Text

Watts Bar, Unit 1, Application to Modify Technical Specifications Regarding AC Sources - Operating (TS-WBN-13-02)
	ML13220A103
Person / Time
Site:	Watts Bar
Issue date:	08/01/2013
From:	Shea J W; Tennessee Valley Authority
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	Download: ML13220A103 (50)
	v • d • e

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402August 1, 201310 CFR 50.90ATTN: Document Control DeskU.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant Unit 1Facility Operating License No. NPF-90NRC Docket No. 50-390

Subject:

Application to Modify Watts Bar Nuclear Plant, Unit I Technical Specifications Regarding AC Sources -Operating (TS-WBN-13-02)

References

1. NUREG-0847, "Safety Evaluation Report Related to the Operation ofWatts Bar Nuclear Plant, Unit 2," Supplement 22, dated February 2011(ADAMS Accession No. ML1 10390197)

2. NUREG-0847, "Safety Evaluation Report Related to the Operation ofWatts Bar Nuclear Plant, Unit 2," Supplement 24, dated September 2011(ADAMS Accession No. ML1 1277A1 48)In accordance with the provisions of 10 CFR 50.90, "Application for amendment of license,construction permit, or early site permit,"

the Tennessee Valley Authority (TVA) is submitting arequest for an amendment to Facility Operating License No. NPF-90 for Watts Bar NuclearPlant (WBN), Unit 1.TVA proposes this license amendment request (LAR) to the WBN, Unit 1 Technical Specifications (TS) to modify the Limiting Condition for Operation (LCO) for the AC SourcesOperating in LCO 3.8.1, provide additional time to restore an inoperable offsite circuit, modifySurveillance Requirement (SR) 3.8.1.8, and modify the current licensing basis, as described inthe Updated Final Safety Analysis Report (UFSAR),

for the available maintenance feeder forthe Common Station Service Transformers (CSST) A and B. The proposed LAR creditsupgrades made to CSST A and B to provide two new sources of preferred Class 1 E powersupply feeds in addition to the two normal Class 1 E power supply feeds. The TS change isneeded to support dual unit operations without requiring a dual unit shutdown duringmaintenance on either preferred power CSST C or D. This proposed request also achieveslicensing basis commonality for the current Operating Unit 1 license with respect to thoseapproved elements of the Unit 2 application as docketed in NUREG-0847, Supplements 22 and24 (References 1 and 2).Printed on recycled paper U.S. Nuclear Regulatory Commission Page 2August 1, 2013The enclosure provides the description, technical evaluation, regulatory evaluation, andenvironmental consideration of the proposed changes.

Attachments 1 and 2 to the enclosure provide the existing TS and Bases pages marked-up to show the proposed changes.Attachments 3 and 4 to the enclosure provide the existing TS and Bases pages retyped withthe proposed changes incorporated.

Attachment 5 to the enclosure provides a summary of theproposed UFSAR changes.TVA requests approval of this LAR no later than April 30, 2014, to support preparations for fuelload activities at Watts Bar Unit 2.TVA has determined that there are.no significant hazards considerations associated with theproposed change and that the change qualifies for a categorical exclusion fromenvironmental review pursuant to the provisions of 10 CFR 51.22(c)(9).

The WBN Plant Operations Review Committee and the WBN Nuclear Safety Review Boardhave reviewed the proposed changes and determined that operation of WBN in accordance with the proposed change will not endanger the health and safety of the public.Additionally, in accordance with 10 CFR 50.91 (b)(1), TVA is sending a copy of this letter andthe enclosure to the Tennessee Department of Environment and Conservation.

There are no regulatory commitments associated with this submittal.

Please address anyquestions regarding this request to Mr. E. D. Schrull at 423-751-3850.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on this1 st day of August 2013.Resp hly,J W S hea,cresident, Nuclear Licensing

Enclosure:

Evaluation of Proposed Changecc (Enclosure):

NRC Regional Administrator

-Region IINRC Senior Resident Inspector-Watts Bar Nuclear Plant, Unit 1Director, Division of Radiological Health -Tennessee State Department ofEnvironment and Conservation ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT IEVALUATION OF PROPOSED CHANGE

Subject:

Application to Modify Watts Bar Nuclear Plant, Unit I Technical Specifications Regarding AC Sources -Operating (TS-WBN-13-02) 1.0 SUMMARY DESCRIPTION 2.0 DETAILED DESCRIPTION 2.1 Proposed Changes2.2 Need for Proposed Changes3.0 TECHNICAL EVALUATION 3.1 System Description

3.2 Evaluation

4.0 REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements and Criteria4.2 Precedent 4.3 Significant Hazards Consideration

4.4 Conclusions

5.0 ENVIRONMENTAL CONSIDERATION

6.0 REFERENCES

ATTACHMENTS

1. Proposed TS Changes (Mark-Ups) for WBN Unit 12. Proposed TS Bases Changes (Mark-Ups) for WBN Unit 1 (For Information Only)3. Proposed TS Changes (Final Typed) for WBN Unit 14. Proposed TS Bases Changes (Final Typed) for WBN Unit 1 (For Information Only)5. Proposed UFSAR Changes (Mark-Ups) for WBN Unit 1 (For Information Only)E-1 I of 48 1.0 SUMMARY DESCRIPTION This evaluation supports a request to amend Watts Bar Nuclear Plant (WBN), Unit 1,Facility Operating License No. NPF-90. The proposed change will modify WBN, Unit 1Technical Specification (TS) 3.8.1, "AC Sources -Operating,"

by adding a note toLimiting Condition for Operation (LCO) 3.8.1, adding additional required actions to LCO3.8.1 Action A, and adding requirements to Surveillance Requirement (SR) 3.8.1.8.

Theproposed change will also revise the current licensing basis, as described in the UpdatedFinal Safety Analysis Report (UFSAR),

to allow the use of Common Station ServiceTransformers (CSSTs) A and B as qualified sources of power.This amendment proposes to revise Technical Specification 3.8.1 and Technical Specification Bases 3.8.1 to add an allowance to use Common Station Service Transformer (CSST) A or B to meet the requirements of LCO 3.8.1, with respect to qualified offsitecircuits, provide additional time to operate with an offsite circuit inoperable when CSST C orD is inoperable, and add testing of the manual transfers of the shutdown boards to and fromthe maintenance feeds (i.e., CSSTs A and B). Testing of the manual transfers is required toshow that these transfers are functional and can be used to supply power to the shutdownboards during conditions when either CSST C or D is out of service for maintenance or torestore power if CSST C or D fails. The proposed changes result from upgrades made toCSSTs A and B to provide two new sources of preferred Class 1 E power supply feeds inaddition to the two normal Class 1 E power supply feeds. The upgrades to CSSTs A and Bwere completed as part of actions to address NUREG-0847, "Safety Evaluation ReportRelated to the Operation of Watts Bar Nuclear Plant, Unit 2," Supplement 22, Appendix HH,'Watts Bar Unit 2 Action Items Table," Open Item 27 (Reference 1).In addition, this amendment proposes to modify the current licensing basis, as described inthe UFSAR, to remove the statements restricting the use of the CSSTs A and Bmaintenance feed during dual unit operations.

Attachments 1 and 2 to this enclosure provide the existing WBN, Unit 1 TS and Basespages marked-up to show the proposed changes.

Attachments 3 and 4 to this enclosure provide the existing TS and Bases pages retyped to show the proposed changes.Attachment 5 to this enclosure provides a summary of the proposed UFSAR changes.2.0 DETAILED DESCRIPTION

Background

The WBN Alternating Current (AC) Electrical Power Distribution System AC sources consistof the offsite power sources (preferred power sources, normal and alternate(s))

and theonsite standby power sources (Train A and Train B diesel generators (DGs)). As requiredby 10 Code of Federal Regulations (CFR) 50, Appendix A, General Design Criterion (GDC)17 (Reference 2), the design of the AC electrical power system provides independence andredundancy to ensure an available source of power to the Engineered Safety Feature (ESF)systems.Offsite power is supplied to the 161 kiloVolt (kV) transformer yard by two dedicated linesfrom the WBN Hydro Plant switchyard.

From the 161 kV transformer yard, two electrically and physically separated circuits provide AC power, through stepdown CSSTs C and D, tothe 6.9 kV shutdown boards. The two offsite AC electrical power sources are designed andlocated so as to minimize to the extent practical the likelihood of their simultaneous failureE-1 2 of 48 under operating and postulated accident and environmental conditions.

