ML19326A210

LER 78-002/03L-0:on 780103,control Rod Group 5 Rod 12 Absolute Position Indication Declared Inoperable.Caused by Component Failure of Absolute Position Indicator Reed Switch.Switch Replaced

ML19326A210
Person / Time
Site:	Davis Besse
Issue date:	01/31/1978
From:	Nelson J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A208	List: ML19326A207 ML19326A210
References
LER-78-002-03L, LER-78-2-3L, NUDOCS 8002030068
Download: ML19326A210 (3)

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gr ; ,l On 1/3/7S, ct I?.30 huur:, Control Rod Creun 5, Rod 12, A5 salute Posi: ion Indic it or I g3;,, ; was da:lared inoperabic. This placed the unit in the Action Statcrent o f TS 3.1. 3. 3. I g ,, 4 4 , l which recuires both relative and absolute position indication in ': odes 1 and 2. At I

oit, ; 0040 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> on 1/5/73. the unit entered tiode 3, removinn the unit fro

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CAUSE GE3t!P*10.'! AND tCU E ::VE ACTIONS I

l3 :. lThe apparent cause of this occurrence was due to a comsonent failure of the Absolute t

[3 4,l iPosition Indicator Reed Suitch. On Januarv 7. 1978. the Absolute Position Im i :,t.w  !

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iTube containin:; the Reed Switch for Control Rod Group 5. Rod 12 was replaced. I i, t ai i I I

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[ ') DAVIS-BESSL USLI 0:iE NUCLE..R l'O'..'CR STAT 10:

\v/ SUPril::- : rat I:*rnR*n_TICM ro" LER MP-33-78-02 DAIES OF EY:ST: January 3, 16, and 24, 1978 FACILITY: Davis-Besse Unit 1 IDENTIFICATI0: OF OCCURRENCE: Asymmetric Fault Indication on Absolute Position Indicator on Control Red Group 5, Rod 12 Conditions Prior to Occurrence: The unit was in Modes 1, 2, or 3 with Power (irJT) ranging between 2100 - O and Land (:r.:E) ranging between 700 - 0.

Description of Occurrence: On January 3, 1973 at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, Control Rod Group 5, Rod 12, absolute Position Indicator was declared inoperabic due to fluxuatir?.

signals from the Position Indicator causing an " Asymmetric Rod" Alarm. This placed the tulit in the Action Statement of Technical Specification 3.1.3.3 uhich requires both relative and absolute position indication in Modes 1 and 2. The l control rod position was verified at 100% withdrawal by using the zonc reference lights. The rod panition was verified at its 100% position at time of occur-rence on January 4, 1978 at 0612 hours0.00708 days <br />0.17 hours <br />0.00101 weeks <br />2.32866e-4 months <br />, 1326 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.04543e-4 months <br /> and at 1825 hours0.0211 days <br />0.507 hours <br />0.00302 weeks <br />6.944125e-4 months <br /> in accor-

. _ , dance with the Action Statement. At 0040 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> on January 5,1978, the unit N

entered :'ade 3, removing'the unit from the Action Statement of Technical Specifi-s s

cation 3.1.3.3 On January 7, 1978, the Absolute Position Indicator (API) tube containing reed suitches for the Control Rod Group 5, Rod 12, was suspected to be the cause of this occurrence and was replaced under Maintenance Procedure MP 1401.08, which also verified operability of the new tube.

A subsequent event, however, occurred on January 16, 1978 at 0928 hours0.0107 days <br />0.258 hours <br />0.00153 weeks <br />3.53104e-4 months <br /> in which API indication briefly oscillated for Control Rod Group 5, Rod 12. The indica-tion retur.ned after che oscillations. Since the unit was at Mode 3 at the time of the occurrence, no Action Statements were entered.

Also at 1250 hours0.0145 days <br />0.347 hours <br />0.00207 weeks <br />4.75625e-4 months <br /> on January 24, 1978, the API for Control Rod Group 5, Rod 12 briefly oscillated three times within thirty minutes. At 1224 hours0.0142 days <br />0.34 hours <br />0.00202 weeks <br />4.65732e-4 months <br />, the API for Control Rod Group 5, Rod 12 was placed in r>YPASS which placed the unit in the Action Statement of Technical Specification 3.1.3.3. Control Rod Group 5, Rod 12 position was verified by the zone reference lights at approximately 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> in accordance witn the Action Statement.

Desienation of Aoncrent Cause of Occurrence: The apparent cause of this occur-rence was a loose eennec:or plug (Fil of Cable CCC RD lilA) possibly due to incorrect initial irstallation.

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SUPPLL::E::T/J. I: F0FJ:/,TIO:: FC:; LE". ::P-3 3-7 5-02 PACC 2 Analysis of Occurrence: There was no dan;;er to the health and safety of the public or to unit personnel. The control rod never deviated from its intended position. Only the rod position indication was defactive.

Correctiv,e Action: On January 24, 1978 at 1224 hours0.0142 days <br />0.34 hours <br />0.00202 weeks <br />4.65732e-4 months <br />, cable connections in the API strin;: for Contrcl Rod Cros.p 5 Rod 12 were inspcceed. Connector Flug Pil of Cable CCCR0111A within Centrcl Rod Drive System Analog Inter f ace Cabinat C480lT was removed, inspected and retightened af ter it was initially found slightly loose.

At 1732 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.59026e-4 months <br /> on January 24, 1978, the API and Relative Position Indientor were verified operable for Control Rod Group 5, Rod 12, which removed the unit from the action Statement of Technical Specification 3.1.3.3.

Failere Data: One previous reported failure of Control Rod Drive connectors has occurred. The failure wa.i, however, within a Control Roon Cabinet. See Licensea Event Report CP-33-77-SS.

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