The optimal usage of designed fuel pellets is one of the very important parameters in inertial confinement fusion (ICF) systems. In this research, time-dependent dynamical equations for D/D fuel are written by considering impurity of 6Li. Then dependency of gain on temperature, density and pellet radius is studied using Runge–Kutta method. The obtained results show that the energy gain will be maximized at the initial temperature 35 keV, density, 5000 g/cm3 and ratio impurity of 6Li, 0.05
