Page 181 - Dynamics and Control of Nuclear Reactors

178 CHAPTER 13 Boiling water reactors

of Ref. [4] was modified to provide the amplitude in units of % power/cent of reac-
tivity as used throughout this book.
Fig. 13.6 shows the power-to-reactivity frequency response obtained with the
low-order model. Note the resonance at around 0.3rad/s. The resonance grows if
changes in conditions cause the system to move toward instability.
Recall that the closed loop transfer function for a system with feedback is
given by
G o
G c ¼ (13.2)
1+ G o H

(A)

(B)
FIG. 13.6
(A) BWR frequency response amplitude, (B) BWR frequency response phase.