Monitoring radionuclides in beach discharges: a new perspective on coastal groundwater risk near a UK nuclear site

Mawby, Naomi Leigh (2020). Monitoring radionuclides in beach discharges: a new perspective on coastal groundwater risk near a UK nuclear site. University of Birmingham. Ph.D.

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Observations of radioactivity from beach springs over a period of four decades provides insights into field scale characteristics of a migrating tritium groundwater plume from the oldest UK nuclear site at Sellafield, in Cumbria. The utility of high resolution spatial and decades long temporal tritium coastal discharge data is demonstrated as an indicator tracer of groundwater flows and radionuclide fate to coastal environmental receptors. Data mined from as far back as 1975 is presented to be of historical significance as one of the earliest unpublished radionuclide contaminant plume investigations in the coastal environment. New field data is presented for tritium activity in beach springs and delineates a distinct asymmetric groundwater plume discharge footprint stretching 2600 metres northwards of the site along the foreshore. The spatial distribution of the tritium is further to the north-west than predicted by the Sellafield Ltd conceptual model and extends beyond the perimeter of the current site groundwater monitoring well network. The spatial footprint was further confirmed by additional sample analysis for technetium-99 with similar contributing source areas. The results of the project suggest that the groundwater flow regime to the north-west of the nuclear site is highly complex and narrow plume contaminant contributions are from more than one source, merging and surfacing in low flow beach springs in the intertidal zone. It is recommended that nuclear sites located near the coast should adopt this simple and inexpensive beach spring monitoring practice as a useful spatial and temporal diagnostic tool at the field scale. This method is complimentary to traditional groundwater monitoring wells and has improved far-field conceptualisation of contaminant sources and resultant pathways to the beach springs and concluded low risk levels to the coastal region (as of 2018).

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Colleges (2008 onwards) > College of Life & Environmental Sciences
School or Department: School of Geography, Earth and Environmental Sciences
Funders: Other
Other Funders: Sellafield Ltd
Subjects: Q Science > QE Geology


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