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Spectroelectrochemical Sensor for Pertechnetate Applicable to Hanford and Other DOE Sites

Description: New film materials for pertechnetate: A new film material comprised of quaternized poly(4-vinylpyridine) cross-linked with 1,10-diiododecane has been developed for use in the spectroelectrochemical sensor. Films were prepared in a one-pot synthesis by stirring poly(4-vinylpyridine), cross-linker and methyl iodide in 1-butanol for 1 h, after which the solution was spin-coating onto ITO-glass. Film thickness was varied either by changing the spin rate or by dilution of the original precursor solution. The thinnest film prepared was 30 nm; the thickest 930 nm. Spectroscopic ellipsometry was used to study the dynamics of film changes on soaking in aqueous salt solution and on preconcentrating model analyte ferrocyanide. The results document that, on hydration, films expanded by almost 90% in 0.1 M KNO3, then contracted slightly when ferrocyanide solution was introduced probably due to electrostatic cross-linking. IR spectroscopy was used to determine the extent of quaternization of the film. For a polymer solution stirred for 1 h, films were about 20% quaternized. This can be increased to {approx}30% by adding more solvent to the precursor solution and stirring for an additional hour. Solubility of the partially cross-linked material was a factor that limited the quaternization process. Use of a more appropriate solvent may enable greater quaternization. A more quaternized film should preconcentrate more pertechnetate by virtue of having a higher density of charged binding sites. Film ruggedness is critical. To investigate this, films on ITO-glass were soaked in methanol and butanol overnight, in 0.1M KNO3, and in 0.1M KNO3 adjusted to pH 12 and pH 2 for 30 days. Each film was then tested as a spectroelectrochemical sensor for model analyte ferrocyanide. The results showed only the pH 2 conditioned sensor behaved abnormally. The film soaked in pH 2 electrolyte delaminated but did not dissolve. Delamination was most likely due to the acid digestion ...
Date: December 1, 2004
Creator: Heineman, William R.
Partner: UNT Libraries Government Documents Department

Examination of Genetic Alterations in Preneoplastic and Neoplastic Lesions of the Lung From Uranium Miners. Final Technical Report

Description: Lung cancer is one of the leading causes of death in the United States and in Western Europe. The incidence of lung cancer in developing countries is rising as their cigarette smoking habits increase. The objectives of this proposed research are to analyze genetic alterations associated with the development and progression on non-small cell lung carcinoma (MSCLC). Endpoints that may be realized from this proposed research are: (1) detection of early genetic and/or cellular alterations which ultimately could lead to diagnostic modalities for the early detection of lung cancer; and (2) detection of novel tumor suppressor genes on chromosome 9p. This proposal will analyze both tumor specimens and sputum samples.
Date: July 12, 2000
Creator: Anderson, Marshall
Partner: UNT Libraries Government Documents Department

Design and construction of a prototype advanced on-line fuel burn-up monitoring system for the modular pebble bed reactor

Description: Modular Pebble Bed Reactor (MPBR) is a high temperature gas-cooled nuclear power reactor currently under study as a next generation reactor system. In addition to its inherently safe design, a unique feature of this reactor is its multi-pass fuel circulation in which the fuel pebbles are randomly loaded and continuously cycled through the core until they reach their prescribed End-of-Life burn-up limit. Unlike the situation with a conventional light water reactor, depending solely on computational methods to perform in-core fuel management for MPBR will be highly inaccurate. An on-line measurement system is needed to accurately assess whether a given pebble has reached its End-of-Life burn-up limit and thereby provide an on-line, automated go/no-go decision on fuel disposition on a pebble-by-pebble basis. This project investigated approaches to analyzing fuel pebbles in real time using gamma spectroscopy and possibly using passive neutron counting of spontaneous fission neutrons to provide the speed, accuracy, and burn-up range required for burnup determination of MPBR. It involved all phases necessary to develop and construct a burn-up monitor, including a review of the design requirements of the system, identification of detection methodologies, modeling and development of potential designs, and finally, the construction and testing of an operational detector system. Based upon the research work performed in this project, the following conclusions are made. In terms of using gamma spectrometry, two possible approaches were identified for burnup assay. The first approach is based on the measurement of the absolute activity of Cs-137. However, due to spectral interference and the need for absolute calibration of the spectrometer, the uncertainty in burnup determination using this approach was found to range from {approx} {+-}40% at beginning of life to {approx} {+-}10% at the discharge burnup. An alternative approach is to use a relative burnup indicator. In this case, a self-calibration method ...
Date: March 30, 2004
Creator: Su, Bingjing & Hawari, Ayman, I.
Partner: UNT Libraries Government Documents Department

Spectroelectrochemical Sensor for Pertechnetate Applicable to Hanford and Other DOE Sites

