View source for PNO-II-85-095, on 851011,unit Shut Down Following Failure of One Emergency Diesel Generator to Pass Routine Checks While Down for Maint.Restart Procedures Underway.Pistons & Two Cylinders replaced.Post-repair Review & Testing Completed

{{Adams
| number = ML20134A376
| issue date = 10/15/1985
| title = PNO-II-85-095:on 851011,unit Shut Down Following Failure of One Emergency Diesel Generator to Pass Routine Checks While Down for Maint.Restart Procedures Underway.Pistons & Two Cylinders replaced.Post-repair Review & Testing Completed
| author name = Burger C, Elrod S
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION II)
| addressee name = 
| addressee affiliation = 
| docket = 05000339
| license number = 
| contact person = 
| document report number = PNO-II-85-095, PNO-II-85-95, NUDOCS 8511040381
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 2
}}
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)-                                                                       October 15, 1985 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PN0-II-85-95 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verifi-cation or evaluation, and is basically all that is known by the Region II staff on this date.
FACILITY: Virginia Power Company                      Licensee Emergency Classification:
North Anna Unit 2                              Notification of Unusual Event Docket No. 50-M- 339                           Alert tiineral, Virginia                             Site Area Emergency General Emergency X Not Applicable

==SUBJECT:==
OUTAGE IN EXCESS OF 48 HOURS The Unit is undergoing restart procedures today after being shut down on October 11 after failure of one of its emergency diesel generators to pass routine checks while down for maintenance. The licensee reported that, while paralleled to normal power at about 90 percent load and at rated speed, a procedure violation resulted in disconnecting the electric governor. This caused a rapid load increase which resulted in tripping of the output breaker on overcurrent.
Th2 resulting loss of load with the throttle set to increase led to an overspeed trip.
Following completion of maintenance, the machine was restarted but failed to run because of crank case pressure trips. The licensee commenced shutdown of the Unit after a 72-hour action statement was exceeded.
The licensee has subsequently determined that defonnation/ extrusion of the wrist pin bushings occurred, resulting in piston-to-cylinder contact and scoring. Following consultation with the vendor, the licensee suspects the cause of the problem to be associated with a history of 50 to 70 fast starts of the generator with rapid loads, rather than Friday's overspeed event.
All pistons and two cylinders have been replaced. The plant has completed post repair review and testing. The licensee plans further technical review and testing. The licensee plans further technical review of the problem which will include the vendor and a reliability consultant.
R;gion II will conduct routine followup.
This information is current as of 3:00 p.m. on October 15.

==Contact:==
C. Burger, 242-4198                             S. Elrod, 242-5536 DISTRIBUTION:                  4          4                     pD H. Street- W f MNBB'49         Phillips /   E/W gWillste q MAIL:
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