05000457/LER-1990-010

LER 90-010-00:on 900609,reactor Trip Occurred During Plant Startup from Low Steam Generator Water Level.Caused by Malfunctioning Bypass Feedwater Regulating Valve.Operator Training provided.W/900706 Ltr

ML20055D955
Person / Time
Site:	Braidwood
Issue date:	07/03/1990
From:	Ibrahim D, Querio R COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BW-90-0694, BW-90-694, LER-90-010-02, LER-90-10-2, NUDOCS 9007100186
Download: ML20055D955 (4)

LER-2090-010,

Event date:
Report date:
4572090010R00 - NRC Website

text

_ _ _ _ __ _ _ .__

/ \ Commonweshh Edison  !

I4.'* .

i

/ Braldwood Nuclear Pow:r Stati;n

(

) Route #1. Box 84

\

' ~ '

'/ Braceville, Illinois 60407 ,

L/ Telephone 815/458 2801 i

'l July 6,1990 3 BW/90-0694 1

i i

\

U. S. Nuclear Regulatory Commission Document Control Desk 1 Washington, D.C. 20555 1

Dear Sir:

The enclosed Licensee Event Report from Braldwood Generating Station is being transmitted to you in accordance with the requirements of '

10CFR50.73(a)(2)(lv) which requires a 30-day written report.

This report is number 90-010-00; Docket No. 50-457.

Very truly yours, L r R. E. Querlo l Station Manager -

i Braidwood Nuclear Station REQ /JDW/sjs (7126z) r l;

Enclosure:

Licensee Event Report No. 90-010-00 cc: NRC Region !!! Administrator i NRC Resident inspector l: INPO Record Center <

CECO Distribution List I

/

9007100186 900703 (

t i PDR ADOCK0500g7 (

s

F <

> u CtN$tt tvtNt at>0kt (tta)

FHv_llet.LIL j U Facility scene (1) Decist Ndaer (2) . fame _fil  ;

,gtgMyggd 2 el 11 Al el Al 41 11 7 1l3 _) _

! ilde (4) Reacter Trip During Plant $ tart tip Free Low $ teen Ger.arator Water level due to a Halfunctienlog Dypass feedwater Repulettog valve.

,,,Lynet Date ($1 LER M gr_(61 RangrL.pgla_f71 Other ratilities inyghed_ (t)

Month Day Year Year /// Sequential /// Revision Month Day Year latility Namag_ )niti Negr.{s t fff fff

/// N,mbe r /// Nabar NDH 01 !! ill 0L01. l l

~ ~

_0.1_1 _01L _930_ 21L 0_l 1 10 0 La 017- _01L 910 Q L E L O L tL L 01 1 1 THl$ kiPORT 15 $UBMITTED PUR$UANT TO THE R(QUIREMENT$ OF 10CFR A""0 1 (Check one er more of the f ellowinal (11)

. 20.402(b) , 20.405(c) _A., 10.73(a)(2)(iv) __,,, 73.71(b)

P0dCR 20.405(a)(1)(1) ___ 50.36(c)(1) 50.73(a)(2)(v) . _ , 73.71(c)

, LEVEL _ 20.40$ta)(1)(ii) $0.36(c)(2) _., 50.73(a)(2)(vii) Other ($pecify z

(101 0l1l  ?- 20.405(a)(1)(iii) , 50.73(a)(2)(t) _ 50.73(a)(2)(vi44)(A) th Abstract

/ / / / / / / / / /,/ /,/,/ /,/ /,/ / / /,/,/, /,/ / _,_ 20.40$(a)(1)(iv) _ 50.73(a)(PHii) 50.73(a)(2)(viii)(B) t.elo, and in

/// / / / / //}//' f}//'/ /}/ / //}/T/,}///

/ _,_ 20. 405 ( a ) ( 1 ) ( v ) ,,,_ 50.73(a)(2)(lii) 50.73(a)(2)(s) feet)

