The effect of fission on circulating a UO2-NaK suspension has been studied up to a total uranium burnup of 0.07%. A loop of one-half inch stainless steel tubing with a test volume of 250 cc was irradiated in the Argonne CP-5 reactor. The loop contained 5% vol. (40% wt) 93.14% enriched UO2 suspended in NaK alloy and was operated for 902 hr at temperatures above 350°C. No difficulty was encountered during the operation of the loop in the reactor. Examination of the slurry after irradiation showed extensive comminution of the UO2 particles. Analytical results after termination of the experiment revealed the distribution of some fission products. 45.5% of the krypton and xenon fission gases were found in the cover gas. 82% of the cesium was found dissolved in the NaK. Cerium and zirconium were found with the UO2.