Jess Shiels

Profile

2010 - 2014 Loughborough Univeristy MChem - First-class honours

Research interests

The fundamental project aim is to further behavioural understanding of caesium phosphomolybdate and zirconium molybdate as dispersions. These are precipitating solids of nuclear waste causing issues whilst being stored in the temporary Highly Active Storage Tanks (HASTs) at Sellafield site. Understanding their behaviour will enable more accurate predictions of their re-suspension from the ‘hot-spot’ beds they form via the jet ballasts incorporated into the newer deigned tanks and  help to provide detailed planning of the draining and Post Operational Clean Out (POCO) of the older designed tanks.

 

Part of the project will look at manipulating the morphology of the simulants which may provide them with advantageous properties that could assist their re-suspension in the HASTs. In addition, a better understanding of their synthesis mechanisms could provide more extensive information on their formation within the HASTs and potential routes for modifying their synthesis, especially in regards to increasing the conversion of caesium phosphomolybdate to zirconium molybdate.

 

Atomic force microscopy (AFM) is a technique to be utilised once crystals of the nuclear waste simulants are grown to a suitable size, in order for the Hanmaker constant to be determined. This can then be used to understand the Van der Waals interactions of the particles and potentially model their aggregation tendency at low pH’s, conditions which they experience in the HASTs.

 

Studies into both solubility and zeta potential will also be conducted to further recognise the surface chemistry of the particles, especially in understanding the role of the nitric acid reaction medium for the synthesis of caesium phosphomolybdate. Compressive yield stress measurements are to be a key focus early on in the research, in order to appreciate the jet ballast behaviour on the sedimentation bed and the re-suspension of the solids. In addition to investigating the properties mentioned for the individual simulants mixed dispersions of both simulants will also be studied.

Research groups and institutes

  • Nuclear Leeds