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2.7 TUD ; One-dimensional Diffusion Calculation
The one-dimensional diffusion routine TUD is preferred to the CITATION by the simpler input
requirement. The following data are required if IC2=4 or IC12=4 is entered in Sect.2.2.
Block-1 Control integers /9/
1 NRMAX Number of regions
A region is divided into fine mesh intervals for flux calculation by the finite
difference method. Material (a set of cross-sections) is assigned by region.
2 IG Geometry type
= 0 Slab (X)
= 1 Cylinder (R)
= 2 Sphere (R S )
3 IBOUND Outer boundary condition
= -1 Zero flux at the outer boundary
= 0 Reflective
= 1 Zero flux at the group dependent extrapolated distance calculated by
using the Milne problem constant: 0.71045.
= 2 Zero flux at the extrapolated distance by using the constant entered by
Block-9
Note: The boundary condition at r = 0
is always set as reflective.
4 IGUESS Initial flux guess control
= -1 Read from logical device 33 prepared by the user
= 0 Uniform; no input required
= N Read from logical device 10 in binary mode as written by ITFLUX below
5 IPTXEC Print control for cross-sections
= 0 Skip print
= 1 Print
6 ITFLUX Print control for fine flux distribution
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