05000285/LER-1990-010

LER 90-010-01:on 900327,unplanned Attempted Start of Emergency Diesel Generator Occurred While Plant in Refueling Shutdown.Caused by Low Air Pressure in Diesel Start Sys. Instructions Re auto-start Signals changed.W/900703 Ltr

ML20055D411
Person / Time
Site:	Fort Calhoun
Issue date:	07/03/1990
From:	Gates W, Molzer D OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-010, LER-90-10, LIC-90-0480, LIC-90-480, NUDOCS 9007060277
Download: ML20055D411 (4)

LER-2090-010,

Event date:
Report date:
2852090010R00 - NRC Website

text

- - .. . . - . - .. . . .- . , - -. ,

,l .y <

i J b >;I ,

a= . :- ,

Omaha Public Power Disttiet 444 South 16th Street Mall Omaha, Nebraska 68102-2247 ~

402/636-2000

= July 3, 1990 LIC-90-0480 U. S. Nuclear Regulatory Commission-

-Attn: Document Control Desk Mail Station P1-137 Washington,' DC 20555 l l

Reference:

-(1)DocketNo.50-285 l' (2)LicenseeEventReport90-10, April 26,1990(LIC-90-0304)

' Gentlemen:

l:

Subject:

Licen:;ee Event Report 90-10, Revision 1 for the Fort Calhoun I

. Station L Please find attached Licensee Event Report 90-10, Revision 1 dated July L 3, 1990. :An. inapplicable procedure number was inadvertently included in i the correctiveiactions of the: original version of this report. This  ;

revision )rovides corrected and updated information identified.by a  !

vertical )ar in-the margin. This report is being submitted pursuant to '

10 CFR 50.73(a)(2)(iv).

If you should have any questions, please contact me.

Sincerely, f Aj.M ,

W. G.-Gates.

Division Manager Nuclear Operations -i WGG/tcm Attachment i

c:, R.'D. Martin, NRC Regional Administrator.

' 4' A. Bournia, NRC Project Manager

,' P. H. Harrell, NRC Senior Resident Inspector -

INP0' Records Center American Nuclear Insurers Vo ,,

1l

' 6

n 90070$$h I$

7 4 s1241

.gDR anpioymengt,ngiopr:ortunity i( i i

o ,

NR f 0940 385 - U.S. NUCLE A2 6 84 ULJ.TDY ConsMIS$10N - APFT.OVtD oms NO. 3160 0104

• } #

EXPlRt$ 4/30/92

• fN i 140N EC 0 7 1 ETF60 W0RS P W A .'O

, UCENSEE EVENT REPORT (LER) gMM4N4,R40,A,R,ogtgi4uaTg TH,t g <

O?"tAPa" Won"an"l#E?C?"aca'k M'Ci OF MANAGEMENT AND BUDGET, WASHINGTON, DC 206031 8 ACILITV NAAff Hi . DOCKET NUMSER {3) PAGE G3 Fort Calhoun Station Unit No. 1 o ls l o l o l o 121815 1 loFl013 TITLE ter Unplanned Attempted Start of Emergency Diesel Generator fiftNT DAtt (El LIR NuesstR f61 REPORT DATE 171 OTHER F ACILITit$ INVOLVED tel MONT H DAY YlAR YEAR l at AL MONTM QAY \ TAR F ACokITV Naval DQCKE T NUMBERtBI l

[

N 015101010 1 I l

- ~

-d3 2l7 90 9l0 0l 1l0 0 l1 0l7 0l 3 9l0 o1 5 1 0 toici l i TMit REPORT IS SUOMITTED PURSUANT TO THE RhouantMENTS Op 10 CF R $ (Caece ea. er more et an. fonew'aff HH OPE R ATING

"**"' 5 m armi n=m X anmuHe niini l R

20 405teH1H4 to asteltil . to.731sH2Hvl 73.714el l n.1 0,0,0 . . .iHi H. axe, muman c g,3;g,g,,,,

l 4 20.400t.H1Hed 90.nteH2Hu 90.73teH2 HoulH A) JssAJ l 4

M 406teH1Hiel 60.73teH2H4 90.73talt2HveNHS) ]

20.40steH1 Het to.73teH2Him to 73teH2Han )

LICEN$tt CONTACT POR TMis LER liti l gAyg TE LEPHONE NUMSIR ARE A CODE Doug S. Molzer, Shift Technical Advisor 4021 1 513 131-i6 i 8 1914 COMPLETE ONS LINE POR E ACM COe4PONENT F AILURE OSSCRietD IN THIS REPORT 413i "A #0' " ' A "T CAVSE SY ST E M COMPONE NT N[0 PR CAvst Sy3TE M COMPONtNT M%AC O PR It '

l I i 1 1 I I I I I I l l I I I I I I I I I I I I I I I i Su,PttMENTAt REPORT txncuo nM MONTH oAv vtAR  !

