ML19291C264

AO 73-19:when Closing Signal Was Applied to Breaker S1A,loss of Power Occurred at 4160-volt Ac Bus 1A Causing Trip of Various Pumps.Caused by Incorrect Setting of Current Transformer Ratio Matching Taps.Taps Set Properly

ML19291C264
Person / Time
Site:	Oyster Creek
Issue date:	09/08/1975
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
Shared Package
ML19291C260	List: ML19291C259 ML19291C264 ML19291C266 ML19291C270 ML19291C277 ML19291C282 ML19291C283
References
NUDOCS 8001230245
Download: ML19291C264 (5)

Text

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< i.a t-  ; . .:- ' c re energi:el to c . , r; p:r:e- i t. the . e. . _ . - .m c8, ut iner tranFo: m r cc .11 o be cc t . : c d c '; n l '. 2 .c : < t cocer setrint on the C ...m di r e n.nt l a; ) .u i a:ir.? r:1 : ': F ':in', i.uring thc e,tr; (Irtt r . ;cn.<J ui " Sit . . i . r "1 ne:,ner diesel <tn-ci ster wasaMu to rcst r rt after h:. 7 cnce been initictei in ~

ti.e " Fast St a rt" tvJe ao.. is un 3.ecur.' schen po.:cr was agt.in lost to me 'lo0V .'J bus,

c. c. c situs' ions are cour : cered t o b cSnor al occurrences as 6; f i ned in t he Technic:.1 F;.eci fi c;t c.r; , part",1 cph 1.15D U nilure of cne or .c r c cor;onents c: an en,qinc ered safet:.

f m ure P.. c: 1s es the feature to bc in:n . :.h of perforn:ing i t .3 intenc: . .t . ct i c r.; r n d . 15 G (c'. ra d im J:quacies in ti.e i: , l e:acat e.t i ce oJ 'roce; n 1 contrc:' such that the inadecur.cy 1 C :.u r e t the 'J Xi Ste 1J e or de Je3 0pO;nt of an unUnfC Condition in conne ction ca th the epcrotion of the plant) . Notification of this event, as required by the Technical Spec-ificat. ions , paragraph 6.6.2.a, unc node to AEC Region I, Dir-ectorate of Regulatory Operations, by telephone on Saturday, Septe:ber 8, 1973, at 10:15 a.m., and further elaborated upon personally 1:i th Mr. E. Greenran from AEC Region 1, Directorate of Her,ulat er; Operat ions , on Tuesda:, , Septenbc r 11, 1973, in the r.orning during his visit to tne site. Further, the preblem seith the ste _ up t- nr fern rs '. as tel ecapi ed t o A'iC Regi on I cn

Wy, St 1. ' : : I r , 3 :' ~ , rt 1 : 7'1 p: ., and the diffi: ult; ex9:rienecc ':ith the Di e.*1 G:'nc rr.t c rs sea s tel ecopied cn

             'i!. n ay , ' c pt er.be r 13, 1975, at 5:00 p.m.

SIlUATIO::. A plant shutdo.:n had progressed to the point tihere, witn elec-trical output at approxir:at ely 90 M c, a transfer of station loadt f rau t h e Au::ili a rf 1 : ca:s fer:. c: to the Starcup Transformers can at t er.:pt e d . Qen a closing sipia! ens applicd to the S1 A brealer, a loss of po.:e: occurred on the 1A 4160V AC bus which, c:.cag other thinc.s, caused to circulating water pumps, three re:::t er rc ei rcul cri on p'r.e , and the operatin;; condensate an 1 feet ,.at er t o: to t::p. 1.esel Generator r1 wns initiated in th. " fast S '. a r ; " : . . c , rcc- :';1cing the IC 4160V AC bus , re:,terin;; p :cr to thc : :i: i re w : J n ste: - should they ha'.c becn rc ;ui red. An ':ti c r a: 'w . r ade t a ".t e rt the 1: r.nd C Cendens ate l'c >s, but before e!':<: : .' p could be started, the react or re: wd du: '. o I c .. r :< 1 'crel. - In reconst ructing the subsc-

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3. : 01] o.:laa a . . ., the d ' 10 ' AC Lux u c r. en crr.i v .'

