ML20055D306

Ro:On 900530,differential Settlement Between Containment & Main Steam Valve House Exceeded 75% of Allowable Value of 0.030 Ft.Caused by Stresses Placed on Main Steam,Feedwater, Svc Water & Condenser Air Ejector Piping.Rept Reviewed

ML20055D306
Person / Time
Site:	North Anna
Issue date:	06/29/1990
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
90-385, NUDOCS 9007060141
Download: ML20055D306 (2)

Text

-

c.

VIHOINIA ELECTHIC AND POWEN COMPANY Iticunoxu,Vinoisir couni June 29, 1990 U.S. Nuclear Regulatory Commission Serial No. 90 385 Attention: Document Control Desk NAPS /RCS/rcs Washington, D.C. 20555 Docket Nos. 50-339 License Nos. NPF-7 -

Gentlemen:

BRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 2 '

DIFFERENTIAL Sr UNIT 2 fCONTAINMENT AND THE LINIT 2 MAIN STEA'M VALVE HOUSE On May 30,1990, the differential settlement between the Unit 2 Containment (survey point 131) and the Unit 2 Main Steam Valve House (survey point 124),

as specified in Table 3.7-5 of Technical Specification 3.7.12.1,' was confirmed to have exceeded 75 percent of the allowable value of 0.030 feet. The differential settlement between survey points 131 and 124, calculated during the performance of Periodic Test I-PT-112, " Category 1 Structures '- Settlement- '

E Monitoring", on May 30,1990 was 0.025 feet, or 83 percent of 0.030 feet. This l

Special Report is being submitted pursuant-to the requirements of Technical l

Specification 3.7.12.1.

The bases for monitoring the differential settlement between the Unit 2 Containment and the Unit 2 Main Steam Valve House are the stresses placed 3 on the Main Steam, Feedwater, Service Water, and Condenser Air Ejector l piping. These lines possess adequate flexibility to absorb 0.030 feet of differential settlement as described in an earlier special report, Serial No. 89-L 540, submitted July 27,1989. The July 1989 submittal was the result of survey

' points 131 and 124 exceeding 75 percent of 0.030 feet differential settlement based on results of the May 1989 differential settlement survey.

L

! On October 2,1989, Virginia Electric and Power Company submitted a .

L' Technical Specification change request (Serial No.89-682) which proposed the deletion of the requirement to monitor survey points 131 and 124 along with

'other rock founded structures. Technical Report," Evaluation of Settlement Monitoring Program for Main Plant Structures in Support of F oposed Changes to' Technical Specification 3/4.7.12," which was Attachment 4 to this October i . 1989 submittal, provides the technical basis for deletion of the requirement to

. monitor these and other points.

A

'l h

9007o6o141 900629

,PDR- ADOCK o$ooo339 (g

S PDC

w -

p

.., . e-

> Based on the above, the structuralintegrity of the piping represented by points 131 and 124 has not been compromised. This Special Report has been reviewed by the Station Nuclear Safety and Operating Committee. l Should you have any questions regarding this report, please contact us at your earliest convenience. ,

i Very truly yours y i W. L. St rt Senior Vice President - Nuclear a cc: U.S. Nuclear Regulatory Commission Region ll i 101 Marietta Street, N.W..

' Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident inspector North Anna Power Station i

,p a

'.I' r

l .'

j-l u.

A1. '

i,[h ; i NH ' , , 'N