L1QM[.jpfiLAU_ [QP. THL) 1LL(12) flee, TtLtPH0ti.jMgG ARLA CODC

____tave Ibrahie Tegh $1gif Eno. Est. 2402 B11l$ 41$1fl.I1181D1 COMPLETE ONE LINE FOR EACH COMPONEN .._[AllyRL DL}RI$1DJf(,ItilLJLLf131 (13)

CAU$t $Y$fth COMPONCNT MO$JFAC. REPORTABLt CAU$t $Y$fCM COMPONENT MAntJFAC. PtP0RfABLE TURER ..IO NPRI'$ __ IVIER 70_)(Pa0$

_x .1 1 e Il Cl vi rl 11 31 0 -- Yan i I I_ l - - - _,_L L ,.L_ _ ._

I I l l l l l l l l 1 l I I _m SUpPLEPENTAL REPOR1 EXPEC1ED (14) ,,,

[vpected ne . rat.Lyaar

$ubmission

~ I

~

Date (15) l I Ilti (I f veWaJ.ltit.llPLLTJp._}(ttil}11QN Daf f ) ) l Hn . ,_

l 1 _l 1 l ABSTRAtt (Limit to 1400 spaces, i.e. approsimately fif teen single-space typewritten lines) ( if,)

A unit start up was in progress. Feedwater (FW) flow was being controlled in automatic by the Bypass FW R:pulating valves (BFRV). $teamline header pressure was being tontrolled in automatic by the $ lear Dumps. At 0030 on Sune 9,1990 a Reactor Operator (RO), who was monitoring the rw panel, observed that indicated level on the 2B Steam Generator ($G) had decreased to 35%. This was below the set point of 501.. The RO placed the co. troller in manual and increased the output to raise $G 1evel. 2B $G 1evel continued to decrease froe the

'shrid' etfeet of the cold FW. The Supervisor ($RO) directed the RO who was monitoring Reactor Control panel, to trithdra. cetrel rods to increase temperature and *$well" Le level. $G 1evel increased f roe an initisi value of 2fl% to 24%. .st 0039 the ef fects of the increase' heat input caused stearline pressure to increase which causid the $ tear Dump Valves to cycle. This created a level perturbation which caused the level in the 2B $G to decrease below the Reactor Trip 5et peint of 171 anf a Reactor trip occurred. The cause of the event was a malfunctioning BFFV which would stich during operation in the lower third of valve travel. The valve pac 6ing was 1:es;ned and valve travel was smooth and acceptable. Operator training will be provided, previous corrective actions are tot applicat.le.  ;

i i

3044m(070290)2 I

i

)

> l

)

UIttlRLLYLELitpostt f ttai ttALC0tallul10ff F1titietLt. ,

tAcn tn aint (1) 00att speta (2$ tra tu ott 16i pestili Year H Sequential ///

fj Revisten I N/j/ Ndar d/ leda r_ q

,gmWpd 2 e i s i e i e I e I al sl 7 eig . eI1ig .

_e i e _gjLgt h, TLKt Energy Industry Identification Systes (till) codes tre identitled in the tent as (KK) 1

'A. tier.t Condittens Prior to tient:

tinitt Breldwood 2: Event Date: June 9. 1990: Event time: 0039; Mode! ? . I'c.er Operetten; b power: 15t; RC$ (ABe) Temperature / pressure: NOT/N0p; B. Description of twent:

I i

A unit start up was in progress in accordante with approved procedures. Rtatter power was at $1. and being increased to approelmately 15% in preparations fot Main Turbine start up, f ee=ater (rW) ($J) flo was being .

controlled in automatic by the Bypass fW Regulating Valves (BTRV). $ttamiine Header l'ressure ($B) was being l c;ntrolled in autoastic at 1092 psig by the $ team Dumps.

t At 0030 on June 9,1990 the Nuclear $tation Operator (N$0) (Licensed Reactor Operator) who was manitoring the FW panel, observed that indicated level on the 2B $tese Generator ($G) (09) had detressed to 35% narrow range ,

scale. This was significantly below the normal control set point of $0%. The N$0 observed that the output from the controller for the 2B $fRV indicated C. The N$0 placed the controller in manual and increased the entro11er output in an attempt to raise SG 1evel. 2B SG 1evel indicated 32% at this time and continued to decrease free the 'shrint* effect of the cold TW addition.

