ML20084J084

Preliminary AO-73-19:on 730908,setting on Base Differential Monitoring Relay C of Startup Transformers Considered Inoperable.Caused by Incorrect Setting of Transformer Ratio Matching Taps.Taps Set Properly

ML20084J084
Person / Time
Site:	Oyster Creek
Issue date:	09/10/1973
From:	Carroll J, Reeves D JERSEY CENTRAL POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
AO-73-19, NUDOCS 8305100056
Download: ML20084J084 (5)

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To:

Jaima P. O'RaL1Ly Directorato of Regttlatrity Oparations Rogion 1 631 Path Avonno King of PtuuGido Petussylvania 19406 a

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Jatscy Ccatral Power ti (,Lgitt bomg.uny Oystar Crcck Hucicat Cetteratitty Station ()ocket !!SO-419 Totkod Rivoro UcW Jersey OU/JL Subject s Abitortual Occurrcoco itoport 73-19 The folicuing La a ptclit,tinitty report hainy subntitt.ed ist cc::tp11ance alth the Technical Spocificaticnu paragraph G.6.2.

Prollettenary Approval:

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. f. CarrolI, Jr.

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ABN0!WAL OCCURRENCE a

REPORT N0. 73-19 l

S_UBJECT:

Violation of the Technical Specification, paragraph 3.7 A.2, in that although both startup transformers were energized to carry power to the station 4160V AC buses, neither transformer could be considered operable due to an improper setting on the C base differential monit-l oring relay.

j Additionally, this event is considered to be an abnormal occurrence as defined in the Technical Specifications

• 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 plant.

Notification of this event, as requireti by the Technical Specifications, l

paragraph 6.6.2,a, was made to AEC Region I, Directorato of Regulatory Operations, by tolophone on Saturday, September 8,1973, at 10:15 a.m.,

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

SITUATION:

M A plant shutd.own had progressed to the point where, with electrical output at approximately 90 Mio, a transfor of station loads from the Auxiliary Transformer to the Startup Transformers was attempted. When a closing signal was applied to the SLA breaker, a loss of power occurred the the "1A" 4160V AC bus, which among other things caused two circula-tory water pumps, three reactor recirculation pumps and the operating condensate and feedwater pumps to trip.

Diessi Generator #1 started l

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it Ahnureal Occurrenco Septecher 8, 1973 Roport No. 7319

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" bus and the req-in the " Fast Start" mode, reonorgleing the 4160V "1C An attempt was nnde to start the D quisite safeguard power supplies, and C condensate pumps, but before either pu:tp could be started, the Automatic treuufor to the reactor scracmed due to low water level,

' SID transforrrer was accomplished, but later in atteepting to start a condensate pump powered fros the "18" 4160V bus, SIB tripped initlating The second CRD pump the "IM t Start" sequence on Diesel Generator #2, was started to assist in monitoring reactqr w:lter level which droppad

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to 9 feet above the active fuel. The reactor was isolated to prevent water inventory loss and the emergency condensers were initiated as needed to remove ' decay heatI. The point at which reactor. isolation occurs artd the emergency cooling system is initiated was g reached, The problem was traced to an incorre'ct setting of the current trans-CAUSE:

fomer ratio matching tops for the C phase differential relay on both In attempting to either carry a sizeablo load or startup transformers.

start a large load, a differential fault was sensed, tripping the cut-put breakers.

REN.0I Ai, ACT104:

The curront transfomer ratio eatching taps were set tap properly a station loads wore returned to normal. The company Relay Departcent was contacted and load checks were conducted in each of the startup All checks were satisfactory.

tratufomor phase differential relays.

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O-Alxto rt:Ist Occurrence Report No. 73-19 L3-Septecher 4, 1973 a

SAFF.TY SIGNIFICANCE:

The significance of this event is that tho designed redundancy of power supplies for the station 4160V buses was not present and, in fact, had not been pre.,ent since July 30, 1973 when the relay test was made, llowcycr, both dicSel P.enerators did function properly upon the loss of power.

Consequently, plant safety was not endangered, j

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c.+a v.cg Date:

September 10; 1973

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For safestion.

F.e A p r.'s t ( Hr.. hf ew e 4. I's 8 ? ) Alf*f0240 iO<N.,...epen, fx n s g u o m 5 Licensce:

J:rsty CentLa Power & Light Company

11. D. Thornburg, oATE Docket No.:

50-219 Chief, FSLEB Abnormal Occurrence:

A0 73-19 10 (N2me and unat)

INITI AL5 PluARAS j

RO:HQ (5)

DR Central Files (1)

The attached report from the subject licensee is oAiE R:gulatory Standards

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Dir. of Licensing (13 foruarded in accordance with RO Manual Chanter 1000.

i 1O (NIme and unit)

INB11ALS M MARK 5 RO Files The action taken by the licensee is considered appropriate.

Followup will be performed during oATE the next incpection as aporopriate.

Copies of f ROM (Name and unit)

PEMARKS

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the report have been forwarded to the PDR, Local I

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PDR, NSIC, DTIE and State representatives. The R. T. Carlson, Chief Facility Operations Bt anch licensee will submit a 10 day written report to POE NOL oATE 9/12/73 Licensing.

USE OTHER 54DE FOR ADoiTIONAL REMAltKS CPO 19710 - 445 4!9 8

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