# Temperature Effect of Reactivity

## Abstract

In Chap. 2, it was assumed that effective multiplication coefficient *k* _{eff} and reactivity *ρ* do not depend on reactor power *n*, and the point reactor kinetics equations were solved. Their solutions are applicable to the reactor having almost zero power or zero number of neutrons. It is called the “zero-power reactor” and its reactor temperature does not change. In the actual reactor, however, when its number of neutrons numbers (or its power) changes, the temperature of the reactor changes and therefore, the *k* _{eff} and *ρ* values change. These changes affect reactor power. This reactivity change is called the temperature effect of reactivity. The reactivity changes with reactor temperature and moderator density, etc. The reactor power changes with the reactivity. Therefore, this reactor power change is called the reactivity feedback effect.