6 Nuclear Transmutation of Minor Actinide
173
Fig. 6.19 Measured pulsed
heights of 237 Np, 241 Am, and
235 U fission reaction rates at
subcritical state (Ref. [5])
(a)
237
Np
(b)
241
Am
1.0
1.5
2.0
2.5
3.0
10
0
10
1
10
2
10
3
10
4
10
5
Pulsed height [V]
Counts [Arbitrary units]
235 U
237 Np
235 U
237 Np
1.0
1.5
2.0
2.5
3.0
10
0
10
1
10
2
10
3
10
4
10
5
Pulsed height [V]
Counts [Arbitrary units]
241 Am
235 U
235 U
241 Am
Table 6.7 Comparison of the
results of fission reaction rate
ratio at subcritical and critical
states (Ref. [5])
Reaction rate ratio Subcritical state Critical state (Ref. [1])
237 Np/ 235 U
0.048 ± 0.001
–
241 Am/ 235 U
0.035 ± 0.003
0.034 ± 0.001
(
237 Np/
197 Au) were measured by a BTB (back-to-back) fission chamber. To investigate the behavior of
237 Np and
241 Am fission and capture reaction rates in the
KUCA A-core, results were deeply analyzed by both the experimental signals from
the BTB fission chamber and the numerical results of MCNP6.1 calculations with
ENDF/B-VII.1. The calculated decomposition in energy of the fission and capture
reaction rates allowed us to isolate the most important energy regions in the responses.
From the results of experimental and numerical analyses, integral experiments on
the irradiation of MA in cores at critical conditions were successfully carried out