1. NAME AND TITLE OF DATA LIBRARY
FARS: 122-Group Coupled Neutron and Gamma-Ray Transport Code Cross- Section Data.
2. NAME AND TITLE OF DATA RETRIEVAL PROGRAM
SUPERTOG Data Retrieval Program.
3. CONTRIBUTORS
Computing Technology Center, Union Carbide Corporation Nuclear Division, Oak Ridge, Tennessee.
Oak Ridge National Laboratory, Oak Ridge, Tennessee.
4. HISTORICAL BACKGROUND AND INFORMATION
DLC-9/FARS is a library of coupled neutron and gamma-ray multigroup cross-section data in ANISN/DOT/DTF-IV format. The 122 group, P8 expansion, cross-section data library was compiled for use by F. A. R. Schmidt in a state-of-the-art study for RSIC.
5. APPLICATION OF THE DATA
DLC-9/FARS data is suitable for neutron, gamma-ray, or coupled neutron and gamma-ray transport calculations. It is intended for use in multigroup discrete-ordinates or Monte Carlo transport codes which treat anisotropic scattering by Legendre expansion up to order P8.
Specifically, the retrieval program manipulates DLC-2/100G such that it conforms to input requirements of the CCC-82/ANISN-CEA, CCC-89/DOT, or CCC-42/DTF-IV codes.
Note of Caution: The DLC-9/FARS 122-group coupled neutron-gamma-ray cross section library cannot be collapsed correctly with versions of CCC-82/ANISN which were distributed before July 31, 1969, unless a correction is made to subroutine WATE. Also, the cross section table position 1 for gamma groups in the DLC-9/FARS library is not . Instead, it is . Eg where is the absorption cross section and Eg is an average energy for the group. This quantity appears rather than that of the the absorption cross section, , because of the nature of data produced by the MUG program.
6. SOURCE AND SCOPE OF THE DATA
DLC-9/FARS is a coupled set of neutron and gamma-ray cross-section data for the elements H, C, N, O, Mg, Al, Si, Ca, and Fe. PSR-13/SUPERTOG was used to generate the neutron multigroup data for all elements except Si, Fe, and Ca, which were generated using CSP. (For the thermal group, it was assumed that scattering was isotropic in the lab system and group averaging was done by hand assuming a Maxwellian energy distribution as a weighting function.)
The source of nuclear data for all elements except Si, Fe, and Ca was ENDF/B. The Si and Fe came from the CCC-17/O5R library and the Ca from a recent evaluation by M. K. Drake. This data is averaged over each specified group width. The explicit assumption was made that the flux (weighting function) per unit lethargy was constant. When resonance data were available, resolved and unresolved resonance contributions were calculated and used. The neutron transfer data consists of fine-group constants such as one-dimensional reaction arrays (absorption, fission, etc.), Pn elastic scattering matrices, and inelastic and (n,2n) scattering matrices. The units are barns rather than cm2.
The Pn scattering matrices for the gamma-ray groups and one-dimensional reaction arrays were computed from DLC-3/HPIC, using MUG.
The neutron to gamma-ray group transfer matrices were generated using PSR-11/POPOP4 with account being taken for the production of gamma-rays from thermal and epithermal neutron capture, inelastic scattering, and other neutron reactions.
DLC-9/FARS represents a P8 approximation to elastic (or Compton) scattering angular distributions. There are 104 neutron groups covering an energy range from 15 MeV to thermal. This group structure was designed by E. A. Straker to properly describe neutron transport in media containing a substantial proportion of oxygen. For gamma-rays, 18 groups cover the energy range from 10 to 0.02 MeV.
7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM
The retrieval program, which was written by the authors of PSR-13/SUPERTOG, is the same as that used for DLC-2/100G except that some array dimensions are increased to allow for 122 groups rather than 100. This program will retrieve DLC-9/FARS data and will then, by input option, edit the data, punch cards in either CCC-82/ANISN-CEA or CCC-42/DTF-IV format, or write an unformatted tape for use by CCC-82/ANISN-CEA.
8. DATA FORMAT AND COMPUTER
/; IBM 360/370.
9. TYPICAL RUNNING TIME
Using the retrieval program to produce an unformatted tape, for use by CCC-82/ANISN-CEA, containing elements hydrogen and oxygen for P8 expansion requires approximately 2 minutes on the IBM 360/65 computer.
10. REFERENCES
a. Included in the documentation:
Robert W. Roussin, "Description of the DLC-9/FARS Data," Informal note (1969).
R. Q. Wright, "User's Manual for SUPERTOG DATA RETRIEVAL Program," Informal notes (June 1969).
R. W. Roussin, Using ANISN to Reduce the DLC-2 100 Group Cross-Section Data to a Smaller Number of Groups, ORNL-TM-3049 (May 1969).
R. W. Roussin, "Note on Collapsing Group Structure for Coupled Cross-Section Sets," Informal note (November 1969).
b.Background information:
F. A. R. Schmidt, The Attenuation Properties of Concrete for Shielding of Neutrons of Energy Less than 15 MeV, ORNL-RSIC-26 (August 1970).
M. K. Drake, Neutron and Gamma-Ray Production Cross Sections for Sodium, Magnesium, Chlorine, Potassium, and Calcium, NDL-TR-89 I-VI (1967).
E. A. Straker, Time Dependent Neutron and Secondary Gamma-Ray Transport in Air-Over-Ground Geometry, ORNL-4289, Vol. II (1968).
11. CONTENTS OF LIBRARY
Included are the referenced documents (a) and a reel of magnetic tape which contains the data library; total records 23,998.
12. DATE OF ABSTRACT
November 1969; revised May 1984.
KEYWORD: MULTIGROUP CROSS SECTIONS