Detection of Pu&Np Trace Amounts in Solutions
Trace Amount of Plutonium and Neptunium Detection in Solutions Using Laser Spectroscopy Methods
Tech Area / Field
- ENV-MIN/Monitoring and Instrumentation/Environment
3 Approved without Funding
Khlopin Radium Institute, Russia, St Petersburg
- University of Manchester / Centre for Radiochemistry Research, UK, Manchester\nLawrence Livermore National Laboratory / Chemistry and Material Science, USA, CA, Livermore\nJohannes Gutenberg-Universitaet Mainz, Institute of Physik, Germany, Mainz
Project summaryLaser spectroscopy methods provide excellent possibilities for trace actinide detection in environmental samples. The high selectivity and sensitivity of laser spectroscopy methods open new possibilities for trace actinide analysis in environmental samples, determination of actinide valence states and type of molecules containing actinide. Such properties of laser spectroscopy methods are very important for the solution of both applied and fundamental problems. A particularly promising direction in the application of laser spectroscopy methods is the use of liquid media and the detection of trace actinide amounts in solutions. Detection of trace amounts of plutonium and neptunium in environmental samples with determination of actinide valence states and type of molecules containing actinide is a very important problem. Alpha-spectroscopy methods have a high sensitivity of detection (for 239Pu the limit of detection –LOD =10-12 M - 10-13 M (mol/l)) but they do not allow one to determine the actinide valence state and type of molecule containing actinide. What is more, the analysis is very time consuming. Laser spectroscopy methods are faster than alpha spectroscopy. Today, the most sensitive laser spectroscopy methods (for example Time Resolved Laser Induced Fluorescence – TRLIF) for the detection of some actinides have sensitivity LOD =10-12 – 10-13M. In such methods the photoluminescence of actinides is used in the detection process. Unfortunately plutonium and neptunium do not give photoluminescence in solution and less sensitive laser spectroscopy methods are used: traditional absorption spectroscopy (LOD = 10-5M), Laser Induced Photoacoustic Spectroscopy (LIPAS) LOD = 10-7M and Thermal Lensing Spectroscopy (TLS) LOD = 10-6M. All these methods have a lower sensitivity than laser spectroscopy methods with luminescence registration, but these methods allow one to obtain information about actinide valence states and type of molecules containing actinides, and they are widely used for these purposes.
The authors observed for the first time the chemiluminescence of solutions containing plutonium, excited by pulse laser radiation and they studied the kinetics of this chemiluminescence. Today, chemiluminescence effects are widely using in biology and medicine for trace amount detection of different substances with a detection limit up to LOD = 10-11M and it is possible to determine the element valence states and type of molecules. For the first time we have demonstrated the application of chemiluminescence effects for trace amount detection of plutonium and other actinides in solutions and the possible application of chemiluminescence effects in radiochemistry.
This project is devoted to the optimization of technology based on the use of chemiluminescence effects and the application of such technology for plutonium and neptunium trace amount detection in solutions with simultaneous determination of actinide valence states and type of molecules containing actinides. The optimized technology will be applied for actinide trace amount detection in environmental samples. During the project works the existing experimental set-up will be modernized and chemiluminescence technology for trace amount actinide detection will be optimized. Such optimization includes: determination of optimal laser radiation parameters, selection of an optimal scheme of actinide excitation by laser radiation, determination of the optimal composition of solutions, an optimal scheme for chemiluminescence registration selection, optimal time intervals for chemiluminescence excitation and registration determination for application of methods using the time resolution technique. Experiments will be carried out both with model and real environmental samples. It is planned to use previous results and experience for technology optimization and to reach plutonium and neptunium detection in solutions up to a limit of LOD - 10-10M - 10-12M, i.e. 4 – 5 orders of magnitude more sensitive than the LIPAS and TLS methods used today. The optimized technology will also be able to determine the actinide valence states and type of molecules containing actinides, similar to LIPAS and TLS methods, but to a higher degree of sensitivity.
The developed technology will be applied for the solution of two tasks. The first task is the trace detection of plutonium and neptunium in different samples. The second is the determination of the valence states of plutonium and neptunium while obtaining information about the type of molecules containing actinides. Other technologies, used today for plutonium and neptunium trace detection, do not have such unique combinations of high sensitivity and possible valence state determination. A new approach to the problem is proposed here, using high sensitivity and high selectivity laser spectroscopy in combination with chemiluminescence effects, to complete the next major step in trace actinide detection and determination of actinide properties, avoiding complicated procedures and facilitating the detection of plutonium, neptunium and other actinides in different samples, using simple automated procedures.
The developed technology will be applied for trace actinide analysis in environmental samples.
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