Analysis of sediment – Do samples from the deeper levels breach permitted “de minimis” limit? Samples analysed for 2013 and 2017 reports were from the top 2cm of the surface of the mud deposits. These will be recent and highly mobile sediments derived from the whole of Bridgewater Bay. They will not be representative of the older and deeper sediments accumulated in past decades from higher nuclear discharges. The previous deep core-samples of 2009 showed significantly higher radioactivity in 3 out of 5 samples, implying that the bulk of excavated material could be of higher levels of radioactivity, which would take the mud closer to the de minimis limit. Exceeding this level would make disposal at sea illegal. EdF have refused the Petitions Committee’s request for more sampling at metre-depths, stating that no artificial radioactivity was observed below 2m. NRW have failed to demand from CEFAS an appropriate test to detect alpha-emitters, such as Uranium and Plutonium and instead relied on gamma spectrometry to test the mud samples. CEFAS then omitted to report indirect evidence of these same alpha-emitters in their reporting to NRW.

Deep Sea or Severn Estuary? The disposal site is in the Severn Estuary and not in the open sea. NRW appears to be permitting the mud dumping because the expected yearly received dose of radiation will not exceed that allowed for sea disposal under the terms of the London Convention, the law regulating the disposal of radioactive material at sea. However, the Cardiff Grounds dispersal site is situated within the Severn Estuary, rather than in open sea.

New assessments by CEFAS of the expected dose of radioactivity are based on only three available samples, meaning their anticipated level of 5.8 µSv/yr could be unrepresentative. The actual dose could exceed the 10 µSv/yr “de minimis” level, making the dump illegal anywhere at sea and even more potentially damaging in an estuarine environment.

The London Convention permits the dumping of artificial radioactive material at sea “where proper account has been taken of the marine environmental and other conditions” and meets “de minimis” criteria. International Atomic Energy Authority guidelines stipulate that disposal can include well-mixed coastal waters but states that disposal should take place a few kilometres off the coast, so that the actual shape of the coastline does not influence dispersal significantly. There is no approved protocol for estuarine disposal.

IAEA guidelines, updated in 2015, require that an assessment on the affects of the disposal on wildlife must be carried out, prior to permissions being granted. Therefore NRW should have produced a Habitat Regulations assessment, prior to granting EdF permissions to dump. Cardiff Grounds is within a Ramsar site, a protected area of international importance to wetland birds, and is also situated within a Special Area of Conservation.

Toxic metal and organic contamination of sediments.

EdF have disclosed to CEFAS that there are excessive levels of metal and organic compounds in the Hinkley mud, which amount to “a quite small breach” of CEFAS’s “Action Level 1”. NRW should have assessed and reported on this anticipated impact to wildlife, but failed to do so before granting EdF permission to dump.

In conclusion, NRW’s expected commitment to sound science and rigorous regulatory standards does not seem to have held sway when granting permission to move mud from Hinkley Point to Cardiff Grounds. They acknowledge that they do not have expertise in nuclear matters, but they were appointed by WAG to approve the removal and re-location of this mud, a legacy of reactors A and B, at Hinkley.

The people of Wales and its environment will not benefit from this mud and we expect our Assembly to exercise due rigour when deciding on its suitability, or not, for dispersal in Welsh waters. We demand that the decision to grant to EdF permission to dump is suspended until proper rigorous testing of deep samples is carried out. This proper testing should be carried out in a manner that will re-assure the public, who do not wish to accept increased radio-active contamination of the Welsh coastline and its tidal waters.

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