*Plenum Gas Effect on Fuel Temperature DOI: http://dx.doi.org/10.5772/intechopen.101098*

all previous fission gas release values. The fission gas generation does not require that the simulation starts from zero. Transmutation of U-238 to plutonium and subsequent fission gas release due to fission of plutonium is also available in the code models. The fuel diameter is a function of power (Kw/ft), as fabricated coldgap thickness (inches) and burnup (MWD/MTM). The model is based on linear regression analysis of experimental data. The fuel densification correlation calculates the reduction of fuel radius as a function of burnup and differential fuel density.

GT-II calculates the gap conductance, temperature, pressure, and stored thermal energy based on the power history of the fuel. The plenum gap conductance for each equal-length, user-designated axial region is determined by an iterative scheme. Radial temperature is calculated using finite difference. The solution procedure consists of iterative convergence for each axial region, followed by iterative convergence on the fuel gas release for each time-power step. Empirical, theoretical, and physical models are used for fuel gas release calculation.
