NESC0358 TWOTRAN2

1. NAME OR DESIGNATION OF PROGRAM:  TWOTRAN2.

3. DESCRIPTION OF PROBLEM OR FUNCTION

TWOTRAN2 solves the two-dimensional multigroup transport equation in (x,y), (r,theta), and (r,z) geometries. Both regular and adjoint, inhomogeneous and homogeneous (keff and eigenvalue searches) problems subject to vacuum, reflective, periodic, white or input-specified boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted.

4. METHOD OF SOLUTION

The discrete ordinates approximation for the angular variable is used in finite difference form which is solved with the central (diamond) difference approximation. Negative fluxes are eliminated by a local set-to zero and correct algorithm. Standard inner (within-group) and outer iterative cycles are accelerated by a coarse-mesh rebalancing on a coarse mesh which may be independent of the material mesh.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Variable dimensioning is used so that any combination of problem parameters leading to a container array less than MAXLEN can be accommodated. On IBM machines, TWOTRAN2 will execute in the 4-byte mode so that any combination of problem parameters leading to a container array less than MAXLEN can be accommodated.  MAXLEN can be several hundred thousand and most problems can be core-contained. On the CDC machines MAXLEN can be slightly greater than 40,000 words and peripheral storage is used for most group-dependent data.

6. TYPICAL RUNNING TIME

A six-group, S4, 42 x 42 mesh point, keff calculation of an  EBR-II model requires about 3.9 minutes of CDC7600 time. The sample problems require 6 minutes on the IBM360.

7. UNUSUAL FEATURES OF THE PROGRAM

Provision is made for creation of standard interface output files for Sn constants, angle- integrated fluxes and angular fluxes. Standard interface input files for sources, fluxes, cross sections and Sn constants may be read. All binary operations are localized in subroutines called REED and RITE.  Detailed edit options, including angular fluxes, dumps and restart capability are provided. Optional use of an arbitrary rebalance mesh independent of the material mesh is allowed.

8. RELATED AND AUXILIARY PROGRAMS

TWOTRAN2 is an improved version of the TWOTRAN program. Many comment cards were added and much simplifying programming was performed to make TWOTRAN2 as easy to understand as possible.

10. REFERENCES

- K. D. Lathrop  and F. W. Brinkley, Theory  and Use of
the General-Geometry TWOTRAN Program, LA-4432, April 1970.
- K. D.  Lathrop, F. W.  Brinkley, and P.  Rood, Theory
and Use of the Spherical Harmonics, First Collision Source, and  Variable Weight Versions of the TWOTRAN Transport Program,   LA-4600, March 1972.
- R. Douglas O'Dell and Raymond E. Alcouffe:
Transport Calculations for Nuclear Analyses: Theory and
Guidelines for Effective Use of Transport Codes
LA-10983-MS and UC-32 (September 1987)

   - K. D. Lathrop, and F. W. Brinkley;
     TWOTRAN-II: An Interfaced, Exportable Version of the TWOTRAN
     Code for Two-Dimensional Transport. LA-4848-MS, UC-32 (July
     1973).
- K. D. Lathrop, and F. W. Brinkley;
TWOTRAN-II: An Interfaced, Exportable Version of the TWOTRAN
Code for Two-Dimensional Transport. LA-4848-MS, UC-32 (July
1973).

11. MACHINE REQUIREMENTS

Five output units, five interface units (use of interface units is optional) and two system input/output units are required. A large bulk memory is desirable, but it can be replaced by disk, drum or tape storage.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

                 K. D. Lathrop and F. W. Brinkley
                 Los Alamos Scientific Laboratory
                 P. O. Box 1663
                 Los Alamos, New Mexico  87544

File name	File description	Records
NESC0358_03.001	INFORMATION	5
NESC0358_03.002	SOURCE PROGRAM (F4) EBCDIC	7503
NESC0358_03.003	DD CARDS	23
NESC0358_03.004	OVERLAY CARDS	20
NESC0358_03.005	SAMPLE PROBLEM INPUT DATA	1986
NESC0358_03.006	SAMPLE PROBLEM PRINTED OUTPUT	1195

File name	File description	Records
NESC0358_04.001	SOURCE PROGRAM (F4) EBCDIC	7305
NESC0358_04.002	SAMPLE PROBLEM INPUT DATA	1985
NESC0358_04.003	SAMPLE PROBLEM PRINTED OUTPUT	25501