ML20199A404

Application for Amends to Licenses NPF-68 & NPF-81,adding Conditions for DGs for Extended DG Completion Time of Fourteen Days

ML20199A404
Person / Time
Site:	Vogtle
Issue date:	01/22/1998
From:	Mccoy C SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20199A407	List: ML20199A404 ML20199A413
References
LCV-1111, TAC-M96769, TAC-M96770, NUDOCS 9801270208
Download: ML20199A404 (31)

Text

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o C. K. McCoy Southore Nuclear Vee President Operating Company. inc.

Vogue Projuct 4 inverness Center Pa4way PO Box 1795 Bmiwfant Alabane 35701 Tel 205 4921172 Ian 7% 932 003 SOUTHERN COMPANY January 22,1998 LCV 1111 Docket Nos. $0 424 50-425 TAC Nos. M96769 M96770 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D.C. 20555 Vogtle Electric Generating Plant Response to Request for Additional!nformation and Request to Revise Technical Specifications, "AC Sources Operating" Emergency Diesel Gencrator Extended AUT Reauest Ladies and Gentlemen:

In accordance with the provisions of 10 CFR 50.90, Southern Nuclear Operating Company (SNC) hereby proposes to amend the Vogtle Electric Generating Plant (VEGP) Unit i and Unit 2 Technical Specifications (TS), Appendix A to Operating licenses NPF-68 and NPF 81 Ily letter LCV 0603 S dated September 13,1996, Georgia Power Company requested that the Technical Specification conversion process e-d approval be separated from the pursuit of an emergency diesel generator (EDG or DG) cxtended allowed outage time (AOT) and that it remain on the docket as submitted by letter LCV 0603 R, dated August 23,1996. In addition, letter LCV 0970 was issued as an interim response to the additional information requested by 3

the NRC by letter dated November 7,1996," Request For Additional Information (RAl)

Regarding Extended Allowed Outage Times for the Emergency Diesel Generators VEGP Unit I and 2, TAC Nos. M96769 and M96770." in order to avoid any confusion with the numerous previous submittals on this subject, all previous written or verbal commitments associated with o\

that prior request including the interim response to the RAI are volded and superseded by this [

letter, attachments, and any subsequent related correspondence. In this new submittal, SNC has supplied the additional information requested by the NRC by the November 7,1996 RAl.

g it is noteworthy that the facility operating liccase was transferred from Georgia Power Company to Southern Nuclear Operating Company on March 22,1997. For case of reference, the previous licensee, Georgia Power Company, is henceforth known as Southern Nuclear Operating Company.

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9901270208 900122 PDR ADOCK 05000424 P PDRs

U. S. Nuclear Rcgulatory Commission Page 2 LCW1111 1he change and basis for the change reques: to the Technical Specifications is provided in Enclosure 1. The supportingjustification and significant hazards evaluation pursuant to 10 CFR 50.92 are provided in Enclosure 2. liased upon the analysis provided. Southern Nuclear Operating Company (SNC) has determined the proposed changes to the Technical Specifications do not involve a significant hazards consideration as defined by 10 CFR $0.92 and will not significantly affect the quality of the environment. Enclosure 3 provides SNC's responses to the RAl. Instructions for the incorporation of the proposed changes are provided in Enclosure 4. A clean typed and hand marked copy of the Technical Specification and 11ases changes are provided in Enclosure 5.

The justification for the use of an EDO extended AOT is based upon a risk infonned deterministic evaluation consisting of three main elements: 1) the availability of the standby auxiliary transformer (SAT), a third ofTsite power source; 2) verification that the combustion turbine electrical power generation of Plant Wilson is functional and sufficiently reliable to provide assurance ofit's black start generation capability, and/or the option of starting and running of a CTO during the extended AOT; and 3) the implementation of a configuration risk management program (CRh1P) at VEGP while the EDO is in an extended AOT. These elements provide adequate justification for approval of this requested TS change by providing high assurance of the capability to provide power to the VEOP emergency safety buses during the EDO extended AOT. Southern Nuclear Operating Company also requetts approval of this T/S change by September 1,1998, to support procedural changes and work planning necessary to accomplish EDO maintenance activities prior to the Unit 1 Spring 1999 refueling outage.

. A copy of these proposed changes is being sent to hir. J. D. Tanner, the Georgia State Designee, in accordance with 10 CFR 50.91(b)(1),

hir. C. K. hicCoy states he is vice president of SNC, is authorized to execute this oath on behalf of SNC, and to the best of his knowledge and belief, the facts set forth in this letter are true.

Sincerely, L K. hicCoy

. $f' Sworn to and subscribed before me this //c* day of MA k*7 1998 v

&Y. k Notary Public

(- hiy Commission Expires: ,

% ( /f7) #

Enclosures and distribution: (next page) -

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U. S. Nuclear Rigulatory Commission Pag) 3 TC Willl

Enclosures:

1. Change and 11 asis for Change Request

2. Justification and 10 CFR 50.92 Evaluation

3. Response to Request for Additional Infor: nation Table 1 "CDF Variables used in EDO Extended AOT Justi0 cation Calculations" Table 2 "EDO Extended AOT Risk Management Guidelines"and Attachment

4. TS and 13ases Changes insertion Instructions

5. Clean Typed and lland Marked Pages cc: Southern Nucler.r Operating Comnany Mr. J.11. licasley, General Manager, VEGP Mr. M. Sheibani NSAC Supervisor, VEGP NORMS U. S. Nudcar Regulatory Commisslan Mr. L A. Reyes, Regional Administrator Mr. D. II. Jaffe, Senior Project Manager, NRR Mr. John Zeller, Senior Resident inspector, VEGP State of Georgig J. D. Tanner, Commissioner, Department of Natural Resources Ol/15N811:16 AM S WOOTtJWOG111 KVE\TI Cl lSPIUl 4DYIX111A1 CV i l l t . DOC -

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Enclotre i Vogtle Electric Generating Plant Request to Revise Technical Specifications,"/.C Sources - Operating" Enttrgtary31ttel Generator Entended AOT Reautti Change and Baala for Change Reautat 1

Pippsted Change - Addition ofEDG EstengleglAQI This submittal proposes to add Conditions to the VEGP Technical Specification for the diesel generators (DGs) for an extended DG Completion Time of 14 days. The proposed EDO extended AOT is conditional upon the main elements 1) availability of an additional qualified offsite power circuit, th 13.8/4.16 kV Standby Auxiliary Transformer (SAT) fed from Georgia Power Company's Plant Wilson,2) verification that the combustion turbine electrical power generation of Plant Wilson is functional and sufficiently reliable to provide assurance ofit's black start generation capability, and/or the option of starting and running of at least one combustion turbine generator during the EDO extended AOT, and 3) the use of a configuration risk management program (CRMP) during the DG extended AOT. While an EDO is out of service, if the SAT is not available or becomes unavailable, or the combustion turbine electrical generation of Plant Wilson becomes inadequate or unavailable, the inoperable EDG (or SAT) must be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

SpecUlc TS C%unges SAT Avallabillly A new required action B.2 is being added along with the existing Condition 11 required actions for one DG inoperable, to verify the availability of the SAT within I hour and once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafler, and restore the DG to operable status within 14 days from discovery -

of failure to meet the LCO.

Camlluallon_Isrbine Electrical Power Generation A new required action B,5.1 is being added to verify that the combustion turbine electrical power generation capability of Plant Wilson is functional and sufTiciently reliable to provide assurance of black start generstion capability within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entry into Condition D or within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> prior to entry into Condition B.

A new required action B.S.2 is being added for utilization when the combined combustion turbine generator (CTG) enhanced black start reliability falls below the required criteria.

This condition allows the option to start or run at least one of the combustion turbine generators (CTGs) at Plant Wilson within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of entry to Condition B, or prior to entry into Condition B for preplanned maintenance.

CRatP Inmi tanentaden A section 5.5.18," Configuration Risk Management Program (CRMP)" is being added to the Administrative section of the TS. This section discusses the program description and use.

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Etciostre !

Yogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sources - Operating" Entrgtacy Diesel Genera (gr_ElitAded AOT Requtal Otangt.andjmala for Chance Regut11 Mistellantans A new condition C is being added for when one DG is inoperable and the required actions and completion times of B.2 are not met, i.e the SAT is not verified to be available or ,

becomes unavailable as an offsite source, or the required actions and completion times of B.5 associated with CTG operation and/or reliability are not met, then restore the DG to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Other changes associated with 3.8.1 conditions, required actions, or completion times are only the result of re. numbering due to the addition of the new condition and required actions of the DG extended AOT and do not reflect a change to operating requirements.

