How do we define the concepts specific activity, radioactive concentration, carrier, carrier-free and no-carrier-added?

Summary

The fission of highly enriched uranium (HEU) by thermal neutrons creates dozens of isotopic products. The Isotope and Nuclear Chemistry Group participates in programs that involve analysis of &ldquo;fresh&apos; fission products by beta counting following radiochemical separations. This is a laborious and time-consuming process that can take several days to generate results. Gamma-spectroscopy can provide a more immediate path to isotopic activities, however, short-lived, high-yield isotopes can swamp a gamma-spectrum, making difficult the identification and quantification of isotopes on the wings and valley of the fission yield curve. The gamma-spectrum of a sample of newly produced fission products is dominated by the many emissions of a very few high-yield isotopes. Specifically, <Superscript>132</Superscript>Te (<Emphasis Type=”Italic”>T<Subscript>1/2</Subscript></Emphasis> = 3.2 d), its daughter, <Superscript>132</Superscript>I (<Emphasis Type=”Italic”>T<Subscript>1/2</Subscript></Emphasis> = 2.28 h), <Superscript>140</Superscript>Ba (<Emphasis Type=”Italic”>T<Subscript>1/2</Subscript></Emphasis> = 12.75 d), and its daughter <Superscript>140</Superscript>La (<Emphasis Type=”Italic”>T<Subscript>1/2</Subscript></Emphasis> = 1.68 d) emit at least 18 gamma-rays above 100 keV that are greater than 5&percnt; abundance. Additionally, the 1596 keV emission from <Superscript>140</Superscript>La imposes a Compton background that hinders the detection of isotopes that are neither subject to matrix dependent fractionation nor gaseous or volatile precursors. Some of these isotopes of interest are <Superscript>111</Superscript>Ag, <Superscript>115</Superscript>Cd, and the rare earths, <Superscript>153</Superscript>Sm, <Superscript>154</Superscript>Eu, <Superscript>156</Superscript>Eu, and <Superscript>160</Superscript>Tb. C-INC has performed an HEU irradiation and also &ldquo;cold&apos; carrier analyses by ICP-AES to determine methods for rapid and reliable separations that may be used to detect and quantify low-yield fission products by gamma-spectroscopy. Results and progress are presented.