ML24131A001

Issuance of Amendment Nos. 167 and 73 Regarding Adoption of Technical Specification Task Force Traveler TSTF-427-A, Revision 2

ML24131A001
Person / Time
Site:	Watts Bar
Issue date:	07/02/2024
From:	Kimberly Green Plant Licensing Branch II
To:	Jim Barstow Tennessee Valley Authority
Green K
References
EPID L-2024-LLA-0003
Download: ML24131A001 (1)

Text

July 2, 2024 James Barstow Vice President, Nuclear Regulatory Affairs and Support Services Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801

SUBJECT:

WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 - ISSUANCE OF AMENDMENT NOS. 167 AND 73 REGARDING ADOPTION OF TECHNICAL SPECIFCATION TASK FORCE TRAVELER TSTF-427-A, REVISION 2 (EPID L-2024-LLA-0003)

Dear James Barstow:

The U.S. Nuclear Regulatory Commission (Commission) has issued the enclosed Amendment No. 167 to Facility Operating License No. NPF-90 and Amendment No. 73 to Facility Operating License No. NPF-96 for the Watts Bar Nuclear Plant, Units 1 and 2, respectively. These amendments are in response to your application dated January 9, 2024.

The amendments revise Watts Bar Nuclear Plant, Units 1 and 2, technical specifications requirements for unavailable barriers by adding Limiting Condition for Operation 3.0.9.

A copy of our related safety evaluation is also enclosed. Notice of issuance will be included in the Commissions Federal Register notice.

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. 50-390 and 50-391

Enclosures:

1. Amendment No. 167 to NPF-90

2. Amendment No. 73 to NPF-96

3. Safety Evaluation cc: Listserv

TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-390 WATTS BAR NUCLEAR PLANT, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 167 License No. NPF-90

1.

The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Tennessee Valley Authority (TVA, the licensee) dated January 9, 2024, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations 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 Commissions regulations; 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 Commissions regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Facility Operating License No. NPF-90 is hereby amended to read as follows:

(2)

Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 167 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3.

This license amendment is effective as of the date of its issuance, and shall be implemented within 120 days.

FOR THE NUCLEAR REGULATORY COMMISSION David Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Operating License and Technical Specifications Date of Issuance: July 2, 2024 DAVID WRONA Digitally signed by DAVID WRONA Date: 2024.07.02 14:21:30 -04'00'

ATTACHMENT TO AMENDMENT NO. 167 WATTS BAR NUCLEAR PLANT, UNIT 1 FACILITY OPERATING LICENSE NO. NPF-90 DOCKET NO. 50-390 Replace page 3 of Facility Operating License No. NPF-90 with the attached revised page 3. The revised page is identified by amendment number and contains a marginal line indicating the area of change.

Replace the following pages of the Appendix A, Technical Specifications, with the attached pages. The revised pages are identified by amendment number and contain marginal lines indicating the area of change.

Remove Pages Insert Pages 3.0-1 3.0-1 3.0-3 3.0-3 3.0-4 3.0-4 3.0-5 3.0-5 3.0-6

Facility License No. NPF-90 Amendment No. 167 (4)

TVA, 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, instrument calibration, or other activity associated with radioactive apparatus or components; and (5)

TVA, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

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 I 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 TVA is authorized to operate the facility at reactor core power levels not in excess of 3459 megawatts thermal.

(2)

Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 167 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

(3)

Safety Parameter Display System (SPDS) (Section 18.2 of SER Supplements 5 and 15)

Prior to startup following the first refueling outage, TVA shall accomplish the necessary activities, provide acceptable responses, and implement all proposed corrective actions related to having the Watts Bar Unit 1 SPDS operational.

(4)

Vehicle Bomb Control Program (Section 13.6.9 of SSER 20)

During the period of the exemption granted in paragraph 2.D.(3) of this license, in implementing the power ascension phase of the approved initial test program, TVA shall not exceed 50% power until the requirements of 10 CFR 73.55(c)(7) and (8) are fully implemented. TVA shall submit a letter under oath or affirmation when the requirements of 73.55(c)(7) and (8) have been fully implemented.

LCO Applicability 3.0 (continued)

Watts Bar-Unit 1 3.0-1 Amendment 55, 111, 167 3.0 LIMITING CONDITION FOR OPERATION (LCO) APPLICABILITY LCO 3.0.1 LCOs shall be met during the MODES or other specified conditions in the Applicability, except as provided in LCO 3.0.2, LCO 3.0.7, LCO 3.0.8, and LCO 3.0.9.

LCO 3.0.2 Upon discovery of a failure to meet an LCO, the Required Actions of the associated Conditions shall be met, except as provided in LCO 3.0.5 and LCO 3.0.6.

If the LCO is met or is no longer applicable prior to expiration of the specified Completion Time(s), completion of the Required Action(s) is not required unless otherwise stated.

LCO 3.0.3 When an LCO is not met and the associated ACTIONS are not met, an associated ACTION is not provided, or if directed by the associated ACTIONS the unit shall be placed in a MODE or other specified condition in which the LCO is not applicable. Action shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to place the unit, as applicable, in:

a.

MODE 3 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />; b.

MODE 4 within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />; and c.

MODE 5 within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />.

Exceptions to this Specification are stated in the individual Specifications.

Where corrective measures are completed that permit operation in accordance with the LCO or ACTIONS, completion of the actions required by LCO 3.0.3 is not required.

LCO 3.0.3 is only applicable in MODES 1, 2, 3, and 4.

LCO 3.0.4 When an LCO is not met, entry into a MODE or other specified condition in the Applicability shall only be made:

a.

When the associated ACTIONS to be entered permit continued operation in the MODE or other specified condition in the Applicability for an unlimited period of time;

LCO Applicability 3.0 Watts Bar-Unit 1 3.0-3 Amendment 111, 167 3.0 LCO APPLICABILITY LCO 3.0.6 When a support system's Required Action directs a supported system to be (continued) declared inoperable or directs entry into Conditions and Required Actions for a supported system, the applicable Conditions and Required Actions shall be entered in accordance with LCO 3.0.2.

LCO 3.0.7 Test Exception LCOs 3.1.9 and 3.1.10 allow specified Technical Specification (TS) requirements to be changed to permit performance of special tests and operations. Unless otherwise specified, all other TS requirements remain unchanged. Compliance with Test Exception LCOs is optional. When a Test Exception LCO is desired to be met but is not met, the ACTIONS of the Test Exception LCO shall be met. When a Test Exception LCO is not desired to be met, entry into a MODE or other specified condition in the Applicability shall be made in accordance with the other applicable Specifications.