LShascLGlanges SAT.Atallability Add the bases for Required Action B.2 concerning SAT availability. The SAT is considered to be available when it meets the following criteria:

e Operable in accordance with plant procedures; e Not already being applied to any of the four 4,16 kV ESF buses for Units 1 and 2 in accordance with Specification 3.8.1 as either an ofTsite source or to meet the requirertents of an I.CO 3.8.1 Condition; e Not providing power to the other unit when that unit is in MODE 5 or 6 or defueled.

Furthermore, the SAT can be applied to only one of the four 4.16 kV ESF buses at any given time for Units 1 and 2 to meet the requirements of an LCO 3.8.1 Condition.

Combustion Turbine Eltthical Power Generatian The bases for Required Action B.S.1 and B.S.2 is added to describe the method of determining the status of combustion turbine generation at Plant Wilson. The bases for these required actions describe the following:

• Testing utilized to capture reliability data for the enhanced black start CTGs and associated bhek. start DG at Plant Wilson.

Enclos:re i Vogtle Electric Generating Plant Request to Revise Technical Speelfications,"AC Sources Operating" Einergency Diesel Generator hiended AOT Rengggi Chamee and hd= for Chamee Reauest

• The option of starting and running a CTO which allows the utilization of the EDG cxtended AOT when the CTO combined reliability is unknown or falls below the necessary criteria of greater 16 m or equal to 95%.

CRMP Imp!tmentallen Add the bases for Required Action U.6 concerning the use of a CRMP and how its use provides an appropriate level of assurance that risk significant activities with an unacceptable risk achievement worth will be minimized during an extended DG AOT. The CRMP will be used to assess changes in core damage frequency from the following applicable plant configurations:

• When a DG is intentionally taken out of service for a planned activity excluding short duration activities (e.g., performing an air roll on the EDG prior to a routine

- surveillance).

• When unplanned maintenance or repairs require the DG to be taken out of service.

ReaLonfor PropnedEhmigCL The intent of the EDG extended allowed outage time is to increase the flexibility should an unexpected condition occur with the EDGs requiring extensive corrective maintenance, and also to allow normal EDG preventis e maintenance to be performed separate from unit refueling outages. During non refueling EDO outages manpower and resources can concentrate on EDG activities thereby allowing a more effective allocation of plant resources to safety significant tasks during refueling outages. An extended DG AOT would also provide increased operational and maintenance flexibility and avert possible unit shutdowns or a need for exigent TS relief.

Actions will be taken to limit the time in any Limiting Condition for Operation TS Required Action Completion Time and therefore limit the EDG unavailability. Other than ten (10) year autage inspections, fourteen (14) days has been determined to be a sufficient amount of time to perform normal preventive DG inspections and maintenance requiring disassembly of the EDG and to perform maintenance and operability tests required to return the DG to OPERABLE status. No changes in DG surveillance testing mode requirements have been identified as necessary. The current TS allow all normal DG maintenance and operability testing to occur during power operation. Certain DG surveillance tests such as Engineered Safeguards Features Actuation System (ESPAS) testing will continue to be perfonned during refueling outages, but should not prevent the IX) from being returned to service during full power operations following normal preventive maintenance.

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1%elos:re !

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Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sources . Operating"  !

Emerr.cacy_DitatLGratratarlAttaded AOT Regunt Gange.and llaah for Cliange Regutti BAS]S FOR CJMNGE REQUEST SA TPower Sntre.mndfinLH)) son _ Combustion Turbine Generalkn Design The SAT is a " swing" or conimon offsite power circuit capable of connecting to any 4.16 kV ESF bus on either VEGP unit. The 13.8 kV Wilson underground line and SAT provide a new source of offsite power for VEGP that meets the capacity and capability requirements of 10 CFR 50 Appendix A, GDC 17. 'ihe SAT capacity of 10/12.5 MVA provides shutdown capability in excess of one ESF bus requirements and exceeds the rating of one DG at 7000 kW.

'ihe SAT is supplied power through a direct buried cable from either the Southern Electric System 230 kV grid or from any combination of Plant Wilson's (6) 60 MVA units of combustion turbine generators (CTO). Regardless ofits power source connection (transmission grid or combustion turbine generation of plant Wilson), the SAT is not normally connected to any of VEGP's normal or alternate offsite power sources, or any of the VEGP onsite er.iergency AC power sources.

Plant Wilson is a completely self sumclent, independent electrical generation facility. Plant _

Wilson has no common auxiliary power, fuel, equipment, or shared systems and/or components with VEGP. In addition, two of the Plant Wilson combustion turbines (CTA and CTil) have an enhanced black start capability (can be started without offsite power) and will be maintained to assure that the combustion turbine electrical power generation of Plant Wilson is functional and sumciently reliable to provide adequate assurance ofit's black start generation capability. If the reliability is not sumcient, the option of starting and running of a CT during the extended AOT can otso provide adequate assurance of the capability to provide power to the VEGP emergency safety buses during the EDO extended AOT. Any of these methods of supplying power to the SAT utilize the Plant Wilson switchyard 13.8 kV power system, llowever, the VEGP and Wilson switchyards are separated by approximately one mile, adding to the defense in-depth design for reducing the likelihood of a single event affecting both facilities.

Therefore, the addition of the SAT line as a third offsite power source along with its back up abundant and independent combustion turbine generation ctpability results in improved availability and recovery time of offsite power to the ESF buses at VEGP and provides sumcient compensation for a DG extended AOT.

CRMPimnitatalathn ,

The configuration risk management program (CRMP) will be used when a DG is intentionally taken out of service for a planned activity excluding short duration activitics (e.g., performing an air roll on the EDO prior to a routine surveillance). In addition, the CRMP will be used when unplanned maintenance or repairs require an extended DG AOT.

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l Enclos:re I  ;

Yog,le Electric Generating Plant  !

Hequest to Hevise Techalcal Specifications,"AC Sources . Operating" i Latratacy_DicacLGeneraint.LatadedADI_Regutal i

Change _and_Itaaltfor Change.Regutal The Levels associated with PRA models as utilized in a CRMP are described as follows. A Level  :

I PRA model supports the determination of core damage frequency (CDF). A Level 2 PRA l model supports the determination of CDF and large early release (LERF). A Level 3 PRA model supports the determination of CDF, LERF, and conseqt.ences of a containment breach.

The CRMP integrates the capabilities of VEGP Equipment Out Of Service (EOOS) risk monitor, ,

hereafter referred to as EOOS, which utillies Level 1, at power, internal events PRA informed methmlology. EOOS provides planning and scheduling strategies to maximite equipment ,

performance, reliability, and availability during the EDO (xtended AOT.

The VEOP probabilistic risk assessment (PRA) forms the basis for the VEGP EOOS quantification engine. Ilowever, unlike the VEGP PRA, the EOOS quantification engine evaluates configuration specific instantaneous core damage frequency (CDF). The VEGP PRA model is periodically updated to reflect plant changes. The EOOS quantification engine is updated following an update of the VEGP PRA model. Since all plant equipment and interactions are not modeled in the EOOS software, the EOOS calculation is not the only input to safety assessment development.1he CRMP will also have provisions to considtr other applicable risk significant contributors, such as Level 2 issues and external events, qualitatively or quantitatively, llowever, the qualitative assessment of the entire work scope by trained and 1 experienced personnel will continue to be a key element in assuring that VEGP scheduled work does not place the plant in an unsafe condition.

Equipment Out Of Service (EOOS), will be used by the VEOP CentrSI Scheduling Group to support the safety assessment for scheduled EDO maintenance. As part of the Plan of the-Day (l" 0) Report, a list of affected equipment and scheduled maintenance dates is generated. This ,

L ' led i maintenance information will be used as an input to EOOS, and the resulting EOOS otn;w will be used by central scheduling personnel in developing a safety assessment of scheduled EDG maintenance. Vogtle Electric Generating Plant intends to continue the current preferred practice of removing from service for maintenance only one safety significant system at a time. The Central Scheduling personnel will apprise plant management of risk insights generated using EOOS. Selected plant personnel including central scheduling personnel have undergone, or will undergo, the necessary training on PRA concepts and applications, EOOS development and use.

