ML20217H693

Proposed Tech Specs Revising & Clarifying Requirements for Offsite Power Sources

ML20217H693
Person / Time
Site:	Vermont Yankee
Issue date:	10/10/1997
From:	VERMONT YANKEE NUCLEAR POWER CORP.
To:
Shared Package
ML20217H689	List: BVY-97-130, Application for Amend to License DPR-28,revising & Clarifying Requirements of Offsite Power Sources ML20217H693
References
NUDOCS 9710170007
Download: ML20217H693 (17)

Text

- _ _ _ _ _-___ _ _ - - _ _ - _ _ _ - .

VYNFS 3.10 LIMITING CONDITIONS FOR 4.10 SURVEILLANCE REQUIREMENTS OPE' RATION

3. Emeroency Buses 3. Emercency Buses The emergency 4160 volt The emergency 4160 volt Buses 3 and 4, and buses and 480 volt 480 volt Buses 8 and 9 buses shall be checked shall be energized and daily.

operable.

4. Off-Site Power 4. Off-site Power

[ a. least no off-si q, The status of the J off-site power sources trans saion 1 e shall be checked daily, an at least no art-up i ransfo in

% gu.dfied serviceit b. Oncs per opereMn3 o VF- sN ?*wer b. on of the '

' * *7

• Sowfce t. lowing a*Ccb5 s..e c.s. .nball

{ co ur3Ve3 6V addition sources y 3 Q g.sk a l

g g,,g g A of del ed access beac.

powe w.+bte on e, ACCe &% E ** u fC#-

ana +be det yea e main se up ransform and e cc.33 s . cc.s. ) unit a liary g.,\\ b s-f trans rmer /

e u c p ga.4 a d av able and able of oper.bia . supplying wer to the ese ency 4160 It buses r, 4160 vo tie ine to V non Hydro- ectric stat capable su ying powe to her of th two emergency 60 volt buses.

5. Reactor Protection System Power Protection 5. Reactor Protection System Power Protection Two RPS power protection panels for Once per operating each inservice RPS HG cycle, the operability set or alternate power of each overvoltage, source shall be undervcitage, and operable, underfrequency protect ive device shall be demanstrated by the performance of an instrument channel 9710170007 971010 calibration test.

PDR ADOCK 05000271 Settings shall be P PDR verified to be in accordance with Table 4.10.1.

Amendment No. M, 14. 125 214

l l

l VYNPS j 3.10 LIMITING CONDITIONS FOR 4.10 SURVEILLANCE REQUIREMENTS OPERATION

f. From and after the date that one of the two 125 volt Switchyard battery g,g P, systems is found or *** U'b\ t ,*k*'****tet*3 made tc. be #***

J r s .1 i3...

DS M ****'3t*t3.g ,y inoperab.Se for any reason, cc..it i nu ed A ,c6, . 53 reactor operation * ** * # 3 6*

• 3 b =8+n .e4 6 Law ,

is permisaib1e P e a es e c.e s & c,.&4. .J f provided that the " "*).c&ja tb*** h.as s b u k=ve /

sk.A Vs w a r f ft *A other 125 volt Switchyard battery *9*'*bh w I4b1* * * * - k'**

• • t" 9*' *f3 M b"#8 system is operable. *d w er . Mar.

3. Off-Site Power

3. Off-Site Power

a. From and after the

&A dat_e tha_t t a. Wher. one f rft.a r p plesep gen ators one o Ws M *- P%c f tra former and j 'or dsoci ted bus a c o.<ce t.s made .c f.,.ind ' on diesel is de foun to I

