After the war, he prepared as a free candidate for the entrance exam to the École nationale des arts et métiers.
On the advice of his professors, he passed the École polytechnique exam in 1949, where he graduated as a major, then joined the CEA Saclay in the mathematical physics department headed by Jacques Yvon [fr], Jules Horowitz, Albert Messiah, Anatole Abragam, Claude Bloch, and others.
and upstream of the fuel cycle (control command of the uranium isotope separation plant) as well as downstream of this cycle (formation and physics of plutonium and other actinides isotopes, descendants of fission products, activated structure nuclei, etc.).
In addition, Robert Dautray participated in the establishment of the basic physical sciences for the sciences of high densities and powers of materials and electromagnetic radiation (state equations, opacity, radiative transfer, discontinuities of high velocity flows, interface instabilities, laser implosions, thermonuclear reactions, non-linear neutronics of high velocity media of nuclei making the neutron transport and plasma physics equations non-linear, etc.).
Robert Dautray co-chaired with the EDF Studies and Research Department the CEA/EDF digital analysis summer schools.