Reactor Theory (Reactor Operations)
DOE-HDBK-1019/2-93
SUBCRITICAL MULTIPLICATION
Summary
The important information in this chapter is summarized below.
Subcritical Multiplication Summary
Subcritical multiplication is the effect of fissions in the fuel increasing the
effective source strength of a reactor with a keff less than one.
Subcritical multiplication factor is the factor that relates the source level to the
steady-state neutron level of the core.
The steady-state neutron level of a subcritical reactor can be calculated based on
the source strength and keff using Equation (4-3).
N S
1
1 keff
The count rate expected in a subcritical reactor following a change in reactivity
can be calculated based on the initial count rate, initial keff, and amount of
reactivity addition using Equation (4-4).
CR1
CR2
1 k2
1 k1
1/M plots can be used to predict the point of criticality.
Rev. 0
NP-04
Page 9