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Enclosure 2  :

Vogtle Electric Generating Plant Request to Revise Technical Speciflentions,"AC Sources Operating" Esaturacy Dienel Generalothitaded AOT Reautat Jg3115cadam and 10 CFR 90.92 Evaluation l'ropeard.fhangt and.Hackground 1his submittal proposes to revise the VEGP Technical Specification for the diesel generators (DGs) to allow an extended DG Completion Time of 14 days. In addition, a new Condition will be added requiring restoration of an inoperable EDG in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in the event that the SAT is unavailable, or the electrical power generation capability of Plant Wilson becomes unavailable or unreliable during the time that an EDO is out of service. The proposed changes are based on  :

three main elements: 1) the availability of the recently installed qualified offsite circuit, the {

13.8/4.16 LV Standby Auxiliary Transformer (SAT) fed from the Georgia Power Company's Plant Wilson; 2) verification that the combustion turbine electrical power generation of Plant Wilson is functional and sufliciently reliable to provide assurance ofit's black stari generation l capabilhy, and/or the option of starting and running of at least one combustion turbine generator during the EDO extended AO ft and 3) the use of a configuraHon risk management program (CRMP) during the DG extended A0T. ,

JMiTIFICATION

,r 'trJulalalle and Tradlilunal Engineerlag Evaluations SA TA vailability. Functlan. Canackte. and Cavabilite

'Ihe purpose of the DGs is to be an onsite standby power source upon the loss of preferred offsite power tources (normal and/or alternate). Upon an LOSP the engineered safeguards features electrical loads are automatically connected to the DGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of a design basis accident such as loss of ,

coolant accident. The accident loading of one 4160 volt Class IE bus is less than 7.3 MVA (maximum). The SAT is rated at 10/12.5 MVA and Plant Wilson hrs six (6) 60 MVA CT generators. Ilased upon analysis and further verified by field data and test results at both Wilson and Vogtle, the 10/12.5 MVA SAT and interconnection with Plant Wilson conforms to position 11.4 of Branch Technical Position llTP PSB.l. The testing demonstrated the capacity and capability of the Vogtle/ Wilson interconnection through the SAT to be able to start and feed one train of-ngineered safety features systems (ESFAS) electrical loads from either the Wilsm 230 kV switchyard, or from at least one (1) CT generator, while meeting voltage and frequetcy requirements.

The SAT is normany energired continuously via the Southern Electric System grid at Plant LWilson, but the SAT remains normally unloaded and not connected to any Vogtle loads, llowever, if the SAT were not energized from the grid, and required receiving power solely from Plant Wilson CT generation, the onsite Plant Wilson CT fuel storage capacity could limit the duration CT(s) could maintain the SAT energli.ed. Plant Wilson CT fuel supply and inventory will be added to the administrative precautionary measures required to be verified prior to entry into an EDO extended AOT. Plant Wilson fuel procurement and inventory will be controlled by VEGP personnel to ensure the onsite CT fuel capacity will be kept well above the requirements needed for the safe shutdown of Vogtle during an EDG extended AOT . The onsite Plant Wilson CT fuel storage capacity is approximately 10 million gallons. Average CT fuel consumption is

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E: clos:re 2  ;

Vogtle Electric Generating Plant Request to Revise Technical Speelfications,"AC Sources - Operating" EtattgentLDiesel Gentalarlattaded AOT Renutal Juillfitailon.and 10 C FR 50.92 Evaluation 5

6,000 gallons per hour. Normal CT onsite fuel storage is 3 to 4 million gallons which is sufHcient to supply fuel for all 6 cts to run, fully loaded, for approximately 4 consecutive days.

Since Plant Wilson's six (6) cts, each rated at approximately 60 MVA, are utilized primarily for peaking purposes, suf0clent CT fuel is maintained during the peaking seasons to allow all of the units to run for extended periods of time. The safe shutdown loading of one train is well below the operating rating of one CT, ther efore requiring only one CT to run at a very light load for VEGP safe shutdown purposes.

L'EGEandffantJUlmtindcoritdence

• Plant Wilson is a completely self sufucient, independent electrical generation facility with no common auxiliary power, fuel, aquipment, or shared systems and/or components with VEGP, thereby reducing common cause failures.

Cl'BlacLSIatulesisnEnabilk 1hc Plant Wilson black start capability is provided via a diesel generator which supplies power for cranking one of the two enhanced black start combustion tmbines (CTA & CTB) and essential station service. For purposes of accelerating the turbines to a sufficient speed from which the combustible Osel ignitors ignite and continue with the turbine rotation acceleration, two 600 hp " cranking / starting" motors are necessary for each CT in order for electrical generation to begin. With Plant Wilson's six cts, the facility has a total of ' cranking motors, ,

and one 2.5 MW dicsci pnerator. When one CT has begun to generate, one or all of the remaining cts may be started from the generation of the original black started CT, During normal Plant Wilson operation, station service ccatrol and power (speciucally the cranking motors)is supplied from Southern Electric System grid. Therefcre, the Plant Wilson diesel generator is not normally utilized for supporting the start of the cts.

[lntCllnfs10fPOWCrRntornflon Per 10 CI R 50.2, Station illackout (SHO) is denned as "the complete loss of alternating current

- (ac) electrical power to the essential and non essential switchgear busses in a nuclear power plant 11.c., loss of offsite electric power system concurrent with turbine trip and unavailability of the onsite emergency ac power system). Station blackout does not include the loss of available ac power to busses fed by station batteries through batteries inverters or by alternate ac sources as denned in this section, .... " With an SB0 at VEGP and the Plant Wilson switchyard energized, the SAT power feed circuit provides an additional and diverse connection to the Soml.ern Electric System grid.1he S AT power feed circuit is immediately_available as an energized line to the Vogtle low voltage switchyard - The SAT power feed can be manually realigned tnd connected to feed either VEGP unit's safe shutdown loads via a 4.16 kV Class IE safety bus within I hour. The SAT underground power feed remains continuously energized.

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f% clos:re 2 Vogtle Electric Generating Plant Request to ResIse Technical Specifications,"AC Sources - Operating

Eaufgtacy DiettLGratrator Extended AOT Renutg JuMjAcalina_and 10 CFR 50.92 Evaluntlna During the initial stages of an Silo at Vogtle concurrent with a LOSP at Plant Wilson, there would be indication of a de energired SAT power feed with the design of a common SAT switchgear trouble annunciator in the VEGP Unit 1 Control Room. The decision to utilize the SAT as a potential offsite source, or try to recover a grid connection through the RAT, would rely heavily on system dispatcher input and diagnosis, and both VEGP and Plant Wilson specinc equipment status and operational concerns. Procedures for restoration of power following an Silo at Vogtle are documented in plant specific emergency and syttem operating procedures

- along with Southern Electric System and Georgia Power Company switching orders and procedures.

Although restoration of offsite power by the system dispatcher would simultaneously proceed given the grid restoration plan, a black start of one of the Wilson cts would then become an immediate option for VEGP personnel to implement in order to expedite the supply of VEOP with safe shutdown power, via the SAT. Two of the six cts at Wilson have been modified with enhanced black start capability, CT4 and CTI), making them a high priority for use under this scenario. The recovery from an Silu at Vogtle by application of the SAT power feed has been adde j to both the plant emergency operating procedures and the system dispatchers plan for restoration of ofTsite safe shutdown power to Vogtle.

In accordance with 10 CFR $0.63 requirements, and plant specific design and analysis, VEGP is an AC independent,4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, Silo coping facility. The addition of the SAT and Wilson underground power feed was not designed in order to meet any specific NRC SBO regulatory requirements or NUMARC 87 00 alternate AC (AAC) source criteria in hopes of changing the VEOP Silo coping strategy. Vogtle is maintaining its AC independent,4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, Silo coping strategy.

Since VEGP does not take credit for either the additional and diverse connection to the Southern Electric System grid continuously available via the Plant Wilson switchyard or the CT's at Plant Wilson as alternate AC ( AAC) power sources in it's station blackout (SBO) coping analysis, the criteria for an A AC being available in a timely manner of one (1) hour is not directly applicable.

'lherefore any simulated black start test and potential final connection of the SAT to VEGP in order to verify timeliness of power restoration Ibr safe shutdown purposes, whether it is performed either in part, or unison, will be considered successful ifit is accomplished within four (4) hours, the time necessary to envelope VEGP's Silo coping analysis.

A simulated black start test was successfully performed on one of the two enhanced black start Wilson cts, Since the time required to perform this function has never been officially recorded, a demonstration at least once per 18 months of the enhanced black start generation capability (involving at least one enhanced black start CTG and the black start diesel generator) will be perfonned and verified to be accomplished within four (4) hours. The time required for a black-start of a Plant Wilson CT is highly dependent upon a variety of factors, such as: the type and severity of the initiating event; the qualified operator staffing available; receipt of system dispatcher switching orders and clearances; verification of available transmission lines; and the possible need to accommodate for supplemental emergency lighting and communications equipment. Therefore the appropriate VEGP Operations personnel will be trained in the use of

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E:elos:re 2 Vogtle Electric Ge.urating Plant Request to Revise Technleal Speelfleations,"AC Sources - Operating" EintrgtatyEtsel Generalarlittaded AOT Reautal  :

Justififation and 10 CFR 50.92 Evaluation CTO black start procedures, and the procedures will be available to the appropriate Operations personnel during an EDO extended AOT. 'ihese measures should reduce delays in restoring offsite power to Vogtle for safe shutdown purposes, however Vogtle is analyzed for coping with an S!!O for four (4) hours utilizing station batteries and inverters.