LCO 3.0.8 When one or more required snubbers are unable to perform their associated support function(s), any affected supported LCO(s) are not required to be declared not met solely for this reason if risk is assessed and managed, and

a. the snubbers not able to perform their associated support function(s) are associated with only one train or subsystem of a multiple train or subsystem supported system or are associated with a single train or subsystem supported system and are able to perform their associated support function within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; or

b. the snubbers not able to perform their associated support function(s) are associated with more than one train or subsystem of a multiple train or subsystem supported system and are able to perform their associated support function within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

At the end of the specified period, the required snubbers must be able to perform their associated support function(s), or the affected supported system LCO(s) shall be declared not met.

LCO Applicability 3.0 Watts Bar-Unit 1 3.0-4 Amendment 167 3.0 LCO APPLICABILITY LCO 3.0.9 When one or more required barriers are unable to perform their related support function(s), any supported system LCO(s) are not required to be declared not met solely for this reason for up to 30 days provided that at least one train or subsystem of the supported system is OPERABLE and supported by barriers capable of providing their related support function(s), and risk is assessed and managed. This specification may be concurrently applied to more than one train or subsystem of a multiple train or subsystem supported system provided at least one train or subsystem of the supported system is OPERABLE and the barriers supporting each of these trains or subsystems provide their related support function(s) for different categories of initiating events.

If the required OPERABLE train or subsystem becomes inoperable while this specification is in use, it must be restored to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the provisions of this specification cannot be applied to the trains or subsystems supported by the barriers that cannot perform their related support function(s).

At the end of the specified period, the required barriers must be able to perform their related support function(s) or the supported system LCO(s) shall be declared not met.

SR Applicability 3.0 Watts Bar-Unit 1 3.0-5 (continued)

Amendment 42, 114, 121, 135, 158, 167 3.0 SURVEILLANCE REQUIREMENT (SR) APPLICABILITY SR 3.0.1 SRs shall be met during the MODES or other specified conditions in the Applicability for individual LCOs, unless otherwise stated in the SR. Failure to meet a Surveillance, whether such failure is experienced during the performance of the Surveillance or between performances of the Surveillance, shall be failure to meet the LCO. Failure to perform a Surveillance within the specified Frequency shall be failure to meet the LCO except as provided in SR 3.0.3.

Surveillances do not have to be performed on inoperable equipment or variables outside specified limits.

SR 3.0.2 The specified Frequency for each SR is met if the Surveillance is performed within 1.25 times the interval specified in the Frequency, as measured from the previous performance or as measured from the time a specified condition of the Frequency is met.

For Frequencies specified as "once," the above interval extension does not apply.

If a Completion Time requires periodic performance on a "once per..." basis, the above Frequency extension applies to each performance after the initial performance.

Exceptions to this Specification are stated in the individual Specifications.

SR 3.0.3 If it is discovered that a Surveillance was not performed within its specified Frequency, then compliance with the requirement to declare the LCO not met may be delayed, from the time of discovery, up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or up to the limit of the specified Frequency, whichever is greater. This delay period is permitted to allow performance of the Surveillance. The delay period is only applicable when there is a reasonable expectation the surveillance will be met when performed. A risk evaluation shall be performed for any Surveillance delayed greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and the risk impact shall be managed.

If the Surveillance is not performed within the delay period, the LCO must immediately be declared not met, and the applicable Condition(s) must be entered.

When the Surveillance is performed within the delay period and the Surveillance is not met, the LCO must immediately be declared not met, and the applicable Condition(s) must be entered.

SR Applicability 3.0 Watts Bar-Unit 1 3.0-6 Amendment 55, 135, 167 3.0 SR APPLICABILITY SR 3.0.4 Entry into a MODE or other specified condition in the Applicability of an LCO shall only be made when the LCO's Surveillances have been met within their specified Frequency, except as provided by SR 3.0.3. When an LCO is not met due to Surveillances not having been met, entry into a MODE or other specified condition in the Applicability shall only be made in accordance with LCO 3.0.4.

This provision shall not prevent entry into MODES or other specified conditions in the Applicability that are required to comply with ACTIONS or that are part of a shutdown of the unit.

TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-391 WATTS BAR NUCLEAR PLANT, UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 73 License No. NPF-96 1.

The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Tennessee Valley Authority (TVA, the licensee) dated January 9, 2024, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations 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 Commissions regulations; 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 Commissions regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Facility Operating License No. NPF-96 is hereby amended to read as follows:

(2)

Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 73 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3.

This license amendment is effective as of the date of its issuance, and shall be implemented within 120 days.

FOR THE NUCLEAR REGULATORY COMMISSION David Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Operating License and Technical Specifications Date of Issuance: July 2, 2024 DAVID WRONA Digitally signed by DAVID WRONA Date: 2024.07.02 14:21:56 -04'00'

ATTACHMENT TO AMENDMENT NO. 73 WATTS BAR NUCLEAR PLANT, UNIT 2 FACILITY OPERATING LICENSE NO. NPF-96 DOCKET NO. 50-391 Replace page 3 of Facility Operating License No. NPF-96 with the attached revised page 3. The revised page is identified by amendment number and contains a marginal line indicating the area of change.

Replace the following pages of the Appendix A, Technical Specifications, with the attached pages. The revised pages are identified by amendment number and contain marginal lines indicating the area of change.

Remove Pages Insert Pages 3.0-1 3.0-1 3.0-3 3.0-3 3.0-4 3.0-4 3.0-5 3.0-5 3.0-6 Unit 2 Facility Operating License No. NPF-96 Amendment No. 73 C.

The license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I 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 TVA is authorized to operate the facility at reactor core power levels not in excess of 3459 megawatts thermal.

(2)

Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 73 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

(3)

TVA shall implement permanent modifications to prevent overtopping of the embankments of the Fort Loudon Dam due to the Probable Maximum Flood by June 30, 2018.

(4)

FULL SPECTRUM LOCA Methodology shall be implemented when the WBN Unit 2 steam generators are replaced with steam generators equivalent to the existing steam generators at WBN Unit 1.

(5)

By December 31, 2019, the licensee shall report to the NRC that the actions to resolve the issues identified in Bulletin 2012-01, Design Vulnerability in Electrical Power System, have been implemented.

