ML20236X577

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SER Addressing Concerns of Safe Shutdown of Plant Following Fire,Internal Flooding of Turbine Bldg & Security Incidents
ML20236X577
Person / Time
Site: Oconee, 05000000
Issue date: 12/29/1982
From:
NRC
To:
Shared Package
ML20195F761 List:
References
FOIA-87-714 NUDOCS 8712090300
Download: ML20236X577 (26)
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' S AT ETY EVALUATION REPORT OCONEE NUCLEAR STATION STANLEY SHUTt3WN FACILITY AUXIL**-* SYSTEy.S BRANCH j 1.0 ISI.S.03 " r i ~ ' M ,

By letter dat ed February 1,1978 the licensee proposed a saf e Such a system l

l shutdown system for the Oco.yee Nuclear Station. ,

wcutd augment existing plant cap a bilit i es re la ti ve t'o miti-gating postulated occurrences such as fires, security inci-dents and turbine building flooding. Ad:itional information .

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describing the conceptual design of the safe shutdown system was received by letter d :ed June 19, 1978; subsequent staff app'revuL of the conceptual design was transmitted to the, Licensee December 29, 1978. In accordance with the conceptual design evaluation, the Licensee provided a final design pro-pos a l for the system, the standby shutdown facility (SSF), in -

a March 28, 1980 submittal. Art the time of the March 28, 1980 subnittot, Appendix R was not effective. .

On February 19, 1981, the fire protection rule for nuclear power plants, Appendix R to 10 CFR 50 became effective.

This rule recuired all Licensees of plantslicensed prior to January 1, 1979, to submit by March 19, 1981: (1) plans and schedules for meeting the applicable requirements of. Appendix R, 8712090300 871204 PDR FOIA PDR ,(

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(2) a. design description cf any morificat ons proposed to orovide alternative safe she c:, n capability pursuant to c aragraph III.G.3 of. Appendix R, and (3) exemption steouests fer which the telling provisions of Section 50.48(c)(6) was to be invoked.Section III.G of Appendix R is a retrofit

. item to aLL. pre-1979 plants regardless of previous SER positions and resolutions. Subsequently, the. Lice'nsee provided submittals reDarding the use of the SSF to meet l Appendix R requirements f or the Oconee Nuclear Station.

, It should be noted that this SER only addresses the ' concerns l of cafe shutdown in the event of fires and turbine building l

flooding. Safe shutdown in the event of a' security incident will be handled by others.

The Licensee has addressed the Oconee Nuclear Station's post-fire shutdown capability in six letters dated January 25, February 1, and June 19, 1978, March 28, 1980, and March '18 and Apri! 30, 1981. Additional information was provided in letters dated January 25, and September 20, 1982. These submittats discuss the various means used to achieve and main-tain safe shutdown conditions, determine whether safe shutdown could be achieved without equipment or cabling in any one fire area, and identify any modifications required due to unacceptable interactions caused by a fire!'

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2. 5 1,,5,* S Y S T E P.L.MSJ MP_U,Q,y, 2.1 Mechanical Systems 2.1.1 General Description The standby shutdown facility (SSF) is a " bunkered" facility which hous,es the systems and components neces'sary to provide an alternate and independent means to achieve and maintain a hot shutdown condition..for one or more of the three Oconee units. The SSF serves to resolve the safe shutdown .

requirement for fire protection, physical security and turbine building flooding. The SSF has the capabil,fty of maintaining het shutdown conditions in all three units for approximately three days following a loss of normal AL -

power.

  • The Licensee concluded that the most likely reason for flooding of the turbine building would be from a condenser circulating water pipe break resulting from a seismic event. The licensee therefore decided that the SSF woutd be a seismic Category I structure and further that it be designed to withstand the effects of tornadoes. The missile spectrum upon which their analysis is based, is in confor-mance with the guidelines of the Standard Review Plan (SRP)

Section 3.5.1.4, Revision 1, for a tornado Zone 7 site. The e

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tace ievel er. trance elevatier. of the SSF is 7*7.* nst.

