Sumanta Mukherjee

A study of chemical parameters of the internal gelation based sol-gel process for uranium dioxide

Abstract Internal gelation process is one of the important sol-gel routes for the preparation of spherical particles of fuel materials. Successful preparation of defect free fuel particles has been reported only with a narrow range of feed solution compositions. Investigations have been carried out to study the gelation behaviour of solutions containing uranyl nitrate, hexamethylene-tetramine (hexa) and urea with a view to defining the regions of possible interest to the process. A gelation field diagram has been constructed defining regions where a single phase gel can be readily obtained. A number of compositions from this gelation field diagram have been used for the preparation of UO 2 microspheres and it was observed that good spherical particles could be obtained with uranium concentrations ranging from 0.7 to 1.5 molar. The mole ratio (hexa, urea)/uranium for obtaining good particles decreased with increasing uranium concentration.

Sorption of Pu(IV) on Aliquat-336 impregnated silica-gel

A new ion exchange material prepared by impregnating Aliquat-336 on silica-gel has been investigated for the recovery of plutonium from nitric-oxalic acid solutions. The distribution ratio of Pu(IV) was studied at various concentrations of nitric and oxalic acids. The presence of Al(III) and Fe(III) in the solution, enhances the uptake of Pu(IV). Pu(IV) breakthrough capacities (btc) have been determined using 2.5 ml bed of the ion exchange material column in the absence and the presence of Al(III) and Fe(III) nitrate. The elution behavior of Pu(IV) was also studied using nitric acid solutions containing reducing agents. More than 90% of plutonium could be recovered from nitric-oxalic acid solutions.

Henrian ideality of iron in liquid uranium solvent at high temperatures

Abstract Equilibrium vapor pressures of iron from its dilute solutions in liquid uranium were measured at high temperatures (2250–2750 K). From the Fe vapor pressure data at known compositions ( x Fe ), Henry’s coefficient ( K Fe = p Fe / x Fe ) of the solute was obtained as log K Fe (±0.07) (Pa) =−18975.6(±1098.1)/T+11.15(±0.44) . The behavior of K Fe ( T ) is shown to be marginally different from that of the equilibrium vapor pressures of pure liquid iron ( p Fe °). The partial molar excess Gibbs energy of iron at infinite dilution derived from the behavior is expressed as Δ E G Fe ∞ =−1588+1.25T ( J mol −1 ) . The result is discussed in the light of the quasi-regular solution model and compared with data of the system available in the literature.

Thermodynamic investigation of MF-MgF2 (M = Na, K) system

The molar Gibbs energy of formation of NaMgF3(s) in NaF-MgF2 system and KMgF3(s) and K2MgF4(s) in KF-MgF2 system has been determined using an electromotive force (e.m.f.) technique. For this purpose, fluoride cell has been constructed for each compound using CaF2(s) as the solid electrolyte. From the measured e.m.f. values and required Gibbs energy data available in the literature, ∆fGom(T) for NaMgF3(s), KMgF3(s), and K2MgF4(s) have been calculated. To determine the stability domains of NaMgF3(s), KMgF3(s), and K2MgF4(s), the binary phase diagram NaF(s)-MgF2(s) and KF(s)-MgF2(s) and ternary phase diagram Na-Mg-F2 and K-Mg-F2 have been calculated and chemical potential diagrams of Na-Mg-F-O and K-Mg-F-O system were calculated.

Thermodynamic investigation of LiF-RbF system

The standard molar Gibbs energy of formation of LiRbF2(s) has been determined using an EMF technique. For this purpose, fluoride cell has been constructed using CaF2(s) as the solid electrolyte. From the measured EMF values and required Gibbs energy data available in the literature, ∆fGom(T) for LiRbF2(s) has been calculated. To determine the stability domains of LiRbF2(s), the binary and ternary phase diagram and chemical potential diagrams of Li-Rb-F-O system were calculated by the CALPHAD method and FactSage software.