Information Notice No. 88-05: Fire in Annunciator Control Cabinets
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
February 12, 1988
Information Notice No. 88-05: FIRE IN ANNUNCIATOR CONTROL CABINETS
All holders of operating licenses or construction permits for nuclear power
This information notice is being provided to inform addressees of three oc-
currences of electrical fires in annunciator control panels supplied by
Electro Devices, Inc. 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:
Recently, electrical fires have occurred in remote cabinets containing
multiple circuit cards for the control of visual and audible annunciator
functions in the main control rooms at three nuclear power plants. The
annunciator systems for the three plants were provided by Electro Devices,
Inc. of St. Louis, Missouri.
On January 28, 1988, while Beaver Valley 2 was in cold shutdown, all control
room annunciator alarms were lost. A small fire was detected in a remote an-
nunciator control cabinet, and it was immediately extinguished by the two
operators who had been dispatched to investigate. Plant parameters were
available throughout the event from other control room instruments and the
safety parameter display system. Because of the sustained loss of the
annunciators, the licensee declared an alert in accordance with the plant
emergency plan. Damaged solid state cards were removed, annunciator
capability was restored, and the alert was terminated. The root cause of the
fire is under investigation.
On February 1, 1988, while Calvert Cliffs Unit 2 was operating at 100% power,
an alert was declared because all control room annunciator alarms were lost.
The complete loss of the annunciator system resulted from a fire in a remote
control cabinet that provides audible and visual alarm functions for the main
control room. The operators were alerted to the fire by the actuation of the
automatic fire protection system. The visual indication function of all
control room annunciator panels was out of service for 2 hours, and the
audible function was not restored for two days. The root cause of the fire is
under investigation; however the licensee intends to review the adequacy of
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February 12, 1988
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(sub-fusing of branch circuits within the annunciator system) to determine if
this contributed to the occurrence of the fire. The unit remained at 100%
power throughout the event.
On February 8, 1988, while Rancho Seco was in cold shutdown, all control room
annunciator alarms were lost because of a fire in a remote control cabinet
that provides audible and visual control functions to the annunciator system.
The fire is believed to have originated from a failed subcomponent on a solid
state circuit card. The root cause of the fire is under investigation.
Although the NRC's investigation of these events is not yet complete, the
following similarities among the events are noteworthy:
. The annunciator systems were provided by the same manufacturer.
. Common to each event was the licensee's lack of specific emergency
procedures to address complete loss of the annunciator system.
. None of the licensees have provisions for monitoring ambient temperatures
in the control cabinets.
. In the events at Calvert Cliffs and Rancho Seco, the fire teams
experienced nausea and dizziness, apparently as a result of inadequate
oxygen in the area in which the fire occurred. Licensees thus may wish
to review their procedures for fighting small fires in confined areas to
determine the adequacy of personnel protection and the need to specify
the use of breathing apparatus.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact: V. D. Thomas, NRR
E. N. Fields, NRR
Attachment: List of Recently Issued NRC Information Notices
Page Last Reviewed/Updated Friday, May 22, 2015