Information Notice No. 85-93: Westinghouse Type DS Circuit Breakers, Potential Failure of Electric Closing Feature Because of Broken Spring Release Latch Lever
SSINS No. 6835
IN 85-93
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
December 6, 1985
Information Notice No. 85-93: WESTINGHOUSE TYPE DS CIRCUIT BREAKERS,
POTENTIAL FAILURE OF ELECTRIC CLOSING
FEATURE BECAUSE OF BROKEN SPRING RELEASE
LATCH LEVER
Addressees:
All nuclear Power reactor facilities holding an operating license (OL) or a
construction permit (CP).
Purpose:
This information notice is to alert licensees that the electric circuit
breaker closing function of Westinghouse Type DS circuit breakers could
possibly malfunction because of a broken spring release latch lever. It is
expected that licensees will review the information for applicability to
their facilities and if the defect exists, consider actions to determine
safety significance and corrective action. However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances:
On April 14, 1985, the Westinghouse Nuclear Services Integration Division
(NSID) issued Technical Bulletin No. NSID-TB-85-17 advising their customers
of a potential malfunction in Westinghouse Type DS Class 1E circuit breakers
because of broken spring release latch levers. These electrically operated
type DS breakers will not close electrically when the spring release latch
lever has been broken off. Twenty-five broken levers have been reported and
evaluated. This evaluation shows concentrations of incidents traceable to
manufacturing in the following periods of time: early 1975, April 1976, and
early 1978.
This circuit breaker failure, as discussed, adversely affects the safety
function (closing on demand) when the circuit breaker is used in the
Engineered Safety Features Systems. However, this failure mode will not
affect the safety trip function when it is used in the reactor protection
system.
Discussion:
The April 14, 1985 Technical Bulletin recommends the following corrective
actions for DS Class 1E circuit breakers: (I) advise the responsible
personnel that the breaker may be closed manually using the operator on the
front panel of the breaker cubicle, if electrical closing does not occur on
demand; (2) for applications other than Westinghouse-designed reactor trip
(RT) function, the
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IN 85-93
December 5, 1985
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user should evaluate the situation to determine if this condition could
affect safety; and (3) inspect the latch lever during normal scheduled
maintenance/inspection of the DS circuit breaker.
The DS Class 1E circuit breakers also are used in plants not designed by
Westinghouse. Some of these facilities may not have received Technical
Bulletin No. NSID-TB-85-17, therefore, it is suggested that these facilities
contact Westinghouse NSID to obtain additional information on performing the
inspections and corrective action.
No specific action or written response is required by this notice. If you
have any questions regarding this notice, please contact the Regional
Administrator of the appropriate NRC regional office or this office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: L. B. Parker, IE
(301) 492-7190
Attachment: List of Recently Issued IE Information Notices
Page Last Reviewed/Updated Tuesday, March 09, 2021