RSICC CODE PACKAGE PSR-499

1. NAME AND TITLE

GAPCON-THERMAL3: Code System to Calculate Fuel Steady State and Transient Behavior.

2. CONTRIBUTORS

Pacific Northwest Laboratories, Richland, Washington, through the Energy, Science and Technology Software Center in Oak Ridge, Tennessee, and the OECD NEA Data Bank, Issy-les-Moulineaux, France.

3. CODING LANGUAGE AND COMPUTER

Fortran-IV; CDC 7600 (P00499/C7600/00).

4. NATURE OF PROBLEM SOLVED

GAPCON-THERMAL3 calculates the thermal and mechanical behavior of the fuel and cladding in a nuclear fuel rod during normal operation for both steady-state and operational transients.

5. METHOD OF SOLUTION

The radial temperature profile is obtained by orthogonal collocation. Stresses and strains are determined by using chained iterative radial and axial finite element models. Fission gas release and gap conductance are calculated from empirical models. The solution iterates to convergence on the gap conductance for each axial node and subsequently on gas release rate for the fuel rod. Additional iterative loops handle plasticity, creep, and nonlinear structural effects due to gap closure.

6. RESTRICTIONS OR LIMITATIONS

Modeling is axisymmetric for the thermal and mechanical calculations. The current model does not compute the strain at pellet-pellet interfaces. As many as 17 variable-length axial regions can be modeled with no limitation on the number of fuel and cladding radial nodes. No more than 49 time-steps greater than or equal to 1-day duration are allowed.

7. TYPICAL RUNNING TIME

Three to 30 seconds per time-step are required on the CDC6600.

8. COMPUTER HARDWARE REQUIREMENTS

A CDC machine is required. About 220K of addressable storage is needed for execution of a typical problem.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran-IV compiler and either SCOPE 2.1 (CDC 7600) or SCOPE 3.4 (CDC 6600) operating system are required for program compilation. This program was not tested at RSICC.

10. REFERENCES

a) included in documentation

D. D. Lanning, C. L. Mohr, F. E. Panisko, and K. B. Stewart, "Gapcon-Thermal-3 Code Description," PNL-2434 (January 1978).

b) background information

D. D. Lanning, F. E. Panisko, and C. L. Mohr, "Verification of the GAPCON-THERMAL-3 Computer Code," PNL-2435 (September 1978).

11. CONTENTS OF CODE PACKAGE

The package includes the referenced document in (10.a) and one DS/HD diskette with the Fortran source files and a test case written in a self-extracting compressed DOS file. Executables are not included with the package.

12. DATE OF ABSTRACT

January 2001.

KEYWORDS: HEAT TRANSFER; NUCLEAR SAFETY; STRESS ANALYSIS