ML20151C185

AO 73-19:on 730908,1A 4,160 Volt Ac Bus Lost Power Causing Two Circulating Water Pumps,Three Reactor Recirculation Pumps & Operating Condensate & Feedwater Pump to Trip.Caused by Improper Tap Setting of Current Transformer Ratio

ML20151C185
Person / Time
Site:	Oyster Creek
Issue date:	09/10/1973
From:	Reeves D JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-73-19, NUDOCS 8103041008
Download: ML20151C185 (3)

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THIS C9CUMEN1-'CONTAINS ABNOURL OCCURRENCE ,

POOR QUALITY PAGES 'A ..,.v . '-

REPORT NO, 73-19 -

SUBJECT:

Violation of_ the Technical 6pecification, paragraph 3.7. A.2, in- that although both startup transfomers were energir.ed to carry power to-the station 4160V' AC busos, neither transformer-could be considered operab1'e due to an improper setting on the C base differentia 1'monit-oring; relay, , ,

, . - Additionally, this event is considered to be an 'abnomal occurrence as defined in the Technical Specifications,A paragraph 1.15G, in that proper procedural controls were not implemented with respect to pro-tective relay testing, which resulted in the development of an unsafo .

condition in connection with.the operation of the plcat.

Notification of this event, as required by the Technical Specif;ications, paragraph 6.6.2,a, was made to AEC Region I, Directorate of Regulatory Operations, by telephone on Saturday, September 8,1973, at 10:15 a.m.,

t and by telocopier on Monday, September 10, 1973, at 1:30 p.m.

M SITUATION:

l A plant shutd.own had progressed to the point where, with electrical

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output at approximately 90 Mio, a transfer of station. loads from the Auxiliary Transfor:nor to the Startup Transformers was attempted. When a closing signal was applied to the S1A breaker, a loss of power occurred tho'the "1A" 4160V AC bus, which among other things caused two circula-i tory water pumps, three reactor recirculation pumps and the operating

~ condensate and feedwater pu ps to trip. Diesel Generator #1 started El030$oog . .

• w - eu a -eh e--e- "e w e-w e'm y -pv .w --e reeg es -4,4-yve- ew s su vtyvery t,r gr nvyw1- m.- = w y- m ,me p P ep ge remr e , >+ sy y e.gg i-t rey.-feemyei,+t--,-smm.W- c-=ser*at*t'* '* T' '* "- 't'

j Abnores1 Occurrenco ' ,

Septceher 8, 1973 s Report No. 73-19 .

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in the " Fast Start" mode, reenergising tho' 4160V "1C" bus and the req-

'An attempt. was made tu start the D quisite safeguard power supplies, '

'and C condensate pumps, but before either purp could be started, the-

.g Automatic transfor. todhe reactor scracacd due ,to low water' lev'el, _ ,

but 14ter in attempting to start a

' SIB transfortter was accosplished, .

condensate pump pwered from the "10" 4160V bu7, SIB tiipped initia 9 Tho'second CRD pucp  ;,

the " Fast start" sequence on Uleiol Generator #2, was started to-assist in monitoring rea'ctay water l'evel which dropped isolated to prevent The reactor w M to 9 feet above the active fuel.

initiated as water in ventory loss and the ecergency condensers were .

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The point at which reactor. isolation needed to remove tlecay heat. '

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occura and the emergency cooling systern is initiated wm ne,t, reac

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,etting of the current trans-CAUSE:

The problem was traced to an incorrect l

former ratio matching taps for the c phase differential relay on bo ^

In'attetapting to either' carry a sicedblo load or startup transfo mers.

start a large loud, a differential fault was sensed, tripping the out- t put breakers. .

PM01 A1, fd.TIOK: .

The curront transfomer ratio ett:hing taps w'ere set up properly a '

,3 The company Relay Departcent station loads wore returned to norraal.

was contacted and load- checks were conducted in each of the startu if y transformor phase differential relays. All checks were sat s actor ,

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3- Septer:her 8,1973 Report no; 73-19 a

i sArr.TY SIGNIFICANCE: ,

i The significance of this event is that tho designed redundancy of 1 pcuor supplies for the station 4160V buses was not present and, in fact, had not been pree.ent 9.ince July 30, 19734when the rolay test  ;

was inade. iWcVer, both dicSel f.enerators did function properly upon the loss of power. Consequently, plant safety was not endangered.

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9 I Date: Septcmber 10; 1973 Prepared by: ____.__

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