+e de u s psrabic. f.c any [g erator or

, b inop able, he reason 3 r e. c.br op erd:.. smociat d buse quir ents o j are ma or to d peci icatic y1 g,g o, 4,, ,,

to be inopera e 4.5. .1 shal be d*'I S Pr.wi es4 *c. for ny reas , yeat stied, reena 1Ma$ M ar&< .>.orce., rea tor ope tion b e+ b worg**c-) cat c. n e.l / maf contin provided e S***ra4*fs,asa

c. 4.c g soc.3 ct.4c2bwat ,g } s requirem

.44 ts of t..w Pre ss re, c.r e ..a Specification qw 3 3.5.H.1 are art <,p s<wMe .c,a If b a satis (ied, t

r egutes.$. t ca.. 4 he

b. From and after the b. b th de yed Q '3, [',{'s) be 0 date that t acc s off- ite g;p % g .a g. 'cetay9a acce po r sour es are n u4.c h,u b w e4J ff- its po r up vaila e, bot skaa. in w aktw t e k rs sou es be ome fr,esel nerato s gng a 4k e., dike.. .p unp alla e, and as ociate sp.ci fte.vt.* ).to. s.T .b rpact r perati buse shall ve may co inue f r bee or sha be ces, attWt,gg c. sevendaysprvided{ -

de natrat d to b

/f ,di bot emerge erable ithin

(- el gen rators, (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, ap ociate, buses,

""d *1' " ~

6h 4 tine .pr.th, p. war s..rcs .wd on e. die ut Pressu Core e d Whom e tther effet b p., s., a *wees oc J gente, +,e .ce ve*4s or Conta ent CGIoling " t- 4 t t s4 e.c . ss .c.c d e.A b se s se s

(.. 4 .+. lee,ta.g.c. hts (., Syst us are ow.wMhM e g an,ica s.n, c.. h s4 Lope able sper u n ta 9.e.a m .4 f.c t. -th s .4b.w .tf,14 , p.,,,, 3 vce 24 h..cs as ) 3 46 h rs win 3 .mA p.,aw h

• • 4 4 L.w 9m isse s C., ..J c..w es , As e smuw 3 di a s.) 5.c.cate,sas.trd=4 l Ce* t'la

• wh C.4 tap 372 h

• Sk

• c.s .,5.es3 t o. a s s %*4 at L...a 9 es s a <e (.< s. A havs bes.a .c sbn to v.e !ft d c . =4 a*% w.**4 C..N3 blab 6 .'s M srskh . rf 0 psf *bt* wt+bta **

• b * *# * *d 4kh es *tesws d es .A % . ** sk , .cd er sg

• m a.s 9se v'M b.

• A **. 4 *.

Shad **}* sk.\\ le s. t 4744 ,,4w,e 4y

that %s 14 c. 14 sk J 4 e.

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Amendment No. M, H4, 125 217

VYNPS BASESr 3.10 AUXILI ARY ELECTRIC p0WER SYSTD13 A. The objective of this Specification is to assure that adequate power will be available to operate the emergency safeguards equipment.

an im.%cdte4s Adequate power can be provided by any one of the following sources:

.cce ss s.wece Eith:: ;; th:]startup transformers, backfeed through the main 49 he 8(transformer, ydehedD or either C:  !!'" Wlt lin; hee. O.e Ve r ~.. Jit ee ' ec t ;;-c ]

oC the two diesel generators. The backfeed through the main transformerclnd n ;; :;t V:::: lin  :: be t h) *, s a.

delayed access off-site power sources._fBacKt eding rough a mat (crans rmer-c n De acpumeAran a py a connec ing th main g erator from he mai transtgemer an energ ing th auxil ry tra former fr the 34 kV swi chyard rough he mai trans rmer. he time re ired t perfo this d connec ion is approx tely s x hours 4160 olt lin from t e Verno Hydro lectri Station can be JD4 stat A nnecte to eit er of t e two e rgen buses ithin a conds b j Lsimple nual s itching _operati n in t e_Hain ontrol R om.

3 Two 480 V Uninterruptible Power Systems supply power to the LPCIS valves via designated Motor control Centers. The 480 V Uninterruptible Power Systems are redundant and independent of any on-site power sources.

L at This Specification assures that at least two off-site and two on-site power sources, and both 480 V Uninterruptible Power Systems will be available before the reactor is taken beyond 'just critical

• testing. In addition to assuring power source availability, all of the associated switchgear must be operable as specified to assure that the emergency cooling equipment can be operated, if required, from the power sources. g Station service power is su plied to the station through either the unit auxiliary transformer r the startup transformers. In order to start up the station.(Et 1;;;t n:3 startup transformers required to supply the station auxiliary load. After the unit is synchronized to the system, the unit auxiliary transformer carries the station auxiliary load, except for the station cooling tower loads which are always supplied by one of the startup transformers.

