ML19324B392

LER 88-002-02:on 880107,emergency Feedwater Actuation Occurred on Loss of Both Main Feedwater Pumps.Caused by Instrumentation & Control Technician Error.Idle Feedwater Pump Started & Actuation reset.W/891026 Ltr

ML19324B392
Person / Time
Site:	Crystal River
Issue date:	10/26/1989
From:	Moffatt L, Ken Wilson FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F1089-21, LER-88-002, LER-88-2, NUDOCS 8911060206
Download: ML19324B392 (5)

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. i Mar 26, 1989 .

3F1089-21 U. S. Nuclear Regulatory Comission Attention: M= ant Cbntrol Desk Washington, D. C. 20555-

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Subject:

Crystal River Unit 3  !

Docket No. 50-302 i Operating License No. DPR-72 Licensee Event Report No.- 88-002-02

Dear Sir:

Enclosed is a supplement to Licensee Event Report (LER) 88-002-02 which was pmviously submitted in accordance with 10 q CFR 50.73. .

Should there be any questions, please contact this office.

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! Very truly youm, a dh.

Kenneth R. Wilson Manager, Nuclear Licensing WIR: mag 1 l

E Enclosure l.

L xc: Regional Administrator, Region II Senior Resident Inspector l'

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l CRYSTAL RIVER UNIT 3 o i s l 0 lo l o 1310l 2 1loFl014 tit Lt **i Technician Error Causes Trip of,0perating Feedwater Pump Which kesults in Emergency Feedwater Actuation and Subsequent Overspeed of Steam Driven Emergency Feedwater Pump EVENT DATE ill Ltm WUletth l (Si SEPOMY DATI 171 OTH(M $ ACILill[$ INYOLVED ($)

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I I I l i I I I I l l 1 1 I SUPPLEMENT AL REPORT E XPECTED (tel MONTH DAY vlAR SO9M45lON 4t$ fit yes. towere GXPICTEO SUOMIS310N DA TEI NO l l l A .T R ACT m-, . ,e -., . . -- ,,,- y, -, ,,,ve ,,,,a n ei On January 7,1988, Crystal River Unit 3 was in the Hot Standby Mode (Mode 3) .

l An Emergency Feedwater actuation occurred on a loss of both main Feedwater  !

pumps. Se operating N punp tripped when control power was lost to its l governor. S e motor driven EF pump started as designed, but the steam driven EF pump started ard then tripped on an overspeed condition.

We cause of the loss of power to the W pump governor was an error by an I&C technician working on a radiation monitor which is powered from the same breaker as the W pump governor. Se MFW pump should not have tripped when control power was lost. % e cause of the trip of the steam driven EF pump was the insuper positioning of the bypass valve around the steam supply valves to the pump.

h e idle W pump was started, and once it was verified that the main Feedwater system was controlling level properly, the EF actuation was reset. We technician involved has been counselled in accordance with approved plant l policies. A mechanical lockirg device has been installed on the steam supply I

bypass valve, and a procedure change has been made to improve the monitoring of 1 this valve's position.

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09 MANAGlMtNr AND UDG E T, Vv ASHINGTVN,0C 201@3. 'ci

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On January 7, 1988, Crystal River Unit 3 (CR-3) was in the Hot Standby condition (Mode 3). Se "B" main Feedwater (W) punp (SJ,P] was in operation with the steam generators (SG) being maintained at their low level limits. A modification was in pi@uss on one of the area radiation monitors (IL, MON].

{ At approximately 1150, the fuse (W) for the Vital Bas breaker (BKR] which powers this radiation mnitor was opened due to an error by the technician.

'Ihis breaker also supplies the control power to the governor (65] for the "B" W punp, and the "B" W punp tripped. Since the "A" W punp was already tripped, an Emergency Feedwater (EF) (BA] system actuation occurred on a loss of both main W punps with the Reactor Protection System (RPS) not in shutdown bypass.

When the EF actuation occurred, both EF punps (BA,P] received auto start signals. Be motor driven EF punp started as required aM delivered flow to

.the steam generators as designed. Se steam driven EF punp tripped on overspeed after starting. Operators started the idle "A" W punp, aM at approxinately 1210, the EF actuation was reset and SG levels were controlled using the "A" W punp.

GU._SIl j te cause of the EF actuation was the loss of both main W pumps. S e cause of i

the fuse opening for the vital bus breaker which supplies both the "B" W punp governor and several radiation monitors was an error by a utility I&C technician. It is thought that the loss of control power to the "B" W pump governor resulted in the tripping of that pump. A further Ergineering review of the applicable drawings is being conducted to determine if the loss of the I governor should have only throttled closed the steam admission valves to the W purp turbine. 'Ihis would have caused the punp to " coast" to a minimum speed condition, which would have given the operators some time to try to prevent the loss of main feedwater.

Se cause of the steam driven EF punp tripping after starting was improper positioniry of the throttle valve in the bypass line around the steam supply l

valves for the EF pump turbine. 21s valve was fouM to be insufficiently l open, which allowed the buildup of condensate in either the pump turbine or in j the steam inlet line. Se buildup of coMensate is a proven cause for j overspeed trips.

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Se Emergency Feedwater Initiation and Control (EFIC) (BA,GA] system functioned as designed ard issued start signals to both EF punps upon a loss of both main W punps with the RPS not in shutdown bypass. We motor driven EF punp started as requjred and delivered flow to both steam generators. We steam driven punp tripped on overspeed. mis trip is considered to be an isolated event, since proper operation of this punp had been demonstrated three times within the previous 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, was demonstrated again imediately following the event, and approximately two days later. It is also inportant to realize that the Emergency Feedwater System is designed such that one punp is capable of providing 100% of system requirements for all analyzed transients.

Based on the above, the Safety significance of the event is minimal.

ui<REvnVE ACTION:

After the main feedwater system had been restored to a normal configuration ard was verified to be controlling steam generator levels, the EF actuation was reset. Se steam supply bypass valve for the steam driven EF punp was opened to its correct position and the punp was su-fully started per approved procedures. It should also be noted that the steam driven EF punp was autmatically started on January 9 as a result of another EF actuation, and it operated properly (this event is described in IER 88-01) .

l Counselling of the utility I&C technician involved in this event has been accouplished in accordance with approved plant policies. Engineering has performed a review of applicable drawings for the W punp governor and determined tne punp should not have tripped during the transient due to the I&C technician's action. Troubleshooting of these circuits was performed to l

ascertain the cause of the pump trip. No cause for the tripping of the B W pump could be determined.

Several steps have been taken to prevent a futum trip of the steam driven EF punp on overspeed. We surveillance procedure urder which operators perform their daily logs has been revised to provide additional guidance on how the l

proper positioning of the steam supply bypass valve for the steam driven EF punp can be determined. Se initial guidance included a twice per shift check.

mis guidance is being changed to a single check per shift based on no instances of the bypass line being closed. In addition, a mechanical locking l

I device has been installed on the steam supply bypass valve which prevents closure of this valve beyond a predetermined position. mis position is designed to allow enough bypass steam flow to prevent the buildup of cordensation in the turbine and steam inlet line.

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0l2 0l4 or 0l4 text in  % -unc %w.,nn PREVIOUS SIMII.AR EVDES:

'Ibere have been previous wants involvirg EF actuations, as reported in IER 88-01 and IER 85-12. 'Ibere have also been several previous occurrences of the steam driven EF punp tripping on an overspeed condition. 'Ibe most recent of these is described in II:R 86-021.

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