[@engelmann]), where $R=\frac{pc}{Ze}$ is the rigidity of particle with momentum $p$ and atomic number $Z$. This extrapolation breaks down around $3\times10^{15}$ eV ([@gaisser00]) because the value of an effective escape length is equal to $c\tau\sim300$ pc which corresponds to just one crossing of the Galactic disk and the probability of nuclei escape significantly rises. The situation within the highest energy range is not clear, but we expect that the nuclei are not trapped in GMF. The task we have to solve is to find the value of tracking time for the simulation of particles with energies in range $10^{13}\div10^{19}$ eV. We have found that the value $T=3\times10^{12}$ s $\sim10^5$ yr appears as the most suitable tracking time of particles for the study of nuclei escape rate from the Galaxy. From the equation $\tau\sim R^{-0.6}$ we obtain the value $10^{11}$ s for proton with the energy in the middle of our range (which is equal to $10^{15}$ eV). Despite of it, we use tracking time longer by one order of magnitude. The reason for such choice is that: (1) The mean residence time for nuclei with higher $Z$ will be longer than for proton. (2) The nuclei escape rates are too 