ML20079K901
| ML20079K901 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 10/31/1991 |
| From: | Feigenbaum T PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NYN-91178, NUDOCS 9111050226 | |
| Download: ML20079K901 (2) | |
Text
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kh Ted C. Feigenboom Pre 6Jent onri Chief Esecodve Ollicer NYN-91178 i
October 31, 1991 thited States Nuclear Regulatory Commission j
Washington, D.C.
20555 Attention:
Document Control Desk R e fe r e n ce s-(a)
Facility Operating 1.icense No. NPF-86, Docket No. 50 443 (b)
Seabrook Station Technical Specification 4.8.1.1.3 (c)
NilY I.etter NYN 91156 dated Septembe r 25,1991, " Diesel Generator Special Report", T. C. Feigenbaum to USNitC
Subject:
Diesel Generator Special Report Supplement Gentlemen:
The following information is provided to supplement a Diesel Generator Special Report submitted by New llampshire Yankee (NilY) on September 25,1991 [ Reference (c)l.
The Diesel Generator Special Report documented a diesel generator failure that occurred at Seabrook Station and which was reported pursuant to Technical Specification 4.8.1.1.3.
On August 26, 1491, t he "A" Tr ain Emergency Diesel Generator (EDG) tripped during post maintenance testing. The EDG trip was caur.cd by the actuation of a reverse power relay and lockout relay. In accordance with Regulatory Position C.3.h of Regulatory Guide 1.106, Revision 1, August 1977, it was determined that this event wa a non-valid EDG start f ailure. At the time of this failure the plant was in a refueling outa with no fuel in the e
l reactor vessel. Additionally, the "I1" Train EDG was operable.
1 Prior to the August 26, 1991 diesel generator failure, the reverse power relay in the "A" Train EDG was replaced with an identical (General Electric Type ICW) new relay during the eighteen morth engine overhaul.
The - new relay was removed from stock and pre-caiibrated prior to ia r llation. llowever, during the post maintenance test, this new a
relay actuated and trip;. the lockout relay which tripped the generator output breaker.
l Following the EDG trip, an inspection of the old and new reverse power relays was l
conducted. It was determined that the potential wiring leads internal to the old relay were r e ve r se d.
A r,ubsequent inspection of the reverse power relay installed in the "it" Train EDG revealed the same condition. An Engineering Change Authorization (ECA), issued in 1984, revised this circuit by reversing the current input leads external to the reverse power relay.
It is believed this ECA was issued as a result of an unsuccessful preoperational test of EDG circuitry that was conducted in 1984 911.105022% 911031 PDR ADOCK 05000443 n
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New Hampshire Yankee Division of Public Service Company of New Hampshire f C P.O. Box 300
- Seabrook, NH 03874
- Telephone (603) 474 9521
UnitcQ States Nuclear Regulatory Commission October 31, 1991 Attention:
Document Control Desk Page two Root Cause The documentation and records related to the EDG reverse power relay and the ECA were reviewed but the exact reasons for the reversal of leads internal to the relay could not be determined. In addition it has been determined that there was an inadequate technical review associated with the implementation of the ECA, A thorough evaluation to determine the cause of the relay's failure to function as designed should have been performed rather than authorizing the reversal of the current input leads external to the reverse power relay to compensate for wiring problems internal to the relay.
Corrective Action A design-change was issued and implemented to correct the wiring of the reverse power relays as well as the affected schematic drawings. Specifically, the reverse power relay potential lead wires and the current input lead wires were modified to meet oiiginal design requirements on the "ll" Train EDG, For the new relay in the A Train EDG, only the current input leads to the reverse power relay were corrected. This rewiring was performed to ensure that any properly wired relay can be used for future replac;mc.;S The current NilY Design Control Program will preciude a similar configuration management error from occurring.
The Design Control Program requires a rigorous multi disciplined technical review cf proposed d: sign changes similar to the ECA.
Should you require further information regarding this matter, pleast contact Mr. James M. Peschel, Regulatory Compliance Manager, at (603) 474-9521, extension 3772.
Very truly yours, f
Ted C. Feig6nbauin i
1 l
cc:
Mr. Thomas T. Martin Regional Administrator U.S. Nuclear Regulatory Commission l
j Region !
475 Allendale Road King of Prussia, PA 19406 1
l Mr. Gordon E, Edison, Sr. Project Manager Project Directorate 13 Division of Reactor Projects U.S. Nuclear Regulatory Commission Washington, DC 20555 Mr. Noel Dudley NRC Senior Resident inspector P.O. Box 1149 Seabrook, N!I 03874