SCALE Software Coordinator
This topic has been migrated from the SCALE 6 notebook.
I'm running CENTRM to obtain a neutron energy spectrum. For a simplified case I have a homogenous, infinite media of U-238 with an input fixed source distribution. It seems that the choice of DEMAX (upper PW calculation cutoff) can drastically change the results.
Attached are two images. The first has DEMAX set to 20 keV (end of U-238 resolved resonance region). The second has DEMAX set to 10 MeV. Not only are both spectra different, there is some odd behavior in both of them. The first one has some erratic multigroup fluxes right above the resonance range and the second seems to have some non-physical spikes at higher energies.
Both of these plots are from the pointwise flux punched output. I divided the flux by E to put it in the correct units for comparison with MCNP and the other code, but that's the only modification. I'm assuming the units of the flux punch edit are just n/cm^2-s correct?
Below is my SCALE input. IF anyone has any ideas or explanation of this behavior it would be appreciated.
=shell
del C:\scale6\tmpdir\ft88f001
copy C:\scale6\data\xn238v7 ft88f001
end
=ajax
0$$ 11 0
1$$ 1 T
' Input libary / Number of isotopes to copy
2$$ 88 1 T
' Isotope ZAID
3$$ 92238 T
end
=bonami
' Input library / Scratch / Scratch / Output library
0$$ 11 0 18 1
' Geometry flag / Number of zones / Mix table length / XS edit flag /
1$$ 0 1 1 0
' Bondarenko edit flag / Dancoff factor
0 0 T
' Mixture numbers by isotope
3$$ 1
' Nuclide IDs
4$$ 92238
' Nuclide concentrations (atom/b-cm)
5** 1.000
' Mixtures by zone
6$$ 1
' Tempuratures by zone
8** 9.00000E+02
' New Identifier in Mixing tables
10$$ 92238
' Zone types (0 - fuel, 1 - mod, 2 - clad)
11$$ 0 t
end
=worker
' Input master lib / Input working lib / Output lib
0$$ 1 0 4
' Scratch / Scratch / Output Temp-Interpolated lib
18 19 0
' Num nuclides to read from master lib / Num to read from working lib
1$$ 1 0
' Output print option / Flag to copy master / Flag to copy working
-2 -1 -1
' Sequence # of master / Sequence # of working / Sequence # of output
1 1 1 T
' IDs from master to copy
2$$ 92238
' Thermal scat. kernel temps
6** 9.00000E+02 T
end
=crawdad
' Output CENTRM lib / Scratch / Scratch / CE-KENO lib
0$$ 81 17 18 77
' Number of PW nuclides / CENTRM Identifier header / Print flag
1$$ 1 66666 1
' Lib format 0/1= old/new / Temp interp method / Thermal lib out flag
0 0 1
' Extra unused integer flags
e T
' Data Blocks 2 and 3 repeated for each nuclide
' ZAID for PW mat / ENDF version / ENDF mod / Number of temps for iso
2$$ 92238 7 -1 1
' MTs to be included / Mod number of therm data / Data source
0 -1 0
' Lower PW energy limit (eV) / Upper PW energy limit (eV)
3** 1.00000E-04 2.000E+07 T
' Nuclide temps to process
4** 9.00000E+02 T
end
=centrm
CENTRM: U-238 Inf medium at 900 K
' Punch logical / Thermal kernel / MG working lib / PW lib
0$$ 7 0 4 81
' MG flux restart / MG output / PW output / MG Angular output
0 25 15 16
' Scratch for thermal matricies / Optional PW xs print / Scratch
17 18 19
' Not used / Scratch
8 9
' Geometry / Num Zones / Num Intervals / Left BC / Right BC
1$$ 0 1 1 0 0
' Num Mixtures / Mix Table Length / Sn order / Max Pn Order
1 1 0 64
