Part 21 Report - 1997-280

LICENSEE: COMMONWEALTH EDISON CO. SITE: ZION 1 2 EN NUMBER:32037 DOCKET: 05000295 05000304 EVENT DATE: 03-27-97 RX TYPE: PWR PWR EVENT TIME: 13:55 VENDORS: W-4-LP W-4-LP NOTIFY DATE: 03-27-97 EMERGENCY CLASS: N/A REGION: 3 STATE: IL TIME: 15:55 OPS OFFICER: HENRY BAILEY 10 CFR SECTION: CDEG 21.21(c)(3)(i) DEFECTS/NONCOMPLIANCE UNIT SCRAM RX INIT INITIAL MODE CURR CURRENT MODE CODE CRIT PWR PWR 1 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN 2 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN PART 21 NOTIFICATION BY VENDOR. COOPER-BESSEMER EMERGENCY DIESELS ON JANUARY 27, 1997 COMMONWEALTH EDISON COMPANY IDENTIFIED A SIGNIFICANT DROP IN CRANKCASE LUBE OIL LEVEL IN ONE OF THE COOPER-BESSEMER EMERGENCY DIESEL GENERATORS. SUBSEQUENT INVESTIGATION REVEALED THAT A CRACK HAD DEVELOPED IN THE CYLINDER LINER WALL ALLOWING JACKET WATER TO ENTER THE COMBUSTION CHAMBER. THIS RESULTED IN A FAILED PISTON. UPON REVIEW OF THE FAILED PISTON IT WAS NOTED THAT THE PISTON CROWN THICKNESS IN THE AREA OF FAILURE WAS BELOW DRAWING SPECIFICATIONS. THIS IS THE ONLY KNOWN FAILURE OF SUBJECT LINER. THIS LINER DESIGN IS IN USE ON "EARLY" KSV ENGINES IN USE AT THE ZION STATION AND AT THE COOPER NUCLEAR STATION. FAILURE OF THE PISTON WAS A DIRECT RESULT OF THE LINER FAILURE. FINITE ELEMENT ANALYSIS IS BEING CONDUCTED BY COOPER-BESSEMER TO DETERMINE ACCEPTABLE MINIMUM THICKNESS FOR THE PISTON CROWN SECTION. THIS PISTON EVALUATION COULD AFFECT THE FOLLOWING KSV USERS: PALO VERDE, BRAIDWOOD, BYRON, ZION, WATERFORD III, SOUTH TEXAS, COOPER, NINE MILE POINT 2, AND SUSQUEHANNA. IT IS EXPECTED THIS EVALUATION WILL BE COMPLETED BEFORE MAY 28, 1997.

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