ML20197J637

Part 21 Rept Re Possibility of Power Supply hang-up When Energizing Slv Relays.Changes Made in Power Supply Circuitry.Slv Relays,W/Mods Incorporated in Latest Designs, Extensively Tested W/O Power Supply Failures

ML20197J637
Person / Time
Site:	Surry, North Anna, Clinton, 05000000
Issue date:	05/12/1986
From:	Mankoff L GENERAL ELECTRIC CO.
To:	Taylor J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-86, REF-PT21-86-184-000 PT21-86-184, PT21-86-184-000, NUDOCS 8605200111
Download: ML20197J637 (2)

Text

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o GENERAL $ ELECTRIC METER AND CONTROL BUSINESS DEPARTMENT GENERAL ELECTRIC COMPANY e CALL BOX 15

• MALVERN, PENNSYLVANIA 193554715 e (215) 251-7000 May 12, 1986 Mr. James Taylor Director of Office of Inspection and Enforcement United States Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

SLV Relays

Dear Sir:

In my letter of February 26,1986 (copy attached), I described a problem that VEPC0 (Virginia Power) experienced with SLV relay during testing prior to application in a nuclear installation. (To our knowledge, VE 20 had pre-viously applied a number of these relays in 1984 and 1985 and they have been operating without incident.) Since our February 1986 studies we have continued our investigations in conjunction with Virginia Power and have achieved added understanding of the problem and we have instituted design changes which, based on extensive tests by us and by VEPC0, have resolved the problem.

We have informed the only other recorded nuclear user, Nuclear Energy Business Operations, GE, and provided SLV relays to the updated design to Illinois Power, their customer.

Our added study and analysis revealed that for an extremely limited number of relays, there was a very small but finite possibility of a power supply

" hang-up" when energizing the relay. This " hang-up" could cause a failure of a driver transistor which would lead to a thermal failure after about one hour, or, in some cases, the " hang-up" could cause an immediate failure of the chopper transistors in the power supply. With this knowledge, changes were made in the power supply circuitry which were tested on units which exhibited a tendency for " hang-up" on energization. These revised units were subjected to thousands of energization cycles without any problem. Beyond this, a number of modified relays were tested for the full complement of design tests - temperature, voltage variation and surges.

In summary:

a) SLV relays with the modifications incorporated in our latest designs have been extensively tested with no power supply failures as experi-enced by VEPC0 in test with the earlier design. In addition, based on analysis, we conclude that the modifications do not alter the qualified life of the SLV relay.

$0 NON D!

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GENERAL $ ELECTRIC Mr. J. Taylor May 12, 1986 Page 2 b) SLV relays currently in service, but not yet modified, have an extremely low probability of power supply problems. This is evidenced by the fact that relays in service have been performing without incident and that damage and/or failure of these units would occur, if at all, during a reenergization of the relay.

c) Based on joint agreement with VEPCO, SLV relays now in service will be modified and retested by GE as they become available based on normal shutdown conditions.

d) All of the SLV relays which have been modified have been designated 12SLVllA1A - Rev. A as shown on the replacement nameplate and Rev. A designs will be supplied on new orders for this relay.

It is my understanding that this letter to VEPCO, NEB 0 (GE), and the NRC

, fulfills our obligation for added notification relative to the problem.

Yours truly, 7

k 6u.

L.L. Mankoff Engineering Manager

/rgm

o GENERAL $ ELECTRIC METER AND CONTROL BUSINESS DEPARTHENT GENERAL ELECTRIC COMPANY e CALL BOX 15 e MALVERN, PENNSYLVANIA 193554715 * (215) 251-7000 February 26, 1986 Mr. James Taylor Director of Office of Inspection & Enforcement United States Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

SLV Relays

Dear Sir:

Recently, VEPC0 experienced power supply failures during test of some recently manufactured SLV relays which were intended for application in a nuclear installation.

We have searched our records and find that in addition to the VEPC0 units, we shipped two SLV relays for nuclear application to our Nuclear Energy Business Operations (NEB 0) in San Jose, California. (The only other nuclear shipment.)

The attached memorandum provides details of the problem, our actions to date and our plans. We have informed NEB 0 by telephone and by copy of this letter and we will supply specific test instructions to help determine if the two units shipped are vulnerable to the SLV power supply problem.

It is my understanding that our discussions and correspondence with VEPC0, NEB 0 (GE) and the NRC fulfill our obligations for notification relative to the problem.

r i r L b L.L. Mankoff

/rgm cc: V. Thomas, USNRC, Washington DC p

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