ML20207E159

Proposed Tech Specs Re Auxiliary Electric Sys Involving Proposed Change of Dc Batteries

ML20207E159
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/05/1988
From:	PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20207E154	List: ML20207E149 ML20207E156 ML20207E159
References
TAC-67933, NUDOCS 8808170084
Download: ML20207E159 (3)

Text

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Fort St. Vrain #1 Technical Specifications Amendment No.

Page 4.6-3 operability of the other diesel-generator set is demonstrated immediately as in a) above and all essential buses are operable, e) The two station batteries and their associated D.C. buses and battery chargers are operable. One battery charger or battery may be l

inoperable for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, unless disconnected to perform an l equalizing charge, provided conditions 1 through 4 below are satisfied.

1) The other station battery and its associated battery charger and both D.C. buses are operable.

l 2) D.C. bus independence is maintained and the disconnect switch l for the PPS battery is open.

3) Both diesel-generators and their associated essential 480v buses are operable.

4) The PPS battery and battery charger / inverter are operable.

A battery and battery charger disconnected from a D.C. bus to perform an equalizing charge is considered inoperable, but may be l disconnected for up to 5 consecutive days provided conditions 1) l through 4) above are met.

One D.C. bus may be inoperable for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> provided the following conditions are satisfied:

1) The station battery and the associated battery charger of the operable D.C. bus are operable.

2) Instrument power inverter supplied from the operable D.C. bus is operable.

3) Both diesel-generators and their associated 480v essential buses are operable.

8800170084 880805 PDR ADOCK 05000267 P PDC x

Fort St. Vrain #1 Technical Specifications Amondment No.

Page 4.6-5 In the normal operating mode, the unit auxiliary transformer is in operation, reserve auxiliary transfonner is energized and the standby-generator sets are operable. (FSAR Section 8.2.3.?.)

The main turbine-generator can be used as a source of auxiliary power in the event that outside electrical power is lost.

In the event of loss of all outside power and a turbine-generator trip, the diesel-generator sets would come on automatically to provide the required energy nscessary to safely shut down the plant.

In the event of the loss of the Reserve Auxiliary Transformer when the main turbine-generator is out of service, links in the bus between the main turbine-generator and the main power transformer can be removed, allowing the main power transformer and unit auxiliary transformer to be returned to service.

The essential 480v power source is supplied from three separate buses, any two of which can supply adequate power te shut the plant down. Under accident conditions, if the normal supply of power to da:* three essential buses should fail, the diesel-generator sets would come on and energize them. Bus load shedding, breaker closing, and load sequencing on to the diesel-generator sets is handled automatically.

The station batteries supply power for the instrument power inverters, protective devices and equipment operational control. During normal operation, D.C. power is supplied by A.C. to D.C. rectifiers, that is, battery chargers, which also keep the batteries fully charged. (FSAR Section 8.2.2.4.)

Fort St. Vrain #1 Technical Specifications Amendment No.

Page 4.6-6 The backup sources of electric power for the non-interruptible A.C.

l Instrument Power Buses are provided from Instrument Power Transformers fed from the 480 VAC essential buses through the Inverter / Static l Transfer Switches. Interruptible Instrument Bus No. 3 receives its power from redundant instrument transformers which are supplied from the essential 480 volt switchgear. (FSAR Section 8.2.2.3.)

A redundant source of electric power for the D.C. instrument loads is available from bus tie breakers between the two D.C. buses which allows l the backup battery charger to supply either one of the two buses while maintaining D.C. bus independence.

These backups and redundancier permit the temporary removal from service of an instrument power inverter, a battery, a D.C. bus or a l battery charger.

A diesel fuel storage capacity of 50,000 gallons is provided. A supply of 20,000 gallons of diesel fuel is adequate to provide for operation of the standby generators for at least seven days under required loading conditions. This allows adequate time to obtain additional fuel and to make provisions to restore the standby source of power into the station.