ML19317F225

AO-287/75-06:on 750327,inadvertent Isolation of Keowee Underground Feeder Occurred During Emergency Start Test. Caused by Deficiency in Test Procedure.Test Procedure Modified to Assure Breaker Is Closed at All Times

ML19317F225
Person / Time
Site:	Oconee
Issue date:	04/11/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19317F221	List: ML19317F220 ML19317F225
References
NUDOCS 8001080935
Download: ML19317F225 (1)

Text

-- _ - _ _ - - _ _ - _ _ _ _ _

OO%

f%

em m.

--r ..

[]'

\-

DUKE POWER COMPANY OCONEE UNIT 3 Report No.: A0-287/75-6 ,;, ,,

(-II *T Report Date: April 11, 1975 Occurrence Date: March 27, 1975 Facility: Oconee Unit 3, Seneca, South Carolina Identification of Occurrence: Inadvertent isolation of Keowee underground feeder Conditions Prior to Occurrence: Power operation Description of Occurrence:

on March 27, 1975, the Keowee Emergency Start Test was performed from the Oconee Unit 3 control room. The test is performed by isolating the Keowee overhead transmission line from the 230 kv switchyard, inhibiting one Keowee unit, and starting the remaining Keowee unit with the emergency start circuits. The first portion of the test, with Unit 2 inhibited, satis-factor 11y resulted in Keowee Unit 1 charging the underground feeder. When the inhibit was removed from Keowee Unit 2 and Unit 1 was inhibited, ACB3 (breaker from Unit 1 to underground feeder) opened resulting in both Keowee units being isolated from the underground feeder and overhead transmission j lines for a period of five minutes.

Designation of Apparent Cause of Occurrencel The apparent cause of this occurrence was a deficiency in the procedure in that it did not caution that a Keowee unit inhibit results in the opening of the associated breaker to the underground feeder. The Test Cecrdinator performing the test did not realize the existence of this interlock.

Analysis of Occurrence: I The Keowee Hydro Station supplies emergency power to the Oconee Nuclear Station through the underground feeder in the event of a system blackout and the loss of the Oconee units. This incident resulted in the Keowee Hydro Station being separated from Oconee for a period of five minutes.

Should emergency power have been required, ACB-4 could have been closed by j operator action to connect Keowee Unit 2 to the underground feeder. It is j concluded that the health and safety of the public was not affected by l this incident.

Corrective Action:

The Keowee Emergency Start Test procedure has been changed to assure that either ACB3 or ACB4 is closed at all times during the test. This will result in one Keowee unit being connected to the underground feeder circuit at all times.  ;

I 8001080 f g

~~

NRC DILNjfp 'lON FOR PART SO DOCKET MATERIAL

^

• -  : TEMPORARY FORM)

~

• CONTROL NO:

FILE: INCIDEITT REPORT FII.Z DATE OF DOC D ATE R E O LTR TWX RPT OTHER FROM: Duke Power- Company Charlotte, N.C. 4-11-75 4-16-75 XXX CC OTHER SENT AEC PDR XXX TO'. ORIG 1 Signed XXX Norman C. Moseley SENT LOCAL PDR PROPINFO INPUT NO CYS REC'D DOCKET NO:

CLASS UNCLASS XXX 1 50-287 DESCRIPTION: ENCLOSURES:

Letter trans the following, ..... Abnorm. Occurr. # 75-6, on 3-27-75, concern-ing Inadvertent isolation of Keowee under-ground feeder....

( 1 cy. Encl. rec'd)

PLANT NAME: Oconee #3 FOR ACTION /INFORMATION vcn 4_17 75 SCHWENCER (L) ZIEMANN (L) REGAN (E)

BUTLER (L) W/ Copies W/ Ccpie: W/ Copies W/ Copies CLARK (L) STOLZ (L) DICKER (E) LEAR (L)

W/ Cop!.s W/ Copies W/ Copies W/ Copies PARR(1) VASSAL.LO (L) KNIGHTON (E) SPE l.S W/ Copies W/ Copies W/ Copies W/ Copies KNIEL (L) / PUHPLt- (L) 'Y'OUNGtstOOD (E)

W/ Copics W/3 Copies W/ Copies W/ Copies INTERNAL DISTRIBUTION LIC ASST A/T IND .

BEG F TECH REVIEW DENTON BRAITMAN jNRC PDR pSCHROEDER yGRIMES R. DIGGS (L)

MACCARY GAMMILL H. GEARIN (L) SALTZMAN OGC, ROOM P 506A KNIGH' KASTNER E. GOULBOURNE (L) MELTZ GOSSICK/ STAFF f CASE PAWL Al BALLARD P. KREUTZER (E)

PLANS GIAMBUSSO SHAO SPANG LER J. LEE (L) .

