A simple wet chemical method has been developed to synthesize selenium nanoparticles (size 40–100 nm), by the reaction of sodium selenosulphate precursor with different organic acids in aqueous medium, under ambient conditions. Polyvinyl alcohol has been used to stabilize the selenium nanoparticles. The synthesized nanoparticles can be separated from its sol by using a high-speed centrifuge and can be redispersed in aqueous medium with a sonicator. UV-visible optical absorption spectroscopy, X-ray diffraction, energy dispersive X-rays, differential scanning calorimetry, atomic force microscopy, and transmission electron microscopy techniques have been employed to characterize the synthesized selenium nanoparticles.

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To establish the use of TEHDGA/isodecylalcohol/n-dodecane solvent system for actinide partitioning from HLW, the hydrolytic and radiolytic stability of the solvent was investigated. Hydrolysis of TEHDGA with nitric acid at room temperature was not observed. Radiolytic degradation was observed and found to increase with increase in absorbed dose. It was found that the presence of n-dodecane enhances the degradation of TEHDGA whereas isodecyl alcohol, the phase modifier, has no such effect. At gamma-radiation dose as high as 0.2 MGy, no significant loss of TEHDGA was observed. The degradation products were identified by GC-MS, the main products were formed by cleavage of ether and amide bonds of TEHDGA molecule. The extraction behavior of Am(III) at 4.0 M HNO3 does not vary much with increase in absorbed dose, however stripping behavior is affected by the presence of acidic degradation products formed during radiolysis. The findings indicate that the solvent retains its expected extraction and stripping properties up to a high gamma-radiation dose of 0.2 MGy. Irradiated solvent was purified and made suitable for reuse by treating it with 5% w/v Na2CO3 solution, basic alumina and finally by distillation at reduced pressure.

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The present work involves single-phase computational fluid dynamics (CFD) simulations of continuous flow pump-mixer employing topshrouded Rushton turbines with trapezoidal blades. Baffle-impeller interaction has been modeled using sliding mesh and multiple reference frame approaches. Standard k-model has been used for turbulence modeling. Several CFD runs representing different combinations of geometric and process parameters have been carried out. Results of CFD simulations have been used to find out two macroscopic performance parameters of pump-mixer-power consumption and head generated by the impeller. The simulation results have been compared with the experimental data obtained on a pilot-scale setup. Good agreement between CFD predictions and experimental results is observed. In most cases, sliding mesh approach is found to perform better than multiple reference frame approach. Details from CFD simulations have been used to have an insight into the pumping action of the impeller.