ML20043G074

LER 90-011-00:on 900514,feedwater Isolation Signal & Main Turbine Trip Signal Occurred When Steam Generator B Reached hi-hi Level Setpoint & Generator C Reached lo-lo Setpoint. Caused by Power Oscillations.Procedure revised.W/900613 Ltr

ML20043G074
Person / Time
Site:	Wolf Creek
Issue date:	06/13/1990
From:	Mike Williams, Withers B WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-011, LER-90-11, WM-90-0107, WM-90-107, NUDOCS 9006190024
Download: ML20043G074 (4)

Text

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

I

. i

$ . I

~

W44.F CREEK NUCLEAR OPERATING CORPORATION r

es,10. ww.s I w eas -

Opust Basseuse CIheer  !

June 13,1990 WM 90-0107 U. S. Nuclear Regulatory Comunission  ;

' ATTN Document Control Desk Hall Station P1-137 ,

Washington, D. C. 2055$

Subject:

Docket No. 50-482: Licensee Event Report 90-011 00 t

Gentlemen:

The attached Licensee Event Report (LER) is being submitted pursuant to i 10 CFR 50.73 (a) (2) (iv) concerning an Engineered Safety Features l Actuation.  ;

Very truly yours.  ;

k e

1 -

_J Bart D. Withers President and Chief Executive Officer BDW/aem Attachment cca R. D. Martin (NRC), w/a f D. V. Pickett (NRC), w/a M. E. Skow (NRC), w/a J. S. Wiebe (NRC), w/a i )

l l

+00619a,;4 .. - RO. Son 411/ Surimgeon, KS 6663s / Phone: (316) 364 8831

.f, AbOC p. [k ,)','fl,h An Equal opporturey Employer utevET ,i m l

L asac p . See u s Lucitua c tro6 stony conswission t' ."'#

• A7enovto owe no sinopipe

. LICENSEE EVENT REPORT (LER) ' ' m"' 8 ' 8 '

l

. Aciut, =.mt n, oocair =v u nini ,aa a l

Wolf Creek Generating Station 015 l 010 l 0141812 1 !orl 013 )

Heactor Trip Signal and Engineered Satety Features Actuations During Turbine l Overmeed Testina caused By Dif ficulty in Steam Generator Level Control l tVtWf oaf t 166 Lim hpMeth 561 REPohi DAf t I7s DTHth f Acittfitt LNyoLYto iti l MDNTM DAv YE A05 v5Ah ['N L* 6 "'fM UD%TH oav t l ali 8Abbit' h&Vl4 DOC klT NuYDt htli

'~""

l l

o 16101010 1 l l

Ol s 11 4 9 0 d0 3 i. u ,o , . .v 0l1l ] 0l 0 0l6 1 l3 9l0 01 6 1010 1 0 11 l

, ,,,,,,,,,,, it1E o ,vos.~, ,o 1 i = ovin t.18 o, i. c . , ,c . ,,, .. ., , . ,.. . ,, n i. ,

"0D ' '

l 1 to 402w to sostei X to73 Han i 's tit.i l

h 70 406aaHt Hil H 36teHt t M f atelt,Hel f 3 titel l

no, i i n .in n.,

..H.,

,3.H,H.i.,

_ g,=,=,,,, .. g,z,,

l 20 406deHiHi4H SO 73teitalf 4 60 73teH2)ivisHIAl J6&AJ

1. 0 eO6tell1Hi.) 60.736a H2 H.i M 93eeH2Hvihh81 l 29 4044 ell 1 Het 60 931sH3 Hail W 731sH2Han tactN$tt cont ACT DDR YMit Lt m H31 NAV4 tittPMohl 96vv9t h aht a CDDI l Merlin G. Williams Manager Plant Support 3 [1 i 6 31 614;- l 8 l8 l3 il I cou,6 tit out L.~t eon saca co ou=v eaitual otscaisto i= tuis I teon, n3i .

