EX/HD

Question 1

State how FW heaters respond on a High-High level

Answer 1

Flow is stopped by closing EX MOV/NRV, RHDT LV and cascade inlet
For 21/22 heaters: that heater string isolates and CO-V-75 opens

Question 2

Discuss HDT Discharge Valve Position Control

Answer 2

In effect when conditions are very stable and power is above 90%. Maintains tank level constant. Only 1 discharge valve moves in very small increments.

Question 3

Discuss HDT Discharge Valve Flow Control

Answer 3

Normal mode for controller(s) when <90% power or transients. tries to maintain 55% HDT level

Question 4

Discuss HDT Discharge Valve Pressure control mode

Answer 4

Responds to a lowering HDT level. Shuts HDT discharge valve to 90% of calculated in-flow. 40% for A HDT pump and 30% for B HDT pump.

Question 5

State when 6” and 10” dump opens and auto actions for Hi-Hi level

Answer 5

68%: 6” dump modulates opens
72%: 10” dump modulates opens
75%: 10” dump trips opens
80%: RHDT, 26 cascade and 26 dump Closes, HDT vent also closes

Question 6

Discuss HDT Level Control in Turbine trip mode

Answer 6

With HD Pumps running: maintains B SGFP suction pressure at 385# for up to 90 Seconds
With HD Pumps tripped: 6” opens 10” modulates, resets on Turbine reset or override button at CP-551

Question 7

Discuss ARDVs actions on Turbine trip

Answer 7

ARDVs block/vent control Air to shut NRVs

Signals to close all EX MOVs

Question 8

State HD Pump auto trips

Answer 8

Turbine trip, >90 seconds time delay
Turbine trip, <28% HDT level
Turbine trip, >450/400 psig SGFP suction pressure
HDT low-low level <21% (A HDP), <17% (B HDP)
Electrical fault (Overcurrent, Bus undervoltage)

Question 9

Discuss HD pump recirculation flow

Answer 9

Recirc valve opens:
HD Pump running -AND-
Discharge valve <40% open -OR- Flow <1500 gpm

Recirc valve closes at 1% per minute:
Discharge valve >40% open -AND- Flow >2000 gpm