Reactor Theory (Nuclear Parameters)
Reactivity is a measure of the departure of a reactor from criticality. The
reactivity is related to the value of keff . Reactivity is a useful concept to predict
how the neutron population of a reactor will change over time.
Given the number of neutrons in a reactor core and the
effective multiplication factor, CALCULATE the number of
neutrons present after any number of generations.
DEFINE the term reactivity.
CONVERT between reactivity and the associated value of keff.
CONVERT measures of reactivity between the following units:
Percent millirho (pcm)
EXPLAIN the relationship between reactivity coefficients and
Application of the Effective Multiplication Factor
When keff remains constant from generation to generation, it is possible to determine the number
of neutrons beginning any particular generation by knowing only the value of keff and the number
of neutrons starting the first generation. If No neutrons start the first generation, then No(keff)
neutrons start the second generation. Equation (3-4) can be used to calculate the number of
neutrons after the completion of "n" generations.