Concern and uncertainty exists over nuclear waste at Dungeness, Bradwell and Hinkley Point

In a report by marine pollution consultant, Tim Deere-Jones, it is evident that considerable uncertainty exists over the exact nature of proposals to package “fuel element debris” (FED) arising from the storage of spent nuclear fuel at the Magnox nuclear power stations at Dungeness (Kent), Bradwell (Essex) and Hinkley Point (Somerset); and, that concern exists over the exact nature, quantity and marine environmental impact of the radioactive materials involved.

Whilst the spent nuclear fuel (uranium) from these power stations has been shipped to Sellafield in Cumbria for reprocessing, the casing and magnesium cladding components from the fuel rods have been retained on site. The Nuclear Decommissioning Authority (NDA) has now decided that these materials (classed as Intermediate Level Radioactive Wastes) should be retrieved, processed and packaged for interim storage and eventual disposal.

This process involves the dissolving of these metal components and debris into an acid solution. The process involving a mild acid, carbonic acid, has been pioneered at Dungeness since 1988, but due to carbonic acid’s mildness the process is very slow. The desire of the NDA is now to accelerate the process and to employ nitric acid. Thus whereas hitherto the dissolution of “fuel element debris” has taken many years, the process is now expected to take 18 months. The nitric acid process is similar to the one used at Sellafield in order to reprocess the spent uranium.

Dissolution of the debris (FED) in nitric acid will generate highly radioactive wet solids. It is stated that “the bulk of the radioactivity will be retained within the residue and secondary wastes” and these will be packaged in containers suitable for interim storage and eventual disposal. However the process will also generate a less radioactive liquid which will be discharged to sea. These liquid effluents will be sand-filtered prior to discharge, and it is believed that this will be sufficient to remove any higher-level particles and radioactivity.

The first new FED dissolution plant is due to open very shortly at the Bradwell nuclear station on the sediment rich Blackwater estuary in Essex. It is proposed that FED will be retrieved from the power plant’s storage vaults and dissolved in nitric acid.

Concern exists as to the nature of the radionuclides which will be discharged to sea as a result of the new FED process. The Nuclear Free Local Authorities (NFLA) have a made a Freedom of Information (FoI) request to the company that owns the waste, Magnox Ltd, and the FoI reply lists 20 named radionuclides, including the nuclides Tritium (an isotope of Hydrogen), Cobalt 60, Strontium 90 and also alpha radioactivity emitting transuranics — such as 2 nuclides of Plutonium (Pu 240 and Pu 241) and one of Americium (Am 241).

The FoI request also sought to establish the quantity of these various nuclides in the discharges, but information on the expected quantity was only supplied in respect of 2 of these nuclides (Tritium and Caesium 137).

As a result, uncertainty exists as to the marine environmental impact of this new FED process due to the discharges to sea. In the case of a number of the nuclides, they can be re-concentrated in fine and muddy marine sediments in adjacent areas (estuaries, salt marshes) at levels considerably greater than those experienced in sea water itself. Hence uncertainty about discharge levels leads to uncertainty about whether local coastal areas will experience elevated levels of radioactive contamination, particularly by the long-lived highly radioactive nuclides of Plutonium, Curium and Americium.

As a result marine pollution consultant, Tim Deere-Jones, is strongly recommending that all new FED dissolution proposals should be subject to full and detailed Environmental Impact Assessments (EIAs) and Public Inquiries into the public health and environmental implications.

Source: Paper prepared by Tim Deere-Jones, June 2014, a copy of which may be viewed here.

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