ML20153G361
| ML20153G361 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/18/1998 |
| From: | Kim T NRC (Affiliation Not Assigned) |
| To: | Richard Anderson NORTHERN STATES POWER CO. |
| References | |
| TAC-MA98760, NUDOCS 9809300050 | |
| Download: ML20153G361 (3) | |
Text
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September 18, 1998 l
Mr. Roger O. Anderson, Director Nuclear Energy Engineering Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401
SUBJECT:
REVIEW OF STEAM GENERATOR WELD INDICATION EVALUATION FOR PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 2 (TAC NO. M98760)
Dear Mr. Anderson:
In a letter dated May 6,1997, Northern States Power Company (NSP) submitted, for NRC review, its evaluation of flaw indications in steam generator welds from ultrasonic testing (UT) conducted during the refueling outage in winter 1997, at the Prairie Island 2 Nuclear Power Plant. The document indicates that there are 17 indications and 5 of them exceed the allowable I
flaw sizes specified in IWB-3500 of Section XI of American Society of Mechanical Engineers (ASME) Code and require flaw evaluation using IWB-3610 of the ASME Code. Allindications are in the tubesheet to channel head weld region for #22 steam gerierator. These examinations were done to satisfy the first period requirements of the third 10-year intervalin compliance with the 1989 edition of Section XI of the ASME Code.
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The NRC staff completed the review and found the submittals acceptable. The staff evaluation is summarized in this letter.
Having characterized the flaws through flaw sizing and determined that five indications exceeded the allowable flaw sizes specified in IWB-3500 of Section XI of the ASME Code, NSP used a handbook by Westinghouse, WCAP-14166, " Handbook on Flaw Evaluation for Prairie Island Units 1 and 2 Steam Generators and Pressurizer," to determine the acceptability of these five flaws. The handbook was enclosed as a supplement to a submittal dated December 30, 1994, regarding similar flaw evaluations on steam generator weld indications. This handbook D
l provides methodology and evaluation curves for various welds in Prairie Island Units 1 and 2 steam generators based on the criteria of IWB-3611 and IWB-3612. Fatigue crack growth has also been considered. The portion of the handbook related to the indications in the tubesheet L
to channel head weld region in Prairie Island steam generators was reviewed in 1995 by the y
staff. The staff concluded in a safety evaluation dated September 6,1995 (transmitted by letter o\\
from J. N. Hannon (NRC) to R. O. Anderson (NSP) dated September 6,1995) for that submittal g\\
9 that the methodology and criteria used in generating flaw evaluation curves for the steam
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generators of both units of Prairie Island are in accordance with Section XI of the ASME Code.
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R. O. Anderson
-2 September 18, 1998 in the present review, the staff has assessed NSP's flaw sizing calculations and flaw evaluation using WCAP-14166 and determined that NSP sized the flaws adequately and applied the handbook curves in its flaw evaluation adequately. The results indicate that the detected flaw sizes are smaller than the critical flaw size. Hence, the reported flaws are acceptable without repair. However, according to IWB-2420, the areas containing flaws shall be reexamined during the next three inspection periods listed in the schedule of the inspection program of IWB-2400.
This completes cur work for TAC No. M98760.
Sincerely, ORIGINAL SIGNED BY Tae Kim, Senior Project Manager Project Directorate 111-1 l
Division of Reactor Projects -Ill/lV Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306 cc: See next page j
DISTRIBUTION:
Docket File PUBLIC PD# 3-1 Reading EAdensam (EGA1)
SSheng OGC ACRS MKunowski DOCUMENT NAME:G:\\WPDOCS\\ PRAIRIE \\Pl98760.LTR *SEE PREVIOUS CONCURRENCE l
To receive a copy of this document, indicate in the box C= Copy w/o attachment / enclosure E= Copy with j
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DATE OFFICIAL RECORD COPY
1 Mr. Roger O. Anderson, Director Prairie Island Nuclear Generating Northern States Power Company Plant cc:
l J. E. Silberg, Esquire Site Licensing Shaw, Pittman, Potts and Trowbridge Prairie Island Nuclear Generating 2300 N Street, N. W.
Plant Washington DC 20037 Northern States Power Company
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1717 Wakonade Drive East Plant Manager Welch, Minnesota 55089 Prairie Island Nuclear Generating Plant Tribal Council Northern States Power Company.
Prairie Island Indian Community 1717 Wakonade Drive East ATTN: Environmental Department Welch, Minnesota 55089 5636 Sturgeon Lake Road Welch, Minnesota 55089 Adonis A. Nebiett Assistant Attorney General Office of the Attorney General 455 Minnesota Street Suite 900 St. Paul, Minnesota 55101-2127 U.S. Nuclear Regulatory Commission Resident inspector's Office 1719 Wakonade Drive East Welch, Minnesota 55089-9642 Regional Administrator, Region ill U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois 60532-4351 Mr. Stephen Bloom, Administrator Goodhue County Courthouse Box 408 Red Wing, Minnesota 55066-0408 Kris Sanda, Commissioner Department of Public Service 121 Seventh Place East Suite 200 St. Paul, Minnesota 55101-2145 June 1998
,