United States Nuclear Regulatory Commission - Protecting People and the Environment

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
                           WASHINGTON, D.C. 20555

                               March 23, 1987



All nuclear power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 


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 


                                                       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. 


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 

                                                       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 
Page Last Reviewed/Updated Friday, May 22, 2015