1. NAME AND TITLE

VALE 1.1: A Multigroup Diffusion Theory Neutronics Code System for Solving Two- and Three-Dimensional Problems for Triagonal Geometries.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran 77, IBM 386, 486, and an IBM RISC 6000 Workstation.

4. NATURE OF PROBLEM SOLVED

VALE is a companion code module to the VENTURE neutronics code module in the BOLD VENTURE code system. The original intent was to implement VALE in the BOLD VENTURE system, but the implementation was never carried out. VALE is now a stand-alone code that can be run independently of the BOLD VENTURE system. VALE, Version 1.1, corrects a conflict in naming of the interface data files on workstations and a problem related to direct access block size and record length specifications. Other minor changes were also made in this release.

A variety of types of problems may be solved: the usual neutron flux eigenvalue problem, or a direct criticality search on buckling, on a reciprocal velocity absorber (prompt mode), or on nuclide concentrations. The adjoint problem and fixed source problems may be solved, as well as the dominating higher harmonic, or the importance problem for an arbitrary fixed source. Also implemented is a parametrized formulation that allows part of the absorption term to lie off the matrix diagonal (Taylor series, linear flux, and linear finite element equation formulation methods). The mesh points are located at the material junctures (mesh edge) on planes and mesh centered between planes. The mesh may be 120, 60, or 30 degrees. It is not necessary to treat a parallelogram. With 60 degree mesh point arrangement, only a triangle, or a truncated triangle may be treated. With 30 degree mesh arrangement, a pie shaped section may be treated. There is provision for the more commonly used boundary conditions including the repeating boundary, 180 degree rotational symmetry, and the rotational symmetry conditions for the 30 degree, 60 degree, and 120 degree triangular grids on planes.

5. METHOD OF SOLUTION

Inner-outer iterations are done with restrained line overrelaxation, and asymptotic flux extrapolation done when distinct error modes are established. Normally the eigenvalue of a problem is calculated each outer iteration from an overall neutron balance; however, source ratios are used in some situations.

6. RESTRICTIONS OR LIMITATIONS

The large data arrays in VALE are variably dimensioned. The size of problems that may be run are restricted only by the size of the memory available.

7. TYPICAL RUNNING TIME

A three dimensional problem with 36 planes and 324 points per plane requires approximately 40 minutes on a 386-33 PC, and 4 minutes on a work station. RSIC tested the problem VALESAMP.INP on an IBM RISC 6000 Model 550; the problem took 96 seconds of CPU time. On a PC 486/66, VALESAMP.INP took about 1 minute 15 seconds.

8. COMPUTER HARDWARE REQUIREMENTS

VALE will run on a 386 or 486 PC with a math coprocessor or an IBM RISC/6000 Work Station.

9. COMPUTER SOFTWARE REQUIREMENTS

VALE consists of approximately 400 subroutines (approximately 50000 FORTRAN statements), which when compiled creates an executable file of approximately 1.5 megabytes. VALE-PC was compiled with the Lahey Extended Memory Compiler F77L-EM/32, Version 5.01, and VALE-WS was compiled with the AIX XL FORTRAN Compiler/6000, Version 2.2 and 2.3. All of the large arrays are stored in one data container array "A", dimensioned A(IP1 + IP2 X 1,000,000) where IP1 and IP2 are defined in Reference 2 below. For VALE-PC this dimension is allocated at run time. For VALE-WS, "A" was compiled with a dimension of 2,000,000 (4-byte words) in the main program. The input for a problem must be a file named VALE.INP. To run a problem, copy the input in VALE.INP and at the prompt type VALE. The output will be written on a file named VALE.OUT. A condensed output file (VALE.CND) is also written. The code may create as many as 30 or more scratch I/O files (sequential and direct access) during execution, depending upon the problem being run and the memory available. VALE chooses one of two modes of data storage during the iterative procedure: 1) if enough memory is available, data is I/O-ed for all mesh points for each energy group, 2) otherwise data is I/O-ed for several planes of points for each energy group. Provision has been made to specify as input two data items for opening direct access files. These input items are IP3 and IP4 in the "USER INPUT INSTRUCTIONS TO CONTROL MODULE CONTROL1" (Reference 2 below). If IP3=0, bytes will be used for the RECL parameter in direct access OPEN statements. If IP3=1, 4 byte words will be used. VAX uses words. Most other compilers use bytes. IP4 is the maximum record length allowed (specified as 4-byte words) for RECL. This also varies with the compiler being used. The default values are 0 for IP3 8000 for IP4.

10. REFERENCES

a: Included in documentation:

T. B. Fowler and J. P. Renier, "Changes to CCC-613/VALE - For Release Version 1.1," (June 30, 1993).

T. B. Fowler and J. P. Renier, "COMPUTER CODE ABSTRACT - VALE (Release Version 1.0).

D. R. Vondy and T. B. Fowler, "Neutronics Code Vale for Two-Dimensional Triagonal (Hexagonal) and Three-Dimensional Geometries," ORNL-5792 (August 1981).

D. R. Vondy and T. B. Fowler, and G. W. Cunningham, "The Bold Venture Computation System for Nuclear Core Analysis, Version III," ORNL-5711 (June 1981).

D. R. Vondy, T. B. Fowler, and G. W. Cunningham, "Input Data Requirements for Special Processors in the Computation System Containing the Venture Neutronics Code," ORNL-5229/R1 (July 1979).

b: Background References:

RSIC Computer Code Collection, CCC-459B&C (March 1991). (This is a rewrite of Reference 2 above).

G. E. Bosler, R. D. O'Dell, and W. M. Resnik, "LASIP-III, A Generalized Processor for Standard Interface Files," LA-6280-MS (April 1976).

D. R. Vondy, T. B. Fowler, and G. W. Cunningham, "VENTURE: A Code Block for Solving Multigroup Neutronics Problems Applying the Finite-Difference Diffusion-Theory Approximation to Neutron Transport, Version II," ORNL-5062/R1 (November 1977).

11. CONTENTS OF CODE PACKAGE

Included is the referenced documents (a), source code files, batch files, data files, executable files, and a sample problem output file. Files are in compressed mode for DOS on 1 DS/HD 3.5-inch diskette (must be 1.44 MB) and tar format on 1 DS/HD 3.5-inch (2 MB) diskette.

12. DATE OF ABSTRACT

February 1993, August 1994.