A detaileddescription of the offsite power network and the circuits to the Class 1 E shutdown boardsare found in WBN UFSAR Section 8 (Reference 3).The WBN Auxiliary Power System (APS) was originally designed for two unit operation.

However, due to the deferral of completion of Unit 2 prior to 2007, a detailed analysis of theadequacy of the APS was performed for Unit 1 only during the Unit 1 licensing effort.Therefore, the APS analysis supported Unit 1 operation only, although it took into accountUnit 2 buses, boards and loads required for Unit 1 operation and safe shutdown.

Currently TVA continues to prepare for WBN Unit 2 licensing and plans to place the unit intocommercial operation in the near future. Thus, the APS will be required to support a twounit operation.

By letter dated July 12, 2010, (Reference 4), the NRC requested that TVAprovide an executive summary of the two unit analysis to support the following designrequirements:

" Dual-unit trip as a result of an abnormal operational occurrence;

Accident in one unit and concurrent shutdown of the second unit (with and without offsitepower); and* Accident in one unit and spurious Engineered Safety Feature (ESF) actuation in theother unit (with and without offsite power).WBN performed a study (Reference

5) to evaluate the existing WBN APS to determine itsadequacy for two unit operation, including the design requirements requested in theReference 4 NRC letter. As stated in the TVA letter to the NRC dated July 31, 2010(Reference 6), the scope of this study included the CSSTs A, B, C, and D; 6.9-kV shutdownboards; 6.9-kV start buses; 6.9-kV common boards; 6.9-kV unit boards; downstream 6.9-kV-480-volt (V) transformers; 480-V distribution systems loads, and all interconnections.

The study specifically evaluated existing CSSTs A and B to determine their acceptability asqualified offsite power sources for the safety related boards when used for safe shutdown ofthe units under a design basis Loss of Coolant Accident (LOCA). The study recommended adding an automatic On Load Tap Changer (OLTC) on the primary side of CSST A and B.The study also concluded that WBN Units 1 and 2 are stable for all 3-phase fault scenarios with normal clearing.

Additionally, it concluded that the voltage criteria are met for WBN Unit2 coming on line and for other future system changes.As a result of the above study, TVA upgraded CSSTs A and B to functionally perform asalternate sources of offsite power in order to increase defense in depth and add increased reliability to the offsite power sources.The WBN Design Change Notices (DCNs) that facilitated the use of CSSTs A and B asqualified offsite sources for the 6.9 kV shutdown boards to support safe shutdown of the unitduring a design basis event have been completed.

This License Amendment Request (LAR) requests to revise the WBN, Unit 1 Technical Specifications (TS) by modifying the Limiting Condition for Operation (LCO) for theAC Sources Operating in LCO 3.8.1, providing additional time to restore an inoperable offsite circuit, modifying Surveillance Requirement (SR) 3.8.1.8, and modifying the currentlicensing basis, as described in the UFSAR, for the available maintenance feeder for CSSTsA and B.E-1 3 of 48 2.1 Proposed ChangesTechnical Specification ChangesTVA proposes the following changes to the WBN, Unit 1 Technical Specifications.

a. Number the current LCO 3.8.1 Note as "Note 1" and add a Note 2 to LCO 3.8.1 toprovide guidance and conditions for using CSST A or B to meet one of the two qualified offsite circuits, to read:2. Common Station Service Transformer (CSST) A or B may be used to meetone of the two qualified offsite circuit requirements of LCO 3.8.1, providedCSST A or B is only providinq power to its normal unit and reactor coolantpump boards, and:a. CSST A or B is providinq power to the associated shutdown board; orb. The associated shutdown board is beinq powered by the Unit StationService Transformer (USST) and automatic transfer capability from theUSST to CSST A or B (as applicable) is OPERABLE.

b. Renumber Required Action A.3 to "A.3.1" and add additional required actions to LCO3.8.1 Condition A to provide alternate requirements for using CSST A or B to meet LCOrequirement, to read (renumbered Required Action A.3.1 shown for clarity):

A.3.1 Restore offsite circuit to OPERABLE status.ORA.3.2.1 Aliqn backup offsite circuit CSST A or CSST B torequired shutdown board.ANDA.3.2.2 Restore offsite circuit to OPERABLE statusc. Revise SR 3.8.1.8 to add additional surveillance requirements for verifying automatic and manual function of 6.9 kV power supplies, to read:Verify the followincq:

a. Automatic and manual transfer of each 6.9 kV shutdown board powersupply from the normal offsite circuit to the alternate offsite circuit;b. Automatic transfer of the associated 6.9 kV shutdown board power suppl,from the USST to the associated CSSTA or B, when USST is powerinq theassociated shutdown board and CSST A or B is credited with meetinq LCO3.8.1.a requirements; andc. Manual transfer of the associated 6.9 kV shutdown board power supplifrom the associated CSST A or B to the normal offsite circuit (CSST C or D.E-1 4of48 as applicable),

when CSST A or B is credited with meeting LCO 3.8.1.arequirements.

UFSAR ChangesIn order to credit upgrades made to CSSTs A and B, to provide four new sources ofpreferred Class 1 E power supply feeds in addition to the two normal Class 1 E powersupply feeds, the following UFSAR sections will be revised:

Sections 8.2.1, 8.2.1.3,8.2.1.5, 8.2.1.6 and 8.2.1.8.

In addition, UFSAR Figures 8.1-2, 8.1-2B, 8.3-5, 8.3-16,8.3-17, 8.3-18 and 8.3-19 are affected by the proposed change and will be updated aspart of the amendment implementation phase to be included in the subsequent UFSARupdate as required by 10 CFR 50.71(e),

"Maintenance of records, making of reports."

The referenced figures are based on TVA drawings 1-15E500-1, 1-15E500-3, 1-45W724-1, 1-45W724-2, 1-45W724-3 and 1-45W724-4 respectively.

Refer to Enclosure Attachment 5 for the currently planned UFSAR text changes.2.2 Need for Proposed ChangesWatts Bar Nuclear Plant (WBN) is currently configured with four CSSTs that provide offsitepower. CSSTs C and D are qualified and used to supply the safety related class 1 E powersystem; CSSTs A and B are used for non-safety loads. During operation in Mode 1, 2, 3, or4 with either CSST C or D out of service, the plant is required to enter LCO 3.8.1 Condition A for not having two qualified offsite power sources available (i.e., one of the two qualified offsite sources are inoperable

). From a plant operational flexibility standpoint, this condition has been adequate for single unit operation.

Maintenance on either CSST C or D duringsingle unit operation mode can be performed in Modes other than Modes 1, 2, 3, and 4, i.e.,when only one of the two qualified offsite circuits are required to be OPERABLE inaccordance with LCO 3.8.2, "AC Sources -Shutdown."

Thus, performing maintenance atthis time does not require entry into LCO 3.8.1.However, once Unit 2 begins power operations, it will be desirable to have one unit runningwhile the other unit is in an outage. Therefore, one unit will be in Mode 1, 2, 3, or 4 when itis desired to perform maintenance on CSST C or D. To support performing maintenance oneither of these two CSSTs when one unit is operating will require increased operational flexibility from the offsite power system to ensure that two offsite sources can be maintained even when a CSST is removed from service.

Furthermore, performing the requiredmaintenance can take more time than the currently allowed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to restore aninoperable qualified offsite circuit to OPERABLE status when the unit is in MODE 1, 2, 3, or4, as required by LCO 3.8.1, Action A. Therefore, this technical specification change isnecessary to allow this maintenance to be performed without requiring a dual unit shutdownincluding those times when the maintenance or repairs may require up to 14 days or longer.3.0 TECHNICAL EVALUATION 3.1 System Description The WBN plant electric power system consists of the main generators, USSTs, CSSTs,diesel generators, batteries, and the electrical distribution system. Under normal operating conditions, the main generators supply electrical power through isolated-phase buses to themain step-up transformers and through the unit station service transformers to thenon-safety auxiliary power system. Offsite electrical power supplies Class 1 E circuitsthrough the 161-kV system via CSSTs C and D. The primaries of the unit station serviceE-1 5of48 transformers are connected to the isolated-phase bus at a point between the generator terminals and the low-voltage connection of the main transformers.

