ML20248B258

Proposed Tech Specs,Establishing Limiting Conditions for Operation for Safeguards Buses in Electrical Distribution Sys

ML20248B258
Person / Time
Site:	Point Beach
Issue date:	09/22/1989
From:	WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20248B240	List: ML20248B234 ML20248B258
References
NUDOCS 8910030147
Download: ML20248B258 (6)

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

Objective 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.

Specification 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 transmission lines are in service.

b. The 345/13.8 KV and the 13.8/4.16 KV station auxiliary transformers ,

associated with the reactor (s) to be 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. 480 Volt safeguards buses 1-B03, 1-B04, 2-B03, and 2-804 are energized from their normal supply.

d. 4160 Volt safeguards buses 1-A05, 1-A06, 2-A05, and 2-A06 are energized from their normal supply.

e. 4160 Volt unit supply buses A03 and A04 for the unit to be taken critical are energized.

f. A fuel supply of 11,000 gallons is available; and both diesel i generators are operable.

g. All four batteries and their associated DC systems are operable. I

h. Four battery chargers are operable with one charger carrying the DC l loads on each DC main distribution bus.

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Unit 1 - Amendment No. 15.3.7-1 Unit 2 - Amendment No. 8910030147 890922 PDR ADDCK 05000266 P PNV s

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

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 KV station auxiliary transformer is in service and the gas turbine is operating.

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

d. 480 Volt safeguards buses 1-B03, 1-B04, 2-B03, and 2-804 are energized from their normal supply.

e. 4160 Volt safeguards buses 1-A05, 1-A06, 2-A05, and 2-A06 are energized from their normal supply.

f. 4160 Volt unit supply buses A03 and A04 for the unit to be taken critical are energized.

g. A fuel supply of 11,000 gallons is available; and both diesel l generators are operable.

h. All four batteries and their associated DC systems are operable. l

i. Four battery chargers are operable with one charger carrying the DC 1 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 load, until one or more 345 KV transmission lines are I

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.

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.n If.the 13.8/4.16 KV auxiliary transformers are reduced to only one, c.

the reactor associated with the out of service transformer must be placed in the hot shutdown condition.

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> 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 normally supplied by the out.of service bus.

e.  : Either buses 1-A05 and 1-A06 or buses 2-A05 and 2-A06 may be tied together through their common tie breaker for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. If these buses cannot be made operable within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, any operating unit (s) shall be placed in Hot Shutdown within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. .

. f. Either buses 1-803 and 1-B04 or buses 2-803 and 2-B04 may be tied together through their common tie breaker for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. If these buses cannot be made-operable within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, any operating unit (s) shall be placed in Hot Shutdown within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

g. One diesel generator may be inoperable for a period not exceeding 7 l 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 LCO shall not b'e applied in conjunction with e. or f. above,

h. One of the batteries DOS or 006 may be inoperable for a period not I 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.

i. One of the batteries D105 or 0106 may be inoperable for a period not I exceeding 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 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.

Unit 1 - Amendment No. 15.3.7-3

. Unit 2 - Amendment No.

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L 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 plant. All of these energy sources will be utilized to provide depth and L

reliability of service to the Engineered Safeguards equipment through 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 13,800 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-B03 and two on bus 2-B04; the four containment fans are divided between 480 volt buses 1-803 and 1-B04 for Unit No. I and 2-803 and '2-B04 for Unit No. 2 and so forth. Redundant valves are supplied from motor control centers 1-B32 and'l-B42 for Unit No. 1 and 2-B32 and 2-842 for Unit No. 2.  ;

l The specifications for the 480 volt safeguards buses, 803 and B04, and the 4160 volt safeguards buses, A05 and A06, direct an independent lineup of power distri-bution, specifically stating that a normal lineup must be achieved (all safeguards buses are powered through their normal supply breaker with all bus tie breakers 1

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

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open) prior to taking a unit critical and during subsequent power operation. I Operability of the safeguards buses is based on maintaining at least one on site AC power source and associated distribution system operable during accident conditions coincident with an assumed loss of off-site power and a single-failure in the other on-site AC source. The LCOs permit abnormal power distribution lineups for limited periods of time in order to facilitate such items as maintenance of normal. supply breakers or transformers. In such cases, bus independence'may be relaxed under the condition specified in the LC0 for a limited period of time.

The plant DC electrical system has been modified so that each of the four instru-ment bus power su,rplies 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 emergency generators and other emergency uses.

The emergency generator sets are General Motors Corporation, Electro-Motive Division, Model 999-20 Units rated at 2850 XW 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 Tenk 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 at 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 ree.ctor trip (s) if the reactor (s) power level were greater than 50L Therefore, in order to maintain continuity of l service and the possibility of self sustaining operations, if only one 345 KV transmission line is in service to any operating reactor (s), the power level of the affected reactor (s) will be limited to 50L Unit 1 - Amendment No. 15.3.7-5 Unit 2 - Amendment No.  !

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I' If both 345/13.8 KV station auxiliary transformers are out of 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 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.

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15.3.7-6

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