A rapid, automated, microanalytical procedure for the determination of 90 Sr in aged nuclear waste has been developed. It is based on a sequential injection analysis (SIA) system which rapidly separates 90 Sr from 90 Y, 137 Cs, and other radionuclides. The isolated 90 Sr is then detected on-line with a flow-through liquid scintillation counter. The separation is achieved using a sorbent extraction minicolumn containing a resin (EIChrom, Sr-Spec) that selectively binds 90 Sr as a crown ether complex under acidic conditions. The 90 Sr is eluted with water, mixed with liquid scintillation cocktail, and detected in the flow cell of the counter. Sample 90 Sr activity can be quantified from peak areas, giving linear calibration curves. The instrument can also be operated in a stoppedflow mode for longer counting times. Analyses of aged nuclear waste samples from the Hanford site by the SIA method and a manual method were in excellent agreement: correlation coefficient R ) 0.994. Sample analysis by the SIA method is complete in less than 40 min. The advantages of the new 90 Sr analyzer include faster analysis, greater precision, reduced labor costs, and reduced secondary waste. Worker safety is improved because solution handling operations are fully automated and contained.
A sequential injection (SI) separation system has been developed for separation and analysis of Am, Pu, and Np isotopes using on-line inductively coupled plasma mass spectrometry (ICP MS) detection. On-line actinide separations were carried out using an actinide-specific extraction chromatographic material (TRU-resin, Eichrom Industries, Inc. USA). Separations are demonstrated and characterized that are compatible with on-line ICP MS detection and address isobaric ( 241 Am/ 241 Pu, 244 Pu/ 244 Cm, 238 U/ 238 Pu), molecular ( 238 UH/ 239 Pu), and spectral ( 238 U/ 237 Np) interferences encountered in the analysis of Am, Pu and Np isotopic composition using ICP MS. The effects of reductive sample treatment on the extent of U matrix removal were investigated. Uranium separation factors were limited by the formation of U(IV) species, which exhibited separation behaviors similar to that of Pu(IV) and Np(IV). Nevertheless, separation factors as high as 3.0 3 10 5 can be achieved at the 0.1 mg ml 21 U concentration levels using Fe(II) sulfamate as a reductant. The sequential injection (SI) ICP MS technique has been applied towards analysis of Am, Pu, and Np isotopes in a dissolved vitrified nuclear waste sample. Results obtained using the automated separation technique with ICP MS detection were in satisfactory agreement with results obtained using standard analytical methodologies.
An automated procedure for the determination of (99)Tc in aged nuclear waste has been developed. Using advanced sequential injection (SI) analysis instrumentation, (99)Tc(VII) is separated from radioactive and stable interferences using a TEVA resin column that selectively retains pertechnetate ion from dilute nitric acid solutions. The separated (99)Tc is eluted with 6 M nitric acid and quantified on-line with a flow-through liquid scintillation detector. A stopped-flow technique has been optimized that improves the analysis precision and detection limit compared to continuous-flow detection, reduces consumption of liquid scintillation cocktail, and increases sample throughput by separating the next sample while the present sample is being counted. The detection limit is 30 pCi, or 2 ng, of (99)Tc, using a 15-min stopped-flow period. The analysis time is 40 min for the first sample and is reduced to 20 min for each subsequent sample. Processed nuclear waste samples from the Hanford site were successfully analyzed by this new method.
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