During normaloperation, station auxiliary power is taken from the main generator through the unit stationservice transformers and from the 161-kV system through the CSSTs.In conformance with GDC 17, the design function of the preferred offsite power system is tosupply power within specified limits to components and systems required to ensure that fueldesign limits and reactor coolant pressure boundary design conditions are not exceededdue to operational occurrences and the core is cooled and vital functions are maintained during postulated accidents in one unit while safely shutting down the other unit.The preferred power lines from the existing Watts Bar Hydro 161-kV switchyard, providespower to all four CSSTs (A, B, C, and D) and are routed to minimize the likelihood of theirsimultaneous failure.The safety-related plant distribution system receives AC power from CSSTs C and Dthrough the shutdown boards (which are powered from the offsite power system),

or four4400 kW diesel-generator standby power sources, and distributes it to both safety-related and non-safety-related loads in the plant. The two preferred circuits have access to the TVAtransmission network which in turn has multiple interties with other transmission networks.

Each line (CSST C and D) is the normal feed for one train of shutdown boards and thealternate feed for the other train of shutdown boards. The other transformer (CSST A andB) on each line supplies power to the 6.9kV unit boards and can indirectly power theshutdown boards if they are tied to the unit boards through the maintenance feeder. Thismaintenance feeder path is not a qualified source for the shutdown boards and can only beused in Mode 5 or below (i.e., when LCO 3.8.1 is not applicable).

Currently, UFSAR Section 8.2.1.8 describes automatic fast transfer of the 6.9kV shutdownboards to their alternate source (CSST C or D) when the normal source (CSST C or D) trips.When CSST C or D trips and CSST A or B is manually aligned in place of the trippedCSST C or D, the fast transfer for the alternate is lost. Also, due to loading and separation requirements alignment restrictions are required when CSST A or B is used as an offsitesupply for the 6.9kV Shutdown Boards.The 6.9kV common switchgear C and D are connected to the 6.9kV shutdown boards bycables arranged to provide two physically independent sources of offsite power.The CSSTs and buses are connected and arranged to provide two physically independent offsite power (OSP) circuits to the onsite (Class 1 E) distribution system. One OSP circuitthat is connected to CSSTs A and D is designated P while the other OSP circuit that isconnected to CSSTs B and C is designated R. Circuits designated P and R are routed inseparate conduits and trays to assure physical independence with any exceptions and theirjustifications documented in the design criteria.

Non-segregated phase buses are used toconnect the secondary of CSSTs C and D to 6.9-kV common switchgear C and switchgear D, respectively.

During startup and shutdown, all auxiliary power is supplied from the161 -kV system through CSSTs A, B, C and D.E-1 6 of 48 Two offsite power circuits are required to be operational with one available within a fewseconds following a loss of coolant accident (as specified in GDC 17). The proposedamendment improves the ability of the plant to meet these design requirements during dualunit operation.

A simplified diagram of the proposed change is provided below.CSST B CSST A CSST B CSST AIL ILLIi IL1B i 1C i 2B 2C Unit Boardsi iCSST0 ..0 0B.,

r.L:IShutdownlA-A lB-B 2A-A 2B-B BoardsMaintenance feeder proposed by this license amendment.

3.2 Evaluation

3.2.1 Introduction

Design studies have concluded that CSSTs A and B are appropriately sized to carryrequired Balance of Plant (BOP) loads as well as one train of Class 1 E loads for each unitduring normal and accident conditions provided both CSSTs A and B are in service(Reference 8). In addition, the analysis demonstrated that power and control cablesassociated with CSSTs A and B and the maintenance feeders meet separation requirements provided only CSST A or CSST B is used to power one train of shutdownboards, but not both. These restrictions have been incorporated into the WBN Unit 1UFSAR and Design Criteria.

With CSSTs A and B meeting the requirements of GDC 17, these transformers may be usedas qualified sources of offsite power. A description of the changes to CSSTs A and Bneeded for them to considered qualified sources is provided below. This amendment proposes to revise Technical Specification 3.8.1 by adding a note to Limiting Condition forOperation (LCO) 3.8.1 allowing the use of CSST A or B to meet the requirements ofLCO 3.8.r.a under certain circumstances, adding additional required actions to LCO 3.8.1Action A to allow one qualified offsite circuit to be inoperable for up to 14 days, and addingrequirements to Surveillance Requirement (SR) 3.8.1.8 to add testing of the manualtransfers of the shutdown boards to and from the maintenance feeds (i.e., CSSTs A and B)in order to show that these transfers are functional and can be used to supply power to theshutdown boards in the case that either CSST C or D is out of service for maintenance or forother reasons.E-1 7 of 48 3.2.2 Technical BasisThe existing CSSTs A and B were upgraded to provide an additional source of qualified power to the safety related class 1 E system. This upgrade allows either CSST A or B topower the shutdown boards while either CSST C or D is out of service for maintenance.

Several design changes were required in order to qualify the existing CSSTs A and B foroffsite power sources to the safety related class 1 E system. On-load tap changers (OLTCs)were installed on CSST A and B to meet the required stable voltage requirements for the6.9kV Shutdown Boards. "P" and "R" train designations were added to power and controlcables associated with CSSTs A and B and cables were re-routed as necessary to maintainGDC 17 separation requirements.

Additional new features from the physical work completed under DCN 52336, have installed:

" cables and raceways to provide OLTC position indication;

OLTC trouble alarm;* manual/automatic operation of the OLTC in the Main Control Room;* control switch and tap position indicator, for CSST A and B in the Electrical ControlBoard (ECB) Panel 2;* Alarm for CSST A and B tap changer abnormal in annunciator window box XA-55-42A, window number 502B/503B, located in ECB Panel 3; and* Alarm input combined with other alarm inputs from CSST A and B.The use of CSSTs A and B as offsite power sources to the safety related class 1 E systemrequires compliance with several restrictions to ensure loading and separation requirements are met before either of these CSSTs can be aligned to the shutdown boards. Somerestrictions include:1. Only CSST A or B can be used as a qualified offsite power at any given time(i.e., either CSST C or D must be Operable);

2. All power and control circuits associated with CSSTs A and B as well as themaintenance feeders must be normally aligned; and3. The CSST being used to meet LCO 3.8.1.a cannot be providing power to unit andreactor coolant pump (RCP) boards other than its normal boards. The unit andRCP boards not normally powered by the CSST being used to meet LCO 3.8.1.amust be powered by the other CSST (A or B) or the USST.These restrictions are required in order to maintain the GDC 17 separation requirements because the original design did not consider these separation requirements.

The offsite source via CSST A or B has been analyzed to demonstrate that the sources cansupport shutdown in the event of an accident in one unit and an orderly shutdown of theother unit, including a spurious ESF actuation in the non-accident unit. The Transmission System Study considered the following:

" Loss of the largest capacity being supplied to the grid;* Loss of the largest load from the grid;* Loss of the most critical transmission line; and* Loss of both unitsE-1 8 of 48 The analysis demonstrated that CSST A or B has sufficient capacity and voltage toadequately supply the 1 E loads. Electrical Calculation EDQ00099920070002, "Auxiliary Power System Analysis for Two Unit Operation,"

(Reference

8) evaluated and determined the use of CSSTs A and B as substitutes for CSSTs C and D acceptable providedCSSTs A and B are equipped with automatic OLTCs under certain documented operational restrictions.

When the plant is normally aligned with CSSTs C and D powering the shutdown boards, theloss of a CSST results in the automatic transfer of the two shutdown boards it powers to theother CSST, D or C. This proposed TS change provides an alternate path to offsite powervia CSST A or B to one train of safety buses. Realignment is performed manually from theMain Control Room using a permanently installed transfer scheme, with no requirement onactions outside the Main Control Room (can also be done locally in AUX Position).

Upondetecting a loss of offsite power from C or D, the operable Maintenance Supply is available for restoration of the preferred source to safety related loads. The restoration of power tothe Safety Related Boards can be performed within a few minutes of detection, which is wellwithin the four hour coping period established for station blackout, loss of all offsite andonsite AC power.As stated in proposed Note 2 to LCO 3.8.1, the use of CSSTs A and B as a qualified backupis limited to one CSST only (i.e., only one train per unit can be supplied by CSST A or B atany given time). If CSST C or D is out of service, train A or B for both units will be requiredto be manually aligned to CSST B or A, respectively, when CSST A or B is being used tomeet LCO 3..8.1.a requirements.