The station cooling tower loads are not required to perform an engineered safety feature function in the event of an accident; therefore, an alternate source of power is not essential. Normally one startup transformer supplies 4160 volt Buses 1 and 3, and the other supplies Buses 2 and 4 /t howe r, en two sc rtup t ansformgrs-Mtre o ignea with a quate capaci such hat, s ould o e becom( or be de ino erable tempo ary co actio can made o suppl to 1 sta on loa (les the c ing t ers) f /om the other sy/ t.ie j artup dt nsfo r .- r-A battery charger is supplied for each battery. In addition, the two 125 volt station batteries have a spare charger available.

Since one spare 125 volt station charger is available, one station battery charger can be allowed out of service for maintenance and repairs.

Power for the Reactor Protection System is supplied by 120 V ac motor generators with an alternate supply from MCC-8B. TVG redundant, Class lE, seismically qualitied power protection panels are connected in series with each ac power source. These panels provide overvoltage, undervoltage, and underfrequency protection for the system. Setpoints are chosen to be consistent with the input power requirements of the equipment connected to the bus.

Amendment No. G4, 56, +44, +44, 125 220

\

Insert A The delayed access source is made available by opening the generator no load disconnect switch and establishing a feed from the 30 kV switchyard through the main generator step up transformer and unit auxiliary transformer to the 4.16 kV buses. The delayed access source is available within an hour of loss of the main generator capability to assure that fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded.

Electric power can be supplied from the off-site transmission network to the on-site Emergency AC Electric Power Distribution System by two independent sources, one immediate access and one delayed access, designed and located so as to minimize to the extent practicable, the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. An additional off-site source, a 4160 V tie line to Vernon IIydroelectric Statioa can nipply either 4160 V emergency bus.

It is used to meet Station Blackout and Appendix R licensing requirements.

Off-site power is supplied to the 345 kV switchyard from the transmission network by three transmission lines. A 400 MVA autotransformer is connected between the 345 kV north bus and the 115 kV bus. The autotransformer is the normal source for the 115 kV bus and the station startup transformers. The autotransformer also feeds the 115 kV transmission line to Keene.

The immediate access scurce is supplied from the 345 kV transmission system through the 345 kV /115 kV autotransformer. It feeds the on-site Electric Power Distribution System through the two 115 kV to 4,16 kV startup transformers and is available within seconds following a design basis accident to assure that core cooling, containment integrity and other vital functions are maintained. An alternate immediate access source through the Keene line may be made available. Its availability is dependent on its preloading, which must be limited by system dispatchers prior to it being declared an immediate access source.

A qualified source consists of all breakers, transformers, switches, interrupting devices, cabling and controls required to transmit adequate power from the off-site transmission network to the on-site Emergency Safeguards buses 3 and 4.

i

4 l-jyJ VYMPS  !

}tA4 8

BASES . 3.10 (Cont'd) .A twi.,k access succ es B. Adequate power is available operate the emergency safeguards

• equipment f rom C i - - - m -. -- -- _-___ 4 or for minimum engineered

,7 h $,4 safety features from either of the emergency diesel generators.

I T erefore, reactor operation is permitted for up to seven days with 4a.

D'{s4 24W g3

• ) & delayed-accessoff-sitepowersource/ Q*3e Jemv.3 aW .

d.I b 1, Each of the diesel generator units is capsole of supplying 100

,,y1{"+lf

• percent of the minimum emergency loads :equired under postulated design basis accident conditions. Each unit is physically and gsv g

• 0 *" *!. electrically independent of the other and of any off-site power i

%[ e , i source.4 Therefore, one diesel generator can be allowed out of 7 service for a period of seven days without jeopardizing the safety

^ +.*h dW* 0$N of the station.

