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LER 77-090/03L-0:on 771107,during Review of Deficiency in Steam & Feedwater Rupture Control Sys Monthly Test,Reactor Coolant Pump Found Inoperable.Caused by Component Failure. Voltage Regulating Diode Replaced
	ML19326A510
Person / Time
Site:	Davis Besse
Issue date:	12/01/1977
From:	Mitchell D; TOLEDO EDISON CO.
To:	; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A493	List: ML19326A492; ML19326A510;
References
	LER-77-090-03L, LER-77-90-3L, NUDOCS 8002040697
	Download: ML19326A510 (2)
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mm 101311 Mon hiv Tes't. aoNblemaffectingthe~RPSwasfound. One of the four RCP monitors -l RPS .

El "5T"T4 frc$%di-VW2--2'T-gocreo RPR . Channel. 21 was _ determined to be_. inoperable. _

'I o I si F-channel -vas-declaredcinneerabia and tripped which placed. the statiott in Action _ _

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I I o is i I statement 3' oflechnica1 Soecific'attorr 3.Y.l.1.- The redundant.aPS channels, wouid _ .

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^- r i t o.}.F Compore.5t_dati-aiel v'as; the -cause-of this occurrence. ,-A., cur-rentz PCv voltage transducer

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-- g. [ +r & ~ current eni+or. had. a .def ective_ voltage.iragulating. :ener-diede. Cn '_

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Noiem5ei'10, T977, Control Syster: s personnel' replaced- the voltage- regulating :ener I.

.- ,, M l-l..d16de. The cha'anel_ was. d.clared. operable at 1405 hours0.0163 days 0.39 hours 0.00232 weeks 5.346025e-4 months ..on. November. 10, 1977. whic'a 1

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DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-90 DATE 0F EVENT: November 7, 1977 ACILITY: Davis-Besse Unit 1 IDENTIFkCATIONOF0CCURRENCE: -Inability of Reactor Protection System. (RPS). Channel -

. 2 to-recognize a locked rotor. (hig&L. current) condition. for . Reactor.-Coolant Pump,__.

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(RCP) motor 2-2. .

t Conditions"FIior co Occurrenew- l The. unit -was, in Mode- 2gi:th Power..(MWI) = 0 and ... .a .

Load (MWE) = 0. .

-- Desci:1 priori of'0Feurrence: Ar eL340: hours- on November 7,1-972,..during a review of. . . _.

), a deficiency ~in the Steam and: F7eeiiwEei.'tGipture Control Systam. ;(SFRCS) Monthly _ , ,1,.

Test, ST 5031.14, a problem gffecting the RPS was found. One of the four RCP m'onitors from RCF; motor 2-2 (-going.to RPS Channel 2) _was determined. to be..inopera j ..g- ,

ble such char the RPS Channeiv2 would not- recognize a; locked rotor condition of.

-the-2-2 pump motor. This -does. pat--affect the SFRCS since...it. ia concerned with ,__ .., _

loss of power to all four pump. motors, but does affect the-RPS.

The Technical Engineer was no.tified..and at 1335- hours, RPS Channel 2 was declared

- cinoperable and tripped which -placed the unit-in the Action;Stacament 3.of -Tech . -;; . . ..:.

nical Specification (TS) 3.3.1,.l. . . . ,

Designatiotr oF Apparent Causeiof Occurrence: Component failure was the cause of., - ,

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this occurrence. A current ep;yoitage transducer if RCP . motor current monitor had a defective voltage regulating-zener diode. -

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- -Analysis -of-Odedrrence: - Thergy--no -danger to.- the health ansi . safety .of the .public, .. --

or to station personnel. The redundant RPS channels would'have limited reactor. ,

power--if an overcurrent trip had -occurred. . ,,,

Corrective Action: On November 10, 1977, the voltage-regulating sener diode was ._ -.

replaced. The transducer was reinstalled and the calibration was_ satisfactorily -

m- 'chec'ked.MTST-5031.14; ."SFRCS Monchly . Test",.was performed for RCP

2-23 RES J.hannel--/ 5 --

e - 2 and a new _ response time check..was satisf actorily. perforced ,. ~3-C m . : :: ; --. .

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Tfie cha5 net %zs de51ared operable at 1405-hodrsr on Novembep40m117.7, which, removed. . :,

the station fr-om action Statetsent 3 of TS 3.3.1.1.- 1; .w- 2.-

Failure-Dees: No previous failures of these transducers have occurred.

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ML19326A510

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