ML20086B419

AO 50-267/74-15:on 740806,following Simulation of Loss of Outside Power & Main Turbine Trip,Load Sequencing Programmers Failed.Caused by Screws Not Initially Tightened. Semiannual Program Established

ML20086B419
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/09/1974
From:	Liebelt J, Mathie F, Swart F PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20086B380	List: ML20086B384 ML20086B401 ML20086B414 ML20086B419
References
AO-50-267-74-15, NUDOCS 8311170203
Download: ML20086B419 (3)

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ADNORMAL OCCURilEN('E U 'I 0; __l'.!!D.ii 9a 1974 FORT ST. VRAIN NUCLEAR ChMERAT1Hr. STATION PUBLIC SERVICE COMPAth' 0F COLOllADO P. O. DOX 361 PLATTEVILLE, COLORADO 80651 REPORT No. 50-267/74/15 PREL1HINARY IDENTIFICATIGN OP OCCURRENCE:

Malfunction of load acquencing programmers, following a sinulation of loss of outside power and main turbine trip, on Tuesday August 6,1974.

This is considered an abnormal occurrence, per section 2.1 (f) of the Technical Specifications.

CONDITIONS PRIOR TO OCCURRENCE: Steady State Power Routine Shutdown 110t Shutdown , Routine Load Change X Cold Shutdown other (specify)

Refueling shutdown Reactor in helium at approximately Routine Startup atmospheric pressure The major plant parameters at the time of the event were as follows: ,

Power PTR, 0 Wth ELECT, O We Secondary Coolant '- ~ Pressure 0 psig Temperature 0 *F Flow 0 #/hr.

Pressure O psig Primary Coolant Tanperature 100 *F. Core Inlet m 100 *F Core Outlet 8311170203 741209 PDR ADOCK 05000267 PDR .ow 0 #/hr.

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In preparat ion for i nanine. S/R 5.6.16-SA, (Sirm:1at ing 1.onn of Otu nide Pouer aml 11ain Turbine Trip) a nalf unction of contact: in one Dienel- Generat er inalu breaker cauned the 252 TX relays (load shedding) not to operate, and prevented any further auto action.

ANAL.YSIS OF OCCimRD:CE:

The malfunt tion of contact s on the "li" Diesel Generator nain brenhcr, was caut.cd due to loone nerews holding the auxiliary nuitch mechanism; there-fore the uvitch rained, instead of actuating the rotor of the switch. Both generators started and came to npeed and voltage but did not load automatically.

Al'PARDff CAUSE Design Unusual Service Cond.

OF OCCLIRRENCtQ _

Including Environ.

Manufacture Co::tponent Failure X Installation /Const. Other (specify)

Operator Procedure Screws not properly tichtened initially, t

CORRECTIVE ACTION: __

A semi-annual program has been set up to combat loose equipment in the diesel-generator breakers. In addition, Engineering changes are being surveyed to prevent f ailure of all load sequencing programmers to function with one failure of equipment.

FAILURE DATA /SIMILAR REPORTED OCCURRENCES: .

This equipment has not failed in the past tests.

None

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PHOCRA}DMTIC I!n'ACT:

None ,

.UJ.EE_Il91ASD.

Violation of single failure criterin design. .

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?MfM Frank M. Mathie V l$ 'l$

J m Liebelt Superintendent Maintenance

lectrician Specialist 1 11 Amu 7i i

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i F/edericE. Swart ~ l Superintendent Nuclear Production 4

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. . . - A ny m .t l FORT ST. VitAIN NUCLEAR GENERATl!T STATION PUBLE SI:l'VICE COMPANY OF Cos.0:tADO l l

P. O. BOX 361 PLATTEVILLl', COI.ORADO 80651 REPORT UO. 50-267/74/16 F111AL IDENf1FICATION OF OCCUlutENCE:

Mal f unction of one diesel-generator load sequencing progra tmer follo.'ing a s!nulation of loss of out side power and main turbine trip.

This is considered an abnormal occurrence, per section 2.1 (f) of the Technical Specifications.

CONDITIONS PRIOR Steady State Power Routine Shutdown T10CCURRENCI':

llot Shutdown Routine Load Change X Cold Shutdcwn Other (specify)

Refueling Shutdown Reactor in helium at approventely Routine Startup atmospheric pressure The major plant parameters at the time of the event were as follows:

Power PTR, O MWth ELECT, O MWe Secondary Coolant Prassure O psig Temperature 0 'F I

c. Flow 0 -

1. /hr.

Primary Coolant Pressure O psig Temperature 100 *F Core Inlet 100 *F Core Outlet Flow 0 f/hr.

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• O'" Page 2 DESCulPTION OF .

OCCU MM h:-;C M .

i Af t er i epairing t he probicm report ed in Abnormal Occurrence Report No. 50 267/74/15, n cmnplete t ent of the lonn of outnide power and naf u  !

turbine t rJp mis accomplished with very natisf act ory results. Upon rev iewing all part s involved , it was diccovered that one of t ha r edundant load pronramer drums had not conpleted it a cycle of 99 seconds. Further investigation revealed in narkin,; tape f roa the dru:a showing the ceconds had come loose and was caacht the hearn and actuated the (home base) contact shutting down the drum at 23 ,

sec ond s. llovever the redundant drum completed it a cycle perfor:aing its functivn as deninned.

i APPAL!EI;T CAUSE 0F OCClnutty;CE- _

Design Unusual Service Cond.

Including Environ. l i

Manufacture _Conponent Failure {

6 X Installation /Const. Other (specify) {

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4 Operator i

t Procedure i

Tape applied to the sequencer drum to facilitate narking of times for sequences had come loose and prematurely shutdown the drum by tripping the home base contact.

ANALYSIS OF OCCURRENCE:

The apparent shutdown of the programmer was due to tape applied to the drum and getting caught in the microswitches that shuts down the drum once it has been actuated.

Coltlu'CTIVE ACTION:

The tape has been removed from all drums' of the programmers.

FAII.URE DATA /SIMILAR _ REPORTED OCCURRENCES:

None

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PROI;!tAf f !ATIC 114 PACT:

None Coll!: 1" PACT:

None

, .o mec/2 L f.- & # W im Liebe'l E Frank ii. Mathie

-:lectrician Specialist Superintendent Maintenance

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Approved: a L, n$n e, e t a ederic E. Swart perintendent Nuclear Production t-c.

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