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2. The "]cchcut" re l :" , 3 05 A , ; ..c.  ? c: n cauc1];. , t h e G '.

L' rt .. : c r c a . eles . , Merc1 Ucn :..or F1 tras synchrcn-ined with "systen," cnd the JC br,;aher uus c1cstd.

5. Diese] Gem cater fI r.is sccurcJ. At this tine, the

                        " Trouble" al arm was ..nnuncirt ed in the Contral Roen                       ,

and an electrician uns dispatched to d::teri.dr.e the cacze.

4. An atter'pt uns nadc to start thc A Condensate Punp, but the in-rush current apparently tripped 51 A breaker, Dicsel Generator el uas not~ initiated in the "Fnst Start" node due to the ciifine "3 ockout" relay which has pretio.tsly beer actunted (the c;.use for the "Troub]e" alarn).

5. An attempt was nade to start the B or C Condensate Punps, but the in-rush current apparently tripped the 51B breakcr. Diesel Generator 1-2 was initiated in the

                        " Fast Start" mode reenergizing the 1D 4160V AC bus.

For the period of tine taken for Diesel Generator *2 to come up to speed, buildup volt age and reenergize the bus (less than 15 seconds), the station was without AC power.

6. Both the SA and SD transferrar "Icetout" relays were reset na!.ually and bct ' S1.4 and SIB breakers were closed.

7. Diesel Generator il was initiated in the " Fast Start" node when the c]cetrician reset the engine " lockout" relay.

8. Diesel Generator it2 was synchroni:cd with "systen,"

the ]D bren!;cr closed, and the Diesel Generator was secured. Upon ;;ecuring the unit, the " Trouble" alare was annunciated (apparently due to the engine " lockout" rclay being. activat ed) . The electrician was advised of the situat i on.

9. '. gain an atter.pt was cade to start the B or C Condensate l'ugs with t he sarce resu] ts as before. Ilowever, Diesel Generator i 2 failed te start.

pphj\ o 9o ag 1792 206 TJ J A Alt 4 a

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hydr '.';c cc..t ro , st; ac: t.:3 s.  : a um opmed 1 o i=sist in il. rc cc . . cy o f rer c . 2 t er J evel . i n a r. l. . . - teu b vel n .e c h t .. , rc co. . x ..a Feed. eater Contre' Syst m le'.cl 1ccoct r, was f.' : - the core, l'10" c'>c 2 . the t.c t . .. . i on ptd '.t #cr inititt _ t e Co: ,.: S;...:y Sys u und .bo:: ...ing the reactor.

12. 'ihe "SIV's ucre clos;c' by the c; _ . :or und the Isolt.t i.or Condensers were '.:c:n:.:lly in:t: . . .. o clir..inate the uc.tt -