OptradWt.tsMainkaancts.Ithling.and.Rtilabjiity af cts Plant Wilson is maintained and operated with separate and independent generating plant guidelines and practices than those of Vl?GP. Plant Wilson operations and maintenance practices are consistent with industry standard practices for .lectrical generation fossil fired peaking urits.

The current Plant Wilson practice is to stan and run one (1) CT once a week for approximately one (1) hour. Therefore, each CT is exercised at least once every six (6) weeks. During these weekly CT exercise runs. the starting and cranking of the CT(s) are not black started. The cts are normally started from power supplied by the grid. During peak seasons when the cts run frequently to meet generation demand, the weekly testing is not necessary, and iti s not performed. Upon approval of the EDG cxtended AOT, the weekly individual C.O load run tests will be perfctmed at a capacity that envelopes the safe shutdown load requirements of at least one VEGP unit.

Prior to an anticipated run, a CT is placed on turning gear for approximately two hours prior to the eventual cranking, fuel ignition, and electrical generation. In an emergency, the turning gear is not ne5essary, however it is a preferred method for continued long term operation and equipment maintenance. The turning gear motors are DC motors and would be unaffected due to a Plant Wilson 1,OSP.

In order to achieve high assurance of the enhanced black-start combustion turbine generation of Plant Wilson, the TS will also be revised to require that one of the enhanced black start combustion turbine generators (CTGs) be verified functional by starting it and verifying that it achieves steady state voltage and frequenc>. This must be performed either within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> prior to removing a DG from service for an extended DG AOT, or within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after removing the DG from service for the extended AOT. See Required Action 11.5.1 in the enclosed marked up pages. This Required Action is contingent on the combined reliability of the enhanced black start CTGs having been demonstrated and maintained to be 2 95 %. Prior to demonstrating the reliability of the enhanced black-start CTGs, or in the event that the combined reliability falls below 95 %. a CTG must be started and allowed to run continuously in the event that a DG is out of service for an utended AOT, in this case the CTG must be started prior to removing the DG from scryice for preplanned maintenance that would require the DG to be out of service for an extended AOT. For unplamied DG inoperabilities requiring an extended AOT.

the CTG must be started within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> aller removing the DG from service. Sm Required Action ll.5.2 in the enclosed marked up pages.

As stated in the enclosed proposed liases fer Required Action 11.5.2, any one of the six CTGs may be started for the purposes of Required Action 11.5.2. If a CTG is allowed to nm while a DG is out if service, it is not necessary that the CTG be one of the two enhanced black start 4

_ .. - .- - -_ - _ - . - -_- ~ - - - -

Etciostre 2 Vogtle Electric Generating Plant Hequest to Revise Technical Speelfications,"AC Sources Operating" Emergenty Diesel GRAffALGEEittaded AOT Renutal dualifisAtlon and.10 CFR 50.92 Evaluation CTGs. In addition, the proposed llases for Required Action 11.5.2 state that if the running CTG fails, one of the remaining CTGs must be started within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. In the unlikely event that no CTG can be started, Condition C would apply and the inoperable DG would have to be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after entry into Condition C.

1 If a DG is to be removed from service for an extended AOT without requiring that a CTO be operated throughout the time that the DG is inoperable, then the enhanced black start C1Gs must have a demonstrated reliability of 2 95 %. The reliability of the enhanced black start CTGs will be demonstrated by performing a minimum of 20 starts and load runs of at least I hour on cach enhanced black start CTG. The black start diesel generator will be tested separately, and it will also be subjected to a minimum of 20 starts and load runs of at least I hour. The comNned reliability of the two enhanced black start CTGs and the black start diesel generator must be 2 95 %. A successful start will be defined as a CTG starting and achieving steady state voltage and frequency within acceptable limits within a time restraint of one (1) hour. A successful load run will be declared if the CTG runs with its output breaker closed for a continuous one (1) hour period.

The combined C id reliability will be calculated as follows:

Combined reliability = [(Reliability of CTA + Reliability of CTII)- (Reliability of CTA* Reliability of CTil)]* Reliability of black start DG The reliability of CTA or CTil will be defined as:

Reliability of CT(A/II) = Start Reliability

• Load run Reliability Where:

Start Reliability = Number of successful starts / Numb (r of start 6mands Load run Reliability = Number of successful load runstfotal number ofload run demands The reliability of the enhanced black start CTGs (including the black start diesel generator) will be maintained by quarterly testing. A commitment to a quarterly start and load run test for each enhanced black-start CTG appears in the proposed llases for new Required Action I1.5.1 in the enclosed marked up pages.

- Dunman Cause Failure The Plant Wilson Combustion Turbine facility is a completely self-sufricient, independent electrical generation facility, Plant Wilson cts are utilized for peaking power generation and the Plant Wilson switchyard and station service are continuously energized from the Southern Electric System grid. Plant Wilson's switchyard is connected to the Southern Electric System l Grid by two overhead transmission lines: (1) the Waynesboro, Ga. 230 kV transmission line S

l =. ,

L

Enclos:re 2 Vogtle Electric Generating Plant Hequest to HesIse Techuleal Specifications,"AC Sources . Operating" EmergcacLDicatlGrattator Estended AUT Reautal JuntlGratlan_and 10 CFR 50.92 Evaluailes entering the Wilson switchyard from the south; and (2) a second 230 kV transmission line entering the Wilson switchyard from the north and connected to the VEGP high voltage switchyard " breaker and a half scheme" bus. Plant Wilson has no common auxiliary power, fuel, equipment, or shared systems and/or components with VEGP. The only connections between the two facilities are the underground SAT power feed, two 13.8 kV overhead power lines and one 230 kV transmission line. Sufficient protective relaying has been provided to assure that any fault on these interconnected lines is isolated. The ground mats for the two facilities have been electrically connected to negate possible ground potential difTerence between the two sites and the interconnecting ground cable has been slied to withstand the predicted potential ground fault current.

VEGP and Wilson switchyards are separated by approximately one mile. The Vogtle Wilson underground interconnecting power feed and associated transformer (SAT) share a common switchgear and cable bus which feeds into a manual disconnect on the low side of each RAT, the VEGP normal preferred power sources. Therefore, a failure of either the disconnect switch, cable bus, or supply breaker would render one preferred offsite power source (RAT) and the SAT unavailable for use on that train of associated shutdown loads, llowever, under emergency conditions the other RAT can be aligned to supply power to that bus through the alternate 4.16 LV IE safety bus tie breakers.

The only common points between the SAT and the onsite emergency power sources (EDGs) are the individual emergency 4.16 LV I E safety busses. They do not share a common bus breaker, ,

These is minimal potential for common cause failure of all VEGP offsite power, the SAT power circuit emanating from Plant Wilson, and the Plant Wilson switchyard and CT  :

generators. The physical separation of the two generating facilities provides a high level of assurance that a single likely weather related event will not render both VEGP's and Plant Wilson's switchyards and/or generating capability permanently disabled or unavailable for lengthy periods.

}&ather TolerettiDeslyn Additional protection from weather felated events is provided by the underground routing of the SAT power line interconnection from Vogtle to Wilson. The SAT power supply circuit emanates from the Plant Wilson switchyard and is run underground as a direct buried cable for approximately 1/2 mile until it enters a cos. crete duct run near the Vogtle Unit 2 cooling tower.

From this point on, the circuit continues in r. concrete duct run until it reaches the Vogtle low voltage switchyard where it terminates at the SAT high. side circuit breaker in a weather resistant switchgear switchouse. From the SAT secondary, the circuit returns to a 4.16 kV circuit breaker located in the same switchouse enclosure and then connects to the existing above-ground /open-air cable bus w hieh connects to a manual disconnect on the secondary side of each RAT. The RAT / SAT disconnect switches feed the associated 4.16 kV I E safety bus. Therefore, the SAT shares a common switchgear and cable bus which connects to a manual disconnect on the low side of each RAT, the normal preferred power sources.

6

E:cion:re 2 Vogtle Electric Generating Plant Request to Revise Technleal Specincations,"AC Sources Operating" t E.Intigtaty_idtAtl3itAfrator Este.aded AUT Rea,util i 7

Jutuficadua.and.10.fFM 30.92 Evalunden The SAT is located beside its own Aeparate switchouse in the VEGP low voltage switchyard and is positioned in the same vicinity as the existing normal offsite power source transformers, the reserve auxiliary transformers (RATS). Since the SAT is located near the RATS in the

, switchyard, it is exposed to the same weather conditions as the normal ofTsite power sources.

Ilowever, given the extreme weight, substantial physical nature of their construction and switchyard design standards, it is unlikely a severe weather related event such as a tornado, could render all of these trant. formers irretrievably lost.

Adminhtnuthe/Congensalon Meswes The following general guidelines and compensatory measures will be utilized to assure that the SAT is available and that Plant Wilson combustion turbine generation is maintained in a state of readiness in order to provide power to the VEGP emergency safety buses if necessary during the EDO extended AOT.

