ML20052A509

Forwards LER 82-005/01T-0.Detailed Event Analysis Encl

ML20052A509
Person / Time
Site:	Oconee
Issue date:	03/26/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20052A510	List: ML20052A509 ML20052A514
References
NUDOCS 8204280407
Download: ML20052A509 (2)

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Vice Pat 5tDENT i^^ IO sm- Paoouct'oN March 26, 1982 w 37 3-** o

. 1; Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission b

D Region II w 101 Marietta Street, Suite 3100 cc Atlanta, Georgia 30303 Re: Oconee Nuclear Station .

Docket No. 50-270

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-270/82-05. This report is submitted pursuant to Oconee Nuclear Station Technical Specification 6.6.2.1.a(9), which concerns the discovery of conditions not specifically considered in the safety analysis report or Technical Specifications that require corrective measures to prevent the existence or development of an unsafe condition, and describes an incident which is considered te be of no significance with respect to its effect on the health and safety of the public.

Ve trulyyours,7

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oo_ 'O. LL William O. Parker, Jr.

JFN/php Attachment cc: Document Control Desk Records Center U. S. Nuclear Regulatory Commission Institute of Nuclear Power Operations Washington, D. C. 20555 1820 Water Place Atlanta, Georgia 30339 Mr. W. T. Orders NRC Resident Inspector Oconee Nuclear Station otTiCTATfCON 8204280V37 #C T C,d

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e DUKE POWER COMPANY OCONEE NUCLEAR STATION UNIT 2 Report Number: R0-270/82-05 Report Date: March 26, 1982 Occurrence Date: March 12, 1982 Facility: Oconee Unit 2, Seneca, South Carolina Identification of Occurrence: Experimental Zircaloy Spacer Grids moved Conditions Prior to Occurrence: Refueling Shutdown Description of Occurrence: As a result of post-irradiation examinations it was discovered that the intermediate spacer grids 1 through 5 on NJ01QF, a demonstration Mark BZ fuel assembly with zircaloy spacer grids, had moved approximately two inches upward during Unit 2 Cycle 5 operation. This caused loss of grid to grid contact with adjacent Mark B4 fuel assemblies.

Apparent Cause of Occurrence: The lQF grid springs holding the grids in .L place were not strong enough to prevent the grids from sliding upwards due to friction from the reactor coolant flow during Unit 2 Cycle 5, as described

-in letter of W. O. Parker, Jr. to James P. O'Reilly dated March 24, 1982.

Analysis of Occurrence: Due to the thicker zircaloy spacer grid configura-tion, there is a larger pressure drop across the zircaloy grid than-the standard Inconel grid. The IQF grid springs allowed the spacer grids to move upwards until they were stopped.by the spacer sleeves on the instrument tube of the fuel assembly. The IQF spacer sleeves are shorter than sleeves on four Mark BZ assemblies in Unit 1 Cycle 7, and allowed the grids to move

enough (more than 1.895 inches) to lose grid to grid contact with adjacent Mark B4 fuel assembly grids. No damage to fuel occurred. It is considered that the health and safety of the public were not affected by this event.

Corrective Action: Fuel-assembly lQF was removed (along with 15V) and replaced with 15W and 15A. Fuel assemblies 1KD, 15W, and 15A were positioned in core locations H-7 through H-9 so as to minimize the impact on Cycle 6 reload design. 15W (the only fuel assembly adjacent to lQF remaining) will be examined prior to Cycle 6 operation.

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