ML20114B640

Proposed TS 15.3.7 Re Auxiliary Electrical Sys,Spec A.1.c Covering 480-volt Supply Buses A03 & A04

ML20114B640
Person / Time
Site:	Point Beach
Issue date:	08/25/1992
From:	WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20114B639	List: ML20114B636 ML20114B640
References
NUDOCS 9208310023
Download: ML20114B640 (6)

Text

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15.3.7 l AUXILIARY ELECTRICAL SYSTEMS f ApolicabilitY Applies to the availability of off-site and on-site electrical power for plant power operation and for the operation of plant auxiliaries.

Ob.iective To define those conditions of electrical power availability necessary (1) to provide for safe reactor operation, and (2) to provide for the continuing availability of engineered safeguards.

!?ecification

' i A.1 Under normal conditions neither one nor both reactors shall be made critical unless the following conditions are met:

a.

At least two 345 KV transmissien lines are in service, b.

The 345/. 8 KV and the 13.8/4.16 KV station auxiliary transfurmers cssociated with the reactor (s) to 6 taken critical are in service; or one 345/13.8 KV station auxiliary transformer and the associated 13.8/4.16 KV station auxiliary transformer (s) are in service with the gas turbine operating.

c. ~

4160 Volt unit . supply buses A03, and -A0.4,-l forL the unit. to be ;taken critical are energized from.their normal supply.

d.

4160 Volt safegitards buses A9h--A04r A05, and A06 for the unit (s) to be taken critical are independently energized from 4theirJnormal supply and.both units' A05/A06 bus tie-bheakers .are re'movedifroin their cubicles.

4 ee.

480 Volt buses 803 and B04 for the unit (t) to be taken critica' are independently energized from their normai- supply 'and Loth units' B03/B04-bus tie-breakers are open with~ control power removed, m fe. A fuel supply of 11,000 gallons is available; and both diesel E generators are operable.

J gf.

All four batteries and their associated DC systems are ooerable.

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h. 9 Four battery chargers are operable with one charger carrying the DC loads on each DC main distriott ion bus.

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88 e?d y Unit 1 - Amendment No. 15.3.7-1 Unit 2 - Amendment No.

A.2 Under abnormal conditions including Black Plant startup, one reactor may be made critical oroviding the following conditions are net:

a. One 345 KV transmission line is in service; or the gas turbine is operating.

b. The 345/13.8 KV and the 13.8/4.16 KV station auxiliary transformers associated with the unit to be taken critical are in Service; or the associated 13.8/4.16 K/ station auxiliary transfer .c is in service and the gas turbine is operating.

c. Reactor power level is limited to 50% r=ted power until 2 or more transmission lines are restored to service.

4150 Volt- buses A03- and A04; for the unit- to be taken critical- are

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d.

endgized from their normale supply.

e. 4160 Volt safegu'a rds buses A0h-A04v A05, and A06 for the unit to be taken critical are independently energized from their.~ normal-or emergency l power supply. and both ' Units' A05/A06 ' bus- tie 4reakers ~ars removed from __their cubicles.

fd. 480 Volt safeguards buses 803 and B04 for the unit to be taken critical are independently energized from.their normal lor emergency

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power! supply 'and both~ units B03/B04^ bus.t'e-breakers'are open with controlipower removed.

gf.  % fuel supply of 11000 gallons is available; and both diesel generators are operable, hg All four batteries and their associated DC systems are operable.

ih. Four battery chargers are ouerable with one charger carrying the DC loads of each DC main distribution bus.

B.1 During power operation of one or both reactors, the requirements of 15.3.7. A.1 may be modified to allow the following arrangements of systems and components:

a. If the 345 KV lines are reduced to only one, any operating reactor (s) must be promptly reduced to, and limited to, 50% power. If all 345 KV lines are lost, any operating reactor (s) will be reduced to supplying its auxiliary lead, until one or more 345 KV transmission lines are again available.

b. If both 345/13.8 KV auxiliary transformers are out of service and only the gas turbine is operating, only one reactor will remain operating and it will be limited to 50% power. The second reactor will be placed in the hot shutdown condition.

