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首页> 外文学位 >Speciation and spectroscopy of the uranyl and tetravalent plutonium nitrate systems: Fundamental studies and applications to used fuel reprocessing .
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Speciation and spectroscopy of the uranyl and tetravalent plutonium nitrate systems: Fundamental studies and applications to used fuel reprocessing .

机译：铀酰和四价硝酸nitrate体系的形态和光谱学：基础研究及其在废燃料后处理中的应用。

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摘要

This dissertation explores the use of UV-Visible spectroscopy and Time Resolved Laser Induced Fluorescence spectroscopy as near real time process monitors of uranium and plutonium concentrations in aqueous reprocessing trains. The molar absorptivities and linear ranges of these metals were investigated under total nitrate and acid concentrations similar to those found in current reprocessing systems. Concurrent to this, a new multiple wavelength monitor was derived that is capable of determining the total nitrate concentration spectroscopically. This method uses the uranium absorbance spectrum to calculate the nitrate concentration in solution. When used as part of an Advanced Safeguard suite, this technique can provide information on the process chemistry in use.;The fundamental chemistry of the uranyl nitrate system was investigated to add to the thermodynamic data set. A combination of spectroscopic measurements, Density Functional Theory calculations, Extended X-ray Absorption Fine Structure spectroscopy, and observations of solvent extraction studies were used to theorize a new model of uranyl-nitrate speciation. In this model, the dominant species at low nitrate concentrations is UO2(NO3) 2 and the UO2NO3+ species is de-emphasized. Spectrophotometric titrations of the uranyl system were used to determine the log β2,1 values for this system at multiple ionic strengths and the zero ionic strength stability constants were calculated using the Specific Ion Interaction Theory.;The UV-Visible spectroscopy of the tetravalent plutonium nitrate system was investigated as a function of nitric acid concentration. Two pseudo-isobestic points were identified in the spectra which can be used to determine the total PuIV concentration. Factor analysis was then used to investigate the speciation of the system; a total of 5 species exist between 2 and 10 M HNO3. This information can be used to focus future studies.
机译：本文探讨了紫外可见光谱法和时间分辨激光诱导荧光光谱法作为水处理反应堆中铀和p浓度的近实时过程监测仪的应用。在总硝酸盐和酸浓度与目前的后处理系统相似的情况下，研究了这些金属的摩尔吸收率和线性范围。与此同时，推导了一种新的多波长监测器，该监测器能够通过光谱确定总硝酸盐浓度。该方法使用铀吸收光谱来计算溶液中的硝酸盐浓度。当作为Advanced Safeguard套件的一部分使用时，该技术可以提供有关使用中的过程化学的信息。;已研究了硝酸铀酰系统的基本化学作用，以添加到热力学数据集中。结合光谱测量，密度泛函理论计算，扩展的X射线吸收精细结构光谱以及溶剂萃取研究的观察结果，为新的硝酸铀酰形态分析模型建立了理论基础。在此模型中，低硝酸盐浓度下的优势种为UO2（NO3）2，并且不重视UO2NO3 +物种。铀酰体系的分光光度滴定法用于确定该体系在多个离子强度下的logβ2,1值，并使用比离子相互作用理论计算了零离子强度稳定常数。;四价硝酸-的紫外可见光谱研究了该系统作为硝酸浓度的函数。在光谱中鉴定出两个伪等吸收点，可用于确定总PuIV浓度。然后使用因子分析来研究系统的形态；在2至10 M HNO3之间共有5种。该信息可用于重点研究。

著录项

  • 作者

    Smith, Nicholas Alexander.;

  • 作者单位

    University of Nevada, Las Vegas.;

  • 授予单位 University of Nevada, Las Vegas.;
  • 学科 Chemistry Analytical.;Chemistry Nuclear.;Chemistry Inorganic.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 173 p.
  • 总页数 173
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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