RSICC CODE PACKAGE PSR-483

1. NAME AND TITLE

GT2R2: Code System to Calculate Fuel Rod Thermal Performance.

2. CONTRIBUTOR

Pacific Northwest Laboratory, Richland, Washington, through the Energy Science Technology Software Center, Oak Ridge, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran 77; CDC and DEC Vax (P00483ALLMF00).

4. NATURE OF PROBLEM SOLVED

GT2R2 is Revision 2 of GAPCON-THERMAL-2 and is used to calculate the thermal behavior of a nuclear fuel rod during normal steady-state operation. The program was developed as a tool for estimating fuel-cladding gap conductances and fuel-stored energy. Models used include power history, fission gas generation and release, fuel relocation and densification, and fuel-cladding gap conductance. The gas release and relocation models can be used to make either best-estimate or conservative predictions. The code is used by the United States Nuclear Regulatory Commission for audit calculations of nuclear fuel thermal performance computer codes.

5. METHOD OF SOLUTION

The fuel-cladding gap conductance for each equal-length, user-designated axial region is determined by an iterative scheme. Radial temperatures are calculated using a finite difference procedure. The solution procedure consists of iterative convergence for each axial fuel region, followed by iterative convergence on the fuel rod gas release for each time-power step. A mixture of empirical, theoretical, and physical models is used.

6. RESTRICTIONS OR LIMITATIONS

Maxima of 35 time-steps, 23 sets of temperature and physical properties parameters for cladding, 20 pairs of time and diametrical change parameters for cladding creep down, 20 pairs of diameter and relative power parameters for the radial power profile, 20 axial fuel regions, and 10 sets of temperature and thermal conductivity parameters for fuel thermal conductivity.

7. TYPICAL RUNNING TIME

Typical run time on the CDC CYBER74 is approximately 30 seconds per time-step; the sample problem ran in less than 20 CP seconds on a CDC7600.

8. COMPUTER HARDWARE REQUIREMENTS

About 151 Kbytes words of storage are needed on DEC VAX11/780. GT2R2 also ran on CDC computers.

9. COMPUTER SOFTWARE REQUIREMENTS

The software ran under VMS 3.7 (DEC VAX11/780); SCOPE 3.4 (CDC6600); NOS/BE (CDC CYBER74); SCOPE 2.1 (CDC7600). A Fortran compiler is required.

10. REFERENCES

a) Included in package:

M.E. Cunningham and C.E. Beyer, "GT2R2: An Updated Version of GAPCON-THERMAL-2," NUREG/CR-3907 (PNL-5178, (September 1984).

NESC Note 92-11, "GT2R2, NESC No. 618.VX11; Tape Description and Implementation Information" (October 1991).

b) Background information:

C.E. Beyer, C.R. Hann, D.D. Lanning, F.E. Panisko and L.J. Parchen, "GAPCON-THERMAL-2: A Computer Program for Calculating the Thermal Behavior of an Oxide Fuel Rod," BNWL-1898 (November 1975).

11. CONTENTS OF CODE PACKAGE

Included are the reference documents in (10.a) and one 3.5" DOS diskette in compressed PkWare ® format. Software includes source, samples, and data files. No executable is included with the package.

12. DATE OF ABSTRACT

Abstract first distributed March 1974 by NESC then transferred to ESTSC then to RSICC from which it was released software November 2000.

KEYWORDS: FUEL MANAGEMENT; REACTOR PHYSICS