Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
ACCESSION #: 9612180108
Westinghouse Energy Systems Nuclear Services Division
Electric Corporation
PO Box 899
Pittsburgh, Pennsylvania
15320-0855
NSD-SRC-96-036
December 13, 1996
Document Control Desk
U. S. Nuclear Regulatory Commission
Washington, DC 20555-0001
Attention: NRC Operation Center
SUBJECT: NOTIFICATION OF THE POTENTIAL EXISTENCE OF DEFECTS PURSUANT
TO
10CFR21.21
Westinghouse, has identified defects that could create a substantial
safety hazard should the defect remain uncorrected.
Background
A deviation was determined by Callaway Nuclear Plant during testing of
six type HFD3045 and HFD3060 molded case circuit breakers with 125 VDC
shunt trip devices supplied as safety related by Westinghouse. The shunt
trip circuitry is specified to be equipped with a cut-off switch to
remove the shunt trip coil from the power source subsequent to tripping
the breaker. The coil is not designed for continuous duty and would
eventually open circuit if it remained energized. The shunt trip coil of
the breakers supplied to Callaway remained connected to the power source
after the breaker tripped. In addition, it was determined when
evaluating returned breakers from Callaway, That shunt barriers that
provide protection against damage due to arcing were missing.
Evaluation
Investigation by the vendor (Cutler Hammer) has determined that the six
circuit breakers supplied only to Callaway were tested by the same
technician using the wrong test procedure. The shunt trip units were
installed incorrectly but would still trip the breaker demand. However,
the cut-off switch would not operate properly and the shunt trip coil
would be damaged and unable to perform upon the next demand. The breaker
could be reset and the damaged coil would not be detected until the next
surveillance. Records at Cutler Hammer show that this technician only
tested these six breakers, therefore no suspect breakers are in service.
Cutler Hammer has concluded that a recent change in the facilities that
installed the shunt trip units led to the missing shunt trip barriers.
Since the change in the facilities, 21 breakers with either AC or DC
shunt trip units (including the six above) have been shipped, again only
to Callaway Nuclear Plant. Subsequent operability of these breakers
after a trip has not been determined by Cutler Hammer.
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Document Control Desk
Page 2
NSD-SRC-96-036
December 13, 1996
Safety Significance
Westinghouse is rarely informed of the application of device such as
molded case circuit breakers. However, the device was supplied a safety
related and the utility has indicated that if damage to the shunt trip
circuitry was not detected it could potentially represent a substantial
safety hazard. Any damage subsequent to a trip would be detected at the
next surveillance interval, which would be acceptable for random failure.
However, this would not be acceptable if these breakers was installed in
redundant circuit applications.
Plant Applicability
Callaway
Recommendations/Corrective Actions
All six (6) of the breakers with incorrectly installed DC shunt trip
units have been identified (none in service) and are in the process of
being returned to the vendor. Therefore, no recommendations to the
utility are required. Corrective action at Cutler Hammer consisted of
additional training of the technician regarding correct testing and
installation practices.
Westinghouse has been informed by Callaway that only one breaker with a
suspect barrier is in service. The remaining fourteen (14) breakers will
not be placed in service until it is verified that the shunt trip
barriers are installed. Since subsequent operability of shunt trip units
with missing barriers is indeterminate, Callaway will be advised to
perform a surveillance test after any breaker trip demand until the
breaker can be corrected or replaced. Corrective action at Cadet Hammer
will be additional training an correct shunt trip unit installation.
If you have any questions regarding the notification, piano call H. A.
Sepp of my staff at (412) 374-5292.
Very truly yours,
N. J. Liparulo, Manager
Engineering
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GENERAL INFORMATION or OTHER EVENT NUMBER: 31449
LICENSEE: WESTINGHOUSE ELECTRIC CORPORATION NOTIFICATION DATE:
12/13/96
CITY: PITTSBURGH REGION: 1 NOTIFICATION TIME: 14:22[ET]
COUNTY: STATE: PA EVENT DATE: 12/13/96
LICENSE#: AGREEMENT: N EVENT TIME: 00:00 [EST]
DOCKET: LAST UPDATE DATE: 12/13/96
NOTIFICATIONS
NRC NOTIFIED BY: N. J. LIPARULO VERN HODGE, RVIB NRR
HQ OPS OFFICER: LEIGH TROCINE
EMERGENCY CLASS: NOT APPLICABLE
10 CFR SECTION:
CCCC 21.21 UNSPECIFIED PARAGRAPH
EVENT TEXT
MOLDED CASE CIRCUIT BREAKERS WITH INCORRECTLY INSTALLED DC SHUNT
TRIP
UNITS AND MISSING SHUNT TRIP BARRIERS
CALLAWAY IDENTIFIED A DEVIATION DURING TESTING OF 6 TYPE HFD3045 AND
HFD3060 MOLDED CASE CIRCUIT BREAKERS WITH 125-VOLT DC SHUNT TRIP
DEVICES
SUPPLIED AS SAFETY-RELATED BY WESTINGHOUSE. THE SHUNT TRIP
CIRCUITRY IS
SPECIFIED TO BE EQUIPPED WITH A CUT-OFF SWITCH TO REMOVE THE SHUNT
TRIP
COIL FROM THE POWER SOURCE SUBSEQUENT TO TRIPPING THE BREAKER. THE
COIL
IS NOT DESIGNED FOR CONTINUOUS DUTY AND WOULD EVENTUALLY OPEN THE
CIRCUIT
IF IT REMAINED ENERGIZED. THE SHUNT TRIP COIL OF THE BREAKERS SUPPLIED
TO CALLAWAY REMAINED CONNECTED TO THE POWER SOURCE AFTER THE
BREAKER
TRIPPED. IN ADDITION, DURING THE EVALUATION OF THE BREAKERS THAT
WERE
RETURNED FROM CALLAWAY, IT WAS DETERMINED THAT SHUNT TRIP
BARRIERS WERE
MISSING. THESE BARRIERS PROVIDE PROTECTION AGAINST DAMAGE DUE TO
ARCING.
THE VENDOR (CUTLER HAMMER) DETERMINED THAT 21 BREAKERS WITH EITHER
AC OR
DC SHUNT TRIP UNITS (INCLUDING THE 6 REFERENCED ABOVE) HAD BEEN
SHIPPED
ONLY TO THE CALLAWAY PLANT. SUBSEQUENT OPERABILITY OF THESE
BREAKERS
AFTER A TRIP HAS NOT YET BEEN DETERMINED BY CUTLER HAMMER.
ALL SIX OF THE BREAKERS WITH INCORRECTLY INSTALLED DC SHUNT TRIP
UNITS
HAVE BEEN IDENTIFIED AND ARE IN THE PROCESS OF BEING RETURNED TO THE
VENDOR. WESTINGHOUSE HAS ALSO BEEN INFORMED BY CALLAWAY THAT
ONLY ONE
BREAKER WITH A SUSPECT BARRIER IS IN SERVICE. CALLAWAY DOES NOT PLAN
TO
PLACE THE REMAINING FOURTEEN BREAKERS IN SERVICE UNTIL IT IS VERIFIED
THAT THE SHUNT TRIP BARRIERS ARE INSTALLED. SINCE SUBSEQUENT
OPERABILITY
OF THE SHUNT TRIP UNITS WITH MISSING BARRIERS IS INDETERMINATE,
CALLAWAY
WILL BE ADVISED TO PERFORM A SURVEILLANCE TEST AFTER ANY BREAKER
TRIP
DEMAND UNTIL THE BREAKER CAN BE CORRECTED OR REPLACED.
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