ML20117C357

Provides Statement of Conditions & Response to 960725 Telcon W/Sa Varga Re Request for Extended AOT for EDGs

ML20117C357
Person / Time
Site:	Vogtle
Issue date:	08/23/1996
From:	Woodard J GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20117C361	List: ML20117C357 ML20117C415
References
RTR-NUREG-1431 LCV-0603-R, LCV-603-R, TAC-M92131, TAC-M92132, NUDOCS 9608270368
Download: ML20117C357 (5)

Text

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Georgia Power Company

, , 333 Piedmont Avenue Atlanta. Georgra 30308

,p Te:ephone 404 52fc3195 Mail [ng Address 40 Inverness Center Parkway Post 0%ce Box 1295 ,

Birmingham, Alabama 35201 Telephone 205 B60-5086 J. D. Woodard l'e mo!NM 'xtoc num Senior Vece President August 23, 1996 l LCV-0603-R Docket Nos. 50-424 1 50-425  ;

TAC Nos. M92131 1 M92132 1

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk i Washington, D. C. 20555 Gentlemen:

VOGTLE ELECTRIC GENERATING PLANT I PROPOSED CONVERSION OF Tile UNIT 1 AND 2 TECHNICAL SPECIFICATIONS BASED ON NUREG-1431 On July 25.1996, a telephone conversation was held between Mr. J. D. Woodard of Georgia i Power Company (GPC) and Mr. Steven A. Varga of the NRC concerning our request for an extended allowed outage time (AOT) for the emergency diesel generators (DGs) as documented in our May 6,1996 letter (LCV-0603-P) and as supplemented by our June 17, 1996, letter (LCV-0603-L). During that telephone conversation, the NRC presented specific I conditions which, ifimplemented at the Vogtle Electric Generating Plant (VEGP), would result in NRC approval of our requested extended DG AOT. The following is a statement of those conditions and our response.

The time of year that the extended DG AOT may be used must be limited so as to minimize the potential for weather-related events such as hurricanes occurring while a DG is i

inoperable. Enclosed are marked up pages from the VEGP Unit 1 and Unit 2 improved '

Technical Specifications (TS) and Bases that accompanied our June 17,1996 letter (Enclosure 1). Limiting Condition for Operation (LCO) 3.8.1 has been marked to show a new Required Action B.l. Upon entry into Condition B ("One DG inoperable"), Required Action B.1 requires verification that the calendar date does not fall on or within the period

! July 15 through November 15. If at any time while the DG is inoperable the date does fall I within this period, Condition C must be entered, and the DG must be restored to operable l status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from entry into Condition C. This will effectively prevent preplanned main'enance that might involve an extended I)G AOT that falls on or within this period of time.

9608270368 960823 PDR ADOCK 05000424 P PDR i

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U. S. Nuclear Regulatory Commission

~ ' LCV'0603-R Page 2 l

l 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 I

l steady state voltage and frequency. 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 l removing a DG from sersice 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 l l DG from service for the extended AOT. See Required Action B.6.1 in the enclosed marked up pages. This Required Action is contingent on the combined reliability of the enhanced ,

l black-start CTGs having been demonstrated and maintained to be 2 95 %. Prior to

' l 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 extended AOT. In this case the l CTG must be started prior to removing the DG from service for preplanned maintenance that l would require the DG to be out of service for an extended AOT. For unplanned DG l i

inoperabilities requiring an extended AOT, the CTG most be started 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. See Required Action B.6.2 in the enclosed marked up pages. ,

As stated in the enclosed proposed Bases for Required Action B.6.2, any one of the six CTGs l may be started for the purposes of Required Action B.6.2. If a CTG is allowed to run while a >

DG is out if service, it is not necessary that the CTG be one of the two enhanced black-start CTGs. In addition, the proposed Bases for Required Action B.6.2 state that if the running CTG fails, one of the remaining CTGs must be started within I hour. In the unlikely event l 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.  !

l In order that a DG may be removed from service for an extended AOT, the standby auxiliary transformer (SAT) must be available. This requirement is expressed as Required Action B.2  !

of LCO 3.8.1. The NRC staff has expressed concern that for the SAT to be available it must be energized via the underground line from it's switchyard. The Bases for LCO 3.8.1 define SAT availability as, in part, that the SAT must be operable in accordance with plant j procedures. " Operable in accordance with plant procedures" means that, as a minimum, the SAT would be energized via the underground line from it's switchyard.

If a DG is to be removed from service for an extended AOT without requiring that a CTG be operated throughout the time that the DG is inoperable, then the enhanced black-start CTGs must have a demonstrated reliability of 2 95 %. The reliability of the enhanced black-start l CTGs will be demonstrated by performing a minimum of 20 starts and load-runs of at least I hour on cuch 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 1 l hour. The combined reliability of the two enhanced black-start CTGs and the black-start diesel generator must be 2 95 %. A successful start will be defmed as a CTG achieving  ;

, steady state voltage and frequency within acceptable limits and time. For the purpose of  ;

supporting a 14-day AOT, the acceptable time is dermed as I hour. A successful load-run

l U. S. Nuclear Regulatory Commission

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• LCV10603-R

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l l will be declared if the CTG runs with its output breaker closed for I hour. The combined reliability will be calculated as follows: I 4

Combined reliability = [(Reliability of CTA + Reliability of CTB)-(Reliability of

CTA* Reliability of CTB)]* Reliability of black-start DG The reliability of CTA or CTB will be defined as

Reliability of CT(A/B) = Start Reliability

• Load-run Reliability Where:

, Start Reliability = Number of successful starts / Number of start demands Load-run Reliability = Number of successful load-runs / Total number ofload-run l demands The reliability of the enhanced black-start CTGs (including the black-start diesel generator) will be maintained by quarterly testing. A commitment to quarterly testing appears in the proposed Bases for new Required Action B.6.1 in the enclosed marked up pages.

