125vdc

Question 1

Where is the U2 125vdc battery?

Answer 1

TB 549 (above MCR)

Question 2

Where is the U3 125vdc Battery?

Answer 2

Upper level battery room above U3TB 538.

Question 3

Where is the U2 125vdc alt battery

Answer 3

SBO building

Question 4

What powers the 2(3) 125vdc battery Charger?

Answer 4

MCC 29-2(39-2)

Question 5

What Powers the 2(3)A 125vdc Charger?

Answer 5

MCC 28-2(38-2)

Question 6

What powers the U2 125vdc alt battery charger?

Answer 6

MCC 65-1

Question 7

What timeframe load is the 125vdc designed to handle?

Answer 7

Start and handle normal DC and all SSD DC loads on one unit AND
Operations to limit consequences of design basis event on other unit for 4 hours

Question 8

What is the purpose of 125vdc dist. system?

Answer 8

Provides reliable DC power to operate equipment such as solenoid valves, logic systems (PCIS & ECCS), and circuit breaker power for 4kV and 480V buses.

Question 9

What is the normal mode of operation for the 125vdc battery chargers?

Answer 9

Float

Question 10

What provides Div I 125vdc normally?

Answer 10

The Unit 125vdc battery charger

Question 11

What supplies the Div II 125vdc loads?

Answer 11

Opposite Unit 125vdc battery system.

Question 12

During normal operations, what normally provides the power source for 125vdc loads?

Answer 12

Unit 125vdc battery chargers.

Question 13

Why is the Unit 2 125vdc alt battery larger than the U3 battery?

Answer 13

Sized larger because of the larger losses from longer cable runs to go from SBO to Power block.

Question 14

What is the U3 125vdc alt battery charger power source (normally)?

Answer 14

MCC 35-2

Question 15

What is the purpose of the battery chargers?

Answer 15

The battery chargers provide the normal 125vdc power, and keep batteries fully charged in float pmode.

Question 16

What supplies the main 125vdc power to the Unit Div. I RB Loads?

Answer 16

RB Distribution Panel

Question 17

What supplies normal power to 125vdc Reserve Bus 2(3)?

Answer 17

Main Bus 3A (Main Bus 2A-1)

Question 18

What is a Level 2 Ground?

Answer 18

Requires Immediate immediate ground checking and IR
125vdc : <125kOhm (to ground) (>70v w/no buttons or >90 v w/either button)
250vdc : >183.6v with no buttons or > 215.5v w/either buttons

Question 19

What is a Level 3 Ground?

Answer 19

14days to find and notify distribution operator:
125vdc: <20kOhm (>115v w/no buttons or >120 v with either button)
250vdc: >229.4 v w/no buttons or >244.1v w/either button
(A+B = C : Positive button + negative button = no button)

Question 20

How are battery voltages displayed in MCR?

Answer 20

6 position switch on 902-8 panel

* THERE IS AN AMMETER ON BATTERY DISCHARGE THAT COULD CAUSE 902(3)-8 F-9 “250V-125V 24/48V BATT DISCHARGE HI” alarm*

Question 21

What loads are lost upon loss of U2 125vdc Reactor Building Distribution Panel Loss?

Answer 21

Control Power for 23-1 & 28
RB Vent Dampers Close
2/3 EDG control power transfer to U2 RB Bus
IsoCondenser Isolates

Question 22

What happens with loss of Main Bus 2A-1?

Answer 22

U2 RB Bus lost
Lose control power to 23 and 36
RFP and Cond. Pps auto start disabled.
All RFP trip relays disabled (continue to run)
HPCI logic alternate disabled
CS & LPCI Div I logic lost
ADS Div I logic lost
All ADS valve solenoids transfer to alternat feed lost
ISCO logic lost - causes ISCO isolation
MCR indication of inboard MSIVs lost
Loss of U3 Reserve Bus 3B-1 and all loads

Question 23

What happens if the feed to Bus 2A-1 loads lost?

Answer 23

Breaker Control for Bus 21 and 25 lost
various panels (Gen backup relay, EHC, Voltage Reulation exciter, annunciator panel 902-34, H2 and Stator Water Cooling Panel)

Question 24

What happens with loss of 2B-1 Bus?

Answer 24

Loss of Control to Bus 24, 24-1, and 29
U2 EDG control Power lost
ATWS 70B Inverter supply lost
Div II LPCI and CS logic
ADS Div II logic
HPCI logic normal feed
MCR indication for outboard MSIV