ML20132C075
| ML20132C075 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/13/1996 |
| From: | Lipuralo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-96 NSD-SRC-96-036, NSD-SRC-96-36, NUDOCS 9612180108 | |
| Download: ML20132C075 (4) | |
Text
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.DEC 13 '96 14:25 FR (to OPL LICENSING 412 374 4011 TO 813018165151 P.02/03 i
Westinghouse Energy Systerns Nuam suces Division Electric Corporation po,, 833 PinsDutgh Pennsylvania 15230 0855 i
NSD-SRC-96.036 December 13, 1996 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 l
Attention: NRC Operations Center
SUBJECT:
NOTIFICATION OF THE POTENTIAL EXISTENCE OF DEFECTS PURSUANT TO 10CFR 21.21 Westinghouse has identified defects that could create a substantial safety hazard should the defect remain uncorrected.
Backcrou_nd 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-ofrswitch to remove the shunt trip coil from the power source subsequent to tripping the breaker. The coil is not designed for continuous duty and 1
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 trip barriers that provide protection against damage due to arcing were missing.
Evaluation
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Investigation by the vendor (Cutler Hammer) has determined that the six circuit breakers supplied only
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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 basker on demand. However, the cut-off switch would not cperate properly and the shunt trip coil would be damaged and unable to perform upon the next demand.
b[p TEo bitaker 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 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 cperability of these,bga);ey,qfler a trip has not been determined by Cutler Hammer.
9612180108 961213 PDR ADOCK 05000483 S
PDR mm.r sm.,
, DEC 13 '96 14:25 FR CW) OPL LICENSING 412 374 4011 TO 813018165151 P.03/03 Document Control Desk Pags 2
- NSD SRC-96-036 December 13,1996 Safety Sinnificance Westinghouse is retely informed of the application of devices such as molded case circuit breakers.
However, the device was supplied as 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 failures. However, this would not be acceptable if these breakers were installed in redundant circuit applications.
l Plant Anolicability 1
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 barner 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 Cutler Hammer will be additional training on correct shunt trip unit installation.
If you have any questions regarding the notification, please call H. A. Sepp of my staff at (412) 374 5282.
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i Very truly yours, 1
N. J. Liparulo, Manager Engineering 1334xWrw!N jas
y Ed%3 GENERAL INFORMATION or OTHER EVENT NUMBER:
31449 j
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 i
LICENSE #:
AGREEMENT: N EVENT TIME:
00:00(EST)
DOCKET:
LAST UPDATE DATE:
12/13/96 NOTIFICATIONS i
NRC NOTIFIED BY: N. J. LIPARULO VERN HODGE, RVIB NRR HQ OPS OFFICER:
LEIGH TROCINE 1
EMERGENCY CLASS: NOT APPLICABLE 10 CFR SEC. TION:
CCCC 21.23 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 i
COIL FROM THE POWER SOURCE SUBSEQUENT TO TRIPPING THE BREAKER.
THE COIL IS l
NOT DESIGNED FOR CONTINUOUS DUTY AND WOULD EVENTUALLY OPEN THE CIRCUIT IF j
IT REMAINED ENERGIZED.
THE SHUNT TRIP COIL OF THE BREAKERS SUPPLIED TO 1
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 ARCIMG.
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.
i 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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i Our fax number is (412) 374-4011 (WIN 284 4011)
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