E e A demonstration at least once per 18 months of the enhanced black start generation capability (involving at least one enhanced black start CTO and the black stan diesel generator) will be performed and verified to be accomplished within four (4) hours.

• An EDG extended AOT will not be entered for scheduled maintenance purposes if severe weather conditions are expected.

• The appropriate VEGP Operations personnel will be trained in the use of the CTO black start procedures, and the procedures will be available to the appropriate Operations personnel during an EDO extended AOT.

• Voluntary entry into the EDG cxtended AOT will not be abused by repeated entry and exit from the LCO.

• The SAT will be verified to be available within one hour of entr to Condition 11 and at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter, while in the EDG AOT.

• While in the EDO AOT, additional elective equipment maintenance or testing will be evaluated using the CRMP Activities which yield unacceptable results via the CRMP will be avoided.

• No maintenance will be performed within the Wilson substation w hich would challenge the ,

13.8 kV SAT connection.

• The Waynesboro 230 kV olTsite power connection to the Wilson substation will be in service. .

• The CT electrical generation capability of Plant Wilson will:acessfully meet the requirements of TS condition 11.5.1 or 11.5.2 prior to initiating a Vogtle pre planned EDG .3 maintenance. Plant Wilson C'l testing will demons

• rate voltage, frequency, and loading 7

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Enclos:re 2 l

l Vogtle Electric Generating Plant l Hequest to Reviac Technical Specifications,"AC Sources - Operating l Einerpency Dicael Generator Extended AOT Request i~

Jyntification ==d 10 CFR 50.92 Evalua002

. capabilities that envelope safe shutdown loads for Vogtle The test is accomplished by tying a CT to the transmission network for generation purposes.  !

• Fuel supply and inventory verification at Plant Wilson will be performed to ensure that  ;

sufficient CT fuel is available to support the requirements needed for the safe shutdown of one VEGP unit during an EDG cxtended AOT.

• No elective maintenance or testing will be performed on the Plant Wilson cranking diesel or i the A and il CT units.

• The System Dispatcher / Power Control Center (PCC) will be notified in advance that VEGP is performing onsite emergency AC power source maintenance and be advised of the increased risk of an Silo at VEGP during this time.

• If an offsite power source (a li AT) connected to the 4.16 kV IE safety bus associated with  ;

the out of service EDG becomes unavailable or lost during the extended AOT :

The SAT 13.8 kV underpe iund connection will used to restore the affected bus.

The GPC Transmisslon Maintenance Services (TMS) department will be immediately '

notified to assist in restoring the affected RAT, The System Dispatcher /PCC will be notified that Vogtle is aligning one 4,16 kV class IE safety bus to Plant Wilson.

e if a CT black start appears to be necessary during she extended EDO AOT, e.g. impending extremely severe weather or the Southern Electric System has been identified as being potentially unstable due to events in the system, the following action will be taken:

An operator will be dispatched to Plant Wilson and prepare for a CT black start by placing at least one CT on turning gear. [ Note: The alignment of the CT switchyard / SAT line to VEGP can be performed in parallel with a CT black-start and is designed to be accomplished within I hour.]

• If a SILO were to occur at Vogtle during the extended EDG AOT:

- An operator will be dispatched to staff Plant Wilson, if unstaffed, and prepare for a CT emergency black start.

He system dispatcher /PCC is trained and cognizant of the necd to initiate the restoration

. of ofTsite power to Vogtle utilizing the transmission emergency operating procedures for safe shutdown purposes ,

VEGP will have procedures in place to implement the above commitments prior to entering an extended DG AOT, 8

O

E: clos:re 2 Vogtle Flectric Generadog Plant Request to Revise Techalcal Specifications,"AC Sources Operating" LattstaQ31tatl_Gtaffal9r EstendedAOT Mequtal Jus 11flCA1195.And 10 CFM M92 Eialuation U TLine and l'ECP EDG Maintenaner Rufr CrJterla Inqpact in accordance with current Maintenance Rule performance criteria, SAT availability is currently being tracked as an "of/31/c power wurce"(as a functio of Technical Specifications 3.8.1.(a) and 3.8.2.(a)"AC Sources . Operating and Shutdown") such that the total LCO time for all offsite power sources is less than 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> per rolling 18 months; 180 hours0.00208 days <br />0.05 hours <br />2.97619e-4 weeks <br />6.849e-5 months <br /> of unavailable time per off site source per rolling 18 months; no LOSP events occur due to maintenance factors; no more than one (1) maintenance preventable functional failures (MPFF) occur per rolling 18 months; and no repetitive MPFFs are experienced. The equipment associated with the SAT covered by maintenance rule applicability includes the RAT lowside disconnects, the SAT cable bus, transformer, SAT switchgear and the underground cable up to the first breaker in the Plant Wilson switchyard. This system is currently performing better than the above perfonnance criteria, and the system is in the 10 CFR 50.65 a(2) Maintenance Rule category, meaning that it's performance or condition is effectively controlled through performance of appropriate preventive maintenance.

The CTG capability of Plant Wilson is not considered to be covered by the requirements of the Maintenance Rule.

Cunently the VEGP Maintenance Rule Performance Criteria for EDO unreliability is defined in tenas of Maintenance Preventable Functional Failures (MPFF) of 1.0, and for EDG unavailability of 1.52E 2, i.e. 98.48 % availability. De EDG's are all currently in tne 10 CFR 50.65 a(2) Maintenance Rule catep ey. With impkmentation of an EDO extended AOT, the new EDO maintenance rule unavailability perfunnance criteria of the EDO is expected to become 4.10E 2, or 95.9 % availability. These numbers are based upon an expected 14 days per cycle per EDG unavailability being moved from refueling outages to power operation.

EtchabilblicSuppet]

An assessment was perfonced to evaluate the changes in core damage frequency (CDF) w hich would result from the proposed increases in the technical specification allowed outage times for the diesel generators (DGs) and the addition of the SAT offsite source. A seismic analysis and a consideration of severe weather impacts were performed and included in the new CDF number to account for the vuinerability of the S AT source to seismic events and severe weather which could adversely impact the mitigation provided by the SAT for a loss of offsite power (LOSP) event. OfTsite power recovery probabilities were ad, justed to simulate the elTect cf this direct feed romce of olTsite power. The evalustion resulted in a substantial decrease in the 1.OSP L contribution to the calculated CDP. %c combined effect ofinstalling the SAT and increasing the DG Completion Times results in a net decrease in the CDF at VEGP. The assessment showcs that CDP will decrease by approximately 12.5% with the addition of the SAT offsite source. As a comparison, an additional unavailability of a DG for approximately 170 days per year would result in no change to the CDF, offsetting the improvement in safety offered by SAT availability Conservative human error factors were assumed, and conservative seismic and severe weather analyses were perfonned.

9 e _ _ _ . _ _ _ . . _ _

Eaclos :re 2 Vogtle Electric Generating Plant Request to ResIse Techalcal Specincations,"AC Sources . Operating" EmergenO' Diestl.Grattator Extended AOT Requent j Justification med 10 CFR 50.92 Evaluation Changes made to the baseline PRA for use in this TS change evaluation include formal addition of the S AT/ Wilson line into the PRA model with the LOSP frequency revised to include operating experience through December 1995 which is past the cut off date used in the baseline PRAT and the dual unit LOSP frequency was apportioned to define non hurricane season LOSP and hurricane season LOSP, lhe baseline PRA has undergone a review by an independent Review Group (IRG) as part of the Individual Plant Examination process.1he original PRA submitted as part of the IPE process has been recently converted to linked fault tree methodology based on the EPRI CAFTA suite of software. Calculations performed as part of the baseline PRA and conversion to CAFTA are documented in calculation packages which were originated and independs utly verified by quallned personnel in accordance with approved procedures. The PRA casulations performed in support of the TS change were originated and independently veri 0ed by qualined personnel in accordance with approved procedures.

1he risk measures used in evaluating the changes included:

(a) Average annual CDF from internal initiating events.

(b) Change in the average annual CDF from internal initiating events.

(c) Contribution to CDF from scismic and tornado events.

(d) Change in the core damage probability (CDP) when a EDO is taken out of service for 14 days.

4 (c) Change in the CDP w hen a EDG is taken out of service for 14 days during non hurricane season.

(f) Change in the CDP when a EDO is taken out of service for 14 days during hurricane season, (g) Changes in the CDF when one train of NSCW or TDAFW pump is taken out of service concurre it with a EDO outage.

No quantitative uncertainty snalysis was performed as part of the PRA calculations. Sensitivity analysis on a number of assumptions such as common cause and human error rates were performed or, the original PRA as part of the IPE submittal to the NRC.

