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PSR-0363 FRANCO.

FRANCO, Finite Element Method (FEM) Fuel Rod Analysis for Solid and Annular Configurations

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1. NAME OR DESIGNATION OF PROGRAM:  FRANCO.
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2. COMPUTERS
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Program name Package id Status Status date
FRANCO PSR-0363/01 Tested 24-NOV-2000

Machines used:

Package ID Orig. computer Test computer
PSR-0363/01 Many Computers PC Pentium III 500,Linux-based PC,IBM RISC6000 WS
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3. DESCRIPTION OF PROGRAM OR FUNCTION

The FRANCO code is a quasi- static two-dimensional fuel rod analysis code, that calculates the fuel temperature and material deformation as a function of heat generation rate. Both solid and annular fuel configurations are modeled.
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4. METHOD OF SOLUTION

FRANCO uses two-dimensional finite element theory and applications for mechanical deformation and heat conduction, and determines the temperature distribution from the fuel center to the coolant adjacent to the clad at a position along  the fuel rod axis. FRANCO calculates the average temperature of each radial division, the nodal displacement, and strain and stress within the fuel pellet and clad. The principal stresses, which represent maximum and minimum stresses within an element, result from Mohr's circle relationship between normal stresses. FRANCO is capable of predicting the thermo-mechanical behavior in the radial direction of a single fuel rod for both boiling water reactors (BWR's) and pressurized water reactors (PWR's). The cross sectional  plane geometry of fuel rod is modeled using three-node constant strain triangular finite elements, and both thermal and mechanical solutions are computed with the same finite element configurations.  The local linear heat generation rate is modeled as a uniform heat source in a fuel pellet, and the coolant temperature and heat transfer coefficient are applied as known boundary conditions at the boundary of the cladding surface. The total load to form the global  force vector consists of the thermal load that results from thermal  expansion of the material and the mechanical load exerted by pressure. FRANCO assumes the fuel-cladding gap region to be conductive material in order to simplify the analysis, and this gap  is simulated by either an open gap or a closed gap model. A time- dependent problem can be simulated by FRANCO using quasi-static analysis when time-dependent parameters are provided. FRANCO can treat a steady-state or mild transient condition as a time-dependent problem, where time-dependent parameters are input as "snap shots".  Consequently, the FRANCO code is able to run faster and easier compared to other industrial codes with comparable results; and hence, FRANCO is useful in analyzing the fuel element performance as a first cut or scoping tool.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

FRANCO analyses only a quarter of fuel rod cross-sectional area because azimuthal symmetric geometry is assumed for fuel pellet, gap, and clad. Fuel densification, swelling, and relocation are not considered in FRANCO, but a fuel relocation model can be considered by making an assumption about the reduced gap size. A smaller gap size rather than as-manufactured gap size were used in some of the FRANCO benchmark problems to account for the effect of fuel relocation. FRANCO models the elastic deformation of fuel and cladding, but not  plastic deformation. Gas thermal conductivity is used as a material  property input because the gap region is assumed to be a conductive  material like the fuel and clad. FRANCO handles steady-state conditions and mild transient power changes.
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6. TYPICAL RUNNING TIME:  A few seconds on Pentium III machines.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS:
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9. STATUS
Package ID Status date Status
PSR-0363/01 24-NOV-2000 Tested at NEADB
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10. REFERENCES

- M.A. Feltus and K. Lee:
  Evaluation of the FRANCO Finite Element Fuel Rod Analysis Code
  Ann. Nucl. Energy 23, No. 7, pp. 553-565 (1996)
PSR-0363/01, included references:
- Kwangho Lee:
  Evaluation of the Finite Element Fuel Rod Analysis Code (FRANCO)
  Penn State University Master Thesis (December 1994)
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11. MACHINE REQUIREMENTS

FRANCO runs on IBM personal computers and mainframe. It also runs on IBM RS/6000 and Sun workstations.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
PSR-0363/01 FORTRAN-77
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

FRANCO has been compiled using Lahey Fortran 95 and MS DVF under DOS/Windows 98; with g77 under Red Hat 6.1 Linux; with xlf under aix 3.4 on IBM RS/6000.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHORS

Contributed by:
                Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.

Developed by:
                Penn State University
                University Park
                Pennsylvania
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16. MATERIAL AVAILABLE
PSR-0363/01
README.RSI Information file
FRANCO.EXE Compressed executable file
363MNYCP.00 Listing of files
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17. CATEGORIES
  • I. Deformation and Stress Distributions, Structural Analysis and Engineering Design Studies

Keywords: deformation, fuel elements, fuel rods, heat conduction.