RSICC CODE PACKAGE PSR-551

 

 

1.  NAME AND TITLE

                        SELFS-3:  Self-Shielding Correlation of Foil Activation Neutron Spectra Analysis by SAND-II

           

2.  CONTRIBUTORS

            Energy Research Foundation (ECN), formerly known as Reactor Centrum Nederland, Petten, The Netherlands, through the OECD NEA Data Bank, Issy-les-Moulineaux, France.

 

3.  CODING LANGUAGE AND COMPUTER

                        Fortran IV; CDC 7600 SCOPE 2.1 (RSICC ID: P00551C660000).

                        NEADB package identifier is NEA-0654/01.

 

4.  NATURE OF PROBLEM SOLVED

SELFS-3 corrects for the influence of the self-shielding effect in neutron spectrum determinations by means of the multifoil activation method. It is used in combination with the SAND-II program for unfolding the responses of an irradiated set of activation detectors in 620 groups. The program SELFS can calculate a corrected 620 group cross section data set for specified reactions used in the SAND-II library, and for specified foil thicknesses. This procedure requires no additional assumption on the shape of the neutron spectrum and on other experimental conditions, but only some foil characteristics (reaction type, material composition, foil thickness). Application of this procedure is possible when multigroup unfolding programs are used with suitably small energy intervals. This code system was developed in the 1970’s at Reactor Centrum Nederland, Petten, The Netherlands, and was contributed to RSICC through the NEA Data Bank. No changes were made to the package when it was released by RSICC in 2008. Modifications will be required to run SELFS-3 on current computer systems.

                        .

5.  METHOD OF SOLUTION

The following assumptions are made:

-  the neutron flux is isotropic

-  no multiple interactions

-  scattering reactions neglected

-  foil may be considered as a plane slab

- flux depression outside foil is much less than self-shielding in the foil

Under these assumptions the basic equation for the neutron self- shielding effect may be simplified, and the resulting equation used to produce group cross sections corrected for the self-shielding effect in the foil detector. The Gauss-Legendre method is used in the integration.

 

6.  RESTRICTIONS OR LIMITATIONS

                        The energy group limit is 620.

 

7.  TYPICAL RUNNING TIME

                  For 620 self-shielding factors, when the integration convergence condition is 0.001, the CPU time was a little over 1 second on the CDC 6600.

 

8.  COMPUTER HARDWARE REQUIREMENTS

                        SELFS-3 ran on CDC 7000 computers.

 

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran compiler is required; no executables are included in the package. SELFS-3 was developed on a CDC 7600 computer running SCOPE 2.1 operating system with the FTN 4.8 + 538 compilers. It has not been ported to other computers and was not tested at RSICC.

 

10. REFERENCES

            10a included with the package:

            Ikuo Kondo, "SELFS, A Program for Determining Self-Shielding Corrections for Foil Detectors," RCN-74-105 (August 10, 1974).

            A.M. Barsky, H.J. Nolthenius,  "Neutron Selfshielding of Activation Detectors Using Total Cross-Section Values from the ENDF/B-IV Library," RCN-75-156 (November 1975).

            H.J. Nolthenius, R.J.M. Kok and W.L. Zijp:  "Cross Section Library REAL80A" (in the 620 Groups SAND-II Format), ECN-81-013 (January 1981).

            10b background reference:

W.N. McElroy et al, "RSIC Computer Code Collection CCC-112, SAND II Neutron Flux Spectra Determination by Multiple Foil Activation Iterative Method" AFWL-TR-67-41 (1967).

 

11. CONTENTS OF CODE PACKAGE

                        The package is transmitted on one CD in a compressed Winzip file which contains the references listed above in Section 10.a, source code, and input sample data.

 

12. DATE OF ABSTRACT

                        October 2008.

 

KEYWORDS:

ACTIVATION SPECTRA ANALYSIS; CROSS-SECTION PROCESSING; NEUTRON; SELF-SHEILDING