ML20083D574
| ML20083D574 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/25/1991 |
| From: | Feigenbaum T PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20083D543 | List: |
| References | |
| NYN-91156, NUDOCS 9110010075 | |
| Download: ML20083D574 (2) | |
Text
_ _ _ -.
New Hampshire Yall e
Ted C. Feigenhovm Presdent and Chief Executive Offices NYN. 91156 September 25, 1991 United States Nuclear Regulatory Commission Washington, D.C.
20555 Attention:
Document Control Desk
References:
(a)
Facility Operating License No. NPF-86, Docket No. 50-443 (b)
Se.ibrook Station Techni ] Specification 4.8.1.1.3
Subject:
Diesel Generator Special Report Gentlemen:
The following Diesel Generator Special Report documents a diesel generator failure that occurred at Seabrook Station and is reported pursuant to Technical Specification 4.8.11.3.
On August 26, 1991, t he A frain Emergency Diesel Generator (EDG) tripped d
post maintenance testing. The EDG trip was actuated by the reverse power relay.
. 3rdance with Regulatory Position C.3.b of Regulatory Guide 1.108, Revision 1, August
< it was determined that this event is a non-valid EDG start failure. At the time of this dare the plant was in a refueling outage with no fuel in the reactor vessel. Additionally, the B Train EDG was operable.
The reverse power relay in the A Train ED6 was replaced with an identical (General Electric Type ICW) relay during the eighteen month engine overhaul. Prior to the outage, the new relay was removed from stock and pre-calibrated prior to installation. Ilowever, during the post maintenance test, this new relay activated the backup protection relay and teipped the generator output breaker.
Following the EDG trip, an inspection of the old and new reverse power relays was conducted it was determined that the potential coils internal to the old relay were reversed.
A subsequent inspection of the reverse pawer relay installed in the B Train EDG revealed the same condition. An Engineering Change Authorization (ECA), issued in 1984, ievised this circuit by reversing the current coil connections on the back of the relay case.
Root Cause A root cause analysis is currently being perfoimed, however the root cause for the incorrect wiring has not been conclusively determined. It is expected that the root cause analysis will be completed and a supplemental report submitted to the NRC by October 30, 1991.
9110010075 910924 PDR ADOCK 05000443 p
PDR New Hampshire Yankee Division of Public Service Company of New Hampshire P.O. Box 300 = Seabrook, NH 03874 = Telephone (603) 474 9521
n,-.
l United States Nuclear-Regulatory Commission Sept e mber; 25,1991 -
Attention:
. Document Centrol Desk Page two Corrective ~ Action A design-cha: ige was-issued and implemented to correct the wiring of the subject relays as well as the schematic drawings. Specifically, the internal relay potential coil wires and the external relay. case potential coil wires were swapped for the relay installed in the 11 Train EDG. For the new relay in the A Train EDO, only the_ external relay case' potential coil. wires wcre swapped. _This rewiring was performed to ensure that any properly wired relay can be u' sed for future replacements.
Should you require further information regarding this matter, please contact Mr. James M. Peschel, Regulatory Compliance Manager, at (603) 474-9521, extension 3772.
Very truly yours.
[M$be
- Ted C. Feigen aum TCF:WJT/ss cc:
Mr. Thomas T. Martin Regional Administrator United States Nuclear Regulatory Commission Region 1-475' Allendale Road King of Prussia, PA 19406
- Mr. Gordon E. Edison, Sr. Project Manager Project Directorate 13 Division of Reactor Projects U.S, Nuclear Regulatory Commission Washingto, DC 20555.
-_ Mr. Noel Dudley NRC Senior Resident Inspector P 0, Box 1149 Seabrook,- NH : 03874
.