M. MAIGRET (L) MCDONALD BOYD **s STE LLO CHAPMAN MOORE (L) **fHOUSTON ENVIRO- S. REED (E)

• • MULLER M. SERVICE (L) DUBE (Ltr)

DEYOUNG (L) ,NOVAK E. COUPE SKOVHOLT (L) ROSS DICKER # .SSHEPPARD (L)

KNIGHTON M. SLATER (E) PETERSON GOLLER (L) (Ltr) f lPPOLITO HARTFIELD (2)

P. CO LLINS TEDESCO YOUNG BLOOD H. SMITH (L)

REGAN S. TEETS (L) KLECKER l DENISE LONG EISENHUT  !

R E G O P R_ LAINAS PROJECT LDR G. WILLI AMS (E)

V. WILSON (L) WIGGINTON

.'Fil E & REGION (2) BENAROYA VOLLMER HAR LESS R. INGRAM (L) 'F. WILLIMIS f "IPC/PE (3) , pguy,73 STEELE EXTERN AL DISTRIBUTION cc el - LOCAL PDRJallahalla, S.C. 1 - PD R-SAN /LA/NY  !

pl - TIC (ABERNATHY) (1)(2)(10) - N ATION AL LABS 1 - BROOKHAVEN NAT LAS 1 - W. PENNINGTON, Rm E 201 GT f 1 - NSIC (BUCHANAN) 1 - G. ULRIKSON, O P.N L 1 - ASLB 1 - CONSULTANTS EWM ARK /BLUME/AGBA8I AN 1 - AGMED (RUTH GUSSMAN) 1 - Newton Anderson M- ACRS SEIT To LIC ASST

• • SE::D CNill TE:i DNI REPORTS y

( .

Rm 8-127 GT 1 - J. D. RUNKLE'S, Rm E 201 GT l

l O

~

1. 4 " ;. ^

.- DUKE POWER COMPANY .

PowzR Buscrwo 4aa SouTu CHURcu SrazzT, CuAaroTTE, N. C. asaci A. C. THICS P. o. Box as7e StmaOm Vict PettiOENT PWODUCfiON ANO TRANSedeSSION April 11, 1975 --

..s.

. f Mr. Norman C. Moseley, Director ~

U. S. Nuclear Regulatory Coramission Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 Re: Oconce Unit 3 Docket No. 50-287

Dear Mr. Moseley:

Pursuant to Sections 6.2 and 6.6.2 of the Oconee Nuclear Station

~ Technical Specifications, please find attached Abnormal Occurrence 1

Report A0-287/75-6% -

Very truly yours, S .

l A. C. Thies -

ACT:vr I Attachment -

cc: Mr. Angelo Giambusso W

s e e--- . 3- m-- - - , e-

w y.! . ;m #N DUKE POWER COMPANY OCONEE UNIT 3 Report No.: A0-287/75-6 Report Date: April 11, 1975 Occurrence Date: ,

March 27, 1975 Facility: Oconee Unit 3, Seneca, South Carolina

. Identification of Occurrence: Inadvertent isolation of Keowee underground feeder Conditions Prior to Occurrence: Power operation Description of Occurrence:

On March 27, 1975, the Keowee Emergency Start Test was performed from the Oconee Unit 3 control room. The test is performed by isolating the Keowee overhead trcnsmission line from the 230 kv switchyard, inhibiting one Keowee unit,-and starting the remaining Keowee unit with the emergency start circuits. The first portion of the test, with Unit 2 inhibited, satis-factorily resulted in Keowee Unit 1 charging the underground feeder. When the inhibit was removed from Keowee Unit 2 and Unit 1 was inhibited, ACB3 (breaker from Unit 1 to underground feeder) opened resulting in both Keowee units being isolated from~the underground feeder and overhead transmission lines for a period of five minutes.

Designation of Apparent Cause of Occurrence: ,

The apparent cause of this occurrence was a deficiency in the procedure in that it did ncc caution that a Keowee unit inhibit results in the opening of the associated breaker to the underground feeder. The Test Coordinator performing the test did not realize the existence of this interlock.

Analysis of Occurrence:

The Keovee Hydro Station supplies emergency power to the Oconee Nuclear Station through the underground feeder in the event of a system blackout and the loss of the Oconee units. This incident resulted in the Keowee Hydro Station being separated from Oconee for a period of five minutes.

Should emergency power have been required, ACB-4 could have been closed by operator action to connect Keowee Unit 2 to the underground feeder. It is concluded that the health and safety of the public was not affected by this incident.

Corrective Action:

The Keowee Emergency Start Test. procedure has been changed.co assure that either ACB3 or ACB4 is closed at all times during the test. This will result in one Keowee unit being connected to the underground feeder circuit at all times.