Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
March 15, 1989
Information Notice No. 89-29: POTENTIAL FAILURE OF ASEA BROWN BOVERI
CIRCUIT BREAKERS DURING SEISMIC EVENT
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice is being provided to alert addressees to potential
failures of ASEA Brown Boveri (ABB) K-Line circuit breakers (CBs) during a
seismic event. It is expected that recipients will review the information for
applicability to their facilities and consider actions, as appropriate, to
avoid similar problems. However, suggestions contained in this information
notice do not constitute NRC requirements; therefore, no specific action or
written response is required.
Description of Circumstances:
ABB submitted two letters, dated January 13 and February 16, 1989, to the NRC
in accordance with the requirements of 10 CFR Part 21 regarding a deficiency
in K-Line CBs, model numbers K-225 through K-2000, that were delivered to cus-
tomers before July 1974. These CBs have a slow-close lever that could move
during a seismic event and prevent the CBs from closing upon an electrical
demand. The slow-close lever is used to perform diagnostic checks on the
CB internals during initial installation. The lever is located in the rear
portion of the CB and is only accessible while the CB is out of its cubicle.
Discussion:
In late 1988, Rancho Seco personnel asked ABB why some K-Line CBs used at the
Rancho Seco plant had springs on the slow-close lever and others did not. ABB
investigated the matter and determined that rebound springs were added to CBs
manufactured after July 1974 as a response to CB failures that occurred during
seismic testing of K-Line CBs.
The seismic testing was conducted on several sample K-Line CBs at Wyle Labora-
tories in 1974 and consisted of 123 test runs under varying seismic conditions.
During test run number 100 (which consisted of side-to-side sine dwell at 23
hertz, amplitude 0.5 g, duration greater than 20 seconds), one K-1600 CB jammed
and failed to close on demand. During test run number 101 (which consisted of
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.. IN 89-29
March 15, 1989
Page 2 of 2
side-to-side sine dwell at 30 hertz, amplitude 0.36 g, duration greater than
20 seconds), a second K-1600 CB failed to close on demand. The causes of the
breaker malfunctions were not immediately recognized. ABB later determined
that the CBs had failed to close because of vibration-induced movement of the
slow-close lever to a position where it interfered with the closing mechanism
of the CB. As a result, a rebound spring that prevents any undesired movement
of the slow close lever was added to the CB design and installed in all CBs
manufactured after mid-1974.
ABB sent the letters of January 13 and February 16, 1989, to all nuclear power
plants that have purchased safety-related electrically operated K-Line CBs,
model numbers K-225 through K-2000, and requested that all users of these
CBs add rebound springs to the slow-close levers. The letters are included
as Attachment 1 and Attachment 2 respectively. Attachment 1 also includes
a sketch of the location of the slow-close lever with the rebound spring in
place and the field installation procedures for adding the rebound spring
to the slow-close lever. Additional information on this subject may be
obtained by contacting the appropriate ABB representative.
It is important for addressees to determine whether any of the subject CBs,
regardless of their delivery or installation date, are installed at their
facilities and to verify that the CBs are seismically qualified.
In addition, addressees are reminded that component manufacturers do not
typically notify customers who have procured commercial grade items of design
changes and deficiencies identified in their components. Therefore, it is
important that this fact be considered when purchasing components that were
procured as commercial grade and dedicated for safety-related applications
by entities other than the component manufacturer.
No specific action or written response is required by this information notice.
If you have any questions regarding this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact: Jaime Guillen, NRR
(301) 492-1170
Attachments:
1. ASEA Brown Boveri Letter dated January 13, 1989
2. ASEA Brown Boveri Letter dated February 16, 1989
3. List of Recently Issued NRC Information Notices
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IN 89-29
March 15, 1989
Page 1 of 1
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________
Information Date of
Notice No._____Subject_______________________Issuance_______Issued to________
89-28 Weight and Center of 3/14/89 All holders of OLs
Gravity Discrepancies or CPs for nuclear
for Copes-Vulcan power reactors.
Air-Operated Valves
89-27 Limitations on the Use 3/8/89 All holders of OLs
of Waste Forms and High or CPs for nuclear
Integrity Containers for power reactors,
the Disposal of Low-Level fuel cycle
Radioactive Waste licenses and
certain by-product
materials licenses.
89-26 Instrument Air Supply to 3/7/89 All holders of OLs
Safety-Related Equipment or CPs for nuclear
power reactors.
89-25 Unauthorized Transfer of 3/7/89 All U.S. NRC source,
Ownership or Control of byproduct, and
Licensed Activities special nuclear
material
licensees.
89-24 Nuclear Criticality Safety 3/6/89 All fuel cycle
licensees and other
licensees
possessing more
than critical
mass quantities of
special nuclear
material.
89-23 Environmental Qualification 3/3/89 All holders of OLs
of Litton-Veam CIR Series or CPs for nuclear
Electrical Connectors power reactors.
89-22 Questionable Certification 3/3/89 All holders of OLs
of Fasteners or CPs for nuclear
power reactors.
89-21 Changes in Performance 2/27/89 All holders of OLs
Characteristics of Molded- or CPs for nuclear
Case Circuit Breakers power reactors.
__________________________________________________________________________________
OL = Operating License
CP = Construction Permit
..
