IAEA0914 HEXNOD2/3.

1. NAME OR DESIGNATION OF PROGRAM:  HEXNOD2/3.

3. DESCRIPTION OF PROGRAM OR FUNCTION

Two- or three dimensional coarse mesh solution of steady state two group neutron diffusion equation in arrays of regular hexagons or hexagonal subassemblies.

4. METHOD OF SOLUTION

The neutron flux in a hexagonal node is expanded in a series of Bessel functions in the hexagonal plane. Polynomials up to the 4th order are used for the approximation of neutron flux in axial direction of three dimensional cases. Resulting relations between node averaged fluxes and mean partial currents of node faces in connection with the neutron balance of nodes are used to calculate the eigenvalue Keff, mean fluxes and mean powers of nodes. The iterations process is divided into inner and outer iterations. The iterations are accelerated by Ljusternik and Tschebyscheff extrapolation schemes. The power densities in the  nodes and subassembly powers are computed for given reactor power in three dimensional cases. 30 degree reflectional, 60 and 120 degree rotational core symmetry and the whole core can be treated.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

If the problem size  designated by LIAR and LRAR exceeds 3000 and 50000 respectively, the lengths of the working array MIAR and MRAR in the main program can be increased. External sources are not permitted.

6. TYPICAL RUNNING TIME

The CPU time is problem dependent. The calculation of a three dimensional case with 528 nodes requires about 300 s of CPU time.

NEA-DB executed the test case included in this package  on an IBM 3081 computer. Required CPU times were 2 seconds (case 1); 33 seconds (case 2).

7. UNUSUAL FEATURES OF THE PROGRAM

Albedo matrix boundary conditions  at the outer boundary of the reactor can be used.
   Some of the nodes can contain non-multiplying materials.

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES:

- U. Grundmann:
  HEXNOD23 - A Two- and Three-Dimensional Nodal Code for Neutron
  Flux Calculation of Thermal Reactors with Hexagonal Geometry.
  ZfK-557  (June 1985)

11. MACHINE REQUIREMENTS

Main storage of about 320,000 bytes for the given lengths of working arrays.

To run the test cases on IBM 3081, 520K bytes of main storage were required.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  Standard OS/ES.

MVS-SP (IBM 3081).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

Ulrich Grundmann
Zentralinstitut fuer Kernforschung Rossendorf
Postfach 19
Dresden 8051
Federal Republic of Germany

File name	File description	Records
IAEA0914_01.001	Information file	52
IAEA0914_01.002	HEXNOD-2/3 main program (FORTRAN 77)	81
IAEA0914_01.003	HEXNOD-2/3 subroutines (FORTRAN 77)	3222
IAEA0914_01.004	JCL to run sample cases	56
IAEA0914_01.005	Sample case 1 input	45
IAEA0914_01.006	Sample case 1 output	153
IAEA0914_01.007	Sample case 2 input	75
IAEA0914_01.008	Sample case 2 output	411