This elev.: ion is belo. Keowee fu'l pond elevation-ef 800 as . e l '. as .e a x ' r. u - '. a ;. e elevatior, of SCS. -: t.t*, in the event of fLcoding due to a break of the non seismic c o r,-

denser circulating water (CCW) system / piping locat ed in the turbine building, the maximum expected water level within

- the site boundary is EL 796.5. Since the maxi um exoected

.ater level is below the elevation of the grade Leve,l entrance to the SSF, the structure will not be ilooded by such an incident. In addition, the s*.ructure wilL be waterproofed to prevent infiltration of normal ground wa*er. Thus,the structure meets the requirements of GDC 2, and the guidelines of Regulatory Guide 1.102 with respect to protection against fleeding. Since the use of the SSF may be required following a tornadic event to meet II.E.1.1 requirements, a separate review of the structures and systems to withstand the eff? cts of tornado missiles will be perf ormed.

2 1.2 .Meactor teolont_(DC) Mekeue See**/

The SSF RC makeup system is designed to supply makeup to the reactor coolant system (RCS) in the event that normal systems are unavailable. The capacity of the system is sized to account for normal system Leakage, and shrinkage which results from going from a hot power operating condi-

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tion to hot shutdown.

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l The crimary conocnent of the SSF RC makeup < stem is the 26 spm SSF RC pucp. One pucp is required for each of the three units; each pump is located in its respective reactor s

building. The capacity is sufficient to maintain RC inven-

. r-tory during the transition from power operations to hot shutdown. The makeup source is from the spent fuel pool, thus ensuring a supply of borated. water. Letdown, if required, is returned to the spent fuel pool. The letdown valve is powered f rom the SSF power system and is controlled from the SSF ohly. Capability for power and control of

'one bank of pressurizer' heaters atlow control of the steam bubble in the pressurizer. Overpressurization protection is provided by existing rett.'/ valves. The system is designed to seismic Category 1 ind Quality Group B require-ments. Failure of the SSF RC makevo components wilL not 4

affect the operation of the normal "in plant" components.

The $$F RC makeup system is opt attd sid/or tested only frors the $$F.

2.1.3 Str a uv4'4=ry Mievice Water System (SSF ASVS)

The SSF ASWS is a high head, high volume system designed to

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provide suffictent secondary side inventory for adequate decay, heat removal during a loss of normal AC power (n conjunction with the loss of the normal and eme'rgency feed-i . . . . ... .. .

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The SSF ASWS pump is the major c om; o n e r.t of the system, and is housed in the SSF. The one motor driver .- u m p which is j

powered from the SSF power system is designed ,to provide approximately 750 gpm at full system pressure to each of the three units for approximately three days. The water contained in the embedded condenser circulating water (CCW) piping serves as the water supply. The e m b e d d e d " p o r.t i o n of the CCW piping is designed to withstand the effects of a seismic event'. The SSF ASWS is designed to seismic Category I and Quality Group B and C requirements. Failure of the SSF ASWS components wilL not affect the operation of the normal "in plant" c o,mp o n e nt s . The SSF ASWS is operated and/or tested only from the SSF.

2.1.4 _ SET Serv 4c* Water Evstem,,

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The SSF service water system is comprised of thk HVAC ser-vice water system and the diesel engine service watet system.

The HVAC service water system, which operates continuously, centains two 100% capacity pumps and supplies cooling wat er to the HVAC condensers. Onty one pump operates at a gi,ven t'i m e , the other pump. serves as a backup. j I

The diesel engine service water system, which operates only l when the diesel is operating, contains one pump and provides service water to the diesel engine jacket water heat exchan-gers.

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4 A l '. three pv cs take their suction from the embec.ed CCW cicing and return the 1 Low to the CCW piping after passing l

through their respective system. The piping and components l

the SSF service water system are designed to withstand of seismic event. All pumps are powered the effects of a from the SSF power system..

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I The SSF HVAC system is comprised of a ventilation system l

and an air conditioning system. The HVAC system provides filtered and conditioned ventilation for the'SSF structure, l

and maintains the environmental conditions uithin the limits set for personnot. occupancy and equipment operability.

The combustion air and diesel engine exhaust s,y, stems are independent of the ventilation systems. The HVAC system consists of three ventilation fans, two air conditi6ning All components refrigeration units and associated ductwork.

and ductwork which service areas which contain ecuipment l

n'eeded for safe shutdown are designed to withstand the effects of a seismic event. All components are powered from the SSF power system.