.Ae techh acetas s.w e.s ta wavmAW In the event that & '-_P, adequate power is available to operate the emergency safeguards equipment from j4g either of the emergency diesel generators or from cat.:r ;U the 3 delayed-access of f-site power sourcesf.4 @ ~.I'n the event that both 4 e- emergency diesel generators are lost, adequate power is available d.3'41af1:

r-0-

pm ___21: a rto, operate

_ _ . . - .-the

_ _ emergency

--C or safeguards f rom e nhee-edequipment thefrom @ e- D .d%g g {4 'I d

delayed-access of f-site power sourcepr within Nourg. The plant 5"'**-

j b

f a' is designed to accept one hundred percent load rejection without wone,,

I adverse effects to the plant or the transmission system. Network stability analysis studies indicate that the loss of the Vermont

f. / .,gf $6 Yankee unit will not cause instability and consequent tripping of

.- l the connecting 345 kV and 115 kV lines. C.: V:r .:n ::e :: 10 4 f) .g,e (Inder r ": ::ree3 Thus, the availability of the Q:11/92::22:3 off-site power sources is assured in the event of a turbine trip.

{Ther tore, yea m r peratio as pe .hActed one diesel with th enerato start out of tra formers out o servic and w' se ice pttvided kr_e torati6n plan e NRC s noti led i ediatel of the event /nd Icetr E # Either of the two station batteries has enough capacity to energize the vital buses and supply d-c power to the other emergency equipment for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> without being recharged. In addition, two 24 volt ECCS Instrumentation batteries supply power to instruments that provide automatic initiation of the ECCS and some reactor pressure and level indication in the Control Room.

Due to the high reliability of battery systems, one of the two batteries may be out of service for up to three days. This minimizes the probability of ur.sarranted shutdown by providing adequate time for reasonable repairs. A station battery, ECCS Instrumentattor. battery, or an Uninterruptible Power System battery

-- - --is considered inoperable -if more-than one cell sis .out of service. A cell will be considered out of service if its float voltage is below

- 2.13 volts and the specific gravity is below 1.190 at 77'F.

The Battery Room is ventilated to prevent accumulation of hydrogen gas. With a complet. loss of the ventilation system, the accumulation of hydrogen would not exceed 4 percent concentration in 16 days. Therefore, on loss of Battery Room ventilation, the use of portable ventilation equipment and daily sampling provide assurance that potentially hazardous quantities of hydrogen gas will not accumulate.

C. The minimum diesel fuel supply of 25,000 gallons will supply one diesel generator for a minimum of seven days of operation satisfying the load requirements for the operation of the safoguards equipment.

, Additional fuel can be obtained and delivered to the site from nearby sourcos within the seven-day period.

Amendment No. G6, 58, 61 221

Insert E In the event that _one off-site power. source and one emergency diesel generator are unavailable, adequate power is available to operate both emergency buses from the -

operable; off-site power source and to operate 100% of the minimum- emergency safeguards loads from the operable diesel generator. In addition, the Station Blackout

- Alternate AC Source of power is capable of supplying power to the bus with the inoperable diesel generator, Therefore, continued operation is permitted for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with one off site power source and one emergency diesel generator unavailable,

=_

i

h. _ _ -__ _ _ _ _ . =

VYNPS BASES:-

4.10 AUXILIARY ELECTRICAL POWER SYSTEMS-A. The monthly tests of the diesel generators are conducted to check for equipment failures and deterioration. The test of the undervoltage automatic starting circuits will prove that each diesel will receive a start signal if a loss of voltage should occur on its emergency bus. The loading of each diesel generator is conducted to demonstrate proper operation at less than the continuous rating and at equilibrium operating conditions. Generator experience at other generator stations indicates that the testing frequency is adequace to assure a high reliability of operation should the system be required.

Both diesel generators have air compressors and air receivers tanks for starting. It is expected that the air compressors will run only infrequently. During the monthly check of the units, each receiver will be drawn down balow the point at which the compressor automatically starts to check operation and the ability of the compressors to recharge the receivers.

