ML20127J777
| ML20127J777 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/10/1985 |
| From: | Mangan C NIAGARA MOHAWK POWER CORP. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| (55(E)-85-14), (NMP2L-0425), (NMP2L-425), NUDOCS 8506270090 | |
| Download: ML20127J777 (2) | |
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- A Y NIAGARA NUMOHAWK NINE MILE PolNT-UNIT 2 P.O BOX 63. LYCOMING NY 13093 TELEPHONE (315) 343-2110 June 10,1985 (NMP2L 0425)
Mr. R. W. Starostecki, Director U.S. Nuclear Regulatory Commission Region I Division of Reactor Projects 631 Park Avenue King of Prussia, PA 19406
Dear Mr. Starostecki:
Subj ect: Nine Mile Point - Unit 2 Docket No. 50-410 Enclosed is a final report, in accordance with 10CFR50.55(e), for the problem concerning Westinghouse TD-5 timers.
This problem was reported via tel-con to R. Barkley of your staff on April 11, 1985 Very truly yours, h hdAV C. V. Manga Vice President Nuclear Engineering and Licensing CVM/GG/cla (0567F) xc:
Director of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 R. A. Gram, NRC Senior Resident Inspector Project File (2) 506270090 850610 ADOCK 05000410 S
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W NIAGARA M0 HAWK POWER CORPORATION NINE MILE POINT - UNIT 2 DOCKET NO. 50-410 Final Report for Problems Concerning the Westinghouse TD-5 Timers (55(e)-85-14)
Description of the Problem A condition was identified in 4160-V switchgear 2 ENS *SWG101, 2 ENS *SWG102, and 2 ENS *SWG103 during preliminary testing of the standby emergency diesel generator load shedding scheme wherein the contacts 'of the Westinghouse Type TD-5 relays had burned due to excessive current discharge when TD-5 target coil contacts are used to open the circuit.
The excessive current was due to the reduced effective resistance of the series-parallel relay circuit in the load-shedding scheme.
This circuit design had caused over 1 ampere to flow through to 0.2-ampere rated contact of the TD-5 relay.
The TD-5 relays used do not have a 2-ampere tap setting.
Analysis of Safety Implications The defective circuit design of the load-shedding scheme could result in malfunction of the TD-5 relays, rendering the relays inoperabl e, thus affecting the design function of the diesel generator load shedding system.
Therefore, had this condition remained uncorrected, it could have adversely affected the safety of operations of the plant.
Corrective Actions 1.
4160-V Switchgear 2 ENS *SWG101 and 2 ENS *SWG103 The circuit has been revised so that the current through target coil and contacts will be reduced to no more than 0.2-ampere and arc suppression across the,ontacts will be provided.
This change was documented on Engineering Change Notice No. ENS-509 This corrective action will be performed in accordance with Engineering and Design Coordination Report No. C45455.
2.
4160-V Switchgear 2 ENS *SWG102 The circuit will be inodified to be compatible with the TD-5 relays.
General Electric will issue Field Deviation & Disposition Report No.
KGl-4079-0 to detail the modification.
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