ML19210D692

Deficiency Rept Re Pipe Stress Analysis for safety-related Sys Showing Nonconservative Pipe Stresses.S&W Will Reanalyze All Isometric Pipe Drawings Affected & Mods Will Be Made as Required

ML19210D692
Person / Time
Site:	North Anna
Issue date:	11/09/1979
From:	Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
References
REF-PT21-79-172-000 934, NUDOCS 7911270457
Download: ML19210D692 (2)

Text

. . - . . _ . - . _ . . . .

c J ". ' -

7 % h.2-oo o O _ .... .... - -- .....-.-.- -.

. . , .. g

"

.1 - -

November 9, 1979 Mr. James P. O'Reilly, Director Serial No. 934 Office of Inspection & Enforcement PSE&C/CGC:mac: wang U. S. Nuclear Regulatory Cocnission Region II Docket No. 50-339 ,

101 Marietta Street, Suite 3100 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

On Novenber 5,1979, a report was made under the provisions of 10CF9.50.55(e) concerning seismic response spectrun curves in some pipe stress analyses.

In accordance with the reporting requirements of 10CFR21, the following information is submitted:

A. Nam and address of' reporting individual:

Mr. E. A. Baum, Executive Manager Licensing and Quality Assurance " " ^ ' '

Virginia Electric and Power Company D* D D' ~~D P. O. Box 26666

]_J g Richmond, Virginia 23261 B. Facility, activity and/or cocponent affected:

North anna Power Station, Unit 2 Some Safety Related Pipe Systams C. Name of firm constructing the facility or supplying the component, activity or service:

Stone & Webster Engineering Corporation P. O. Box 2325 Boston, Massachusetts 02107 D. Description of detect, deficiency, or failure t'o comply:

We have discovered a problem concerning amolified response soectrum

_(ARS) curves applied in some pipe stress analyses for safety related systems; this problem could vield unconservative pipe stresses 1 pipe support loads, and equipment loads.

We have determined that this p-oblem applies to 44 MSK's (an MSK is an iscrnetric piping drawing) on Unit 1; however,18 of these 44 PSK's are applicable to Unit 2 as well. To date, reanalysis has identified two pipes onduring overstressed Unit 1accident and oneconditions.

pipe on Unit 2 which would be % g

}

7 911270 +5 7

,,. D(-

. . . . . . 2 .

date of detertaination of reportability:

~

E. n Novenber 5,.1979 b F. Similar ccr onents, activities, or services:

North Anna Power Station, Unit 1 S. Corrective action which has been, is being or will be taken, the individual responsible and the length of time to complete the action:

Stone & Webster has already begun a program to reanalyze all MSK's "

- - -.. zffected by this problem. Modif.ications wil.l..be made as required, H. Other information:

None Any information noi available at this time will be submitted in a fo11cw-up 1atter at a 30-day report.

Should you require further information, please contact this office.

/I'"T"e s

Senior ice Dresiden,t - Powe tation Enginee ing and Constru s~on ec: Director, Office of Inspection and Enforcement (3)

J