WATER WORLD | SPECIAL REPORT
such as cadmium and mercury which is present as trace contaminants in bulk raw materials. The EA also requires a report on the operational
strategy for the control of biofouling of the cooling water system. That would include an appraisal of the operational conditions and chlorination strategy employed at Sizewell B, lessons from commissioning and operating any other EPR (eg Flamanville in France), details of how the operational strategy has been optimised to reduce the need for chemical dosing and validation of the impacts of the proposed dosing regime. NNB also has to report on its plans for the use and discharge of hydrazine (N2H4
), which is added to cooling
water prevent oxidation of metals (rusting) in the steam generator. NNB said that that although other ‘oxygen scavengers’ are available, these either reduce the efficiency of the power station, or are more harmful to the environment than hydrazine. Hydrazine will be present within waste streams from the nuclear island waste monitoring and discharge system and tanks and within a waste stream from the conventional island liquid waste discharge system network and tanks. NNB has agreed to monitor hydrazine within these systems and use an appropriate treatment method – still to be determined and qualified - to reduce levels before any discharges occur if they may breach limits. In addition before commissioning at Sizewell C NNB will study the feasibility of further minimising hydrazine. The need to protect fish in Greater Sizewell Bay has been highlighted by campaigners against the new plant at Sizewell C. As a result of the direct cooling of the Sizewell C power station with seawater, each unit will each incorporate a fish recovery and return (FRR) system to minimise the risk of injury to fish that are drawn into the cooling water system. The FRR systems will return the fish to the Greater Sizewell Bay. Each of the FRR systems is served by a dedicated discharge tunnel and outfall. These will discharge at locations where fish are not likely to be returned to the four cooling water intakes. At Hinkley Point C, measures to ensure fish are not
scooped up in the cooling water intakes include three so- called ‘acoustic fish barriers’ (AFBs). EDF has recently argued that the benefits of having three AFBs do not outweigh their
costs. But in March this year the environment secretary ruled against EDF when it argued that only two fish barriers were required. Quoted in local media, Chris Fayers, Head of Environment at Hinkley Point C, said: “We are considering the detail of the planning inspector’s decision and the options available to us. Hinkley Point C is the first power station in the Bristol Channel to include any fish protection measures at all. Studies from the government’s own marine science experts have shown that the power station will have a negligible impact on local fish stocks with our proposed fish protection measures in place. This includes a fish return system, and water intakes designed to significantly reduce the number of fish coming into the pipes.” At Sizewell C, it is not yet clear what measures will be
required. NNB has to present EA with an updated site plan and a commissioning plan for the two FRR systems, details of the monitoring proposed to facilitate optimisation minimise fish kills and proposals for demonstrating the effectiveness of the optimisation. That will incorporate the lessons learnt through design evolution and from other EPRs at Hinkley Point or worldwide.
Other water supplies Although cooling water is by far the largest water use for Sizewell C, general water requirements onsite are a complex challenge for NNB and the eventual operator of the reactors. In the decision letter granting development consent for Sizewell C the Secretary of State devoted 57 paragraphs to discussion of this issue. The supply will be provided by local water monopoly Essex and Suffolk Water (whose parent company is Northumbrian Water Ltd, NWL), and wastewater services will be provided by Anglian Water. But in its planning, NWL says the region is expected to be in deficit and “the water required deficit increases in 2032 due to a step increase in demand when we will start supplying Sizewell C with 2.2Ml/d as an annual average and 2.8Ml/d as a peak daily”.
When NNB applied for development consent it expected that it would be supplied with ‘mains water’ from the local Blyth Water Resource Zone, but the EA considers NWL abstractions in this zone to be ‘over licensed’, with NWL unable to meet additional water demand by abstracting more water.
Above: The Suffolk region in the eastern UK is an area defined by the Environment Agency as under ‘water stress’
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