Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
LICENSEE: COOPER ENERGY SERVICES
SITE: COOPER ENERGY SERVICES EN NUMBER:33398
DOCKET: EVENT DATE: 12-12-97
RX TYPE: EVENT TIME: 15:30
VENDORS: NOTIFY DATE: 12-12-97
EMERGENCY CLASS: N/A REGION: 1 STATE: PA TIME: 15:30
OPS OFFICER: JOHN MacKINNON
10 CFR SECTION: CDEG 21.21(c)(3)(i) DEFECTS/NONCOMPLIANCE
10 CFR 21 NOTIFICATION, ENTERPRISE DSR-4 AND DSRV-4 EMERGENCY
DIESEL GENERATOR ADJUSTING SCREW FAILURE.
ON SEPTEMBER 26, 1997, ENTERGY OPERATIONS RIVER BEND STATION
REPORTED THE FAILURE OF AN ADJUSTING SCREW, COOPER ENERGY
SERVICES PART NUMBER 1A-7840. THE ADJUSTING SCREW IS A BALL AND
SWIVEL ASSEMBLY UTILIZED TO ALLOW FOR ANGULAR MOVEMENT BETWEEN
THE ROCKER ARM AND INTAKE AND EXHAUST VALVE STEM OF THE POWER
CYLINDER HEAD. THE ADJUSTING SCREW IS ASSEMBLED BY SWAGING A
"SWIVEL PAD" ON TO A "BALL".
SUBSEQUENT INVESTIGATION DETERMINED THAT THE SWAGING PROCESS AND
TOOLING WAS OF A DESIGN THAT ALLOWED FOR "OVERSWAGING" OF THE
PAD, REDUCING THE AMOUNT OF FREE ANGULAR MOVEMENT IN THE
ASSEMBLY. THIS CONDITION POTENTIALLY CAUSED THE MATERIAL OF THE
UPPER EDGE OF THE SWIVEL PAD TO BE OVER STRESSED, AND/OR LIMIT
THE ABILITY OF THE ASSEMBLY TO ACCOMMODATE THE REQUIRED ANGULAR
MOVEMENT WITH UNDUE STRESS.
THE FAILURE OF THE ASSEMBLY WAS THE CRACKING OF THE SWIVEL PAD
MATERIAL AT THE UPPER EDGE. THIS FAILURE HAS THE POTENTIAL TO
CAUSE AN OPERABILITY CONCERN DUE TO THE ASSEMBLY SEPARATING AND
EXCESS CLEARANCE (VALVE LASH) BEING ESTABLISHED WHICH COULD LEAD
TO CATASTROPHIC FAILURE OF THE VALVE STEM OR REMAINING BALL
PORTION OF THE ASSEMBLY. MULTIPLE FAILURES OF THE ASSEMBLY
WITHOUT CATASTROPHIC FAILURE COULD ALSO REDUCE ENGINE OUTPUT DUE
TO DECREASED VALVE LIFT. IN ADDITION, LOOSE PIECES OF THE
ASSEMBLY COULD CAUSE SECONDARY DAMAGE IN THE ENGINE.
COOPER ENERGY SERVICES HAS SUPPLIED THE 1A-7840 ADJUSTING SCREW
TO THE FOLLOWING SITES: RIVER BEND, CATAWBA, AND KORI 3 & 4
(KOREA ELECTRIC).
CORRECTIVE ACTION:
THE SUBJECT ASSEMBLIES AT RIVER BEND STATION HAVE BEEN REPLACED
WITH ACCEPTABLE ASSEMBLIES.
THE SWAGING TOOLING HAS BEEN CORRECTED TO LIMIT THE AMOUNT OF
"SWAGE". ACCEPTANCE CRITERIA ASSURING THE NECESSARY FREEDOM OF
THE ASSEMBLY HAS BEEN DEFINED AND WILL BE VERIFIED DURING
MANUFACTURE.
USER RECOMMENDATIONS:
UTILITIES CURRENTLY IN POSSESSION OF 1A-7840 ASSEMBLIES ARE
INSTRUCTED TO VERIFY THAT A MINIMUM OF 18 DEGREES OF ANGULAR
MOVEMENT FROM CENTERLINE IS AVAILABLE IN ALL DIRECTIONS, WITH NO
INDICATION OF ROUGHNESS WHEN MOVING.
