NESC0213 RIFF-RAFF.
RIFF-RAFF, Resonance Integrals in 2 Region Cell, Isotropic Flux and Isotropic Scattering
NAME OR DESIGNATION OF PROGRAM, COMPUTER, NATURE OF PHYSICAL PROBLEM SOLVED, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED, ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHOR, MATERIAL, CATEGORIES
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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.
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.
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.
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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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.
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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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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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.
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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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 |
Keywords: cell calculation, flux distribution, isotropy, resonance integrals, scattering.