Improved Analytical Characterization of Solid Waste-Forms by Fundamental Development of Laser Ablation Technology

Russo, Richard E.

Lawrence Berkeley National Laboratory

关键词: Sample Preparation;    Solid Wastes;    12 Management Of Radioactive Wastes, And Non-Radioactive Wastes From Nuclear Facilities;    Waste Forms;    Los Alamos;   

DOI  :  10.2172/828184
RP-ID  :  EMSP-55318-2000
RP-ID  :  828184

美国|英语

来源: UNT Digital Library

【 摘 要 】

Laser ablation (LA) with inductively coupled plasma mass spectrometry (ICP-MS) has been demonstrated as a viable technology for sample characterization within the EM complex. Laser ablation systems have been set up at the Hanford Site, Savannah River Plant, the Pu immobilization program (MD), Los Alamos, and at numerous other DOE facilities. Characterization of elemental and isotopic chemical constituents is an important function in support of tank-waste operation and remediation functions. Proper waste characterization enables safe operation of the tank farms, resolution of tank safety questions, and development of processes and equipment for retrieval, pretreatment, and immobilization of tank waste. All of these operations are dependent on the chemical analysis of tank waste (1). A specified need by the Tanks Focus Area (TFA) is to validate the laser ablation mass spectrometer (LA/MS) technology through round robin testing of standard materials and through fundamental studies of the laser ablation process (2). Advancement of the laser ablation technology is warranted to guarantee accuracy of analysis for the diversity of complex EM samples. This EMSP research endeavored to understand fundamental laser-ablation and ICP-MS detection characteristics, to ensure accurate and sensitive analytical characterization for EM wastesite samples. The difficulty in characterization of EM waste samples is that matrix-matched standards are not available. ICP-MS instrumental calibration must be performed with a series of standards. The sample-matrix will influence the ablation process, such as an amount of ablated mass, elemental fractionation, particle size distribution and particle transport characteristics, and ICP-MS response. If matrix-matched standards existed, the quantity of mass, degree of fractionation, and particle transport would be the same for standards and samples; hence, accuracy of analysis would be guaranteed. In contrast, for most EM samples in which standards are not available, accuracy can only be accomplished through knowledge of the laser ablation processes. Laser ablation offers direct characterization of any solid waste form in a timely manner and at a reduced cost compared to conventional analytical technologies (3-5). Numerous advantages exist for direct solid waste-form characterization. Little or no sample preparation will be required. Laser ablation will eliminate the dissolution requirement, and eliminate the generation of solvent waste. Personnel exposure to hazardous materials will be minimized. Chemical characterization 6 using laser ablation requires a smaller amount of sample (