ML20059B425
| ML20059B425 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 10/26/1993 |
| From: | Fox J GENERAL ELECTRIC CO. |
| To: | Poslusny C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9310280180 | |
| Download: ML20059B425 (18) | |
Text
"
GENucle:rEn:rgy Cr.ere! Electnc Company 175 Cumner Avenue. San Jose. CA 55125 October 26,1993 Docket No.52-001 Chet Poslusny, Senior Project Manager Standardization Project Directorate Associate Directorate for Advanced Reactors and License Renewal Office of the Nuclear Reactor Regulation Subj.:ct:
Submittal Supporting Accelerated ABWR Schedule - LCO 3.8.9 and Bases
Dear Chet:
Enclosed are LCO 3.8.9 and its associated bases, incorporating P&R review comments and recent agreements reached between NRC staff and GE. Please provide markup comments as soon as possible.
Please send copies of this transmittal to Mark Reinhart and Jim Lazevnick.
Sincerely, hv Jack Fox Advanced Reactor Programs ec:
Alan Beard (GE)
Norman Fletcher (DOE)
Cal Tang (GE) i 2800;;9 ama3 f
\\
sN 9310280180 931026 I3 PDR ADOCK 05200001 es t
-A PDR~
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Distribution Systems-Operating 3.8.9 3.8 ELECTRICAL POWER SYSTEMS 3.8.9 Distribution Systems-Operating LCO 3.8.9 Divisions I, II, and III AC, Divisions I, II, III, and IV DC, and Divisions I, II, III, and IV AC vital bus electrical power distribution subsystems shall be OPERABLE.
APPLICABILITY:
MODES I, 2, and 3.
ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A.
}D"eEliffsffsdtid 2360Fi power distribution pequiirsdfelajafe5
~ ~ ~ ~ ~
subsystem inoperable.
! inoperable; AND A.'.'2.2, ~ WeEif#tlisi.te6ba,sfi.nn 12~h.6,UFs; bfie)iisfandtfonsT (CTG 'fiffisgithsiCTG startsVhndiahhisisT stlesdylststbyV61tigs an;d!;frd40enMWithij
- 10;:;mjriutesj 8!!Il A.T3T ffYbrlfy3 hs3 CTG.
-.,66..iiFs.
12?!
-~
capable {offbbisg A@
~lignedztosthe a
0.PERABLE;6f9fkV 6nEs~jiiE8 esisn..tial. fAC%d. sist.S hon.d~~~"
~ ~ ~ ' ~ '
AND (continued)
ABWR TS 3.8-I 10/21/93
Distribution Systems-0perating 3.8.9 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME A.
(continued)
A.4 Restore AC electrical 72[hhUfs power distribution subsystem to OPERABLE AND status.
dfsco]veryof 77diy from failure to meet LC0 B.
One AC vital bus B.I Restore AC vital bus Z21hpHFs electrical power electrical power distribution subsystem distribution AND inoperable.
subsystem to OPERABLE status.
7Edaisfrom disioVery of failure to meet LC0 AND B.2 Declare affected 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> required features inoperable.
C.
On AC vital bus C.I Restore inoperable AC 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> electrical power vital bus (other than distribution subsystem Division IV) to (either Division I, OPERABLE status.
II, or III) inoperable.
0_8 AND C.2 Restore inoperable 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Division IV AC vital Division IV AC vital bus to OPERABLE bus inoperable, status.
I (continued)
ABWR TS 3.8-2 10/21/93
Distribution Systems-Operating 3.8.9 ACTIONS (continued)
CONDITION REQUIRED ACTION CDP.PLETION TIME D.
One DC electrical D;17!
iDiclaFsisfficted
'sh6dFs 2
power distribution "YelqdirsdifeatUFd5
~ ~ ^ ' ' " ~ ~
subsystem (either irfopsrsb1'sf~*^~
Division I, II, or III) inoperable.
AND D{2]
} Vip {f@t[fsH6@busMjj 721F6sFs turbine 3generatot
'(f$e)Wistfuiictichilfiffihgi? thy [ CTG CTG b
!hi b
an'difrequbncyijjithDj 101minutesi, b!@
D...: 3 f-WeafflthE!!. CTG.