' Source type / Inner iter max / Upscatter outer iter max
0 20 100
' UMG range calc type / LMG range calc type / PW range calc type
2 2 3
' MG source and XS linearization / Pn order for PW calc
3 64
' PW Inelastic scat option
1
' Mix XS print opt / Flux print opt / Balance table print
2$$ 0 3 1
' Vol source flag / Boundary source flag / Group diffusion coeff
1 0 2
' Density factors / Extra print opt / Mass scattering restriction
0 1 0
' Restrictive order / corelate PW and MG flux / Not used
64 0 0
' Upscatter converg / Point converge / Source normalization
3** 1.00000E-04 1.00000E-05 1.00000E+00
' Material Buckling (1/cm) / LMG range cutoff / UMG range cutoff
0.00000E+00 1.00000E+00 1.00000E+07
' Thinning tolerance / Frac Lethargy gain allowance / Not used
1.00000E-03 1.00000E-01 0.0+00 T
' Mixture numbers
13$$ 1
' Isotope identifiers
14$$ 92238
' Isotope concentrations (atoms/barn -cm)
15** 1.0000 T
' Source number by interval
30$$ 1
' Volumentric soucre by interval and group
31**
9.61E+00
3.18E+01
6.59E+01
8.57E+01
2.44E+02
3.78E+03
1.29E+04
4.60E+04
1.39E+05
8.15E+04
3.80E+05
2.48E+05
7.00E+04
3.27E+05
2.70E+05
8.34E+04
3.75E+04
3.36E+04
5.86E+04
4.44E+04
9.02E+04
8.26E+04
8.36E+04
1.87E+04
2.34E+04
1.30E+04
3.85E+04
6.57E+04
6.64E+04
8.38E+03
6.48E+04
2.47E+04
2.09E+04
4.54E+04
2.61E+04
2.62E+04
1.72E+04
1.70E+04
5.77E+04
4.66E+04
4.99E+04
3.19E+04
1.26E+04
1.51E+04
7.30E+03
1.39E+03
3.16E+03
8.80E+02
5.44E+03
3.09E+03
7.40E+02
1.79E+03
4.79E+03
1.38E+03
1.93E+03
8.18E+02
6.21E+02
2.31E+02
2.85E+02
2.48E+02
1.66E+01
7.22E+01
3.73E+01
2.41E+01
7.18E+00
3.01E+01
1.72E+01
3.29E+00
2.14E+01
1.09E+01
1.28E+01
5.70E-01
4.99E+00
8.51E+00
5.79E-01
1.23E+00
7.58E-01
6.09E-02
3.58E-01
1.51E-01
1.34E+00
5.55E-02
7.29E-02
1.25E-01
1.38E-01
1.64E-01
1.25E-01
3.03E-02
5.96E-02
5.80E-02
6.34E-02
3.43E-02
5.35E-02
2.61E-02
7.08E-02
1.71E-02
1.69E-02
1.67E-02
1.06E-02
1.51E-02
2.06E-02
1.35E-02
1.77E-02
1.52E-02
1.50E-02
5.29E-03
1.15E-02
1.03E-02
1.52E-02
8.98E-03
8.38E-03
4.88E-03
1.44E-02
4.73E-03
1.17E-02
2.26E-02
2.16E-02
2.05E-02
1.18E-02
7.63E-03
7.44E-03
3.65E-03
1.07E-02
6.85E-03
5.98E-03
4.53E-03
4.11E-03
5.23E-03
5.94E-03
2.31E-03
8.29E-03
4.69E-03
4.94E-03
4.42E-03
6.73E-04
1.11E-03
1.08E-03
1.06E-03
1.04E-03
2.41E-03
1.54E-03
9.31E-04
2.64E-03
8.95E-04
7.37E-04
1.08E-03
2.97E-04
1.47E-04
8.74E-05
2.88E-04
2.83E-04
2.78E-04
2.73E-04
2.68E-04
2.36E-04
2.06E-04
2.28E-04
2.23E-04
2.90E-04
1.42E-04
1.86E-04
2.04E-04
1.99E-04
1.94E-04
1.89E-04
1.02E-04
1.01E-04
9.89E-05
9.70E-05
9.52E-05
4.69E-05
4.64E-05
4.59E-05
4.54E-05
1.81E-05
1.80E-05
1.79E-05
1.78E-05
1.77E-05
1.76E-05
1.75E-05
1.75E-05
1.74E-05
1.73E-05
1.72E-05
1.72E-05
1.71E-05
1.70E-05
1.69E-05
4.19E-05
4.13E-05
4.08E-05
4.03E-05
7.88E-05
7.66E-05
7.42E-05
7.18E-05
6.92E-05
3.36E-05
3.30E-05
6.39E-05
6.11E-05
5.81E-05
5.49E-05
2.62E-05
2.54E-05
2.45E-05
2.36E-05
2.26E-05
2.16E-05
2.05E-05
1.94E-05
1.82E-05
1.70E-05
1.56E-05
1.41E-05
5.20E-06
4.91E-06
4.62E-06
4.30E-06
3.95E-06
3.57E-06
3.15E-06
1.32E-06
3.40E-06
3.94E-07
3.33E-07
1.13E-07
9.96E-08
4.42E-08
4.00E-08
3.52E-08
1.86E-08
1.12E-08
1.25E-08
1.05E-08
1.14E-08
1.09E-09
t
' Zone number by interval
36$$ 1
' Mixture number by zone
39$$ 1
' Temperature by zone
41** 9.00000E+02
t
end