Safeguards Analytical Laboratory
Scanning Electron Microscope with Electron Probe Attachment
A great deal of information is contained in small particles which are present in environmental samples. These particles can be pure compounds of U or Pu resulting from nuclear processing operations which took place in the sampling locations. The Clean Laboratory is equipped with a Philips XL-30 scanning electron microscope with wavelength and energy-dispersive X-ray fluorescence detectors, as shown below. The particles of interest are removed from the sample by ashing or ultrasoneration and deposited on a conducting substrate for introduction into the SEM. Under high magnification (1000-5000X) the particles are examined and the backscattered electron signal is used to search for particles containing heavy elements. Heavy particles can then be measured by energy-dispersive X-ray fluorescence spectrometry to give a semi-quantitative elemental analysis. Particles containing U or Pu can be identified in this way; their size and morphology, as well as the presence % other elements will give information about the nuclear process which created them. This type of analysis forms a part of the classical "particle analysis" approach which is applied in certain NWAL laboratories in conjunction with thermal ionization mass spectrometry.
Scanning Electron Microscope