Actinides and Other Alpha‐Emitters, Determination of

Abstract

To assay an actinide or other α‐emitter at the low concentrations encountered in many environmental samples necessitates chemical separation of the actinide of interest from the bulk matrix, purification by the elimination of other interferants, mounting onto a suitable substrate for counting, and quantification by radiometric, mass spectrometric or other means. In this contribution, the chain of analysis from sampling to counting is critically reviewed and many of the most important pitfalls and sources of error are highlighted. Specifically, the pretreatment, preconcentration, separation and purification steps required for the assay of thorium, uranium, neptunium, plutonium, americium and curium in a wide range of environmental matrices are examined in detail. Emphasis is given to the need for appropriate radiochemical yield monitors and to the practical application of ion exchange, solvent extraction and extraction chromatography in the purification of these elements. This is complemented by a description of methods for the preparation of quality sources suitable for counting by α‐spectrometry, liquid scintillation α‐spectrometry and mass spectrometry. In addition, an overview is given of the operational principles and systems used in α‐radiometry and mass spectrometry, including a discussion of the practical limits of detection and quantitation achievable with these systems. Finally, the importance of traceability and good quality assurance in precision actinide assay is emphasized.

The Solid Speciation of 90Sr, 137Cs, 226Ra, 238U and 239,240Pu in Surface Soils from Sites of Special Radiological Interest in Kazakhstan

“…The plutonium content of each fraction was similarly determined by alpha spectrometry following separation and purification by ion-exchange [18], and electrodeposition, as described above. Chemical recoveries were determined using a NIST-certified 242 Pu standard reference solution as yield monitor and were typically in the range 60-95%.…”