ML20137B413
| ML20137B413 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 01/03/1986 |
| From: | Mangan C NIAGARA MOHAWK POWER CORP. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| (55(E)85-28), (NMP2L-0575), (NMP2L-575), NUDOCS 8601150321 | |
| Download: ML20137B413 (2) | |
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N3M NIASARA B00 HAWK POWER CORPORATl0N/300 ERIE BOULEVARD WEST. SYRACUSE. N.Y.13202/ TELEPHONE (315) 4741511 January 3, 1986 (NMP2L 0575)
Mr. R. W. Starostecki, Director U.S. Nuclear Regulatory Comission Region I Division of Reactor Projects 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 Gould Service Water Pumps - Motor Holdr'own Bolts.
This problem was reported via tel-con to J. Stair of your staff on September 30,1985, and an interim report was submitted on October 30, 1985 Very truly yours, C. V. Mangan Senior Vice President CVM/GG/cla (1359H) xc: Director of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 R. A. Gram, NRC Senior Resident Inspector hk PD to S
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NIAGARA M0 HAM POWER CORPORATION NINE MILE POINT - UNIT 2 DOCKET NO. 50-410 Final Report for a Problem Concerning Gould Service Water Pumps -
Mutor Holddown Bolts (55(e)85-28)
Description of the Problem A check of the service water pumps (2SWP*PI A-F) motor holddown bolts identified a potential overstress condition due to insufficient thread engagement with the pump assembly baseplate.
The length of thread engagement -
was found to be less than expected.
A calculation for one of the pumps was performed and showed that when considering the actual thread engagement, the design loadings, and the pretorquing of the bolts, the bolt threads would fail in shear.
Analysis of Safety Implications Because all the motor holddown bolts for pumps 2SWP*PI A-F will be replaced, complete measurement and evaluation of bolt thread engagement - has not been performed.
For this evaluation, a conservative assumption is made that all the bolts have insufficient thread engagement.
Under this condition, the motors would not be held down properly with the possible consequences of pump /
motor misalignment and risk to the operability of - the pumps.
The pumps provide cooling water to safety-related components, and their. loss, if the-condition had remained uncorrected, could have adversely affected the safety of operations of the plant.
Corrwetive Action The 2-in long motor holddown bolts are being replaced with '2 1/2-in. long bolts which will provide sufficient thread engagement. ~ This corrective action is being performed in accordance with Engineering a Design Coordination Report No. 260671.
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