For many years effort has been directed toward the development of means for the practical utilization of the heat evolved from the radioactive decay of certain fission and irradiation products. Fission products, in view of their availability in the plentiful, high-level wastes resulting from the processing of irradiated, nuclear reactor fuels have been most intensively studied for applications where their heat of decay might be converted into useful energy such as electricity for the operations of certain devices in place of chemical batteries . In addition other materials having desired radioactive properties may be produced by neutron bombardment of readily available elements.

The study of the flame photometric method for determining the concentration of tributylphosphate (TBP) in a hydrocarbon diluent was undertaken because it showed promise of being economically competitive and subject to fewer interferences than the existing methods. The determination of TBP in the hydrocarbon solutions throughout the range 0.01 to 80 per cent TBP may be performed using the flame photometer. The principal conclusions resulting from the study found a that there was higher precision in the one to two percent TBP rang than the 45 per cent TBP level due to error in reproducing narrow slit width in the higher range, 2) nitric acid, uranyl nitrate, and thorium nitrate all interfere if present but can be eliminated by contacting the solution with water or sodium carbonate solution. 3) a single determination may be made in 15 minutes, multiple determinations can be made at a rate of one to two minutes per determination, and 4) a modification of an existing method makes possible the application of this method to the determination of TBP dissolved in aqueous samples. A relative precision of plus of minus five per cent (95 per cent confidence level) is obtained.

Graphs for estimation of plutonium and trans-plutonium isotopic content of irradiated plutonium reactor fuel of various initial isotopic compositions.