1. NAME AND TITLE

RFSP-JUL: Unfolding Code System for Neutron Spectra Evaluation from Activation Data.

RFSP-JUL is a revised and improved version of an earlier RFSP[INDC(HUN)-8/U] code and CCC-108/SPECTRA.

2. CONTRIBUTOR

Kernforschungsanlage Jülich GmbH, Jülich, Federal Republic of Germany.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360/370.

4. NATURE OF PROBLEM SOLVED

RFSP-JUL calculates the spectral neutron flux density from activation data, guess spectra and cross section data.

5. METHOD OF SOLUTION

RFSP-JUL is based on the mathematical method used in the RFSP program and represents its developed and more flexible version. The unfolding problem is solved by a step-by-step method starting from a guess spectrum given by the user or chosen by the program from a guess spectrum library. A multiplier constant is used to increase the speed of convergence; it enables the user to achieve a solution in one or two iteration steps.

The measured activities, cross sections, and guess spectra are provided as input; or, as stated above, the guess spectra may be chosen by the program from a guess spectrum library, as well.

6. RESTRICTIONS OR LIMITATIONS

Number of flux points used in calculations m < 100

Number of detectors n < 30

Number of cross section points m' < 2000

(the energy point structure and the number of energy points may be different for different detectors)

Number of flux points for each of the spectra in the guess spectrum library m'' < 624

7. TYPICAL RUNNING TIME

The running time depends mainly upon the number of energy points; it is nearly independent of the number of detectors. The running time for a problem with 10 activity detectors and 100 energy points was found to be about 30 sec.

8. COMPUTER HARDWARE REQUIREMENTS

RFSP-JUL is operable on the IBM 360/370 computers. It executes with 265 K bytes of memory. It requires 2 tapes or discs for the cross section library and guess spectrum library and a third tape or disc for compilation of or changes in the cross section library. The output can be obtained on a lineprinter, cards and a CALCOMP plotter.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

A. Fischer, "RFSP-JUL: A Programme for Unfolding Neutron Spectra from Activation Data,JUL-1475 (December 1977).

A. Fischer, "The Petten Version of the RFSP-JUL Program: Description and User's Manual," R.M.G. Note 76/10 (April 1976).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source code input, plus cross sections and guess spectra.

12. DATE OF ABSTRACT

March 1984.