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Abstract  

Application of power ultrasound in chemical processes is recognized as an effective tool to solve many industrial problems encountered in processes involved in nuclear industry, particularly, digestion and leaching steps. In addition, problems related to radiological safety are the most important factors to be considered, when handling radioactive materials. Sonochemical processes, due to relatively low temperature operations, are attractive in this regards. Further they are eco-friendly and economical as well. Hence, sonochemical studies were taken up for the removal of uranium from fluoride containing matrix. Dissolution studies were carried out in nitric acid medium, in a 5 L capacity tank type sono-reactor, operating at frequency and power of 22 ± 3 kHz and 150 W respectively. The parameters studied were concentration of HNO3, temperature of water-bath, choice of purged gas (air/oxygen) and flow rate of purged gas passed. Experiments were also carried out to study the amount of fluoride matrix dissolved. Enhancement with US was 76 to 91 % for U removal from MgF2 slag in 2 M HNO3. The prime advantage achieved is the reduction in the reaction time. Other advantages are minimizing labor, remotisation of operations to reduce radiation exposure, use of less acid and accordingly lesser effluent for treatment before disposal.

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Abstract  

Sorption of technetium on hematite colloids, at varying pH (3–10), has been studied in absence and presence of humic acid using 95mTc-96Tc radiotracers. Technetium was found to be weakly sorbed on hematite at lower pH (<5) values, while no sorption was observed at higher pH values. Humic acid was found to have no effect on the sorption of technetium on hematite under aerobic conditions, while at lower pH values small reduction was observed which was attributed to the reduced zeta potential of the hematite colloids owing to the strong sorption of humic acid.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Sharayu Kasar, Sumit Kumar, Aishwarya Kar, K. Krishnan, N. Kulkarni, and B. Tomar

Abstract  

Sorption of Eu(III), an analogue of trivalent actinides (Am, Cm), by amorphous titania as well as different crystalline phases of titania, namely anatase and rutile, have been studied as a function of pH, using 154Eu (half life = 8.8 yrs, Eγ = 123,247 keV) as a radiotracer. The objective of this study was to investigate the effect of the crystalline phase of the titania on their sorption behaviour towards the metal ion. Amorphous titania was prepared by organic route and was converted into anatase and rutile by heating at elevated temperatures based on the differential thermal analysis studies. Eu(III) sorption by all forms of titania rises sharply with the pH of the suspension, with the sorption edge shifting to higher value in the order; amorphous < anatase < rutile. However, the normalization of the sorption data to the surface area of the sorbents resulted in the overlapping of the sorption curves for amorphous and anatase phases, with the data being higher for rutle in the lower pH region, indicating the effect of the crystal phase on sorption behaviour of Eu(III).

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Abstract  

Efficacy of chlorinated cobaltdicarbollide in a modified diluent, 20% nitrobenzene in xylene was tested for the extraction and recovery of Cs from simulated high-level waste (HLW) solutions generated from PHWR-fuel reprocessing. Concentration of the reagent, composition of the diluent, numbers of contacts, the nature of stripping agents are some of the parameters optimized for the complete removal of Cs from such waste solutions. The above solvent extraction procedure can be applied to genuine HLW solutions for effective reduction of the dose due to Cs so that HLW can be handled in fume hoods for its characterization.

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Abstract  

Diffusion of sodium in Mn and Ti bearing sodium borosilicate glass used for the immobilization of the high level waste at the Waste Immobilization Plant, Tarapur has been studied by heterogeneous isotopic exchange using 24Na as the radiotracer for sodium. The temperature dependence of the self-diffusion coefficient of sodium in the glass was found to follow Arrhenius equation below the glass transition temperature.

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Abstract  

The high level waste (HLW) generated from the reprocessing of the spent fuel of pressurized heavy water reactor has been characterized for the minor actinides. The radiation dose of the waste solution was reduced by radiochemical separation of cesium from HLW by solvent extraction with chlorinated cobalt dicarbollide dissolved in 20% nitrobenzene in xylene. Minor actinides (Np, Pu, Am, Cm) in the high level waste were assayed by alpha spectrometry following radiochemical separation. The gross alpha activity determined by liquid scintillation agrees well (within 10%) with the cumulative quantities of actinides determined by alpha spectrometry.

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