Description: During the period of this grant several significant milestones have been passed pursuant to designing a fluorescence sensor for pertechnetate (TcO4-). They are as follows: Fluorescence spectroelectrochemistry and less than picomolar limit of detection for a model non-radioactive analyte have been demonstrated. The spectroelectrochemical sensor and associated instrumentation for fluorescence mode of operation have been made, are portable, and easily transported to and used at DOE sites. The sensor has sufficient selectivity for its application to complex samples, even including tank waste, that exist at DOE sites such as the Hanford Site. Pertechnetate has been preconcentrated in sensor films and electrochemically reduced. This is the first critical step in operation of a spectroelectrochemical sensor for TcO4-. New Tc complexes have been made that fluoresce and these complexes have been preconcentrated and electrochemically modulated in a sensor film leading to fluorescence modulation, which is the second critical step in operation of the spectroelectrochemical sensor for TcO4-. We have determined that fluorescence offers a means of dramatically improving the limit of detection. Based on measurements on our new fluorescent complexes of Tc, we estimate the limit of detection for the sensor to be 5 x 10-12M. In related work, we have shown that the sensitivity of the spectroelectrochemical sensor for some metal cations can be improved by forming a metal complex with better optical and electrochemical properties. In addition, some heavy metals can be detected with the spectroelectrochemical sensor by depositing them directly as metals on the sensor surface.
Date: September 28, 2009
Creator: Heineman, William R.; Seliskar, Carl J.; Bryan, Samuel A. & Hubler, Timothy L.
Partner: UNT Libraries Government Documents Department

Spectroelectrochemical Sensor for Technetium Applicable to the Vadose Zone

Description: The general aim of this project is to continue the design and implementation of a new sensor technology that offers the unprecedented levels of specificity needed for analysis of the complex chemical mixtures found at DOE sites nationwide. The new sensor concept combines the elements of electrochemistry, spectroscopy and selective partitioning into a single device that provides three levels of selectivity. The specific goal of this project is the development of a sensor for technetium (Tc) that is applicable to characterizing and monitoring the Vadose Zone and associated subsurface water at the Hanford site. The first goal is a sensor that determines technetium in the chemical form pertechnetate (TcO4 -).
Date: June 1, 2003
Creator: Heineman, William R.; Seliskar, Carl J.; Bryan, Samuel A. & Hubler, Timothy L.
Partner: UNT Libraries Government Documents Department

Solubility of airborne uranium compounds at the Fernald Environmental Management Project

Description: The in vitro volubility of airborne uranium dusts collected at a former uranium processing facility now undergoing safe shutdown, decontamination and dismantling was evaluated by immersing air filters from high volume samplers in simulated lung fluid and measuring the {sup 238}U in sequential dissolution fractions using specific radiochemical analysis for uranium. X rays and photons from the decay of uranium and thorium remaining on the filter after each dissolution period were also directly measured using a planar germanium detector as a means for rapidly evaluating the volubility of the uranium bearing dusts. Results of these analyses demonstrate that two -distinct types of uranium bearing dusts were collected on the filters depending upon the location of the air samplers. The first material exhibited a dissolution half-time much less than one day and was most likely UO{sub 3}. The dissolution rate of the second material, which was most likely U{sub 3}O{sub 8}, exhibited two components. Approximately one-third of this material dissolved with a halftime much less than one day. The remaining two-thirds of the material dissolved with half times between 230 {+-} 16 d and 1350 {+-} 202 d. The dissolution rates for uranium determined by radiochemical analysis and by gamma spectrometry were similar. However, gamma spectrometry analysis suggested a difference between the half times of {sup 238}U and its daughter {sup 234}Th which may have important implications for in vivo monitoring of uranium.
Date: April 4, 2000
Creator: Heffernan, T.E.; Lodwick, J.C.; Spitz, H.; Neton, J. & Soldano, M.
Partner: UNT Libraries Government Documents Department

Spectroelectrochemical Sensor for Technetium Applicable to the Vadose Zone

Description: The general aim of this project is to continue the design and implementation of a new sensor technology that offers the unprecedented levels of specificity needed for analysis of the complex chemical mixtures found at DOE sites nationwide. The new sensor concept combines the elements of electrochemistry, spectroscopy and selective partitioning into a single device that provides three levels of selectivity. The specific goal of this project is the development of a sensor for technetium (Tc) that is applicable to characterizing and monitoring the Vadose Zone and associated subsurface water at the Hanford site. The first goal is a sensor that determines technetium in the chemical form pertechnetate (TcO4 -).
Date: June 1, 2000
Creator: Heineman, William R.; Seliskar, Carl J.; Bryan, Samuel A. & Hubler, Timothy L.
Partner: UNT Libraries Government Documents Department

Spectroelectrochemical Sensor for Technetium Applicable to the Vadose Zone

Description: The general aim of this project is to continue the design and implementation of a new sensor technology that offers the unprecedented levels of specificity needed for analysis of the complex chemical mixtures found at DOE sites nationwide. The new sensor concept combines the elements of electrochemistry, spectroscopy and selective partitioning into a single device that provides three levels of selectivity. The specific goal of this project is the development of a sensor for technetium (Tc) that is applicable to characterizing and monitoring the Vadose Zone and associated subsurface water at the Hanford site. The first goal is a sensor that determines technetium in the chemical form pertechnetate (TcO4 -).
Date: June 1, 2001
Creator: Heineman, William R.; Seliskar, Carl J.; Bryan, Samuel A. & Hubler, Timothy L.
Partner: UNT Libraries Government Documents Department