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BASES
BA4CKGRO'L'KD
(continued)
Revision j,
September 1999
The autornatic nortion of the plenum dduze svsterns provides a water curtain in
front of the downstream deinister screen wlien actuated %%en omratinn as
desiotied, the automatic delune system will create a water curtain thai is expected
to cool the air in the plenum Drior to the air imnactina the WP.4 fitccr stagc(s)
The cooled air ~ili then begin to lower the HEPA filter temperaturf to protecc the
filters fioni i&ioii. TTrc automatic deluge sDray ma): also cool hot ernbcrs and
tlvinrr brands before thev reach the HEPA filters. although the svsteni ws
designed for air cooling der than particulate cooIinz. lfthe automatic deluge
salve &Is to open, a ca~abilitv exists for manual operation of the automatic
deluge systcrn by ouetrine a manual vdve in an automatic deluge vdve hvuass
line These hwass line manual valves are located in the basement of Bujtding 991
for the Building 991 uienum and in Building; 985 for the Building: 985 plenum
A seuarate manual ulenum deluge svstern esists for each uleniini. If actuated. the
manual Dortion of rhe ~lenum deiuae svsten Drovides mrav directly onto the
HEPA filters. The manual deluee wrav and filter wetting will extinguish any
filter fires that have been initiated hv high temperatures, hot enibers or flying
brands. Additionallv- the SDXW may cool hot embers and fly50 brands Drior to
their imuact on the filters. Studies have shom that direct werting of a .mge of
HEPa4 filtration in an active ventilation swtein is likelv to fail the filters. The
filter f.8ilure occurs due to ulu~ing of the filter bv soaked uarticuiates (effectively
stoDuiiisz ventilation). bv arti id Diuaginr causing; media f5ihx-e. or bv dircct sumy
damage. In Building 985. rnuftide stages of HEPA filtration exist in the denurn,
therefore. the sxrificc of the first stwe of filters due to wetting is more desired
dim the imition of the first stage of filters with subsewtent potential for fire
prouagation to the second we. However. &e B~dding 991 roofolenum onlv has
a single w e of filters and the decision to manuallv actuate the deluge system
reauires assessing the likelihood of filter ignition if the manual suray is not
actuated ~.ersus the Iikeiv Eailurc of the stme from wetting if the manual de1uc;e
svstern is actuated. For the Buildiiio 991 deniirn, the manual ulenum deluge
svstern actuation vdve is located on the roof of Building 991, next to the plenum
and a ulenum window dotmstream of the filter stage. The manual olenwn deluge
system actuation vdve for the Building 955 is located in Buildinn 985.
Functional Derformance and maintenance expectations are esmblished for these
systems in Site procedures, which are based on accepted industrv standards such
as NFPA 25. irzsr>eciicm, Teshng and Maintenance of Water-Baseti Fi I'F
Protection .S~.vftvx (Ref. A-1). NFPA 72. Abriolzal Fire Alarm Code (Ref. A-2).
arid NFPA 13. Sk-m&rti fbr the Instdintion of Sprinkler Systenrr (Ref. A-31.
A-66 Building 991 Complex FSAR
Appendix A