6 Nuclear Transmutation of Minor Actinide
171
(a) Pb-Bi target at location of (15, H)
10
-4
10
-3
10
-2
10
-1
10
0
10
1
10
2
10
-10
10
-9
10
-8
10
-7
10
-6
Neutron energy [MeV]
Neutron flux per energy bin [1/cm
2
/eV/source]
Pb-Bi target
10
-8 10
-7 10
-6 10
-5 10
-4 10
-3 10
-2 10
-1 10
0 10
1 10
2
1.00
2.00
3.00
4.00
Neutron energy [MeV]
Neutron flux / lethargy [Arbtrary units]
ADS core
Critical core
ADS core
Critical core
(b) BTB chamber at location of (15, O; Fig. 6.15) in ADS and critical cores
Fig. 6.18 Calculated neutron spectra (PHITS) at locations of (15, H) and (15, O) in Fig. 6.15 (Ref.
[5])
6.2.1.4
237 Np and
241 Am Foils
To measure fission and capture reactions of
237 Np and
241 Am (both 99.99% purity,
89 μg and 15 μg weight, respectively), the BTB fission chamber was used in subcritical irradiation experiments and set at the location of (15, O; Fig. 6.15) of a special
void element. The main function of the BTB chamber is to obtain simultaneously two
signals from specially installed test (
237 Np or
241 Am) and reference (
235 U; 99.91%
enrichment, 10 μg weight) foils. For fission reaction rates, the two main signals from
the test and reference foils come from electric ones of fission fragments caused by