The CRh1P will be utilized to evaluate equipment outage con 0gurations tht could threaten the integrity ofimportant safety functions during the EDG cxtended A0T. The RMP plant procedure will provide a description of the capability to perform a prompt assessment of the overall impact on safety of proposed plant con 0gurations including an explanation of how these tools will be used to ensure that risk signincant plant configurations will not be entered and that appropriate actions will be taken when unforeseen events put the plant in a risk signincant con 0guration. Tabic 2 of this TS change submittal provides the EDG Extended AOT Risk Management Guidelines.

lhe CRMP procedures will be approved and in efTect prior to implementing this requested TS change however EOOS is currently in place and functional.

10 4 m

E nclos re 2 1 l

Vogtle Electric Generating Plant Request to Revise Technical Specifications. "AC Sources . Operating" ,

Estigtary Dienel Grattator Estended AOT Renutal Juillfitallna.and 10 CFR 50.92 Evalsa1195 ,

Smitmac' His proposed TS amendment only afTects the length of the allowed outage time for DGs .nd does not change the DG testing or maintenance requirements. De use of the SAT as an additional offsite power source coupled with the veri 0 cation that the combustion turbine electrical power generation of Plant Wilson is functional and sufUciently reliable to provi, o assurance ofit's black start generation capability, or the option of starting and running of a CT during the extended AOT, and the use of a con 0guration risk management program has been shown to provide more than adequate compensation for the poteritial risk of the extended DG Completion times during power operation and would also reduce shutdown risk by increasing the availability of emergency power during refueling outages. The proposed change in DO completion times in conjunction with the added availability of the SAT and use of the CRMP during the extended DG Completion time, continue to provide adequate assurance of the capability to provide power to the ESF buses.

t

' 11  :

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E:cic=re 2 Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sourtes - Operating" Emelgency Diesel Generatot, Extended AOT Reaut:1 Justification und 10 CFR 50.92 Evaluation 10 CFR 50.92 Evaluation SNC has reviewed the requirements of 10 CFR 50.92 as they relate to the proposed changes and has made the following determination:

1. Does the change involve a significant increase in the probability or consequences of an accident previously evaluated?

No. The DGs are used to support mitigation of the consequences of an accident; however, they are not considered the initiator of any previously aralyzed accident. The use of the SAT as an additional offsite po ver source coupled with the black start generation capability of Plant Wilson and the use of a configuration risk management program wil; more than compensate for the risk introduced by the extended DG Completion Times. As such, the extension of the DG Completion Times will not significantly increase the probability or consequences of any accident previously evaluated.

2. Does the change create the possibility of a new or different kind of accident from any accident previously evaluated?

No. The proposed change does not introduce a new mode of plant operation and does not involve a physical modification to the plant. Therefore, it does not create the pessibility of a new or different kind of accident from any accident previously evaluated.

3. Does this change involve a significant rsduction in a margin of safety?

i No. This proposed TS only affects the length of the allowed outage time for DGs and does not change the DG testing or maintenance requirements. The proposed TS still requires the DGs to be maintained Operable to the same standard as before. The use of

< the SAT as an additional offsite power source coupled with the black start generation capability of Plant Wilson and the use of a configuration risk management program has been shown to provide more than adequate compensation for the potential risk of the extended DG Completion times. The peoposed change in DG completion times in conjunction with the added availability of the SAT, continue to provide adequate assurance of the capability to provide power to the ESF buses. Therefore, the proposed change does not involve a significant reduction in a margin or safety.

Conclusion Based on the preceding analysis andjustification, SNC has determined that the proposed changes to the Technical Specifications wi:1 not significantly increase the probability or consequences of an accident previously evaluated, create the possibility of a new or different kind of accident from any accident previously evaluated, or involve a significant reduction in a margin of safety.

Therefore, SNC has determined the proposed changes tueet the requirements of 10 CFR 50.92(c)

. and do not involve a signifiernt hazards consideration.

l 12 i

Etcios:re 3 Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sources . Operating" Emergency Diesel Generator Exituded AOT Requent FJ:spnnse to Request for Additional InforJnaliRR lly letter dated November 7,1996, titled " Request For Additional f 4rmation (RAI) Regarding Extended Allowed Outage Times for the Emergency Diesel Generators VEGP Unit I and 2, TAC Nos.

M96769 and M96770" the NRC r. quested the following additional information. Below is a tianscription of the NRC's specific request followed by SNC's response.

NRC Outalinal

1. "Please provide a markup of all TS sections issued or. 3eptember 25,1996, that will be affected by your application for the 14 day AOT. The staff recognizes that you may have provided most or all of this information during the review of your application for full conversion to the improved TSs.

Ilowever, since r.ew TS have been issued, your markup of those new TSs is requested to ensure there is no confusion regarding your AOT request."

SNC Response to NRC Outation 1

1. Enclosure 5 contains the proposed changes to the latest amendments of the TS and also the proposed changes to the TS Bases. Any prior TS markups from previous submittals should be disregarded.

NRC Ontalluul Note: For ,:omenience of reference, the CDF variables discussed in the following answer are listed and described in Table 1 immediately aller Enclosure 3,

2. Beginning with the Station Blackout induced Core Damage Frequency (SBO/CDF) reported in the Vogtle Individual Plant Examination (IPE), identify and quantify SBO/CDF reduction (credi t) taken in the revise.1 Probabilistic Risk Assessment (PRA) for the following:

(a) Plant Wilson availability (altemate AC source),

(b) EDG X-Tie capability, and (c) Deletion of 7/l5 11/15 hurricane season (in relation to the assumed loss of offsite power frequency)

Provide a revised SBO/CDF estimate based on the above.

(d) Describe and quantify any other credit taken in addition to the three items listed in 2(a) above.

(e) Provide this as your second revised SBO/CDF estimate. (Note: please do not include the 14-day EDG AOT in this revised baseline estimate.)

(f) include in your estimate a 14-day AOT for each of the EDG's and quantify the increase in SBO/CDF. Report this as your final SBO/CDF estimate.

1

En .lostre 3 Vogtle Electric Generating Plant Request to Revise Technical Speelfications,"AC Sources - Gperating" Entgency Dierel Generator ritended AOT Reau. cal Response to Request for Additional Information (g) Provide the calculated total CDF resulting from all PRA sequencer involving SBO before end after you met the SBO Rule (10 CFR 50.63) implementation.

(h) Provide the instantaneous change in the CDF value for the worst-case plant configuration allowed under the proposed specification.

(i) Exp ain how the EDG preventive maintenance and subsequent or+1ine operability testing is treated in the CDF calculations.

(J) Provide the EDG reliability and availability values used in the PRA analysis to calculate the SBO CDF values. Discuss these values in relationship to any goals associated with the implementation of the maintenance rule and in comparison to actual past performance of the Vogtle EDGs. Also, compare the values used in the PRA analysis to the target values committed to for 5130.

f SNC Resnonac_to NRC Ouestiani.

(a) The decrease in the average CDF when credit is taken for the availability of Plant Wilson will be:

CDF decrease = (CDF 3-CDFn)

= (3.932E 3.442E 05)/3.932E-05

• 100%

= 12.5 %

(b) No credit has been taken in the PRA calculations for the ability to cross tie the EDGs between units for safe shutdown purposes in support of the assessments for an EDG extended AOT. Therefore no decrease in CDF associated with this capability has been calculated. Although appropriate VEGP personnel received training in April 1997, on options available to provide power through electrical distribution system alternative alignments, no credit has been taken in th PRA model for this type of recovery action, nor are there any plans to formally proceduralize these m :thods. The EDG unit cross tie capability was an insignificant contributor to CDF reduction compared to the contributions -

of the SAT and Plant Wilson.

(c) Three " baseline" CDFs were calculated for non-hurricane season, hurricane season, and the annual average which are provided in response to question 2(e).

(d) No other credit was taken in the calculation.

