05000298/LER-1981-020, Forwards LER 81-020/03L-0. Detailed Event Analysis Also Submitted

Forwards LER 81-020/03L-0. Detailed Event Analysis Also Submitted

ML20010G089
Person / Time
Site:	Cooper
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
ML20010G091	List: 05000298/LER-1981-020, Forwards LER 81-020/03L-0. Detailed Event Analysis Also Submitted 05000298/LER-1981-020-03, /03L-0: on 810728, During Procedure Returning Diesel Generator 1 to Svc After Flexible Fuel Line Leak, Control Air Line Fitting Failed Causing Generator to Shut Down. Caused by Broken Air Line Due to Crimped Ferrule
References
CNSS817500, NUDOCS 8109150315
Download: ML20010G089 (2)

LER-1981-020, Forwards LER 81-020/03L-0. Detailed Event Analysis Also Submitted

Event date:
Report date:
2981981020R00 - NRC Website

text

LEL 4,-Nebraska Public Power District COOPER NUCLEAR STATION

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CNSS817500 August 25, 1981

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U.S. Nuclear Regulatory Commission 2-b / 4) 4%

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Office of Inspection and Enforcement 2 h 1,\\ $

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Region IV

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Suite 1000 Arlington, Texas 76011 4e 0

Dear Sir:

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

Report No.:

50-298-81-20 Report Date:

August 25, 1981 Occurrence Date:

July 28, 1981 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identificatica 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.

Condition: Prior to Occurrence:

The reactor was at 96% of rated thermal power.

Description of Occurrence:

This event occurred while testing #1 Diesel Generator (Surveillance Procedure 6.3.12.1) to return it to service following replacement of the flexible fuel line described in LER 81-19.

During the test, a control air line fitting failed causing the DG to automarleally shut down due to low control air pressure.

Designation of Apparent Cause of Occurrence:

The failure of the fitting on the control air line occurred because the air line broke inside the fitting where the fitting ferrule gQ) was crimped to the line.

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8109150315 810825 PDR ADOCK 05000298 S

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

Anr. lysis of Occurrence:

The station's emergency power system consists of two emergency diesel generators, each capable of supplying power for post acci-dent safety system operation and safe reactor cooldown.

When attempting to test #1 DG to return it to service following the event described in LER 81-19, a_ control air line fitting failed, causing the DG to shut down due to low control air pressure. The fitting failed because the air line broke inside the fitting where the ferrule was crimped to the line. It is believed that engine vibration caused the air line to break at this stress point within the fitting. This condition existed for some undetermined period of time. Eventually, due to continued engine vibration, the fitting worked completely apart causing the loss of control air pressure and the automatic shutdown of #1 DG.

During this event the normal, startup and emergency transformers were available to supply power as the station required. This event presented no adverse consequences to the public health and safety.

3

Corrective Action

The defective fitting on the air line was immediately replaced and the same line on the other DG was inspected. The DG was satis-factorily tested and returned to service. The vendor has been contacted ~and a visit to the site has been scheduled to determine if any additional deficiencies in the DG control air system exist.

Sincerely,

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i L. C. Lessor l

Station Superintendent

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Cooper Nuclear Station l

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