NESC0770 GAPCON-THERMAL3

GAPCON-THERMAL3, Fuel Rod Steady-State and Transient Thermal Behaviour, Stress Analysis

NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES

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1. NAME OR DESIGNATION OF PROGRAM: GAPCON-THERMAL3

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2. COMPUTERS

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Program name	Package id	Status	Status date
GAPCON-THERML3	NESC0770/02	Tested	01-MAR-1980

Machines used:

Package ID	Orig. computer	Test computer
NESC0770/02	CDC 7600	CDC 7600

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3. DESCRIPTION OF PROBLEM OR FUNCTION

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.

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4. 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.

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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

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.

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6. TYPICAL RUNNING TIME

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

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7. UNUSUAL FEATURES OF THE PROGRAM

The   finite   element   chained
radial-axial-radial mechanics modeling yields a good approximation
to  total  two-dimensional  finite   element  calculation  results
without commensurate large computer storage and long running time.
The  program includes  variable  dimensions  to limit  storage  to
individual problem requirements.  A restart tape and plot tape are
produced by the main code as optional output.

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8. RELATED AND AUXILIARY PROGRAMS

PLOT3 produces high  quality off-
line   plots    of   GAPCON-THERMAL3    output.    GAPCON-THERMAL3
incorporates  the thermal  calculations  of GAPCON-THERMAL2  (NESC
Abstract 618) with  a more detailed nonlinear  mechanical analysis
to evaluate  the interactive  effects.  Available  output includes
fuel and cladding stresses and strains  in radial, hoop, and axial
directions and fuel and cladding axial and radial displacements.

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9. STATUS

Package ID	Status date	Status
NESC0770/02	01-MAR-1980	Tested at NEADB

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10. REFERENCES

D. D. Lanning,  C. L. Mohr, F. E. Panisko,  and K. B.
Stewart,  Gapcon-Thermal-3  Code  Description,  PNL-2434,  January
1978.
             D.  D.  Lanning,  F.  E. Panisko,  and  C.  L.  Mohr,
Verification  of  the GAPCON-THERMAL-3  Computer  Code,  PNL-2435,
September 1978.

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11. MACHINE REQUIREMENTS

About 220K of addressable storage is needed
for execution of a typical problem.

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12. PROGRAMMING LANGUAGE(S) USED

Package ID	Computer language
NESC0770/02	FORTRAN-IV

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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

SCOPE 3.4
(CDC6600), NOS/BE and SCOPE 2.1 (CDC7600).

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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

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15. NAME AND ESTABLISHMENT OF AUTHORS

                 D. D. Lanning, C. L. Mohr, F. E. Panisko,
                 and K. B. Stewart
                 Pacific Northwest Laboratories
                 Battelle
                 P. O. Box 999
                 Richland, Washington  99352

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16. MATERIAL AVAILABLE

NESC0770/02

File name	File description	Records
NESC0770_02.001	SOURCE	7631
NESC0770_02.002	INPUT FOR S.P.	94
NESC0770_02.003	AUX. PROGRAM	571
NESC0770_02.004	OUTPUT OF S.P.	453
NESC0770_02.005	INFORMATION	3

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17. CATEGORIES

I. Deformation and Stress Distributions, Structural Analysis and Engineering Design Studies

Keywords: cladding, creep, deformation, finite element method, fuel rods, plasticity, steady-state conditions, stresses, transients.