**1. NAME AND TITLE**

TRANSHEX: Two-dimensional Multigroup Collision Probability Code System for Hexagonal
Geometry.

**2. CONTRIBUTOR**

Technical Research Center of Finland, Nuclear Engineering Laboratory, Helsinki, Finland.

**3. CODING LANGUAGE AND COMPUTER**

Fortran V; UNIVAC 1108.

**4. NATURE OF PROBLEM SOLVED**

TRANSHEX is a multigroup integral transport program that determines the thermal scalar flux
distribution arising from a known epithermal flux in two-dimensional hexagonal geometry.

**5. METHOD OF SOLUTION**

TRANSHEX solves the isotropic collision probability equations for a region-averaged scalar flux
by an iterative method. Either a successive over-relaxation or an inner-outer iteration technique is
applied. Flat flux collision probabilities between trigonal space regions with white boundary condition
are utilized. The effect of epithermal flux is taken into consideration as a slowing down source that
is calculated for a given spatial distribution and 1/E energy dependence of the epithermal flux.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for TRANSHEX.

**8. COMPUTER HARDWARE REQUIREMENTS**

Organized as an overlay structure, TRANSHEX requires about 13.6 K words core memory plus
the memory required by array T on the UNIVAC 1108. If no overlay structure is used, the memory
required is about 18 K words plus the array T.

**9. COMPUTER SOFTWARE REQUIREMENTS**

TRANSHEX runs under the EXEC 8 operating system.

**10. REFERENCE**

E. Patrakka, "TRANSHEX: A Two-dimensional Multigroup Collision Probability Computer
Program for Hexagonal Geometry" (June 1973).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code plus sample problem input and output.

**12. DATE OF ABSTRACT**

January 1984.

**KEYWORDS:** TWO-DIMENSIONS; MULTIGROUP; COLLISION PROBABILITY