6 Nuclear Transmutation of Minor Actinide
163
Fig. 6.6 Measured pulsed
heights of 237 Np and 235 U
fission reaction rates in
HEU-Pb zone (15, O;
Fig. 6.4a) at critical state
(Ref. [1])
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
10
0
10
1
10
2
10
3
10
4
10
5
Pulsed height [V]
Counts [Arbitrary units]
235 U (10 g)
237 Np
235 U
237 Np
Fig. 6.7 Measured pulsed
heights of 241 Am and 235 U
fission reaction rates in
HEU-Pb zone (15, O;
Fig. 6.4a) at critical state
(Ref. [1])
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
10
0
10
1
10
2
10
3
10
4
10
5
10
6
10
7
Pulsed height [V]
Counts [Arbitrary units]
241
Am
235
U
235 U (5 g)
241 Am
making lower-level discrimination about 1.0 V and integrating the count per channel
over 1.0 V. Also, the difference in pulsed heights between 5 and 10 μg of
235 U for
241 Am fission reaction rates was clearly observed by comparing the HEU-Pb and
HEU-PE zones shown in Figs. 6.7 and 6.8, respectively.
In addition to the fission reaction rates, capture reaction rates were obtained by
measuring the γ-ray of
237 Np foils in HEU-Pb and HEU-PE zones with the HPGe
detector after the irradiation experiments, as shown in Figs. 6.9 and 6.10, respectively.
For the
237 Np capture reaction rates, three peaks (Table 6.3) were found to be clearly
in the γ-ray measurements of two irradiation experiments in both HEU-Pb and HEUPE zones, and
237 Np capture reaction rates were experimentally deduced through the
saturated radioactivity.