Information Notice No. 81-06: Failure of ITE Model K-600 Circuit Breaker
SSINS No.: 6835
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
March 11, 1981
Information Notice No. 81-06: FAILURE OF ITE MODEL K-600 CIRCUIT BREAKER
The purpose of this information notice is to provide early notification of a
matter that could adversely affect the safety of nuclear power plants.
Toward this end, this information notice alerts holders of operating
licenses and construction permits of a possibly generic deficiency involving
Model K-600 circuit breakers manufactured by ITE.
Description of Circumstance:
By letter dated February 20, 1981, the Sacramento Municipal Utility District
informed us that, while performing preventive maintenance on electrical
circuit breakers at its Rancho Seco facility, an ITE Model K-600 breaker was
observed not to trip. An investigation revealed that a tripping coil wire
had slipped out of its terminal. Further examinations revealed that the coil
wire size was AWG 20, whereas the mating lug was sized for AWG 16-14 wire. A
check of other ITE electrical breakers indicated that the problem may be
generic. Subsequent to the letter, the Sacramento Municipal Utility District
informed us orally that ITE Model K-1600 breakers have the same deficiency
and that Model K-3000 breakers may be similarly affected.
The information provided by the Sacramento Municipal Utility District is
preliminary and will be followed by a complete report. Consequently, we have
not yet evaluated the safety significance of this event. Nevertheless, the
information herein is being provided as an early notification of a possibly
significant event. Although no specific action or response is requested at
this time, recipients should review the information for possible
applicability to their facilities. If NRC evaluations so indicate, further
licensee actions may be requested.
If you have any question regarding the information contained herein, please
contact the Director of the appropriate NRC Regional Office.
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