ML20010G258

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Forwards LER 81-021/03L-0.Detailed Event Rept Submitted
ML20010G258
Person / Time
Site: Cooper Entergy icon.png
Issue date: 08/25/1981
From: Lessor L
NEBRASKA PUBLIC POWER DISTRICT
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20010G259 List:
References
CNSS817128, NUDOCS 8109150496
Download: ML20010G258 (2)


Text

F 1EL COOPER NUCLE AR ST A TION Nebraska Public Power District "~ ' " "A%?ZX'#;"M"^T^ ""'

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CNSS817128 August 25, 1981 _

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.sYy ','.n Mr. K. V. Seyfrit, Director M: '- 4.

U.S. Nuclear Regulatory Commission C-! ,\\ g\y / ;---

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Ice Inspection and Enforcement 'g ,,' 5[#

611 Ryan Plaza Drive 9 N Suite 1000 4 Arlington, Texas 76011 aYh

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on July 28, 1981. A licensee event report form is also enclosed.

Report No.: 50-298-81-21 Report Date: August 25, 1981 Occurrence Date: July 28, 1981 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition occurred which resulted in operation in a degraded mode permitted by a limiting condition for operation established in Section 3.5.F.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was at 96% of rated thermal power.

Description of Occurrence:

During performance of Surveillance Procedure 6.3.12.1 to prove operability of #2 Diesel Generator (DG) because #1 DG was inop-erable (reference LER's 81-19 and 81-20), an injector line failed.

I99 5 The DG was shut down and declared inoperable.

II Designation of Apparent Cause of Occurreace:

The failure of the injector line is evaluated to be the result of the combined eficcts of metal fatigue and vibration. The failure is considered an isolated event.

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Mr. K. V. Seyfrit August 25, 1981 Page 2.

Analysis of Occurrence:

The station's emergency power system consists of two emergency diesel generators, each capable of supplying power for post ac-cident safety system operation and safe reactor cool down.

The injector line connects the individual cylinder injector pumps to their respective injectors. The line is heavy-wall h" tubing (wall thickness = 3/16"). The line failed near the injector com-pression fitting due to what is evaluated to be the combined effects of metal fatigue and vibration. Failure of this line vould not have made the DG inoperable under accident conditions. The engine would have carried full load on the other cylinders; however, it was shut down during the test due to equipment safety consider-ations. At the time this DG sas shutdown, the other DG's fuel supply hose had been repaired (reference LER 81-19). The other DG had not yet beet. tested after maintenance, but would have functioned after clearing the equipment tagout in effect.

The normal, startup, and emergency transformers were operable during this event. This occurrence presented no adverse conse-quences to the public health and safety.

Corrective Action:

The injector line was immediately replaced. The DG was tested satisfactorily and returned to service. Although this is the first I failure of this type at this site on either DG, components have been ordered to replace all injector lines on both diesels if such j action is considered necessary. Once these components are on site, replacement and inspection of lines will be accomplished during an appropriate diesel outage.

Sincerely, L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.