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NEA-0434 ISOTEX-1.

ISOTEX-1, Time-Dependent Heavy Isotope and Fission Products Concentration in U Reactor or Pu Reactor

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1. NAME OR DESIGNATION OF PROGRAM:  ISOTEX-1.
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2. COMPUTERS
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Program name Package id Status Status date
ISOTEX-1 NEA-0434/01 Tested 01-MAR-1976

Machines used:

Package ID Orig. computer Test computer
NEA-0434/01 IBM 370 series IBM 370 series
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3. NATURE OF PHYSICAL PROBLEM SOLVED

The code ISOTEX-1 is a one-group neutron code which computes in double precision the time-dependent concentrations of 82 isotopes produced in an uranium and/or plutonium reactor. The U-235 depletion, the fuel depletion, and the burnup are also computed.
The isotopes form five chains:
- 17 isotopes ranging from U-234 to Am-242
-  7 isotopes with mass numbers between 81 and 86
-  1 isotope with mass number 106
- 19 isotopes with mass numbers 129-137
- 38 isotopes with mass numbers 140-155.
Most of these isotopes have half-lives greater than one day.
The value of the neutron flux, the cross sections (capture and fission) and the ratios of activation cross sections may be changed after each time step.
The concentrations and ratios of concentrations may be printed during the irradiation.
28 different units may be used for the printing of the results. The ratios of concentrations may be chosen among a list of 41 ratios built into the code or may be defined by the user as ratios of sums or of products of concentrations.
Several different problems may be treated.
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4. METHOD OF SOLUTION

The analytical solution of the system of 82 differential equations describing the isotope transmutation schemes  provides the values of the concentrations by assuming that the parameters entering the equations are kept constant during each time step and that there is no interaction between the isotopes.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

There seems to be no  upper limit in the range of applicability when high values of the fluxes and/or large time steps are used. A lower limit would probably correspond to the case of an irradiation time of the order  of one hour in a flux of the order of 10**10 n/cm**2*sec.
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6. TYPICAL RUNNING TIME
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7. UNUSUAL FEATURES OF THE PROGRAM

A complete set of data (fission energy, decay constants, yields, branching ratios) is provided together with a library of thermal cross sections (fission, capture  and ratios of activation cross sections). The user need only, for a  given problem, specify the values which should be modified in this set of data, or in the set of data which has been used for the previous problem.
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8. RELATED OR AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
NEA-0434/01 01-MAR-1976 Tested at NEADB
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10. REFERENCES

- Alain Sola, "ISOTEX-1, code de calcul de concentrations isotopiques et de rapports de concentrations.' EUR 5111.F (1974)
NEA-0434/01, included references:
- Alain Sola, "ISOTEX, code de calcul de concentrations isotopiques et de
rapports de concentrations."  EUR 5048.f (1974)
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11. HARDWARE REQUIREMENTS
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-0434/01 FORTRAN-IV
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13. SOFTWARE REQUIREMENTS
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
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15. NAME AND ESTABLISHMENT OF AUTHOR

Joint Research Centre EURATOM
Ispra Establishment
Ispra, Italy.
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16. MATERIAL AVAILABLE
NEA-0434/01
File name File description Records
NEA0434_01.001 SOURCE PROGRAM (F4) 2816
NEA0434_01.002 OVERLAY CARDS 4
NEA0434_01.003 SAMPLE PROBLEM INPUT DATA 62
NEA0434_01.004 SAMPLE PROBLEM PRINTED OUTPUT 2367
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17. CATEGORIES
  • D. Depletion, Fuel Management, Cost Analysis, and Power Plant Economics

Keywords: burnup, cross sections, daughter products, depletion, fission products, isotope production, isotopes, neutron flux, one-group theory, radioisotopes.