ML20151P169
| ML20151P169 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/17/1998 |
| From: | Abbott R NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20151P172 | List: |
| References | |
| GL-88-01, GL-88-1, NMP2L-1792, NUDOCS 9806230279 | |
| Download: ML20151P169 (2) | |
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o JUN-17-98 k'ED 08:33 AM l.lCENSING FAX NO. 3153491400 P. 02 7
l Richard B. Abbott
?$l5lr*I?g5eorino June 17,1998 ome.: (31sj us.ista Fac (315)3494417 NMP2L 1792 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE:
Nine Mile Point Unit 2 Docket No. 50-410 NPF-60
Subject:
NRC Generic Letter 88-01, "NRC Position on 1GSCC in BWR Austenitic Stainless SteelPiping" Gentlemen:
' Nine Mile Point Unit 2 (NMP2) Technical Specification 4.0.5.f requires the performance of inservice inspections of piping identified in Generic Letter (GL) 88-01, *NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping". The Commission issued a Safety Evaluation dated August 17,1990 for the NMP2 position ca GL 88-01, In their Safety Evaluation, the Commission indicated that for any flaws identified that do not meet the criteria delineated in Section XI of ASME Code for continued plant operation, Commission approval of flaw evaluations and/or repairs in accordance with IWB-3640 and IWA-4130 is required before resumption of plant operation. Specifically, ASME Code,Section XI, IWB-3640 states that piping containing a flaw exceeding the allowable flaw standards ofIWB-3514.3 may be evaluated to determine its acceptability for continued service in accordance with the evaluation procedures and acceptance criteria ofIWB-3641 of IWB-3642. As indicated above, these evaluation procedures and acceptance criteria require Commission approval prior to resuming operation. The Commission issued Supplement 1 to GL 88-01 February 4,1992. The supplement provided sample expansion criteria for category "D" welds.
During the performance of required GL 88-01 ultrasonic (UT) examinations, for category "D" welds, during NMP2's current refueling outage (RFO-6) one (1) indication was found on feedwater inlet nozzle N4D safe end-to-nozzle weld that exceeded the Section XI allowable flaw size. A review of relevant UT records, inspection information and fabrication records all indicate that the indication is fabrication related and is not due to Intergranular Stress Corrosion Cracking (IGSCC).
Nine We Point Nacicar Station. P.O. Box 63, Lycoming. New York 13093 www.nimo.com 9806230279 990617 PDR ADOCK 05000410 P
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JUN-17-98 WED 08:34 AM 1.lCENSING FAX NO. 3153491400 P, 03
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l Page 2 In accordance with Section XI, Ningua Mohawk has evaluated the indication found in the feedwater inlet nozzle, safe end-to-nozzle weld and determined it is acceptable for plant start up and continued plant operation. This determination is based on the fracture mechanics evaluation included as Attachment A to this letter. To be conservative, the fracture mechanics analysis has evaluated the indication as if crack growth proceeds from active IGSCC. In addition, the weld will be recategorized as "P" for GL 88-01 requirements. Also, a comparison of the results of safe end-to-nozzle welds UT examination performed in 1995 to 1
the results of examinations performed during RFO-6 (i.e.,1998) indicated no appreciable change. Additional details concerning the 1995 versus 1998 examination results are provided in the attached evaluation. Three (3) of the six (6) feedwater inlet nozzle welds are examined every refueling outage to meet GL 88-01 inspection requirements. Consistent with GL 88-01 Category "F" inspection requirements, the flawed weld will be prioritized to assure it is examined during the next refueling outage. Any additional action will be based on these examination results.
GL 88-01 Supplement I requires an expanded examination sample when examinations reveal indications that exceed ASME Code allowable. Therefore, to satisfy the GL 88-01, Supplement 1, expanded sample requirements, the three remaining feedwater safe end-to-nozzle welds were examined and found to be acceptable. This resulted in all six (6) feedwater inlet nozzle safe end-to-nozzle welds being examined during the current refueling outage.
'7 Nine Mile Point Unit 2 is currently scheduled to restart on June 2,9,1998. Niagara Mohawk requests approval of the attached evaluation prior to June 29,1998 to support this schedule.
7 Very truly yours,
/2B 4 f/ A '
R.B. Abbott Vice President - Nuclear Engineering RBA/JM/sc Attachment xc:
Mr. H. J. Miller, NRC Regional Administrator Mr. S. S. Bajwa, Acting Di. set?r, Project Directorate I-1, NRR Mr. B. S. Norris, Senior Reid..nt Inspector Mr. D. S. Hood, Senior Project Manager, NRR Records Management
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