PNO-III-90-046, on 900709,partial Loss of Offsite Power Occurred During Refueling Outage.Determined That Technician Failed to Insert Relay Logic Block.Licensee Reviewing Controls on Switchyard Activities.State of IA Notified

PNO-III-90-046:on 900709,partial Loss of Offsite Power Occurred During Refueling Outage.Determined That Technician Failed to Insert Relay Logic Block.Licensee Reviewing Controls on Switchyard Activities.State of IA Notified

ML20055G348
Person / Time
Site:	Duane Arnold
Issue date:	07/11/1990
From:	Hague R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-90-046, PNO-III-90-46, NUDOCS 9007230079
Download: ML20055G348 (1)

F~~u IPRdlMINARYtiOTIFICATIONOFEVENT-ORUNUSUALOCCURRENCEPNO-Ill-90-46DateJuly 11.-1990 f: . . \

h Thish preliminary n;tificati:n constitutes EARLY notice of events of POSSIBLE safety or p:blic

/ ; interest significance. The information is as initially received without verification or

;valuatiAn,' and is basically all that is known by the Region 111 staff on this date. (}g

{

Facility:. Iowa Electric Light & Licensee Emergency

!.. Power Classification: .

Duane Arnold Energy X Unusual Event '

Center Alert Palo, I A 52324 Site Area Emergency General Emergency Docket No. 50 331 Not Applicable

Subject:

PARTIAL LOSS OF 0FFSITE POWER At 10:33 a.m. (CDT), July 9, 1990, during a refuoling outage, the standby transformer s:ddenly lost power. This caused a temporary lots of off-site power to both 4160 volt <

ess:ntialbuses(1A3and1A4). Offsite power rerained to the non-essential 4160 volt buses.

All fuel had previously been removed from the reactor. The A emergency diesel generator was out of service at the time, but the B diesel generator was available.

' The power loss occurred during relay testir.g in the switchyard. The licensee determined that a technician failed to insert a relay logic block, thereby tripping a supply breaker to the standby transformer. This caused busses 1A3 and 1A4 to lose power. A suisequent full R: actor Protection System (RPS) scram signal and Primary Containment Isolation System (PCIS) group 1 through.5 isolation signals were received. (No rod motion occurred because of refueling activities. Isolation of some PCIS valves were also blocked because of maint: nance.tagouts.)

Tha 1A4 bus was r^ energized inmediately by the B Emergency Diesel Generator. Bus IA3 r:mained deenergiced for about 40 minutes until power was restored to the standby transformer.

The licensee declared an Unusual Event at 11:31 a.m. (CDT), July 9, 1990, in accordance with its Emergency Classification System. The Unusual Event was terminated at 11:54 a.m. (CDT). '

- The licensee is currently reviewing its controls on all switchyard activities. -

. Region'111 (Chicago) is monitoring the licensee's course of action.

.TheLState of Iowa will be notified. This information has been reviewed with licensee manag: ment. .

Region 111 was notified of this event at 11 a.m. (CDT), July 9,1990. This information is currsnt as of 9 a.m. (CDT), July 11, 1990.

CONTACT:6 . Hague (FTS 388-5546) .K [(FTS388-5547)

DISTRIBUTION:

HEADQUARTERS OFFICES REGIONS MAIL T0:

Chairman Carr NMSS Region 1 DCS (Orig) ( '

GPA:SP Region 11 DOT (Tranc. ,

Cornm. Rogers GPA:PA Region IV Only)

Comm. Curtiss GPA:CA Region V / ',

Comm. Remick *0lG EDO

' Gen. Counsel

• ASLAP Research FAX T0:

INP0 /01/4 NSAC /O!40 LIC /OW2

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NRR 1RM NRC OPTCTR / O.'.7

• 9007230079 900711 AE0D - ACRS PDR (8/634-33T3) 70N PDR I&E PNO-III-90-046 PDC Enforcement (Denotes a Displaywriter/PC not an IBM 5520 Terminal. . Rev. 06/22/90