1. NAME AND TITLE OF DATA LIBRARY

NAB: 100-Group, P₃, Neutron Cross Section Data for Sodium and Aluminum.

2. NAME AND TITLE OF DATA RETRIEVAL PROGRAM

LIBGEN: Library Generation Routine to Produce Unformatted Cross-Section Tape for Input to ANISN.

3. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

4. HISTORICAL BACKGROUND AND INFORMATION

The cross-section data were compiled at ORNL to be used for studies of neutron transport through sodium, particularly in conjunction with the calculations with the CCC-127/MORSE Monte Carlo code of the ORNL-LMFBR Sodium Benchmark Experiment. This experimental program involves the measurements of neutron transport through up to fifteen feet of sodium. The NAB data were judged to be satisfactory for most practical applications to problems involving deep penetration of neutrons.

5. APPLICATION OF THE DATA

DLC-18/NAB is suitable for multigroup neutron transport calculations in sodium or sodium contained in aluminum tanks such as the ORNL-LMFBR Sodium Benchmark Experiment. The retrieval program manipulates such that it can be used in codes such as CCC-82/ANISN, CCC-89/DOT, and CCC-127/MORSE.

6. SOURCE AND SCOPE OF THE DATA

The 100 neutron group data were produced by PSR-13/SUPERTOG using a "1/E" weighting spectrum for non-thermal energies. The energy group structure is that used for GAM-II which covers the energy range from 14.92 MeV to thermal. The thermal group cross sections were determined by assuming a Maxwellian weighting function and a constant scattering cross section and a "1/v" absorption cross section.

This data represents a P₃ Legendre expansion approximation for neutron elastic scattering. inelastic neutron scattering was treated as isotropic in the lab system.

The multigroup cross sections were generated from a preliminary version of the ENDF/B-III MAT 1156 sodium and MAT 1135 aluminum. Subsequent changes to the evaluated data prior to its official release as part of ENDF/B Version III would affect the data in DLC-18/NAB somewhat, but probably not significantly.

Because the materials used in the experient were not free from impurities, these were included as follows:

Calcium 400 ppm

Oxygen 200 ppm

Potassium 150 pm

Hydrogen 50 ppm.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM

LIBGEN is a modified version of the Library Generation Routine which is available in the CCC-82/ANISN code package. This version will read data from a card image tape, the mode by which NAB is distributed, and write an unformatted tape for direct use with ANISN.

8. DATA FORMAT COMPUTER

BCD/EBCDIC card images; IBM 360/370.

9. TYPICAL RUNNING TIME

On the IBM 360/91 computer, it required 15 seconds to read the NAB data from a card image tape and rewrite it on an unformatted tape.

10. REFERENCES

F. R. Mynatt, M. J. Gritzner, R. E. Maerker, and B. J. McGregor, "Fast Reactor Shielding Monthly Progress Report for March 1972, 189a No. 10028, Activity No. 40 01 61," ORNL-TM-3800 (May 1972) 30-35.

L. R. Williams, "Input Description for LIBGEN," Informal note (1972).

11. CONTENTS OF LIBRARY

Included are the referenced documents and one (1.2MB) DOS diskette which contains the cross section data, the source code and sample problem input and output.

12. DATE OF ABSTRACT

August 1972; reviewed May 1984.