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The SSF sump system provides a means of :ollecting and dis-charging drainage from equipment and floor drains.. T,w o sump pumps, both of whien are powered from the SSF power system, discharge the effluent to the yard drainage system.

The discharge line will be designed.to prevent back flow into the sump from outside sources. Level switches tocated in the sump are used to automatically start and stop the pumps. The sump system is a nonseismic system as its f ailure will not adversely ^ affect equipment needed f'or safe shutdown. -

2c1.7 .E.SL.f o t a b l e Watar Sv9 tem The potable water system proiides potable water 1or sani-tation and potable services. Water is provided from a 200 gallon storage tank located in the SSF. The tank is fed from the plant potable water system, and tank level is float

entrolled. Water t o t h e 6.> r t a b le b a t t e r y test' facility is supplied directly from the plant potable water system rather than from the storage tank. The system is. designed to nonseismic requirements since its failure will not adversely af f ect equipment needed for safe shutdown.

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9 2.1.' Instrumentation and Con,tt:13 The SSF con *.rol panel provides inst rumentation and cont rols needed to assure safe plant operations and shutdown condi-tions for the three units. Monitoring capability is pro-vided for plant parameters such as primary coolant tempera-ture and pressure, pressurizer pressure and level, incore thermocouple, and steam generator level, and diagnestic capabilitiesifor mechanical and electrical compenent per-formance. However, steam generator pressure and neutron flux indication, and steam generator pressure controls have not been provided in the SSF. All electrical equip-ment necessary for hot shutdown is designed to withstand Electrical power is pro-the effects of a seismic event.

vided by the SSF power system.

2.2 SSF Power Eve +aa 2.2.1 Ge_neral Descriotien .

The SSF power system is comprised of independent emergency sources of AC and DC electrical power and their associated electrical distribution systems, and various support systems.

It would be operated only in the event installed normal standby systems are inoperable. Manual operator action is required to actuate the system.

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The SSF ::wer sy s t e m includet onsite 4160VAC, 600"AC, 120VAC ar.c 12fVDC power. This s y s t e- s u: -t i es ' power necessary for

-t -:: sn.tc:Ln ci tne reaet:- in the event of less of oower from aLL other poser systems. It consists of switch-year, a Lcad center, a motor control center, paneLboards, battery, battery chargers, an invert er, a diesel-electrical generator unit, relays, control devices, and interconnecting

a:te s;optying the appropriate loads. ,

The inverter supplied 120VAC power system s upplyi ng the security system circuits in conjunction with the 125VDC '

instrumentation and control power system supplies continuous control power to all Loads that are recuired for a hot shutdown of the reactor.

2.2,2 AC Power Interfacingm The 4160 volt SSF power system is provided for backup ser-vice only and is normally de-energized with all breakers on the bus in the open position. Upon less of the normal p:wer system, the 4160 VAC SSF power system will provide power to the necessary leads to saf ely shut down the unit by an onsite diesel-electric generator (see Section 2.2.3 for further discussion) which is independent of the normal power distribution system.

Att of the loads required for hot shutdown of the reactor are supplied power during loss of the normal distribution system from the 4160 VAC SSF power system, either directly (for the high head auxiliary se rvi ce water pump) or through transformer (s) if at a lower 1

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The 660VAC SSF load center is normally de energi.ed. Power to the 60DVAC mctor co. trol center is supplied from a d o u b l e - e r.d e d bus nor atly sup; lied from a unit lcad center of the 600VAC normal auxiliary power system and alternately fed from the SSF power system. The motor control center supply bus cannot be connected.to either source unless the ether source breaker is open. Upon los's"of power to the normal source breaker, an automatic transfer to the SSF source will be initiated. Connected to the motor control center are all the remaining 600VAC

[cadswhich recuire i power for hot shutdown of the reactor. Normal power to the pressurizer heaters and necessary primary system iso-Lation valves is supplied from their respect 4ve unit normal auxiliary power system. When their normal source arelost, they are transferred to the 600VAC SSF power system.

