Authors:P. Kalsi, B. Tomar, K. Ramakumar, and V. Venugopal
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.
Authors:S. Kumar, N. Rawat, B. Tomar, V. Manchanda, and S. Ramanathan
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.
Authors:Sharayu Kasar, Sumit Kumar, Aishwarya Kar, K. Krishnan, N. Kulkarni, and B. Tomar
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).
Authors:M. Murali, D. Raut, D. Prabhu, P. Mohapatra, B. Tomar, and V. Manchanda
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.
Authors:S. Kumar, N. Rawat, A. Kanekar, B. Tomar, V. Manchanda, M. Sonavane, N. Sonar, and K. Raj
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.
Authors:M. Murali, A. Bhattacharayya, D. Raut, A. Kar, B. Tomar, and V. Manchanda
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