1. NAME AND TITLE

AXMIX: ANISN Cross Section Code System.

AUXILIARY ROUTINES

AMP: Activity Manipulation Program.

GIP: Group-Organized Cross-Section Input Program.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran 77 and C Language; IBM RS/6000 (P00075/IRISC/01), and Cray (P00075/CY0MP/00).

4. NATURE OF PROBLEM SOLVED

AXMIX provides a fast, simple, and economical tool for creating cross-section data sets for CCC-254/ANISN and CCC-543/TORT-DORT from cross-section sets in ANISN format, nuclide-organized libraries, and group-independent data sets. Numerous options including adjointing, Pn adjustments, changing table length, mixing, transport corrections of ANISN-type cross sections, and management of cross-section data sets and libraries are available.

Some fix-ups and additions to the older Cray versions have been implemented in the IBM RS/6000 version. The AXMIX scratch files are no longer using a TMPDIR but are written to named files resulting in more space allocation. Also an error was corrected in the commons that would not allow the proper return of an error condition when an end-of-file was reached on a cross-section file. The 1$ array has 2 extra inputs; (13. ISCT - order of scatter and 14. no of k-words). AMP has the option to weight responses with delta-E instead of delta-U by selecting K2=2 (13th entry in the 1$ array). The GIP program included in this package was copied from CCC-543MFMWS04/TORT-DORT 2.12.14.

5. METHOD OF SOLUTION

The number of energy groups which will fit into the core allocated is determined first. If all groups will fit, the solution is straightforward; if not, then the maximum number of groups which will fit is processed repeatedly using direct access I/O and storage disks.

6. RESTRICTIONS OR LIMITATIONS

AXMIX is limited in its ability to process cross-sections with upscatter, and extra caution must be used with them. This is due to the difference in the location of the total upscatter coefficient in ANISN and DORT cross sections. A special section on upscatter is, therefore, included in the document.

In addition to the standard I/O equipment, the computer facility must have either enough core memory to run all groups of a problem at once or direct access I/O routines of the FBSAM type developed at ORNL.

7. TYPICAL RUNNING TIME

Running time is inversely proportional to the number of groups of data which will fit into core memory. Problems of a practical nature require from 2 to 20 seconds of CPU time on the IBM RS/6000 computer. The sample problem ran in .20 seconds of CPU time.

8. COMPUTER HARDWARE REQUIREMENTS

AXMIX is operable on the IBM RS/6000 and Cray systems. At least 150 K bytes of memory are required.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran 77 compiler is required. On the RS/6000, the XLF (version 3.2.2.3) compiler was used for testing the codes under AIX (3.2.5). The Cray package runs under UNICOS using the CFT77 compiler.

10. REFERENCES

G. D. Haynes, "The AXMIX Program for Cross Section Mixing and Library Arrangement," ORNL/TM-5295 (December 2, 1974).

W. W. Engle, Jr., "AMP (Activity Manipulation Program)," Originally ORNL/TM-5296 (June 16, 1975).

W. A. Rhoades, "The GIP Program for Preparation of Group-Organized Cross Section Libraries," Informal Notes (November 1975).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and a 3.5" (1.44 MB) diskette written in DOS format which contains the source code and sample problem input and output for AMP, AXMIX and GIP.

12. DATE OF ABSTRACT

February 1984; revised February 1991, April 1995, June 1996.