(6)

The licensee shall maintain in effect the provisions of the physical security plan, security personnel training and qualification plan, and safeguards contingency plan, and all amendments made pursuant to the authority of 10 CFR 50.90 and 50.54(p).

(7)

TVA shall fully implement and maintain in effect all provisions of the Commission approved cyber security plan (CSP), including changes made pursuant to the authority of 10 CFR 50.90 and 10 CFR 50.54(p).

The TVA approved CSP was discussed in NUREG-0847, Supplement 28, as amended by changes approved in License Amendment No. 7.

(8)

TVA shall implement and maintain in effect all provisions of the approved fire protection program as described in the Fire Protection Report for the facility, as described in NUREG-0847, Supplement 29, subject to the following provision:

LCO Applicability 3.0 (continued)

Watts Bar - Unit 2 3.0-1 Amendment 6, 73 3.0 LIMITING CONDITION FOR OPERATION (LCO) APPLICABILITY LCO 3.0.1 LCOs shall be met during the MODES or other specified conditions in the Applicability, except as provided in LCO 3.0.2, 3.0.7, 3.0.8, and 3.0.9.

LCO 3.0.2 Upon discovery of a failure to meet an LCO, the Required Actions of the associated Conditions shall be met, except as provided in LCO 3.0.5 and LCO 3.0.6.

If the LCO is met or is no longer applicable prior to expiration of the specified Completion Time(s), completion of the Required Action(s) is not required unless otherwise stated.

LCO 3.0.3 When an LCO is not met and the associated ACTIONS are not met, an associated ACTION is not provided, or if directed by the associated ACTIONS the unit shall be placed in a MODE or other specified condition in which the LCO is not applicable. Action shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to place the unit, as applicable, in:

a.

MODE 3 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />; b.

MODE 4 within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />; and c.

MODE 5 within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />.

Exceptions to this Specification are stated in the individual Specifications.

Where corrective measures are completed that permit operation in accordance with the LCO or ACTIONS, completion of the actions required by LCO 3.0.3 is not required.

LCO 3.0.3 is only applicable in MODES 1, 2, 3, and 4.

LCO 3.0.4 When an LCO is not met, entry into a MODE or other specified condition in the Applicability shall only be made:

a.

When the associated ACTIONS to be entered permit continued operation in the MODE or other specified condition in the Applicability for an unlimited period of time;

LCO Applicability 3.0 3.0 LCO APPLICABILITY Watts Bar - Unit 2 3.0-3 Amendment 6, 73 LCO 3.0.7 Test Exception LCO 3.1.9 allows specified Technical Specification (TS) requirements to be changed to permit performance of special tests and operations. Unless otherwise specified, all other TS requirements remain unchanged. Compliance with Test Exception LCOs is optional. When a Test Exception LCO is desired to be met but is not met, the ACTIONS of the Test Exception LCO shall be met. When a Test Exception LCO is not desired to be met, entry into a MODE or other specified condition in the Applicability shall be made in accordance with the other applicable Specifications.

LCO 3.0.8 When one or more required snubbers are unable to perform their associated support function(s), any affected supported LCO(s) are not required to be declared not met solely for this reason if risk is assessed and managed, and

a. the snubbers not able to perform their associated support function(s) are associated with only one train or subsystem of a multiple train or subsystem supported system or are associated with a single train or subsystem supported system and are able to perform their associated support function within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; or

b. the snubbers not able to perform their associated support function(s) are associated with more than one train or subsystem of a multiple train or subsystem supported system and are able to perform their associated support function within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

At the end of the specified period, the required snubbers must be able to perform their associated support function(s), or the affected supported system LCO(s) shall be declared not met.

LCO Applicability 3.0 3.0 LCO APPLICABILITY Watts Bar - Unit 2 3.0-4 Amendment 73 LCO 3.0.9 When one or more required barriers are unable to perform their related support function(s), any supported system LCO(s) are not required to be declared not met solely for this reason for up to 30 days provided that at least one train or subsystem of the supported system is OPERABLE and supported by barriers capable of providing their related support function(s), and risk is assessed and managed. This specification may be concurrently applied to more than one train or subsystem of a multiple train or subsystem supported system provided at least one train or subsystem of the supported system is OPERABLE and the barriers supporting each of these trains or subsystems provide their related support function(s) for different categories of initiating events.

If the required OPERABLE train or subsystem becomes inoperable while this specification is in use, it must be restored to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the provisions of this specification cannot be applied to the trains or subsystems supported by the barriers that cannot perform their related support function(s).

At the end of the specified period, the required barriers must be able to perform their related support function(s) or the supported system LCO(s) shall be declared not met.

SR Applicability 3.0 Watts Bar - Unit 2 3.0-5 3.0 SURVEILLANCE REQUIREMENT (SR) APPLICABILITY SR 3.0.1 SRs shall be met during the MODES or other specified conditions in the Applicability for individual LCOs, unless otherwise stated in the SR.

Failure to meet a Surveillance, whether such failure is experienced during the performance of the Surveillance or between performances of the Surveillance, shall be failure to meet the LCO. Failure to perform a Surveillance within the specified Frequency shall be failure to meet the LCO except as provided in SR 3.0.3. Surveillances do not have to be performed on inoperable equipment or variables outside specified limits.

SR 3.0.2 The specified Frequency for each SR is met if the Surveillance is performed within 1.25 times the interval specified in the Frequency, as measured from the previous performance or as measured from the time a specified condition of the Frequency is met.

For Frequencies specified as "once," the above interval extension does not apply.

If a Completion Time requires periodic performance on a "once per..."

basis, the above Frequency extension applies to each performance after the initial performance.

Exceptions to this Specification are stated in the individual Specifications.

SR 3.0.3 If it is discovered that a Surveillance was not performed within its specified Frequency, then compliance with the requirement to declare the LCO not met may be delayed, from the time of discovery, up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or up to the limit of the specified Frequency, whichever is greater. This delay period is permitted to allow performance of the Surveillance. The delay period is only applicable when there is a reasonable expectation the surveillance will be met when performed. A risk evaluation shall be performed for any Surveillance delayed greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and the risk impact shall be managed.

If the Surveillance is not performed within the delay period, the LCO must immediately be declared not met, and the applicable Condition(s) must be entered.

When the Surveillance is performed within the delay period and the Surveillance is not met, the LCO must immediately be declared not met, and the applicable Condition(s) must be entered.

