ML19221A911

Reg Guide 1.93, Availability of Electric Power Sources

ML19221A911
Person / Time
Issue date:	12/31/1974
From:	NRC OFFICE OF STANDARDS DEVELOPMENT
To:
References
REGGD-01.093, REGGD-1.093, NUDOCS 7907100337
Download: ML19221A911 (9)

Text

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December 1974 I i 555ib" d b RY GU DDE

• r, DIRECTORATE OF REGULATORY STANDARD 3 REGULATORY GUIDE 1.93 AVAILABILITY OF ELECTRIC POWER SOURCES A. INTRODUCTION than are required by GDC-17 can tolerate the loss of one or more sourtes ed still meet the If0. Dunng the Section 50.36(c)(2), " Limiting Conditions for Opera-normal course of operation however, any nuclear power tion," of 10 CFR Part 50." Licensing of Production and plant raay lose power sources to the extent that the if0 Utth2ation Faahties," requires the Technical Specifica-is not met. This guide addresses such cases tions to include the limiting conditions for operation GDC 17 specifies design requirements, not operaung (LCO) and actions required to be taken by the hcensee requirements, it therefore does not stipuiste opera-when the LfD is not met. Power operation may be miti-tional restncuons on the loss of power sources Never-ated and contmued without restnction only when the theiets, operational restnctions based on the intent of Lf 0 is met.

GDC-17 on the loss of power sources have been included This guide describes operatmg procedures and restric-in the Techrucal Specifications of recently bcensed tions acceptable to the Regulatory..aff which should be nuclear power plants. Such restncuons are based on the implemented if the available electric power sources are following assumpoons less than the LCO. This guide is appl cable to single and e The I.f0 of nuclear power plants is met when all multi-unit plants, including multrumt plants that share the electnc power sources required by GDC-17 are the required electric power sources.

available.

The LCO with respect to available electne power e Under certam conditions, it may be safer to sources is an electnc power system that satisfies General continue operation at full or reduced power for a limited Design Critenon 17 (GDC-17)," Electric Power Systems,"

time than to effect an immediate shutdown on the loss of Appendix A. " General Design Critena for Nuclear of some of the required electric power sources. Such Power Plants," of 10 CFR Part 50 by meluding the follow-decisions should be based on an evaluation that balances ing electnc power sources:(1) two physically tndependent the risks associated with immediate shutdown against circuits from the offute transmtssion network, each of those associated with contmued operation. If, on bal-which is either continuously avadable or can be made ance, immediate shutdown is the safer course, the unit avadable withm a few seconds followtng a loss-of-coolant should be brought promptly to an orderly shutdown, accident (LOCA), (2) redundant onste a.t power sup-and to a cold shutdown state as soon as possible. For phes. and (3) redundant onsite d.c. power supplies.

example, the nsks associated with an immediate shut-Nuclear power plants wherein only one of the two iown on the loss of onsite a.c. power supply dunng a required offsite circuits can be made available withm a penod of light system load would tend to be less than few seconds followmg a LOCA are outside the scope of those du.ing a peak load penod because the stabdity of this guide. However, the restnctions imposed on such the offsite power system would be relatively higher, if, balance, contmued power operation is the safer plants on the loss of required sources would generally be on more stnntent than those recommended in this guide.

course, the penod of conunued operation should be used to res: ore the lost source and to prepare for an B. DISCUSSION orderly shutdown, provided, of course, that these activities do not nsk further degradation of the electnc laectnc loads important to safety of nuclear power power system or in any way jeopardiz.e plant safety.

plan ts are served by an electne power system that e If the LCO has not been achieved, the unit shou'd conforms to GDC 17. Plants with more power sources be promptly brought to an orderly shutdown after the USAEC REGULATOMY GUIDES Coo.es of peehed p. esse any me obiemed by ree.en.M.est.as tw d.ve eas see.ned se t he va Ateenic s eer,v ceranese.ea, vuesNyen, cf. 2cs44 A *ewin e er y G ouses e,e.nsoed so e,m.tw ems ase e ea b= to ihe puenhe A s ters om o. career of Regulestry stenderes. Cemsats eM euggest.een 'er s

