1. NAME AND TITLE

FRAPCON2: Fuel Rod Thermal-Mechanical Behavior, Versions FRAPCON2, FRAPCON2/VIM4 & FRAPCON2/VIM5.

Note: See http://frapcon.labworks.org/ regarding newer versions of FRAPCON-2, FRAPT6/MOD1 and FRAPT6/V21.

2. CONTRIBUTORS

EG and G Idaho Inc., Idaho Falls, Idaho, and Pacific Northwest Laboratory, Richland, Washington, through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.
 

3. CODING LANGUAGE AND COMPUTER

(P00517MFMWS00)

VAX Fortran 4.2; DEC VAX 11/750 FRAPCON2

Fortran IV; CDC Cyber 176 FRAPCON2/VIM4

Fortran IV; CDC Cyber 176 FRAPCON2/VIM5
 

4. NATURE OF PROBLEM SOLVED

This package contains three versions of the FRAPCON series of fuel rod response modeling programs. The FRAPCON series, like the earlier FRAP-S and GAPCON-THERMAL codes, is designed to predict the steady-state long-term burnup response of oxide fuel rods in light water reactors (LWRs). In addition, these codes generate the initial conditions for transient fuel rod analysis by the FRAP-T6 or thermal-hydraulic analysis programs. The FRAPCON2 programs calculate the temperature, pressure, deformation, and failure histories of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include heat conduction through the fuel and cladding, cladding elastic and plastic deformation, fuel-cladding mechanical interaction, fission gas release, fuel rod internal gas pressure, heat transfer between fuel and cladding, cladding oxidation, and heat transfer from cladding to coolant. Material properties, water properties, and heat transfer correlation data are included.

The FRAPCON series replaced the FRAP-S1, FRAP-S2, and FRAP-S3 series of programs. The fuel temperature computation used in the FRAPCON series was taken from the GAPCON-THERMAL2 code (NESC 618). FRAPCON2/VIM4 generates the initial conditions for transient fuel rod analysis used either by FRAP-T6 (NESC 658) or RELAP4/MOD7 (NESC 369).
 

5. METHOD OF SOLUTION

FRAPCON2 iteratively calculates the interrelated effects of fuel and cladding temperature, rod internal gas pressure, fuel and cladding deformation, release of fission product gases, fuel swelling and densification, cladding thermal expansion and irradiation-induced growth, cladding corrosion, and crud deposition as functions of time and fuel rod specific power. The calculation begins with processing of input data. Next, the initial fuel rod state is determined through a self-initialization calculation. Time is advanced according to the input-specified time-step size; a steady state solution is determined, and the new fuel rod state obtained. The new fuel rod state provides the initial state conditions for the next time step, and these calculations are cycled in this manner for the user-specified number of time steps. The solution for each time step consists of a calculation of the temperature of the fuel and cladding, a calculation of fuel and cladding deformation, and a calculation of the fission product generation, void volume, and fuel rod internal gas pressure. In FRAPCON2, when the FRACAS-I mechanics model is selected, the fuel rod failure probability is calculated also. Each of these calculations is performed in a separate subcode.
 
 
 

6. RESTRICTIONS OR LIMITATIONS

The codes are limited to single-rod analysis with 11 radial nodes. FRAPCON2 allows a maximum of 19 axial nodes and a maximum of 100 power time steps. The FRAPCON2/VIM codes allow a maximum of 18 axial nodes and a maximum of 200 power time steps. The thermal models of the code are based on steady-state data and equations; therefore, calculated temperatures will become progressively inaccurate as input power histories result in power ramp rates greater than 0.02 percent per second. Similarly, the gas release models are based on steady-state data and do not reflect release rates for rapid power changes. All of the thermal and mechanics modeling options assume an axisymmetric fuel rod. Large deformations with greater than 5 percent strain will not be traced well. If the PELET option is selected, power step changes greater that 1.0 KW/ft per time step should not be used.
 

7. TYPICAL RUNNING TIME

NESC executed the FRAPCON2 sample problems in 25 CPU minutes on a DEC VAX11/785.
 

8. COMPUTER HARDWARE REQUIREMENTS

These codes were developed on CDC Cyber computers. The FRAPCON2 code was converted to run on DEC VAX computers. The FRAPCON2/VIM versions ran only on CDC.
 

9. COMPUTER SOFTWARE REQUIREMENTS

Fortran compilers are required to compile and load the FRAPCON source files. The FRAPCON2 package was tested at the NEADB on a DEC VAX 8810 under VMS V5.0-1 and was released as NESC-0694/09. The FRAPCON2/VIM4 version ran on CDC Cyber 176 under NOS2. This version was screened at the NEADB in June 1993 and released as NESC-0694/08. The FRAPCON2/VIM5 version ran on CDC Cyber 176 under NOS2. The codes were not tested or modified when released by RSICC in March 2002.
 

10. REFERENCES

a) Included in documentation:

W.N. Rausch and D. D. Lanning, "FRAPCON2-VIM4," Pacific Northwest memo (February 7, 1983).

NESC Note 82-09 FRAPCON2, NESC No. 694.C176 (November 30, 1981).

G.A. Berna, M.P. Bohn, W.N. Rausch, R.E. Williford, and D.D. Lanning, "FRAPCON-2: A Computer Code for the Calculation of Steady State Thermal-Mechanical Behavior of Oxide Fuel Rods," NUREG/CR-1845 R3 (January 1981).

Addenda to FRAPCON-2 Code Manual, received April 1988.

G.A. Berna, D.D. Lanning and W.N. Rausch, "FRAPCON-2 Developmental Assessment," NUREG/CR-1949 (July 1981).

D.L. Hagrman, G.A. Reymann and R.E. Mason, " MATPRO - Version 11(Rev. 1): A Handbook of Materials Properties for Use in the Analysis of Light Water Reactor Fuel Rod Behavior," NUREG/CR-0497 (February 1980).

D.R. Coleman, "Evaluation of Power Reactor Fuel Rod Analysis Capabilities, Phase 2 Topical Report, Volume 1: Data Evaluation," NUREG/CR-3741 Vol.1 (April 1984).
 

b) Background reference:

D.R. Coleman, "Evaluation of Power Reactor Fuel Rod Analysis Capabilities, Phase 2: Topical Report, Volume 2: Code Evaluation," NUREG/CR-3741, Volume 2 (November 1985).
 

11. CONTENTS OF CODE PACKAGE

Included in the package are the referenced documents in 10.a and a CD with the source codes, test cases and command procedures written in self-extracting Windows files. Electronic documentation files are distributed in PDF format.
 

12. DATE OF ABSTRACT

March 2002.
 

KEYWORDS: FRACTURE MECHANICS; LWR; REACTOR SAFETY