1. NAME AND TITLE OF DATA LIBRARY

GARLIB: Multigroup Resonance-Region Cross Sections for Use in Shielding Calculations.

2. NAME AND TITLE OF DATA RETRIEVAL PROGRAMS

GARW: A Program to Manipulate GAROL Resonance Cross Sections for Fully Dense Natural Tungsten.

GARU: A Program to Manipulate GAROL Resonance Cross Sections for Fully Dense Depleted Uranium.

3. CONTRIBUTOR

National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio.

4. HISTORICAL BACKGROUND AND INFORMATION

The GARLIB data is produced by PSR-33/GAROL. Because other libraries of updated input data (i.e., resonance parameters and optimum energy point distributions) are required for PSR-33/GAROL, and the code is not widely used, the GARLIB data were generated for use by those designing space power reactor shields.

5. APPLICATION OF THE DATA

The 32-group, 0.4 to 1234 eV, capture and scattering cross sections contained in the library may be used as is for multigroup neutron transport calculations for the tabulated thicknesses of resonance absorber slabs (or cylindrical or spherical shells of the same thickness). They must, of course, be merged with a high energy (1 keV to 15 MeV) cross section set as calculated by GAM-II, for example. If the slab is not of the thickness listed, interpolated values may be used. Extrapolation, especially to thinner absorbers, is not advised because of the rapidly rising average cross sections. Total capture rates in the absorber will be preserved when these cross sections are used.

It is often inconvenient to perform a neutron transport calculation with the 32 energy groups in the 0.4 to 1234 eV region. For this reason, the relative group fluxes which were calculated by GAROL are also contained in the library to permit group collapsing. This group collapsing may be done by hand calculations or with the retrieval programs included with the data library.

6. SOURCE AND SCOPE OF DATA

Multigroup capture and scatter cross sections for the resolved resonance region were calculated for tungsten and depleted uranium slabs. The computer code used to generate the cross sections, PSR-33/GAROL, was previously observed to preserve the total capture rate in detailed multigroup neutron transport calculations. The cross sections are intended for use in shielding calculations of neutron transport and capture distribution in slabs or cylindrical or spherical shells of thick resonance absorbers.

Capture and scatter cross sections were obtained for fully dense tungsten and depleted uranium slabs of thickness 1, 2, 2.54, 4, and 8 centimeters; the slabs were surrounded by either hydrogen or lithium hydride. Group cross sections were calculated for a group split of 0.25 lethargy units extending from 0.414 to 1234.1 eV. This group structure is identical to that of the last 32 groups in the GAM-II 99-group structure; thus, the presently reported group cross section sets may be readily merged with the 1 keV to 15 MeV cross section data of GAM-II. All cross sections are microscopic and in units of barns. Because it may not be generally convenient to run with 32 energy groups in the 1 eV to 1 keV region, the group fluxes which were calculated with PSR-33/GAROL are also presented; further group collapsing either by hand calculations or with included computer codes is thus permitted.

Cross sections are included for:

¹⁸⁰W, ¹⁸²W, ¹⁸³W, ¹⁸⁴W, ¹⁸⁶W, ²³⁵U and ²³⁸U.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAMS

retrieval programs read multigroup region-averaged fluxes, capture cross sections, and scattering cross sections calculated and punched out by PSR-33/GAROL. Separate codes are included for the tungsten and uranium cases. The codes, when executed, will print out the information presented in the packaged documentation. The final section of each code outlines a procedure for further group-collapsing the cross sections.

The first code, GARW, manipulates isotopic tungsten cross sections. Tungsten is fully dense and isotope fractions are those occurring naturally. The second code, GARU, manipulates cross sections of uranium-238 and uranium-235 as calculated for fully dense depleted uranium (0.2% uranium-235).

Versions of the library and retrieval programs are available for both the IBM 7090 and the IBM 360/370 computers.

8. DATA FORMAT AND COMPUTER

BCD/EBCDIC card images; IBM 7090 (A) or IBM 360/370 (B).

9. TYPICAL RUNNING TIME

It takes approximately 1 minute to run either GARU or GARW on the IBM 7090 computer. On the IBM 360/91 computer, GARW runs in approximately 21 seconds and GARU in 18 seconds.

10. REFERENCE

G. P. Lahti and R. M. Westfall, "Multigroup Resonance-Region Cross Sections for Tungsten and Depleted Uranium for Use in Shielding Calculations," NASA TM X-1909 (January 1970).

11. CONTENTS OF LIBRARY

Included are the referenced document and one tape cartridge in TAR format which contains the source codes for the retrieval programs and the data libraries, plus output from the sample edits of the data libraries.

12. DATE OF ABSTRACT

July 1970; reviewed May 1984.