(e) The following baseline CDFs were calculated:

Non-hurricane season CDFn = 3.432E-05/ year ilurricane season CDFo = 3.514E-05/ year Annual Average CDFn = - 3.442E 05/ year (f) Change in the CDP during ron-hurricane ve on with EDGJ in maintenance for 14 days and EDG-B no* in maintenance will be:

2

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E: clos:re 3 Vogtle Electric Generating Plant Ilequest to Revise Technical Specifications,"AC Sources - Operating" Emergency Diesel Generator Extended AOT Reautti Response to Reauest for Additional Information DCDP = -(CDF c - CDF o + dCDF sushuC+ ToEAlo)

• 14/365

=

(4.105E-05 3.432E 05 + 2.53E-06)

• 14/365

= 3.78E-07 Change in the CDP during non-hurricane season with EDG B in maintenance for 14 days and EDG-A not in maintenance will be:

DCDP = (CDF r - CDF D + dCDF sushuC + TokNADO)

• 14/365

=

(4.176E 05 - 3.432E-05 + 2.53E-06)

• 14/365

= 3.82E-07 Change in the CDP during hurricane season with EDG A in maintenance for 14 days and EDG-B uot in maintenance will be:

4 DCDP = (CDF n CDF a + dCDF sushnC+ TORNADO)

• 14/365

=

(4.609E 3.514E-05 + 2.53E-06 )

• 14/365

= 5.17E-07 Change in the CDP during hurricane season with EDG B in maintenance for 14 days and EDG-A not in maintenance will be:

DCDP = (CDF i - CDF a + dCDF suSMIC + TORNADO)

• 14/365

=

(<.627E 3.514E-05 +2.53E-06)

• 14/365

= 5.24 E-07 Change in the CDP using average values for LOSPI (single unit LOSP) and LOSP2 (dual unit LOSP) with EDG-A in maintenance for 14 days and EDG B not in maintenance will be:

DCDP = (CDF j - CDF n + dCDF suSMIC + TORNADO) 14/365

= - (4.218E 3.442E-05 + 2.53E-06)

• 14/365

= 3.95E-07 Change in the CDP using average values for LOSP1 and LOSP2 with EDG-B in maintenance for 14 days and EDG-A not in maintenance will be:

DCDP = (CDF g - CDF u + dCDF sussuC + TORNADO)

• 14/365

=

(4.231E 3.442E-05 + 2.53E 06)

• 14/365

= 4.00E-07

-(g) De SBO rule had no c fect r on the PRA model.

1 l

3  ;

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Eselostre 3 Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sourees - Operating" Enttguity DieselGenerator hiended AOT Requtil Resnonse to Requealfor AdditionalInformation (h) To determine the instantaneous change in the CDF valte for the potential worst-case plant configuration allowed under the proposed technical specifications, two cases were evaluated to determine the impact on instantaneous CDF if additional equipment was cut of service during a diesel generator extended AOT. VEGP Technical Specifications allow the turbine driven AFW pump or a train of NSCW associated with the EDG to be out of service at the same time.

Case 1: TDAFW pump and EDG A in maintenance: Change in the VEGP CDF using average values for LOSP1 and LOSP2 with EDG-A and TDAFW pump in maintenance, and EDG-B and MDAFW pumps not in maintenance will be :

dCDF = (CDF ,i - CDF n + dCDF sasuic + TonnAno)

=

(7.500E 3.442E 05 + 2.53E-06)

= 4.3 I I E-05 Case 2: NSCW train B and EDG B in maintenance: Change in the VEGP CDF using average values for LOSP1 and LOSP2 with EDG-B and NSCW train B in maintenance, and EDG A and NSCW train A not in maintenance will be :

DCDP = CDF u - CDF n + dCDF scisuic + TORNADO)

=

(7.355E 3.442E-05 +2.53E-06)

= 7.036E-04 (i) EDG preventive maintenance and subsequent on-line operability testing is considered to render the EDG incapable until the testing is completed of performing its intended safety function in the CDF calcult.tions.

(j) The EDG unreliability and unavailability values used in the CDF calculations are historical based and listed below:

EDG random failure to run = 1.14E-02 EDG random failure to start = 6.33E-03 EDO A & B common cause failure to run = 3.08E-04 EDG A & B common cause failure to start = 1.71E-04 EDG maintenance unavailability (out of service) = 1.3E-02, i.e. 98.7% Availability.

(Based on historical data. Miscellaneous outages, i.e. testing and corrective maintenance during power operations)

With the implementation of an EDG extended AOT, the unavailability of the EDG is expected to rise to 3.9E-2 or 96.1% availability. These numbers are based upon an estimated la days per cycle per EDG being moved from refueling to power operation.

Currently c VEGP Maintenance Rule Performance Criteria for EDG unreliability is defined in i terms of h.amtenance Preventable Functional Failures (MPFF) of 1.0, and for an EDG target  !

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Erciostre 3 Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sources - Operating" Emergency Diesel Generator Extended AOT Request Response to Request for AdditionalInformation unavailability of 1.52E-2, or 98.48% availability. With an EDG extended AOT, the new EDG rr.aintenance rule unavailability performance criteria is expected to become 4.10E-2, or 95.9%

availability.

During 10 CFR 50.63, Station Blackout rule implementation, VEGP committed to an EDG target reliability of 0.95. With the approval of an EDG extended AOT of 14 days this commitment is expected to be unaffected. In the PRA calculations forjustification in support of the EDG extended AOT, the SAT availability is equivalent to the Plant Wilson Switchyard availability, regardless of generation source (grid or cts), and is considered to be unavailable for only one (1) day a year, or 99.7 % availability. The unavailability of the Plant Wilson Switchyard renders the cts unavailable also. The high availability of the Plant Wilson Switchyard is due to the high reliability of the Southern Electric System Grid.

Note:The above PRA calculations are based on the CDF variables in Table 1.

NRC Ouestian)

3. Provide a copy of your approved Configuration Rin hianagement Program (CRh1P) and explain how it will be mali.tained and referenced in the administre?ive control section of the Vogtle TS. Please ensure that your submittal includes the following with respect to your CRhiP:

Describe how PRA insights are (or will be) used in the decision making process, specifically with respect to planning and controlling maintenance activities involving the EDGs. Also, describe training requirements for personnel that will use or report PRA results to upper management.

Discuss how configuration risk estimates for equipment configurations not modeled in PRA were addressed. Also discuss the software presently used or planned to be used to generate PRA insights, j and how it will be maintained.

4 Discuss the extent to which numerical criteria are used to proceed with a 14 day EDG AOT. Include Incremental Conditional Core Damage Probability estimates, or core damage frequency estimates used as decision criteria. Describe how uncertainties will be addressed in the decision making process, and the role these quantitative insights will play in the management approval process.

SNC R.sponse to NRC Oncition)J VEGP Maintenance Scheduling procedure 00354-C provides instructions for scheduling maintenance activities during periods between refueling outages. This procedure will integrate the capabilities of VEGP Equipment Out Of Service (EOOS) risk monitor, hereafter referred to as EOOS, and provide ,

planning and scheduling strategies'to maximize equipment performance, reliability, and availability.

EOOS replaces the use of other potential PRA tools such as the VEGP IPE TOOL previously discussed j with the NRC. The VEGP Procedure 00354-C or equivalent will implement a Configuration Risk '

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Eaelos:re 3 Vogtle Electric Generating Plant Request to Revise Techniul Speelfications,"AC Sources . Operating" Emergency Diesel Generator hiended AOT Requcal Response to Request for Additional Informatian Management Program which will be referenced in the administrative control section of the VEGP Technical Specifications. See Enclosure 5 for a mark up of TS page 5.0 27.

EOOS will be used by the Central Scheduling Group to support the safety assessment of scheduled EDG maintenance. As part of the Plan-of the-Day Report, a list of affected equipment tag numbers and scheduled maintenance dates is generated every weekday. This scheduled maintenance information will be used as an input to EOOS, and the resulting EOOS output will be used by central scheduling personnel in developing a .afety assessment of scheduled EDG maintenance. VEGP intends to continue the current practice of scheduling system outages on only one safety signiGcant system at a time.

Central Scheduling will inform plant management of risk insights generated using EOOS. Selected plant personnel including central scheduling personnel have undergone or will undergo in the future the neces:.ary training on PRA concepts and applications, EOOS development and use, and hiaintenance Rule implementation.

The VEGP probabilistic risk assessment (PRA) forms the basis for the quantification engine used by the VEGP EOOS. Ilowever, unlike the VEGP PRA, the EOOS quantificatiot, engine evaluates configuration specific instantaneous CDF. The VEGP PRA model will be updated regularly to reflect plant changes, The EOOS quanti 6 cation engine will be updated following an upda:e of the VEGP PRA model.

Table 2 provides the EDO Extended AOT Risk hianagement Guidelines which includes recommended corrective actions based on the configuration specific Instantaneous Core Damage Frequency (CDFmsT )

or Plant Safety Index (PSI). The hiaximum Duration 1.imit (DURstrx)in Table 2 is a configuration-specific value displayed on the EOOS Operators Panel which provides the recommended maximum duration within which the corrective actions should be completed to limit the change in core damage probability to a value of IE-06. The change in core damage probability requiring management approval for authorizing EDG extended AOT is chosen as lE 06 based on the Nuclear Energy Institute (NEI) PRA Application Guide. Table 2 shows the possible DURsirx values associated with each PSI Color band.

Also provided are the management approval levels for authorizing EDG extended AOT depending on the PSI Color band displayed on the EOOS Operators Panel. The Corrective Actions, PSI, DURhiAx an'd management approval levels specified in Table 2 are applicable only when an extended EDG AOT is in effect. . The Risk hianagement Guidelines of Table 2 will be3 .duded in procedure 003!4 C and will be revised when needed to reflect changes to the VEGP PRA.

NRC.Qutation 4

4. Please inform the statt when a document has been promulgated that provides specine directions for cross-connecting an EDG of one unit to the Class IE busses of the other unit.

