Mass of radionuclides

A radioactive material is defined as any material with specific activity. In this context, specific activity means the activity per unit mass of radionuclide is essentially uniformly distributed, which is the activity per unit mass of material. 

In determining the specific activity of a material in which radionuclides are distributed, the entire mass of that material or a subset thereof, i.e. the mass of radionuclides and the mass of any other material, needs to be included in the mass component. The different interpretations of specific activity in the definition of LSA material (para. 226) and in Table II. 1 should be noted. 

Specific-activity—Radioactivity per unit mass of material containing a radionuclide, expressed, for example, as Ci/gram or Bq/gram. 

Parker, F. L., Churchill, M. A., Andrew, R. W., Frederick, B. J., Carrigan, P. H. Jr., Cragwall, J. S. Jr., Jones, S. L., Struxness, E. G. and Morton, R. J. (1966). Dilution, dispersion and mass transport of radionuclides in the Clinch-Tennessee Rivers, page 35 in Disposal of Radioactive Wastes into Seas, Oceans and Surface Waters, IAEA Publication No. STI/PUB/126 (International Atomic Energy Agency, Vienna). 

Specific activity The ratio between activity (in number of disintegrations/min) and the mass (in grams) of material giving rise to the activity. Biological hazards of radionuclides are directly related to their specific activity and are expressed in Bq/kg mass. 

Fig. 8. Radionuclide migration studied in a granitic shear zone at the Grimsel test site, Switzerland (injection flow rate 10 mL/min extraction flow rate 150 mL/min, dipole distance 2.3 m). Am(III), Pu(IV) and Th(IV) are co-eluted with the colloids grey vertical lines indicate maxima of breakthrough curves (Geckeis et al. 2003). In order to allow a direct comparison of breakthrough curves, the colloid and radionuclide concentrations (c in mg/mL) in the extracted water samples are normalized to the total injected mass of individual colloid or radionuclide tracers (mn in mg).

Conventional radiochemical methods for the determination of long-lived radionuclides at low concentration levels require a careful chemical separation of the analyte, e.g., by liquid-liquid, solid phase extraction or ion chromatography. The chemical separation of the interferents from the long-lived radionuclide at the ultratrace level and its enrichment in order to achieve low detection limits is often very time consuming. Inorganic mass spectrometry is especially advantageous in comparison to radioanalytical techniques for the characterization of radionuclides with long half-lives (> 104 a) at the ultratrace level and very low radioactive environmental or waste samples. 

Henry et al.33 reported that improvements in quadrupole ICP-MS resulted in ag mass detection capability. Consequently the analysis of radionuclides with shorter half-lives is also possible. In Table 9.38 the detection limits of several mass spectrometric techniques for the determination of long-lived radionuclides are compared. 

The radioactive products of the Sedan detonation were present in the fireball and mixed into the mass of earth moved by the detonation. As the fireball cooled, condensation occurred, and radioactivity in various forms was scavenged by earth materials entering the cloud. Apparently a large fraction of the residual tritium from the explosive was present in the cloud as tritiated steam. This tritiated water was entrained by the ejecta as it fell onto the surrounding land surface, and the resulting postshot substratum thus contained a most significant and mobile tracer. Other radionuclides scavenged by the ejected earth mass constitute another type of tracer for Sedan ejecta. 

The determination of mass and radionuclide distributions as a function of particle size and type. 

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