I 1 l cAust svitiv cowosest *^%'C 17",',',!!' cavit avsviv coveos#85 *d 'C "',7",',', jj ' l 1

I 1 I i i i I i i 1 i 1 i i t I l l l i I I i i i l i I I i i SUPPLEMENT AL REPORT tmPicTto 1941 McN1H Dat itaR sv8vissioN l 7 so

-] vt <,,,,, ,-,. ,uscrec sv,wssio. cA rne l i i a ui . .c, ,4 ,-, ,, . . ... . . ... , ,, . . . .. .-, o , n .

1 Ch May 14,1990, at 2136 CDr, during performance of the Main Turbine l overspesd trip test, a Feedwater Isolation Signa) (FWIS) and Main 'Ibrbine trip signal occurred when Steam Generator 'B' reached the high-high level setpoint. Shortly thereafter, a Reactor trip and Auxiliary Feedwater Actuation Signal (AFAS), and Steam Generator Blowdown and sanple Isolation l Signal (SGBSIS) occurred when Steam Generator 'C' reached the low-luw level setpoint. All Engineered Safety Features and Reactor Protection System ,

equipment responded properly to the actuation signals.

1 Earlier in the day on May 14, 1990, feedwater preheating using main steam had been reoved frcm service. When the Main Turbine was taken offline in accordance with the overspeed trip test, feedwater heating using extraction steam was lost. As a result of the colder feedwater being supplied to the steam generators, significant level oscillations occurred. Although the-Control Rocan Operators took the apsvslate actions to dampen these oscillations, thel.r efforts were unsuccessful in preventing the high-high and low-low level conditions.

'Ihe svwdure for performing the overspeed trip test has been revioed to require feedwater heating to be inservice prior to conducting the test. 'Ihe revised test was ocmpleted successfully en May 16, 1990 at 0002 CDP.

l-

= ~c e ... m I .. u

.;,.. . o. toc ..omion, c- o.

UCENSEE EVENT REPORT (LER)  !,%,^'.',%'#"Mi%.",'!?n'n/%Cf'l*Jl ."s".'.4 TEXT CONTINUATION F#4'fAWu'ZU hUl'all'c7','l# '"/ "Me"f!

o.i"t.",'A"Mi"."#AS,A',!;eniucro ua%.oiwiwi awo Duocat nas

?'J .oc M

1. 1. ,oen?.la

. AC,Ut v ha.84 (it DoCEli Nut. Din (,, 4th NUh.$lR ($l PA06 (31 vs a " ti';P." -

W.T; Wolf Creek Generating Station 0 IB l0 l o l 0 l 4l 8l 2 9l0 -

0l1l1 -

0l0 0 l2 oF 0 l3 em. -. ,*,, - wc, - .m.

IMm3IETICEI On May 14,1990, at 2136 CDP, during the performance of the Main Turbine (TA-MB) overspeed trip test, a FeeKiwater Isolation Signal (FWIS) and Main

'Atrbine trip signal occurred when Steam Generator 'B' (AB-SG) reached the high-high level setpoint of 78 percent. Shortly thereafter, a Reactor trip Auxiliary Feedwater Actuation Signal (AFAS) and Steam Generator Blowdown and Sanple Isolatim Signal (SGBSIS) occurred when Steam Generator 'C' reached .

the low-low level setpoint of 23.5 percent. All Engineered Safety Futures I (ESP) and Reactor Protectim Systern (RPS) equipnent responded properly to the actuation signals. 'Ihese events are being reported pursuant to 10 CPR 50.73(a)(2)(iv) concerning unplanned actuations of ESF and RPS equipnent.

EEKRIPTIGE W EMtr Prior to these events, the unit was operating in Mode 1, Power Operations, at 18 percent reactor power. '1he Main Generator [hGEN) was synchronized to the grid with a load of approximately 128 Megawatts electrical. Steam Generator levels were being controlled by the Main Feedwater Control Valve Bypass Valves (SJ-V), which were in autmatic. Surveillance testing was l

being conducted in accordance with surveillance s ucxmiure S W AC-007,

" Turbine Overspeed Trip ' Dest".