Furthermore, alignment of the shutdown boards to theUSST is allowed by Note 2 since an automatic transfer capability from the USST to CSSTsA and B exists. Thus, if the USST trips, power to the applicable unit boards is automatically transferred to CSSTs A and B, thereby maintaining power to the shutdown boards, if theyare directly tied to the units boards. In addition, the CSST being used is restricted topowering only its normal unit and RCP boards. This ensures the CSST is not overloaded when supplying power to the shutdown boards.Plant modifications resulted in the acceptable alignments for the shutdown boards, allowingCSST A or B to be placed in service in any operating mode while CSST D or C respectively is out of service.

The modifications created operational differences that affect actions by theOperations staff. The ability to use CSST A or B as a qualified offsite power source will beadded to operations procedures and training.

In addition there is no automatic transferassociated with the maintenance feeders such as those that exist between the normal andalternate supplies to the shutdown boards. All transfers to and from the maintenance feedsare manual. It is also possible to make the transfer by local control if in the AUX position.

The WBN simulator was modeled to show that the proposed lineups can be performed andplant operators will be able to execute the procedures and meet the times that are in theproposed TS Amendment.

When one of the two normal CSSTs (i.e., CSST C or D) becomes inoperable, existingTS 3.8.1 Required Action A.3 requires the offsite circuit to be restored within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .Proposed Required Actions A.3.2.2 will allow up to 14 days to restore the inoperable circuitto operable status. This time is allowed only if CSST A or B is aligned to be capable ofproviding power to the respective shutdown board within the same 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months as is currently allowed to restore an inoperable offsite circuit.

Furthermore, during this extended time, theDGs remain operable (if they were inoperable, another Action would be required to beentered -Action D -and Action D does not allow this extended Completion Time). Theadditional time from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 14 days for proposed LCO Required Action A.3.2.2 allowsE-1 9of48 completing maintenance and/or major repairs and also limits the number of transients required during this period. A PRA risk review identified the extension of time where asecond offsite power source is not automatically available has less risk significance thanmultiple transients to maintain an automatically available second offsite power source(Reference 9). If the other CSST C or D is lost during this time (i.e., the time between thecurrent 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and the proposed 14 days), the shutdown boards powered by thatCSST (C or D) would be automatically re-energized from the associated DGs. The PRAanalysis concluded that the planned alternate alignments could be maintained for an entireannual evaluation period and the changes in CDF and LERF would be minimal and wouldremain below industry guidelines for risk associated with online maintenance

(< 1 E-6 IDCP, 1 E-7 ILERP). Therefore, power to the shutdown boards (at least one train)could be manually transferred to CSST A or B, whichever has been aligned as required byproposed Required Action A.3.2.1, and the DGs placed back into the standby condition.

This situation is similar to the condition currently allowed during the first 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months afterCSST C or D becomes inoperable.

Therefore, TVA considers the extension of therestoration time to be acceptable.

To ensure CSSTs A and B are operable, SR 3.8.1.8 has been modified to require similartesting as is currently performed for CSSTs C and D. Specifically, the manual transfercapability is required to be tested when CSST A or B is used to meet the LCO 3.8.1.arequirements.

Furthermore, if the USSTs are tied to the unit boards, then the proposed SRalso requires testing of the automatic transfer between the USSTs and CSSTs A and B.This will ensure CSSTS can be properly aligned to provide power to the shutdown boards,when they are being used to meet the LCO 3.8.1.a requirements.

To ensure the CSST isonly providing power to its normal unit and RCP boards, the Bases of SR 3.8.1.1, whichverifies correct breaker alignment and power availability for each offsite circuit, will bemodified to provide clarification that when the CSST A or B is being used to meetLCO 3.8.1.a requirements, the breaker alignment check will include verifying the CSST isonly providing power to its normal unit and RCP boards.In addition, the NRC has previously reviewed and approved the above design changes forCSSTs A and B to support dual unit operation.

This is detailed in References 1 and 7,which are NRC Safety Evaluations related to the operation of WBN, Unit 2. These proposedchanges achieve licensing basis commonality for both units, with respect to usingCSSTs A and B.3.2.3 Conclusion The physical modifications upgraded CSSTs A and B to be in conformance with therequirements of GDC 17 for use as an offsite power source. The manual transfer toCSSTs A and B can be performed directly from the Main Control Room. The proposedTS Amendment Will improve the availability of the offsite power system to the safety relatedelectrical buses and provide the necessary flexibility for two unit operation withoutnecessitating the simultaneous shutdown of both units for maintenance of eitherCSST C or D.Proposed changes to the UFSAR, tech specs, tech spec bases, and design criteria havebeen prepared and are waiting implementation upon approval of this amendment request toreflect this change as well as to outline the requirements which must be met in order forCSSTs A and B to be used as offsite power sources.

Qualification of CSSTs A and B asoffsite power sources will allow maintenance to be performed on CSSTs C and D withoutrequiring a dual unit outage which is necessary for WBN to operate as a dual unit plant.E-1 10 of 48 As stated above, these changes, related to utilizing CSSTs A and B as qualified offsitesources, have been previously approved by the NRC for WBN, Unit 2.The proposed revision to Unit 1 TS 3.8.1 to establish licensing basis commonality forWBN Units 1 and 2 is based on previously approved elements of the Unit 2 SafetyEvaluation documented in References 1 and 7. The extension of the Completion Time from72 hours to 14 days is acceptable because during the additional time, a qualified secondcircuit is available to be manually tied to provide power to at least one shutdown board train,and the DGs remain fully operable.

Furthermore, the request to provide additional time tooperate with an offsite circuit inoperable when CSST C or D is inoperable helps reduce thenumber of times that the transfers are performed and allow additional time to completemaintenance and/or repairs while also limiting the number of transients required during thisperiod. The PRA risk review identified the extension of time where a second offsite powersource is not automatically available has less risk significance than multiple transients tomaintain an automatically available second offsite power source.The revision to add the automatic (USST only) and manual transfer testing of the associated shutdown power to the associated CSST A or B is to ensure functionality of the associated equipment and maintain an appropriate level of quality.4.0 REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements and CriteriaPer GDC 17 the purpose of the offsite power system is to provide a source of power for allequipment required to assure that fuel design limits and design conditions of the reactorcoolant pressure boundary are not exceeded.

Two offsite power circuits are required to beoperational with one available within a few seconds of a loss of coolant accident.

Theproposed amendment improves the ability of the plant to meet these design requirements.

The proposed changes described in this Technical Specification (TS) amendment request,do not alter or revise offsite Alternating Current power systems at Watts Bar Nuclear Plant(WBN) Unit 1, which are designed to comply with the following applicable regulations andrequirements:

10 CFR 50, Appendix A, General Design Criterion (GDC) 17, "Electric powersystems,"

specifies that an offsite electric power system shall be provided to permitfunctioning of structures,

systems, and components important to safety.* 10 CFR 50, Appendix A, GDC 18, "Inspection and testing of electric power systems,"

specifies that electric power systems important to safety shall be designed to permitappropriate periodic inspection and testing of important areas and features.

Regulatory Guide 1.32, Revision 1, "Criteria for Safety-Related Electric PowerSystems for Nuclear Plants,"

describes acceptable designs for the availability ofoffsite power.& Regulatory Guide 1.93, Revision 0, "Availability of Electric Power Sources,'"

describes the operating procedures and restrictions with respect to the availability ofelectric power sources.E-1 11 of 48 Institute of Electrical and Electronics Engineers (IEEE) Standard 308-1971, "Criteria for Class 1 E Power Systems for Nuclear Power Generating Stations,"

provides criteria for the determination of Class 1 E power system design features andthe requirements for their testing, surveillance, and documentation.

With the implementation of the proposed change, WBN will continue to meet the applicable regulations and requirements.

4.2 Precedent

TVA did not identify any applicable regulatory precedent regarding the changes proposed byTVA in this license amendment request.4.3 Significant Hazards Consideration IVA has concluded that the changes to WBN Unit 1 TS 3.8.1 and the licensing basis, asdescribed in the Updated Final Safety Analysis Report (UFSAR),

do not involve a significant hazards consideration.

