Influence of Isopar-M on Radiation and Thermal Degradation of Tri- n -Butyl Phosphate in Solutions

The post-radiation (dose 1 MGy) thermal and hydrolytic stability of 30 vol % tributyl phosphate solutions in Isopar-M at 90–170°C in contact with an aqueous solution of 8–12 M HNO 3 was studied. Isoparaffins participate in the radiolytic degradation of TBP mainly due to radical processes of alkylation and hydrogenation. Post-radiation acid hydrolysis causes degradation of nitrogen-containing radiolysis products, leading to partial regeneration of dibutyl phosphate and monobutyl phosphate. Heating additionally stimulates the dealkylation of products with the formation of volatile hydrocarbons, which increases the fire and explosion hazard of high-temperature operations with irradiated solutions.