Following the tests of the units and at least weekly, the fuel volume remaining will be checked. At the end of the monthly load test of the diesel generators, the fuel oil transfer pump will be operated to refill the day tank. The day tank level indicator and alarm switches will be checked at this time. Fuel oil transfer pump operability testing is in accordance with Specification 4.6.E.

The test of the diesels and Uninterruptible Power Systems during each refueling interval will be more comprehensive in that it will functionally test the system; i.e., it will check starting and closure-of breakers and sequencing of loads. The units will be started by simulation of a loss of coolant accident. In addition, a loss of normal power condition will be imposed to simulate a loss of off-site power. The timing sequence will be checked to assure proper loading in the time required. Periodic tests between refueling intervals check the capability of the diesels to start in the required time and to deliver the expected emergency load requirements. Periodic testing of the various components plus a T.wsER.T b functional test at a refueling interval are sufficient to maintain adequate reliability.

B. Although the Main Station, ECCS, AS-2, and UPS batteries will deteriorate with time, utility experience indicates there is almos-no possibility of precipitous failure. The type of surveillance described in this specification is that which has been demonstrated over the years to provide an indication of a cell becoming irregular or unserviceable long before it becomes a failure.

The performance discharge test provides adequate indication and assurance that the batteries have the specified ampere hour capacity. The rate of discharge during this test shall be in accordance with the manuf acturer's discharge characteristic curves for the associated batteries. The results of these tests will be logged and compared with the manufacturer's recommendations of acceptability.

The service discharge test provides a test of the batteries ability to satisfy the design requirements (battery duty cycle) of the associated de system. This test will be performed using simulated or actual loads at the rates and for the durations specified in the 245EdLT D design load profile.

Amendment No. 46, 446, 128 222

'.'A..

! .# r htowt B The purpose of establishing the delayed access source once per operating cycle is to demonstrate that the delayed access source can be established within the required time of one hour and to demonstrate proper operation of the generator no load disconnect switch. The test demonstratea that power can be transferred to the delayed access source in a timely fashion. The test is not intended to simulate an actual loss of immediate access source, failure of both diesel generators and consequent loss of power to the <

- station buses.

1 Insert D Verification of operability within one hour and once per eight hours thereafter, may be performed as an administrative check by examining logs and other information to determine that required equipment is available and not out of service for maintenance or other reasons. It does not require performing the surveillance needed to demonstrate the

-_ operability of the equipment.

1 1

. _ .y -, - _ . . _ ,,. --.

4 4

0 4

.. a 8

S

- - "- - - -----_-m_.u___,_ _

[~ ,

4 VYNPS 3.10 LIMITING CONDITIONS FOR 4.10 SURVEILLANCE REQUIREMENTS OPEFATION

3. Emeraency Buses 3. Emeroency Buses The emergency 4160 volt The emergency 4160 volt Buses 3 and 4, and buses and 480 volt 480 volt Buses 8 and 9 buses shall be checked shall be energized and daily, operable.

4. Off-Site Power 4. Off-Site Power Two qualified off-site a. The status of the powe. sources l off-site power consisting of the sources shall be immediate access source checked daily, and the delayed access source shall be b. Once per operating energized and operable. cycle, the delayed access source shall be established within one hour.

5. Peactor Protection 5. Reactor Protection System Power Protection System Power Protection Two RPS power Once per operating protection panels for cycle, the operability each inservice RPS MG of each overvoltage, set or alternate power undervoltage, and source shall be underfrequency operable. protective device shall be demonstrated by the performance of an instrument channel calibration test.

Settings chall be verified to be in accordance with Table 4.10.1.

Amendment No. M, 44-2 , 4-26 , 214

VYNPS

-3.10 LIMITING CON 61TIONS FOR 4.10 SURVEILLANCE REQUIREMENTS OPERATION

f. From and after the-date that one of the two 125 volt Switchyard battery systems is found-or made-to be-inoperable for any

-reason, continued reactor operation is permissible-provided that the other 125 volt Switchyard battery system is operable.

