ML20100E603
| ML20100E603 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 11/15/1984 |
| From: | Mangan C NIAGARA MOHAWK POWER CORP. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| (55(E)-84-27), (NMP2L-0241), (NMP2L-241), NUDOCS 8412060303 | |
| Download: ML20100E603 (2) | |
Text
,
e<
N3fatelle NIAGARA MOHAWK POWER CORPORATION /300 ERIE BOULEVARD WEST SYR.ACUSE, N.Y.13202/ TELEPHONE (315) 474-1511 November 15, 1984 (NMP2L 0241)
Mr. R. W. Starostecki, Director U. S. Nuclear Regulatory Comission Region I Division of Project and Resident Programs 631 Park Avenue King of Prussia, PA 19406 Re: Nine Mile Point - Unit 2 Docket No. 50-410
Dear Mr. Starostecki:
Enclosed is a final report in accordance with 10CFR50.55(e) for the problem concerning General Electric SAM relays.
This problem was reported via tel-con to S. Collins of your staff on July 23, 1984 An interim report was submitted via our letter dated August 23, 1984 Very truly yours, C. V. Manga Vice President Nuclear Engineering and Licensing CVM/GG/dd Enclosure xc: Director of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, DC 20555 R. A. Gramm, NRC Resident Inspector ProjectFile(2)
%2gpg[o e
'S 4
7
s
/
h e
NIAGARA MOHAWK POWER CORPORATION
-NINE MILE P0 INT-- UNIT 2 DOCKET NO. 50-410 Final Report for a Problem Concerning the Misoperation of GE SAM Relays (SS(e)-84-27)
Description of the Problem General Electric has advised Niagara Mohawk Power Corporation that it is-possible for certain SAM relays (Model Nos. SAM 11, 13, 15, and certain SAM 99 special relays) to operate in less than the set time delay if the initiating contact experiences a very specific mode of contact bounce.
In Nine Mile Point - Unit 2 design, these relays are used in various Category I switchgear lineup applications (for example, load sequencing of emergency buses).
These timing relays are used primarily to facilitate coordination of relays with other downstream protection.
In such applications, the time delay is critical.
Analysis of Safety Implications Under certain conditions, the misoperation of these relays could result in shorter time delays than required.
As a result of shorter time delays, protective relay selectivity and load sequencing of emergency buses could be adversely affected.
Therefore, if this problem were to have remained uncorrected, it could have adversely affected the safety of operation of the plant.
Corrective Action General. Electric has infomed Stone and Webster that the problem could be corrected by replacing the existing printed circuit cards with the current design cards for the subject relays.
This recommended change will be made and the relays will then be recalibrated for the required time delay.
The corrective action will be accomplished in accordance with the Engineering and Design Coordination Report (EADCR) No. F-01889 and will be complete by July 31, 1985
.