Unit 1 - Amendment No. 15.3.7-2 Unit 2 - Amendment No.

c. If the 13.8/4.16 KV auxilicry transformers are reduced to only one, the reactor associated with the out of service transformer must be placed in the hot shutdown condition,

d. Either bus A03 or A04 may be out of service for a period not exceeding 7 days provided both diesel generators are operable and the associated diesel generator is operating and providing power to the engineered safeguard bus r.ormally supplied by the out of service bus.

e.- ;1Wl_t_hla unitiin;; cold?; ort ref6_elhgishutdosn6lonejaJrlof:;biises,f A051an.d A06'or 803'.and180_4Gforfthatishutdownfun.{th maifbeltisdit;ogetheij -

thr;ought:theirTcbmmori:tiefbreaksr? f6rLupftof hburs! ;Ifftheiti.bi LVe a ker c anno t be lope ned :'odthsic6nd i ti on sf o f ' 15. 3. 7. Bl.'l . f.L me tisi th i ri 8 hodrs; the!oper~atinc[6 nit [shillsbejla~cedTinith{hotEshutd_okriTcondi-

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ti on . wi thiriL6? ho'urs and Li nlcol djshu_t@wn1wi thi n ; thef: f01 fowirlg[30f h60ps u

f. Nith[a f snitifullyidefueled,1o'nefpalN,f ?bdies" for. thsidefusled _06it ,

.A05"andLA06 or;B03fand2 BORmay[be7tisd Ltogetheft.hrd.ucj(their commoh

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tie-bfeak'er 11nf; excess of;8 h;6urs@oVidsdi .

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1); LAn evaluat'i.onlisfperformedit;;61shoithat}:thejT6sdR;thatyemain7 or?can;be? energized :bfj:the} b0ses;@ill [niot3adssfa(pot'ent;ial.

over1badLof t.he associatsd" diesel cjerierator; iThe"applibable LimitinglCondit t_onsjfor. Operatio'njof:: theLequipmentirem'ovsdifrom service ~ shall .be' enteredifor thefoperating sunit.

2)l  : A i s i ngTsitf A i nf o f spent7fdel :" cool i hgl;i s ladequ a t e lto i ccoll t.h3 spent.: fue1 Moo _1.

ge. One diesel generator may be inoperable for a period not exceeding 7 days provided the other diesel generator is tested daily to ensure operability and the engineered safety features associated with this diesel generator shall be operable. This LC0fshall;notibelallowed in conjunction w d h e. Lor f. above, hf. One of the batteries DO5 or 006 may be inoperable for a period not exceeding 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provided the other three batteries and four battery chargers remain operable with one charger carrying the DC loads of each DC main distribution bus, ig. One of the batteries D105' or C106 may be inoperable for a period not exceeding 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> pro.ided the other three batteries and four battery chargers remain operable with one charger carrying the DC loads of each DC main distribution bus. .

Basis This two unit plant has four 345 KV transmission line interconnections. A 20 MW gas turbine generator and two 2850 KW diesel generators are installed at the Unit 1 - Amendment No. 15.3.7-3 Unit 2 - Amendment No.

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plant. All of these energy sources will be utilized to provide depth and reliability of service to the Engineered Safeguards equipment tnrough redundant station auxiliary power supply systems.

The electrical system equipment is arranged so that no single contingency can inactivate enough safeguards equipment to jeopardize the plant safety. The 480-volt equipment is arranged on 4 buses per unit. The 4160-volt equipment is supplied from 6 buses per unit.

Two separate outside sources can serve either unit's low voltage station auxiliary transformer. One is a direct feed from the unit's high voltage station auxiliary transformer and the second is from the other unit's high voltage station auxiliary transformer or the gas turbine via the :3,800 volt system tie bus H01.

Separation is maintained in the 4160-volt system to allow the plant auxiliary equipment to be arranged electrically so that redundant items receive their power from the two different buses. For example, the safety injection pumps are supplied from the 4160 volt buses 1-A05 and 1-A06 for Unit No. I and 2-A05 and 2-A06 for Unit No. 2; the six service water pumps are arranged on 480-volt buses as follows: two on bus 1-B03, one on bus 1-804, one on bus 2-803 and two on bus 2-B04; the four containment fans are divided between 480-volt buses 1-B03 and 1-B04 for Unit No. I and 2-303 and 2-804 for Unit No. 2 and so forth. Redundant valves are supplied from motor control centers 1-B32 and 1-842 for Unit No. I and 2-B32 and 2-842 for Unit No. 2.

