CCC-0320 DOT-4.2.

1. NAME OR DESIGNATION OF PROGRAM:  DOT-4.2.

3. DESCRIPTION OF PROGRAM OR FUNCTION

DOT-4 determines the flux or fluence of particles throughout a two-dimensional geometric system due to sources either generated as a result of particle interaction  with the medium, or incident upon the system from independent sources. The principal application is to the deep penetration transport of neutrons and photons. Criticality (k-type and search) problems can be solved. Numerous printed edits of the results are available, and results can be transferred to output files for subsequent analysis.

4. METHOD OF SOLUTION

The Boltzmann transport equation is solved using the method of discrete ordinates, diffusion theory, or a special "combined P1" solution. In the discrete ordinates method, the primary mode of operation, balance equations are solved for the  flow of particles moving in a set of discrete directions in each cell of a space mesh, and in each group of a multigroup energy mesh. Iterations are performed until all implicitness in the coupling of cells, directions, groups, and source regeneration has been resolved. Methods are available to accelerate convergence by space-  dependent rebalance and by successive over-relaxation. Anisotropic cross sections can be expressed in a Legendre expansion of arbitrary order. Output data sets can be used to provide an accurate restart of a previous problem.

Special techniques are available to remove the effects of negative  fluxes caused by the finite space and direction meshes, and of negative scattering due to truncation of the cross-section expansion. The space mesh can be described such that the number of first-dimension (I) intervals varies with the second dimension (J).  The number of discrete directions can vary across the space mesh and with energy. The order of Legendre expansion can vary with cross- section set and with energy group.

Provision is made to treat sources resulting from the first collision of particles from a point source. In this case, flux due to uncollided particles is included in the output edits.

Direction sets can be biased, with more discrete direction segments per unit solid angle in some directions than in others.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

External force fields or non linear effects cannot be treated. Flexible dimensioning is used throughout, so that no restrictions are imposed on individual problem parameters. Certain options, especially diffusion and P1 theories, are not compatible with variable mesh and quadrature problems.
DOT-4/VE: The vectorized algorithm is not used with variable mesh and quadrature problems.

6. TYPICAL RUNNING TIME

Running time is roughly proportional to:
Flux work units (FWU) = number of space mesh cells x number of
                        directions x number of energy groups x
                        number of iterations per group.
Depending on the options chosen, a rate of 1.3 to 2.3 million FWU per minute on the IBM 360/195 is typical. Thus, a very large problem with 5000 space cells, 48 directions, 50 energy groups, and 10 iterations per group would require roughly 1 to 1.5 hours fo 360/195 CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM

In DOT-4/VE, the algorithm used in the calculation is partially vectorized. Problems with large number of spatial meshes and of discrete ordinates and with highly anisotropic scattering take maximum benefit from this feature.

8. RELATED AND AUXILIARY PROGRAMS:

GIP                 Cross-section preparation
GRTUNCL             First-collision source generation
RTFLUM              Flux edits and conversion

10. REFERENCES

- W.A. Rhoades and F.R. Mynatt:
  The DOT-III Two-Dimensional Discrete Ordinates Transport Code
  ORNL-TM-4280 (September 1973)
- F.R. Mynatt, F.J. Muckenthaler and P.N. Stevens:
  Development of a Two-Dimensional Discrete Ordinates Transport
  Theory for Radiation Shielding
  CTC-INF-952 (August 1969)
- 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)
- B. Barbucci, G. Mariotti:
  Development of a Vectorized Version of the DOT Code for an
  IBM 2090/200 VF Computer.
  Proc. of 7th Int. Conf on Radiation Shielding,
  Bournemouth (UK), 1988

- W.A. Rhoades:
  Informal Notes  (October 1979)
- W.A. Rhoades, D.B. Simpson, R.L. Childs and W.W. Engle Jr.:
  The DOT-4 Two Dimensional, Discrete-Ordinates Transport Code with
  Space-Dependent Mesh and Quadrature.
  ORNL/TM-6529  (August 1978)
- DOT-4 Problem Set Descriptions
  (April 1978)
- W.A. Rhoades:
  RTFLUM - A Module for Converting, Expanding, and Editing
  Standard Flux Files.
  (April 1978)
- W.A. Rhoades:
  The GIP Program for Preparation of Group-Organized
  Cross Sections Libraries
  (April 1978)
- ITOM - A Module to Convert ISOTXS Files to MATXS Format
  (April 1978)
- W.A. Rhoades:
  The FBSAM Data Transmission Package for IBM 360/370 Computers.
  ORNL/TM-5199  (January 1976)
- D.B. Simpson and W.A. Rhoades:
  The CFLAG Code
  (April 1978)
- W.A. Rhoades:
  The DOT-IV Variable Mesh Discrete Ordinates Transport Code.
  Preprint of Paper 5 of Session P2 to be Included in Proceedings
  of 5th International Conference on Reactor Shielding, Knoxville
  (April 18-22, 1977)
- W.A. Rhoades:
  Discrete Ordinates System Note 5 on "Space-Dependent
  Rebalance Parameters  (September 1978)
- W.A. Rhoades, R.L. Childs and W.W. Engle, Jr.:
  Comparison of Rebalance Stabilization Methods for Two-Dimensional
  Transport Calculations.

11. MACHINE REQUIREMENTS

Memory must be approximately 50,000 words for a small problem, expanding wht problem size. External data storage must be provided for 8 scratch files, of which 4 must be direct (random) access. User-supplied input and output data files must be supplied on sequential-access devices, e.g. tapes or equivalent.
CCC-320/02: Main storage requirements to execute the test case on CDC CYBER 170/740 are 220,600 (octal) words.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

The IBM version uses OS version 21. No special requirements are made of the operating system. Two types of overlay facility can be used if available.
CCC-320/02: The test case has been executed by NEA-DB on CDC CYBER 170/740 under the NOS 4.1 operating system.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

     Contributed by:
                     Radiation Safety Information Computational Center
                     Oak Ridge National Laboratory
                     Oak Ridge, Tennessee, U. S. A.
     DOT-4/VE:       P. Barbucci and G. Mariotti
                     ENEL
                     Thermal and Nuclear Research Center
                     PISA, Italy

File name	File description	Records
CCC0320_04.003	DOT-4.2 INFORMATION FILE	46
CCC0320_04.004	DOT-4.2 SOURCE (FORTRAN-4)	11897
CCC0320_04.005	DOT-4.2 SOURCE (ASSEMBLER)	4094
CCC0320_04.006	GIP SOURCE (FORTRAN-4)	2464
CCC0320_04.007	RTFLUM SOURCE (FORTRAN-4)	2369
CCC0320_04.008	ROUTINES NEEDED BY GIP, RTFLUM (ASSEMBLER)	372
CCC0320_04.009	JCL FOR JOB COMPILE,LINK,RUN	1737
CCC0320_04.010	DOT-4.2 PRINTED OUTPUT OF TEST CASES	13720