(continued)

Amendment 3, 12, 39, 66, 73

SR Applicability 3.0 Watts Bar - Unit 2 3.0-6 Amendment 3, 39, 73 3.0 SR APPLICABILITY SR 3.0.4 Entry into a MODE or other specified condition in the Applicability of an LCO shall only be made when the LCO's Surveillances have been met within their specified Frequency, except as provided by SR 3.0.3. When an LCO is not met due to Surveillances not having been met, entry into a MODE or other specified condition in the Applicability shall only be made in accordance with LCO 3.0.4.

This provision shall not prevent entry into MODES or other specified conditions in the Applicability that are required to comply with ACTIONS or that are part of a shutdown of the unit.

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 167 AND 73 TO FACILITY OPERATING LICENSE NOS. NPF-90 AND NPF-96 TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-390 AND 50-391

1.0 INTRODUCTION

By application dated January 9, 2024 (Agencywide Documents Access Management System (ADAMS) Accession No. ML24009A170), the Tennessee Valley Authority (TVA, the licensee),

submitted a license amendment request (LAR) for changes to the Watts Bar Nuclear Plant (Watts Bar), Units 1 and 2, Technical Specifications (TSs). The proposed amendments would revise Watts Bar, Units 1 and 2, TS requirements related to the unavailability of barriers in the TSs by adding a new limiting condition for operation (LCO). The proposed changes are based on Technical Specifications Task Force (TSTF) traveler TSTF-427, Allowance for Non Technical Specification Barrier Degradation on Supported System OPERABILITY, Revision 2, dated May 3, 2006 (ML061240055).

2.0 REGULATORY EVALUATION

2.1 Background

The standard technical specifications (STS) (NUREG-1431, Standard Technical Specifications:

Westinghouse Plants, Revision 5.0, Volume 1, September 30, 2021 (ML21259A155)), provide guidance on the format and content of TSs for each of the light-water reactor nuclear steam supply systems. The current version of the STS incorporates the changes to the STS proposed in TSTF-427, Revision 2. The NRC staff published a notice of availability of the model safety evaluation (SE) and model application for TSTF-427, Revision 2, in the Federal Register on October 3, 2006 (71 FR 58444), as part of the Consolidated Line Item Improvement Process. In its application, the TVA stated that the justifications presented in TSTF-427 and the model SE are applicable to its facilities and justify the proposed TS changes.

The TSTF-427 was developed as one of the industrys initiatives under the risk-informed TSs program. These initiatives are intended to maintain or improve safety through the incorporation of risk assessment and management techniques in TSs, while reducing unnecessary burden and making TS requirements consistent with the Commissions other risk-informed regulatory requirements.

LCOs specify minimum requirements for ensuring safe operation of the facility. When an LCO is not met, the licensee must shut down the reactor or follow any remedial actions permitted by the TSs (identified as required actions in the TSs) until the LCO can be met. The TSTF-427, Revision 2, proposed to add LCO 3.0.9 to the STS to allow a licensee to delay declaring an LCO not met, when the system inoperability is due solely to an unavailable barrier if risk is assessed and managed. The full text of LCO 3.0.9 is included in Section 2.2 of this SE. The Nuclear Energy Institute (NEI) also provided industry guidance for implementing TSTF-427 in NEI 04-08, Risk-Informed Technical Specifications Initiative 7a: Allowance for Non-Technical Specification Barrier Degradation on Supported System OPERABILITY (TSTF-427), Industry Implementation Guidance, March 2006 (ML061220426).

The postulated initiating events which may require a functional barrier are limited to those with low frequencies of occurrence, and the overall TS system safety function would still be available for most anticipated challenges. Barriers are doors, walls, floor plugs, curbs, hatches, installed structures or components, or other devices, not explicitly described in the TSs, that support the performance of the functions of systems described in the TSs. For purposes of LCO 3.0.9, the term barrier refers to one or more devices which protect one train of a safety system from a given initiating event. A degraded barrier refers to a barrier that has been found to be degraded and must be repaired, or to a barrier that is purposefully removed or reconfigured to facilitate maintenance activities. LCO 3.0.9 does not apply to fire barriers, snubbers, barriers which support ventilation systems, barriers for systems not required by TSs, or barriers which support TS systems where the unavailability of the barrier does not render the supported system inoperable.

Some systems may require one or more functional barriers to perform their intended safety functions for certain initiating events. For example, there are barriers to protect systems from the effects of internal flooding (e.g., floor plugs and retaining walls); barriers to protect equipment from steam impingement in case of high energy line breaks; and barriers to protect systems against missiles generated internally or externally.

Barriers are not explicitly described in the TSs, but the definition of operability in the TSs requires barriers to be capable of performing their support function for systems included in the TSs. Therefore, under the current TSs, the supported system must be declared inoperable when related barriers are unavailable. However, the risk associated with an unavailable barrier is much less than the risk associated with the direct unavailability of the supported system, because barriers are only required for specific, low-frequency initiating events.

Some potential undesirable consequences of the current TS requirements include:

1. A reduced ability to complete maintenance activities on supported systems within the completion time for TS required actions due to the time needed to remove and restore barriers;

2. Prioritizing the restoration of barriers following maintenance when other activities may have a greater risk impact; and

3. Unnecessary plant shutdowns due to degraded barriers that cannot be repaired within the timeframe required for restoring a supported system to operable status.

To improve the treatment of unavailable barriers and enhance safety, the TSTF proposed a risk-informed change to the STS that introduced a delay time before declaring the LCO for the supported system not met when there are one or more degraded barriers if risk is assessed and managed. Such a delay time will provide flexibility for performing maintenance and enhance overall plant safety by:

1. Providing more time for the safe conduct of maintenance and testing activities on the supported barrier since removal and restoration can be performed on a separate timeframe,

2. Allowing barrier removal and restoration activities to be assessed and prioritized based on actual plant risk impacts; and

3. Avoiding unnecessary plant shutdowns, which decreases plant transition and realignment risks.

2.2 Description of Proposed Changes The STS LCO 3.0.9 states:

When one or more required barriers are unable to perform their related support function(s), any supported system LCO(s) are not required to be declared not met solely for this reason for up to 30 days provided that at least one train or subsystem of the supported system is OPERABLE and supported by barriers capable of providing their related support function(s), and risk is assessed and managed. This specification may be concurrently applied to more than one train or subsystem of a multiple train or subsystem supported system provided at least one train or subsystem of the supported system is OPERABLE and the barriers supporting each of these trains or subsystems provide their related support function(s) for different categories of initiating events.

