implemented to calculate the 3-D absorbed dose distribution, for each energy group, scaled by
the flux along the current vector direction. Finally the EDK-SN will accumulate these individual
energy group dose contributions into a 3D total absorbed dose distribution. In Section 4.7, we
describe the parallel code algorithm.
4.5 External Source Benchmark
An external source problem for benchmarking purposes is presented to demonstrate the
EDK-SN methodology and provide a direct comparison with a full-physics Monte Carlo solution.
The model considered was a homogenous block of water (45 x 45 x 45 cm 3) with a 15 x 15 x 1
cm 3 Source (defined for 16 energy groups spanning from 0.0 to 8.0 MeV cast as a flat-weighted
energy distribution source term). A 3-D spatial mesh distribution was generated by the
PENMSH-XP mesh generating code in the PENTRAN systeml9. The model was then sub-
divided into 3 z-levels; each z-level was then divided equally into 9 coarse meshes, each coarse
mesh contained 3375 fine mesh cells; therefore, a total of 91,125 fine mesh cells were used in the
complete SN problem as shown in Figure 4-12.A.
20g
40 4
A. B
Figure 4-12. External Source impinging on block of water (left: Mesh distribution generated by
PENTRAN package; Right: MCNP5 Cell/Surface schematic input)