TVA's conclusion is based on its evaluation in accordance with10 CFR 50.91 (a)(1) of the three standards set forth in 10 CFR 50.92, "Issuance ofAmendment,"

as discussed below:1. Does the proposed amendment involve a significant increase in the probability or consequence of an accident previously evaluated?

Response:

NoThe proposed changes described in this TS amendment

request, do not alter thesafety functions of the WBN Offsite Power system. Design calculations documentthat CSSTs A and B have adequate capacity to supply all connected loads including one train of shutdown boards in all allowable alignments and meet the separation requirements for offsite power sources.

The consequences of an accident are notchanged when using CSST A or B to power the shutdown boards because theseCSSTs are rated to carry all required loads for any design basis accidents.

Thefailure of a CSST is not considered to be an initiator of a plant accident and therefore the probability or consequences of accidents or events previously evaluated, asdescribed in the UFSAR, is not changed.Therefore, this proposed amendment does not involve a significant increase in theprobability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kindof accident from any accident previously evaluated?

Response:

No.As stated above, malfunctions of the CSSTs are not considered to be an initiator forplant accidents and the modifications to the offsite power system do not create a newor different kind of accident.

The purpose of the offsite power system is to provide asource of power to the safety related equipment required to mitigate a design basisaccident.

CSSTs A and B have been physically upgraded and proven by designcalculation to meet all required GDC 17 requirements for separation and voltageE-1 12 of 48 stability.

Using CSSTs A and B as alternate sources of shutdown power does notnegatively affect the offsite power systems ability to meet its design function.

Therefore, the proposed amendment does not create the possibility of a new ordifferent kind of accident from any accident previously evaluated.

3. Does the proposed amendment involve a significant reduction in a margin ofsafety?Response:

No.CSSTs A and B have adequate design margin to meet all possible loading scenarios as long as both CSSTs A and B are operational prior to one being used as a sourceof offsite power. This requirement is added to the control room drawings, plantdesign criteria and the UFSAR in order to ensure acceptable margin is alwaysavailable prior to CSSTs A or B being used as a source of offsite power.Therefore, the proposed changes do not involve a significant reduction in a margin ofsafety.4.3 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 theproposed 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 commondefense and security or to the health and safety of the public.5.0 ENVIRONMENTAL CONSIDERATION A review has determined that the proposed amendment would change a requirement withrespect to installation or use of a facility component located within the restricted area, asdefined 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 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 to10 CFR 51.22(b),

no environmental impact statement or environmental assessment need beprepared in connection with the proposed amendment.

E-1 13 of 48

6.0 REFERENCES

1. NUREG-0847, "Safety Evaluation Report Related to the Operation of Watts BarNuclear Plant, Unit 2," Supplement 22, dated February 2011 (ML1 10390197).

2. 10 CFR 50 Appendix A, General Design Criterion (GDC) 17, "Electric PowerSystems"3. WBN Unit 1, UFSAR, Section 8.4. NRC letter, 'Watts Bar Nuclear Plant, Unit 2 -Request for Additional Information Regarding Licensee's Final Safety Analysis Report Amendment related to Electrical Engineering Systems (TAC No. ME2731),"

dated July 12, 2010 (ADAMS Accession No. ML101530354).

5. WBN-AC-Study-001, "Offsite Power Feasibility Study for the AC Auxiliary PowerSystem to Determine Its Acceptability for Unit 2 Completion."

6. TVA letter, "Watts Bar Nuclear Plant (WBN) Unit 2 -Final Safety Analysis Report(FSAR) -Response to Preliminary Requests for Additional Information and Requestsfor Additional Information,"

dated July 31, 2010 (ADAMS Accession No.ML 102290258).

7. NUREG-0847, "Safety Evaluation Report Related to the Operation of Watts BarNuclear Plant, Unit 2," Supplement 24, dated September 2011 (ML1 1277A148).

8. Watts Bar NPG Calculation No. EDQ00099920070002, "AC Auxiliary Power SystemAnalysis,"

Revision 028, dated May 30, 2011.9. TVA PRA Evaluation Response No. WBN-1-11-094, Revision 0, approved November10, 2011, to support license amendment request to permit the use of CSST A or B tofunction as alternate to CSST C or D.E-1 14 of 48 ATTACHMENT IProposed TS Changes (Mark-Ups) for WBN Unit IAC Sources-Operating 3.8.13.8 ELECTRICAL POWER SYSTEMS3.8.1 AC Sources -Operating LCO 3.8.1 The following AC electrical sources shall be OPERABLE:

a. Two qualified circuits between the offsite transmission network and theonsite Class 1 E AC Electrical Power Distribution System; andb. Four diesel generators (DGs) capable of supplying the onsite Class 1 E ACElectrical Power Distribution System.---------------------

NOTES---------------------

1. The C-S DG may be substituted for any of the required DGs.2. Common Station Service Transformer (CSST) A or B may be used to meet one ofthe two qualified offsite circuit requirements of LCO 3.8.1. Provided CSST A or B isonly Providinq power to its normal unit and reactor coolant pump boards, and:a. CSST A or B is providinq power to the associated shutdown board: orb. The associated shutdown board is beinq powered by the Unit Station ServiceTransformer (USST) and automatic transfer capability from the USST to theCSST A or B (as applicable) is OPERABLE.

APPLICABILITY:MODES 1, 2, 3, and 4.ACTIONSNOTE---------------------------------

LCO 3.0.4.b is not applicable to DGs.E-1 15of48 ATTACHMENT 1Proposed TS Changes (Mark-Ups) for WBN Unit IAC Sources-Operating 3.8.1CONDITION IREQUIRED ACTIONCOMPLETION TIMECONDITION__IREQUIRED__ACTION A. One offsite circuitinoperable.

A.1Perform SR 3.8.1.1 forOPERABLE offsite circuit.ANDA.2Declare requiredfeature(s) with no offsitepower available inoperable when it'sredundant requiredfeature(s) is inoperable.

ANDA.3.1 Restore offsite circuit toOPERABLE status.ORA.3.2.1 Align backup offsitecircuit CSST A or CSSTB to required shutdownboard.ANDA.3.2.2Restore offsite circuit toOPERABLE status.1 hourANDOnce per 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months sthereafter 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months fromdiscovery of nooffsite power to onetrain concurrent withinoperability ofredundant requiredfeature(s) 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months sAND6 days fromdiscovery of failure tomeet LCO72 hoursAND6 days fromdiscovery of failureto meet LCO14 daysE-1 16 of 48 ATTACHMENT IProposed TS Changes (Mark-Ups) for WBN Unit IAC Sources-Operating 3.8.1SURVEILLANCE FREQUENCY SR 3.8.1.7 Verify each DG starts from standby condition 184 daysand achieves in _< 10 seconds, voltage _> 6800 V,and frequency

> 58.8 Hz. Verify after DG faststart from standby conditions that the DGachieves steady state voltage _> 6800 V and <7260 V, and frequency

_ 58.8 Hz and _< 61.2 Hz.SR 3.8.1.8---------------------

NOTE -----------------

For the 1A-A and 1 B-B Shutdown Boards, thisSurveillance shall not be performed in MODE 1 or 2.However, credit may be taken for unplanned eventsthat satisfy this SR.Verify automatic and manual tranisfor of "Ach 6.9 W,s-hutd-own board power supply fromn the normal offsitecrutto eac-h -alternate offeito circuit.Verify the followingi:

a. Automatic and manual transfer of each 6.9 kVshutdown board power supply from the normaloffsite circuit to the alternate offsite circuit;b. Automatic transfer of the associated 6.9 kVshutdown board power supply from the USST to theassociated CSST A or B, when USST is powerina theassociated shutdown board and CSST A or B iscredited with meeting LCO 3.8. 1.a requirements:

and18 monthsc. Manual transfer of the associated 6.9 kV shutdownboard power supply from the associated CSST A orB to the normal offsite circuit (CSST C or D. asapplicable),

when CSST A or B is credited withmeeting LCO 3.8.1.a requirements.

(continued)

E-1 17 of 48 ATTACHMENT 2Proposed TS Bases Changes (Mark-Ups) for WBN Unit 1AC Sources -Operating B 3.8.1BASES (continued)

APPLICABLE SAFETY ANALYSESThe initial conditions of DBA and transient analyses in theFSAR, Section 6 (Ref. 4) and Section 15 (Ref. 5), assume ESF systems areOPERABLE.