If the required OPERABLE train or subsystem becomes inoperable while this specification is in use, it must be restored to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the provisions of this specification cannot be applied to the trains or subsystems supported by the barriers that cannot perform their related support function(s).

At the end of the specified period, the required barriers must be able to perform their related support function(s) or the supported system LCO(s) shall be declared not met.

TVAs proposed addition of a new LCO 3.0.9 to the Watts Bar TSs for each of its units is consistent with STS LCO 3.0.9 and TSTF-427, Revision 2.

STS LCO 3.0.1 for each facility states that LCOs shall be met during the modes or other specified conditions in the applicability, except as provided in specific LCOs included in TS Section 3.0. Consistent with TSTF-427, Revision 2, TVA proposed to add LCO 3.0.9 to the list of exceptions included in LCO 3.0.1 for Watts Bar TSs for each of its units as follows (the proposed changes are shown in bold text):

LCO 3.0.1 LCOs shall be met during the MODES or other specified conditions in the Applicability, except as provided in LCO 3.0.2, LCO 3.0.7, and LCO 3.0.8, and LCO 3.0.9.

2.3 Regulatory Requirements Title 10 of the Code of Federal Regulations (10 CFR) 50.36, Technical specifications, establishes the regulatory requirements related to the content of TSs. Section 50.36(a)(1) requires an application for an operating license to include proposed TSs. A summary statement of the bases or reasons for such specifications, other than those covering administrative controls, shall also be included in the application, but shall not become part of the TSs.

Pursuant to 10 CFR 50.36, TSs for operating reactors are required to include items in the following five specific categories: (1) safety limits, limiting safety system settings, and limiting control settings; (2) LCOs; (3) surveillance requirements; (4) design features; and (5) administrative controls. In accordance with 10 CFR 50.36(c)(2), LCOs are the lowest functional capability or performance level of equipment required for safe operation of the facility.

When LCOs are not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the LCO can be met. For each of the Watts Bar facilities, TS Section 3.0 provides details or ground rules for complying with the LCOs.

3.0 TECHNICAL EVALUATION

The industry submitted TSTF-427, Revision 2, in support of the proposed TS change, which documents a risk-informed analysis of the proposed TS change. Probabilistic risk assessment (PRA) methods are used, in combination with deterministic and defense-in-depth arguments, to identify and justify delay times for entering the actions for the supported equipment associated with unavailable barriers at nuclear power plants. The industry also submitted NEI 04-08 which provides detailed guidance on assessing and managing risk associated with unavailable barriers. This is in accordance with guidance provided in Regulatory Guide (RG) 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, dated July 1998 (ML003740133), and RG 1.177, An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications, dated August 1998 (ML003740176).

The risk impact associated with the proposed delay times for entering the TS actions for the supported equipment can be assessed using the same approach as for allowed Completion Time (CT) extensions. Therefore, the risk assessment was performed following the three-tiered approach recommended in RG 1.177 for evaluating proposed extensions in currently allowed CTs:

1. The first tier involves the assessment of the change in plant risk due to the proposed TS change, as expressed by the change in core damage frequency (CDF), the change in large early release frequency (LERF), the incremental conditional core damage probability (ICCDP), and the incremental conditional large early release probability (ICLERP). The assessed CDF and LERF values are compared to acceptance guidelines, consistent with the Commissions Safety Goal Policy Statement, as documented in RG 1.174, so that the plants baseline risk is maintained within a minimal range. The assessed ICCDP and ICLERP values are compared to acceptance guidelines in RG 1.177, which provide assurance that the plant risk does not increase unacceptably during the period the equipment is taken out of service.

2. The second tier involves the identification of potentially high-risk configurations that could exist if equipment, in addition to that associated with the change, were to be taken out of service simultaneously, or other risk-significant operational factors such as concurrent equipment testing were also involved. The objective is to ensure that appropriate restrictions are in place to avoid any potential high-risk configurations.

3. The third tier involves the establishment of an overall Configuration Risk Management Program (CRMP) to ensure that potentially risk-significant configurations resulting from maintenance and other operational activities are identified. The objective of the CRMP is to manage configuration-specific risk by appropriate scheduling of plant activities and/or appropriate compensatory measures.

In TSTF-427, a simplified risk assessment was performed to justify the proposed addition of LCO 3.0.9 to the TSs. This approach was necessitated by (1) the general nature of the proposed TS change (i.e., it applies to all plants and is associated with an undetermined number of barriers that are not able to perform their function), and (2) the lack of detailed modeling in most plant-specific PRAs which do not include passive structures such as barriers.

The simplified risk assessment considers three different parameters:

1. The length of time the affected barrier is unavailable,

2. The initiating event frequency for which the affected barrier is designed to mitigate, and

3. The importance to CDF (or LERF) of the TS equipment (train, subsystem, or component) for which the affected barrier is designed to protect, measured by the Risk Achievement Worth (RAW) of the equipment.

The ICCDP can be calculated based on the following equation:

ICCDP T

IE IE RAW CDF CDF C

i T

j base base

8766 Where:

Tc is the time the barrier is unavailable (hours)

Tc/8766 is therefore the fraction of the year during which the barrier is unavailable, IEi/IET is the ratio of the initiating event frequency for which the affected barrier is designed to mitigate, IEi, and the total initiating event frequency, IET, RAWj is the risk achievement worth of the component(s) for which the barrier provides protection, and CDFbase is the baseline CDF (per year).

ICLERP also may be similarly determined, using baseline LERF and RAW values with respect to LERF. It is assumed that the magnitude of the LERF risk resulting from the barrier unable to perform its related support function would be generally at least one order of magnitude less than the corresponding CDF. Containment bypass scenarios, which are typically the significant contributors to LERF, would not be uniquely affected by application of LCO 3.0.9, and initiating events which would be significant LERF contributors, such as steam generator tube rupture and interfacing systems loss-of-coolant accident (LOCA), are not typically associated with barriers within the scope of LCO 3.0.9. Therefore, the assumption regarding LERF risk is reasonable and acceptable for the generic risk evaluation, provided that LERF risk impacts are considered on a plant-specific basis for unavailable barriers, as described in Section 3.1.3 of this SE.