12.15.h60.Fs
~
'capablelbftbsihg~"
AND al19nsd3toithe~
" ~ ~ ~
OPERABLCf6$9LkV OnfEliieWnlT60F5
'esseltial@Cf.btissis thetbaftsf"^'~
AND D.4 Restore DC electrical 72ffi61if]
power distribution subsystems to AND OPERABLE status.
7sdif5from d'iscovery of failure to meet LC0 (continued) i i
ABWR TS 3.8-3 10/21/93
e e
Distribution Systems-Operating 3.8.9 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME E.
Division IV DC E.1 Restore Division IV 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> electrical power DC electrical power distribution subsystem distribution inoperable.
subsystems to OPERABLE status.
M E.2 Declare affected 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> required features inoperable.
F.
One DC electrical F.1 Restore inoperable DC 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> power distribution electrical power st.bsystem (either distribution Division I, II, or subsystems (other III) inoperable.
than Division IV) to OPERABLE status.
AND E
Division IV DC electrical power F.2 Restore Division IV.
2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> distribution subsystem DC electrical power inoperable.
distribution subsystems to OPERABLE status.
G.
Required Action and G.1 Be in MODE 3.
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time of Condition A, AND B, C, D, E, or F not met.
G.2 Be in MODE 4.
36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> ABWR TS 3.8-4 10/21/93
Distribution Systems-Operating j
3.8.9 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.9.1 Verify correct breaker alignments and 7 days voltage to required AC, DC, and AC vital bus electrical power distribution subsystems.
ABWR TS 3.8-5 10/21/93
1 Distribution Systems-Operating B 3.8.9 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.9 Distribution Systems-0perating BASES BACKGROUND The onsite Class lE AC and DC electrical power distribution system is divided by division into three independent AC and four independent DC and AC vital bus electrical power distribution subsystems, The primary AC distribution system consists of each 6.9 kV Engineered Safety Feature (ESF) bus that has two separate and independent offsite sources of power, as well as a dedicated onsite diesel generator (DG) source.
Each 6.9 kV ESF bus is normally connected to a preferred source.
If all offsite sources are unavailable, the onsite emergency DGs supply power to the 6.9 kV ESF buses. Control power for the 6.9 kV breakers is supplied from the Class IE batteries.
Additional description of this system may be found in the Bases for LCO 3.8.1, "AC Sources-Operating," and the Bases for LC0 3.8.4, "DC Sources-Operating."
i The secondary plant AC distribution system includes 480 V ESF load centers and associated loads, motor control centers, and transformers.
Each 480 V AC MCC is powered from its divisional 6.9 kV ESF Bus via a 6.9 kV/480 V transformer.
1 The 120 V AC vital buses A10, BIO, C10, and D10 (Divisions I, II, III, and IV respectively) are arranged in four load groups and are normally powered from a divisional 480 V AC 4
motor control center (MCC) via a rectifier, an inverter, and i
a static switch.
Divisions I, II, and III are normally powered from Division I, II, and III 480 V AC MCCs, j
respectively. Division IV is normally powered from a Division II 480 V AC MCC since there is no fourth division of 480 V AC. However, each of the four DC electrical power distribution subsystems (including Division IV) is backed up by its own battery bank and will automatically supply power (via the inverter) in the event of low voltage output from the rectifier (which would occur, for example, if the 480 V AC divisional power is lost). The Bases for LC0 3.8.7,
" Inverters-Operating," describe the use of the four DC subsystems. In the event of an inoperable inverter, an alternate power supply for each 120 V AC vital bus is a divisional Class IE 480 V/120 V bypass transformer powered (continued)
ABWR TS B 3.8-1 10/21/93
T 4
Distribution Systems-Operating i
B 3.8.9 l
BASES BACKGROUND from its divisional 480 V AC MCC; again, with no fourth 3
(continued) division of 480 V AC, the alternate power supply to the Division IV 120 V AC bus is a Division II 480 V AC HCC.
There are four independent 125 VDC electrical pcwer distribution subsystems.
The list of all distribution buses is located in Table B 3.8.9-1.
