ML19242C480

LER 79-076/03L-0 on 790708:reading of Core Flood Tank Level Indicator Li-CF3B2 Did Not Appear to Read Same as Indicator LI-CF3B1.Caused by Faulty Amplifier in Level Transmitter LT-CF3B2.Amplifier Replaced & Transmitter Recalibr

ML19242C480
Person / Time
Site:	Davis Besse
Issue date:	08/03/1979
From:	Borysiak M TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242C477	List: ML19242C476 ML19242C480
References
LER-79-076-03L, LER-79-76-3L, NUDOCS 7908100467
Download: ML19242C480 (2)

Text

U. Ss NUCLE AR REGUL ATORY COMMISSION NRC F ORM 366 (7 71)

LICENSEE EVENT REPORT CONTFlOL BLOCK: l l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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81*@ TCATE b) 8 60 til DOC AET NVYdt H EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h io 2 [On July 8,1979, at O' 00 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, the Core Flood Tank (CFT) 1-1 Icw level alam was re- l

,a 3 [ ceived.

Investigation revealed that the reading of CFT level indicator LI-CF3B2 did i

1. o 4 lnot appear to read correctly as compared to I.I-CF3Bl. Since redundant level indica- i lo 5 l tor LI-CF3B1 was operating properiv. no action statements "ere e n tcc e . This report l l o l6 ] l is being submitted as documentation of a component failure. Thece was no dancer to 1 0 7 the health and safety of the public or station personnel. The loss of one of the two l l CFT 1-1 level transmitters did not render this CFT inoperable. GG- 3 3- 79-8 M 1 1o a 8J 8 9 7

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_ 21 C C'*FONE N T S, H J T OOi A TT AC HY E N T *NF4 P YE C2 P ACTION FUTURE EFFECT s YANtF ' Cl u h E n TAKEN ACTP . ON PL 1 NT W TWJO 6 URS SL9Yi T T E D FOH'* n s 5 ;' E4 l lhl lh I lh l hl J Ik'l0 40 l l Yl@

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i o l The cause was found to be a faulty amnlifier in level transmitter LT-CF3B2. Instrumont The i 3 j and Control persor tel replaced the amplifier and calibrated the trausmitter. i On

,,, i ampli f ier is being returned to the vendor for determination of the root cause. l l

,g,,(Juty 10, 1979, at approximately 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br />, a surveillance test wa s pe r f o rmer' which g , ,4 g g ve. i fled the operability of LI-CF3B2. 03 J

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-84 DATE OF EVENT: July 8, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Failure of Core Flood Tank 1 level transmitter LT-CF3B2

_ Conditions Prior to Occurrence: The unit was in Mode 3, wit < Power (MWT) = 0, and Load (Gross MWE) = 0.

Description of Occurrence: On July 8,1979, at approximately 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br />, the control room operator received Core Flood Tank 1-1 low level alarm. Upon referring to the level Jndication, the operator discovered core flood level indicator LI-CF3B2 reading had dropped to indicate a zero level. Since no core flood tank low pressure alarms were received and there was no indication of a core flood tank actuation, the low level indication was determined to be erroneous. Since the redundant level indicator (LI-CF3B1) for Core Flood Tank 1-1 was operating properly, the unit did not enter any action statements. This cccurrence is being reported as documentation of a component failure.

Designation of Aoparent Cause of Occurrence: The cause of the Core Flood Tank 1-1 low level alarm and the loss of level indication was found to be due to a defective amplifier in the level transmitter. Instrument and Control personnel replaced the amplitier and LT-CF3B2 was returned to operable status. The amplifier is being returned to the manuf acturer, Bailey Meter Company, fer repair and an analysis of the failure.

Analysis of Occurren q: There was no danger to the health and safety of the public or to station personnel. The redundant Core Flood Tank 1-1 level indication, LI-CF3B1, was operable. The loss of one of the two Core Flood Tank 1-1 level transmitters did not cause an inoperability of this core flood tank.

Correcti"e Action: The defective amplifier was replaced, and the transmitter calibrated through Instrument and Control Work Order 336-79. On July 10, 1979, at approximately 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br />, Surveillance Test ST 5099.01, " Miscellaneous Instrument Shlft Check", was successfully performed which verified the operability of the level transmitter.

Failure Data: There have been no previous reported f ailures of core flood tank icvel ins t rum en ta t ion .

LER J79-076 g .on<

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