The Shif t Engineer ($t) (Licensed Senior Reactor Opetetor) directed the N$0 who was monitoring Reetter Control Panel, to withdraw control rods in an ef fort to increase temperature and *$well* the level in the

$Gs. The N30 withdrew the control rods and observed the resultant increases in RC$ temperature and $G 1evel. 4

$G 1evel increased free an initial value of 20% to 241. and reactor pc.er mas indicating 111..

At 0039 the effects of the increased heat input to the $Gs caused steamline pre;sure to increase. This  !

caused the $ tram Dump valves, which were contro11tng in auto, to cycle. This created a level perturbation on the $G 1esel contro'. systee which caused the level in the 2B $G to decrease *oelo= the reactor Trip $et point of 17% and a Reactor trip occurred. The N$0s verified all avtomatic actions. All systems functioted as de signed. Stable conditions were immediately established.

The appropriate NRC notification via the (N$ phone systee was made at 0108 pursuant to 10CFR$0.72(b)(2)(ii).

This event is being reported pursuant to 10CFeh0.73(a)(2)(iv) . any event or condition that resulted in manual or automatic actuation of any [ngineered $t6fety festure, including the peetter protection $ystem, C. Cause of tvent:

i The root cause of this event was a malfunctioning valve. The malfunction of the El BrRV created a low level condition in the 2B $G. During the action to recover level, the addition of the cold FW combined with the cycling of the Steam Deps created a tendition that caused the Indicated level in the 2D $G to decrease below the Reactor trip set point. 1he sequence of events initiated by the malfunction of the 2B BFRV caused the cy:nt.

i 3044e(070290)3

_.___o

r a

f,' .

utDtut typ1 atPott tttal ttat enN13411oM Lata.lar_LL FaeltttY swet til t* *tt *>otn (2) Ltn mMett to Psaa. t 31 -,

Year //' Sequential // RevistDn fff aLme.ar ff "r

. Arate...d 2 e 1 i 1 e i e i e I di il 7 slt . eI1ie . _c I e

-- als or e_Is itRt Energy Industry identiff tation Systes (t!!$) tedes are identified in the tomt as (KK)

D. Safety Analysis:

This event had no effect on the safety of the plant or the public. All systee's operated as designed.

A:siliary Fetdwater attuated at.) restored $G tevels as designed.

Under the worst case condition of a low $G 1evel occurring with the Unit operettop at 1001. Power there would still be no effett. The Engineered Safety feature Attuation System (t$F) would initiate a Reatter Trip, turbine Trip and Auriliary f eed= ster Actuation free either of the two redundant Trains of ($f both of which were operable and evaliable for this event.

L. Correttive Actions:

f reuble shooting was i.erfumed on both the instrument control loop for the 2B Bf RV arid the valve itself.

2F WOS20A. All portions of the control loop tested out satisf actorily. The valve emperiented sticking and jer6y motion when operated in the lower third of valve travel. The valve packing was loosened and valve travel was smooth and acceptable during additional testing. The valve has performed acceptably at maintaining $G level in automatic since making the pocling adjustment.

This event will be included it, the titensed Drerator Requalification Training program as part of the continuing ef fort to share experiente on level control of the Model D-5 $Gs during low power operation, this action will be tracked to completion by action itee 457-000-90-02601.

F, provious occurrences:

fl.ere have been previous occurrentes of t$F actuations as a result of level perturbations occurring on the Unit 2 Model 0-$ Steam Generators during low power opers'. tons. The corrective actions were implemented addressing both root and contributing causes, previous torrective actions are not applicable to this event.

G. Component Islivre Data:

!$4(1U1411ERI N98tElitEt Min. pari A fisher Controls Co. tevel Control valve 667-55-79 i

I l l 3044m(070290)4

)

l