Information Notice No. 87-14:Actuation of Fire Suppression System Causing Inoperability of Safety-Related Ventilation Equipment
SSINS No.:6835
IN 87-14
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
March 23, 1987
Information Notice No. 87-14: ACTUATION OF FIRE SUPPRESSION SYSTEM CAUSING
INOPERABILITY OF SAFETY-RELATED VENTILATION
EQUIPMENT
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or a
construction permit (CP).
Purpose:
This notice is to alert recipients to a potential generic problem involving
operator errors and single- and common-cause failures that initiate fire
suppression systems and cause the inoperability of safety-related systems.
We expect that recipients will review the information for applicability to
their facilities and consider actions, if appropriate, to preclude similar
problems from occurring at their facilities. However, suggestions contained.
in this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances:
In June 1983 the NRC issued Information Notice (IN) 83-41. The purpose of
that notice was to alert licensees to several reported events during which
fire suppression systems actuation resulted in the inoperability of
safety-related systems. A continuing series of events indicate that the
concerns addressed by IN 83-41 are not resolved.
On October 15, 1986, at Duane Arnold, testing of the deluge system
temperature sensors resulted in wetting of the charcoal in both trains of
the control room ventilation system. Although procedures called for
isolation of the water supply before testing the sensors, the procedures
failed to require that the control valves be reset before reopening the
supply valve.
On August 27, 1986, the licensee for Pilgrim Nuclear Power Station Unit 1
determined that automatic or manual initiation of the standby gas treatment
(SBGT) system deluge fire suppression system would result in the charcoal
beds of one train becoming water soaked. Since the Pilgrim SBGT system's
redundant trains are cross-connected via pneumatic normally open/fail open
dampers, a deluge system actuation without operator action to close the
cross connect dampers will result in a complete loss of SBGT system
operability.
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IN 87-14
March 23, 1987
Page 2 of 3
On May 19, 1985, personnel at Hatch Unit 1 observed water falling from a
control room heating ventilation and air conditioning (HVAC) vent onto an
analog transmitter trip system panel in the control room. The water was from
the control room HVAC filter train deluge system which had been
inadvertently activated as a result of unrelated maintenance activities (See
Information Notice 85-85). The water resulted in the lifting of a safety
relief valve four times. The valve stuck open on the fourth cycle,
initiating a severe transient. Moisture also energized the high pressure
coolant injection (HPCI) trip solenoid making the HPCI inoperable for vessel
makeup during part of this event.
On April 4, 1984, construction workers at the Cooper Nuclear Power Station
sheared a hydrant from the fire protection system. When the hydrant was
isolated and the system repressurized, a water hammer forced the SBGT system
fire suppression deluge valves open, flooding the charcoal filters. Both
trains of SBGT were rendered inoperable.
On March 21, 1984, a pressure transient in the firewater system (that was
caused by a false initiation elsewhere in the plant) momentarily opened the
deluge valves for both SBGT system trains at WNP2. One valve did not reseat
properly. Similar events involving only one train occurred on April 4 and 27
of the same year.
On March 24, 1983, incorrect installation of a new control valve in the fire
suppression deluge system for one SBGT train at Pilgrim Nuclear Power
Station resulted in the loss of the train. The deluge system was not tested
after modification and the valve leaked as a result of the installation
error. As discussed above, because the Pilgrim SBGT system design and
operational configuration includes normally open cross connection dampers,
the continued operability of the redundant SGTS train was threatened.
Discussion:
Events such as those described above are of particular concern, not only
because of their impact on systems that are required for accident
mitigation, but also because of the special fire safety problem presented by
dry charcoal that has been wetted (i.e., lower ignition temperature) and
because of water damage to other safety systems. General Design Criterion 3
(Fire Protection) of Appendix A to 10 CFR Part 50 states in part: "Fire
detection and fighting systems of appropriate capacity and capability shall
be provided and designed to minimize the adverse effects of fires on
structures, systems and components important to safety. Fire fighting
systems shall be designed to ensure that their rupture or inadvertent
operation does not significantly impair the safety capability of these
structures, systems and components." Appendix R to 10 CFR Part 50 requires
that a fire hazard analysis be performed to assess the probability and
consequences of fires in each utilization facility. This analysis should
include the effects of inadvertent operation or leaks in moderate energy
lines of the fire suppression system. The events reported in this notice
subsequent to IN 83-41 indicate that the problem has not been fully
resolved.
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IN 87-14
March 23, 1987
Page 3 of 3
To date, none of the reported events have resulted in a serious impact on
the health and safety of the public. However, each instance cited above
could lead to much more serious consequences given a valid demand for the
safety systems that were damaged by the event.
Although no written response to this notice is required, it is suggested
that holders of OLs or CPs review the information In this notice for
applicability at their facilities. The specific events cited occurred at
BWRs, but our concern is not limited to BWRs. For example, Supplement 2 to
Information Notice 86-106 describes actuation of the carbon dioxide fire
suppression system at the Surry Power Station as a result of water entering
the control panels through the ends of several open conduits. This resulted
in carbon dioxide, entering the control room, causing shortness of breath,
dizziness, and nausea of some personnel.
Because of the recurring failures such as those discussed above, NRC's
evaluation of this problem is continuing. Specifically, AEOD is currently
evaluating the safety significance of a number of inadvertent actuations of
fire suppression systems at operating plants. Depending on the results of
the evaluation, further information will be published and/or specific
actions may be requested. If you have any questions regarding this matter,
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: R. F. Scholl, NRR
(301) 492-8443
J. B. Henderson, IE
(301) 492-9654
Attachment: List of Recently Issued IE Information Notices
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