The AC electrical power sources are designed to provide sufficient

capacity, capability, redundancy, and reliability to ensure the availability ofnecessary power to ESF systems so that the fuel, Reactor Coolant System(RCS), and containment design limits are not exceeded.

These limits arediscussed in more detail in the Bases for Section 3.2, Power Distribution Limits;Section 3.4, Reactor Coolant System (RCS); and Section 3.6, Containment Systems.The OPERABILITY of the AC electrical power sources is consistent with theinitial assumptions of the Accident analyses and is based upon meeting thedesign basis of the plant. This results in maintaining at least two DG'sassociated with one load group or one offsite circuit OPERABLE during Accidentconditions in the event of:a. An assumed loss of all offsite power or all onsite AC power; andb. A worst case single failure.The AC sources satisfy Criterion 3 of NRC Policy Statement.

LCOTwo qualified circuits between the Watts Bar Hydro 161 kV switchyard and theonsite Class 1 E Electrical Power System and separate and independent DGs foreach train ensure availability of the required power to shut down the reactor andmaintain it in a safe shutdown condition after an anticipated operational occurrence (AOO) or a postulated DBA.Qualified offsite circuits are those that are described in the FSAR and are part ofthe licensing basis for the plant.Each offsite circuit must be capable of maintaining acceptable frequency andvoltage, and accepting required loads during an accident, while connected to the6.9 kV shutdown boards.Offsite power from the Watts Bar Hydro 161 kV switchyard to the onsite Class 1 Edistribution system is normally from two independent immediate access circuits.

Each of the two circuits is routed from the switchyard through a 161 kVtransmission line and 161 to 6.9 kV transformer (common station servicetransformers) to the onsite Class 1E distribution system. The medium voltagepower system starts at the low-side of the common station service transformers.

E-1 18 of 48 ATTACHMENT 2Proposed TS Bases Changes (Mark-Ups) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

LCO Each DG must be capable of starting, accelerating to rated speed and voltage,(continued) and connecting to its respective 6.9 kV shutdown board on detection of loss-of-voltage.

This will be accomplished within 10 seconds.

Each DG must also becapable of accepting required loads within the assumed loading sequenceintervals, and continue to operate until offsite power can be restored to the 6.9 kVshutdown boards. These capabilities are required to be met from a variety ofinitial conditions such as DG in standby with the engine hot and DG in standbywith the engine at ambient conditions.

Additional DG capabilities must bedemonstrated to meet required Surveillances, e.g., capability of the DG to revertto standby status on an accident signal while operating in parallel test mode.Proper sequencing of loads, including tripping of nonessential loads, is a requiredfunction for DG OPERABILITY.

Note I has been added to indicate that the C-S DG may be substituted for any ofthe required DGs. However, the C-S DG cannot be declared OPERABLE until itis connected electrically in place of another DG, and it has satisfied applicable Surveillance Requirements.

The AC sources in one train must be separate and independent (to the extentpossible) of the AC sources in the other train. For the DGs, separation andindependence are complete.

For the offsite AC sources, separation and independence are to the extentpractical.

A circuit may be connected to more than one ESF bus, with fasttransfer capability to the other circuit OPERABLE, and not violate separation criteria.

A circuit that is not connected to an ESF bus is required to haveOPERABLE fast transfer interlock mechanisms to at least two ESF buses tosupport OPERABILITY of that circuit.A second Note has been added to allow common station servicetransformer (CSST) A or B to be used to meet one of the two qualified offsite circuit requirements of LCO 3.8. l.a. CSSTs A and B directly powerthe unit boards, and throuwh feeder breakers between the unit boards andthe shutdown boards, can provide power to the shutdown boards requiredby LCO 3.8.9, "AC Distribution."

The Note allows one of the two CSSTs (Aor B) to replace the normal qualified offsite circuit supply (CSST C or D),provided the CSST is only providina Dower to its normal unit and reactorcoolant pump (RCP) boards and either a) CSST A or B (as applicable) isprovidinq power to the associated shutdown board; or b) the associated shutdown board is beinq powered by the unit station service transformer (USST) and automatic transfer capability from the USST to CSST A or B (asapplicable) is OPERABLE.

This allowance is acceptable since CSSTA andB are capable of providinq the proper voltage and frequency to the class 1Eshutdown boards. In addition, all necessary unit boards and breakersnecessary to provide power to the required shutdown boards are requiredto be OPERABLE and are part of the CSST A or B qualified circuit.E-1 19 of 48 ATTACHMENT 2Proposed TS Bases Changes (Mark-Ups) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

ACTIONS A.3.1. A.3.2.1.

and A.3.2.2(continued)

According to Regulatory Guide 1.93 (Ref. 6), operation may continue inCondition A for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . With oneoffsite circuit inoperable, the reliability of the offsite system is degraded, and the potential for a loss of offsite power is increased, with attendant potential for a challenge to the plant safety systems.

In this Condition,

however, the remaining OPERABLE offsite circuit and DGs are adequateto supply electrical power to the onsite Class 1 E Distribution System!The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time takes into account the capacity andcapability of the remaining AC sources, a reasonable time for repairs, andthe low probability of a DBA occurring during this period.The second Completion Time for Required Action A.3 establishes a limiton the maximum time allowed for any combination of required AC powersources to be inoperable during any single contiguous occurrence offailing to meet the LCO. If Condition A is entered while, for instance, aDG is inoperable and that DG is subsequently returned

OPERABLE, theLCO may already have been not met for up to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . This could leadto a total of 144 hours0.00167 days 0.04 hours 2.380952e-4 weeks 5.4792e-5 months , since initial failure to meet the LCO, to restore theoffsite circuit.

At this time, a DG could again become inoperable, thecircuit restored

OPERABLE, and an additional 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months (for a total of9 days) allowed prior to complete restoration of the LCO. The 6 dayCompletion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO. This limit isconsidered reasonable for situations in which Conditions A and B areentered concurrently.

The "AND" connector between the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and6 day Completion Times means that both Completion Times applysimultaneously, and the more restrictive Completion Time must be met.As in Required Action A.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."This will result in establishing the "time zero" at the time that the LCO wasinitially not met, instead of at the time Condition A was entered.Alternately, in lieu of restoring the inoperable circuit to OPERABLEstatus in 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . required Action A.3.2.1 requires aligning thebackup offsite circuit CSST A or B to the required shutdown boardwithin 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . This is accomplished by ensuring power isavailable to CSST A or B. and that the breakers from CSST A or B tothe associated unit boards are OPERABLE and can be closed fromthe control room, and the breakers from the associated unit boardsto the associated shutdown boards are OPERABLE and can beclosed from the control room. This action is allowed since theremaining qualified offsite circuit continues to provide Power to allthe shutdown boards. In addition.

once CSST A or B is "alianed."

itE-1 20 of 48 ATTACHMENT 2Proposed TS Bases Changes (Mark-Ups) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued) is capable of beinq manually connected to the associated shutdownboards (either Train A or Train B shutdown boards) by control roompersonnel Furthermore, the inoperable offsite circuit must be restored toOPERABLE status within 14 days. This can be accomplished b'either restoring the normal circuit (CSST C or D) to OPERABLEstatus, or by utilizing the LCO Note 2 allowance.

LCO Note 2 allowsCSST A or B to replace one of the normal qualified offsite circuits, provided either: a) CSST A or B is providing power to the associated shutdown board (i.e., it is physically tied, througqh the unit boards, tothe associated shutdown boards);

or the associated shutdownboards are powered from the associated USST (throucih the unitboards) and the automatic transfer capability from the USST to theCSST is OPERABLE.

Once this LCO Note 2 requirement is met,CSST A or B is allowed to meet the LCO 3.8. l.a requirement andthus, the requirement for two qualified circuits is being met. The 14-day completion time is acceptable durinq this additional time periodsince the remaining OPERABLE qualified circuit continues toprovide offsite power to the shutdown boards and either CSST A orB is available to provide a second source of qualified offsite power,througjh the manual operation of circuit breakers from the controlroom.E-1 21 of 48 ATTACHMENT 2Proposed TS Bases Changes (Mark-Ups) for WBN Unit 1AC Sources -Operating B 3.8.1BASES (continued)

ACTIONS H.1 and 1.1(continued)

Condition H and Condition I corresponds to a level of degradation in which allredundancy in the AC electrical power supplies cannot be guaranteed.

