1. NAME AND TITLE OF DATA RETRIEVAL PROGRAM

COVFILS: A 30-Group Covariance Library Based on ENDF/B-V.

2. NAME AND TITLE OF DATA RETRIEVAL PROGRAM

COVARD: Covariance Reader.

3. CONTRIBUTOR

Los Alamos National Laboratory, Los Alamos, New Mexico.

4. HISTORICAL BACKGROUND AND INFORMATION

COVFILS stands for "covariance files." The library, designed for use in sensitivity studies, was prepared from ENDF/B-V data with the NJOY code system. The selection of the contents of the library was based on a report from Los Alamos National Laboratory.

5. APPLICATION OF THE DATA

COVFILS contains neutron cross sections, and their uncertainties and correlations, in multigroup form. These data can be used, in conjunction with sensitivity information, to estimate the data-related uncertainty in calculated integral quantities such as radiation-damage or heating. COVFILS is a standard input file for the Los Alamos sensitivity code SENSIT and, with suitable format conversion, can be used with other sensitivity systems as well.

6. SOURCE AND SCOPE OF DATA

COVFILS was obtained by processing evaluations from ENDF/B-V with the ERRORR module of the NJOY nuclear data processing system (LA-9303-M, Vol. I). The group structure is the Los Alamos 30-group structure which is listed in "File 1" of each multigroup data set in the library. The elements included are:

¹H, ¹⁰B, C, ¹⁶O, Cr, Fe, Ni, Cu, Pb.

The data for Cu were obtained by combining the ENDF/B-V cross sections for Cu with the ENDF/B-V relative covariances for Fe.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAMS

A short retrieval program, COVARD, and the results of a sample execution of the program are included in the package. COVARD reads the multigroup cross-section and covariance data in the condensed ENDF-like format of COVILS and transforms the data into engineering format (with zeros present explicitly and groups reordered to the conventional high-to-low order). This version of COVARD retrieves and prints the cross sections and the covariance matrix for a single "wired-in" reaction pair. The output resulting from executing COVARD, as written with no input required, is included in the code package.

8. DATA FORMAT AND COMPUTER

EBCDIC card images; IBM 360/370.

9. TYPICAL RUNNING TIME

COVARD running time, for retrieving the data for any single reaction pair, is less than 3 seconds on a CDC-7600.

10. REFERENCES

Included in document:

D. W. Muir and R. J. LaBauve, "COVFILS, A 30-Group Covariance Library based on ENDF/B-V," LA-8733-MS (March 1981).

Background information:

R. E. MacFarlane, D. W. Muir, and R. M. Boicourt, "The NJOY Nuclear Data Processing System, Vol. I: User's Manual," LA-9303-M (1982).

S. A. W. Gerstl, "SENSIT: A Cross-Section and Design Sensitivity and Uncertainty Analysis Code," LA-8498-MS (August 1980).

11. CONTENTS OF LIBRARY

Included are the referenced documents and one (1.2MB) DOS diskette which contains the COVARD source file and the COVFILS data library and sample JCL, plus output from COVFILS using COVARD.

12. DATE OF ABSTRACT

April 1985.