The specifications for the' 480. volt safeguards buses, B03l ar.d B04, and';the 4160 volt safegu'ards b'uses, A05 and A06,Jdirect -'anLindependent lineup::of. power distri-bution, specifically stating that a . normal lineup mustfbe achie~ved (all safeguards buses associated with a ' unit are powered through theirLnormal supply breaker {with _

all safeguards 1 bus tie-breakers open)' prior to' takingla unit critical;and duping i

subsequent power! operation. 0perability of the sa'feg6ards busesfisl based'on maintaining (at least:one on-sit.e - AC powerLsource and associatedidistr.ibution system operable during accident condition's coincidbnt with 'an assumed loss of -off-site-power and a singl'e-failure in the other on-site.AC source. This includes.~a failure of a tie-breaker to trip, which under-certain'coriditions 'c'ould' result'in an overload and a loss ofLthe 'ssociated a diesel l generator. The LCOs' permit abnor-mal power distribution lineups for limited periods;ofitime in order toe facilitate such items as maintenance of- normal supply breakers or transformers. 'InJsuch

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cases, bus independence may be relaxed under the conditions specified in.theiLCO.'

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l Unit 1 - Amendment No. 15.3.7-4 Unit 2 - Amendment No.

t .

w Extended use of. safeguards bus tie-breakers-is al'iowed under specified,- controlled conditions. 'For example, when a unit is fully _ defueled, safeguards an'd safe shutdown systems and equipment. dedicated to that' unitare not required. However,'

spent fuel pool cooling must.be maintained. By limiting the loads! supplied'by-the cross-connected buses, the potential for loss of a diesel; generatorfdue to overbading- caused by'the failure of a- tie-breakerL to open is . minimized.

Operability of shared safeguards systenisis'uch 'as auxiliaryy feedwater and service

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water must be maintained as' required by their' applicable _ LCOs.

The Plant DC electrical sys+em has been modified so that each of the four instrument bus power supplies has its own battery and battery charger. One battery charger shall be in service on each battery so that the batteries will always be at full charge in anticipation of a loss-of-ac power incident. This insures that adequate dc power will be available for starting the emargency generators and other emergency uses.

The emergency gene ator sets are General Motors Corporation, Electro-Motive Division, Model 999-20 Units rated at 2850 KW continuous, 0.8 power factor 900 RPM, 4160 volts 3 phase, 60 cycle and consume 205 gallons of fuel per hour. Thus the 11,000 gallon supply in the Emergency Fuel Tank provides sufficient fuel to operate one diesel at design load for more than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. In addition, it will be normal for Point Beach to keep one, or the equivalent of one, bulk storage tank full c.t all times (55,000 gallons which is equal to about 10 days' supply). They are each capable of providing 3050 kw for a 30 minute period. The gas turbine is capable of providing 20,000 kw.

If only one 345 KV transmission line is in service to the plant switchyard, a temporary loss of this line would result in a reactor trip (s) if the reactor (s) power level were greater than 50%. Therefore, in order to maintain continuity of scrvice ard the possibility of self sustaining operations, if only one 345 KV transmission line is in service to any operating teactor(s), the power level of the affected reactor (s) will be limited to 50%.

If both 345/13.8 KV station auxiliary transformers are out cf service, only one reactor will be operated. The gas turbine will be supplying power to operate the safeguards auxiliaries of the operating reactor and acts as a backup supply for the unit's normal auxiliaries. Therefore, to prevent overloading the gas turbine in the event of a reactor trip, the maximum power level for the operating reactor Unit 1 - Amendment No. 15.3.7-5 l Unit 2 - Amendment No. l

,., r will be limited to 50%. These conservative limits are set to improve transmission system reliability only and are not dictated by safety system requirements.

References FSAR Section 8.

1 Unit 1 - Amendment No. If.3.7-6 Unit 2 - Amendment No.

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