DETERMINATION OF THORIUM IN PLUTONIUM-THORIUM ALLOYS

A spectrophotometric method used in the determination of thorium was modified for the purpose of anulyzing plutorium alloys which contained 0.01 to 0.8% thorium. Absorbance values were measured at 545 m mu for solutions containing thorium and thorin, the organic reagent added to form a colored complex with thorium in the presence of plutonium(III). With plutonium-thorium solution samples, equivalent to dissolved alloys containing 0.2 to 0.8% thorium, the average recovery of thorium was 99.6 plus or minus 1.5%. For similar samples containing 0.01 to 0.2% thorium, the average recovery was 101.0 plus or minus 3.4%, after the thorium was separated from plutonium by precipitation of thorium fluoride with the aid of lanthanum fluoride as a carrier. (auth)