At thisseverely degraded level, any further losses in the AC electrical power system willcause a loss of function.

Therefore, no additional time is justified for continued operation.

The plant is required by LCO 3.0.3 to commence a controlled shutdown.

SURVEILLANCE The AC sources are designed to permit inspection and testing of all important REQUIREMENTS areas and features, especially those that have a standby function, in accordance with 10 CFR 50, Appendix A, GDC 18 (Ref. 8). Periodic component tests aresupplemented by extensive functional tests during refueling outages (undersimulated accident conditions).

The SRs for demonstrating the OPERABILITY ofthe DGs are in accordance with the recommendations of Regulatory Guide 1.9(Ref. 3) and Regulatory Guide 1.137 (Ref. 9), as addressed in the FSAR.Where the SRs discussed herein specify voltage and frequency tolerances, thefollowing is applicable.

6800 volts is the minimum steady state output voltageand the 10 second transient value. 6800 volts is 98.6% of the nominal busvoltage of 6900 V corrected for instrument error and is the upper limit of theminimum voltage required for the DG supply breaker to close on the 6.9 kVshutdown board. The specified maximum steady state output voltage of 7260 Vis 110% of the nameplate rating of the 6600 V motors. The specified 3 secondtransient value of 6555 V is 95% of the nominal bus voltage of 6900 V. Thespecified maximum transient value of 8880 V is the maximum equipment withstand value provided by the DG manufacturer.

The specified minimum andmaximum frequencies of the DG are 58.8 Hz and 61.2 Hz, respectively.

Thesevalues are equal to +/- 2% of the 60 Hz nominal frequency and are derived fromthe recommendations given in Regulatory Guide 1.9 (Ref. 3).SR 3.8.1.1This SR ensures proper circuit continuity for the offsite AC electrical powersupply to the onsite distribution network and availability of offsite AC electrical power. The breaker alignment verifies that each breaker is in its correct positionto ensure that distribution buses and loads are connected to their preferred power source, and that appropriate independence of offsite circuits is maintained.

When the allowance of LCO Note 2 is being used, this SR also includesverifying CSSTA or B (as applicable) is only aligned to provide power to itsnormal unit and RCP boards. The 7 day Frequency is adequate since breakerposition is not likely to change without the operator being aware of it andbecause its status is displayed in the control room.IE-1 22 of 48 ATTACHMENT 2Proposed TS Bases Changes (Mark-Ups) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

SURVEILLANCE SR 3.8.1.7REQUIREMENTS (continued)

See SR 3.8.1.2.SR 3.8.1.8Transfer of each 6.9 kV shutdown board power supply from the normal offsitecircuit to the alternate offsite circuit demonstrates the OPERABILITY of thealternate circuit distribution network to power the shutdown loads. Similarly, ifCSST A or B is beinq used to meet LCO 3.8.1.a as allowed by LCO Note 2.then the manual transfer from CSST A or B (whichever is being used) to thenormal offsite circuit (CSST C or D (as applicable),

demonstrates theOPERABILITY of the associated CSST A or B offsite circuit to power theshutdown loads. In addition, if the USST is bein-g used to provide power tothe shutdown boards, then automatic transfer capability from the USST tothe associated CSST (A or B) must also be tested. This required portion ofthe Surveillance Requirement demonstrates power can be provided by therequired CSST A or B (as applicable),

if power is being initially provided bythe USST (i.e., the provision described in part b of LCO Note 2).The 18 month Frequency of the Surveillance is based on engineering

judgment, taking into consideration the plant conditions required to perform theSurveillance, and is intended to be consistent with expected fuel cycle lengths.Operating experience has shown that these components usually pass the SRwhen performed at the 18 month Frequency.

Therefore, the Frequency wasconcluded to be acceptable from a reliability standpoint.

This SR is modified by a Note. The reason for the Note is that, during operation with the reactor critical, performance of this SR could cause perturbations to theelectrical distribution systems that could challenge continued steady stateoperation and, as a result, plant safety systems.

Credit may be taken forunplanned events that satisfy this SR. Examples of unplanned events mayinclude:1) Unexpected operational events which cause the equipment to performthe function specified by this Surveillance, for which adequatedocumentation of the required performance is available; and2) Post corrective maintenance testing that requires performance of thisSurveillance in order to restore the component to OPERABLE, providedthe maintenance was required, or performed in conjunction withmaintenance required to maintain OPERABILITY or reliability.

E-1 23 of 48 ATTACHMENT 3Proposed TS Changes (Final Typed) for WBN Unit IAC Sources -Operating 3.8.13.8 ELECTRICAL POWER SYSTEMS3.8.1 AC Sources -Operating LCO 3.8.1The following AC electrical sources shall be OPERABLE:

a. Two qualified circuits between the offsite transmission network and theonsite Class 1 E AC Electrical Power Distribution System; andb. Four diesel generators (DGs) capable of supplying the onsite Class 1 E ACElectrical Power Distribution System.----------------------

NOTES --------------------------

1. The C-S DG may be substituted for any of the required DGs.2. Common Station Service Transformer (CSST) A or B may be used to meetone of the two qualified offsite circuit requirements of LCO 3.8.1, providedCSST A or B is only providing power to its normal unit and reactor coolantpump (RCP) boards, and:a. CSST A or B is providing power to the associated shutdown boarddivision; orb. The associated shutdown board is being powered by the UnitStation Service Transformer (USST) and automatic transfercapability from the USST to CSST A or B (as applicable) isOPERABLE.

APPLICABILITY:MODES 1, 2, 3, and 4.ACTIONS------------------------------------------

NOTE--------------------------------------------------

LCO 3.0.4.b is not applicable to DGs.CONDITION I REQUIRED ACTIONI COMPLETION TIMEA. One offsite circuitinoperable.

A.1Perform SR 3.8.1.1 forOPERABLE offsite circuit.1 hourANDOnce per 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months sthereafter (continued)

ANDE-1 24 of 48 ATTACHMENT 3Proposed TS Changes (Final Typed) for WBN Unit IAC Sources -Operating 3.8.1CONDITION I REQUIRED ACTION I COMPLETION TIMEA.2Declare requiredfeature(s) with no offsitepower available inoperable when it'sredundant requiredfeature(s) is inoperable.

ANDA.3.1 Restore offsite circuit toOPERABLE status.ORA. 3.2.1 Align backup offsite circuitCSST A or CSST B torequired shutdown board.ANDA.3.2.2 Restore offsite circuit toOPERABLE status.24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months fromdiscovery of no offsitepower to one trainconcurrent withinoperability ofredundant requiredfeature(s) 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months sAND6 days fromdiscovery of failure tomeet LCO72 hoursAND6 days fromdiscovery of failure tomeet LCO14 days(continued)

E-1 25 of 48 ATTACHMENT 3Proposed TS Changes (Final Typed) for WBN Unit IAC Sources -Operating 3.8.1SURVEILLANCE FREQUENCY SR 3.8.1.7 Verify each DG starts from standby condition 184 daysand achieves in < 10 seconds, voltage _> 6800 V,and frequency

>_ 58.8 Hz. Verify after DG faststart from standby conditions that the DGachieves steady state voltage > 6800 V and <7260 V, and frequency

_> 58.8 Hz and <_ 61.2 Hz.SR 3.8.1.8 -------------------

NOTE-----------------

For the 1A-A and 1B-B Shutdown Boards, thisSurveillance shall not be performed in MODE 1 or 2.However, credit may be taken for unplanned eventsthat satisfy this SR.18 monthsVerify the following:

a. Automatic and manual transfer of each 6.9 kVshutdown board power supply from the normal offsitecircuit to the alternate offsite circuit;b. Automatic transfer of the associated 6.9 kV shutdownboard power supply from the USST to the associated CSST A or B, when USST is powering the associated shutdown board and CSST A or B is credited withmeeting LCO 3.8.1.a requirements; andc. Manual transfer of the associated 6.9 kV shutdownboard power supply from the associated CSST A or B tothe normal offsite circuit (CSST C or D, as applicable),

when CSST A or B is credited with meeting LCO 3.8.1.arequirements.