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_e allowed time for continuc4 power operanon he elapsed 2, N AvaaaMe Offalta A.C. Power Sources Are Two and to a cold shutdown state as soon.ts puesiMe Lms Thaa the LEO.

thervatier. The premsse here is that the uma allowed for conunced operation could have been used to enhance the safety of the imm.nent shutdown For example, the TMs deyadnion level means that the offsite power system does not have the capabdity to effect a safe dispatcher could take such system-wide ac tions as increasing generanon at other plants or dropping se.

shutdown and to mitigste the effects of an accident; let ted loads to ensure that the shutdown does not cause however, the onsite a c. system has not been degraded.

gnd mstabdity. In addition. il the hiss of sources beyond This depadauon level generally corresponds to totalloss

, the if0 were to wcur dunng a peak load penod. the of the immediately accessible offute power sources.

allowed operating time could he used to defer the Ektause of the normally high availabihty of the shutdown to an off pcak penod when the stabhhty of offsite sources, this level of depadacon may appear to the gnd should be higher.

be more severe than the next two degradation levels To develop bases for specific guidance. five levels of listed. Howeve r, two factors tend to decrease the degradanon of the power systems are descnbed below in severity of this depadation level as compared to the order of increasms severity:

next two degradation levels:(a) the configuration of the redundant a.c. power system that remains available for this degradation level is not suscept2ble to a smgle bus or switchirig faihsre, whereas the next degradation level

1. The AvailaWe A.C. Power Sources Are One Less Issted (No. 3) may be so susceptible, and (b) the time Than the LCO.

required to detect and restore an unavailable offsite Ttus degradation level means that one of the required Power source is generally much less than that requ2 red to detect and restore an unavadable onute a.c. power offsite or onnte a c. sources is not avulable. Thus, either source.

the offsite or the onute a.c. power system has no redundancy; however, each system retams full capability This degndation can be caused by any of several (one system with redundancy) to effect a safe shutdown events, including the loss of two offsite circuits, an unstable offsite power system, or any condition that and to mitigate the effects of a deugn bas s accident.

Operation could therefore safely contmue if the avail-renders offute power unavadable for safe shatdown and emergency purpmes. Smce the onsite power system has abihty of the remainir;g sources is venfied; however, n t been depaded and since simultaneous loss of offsite unce the system is degraded below the LCO, a ume hmit Power and a LOCA were postulated as a deugn basis, a on continued operation is warranted Operatmg expen.

bnef mterval of centinued operation is justified. (Note:

ence-indicates that the avulability of a typical offsite source is tugher than that of a typical onuts a c. supply.

S me nuclear Power plants are designed to cause an Thus, if nsk is evaluated in terms of avulabihty, the nsk automatic shutdown or to initiate load rejection at this lev-l I depadation. Plants deugned to cause an auto-associated with the loss of an of'ute power source (the source with the higher avulalahty) would appear to be matic shutdown at this level of degradation need no more severe than the nsk associated with the loss of an further discusuon; however, those that reject load are onsite a c. supply (the source with the lower avulabil-C'isidered to remun operating Mthin the context of Ss guide )

igy )

H oweve r, this apparen t ifference m seventy is usually offset by muntainabdity considerauons; that is, the time required to detect and restore an unavulable

3. The Availa',le Offsite and Onsite A.C. Power Sources offsite source is generally much less than that required Are Each One i esa fhan the LCO.

to detect and restore an unavulable onsite a1. supply.

Based on these consderations, a general distinction This degradation level results in the loss ofindividual does not appear to be warranted for operating restric-redundancy in both the offsite power system and the tions se ciated with the loss of an offute source and onsite a c. power system. However, since power system thcze r inctions assocsated with the loss of an onsite redundancy is provided by two diverse sources of power, a c. supely. However, the loss of an offsite source due to the rehabibty, and hence the safety, of this degradation a cause associated Mth extensvr consequences such as a level appears to be higher than that of the previous severe rce storm or a forest fire ould have impli:stions degradation level. This apparent improvement could, more severe than the loss of an mute s e,, ply. The however, be offset by the susceptibdity of this power nsks associated with such an offute loss would be system configuracon to a single bus or switchmg failure.

