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IAEA0804 TRIFIDO.

TRIFIDO, Decay Constant and Prompt Neutron Calculation from Pulsed Neutron Experiment

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1. NAME OR DESIGNATION OF PROGRAM:  TRIFIDO.
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2. COMPUTERS
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Program name Package id Status Status date
TRIFIDO IAEA0804/01 Tested 01-SEP-1976

Machines used:

Package ID Orig. computer Test computer
IAEA0804/01 IBM 370 series IBM 370 series
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3. NATURE OF PHYSICAL PROBLEM SOLVED

The program calculates decay constants and the population of the fundamental prompt neutron mode  extrapolated to initial time, using pulsed neutron experimental data. This data is the resulting time profile of the neutron density of a subcritical multiplicative assembly which is repetitively pulsed with short bursts of neutrons. The time profile is measured with an appropriate detector and recorded with a time analyser.
With the calculated parameters the program determines the values of  kbeta/l and reactivity by means of the Garelis-Russell method, and reactivities using the Gozani and Sjostrand methods.
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4. METHOD OF SOLUTION

Least-squares weighted fit for the decay constant and extrapolated population calculation. Iteration for the  Garelis-Russell method.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The program is presently restricted to 256 experimental point data (for example those provided by ATMC multichannel analyser). This is adequate for  most pulsed neutron measurements. The restriction can be easily overcome if necessary by changing a DIMENSION card. Minor parameter  adjustments are needed according to the multiplying system used and  to the experimental procedure.
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6. TYPICAL RUNNING TIME

This time depends mainly on the number of cases processed in one run. Table 1 gives typical processor times on an IBM/360-65 computer, operating system OS/360 with MVT, FORTRAN IV G compiler, and on a BULL GE-625 computer, operating system GECOS 3, FORTRAN IV compiler.
                                         Table 1
                                Typical Processor Time
Number of Cases          Processor Time on        Processor Time on               IBM/360-65 (sec)         BULL GE-625 (sec)        in one run   
     1                   2.54                     3.60
     4                   4.78                     7.92
    10                  12.30                    16.92
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7. UNUSUAL FEATURES OF THE PROGRAM

It calculates several pairs of quantities such as the decay constant and the extrapolated population of the fundamental prompt neutron mode as a function of the starting analysis channel (initial time). Since the program selects as fundamental prompt mode those values which provide the best agreement between fitted and experimental data, it can proceed  directly to calculate kbeta/l and reactivity values. Thus all these  kinetic parameters are obtained in just one computer run. In order to provide a visual checking, the program draws a graphic of the experimental data corrected for noise and dead time effects and fitted values.
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8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
IAEA0804/01 01-SEP-1976 Tested at NEADB
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10. REFERENCES

- E. Garelis and J.L.Russell:
  Nucl.Sci.Eng.16, 263(1963).
- T.Gozani:
  EIR-Bericht NR. 79 (April 1965).
- N.G. Sjostrand:
  Ark.Fys. 11, 233 (1957).
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11. MACHINE REQUIREMENTS

10k core on BULL GE-625
                      11k core on IBM/360-65
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
IAEA0804/01 FORTRAN-IV
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13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED:  GECOS 3 on BULL GE-625; OS/360 on IBM/360.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
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15. NAME AND ESTABLISHMENT OF AUTHOR

F. Difilippo and N. Pieroni
                                   CNEA
                                   Departamento de Reactores
                                   Av.Da del Libertador 8250
                                   Buenos Aires (Argentina)
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16. MATERIAL AVAILABLE
IAEA0804/01
File name File description Records
IAEA0804_01.001 SOURCE PROGRAM (F4) EBCDIC 428
IAEA0804_01.002 SAMPLE PROBLEM INPUT DATA 6
IAEA0804_01.003 SAMPLE PROBLEM PRINTED OUTPUT 131
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17. CATEGORIES
  • O. Experimental Data Processing

Keywords: decay, least square fit, neutron spectra, pulsed neutron techniques, reactivity.