NESC0754 DEMONR

1. NAME OR DESIGNATION OF PROGRAM:  DEMONR

3. DESCRIPTION OF PROBLEM OR FUNCTION

DEMONR treats the behavior of neutrons in a slab shield. It is frequently used as a teaching tool.

4. METHOD OF SOLUTION

An unbiased Monte Carlo code calculates the number, energy, and direction of neutrons that penetrate or are reflected from a shield.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Only one shield may  be used in each problem. The shield material may be a single element or a homogeneous mixture of elements with a single effective atomic  weight. Only elastic scattering and neutron capture processes are allowed. The source is a point located on one face of the slab. It provides a cosine distribution of current. Monoenergetic or fission  spectrum neutrons may be selected.

6. TYPICAL RUNNING TIME

For 10,000 neutrons incident on a five centimeter slab of sodium, the CPU time is about 35 seconds. The NESC executed the sample problems in 100 CPU seconds on an IBM370/195.

NEA-DB executed the test case included in this package  on an IBM 3084 computer in 61 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM

The user may choose the number of  energy groups and angular intervals for problem output. The cross-section detail is also selected by the user to be appropriate  for the shield material.

8. RELATED AND AUXILIARY PROGRAMS

DEMONR is based on the DEMON demonstration Monte Carlo code described in reference 1.

10. REFERENCES

- N.M. Schaeffer:
  Reactor Shielding for Nuclear Engineers
  TID-25951 (1973).
- W.E. Selph, J.D. Marshall and N.M. Schaeffer:
  Demonstration Monte Carlo Program
  RRA-N7122 A, Revised (June 15, 1972).

- Techniques for Efficent Monte Carlo Simulation: Volume II - Randon
  Number Generation for Selected Probability Distributions
  Appendix B, MIRAN - A Machine Independent Package for Generating
  Uniform Random Numbers
  SAI-72-590-LJ, Vol. II.
- J.C. Courtney and D.S. Ambuehl:
  Fission Spectrum Calculations in Slab Geometries
  Reprint from Transactions of the American Nuclear Society, Vol. 21
  pp. 76-77 (1975).
- DEMONR, ACC No. 754.360, DEMONR Input Data Requirements
  Argonne Code Center Note 78-20 (May 10, 1978).

11. MACHINE REQUIREMENTS

A card reader, tape drives, line printer, and 60K of memory are required.

316K bytes of main storage were required to run the test case on an IBM 3084.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   HASP 3.1.

MVS/SP (IBM 3084).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

Because of the random number generator (RNG), the output will vary from installation to installation. For each problem the number of neutrons transmitted, reflected, and absorbed are given. To assure a correct running, the sum of the row (column) totals of the current per source neutron of all three of the above must equal the number of neutrons going into the shield. For the sample problem the number of neutrons going in was 1. The RNG routines RANDU, URAND, and RANSET may be replaced by more efficient routines designed for the particular system being used.

15. NAME AND ESTABLISHMENT OF AUTHOR

                 J. C. Courtney
                 Nuclear Science Center
                 Louisiana State University
                 Baton Rouge, Louisiana  70803

File name	File description	Records
NESC0754_01.001	Information file	49
NESC0754_01.002	DEMONR source program (fortran IV)	558
NESC0754_01.003	Sample data input	75
NESC0754_01.004	Sample output printing	413