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BASES
APPLICATION
TO SAFETY
ANALYSIS
The Automatic Plenum Deluge Svstems supnort the Filtered Exhaust Ventilatiori
Svstenis bv providing protection ofthe HEPA filters diirhg resyonsc to fires. 7122
FEVS is a recognized control credited to mitigate the public and collocated worker
radiolorjcal dose conseaumces for several dominant Dosculattd accident scenaios
as indimd in Chwter 5. ,krfetv Stnicfiires, Swtenls. aid Cumrionenfs. of the
FSAR. 71rc control was not credited as uart of the accident andvsis presented in
the FSAR-suu~ortinn Nuclear Saiktv Teclrnical Report fiSTR). Rather. the
control was identified and crcdited as art of the dominant accident scenario
discussions in the NSTR and in Chapter 4. Hazard and Accidmzt Anrrlwzs
Summan- of the FSAR. The single stage of HEPA filtration is credited with
accident scenario mitigation for most operational event scenarios.
-
The Autoniatic Plenum Deluge Svstems are a DEFEYSE-IN-DEPTH mitivative
feature for filter Drotection in remonse to lme faciliw fires. IXe internal facility
fires evaluated in the s d i analyses onlv deal wirh 1 MW and 2 hlu’ fires which
mill not challenve the ventilation srstems and filters. Laz cr fires would have to
occur in order to reach plenum temperatures in excess of 19W’F and achmte the
Autotnatic Plenum Deluw Svstems. A potential docs esist for hot embers and
flvinrr brands from analvzcd fires to be cautured bv the filters and create the
potential for filter imition. but the likelihood of this event is considered to be low.
In this situation. the deluw system would onlv be actuated rnanuallv and onlv if
filter imition was observed or felt to be imminent. and the filter mxxtinrfloss issut?
would influence the decision to use the svstem. Therefore- the likelihood of the
actuation of this svstem. either automaticaZfv or mmdlv. is considered to be low
As such. the systcrn is not credited in the safh analyses and onlv serve as a
DEFEME-LV-DEPTH mitigative feature for a uotential mitigation of low
likelihood events.
LCO 3.3 The BUILDING991 COMPLEX Automatic Plenum Deluge Svstenis shall be
OPER4BLE.
Revision I
Septcmkr 1990
For the Automatic Plenum Deluge Svstems to be OPERABLE. the ststenis mus?
be CaDable of automaticallv or nianuallv suoulvino cooling and/or pietting water
mray inside the W S olenums. The svmms must be cauable of detecdino hi&
temuemtures in a vzntilation svstem Dlenum and automaticallv openine a delu~e
svsteni salve. The systems must dso provide a capabilitv of ~i‘muall~ bwassing
the automatic deluge dve and of manuallv acttiatinr the filter direct sumv portion
of the svstem.
A-67
Building 991 Complex FSAR
Appendix A
I