APPLICABLE The initial conditions of Design Basis Accident (DBA) and SAFETY ANALYSES transient analyses in the SSAR, Chapter 6 (Ref. 1) and Chapter 15 (Ref. 2), assume ESF systems are OPERABLE. The AC, DC, and AC vital bus electrical power distribution systems are designed to provide sufficient capacity, capability, redundancy, and reliability to ensure the availability of necessary power to ESF systems so that the fuel, Reactor Coolant System, and containment design limits are not exceeded. These limits are discussed in more detail in the Bases for Section 3.2, Power Distribution Limits; Section 3.4, Reactor Coolant System (RCS); and Section 3.6, Containment Systems.
The OPERABILITY of the AC, DC, and AC vital bus electrical power distribution systems is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant.
This includes maintaining the AC and DC electrical power sources and associated distribution systems OPERABLE during. accident conditions in the event of:
a.
An assumed loss of all offsite or onsite AC electrical power; and b.
A worst case single failure.
The AC, DC, and AC vital bus electrical power distribution systems satisfy Criterion 3 of the NRC Policy Statement.
(continued)
ABWR TS B 3.8-2 10/21/93
Distribution Systems-Operating B 3.8.9
)
BASES LCO The required AC, DC, and AC vital bus power distribution subsystems listed in Table B 3.8.9-1 ensure the availability of AC, DC, and AC vital bus electrical power for the systems required to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence (A00) or a postulated DBA. All divisional AC, DC, and AC vital bus electrical power primary distribution subsystems are required to be OPERABLE.
Maintaining the three Divisions of AC and the four Divisions of DC and AC vital bus electrical power distribution subsystems OPERABLE ensures that the redundancy incorporated into the design of ESF systems is not defeated. Any two of Divisions I, II, and III of the AC, DC, and AC vital distribution systems are capable of providing the necessary electrical power to the associated ESF components. In addition, any two of Divisions I, II, III, and IV of the DC and AC vital distribution systems except the combination of Divisions II and IV systems (which are vulnerable to common failure because of their common AC power supply) a~e capable of providing the necessary electrical power to the associated RPS and ECCS safety system logic and control system components. Therefore, a single failure within any sys. tem or within an electrical power distribution subsystem does not prevent safe shutdown of the reactor.
OPERABLE AC, DC, and AC vital bus electrical power distribution subsystems require the associated buses (listed in Table B 3.8.9-1) to be energized to their proper voltages.
With the exception of a special set of manual interlocks through the spare battery chargers, there are no tie breakers between redundant safety related AC, DC, and AC vital bus power distribution subsystems. This prevents any electrical malfunction in any power distribution subsystem from propagating to a redundant subsystem, which could cause the failure of the redundant subsystem and a loss of essential safety function (s).
It does not, however, preclude redundant Class IE 6.9 kV buses from being powered from the same offsite circuit.
(continued)
ABWR TS B 3.8-3 10/21/93
=.
t t
~
Distribution Systems'-Operating B 3.8.9 BASES i
APPLICABILITY The electrical power distribution subsystems are required to be OPERABLE in MODES 1, 2, and 3 to ensure that:
a.
Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of A00s or abnormal transients;'and b.
Adequate core cooling is provided, and containment OPERABILITY and other vital functions are maintained, in the event of a postulated DBA.
Electrical power distribution subsystem requirements for MODES 4 and 5 are covered in the Bases for LC0 3.8.10,
" Distribution Systems -Shutdown."
ACTIONS A.lMA!2UAT314sdIA74 r
With one or more required AC buses, load centers, motor control centers, or distribution panels (except AC vital l
buses), in one division inoperable, the remaining AC.
electrical power distribution subsystems-(other divisions) are capable of supporting the minimum safety functions-necessary to shut down the reactor and maintain it in a safe shutdown condition, assuming no single failure. The overall reliability is reduced, however, because a single failure in i
the remaining power distribution subsystems could result in the minimum required ESF functions not being supported.
Therefore, the required AC buses, load centers, motor control centers, and distribution panels must be restored to OPERABLEstatuswithin12 hours.
The Condition A worst scenario is one division without AC power (i.e., no offsite power to.the division and the associated DG inoperable).
