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IAEA0826 SHOVAV.

SHOVAV, Space-Dependent and Time-Dependent Neutron Diffusion with Temperature Feedback in Slab Geometry

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1. NAME OR DESIGNATION OF PROGRAM:  SHOVAV.
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2. COMPUTERS
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Program name Package id Status Status date
SHOVAV IAEA0826/01 Tested 01-DEC-1976

Machines used:

Package ID Orig. computer Test computer
IAEA0826/01 IBM 370 series IBM 370 series
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3. NATURE OF PHYSICAL PROBLEM SOLVED

The space and time-dependent neutron diffusion equation is solved in slab geometry for four energy groups and six groups of delayed neutrons. The core thermodynamic equations are also solved at each mesh point for average temperatures of fuel and coolant to provide a temperature feedback for the kinetic calculations.
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4. METHOD OF SOLUTION

The Gauss-Seidel method is used for the static part of the solution of the diffusion equation. For the dynamic part, the optimal source projection method is used (3). This method  uses a polynomial or exponential approximation to predict the fission source at each mesh point for the next time step. The degree of the polynomial is optimized so as to maximize the time step size  and minimize the number of iterations. Temperature feedback is provided by recalculating cross sections using the appropriate temperature dependent shielding factors.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

100 mesh points (can easily be extended).
  4 energy groups
10 isotopes-materials (6 of them can be fissile isotopes)
11 regions with different material composition
  6 groups of delayed neutrons for each fissile isotopeS
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6. TYPICAL RUNNING TIME

The running time is strongly dependent on the transient calculated, the number of mesh points, and the error criteria set by the user. Typically, 15 to 20 time steps are calculated per second on the IBM 370/195 for a 50 mesh point problem.
A 20 second transient resulting in a 200 percent power increase required 675 time steps with an error criteria of 10**(-6) and took  39.2 seconds of CPU time. A 2 millisecond transient resulting in a 170 percent power increase required 139 time steps with an error criteria of 10**(-6) and took 10 seconds of CPU time.
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7. UNUSUAL FEATURES OF THE PROGRAM

The optimal source projection method reduces required computer time by one to two orders of magnitude as compared to ordinary relaxation methods.
Six groups of delayed neutron data lambda-i and beta-i can be inserted for each fissile isotope.
Delayed neutron spectra for six delayed groups and four energy groups can be inserted.
Material group cross sections or regional group cross sections can be used for input data.
Mixing and shielding factors are used to calculate temperature dependent cross sections for temperature feedback.
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8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
IAEA0826/01 01-DEC-1976 Tested at NEADB
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10. REFERENCES

- D. Saphier, S. Yiftah:
  A Program to Solve the Few Group Space Time Dependent Diffusion Equation with Temperature Feedback.
  Israel Atomic Energy Commission IA 1217 (1971).
- D. Saphier:
  Source Projection Method to Accelerate Reactor Dynamic Calculations.
  Trans. Am. Nucl. Soc. 15, 2 (1972) 792.
- D. Saphier:
  An Optimal Source Projection Method to Accelerate Space Time Dependent Calculations.
  Trans. Am. Nucl. Soc. 16, 1 (1973) 300.
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11. MACHINE REQUIREMENTS

The amount of storage in k-bytes, N, is given approximately by - N=A+IP(B+0.125*IMAX), where A is 100, B is 10, IMAX is the number of meshpoints, and IP is 4 or 8 for single or double precision calculations, respectively. For a 65 meshpoints problem, executed in double precision, 245k bytes of storage should be allocated.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
IAEA0826/01 FORTRAN-IV
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13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

IBM 360 OS level 21.7 with FORTRAN H or G. Usually automatic double precision of FORTRAN H is used.
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14. ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

If plotting (option) is required, the user must supply his own plotting routine.
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15. NAME AND ESTABLISHMENT OF AUTHOR

David Saphier
Argonne National Laboratory
Building 308
Argonne, Ill 60439
USA.

- or

Soreq Nuclear Research Center
Yavneh
Israel.
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16. MATERIAL AVAILABLE
IAEA0826/01
File name File description Records
IAEA0826_01.001 PROGRAM SOURCE - FORTRAN IV 3550
IAEA0826_01.002 SAMPLE PROBLEM DATA 328
IAEA0826_01.003 SAMPLE PROBLEM OUTPUT 1688
IAEA0826_01.004 OVERLAY STRUCTURE 10
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17. CATEGORIES
  • F. Space - Time Kinetics, Coupled Neutronics - Hydrodynamics - Thermodynamics

Keywords: excursions, feedback, few-group, kinetics, neutron diffusion equation, slabs, space-time, thermodynamics.