United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 90-69: Adequacy of Emergency And Essential Lighting

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                     OFFICE OF NUCLEAR REACTOR REGULATION
                            WASHINGTON, D.C.  20555

                               October 31, 1990

Information Notice No. 90-69:  ADEQUACY OF EMERGENCY AND ESSENTIAL 
                                   LIGHTING

Addressees:

All holders of operating licenses or construction permits for nuclear
power  reactors.

Purpose:

This information notice is intended to alert addressees to a possible
problem  concerning the adequacy of emergency and essential lighting at
commercial  power reactor facilities.  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:

On March 3, 1989, Unit 3 at the Palo Verde Nuclear Generating Station 
experienced a reactor/turbine trip, main steam isolation, containment 
isolation, and safety injection as a result of a grid-induced load
rejection  event.  This event included three significant system failures: 
(1) half of  the steam bypass control system malfunctioned; (2) the
atmospheric dump valves  (ADVs) failed to operate from the control room
and the remote shutdown panel;  and (3) the emergency lighting in the main
steam support structure (MSSS)  failed, hampering the operators in their
attempt to cope with the ADV  failures.  Being unable to maintain pressure
control on the secondary side by  operating the ADVs from the control room
or the remote shutdown panel, plant  personnel attempted to establish
local (manual) control of the ADVs in the  MSSS.  When operators first
entered the MSSS, they found no direct lighting.   Normal lighting was
lost due to the loss of power to the non-Class 1E  electrical busses in
the plant.  The emergency lighting was not properly  positioned in the
north MSSS room (containing the ADVs for the No. 1 steam  generator) to
provide adequate lighting for the operators to perform their  required
activities and was not functioning at all in the south MSSS room 
(containing ADVs for the No. 2 steam generator). Because of a burned-out
light  bulb, plant personnel could not restore essential lighting (from
Class 1E  power sources) in the south MSSS room. 

9010250054


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During the NRC inspection (50-530/89-13) conducted by an augmented
inspection  team (AIT) sent to examine the event at Palo Verde, the staff
found  deficiencies in the licensee's maintenance and testing of emergency
and  essential lighting.  The team discovered that plant personnel had
waived the  quarterly preventive maintenance (PM) tasks on the MSSS
emergency and  essential lights for five consecutive quarters.  By
grouping the lights in the  MSSS with the lights in the containment
building, which were inaccessible  during power operations, the PM tasks
were waived for the MSSS lights during  each of these periods along with
the containment lights.  NRC inspections  further revealed that the
licensee, prior to the performance of the 8-hour  lighting unit discharge
test, performed preventive maintenance (i.e., battery  replacement,
addition of electrolyte, cleaning of battery terminals, and  battery
charging) on the lighting unit battery.  This preventive maintenance 
practice resulted in not verifying the performance of the 8-hour emergency 
lighting units in the "as found" condition.  The inspections also revealed 
that the licensee had failed to implement the relevant portions of its
quality  assurance program for emergency lighting.  Because of these
failures, the  emergency lighting was not properly tested, and
deficiencies were not properly  corrected.

After the event, plant personnel reconstructed the design bases of the 
lighting system and conducted walkdown inspections of the emergency and 
essential lighting in the plant.  In some instances, the licensee found
the  lighting to be inadequate to perform the required tasks because the
original  design did not require emergency lights or because the emergency
lights  provided inadequate illumination.  In addition, the licensee
identified many  areas that required the installation of or modification
to lighting to meet  the licensee's design bases and the requirements in
10 CFR Part 50 Appendix R.

Background:

At Palo Verde, the essential lighting system is an integral part of the
normal  lighting system that provides illumination if the normal lighting
system  fails. The essential lighting system is rated non-Class 1E but is
powered from  Class 1E sources.  The system provides lighting in the
control room, in the  shutdown panel area, in the main walkways and
stairs, in the Class 1E  switchgear rooms, in areas having Class 1E
equipment, and in areas used for  the safe shutdown of the reactor.  Upon
loss of the normal lighting system,  the essential lighting system
provides adequate illumination for the safe  shutdown of the reactor.  The
system receives power from two redundant and  independent Class 1E ac
busses.  Each redundant Class 1E ac bus supplies power  to 50 percent of
the essential lighting in the vital areas.  The diesel  generators provide
backup power.


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The emergency lighting system receives dc power from two redundant Class
1E  batteries through inverters and provides illumination for the control
room,  the auxiliary electrical equipment rooms, the stairways, and the
points  leading to plant exits.  The system is normally deenergized and is 
automatically energized upon loss of ac power to the normal system.  The 
emergency lighting system is also composed of 8-hour and 1 1/2-hour 
(individually battery-powered) emergency lighting units.  The 8-hour
emergency  lighting units are designed to meet the technical requirements
of 10 CFR 50  Appendix R, Section III.J which requires that emergency
lighting units with at  least an 8-hour battery power supply be provided
in all areas needed for  operation of safe shutdown equipment and in
access and egress routes thereto.   The 1 1/2-hour emergency lighting
units are installed to meet the requirements  of the Life Safety Code. 
These lighting units are generally installed in  plant locations to
accommodate the safe evacuation of personnel in the event  of a fire in
such areas.

Discussion:

During the Palo Verde event, the inadequate lighting conditions
significantly  complicated the licensee's efforts to cope with the initial
failure of the  ADVs, which delayed the commencement of the controlled
removal of decay heat  as called for by the emergency operating
procedures.

It is important to note that adequate PM and routine testing programs for 
essential and emergency lighting systems are helpful in ensuring adequate 
illumination for the operation of safe shutdown equipment.  Emergency
lighting  is a key fire protection feature associated with supporting
post-fire safe  shutdown operations.  The exercise of good engineering
design practices that  conform to industry standards ensures the ability
of the lighting system to  provide adequate station lighting in all vital
areas during all types of  accident or transient conditions.  The
implementation of an effective PM and  testing program which demonstrates
lighting system operability is important.  Emergency lighting PM programs
recommended by manufacturers generally include  routine monitoring of the
battery condition for each lighting unit, periodic  load testing to verify
that the lighting unit and its associated charger are  functioning
properly, and a periodic "as found" 8-hour lighting unit discharge  test. 
In addition, the Palo Verde event identified that the inadvertent 
repositioning of the emergency lighting fixtures can cause inadequate 
illumination and that routine verification of emergency lighting fixture 
orientation can ensure that emergency lighting is effective.


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This information notice requires no specific action or written response. 
If  you have any questions about the information in this notice, please
contact  one of the technical contacts listed below or the appropriate NRR
project  manager.


                              Charles E. Rossi,  Director
                              Division of Operational Events Assessment 
                              Office of Nuclear Reactor Regulation 


Technical Contacts:  N. K. Trehan, NRR 
                     (301) 492-0777 

                     S. R. Peterson, NRR 
                     (301) 492-3062 

Attachment:  List of Recently Issued NRC Information Notices


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