Computational investigations of the interaction of brucite surfaces with uranium and its fission products

A key component of nuclear waste is spent uranium fuel rods and, in the case of waste from first generation British nuclear power reactors, a magnesium-aluminium alloy known as Magnox, used as fuel cladding. This waste is found as fuel element debris at Magnox reactor sites around the UK, and at Sellafield in water filled storage ponds which act as radioactivity shields to the environment and as aids to cooling. A storage period of several decades has resulted in an accumulation of a variety of radioactive elements; the primary species present are uranium and two of its nuclear decay products, strontium and caesium.

The Magnox fuel cladding corrodes to produce a sludge of the mineral brucite (Mg(OH)2), which readily adsorbs atoms of metals such as uranium and its decay products. The understanding of the interactions between these metal atoms and brucite is therefore important when forming strategies for the continued storage and immobilisation of radioactive species in the waste, particularly since some of the storage ponds are nearing the end of their operational lifetimes.

This computational project will focus on the application of the periodic electrostatic embedded cluster method, in which an explicitly treated cluster is embedded in an infinite array of point charges. This allows the study of the binding of small molecules with the cluster, whilst also incorporating long-range effects into the model. Short-range interactions are simulated using a quantum chemical method (typically density functional theory), whilst the long-range electrostatic interactions with the bulk are modelled via the embedding of charges. In the present project, the explicitly treated cluster will represent part of the brucite surface, and the interactions of this with small molecular hydrates of uranium, strontium and caesium will be investigated.

Please contact Nik Kaltsoyannis ([Email Address Removed]) for further details.