View source for PNO-V-86-023, on 860426,ESF Load Sequencer for Train a Emergency Diesel Generator Inoperable.Caused by Broken Conductor in Relay Wire Discovered in Late 1985 But Mistakenly Considered Unimportant Grounding Path

{{Adams
| number = ML20203N883
| issue date = 04/29/1986
| title = PNO-V-86-023:on 860426,ESF Load Sequencer for Train a Emergency Diesel Generator Inoperable.Caused by Broken Conductor in Relay Wire Discovered in Late 1985 But Mistakenly Considered Unimportant Grounding Path
| author name = Miller L, Zimmerman R
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION V)
| addressee name = 
| addressee affiliation = 
| docket = 05000529
| license number = 
| contact person = 
| document report number = PNO-V-86-023, PNO-V-86-23, NUDOCS 8605060176
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 1
}}
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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-86-23 Date: 04/29/86 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by Region V staff on this date.
FACILITY: Arizona Nuclear Power Project                          Eme.rgency Classification Palo Verde Unit 2                                         Notification of Unusual Event DOCKET No. 50-529                                         Alert Site Area Emergency General Emergency X Not Applicable

==SUBJECT:==
INOPERABILITY OF EMERGENCY DIESEL GENERATOR TRAIN       'A'  LOAD SEQUENCER On April 26, 1986, the licensee discovered that the engineered safety features load ssquencer for the Train 'A' Emergency Diesel Generator (EDG) was inoperable due to a broken conductor in a relay wire. This open circuit would have prevented the Train 'A' EDG output breaker from closing onto the 4160 volt emergency bus, if called upon, by a loss of offsite power.
Preliminary information from the licensee indicates that the wire conductor was discovered to be broken by the licensee in late 1985 prior to low power licensing. However, the function of the wire was mistakenly believed to be an unimportant alternate grounding path. Consequently, it appears that repair of the condition did not receive priority attention by the licensee, and the EDG may have been inoperable from late 1985 to the present.
Pelo Verde Unit 2 is in Mode 3. The Senior Resident Inspector and his staff are following up to confirm this information and assess its significance.
This information is current as of 9:03 am, PDT, on April 29, 1986.
CONTACT:   R. Zimmerman, Sr. Resident Inspector         L. Miller (602) 386-5760                               (415) 943-3869 DISTRIBUTION H St.                MNBB     Phillips       E/W     Willste      Air Rights 31 55EMail:
Chairman Palladino EDO           NRR          IE       NMSS                        ADM:DMB Comm. Zech                                    OIA                                  DOT:Trans Only PA                               RES Comm. Bernthal        MPA                     AEOD Comm. Roberts         ELD Comm. Asselstine                 Regions:
SECY                             INP08.*f(. NSAC g:J'/
ACRS                             Licensee: # 1 '/ /
CA                               (Reactor Licensees)          REGION V: FORM 211 PDR                              Resident Inspector __               (Revised 3/14/83) 8605060176 860429 PDR    ILE
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