ML19290E647

LER 80-015/03L-0:on 800210,during Normal Startup,Control Rod 5-11 Absolute Position Indication Declared Inoperable.Caused by Numerous Asymmetric Rod Alarms.Data from Current Failure Evaluated

ML19290E647
Person / Time
Site:	Davis Besse
Issue date:	03/07/1980
From:	Werner J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19290E612	List: ML19290E611 ML19290E647
References
LER-80-015-03L, LER-80-15-3L, NUDOCS 8003140330
Download: ML19290E647 (2)

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o 2 l On February 10, 1980 at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> during a normal startup, Control Rod 5-11 absolute ;

lo l3l l position indication (API) wcs declared inoperable due to numerous asymmetric rod

- g g [ alarms. This placed the unit in the action statement of Technical Specification g loisl l 3.1.3.3 which required the position of the control rod to be verified by actuating g lo is l l one of its zone reference indicators. There was no danger to the health and safety j

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-21 DATE OF EVENT: Februa ry 10, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATIGN OF OCCURRENCE: Control Rod 5-ll Absolute Position Indication (API)

Failure Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 471, and Load (Gross MWE) = 156.

Description of Occurrence: On February 10, 1980 at 1500' hours, Control Rod 5-11 API was declared inoperable due to numerous asymmetric rod alarms. This placed the unit in the action statement of Technical Specification 3.1.3.3 which permitted continued unit operation if the position of the control rod and its group is main-tained and periodically verified at one of the zone reference positions. The rod position was verified at its 100% withdrawn position per the action statement, and the rod position indication was placed in asymmetric bypass.

Designation of Apparent Cause of Occurrence: The exact cause of this occurrence is still undetermined but appears to involve two separate problems. One problem appears to be somewhere in the containment electrical penetration, the second appears to be somewhere in the position indication assembly, possibly the reed switches. Investigation is continuing at this time.

Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. The control rod did not vary from its intended posi-tion, only the API was faulty.

Corrective Action: During the last shutdown in February,1980, an additional test connection was made at the inner containment electrical penetration at existing butt splices in the API cabling. This was done under FCR 79-424 Rev. A, and as a con-tinuing corrective action to similar occurrences reported under Licensee Event Reporte NP-33-79-141 and NP-33-80-07. Data collected under Maintenance Work Order 80-1551 from present test connections is currently being evaluated by Toledo Edison and vendor personnel. Based on this evaluation, a decision concerning further corrective action will be made.

Failure Data: There have been previous failures of control rod APIS. Control Rod 5-ll's current symptoms were previously reported la Licensee Event Reports NP-33-79-141 and NP-33-80-07.

LER #80-015

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