Page 162 - Dynamics and Control of Nuclear Reactors

12.10 Feedwater control for PWR with U-tube steam generators 159

Water Steam Feedwater
level flow flow

L W ST W FW

–
Set
point + + –

DL DW
Allowable Full power
level range steam flow

K 1 K 2

(1 + Ki/S)

Control signal to
feedwater valve

DL DW Ki
Control Signal = K 1 + K 2 • 1 +
L range W steam,100% S
FIG. 12.12
Three-element U-tube steam generator controller.

control in a PWR with a U-tube steam generator. The turbine controller adjusts the
steam valve to admit steam as needed to provide required turbine power. The reac-
tivity controller responds to changes caused by a change in steam flow rate. Resulting
processes in the system then determine the resulting steam pressure as specified in
the steady state program.