Ruthenium: Nuclear’s Volatile Problem

Supervisors:

1) Professor Colin Boxall, Lancaster University

2) Dr Mick Bromley, Lancaster University

3) Dr Josh Turner, UKNNL Ltd

4) Jo Pugh, Sellafield Ltd

Ruthenium is a fission product possessed of two relatively long lived stable isotopes: Ru-103 (half life = 39.8 days) and Ru-106 (half life = 1 year). Both isotopes are present in UK spent fuel and so have had to be accounted for during the reprocessing or disposal of that fuel. At a number of stages during the processing of spent fuel, ruthenium can be exposed to high nitric acid, high temperature conditions that may lead to its transfer into the gas phase as ruthenium tetroxide. Two such stages are the dissolution of spent fuel into concentrated nitric acid at the start of reprocessing, and the vitrification of ruthenium into a glass waste form after reprocessing has occurred.

Volatilisation is to be avoided as the resultant gas phase ruthenium may then redeposit within metal pipework elsewhere in the plant which will then have to be decontaminated. However, ruthenium volatilisation occurs at unexpectedly low temperatures. Whilst RuO2 is not seen to volatilise below 900oC, gaseous ruthenium oxides have been seen to evolve from solutions of Ru in nitric acid at temperatures as low as 150oC – making the management of ruthenium difficult during reprocessing and vitrification.

Thus, given its volatile nature and high specific radioactivity ruthenium presents a strong challenge to the nuclear industry in effectively managing its abatement. Key challenges are to fully understand the highly complex solution/solid state chemistries that obtain not only under conditions relevant to dissolvers, evaporators and vitrification plants, but also in the decontamination methods used in its clean up. Using a combination of chemical, analytical and engineering approaches, we shall seek to address these challenges in this PhD.

This project is a collaboration between Lancaster University, The UK National Nuclear Laboratory (UKNNL) and Sellafield Ltd. Experimental work will be conducted primarily in

Lancaster’s UTGARD (Uranium-Thorium beta-Gamma Active R&D) Lab (https://www.lancaster.ac.uk/engineering/research/facilities/utgard-laboratory/)

This project is offered through the SATURN CDT (Skills And Training Underpinning a Renaissance in Nuclear Centre for Doctoral Training):

https://www.saturn-nuclear-cdt.manchester.ac.uk/

For further information: https://www.saturn-nuclear-cdt.manchester.ac.uk/

For further information: http://www.lancaster.ac.uk/engineering/

To apply for this PhD, please first send an email expressing interest to saturn@manchester.ac.uk. And c.boxall@lancaster.ac.uk. You should then apply using the on-line application form available at:

https://www.lancaster.ac.uk/study/postgraduate/applying-for-postgraduate-study/

You should address your background and suitability for this project in your personal statement.

SATURN_Nuclear_CDT