Sample Problem 4. Cross Sections for GODIVA

  TEST 4 -- GODIVA
  0  1  0  1  1  1  0  3  30  1
  20  4  34  0  0  1  1  3  1  0
  CORE
  CORE/
  1  1  U235  .0450/
  1  1  U238  .002498/
  1  1  U234  .000492/
  CHI
  19R1  11/ COLLAPSE OUT BOTTOM 11 GROUPS
  6.80E-8  1.72E-7  5.78E-7  3.30E-6  1.88E-5  5.92E-5  3.52E-4 3.21E-4
  4.00E-4  4.43E-4  4.61E-4  8.79E-4  7.74E-4  5.90E-4  3.53E-4 2.83E-4
  6.30E-5  9.77E-6  1.27E-6  1.62E-7  1.87E-8  2.23E-9  3.41E-10 3.56E-11
  5.38E-12  2.29E-12  9.15E-13  1.30E-15 7.63E-19 1.59E-22/
  STOP

GODIVA is a bare sphere of enriched uranium that is often used as a cross-section benchmark (Ref. 23). In this example, macroscopic P3 cross sections are produced directly. As a result, it is not necessary to mix cross sections in the transport code. In addition to saving time and storage space, this approach allows a mixture-dependent fission $\chi$ to be formed. Because the spectrum of GODIVA is rather hard, the lower energy groups are collapsed down to fewer groups (note the use of the repeat specification). An initial flux guess is read in from the input file to improve the estimate for the fission spectrum $\chi$ and to improve the group collapse. Note that ICOL=30, the number of fine groups, and NGROUP=20, the number of coarse groups for the output material. CHI is a special edit command that does not require any further specification.

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