The 120VAC power cystem consists of a static inverter, a panelboard, a manual transfer switch and interconnecting cables. The system is designed such that ncrmal power is provided from the battery-backed 125vDC distribution center to the static inverter, through the manual transf er switch and to the panelboard which, in turn, supplies power to the shutdown system circuits. Upon loss of the static inverter or the DC power system the SSF 120VAC power system panelboard is manually transferred to its alternate source, the 600VAC SSF Power system. '

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.s s 2.2.3 S;andby_DS.** S ur r. ly The SSF standby power sy; ply consists of an indel ndent d i e s e l - e ', e : t e d: penerating unit, which is rated at 3000 kW, O.SPF, 4160 VAC The auxiliaries recuired'to assure preper operation of the diesel generator unit are supplied with powey Yrom the appropriate buses (600VAC, 120VAC or 125VDC) of the SSF power system. The diesel-electric

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generating unit is rated for contihuous coeration at 3000 kW. The design lead level for the syste- coes net' exceed the 3000 KW continuous rating of the diesel-electric generating unit. .The unit has an independent air starting system with storage to provide at least two stou starts.

An i n e' e o e n d e n t fuel system, complete with a separate under-j ground storage tank and a one hour day tank, is supplied l The underground )

1er the diesel-electric generating unit.

storage tank is sized to operate the recuired SSF power The day tank is sized s'ystem for a period of seven days.

based upon the fuel oil storage recuired te successfully l

start the unit and to allow for orderly shutdown of the diesel unit upon loss of oit kom the main storage tank. i 1

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Following loss of nornal (effsite) power, the diesel-electric

enerating unit is nanuelly started and connecte
to the 4160 V AC SSF power system ous. By m a r.u a l l y c t: sing the 4160VAC generator breaker, the high head ausiliary . service water rump motor breaker, and the 4160/600VAC transformer breaker, the entire SSF power system is provided w.ith its backup seurce of power. .

2.2.4 (G _P_p_w ed:e_Lv The DC power supply system censists of a 125VDC distribu-tien center, one normal and ene standby 600VAC/125VDC battery c h a'r g e r , a 125VDC battery, interconnecting cables, and associated instrumentation and control circuits. The system is designed to p'r'cvide an adequate and reliable source ,

l of continuous DC power for all controls, i n s t r ut e n t a t i o n ,

annunciators, inverters, DC motors, backup lighting, relays 1

anc solencid valves of the SSF pcwer system until the diesel-electric generating unit is available to supply power i to the system.

The DC pewer system is designed to coerate ungrounded and is provided with a ground detection system set to indicate the first ground.

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Both battery chargert areidentical and.are rated o00fvolts, 3 phase, d;

r. e r t : inout, and suo;ly ;cser for,the

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j 600VAC SSF oower system motor control center. Normally, one of.the chargers is connected to float charge the -

battery while carrying the continuous lead, w ith the other

. charger available to ecualize the battery discen'nected fro'm the DC bus while the normal charger carries the normal load. It would also be available as a backuo for the nor-mal charger. Each charger is designed to prevent the battery from discharging back into any i n t e r n a t. c h a r g e,r circuits in the event of an AC power supDLy failure or a charger malfunction.

The battery meets the duty cycle recuirenents without use of a charger and witheyt,, decreasing the voltage below- an acceptable level in its operating environment. During normal operation, the batteries are floated on the b u s e's and assume lead without interruption upon loss of a battery charger or AC power source.

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  • I The DC distribution center receives power f ce a battery charger er battery ce: enc'ing en AC power system sta us,'a*.d in turn.feecs ;cWe* :: a DC peser panettcare and a static )

inverter. The 125VDC distribution centers are metaletad f

free--standing steel structures of NEMA Type 1A construc-tion with.gasketed doors, cover plates, and contain m,olded circuit breakers and voltage monitoring devices. The battery bvs voltage is monite ed by voltneters located on the 125VDC distribution center.

3.0 REVIEu natr_s The design of the SSF was reviewed to the requirements of Aopendix R to 10 CFR 50, Sections III.G.3 and III.L, and those requirements applicable for flooding and seismic events.