compounded by three effects: (a) the maintunabthty For example, the fulure of an emergency power advantage of the offsite sources would be lost,(b) the distnbution bus that is energized by esther the ungle remaming off:ite circuit could be susceptible to the same avslable offsite arcuit or the ungle avadable onnte a.c.

cause, and (c) the stability of the offsite power system supply cou}d render all emergency a.c. power ineffective.

nught be affected. Thus, the loss of an offste source by Based on these conuderations, the operating restric-such a cause should be treated as equivalent to the loss tims imposed m this level of depadation should be of both required offute surces unular to those of the previous degradation level.

l 93 2

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However, the allowed operating time should be short-C. REGULATORY PC3l TION ened because the onnte a.c. power system has been i

degraded, and the umultaneous loss of the offute power The intent of each regulatory position is io imple-and a LOCA (or any event that causes generator trip)is a ment the safest oper:Ung moda wnenever the uvaslable design bans event.

electric pour sources are less than the I.f0. Accordmg-ly, vanous levela of degradation of the electnc power system are hated below m order of increasing degrada-tiai; t e regulatory poution given for each degraded

4. the AvmisWe Omue A.C. Electne Power SuppUes h

Are Iwo Less Than the LCO.

lent should be incorporited in the Techn cal Specifica-uona. Whenever the Techrucal Specifications allow unre-l!us degradation level means that the onnte a.c.

stncted ope ration to be resumed, such resumption power system does not have the capabihty to effect a should be contingent on the venfication of the mtegnty safe shutdown and to mitigate the effects of an accident.

and capability of the restored sources. Wheriever the in a single urut niant, this condition usually means the Technical Specificauons allow power operat2on to con-unavulabihty of two diesel generators. In multi-unit tinue danng a specific degradauon level, such continued plants that share onsite a.c. supphes, this degradauon power operauon should be conting:nt on (a) an imme-level means that the avulable ortsite supphes,if any, do diste verification of the svadabihry and integnty of the not have the capacity to mitigste the effects of an remamtng sources, (t) reevaluation of the availability of accident m one unit and to safely shut down the o*her the remaining diesel-generator (s) at ume intervals not to umt(s).

exceed eight houn, (c) venfication that the requirev Smce the offute power system is the only source of mamtenance actmties do not further degrade the power a c.

power for tlus level of degradation, the risk system or m any way jeopardize plant safety, and (d) associated with contmued operation for a very short compliance with the additional conditions stipulated for time could be less than that associated with immediate each specific degradation level.

shutdown (the immediate shutdown could cause grid 1.

If the ava !ah!e a c. power sources are one less than instabihty which could result in totalloss of a c. power).

the LCO, power operation may contmue for a penod Ilowever, smce any inadsertent generator inp could also that should not exceed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the system stability result in total loss of a c. power, the ume allowed for and reserves are such that a subsequent smg!e failure contmued operation should be severely restricted. The (meludmg a inp of the ururs generator, but excludmg an mtent here is twofold. (a) to avoid the nsk associated unrelated fulure of the remairung offsite circuit if this with immediate shu tdown and (b) to subsequently degraded state was caused by the loss of an offsite minimize the nsk associated with this level of degradt-source) would not cause totalloss of offsite power.

tion by severely Itmitingits exposure time.

If th"e condiuons for contmued power operation are A concerted effort should be made to restore at least met and the affected source is restored withm 72 houri, one onute a.c. supply dunng this restncted time penod, unrestncted operauon may resume. If the conditions for and system-wide acuons shculd be miuated to ensure continued power operation are rr.et but the source is not that the offsite power system can accommodate the restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the unit should be brought to immment shutdown.

a cold shutdown state withm the next 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> If the conditions fcr continued power operation cannot be met, the uru t snould be ramped down

5. The Avadable Onsite D.C. Supplies Are One Lesa immediately to the mmi:num power lewl required for Than the LCO.

stable omath>n (preferably that required to accommo-date the urut's aux 1hary loads ortly). The rampmg rate This degradauon level means that the available d.c.