invcntc:y loss fror the venc; i. .c provide f ar c:cc;- heat reua'.' l . C ." ' " ! - The prob]cn exne;ienced vi t' th e S . : rt'a - r: :s for':.c r b rech en SIA and SIB ucs t rnced to i.n incorrc;t s c .;ing of the cur:ent transformer ratio r".tching taps for the C p.ase differentici relay on both units. In attempting to either crrry a sizeabic load and/ or start a large load, a differential fcuh current based upon the improper tap setting was sensed, trippin; O e bus supply breckers. The problen expcrienced with the Diesel G: .erators was i d ent i fi .-d to be as a result of relay contact actraile, which is inherent in the design of the circuit (see Figure 1). iicien the unit is initiated in the " Fast Stcrt" Lode, pecer to the cr . n..- fault circuit is cut. off. Uith the unit at spec c', the 0AD rc1:- ir encroi ed closin~o e contccts in the u.g; ne " loc.:c A" circuit.. E:dcr norr.a1 cond.tior , the bc trint oil mcssure sunch ucu . b; c::sua, enabling the :M relay to be enc . p d, cptnin;; a contact 1. ...e en,ine " "Jachaut" ci rcui t . Heue'c:, inat relay cculd not a energized duc to the opened Ic.st Start Relay contcci- and com crf cntly the bearing oil pressure contacts rennined closed. liaen ...c unit was r' d, the Fast St art i'elay was deenergized, closing t' c Fast Str .selay contacts. P.cfore the MBR relav could be ? :rgized and 2ts resnec-tive contacts opened in the enginc " loc!: a" circuit, the "l o'clou r " relay uns actuated which prevented a subr er xnt start. Tne engine 3 would renain locked out until the rela;;c: ?lc be manually reset le cally, as nas the case. 1;F' ~ib I .'.L f . ! O', .

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di: fc tr.u ini re: s. All c:. co cere ,. :. fcetccy. As reg:: M 1792 207 <g go o e Ty a la X n

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to rer', : . A "iCyt StLri" tt;st of I 3 !Lf el Ce; ' ..I' U .' . 5 0' s C .'. . cntly C o!. .'u r I C d

                    . .ile rmiton:u. the enginc fcult 2.? c ci rcui trv, turning up tia prci.)er rs *nevict-1:. dir cus.v ad.         G: w: .!         i.. et ers ha s been ec .-

t act ed with ret.crd:. t o a nodi ficatica 1:nich cc Ad be cade to tha circuit to circuivent the problent. S PETY SiQ: F1CAF: - h deri:;ned redundancy for the stnt lo:i vi tal pv.<cr supplies (i . e . , off-sitc pacer '.d diesel ;a S ctms) w not prescnt and, in fact , h.d not bcen present since July 30, 1U73 when a test of the S.crtup Transformer p: tare differential relcy: had been conducted. Under a bona-fide loss of power ccndition, bou a esel generntors would have p:;rfor;ned their intended function and, in fact, did since both units actuete; to enerrine their respective buses upon initin11y sensing undervoltarc. Ilo.eever, had a prnlett arisen, which required a subsequent " Fast S* art" irzaediately after the units had been secured from a " Fast St: rt ," such as occurred here, no AC power would have been availabic to power any necessary safe-guarch equipment until the engine " lockout" relays cauld be reset. P.E CO'2 CNDAT1ONS :

1. Prepare procedures, in cenjunction with the P. clay Departnant, for all Relay Departccnt work in the plant. All work must be coordinated with the Shift Forcn.cn.

                   .      Prepare a desirn change to the diesel gencrator logic circuits to prevent lockout fo!!cminr, chu ('u n of the diesel.                         General 1lotors should be contacted for recon:acndations.

3. Pcriew and revise Procedure 511, as rcquired.

1792 208 Pmpared ,ey: e I

                                                          < )_         Date:           ,.j'I'./?.

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ATTACIC C III Page 5 of 5 RESPONSE 'ID ENCNJRE QUESTIONS REPORTIGLE CTUPRENCE 50-219/73-19 Section B of Enclosure Questions is pertinent since this event involved both Startup Transformers. RESIONSE: B.1 Power to both ouses was lost for approxunately 15 seconds until the Diesel Generator could start and supply power to one bus. Refer to report for . details. NCTIE: As described in the report the designed sta.-tup transfcImer capability was lost for a period of approx. 38 days. B.2 Since the event caused a Reactor Scram Turbine Trip, this glestion does not appear perti:ient. Please review report for details. B.3 Both autcratic and manual actions were taken as detailed in the report. B.4 No voltage excursions are relevant to the occurrence. B.5 No frequency excursions are relevant to the occurrence. B.6 Date of event: 9/8/73 1792 209}}