RSIC COMPUTER CODE PSR-029
1. NAME AND TITLE
SCANS: Spectra Calculation from Activated Nuclide Sets.
Idaho Nuclear Corporation, Idaho Falls, Idaho.
3. CODING LANGUAGE AND COMPUTER
Fortran IV and Assembler language; IBM 360/75/92
4. NATURE OF PROBLEM SOLVED
SCANS determines the fast (above 1 MeV) and thermal neutron flux levels from Co58 and Co60
disintegration rates, given the irradiation history (operating power level versus time) of the reactor in
which the activities were produced in Ni and Co wires. It processes up to 50 pairs of disintegration
rates per problem; hence, all the data from a pair of irradiated wires monitored at a number of
corresponding positions can be handled.
5. METHOD OF SOLUTION
The flux energy spectrum is first divided into a number of energy groups, as in the customary multigroup formulations in reactor physics. The problem then becomes that of finding the group fluxes. The solution method used in SCANS is based on two assumptions: 1) the energy dependence of the neutron flux at the point of irradiation is independent of the power level, and 2) the irradiation of the samples produces a set of activities to be monitored.
The solution method is applied to the evaluation of the fast (above 1 MeV) and conventional
thermal neutron fluxes, given the activities of Co58 and Co60, respectively, that arise in the irradiation
of Ni58 and Co59 samples. In the application, Ni and Co wires are irradiated in a reactor, removed,
and, after a suitable wait time, monitored at a number of positions along the wires. The pair of
activities measured at each position satisfy the second assumption in that the Co60 activity is virtually
dependent only on the thermal flux while the Co58 activity is a function of both group fluxes.
6. RESTRICTIONS OR LIMITATIONS
The method, in its present form, is a "fully determined" one (there must be as many given activities as there are flux groups to be determined). This may restrict its use to cases of relatively small numbers of flux groups and accordingly crude spectra.
Each group flux determined can be a function of no other fluxes than those already determined.
However, this guarantees an exact solution for the set of group fluxes with one sweep through the set.
7. TYPICAL RUNNING TIME
No study has been made by RSIC of typical running times for SCANS.
8. COMPUTER HARDWARE REQUIREMENTS
SCANS is operable on the IBM 360/75/91 computer.
9. COMPUTER SOFTWARE REQUIREMENTS
A Fortran IV compiler is required. Compile using OPT=2.
M. H. Putnam and G. E. Putnam, "SCANS: Spectra Calculation from Activated Nuclide Sets," IN-1446 (November 1970).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code and sample problem input and output.
12. DATE OF ABSTRACT
KEYWORD: ACTIVATION SPECTRA