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Testing of a £50m ultrasound system designed to stop fish being sucked into the cooling pipes of Hinkley Point C nuclear power station has gone “really well”, according to engineers working on the Somerset project. The trial by Swansea University found the system “highly effective,” and project leaders are now considering scrapping plans to flood 900 acres of farmland in Gloucestershire which had been proposed to provide compensating habitat for fish.
Two tunnels bored 1.8 miles under the Severn Estuary will deliver 120,000 litres of water per second into the plant’s cooling system. The estuary is home to large numbers of sprats and salmon, and the twaite shad, a protected migrating species which spawns in the tributaries of the River Severn. Older power stations have simply placed grills across inlet pipes, filtering out fish in the process. At Hinkley Point C, officials are planning what one government reviewer described as “more fish protection measures than any other power station in the world.”
How the system works
Dubbed the underwater fish disco, a network of ultrasonic speakers has played sounds deterring fish from swimming close to the plant’s pipes for six months. The system was designed in Devon by Fishtek Marine and tested by Swansea University in the Severn Estuary. Trials found only one tagged twaite shad came within 30 metres of the intake heads, compared to 14 before the system was switched on.
Chris Fayers, head of environment at Hinkley Point C, said the ultrasonic speakers are lowered into the seabed “a bit like a lobster pot. We can raise it up again after a year to change the batteries. That means we can avoid using divers, which is a really risky operation that we wanted to avoid.”
Pete Kibel, managing director at Fishtek Marine, said “We have now developed a highly effective system that will protect fish in the Severn Estuary and potentially be an option for many more power stations throughout the world.”
Farmland flooding plans may be scrapped
Project leaders had originally drawn up plans to flood 900 acres of farmland on the banks of the Severn in Gloucestershire to create saltmarsh habitats as compensation for fish mortality. The proposal met fierce local opposition. Councillor David Merrett, chair of Arlingham Parish Council and a dairy farmer, said “The area they were targeting was 500 acres of prime farmland, meadows, and orchards. So to flood that seemed like a completely daft idea.” Merrett said parishioners will be “thrilled” if the flooding scheme is scrapped.
If the fish disco is approved, project leaders say they “should not need to create 900 acres of salt marsh as environmental compensation.” However, the final decision is yet to be taken. The system will be tested for another six months in 2026 to establish more evidence before Fayers’ team seek final approval from environmental regulators.
Questions over cost
Some experts have questioned whether the technology is worth its price. While the acoustic deterrent itself costs £50m, the wider fish protection system — including larger inlet heads and a return pipe — will cost £700m in total. Some experts note the number of fish actually at risk is small, roughly equivalent to the daily catch of one Cornish fishing boat, given that fish must swim within two metres of the pipe inlet heads in an estuary 22km wide at that point.
John Fingleton, who recently reviewed nuclear regulation for the UK government, singled out Hinkley Point’s fish protection measures as a case study of “overly cautious regulation,” noting “Motorways wouldn’t be very useful if we all drove at five miles an hour, but that’s sort of what we’re doing in nuclear safety.” The estimated cost of Hinkley Point C has risen to £46bn from the £18bn predicted in 2017, with the plant expected to open in 2031.