ML20024G719

LER 91-001-00:on 910401,reactor Trip Occurred When Rod Dropped in Core.Caused by Defective Circuit Card in Rod Control Sys.Suspect Circuit Cards Replaced & Sent to Westinghouse for evaluation.W/910423 Ltr

ML20024G719
Person / Time
Site:	Farley
Issue date:	04/23/1991
From:	Dennis Morey, Woodard J ALABAMA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-001-01, LER-91-1-1, NUDOCS 9104260217
Download: ML20024G719 (4)

Text

.___________ ____ _ ___ _ _ ___

ima u,.a h 4c, r erci,

+l d l0,4't try h (, .it ' (lei l'es t) A ,y I W O" t 15 is t .'ii' (t: r 1 i,J t ,pi t l :jl ., . g3 _ d g ')

Ic<ep e. vie N: t6t d i sutt.

t

<\ltih;iril:i Powei m.

(0E7fko. .,. April 23, 1991 t c .., n a r .. . , . , , . . . . . , , ,

10 CFit 50.73 Docket No. 50-364

11. S. Nuclear llegulatory Commission ATTN: Document Control Desk dashington, D.C. 2055S Joseph H. Parley Nucleat Plant - Unit 2 Licensee Event Iteport No. LElt 91-001-00 Gentlemen Joseph H. Parley Nuclear Plant, Unit 2, Licensee Event Iteport No LElt 91-001-00 is being submitted in accordance with 10 CFh 50.73. If you have any questions, please advise.

Itespectfully submitted, h twk \

h.D.Voodard JDV/BilVa maf 8.28 Enclosure cci Mr. S. D. Ebneter Hr. G. F. Maxvell I

l' I

3 2r 9104260217 910423 DR ADOCKOS00{ge4 g

(

m., . N. . ....... ..n _,..N .,_,v,,,,,,,,,,,m.

(htiHi$ 4'3tr97 1511MA181. tuhDI N ti fi fet t>ONnt to Coul t v WTH 1 Hit LICENSEE EVENT REPORT (LER) C.~.'.C.i n . n. n o N,'i J, Ot . . iN,H e,'.fd.u'iu.',Y,"';'.i Wc'S.h.$'v o 6m,u t 2on,'i .?

a h6

%Hi0v4 & TORY F Atl6 COMMIuluh WDest tal ppCi W e bHINGTON TON #>HOJ4 01 (>[Oyet.h.6, ttdi4% AND i Of f1()

ill DF MANAbl M4 N T AND b;tOGt I _ W.fsHINQ1DN (lC 7ttbO3

.acio,,N. n, wii uu . . ui am a Joseph H. Tarley - Unit 2 o 16101010 l 31614 I lml011

,,, a is>

Dropped Control Rod Causes Reactor Trip EvlN1 DAT4164 40 R IsLae.t h 161 SIPOR T DAll 174 Of Hl h 8 ACittf all INv04VID 141

• T, *',b".'tI MONI" U"' **Lf' " "i ' DU( n n u 9i ni WONTH Dav VlAM Yl&R m' . A

~

0 16101010 1 l l

~ ~

0 l4 0l1 9 1 9 l1 0hl1 0l 0

,His ainoav ii su.. rnD eu van, vo s . Ouinioihn O, n Cf t ,c 0l 4 2l 3 9l1

. . .. . ... . .,, n n o isio io i o, i i

,,,,,,,,,,,, g

• • l

• n== n o., se ni.ia n,,, n inu 4 _

n e.num so wi.nu u n.nin.i n tu.i no, 1 n io a =Nin un u n.nsi w n.nsnoi _ g,Hiay=7;,;al;;*u,, , , , ,

n m. mum u n.nsn.i w n..iaii. nu w a m. inn i u n.nin.i w n.nin. noi n =Nm n.i u ni. nan,m a n,.nin.i LICLNllt CONT ACT 90M THi$ Llfi till No . via hon Nuveia h4&(OOO D. N. Morey, Cencral Manager - Nucicar Plant 2, 0 l 5 8,9, 9; i 4 1 5 g (

C(merktit DNt teht 90m t ACH COMPON61st 8 Altunt 085C01:540 ph TH!l hlPOnt n$i I "

CAUSI Svlttu Cow >0NtNT 'g $C

"'9 o ,','; C a ult tytttu COM*0NINT $E "I,'c ,',"g I B

$^ 57XX 1 I Vi 120 1 Y i , , , i i i l l I I I I I I I I I I I 1 SUPPLEMENT AL pipont t aP6CitD ltei won 1H Day vtan tvDW & lion 4th 440, .emon,e i kHCTRO Sve.,lS$90k OA f ti kQ l l l c.. r . .C , u ,,,,,, > m . . . .,,, . ., ,. n ,,. . ,, . . . . , n e i At 1055 on 4-1-91, while operating at approximately 100 percent power, a reactor trip occurred when rod H-10 dropped into the core. The teactor trip occurred due to a high negative flux rate as detected by the power range nuclear detectors.

The operator was performing FNP-2-STP-5.0 (Full Length Control Rod Operability Test). When control rod group C vas tested, rod H-10 dropped into the core.

This event was caused by defective circui t cacd(s) in the rod control system.

