Studies on the identification of harmful radiolytic products of 30% TBP-N-dodecane-HNO3 by gas-liquid chromatography. II. Formation and characterization of high molecular weight organophosphates

Gamma radiolysis of Purex solvent, 30% tri-n-butylphosphate-n-dodecane-HNO3 is observed to yield many undesirable metal complexing species. A method f or identifying the gas-liquid chromatographic (GLC) signatures of high mole cular weight organophosphates (HMPs) through a nitrogen- and phosphorous-se lective detector is described. Fractionation of the radiolyzed solvent by v acuum distillation resulted in the enrichment of HMP species in the high bo iling, viscous residue in the last fraction. This residue showed intense in frared signals characteristic of the presence of nitro, carbonyl, and phosp horyl groups, which implies the presence of multifunctional species. The st udy revealed a strong association among the components of radiolyzed solven t, which inhibits clean fractionation. Gas chromatography-mass spectrometry assay of the sample indicated that these HMPs consist of (NO2-C4H8)(C4H9O) (2)PO, (OH-C4H8O)(C4H9O)(2)PO, and (CH3-C4H8)(C4H9O)(2)PO species. The HMP- rich fraction exhibited very high plutonium-retention behavior, which Was s ubstantially lowered by efficient uptake of HMPs upon alumina treatment. Th us, the present study correlates the GLC signatures of HMPs, especially tho se of nitrated species, formed by radiolysis of 30% tri-n-butylphosphate-n- dodecane-HNO3 and solvent quality deterioration with respect to Pu-retentio n behavior.