Metallic U is calculated by means of the method of many-electron operator spinors. Atomic phase diagram is accompanied by dividing of 5$f$-shell on $e_{\textrm{g}}$ (5$f^1$) and $t_{2\textrm{g}}$ (5$f^2$) subshells. Destabilization of U ion electronic structure is connected with 5$f$–6$d$ hybridization. Jumping of ‘outer’ 5$f^1$ electrons on 6$d$ level owing to excitation of chemical (covalent) bond fluctuations (CBF) with temperature $T$ growth leads to $\alpha$–$\beta$ transition ($T$ → $T_{\textrm{k1}}$). Then growth of CBF density excites 5$f^2$–6$d$ hybridization and $\beta$–$\gamma$ transition at $T$ → $T_{\textrm{k2}}$ > $T_{\textrm{k1}}$. Hysteresis of each transition is conditioned by covalent-band bonds. Transitional volume jumps $\Delta V_{1,2}$ are determined by inhomogeneity $\Gamma_{dd}(\textbf{r} – \textbf{R})$ of U ion covalent bonds in sites $\textbf{r}$ and $\textbf{R}$. Angular moment $\textbf{L}_{\textbf{r}}$ locality prevents from display magnetism of metallic U. But inclusion of U ion spin-orbital bonds with 3$d$ ions influences on magnetic hardness of alloys of U–Co type, which is observed experimentally.