NEA-0654 SELFS-3.

1. NAME OR DESIGNATION OF PROGRAM:  SELFS-3

3. DESCRIPTION OF PROBLEM OR FUNCTION

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.

4. 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.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:  620 energy groups.

6. TYPICAL RUNNING TIME

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

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

SELFS reads an original group cross section library made by the program CSTAPE of the SAND II package. The corrected library output by SELF can be used in a SAND II spectrum calculation.
CSTAPE may read a point cross section library created by the program BARSKY from data on the ENDF/B files.

10. REFERENCES

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

- I. 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).

11. MACHINE REQUIREMENTS

One input cross section library tape and one  output corrected cross section tape.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHOR

          Ikuo Kondo
          Reactor Centrum Nederland
          Petten, Netherlands.
          (JAERI, Oarai, Japan)

File name	File description	Records
NEA0654_01.002	SELFS-3 INFORMATION	33
NEA0654_01.003	LIB SOURCE PROGRAM FORTRAN-4	43
NEA0654_01.004	REAL-80A LIBRARY	3655
NEA0654_01.005	SELFS-3 SOURCE PROGRAM FORTRAN-4	381
NEA0654_01.006	QUADR SUBROUTINE FORTRAN-4	205
NEA0654_01.007	DUMMY PLOT ROUTINE	21
NEA0654_01.008	SELFS-3 INPUT FOR TEST CASE	2
NEA0654_01.009	JCL FOR TEST CASE	27
NEA0654_01.010	REAL-80A LIB OUTPUT	3684
NEA0654_01.011	SELFS-3 OUTPUT OF TEST CASE	238