05000346/LER-1978-122-03, /03L-0 on 781208:control Rod 4 of Group 3 Absolute Position Indication Was Erratic Due to Intermittent Failure of a Component within the Position Indicator Tube

/03L-0 on 781208:control Rod 4 of Group 3 Absolute Position Indication Was Erratic Due to Intermittent Failure of a Component within the Position Indicator Tube

ML19274D101
Person / Time
Site:	Davis Besse
Issue date:	01/05/1979
From:	Naylor R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19274D100	List: 05000346/LER-1978-122, Forwards LER 78-122/03L-0 05000346/LER-1978-122-03, /03L-0 on 781208:control Rod 4 of Group 3 Absolute Position Indication Was Erratic Due to Intermittent Failure of a Component within the Position Indicator Tube
References
LER-78-122-03L, LER-78-122-3L, NUDOCS 7901120161
Download: ML19274D101 (3)

LER-1978-122, /03L-0 on 781208:control Rod 4 of Group 3 Absolute Position Indication Was Erratic Due to Intermittent Failure of a Component within the Position Indicator Tube

Event date:
Report date:
3461978122R03 - NRC Website

text

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EVENT DESCRIPTI,0N AND, PROBABLE CONSEQUENCES h Control Rod 4 of Group 3's Absolute Position Indication (API)l g g l On 12/8/78 and 12/11/78, The absolute position indication channel was declared inoperable, plac-I l was erratic.

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7 8 9 10 DVR 7J-183 Rick Naylor

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR PG?ER STATION UNIT ONE SUPPLEMENTAL I'; FORMATION FOR LER NP-33-78-144 DATE OF EVENT:. December 8 and 11,1978 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Absolute Position Indication for CorJ-ral Rod 4 at Group 3 Inoperable.

Conditions Prior to Occurrence: On December 8,1978, the unit was in Mode 3, with Power (MWT) = 0, and Load (Gross MWE) = 0.

On December 11, 1978, the unit was in Mode 1, with Power (MUT) = 2514, and Load (Gross MWE) = 835.

Description of Occurrence:

On December 8, 1978, during a unit startup, Control Rod 4 of Group 3's Absolute Position Indication (API) was erratic. At 1112 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.23116e-4 months <br />, an asymmetric rod alarm was received, and the rod absolute position was declared in-operable, placing the unit in the Action Statement of Technical Specification 3.1.3.3.

The Technical ~,ecification requires all position indication channels to be operable whenever th unit is in Modes 1 or 2.

The reactor was shutdown and the unit entered Mode 3 at approximately 1115 hours0.0129 days <br />0.31 hours <br />0.00184 weeks <br />4.242575e-4 months <br /> on December 8,1978.

On December 11,1978, Rod 3-4 experienced several rod withdrawal inhibit interlock actuations due to the erratic operation of the API. The position indication was declared inoperable at 1510 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.74555e-4 months <br />, placing the unit in the Action Statement of Technical Specification 3.1.3.3.

At 1655 hours0.0192 days <br />0.46 hours <br />0.00274 weeks <br />6.297275e-4 months <br />, this API signal for Rod 3-4 was placed in asymmetric bypass.

Unit operation continued under Action Statement (a.2) of Technical Specification 3.1.3.3.

Designation of Apparent Cause of Occurrence:

By testing the individual components of the PI string, the cause of the occurrence has been determined ~to be an inter-mittent failure of a ccaponent within the position indicator tube.

There was no danger to the health and safety of the public Analysis of Occurrence:

or to unit personnel.

Relative position, as well as zone reference indication for Rod 3-4 were operable during the period the API was inoperable.

Corrective Action

On December 7,1978, work had been completed per Facility Change 78-501 to relocate API cable CCCRD110 for Rod 3-4 to a different cable in Request the penetration PCCSU.

ST 5013.03, " control Rod Program Verification", was completed satisfactory.

LER #78-122

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-78-144 On December 8,1978, under Maintenance Work Order 78-2364, Maintenance personnel The cleaned and dried the connections on the position indicator for Rod 3-4.

cable from the position indicator to the bulkhead was replaced with a new cable.

Sections 6.5, 6.7 and 6.10 f or Rod 3-4 " Rod Program Verification" was ST 5013.03 The API for Rod 3-4 was declared operable.

completed satisf actory at 2130 hours0.0247 days <br />0.592 hours <br />0.00352 weeks <br />8.10465e-4 months <br />.

On December 19, 1978, under Maintenance Work Order 78-2873, the position indicator tube was replaced.

i 20, 1978, under Maintenance Work Order 78-2908, and Facility Change On Deccaber 78-538, the API cable CCCRD130 was returned to its original location.

Request the position indicator vendor, was contacted and will further in-Diamond Power, vestigate the failure of the position indicator tube.

Previous occurrences of API failures on Rod 3-4 were reported in Failure Data:

Licensee Event Report NP-33-78-135; r eports on other API failures were reported in NP-33-78-02, NP-33-78-19, NP-33-78-26, and NP-33-78-38.

LER #78-122