Main Feed Pumps and Main Turbine Trips

Question 1

FWPT trips result in the following AUTO closures and actions from the FWPT system:

• 5 different auto close/actions *

Answer 1

1. Closure of HP and LP stop valves
2. Closure of HP and LP control valves
3. Closure of pump mini-flow valve
4. Feed Pump tripped signal to RPCB (2/3 logic)
5. “FWPT A(B) Trip” annunciator

Question 2

Main FWPT Overspeed:

Answer 2

6350 RPM

Question 3

Main FWPT Low Suction Pressure trip:

Answer 3

245 PSIG after time delay:

• > 10 seconds for “B” pump
• > 15 seconds for “A” pump
• 2 out of 3 logic
• Time delay ensures 1 pump trips first to help prevent a complete loss of Main Feedwater on short transients

Question 4

Main FWPT High Discharge Pressure trip:

Answer 4

1780 PSIG

• 2 out of 3 logic
• Backup to overspeed trip
• Has occurred in past - FWCS valves in MANUAL and FWPT speed controllers in AUTO

Question 5

Main FWPT Low Vacuum in Main Condenser trip:

Answer 5

13. 5” HgA

* 2 out of 2 logic

Question 6

Low Control Oil Pressure to the Stop and Control Valve Operators trip:

Answer 6

75 PSIG

Question 7

Active Thrust Bearing Wear Oil High Pressure trip:

Answer 7

40 PSIG

Question 8

Inactive Thrust Bearing Wear oil High Pressure trip:

Answer 8

40 PSIG

Question 9

FWPT Bearing Low Oil Pressure trip:

Answer 9

4 PSIG

* 2 out of 3 logic

Question 10

FWPT Turbine Bearing Low Oil Pressure trip:

Answer 10

4 PSIG

* 2 out of 3 logic

Question 11

FWPT Manual Trip:

Answer 11

B06 or Local

Question 12

FWPT Speed potentiometer must be ___ to reset system

Answer 12

Fully counter-clockwise

Question 13

FWPT Normal reset requires ___

Answer 13

• LP and HP Control Valves to be closed

* “Reset” pushbutton depressed

Question 14

FWPT Reset actuation results in the following:

• 3 things *

Answer 14

1. HP and LP Stop Valves opening
2. “FWPT Trip” annunciator clears
3. Mini-Flow Recirculation Valves Open

Question 15

Main Turbine Overspeed Trip set point:

Answer 15

110%

Question 16

Main Turbine Backup Overspeed Trip:

Answer 16

110.5%

Question 17

MT Main Condenser Low Vacuum Trip:

Answer 17

7.5” HgA

Question 18

MT Excessive Thrust Bearing Wear Trip:

Answer 18

40 MILS

Question 19

MT Excessive Vibration Trip:

Answer 19

12 MILS

Question 20

MT High Exhaust Hood Temperature Trip:

Answer 20

225 F

Question 21

MT MSR Hi-Hi Level Trip:

Answer 21

3” Below MSR Bottom

Question 22

MT Loss of Stator CW Trip:

Answer 22

549 GPM

Question 23

MT Low EHC Fluid Pressure Trip:

Answer 23

1100 PSIG

Question 24

MT Loss of 125 VDC Control Power Trip:

Answer 24

Loss of Both Speed Signals

Question 25

MT Low Bearing Oil Pressure Trip:

Answer 25

12 PSIG

Question 26

MT Low Discharge Pressure on Shaft Driven LO Pump Trip:

Answer 26

100 PSIG

Question 27

MT Power Load Unbalance Trip:

Answer 27

Mismatch between generator amps and cross-under pressure

Question 28

The MT Main Shaft Oil Pump is rated for 1500 GPM at 235 PSIG and supplies LO for the system when the MT shaft speed exceeds ___

Answer 28

90% of rated speed