In this Condition, the unit is.
more vulnerable to a complete loss of AC power. Jf Condition A is entered,'Re'q'uiFed Action ^A.5 allow's 72'66'uFs' to restore the inoperable:AC electrical' power distribution" subsystem to OPERABLE status; provided the combustion' ' ~~ ~
turbine' generator (CTG)' is ' erified functional throu' fi v
g testin'g within,12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />andlits capability of being alfgiiid to the other OPERABLE 6.9 kV essential, AC buses'is v'erifiedi initially within'12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />', and once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />,thereafterJ The functi' nal' capability of the CTG is< verified in this' 'j o
6CTIONSL "71 A. I. A. 2." A.3. and A. 4 (continiied)' ~ ^"^ ~~ "^~ ^ '~"' ^ ^'~~
(continued)
ABWR TS B 3.8-4 10/21/93-
Distribution Systems-0perating B 3.8.9 BASES (continued)
ConditiAn{td[beijspablF7off tf61ngsThijsdltb[thiTOPERABLETES6 busesSto providesaibackupjpowernsource0 duping allossidfsall.
AC L event. JAt~ thE's a'me~t i me', 'thTUn i t
- Bpsa f o][s*"it'tidifod' r
shoul'd ~be focused on minimizing the potential for loss of power to the remaining two divisior; by stabilizing the unit, and on restoring power to the affected division. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> time limit before requiring a unit shutdown in this Condition is acceptable because:
a.
There is potential for decreased safety if the unit operators' attention is diverted from the evaluations and actions necessary to restore power to the affected division to the actions associated with taking the unit to shutdown within this time limit.
b.
The potential for an event in conjunction with a single failure of a redundant component in the division with AC power.
(The redundant component is verified OPERABLE in accordance with Specification 5.8, " Safety Function Determination Program (SFDP).")
i ThesecondCompletionTimeforRequiredActionAJ4 establishes a limit on the maximum time allowed 'for any combination of required distribution subsystems to be inoperable during any single contiguous occurrence of failing to meet the LCO.
If Condition A is entered while, for instance, a DC bus is inoperable and subsequently returned to OPERABLE status, the LC0 may already have been not met for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
This situation could lead to a total duration of 6fdsyi, since initial failure of the LCO, to restore the AC distribution system. At this time, a DC circuit could again become inoperable, and AC distribution could be restored OPERABLE.
This could continue i
indefinitely.
This Completion Time allows for an exception to the normal j
" time zero" for beginning the allowed outage time " clock."
l This results in establishing the " time zero" at the time the LC0 was initially not met, instead of at the time Condition A was entered.
The 7Lday Completion Time is an acceptable limitation on this potential to fail to meet the LC0 indefinitely.
]
ACTIONS fA.l.1A;2.'A'.3; and'AL4 (continued)
~~
(continued)
ABWR TS B 3.8-5 10/21/93
l o
Distribution Systems-Operating B 3.8.9 BASES (continued)
Re qu i fed l Ac t i onW 2!i si s pe ci fisd 46:ithif7a piiVbpfi s tif sEtiliiis
~
are :impl emented 1.in f accordance IWi tEthstuf fected & squired ~"~~
fe a t u re s ; o flLC0j: 314. 7f fo rf RHRlShu tdoWn:1CoolJndniMODE137 4
l B.1 and B.2 With one AC vital bus &c= cither Division I, II, or III inoperable, the remaining OPERABLE AC vital buses are capable of supporting the minimum safety functions necessary to shut down and maintain the unit in the safe shutdown becaus.i.on_._. OveFallEtFippeli.abil;itjHsNdinfilnsdHh6WsiTsFi condit eLthei vi.tal4.Aci buses? supplyFpowerito;;;thesRPS/MSIV ~~ ~
logi.c fand -co'ntrol;:l(onelofj;four1R.PS/MSIVJchhnnblf tEiRiri*ISSLC on ol os~si o f i poWe r)hto ired undan tj scramfp il ot: Land 2MSIV5ilotT s ol enoi d s, i NMS p and ' PRRM i; ;iThe re fo re nthe t.requ i red r ACWi t al bus'can be restopeditol0PERABLE;(sitatdM withinU23 6uf f "
Condition B represents one AC vital bus without power; potentially both the DC source and the associated AC source nonfunctioning.
