View source for PNO-V-85-046, on 850720,reactor Tripped from 100% Power Due to Turbine Trip on Loss of Unit Auxiliary Transformer.Caused by High Temp When Failure of Control Relay Caused Loss of Cooling Fans

{{Adams
| number = ML20132C603
| issue date = 07/22/1985
| title = PNO-V-85-046:on 850720,reactor Tripped from 100% Power Due to Turbine Trip on Loss of Unit Auxiliary Transformer.Caused by High Temp When Failure of Control Relay Caused Loss of Cooling Fans
| author name = Pereira D, Richards S
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION V)
| addressee name = 
| addressee affiliation = 
| docket = 05000344
| license number = 
| contact person = 
| document report number = PNO-V-85-046, PNO-V-85-46, NUDOCS 8507300398
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 1
}}
{{#Wiki_filter:1.      1 O     l Y.      f PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-85-46          Date: 07/22/85 Thia preliminary notification constitutes EARLY notide of events of POSSIBLE safety or public intsrest significance. The information presented is as initially received without verification cr evaluation and is basically all that is known by Region,V staff on this date.
FACILITY: Portland General Electric Company                     Emergency Classification Trojan Nuclear Plant                 .
Notification of Unusual Event Docket No. 50-344                                       Alert      ,
Portland, OR 97204                                      Site Area Emergency General Emergency
                                                                 >O( Not Applicable

==SUBJECT:==
REACT 0k TRIP AND SUBSEQUENT SHUTDOWN FOR GREATER THAN 48 HOURS Ths reactor tripped from 100% power at 7:07 a.m.,     PDT, on July 20, '985, because of a turbine trip that was caused by the loss of the unit auxiliary transformar. The auxiliary transformer " locked out" due to high temperature when the failure of a control relay caused the loss of its cooling fans. All systems functioned normally following the trip except th t low pump suction pressure caused the trip of one auxiliary feedwater pump and then the oth1r after restart of the first pump. This feature was subsequently bypassed by the cp;rator.
Tha low suction pressure was caused by excessive combined flow from the two auxiliary fe:dwater pumps which draw from a single header from the condensate storage tank. The flow control valves were open farther than required since new controllers had been installed during the recent refueling outage. Surveillance tests of individual flow paths previously parformed did not indicate that low pump suction pressure would be a problem. The valves h:va now been adjusted and the limit switch band for minimum-maximum flow reset to preclude future problems.
Th2 reactor had to be taken to Mode 4 to repair a circulating water to hot well leak that d:veloped during the transit. Due to water cleanup and the repair, startup was not cxp2cted until July 23, 1985.
This information is current as of 8:00 a.m., PDT, July 22, 1985.
CONTACT:   D. Pereira                      S. Richards FTS 463-3788                    503-556-3751 DISTRIBUTION H St. //13           MNBB/# Y 7Phillips # TE/W      Willste# U Air Rights           Mail:
Chairman Pallidino EDO          NRR          IE        NMSS                         ADM:DMB Comm. Zech            PA                     OIA       RES                          DOT:Trans Only Comm. Bernthal        MPA                    AE0D
-Comm. Roberts          ELD C:mm. Asselstine                Regions : A'It /! J2, /IT--/? J'/j M-/ 3'f,d 2 I # #
SECY                            INP02lCT NSAC,2 : o /
ACRS                            Licensee: Tf -2 3 CA                              (Reactor Licensees)            REGION V: FORM 211 PDR                             ResidentInspector[27                (Revised 3/14/83) 8507300398 850722                            i -F PDR    18,E PNO-V-85-046       PDR gC_                 L[
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