ML20050A286
| ML20050A286 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/16/1982 |
| From: | Rhode G NIAGARA MOHAWK POWER CORP. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8204010010 | |
| Download: ML20050A286 (2) | |
Text
.s Y NIAGARA NUMOHAWK NIAGARA MOHAWK POWER CORPORATION /300 ERIE BOULEVARD WEST. SYRACUSE, N.Y.13202/ TELEPHONE (315) 474-1511 March 16, 1982
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e Office of Inspection and Enforcement g
Region I b
fiEcggg9 Attention:
Mr. R.W. Starostecki, Director Division of Resident and Project Inspection C
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Nine Mile Point Unit 2
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Docket NO. 50-410
Dear Mr. Starostecki:
Enclosed is a final report in accordance with 10CFR50.55(e) for the deficiency regarding Series 20K switches manufactured by Electroswitch Corporation. This condition was reported by telephone to Mr. H. Kister of your staff on February 16, 1982.
Very truly yours, NIAGARA M0 HAWK POWER CORPORATION h
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'rf Vice President System Project Management PEF:bd cc: 1.
Director, Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 2.
Mr. R.D. Schulz, Resident Inspector F204010010 820316 DR ADOCK 05000 h
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NIAGARA M0 HAWK POWER CORPORATION NINE MILE POINT UNIT 2 DOCKET N0. 50-410 FINAL REPORT FOR REPORTABLE DEFICIENCY REGARDING ELECTR0 SWITCH - SERIES 20K SWITCHES Description of the Deficiency The Series 20K switches incorporate slip contacts along with standard normall) open/ closed contacts. The area of concern is the slip contact configuration.
The slip contacts are closed in one position and remain closed when the operator handle is returned to center normal. During manual operation of the switch handle, there is a possibility of slip contacts failing to perform as designea. This improper operation results in slip contacts remaining closed when they are expected to have opened or vice versa.
The deficient switches have been determined to be in the following safety related systems:
Standby Gas Treatment Drywell Cooling Reactor Building Ventilation Control Building Chilled Water Control Building ventilation Yard Structure Ventilation Diesel Generator Building Ventilation Analysis of Safety Implications The improper operation of the switch, depending on slip contact usage within the circuits, could affect operation of safety related systems which contain these switches. Therefore, if tne problem were to have remained uncorrected, it could nave adversely affected the operation of-these systems.
Corrective Action Electroswitch. Corporation, the vendor for the Series 20K switches, has modified the design of these switches. The redesign eliminates the possibility of slip contacts failing to perform as designed.
Electroswitch Corporation will no longer furnish more than four slip contacts
- per switch unit.
In the new design, the7 contacts are made in only one select position, at the front of the switch (closest to the handle). The vendor has added a mechanical shaft slip coupling, then a positive detent mechanism, and finally the slip contacts. With t_h in position by the detent mechanism,is arrangement, the slip contacts are held The subject switches already mounted on the control panels, will be modified
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to the acceptable switch configuration. Measures are also being taken to ensure that Series 20K switcnes supplied by Electroswitch Corporation in the future will have the acceptable switen configuration.
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