ML18353B231

Unusual Event Report UE-75-2 Re Failure of Control Rod No. 30 to Drop Properly

ML18353B231
Person / Time
Site:	Palisades
Issue date:	04/10/1975
From:	Sewell R Consumers Power Co
To:	Office of Nuclear Reactor Regulation
References
LER 1975-002-00
Download: ML18353B231 (2)

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Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201

• Area Code 517 788-0550 Division of Reactor Licensing Re: Docket 50-255 US Nuclear Regulatory.Commission License DPR-20 Washington, DC 20555 Palisades Plant UE-75-2 Gentlemen:

Attached is Unusual Event Report UE-75-2 which covers the failure of Control Rod No 30 to drop properly. This failure occurred during testing with the plant in hot shutdown and there was no effect on plant operation.

The Palisades Technical Specifications permit plant operation with an inoperable control rod.

Very truly yours, DAB/ce Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USNRC

• 1. Report No:

UNUSUAL EVENT REPORT Palisades Plant UE-75-2, Docket 50-255 2a. Report Date: April 1, 1975 2b. Occurrence Date: March 29, 1975

3. Facility: Palisades Plant, Covert, Michigan

4. Identification of Occurrence: Control Rod No 30 failed to drop properly during rod drop timing test.

5. Conditions Prior to Occurrence: The reactor was in the hot shutdown condition.

6. Description of Occurrence: On March 29, 1975 CRDM torque and control rod drop testing was being conducted. During the testing, Control Rod No 30 failed to drop properly when the clutch switch was opened. Successive testing showed rough operation coupled with slow or incomplete rod drops.

7. Apparent Cause of Occurrence: An apparent cause of the event has not been de-termined. Further investigation will be conducted at the next cold shutdown *

8. Analysis of Occurrence: PRC review of the incident concluded that plant opera-tion can continue per Technical Specifications Section 3.10.4.b. The control rod is mechanically operable but is classified as "inoperable" because it can-not be satisfactorily tripped.

9. Corrective Action: The following corrective action was taken or will be taken:

a. It was recommended that this control rod not be further exercised or oper-ated unnecessarily and so noted in daily orders in shift supervisor's office.

b. Continue the investigation into the cause of the malfunction. Engineering assistance is to be provided to follow up on the repair of the drive unit.

10. Failure Data:

a. There is no record of any previous malfunctions of this type on any of the CRDMs.

b. Control Rod Drive No 30 manufacturer is Combustion Engineering, Inc and the piece number is J-2966-163-001 *