Characteristics and occurrence of radioactive beach finds near the Sellafield site

Radioactive objects have been found on beaches near the Sellafield Ltd. nuclear site (UK). Between 2006 and 2024, routine beach monitoring recovered 3621 radioactive objects which have been analysed by gamma spectrometry. A subset of finds was subjected to detailed characterisation to identify their composition, age and source, and trends in find rates were analysed. Alpha-rich radioactive particles comprise iron oxides from nuclear fuel reprocessing waste, somebeta-rich radioactive particles comprise metal, graphite or iron oxides. Both were likely discharged before the requirement to exclude solids from effluent was introduced and abatement plants were commissioned in the 1980s. They may have entered the environment shortly after production, or when the former sea pipeline was decommissioned by the mid-2000s. Some beta-rich particles and larger objects (> 2 mm) formed from the sorption of ¹³⁷Cs from aqueous effluent onto natural rocks and minerals. No evidence for nuclear fuel fragments was found in this study. Radioactive objects are likely to be distributed through the offshore environment, mostly localised to Sellafield, and are washed onshore in conjunction with bulk sand transport processes, although a small proportion of alpha-rich particles are transported northwards. The risks to beach users from radioactive objects are very low.