2 Subcriticality
45
Table 2.3 Reactivity obtained by beam trip and restart experiments [%k/k] (Ref. [28])
Rod
Neutron
Beam trip experiment
Beam restart
Pattern
Counter
LSIKM
Integral
Experiment a
A
B1
−0.283 ± 0.010
−0.288 ± 0.020
−0.340 ± 0.034
B2
−0.244 ± 0.008
−0.232 ± 0.012
−0.242 ± 0.025
B3
−0.244 ± 0.009
−0.233 ± 0.016
−0.241 ± 0.028
B4
−0.241 ± 0.008
−0.232 ± 0.012
−0.239 ± 0.026
B
B1
−1.293 ± 0.018
−1.115 ± 0.054
−1.278 ± 0.083
B2
−0.641 ± 0.008
−0.617 ± 0.026
−0.632 ± 0.035
B3
−0.631 ± 0.009
−0.612 ± 0.034
−0.625 ± 0.042
B4
−0.617 ± 0.008
−0.599 ± 0.026
−0.593 ± 0.033
C
B1
−5.082 ± 0.094
−4.065 ± 0.256
−2.698 ± 0.423
B2
−1.599 ± 0.025
−1.513 ± 0.092
−1.460 ± 0.165
B3
−1.555 ± 0.033
−1.501 ± 0.120
−1.447 ± 0.201
B4
−1.504 ± 0.027
−1.431 ± 0.084
−1.355 ± 0.171
a LSIKM applied
Table 2.4 Reactivity
obtained by pulsed neutron
experiments [%k/k] (Ref.
[28])
Rod
Neutron
Pulsed neutron experiment
Pattern
Counter
Conventional
Mask technique
A
B1
−16.05 ± 0.68
−0.236 ± 0.039
B2
−0.299 ± 0.042
−0.223 ± 0.038
B3
−0.153 ± 0.036
−0.227 ± 0.039
B4
−0.043 ± 0.036
−0.245 ± 0.039
B
B1
−16.25 ± 0.69
−0.644 ± 0.055
B2
−0.872 ± 0.065
−0.642 ± 0.054
B3
−0.622 ± 0.053
−0.658 ± 0.055
B4
−0.359 ± 0.049
−0.668 ± 0.055
C
B1
−18.09 ± 0.73
−1.616 ± 0.092
B2
−2.342 ± 0.126
−1.554 ± 0.089
B3
−1.497 ± 0.087
−1.572 ± 0.090
B4
−0.952 ± 0.075
−1.565 ± 0.089
those obtained in a conventional pulsed neutron experiment and agrees with the result
of the pulsed neutron experiment based on the mask analysis within experimental
errors. Here, we note a further observation from this table, which is a larger error of
the beam restart experiment than that of the beam trip one. From the least-squares
fitting of Eq. (2.55) to beam trip data, only the reactivity is determined. From the
fitting of Eq. (2.53) to beam restart data, however, not only is the reactivity but also
the source strength is simultaneously determined. The additional unknown constant