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3.9.8 Other techniques

In cases where sites are contaminated with high concentrations of radioactive materials, gross alpha, beta and gamma measurements are able to produce a rough picture about the total inventory of contaminants and the extent of the contamination. If more detailed, qualitative and/or quantitative information is required, radiochemical methods will need to be applied. Due to the nature of radiochemical techniques, they allow only one or a small group of isotopes to be determined simultaneously. Depending on the method and detection system used, radiochemical methods may provide limited information about the elemental composition, especially in case of uranium and the actinides. For radionuclides with half lives longer than about 200 years, non-radiometric techniques can be more sensitive than their radiometric counterparts.
Non-radiometric techniques to be considered are:

  • Glow discharge mass spectrometry is a technique that does not require dissolution of the sample and can measure in a described configuration a considerable number of elements in the periodic system with one measurement. The sensitivity reaches the parts per billion (ppb) level.
  • Real time aerosol mass spectrometry performs qualitative elemental and isotopic characterisation from aerosols in air with sizes below 1 micrometer.
  • Inductively coupled plasma mass spectrometry (ICPMS) can be used to detect trace levels of stable or long-lived radionuclides. In this context, it is particularly useful for assay of isotopes such as 36Cl, 129I and actinides.
  • High performance ion liquid chromatography on-line with inductively coupled plasma mass spectrometry for qualitative and quantitative characterization of all uranium and actinide isotopes of interest in sample materials. In cases where only qualitative information is required, the uranium, plutonium and americium isotopic compositions can be determined in a single sample run.
  • Many other standard chemical techniques may be found useful, particularly those aimed at determination of trace elements.
  • X-ray fluorescence has been used for determination of many materials including uranium and plutonium, as well as for non-radioactive elements such as lead.

Non-radiometric techniques are not described in detail, but their possible application should be considered when it is necessary to determine a very long-lived radionuclide.