ML24260A168

Regulatory Audit Summary Related to Request to Add and Revise Notes Related to Technical Specification Table 3.3.2-1, Function 5

ML24260A168
Person / Time
Site:	Sequoyah, Watts Bar
Issue date:	10/04/2024
From:	Kimberly Green Plant Licensing Branch II
To:	Jim Barstow, Erb D Tennessee Valley Authority
Green K
References
EPID L-2023-LLA-0175
Download: ML24260A168 (1)

Text

October 4, 2024 Delson Erb Vice President, OPS Support Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801

SUBJECT:

SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2; WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 - REGULATORY AUDIT

SUMMARY

RELATED TO REQUEST TO ADD AND REVISE NOTES RELATED TO TECHNICAL SPECIFICATION TABLE 3.3.2-1, FUNCTION 5 (EPID L-2023-LLA-0175)

Dear James Barstow:

By letter to the U.S. Nuclear Regulatory Commission (NRC) dated December 18, 2023, as supplemented by letter dated August 19, 2024, Tennessee Valley Authority (TVA) submitted a license amendment request. The proposed amendments would revise Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2, Technical Specification (TS) Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, Functions 5a and 5b, by adding a note related to the turbine trip function, and revise a note in Watts Bar TS Table 3.3.2-1 to be consistent with the corresponding note in Sequoyah TS Table 3.3.2-1.

To enhance the review of TVAs request, the NRC staff conducted an audit of supporting documents from July 8 - 11, 2024. The staff audited the requested documents to gain a better understanding of the license amendment request and the logic for the turbine valve signals and associated turbine trips and reactor trips. A summary of the regulatory audit is enclosed.

The NRC staff did not identify any significant issues during the audit.

Sincerely,

/RA/

Kimberly J. Green, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos.

50-327 and 50-328 50-390 and 50-391

Enclosure:

Regulatory Audit Summary cc: Listserv

Enclosure REGULATORY AUDIT

SUMMARY

RELATED TO LICENSE AMENDMENT REQUEST REGARDING TECHNICAL SPECIFICATION TABLE 3.3.2-1, FUNCTION 5 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-328 AND 50-328 WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-390 AND 50-391

1.0 BACKGROUND

A regulatory audit is a planned license or regulation-related activity that includes the examination and evaluation of docketed and non-docketed information. The audit was conducted with the intent to gain understanding, to verify information, and to identify information that will require docketing to support the basis of a licensing or regulatory decision.

By application dated December 18, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23352A298), as supplemented by letter dated August 19, 2024 (ML24232A071), pursuant to Section 50.90 of Title 10 of the Code of Federal Regulations (10 CFR), the Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) to amend Facility Operating License Nos. DPR-77 and DPR-79 for Sequoyah Nuclear Plant (Sequoyah), Units 1 and 2, respectively, and Facility Operating License Nos. NPF-90 and NPF-96 for Watts Nuclear Plant (Watts Bar), Units 1 and 2, respectively. The proposed amendments would revise Sequoyah and Watts Bar Technical Specification (TS) Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, by adding a note to Functions 5a and 5b related to the turbine trip function. The amendments for Watts Bar, Units 1 and 2, would also revise note (f) of Watts Bar, Unit 1, TS Table 3.3.2-1 and note (h) of Watts Bar, Unit 2, TS Table 3.3.2-1 to be consistent with the corresponding note in Sequoyah, Units 1 and 2, TS Table 3.3.2-1.

The NRC staff performed a preliminary review of the LAR and determined that a regulatory audit would assist in the timely completion of the review. The regulatory audit was performed consistent with NRC Office of Nuclear Reactor Regulation Office Instruction LIC-111, Revision 1, Regulatory Audits, dated October 31, 2019 (ML19226A274).

2.0 AUDIT ACTIVITIES AND OBSERVATIONS The NRC staff conducted a regulatory audit that consisted of a remote audit from July 8 - 11, 2024. The remote audit was conducted using an online portal. An audit plan was provided to

TVA on June 11, 2024 (ML24177A141). The list of information uploaded by TVA in response to the NRC staffs request and examined by the audit team is provided in Section 4.0 below.

The purpose of the audit was to (1) confirm the NRC staffs understanding of the LAR, (2) gain a better understanding of the logic for the turbine valve signals and associated turbine trips and reactor trips and their implications for the LAR, and (3) identify questions and requests that may become formal requests for additional information.

The NRC staff examined the documents provided on the portal by TVA. The staff confirmed its understanding of the logic for the turbine stop (throttle) valves and governor valves.

The NRC staff held an audit exit call with members of TVA on July 11, 2024. After the conclusion of the audit, the NRC staff determined no additional information would be needed for the staff to complete the review of the LAR.