In this situation, the plant is significantly more vulnerable to a complete loss of all noninterruptible power.
It is, therefore, imperative that the operator's attention focus on stabilizing the plant, minimizing the potential for loss of power to the remaining three vital buses, and restoring power to the affected vital bus.
This-14-houe-44mM-4 ; more c-enseevat4ve-than-Gomplet4en T4mes allowed-for the majority-of-eempenente-that-are
- Mhout-adequate-VMal AC powee---Tak4eg-except4en-te LGO 3.0.2 fee-eemponent+-*Mheut-adequate AC vMel-poweer that-would have Required Action Completion Times sheetee than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if deekeed-4noperabic, i'; acceptable-because of+
T he-potent 4a4-feHiee+ eased-safety-when-reqateing-a c.
change in phnt-condM4 ens (i.e., requiring-a shutdown) while not-a44 ewing-steble operations to cent 4nuet i
b.
The-potent 4al-fee-deeeeased-safety ahen requ4eing entey-4ntc numceous-appi4eaMe-GondM4 ens-and-Requ4eed AeMons-fee-eemponent-s-wMhout-adequate-44-te4-AG poweer-wM4e-not-prev 4d4ng-suf-fitient time fee-the (continued)
ABWR TS B 3.8-6 10/21/93 l
l l
i
s Distribution Systems-Operating B 3.8.9 BASES operator; to perform the necessary evahat4cn; and action; te rc;t+rc pcwcr to the affec-ted divisien; c.
The-petential for an event in c+nfunctica with-a s4ngle f 4hre of a redundant-c+mpenentr Each AC vital bu: supp&ics pcwcr at constant vcitage-and frequency tc the Safety System Logic and Centrol (SSLC) for the rc;oter protection system (RPS) which i; fail : fc.
The AC vital buses do not pr. ovide power to the SSLC for the ECCS. Therefore, the 72-hour Completion Time is specified.
The 72-hour Completion ~ Time also takes into account the impoFtance to safety of restoring the AC vital bus to OPERABLE status, the redundant capability afforded by the other OPERABLE vital buses, and the low probability of a DBA occurring during this period.
The second Completion Time for Required Action B.1 establishes a limit on the maximum time allowed for any combination of required distribution subsystems to be inoperable during any single contiguous occurrence of failing to meet the LCO.
If Condition B is entered while, for instance, an AC bus is inoperable and subsequently returned OPERABLE, the LC0 may already have not been met for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This situation could lead to a total duration of 3? day's, since initial failure of the LCO, for restoring the vital bus distribution system. At this time, an AC division could again become inoperable, and vital bus distribution could be restored to OPERABLE.
This could continue indefinitely, This Completion Time allows for an exception to the normal
" time zero" for beginning the allowed outage time " clock."
This allowance results in establishing the " time zero" at the time the LC0 was initially not met, instead of at the time that Condition B was entered. The ZMiy Completion Time is an acceptable limitation on this potential of failing to meet the LC0 indefinitely.
Action B.2 is specified so that appropriate restrictions are implemented in accordance with the affected required feature (s) of the LCOs' ACTIONS.
4*4endi-tien C, the--Mv4 Mon-4" AC vit+.1 bu: is inoperaMe.-
ReqMred Act4en: C.1 and C.2 allcw 12-heur; to cither eestere-this AC vital bus 10 CPERABLE status-cr cater the (continued)
ABWR TS B 3.8-7 10/21/93
l Distribution Systems-Operating B 3.8.9 BASES appMcable Condit4 ens--and fcllcw the Required Actions cf LEO 3.3.1.1, " Reactor Prctcction System-4nst+umenhtien,"
and LC0 3.3.1.2, " Source Range Monitor Instrumentation."
Mv4s4en IV is less critical than the other three AC vital-buses-beesuse-ef-Ms-MMied role in aetuat4eg-safety rehted fune14 ens.
It los: is not ;; crit 4 cal a: a 1000 of one of the other invertees -and-the less rest +4etive ACTIONS r
ef LC0 3.3.1.1 and-1-60 3.3.1.2 are-appropriate.
