ML18040A316
| ML18040A316 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 08/14/1997 |
| From: | Conway J NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17059B678 | List: |
| References | |
| GL-88-01, GL-88-1, NMP1L-1243, NUDOCS 9708220237 | |
| Download: ML18040A316 (7) | |
Text
CATEGORY j.
REGUEATOI INFORMATION DiSTRIBUTION TEM (RIDS)
ACCESSION NBR:9708220237 DOC.DATE: 97/08/14 NOTARIZED:
NO DOCKET
'ACI~.:50-220 Nine Mile Point Nuclear Station, Unit l, Niagara Powe 05000220 AUTH. NAME AUTHOR AFFILIATION CONWAY,J.T.
Niagara Mohawk Power Corp.
RECIP.NAME RECIPIENT AFFILIATION N~fz5 Document Control Branch (Document Control Desk)
SUBJECT:
Forwards results of evaluation which indicates that weld overlay repair of RWCU weld 33-FW-22 meets requirements of ASME Code Case N-504,Sections (g)(2)
& (g)(3).
DISTRIBUTION CODE:
AOISD COPIES RECEIVED:LTR J ENCL J SIZE: 8 +~
TITLE: GL 94-03 Intergranular Stress Corrosion Cracking of Core Shrouds in B
NOTES:
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N NOTE TO ALL "RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD)
ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED:
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c NIAGARAMOHAWK C EN ERATION BUSINESS CROUP JOHN T. CONWAY Vice President Nuclear Engineering NINE MILEPOINT NUCLEARSTATION/lAKEROAD, P.o. BOX63, LYCOMING,NEW YORK 13093/TELEPHONE (315) 34W213 FAX (31 5) 349-2605 August 14, 1997 NMP1L 1243 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Nine MilePoint Unit 1 Docket No. 50-220
Subject:
Generic Letter (GL) 88-01, "tlRCPosition on IGSCC in BWR Austenitic Stainless Steel Piping" Gentlemen:
By letter dated May 15, 1997, Niagara Mohawk Power Corporation (NMPC) indicated that a through-wall pin hole leak at a bimetallic weld (33-FW-22) in the Nine MilePoint Unit 1 (NMP1)
Reactor Water Cleanup System (RWCU) had been discovered.
This leak resulted from a 7/16" axial crack that was classified as Intergranular Stress Corrosion Cracking gGSCC).
NMPC proposed to repair this weld by performing a weld overlay to restore the structural strength of the weldment and requested NRC approval of the weld overlay repair.
Based on information provided in our May 15, 1997 letter and by telephone conversation on May 16, 1997, the NRC approved restart of NMP1 following repair of the weld. Additionally, the NRC requested that additional information be provided via written communication.
By letter dated May 19, 1997, NMPC provided the additional information. This included a commitment to perform an evaluation of flaw growth due to fatigue, as well as shrinkage effects on welds and components in the system affected by the weld reinforcement, and to submit the results to the NRC.
The enclosure to this letter provides the results of our evaluation.
This evaluation indicates that the weld overlay repair of RWCU weld 33-FW-22 meets the requirements of ASME Code Case N-504 Sections (g)(2) and (g)(3) as follows:
A postulated initial flaw through the first weld pass of the overlay (360'round the overlay) is calculated to grow into the remaining weld overlay thickness less than the allowable depth specified by r
ASME Section XI, Table IWB-3641-5.
I 9708220237 9708i4
Page 2 The maximum stress in the RWCU system due to shrinkage at the weld overlay of 2162 psi is well within the ASME Section IIIallowable stress of 45,000 psi in SA106 Grade B piping due to a one-time anchor motion.
Sincerely, ohn T. Conway Vice President - Nuclear Engmeering JTC/JMT/cmk Enclosure xc:
Mr. H. J. Miller, NRC Regional Administrator Mr. B. S. Norris, Senior Resident Inspector Mr. A. W. Dromerick, Acting Director, Project Directorate I-l, NRR Mr. D. S. Hood, Senior Project Manager, NRR Records Management
.970822
1