3. Off-Site Power 3. Off-Site Power

a. From and after the a. When one off-site date one off-site power source is power source is unavailable, the made or found to remaining power be inoperable for source, both any reason, emergency diesel zesctor operation generators, may continue for associated seven days emergency buses provided the and all Low remaining off-site Pressure Cora and source, both Containment emergency diesel Cooling Systems generators, sh411 have been or associated shall be verified emergency buses operable within and all Low one hour and once Pressure Core and per eight hours Containment thereafter.

Cooling Systems

-are operable.

If this requirement cannot be met, an orderly shutdown shall be initiated and the reactor shall be in cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> unless the conditions of Specifications 3;10.B.3.b are applicable.

Amendment No. e6, ++G, 4G6, 217

VYNPS 3.L0 LIMITING CONDITIONS FOR 4.10 SURVEILLANCE REQUIREMENTS OPERATION _

b. From and after the b. 'When either dats that either off-site power of.'-site power source and one source and one diesel or diesel generator associated buses are made or found are unavailable:

to be inoperable for any reason, 1. The other continued off-site operation is power source permitted for and all' Low 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as long Pressure as the remaining Core and off-site power Containment source, the Cooling remaining diesel Systems generator, shall have associated been or emergency buses shall be and all Low verified Pressure Core and operable Containment within one Cooling Systems hour and are operable, once per eight hours If this require- thereafter, ment cannot be met, an orderly 2. The shutdown shall be remaining initiated and the . diesel reactor shall be generator in cold shutdown shall have v3 thin 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, been or shall be demonstrated to be operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Amendment No. 217a W. _ _ _ - _ - - _ _ - _ _

VYNPS BASES:

3.10 AUXILTARY ELECTRIC POWER SYSTEMS A. .The objective of this Specification is to assure that adequate power

-will be available to operate the emergency safeguards equipment.

_ Adequate power can be provided by any one of the following sources an immediate access source through both startup transformers, backfeed through the main transformer, or either of the two diesel generators. The backfeed through the nain transformer is a delayed access off-site power source. The delayed access source is made available by opening the generator no load disconnect switch and establishing a feed from the 345 kV switchyard through the main generator step up transformer and unit auxiliary transformer to the 4.16 kV buses. The delayed access source is available within an hour of loss of main generator capability to ausure that fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded.

Electric power can be supplied from the off-site transmission network to the on-site Emergency Safeguards Electric Power Distribution System by two independent sources, one immediate access and one delayed access, designed and located so as to minimize to the extent practicable the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. An additional off-site source, a 4160 V tie line to Vernon Hydroelectric Station, can supply either 416G V emergency bus. It is used to meet station blackout and Appendix R licensing requirements.

Off-site power is supplied to the 345 kV switchyard from the transmission network by three transmission lines, A 400 MVA autotransformor is connected between the 345 kV north bus and the 115 kV bus. The autotransformer is the normal source for the 115 kV bus and the statJon startup transformers. The autotransformer also feeds the 115 kV transmission line to Keene.

The immediate accesr source is supplied from the 345 kV Transmission System through the 345 kV/115 kV autotransformer. It feeds the on-site Electric Power Distribution System through the two 115 kV to 4.16 kV startup trt.nsformers and is available within seconds following a design basis accident-to assure that core cooling, containment integrity and other vital functions are maintained. An alternate immediate access source through the Keene line may be made available. Its availability is dependent on its preloading which must be limited by system dispatchers prior to it being declared an immediate access source.

A qualified source ccnsists of all breakers, transformers, switches, interrupting devices, cabling and controls required to transmit adequate power from the off-site transmission network to the on-site Emergency Safeguards Buses 3 and 4.

Two 480 V Uninterruptible Power Systems supply power to the LPCIS valves via designated Motor. control Centers. The 480 V Uninterruptible power Systems are redundant and independent of any l on-site ac power sources.

This Specification assures that at least two cff-site and two on-site power sources, and both 480 V Uninterruptible Power Systems

-will be available before the reactor is taken beyond "just critical" testing. In addition to assuring power source availability, all of the associated switchgear must be operable as specified to assure that the emergency cooling equipment can be operated, if required, from the power sources.

