RRFM 2009 Transactions - European Nuclear Society

switch from a fast to a thermal spectrum in the parameters above can at least be partially
counteracted.
Methodology
For this preliminary parametric study it was decided to use the depletion code DARWIN 2.2
[3] to handle both the JHR [2] case and the SFR [1] reference sample with the same program
and data files. As a reference sample serves Am 0.1 U 0.9 O 2 because it’s a likely candidate for
the actual experiment and has plenty of margin to change the fission rate by 235 U enrichment.
Additionally similar compositions have already been investigated as transmutation/fertile
blanket in the SFR core [3]. Starting from the reference sample U enrichment, neutron flux
level and Am content, but not isotopic composition, were modified in the JHR spectrum to
approach the behaviour of the same sample in the SFR. Table 1 shows reference case for
both reactor spectra.
SFR core
JHR reflector
max flux [n/s/cm²] 2.4667x10 15 5.1267x10 14
spectrum
ERANOS
33 gr.
TRIPOLI
172 gr.
reference sample Am 0.1 U 0.9 O 2
density [g/cm³] 10.3
U mass composition
Am mass composition
0.25% 235 U, 99.75% 238 U
95% 241 Am, 5% 243 Am
Tab 1: Reference cases for JHR and SFR
The necessary neutron spectra were provided by existing detailed TRIPOLI4.4 and ERANOS
models for the JHR, SFR and PHENIX and are shown below in figure 1.
Neutron Spectrum
1.E+15
1.E+14
1.E+13
1.E+12
JHR reflector
SFR in core
1.E+11
1.E+10
1.E+09
1.E- 09 1.E- 08 1.E- 07 1.E- 06 1.E- 05 1.E- 04 1.E- 03 1.E- 02 1.E- 01 1.E+00 1.E+01 1.E+02
Energy [MeV]
Fig 1: Neutron spectrum used in the calculations
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