Rapid Load Reduction (AP-25)

Question 1

AP-25

What are the entry conditions for a “rapid load reduction”?

Answer 1

• FW heater tube failure
• T.S. required shutdown
• turbine runback or programmed ramp
• GCC called and said so (Path 15)
• any time plant conditions require > 5 MW/min ramp down

Question 2

AP-25

What ramp rate can DFWCS adequately control SGWL?

If during a rapid load reduction the procedure states turn Pzr heaters on, if the heater are already on, does any action need to be taken?

Answer 2

< 225 MW/min

Yes, take control switch to ON, so the heaters stay on

Question 3

AP-25

What are the Programmed Ramps on the turbine?

What are the ramp rates for the Programmed ramps?

Answer 3

MFP trip

• 225 MW/ min -> 650 MW
• 25 MW/ min -> 550 MW

CWP trip

• variable rate (Group II Stm Dmps dont open) ->550 MW

HDP

• 40 MW/ min -> 770 MW