3.0 AUDIT PARTICIPANTS NRC TVA Ahsan Sallman Russell Wells David Nold Shawna Hughes Nicholas Soliz Dustin Martin (7/8)

Tarico Sweat Paul Parashak Kim Green Joyce Artis (7/8)

Milton Valentin (7/11)

Isaac Chandler (7/8)

Caleb Clements Keith Skubisz (7/8)

Andrew McNeil Stuart Rymer (7/11)

Andy Taylor (7/11)

Jesse Baron (7/11) 4.0 DOCUMENTS PROVIDED IN ELECTRONIC READING ROOM Item #

Audit Item 1

Current logic (e.g., diagrams) for turbine trip signal related to the closing of the turbine stop valves and turbine governor valves WATTS_BAR1_r13, Sheet 11, Module Revision 13, GAP Sheet 305 TRIP Unit 1 -

WBN WATTS_BAR2_r6, Sheet 6, Module Revision 6, GAP Sheet 305 TRIP Unit 2 - WBN SEQUOYAH_r5, Sheet 2, Module Revision 5, GAP Sheet 254 Unit 1 - SQN 2

Information (e.g., logic diagrams) related to the turbine trip signal that is generated from the safety-related reactor trip signal Elementary Diagram 1-45W600-47-11, Main Turbine Control, for Watts Bar Nuclear Plant Elementary Diagram 1-45N647-11, Main Turbine Control, for Sequoyah Nuclear Plant

Item #

Audit Item 3

Information (e.g., logic diagrams) related to the reactor trip signal as it relates the turbine trip signal and turbine stop valve indication signal Elementary Diagram 1-45W600-47-11, Main Turbine Control, for Watts Bar Nuclear Plant Elementary Diagram 1-45N647-11, Main Turbine Control, for Sequoyah Nuclear Plant 4

Any analyses or evaluations that considered anticipated operational occurrence(s)

TV Sequoyah UFSAR Watts Bar UFSAR 5

Any analyses or evaluations that considered false turbine stop valve indication (valve indication is OPEN but valve is closed) but the reactor does not trip Sequoyah Unit 1, Technical Specification Bases, Section 3.3.1, pages B 3.3.1-24 and B 3.3.1-25 Watts Bar Unit 1, Technical Specification Bases, Section 3.3.1, pages B 3.3.1-23 and B 3.3.1-24 6

Any analyses or evaluations that considered false turbine stop valve indication (valve indication is CLOSED but valve is open) and the reactor trips but turbine stop valves and governor valves are left open TVA provide a description of what would transpire in this scenario and stated that the proposed LAR has no impact on this scenario.

7 Description of any proposed design changes needed to support the requested TS change (e.g., changes to logic) and continued compliance with relevant general design criteria TVA provided a statement that no design changes are needed to support the requested TS change.

8 Plant component ID listing for all turbine-related stop, throttle, governor, and control valves TVA provided the component ID numbers for the main turbine stop (throttle) valves, governor valves, moisture separator reheater (MSR) to low pressure turbine stop valves, and MSR to low pressure turbine intercept valves.

9 Component description, including function, for reheat stop valves and interceptor valves TVA provided a description of the components and function for the reheat stop valves and interceptor valves.

10 Information related to plant operations during Mode 1 with % RATED THERMAL POWER >

5% but < 50% (P-9 interlock) with all throttle valves, control valves, reheat stop valves, and interceptor valves in the CLOSED position TVA provided a description of what would transpire for the given circumstances.

11 Information related to plant operations during Mode 1 with % RATED THERMAL POWER >

5 % and the P-14 interlock engaged (i.e., 2/3 steam generator water level above setpoint on one or more steam generators)

TVA provided a description of what would transpire for the given circumstances.

Item #

Audit Item 12 Provide further explanation as to how rendering a turbine stop valve or governor valve renders both trains of engineered safety features actuation system (ESFAS) inoperable Sequoyah Nuclear Plant, Unit 1, Surveillance Instruction, 1-SI-IRT-099-621.A, Response Time Test of ESFAS Slave Relay K621 Actuated Devices (Turbine Trip)

Train A, Revision 0013 Sequoyah Nuclear Plant, Unit 1, Surveillance Instruction, 1-SI-IRT-099-621.B, Response Time Test of ESFAS Slave Relay K621 Actuated Devices (Turbine Trip)

Train B, Revision 0010

ML24260A168 OFFICE NRR/DORL/LPL2-2/PM*

NRR/DORL/LPL2-2/LA NRR/DSS/SCPB/BC NAME KGreen ABaxter MValentin DATE 09/16/24 09/23/24 09/24/24 OFFICE NRR/DSS/SNSB/BC NRR/DORL/LPL2-2/BC NRR/DORL/LPL2-2/PM NAME PSahd DWrona KGreen DATE 09/24/24 10/04/24 10/04/24