The licensee has stated that the Standby Shutdown racility (SSF), ,

associated mechanical and electrical systems and oower sue: Lies, meets or exceeds tre acclicable cri teria contained in the Oconee FSAR. Additionally, ASME and IEEE coces are utilized as appropriate, in'the design of various subsystems and components. The SSF and systems / components need'ed for i

safe shutdown art designed to withstand the Safe, Shutdown Earthquake (SSE).

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'o- 1 The SSF system required for saft- hutossn are designed with adecuate capacity to ensure sa'e hot shutdown conditions cf i d

aL. t. tree Cccnee units. The SSF cc.er syste- are des'igned with adequate capacity and capability to supply the necessary i toads, and are physically and electrically independent from i

the main shutdown system power supply (station power). Addi-tionaLly, the AC and DC power systems and equipment ~ required for the SSF essential functions have been designed and installed consistent with the Duke QA program of Class 1E ecuipment.

1 The systems are not designed to meet the single failure criterion, but are designed such that failures in the system do not cause failures or inadvertent operations in existing plant systems. The systems in the SSF are manually initiated; multipte actions must be performed to provide 1 Low to existing safety systems.

4.0 EVALUATION The SSF is a seiseic Category I structure which houses systems and components needed for safe shutdown, and their support systems. The facility is designed to withstand the effects.of flooding and earthquakes. The SSF RC makeup system has the capability of providing adequate makeup to the R...etor Coolant System (RCS), and the capacity of the SSF auxiliary service water system is such that adequate fi o w for decay heat removal can be provided to each unit.

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The SSF power suoply is physically separated and electrically I- i ndependent thrcugn the transformer and c d-cuit breakers from the nair.otat'i~on power system. The estac4 ty Of the normal power suoply and the diesel generator and the batteries is adequate to supply all the SSF design loads. Adecuate pro-tection is provided to the SSF power supply systems to pro-tect from abnormal electrical condition.

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Adecuate instrumentation and controls have been provided in the SSF with the exception of neutron flux and steam generator pressure monitoring capability.

l CONCLUSIONS (with reseeet te franddae) 5.0 Based on our review, we conclude that the design criteria and the cesign of the power supplies, mechanical s y s t e r.s ,

and instrumentation and contro'Is for the Standby shutdown Facility with respect to turbine building flooding, are acceotable.

6.0 C O *' C L U S I O NS__( e i t h reemaet tm A*eendir R e t,q u i r a a a a t =J 6.1 OVERVIEW _

To preclude a single fire f rom af f ecting redundant trains of a system, each safety train must meet minimum separation /

protection requirements. In the licensee's " Fire Hazards

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1 and Response to BTP 9.5-1" dated December 31,1976, and in subse: vent responses to re:uests for additional in :rma-tion, Me 'icensee identifie: vari: . s areas of the plant which cid not meet the required. separation /pr'otection requirements. To eliminate the deficiencies, a dedicated  ;

i safe shutdown system independent of the existing plant .{

systems which uould be used to achieve safe shutdown was To nitigate the censecuences of post'ulated fires, creocsed.

the dedi:sted shutdown system has. be en incorporat ed'into the design of the Standby Shutdown Facility (SSF). The use of the SSF as a means of achieving compliance to Sections III.G.3 and III.L of Appendix R to 10 CFR 50 is premi' sed upon the acceptability of the SSF design as a whole. When-

  • ever possible, the existing plant systems will be used to achieve hot shutdown. The SSF witt be used when the existing plant systems or facilities of one of the three units are unavailable due to a fire. The SSF is not designed to bring the reactor from hot shutdown to cold shutdown. ,

Cold shutdown will be achieved and maintained through the use of existing plant systems and ecuipment as discussed below. No repairs or. modifications are required to effect hot shutdown utilizing the dedicated shutdoun method. Repairs for cold shutdown may be required depending upon the fire 1

area.

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6.2 _ SYSTEMS USED FOR POST-FIE ,IAre t u n t a m u,L

  • A. Systems R :vired f o r_S a f.e S h u t d cLa:A Safe shutdown of the reactor is initially performed by the insertion of control rods from the control room. Insertion can also be accomplished by removing power to' the motor generator sets in the switchgear room. Reactor coolant inventory and reactor shutdown margin are maintai'ned by the SSF makeup pump taking suction fro the spent. fuel pool.

