PSR-0233 LSL-M2.

LSL-M2

LSL-M2 adjusts calculated neutron spectra to make the fluence values consistent with given neutron dosimetry measurements. The primary output is a set of values for the best estimates of damage parameter values; the solution is based on a least squares fit of all input data. Several input spectra, possibly from different irradiations, can be processed simultaneously.

In an adjustment procedure, consistency is achieved by adjusting the input data in such a manner that a weighted sum of squares of adjustments is minimized. The weights are assigned according to the input uncertainties, i.e., the larger the uncertainty, the smaller the weight. This sum, which is further modified by correlations, represents the negative logarithm of the probability of the outcome of the experiment if the adjusted values are the "true" data.

The results of the adjustment are valid only if the size of the adjustment does not exceed the input uncertainties. The user should also guard against adjustments that exceed the limitations given by the linearization of the problem.
The number of spectra times the number of energy groups may not exceed 400. The number of dosimetry measurements must not exceed 100.

To compile and link source codes and execute 8 sample problems on an IBM PC required about 2 hours. Compiling LSL-M2 required more than 30 minutes. The AT is, of course, much faster.

The following Table displays the CPU time necessary to run seven out of the eight the test cases on the VAX 6000-510 machine (running OpenVMS V6.1):

AUXILIARY ROUTINES:

ACT: Converts from dosimeter activities to reaction rates.

CALACT: Determines calculated reaction rates from fluences and cross sections.

FLXPRO: Converts fluences, cross sections, and covariances from one group structure to another.

DATA LIBRARIES:

CROSS.XSO: Dosimetry cross section file obtained from IRDF-8 as distributed with the REAL84 exercise.

DAMAGE.XSO: Contains dpa cross sections as given in AST Standard E693-79.

SPVC.XSO: Based on the determination of fluence covariances in the ORR-PSV experiment.

LSLNUC.DAT: Obtained from the Nuclear Data Guide.

• D.E. Cullen and P.K. McLaughlin, "The International Reactor Dosimetry File (IRDF-85)", (April 1985).

• W.L. Zijp, E.M. Zsolnay, and D.E. Cullen, "Information sheet for the REAL84 exercise", Report INDC(NDC)-166 (March 1, 1985).

• R.E. Maerker, J.J. Wagschal, and B.L. Broadhead, "Development and Demonstration of an Advanced Methodology for LWR Dosimetry Applications", EPRI-NP-2188 (1981).

• W.L. Zijp and J.H. Baard, "Nuclear Data Guide for Reactor Neutron   Metrology, Part 1 and Part 2", ECN70/71 (1979).

LSL-M2 is operable on a IBM PC-AT or IBM with fixed disk, an 8087 match coprocessor and 640K memory. It also runs on the VAX family of computers.

IBM Personal Computer Professional Fortran, Version 1.0, is required. The VAX version runs under the VMS operating system, using the VAX FORTRAN compiler.

The code was run at RSIC under PC DOS 3.1. The VAX version was tested on a VAX 6000.

The programs were installed by NEA-DB on a DEC VAX 6000/510 computer.

The source code files for the main program (LSLM2.FOR), and of the three auxiliary programs (ACT.FOR, CALACT.FOR and FLXPRO.FOR) were compiled with the DEC FORTRAN-77 compiler. The executables were run under OpenVMS V6.1.

Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.

Developed by:   Oak Ridge National Laboratory,
                Oak Ridge, Tennessee, USA