Gapcon-3 a computer code to analyze the path-dependent thermal and mechanical performance of nuclear fuel rods

GAPCON-3 provides an integrated thermal and mechanical analysis of a reactor fuel pin in terms of its path-dependent power history. It is designed to handle the axial and radial variations in power, temperature, and fuel cladding mechanical interaction, normally encountered in LWR fuel. It provides detailed information regarding temperatures, stresses, and strains depending upon the mesh size selected and the needs of the user. The Code uses a finite element formulation for the mechanical analysis and includes the effects of creep, plasticity, and anisotropy. The steady state thermal calculations are based upon the method of weighted residuals (MWR) and use a finite difference formulation for treating the transient thermal dependence. The fuel behavior models incorporate relocation, swelling, and densification as well as power history-dependent local fission gas release. The code is structured to operate efficiently and to allow its use in both parametric as well as detailed analysis applications. A typical problem on a CDC-6600 computer will require 8 to 10 seconds per time step for solution