SCALE Software Coordinator
I've been trying to benchmark CENTRM to a similar MCNP calculation and am seeing a disparity between the two that I can't explain. The attached plot shows the spectra generated by the two programs. The CENTRM spectrum is much harder for some reason.
In MCNP I'm modeling a large sphere of U-238 with reflected boundaries intended to be an infinite medium) and taking a fine energy mesh tally of the neutrons. I created the MCNP data library by running RECONR and BROADR modules of NJOY to reconstruct and broaden the U-238 to 900 K. Fission is turned off and I'm using an analytic Watt fission spectrum according to S(E) = exp(-E/0.966)*sinh(sqrt(2.842*E) (MCNP manual page H-3) for the source.
In CENTRM I am using the below input. My source given in card 31** is obtained by integrating the Watt Fission spectrum over the 238 energy groups used in SCALE.
Any help would be appreciated. I'm basing this input off of the example problem for CENTRM given in the SCALE manual at F18.6.2 and I may have missed something when modifying it for my problem.
=shell
del C:\scale6\tmpdir\ft88f001
copy C:\scale6\data\xn238v7 ft88f001
end
=ajax
0$$ 11 0
1$$ 1 T
2$$ 88 1 T
3$$ 92238
4$$ 92238 T
end
=bonami
0$$ 11 0 18 1
1$$ 0 1 1 1 1 0
2** e t
3$$ 1
4$$ 92238
5** 1.000
6$$ 10000
8** 9.00000E+02
10$$ 92238
11$$ 0 t
end
=worker
0$$ 1 0 4 18 19 0
1$$ 1 0 -2 -1 -1 1 1 1
1t
2$$ 92238
6** 9.00000E+02
2t
end
=crawdad
0$$ 81 17 18 77
1$$ 1 66666 1 0 0 1 e
1t
2$$ 92238 7 -1 1 0 -1 0
3** 1.00000E-04 2.000E+07
2t
4** 9.00000E+02
3t
end
=centrm
CENTRM: U-238 Inf medium at 900 K
0$$ 7 0 4 81 0 25
15 16 17 18 19 8
9
1$$ 0 1 1 1 1 1
1 0 64 0 20 100
2 2 3 3 64 1
2$$ -2 3 0 1 0 2
0 1 100 64 0 0
3** 1.00000E-04 1.00000E-04 1.00000E+00 0.00000E+00 1.00000E+00
2.00000E+04 1.00000E-03 1.00000E-01 0.00000E+00
t
13$$ 1
14$$ 92238
15** 1.0000
t
30$$ 1
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
36$$ 1
39$$ 1
41** 900
t
end
Brian Triplett
SCALE Software Coordinator
Brian Triplett