The Environment Agency has agreed to allow Devonport Royal Dockyard Ltd (DRDL) permission to increase the quantity of radioactive carbon released into the atmosphere from submarine refit operations at the dockyard, following public consultation over the need to vary the company's Environmental Permit.
The Agency claims that it is satisfied that the application for the increase to the permitted annual limit and quarterly notification level for atmospheric carbon-14 emissions is justified. Although accepting that “there will be a small increase in public radiation dose” as a result, the Agency argued that this would be small in comparison with the average annual dose accrued by a person living in the South West of England.
DRDL say that the increase in discharge limits is needed to allow the refit of HMS Vanguard to proceed to schedule. HMS Vanguard, a nuclear-powered and nuclear-armed Trident submarine, is currently undergoing an unscheduled second refit at Devonport. The refit was ordered following the discovery of a radioactive leak in a test reactor at the Naval Reactor Test Establishment at Dounreay, and was deemed necessary as a precaution to ensure that the reactor in Vanguard – the oldest submarine in the Trident fleet – did not develop a similar defect.
However, the variation to the company's Environmental Permit which has been agreed by the Environment Agency appears to allow a permanent increase in carbon-14 discharges from the Dockyard, and not just a one-off temporary increase for the period of the Vanguard refit. This leaves open the possibility that increased quantities of carbon-14 may be discharged as a result of future submarine refits.
Although claiming that ‘Best Available Techniques’ were being applied to control carbon-14 emissions, the Environment Agency rejected options which might reduce the quantity of carbon-14 emitted, arguing that abatement technology, whilst available, “would be complex with high operating costs and energy consumption, and generate significant quantities of secondary waste”
Government policy on radioactive releases to the environment is to achieve “progressive and substantial reductions on radioactive discharges” and “progressive reductions in human exposures to ionising radiation ... as a result of planned reductions in discharges”. As a guiding principle policy emphasises “the preferred use of ‘concentrate and contain’ in the management of radioactive waste over ‘dilute and disperse’” However, the Environment Agency claims that “Of the reasonably practicable options considered by the applicant, the chosen discharge route was shown to result in the lowest dose to the representative person” and is therefore justified.
Much remains unknown about the low-level impacts of radiation doses on health, but there are concerns that, because of its relatively long half-life and disposition to organically bind to cell constituents, ionising radiation from carbon-14 can cause cell damage with corresponding impacts on human health.