R. Rajeev

Indira Gandhi Centre for Atomic Research

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K. A. Venkatesan

Sri Ramakrishna Institute of Paramedical Sciences

K. Ananthasivan

Indira Gandhi Centre for Atomic Research

P. Vishnu Anand

Indira Gandhi Centre for Atomic Research

N. Desigan

Indira Gandhi Centre for Atomic Research

P. Velavendan

Indira Gandhi Centre for Atomic Research

N. K. Pandey

Indira Gandhi Centre for Atomic Research

Saroj K. Panda

Indira Gandhi Centre for Atomic Research

Satyabrata Mishra

Indira Gandhi Centre for Atomic Research

Vivek Mishra

Homi Bhabha National Institute

U. Kamachi Mudali

Central Ground Water Board

Cooperative Institutions

Indira Gandhi Centre for Atomic Research

Homi Bhabha National Institute

Bhabha Atomic Research Centre

Institute of Chemical Technology

Department of Atomic Energy

SRM Institute of Science and Technology

Sri Venkateswara University

Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology

University of Mumbai

Indian Institute of Technology Bombay

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Modeling and simulation of diluent recovery unit in PUREX solvent regeneration system

Progress in Nuclear Energy (2017)

P. Vishnu Anand R. Rajeev P. Velavendan N. K. Pandey U. Kamachi Mudali

PUREX

Diluent

Subcooling

10.1016/j.pnucene.2017.01.011

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Citations (5)

Numerical Analysis of Solid–Liquid Disengagement in a Continuous Precipitator Relevant to Plutonium Reconversion

Lecture notes in mechanical engineering (2024)

Saroj K. Panda P. Vishnu Anand Vivek Mishra R. Rajeev K. A. Venkatesan

Oxalic Acid

Nuclear reprocessing

10.1007/978-981-99-6343-0_23

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Experimental investigation of sedimentation behaviour using cerium oxalate particles in oxalic‐nitric acid medium

Asia-Pacific Journal of Chemical Engineering (2021)

Saroj K. Panda P. Vishnu Anand R. Rajeev K. A. Venkatesan K. Ananthasivan

Abstract Settling behaviour of cerium oxalate particles in the solution was investigated by batch settling tests. The settling curves were experimentally generated for different overall solid fractions ( OSF ), initial dispersion height ( h t ) and batch cylinder diameter ( d ). Settling curves were analysed to obtain bulk settling velocity, and it was observed that bulk settling velocity decreases with increase in OSF and remains unchanged with change in cylinder diameter. Bulk settling velocity was found more or less same with increase in initial suspension height as long as the OSF was maintained constant. The particle settling time is delayed at higher OSF due to dense particle population as the movement of one particle is affected by the presence of neighbouring particle. Regression analysis of the settling curve was performed to identify suitable mathematical model. Two parameter based model was found to represent the settling curve better in comparison to three and five parameter based models. Applicability of dispersion number for characterizing the solid–liquid suspension was checked, and it was found that the dispersion number was not unique for the solid‐liquid system where it was influenced by the operating and dimensional parameters.

Settling

Suspension

Particle (ecology)

Sedimentation

10.1002/apj.2731

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Citations (5)

Pressure drop across vortex diodes: Experiments and design guidelines

Chemical Engineering Science (2008)

Amol A. Kulkarni Vivek V. Ranade R. Rajeev S. B. Koganti

10.1016/j.ces.2008.10.060

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Citations (42)

Investigating Sedimentation Process in the Plutonium Reconversion Step of Spent Fuel Reprocessing Using Eulerian Two-Fluid Simulations and Experimental Verification

SSRN Electronic Journal (2022)

Saroj K. Panda Vivek Mishra Vishnu Anand P R. Rajeev K. A. Venkatesan

Batch settling simulations were used to investigate the sedimentation behaviour of cerium oxalate particles (surrogate to plutonium) in the nitric-oxalic acid solution which will be useful for the design of continuous process equipment used in plutonium reconversion. The effects of overall solid fractions (OSF), initial dispersion height (ht), and cylinder diameter (d) on the settling curve were investigated and comparisons were made with experimentally obtained results. Further, the solid volume fraction distributions of cerium oxalate obtained by varying the dispersion height, OSF, and cylinder diameter were numerically analysed. The movement of solid phase (particles) in the solution is affected by the presence of neighbouring particles, which leads to deceleration in the settling time of the particles with increasing OSF. The analysis of pressure variation was done by varying the ht, d, and OSF. The bulk settling velocity was computed for different OSF and ht values. It was observed that the settling velocity was reduced with an increase in OSF and was independent of d. The changes in bulk settling velocity with time helped to explain the separation process in detail. The vorticity and velocity fluctuations obtained along the height of the batch settler confirmed the random motion of particles during settling. The clear liquid collected at the top region of the batch cylinder was investigated as a function of sedimentation velocity which will be helpful for any future design optimization of a continuous separation equipment.

