Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
LICENSEE: NORTHEAST UTILITIES
SITE: MILLSTONE 3 EN NUMBER:31371
DOCKET: 05000423 EVENT DATE: 09-25-96
RX TYPE: PWR EVENT TIME: 00:00
VENDORS: W-4-LP NOTIFY DATE: 11-22-96
EMERGENCY CLASS: N/A REGION: 1 STATE: CT TIME: 14:05
OPS OFFICER: STEVE SANDIN
10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH
UNIT SCRAM RX INIT INITIAL MODE CURR CURRENT MODE
CODE CRIT PWR PWR
3 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN
THE LICENSEE IS MAKING A PART 21 NOTIFICATION.
"IN ACCORDANCE WITH 10 CFR 21.21(d)(3)(i), NORTHEAST NUCLEAR
ENERGY COMPANY (NNECO) IS PROVIDING NOTIFICATION TO THE NRC VIA
THIS FACSIMILE AND CONCURRENT TELEPHONE CONVERSATION, REGARDING A
POTENTIAL SIGNIFICANT SAFETY HAZARD (SSH) IDENTIFIED AT MILLSTONE
STATION.
"FIFTEEN DIFFERENT FUSE TYPES FROM THREE DIFFERENT MANUFACTURERS
(GOULD-SHAWMUT, BUSSMAN, AND CEFCO) WERE FOUND TO HAVE AXIAL
CRACKS. THE CRACKS OCCURRED AS A RESULT OF THE BRASS FERRULE
RELIEVING INTERNAL STRESS.
"DURING COMMUNICATIONS WITH MANUFACTURERS, IT WAS DETERMINED
THAT
THESE DEFECTS HAVE BEEN PRESENT WITHIN THE FUSE INDUSTRY FOR MANY
YEARS AND THAT FUSES MANUFACTURED WITH BRASS ARE SUSCEPTIBLE TO
THIS DEFECT.
"NNECO DETERMINED THAT FUNCTIONAL TESTING SHOULD BE PERFORMED ON
A SAMPLE OF THE FUSES. THE RESULTS FROM THE TESTING INDICATED
THAT THE FUSES MET THEIR INTENDED FUNCTION OF INTERRUPTING THE
CURRENT, HOWEVER TEN OUT OF FORTY SIX FUSES HAD FERRULES
PHYSICALLY BLOW OFF THE END. THE FOLLOWING IS A LIST OF THOSE
FUSES THAT THE FERRULE(S) CAME OFF THE END:
GOULD-SHAWMUT
A6Y2 TYPE II, 10KA IR
A6Y5, 200KA IR
TRM25, 10KA IR
A4J10, 200KA IR (2)
BUSSMAN
FRN12, 200KA IR
FRN-R25, 200KA IR
FRN-R30, 200KA IR
FRN-R35, 200KA IR
FRN-R60, 200KA IR"
"CONCLUSION:
THE CRACKS COULD RESULT IN A LOSS OF SAFETY-RELATED EQUIPMENT DUE
TO THE FERRULE COMING OFF OF THE FUSE, WHICH COULD THEN SHORT OUT
OR DAMAGE OTHER SAFETY-RELATED ELECTRICAL DISTRIBUTION. THIS
COULD BE A SSH CONCERN THAT SHOULD BE REPORTED THROUGH 10CFR21,
WITH NOTIFICATION TO OTHER UTILITIES DUE TO THE GENERIC NATURE OF
THE BASIC COMPONENT.
"IN ACCORDANCE WITH 10CFR 21.21(d)(3)(ii), A WRITTEN REPORT WILL
BE PROVIDED WITHIN 30 DAYS."
