Radionuclides actinides

Distribution ratios and transport were carried out on real HAW arising from dissolution of a mixed oxide of uranium and plutonium (MOX) fuel (burnup 34,650 MW d/tU), where uranium and plutonium have been previously extracted by TBP.86 The experiments were performed in the CARMEN hot cell of CEA Fontenay aux Roses with two dialkoxy-calix[4]arene-crown-6 derivatives (diisopropoxy and dini-trophenyl-octyloxy). High cesium distribution ratios were obtained (higher than 50) by contacting the HAW solution with diisopropoxy calix[4]arene-crown-6 (0.1 M in NPHE). Moreover, the high selectivity observed with the simulated waste was confirmed for most of the elements and radionuclides (actinides or fission products Eu, Sb, Ce, Mo, Zr, and Nd). The residual concentration or activity of elements, other than cesium, was less than 1% in the stripping solution, except for iron (2%) and ruthenium (8%) the extraction of these two cations, probably under a complexed... 

A general review of actinide transport on colloids, and how this may relate to radionuclide transport studies, is provided by Ivanovich (1991). It has been found that colloids can carry a large fraction of U (Dearlove et al. 1991). Due to the greater reactivity. 

NevissiAE. 1992. Measurement of actinides and long-lived radionuclides in large coral samples. J Radioanal Nucl Chem 156(2) 243-251. 

Popplewell DS, Boocock G. 1967. Distribution of some actinides in blood serum proteins. In Kombeig HA, Norwood WD, eds. Diagnosis and treatment of deposited radionuclides. Amsterdam Excerpta Medica Foundation, 45-55. 

SikovMR. 1987. Placental transfer of the actinides and related heavy elements. In Age-related factors in radionuclide metabolism and dosimetry. Netherlands Kluwer Academic Publishers, 303-314. 

Popplewell, D. S. AND Boocock, G. (1967). Distribution of some actinides in blood serium proteins, page 45 in Diagnosis and Treatment of Deposited Radionuclides, Monographs in Nuclear Medicine and Biology No. 2, Romberg, H. A. and Norwood, W. D., Eds. (Excerpta Medica Foundation, Amsterdam). 

The potentially important role of colloidal species in the geochemical behaviour of the polyvalent actinides has nevertheless been stated by various authors (e.g., Kim 1991 Kersting et al. 1999). The present paper discusses the role of colloids on the release of radionuclides from a nuclear waste repositoiy with regard to the processes leading to (1) colloid generation and stability (2) radionuclide interaction with aquatic colloids and (3) colloid-borne radionuclide migration. 

Much stronger kinetic stabilization can be expected for processes leading to the inclusion of radionuclide ions into the colloid structure (Fig. 7, lower part). Spectroscopic indications for such processes have indeed been found again by TRLFS for the Cm(III) interaction with colloidal and particulate amorphous silica, calcite and CSH phases (Chung et al. 1998 Stumpf Fanghanel 2002 Tits et al. 2003). The incorporation of actinide ions into colloidal precursor clay phases has been recently investigated as a possible mechanism in natural... 

Actinides were determined at the ultratrace level in moss samples collected from the eastern Italian Alps (1500 m a.s.l.). The frozen samples were cut into 1-2 cm sections and analyzed separately to obtain the distribution curves of the vertical concentrations. For plutonium and americium isotope analysis, 1-2 g of the samples were ashed, leached, separated with respect to analytes and analyzed by alpha spectrometry and LA-ICP-MS after the plutonium or americium had been electroplated on a stainless steel disk.23 Estimated limits of quantification of LA-ICP-MS for actinide radionuclides deposited on stainless steel plates after chemical separation are summarized in Table 9.45. For most of the long-lived radionuclides in moss samples, lower limits of determination were found at the 10 15gg 1 concentration level compared to those of a - spectrometry 23... 

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