should be at the maximum permitted by the Technical power supphes do not have the requi ed redundancy; Specifications without resorting to blowdown. While the howeve r, the d.c. power system has full functional Urut is op:ratmg at this reduced power level,it should cambility to effect a safe shutdown and to nuugate the provide trunimum real power to the grid (preferably eHects of an accident. Since a subsequent degradation uro); however, the gnerator may supply reactive power could jeopardize plant safety (e.g., a subsequent smgle to the grid within ita rating, as required to enhance grid fadure could render the entire power system ineffective stabibty. The urdt may operate at tMs reduced power on a generator tn?), the ume allowed for contmued level for a period that should not exceed 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. If the operanon should be severely restncted. If the affected affected source is restore I within 43 hccrs. unrestricted

d.. supply is re toied within t' :s ame penod, unre-operation could be treumd. If not, the unit should be stncted operauon may be resumed. If not, the unit brought to a cold shutdo vn state within the next 36

hould be brought promptly to an orderly shutdown and hours.

to a cold shutdown state as soon as posuble. The required functions of the d c. system should be entica!!y i

g monitored dunng the shutdown penod and correcuve

%,., (5 theets) ypeded to tw guje. These sheets depict actions taker, if rr juired. to ensure the safety of the graphicdy the recta.rory poen for ca.ch of the rive levels of sh u t dowTi degradanon cmcred t>y ti 3, =. 0 9 f

1.93-3

2 11 the available offsite a.c. power sources are two lets for a period that thouk not exceed 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. If both sources era restored mit et this 12-hour period. unre-than the LFO, power operation may conttr.ue for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if it appears hkely that at least one of the offsite stricted operation may be recumed If etther an offitta or an ortsits a.c. source is restored withfn this 12-hour sources can be restored withm 24 houn.

if these wndmons for cont!nued power operauon are penod, reduced power operahon may continue for an

.nd both olf ute sources are restored withm 24 additional 12 houn subsequent to the retteratton of one me t sou rce. If the other source t r-stored withm these hours, unrestncted operation may be resumed. If only ooc ofkite source is restored within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, power additmetal 12 houn, unrestricted cperauon may resume; operation may continue for a total time that should not if not, the unf t thcold be brought to a cold shutdown e xceed 72 houn in accordance with the conditions state withsn the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> If netther un offsf te nor desenbed in ReFulatoiy Poo tion I (loss of ane a.c.

an onsite a,c, source is resto:ed wittun the first i2 hours source ) If no of fsne source o restored withm the first of reduced power opention, the unit shoeM be brought to a cold shutdown state within the next 36 hoisrs.

24-hour penod of cont 2nued oower operation, the unit should be promptly shut down and brought to a cold 4.

If the avadable onsJte a c. electne tuppbes are two shuidown state, or the lowest attairuble pressure tem-less than the IfO powr operation may continue for a perature slate. wahm the neitt 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> penod that shodd not exceed tw a houn. If both onsite a c. electric power suppbes are resto'ed within theie two 11 the conditiom for continued power ope rsoon houn, unrestricted operanon may be resurmd If only cannot be met, the umt should be ramped down to the one onsf te a c. supply is restor-d within these two htmn, mimmum power level as descnbed in Regulatory Pos).

Power operat:en may contmue for a total ume that tion i Ihe umt may operate at this reduced power level exceed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in accordance with the should not f or a penod that should not ex eed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. If both conditions descnbed in Reguintcry Fosttion I for the offsite sources are restored withm the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> penod, Icus of cxie a c. soi.rce. If no onnte a.c supply is restored unrestncted operanon could be resumed !! only one withu the first two houis of continued power operatice, is restmed withm thts 24-hour pem>d, the umt should be brought to a cold shutdown nate

.,u m me reduced power operat:on may continue for an addinona!

within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> 24 houn suhequent to the restoration of one source if

5. If the avn Jable or, sac d c. supplies are one less than the other of fsite source is restored wHhrn thr; additional the 1f0, power operanon msy contmue fot a period time, unrestncted operanon could be resumed, if not, that thodd not exceed two hourt if the tfiected d.c.

the unit should be promptly shut dm and brought to a supply a restored within these two huers, unrestricted cold shuidown state, or to the lowest attainabb pres.

