Radionuclide separation using coupled chromatographic and scintillation detection techniques

Radiochromatographic techniques were investigated for the analysis of radionuclides in environmental and waste samples. Initial work quantified the capability of an ion chromatography and flow-through radiation detector system to separate radionuclides in the presence of common groundwater and high level waste tank constituents. Incremental mass loadings of individual constituents were mixed with a radioactive solution (55Fe, 63Ni, 90Sr and 147Pm) and then analyzed by radiochromatography. Of the three activation/fission products ( 60Co, 152Eu, and 137Cs) tested with the tracer solution, poor peak separation was observed between 137 Cs and 63Ni. The elution program was incapable of consistently separating natural uranium or thorium from the radionuclide solution. For the chemical ionic components, increased ionic strength of the solution resulted in decreased retention fractions on the preconcentration column and significant shifts in peak elution times.; Due to the variability of the sample matrix, selective extractive chromatography resins were evaluated as a sample preparation technique for radiochromatography. Uncontaminated soil samples spiked with a tracer solution (241Am, 244Cm, 233U, and 90Sr) were either acid digested or acid leached to decompose the soil matrix. Strontium and the actinides were extracted from the acidified solution using a serial arrangement of strontium and actinide selective columns. The results were inconsistent as some chromatograms contained either poor peak separation or variable peak elution times, indicative of ionic interfering constituent(s) in the chromatography sample matrix. Diluting the chromatography sample matrix improved peak separation, but with a concurrent decreased sensitivity for radionuclides.; An innovative radionuclide sensor that combines sample preparation, chromatography, and radiation detection into a single component was evaluated for actinide separation and quantification. This extractive scintillating resin consists of an inert polystyrene core impregnated with organic fluors (diphenyloxazole and 1,4-bis-(4-ethyl-5-phenyl-2-oxazolyl) benzene) and an actinide selective extractant (octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide in tri-butyl phosphate). A scintillation detection system, which utilizes the resin in a flow-cell configuration, acquires pulse height spectra and time-series data during the loading and elution of actinides. This analytical technique offers on-line actinide activity and actinide characterization associated with the choice of eluent. The capability of the resin was evaluated using actinide waste solutions and spiked synthetic groundwater.