1. NAME AND TITLE
GLUCS: A Generalized Least-Squares Code System for Updating Cross Section Evaluations
with Correlated Data Sets.
INPUT: Reads evaluated nuclear data files, selects appropriate material and puts it into a form that GLUCS can read.
OUTPUT: Writes output data from GLUCS and INPUT programs in ENDF/B-V format to
PDP-10 disk files.
Oak Ridge National Laboratory, Oak Ridge, Tennessee.
3. CODING LANGUAGE AND COMPUTER
Fortran IV; PDP-10 or VAX.
4. NATURE OF PROBLEM SOLVED
GLUCS is a generalized least-squares code system for updating cross section evaluations with
correlated data sets. Simultaneous evaluation of cross sections is required where ratio data exist. Since
ratio measurements do not require absolute neutron flux determination, which is usually the largest
source of uncertainties, correct use of ratio data could establish the relative magnitudes of various
cross sections quite well. High-precision absolute data for one reaction would improve the absolute
magnitudes of all other cross sections connected by high-precision ratios. The idea is to combine the
new set of measurements with the evaluation, which is assumed to represent older data.
5. METHOD OF SOLUTION
This code system includes the PDP-10 Fortran IV computer programs INPUT.F4, GLUCS.F4 and
OUTPUT.F4, which employ generalized least-squares for simultaneous evaluation of reaction cross
sections. Evaluations of cross sections and covariances are used as input for incorporating correlated
data sets, particularly ratios. These data are read from Evaluated Nuclear Data File (ENDF/B-V)
formatted files. Measured data sets, including ratios and absolute and relative cross section data, are
read and combined with the input evaluations via the least-squares technique. The resulting output
evaluations have not only updated cross sections and covariances, but also cross-reaction covariances.
These output data are written into ENDF/B-V format.
6. RESTRICTIONS OR LIMITATIONS
The code is general in that it is capable of handling large numbers of correlated evaluations, a variety of data types that may be correlated, and the most commonly used ENDF/B-V covariance formats and interpolation laws. However, the user should make note of the following restrictions:
a) the new data cannot be correlated to the old evaluation,
b) there are specific classes of ratio data allowed,
c) no significant energy uncertainty is allowed,
d) there are no energy resolution problems,
e) specific ENDF/B-V interpolation laws are used,
f) only "NI-type" sub-subsections in file 33 of the ENDF/B-V data can be used to compute the
covariance matrix; "NC-type" sub-subsections are not allowed implying that NC in file 33 must
be equal to 0.
7. TYPICAL RUNNING TIME
Each sample problem involves three runs and required the following running times (in min:sec cpu)
on the ORELA PDP-10:
Problem #1 Problem #2
INPUT 0:27 cpu 1:30 cpu
GLUCS 0:18 1:41
OUTPUT 0:12 0:33
8. COMPUTER HARDWARE REQUIREMENTS
GLUCS runs on the DEC PDP-10 and, with minor modifications, has been successfully
implemented on the CDC 7600 computer at Los Alamos Scientific Laboratory and on VAX computers
9. COMPUTER SOFTWARE REQUIREMENTS
A Fortran IV compiler is required.
a. Included in the documentation:
D. M. Hetrick, C. Y. Fu, "GLUCS: A Generalized Least-Squares Program for Updating Cross
Section Evaluations with Correlated Data Sets," ORNL/TM-7341, ENDF-303, (1980).
b. Background information:
J. B. Dragt, J. W. M. Dekker, H. Gruppelaar, and A. J. Janssen, "Methods of Adjustment and Error Evaluation of Neutron Capture Cross Sections; Application to Fission Product Nuclides," Nucl. Sci. & Eng., Vol. 62 (1977) p. 117.
F. G. Perey, "Spectrum Unfolding by the Least-Squares Method," Proceedings IAEA Technical Committee Meeting on Current Status of Neutron Spectrum Unfolding, Oak Ridge, Tennessee (October 1977).
R. Kinsey, "Data Formats and Procedures for the Evaluated Nuclear Data File," ENDF, BNL-NCS-50496 (ENDF-102) 2nd Edition (ENDF/B-V) (1979).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the
source code and sample problem input and output.
12. DATE OF ABSTRACT
August, 1982; revised October 1983; approved August 1984, revised December 1988.
KEYWORDS: COVARIANCE DATA PROCESSING; ENDF FORMAT; ENDF/B-V; NEUTRON CROSS SECTION PROCESSING