The relevant initiating events (i.e., events for which barriers subject to LCO 3.0.9 provide protection) are: internal and external floods, high-energy line breaks, feedwater line breaks, LOCAs (small, medium, and large), tornados and high winds, and turbine missiles. Generic frequencies for most of these initiating events were obtained from NUREG/CR-5750, Rates of Initiating Events at U.S. Nuclear Power Plants: 1987 - 1995, February 1999 (ML070580080).

For external floods, turbine missiles, and tornados, other industry source documents were referenced. The most limiting (highest frequency) initiating event was obtained for a high-energy line break from NUREG/CR-5750, with a frequency of 9.1E-3 per year. The risk assessment is, therefore, based on this limiting frequency, and the proposed methodology to apply LCO 3.0.9 is similarly restricted to barriers protecting against initiating events whose total frequency is no more than 9.1E-3 per year.

In its LAR, the licensee stated that the initiating event frequencies from the TSTF-427 generic analysis do not, in all cases, bound the Watts Bar PRA initiating event frequencies. However, after conducting a plant-specific risk analysis in accordance with RG 1.174, the licensee confirmed that the risk assessment for Watts Bar, specifically for a 30-day barrier unavailability scenario, falls within the very low risk category of RG 1.174. Consequently, the risk conclusions given in the TSTF-427 generic analysis are considered applicable.

For the reasons outlined below, the NRC staff concludes that the TSTF-427 generic analysis is appropriate and applicable for application to Watts Bar: (1) the licensees plant-specific risk analysis demonstrated that the risk associated with barrier unavailability aligns with the risk acceptance guidelines of RG 1.174 and falls within the very low risk category; (2) per RG 1.177 and TSTF-427, Revision 2, the very low risk associated with barrier unavailability results in a calculated CT for normal work controls (i.e., ICCDP < 10-6 and ICLERP < 10-7 in TSTF-427, Revision 2) that significantly exceeds the 30-day backstop allowed CT; and (3) the LAR included regulatory commitments in section 3.2, Verification and Commitments, that when LCO 3.0.9 is applied, the licensee will assess and manage risk, and determine the allowed CT (not to exceed the 30-day backstop) using plant-specific configurations as per NEI 04-08 and the requirements of paragraph (a)(4) of the Maintenance Rule (10 CFR 50.65).

3.1 Risk Assessment Results and Insights The results and insights from the implementation of the three-tiered approach of RG 1.177 to support the proposed addition of LCO 3.0.9 to the TS are summarized and evaluated in the following Sections 3.1.1 to 3.1.3.

3.1.1 Risk Impact The bounding risk assessment approach, described in Section 3.0 was developed for a range of plant baseline CDF values and for a range of protected component RAW values. The maximum allowable 30-day outage time was used. The results are summarized (from TSTF-427, Revision

2) in Table 1 below:

Table 1: Risk Assessment Results for a Postulated 30-Day Barrier Outage.

Baseline CDF = 10-6 Baseline CDF = 10-5 Baseline CDF = 10-4 RAW ICCDP ICLERP ICCDP ICLERP ICCDP ICLERP 2

7.5 x 10-10 7.5 x 10-11 7.5 x 10-9 7.5 x 10-10 7.5 x 10-8 7.5 x 10-9 10 6.7 x 10-9 6.7 x 10-10 6.7 x 10-8 6.7 x 10-9 6.7 x 10-7 6.7 x 10-8 50 3.7 x 10-8 3.7 x 10-9 3.7 x 10-7 3.7 x 10-8 3.7 x 10-6 3.7 x 10-7 100 7.4 x 10-8 7.4 x 10-9 7.4 x 10-7 7.4 x 10-8 7.4 x 10-6 7.4 x 10-7 The above results represent a sensitivity analysis covering the expected range of plant baseline CDF values and component RAW values. The most limiting configurations involving very high-risk components (RAW > 10) would not be anticipated to occur for most planned maintenance activities.

The calculations conservatively assume the most limiting (highest frequency) initiating event and the longest allowable outage time (30 days). Occurrence of the initiating event during unavailability of the barrier is conservatively assumed to directly fail the protected equipment; no credit is taken for event-specific circumstances which may result in the equipment remaining functional even with the barrier unavailable. For example, a barrier required to protect equipment from steam impingement for high energy line breaks may only be required for breaks occurring in specific locations and orientations relative to the protected equipment, and only for large size breaks. No credit is taken for avoided risk identified in Section 2.1.

The risk assessment results of Table 2 were compared to NRC-endorsed guidance, that is now in Section 11 of NUMARC 93-01, Revision 4F, April 2018 (ML18120A069), for implementing the requirements of paragraph (a)(4) of the Maintenance Rule (10 CFR 50.65). This guidance is summarized in Table 2 below. Guidance regarding the acceptability of conditional risk increase in terms of CDF (i.e., RCDF) for a planned configuration is provided. The NUMARC 93-01 guidance states that a specific configuration that is associated with a CDF higher than 10-3 per year should be carefully considered before entering voluntarily. The NRC staff notes that the higher risk configurations documented in Table 2 would exceed this value. For example, with a baseline CDF of 10-4 per year, a component with a RAW greater than 10 would exceed the 10-3 per year criteria. Therefore, the sensitivity analyses presented in Table 2 are understood to include higher risk configurations which should be carefully considered before entering voluntarily per the NUMARC 93-01 guidance.

Table 2: Guidance for Implementing 10 CFR 50.65(a)(4)

RCDF Guidance Greater than 1E-3/year Configuration should not normally be entered voluntarily ICCDP Guidance ICLERP Greater than 1E-5 Configuration should not normally be entered voluntarily Greater than 1E-6 1E-6 to 1E-5 Assess non-quantifiable factors Establish risk management actions 1E-7 to 1E-6 Less than 1E-6 Normal work controls Less than1E-7 Guidance regarding the acceptability of ICCDP and ICLERP values for a specific planned configuration and the establishment of risk management actions is also provided in NUMARC 93-01. This guidance, as shown in Table 2, states that a specific plant configuration that is associated with ICCDP and ICLERP values below 1E-6 and 1E-7, respectively, is considered to require normal work controls. Table 2 shows that for the majority of barrier outage configurations, the conservatively assessed ICCDP and ICLERP values are within the limits for what is recommended as the threshold for the normal work controls region.

As stated in the implementation guidance in NEI 04-08 for LCO 3.0.9, plants are required to commit to the guidance of NUMARC 93-01 Section 11 to adopt TSTF-427, therefore the above limits would be applicable. Plant configurations including out of service barriers may, therefore, be entered voluntarily if supported by the results of the risk assessment required by 10 CFR 50.65(a)(4), and LCO 3.0.9.