'E'~

O vu <>< r., e.n.. uurcuo suomss>ON ours T} NO , l l Auf R Ac, <L-, ,. , a s e . P . .., r. . ,,. e ,, ..n , n .,

On March 27, 1990, at 1428, an unplanned attempted start of Emergency Diesel Generator D-1 occurred while the plant was in refueling shutdown. Operations personnel were performing an electrical checklist as part of )ost-maintenance testing prior to returning the diesel generator to service. T1e diesel -

attem)ted to start when the mode selector switch was taken to " Emergency Stand)y", per the procedure, and the start circuitry sensed a low voltage on a '

associated non-vital bus. The non-vital bus had been tagged out and de-energized for scheduled maintenance. The diesel failed to start due to low air pressure in the diesel air start system, which had not yet been completely pressurized.

An unplanned start of an emergency diesel generator is considered an actuation of a Emergency Safeguards Feature. The unsuccessful start in this event was considered to meet the reportability criteria. A four-hour notification to i the NRC was made at 1632, in accordance with 10 CFR 50.72(b)(2)(ii).

l l- Corrective actions included changes to the operating instructions to provide I l

additional guidance prior to realigning the diesel for nc,rmal operation or testing. The revision included a list of the auto-start signals that will initiate a diesel start. As an interim measure, appropriate caution tags were placed on the mode selector switches.

N C 7orm att (44$

toras sena u tructemaavtAvoRv consesseseoN ,,, -j

'4 EKPlit5 4/30192

• LICENSEE EVENT REPORT (LER)' f,Un^4'A *yM/cGo!'Mai',/%eggty ,w,v,w ;aig

,n TEXT CONTINUATION C 'o'"4"4'3,1Snn"cias'.MUC#,'!R?,".'f,$$fi P A E RWO RE UC ION ROJ 3 0 i IC r OF MANAGEMtNT AND 9000tT.WASHINQTDN, DC 20603.

FACitlTY ,sAaSt tu DOCRif NUGSER (36 klR NURAS$R 14) PAGE (Si VEAR

U' {n' b

$,8,y,*

g Fort Calhoun Station Unit No. 1 o ls j o j o j o l 2l 815 9l 0 -

0l1l0 -

0l1 0l2 0F 0 l3 ftXT f# passe ausse e soewegal asse aduissaar #AC #wiss Mail 171 L On March 27, 1990, Fort Calhoun Station Unit No. I was in a refueling outage (Mode'5). The 4160V Bus 1A1 was de-energized and tagged out for scheduled Emergency Diesel Generator D-1 had also been out of service for maintenance.

maintenance. The maintenance on D-1 had been completed and work was in-progress to return the system to service. Surveillance test lH-ST-DG-0001 was

the procedure controlling the inspection and testing of D-1. The test l required that D-1 be started following inspection. In preparation for starting the diesel, operations personnel were performing procedure 01-DG-1, >

Normal Operation Diesel' Generator No. 1". Operations personnel started the compressors for the diesel starting air system as required by 01-DG-1. The

procedure also required that checklists DG-1-CL-A through E be completed. In L checklist DG-1-CL-E, " Normal Operation Electrical Checklist No. 1 Diesel L Generator" an operator is required to place the 43-1/01 Diesel Mode Selector L Switch in the " Emergency Standby" position.

