ML19257D447

LER 80-001/01T-0:on 800118,during Review for IE Bulletin 79-14,letdown Lines 3/4-CH-275-1502Q1 & 3/4-CH-123-1502-Q2 Reported Overstressed.Caused by Incorrect Valve Weights Used in Pipe Stress Calculations

ML19257D447
Person / Time
Site:	North Anna
Issue date:	01/31/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19257D444	List: ML19257D443 ML19257D447
References
IEB-79-14, LER-80-001-01T, LER-80-1-1T, NUDOCS 8002040418
Download: ML19257D447 (2)

Text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION (7 7.7) ,

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T DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 L n a nu ry 18, 1 10, Stone & uetster reported that an overstressed condition on eveessl 1

o 3 l 1e tdown lines 3/4"-CH-275-1502-Q1 and 3/4-CH-123-1502-02 had been i.dentified durine o 4 l the review for IE Bulletin 79-14. The stress on each pipe exceeds the nomal or I o s l upse t allowable but is less than faulted allowable. The health and safety of the I o 6 l general public were not af fected by this event. Reportable pursuant to T.S. 6. 9 . 1. I o 7 l 8.i. l O H 7 8 9 SYSTEM CAUSE CAUSE COVP. VALVE CODE CODE SU8 CODE COVPONENT CODE SUSCODE SU8 CODE 7

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44 Gl3l4 4[@ 41 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i o lThe cause for the overstressed piping is that incorrect valve we igh t s we re used in the l l3 l3 ; l pipe stress calculations due to a change in the center of gravity for valvo PCV-1201 1 and a change in we ight for the vent valve in the inlet to the excess letdown heat ex- l 3 3 changer. A snubber will be designed and added to the line in the area of HCV-1201 l

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Doc ke t No. 50-338 Report No. LER 80-001/01T-0 Description of Event On January 18, 1980, during a review for IE Bulletin 79-14, Stone & Uebster discovered several points on excess le tdown lines 3/4"-CH-275-1502-Q1 and 3/4"-CH-123-1502-Q2 which are stressed over the normal or upset allowable.

The stress on these lines, however, is less than faulted allowable.

Probable Cansequences of Event Because the stress on the pipes is groter than the normal allowable, it is possible that minor deformation of the piping could develop during a seismic event. But because the stress does not exceed the emergency or faulted allowable, no major deformation or actual pipe separation should occur. Also, the effects of this nonconformance are minimized by the fact that the overstressed point is normally isolated from the primary system during normal plant operat2on. As a result, the health and safety of the general public were not af fected by this event. The re are no generic implications associated with this occurrence.

Cause of Event:

The piping is overstressed because incorrect valve weights were used in the pipe stress calculations. The center of gravity for valve HCV-1201 changed from 37 inches of f centerline to 173 inches of f centerline and the weight of the vent valve on the in le t to the excess le tdown heat exchanger changed from 7 lbs. to 12 lbs.

Innediate Corrective Action A snubber is being designed to support the piping and alleviate the overstressed cor.dition.

Scheduled Corrective Action During the next outage of sufficient duration, the snubber will be added to the line in the area of valve HCV-1201.

Actions Taken to Prevent Recurrance No further actions are required.

1866 '077

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