ML19274D101

LER 78-122/03L-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

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: ML19274D099 ML19274D101
References
LER-78-122-03L, LER-78-122-3L, NUDOCS 7901120161
Download: ML19274D101 (3)

Text

U.S. NUCLEAR REGULATORY COMMISSION RC FORM 366 17M LICENSEE EVENT REPORT v .

(PLE ASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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' 8 60 61 DOCKET NUvS ER 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 g 3 l was erratic.

o 4 ing the unit in the Action Statement of Technical Specifice.ian 3.1.3.3. There was I Reintive posi-l l o i s ] l no danger to the health and safety of the public or to unit personnel.

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o 6 l tion, as well as zone reference indication for Rod 3-4 were operable during l

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lZ 44 lZ lZ lZ lQ 47 3L 36 i CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h the cause of the occurrence hasi i g l By testing the individual components of the PI string, been determined to be an intermittent failure of a component within the position indi-l y,;3, The position indicator tube was replaced. Diamond Power, the position [

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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.

Analysis of Occurrence: There was no danger to the health and safety of the public 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 Request 78-501 to relocate API cable CCCRD110 for Rod 3-4 to a different cable in 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.

ST 5013.03 Sections 6.5, 6.7 and 6.10 f or Rod 3-4 " Rod Program Verification" was 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 On Deccaber 20, 1978, under Maintenance Work Order 78-2908, and Facility Change Request 78-538, the API cable CCCRD130 was returned to its original location.

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

Failure Data:

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