Marine Licence 12/45/ML, granted by the Welsh Government, permits the disposal of up to 300,000 tonnes of radioactively contaminated marine sediment, dredged from the seabed at the Hinkley Point nuclear site, into the Cardiff Grounds marine dump site close to the South Wales coast. This will allow work to begin on the 2 new Hinkley C nuclear reactor pipelines.

The sediments to be dredged are adjacent to the waste pipes used for the discharges from Hinkley’s 4 existing reactors. Analysis, commissioned by UK Government agencies, shows that the sediment is contaminated by radioactive waste discharged to sea over 50+ years of operations at the Hinkley site. Calculations derived from the official data indicate that the proposed dredge sediments may hold at least 7 billion Bqs of aggregated radioactivity, yet reports state that doses to humans would be very low.

Hinkley’s radioactive discharges to sea contain over 50 radio-nuclides, but the analysis has only investigated 3 of them. Thus, the actual aggregated radioactivity content of the sediments will be much higher than indicated by the available analysis. The available evidence also implies that only surface samples (0 to 5cms deep) of the sediment have been analysed, despite the fact that core sample research from elsewhere in the Irish Sea demonstrates that, at depths below 5cms, radioactivity concentrations may be up to 5 times higher.

While sedimentary radioactive material is initially likely to disperse, studies prove that it later re-concentrates in coastal and estuarine mudflats and saltmarshes, and is also available for sea-to-land transfer during onshore winds and coastal flooding. We note the absence of research on the fate of such radioactivity in South Wales inshore waters. In this context we are concerned that the environmental and human health (dose) risks from the proposed disposal have not been adequately researched and that any conclusions based on the current incomplete data, are unreliable.