Radioactive particles have been released into the environment from different sources (e.g. nuclear weapon tests, nuclear accidents, nuclear reprocessing plants, and use of depleted uranium (DU) munitions). Nuclear fuel particles have been released from authorised discharges of low-level radioactive effluent into the Irish Sea sediments from the nuclear fuel reprocessing plant at Sellafield, UK. Following the use of depleted uranium munitions in the Gulf wars and the Balkan conflicts, the environmental impact of depleted uranium and its behaviour in the environment have been of great concern. In this thesis, nuclear fuel particles released from Sellafield and retained in the intertidal Irish Sea salt marsh sediments, and DU particles arising from testing of DU munitions against hard targets and corrosion of DU metal buried in soil at Eskmeals firing range, UK, were investigated using a range of microanalytical, analytical and radiometric techniques. The particles were characterised in terms of size and morphology, elemental and radionuclide compositions, isotopic composition of associated radionuclides and, crystalline structure of uranium forms. The results demonstrate the usefulness of the applied techniques in characterising environmental radioactive particles, and lead to better understanding of the origin, behaviour and fate of these particles in the environment. The nuclear fuel particles were 1-20 µm in size, composed mainly of uranium and irradiated in the reactor as the transuranium elements (Np, Pu, Am and Cm) can be identified. The isotopic composition of uranium and plutonium suggest that these particles are derived from reprocessing of spent fuel. The results demonstrated the persistence for some decades of irradiated fuel particles in estuarine marine environment.DU particles from firing impacts were oxidized uranium forms (UO2 and U3O8) and composed mainly of uranium with few molten particles composed of a mixture of uranium and iron. DU particles from corrosion processes were mainly sand grains coated with metaschoepite corrosion product. The results showed the diversity of particles which can be produced through the use of DU munitions and the potential for these to persist in the environment for many years.
|Date of Award||31 Dec 2010|
- The University of Manchester
|Supervisor||Francis Livens (Supervisor)|