABILITY, but a time constraint is not imposed.
This is because a typical DG will experience a period of voltage and frequency oscillations prior to reaching steady state operation if these oscillations are not dampened out by load application. This period may extend beyond the 10 seconds acceptance criteria and could be a cause for failing the SR. In lieu of a time constraint in the SR, WBN will monitor and trend the actual time to reach steady state operation as a means of ensuring there is no voltage regulator or governor degradation which could cause a DG to become inoperable.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
For the purpose of this testing, the DGs shall be started from standby conditions, that is, with the engine coolant and oil being continuously circulated and temperature maintained consistent with manufacturer recommendations. The DG engines for WBN have an oil circulation and soakback system that operates continuously to preclude the need for a prelube and warmup when a DG is started from standby.
AC Sources - Shutdown B 3.8.2 BASES (continued)
Watts Bar - Unit 2 B 3.8-42 Revision Amendment ACTIONS A.2.1, A.2.2, A.2.3, A.2.4, B.1, B.2, B.3, and B.4 (continued)
The Completion Time of immediately is consistent with the required times for actions requiring prompt attention. The restoration of the required AC electrical power sources should be completed as quickly as possible in order to minimize the time during which the plant safety systems may be without sufficient power.
Pursuant to LCO 3.0.6, the Distribution System's ACTIONS would not be entered even if all AC sources to it are inoperable, resulting in de-energization. Therefore, the Required Actions of Condition A are modified by a Note to indicate that when Condition A is entered with no AC power to any 6.9 kV shutdown board, the ACTIONS for LCO 3.8.10 must be immediately entered. This Note allows Condition A to provide requirements for the loss of the offsite circuit, whether or not a train is de-energized. LCO 3.8.10 would provide the appropriate restrictions for the situation involving a de-energized train.
SURVEILLANCE REQUIREMENTS SR 3.8.2.1 SR 3.8.2.1 requires the SRs from LCO 3.8.1 that are necessary for ensuring the OPERABILITY of the AC sources in other than MODES 1, 2, 3, and 4. SR 3.8.1.8 is not required to be met since only one offsite circuit is required to be OPERABLE. SR 3.8.1.17 is not required to be met because the required OPERABLE DG(s) is not required to undergo periods of being synchronized to the offsite circuit. SR 3.8.1.21 is excepted because starting independence is not required with the DG(s) that is not required to be operable.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DG(s) from being paralleled with the offsite power network or otherwise rendered inoperable during performance of SRs, and to preclude de-energizing a required 6.9 kV bus or disconnecting a required offsite circuit during performance of SRs. With limited AC sources available, a single event could compromise both the required circuit and the DG. It is the intent that these SRs must still be capable of being met, but actual performance is not required during periods when the DG and offsite circuit is required to be OPERABLE.
Refer to the corresponding Bases for LCO 3.8.1 for a discussion of each SR.
REFERENCES
- 1.
Watts Bar FSAR, Section 8.0, "Electric Power."
- 2.
Title 10, Code of Federal Regulations, Part 50, General Design Criterion 17, "Electric Power Systems."