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NESC0213 RIFF-RAFF.

RIFF-RAFF, Resonance Integrals in 2 Region Cell, Isotropic Flux and Isotropic Scattering

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1. NAME OR DESIGNATION OF PROGRAM:  RIFF-RAFF.
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2. COMPUTERS
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Program name Package id Status Status date
RIFF-RAFF NESC0213/03 Tested 01-JUN-1971

Machines used:

Package ID Orig. computer Test computer
NESC0213/03 CDC 3600 CDC 3600
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3. NATURE OF PHYSICAL PROBLEM SOLVED

The program computes resonance integrals for absorbers in a rod in a two-region circularized cell for above thermal energies. The flux distribution in the cell is also computed and can be printed. The method of solution is based upon the following assumptions - isotropic scattering in the laboratory system, constant total cross section in the moderator and isotropic neutron fluxes entering and leaving the rod.
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4. METHOD OF SOLUTION

An energy range of interest is divided into extremely narrow intervals of equal lethargy. For each interval the  source distribution in each region is taken to be a three term polynomial in the radial coordinate. With this form for the source,  reaction rates in the rod are obtained by use of first flight escape probabilities. The flux distribution in the rod is obtained from use of Codys moment method and the flux distribution in the moderator is obtained by requiring - neutron conservation, vanishing of the derivative of the flux at the cell boundary and equality of the fluxes at the fuel-moderator interface. The reaction rates are accumulated over specified energy intervals to obtain resonance integrals. The flux distribution is used to obtain the source distribution for intervals at lower energies. Resonances are described by the single-level Breit-Wigner formulation with interference scattering included. All resonances contribute to cross sections for each fine group.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The program allows for 10 materials in each region. There can be 4 resonant absorbers in the rod, each having 60 resonances. The non-resonant materials can have 1/v absorption cross sections with the restriction that for the moderator, the macroscopic absorption cross section must be small compared to the scattering cross section. The width of the moderator in mean free paths should exceed 0.2. fluxes for 600 groups are stored.
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6. TYPICAL RUNNING TIME

Running time is roughly proportional to the product of resonances and fine groups. The running time for a problem with 20 resonances and 5000 fine groups is about 2 minutes for the CDC3600.
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7. UNUSUAL FEATURES OF THE PROGRAM

Standard methods of treating resonance absorption are based on the narrow resonance approximation in the moderator and the flat flux approximation in the fuel rod. Because the program uses space and lethargy dependent sources in computing resonance integrals, these standard approxi-between resonances significantly affects resonance integrals.
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8. RELATED AND AUXILIARY PROGRAMS:  MISH MASH (ACC abstract 214).
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9. STATUS
Package ID Status date Status
NESC0213/03 01-JUN-1971 Tested at NEADB
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10. REFERENCES
NESC0213/03, included references:
- P.H. Kier:
  RIFF RAFF, A Program for Computation of Resonance Integrals in a
  Two-Region Cell
  ANL-7033 (August 1965).
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11. MACHINE REQUIREMENTS

32k memory. Input is by punched card and output uses an off-line printer.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0213/03 FORTRAN-IV
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13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED:  SCOPE.
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14. ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

Data statements are used to store extensive tables within the program. If the program is to be used on computers that do not allow data statements these tables must be entered by use of cards or tape. A subroutine, FLUXP, together with its input, which computes and punches the data in these tables on cards is included in the package.
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15. NAME AND ESTABLISHMENT OF AUTHOR

                 P. H. Kier
                 Reactor Physics Division
                 Argonne National Laboratory
                 9700 South Cass Avenue
                 Argonne, Illinois  60439
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16. MATERIAL AVAILABLE
NESC0213/03
File name File description Records
NESC0213_03.001 SOURCE CDC/3600 + DATA FOR SAMPLE CASE 1963
NESC0213_03.002 AUX. PROGRAM SOURCE + DATA 194
NESC0213_03.003 SAMPLE PROBLEM OUTPUT 1306
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17. CATEGORIES
  • B. Spectrum Calculations, Generation of Group Constants and Cell Problems

Keywords: cell calculation, flux distribution, isotropy, resonance integrals, scattering.