At 1428, Diesel Generator D-1 attempted to auto-start when a control room operator turned the diesel mode selector switch to the " Emergency Standby" position from the "Off Auto" position. The diesel failed to start because of low air pressure in the diesel air start system. The compressors for the starting air system did not have sufficient time to build up system pressure due to being placed in service only a short time earlier. The control room operator performing the switch lineup realized that the diesel was attempting to start and repositioned the diesel mode selector switch back to "Off Auto",

reset the diesel auto start lockout relays and depressed the diesel stop pushbuttons. 4 Investigation following the incident revealed that when the 43-1/01 Diesel Mode Selector Switch was placed in the " Emergency Standby" position, the diesel generator idle start circuitry sensed a low voltage on the associated non-vital 4160V bus IA1. As designed, the undervoltage condition on bus 1A1 tripped the diesel auto start lockout relays (86A/D1 and 86B/01) and initiated an idle start of the diesel, when the mode selector switch was placed in the

" Emergency Standby" position.

Immediately following the incident the Shift Supervisor placed a caution tag on the mode selector switch with instruction that the switch remain in the "Off Auto" position. This was to ensure that another operating crew did not reposition the switch while the diesel auto-start signal was present.

An unplanned start of an emergency diesel generator is an actuation of a Emergency Safeguards Feature. A conservative interpretation was made that this event met the reportability criteria, even though the diesel was out of service and not required to be operable. It did not actually start, and would not have performed its safety function. The NRC Resident Inspector was notified and a four-hour notification to the NRC was made at 1632, in L

accordancewith10CFR50.72(b)(2)(ii). This LER is submitted pursuant to 10 CFR50.73(a)(2)(iv).

i tKC Form assA (649)

n POnteSetA U 8. WWCL4A7. Ai1UGTORY Cohne60560N ,

, p , ;', e xpi::.ts etsow -

LICENSEE EVENT REPORT (LER) ',"#W,%',$fREMM's fo*i'n' .oC f7.7 ig"JR'!

S

. TEXT CONTINUATlON * #,'n'o',",!"Mf,?d Mf"* ",'C04#

',".' $Nf!

PAPE RWO RE itON J l'3 60 IC OF MANAGEMsNT AND $UDGET, WASHINGTON.DC 70603 9ACILITV NAMI HD DOCKET NUsetR 12) - Lim NUMeth Mi PAOS Q1 "aa -" t=. t'JJ.7 Fort Calhoun Station Unit No. -1 o ls jo j o Io l 2l8 l 5 9l0 -

01110 -

Q1 Q3 oF 0l 3 rirrin - . . ,= - o ,amm on The safety significance associated with this event was minimal. At the time 1 oftheeventtheplantwasinrefuelingshutdown(Mode 5)andallfuelhad been removed from the reactor. In this mode and plant condition the diesel 1 generators are not required to be operable to be in compliance with  !

Technical Specifications. At the time of the event, plant loads were supplied from 161KV off-site power, and 345KV off-site power was available as a backup power supply if needed. Diesel generator D-2 was operable and available for use. Based on the condition and operating mode of the plant during this event, it can be concluded that nuclear safety was not adversely affected.

The primary cause of this event was insufficient guidance in 01-DG-1. The procedure failed to provide instructions for the operator to ensure that no l auto-start signals were 3 resent prior to-performing realignment for normal u o>eration or' testing. T1e procedure also failed to caution the operator I t1at starting air pressure must be adequate before placing the mode switch in " Auto". The same deficiencies existed in the corresponding 3rocedure (01-DG-2)forDieselGeneratorD-2. A contributing cause was t1e failure of operations personnel to recognize existing plant conditions and their effect on-the diesel. auto-start circuitry.

The following corrective actions are associated with this event:

(1) Operating Instructions 01-DG-1 and 01-DG-2 have been revised to include l a precaution statement for the operator to ensure a diesel auto-start signal is not present before realigning the diesel for normal operation or testing. The revision includes a list of the auto-start signals that will initiate a diesel start. A precaution has been added to ensure the operator verifies that starting air pressure is adequate prior to placing the mode selector switch in " Emergency Standby".

(2) Surveillance Test MM-ST-DG-0001 has been revised to include a step to ensure that applicable sections of 01-DG-1 and 01-DG-2 are performed prior to starting the affected diesels.

(3) As an interim measure, caution tags were put on the mode selector i switches as reminders to verify conditions which initiate an auto-start of the emergency diesel generators did not exist prior to moving the switches from "Off-Auto" position. These caution tags have been '

cleared.

This is the fourth LER associated with an inadvertent start of a Emergency Diesel Generator at Fort Calhoun Station. The others are reported in LER's 88-07, 88-14, and 88-24.

ec, =A m l