PNO-V-86-094, on 861224,facility Tripped from 100% Power. Cause Believed to Be Electrical Malfunction on Vital Bus B. Definitive Cause of Malfuncion Under Investigation.Unit Will Be Maintained in Mode 3 Until Cause Identified

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PNO-V-86-094:on 861224,facility Tripped from 100% Power. Cause Believed to Be Electrical Malfunction on Vital Bus B. Definitive Cause of Malfuncion Under Investigation.Unit Will Be Maintained in Mode 3 Until Cause Identified
ML20212E764
Person / Time
Site: Palo Verde Arizona Public Service icon.png
Issue date: 12/29/1986
From: Bosted C, Richards S
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-86-094, PNO-V-86-94, NUDOCS 8701050444
Download: ML20212E764 (1)


K PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE-PNO-V-86-94 Date: 12/29/86 Thio preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information pre;;ented is as initially received without verification er cvaluation and is basically all that'is known by Region V staff on this date.

FACILITY: Arizona Nuclear Power Project Emergency Classification Palo Verde Unit 2 ~ ~ ~ Notification of Unusual Event DOCKET No. 50-529 Alert Site Area Emergency General Emergency X Not Applicable

SUBJECT:

REACTOR TRIP AND PLANT SHUTDOWN CREATER THAN 48 HOURS On December 24, 1986, at approximately 8:10PM, MST, Palo Verde Unit 2 tripped from 100%

powar. The cause of trip is believed to be due to an electrical malfunction on the "B" Vital bus. Plant Protective Systems and Engineered Safety Features System are powered from that bus and portions of those systems were deenergized due to the malfunction.- In addition-to the Reactor Trip, actuations of the Safety Injection, Containment Isolation, Main. Steam Isolation. Auxiliary Feedwater 1, and Recirculation Systems occurred. A definitive cause of thi electrical malfunction is currently under investigation and the licensee intends on

. maintaining the unit in Mode 3 until the cause has been identified and the Post-Trip review h2s been completed.

A press release was issued by the licensee.

This information is current as of 9:30 AM (MST) December 29, 1986.

CONTACT: S. Richards C. Bosted FTS 463-3853 (602) 386-5260 DISTRIBUTION H St. MNBB Phillips#O'OfE/W Willste Air Rights /I./3 Mail:

~ Chairman Zech EDO NRR IE NMSS ADM:DMB Comm.' Roberts PA OIA RES DOT:Trans Only Comm. Asselstine MPA AEOD Comm. Bernthal OGC Comm. Carr Regions:

SECY INPO / f5~ NSAC / '87

.ACRS Licensee:

CA (Reactor Licensees) REGION V: FORM 211 PDR Resident Inspector 2?/() (Revised 3/14/83)

Hqs apelmcAS c5K l' S 90

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