RG 1.177 provides risk acceptance guidelines for evaluating changes to TS allowed outage times. The first acceptance guideline is that it has been demonstrated that the change in TS allowed outage time has only a small quantitative impact on plant risk. For this purpose, an ICCDP of less than 5.0x10-7 is considered small for a single TS allowed outage time change and an ICLERP of less than 5.0x10-8 is also considered small. As shown in Table 1, these guidelines are met for the typically anticipated configurations, unless either the baseline CDF for the plant approaches 10-4 per year or the RAW of the protected components is well above 10.

Such configurations may exceed the criteria described in Table 2 and would not be voluntarily entered. Such configurations are not expected to be frequently encountered and may be addressed on a case-by-case plant-specific basis by limiting the allowed outage time and by implementing plant-specific risk management actions, as per the implementing guidance in NEI 04-08.

RG 1.174 provides acceptance guidelines for risk-informed applications. If an application clearly shows a decrease in CDF and LERF, then the change in risk is acceptable. If the change results in an increase in CDF of less than 10-6 per year and an increase in LERF of less than 10-7 per year, then the change will be considered regardless of whether there is a calculation of the total CDF and LERF. If the increase in CDF is in the range of 10-6 per year to 10-5 per year and the increase in LERF is in the range of 10-7 per year to 10-6 per year, the application will be considered only if it can be reasonably shown that the total CDF is less than 10-4 per year and the total LERF is less than 10-5 per year. Applications that result in an increase in CDF greater than 10-5 per year or an increase in LERF greater than 10-6 per year would not normally be considered. The ICCDP calculations demonstrated that each individual 30-day barrier outage is anticipated to be low risk. Although there is no explicit limit on the number of times per year that LCO 3.0.9 may be applied, even assuming barrier outages occurred continuously over the entire year, the risk incurred would still be anticipated to within acceptable limits based on the guidance in RG 1.174.

The NRC staff finds that the risk assessment results support the proposed addition of LCO 3.0.9 to the TSs for Watts Bar. The risk increases associated with this TS change will be insignificant based on guidance provided in RG 1.174 and RG 1.177 and within the range of risks associated with normal maintenance activities.

3.1.2 Identification of High-Risk Configurations The second tier of the three-tiered approach recommended in RG 1.177 involves the identification of potentially high-risk configurations that could exist if equipment, in addition to that associated with the TS change, were to be taken out of service simultaneously. Insights from the risk assessments, in conjunction with important assumptions made in the analysis and defense-in-depth considerations, were used to identify such configurations. To avoid these potentially high-risk configurations, specific restrictions to the implementation of the proposed TS changes were identified.

When the proposed LCO 3.0.9 is applied, at least one train or subsystem is required to be operable with required barriers in place, such that this train or subsystem would be available to provide mitigation of the initiating event. The proposed LCO 3.0.9 may be applied to multiple trains of the same system only for barriers which provide protection for different initiating events, such that at least one train or subsystem is available to provide mitigation of the initiating event.

The use of LCO 3.0.9 for barriers which protect all trains or subsystems from a particular initiating event is not permitted. Therefore, potentially high-risk configurations involving a loss of function required for mitigation of a particular initiating event are avoided by the restrictions imposed on applicability of LCO 3.0.9.

LCO 3.0.9 also addresses potential emergent conditions where unplanned failures or discovered conditions may result in the unavailability of a required train or subsystem for a particular initiating event. Such conditions may result during application of LCO 3.0.9 from equipment failure on the operable train, such that all trains of a TS system are not protected from the same initiating event. In such cases, a 24-hour allowed time is provided to restore the conditions to permit continued operation with unavailable barriers, after which the applicability of LCO 3.0.9 ends, and the supported system LCO becomes effective. This allowed time is provided so that emergent conditions with low-risk consequences may be effectively managed, rather than requiring immediate exit of LCO 3.0.9 and the potential for an unplanned plant shutdown.

A limit of 30 days is applied to the LCO 3.0.9 allowed outage time for each barrier, after which the barrier must be restored to an available status, or the supported system TS must be applied.

This 30-day backstop applies regardless of the risk level calculated and provides assurance that installed plant barriers will be maintained available over long periods of time, and that the application of LCO 3.0.9 will not result in long-term degradation of plant barriers.

The NRC staff concludes that the restrictions on the applicability of LCO 3.0.9 assuring that one safety train remains available to mitigate the initiating event, along with the 30-day limit applicable to each barrier, assure that potentially high-risk configurations are avoided in accordance with the guidance provided in RGs 1.174 and 1.177.

3.1.3 Configuration Risk Management The third tier of the three-tiered approach recommended in RG 1.177 involves the establishment of an overall CRMP to ensure that potentially risk-significant configurations resulting from maintenance and other operational activities are identified. The objective of the CRMP is to manage configuration-specific risk by appropriate scheduling of plant activities and/or appropriate compensatory measures. This objective is met by licensee programs to comply with the requirements of paragraph (a)(4) of the Maintenance Rule (10 CFR 50.65) to assess and manage risk resulting from maintenance activities, and by LCO 3.0.9 requiring risk assessments and management using (a)(4) processes if no maintenance is in progress. These programs can support licensee decision making regarding the appropriate actions to manage risk whenever a risk-informed TS is entered.

The implementation guidance for LCO 3.0.9 (NEI 04-08) requires that the allowed outage time determination for an unavailable barrier be performed using the plant-specific configuration.

Further, the risk determinations are to be updated whenever emergent conditions occur. These requirements assure that the configuration-specific risk associated with unavailable barriers is assessed and managed prior to entry into LCO 3.0.9 and during its applicability as conditions change.

These evaluations for the unavailable barrier are performed as part of the assessment of plant risk required by 10 CFR 50.65(a)(4). The numerical guidance identified in Table 2 is applicable to implementation of LCO 3.0.9, using the results of the configuration-specific risk assessment which addresses the risk impact of the unavailable barrier along with all other out of service components and plant alignments.

Risk management actions are required to be considered when the calculated risk exceeds specific thresholds per NUMARC 93-01, Section 11, as identified in Table 2. Additional guidance on risk management actions is provided in the implementation guidance for LCO 3.0.9.

The allowed outage time for a barrier is calculated based on an ICCDP limit of 10-6. This is the NUMARC 93-01, Section 11, guidance for applicability of normal work controls and is conservatively lower than the guidance of 10-5 for voluntary maintenance activities. The use of 10-6 will result in conservatively short allowed outage times for barriers compared to allowed times for other maintenance activities.

