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Development of Method for Actinides Determining

#2741


Development of Express and High-Sensitive Liquid Scintillation Alpha-Spectrometric Method of Determining Actinides in Process Solutions from Radiochemical and Isotope Production and in Environmental Samples

Tech Area / Field

  • CHE-ANL/Analytical Chemistry/Chemistry
  • ENV-MIN/Monitoring and Instrumentation/Environment

Status
3 Approved without Funding

Registration date
20.03.2003

Leading Institute
All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow

Collaborators

  • Pribori Oy / Pribori Oy - Moscow Representation, Russia, Moscow\nCanberra Industries / Moscow office, Russia, Moscow

Project summary

The goal of the Project is to develop a novel liquid scintillation alpha-spectrometric method and technical tools to conduct on express and high sensitivity determination of actinides available in process solutions and environmental samples. The method is based on a novel methodologic approach according to which to decompose alpha-spectra into constituent components use is made of pre-established regularities inherent in the liquid scintillation alpha-spectrometry and to identify the alpha-spectra of samples having the unknown nuclide composition a sample is spiked and the position of the label alpha-peak is found.

The technical tools comprise a newly designed detection unit, a software to deduct the alpha-spectrum of a sample from the spectrum of a sample containing an isotopic label and a program to decompose the alpha-spectra and compute the activity of nuclides available in the composition of samples being analyzed.

The traditional alpha-spectrometric method that uses a silicon semiconductor detector is usually applied to determine actinides and is labour – and time consuming (it takes some 20 hours to prepare a single sample) because thin – layer counting specimens have to be prepared by the electrochemical deposition method.

The project suggested method which put into practice shall keep the advantages of the liquid scintillation alpha-spectrometry (namely, high expressness, low labour consumption and low measurement limit) and eliminate its faults (low level of spectral resolution and difficulties of alpha-spectra identification.

The work already carried out to assess the potentiality and metrologic characteristics of the method offered has demonstrated that the lower limit of measurement shall be of the order of 1 × 10-3 Bq/sample, the accuracy of 5 – 15 %, the spectral resolution limit of 50 – 100 keV (in contrast to 300 – 350 keV for the series alpha-spectrometer “PERALS”), the sample preparation time of 0.5 – 1 h ( in contrast to 10 – 20 h in the traditional method), the analyzed sample volume of 1 – 2 ml (compare to 2 – 5 l), the number of nuclides determined at a time is up to 10.

Scope of Project efforts:

- develop an alpha-spectra identification method that involves an introduction of a label (the known radionuclide) into a sample and subtraction of a sample spectrum from the spectrum of a sample containing a label using a software;

- study regularities inherent in liquid scintillation alpha-spectrometry and, specifically, study the shape of the alpha-peak contours and dependence of the interlocation of the alpha-peaks of various nuclides and their half-widths upon the extent of light absorption in liquid scintillator solution;

- develop a software to decompose alpha-spectra of samples into constituent components using the established regularities and compute activities of radionuclides available in samples;

- determine metrologic characteristics of the method;

- adapt the method to the series alpha-spectrometer “PERALS”.


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