Primary system pressure can be maintained by the pressurizer i

heaters and pressurizer spray or by use of charging com-bined with letdown. Should the pressurizer heaters be unavailable (caused by fire inside containment), progres-  ;

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sion towards cold shutdown will be initiated as soon es }

I hot shutdown is achieved.' Decay heat removal can be I accomplished by releasing steam from the steam generators via the atmospheric dump valves. Makeup to the steam generators can be provided by the SSF auxiliary service water system (SSFASWS), which takes suction from the embedded condenser circulating water (CCW) system piping.

Depressurization to cold shutdown can be achieved b/ bypassing steam to the turbine (since CCW is not lost in the event of a loss of offsite power), use of pressurizer spray, or use

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of acxiliary'pressuri:er spray via the high oressure injec-tion (HDI) pumo. The low p'r e s r. u r e injection (LPI) pumps will be usec to re.ove decay energy. As a backv'? to the j LPI pumps, the high pressure injection (HPI) pump can be used to maintain flow for decay heat removal. Any damage to either the HPI or LPI power cabling or pump motors can be repaired or replaced within the imposed' time con-straint to ensure the capability to achieve cold shutdown (yi t hin 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of t he fire.)

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Also required for cold shutdown are the Low pr e s s u r e se r vi c e I

wa t e r (LPSW) pumps. Only one pump per unit is required for normal and emergency plant operations. Five LPSW pumps  !

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of equal capacity are provided - three for Units i an'd 2, ano two for Unit 3. These pumps are separated such that a single fire cannot affect all pumps. The piping.for these pumps are interconnected so that they may fee'd any of the three units. Any darage to the pump motors or associated power cabling car, be repaired, or if necessary, replaced within the imposed time constraint to ensure the capability to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of I the fire.

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5. A r < a s ' W h e t_le.fJ, ; . r.cL.S.b u1d cc rt_j s le.;; o i a a 2 The licensee has provided dedicated shute'ewn capabity in- .

deoen. t :: :ne cabling and e:ui nent in -he c ntrol room, cable spreading room, and these areas identified in the staff's August 22, 1978 SER on fire protection. The dedi-cated sh'utdewn method will be accomplished by'the use of the SSF, and actions performed locally at the equipment.

Electrical isolation wi ll b e p r ovi d ed 's uc h t'h a t a fire at the SSF will not prevent safe shutdown of the plant from the control room, and vice versa.

C. _R e m a i n i n e Plant A r_e_11 The staff's August 22, 1978 SER identified many areas of the Oconee Nuclear Station that did not meet various fire protection safe shutdown requirements. Rather than cor-recting the individual deficiencies by modifications to the atready installed components, a dedicated shutdown system (the SSF) was proposed. The i n t e n,t ef the use of t '. c 55' along with the unearaged systems in the fire affected unit is to meet the requirements d Sections III.G.3 and III.L of Appendix R.

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l 6.3 FVALUATION l.

Perfo e:nce Goals The performan:e go.Is for post fire safe snutcown can be met 1

using the systems and equipment list ed in Section A above.

The control of these functions can be accomplished using the SSF or the control room in conjunction with the unda sged

. systems, in the fire affected unit, depending on the location of the fire. The transfer of control ca: ability betwee,n the control room.and the SSF will be accomplished via a keyed interlock. Annunciation wiLL occur in the control room upon transfer of control.

The process monitoring instruments to be used for a post fire shutdown includes reactor hot leg and cold leg temperatures, reactor coolant pressure and pressurizer level, steam generator level, SSF makeup pump flow and SSF ASWS pump suction and discharge pressure. However, an electrically independent source range flux monitor and steam generator pressure indi-cator have na been provided. The licensee should be requested to provide a commitment regarding this instrumentation. The licensee should be advised that the instrumentation d oe s. *no t have to be safety grade, but only meet the requirements of Section III.L.6 of Appendix R.

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The available support systems for post fire safe shutdown are the redundant diesil ' generators, vita. buses, and'those I support systems associated with the SSF.

