ML18040A263
| ML18040A263 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/13/1997 |
| From: | Abbott R NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17059B591 | List: |
| References | |
| NMP1L-1229, NUDOCS 9706200178 | |
| Download: ML18040A263 (7) | |
Text
CATEGORY j REGULATOfOINFORMATION DISTRIBUTION TEM (RIDE)
ACCESSION NBR:9706200178 DOC.DATE: 97/06/13 NOTARIZED:
NO DOCKET FACIL:50-220 Nine Mil.e Point Nuclear Station, Unit 1, Niagara Powe 05000220 AUTH.iVAME AUTHOR AFFILIATION ABBOTT,R.B.
Niagara Mohawk Power Corp.
RECIP,Ni'AME RECIPIENT AFFILIATION Document.Control Branch (Document Control Desk)
SUBJECT:
Forwards final rept of "Metallurgical Evaluation of Failed Shroud Tie Rod Lower Spring Contact Wedge Latches."
Exams were to confirm that latch failure was caused by high stress that esulted in intergranular stress corrosion cracking.
DISTRIBUTION CODE:
A001D COPIES RECEIVED:LTR l
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TITLE: OR Submittal:
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NOTES:
RECIPIENT ID CODE/NAME PDl-1 LA HOOD,D INTERNAL: ACRS NRR/DE/ECGB/A NRR/DRCH/HICB NRR/DSSA/SRXB OGC/HDS3 EXTERNAL: NOAC COPIES LTTR ENCL 1
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'1 NOTE TO ALL "RIDStD RECIPIENTS:
PLEASE HELP US TO REDUCE WASTEI CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN SD"5(EXT. 415-2083)
TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 14 ENCL 13.
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NIACARAMOHAWK G EN ERATION BUSINESS GROUP RICHARD B. ABBOTT Vice President and General Manager - Nuclear NINE MILEPOINT NUCLEAR STATION/LAKEROAD, P.O. BOX 63, LYCOMING,NEW YORK 13093/TELEPHONE (315) 349-1812 FAX(315) 3494417 June 13, 1997 NMP1L 1229 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE:
Nine MilePoint Unit 1 Docket No. 50-220
Subject:
Metallurgical Evaluation ofFailed Core Shroud Tie Rod Lover Spnng Contact Wedge Latches Gentlemen:
By letter dated May 20, 1997, Niagara Mohawk Power Corporation (NMPC) indicated that the final report of the metallurgical examinations related to the failed latch would be submitted to the staff by June 15, 1997.
The purpose of the metallurgical examinations was to confirm that the latch failure was caused by high stress that resulted in intergranular stress corrosion cracking gGSCC) as was presented in Enclosure 2 of our letter dated April8, 1997.
General Electric (GE) has completed final metallurgical evaluations at GE's Vallecitos Nuclear Center Laboratories to validate the root cause of the latch failures.
The enclosed report entitled, "Metallurgical Evaluation ofFailed Shroud Tie Rod Lower Spring Contact Wedge Latches,"
provides the final results.
The final results of the metallurgical evaluations validate that the cause of the latch failure was high sustained loads applied to the underside of the latch nose (due to unacceptable movement of the shroud repair assemblies during plant operation) resulting in an IGSCC fracture of the latch.
Sincerely, 9706200i78 9706iS PDR ADOCK 05000220 P
'PDR RBA/TRE/lmc Enclosure Richard B. Abbott Vice President and General Manager - Nuclear
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Mr. H. J. Miller, NRC Regional Administrator Mr. A. W. Dromerick, Acting Director, Project Directorate I-l, NRR Mr. B. S. Norris, Senior Resident Inspector Mr. D. S. Hood, Senior Project Manager, NRR Records Management
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GE Nuclear Energy GENE B13-01739-44 Revision 0 Class II June 1997 Metallurgical Evaluation ofFailed Shroud Tie Rod Lower Spring Contact Wedge Latches Nine MilePoint Unit 1, RF014 Prepared for:
Niagara Mohawk Power Corporation Prepared by:
GE Nuclear Energy Plant Materials Technology 175 Curtner Avenue, M/C785 San Jose, California 95125
. 9706200178