Reactor Theory (Reactor Operations)
Figure 3 Reactor Power Response to Negative Reactivity Addition
Conversely, in the case where negative reactivity is added to the core there will be a prompt
drop in reactor power. The prompt drop is the small immediate decrease in reactor power
caused by the negative reactivity addition. The prompt drop is illustrated in Figure 3. After the
prompt drop, the rate of change of power slows and approaches the rate determined by the
delayed term of Equation (4-7).
It can be readily seen from Equation (4-7) that if the amount of positive reactivity added equals
the value of
, the reactor period equation becomes the following.