Study of runaway reaction between tri-n-butyl phosphate (TBP) and nitric acid resulting in red-oil formation (and related problems) in the process evaporators of
reprocessing plants has been a major safety concern since last 50 years. Thermal decomposition of nitrated TBP results in
rapid pressurization and in close-vent condition it may lead to failure of process vessel and containment. Thermal decomposition
of nitrated TBP is reported in the literature but corresponding studies for alternate PUREX/UREX solvent tri-iso-amyl phosphate (TiAP) are not available. In this work, comparative study of the thermal decomposition of nitrated solvents
(TBP as well as TiAP) under adiabatic conditions in a sealed autoclave is presented. Experimental results indicate much lesser
pressurization in the case of TiAP as compared to TBP.