SNC Respanac_to NRC Question 4 Although appropriate VEGP personnel received training in April 1997, on options available to provide power through electrical distribution system alternative alignments, and guidelines are available for emergency use, no credit has been taken in the PRA model for this type of recovery action in support of 6

Esclostre 3 Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC Sources - Operating" Emergtary Diesel Generator E11tnded AOT Requeal Response to Request for AdditionalInformation the assessment for an EDG cxtended AOT, not are there plans to formally proceduralize these methods.

These potential alternative alignments to cross-connect the EDGs between units are not in the current design or licensing bases of either unit, and would require that protective interlocks in the electrical distribution system be defeated. Southern Nuclear Operating Company does not believe that procedures

- which reflect these actions can be approved in accordance with 10 CFR 50.59, and currently has no plans to request NRC review of these alignments.

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TABLEI CDF Variables used in EDG Extended AOT Justification Calculations CDF CDF DUAL UNIT LOSP I)ESCRIPTION OF CDF YARIABLE VARIABLE VALUE FREQUENCY CDF 4 3.932E-05 1.43 E-02 Average nnnual CDF with no credit for SAT i.e., Plant Wilson Swyd or cts CDFn 3.442E-05 1.43 E-02 Average annual CDF with credit for SAT i.e.,

Plant Wilson Swyd or cts dCDF sussuc + 2.53 E-06 N/A CDF contribution from Seismic and TornW TORNAto CvCnts CDFn 3.432 E-05 1.13E-02 Average annual non hurricane season CDF with credit for SAT i.e., Plant Wilson Swyd or cts CDFr 4.165E-05 1.13 E-02 Average annual non-hurricane season CDF with credit for SAT i.e., Plant Wilson Swyd or cts, assuming EDG -A in maintenance and EDG-B not in maintenance CDFr 4.176E-05 1.13 E-02 Average annual non-hurricane season CDF with no credit for SAT i.e., Plant Wilson Swyd or cts, assuming EDG -B in maintenance and EDG A not in maintenance CDFo 3.514E-05 3.61 E-02 Average annual hurricane season CDF with credit for SAT i.e., Plant Wilson Swyd or cts CDFn 4.609E-5 3.61 E-02 Average annual burricane season CDF with credit for SAT i.e., Plant Wilson Swyd or cts assuming EDG -A in maintenance and EDG-B not in maintenance CDF 4.627 E-5 3.61 E-02 Average annual hurricane season CDF with credit for SAT i.e., Plant Wilson Swyd or cts, assuming EDG -B in maintenance and EDG.A not in maintenance CDF3 4.218E-05 1.43 E-02 Average annual CD5 with credit for S AT i.e.,

Plant Wilson Swyd or cts, assuming EDG -

A in maintenance and EDG-B not in maintenance CDFg 4.231 E-05 1.43 E-02 Average annual CDF with credit for SAT i.e.,

Plant Wilson Swyd or cts, assuming EDG -

B in maintenance and EDG-A not in maintenance CDF.i 7.500E-05 1.43 E-02 Average annual CDF with credit for SAT i.e.,

Plant Wilson Swyd or cts, assuming EDG -

A and TDAFW in maintenance, and EDG-B and MDAFW pumps not in maintenance --

CDFu 7.355E-4 1.43 E-02 Average annual CDF with credit for SAT i.e.,

Plant Wilson Swyd or cts, assuming EDG-B and NSCW train B in maintenancs, and EDG-A and NSCW train A not in mainteaance 1

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Tchie 2 EDG Etiended AOT Risk Ma===ement Guidelines TABLE 2 i EDG EXTENDED AOT RISK MANAGEMENT GUIDELINES CDFnst (1) PSI (2) PSI (3) CORRECTIVE ACTIONS & TIME APPROVAL POSSlHLE POSSlHLE COLORS CONSTRAINTS LEVEL (6)-

VALUES VALUES CORRECTIVE DURurx ACTIONS (5) POSSIBLE VALUES (4)

CDFIN sr < PSI > 9,34 GREEN None, DURurx > 350 Planning Group SE-05 11rs SE-05 5 7.17 < PSI $ YELLOW Include safety 18 lirs < Shift Supervisor CDFi ssi < 9.34 assessment insights DURuxx s350 SE-04 in pre shift ilts meetings.

SE-015 6.52 < PSI 5 ORANGE Either restore 9 lirs< DURy4x Plant General CDF i wsr < 7.17 inoperable il811rs Manager iE-03 equipment to operable status or restore inoperable EDG to operable status, IE-03 s PSI 5 6.52 RED Promptly DURuxx s 9 lirs Vice President CDFi sst implement compensatory measures to reduce core damage risk, Note 1: Instantaneous Core Damage Frequency (CDFmsT ) is defined as the annual conditional CDF of any plant configuration based on the availability of an SSC(s)(that are modeled in the PRA) during that plant configuration.

Note 2: Plant Sarcty Index (PSI)

PSI = 100 { log (CD&r)+ Log (2.494E-05)

Note 3: PSI Colors refer to the different colors bands corresponding to ranges of PSI on the EOOS Operators panel Note 4: Maximum Duration Limit ilrs. (DURmx) defines a recommended duration for a specific plant configuration based on CDFi sst and an acceptab!c change in CDP of IE 06. The actual configumion-specific maximum duration limit is a function of the CDF nsT. i

- DURat = (IE - 06) O (8760) + (CDhr - 2,494 E - 05)

Note 5: Corrective Actions are the recommended actions to be implemented when the PSI Colcr band is other than " Green" for the purpose of either alerting the plant shill stafTof the increased configuration specil'c core damage risk or initiating actions to decrease configuration specific core damage risk to desired levels, Note 6: Approval Levels are the recommended management level personnel who are required to grant authorization for being in an EDG extended AOT condition depending on the PSI Color band.

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Attachme:t 13 Tcble 2 Vogtle Electric Generating Plant Request to Revise Technical Specifications,"AC - Sources Operating" Emergency Diesel Generator Extended AOT Request CRMP General Guldellats General Guidelines The 14 day AOT for the EDG will cause the PSI to be in the EOOS PSI color band of " Green",

in cases of emergent work, VEGP EOOS will be used to calculate a revised PSI to determine the safety significance of scheduled EDG maintenance coincident with emergent work. The rcsulting EOOS output, consistent with the EDG Extended AOT Risk Management Guidelines provided in Table 2, will be used as an input by Onshih Operations staffin developing a Safety Assessment of scheduled EDG maintenance coincident with emergent work.

If emergent work (equipment failure) occurs during an EDG outage, the on-shih Operations staff will respond to restore safety functions and provide compensatory measures to minimize the consequences of out of service equipment. The appropriate shih Operations personnel will contact Outages and Planning for assistance in using EOOS sonware for evaluating the safety impact of emergent equipment failures.

It should be recognized that the capabilities of EOOS provides one of the many inputs to the development of Safety Assessments of scheduled EDG maintenance and any coincident emergent work. The overall Safety Assessment of scheduled EDG maintenance and any coincident emergent work is performed by knowledgeable and experienced personnel and they will continue to assert a key role in assuring that the scheduled EDO maintenance and any coincident emergent work does not place the plant in an unsafe condition. The Safety Assessment performed prior to the scheduled EDG maintenar>cc includes a multi discipline review by Operations, Maintenance and t entral scheduling personnel as part of the daily " plan-of the-day"(POD) meetings.

Uncertainties in the results of VEGP EOOS calculations will be addressed by the qualitative assessment discussed previously in Enclosure 1.

The above discussion relates to the current SNC plans for implementation of a CRMP at VEGP using EOOS Details of risk screening criteria are provided for your information. Use cf these criteria and this particular schware may be changed in the future to take into account experiences

. gained in the industry and within SNC in using this risk informed methodology.

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Eccios:re 4 Vogtle Electric Generating Plant Request to Revise Technical Specifications, "AC Sources - Operatine,"

Emereeney Diesel Generator Extended AOT Reaucal T!i and haes Changeslaatdinalattrudinna Remove Page Insert Pagg 3.8-2 3.8-2 3.8-3 3.8-3 and inserts land 2 for Condition B 3.8-4 3.8-4 and Insert New Condition C 3.8-5 3.85 5.0 17 5.0-27 and insert for New 5.5.18 0 3.8-5 B 3.8 5 B 3.8-6 B 3.8-6 B 3.8-7 B3.8-7 B 3.8-8 B 3.8-3 and Insert for New Required Action B.2 B 3.8-9 B 3.8 9 B 3.8-10 B 3.810 and Insert for New Required Action B.S.1, B.S.2, and B.6 B 3.811 B 3.811 and insert for New Condition C B 3.812 B 3.812 B 3.8-13 B3.8-13 D 3.8-14 B 3.8-14 8 3.8-15 B 3.8-15 1