ML17311A238

Submits Commitment Change to NRC to Ensure That Electric Equipment Would Not Be Energized & Operated in Excess of Continuous Rating Under Expected Switchyard Voltages

ML17311A238
Person / Time
Site:	Palo Verde
Issue date:	08/24/1994
From:	Stewart W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9409070250
Download: ML17311A238 (6)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

>pa ACCESSION NBR-9409070250 DOC.DATE: 94/08/24 NOTARIZED: NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 p

AUTH.NAME AUTHOR AFFILIATION STEWART,W.L.

Arizona Public Service Co.

(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards NRC Commitment change to ensure that electric equipment would not be energy.zed

& operated in excess of continuous rating under expected switchyard voltages.

DISTRIBUTION CODE:

AOOID COPIES RECEIVED:LTR J ENCL 0 SIZE:

TITLE: OR Submittal: General Distribution NOTES:STANDARDIZED PLANT Standardized plant.

Standardized plant.

0 05000528 1

05000529 05000530 RECIPIENT ID CODE/NAME PD4-2 LA HOLIAN, B INTERNAL: ACRS NRR/DRCH/HICB NRR/DSSA/SPLB NUDOCS-ABSTRACT OGC/HDS2 EXTERNAL: NOAC COPIES LTTR E CL 1

2 RECIPIENT ID CODE/NAME PD4-2 PD TRAN,L NRR/DE/EELB NRR/DRPW NRR/DSSA/SRXB OC/LFDCB 01 NRC PDR COPIES LTTR ENCL Y

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N NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACTTHE DOCUMENTCONTROL DESK, ROOM PI-37 (EXT. 504-2083 ) TO ELIMINATEYOUR NAMEFROM DISTRIBUTIONLISTS I'OR DOCUMENTS YOU DON"I NEED!

TOTAL NUMBER OF COPIES REQUIRED:

LTTR 23 ENCL

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Arizona Public Service Company P.O. BOX 53999

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PHOENIX, ARIZONA85072-3999 WILLIAML. STEWART EXECUTIVEVICEPRESIDENT NUCLEAR 102-03095-WLS/AKK/RKR August 24, 1994 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3 Docket Nos. STN 50-528/529/530 NRC Commitment Change File: 94-056-026 In a November 29, 1984 submittal (ANPP-31 244), Arizona Public Service Company (APS) responded to NRC staff questions on overvoltage conditions at PVNGS. As part of the

response, APS committed to check essential safety feature (ESF) transformer bus voltages and change tap settings prior to initiation of refueling and plant operation activities.

At that time, this commitment ensured that electric equipment would not be energized and operated in excess of the continuous ratings under expected switchyard voltages.

Since that time, APS'nowledge of the electrical distribution system, including switchyard voltages, is more complete. APS has determined, based on experience used to complete more realistic design calculations, that it is not practical to change tap settings to accommodate light load conditions present during normal power operations or during refueling outages and still obtain viable distribution voltages under a fast bus transfer scenario.

The analysis examined both overvoltage and undervoltage concerns.

The analysis found that it was best to use a single tap setting that meets all of the operating requirements.

Any subsequent tap changes would require a complete reanalysis to include calculation of minimum distribution system voltage at maximum loads and minimum anticipated offsite voltage, maximum distribution system voltage at minimum loads and maximum anticipated offsite voltage, and an analysis to ensure the terminal voltage presented to loads are within equipment ratings or are evaluated and justified.

Therefore, APS no longer considers this commitment to be valid.

Elimination of this commitment will result in a cost savings of over $250,000 over the life of the units.

This submittal is provided for your information.

940'TI070250 940824 PDR ADOCK 05000528 iI I

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U. S. Nucle'ar Regulatory Commission ATIN: Document Control Desk NRC Commitment Change Page 2 Should you have any questions, please contact Scott A. Bauer at (602) 393-5978.

Sincerely, WLS/AKK/RKR/dpr cc:

L. J. Callan B. E. Holian K. E. Perkins K. E. Johnston A. V. Godwin ARRA

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