Why is kerosene being used in PUREX (plutonium uranium reduction extraction) as a solvent?

I am searching for a reason, why organic solvent in [PUREX](https://en.wikipedia.org/wiki/PUREX) consists of 30% tributyl phosphate (TBP) in kerosene. Why kerosene (or another hydrocarbon)? What properties does it have? What exactly does kerosene do in the organic phase?




The actual extraction agent in the Purex process is tributyl phosphate (TBP). It is one of the most versatile extraction agents for many inorganic ions and has been made the basis for a number of various processes.


However, because of its high viscosity and a density very similar to that of water, it is customary to use TBP as a solution in an inert solvent such as kerosene.


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