05000346/LER-1979-072-03, /03L-0 on 790708:position Indication on Rod Two of Group Eight Was Inoperable.Caused by Component Failure of Reed Switch within Position Indicator Tube.Part Was Replaced & Returned to Svc

/03L-0 on 790708:position Indication on Rod Two of Group Eight Was Inoperable.Caused by Component Failure of Reed Switch within Position Indicator Tube.Part Was Replaced & Returned to Svc

ML19242A841
Person / Time
Site:	Davis Besse
Issue date:	08/02/1979
From:	Naylor R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242A839	List: 05000346/LER-1979-072, Forwards LER 79-072/03L-0 05000346/LER-1979-072-03, /03L-0 on 790708:position Indication on Rod Two of Group Eight Was Inoperable.Caused by Component Failure of Reed Switch within Position Indicator Tube.Part Was Replaced & Returned to Svc
References
LER-79-072-03L, LER-79-72-3L, NUDOCS 7908060450
Download: ML19242A841 (2)

LER-1979-072, /03L-0 on 790708:position Indication on Rod Two of Group Eight Was Inoperable.Caused by Component Failure of Reed Switch within Position Indicator Tube.Part Was Replaced & Returned to Svc

Event date:
Report date:
3461979072R03 - NRC Website

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U. S. NUCLE AR REGUL AT OR Y CGMMISSION NGC 4 ORM 3CG U 7/)

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2 l On July 8, 1979 at 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />, it was observed that the position indication on Rod 2 l

lof Group 8 was inoperable.

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o lThe exact cause is not known; the apparent cause ic-connonent failure of a reed switchI i

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TOLEDO ED130N COMPA N D^.VIS-BESSE NUCLEAR POWER STATIO:. UNIT ONE SUPPLEMESTAL INFORMATION FOR LER i:P-33-79-99 DATE OF EVENT:

July 8, 1979 FACILITY:

Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Position Indication fcr Red 2 of Group 8 Inoperable Conditions Prior to occurrence: The unit was in Mode 3, with Pcwcr (L'T) = 0, and Load (Gross FME) = 0.

Description of Occurrence: On July 8, 1979 at 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />, it was discovered that the The actica stat (rent of Tech-position indication on Rod 2 of Group 8 was inoperable.

nical Specification 3.1.3.3 (which requires that all safety regulating and axial power shaping control rods absolute position indication channels shall be operable and capa-

"T was not applicable, as the ble of determining the control rod positions within i i unit was in Mode 3 at the time of this occurrence.

This report is being submitted as docuneatation of a componant 1silure.

D e m gi.a :_i t. J ',,

• C=rc_cf Occurrence-Tha epparent cause of the ccrurronco has not been specifically found.

The nost likely cause is that of a faulty reed switch within the position indicator tabe (component failure). Thic caused fluctua-tions of the absolute position indication signal for the rod.

The position indicator will be returned to the vendor for final determination of cause of failure.

Analysis of Occurrence:

There was no danger to the 1 ealth and saf ety of the public or to station personnel. The unit was shutdown in h>t standby, and the relative position and zone reference indications for the rod,were operable.

Correc tive Action: On July 8, 1979, the positior. indicator tube f or Rod 2 of Group 8 was replaced with a rebuilt spare per Maintenance v:ork Order 79-2459 and tested per systan Surveillance Test ST 5013.03, " Control Rod Prcgran Jerification Test".

The rod and position indicator were returned to operaticn on July 10, 1979.

Failure Data: There have been several previously reported position indicator failures due to component failure of the position indicator tube in Licensee Event Reports NP-33-78-02, NP-33-78-135, and NP-33-78-144.

LER #79-072 516 OC5