C.1 and C.2 In Condition C, the Division IV AC vital bus and one other vital bus are inoperable.
Because this condition is more severe than that of Condition B, only 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> are allowed to restore one of the inoperable AC vital buses to OPERABLE status.
This 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Completion Time reflects a reasonable time to assess unit status as a function of the two inoperable AC vital buses and, if one of the buses is not restored to OPERABLE status, to prepare to effect an orderly and safe unit shutdown.
D.l. D.2. D.3, and 0.4 With one DC electrical power distribution subsystem from Division I, II, or III inoperable, the remaining DC electrical power distribution subsystems are capable of supporting the minimum safety functions necessary to shut down the reactor and maintain it in a safe shutdown condition, assuming no single failure. The overall reliability is reduced, however, because a single failure in the remaining DC electrical power distribution subsystems (except Division IV) could result in the minimum required ESF functions not being supported.
If!CotjditisrE Dliis enteredfRequired: Ahtion iD.42all6wsl72?h6drsito19estbFeiths i noperabl e ! DC iel ectricali powe rjd i s tr i bu ti oni'subsfs' tem : t6 ~
~
OPERABLEistatus,?provided the combustibsfturbinbigessfat6si (CTG):: isi veri fied f functional; throughMestingtwi thin?124 han and:.:its;capabilitylofIbeingi aligned tolthelother10PERABLE~d 6.9; kV< esse ~ntials AC? buses)isiverified;:JinitiallyLW1thinjs12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> vandionce per!8ihoursithereaftsrTL.1Thsifunctionlal^ '
c ap abi l i ty o f 1 t he CTG (i s f veri fi ed ?i nithi.s::fCond i t i on j LVecau's:s_
thelDC electrical;powerLdistributionfsubsystemjprovides' (continued)
ABWR 1S B 3.8-8 10/21/93
i Distribution Systems-Operating B 3.8.9 BASES contr6H fdnct 16n s st6TtWdiffs f6n alIDGsTaddithETdiFEiil t breakersyRCIC.(DiVd))Mndjiothed16adf
' ^ ~ ~
Condition D represents one division (either Division I, II, or III) without adequate DC power, potentially with both the battery significantly degraded and the associated charger nonfunctioning.
In this situation, the plant is significantly more vulnerable to a complete loss of all DC power.
It is, therefore, imperative that the operator's attention focus on stabilizing the plant, minimizing the potential for loss of power to the remaining divisions, and restoring power to the affected division.
Th+s-F2-hour liet is more conservative than Completion Time; a'elewed for the majority of--component-s-that could be without-power.
Taking exception to LCO 3.0.2 fcr components w+t4m rdequate DC powcr, that. culd have Required Action Gomplet4en Times sheetee-than-1& hours, i: accept +Me because of:
a.
The potential for deercased-sa-fety-when requiring ehange-4n-plant-eendi-t4en: (i. c., requ 44ng-a shutdown)-whMe-not--aMewing-steMe-opees t4 ens-te eent4nuet b.
The-potential for-decrea cd safety. hen-eequk4ng entry into aumercus applicable Condit4 ens-and-Required Aet4 ens-fee-eempenents.;ithout DC power while net prov4 ding-suff4e4ent time foe-the operatees-to-perfcem the-necessary-evaluat4 ens-end-set 4 ens for rest +eing power to the affected-div4 icn; and c.
The-potential for an event in conjunction with s4ngle failure of a redundant-eemponent,-
EThe-leheue-Eempletion Time for DC buse is censistent-with Reguletery-Gu4dc 1.93 (Ref 3).]
The second Completion Time for Required Action D.4 establishes a limit on the maximum time allowed for any combination of required distribution subsystems to be inoperable during any single contiguous occurrence of failing to meet the LCO.
If Condition D is entered while, for instance, an AC bus is inoperable and subsequently returned OPERABLE, the LCO may already have been not met for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This situation could lead to a total duration of 6fdays, since initial failure of the LCO, to (continued)
ABWR TS B 3.8-9 10/21/93
~
Distribution Systems-Operating B 3.8.9 BASES restore the DC distribution system. At this time, an AC division could again become inoperable, and DC distribution could be restored OPERABLE.
This could continue indefinitely.
