ML19340D592

LER 80-085/03L-0:on 801128 Borated Water Storage Tank Low Level Bistable Tripped.Apparently Caused by Loose Connection at Borated Water Storage Tank Level Transmitter.Lead Tightened

ML19340D592
Person / Time
Site:	Davis Besse
Issue date:	12/26/1980
From:	Isley T TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340D585	List: ML19340D584 ML19340D592
References
LER-80-085-03L, LER-80-85-3L, NUDOCS 8012310328
Download: ML19340D592 (2)

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$KRC 60 l Li@l 0l DOCKET 63 51 eNUMBER l -l 0 l 314 l69 6 ]@l 68 EVENT1 ] 1 l 2 l 8 l 8 REPORT DATE 14 15 l 0 l@l1 DATg l 802 l 2 l 6 l 8 EVENT OESCRIPTION AND PROSABLE CONSEQUENCES 4 l0l2l l (NP-33-80-109) On 11/28/80 at 0833 hours0.00964 days <br />0.231 hours <br />0.00138 weeks <br />3.169565e-4 months <br />. control room operators received a borated I l5Ti1 Iwater storage tank (BWST) low level alarm for Safety Features Actuation System (SFAS) I

[T171 l Channel 2. A check of the SNS Channel 2 cabinet revealed that the BWST low level bi-l l o l s i I stable had tripped. At 0836 hours0.00968 days <br />0.232 hours <br />0.00138 weeks <br />3.18098e-4 months <br />, the channel 2 level indication was declared inoperb-1 lc ls l lble, and the station entered Action Statement 9 of T.S. 3.3.2.1 Table 3.3-3. There f l

lctillwas no danger to the public or station personnel. T_he remaining three BWST level I

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43 44 47 33 35 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i 10 l l The apparent cause of the BWST level failure was a loose connection at the BWST level I g l transmitter. The screw holding the solderless_ connector was loose. Under MaintenancoI l

,,,7, l Work Order IC-787-80 the lead was tightened and the transmitter returned to service.

I l,13, l 0n 11/28/80 at 1505 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.726525e-4 months <br /> the Channel 2 BWST level indication was declared operable.

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s TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-109 DATE OF EVENT: November 28, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Safety Features Actuation System (SFAS) Channel 2 Borated Water Storage Tank (BWST) Level Indication Failed Low .

Conditions Prior to Occurrence: The unit was in Mode 1 with Power (MWr) = 2510 and Load (Gross MWE) = 845 Description of Occurrence: On November 28, 1980 at 0833 hours0.00964 days <br />0.231 hours <br />0.00138 weeks <br />3.169565e-4 months <br />, control room operators received a BWST low level alarm for SFAS Channel 2. A check of the SFAS Channel 2 cabinet revealed that the BWST low level bistable had tripped. The operator also observed the level indication spiking low. At 0835 hours0.00966 days <br />0.232 hours <br />0.00138 weeks <br />3.177175e-4 months <br /> the level indication went low '

off scale. The Channel 2 level indication was declared inoperable at 0836 hours0.00968 days <br />0.232 hours <br />0.00138 weeks <br />3.18098e-4 months <br />, and-the station entered Action Statement 9 of Technical Specification 3.3.2.1 Table 3.3-3.

The action statement requires the inoperable functional unit to be placed in the tripped condition within one hour. The bistable had tripped when the level indication failed.

Designation of Apparent Cause of Occurrence: The apparent cause of the BWST level failure was a loose connection at the BWST level transmitter. The screw holding the solderless connector was loose. There were no ambient or environmental conditions which would cause the screw to loosen. The cause is unknown.

Analysis of Occurrence: There was no danger to the health and safety of the public'or to station personnel. The remaining three BWST level channels were operable and would have performed the required functions.

Corrective Action: Under Maintenance Work Order IC-787-80, the Instrument and Control mechanics found the field lead loose at the transmitter. The lead was tightened and the transmitter returned to service. At 1505 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.726525e-4 months <br /> the station was out of the action statement of Technical Specification 3.3.2.1.

• Failure Data: There have been no previous reports of a channel of.the BWST level indica-tion being inoperable due to a loose terminal screw.

LER #80-085 l

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