[en] From recently published values for the energy levels for atomic uranium (UI) and singly charged ion (UII), the excitation partition functions have been calculated and an analytical form proposed for them which is valid in the temperature range 0-15000 K. These values are used to determine the degree of ionization for the surface ionization of uranium on polycrystalline rhenium. At a temperature of 3000 K, this value has been determined as 3x10-2. (Auth.)