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Abstract  

Red-oil is a mixture of nonspecific composition consisting of extractant, degradation products, nitrated solvent and unidentified red-coloured nitro-organics. Red-oil formation is coupled with decomposition of extractant and diluent into gases of explosive nature. If ignited or incinerated, these gases may cause rapid pressurization and endanger the integrity of containment. Such an event occurred at Tomsk-7 facility in 1993. To ensure safe operation, red-oil formation has to be avoided in the fuel cycle facilities by a careful combination of several independent measures like strict control over temperature, limiting organic entrainment in the aqueous streams (which are to be concentrated by evaporation) and control over acidity of aqueous phases. Since tri-iso amyl phosphate (TiAP) has much lower aqueous solubility as compared to TBP, it is visualized as alternate solvent for PUREX process. In this work, TiAP red-oil was synthesized and characterized.

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Abstract  

Miniature annular centrifugal contactors are nearly perfect for shielded hot-cell applications during flowsheet evaluation but these contactors require complex maintenance of electrical drive-motors during radioactive experiments. To reduce the number of electrical drives in the shielded cell, an indigenous design of miniature Taylor Couette (TC) mixing based countercurrent differential extraction column has been developed. In this paper, results of mass transfer experiments for an indigenously developed TC column with 30% TBP/aqueous nitric acid solutions are reported. The developed device worked perfectly in counter–current differential mode and demonstrated equivalence to multiple-extraction stages while working with a single electrical drive. The developed TC unit demonstrated operation with a reduced efficiency without flooding even in absence of rotor rotation. This observation is a vital step towards designing of robust contactors, which do not flood during temporary power failure or failure of drive mechanism.

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Abstract  

Thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) investigations were carried out on gamma irradiated SrBPO5 samples doped with CeO2 and co-doped with CeO2 and Sm2O3. On gamma-irradiation at room temperature, BO3 2–, O2 and O radicals were produced. It was seen that the O radical ion disappeared in the sample annealed at 500 K. It is proposed that the recombination between trapped electrons and O radical ions results in transfer of recombination energy to the impurity centre Ce3+ resulting in TSL glow peak at 485 K. In the case of co-doped samples energy transfer occurs between Ce3+ to Sm3+ resulting in increase in the intensity of glow peak at 485 K.

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Abstract  

Thermally stimulated luminescence (TSL), electron paramagnetic resonance (EPR) and photo-acoustic spectroscopy (PAS) techniques were used to investigate the radiation induced centers in polycrystalline LaBa2F7 containing trace amounts of other rare-earths particularly Gd3+ and Sm3+. The TSL glow curve of LaBa2F7 after g-irradiation to a dose of 3 kGy had shown a weak TSL glow peak at 390 K and a much stronger one at 495 K. The EPR spectra of the g-irradiated LaBa2F7 samples showed the presence of O- and O2 - ions. Temperature dependence study of the EPR spectra showed that the thermal destruction of O- ion occurs in the 460-490 K temperature range. In g-irradiated samples, O- and F-centers were identified by PAS. The correlation of EPR and PAS results indicate that the prominent TSL glow at 495 K is associated with the thermal destruction of O- radical ion. The trap parameters viz. trap depth and frequency factor have been determined from TSL data.

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Abstract

This paper analyses the growth pattern of Nanoscience and Nanotechnology literature in India during 1990–2009 (20 years). The Scopus international multidisciplinary bibliographical database has been used to identify the Indian contributions on the field of nanoscience and nanotechnology. The study measures the performance based on several parameters, country annual growth rate, authorship pattern, collaborative index, collaborative coefficient, modified collaborative coefficient, subject profile, etc. Further the study examines national publication output and impact in terms of average citations per paper, international collaboration output and share, contribution and impact of Indian Institutions and impact of Indian journals.

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Abstract  

Tri-iso-amyl phosphate is an alternate solvent, proposed in literature as an alternate to the PUREX/UREX solvent tri-n-butyl phosphate for better physical properties. Its PVT properties and accurate expression for estimation of its vapour pressure are not available in the literature. Recently PVT properties of TiAP were estimated by authors and its vapour pressure was measured in a ASTM certified vapor pressure measurement system at temperatures ranging from 273.15 to 373.15 K. In this paper, results of these studies are presented.

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Abstract  

Phenyl trifluoromethyl sulfone (FS-13) is a polar diluent, proposed in literature as an alternate to nitrobenzene, in UNEX/HCCD-PEG processes for better physical properties. Its PVT properties and accurate expression for estimation of its vapour pressure are not available in the literature. Recently PVT properties of FS-13 were estimated by authors and its vapour pressure was experimentally measured at temperatures ranging from 263.15 to 363.15 K. In this paper, results of these studies are presented.

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Abstract  

Reversed TALSPEAK (RT) Solvent [0.3 M di-(2-ethyl hexyl) phosphoric acid or D2EPHA in 0.2 M TBP in normal paraffinic diluent] is used as extractant in partitioning of lanthanides and actinides in post-UREX process flow sheets. There is no experimental data available in literature describing pressurization either due to the thermal decomposition or the reaction of RT solvent with nitric acid at elevated temperatures. Experiments were conducted for heating of RT solvent and acid equilibrated RT solvent under closed-vent adiabatic conditions. During these experiments, considerable pressurization was observed. In this paper, results of these experiments are discussed in detail.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Shekhar Kumar
,
S. Balasubramonian
,
D. Sivakumar
,
U. Mudali
, and
R. Natarajan

Abstract  

Di-(2-ethyl hexyl) phosphoric acid (hereafter referred as D2EHPA) is an important solvent for solvent extraction industry. It is also used in nuclear solvent extraction as a solvent for TALSPEAK and REVERSED TALSPEAK processes for actinide (III)–lanthanide (III) separation. Its PVT properties are not available in literature. In this work, group-contribution approach was used to predict its PVT properties as well as selected physical properties like normal boiling point.

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Abstract  

Phenyl trifluoromethyl sulfone (FS-13) is an inert diluent used in HCCD/PEG process for isolation and recovery of cesium and strontium from highly radioactive raffinate waste. There is no experimental data available in open literature describing pressurization due to the thermal decomposition of FS-13 at elevated temperatures. Experiments were conducted for determination of flash point and heating of FS-13 under pressurized closed-vent conditions in an adiabatic calorimeter. During adiabatic experiments, negligible pressurization was observed.

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