162
C. H. Pyeon
Fig. 6.5 Calculated neutron
spectra (MCNP6.1 with
ENDF/B-VII.1) of HEU-PE
(15, K) and HEU-Pb (15, O)
fuel zones shown in
Figs. 6.2a, b, respectively
(Ref. [1])
10
-9 10
-8 10
-7 10
-6 10
-5 10
-4 10
-3 10
-2 10
-1 10
0 10
1 10
2
0
0.01
0.02
0.03
0.04
0.05
Neutron energy [MeV]
Neutron flux / lethargy [Arbtrary units]
HEU-PE
HEU-Pb
HEU-Pb
HEU-PE
Table 6.1 Positions [mm] of control and safety rods at critical state in HEU-Pb and HEU-PE cores
in Figs. 6.4a, b, respectively (Ref. [1])
Measured fission reaction rate
ratio
C1
C2
C3
S4
S5
S6
HEU-Pb zone
237 Np/ 235 U (10 μg)
723.27 1200.00 1200.00 1200.00 1200.00 1200.00
241 Am/ 235 U (5 μg)
720.35 1200.00 1200.00 1200.00 1200.00 1200.00
HEU-PE zone
237 Np/ 235 U (5 μg)
698.23 1200.00 1200.00 1200.00 1200.00 1200.00
241 Am/ 235 U (10 μg)
694.28 1200.00 1200.00 1200.00 1200.00 1200.00
1200.00 [mm]: Position of upper limit
Table 6.2 Number of atoms of 237 Np, 241 Am, and 235 U foils (Ref. [1])
Foil
Number of atoms
237 Np (HEU-Pb)
(2.27 ± 0.02) × 10 17
237 Np (HEU-PE)
(1.48 ± 0.02) × 10 17
241 Am (HEU-Pb)
(3.62 ± 0.01) × 10 15
241 Am (HEU-PE)
(3.94 ± 0.01) × 10 15
235 U (5 μg)
(1.31 ± 0.02) × 10 16
235 U (10 μg)
(2.67 ± 0.02) × 10 16
Table 6.3 Main characteristics of 237 Np and 197 Au capture reactions (Ref. [1])
Reaction
Half-life
γ-ray energy (keV)
Emission rate (%)
237 Np (n, γ) 238 Np
2.177 d
984.45
47.8
1025.87
9.6
1028.53
20.3
197 Au (n, γ) 198 Au
2.69517 d
411.80
95.5