A planning application for the Sizewell C nuclear power station has been formally accepted, marking the beginning of a process that could result in a green light within the next year.

If approved, construction of the plant on the Suffolk coast is expected to take around 10 years, ultimately generating enough power to support six million homes throughout its 60-year lifespan.

Development is expected to be simplified by the fact the station will be a near replica of the Hinkley Point C plant already under construction in Somerset. However, differences between the ecosystems and weather conditions at the two sites will need to be factored into the protection of marine wildlife.

The best available technology

The installation of an acoustic fish deterrent (AFD) was a key element of the Development Consent Order originally awarded to Hinkley Point C, as it can provide a warning signal to prevent fish from entering the station’s cooling water intakes.

All of the UK’s nuclear power stations have vast cooling requirements, which are met by drawing water from the sea or estuaries. This approach has been acknowledged as the most effective way to cool coastally-sited power stations by the Environment Agency and it is specified as Best Available Technology (BAT) across Europe.

However, since it puts fish in the surrounding waters at risk of being sucked into intakes, different mitigation measures combine to provide protection wherever it is used. These include a low velocity side entry (LVSE) intake, which helps fish swim away before they reach an intake, and the AFD which ensures they can detect their approach and guides them away.

An AFD is therefore also likely to be required at Sizewell C.

And while Hinkley Point C posed unique challenges thanks to one of the highest tidal ranges in the world, design of the Sizewell C solution is expected to be much more straightforward.

The ideal location

Dr Andy Turnpenny, a Fisheries Scientist and internationally recognised specialist in the field, believes that although the technical challenges will be reduced, the importance of an AFD may be even greater at the Suffolk site.

“There is a much larger proportion of fragile pelagic fish like sprat and herring, which are particularly well deterred by an AFD,” he says. “It’s even more important as part of a comprehensive fish protection system at Sizewell. The fish mix will benefit even more.”

That fish mix has changed dramatically over the last 30 years, thanks in part to measures designed to protect herring and allow them to re-establish a significant population.

Also present in the area are eels, which are not sensitive to sound. However, calmer waters make Sizewell C an ideal location for FGS’s patented Synchronised Intense Light and Sound (SILAS) system.

This solution combines high-intensity light bars and Sound Projectors, with the visual stimulus deterring less hearing-sensitive species and the synchronisation improving deflection rates for others. The need for offshore maintenance is reduced by the self-cleaning characteristics of the light bars, as ultraviolet LEDs kill algal cells before they can settle.

Such a system would provide assurance that Sizewell C is future-proofed against changes in the ecosystem, which become increasingly likely as climate change contributes to warmer waters.

Fish that some see as ‘acceptable losses’ now could well become protected species over the 60-year operation of the station, but installing an AFD from the outset will ensure losses are minimised throughout its lifespan.