REACTIVITY
DOE-HDBK-1019/2-93 Reactor Theory (Nuclear Parameters)
Example:
Convert the values of reactivity listed below to the indicated units.
a.
0.000421 Dk/k =
pcm
b.
0.0085 Dk/k =
% Dk/k
c.
16 x 10-4 Dk/k =
Dk/k
Solution:
a.
42.1 pcm
b.
0.85% Dk/k
c.
0.0016 Dk/k
If the reactivity is known, the effective multiplication factor can be determined by solving
Equation (3-5) for keff in terms of the reactivity. This results in the following relationship.
(3-6)
keff
1
1 r
Reactivity must be in units of Dk/k for use in Equation (3-6).
Example:
Given a reactivity of -20.0 x 10-4 Dk/k, calculate keff.
Solution:
keff
1
1 r
1
1 ( 20.0 x 10
4)
0.
998
NP-03
Rev. 0
Page 20
