ML20003G681

Informs of Westinghouse Recalculations of Recommended Insp Intervals for Unit 1 Turbine Using Current Methods. Related Correspondence

ML20003G681
Person / Time
Site:	North Anna
Issue date:	04/21/1981
From:	Christman J HUNTON & WILLIAMS
To:	Buck J, Quarles L, Rosenthal A NRC ATOMIC SAFETY & LICENSING APPEAL PANEL (ASLAP)
References
ISSUANCES-OL, NUDOCS 8104300519
Download: ML20003G681 (2)

Text

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' ~ Y-- * ~D 02.23?02'~~C H uxrox & WILLIA >IS - ' '

707 East M AIN s? Ret? P. o. Box 1535 e o a ? ouisc.~e Rrenxoxo, VrmorxtA 202N .....c...............

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April 21, 1981 E g -

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Alan S. Rosenthal, Esq. M;" % gecuaro,,

• Atomic Safety and Licensing Appeal '

YY Board U.S. Nuclear Regulatory Commission / i _. g . e9

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Uashington, D.C, 20555

, h-Dr. John H. Buck -

- D Atomic Safety and Licensing Appeal ge g Board ure0 U.S. Nuclear Regulatory Concission 4 -

Washington, D.C. 20555 $ APR 2 31981 * %l '

Dr. Lawrence R. Quarles q, cmce y s ten:

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Atomic Safety and Licensing Appeal J //

Board g U.S. Nuclear Regulatory Commission -

Washington, D.C. 20555 l

l Virginia Electric and Power Company (North Anna Power Station, Units 1 and 2)'

l Docket Nos. 50-338 OL and 50-339 OL Turbine Missiles Centlemen:

Westirghouse has recalculated the recon = ended inspec-tion intervals for the North Anna 1 turbine using the current methods. Although Vepco has received nothing in writing from Westinghouse yet, we are informed by phone that the results of the new calculations are as follows:

LP#1

, Disk End Time in Months l

1. 1 GVN 23.0

1. 1 GNN 28.3 f

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\\D l

l 1

8104300 519

Howrow & WILLIAMS Alan S. Rosenthal, Esq.

Dr. John H. Buck Dr. Lawrence R. Quarles April 21, 1981 -

Page Two Disk End Time in Months

1. 2 GVN 34.5

1. 2 GNN 35.9 LP#2 Disk End Time in Months

1. 1 GVN 31.4

1. 1 GNN 22.8

1. 2 GVN 45.0

1. 2 GNN 39.7 As you see, the critical disk is now disk no. 1, generator end, l of the replacement rotor from Three Mile Island, which has a

recommended inspection interval of 22.8 months. -

l -

t I understand that the preparation of the Westinghouse topical reports is proceeding pretty much on schedule and should be finished around the end of this month. Because of the changes that have been made in the methods of calculating the l

probabilities of turbine missile generation, Westinghouse will have to calculate new P1 numbers for the North Anna units. We are still planning to submit to you a final package of infor-mation on the long-term turbine missile risk at North Anna, but l I am not sure exactly how long it will take Westinghouse to

! calculate new P- values and Stone & Webster to calculate new l

P4 values. I w:.ll advise you when I know more about the schedule.

Yours very truly,

b. M James N. Christman

126/586 l cc

Anthony J. Gambardella, Esq.

l Stuart Treby, Esq.

l Chief, Docketing and Service Section /'

l i

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