Search

Uranium is an indispensible material for the generation of electricity by nuclear reactors. The depletion of primary uranium ore bodies has rekindled interest in recovering uranium from other sources to bridge the gap between supply and demand. Rock phosphate is an important secondary source of uranium that offers dual advantages not only to provide uranium for energy production, but also prevents the soils and crops from radioactive contamination. The present review is the compilation of literature reports on the processes for recovery of uranium from phosphoric acid origin by different techniques with an emphasis on solvent extraction technology. The pre- and post-treatment of phosphoric acid were also highlighted together with a history of different extractant systems employed for uranium recovery. Recent developments in evaluating the new extractant molecules for effective separation of uranium from phosphoric acid solution have also been elaborated. With an eye on the different extractants or solvent systems that were studied earlier for uranium extraction from phosphoric acid, factors affecting the extractant moiety are also reviewed to provide insight upon emerging novel extractants to be explored in the future endeavor of solvent designers or synthesizers. [ABSTRACT FROM AUTHOR]

A model is developed to predict the in-reactor dimensional changes of the pressure tube materials in Indian pressurized heavy waterpower reactors (PHWRs) using artificial neural networks (ANNs). The inputs of the ANN are the alloy composition of the tube (concentration of Nb, O, N, and Fe), mechanical properties (yield strength, ultimate tensile strength, and percentage elongation), tube thickness, temperature, and fluence whereas axial elongation is the output. Measured elongation data from various tubes used in Indian PHWRs at Rajasthan Atomic Power Station (RAPS 4) are employed to develop the model. A three-layer feed-forward ANN is trained with the Levenberg-Marquardt training algorithm. It has been shown that the developed ANN model can efficiently and accurately predict the axial elongation of pressure tubes. The results show the high significance of Fe concentration and irradiation fluence in determining axial elongation. [ABSTRACT FROM AUTHOR]

The cyclic stress-strain behaviour of two microalloyed steels with different microstructures has been characterised at room temperature under strain controlled low cycle fatigue. The cyclic stress-strain curve in the double logarithmic plot shows a linear relation for both steels. A transition of the cyclic stress-strain curve from softening to hardening with increasing strain amplitude has been observed with respect to the corresponding tensile curve. The strain amplitude for the onset of cyclic softening to hardening transition has been found to be dependent on grain size. The strain lifetime behaviour, estimated from modified universal slopes equation, shows similar trends as Nb or V bearing microalloyed steels. The cyclic characteristics of the two microalloyed steels have been compared with corresponding predeformed state carried out under stress controlled conditions. While, cyclic saturation was observed in case where the extent of predeformation was within the Lüders strain, cyclic softening occurred when it exceeded the Lüders strain. It has been attempted to provide a mechanistic understanding of the differences in the cyclic behaviour of the two steels owing to the microstructure and predeformation. [ABSTRACT FROM AUTHOR]

Imino diacetamide styrene divinyl benzene resin was evaluated for separation of palladium from simulated high level liquid waste (HLLW). The kinetics of sorption was found to be fast, and the kinetic data were fitted well to the pseudo-second-order kinetics model. Very highKd(~103) were obtained for Pd for feed solutions having acidity from 0.25 M to 4.0 M HNO3. The loading studies of the resin showed the maximum sorption capacity of 54 mg/g. Back extraction studies showed that sorbed Pd can be effectively back extracted using 0.01 M thiourea in 0.2 M HNO3. Studies with simulated HLLW showed preferential sorption of Pd over other metal ions. [ABSTRACT FROM PUBLISHER]