ML20206H261

Part 21 Rept Re Defect Found in Potter & Brumfield Relays. Sixteen Relays Supplied in Lot 913501 by Vendor as Commercial Grade Items.Caused by Insufficient Contact Pad Welding.Relays Replaced with New Relays

ML20206H261
Person / Time
Site:	San Onofre
Issue date:	05/05/1999
From:	Nunn D SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-99 NUDOCS 9905110120
Download: ML20206H261 (4)

Text

MEL%R4sW1W1155 frax:949-368-7575 May 6 '99 12:20 P.02

, SOUTHERN CAUFORNIA EDISON =g-Ancmsommunouv c ,..,

May 5,1999 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

10CFR Part 21 Notification - Potter & Brumfield Relays San Onofre Nuclear Generating Station, Units 2 & 3 in accordance with 10CFR 21.21(d)(3) and 21.21(d)(4), the attachment to this letter reports a defect found in Potter and Brumfield (P&B) relays. Sixteen P&B relays, model KUP93-14A32-120. were supplied in lot '913501" by the vendor as commercial grade items and were dedicated for nuclear service at San Onofre Nuclear Generating Station by Southern California Edison (SCE). SCE's laboratory analyses of four of these relays determined the contact pads were insufficiently welded to their contact arms and could become detached. Based on a review of relay failure history, SCE has concluded the insufficient contact pad welding is limited to lot 913501.

i SCE replaced these relays with new P&B relays which have contact pads that are riveted to their contact arm, thus precluding contact pad detachment.

l My signature below satisfies the notification requirements of 10CFR21.21(d)(4). If you '

require any additional information, please contact me or Mr. Ken Slagte at (949)368 6631.

I Sincere!

\  : .w I

Attachment 1 cc: E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Resident inspector, San Onofre Units 2 and 3 L. Raghavan, NRC Project Manager, San Onofre Units 2 and 3 institute of Nuclear Power Operations (INPO)

P. O. Box 128 San Cicmeme. CA 926744126 #

9. 68 490

• NUCLEAR REG AFFAIRS Fax:949-368-7575 May 6 '99 12:21 P.03 4

a Attachment i 10 CFR Part 21 Report on P&B Relays Page 1 of 2 A. CoiTw+,1 Supplier 1

Potter & Brumfield (A Siemens Co.)

200 South Richland Creek Drive Princeton, Indiana 47671 (812) 386-2211 B. Nature of defect:

On March 30,1999, SCE opened the shipping box for new relays, P&B Model .

Number KUP93-14A32-120, and fcund one contact pad was detached from its contact arm in three relays. A review of relay failure history recognized that, in l December of 1998, this same type of relay had failed after 3 years of service. A total of 16 relays from lot '913501"were purchased from Potter & Brumfield as commercial grade items in 1991 and dedicated by SCE for safety related applications.

1 Each relay contains three contact arms with each having four contact pads for a total of twelve contact pads. One of the twelve contact pads was missing in the middle moving arm at the normally closed contact position in these four relays.

Laboratory analysis determined that the contact pads were inadequately fused to the contact arms. Microscopic inspection found only a small weld area between the contact pad and its mating surface on the contact arm. This same condition also existed on the remaining contact pads, although they were still attached. Without a contact pad, there was no make-up connection to close on demand. Therefore, the cause of the defect was insufficient welding of the contact pads to the contact arm.

C. Date defect discovered:

SCE discovered this deviation on March 30,1999, prior to replacement of the rela during preventative maintenance for auxiliary building emergency chiller. On April 29,1999, SCE completed an evaluation and concluded this condition constitutes a defect of a basic component.

~

NLLtN kt6 RFFRIRS Fax:919-368-7575 May. 6 '99 12:21 p,04

~

Attachment 1 10 CFR Part 21 Report on P&B Relays Page 2 of 2 D. Component location:

A total of 16 relays are installed in each train of auxiliary building emergency chillers, SA1513ME335 and ME336. Eleven of the 16 relays in each train are used for alarming functions only; the remaining 5 relays are used for control functions.

E. Corrective actions:

The installed relays from lot "913501" were replaced with new P&B relays containing contact pads which are riveted to their contact arms.

One of the new replacement relays was checked for contact pad-to contact arm bond integrity. Microscopic inspection found that the new P&B relays have contact pads which are riveted to the contact arm instead of welded. This bonding method does not allow the contact pads to become disengaged from their contact arms.

This defect was determined to be specific to lot 913501 based on the following actions.

1.

A pull test to check contact bonding integrity was performed on six other relay lots. The contact pads could not be dislodged from their contact arms. l 2.

One relay from lot *E9120" was also randomly selected for laboratory analysis. Microscopic inspection found that the contact pads had been fused to the contact arms and could not be dislodged from their contact arms 3.

A review of relay failure history indicated that no s!milar failures have occurred at San Onofre from P&B manufacturing lots other than lot 913501. i SCE will enhance the dedication plan for control relays to measure the conta resistance on all relay contacts.

F. Other pertinent information: '

SCE has not supplied this type of component nor has knowledge of it's use at another facility. However, this type of component may have also been dedica nuclear use by another facility.

F \

OV0WI999 U.S. Nucle:r Regul: tory Commission Oper:tions Center Event Report Pagei Power Reactor Event # 35685 I Site: SAN ONOFRE Notification Date / Time: 05/06/1999 15:12 (EDT) l Unit: 2 3 Region: 4 State : CA Event Date iTime: 05/05/1999 (PDT) ,

Reactor Type: [1] W-3-LP,[2] CE,[3] CE Last Modification: 05/06/1999 Containment Type: DRY AMB DRY AMB NRC Notified by: WILLIAMS Notifications: BILL JONES Pv1 HQ Ops ONker: CHAUNCEY GOULD NRR VERN HOGE (FAX)

Emergency Class: NON EMERGENCY 10 CFR Section:

21.21 UNSPECIFIED PARAGRAPH Unit l Scram Code lRX Critinit Power initial RX Mode Curr Power Current RX Mode 2 N Yes 100 Power Operation 100 Power Operation 3 N No 0 Hot Shutdown 0 Hot Shutdown THE LICENSEE HAS DETERMINED THAT A MANUFACTURING DEFECT IS PRESENT ON SOME OF THE POTTER AND BRUMFIELD (P&B) RELAYS THEY HAVE AT THE SITE.

SIXTEEN P&B RELAYS, MODEL "KUP93-14A32-120", WERE SUPPLIED IN LOT "913501" BY THE VENDOR AS COMMERC!AL GRADE ITEMS AND WERE DEDICATED FOR NUCLEAR SERVICE AT SAN ONOFRE.

THE LICENSEE'S LAB ANALYSIS OF FOUR OF THESE RELAYS DETERMINED THE CONTACT PADS VERE INSUFFICIENTLY WELDED TO THEIR CONTACT ARMS AND COULD BECOME DETACHED. BASED ON l THEIR REVIEW OF RELAY FAILURE HISTORY, THE LICENSEE CONCLUDED THE INSUFFICIENT CONTACT PAD WELDING IS LIMITED TO LOT "913501" THESE RELAYS HAVE BEEN REPLACED WITH NEW P&B RELAYS WHICH HAVE THE CONTACT PADS RIVETED TO THEIR CONTACT ARM, THUS PRECLUDING ANY CONTACT DETACHMENT.

l O

1 i

\,h)i Of( l

(

i 1

l