JAEA-Data/Code 2007-004 - Welcome to Research Group for ...

esonance nuclides is automatically calculated by the installed collision probability routines. The
factor is given not for an absorber lump but for each constituent nuclide for the cell which
contains a resonant nuclide in two or more materials with different compositions.
• A doubly heterogeneous system can be solved by successive cell calculations since homogenizing
and collapsing of macroscopic cross-sections is carried out separately. Especially, the resonance
absorption of which double heterogeneity effect should be solved simultaneously, can be treated
as far as the microscopic cell can be approximated by any of 1D cells.
• The SRAC system can be executed on most of computers with the UNIX operating system or its
similar ones like Linux or FreeBSD. Installation of the system is easily done with an equipped
installation command which prepares appropriate source programs and other necessary data
depending on user’s machine.
This report is the fourth edition of the SRAC users manual. A number of additions and
modifications to the functions and the library data for the old versions 1)-3) of SRAC have been made to
establish the comprehensive neutronics code system SRAC 2006.
1.2 System Structure
Figure 1.2-1 shows the structure of the SRAC system. The body code of the SRAC integrates
the following three transport and two diffusion codes for neutron flux calculations.
• PIJ :
Collision probability method code developed at JAERI (current JAEA) which
covers 16 lattice geometries shown in Fig.1.2-2,
• ANISN 4) : One-dimensional S N transport code which covers slab (X), cylinder (R), and
sphere (R S ) geometries,
• TWOTRAN 5) : Two-dimensional S N transport code which covers slab (X-Y), cylinder (R-Z),
and circle (R-θ) geometries,
• TUD : One-dimensional diffusion code developed at JAERI, which covers slab (X),
cylinder (R), and sphere (R S ) geometries,
• CITATION 6) : Multi-dimensional diffusion code which covers 12 types of geometries
including triangular and hexagonal spatial mesh divisions.
For the imported codes ANISN, TWOTAN, and CITATION, several modifications are added for
speedup on vector computers, for interfacing of cross-sections between codes, and for our additional
functions, while several original functions are suppressed. As far as flux calculation is concerned,
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