The next condition involves establishing procedures for use of the enhanced black-start CTGs and support systems. Additional guidance was provided by the NRC on the afternoon of July 25, and this guidance stated that "the licensee must develop procedures to black-start a CT and provide power to the 4.16 kV safety bus within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> In our May 6,1996, letter LCV-0603-P, we made the following commitment:

e If a CT black-start appears to be necessary during the extended EDG A0T, e.g.

Impending extremely severe weather or the Southern Electric System has been identified as being potentially unstable due to events in the system, thefollowing action l willbe taken.

An operator will report to The CT site and prepare for a CT black-start by placing at least one CT on turning gear. Under these conditions, a CT has been demonstrated to be capable of being black-started within I hour. The alignment of the CT switchyard / SAT line to VEGP for safe cool down purposes can be performed in  ;'

parallel with a CT black-start and has also been accomplished within I hour.

GPC will have procedures in place to implement the above commitment prior to entering an extended DG AOT. In addition,in our June 17,1996, letter LCV-0603-L, we committed to demonstrate the complete enhanced black-start generation capability at least once per 18 months. Therefore, the appropriate Operations personnel will be trained in the use of these

U. S. Nuclear Regulatory Commission

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• LCV-0603-R Page 4 procedures, and the procedures will be available to the appropaate Opentions personnel during a 14-day DG AOT.

Finally, the NRC stated that we must have a configuration isk management program in place prior to entering an extended DG AOT. NRC guidance provided later on the afternoon of July 25 requested that GPC include the SAT in the "lPE Tool" and consider "more than the top 500 sequences." (The existing "IPE Tool" does not include the SAT and/or the CTGs, and all of the calculated risk indicators in support of the proposed extended DG AOT to this point have considered only the top 500 sequences.)

It is cur intention to begin work on an updated IPE model this fall with completion projected for the middle of 1997. This updated model will include the SAT and the CTGs, and it will generate cut-sets as opposed to sequences. It can be used to evaluate plant configurations fbr risk significance, and it will be used to develop a plant-specific equipment out-of-service (EOOS) model based on EPRI methodology. The EOOS model is designed fbr evaluating plant configurations for risk significance, and we project that it will be in place by the end of 1997. Given the above plan for developing more useable risk evaluation tools, GPC is reluctant to divert resources for the purpose ofincluding the SAT and the CTGs in the "lPE Tool" and for evaluating more than the top 500 sequences. However, in the interim, GPC can use the "IPE Tool" to evaluate the risk significance of plant configurations given that a DG is ineperable fbr an extended period. Enclosure 2 documents the results of our evaluation of the impact on risk due to the proposed extended DG AOT using the existing IPE model.

GPC will develop a program to assess changes in core damage frequency associated with applicable at-power plant configurations when a DG is out of service for an extended period.

This program will use the "lPE Tool" in the interim for assessing the risk significance of plant configurations, and it will adopt the updated risk evaluation tools (as discussed above) as they are put into place. This program will be in place prior to removing a DG from service for an extended AOT, and it will include:

e training of appropriate personnel, e provisions 1br identifying plant configurations and the evaluation of risk against established thresholds; and

. provisions Ihr evaluating changes in overall plant core damage risk resulting from unplanned maintenance activities.

Please note that GPC considers the preceding discussion to be a complete set of commitments regarding the proposed extended DG AOT. Therefore, this letter supersedes all prior letters and verbal agreements as they relate to this subject.

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U. S. Nuclear Regulatory Commission

' LCV-0603-R Page 5 in our June 17,1996 letter, we transmitted a complete set of TS and Bases. Since that time, an error was identified in Table 3.3.1-1, page 5 of 8. Function 16.e. The Allowable Value and Trip Setpoint for Power Range Neutron Flux, P-10 are incorrectly shown as s 12.3 %

and s 10 % respectively. The correct values are 2 7.7 % for the Allowable Value and 210

% for the Trip Setpoint. These values are consistent with the current TS requirements. The incorrect values were simply the result of a typographical error. In addition, a limited number of editorial corrections of a non-technical nature are included. For your convenience, marked up pages showing these corrections are provided as Enclosure 3.

Enclosure 4 is a complete clean typed copy of the TS and Bases reflecting the changes discussed in this letter.

The changes to the TS proposed herein do not alter the conclusions of the evaluations I performed pursuant to 10 CFR 50.92 that have been previously docketed with respect to the

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conversion of the VEGP TS based on the improved standard TS. j Finally, GPC regrests that the preceding proposed responses to the conditions of the j aforementioned July 25,1996, telephone call receive a timely review so that the license i amendments can be issued by September 23,1996, with implementation within 150 days of issuance.

Sincerely, i k

D. Voodard JDW/NJS Enclosures xc: Georyia Power Comnany hir. C. K. McCoy (w/o Enclosure 4)

Mr. J. B. Beasley, Jr. (w/o Enclosure 4)

Mr. M. Sheibani (w/o Enclosure 4) j NORMS (w/o Enclosure 4)  ;

U. S. Nuclear Reyulatory Commission Mr. S. D. Ebneter, Regional Administrator (w/o Enclosure 4)

Mr. L. L. Wheeler, Licensing Project Manager, NRR (all Enclosures)

Mr. C. R. Ogle, Senior Resident inspector, Vogtle (w/o Enclosure 4)