This Completion Time allows for an exception to the normal
" time zero" for beginning the allowed outage time " clock."
This allowance results in establishing the " time zero" at the time the LC0 was initially not met, instead of the time Condition C was entered. The Mdif Completion Time is an acceptable limitation on this potential of failing to meet the LC0 indefinitely.
Action P.1 isspecified so that appropriate restrictions-are implemented in accordance with the affected required feature (s) of the LCOs' ACTIONS.
E.1 and E.1 In Condition E, the Division IV DC electrical power distribution subsystem is inoperable.
Required Actions E.1 and E.2 allow 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to either restore this DC
.distribut. ion,Trddifeemto_0PERABLE_s.ta,tusordEMjf5 subsyst affsEt sturesdnoperabls.r Division IV is less gg.edere.qu.g gg.gg.ie"DC"sisHrical power gg distribution subsytems because of its limited role in actuating safety related functions.
Its loss is not as critical as a loss of one of the other DC distribution subsystems,andthelessrestrictiveACTIO!iSof((fsjQ3 LCOs are appropriate.
F.1 and F.2 In Condition F, the Division IV DC electrical power distribution subsystem and one other DC distribution subsystem are inoperable.
Because this condition is more severe than that of Condition E, only 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> are allowed to restore one of the inoperable DC distribution subsystems to OPERABLE status.
This 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Completion Time reflects a reasonable time to assess unit status as a function of the two inoperable DC distribution subsystems and,. if one of the subsystems is not restored to OPERABLE status, to prepare to i
effect an orderly and safe unit-shutdown.
(continued)
ABWR TS B 3.8-10 10/21/93
)
Distribution Systems-Operating B 3.8.9 BASES G.1 and Gd If the inoperable electrical power distribution system cannot be restored to OPERABLE status within the associated Completion Times, the plant must be bought to a MODE in j
which the LCO does not apply. To achieve this status, the i
plant must be brought to at least MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to MODE 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.
SURVEILLANCE SR 3.8,9,1 REQUIREMENTS Meeting this Surveillance verifies that the AC, DC, and AC vital bus electrical power distribution systems are functioning properly, with all the required circuit breakers closed and the buses energized from normal power. The verification of proper voltage availability on the buses ensures that the required power is readily available for motive as well as control functions for critical system loads connected to these buses.
The 7 day Frequency takes into account the redundant capability of the AC, DC, and AC vital bus electrical power distribution subsystems, and other indications available in the control room that alert the operator to subsystem malfunctions.
REFERENCES 1.
2.
3.
Regulatory Guide 1.93, December 1974.
ABWR TS B 3.8-11 10/21/93
i Distribution Systems-0perating B 3.8.9 i
i Table B 3.8.9-1 (page 1 of 1)
AC, DC, and AC Vital Bus Electrical Power Distribution System BUS TYPE AND DIVISION DIVISION DIVISION DIVISION SYSTEM VOLTAGE 1*
2*
3*
4*
AC ESF Bus M/C E M/C F M/C G Not Buses 6900 V Applicable Power Center P/C E10 P/C F10 P/C G10 480 V P/C E20 P/C F20 P/C G20 i
Motor Control C/B E110 C/B F110 C/B G110 Center C/B Elll C/B F111 C/B Gill 480 V C/B Ell 2 C/B F112 C/B G112 C/B E113 C/B Fil3 C/B G113 C/B E120 C/B F120 C/B G120 C/B E260 C/B F260 C/B G260 Distribution IP A10 IP B10 1P C10 Panel IP A20 IP B20 IP C20 120 V DC Motor Control DC MCC Al Buses Center 125 V Distribution DC A10 DC B10 DC C10 DC D10**
J Panel DC A20 DC B20 DC C20 DC D20**
125 V AC CONSTANT All Bil C11 Dll***
Vital VOLTAGE.
A21 B21 C12 D12***
l Buses CONSTANT
[RE0VENCY DISTRIBUTION
{
PANEL i
120 V j
Each division of the AC, DC, and AC vital bus electrical power distribution system is a subsystem.
1 The battery charger for Division 4 DC subsystem is powered by a Division 2 480 V AC motor control center.
ABWR TS B 3.8-12 10/21/93