  Multinucleon transfer mechanism in the collision of
${}^{238}\text{U}+{}^{238}\text{U}$ system is investigated at $E_\text{c.m.}
=833$ MeV in the framework of the quantal diffusion description based on the
stochastic mean-field approach (SMF). Double cross-sections $\sigma(N,Z)$ as a
function of the neutron and proton numbers, the cross-sections $\sigma(Z)$ and
$\sigma(A)$ as a function of the atomic numbers and the mass numbers are
calculated for production of the primary fragments. The calculation indicates
the ${}^{238} \text{U}+{}^{238} \text{U}$ system may be located at an unstable
equilibrium state at the potential energy surface with a slightly negative
curvature along the beta stability line on the $(N,Z)-$plane. This behavior may
lead to rather large diffusion along the beta stability direction.
