Samad Rana

Profile

Project Background:

Research project focused on modelling a key unit operation in the plutonium finishing lines of the PUREX process known in industry as a “vortex reactor” or “vortex precipitator”. This reactor was developed by the UKAEA in the early 1950’s and does not conform to conventional stirred tank reactor designs. Precipitation reactions are performed in this unit to form plutonium(IV) oxalate crystals, which are further processed downstream into plutonium(IV) oxide fuel.

Due to the poor mixing characteristics of vortex reactors, a detailed understanding of the flow behaviour is needed to understand how precipitation processes such as supersaturation, nucleation & growth are influenced by the hydrodynamics/mixing, which will affect the product quality, such as crystal shape, crystal size, & crystal size distributions. Controlling product quality will be important for downstream unit operations, in addition to final fuel qualty.

Additionally this project will investigate advanced fuel cycles currently under research such as the COEX^TM process, where uranium(IV)/plutonium(III) oxide is co-extracted to form MOX fuel via co-precipitation of uranium(IV)/plutonium(III) oxalate. Co-extraction helps minimise the proliferation risks associated with extracting pure plutonium(IV) oxide (a criticism of PUREX) as plutonium is not separated at any point in the process, whilst ensuring control of fuel quality on a molecular scale as compared to current methods to form MOX fuel via solid processing routes.

Project Aims & Objectives:

This project will seek to develop a modelling methodology, using a CFD-PBM approach, to couple hydrodynamics/mixing, using CFD, with precipitation processes, using PBM, where a surrogate material, i.e., calcium(II) oxalate, will be modelled in place of plutonium(IV) oxalate, to understand how operating conditions influences product quality in such vessels. The accuracy of the model will be assessed by validating the predicted data collected against experimental data from previous studies.

A co-precipitation model will also be developed & integrated where for similar reasons surrogate materials will be studied of the form B_xC_1-x(C₂O₄)_y.nH₂O. Experimental data will need to be collected to develop the model and assess quality of predictions from model.

The development of such a model will help improve process understanding allowing process operators to optimise reactor operation to ensure smooth plant operation, minimising the need to perform manual procedures or a series of rigorous experiments (which can be costly & time consuming). Also through gaining an improved understanding of co-precipitation processes, the feasibilty of adopting advanced fuel cycles such as COEX^TM will be assessed helping drive the nuclear industry towards a sustainable closed fuel cycle.

Project Funding:

Funding for project is provided by EPRSC CDT in Nuclear Energy - GREEN.

Research interests

• Spent Nuclear Fuel Reprocessing
• Computational Fluid Dynamics (CFD)
• Population Balance Modelling (PBM)
• Compartment/Zonal Modelling
• Hydrodynamics/Mixing in Vortex Reactors
• Precipitation/Co-Precipitation Processes

Qualifications

• PGDip, Nuclear Science & Engineering (2022-2023) - Distinction
• MEng, BEng, Chemical Engineering (2018-2022) - First Class Honours