Remobilisation of actinides from intertidal sediments of the ravenglass estuary

Abstract

In the Radionuclide Analysis Section at Harwell, methods for the determination of plutonium and americium alpha-activities have been developed for a wide variety of environmental materials. Much of this work has been carried out in connection with programmes of monitoring and research into the fate of these actinides following their discharge from the British Nuclear Fuels plc reprocessing plant at Sellafield in Cumbria. Methods used to determine actinide activities present in the solution and suspended particulate phases of seawater are outlined. These have enabled distribution coefficients (K d's) for actinides between these phases to be calculated for samples collected as part of activity balance studies conducted over complete tidal cycles in the Ravenglass estuary. The results of one such study are presented, and ways in which K d values may be used to explain the observation that currently, the Ravenglass estuary acts as a net source of actinide activity to the Irish Sea, are discussed.