The suspect cards vere replaced and the i. nit returned to power operation at 1208 on 4-09-91.

nC e m. i...I

p.. -

u . ~un . mutm.,, u .mo.,

. ....n nm LICENSEE EVENT REPORT (LER) "'s',','?,n*@,MJ'AM'.,"!4*W ,*a'."4 TEXT CONTINUATlON iT,f i'jll!'o'n0L*f0'.M"'"','!,'M".' 302 i

i O.r%~',.'A'm, o a oi ~

.*~aM.un.a'M..M,~YWJ'T2 n m c.n* now Midi

...LILif V h*MS Hi DUCEt t Nuuti. Lia Llh hued 8th t$i P.0L Ili

'saa " MW." 2htm Farley Nuclear Plant - Unit 2 o p, n ; n o g : 64 00 1 00 0 2 g,

}l _ _

0l 3 nxt a m . w m aiu ,, n,,

Plant and System Identification Vestinghouse - Pressurized Vater Keactor Energy Industry Identification System codes are identilied in the text as (XX).

Summary of Event At 1055 on 4-1-91, while operating at approximately 100 percent power, a reactor trip occurred when rod 11-10 dropped into the core. The reactor trip occurred due to a high negative flux rate as detected by the power range nuclear detectors. The operator was performing FNP-2-STP-S.O (Full Length Control Rod Operability Test). When control tod group C vas tested, rod 11-10 dropped into the core.

Description of Event On 4-1-91, the unit was operating at approximately 100 percent power and surveillance test procedure FNP-2-STP-5.0 (AA) vas being performed. At 1055, vnen the operator was moving the control bank C rods he sav rod 11-10 drop into the core. A high negative flux rate reactot trip vas generated by the power range nuclear detectors IIG). Following the trip, the operators implemented FNP-2-EEP-0 (Reactor Trio or Safety Injection) and FNP-2-ESP-0.1 (Reactor Trip Response),

ensuring that the unit was safely in Mode 3. The unit was maintained in a stable condition.

An intensive investigation was performed to determine the cause of the dropped rod. The investigation included both APCo and Vestinghouse personnel. All fuses in the rod control cabinets vere checked. Continuity checks were performed for the affected rod bank on cables, coils and connections inside and outside of containment. The reactor missile shield was removed to allow the rod control cable connectors on the reactor head to be examined. A Vestinghouse rod control system field service engineer came to FNP to assist in the troubleshooting. The investigation continued with no problems noted until 4-7-91.

On 4-7-91, while withdrawing bank C rods, rod F-8 did not indicate outvard motion.

Additional troubleshooting continued with no deficiencies noted. Due to the intermittent nature of the problem, a test was developed utilizing recorders.

Recorders were connected to monitor appropriate rod control electronic signals continuously during the test. With the recorders in operation, the affected rod bank vas again cycled. During the first three rod bank withdraval and insertion cycles, no abnormalities were noted with the rod movement or the recorded signals.

On withdrawal during the fourth cycle, however, two rods in bank C dropped partially into the core. The intermittent problem vas visible on the recorders.

Evaluation of the recorder traces shoved this group of rods received incorrect current orders for the stationary gripper coils. Three circuit cards that could cause this condition vere replaced. Bank C rods were tested after this card replacement. No further problems were noted.

CC 7eem 3e Iem

C ,OMM pena ut huCLEA,ialoukatomtCourdib640h e

8 telfit t d'30%)

LICENSEE EVENT REPORT (LER) y,"' ',' '?,c,'#'sRJ %,l' AM 't ,";jf *, *Jt' , 1,',".'.y TEXT CONTINUAT10N

?;**,,'n','i ,,"'n','!O7L*f 0FA'"',T'," 'N,"l 0',n'.t f!

@'!A,'A"J1?"##Af##,'.'v;t Of MAN AGt M6 h1 AND DubGit ASH.NG10h.

t

(>C

• ah03;!'!di'4#" 'T Dalt41T V hAME tH Outa n t huMtt a til Oh pl# ten PA06 W

"*a "t?,;." p'A*,W rarley Nuclear Plant - Unit 2 o p ge jo jol3g6 4 ]1 0l 0j l __ O g 0 0 3 or 0l3 tui m - . e wc s .nm Cause of Event This event was caused by defective circuit card (s) in the tod control system.

Reportability Analysis and Safety Assessment This event is reportable because of the actuation of the reactor protection system.

After the trip, the following safety systems operated as designed main feedvater was isolated by automatic closure of the flow control valves and bypass valves, auxiliary feedvater pumps started automatically and provided flov to the steam generators, and pressurizer heaters and spray valves operated automatically as requested to maintain system pressure. The source range nuclear detectors energized automatically.

There vas no etfeet on the health and safety of the public.

Corrective Action The suspect circuit cards were replaced and sent to Vestinghouse for evaluation.

Additional Information The unit was returned to power operation at 1208 on 4-9-91.

Description Part Number Location firing Circuit Spin No. CPELC02 6050D12G01 2 AC Power Cabinet I/O Alarm Circuit Amplifier - A804 3359C65G01 Logic Cabinet Slave Cycler Decoder - A401 3359C62G02 Logic Cabinet This event vould not have been more severe if it had occurred under different operating conditions.

i NRC Penn 3e4A (649)

. _ _ _ . . . _ . _ . . . . _ -