peration may be resumed if not, the urut should be sure temreratur state. withm the neitt 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> if no brought prompdy to a controlla! shmdown and to a of f site source is restored withm the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of cold ihutdown state within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The re-s reduced power operahon, the umt shouhi be shut down quared funct ons of the d c system should be critically as pr viousN described mordtored dunng the shutdown process and necesary 3

If the omlab!e offsite and onute a c power sources actions taken, such as cro-sorrecun?, a supply to a are eac.h one tess than the LCO, pawer oorratmn may I ad. if required, to ensure a sMe r.hutdown.

ton true fot 12 houn if (a) the reerves and system The operating ume knuts d6mented above are ex-stabihty are such that a subseq 2cn t smg!c fm!u re phcitly for correcove m!untenance aetmues ordy. The (mcluding a inp of the umt's e+nermior, but excludmg an

-rattng time hmus should not be construed to mclude unrelated future of the remunmg offtite circuit) would not caw total loss of offute power and (b) it :Pfears

).

entive maintenance actm u~ whch require *he hk ely that it least one of the affected sources can be imapacitanon of any reqwred electnc power source.

Such actmoe:, should he sch*duled for performance rest red wnhm 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> dunn3 cold shutdown and/or refochng penods if th-w conditions for cononued power crera:an are net ard toth sources are restored wahm 12 hcors, unresincted operanon may be re sume d if either an D. WPLEMcNTATION offute or an onsite a c source is restored withm 12 h ou rs

.er opeinhon may contmue for a total time The purpcae of this vction is to provide information that she ld not euced 72 houn in ccordance with the to applicants and hcenee, rtgsrdbg the Re:p.J arory condinon desenbed m Regulatery Pounon I for the loss staffs plans for utthung this reru!stors gmde.

This guh reflects current reptatery pract cc There-of one a c. source. If neither an offsne source nc in onsac source is restored wC:a the first 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of fore, except ir; tho.c cars r whkh the apphcant continued powr operation, the umt shou!d be brought prepaes an acceptable d:ernance nvihod for comply-to a cold shutdown state wittun the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> in, with spedfied poraons of ti,e Cunnession's reguls-If the c on ditwn s for conunued power operauon ticcs, this ;;uide will be used by the Regu! story staff in cannot be met, the unit should be tamped down to the eve!uathq all construction penrut rpphcahons for which nummum power lael as descnhed m Regulatory Poe the usue date of the Safety Nusuon Report (SER)is uon l The unit may operate at this reduced power level July 1,1974, or after 126 000

DECISION FLOW DIAGRAM FOR AVAIL ABILITY OF ELECTRIC POWER SOURCIS e T A rt T (REGULATORY POSITi(W41 - THI AVAILABLE A.C SOURCES ARE ONE LE!S THAN T (E LCO)

REQUlftED

\\

(NOl AC SOURCES

/

AV AIL A SLE P 27 ONLY N

ONE AC.

(go)

(YESI SOURCE NOT

=

1 (Tt s SHEET 2)

AV AILAUL E ?

/

(TO 1HEET 5)

R E QUI R ED MI D C. SOURCES AV AIL A BLE ?

Is4 4EDLAllLY REDUCE CONOt TiONS (NO)

P0 9E R (M %Y OPE R ATE SATISFIED FOR POWER f AT REDUC ED POWER Of1ER ATlON TO pc R 48 HF 8, MAX.)

CONTINUE ?

(FROM OTHER SHEETSI (YES)

't it POWE R OPE H ATION MAY CONTINUE FOR 72 HOURS RESTO E1 THIN f

N 48 H XJR$7

\\

\\

SOURCE

\\ (NO)

(YE S)

RE S TOREO WI THIN i'

72 HOURS?

(F ROM OTHE R SHEETSI (YES)

=

(FROM OTHER r

r LCD SA TISFIED -

tid!ME D1' Ti LY SHUT UN R E STRICTE D DOWN UNIY AND

\\

CPER AT10H MAY gap 40 TO A COLD CONTINUE OR SMUTCO W STATE EKREtuutD WITHIN M 40tTi (E N D)

(E N D)

OtEET1OF5 126 081 l.93 5

(FROM $HEET 1)

(REGULATORY POSITK)h 2 - THE AVAILABLL OFFSITE SOURCES ARE TWO LESG THAN THE LCO)

TYtO OF F SITE eNO)

L 2

(TO CHCE13) flOURCE S ON LY NOT AVAIL?

