Plans to pour nuclear effluent into an Essex estuary could pollute the region’s famous oysters, a fisherman and wildlife expert have warned.

As part of the decommissioning procedure for the nuclear power station at Bradwell-on-Sea, near Maldon, a process known as fuel element dissolution (FED) is set to take place. It involves dissolving metal that was used to hold fuel rods in acid to reduce and capture radioactive material before discharging the liquid by-product into the sea at the Blackwater Estuary.

The process is due to start next month but West Mersea oyster fisherman, Richard Haward, who fishes the estuary and owns the well-known fishmongers The Company Shed, fears too little is known about the potential impact the effluent could have on the fragile population of native oysters that inhabit the area. In December, the estuary was designated a Marine Conservation Zone (MCZ) by the Department for Environment, Food and Rural Affairs (Defra) to protect the oysters, which have been farmed there since Roman times.

However, both Magnox, which operates the plant at Bradwell, and the Environment Agency say the liquid discharges will be within safe limits.

Mr Haward said: “The population of native oysters is much lower than it has been traditionally and the MCZ was set up to help the population grow. If nothing is done now the population could fall beyond a level where they could recover,”

“We are against the process. There’s just not enough information about the impact the process might have and we need to give the oysters every chance we can.”

He has been backed by Sarah Allison, a marine officer at Essex Wildlife Trust, who said she was “seriously concerned” about the discharge plans.

“The environmental impacts of such a process are unknown. It is imperative that we fully understand the potential environmental damage before the process can go ahead , and until this point it should be treated with extreme caution,” she added.

In response, a Magnox spokesman said; “Discharges to the estuary within agreed safe limits have been taking place regularly for more than 50 years and are continuing as the site is decommissioned.

“Magnox is sensitive to the local environments in which it operates and is committed to decommissioning Bradwell with the highest regard to safety and the environment. Our work programme is fully compliant with regulatory requirements and we will ensure that it remains so as clean-up of the site continues.”

In a statement, the Environment Agency added; “A similar process for treatments of FED has been carried out at Dungeness A power station in Kent for well over 10 years.”

In addition to the operators’ environmental monitoring programme, the Environment Agency carries out its own environmental monitoring in the local area to determine levels of radioactivity in the estuary. These continue to demonstrate that levels in the environment around Bradwell are low and health impacts would be negligible.”