Part 21 Report - 1998-290
LICENSEE: DRESSER-RAND
SITE: DRESSER-RAND EN NUMBER:33958
DOCKET: EVENT DATE: 03-20-98
RX TYPE: EVENT TIME: 00:00
VENDORS: NOTIFY DATE: 03-25-98
EMERGENCY CLASS: N/A REGION: 1 STATE: NY TIME: 08:04
OPS OFFICER: LEIGH TROCINE
10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH
10-CFR-PART-21 NOTIFICATION
GOVERNOR VALVE STEMS MADE OF INCONEL-718 MATERIAL WILL EXPAND
MORE THAN THE ORIGINAL 410 STAINLESS STEEL STEMS FOR THE SAME
TEMPERATURE RISE. VALVE ASSEMBLIES THAT STROKE FREELY WHEN
ASSEMBLED BIND OR DRAG AT OPERATING TEMPERATURES. THIS CONDITION
RESULTS IN LOSS OF GOVERNOR CONTROL AND HAS BEEN REPORTED TO HAVE
OCCURRED AT THE FOLLOWING THREE NUCLEAR POWER PLANTS: LIMERICK
(S/N 36691), HOPE CREEK (S/N 37123), AND PERRY (S/N 38176).
ALL REPORTED CONTROL PROBLEMS HAVE BEEN TRACED TO VALVE STEMS
MANUFACTURED BY BW/IP. THE BW/IP MANUFACTURING DRAWING ALLOWS
FOR A DIAMETER OF 0.4980/0.5000", AND THE DRESSER-RAND DRAWINGS
ALLOW 0.4985/0.4990". ANY INCONEL STEM WITH A DIAMETER GREATER
THAT 0.4988" IS SUSCEPTIBLE TO INTERFERENCE WITH THE CARBON
WASHERS AT TEMPERATURES ABOVE 500�F AND COULD RESULT IN TURBINE
CONTROL PROBLEMS. THE PERFORMANCE OF THE DRESSER-RAND INCONEL
STEMS WITH THE CARBON SPACERS IS MARGINAL AT ELEVATED
TEMPERATURES WITH THE MAXIMUM SAFE OPERATING TEMPERATURE BEING
WELL BELOW 600�F.
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