6.4 Er.p a ir s / 7 2 Jic ur _Jt es vir.tm_ tnt Use of the dedicated shutdown method for hot shutdown permits the capability of achieving cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> af ter ,

Repairs, or if necessary, replacement of power

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a fire event.

cabling or pump,. motors associated with LPI, HPI or LPSW may be required for cold shutdown. All comp 6nents are stored onsite to ensure the capability to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of the fire. Procedures are available to imple-ment the required repairs / replacements. ,

6.5 Asso .iated. Circuits and Isola.timp .

All circuitry, indicators, instruments and power supplies associated with the SSF are independent from those identified fire zones for which alternative shutdown capability is recuired. The licensee has s.tated that nonsafety related circuits do not run from one redundant train to another and thus negates the possibility of propagating a fire between redundant circuits. The licensee's methods of protecting the safe shutdown capability are consistent with*the guidelines provided by the staff.

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The S i instre entation has a decicate: ower ' source and its' cabling is separated free those associated with'the normal shutdc.n ins t rurent a t- n. All of the normal pows j and c o r.t r o l ti :.i s are :covided isc'.atien via electri-c'a l l y cc -dir.a ed ci r cuit breakers or fuses.

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2. Cecmon Encicsuna The power sources needed for the SSF ecuienent 2nd instru-entation, and s i t chgear and motor control centers for I required components are not located in the postulated fire zones needing alternate shutdown capabilities. Nonsaf,ety related circuits do not run from one redundant t r a i 'n t o another. Further, all cables of concern are protected by ci r c ui t breakers 4r fuses.,_

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3. Spurious Signal Operations  !

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The devices whose inadvertent operation by spurious s~i g n a l s could adversely affect safe shutdown have been identified.

l The cabling required for hot shutdown via the SSF as well as one redundant train of the normal shutdown system are routed to containment through the west penetration rooms for each unit. Cabling for the other independent normal shutdown system is routed to containment through the east penetration rooms. The cast penetration rooms are separated at each by s three hour fire barrier. The licen:ee.has stated that the cabling routed through the west penetration rooms are separated to the extent practical from existing safety system 1

. _ _ _ _ _ _ . _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ . _ _ ._ __________.__________.____d

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  • cabling, and that suitable isstation is provided o'etween the SSF and existing safety system caoling. Since one indeoen-dent shutdown train will be available regardless of a fire in either penetration room, the cable routing design satis-fies the requirements of III.G and is therefore acceptable.

The licensee has shown that the cable routing of each division (including t he SSF cabling) is such that degradation i

of the redundant shutdown division will not occur, nor will spuricus valve actuation occur which might cause an inad-vertent depressurization of the primary in the event of associated circuit interactions. The cabling for the RHR i

isolation valves are routed such that the reactor coolant .

pressure boundary integrity will be maintained. j 6.6 S,afe. Shutdown Procedures and.Manpowir

~

The licensee has committed to develop and' implement detailed written procedures for obtaining a safe shutdown condition given a fire event. These procedures will be in olace prior to the SSF becoming operational. The manpewer ne:essary 1'o r accomplishing the operations required f or the alternate shut-down will be available at the plant at all times. Members of the fire brigade will not be included in the shutdown l manpower requirements. .

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6.7 CONCLUSION

Based on our rev iew, we concluded tL t the Oconee Nuclear Statien

esign .,- provide ene train o' systers necessary'to a:hieve and maintain safe shutdown conditions by utilizing either the
entrol room or the SSF in conjunction with undamaged systems j l

in the fire.affected unit, and thus will meet the requirements  !

1 of Appendix R to 10.CFR 50, Sections III.G.3 and III.L with .

l respect to safe shutdown in the event of a' fire, with the excep-tiens of the availability of a source range flux monitor and steam generator pressure indication at the SSF.

. i 7.0 Overall SSF Conclusion Based on our review, we conclude that the design criteria and l the design of the SSF to ensure safe shutdown in the event of turbine building flooding are acceptable. We also conclude that the Oconee Nuclear Station, in cot 4j unction with t he use of the' SSF, will meet the requirements of Sections III.G.3 and III.L 1

i of Appendix R to #D CFR 50, with the exception of the availability f

' of a source range flux monitor and steam generator pressure indication at the SSF. We will require such instrumentation l be provided. This SER also resolves the open items in our SER dated August 22, 1978.

- The ability of the Oconee Nuclear Station in conj unction with the SSF to safety shut down following a pecurity incident was not evaluated.

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