05000298/LER-1978-034, Forwards LER 78-034/03L-0

Forwards LER 78-034/03L-0

ML20148A716
Person / Time
Site:	Cooper
Issue date:	12/07/1978
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20148A721	List: 05000298/LER-1978-034, Forwards LER 78-034/03L-0 05000298/LER-1978-034-03, /03L-0 on 781111:during S.P.6.4.1.2. (Withdrawn Control Rod Operability), Control Rod 30-31 Was Found Uncoupled from Its Control Rod Drive. Cause Cannot Be Determined Until Control Rod Drive Is Removed & Examined
References
NUDOCS 7812290197
Download: ML20148A716 (2)

LER-1978-034, Forwards LER 78-034/03L-0

Event date:
Report date:
2981978034R00 - NRC Website

text

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=e COOPER NUCLEAR ST ATION h O. Box 98, DROWNVILLE, NEBRASKA 68321 Nebraska Publ.ic Power Distr. t ic 1ELEmoNE sm ers.38u u.--.. - _ - = - _ _

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December 7, 1978 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011

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 November 11, 1978.

A licensee event report form is also enclosed.

Report No.:

50-298-78-34 Report Date:

December 7, 1978 Occurrence Date: November 11, 1978 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Conditions leading to operation in a degraded mode permitted by a limiting condition for operation in Section 3.3.B.1 of the Tech-nical Specifications for Cooper Nuclear Station.

Conditions Prior to Occurrence:

Reactor at approximately 72% power.

Description of Occurrence:

During performance of surveillance procedure 6.4.1.2, Withdrawn Control Rod Operability, control rod 30-31 traveled to its overtravel position indicating that the control rod and control rod drive were uncoupled.

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781229cV17 i

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Mr. K. V. Seyfrit December 7, 1978 Page 2.

Designation of Apparent Cause of Occurrence:

The cause of the control rod uncoupling cannot be determined until the control rod drive is removed and examined.

Analysis of Occurrence:

Control rod drive 30-31 was a rebuilt CRD installed in the reactor in April 1977. All surveillance and nuclear evaluation procedures indicated proper and reliable operation.

The CRD Coupling In-tegrity Check, Surveillance Procedure 6.4.1.3, indiaated proper coupling in April 1977 after installation and also after refueling outages in October 1977 and April 1978. A Withdrawn Control Rod Operability Check, Surveillance Procedure 6.4.1.2, is performed weekly during plant operation. A review of this data indicates that the subject control rod drive had always been coupled.

The control rod was recoupled to its control rod drive upon discovery of its uncoupled condition.

Control rod drive 30-31 was uncoupled from its control rod in the fully withdrawn position and thus the consequences of a rod drop accident do not exist.

The occurrence presents no adverse consequences from the standpoint of public health and safety.

Corrective Action

The control rod was subsequently recoupled to control rod drive and verified coupled per surveillance procedure 6.4.1.2, Withdrawn Control Rod Operability.

During the next refueling outage, we plan to replace Control Rod Drive (S/N 1953) in core location 30-31 with a new or rebuilt drive. An evaluation of the cause of this oc-currence will then be made.

If the cause can be determined, an updated LER will be submitted.

Sincerely,

[

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