Amendment No, a6, 144, 220

VYNPS  :"

BASES: 13.10 (Cont'd)

Station-service power is supplied to the station through either the unit auxiliary transformer or the startup transformers. In order to

l. start up the station, the startup transformers are required to-supply the station auxiliary load. . After the unit is synchronized to the system, the unit auxiliary transformer carries the station auxiliary load, except for the station cooling tower loads which are always supplied by one of the startup transformers. The station cooling tower loads are not required to perform an engineered safety feature function in the event of an accident; therefore, an alternate source of power is not essential. Normally one startup transfctmer supplies 4160 volt Buses 1 and 3, and the other supplies l Buses 2 and 4.-

A battery charger is supplied'for each battery. In addition, the two 125 volt station batteries have a spare charger available.

Since one spare 125 volt station charget is available, one station battery charger can be allowed out of service for maintenance and repairs.

Power for the Reactor Protection System is supplied by 120 V ac motor generators with an alternate supply from MCC-8B. Two redundant, Class 1E, seismically qualified power protection panels are connected in series with each ac power source. These panels provide overvoltage, undervoltage, and underfrequency protection for the system. Setpoints are_ chosen to be consistent with the input power requirements of the equipment connected to the bus.

B. Adequate power is available to operate the emergency safeguards l equipment from-the immediate access source or for minimum engineered safety features from either of the emergency diesel generators.

Therefore, reactor operation is permitted for up to seven days with l the delayed-access off-site power source unavailable.

Each of the diesel generator units is capable of supplying 1001 percent of the minimum emergency loads required under postulated design basis accident conditions. Each unit is physically and electrically independent of the other and of any off-site power source. Adequate power is also-available to operate the emergency safeguards-equipment from the immediate access source or from the delayed access source of off-site power. Therefore, one diesel generator can be allowed out of service for a-period of seven days without jeopardizing the safety of the station.

l In the event that the immediate access source is unavailable, adequate power is available to operate the emergency safeguards equipment from the emergency diesel generators or from the

-delayed-access off-site power source. Therefore, reactor operation is permitted for up to 7 days with the immediate access source unavailable.

In the event that both emergency diesel generators are lost, adequate power is available to operate the emergency safeguards equipment from the immediate access source or from the delayed-nccess off-site power source within one hour.

The-plant is designed to accept one hundred percent load rejection without adverse effects to the plant or the transmission system.

Network stability analysis studies indicate that the loss of the Vermont Yankee unit will not:cause instability and consequent tripping of the connecting 345 kV and 115 kV lines. Thus, the availability of the off-site power sources is assured in the event of a turbine trip.

Amendment No. 54, ++2, 146, 221

VYNPS BASq1: '3.10 (Cont'd)-

In the event that one off-site power source and one emergency-diesel generator _are_ unavailable, adequate power is available to operate both emergency safeguards buses from the operable off-site power source and to operate 100% of the minimum emergency safeguards loads from the operable diesel generator. In addition, the station blackout alternate ac_ source of power is capable of supplying power to the bus with the inoperable diesel generator. Therefore, continued operation is permitted for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with one off-site power source and one emergency diesel generator unavailable.

Either of the two station batteries has enough capacity to energize <

the vital buses and supply d-c power to the other emergency equipment for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> without being recharged. In addition, two 24 volt ECCS Instrumentation batteries supply power to instruments ,

that provide automatic initiation of the ECCS and some reactor pressure and level indication in the Control Room.

Due to the high reliability of battery systems, one_of the two batteries may be out of service for up to th.ee days. This minimizes the probability of unwarranted shutdown by providing adequate time for reasonable repairs. A' station battery, ECCS Instrumentation battery, or an Uninterruptible Power System battery is considered ineperable if more than one cell is out of service. A cell will be considered out of service if its float voltage is below 2.13 volts and the specific-gravity is below 1.190 at 770F.

The Battery Room is ventilated to prevent accumulation of hydrogen gas. With a complete loss of the ventilation system, the accumulation of hydrogen would not exceed 4 percent concentration in 16 days. Therefore, on loss of Battery Room ventilation, the use of portable ventilation equipment and daily sampling provide assurance that potentially hazardous quantities of hydrogen gas will not accumulate.

