236U is produced only by neutron irradiation of uranium and therefore is potentially useful as a marker for anthropogenic uranium in the environment. Accelerator mass spectrometry (AMS) provides a technique for the determination of very low concentrations of actinide nuclides, and has now been applied to the determination of 236U:235U ratios in an intertidal sediment core collected from the North Irish Sea. Combining measurements of the 238U mass concentrations calculated from alpha spectrometry with 238U:235U ratios from ICP-MS and 236U:235U ratios from AMS has allowed the estimation of the mass concentrations of 236U in the sediments. 236U mass concentrations are in the range 10(-8) to 10(-9) g kg-1, and 236U:238U atom ratios in the range from 10(-5) to 10(-6), well above natural baseline levels. Uncertainties based on propagation of measurement errors were less than +/- 10% although +/- 15% is perhaps a more realistic estimate of overall uncertainty.

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Separation of the minor actinides (Am/Cm) from spent nuclear fuel post-PUREX process is expected to play a key part in new reprocessing methodologies. To date, a number of selective americium extractants from the BTPhen ligand family have been identified. In this investigation, we synthesise 24 novel BTPhens with additional functionality to determine the effects on solubilities and americium extraction capabilities. The data obtained will allow for tuning of steric/electronic properties of BTPhens in order to assist future extractant design.

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