Assessing the properties and release behaviour of products arising from metallic and exotic fuel corrosion

Aim: To develop a better understanding of the properties and reactivity of bulk corrosion products arising from the degradation of legacy metallic and exotic SNF.

Research will develop understanding of the fundamental properties and reactivity of bulk corrosion products arising from the degradation of legacy metallic and exotic nuclear fuel materials. Such research will allow better prediction of the pyrohporicity, and therefore risk posed by such actinide corrosion products present in nuclear storage that might represent a hazard during repackaging or transport to a disposal facility. A recent (22^nd Jan 2018) meeting between RWM, Sellafield, NNL, Magnox and Bristol permitted the following specific objectives to be defined:

A targeted study using advanced X-ray imaging, tomography and diffraction methods to understand the corrosion behaviour of spent metallic fuel sealed ‘partially wet’ inside metal storage cans. Small-scale simulants will be utilised to understand the relative mass, type and distribution of the arising corrosion products.
Corrosion study using isotopic labelling to establish the fundamental mechanisms and rates for oxidation/pyrophoricity of fuel corrosion products in water versus dry oxygen and air. The extent and rate of heat release during oxidation will be determined to aid prediction of possible future thermal excursions during legacy waste repackaging.

The PDRA will use cutting edge materials analysis techniques to provide a nano to micro to millimetre scale observation of carbide corrosion behaviour. Techniques will include X-ray tomography (XRT), high-speed atomic force microscopy, secondary ion mass spectrometry, high-resolution electron microscopy and X-ray diffraction. The techniques are all routinely used and available at the IAC in Bristol. To compliment the materials analysis, residual gas analysis mass spectrometry will be used to examine the gases produced by corrosion and their rate of production; thereby indirectly yielding a corrosion/oxidation rate.

Academic Lead: Tom Scott
Researcher: Haris Parasevoulakos
Location: University of Bristol