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NESC0618 GAPCON-THERMAL2 REV.

GTR2 GAPCON-THERMAL2, Steady-State Fuel Rod Thermal Behaviour and Fission Products Gas Release

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1. NAME OR DESIGNATION OF PROGRAM:  GAPCON-THERMAL2 Rev.1; GT2R2.
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2. COMPUTERS
To submit a request, click below on the link of the version you wish to order. Only liaison officers are authorised to submit online requests. Rules for requesters are available here.
Program name Package id Status Status date
GAPCON-THERMAL-2 NESC0618/03 Tested 18-MAY-1984
GT2R2-1 NESC0618/05 Tested 29-AUG-1994

Machines used:

Package ID Orig. computer Test computer
NESC0618/03 CDC CYBER 740 CDC CYBER 740
NESC0618/05 DEC VAX series DEC VAX 6000
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3. DESCRIPTION OF PROBLEM OR FUNCTION

GAPCON-THERMAL2 Rev. 1
calculates 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.
GT2R2, a revision of GAPCON/THERMAL, is used by the U.S. Nuclear Regulatory Commission for audit calculations of nuclear fuel thermal performance computer codes.
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4. METHOD OF SOLUTION

The fuel to 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.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

(1) GAPCON-THERMAL2:
    Maxima of -
    15 axial nodes
    35 time-steps
No mechanical plastic strain is considered. The thermal model is axisymmetric. The first time-step must be zero time and the second cannot be at zero power.
(2) GTR2:
    Maxima of
    35 time-steps
    23 sets of temperature and physical properties parameters for
       cladding
    20 pairs of time and diametral change parameters for cladding
       creepdown
    20 pairs of diameter and relative power parameters for the
       radial power profile
    10 sets of temperature and thermal conductivity parameters for
       fuel thermal conductivity
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6. TYPICAL RUNNING TIME

Typical run time on the CDC CYBER74 is approximately 30 seconds per time-step; the sample problem runs in less than 20 CP seconds on a CDC7600.
NESC0618/03
NEA-DB executed the test case on CDC CYBER 740 in 275 CPU seconds (about 38 seconds per time step).

NESC0618/05
NEA-DB ran the test case included in this package on a  VAX-6000 computer in 47 seconds of CPU time.
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7. UNUSUAL FEATURES OF THE PROGRAM

Most models have been compared individually with experimental data; however, the code as a whole has not been adjusted to conform to any set of data.
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8. RELATED AND AUXILIARY PROGRAMS

GTR2 is a revision of GAPCON- THERMAL2 Rev.1 to improve predictive abilities at high burnup and coding structure and to conform to the ANSI FORTRAN 77 language standard.
GAPCON-THERMAL2 is a modification of GAPCON-THERMAL1 to reduce the uncertainties associated with the calculation of power history and burnup. GAPCON-THERMAL3 (NESC Abstract 770) is a related program which calculates detailed fuel rod mechanical conditions.
GAPCON-THERMAL3 (NESC0770) is a related program which calculates detailed fuel rod mechanical conditions.
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9. STATUS
Package ID Status date Status
NESC0618/03 18-MAY-1984 Tested at NEADB
NESC0618/05 29-AUG-1994 Tested at NEADB
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10. REFERENCES

- C.E. Beyer, C.R. Hann, D.D. Lanning, F.E. Panisko and L.J. Parchen   User's Guide for GAPCON-THERMAL2: A Computer Program for Calcu-
  lating the Thermal Behavior of an Oxide Fuel Rod,
  BNWL-1897, November 1975.
NESC0618/03, included references:
- C. E. Beyer et al.:
  GAPCON-THERMAL-2: A Computer Program for Calculating the Thermal
  Behavior of an Oxide Fuel Rod
  BNWL-1898 NRC 1 and 3 (November 1975).
- NESC Note 81-07 (December 28, 1980).
NESC0618/05, included references:
- M.E. Cunningham and C.E. Beyer:
  GT2R2 - An Updated Version of GAPCON-THERMAL-2
  NUREG/CR-3907, PNL-5178 (September 1984).
- C.E. Beyer et al.:
  GAPCON-THERMAL-2 - A Computer Program for Calculating the Thermal
  Behavior of an Oxide Fuel Rod
  BNWL-1898, NRC 1 and 3 (November 1975).
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11. MACHINE REQUIREMENTS

GAPCON-THERMAL3 Rev.1: About 54k words of main memory is needed for compilation and execution.
GTR2: About 151 Kbytes of storage are needed for execution on a DEC  VAX11/780.
NESC0618/03
70,600 octal words of main storage on CDC CYBER 740.

NESC0618/05
The program was implemented at NEA-DB on a DEC VAX-6000 computer.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0618/03 FORTRAN-IV
NESC0618/05 FORTRAN-77
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

VMS 3.7 (DEC VAX11/780); SCOPE 3.4 (CDC6600); NOS/BE (CDC CYBER74); SCOPE 2.1 (CDC7600).
NESC0618/05
The program was compiled and executed at the NEA-DB under VAX/VMS V5.5-2 using the VAX FORTRAN compiler V5.5-98.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
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15. NAME AND ESTABLISHMENT OF AUTHOR

C.E. Beyer*, M.E. Cunningham*, C.R. Hann, D.D. Lanning,
F.E. Panisko, and L.J. Parchen
Pacific Nothwest Laboratories
Battelle
P.O. Box 999
Richland, Washington 99352
* Contact
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16. MATERIAL AVAILABLE
NESC0618/03
File name File description Records
NESC0618_03.002 GAPCON-THERMAL-2 INFORMATION 53
NESC0618_03.004 GAPCON-THERMAL-2 SOURCE (COMPILE FORM) 2662
NESC0618_03.005 GAPCON-THERMAL-2 SOURCE (UPDATE FORMAT) 2462
NESC0618_03.006 GAPCON-THERMAL-2 TEST CASE DATA 15
NESC0618_03.007 GAPCON-THERMAL-2 TEST CASE OUTPUT 5675
NESC0618/05
File name File description Records
NESC0618_05.001 This information file 126
NESC0618_05.002 GT2R2-1 Fortran source 4801
NESC0618_05.003 Common Block INPUTV 16
NESC0618_05.004 Common Block AZ 4
NESC0618_05.005 Common Block AF 4
NESC0618_05.006 Common Block AD 11
NESC0618_05.007 Common Block PH 5
NESC0618_05.008 Common Block HGAP 4
NESC0618_05.009 Common Block AB 10
NESC0618_05.010 Common Block INIT 13
NESC0618_05.011 Sample problem input 82
NESC0618_05.012 Sample problem output 2484
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17. CATEGORIES
  • H. Heat Transfer and Fluid Flow
  • I. Deformation and Stress Distributions, Structural Analysis and Engineering Design Studies

Keywords: LWR reactors, cladding, fuel rods, performance, steady-state conditions, thermal conductivity.