(continued)

E-1 26 of 48 ATTACHMENT 4Proposed TS Bases Changes (Final Typed) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

APPLICABLE SAFETY ANALYSESThe initial conditions of DBA and transient analyses in theFSAR, Section 6 (Ref. 4) and Section 15 (Ref. 5), assume ESF systems areOPERABLE.

The AC electrical power sources are designed to provide sufficient

capacity, capability, redundancy, and reliability to ensure the availability ofnecessary power to ESF systems so that the fuel, Reactor Coolant System(RCS), and containment design limits are not exceeded.

These limits arediscussed in more detail in the Bases for Section 3.2, Power Distribution Limits;Section 3.4, Reactor Coolant System (RCS); and Section 3.6, Containment Systems.The OPERABILITY of the AC electrical power sources is consistent with theinitial assumptions of the Accident analyses and is based upon meeting thedesign basis of the plant. This results in maintaining at least two DG'sassociated with one load group or one offsite circuit OPERABLE during Accidentconditions in the event of:a. An assumed loss of all offsite power or all onsite AC power; andb. A worst case single failure.The AC sources satisfy Criterion 3 of NRC Policy Statement.

LCOTwo qualified circuits between the Watts Bar Hydro 161 kV switchyard and theonsite Class 1E Electrical Power System and separate and independent DGs foreach train ensure availability of the required power to shut down the reactor andmaintain it in a safe shutdown condition after an anticipated operational occurrence (AOO) or a postulated DBA.Qualified offsite circuits are those that are described in the FSAR and are part ofthe licensing basis for the plant.Each offsite circuit must be capable of maintaining acceptable frequency andvoltage, and accepting required loads during an accident, while connected to the6.9 kV shutdown boards.Offsite power from the Watts Bar Hydro 161 kV switchyard to the onsite Class 1 Edistribution system is normally from two independent immediate access circuits.

Each of the two circuits is routed from the switchyard through a 161 kVtransmission line and 161 to 6.9 kV transformer (common station servicetransformers) to the onsite Class 1 E distribution system. The medium voltagepower system starts at the low-side of the common station service transformers.

IE-1 27 of 48 ATTACHMENT 4Proposed TS Bases Changes (Final Typed) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

LCO Each DG must be capable of starting, accelerating to rated speed and voltage,(continued) and connecting to its respective 6.9 kV shutdown board on detection of loss-of-voltage.

This will be accomplished within 10 seconds.

Each DG must also becapable of accepting required loads within the assumed loading sequenceintervals, and continue to operate until offsite power can be restored to the 6.9 kVshutdown boards. These capabilities are required to be met from a variety ofinitial conditions such as DG in standby with the engine hot and DG in standbywith the engine at ambient conditions.

Additional DG capabilities must bedemonstrated to meet required Surveillances, e.g., capability of the DG to revertto standby status on an accident signal while operating in parallel test mode.Proper sequencing of loads, including tripping of nonessential loads, is a requiredfunction for DG OPERABILITY.

Note 1 has been added to indicate that the C-S DG may be substituted for any ofthe required DGs. However, the C-S DG cannot be declared OPERABLE until itis connected electrically in place of another DG, and it has satisfied applicable Surveillance Requirements.

The AC sources in one train must be separate and independent (to the extentpossible) of the AC sources in the other train. For the DGs, separation andindependence are complete.

For the offsite AC sources, separation and independence are to the extentpractical.

A circuit may be connected to more than one ESF bus, with fasttransfer capability to the other circuit OPERABLE, and not violate separation criteria.

A circuit that is not connected to an ESF bus is required to haveOPERABLE fast transfer interlock mechanisms to at least two ESF buses tosupport OPERABILITY of that circuit.A second Note has been added to allow common station service transformer (CSST) A or B to be used to meet one of the two qualified offsite circuitrequirements of LCO 3.8. 1.a. CSSTs A and B directly power the unit boards,and through feeder breakers between the unit boards and the shutdown boards,can provide power to the shutdown boards required by LCO 3.8.9, "ACDistribution."

The Note allows one of the two CSSTs (A or B) to replace thenormal qualified offsite circuit supply (CSST C or D), provided the CSST is onlyproviding power to its normal unit and reactor coolant pump (RCP) boards, andeither a) CSST A or B (as applicable) is providing power to the associated shutdown board; or b) the associated shutdown board is being powered by theunit station service transformer (USST) and automatic transfer capability from theUSST to CSST A or B (as applicable) is OPERABLE.

This allowance isacceptable since CSST A and B are capable of providing the proper voltage andfrequency to the class 1 E shutdown boards. In addition, all necessary unitboards and breakers necessary to provide power to the required shutdownboards are required to be OPERABLE and are part of the CSST A or B qualified circuit.E-1 28 of 48 ATTACHMENT 4Proposed TS Bases Changes (Final Typed) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

ACTIONS A.3.1, A.3.2.1, and A.3.2.2(continued)

According to Regulatory Guide 1.93 (Ref. 6), operation may continue inCondition A for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . With one offsite circuitinoperable, the reliability of the offsite system is degraded, and the potential for aloss of offsite power is increased, with attendant potential for a challenge to theplant safety systems.

In this Condition,

however, the remaining OPERABLEoffsite circuit and DGs are adequate to supply electrical power to the onsiteClass 1E Distribution System.The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time takes into account the capacity and capability ofthe remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.The second Completion Time for Required Action A.3 establishes a limit on themaximum time allowed for any combination of required AC power sources to beinoperable during any single contiguous occurrence of failing to meet the LCO. IfCondition A is entered while, for instance, a DG is inoperable and that DG issubsequently returned

OPERABLE, the LCO may already have been not met forup to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . This could lead to a total of 144 hours0.00167 days 0.04 hours 2.380952e-4 weeks 5.4792e-5 months , since initial failure to meetthe LCO, to restore the offsite circuit.

At this time, a DG could again becomeinoperable, the circuit restored

OPERABLE, and an additional 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months (for atotal of 9 days) allowed prior to complete restoration of the LCO. The 6 dayCompletion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO. This limit is considered reasonable forsituations in which Conditions A and B are entered concurrently.

The "AND"connector between the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and 6 day Completion Times means that bothCompletion Times apply simultaneously, and the more restrictive Completion Time must be met.As in Required Action A.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."This will result in establishing the "time zero" at the time that the LCO wasinitially not met, instead of at the time Condition A was entered.Alternately, in lieu of restoring the inoperable circuit to OPERABLE status in 72hours, required Action A.3.2.1 requires aligning the backup offsite circuit CSST Aor B to the required shutdown board within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . This is accomplished byensuring power is available to CSST A or B, and that the breakers from CSST Aor B to the associated unit boards are OPERABLE and can be closed from thecontrol room, and the breakers from the associated unit boards to the associated shutdown boards are OPERABLE and can be closed from the control room. Thisaction is allowed since the remaining qualified offsite circuit continues to providepower to all the shutdown boards. In addition, once CSST A or B is "aligned,"

itis capable of being manually connected to the associated shutdown boards(either Train A or Train B shutdown boards) by control room personnel.

Furthermore, the inoperable offsite circuit must be restored to OPERABLE statuswithin 14 days. This can be accomplished by either restoring the normal circuit(CSST C or D) to OPERABLE status, or by utilizing the LCO Note 2 allowance.

LCO Note 2 allows CSST A or B to replace one of the normal qualified offsiteE-1 29 of 48 ATTACHMENT 4Proposed TS Bases Changes (Final Typed) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)

circuits, provided either: a) CSST A or B is providing power to the associated shutdown board (i.e., it is physically tied, through the unit boards, to theassociated shutdown boards);

or the associated shutdown boards are poweredfrom the associated USST (through the unit boards) and the automatic transfercapability from the USST to the CSST is OPERABLE.

Once this LCO Note 2requirement is met, CSST A or B is allowed to meet the LCO 3.8.1.a requirement and thus, the requirement for two qualified circuits is being met. The 14-daycompletion time is acceptable during this additional time period since theremaining OPERABLE qualified circuit continues to provide offsite power to theshutdown boards and either CSST A or B is available to provide a second sourceof qualified offsite power, through the manual operation of circuit breakers fromthe control room.E-1 30 of 48 ATTACHMENT 4Proposed TS Bases Changes (Final Typed) for WBN Unit IAC Sources -Operating B 3.8.1BASES (continued)