For Nugen – the Toshiba/GDF Suez consortium behind plans for three AP1000 reactors on a green-field site adjacent to Sellafield – the imminent decision by the EU’s competition commissioners on the legality of the range of subsidies and guarantees being offered to developers by the UK Government, represents just one of many major hurdles along the Sellafield new-build route.
NuGen’s announcement earlier this year of a 3-year delay in coming to a decision on whether or not to invest in the project (from 2015 to 2018) is reflected firstly by the visible and documented absence of any tangible progress by NuGen’s investigations on the site for which it secured an option five years ago. Secondly it will reflect unease, irrespective of the EU decision, about the hurdles that lie ahead in fully developing the site. These hurdles include not only the costly and highly contentious National Grid transmission connections with their threat of giant pylons and sub-sea tunnelling under Morecambe Bay but also the site specific problems of geology and the cooling system for the reactors.
Described in 2011 by NuGen as consisting predominantly of improved pasture fields and a small number of arable fields , the site for investigation has a land area of 199 hectares – or 2 square kilometres. By comparison, the Sellafield site is three times larger at some 600 hectares or 6 square kilometres In the early 1990’s BNFL had assessed a tract of land almost identical to that now being considered by NuGen and provisionally selected a 15 hectare plot for new PWR build (with an additional 30 hectares for temporary works) adjacent to the River Ehen and just above the coastal flood plain – a location and elevation that would allow ‘direct seawater cooling’ to be employed .
The geological constraints of the NuGen site include the depth of the bedrock which ‘in some areas is so great that construction is unreasonable’ – as revealed in documents published by Greenpeace UK in 2011 from responses to FoI requests. Similarly described in an earlier report to Cumbrian local authorities as being ‘less than optimal’, NuGen is likely to be hard pressed to safely site one new AP1000 reactor without incurring significant additional costs, let alone three new reactors as proposed.
Whilst in geological terms NuGen face an uphill struggle in constructing its proposed AP1000s, it will be equally challenged by the obstacles presented by cooling the reactors – either through direct (seawater) or indirect (cooling towers) cooling systems. A 2011 Generic Design Assessment published by the Environment Agency (EA) describes direct cooling via seawater extraction/ discharge as being proposed by Westinghouse for its AP1000 reactors on coastal sites , and that ‘direct cooling can be the most appropriate environmental option for large power stations sited on the coast …’. An earlier report by the EA shows the benefits of direct seawater cooling over the use of cooling towers (which it describes as the most offensive) as including higher efficiency, low complexity and the absence of on-site water consumption.
The choice of cooling is a site specific consideration for NuGen and is unlikely to be revealed until it presents its proposals for public consultation. However, the use of indirect cooling (via cooling towers) is already effectively ruled out on the basis of Westinghouse’s preference, supported by the EA, for direct cooling with seawater.
In addition, the case against cooling towers is bolstered by the increasing reluctance of planning authorities to accept cooling towers and their plumes in terms of visual impact. The EA concludes that ‘it is unlikely that nuclear station developers would opt for indirect cooling by choice owing to the various penalties: planning issues, land-take, capital and running costs, lower efficiencies, waste disposal etc’.
With cooling towers seemingly ruled out – the use of direct cooling via seawater extraction brings its own special spectrum of difficulties for NuGen both in terms of cost and physical construction. The foremost difficulty is the construction of the necessary offshore submerged intake/discharge system which, in Cumbrian waters, will involve tunnelling through the seabed and banks of radioactive sediment (including plutonium) that have accumulated over decades from Sellafield’s reprocessing operations. This has long been recognised as being a major difficulty for new-build on the West Cumbria in terms of health & safety issues and the wider dispersion of radioactive contamination during construction.
Despite the lack of documentation in the public domain on the construction of seawater extraction systems specific to West Cumbrian waters, a 2006 report on BNFL’s plans to build a new PWR on the same coastal plot as now being investigated by NuGen concluded that ‘extensive studies indicated that a single station outfall would need to extend 2.5km offshore to achieve the required thermal and chemical dispersion. If a second station was contemplated, a 4km separation would be required between the two outfalls with the intakes being 1.8km offshore in both cases’ .
Whilst the imminent EU ruling on the legality of the UK Government subsidies being offered to new-build developers clearly represents a critical milestone for NuGen, the configuration of a seawater cooling system for three new reactors will be equally critical and contentious for the consortium – as will siting three reactors in a geologically constrained greenfield site that is ‘less than optimal’. Taken as a whole, NuGen’s overly optimistic forecast that all three AP1000 reactors will be up and running by 2026 looks more remote by the day.