At 2043 CDP, the steam dunps were placed in the steam pressure mode to l maintain reactor power at approximately 8 percent while the testing was in l su, ass. Per the instructions in the surveillance test s ucedure, Main l Turbine load was reduced to approximately 47 Megawatts electrical and the ,

Main Generator output breakers were opened at 2123 CDr. Fbliowing the trip 1 of the Main Turbine, feedflow/steamflow mismatches and steam generator level t oscillations occurred in all steam generators. h Control Room operators took manual control of the steam dunps arxl the Main Feedwater Control Valve Bypass Valves in an effort to danpen the oscillations. However, these efforts were unsuccessful in preventing level in Steam Generator 'B' from reaching the high-high level setpoint of 78 percent, initiating a Main i

Turbine trip signal and a FWIS at 2136 CDP. h steam generator level l

oscillations continued, and at 2137 CDT, water level in Steam Generator 'C' reached the low-low level utpoint of 23.5 percent, and initiated a Reactor

( trip signal, AFAS, and SGBSIS. All ESF and RPS equipnent responded properly to these signals.

l After verification that all equipnent had functioned properly, the motor-driven Startup Main Feedwater Punp [SJ-P) was started and the Auxiliary Feedwater Punps (BA-P) were secured at 0016 CUT on May 15, 1990. A reactor restart began at 0445 CDr.

L NRC .ses.i 306A 4891

. c*t0At:30sA W4 RUCL61R LitutA10hv 00htulation p

, littimit 4'3093

%',fE"In"o *

'!;?>"j',/%'f"',tl *J."J".'!

LlcENSEE EVENT REPORT ILER) A, TEXT CONTINUAT10N f,Us"',?,','.

,%"' ",1*M'*fd O'"j.Mlle'0,'l# " '"/

%fi.^.YOnfS"."L' ifs #~^%*lE*J'.'J's UEd?

Of MANAOLMtNT AND DVDGET,n ASHINGTON.DC 30603 f AC64tiv .sanit tu Docetti Nutetta LII tta huMeth 166 9405 (Si vlaa "tt';P. t'A*JO Wolf Creek Generating Station o l6 l0 l0 l0 l 4l 8l 2 9]O -

0l1l1 -

0l0 0l3 0F 013 1m in . t m c % maavnn KXX' CAMIB AIO CIEEEE1'IVE ACTIGt Review of this event concluded that the severe steam generator water level oscillations prior to the FWIS were a direct result of low feedwater tenperature. Previous operating experience has denonstrated that difficulty in steam generator level control while at low power levels is minimized by the use of preheated feedwater. Earlier in the day on May 14, feedwater preheating using Main Steam had been secured when turbine-driven Main

! Feedwater Punp 'A' (M-P] was placed in servloe and the notor driven Startup i

Ebedwater Punp (M-P) was secured. When the Main Turbine Generator was taken offline at 2123 CDP, feedwater heating using extraction steam was removed, and feedwater tanparature rapidly decreased fran approximately 400 degrees Fahrenheit to approximately 150 degraes Fahrenheit. %e colder feedwater contributed significantly to the effects of " shrink" and " swell"

in steam generator water level. We Control Room Operators took the L

aauur.iate actions to ocmpensate for these effacts, but their efforts were unsuccessful. In order to prevent recurrwnee of this type of event, a procedure revision to SIN AC-007 was issued on May 15, 1990, to add a requirement to ensure feedwater heating is in service as an initial condition to perform turbine overspeed trip tests. We turbine overspeed trip test was ccmpleted satisfactorily on May 16,1990, at 0002 CDP, with feedwater heating inservice.

AIDITIGEL DWGGIM'IG8 All safety systeas functioned as designed during this transient, thus preventing developnant of conditions that could have posed a threat to the valth and safety of the public.

Licensee Event Reports 90-007-00, 85-064-00 and 85-042-00 discuss previous ESF equipnant actuations in which the absence of feedwater preheating was a major causal factor. As discussed in Licensee Event Reports 85-064-00 and 85-042-00, the procedure for perfo- cing a plant startup contains instructions for maximizing feedwe se tenperature during a plant startup.

During the revisions to this proce re, the need to also revise SIN AC-007 was not foreseen.

l NRC F.em 386A (6491