C. The minimum diesel fuel supply of 25,000 gallons will supply one diesel generator _for a minimum of seven days of operation satisfying the load requirements for the operation of the safeguards equipment.

Additional fuel can be obtained and delivered to the site from nearby sources within the seven-day period.

Amendment No. 54, 64, 221a 1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

4-VYNPS BASEST-4.10 -AUXILIARY ELECTRICAL POWER SYSTEMS A. The monthly tests of the diesel generators are conducted to check for equipment failurea and deterioration. The test of the undervoltage automatic starting circuits will prove that each diesel-will receive a start signal if a loss of voltage should occur on its emergency bus. The loading of each diesel generator is conducted to demonstrate proper operation at less than the continuous rating and at equilibrium operating conditions. Generator experience at other generator stations indicates that the testing frequency is adequate to assure a high reliability cf operation should the system be required.

Both diesel generators have air compressors and air receivers tanks for starting. It is expected that the air compressors will run only infrequently. During the monthly check of the units, each receiver will be drawn down below the point at which the compressor automatically starts to check operation and the ability of the compressors to recharge the receivers.

Following the tests of the units and at least weekly, the fuel volume remaining will be checked. At the end of the monthly load test of the diesel generators, the fuel oil transfer pump will be operated to refill the day tank. The day tank level indicator and

( alarm switches will be checked at this time. Fuel oil transfer pump operability testing is in accordance with Specification 4.6.E.

The test of the diesels and Uninterruptible Power Systems during each refueling interval will be more comprehensive in that it will functional 3y test the system; i.e., it will check starting and closure of breakers and sequencing of loads. The units will be started by simulation of a loss of coolant accident. In addition, a loss of normal power condition will be imposed to simulate a loss of off-site power. The timing sequence will be checked to assure proper loading in the time required. Periodic tests between refueling intervals check the capability.of the diesels to start in the required time and to deliver the expected emergency load requirements. Periodic testing-of the various-components plus a functional test at a refueling interval are sufficient to maintain adequate reliability.

-The purpose of establishing the delayed access source once per operating cycle is to demonstrate that the delayed access source can

-be established within the required time of one hour and to demonstrate proper operation of the generator no-load disconnect switch. The test demonstrates that power can be transferred to the delayed access source in a timely fashion. The test is not intended to simulate an actual loss of the immediate access source, failure of both diesel generators and consequent loss of power to the station buses.

B. Although the Main Station, ECCS, AS-2, and UPS batterias will deteriorate with time, utility experience indicates there is almost no possibility of precipitous-failure. The type of surveillance described in this specification is that which has been demonstrated over the years to provide an indication of a cell becoming irregular or unserviceable long before it becomes a failure.

The performance discharge test provides adequate indication and assurance that-the batteries have the specified ampere hour capacity. The rate of discharge during this test shall be in accordance with the manufacturer's discharge characteristic curves Amendment No. G6, 125, 146, 222

VYNPS BASES: '4.10 (Cont'd) for the associated batteries. The results of these tests will be-logged and compared with the manufacturer's recommendations of acceptability.

The service discharge test provides a test of the batteries ability to satisfy the design requirements (battery duty cycle) of the associated de system. This test will be performed using simulated or actual loads at the rates and for the durations specified in the design load profile.

-Verification of operability of an off-site power source and Low Pressure Core and Containment Cooling Systems within one hour and once per eight hours thereaf ter as required by 4.10.D.3.b.1 may be performed as an administrative check by examining logs and other information to determine that required equipment is available and not out of service for maintenance or other reasons. It does not require performing the surveillance needed to demonstrate the operability of the equipment.

• C. Logging the diesel fuel supply weekly and after each operation assures that the minimum fuel supply requirements will be maintained. During the monthly test for quality of the diesel fuel oil, a viscosity test and water and sediment test will be performed as described in ASTM D975-68. The quality of the diesel fuel oil will be acceptable if the results of the tests are within the limiting requirements for diesel fuel oils shown on Table 1 of ASTM D975-68.

Amendment No. 146, 223

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