NESC0579 DWARF

1. NAME OR DESIGNATION OF PROGRAM:  DWARF

3. DESCRIPTION OF PROBLEM OR FUNCTION

DWARF allows one-dimensional simulation of reactor burnup and xenon oscillation problems in slab, cylindrical, or spherical geometry using a few-group diffusion theory model.

4. METHOD OF SOLUTION

The few-group, neutron diffusion theory equations are reduced to a system of finite-difference equations that are solved for each group by the Gauss method at each time point. Fission neutron source iteration can be accelerated with Chebyshev extrapolation. A thermal feedback iterative loop is used to obtain consistent solutions for the distributions of reactor power, neutron flux, and fuel and coolant properties with the neutron group constants functions of the latter. Solutions for the new nuclide concentrations of a time-point are made with the flux assumed constant in the time interval.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Maxima of -
     4 groups
    40 regions
    50 macroscopic materials*
    50 nuclides per region
   250 mesh points
* Only 10 are functions of the feedback variables.

6. TYPICAL RUNNING TIME

Primarily a function of the number of feedback iterations required, running time ranges from less than a second to several seconds per time-step.

7. UNUSUAL FEATURES OF THE PROGRAM

The neutron group constants for the macroscopic materials can be user-specified functions of the feedback variables and the group constants can be a mixture of the nondepletion macroscopic and depleting microscopic material data in  a region. Automatic searches on buckling, poison, region dimensions, a region interface position, or total power can be done at each time-point. Basic input data and material constants can be changed freely at any time during problem execution. The solutions for the coolant thermal properties cover the entire range from the subcooled through the superheated vapor regimes with constant pressure and mass flow rate assumed. A plotted output routine can plot up to three distributions (of flux, power, temperatures, densities, etc.)  per frame versus the one-dimensional space variable.

8. RELATED AND AUXILIARY PROGRAMS

CORA, a few-group, one-dimensional  diffusion program and SINBAD, a nuclide depletion program.

10. REFERENCES:

- G. E. Putnam, and E. C. Anderson;
  DWARF, A Few Group, One-Dimensional, Diffusion Theory Program for
  Reactor Depletion with Adjustable Reactivity Feedback
  ANCR-1083 (Nov. 1972).

11. MACHINE REQUIREMENTS

330K bytes of core storage plus 8 FORTRAN logical units, including units for card input, printed output, and plotted output.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   OS/360.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

   The
program compiles with the FORTRAN H compiler, optimization level 2.  It consists of a root main segment that calls 5 overlays serially. The clock and plotted output routines are installation dependent.

15. NAME AND ESTABLISHMENT OF AUTHORS

                 E. C. Anderson and G. E. Putnam
                 EG&G Idaho, Inc.
                 P. O. Box 1625
                 Idaho Falls, Idaho  83401

File name	File description	Records
NESC0579_01.001	SOURCE PROGRAM (F4)	8313
NESC0579_01.002	LOC SUBROUTINE (ASSEMBLER)	6
NESC0579_01.003	OVERLAY CARDS	16
NESC0579_01.004	JCL	12
NESC0579_01.005	SAMPLE PROBLEM INPUT DATA	149
NESC0579_01.006	SAMPLE PROBLEM PUNCHED OUTPUT	10
NESC0579_01.007	SAMPLE PROBLEM PRINTED OUTPUT	1234