If the scope of the PRA model used to support the plant-specific CRMP does not include the initiating event for which a barrier provides protection, then LCO 3.0.9 applicability is limited to one barrier on a single train. Multiple barriers for such initiating events may not be unavailable under LCO 3.0.9, and in such situations the LCO(s) associated with the protected components would be applicable. Applicability of LCO 3.0.9 to the single barrier for an initiating event that is not modeled in the plant PRA is acceptable based on the generic risk analysis provided by TSTF-427, as described in Section 3.1.1 of this SE.

Assessment of the LERF risk impact on an unavailable barrier is required to be performed in accordance with NUMARC 93-01, Section 11. If an unavailable barrier provides protection to equipment which is relevant to the containment function, or which protects equipment from the effects of an initiating event which is a contributor to LERF, then applicability of LCO 3.0.9 must be limited to that one barrier unless a quantified assessment of LERF is performed.

The NRC staff concludes that the risk evaluations necessary to support the applicability of LCO 3.0.9 appropriately consider the risk from unavailable barriers in an integrated manner based on the overall plant configuration. Therefore, potentially high-risk configurations can be identified and managed in accordance with the guidance provided in RGs 1.174 and 1.177.

3.2 Optional Changes and Variations The licensee did not propose any variations or deviations from the TS changes described in TSTF-427, Revision 2, or the NRC staffs model safety evaluation dated October 3, 2006.

The licensee noted that the LCO 3.0.9 Bases in TSTF-427 indicate that risk assessments will be conducted using the procedures and guidance endorsed by RG 1.182, Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants. However, in the Federal Register dated November 27, 2012 (77 FR 70846), the NRC provided notice that RG 1.182 had been withdrawn and the subject matter had been incorporated into RG 1.160, Monitoring the Effectiveness of Maintenance at Nuclear Power Plants. The TSTF issued a letter dated September 16, 2014 (ML14259A575), noting which approved TSTF travelers are affected and described the effect of withdrawal of RG 1.182. By letter dated February 26, 2015 (ML15033A152), the NRC endorsed the TSTFs approach in the handling of future LARs. As such, TVA referenced RG 1.160 in the TS Bases associated with this LAR.

3.3 Summary and Conclusions The unavailability of barriers which protect TS-required components from the effects of specific initiating events is typically a low-risk configuration which should not require that the protected components be immediately declared inoperable. The current TS require that when such barriers are unavailable, the protected component LCO is immediately entered. Some potential undesirable consequences of the current TS requirements include:

1. When maintenance activities on the supported TS system requires removal and restoration of barriers, the time available to complete maintenance and perform system restoration and testing is reduced by the time spent maneuvering the barriers within the time constraints of the supported system LCO.

2. Restoration of barriers following maintenance must be given a high priority due to time restraints of the existing supported system LCO, when other more risk-important activities may have a greater risk impact and should therefore be given priority; and

3. Unnecessary plant shutdowns may occur due to discovery of degraded barriers which may require more than the existing supported system LCO time to complete repairs and restoration.

To remove the overly restrictive requirements in the treatment of barriers, the licensee is proposing a risk-informed TS change which introduces a delay time before entering the actions for the supported equipment when one or more barriers are found degraded or removed to facilitate planned maintenance activities. Such a delay time will provide needed flexibility in the performance of maintenance during power operation and at the same time will enhance overall plant safety by (1) performing system maintenance and restoration activities, including post-maintenance testing, within the existing TS LCO time, and allowing barrier removal and restoration to be performed outside of the TS LCO, providing more time for the safe conduct of maintenance and testing activities on the supported system; (2) requiring barrier removal and restoration activities to be assessed and prioritized based on actual plant risk impacts; and (3) avoiding unnecessary unscheduled plant shutdowns, thus minimizing plant transition and realignment risks.

The risk impact of the proposed TS changes was assessed following the three-tiered approach recommended in RG 1.177. A simplified bounding risk assessment was performed to justify the proposed TS changes. This bounding assessment was selected due to the lack of detailed plant-specific risk models for most plants which do not include failure modes of passive structures such as barriers. The impact from the addition of the proposed LCO 3.0.9 to the TS on defense-in-depth was also evaluated in conjunction with the risk assessment results.

Based on this integrated evaluation, which is bounding for Watts Bar, Units 1 and 2, the NRC staff concludes that the proposed addition of LCO 3.0.9 to the licensees TSs would lead to insignificant risk increases as stipulated by RG 1.177 and depicted on Table 1 above. This conclusion is true without taking any credit for the removal of potential undesirable consequences associated with the current conservative treatment of barriers. Therefore, the proposed change provides adequate protection of public health and safety and is acceptable provided the conditions set forth below are satisfied.

Consistent with the NRC staffs approval and inherent in the implementation of TSTF-427, the licensee agreed to implement LCO 3.0.9 by operating in accordance with the following stipulations:

1. The licensee must commit to the guidance of NUMARC 93-01, Section 11, and to NEI 04-08; and

2. Licensee procedures must be revised to ensure that the guidance on the risk assessment and management process described in NEI 04-08 is used whenever a barrier is considered unavailable and the requirements of LCO 3.0.9 are to be applied.

This must be done in accordance with an overall CRMP to ensure that potentially risk-significant configurations resulting from maintenance and other operational activities are identified and avoided.

The licensees application made regulatory commitments in Section 3.2, Verification and Commitments, to implement LCO 3.0.9 with the above stipulations; the NRC staff acknowledges the licensees regulatory commitments as consistent with TSTF-427.

4.0 STATE CONSULTATION

In accordance with the Commissions regulations, the Tennessee State official was notified of the proposed issuance of the amendment on April 5, 2024. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement with respect to installation or use of a facility component 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 previously issued a proposed finding that the amendment involves no significant hazards consideration published in the Federal Register on March 19, 2024 (89 FR 19610), 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 amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: R. Grover, NRR T. Hillsmeier, NRR Date: July 2, 2024

ML24131A001 OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DRA/APLA/BC NRR/DSS/STSB/BC NAME KGreen ABaxter BPascarelli SMehta DATE 05/09/24 05/14/24 06/10/24 06/12/24 OFFICE NRR/DORL/LPL2-2/BC NRR/DORL/LPL2-2/PM NAME DWrona KGreen DATE 7/2/24 7/2/24