Sedimentation

High-level waste

Nuclear reprocessing

10.2139/ssrn.4034693

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Investigating sedimentation process in the plutonium reconversion using Eulerian Two-Fluid simulations and experimental verification

Nuclear Engineering and Design (2022)

Saroj K. Panda Vivek Mishra P. Vishnu Anand R. Rajeev K. A. Venkatesan

Settling

Sedimentation

Volume fraction

10.1016/j.nucengdes.2022.111955

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Citations (2)

Comparison of the performance of solvent wash reagents used for the primary cleanup of degraded PUREX solvent

Radiochimica Acta (2022)

Satyabrata Mishra Chandan Mukhopadhyaya Chayan Patra Vishnu Anand Panantharayil Puspalata Rajesh

Abstract The effectiveness of the solvent wash reagents such as sodium carbonate and hydrazine carbonate were compared using the lean solvent obtained during reprocessing of high plutonium content fast reactor spent nuclear fuel. The concentrations of the reagents were optimized based on the removal of retained metal ions from the lean solvent and 1.5 M hydrazine carbonate was found to be optimal and superior to sodium carbonate to be adopted as the reagent for primary cleanup of the spent solvent. Both the reagents were found to possess excellent room temperature stability and their performance was not affected upon gamma irradiation which was assessed in terms of capacity to remove di-butyl phosphate from degraded TBP/n-DD system.

PUREX

Sodium carbonate

Hydrazine (antidepressant)

Carbonate Ion

10.1515/ract-2022-0079

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Citations (7)

Alkaline Hydrolysis of Tri-iso-amyl Phosphate in n-dodecane Using Sodium Hydroxide: Part 1—Factors Affecting the Hydrolysis Process

Nuclear Science and Engineering (2024)

Satyabrata Mishra Vishnu Anand P J. Gnanasoundari R. Rajeev N. Desigan

Sodium hydroxide

Dodecane

Alkaline hydrolysis

10.1080/00295639.2024.2398358

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Two-Fluid and Discrete Population Balance Model for Simulation of Batch Sedimentation Relevant to Plutonium Reconversion

Nuclear Technology (2024)

Saroj K. Panda P. Vishnu Anand Vivek Mishra R. Rajeev K. A. Venkatesan

There are widespread occurrence and application of solid-liquid sedimentation processes among different industries. Therefore, it becomes important to understand the hydrodynamic inside the process equipment and particle agglomeration characteristics. In the present work, solid-liquid sedimentation is analyzed, which will be helpful for the design of continuous process equipment in plutonium (Pu) reconversion. Experiments were carried out in a batch settler to understand solid sedimentation in suspension in terms of varying the overall solid fractions. Euler-Euler two-fluid simulations were performed to investigate the local and overall solid phase volume fraction distributions, position of the active interface (AI) (settling curve), axial solid phase velocity, and pressure distributions during settling, and selected data were compared with the measured data. Further, the discrete population balance model (PBM) with different agglomeration kernels was used with the two-fluid computational fluid dynamics (CFD) model to understand and further improve predictions in terms of the AI position. The variation in number density of the different particles in the settler with time was investigated. The predicted results show that agglomeration is dominant during the sedimentation process and application of the discrete PBM with the CFD model enhances the predictive capability in comparison with the predictions obtained from only the two-fluid model. The results reported using CFD+PBM will aid in the design of continuous process equipment (thickener/precipitator) for Pu reconversion.

Settling

Sedimentation

CFD-DEM

10.1080/00295450.2024.2326714

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Regeneration of purex solvent by thin film evaporation

R. Rajeev P. Vishnu Anand C.V. Joyakin P. Velavendan N. K. Pandey

Tri Butyl Phosphate diluted with a suitable hydrocarbon is used as a solvent in the extraction step of PUREX process for spent fuel reprocessing. The useful life of the solvent is limited by the extent of formation of heavy molecular weight secondary degradation products. These degradation products are formed by the interaction of nitric and nitrous acids with various hydrocarbon compounds under the conditions of radiation and nitric acid. One of the easily deployable methods for the removal of these degradation products (secondary degradation products) is thin film evaporation. The instability of tri-n-butyl phosphate at elevated temperatures and the requirement that very low concentrations of variety of impurities that have to be removed, call for careful design of process and equipment. A pilot plant scale solvent purification system based on thin film evaporation under reduced pressure has been designed, developed and commissioned at the Reprocessing Development Laboratory, IGCAR. The solvent recovery system is an integration of different vapor-liquid separation units such as dehydration column, degasser and agitated thin film evaporator. The performances of the auxiliary equipment were monitored by conducting trial runs with simulated degraded solvent. The results obtained from the trial runs were analysed by measuring the physical and extraction properties. (author)

PUREX

Nitric acid

Degradation

Source

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