ML20010J551

Forwards Info Re Mechanical,Electrical & Operating Characteristics of Recently Installed Generator Breaker. Breaker Reduces Probability of Unit 1 Normal Station Svc Buses Being Fed from Reserve Station Svc Transformers

ML20010J551
Person / Time
Site:	North Anna
Issue date:	09/23/1981
From:	Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Clark R, Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20010J552	List: ML20010J551 ML20010J554 ML20010J556
References
908B, NUDOCS 8110050332
Download: ML20010J551 (2)

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Mr. Harold R. Denton, Director Serial No. 9G8B Office of Nuclear Reactor Regulation PSE&C/KSB Attention: Mr. Robert A. Clark, Chief Docket No. 50-338 Operating Reactors Branch No. 3 50-339 Division of Licensing l

U. S. Nuclear Regulatory Commission License Nos. NPF-4 Washington, D. C. 20555 NPF-7

Dear Mr. Denton:

i GENERAL DESIGN CRITERIA 17 ANA'.YSIS _

NORTH ANNA UNIT NOS. 1 AND 2 In our letter to ycu dated Julv 24, 1981, Serial No. 908A, we discussed our installe. ion of a generator breaker on North Ann: Unit 1. In that letter, we committed to provide you with mechanical, electrical, and operating characteristics of the breaker by September 24, 1981. This letter transmits the specified data. Attached are copies of the Technical Specifications issued for the breaker, of the instruction manuals for the breaker and its cooling and compressed air plants, and of the Brown Boveri quality assurance program referred to in the Technical Specifications.

In reference to a May 20, 1981 telephone conference between the NRC and Vepco, the above data documents the tests and specifications required for the breaker. Incin@d in the Technical Specifications are impedance values from which the maximum symmetrical and asymmetrical faults, which the breaker I would be required to interrupt, can be calculated. These values are a result of computer analyses of potential worst. case electrical faults. The breaker will interrupt the worst case generator contribution to a fault and it will interrupt the worst case system contribution to a fault.

The purpose of the breaker installation wr.s addressed in our July 24, 1981 letter. To briefly reiterate, the breaker reduces the probability of Unit 1 Normal Station Service bnes being fe1 from the Reserve Station Service transfomers, thereby reducing Une probability of simultaneous loading from Unit 1 and Unit 2 on the Reserve Station Service transformers. With the addition of the normal to emergency bus ties, the generator breaker provides

for an additional independent source of off-site power from the transmission network to the on-site power distribution system, which is analogous to the Reserve Station Service System, that is not dependent on the mode of operation of the Unit 1 generator.

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V wotNr4 Et.rcTuic AND rOWEN COMMNY TO Mr. Harold R. Denton, Director Page 2 Should you require further information on this su'c ject, please advise.

Very tri y ours,

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R. H. Leasourg Vice President Nuclear Operations Attachments KSP/cdk cc: Mr. J. P. O'Reilly, Director Office of Inspection and Enforcement Region II

!E Soecifications 4199 VIRGINIA ELECTRIC AND POWER COMPANY

RICHMOND, VIRGINIA NORTH ANNA UNITS 1 and 2

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I -l Technical Requirements I For Furnishing of Generator Circuit Breakers i

Purchase Specifications a

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VIRGINIA ELECTRIC AND POWER COMPANY February, 1980 L/2317/2 I

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I Specifications 4193 (Purchasing Issue) l I Summarv of Contents ENCLOSURE 1 SPECIFICATIONS 4198 Part II - Bid Form i Part VI - Technical Specifications ~

ENCLOSURE 2 VEPC0 Certification of Conformance ENCLOSURE 3 VEPC0 Licensing and Quality Assurance l8 VENDOR Surveillance Inspection Report l

ENCLOSURE 4 Virginia Sales and Use Tax Direct Payment Permit l

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