ML20052D057
| ML20052D057 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/21/1982 |
| From: | Clark R Office of Nuclear Reactor Regulation |
| To: | Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 8205060234 | |
| Download: ML20052D057 (5) | |
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APR 211982 P00cket File EReeves fiRC PDR RBirkel L PDR BBuckley NSIC WRoss Docket No. 50-339 ORB #3 Rdg CStable DEisenhut SVarga p
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SUBJECT:
LICENSE CONDITION 2.C.(15)(a), NORTH ANNA P0 DER STATION, UNIT NO. 2 (NA-2)
We have completed our evaluation of your submittal dated March 1, 1982 (Serial No. 124) which addressed the requirements of the ftA-2 License Condition 2.C.(15)(a). License Condition 2.C.(15)(a) required that the results of the guide thinble surveillance progra,regarding the issue of guide thimble tube wear for Westinghouse 17 X 17 fuel assemblies be sutx11tted during the NA-2 first refueling outage.
We have determined that the submittal adequately confirms the accepta-bility of the NA-2 fuel design relative to the propensity for guide thichle tube wear. Therefore, you nave met in full the stipulations of License Condition 2.C.(15)(a).
In the event that other licensees of the Osmer's Group specified in your March 1, 1982 submittal have similar license conditions or unresolved issues, we have prepared a generic safety evaluation report applicable to the licensees facilities as well. This generic safety evaluation I
is provided in the Enclosure to this letter.
l Sincerely, l
Origire' di;a:d by (hde2> M Tron 101ES yy Robert A. Clark, Chief'
(
Optrating Reactors Branch #3 Division of Licensing
Enclosure:
As stated cc:
See next page 8205060234 820421
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Virginia Elcctric and Pcwer Company cc:
Richard M. Foster, Esquire Mr. James Torson Musick, Williamson, Schwartz, 501 Leroy leavenworth & Cope, P.C.
Socorro, New Mexico 87891 P. O. Box 4579 Boulder, Colorado 80306 Mrs. Margaret Dietrich Route 2, Box 568 Michael W. Maupin, Esquire Gordonsville, Virginia 220,42 Hunton, Williams, Gay and Gibson P. O. Box 1535 fir. James C.' Duns'tance Richmond, Virginia 23212 State Corporation Commission Commonwealth of Virginia Alderman Library Blandon Building
!!anuscripts Department Richmond, Virginia 23209 University of Virginia Charlottesville, Virginia 22901 Mrs. June Allen North Anna Environmental Coalition Mr. Edward Kube 8720 Lockmoor Circle Board of Supervisors Wichita, Kansas 67207 Louisa County Courthouse P. O. Box 27 U.S. Environmental Protection Agency Louisa, Virginia 23093 Region III Office ATTN:
Regional Radiation Representative Ellyn R. Weiss, Esquire Curtis Building Sheldon, Harman, Roisman and Weiss 6th and Walnut Streets 1725 I Street, N.W. Suite 506 Philadelphia, Pennsylvania 19106 Washington, D. C.
20006 Mr. Paul W. Purdom Mr. W. R. Cartwright, Station Manager Environmental Studies Institute P. O. Box 402 Drexel University Mineral, Virginia 23117 32nd and Chestnut Streets Philadelphia, Pennsylvania 19104 Mr. Anthony.Gambardella Office of the Attorney General 11 South 12th Street - Room 308,
Atomic Safety and Licensing Appeal Board Panel Richmond, Virginia 23219 U.S. Nuclear Regulatory Commission Washington, D. C.
20555 Resident Inspector / North Anna Regional Administrator c/o U.S.N.R.C.
Nuclear Regulatory Commission, Region II Route 2, Box 78A Office of Executive Director for Operations Mineral, Virginia 23117 101 Marietta Street, Suite 3100 Mr. J. H. Ferguson Executive Vice President - Power Virginia Electric and Power Company s
Post Office Box 26666 Richmond, Virginia 23261 4
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ENCLOSURE SAFETY EVALUATION i
GUIDE THIMBLE TUBE WEAR IN WESTINGHOUSE 6
17x17 FUEL ASSEMBLY DESIGNS INTRODUCTION
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A degradation of guide thimble tube walls has been ob[erved during post-f rradiation examinations (PIES) of irradiated fuel assemblies taken from several operating pressurized water reactors.
Ithasbeenideterminedthat coolant ficw up through the guide thimble tubes and turbulent cross flow above the fuel assemblies have beer, responsible for inducing vibratory motion in the nomally ful.ly withdrawn (" parked") control rods.
When these vibrating rods are in contact with the inner surface of the guide thimble tube wall, a fretting wear of the wall occurs.
Significant wear' has been found to be confined to the relatively soft Zircaloy-4 guide thimble tube because the control rod claddings--stainless steel for Westinghouse NSSS designs--provide a relatively hard wear surface.
l The staff has recently received (Ref.1) a generic report that provides PIE results on guide thimbio tube wear in the Westinghouse 17x17 fuel assembly design.
The report was prepared by Westinghouse for a cooperative Owner's
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Group that sponsored the PIE program.
Members participating in the program were Duke Power Company, Tenness.ee Valldy Authority, Public Service Electric and Gas Company, Pacific Gas and Electric Company, Virginia Electric and l
Power Company, and Westinghouse.
The surveillance data were obtained on fuel discharged from Unit 1 of Salem, a RESAR-3S plant similar to those owned by each participating utility.
Our evaluation of that report ensues.
SUMMARY
OF STAFF EVALUATION In accordance with a prior agreement (Ref. 2) between Westinghouse and NRC, the top 20 inches of all 24 rodded thimbles in each of six fuel assemblies were selected for examination.
Four of'these assemblies had experienced one cycle of operation and two had experienced two full cycles of operation.
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-carm.w-- son The assemblies were selected from various core locations in order to assess any specific wear dependency on core location (for example, by virtue of their different location within the core, the assemblies had been subjected to various coolant flow velocities in the control rod cluster guide column above the upper core plate).
The minimum purpose for the examinations was to determine the presence of any wear holes of a size greater than one-sixteenth of an inch in diameter; however, the experimental techniques actually employed allowed for a much greater resolution of the acquired wear.
Specifically, the boroscope and television monitor that were utilized permitted qualitative resolutic;'. of wear depths corresponding as little as surface scratches.
There were no wear holes or unusuil wear found in any of the 144 thimble tubes that were exam'ined.
Occasional longitudinal scratches were observed',
but the scratches had no appreciable depth. The most pronounced scratches were typically three to eight inches long and one-thirty second of an. inch I
wide.
' Accordingly, we conclude that the Westinghouse 17x17 fuel assembly design is resistant to guide thimble tube wear.
REGULATORY POSITION We conclude that the submittal adequately confirms the acceptability of the Westinghouse 17x17 fuel assembly relative to its propensity for guide thimble tube wear. The report may be referenced in license applications.
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References 1.
Letter from R. H. I.:easburg (VEPCO) to H. R. Denton (NRC), Docket 50-339, March 1,1982.
Enclosure:
Salem Unit 1,17x17 Fuel Assembly Guide Thimble Tube Wear Examination Report, January 1982.
~2. Memorandum from R. O. Meyer (NRC) to K. Kniel, " Westinghouse Proposal for 17x17 Guide Tube Surveillance," February 29, 1980.
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