2 Subcriticality
43
Fig. 2.23 Time-sequence
data N(t) and Q(t) in a beam
restart experiment (Ref. [28])
(a) N(t)
(b) Q(t)
increase after beam restart. The decay of fission neutrons contains information on
the reactivity, while that of the source neutrons is free from such information. Generally, the decay constant of the source-neutron mode free from the neutron-production
process is larger than that of the prompt mode of the fission neutron [11]. In Fig. 2.25,
the decay data of counter B1 are compared with those of B4 in a beam trip experiment, where the control rod pattern is C and the data is normalized in such a way
that the average counts before the beam trip become one. This figure shows a larger
43
Fig. 2.23 Time-sequence
data N(t) and Q(t) in a beam
restart experiment (Ref. [28])
(a) N(t)
(b) Q(t)
increase after beam restart. The decay of fission neutrons contains information on
the reactivity, while that of the source neutrons is free from such information. Generally, the decay constant of the source-neutron mode free from the neutron-production
process is larger than that of the prompt mode of the fission neutron [11]. In Fig. 2.25,
the decay data of counter B1 are compared with those of B4 in a beam trip experiment, where the control rod pattern is C and the data is normalized in such a way
that the average counts before the beam trip become one. This figure shows a larger