(YE&)

(X)NOITONS laQtEDIATELY REDUC 2 RATISFIED FOR POWER (NOi _ poggg ggAy opgg Ayg x

AT REDUCED POWER OPER ATON TO INUE7 FOR N Nff, MAX.)

(YES) t mm POWER OPER ATON pg

,79,9 MAY COdilNUE N HOURS?

FOR 24 FWI, MAX.

ONC (YEg) 500RCC ir RESTOR E D WITH!N 24>'LORS?

s (TO 8HEET 1)

(YES)

DOTH REDUCED PWR OPER.

j 200 ACES (NO)

RE STORED WITHIN MAY CONTINUE FOR 34 HOURS?

AM ADOITON AL 24 HOURS.

(YES) v OTHER SOURCE

.1 (NOl _'r OtJE I;E STO RED WITHIN SOURCE EL 24 HR?

RECTOR ED WITHIN 24 HOUR 37 (YEI)

(YE8)

P u

y y

\\'/

V WV W

m (TO ",HE E T 1) sHEE F 2 OF 5 nq2 L0 UL 193 c

(REGULATORY FOSITION 3 - THE AVAILABLE ONSITE AND U ROM sHE E T 21 OFFSITE A.C. SOURCES ARE ONE LESS THAN THE LCO) 2

-N \\

' ONE OFFSITE &

ONE ONSITE SOURCE (NO) r 3

(TO SHEET 4)

ONL Y NOT AVAIL?

N (YES) y

,/ CONDI TIONS IMMEDI ATE LY REDUCE

\\ (NO POWE R (M AY OPER ATE

[ SATISFIED FOR POWER N

OPER ATION TO AT REDUCED POWER

\\ CON TINUE ?

FOR 12 HR. MAX.)

(YES) goyH URCES (NO) u RESTOR ED WITHIN r

12 HOURS?

POWER OPL R ATION

\\

MAY CONTINUE (YES)

ONE FOR 12 HR MAX.

'I SOURCE gy RESTORED WITHIN V^

12 HOURS?

(TO SHEET 1)

(YES) 00TH REDUCED PWR OPER.

SOURCES (No)

MAY CONTINUE FOR R ESTORED WITHlh AN ADOITIONAL 12 HOUR $?

12 HOURS e

1f o

OTHER (YES)

ONE SOURCE pg))

R ESTORED WITHIN SOURCE ggo)

R E3 TOR ED WITHIN ADDL 12 HR7 12 HOURS?

(YES)

(YES) o ir y

y qr V

V

\\V V

V

~

J

\\

v (TO SHEET 1)

SHEET 3 0F 5

(

126 083 1.93 7

(REGULATORY POSITION 4 - THE AVAILABLE ONSITE A.C.

(FRou SHEET 31 POWER SOURCES ARE TWO LESS THAN THE LCO) 3 TwO ONSITE A.C SOURCE 5 ONLY NOT AV AIL.?

(YES) ir POWE R OPERATION M AY CONTINUE FOR 2 HR, MAX.

,r

/

BOTH SOURCES (NO)

RESTOR ED WITHIN 2 HOUR $?

v ONE (YSS) f,00 RCE (No)

RESTORED WITHIN 2 HOUR $?

(Yell I

irV V

V 2

t (TO SHEE71)

EHEET 4 OF 5 hk 1.93-8

(REGULATORY POSITION 6 - THE AVAILABLE ONSITE (FROM SHEET 1)

D.C. SUPPLIES ARE ONE LESS THAN THE LCO) 4 ONLY ON E O.C.

SOURCE NOT AVAILABLE?

LYES) 1r POWER OPERATION MAY CONTINUE FOR 2 HOURS ir D.C.

SOURCE (NOl RESTORE D WI THIN 2 HOURS?

(YES)

U ir (TO SHE ET 1) 126 085 EHEET6OF5 l.93 9