View source for PNO-V-85-062B, on 850919,reactor Tripped Due to Failure of Steam Reheater Dump Valve to Actuate Resulting in Main Turbine Overspeed.Caused by Lack of Lubricating Oil in Bearing Sumps & Failure of Pressure Switch & Relay

{{Adams
| number = ML20132F217
| issue date = 09/23/1985
| title = PNO-V-85-062B:on 850919,reactor Tripped Due to Failure of Steam Reheater Dump Valve to Actuate Resulting in Main Turbine Overspeed.Caused by Lack of Lubricating Oil in Bearing Sumps & Failure of Pressure Switch & Relay
| author name = Huey R, Johnson P
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION V)
| addressee name = 
| addressee affiliation = 
| docket = 05000206
| license number = 
| contact person = 
| document report number = PNO-V-85-062B, PNO-V-85-62B, NUDOCS 8510010270
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 1
}}
{{#Wiki_filter:.. ___
                                                                                                                  'b.
PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE-PNO-V-85-62B                            Date: 09/23/85 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: Southern California' Edison Company                                    Emergency Classification                       ,
San Onofre Unit 1                                                        Notification of Unusual Event Docket No. 50-206                                                        Alert Site Area Emergency                        .
General Emergency XX Not Applicable
                          ~

==SUBJECT:==
SECOND UPDATE - REACTOR TRIP INVOLVING INOPERABLE TURBINE-DRIVEN                                                       ,
AUXILIARY FEED PUMP AND MAIN TURBINE OVERSPEED San Onofre Unit 1, t' ripped at 1905 on September 19, 1985. The turbine-driven auxiliary feedwater-(AFW) pump started but tripped after a brief run. The AFP trip was initially                                          :
believed to be due to overspeed, b"ut was. subsequently determined by the licensee to have resulted from insufficient lubricating oil in the bearing sumps.
Following the main turbine trip, one steam reheater dump valve did not actuate as required, resulting in a main turbine overspeed to'126% of normal speed (1800 rpm). The licensee has determined that.this was caused by failure of a pressure switch and a relay, both of which were replaced (this is not a nuclear' safety related system).
Following the event, both turbine bearing sumps on the turbine-driven AFW pump were found to have-low oil level. The sight glass on the inboard bearing (pump end of turbine) was correctly indicating a low level, but the sight glass on the outboard end was incorrectly indicating a normal level due to blockage by a portion of a protective ear plug.
In interviews with maintenance personnel subsequent to the event, licensee management-determined that a maintenance person had improperly used a portion of an ear plug as a gasket to repair a leaking sight glass. The licensee believes the loss of oil from the inboard sump resulted from wear on'a shaft. oil seal, plus some sight glass leakage. The                                        ;
turbine-driven AFP has been repaired and successfully tested.
The' unit is expected to restart today (9/23/85) following completion of minor repairs unrelated to this' event.
This informatio is current as of 10:00 am on September 23, 1985.
CONTACT: P       ha on                      R. Huey FT 4DL3745                        (714) 492-2641
     . DISTRIBUTION H St. 3' E             MNBBDPhillips          E/W                   Willste        Air Rights     I Mail:
Chairman Pallidino EDO-          NRR           IE                        NMSS                                ADM:DMB Comm. Zech             PA                     '01A                      .RES  g                              DOT:Trans Only Comm. Bernthal         MPA                     AEOD Comm. Roberts           ELD Comm. Asselstine                 Regions :[f-T 2h d-J
* D       j M- 7'Vd SECT'                             INPO 7:YV NSAC 7: Y.2-ACRS                             Licensee: S* 2 '7 CA                               '(Reactor Licensees)                           REC 10N V: FORM 211 PDR                              Resident Inspector f.'/ >                           (Revised 3/14/83)-                         1 h00         0WW PNO-V-85-062B PDR
[d
-_ _                                                         _ _ _ _ _ _ _ - _                            _ _ _ _ _ _ _ - - _ -}}

{{PNO-Nav|region=V}}