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BASES
REOUIKE E> LCO 3.3 will noc be met if the Automatic Plenum Deiuw Svstem is not
ACTION A.2 OPERABLE in the Building 391 FEVS Dlenuin. The abseiiccz of the deluge
svstem function in the Building 99i FEVS plenum pro.;ides the potential for 3
large faCi1it.i. fire to ininact the Building 991 FEW filters. The Automatic Plenum
Deluge Svstem functions to cool the air entering the denum andior to suppress
hot ernbers and flving brands from igniting the HEPA filters. Without the deluge
function. the likelihood of large fires in the facility intDactiw the filters in die
plenum is increased. The facility is .still urotected if the ddon of the not
OPERABLE confieuntion is decreased sficientlv to offset the increased
likelihood of large h s imuacting the HEPA fdters.
Revision 1
September 1999
If the Automatic Plenum Deluge Svstem is not OPERABLE. the facility shall
restore the function withim 45 days. The restomion of the fiiint+ou within 3
limited time Deriod is a measure to limit the likelihood of fire initision in the
facilitv imDacting the HEPA filters. REOLWD ACTION A.l is identified to
Educe the likelihood of Ime f i initiation ~ during, the time taken to restore the
Automatic Plenum Deluge Svstem.
The 45 dav COMPLETION TIME associated with the rzstoration of the plenum
deluge function provides adequate time for faciliw manaeenient to repair maw of
the delwe wstem Gled confieurations. Readilv available spare uar~s can be
obtained and simule remidmaintenance actikities can be conducted within the
45 day ueriod.
The 45dav COMPLETION TIME does not result in undue risk due the low
likelihood of the Automaric Plenum Deluge Svstem ever beinn needed or used
Fires large enough to imuact the filters in the ventilation system are not considered
to be credible in the sdetv analysis: however. the delwe svsteni is included as 3
mitigative featzlre to Drovide DEFEVSE-IN-DEPTH Droixtion against the
possibilitv of manahzed situations leadinp to a iae fire. In addition. the
possibilitv of hot ember and fl\ins brand ca~ture bv the HEPA filters during
smaller fires does exist. Therefore. the duntion of time for the function beine not
OPERABLE should be limited and is set at 45 days due to the lower likelihood of
svstern use. D ~ C U I given ~ I ~ the termination of hot work as rewired in
REOLrLRED ACTION A.I. However, the REQUIRED ACTION to restore the
hction is expected to be achieved as soon as reasonable. even if this is
significantly less than the assigned COMPLETtOK TIME. The IS dab
COMPLETIOX TIME shodd not be usttd for operational convenience.
A-69 Building 991 Complex FSAR
Appendix A