Comments from the DECC Site---Is Oldbury Suitable?

Deployabilty by the end of 2025: Generic issues with river based sites

The Alternative Sites Study has highlighted that the lack of preparatory work done to date means that Owston Ferry would take significantly longer to develop than most of the nominated sites. This and other complicating factors set out below suggests that development by the end of 2025 is not credible.

Owston Ferry is a river based site. The Alternative Sites Study has concluded that river based sites for nuclear power stations are technically feasible and noted that they do operate in other countries. However, they highlight that there are a number of significant drawbacks associated with them which may make them unattractive from the perspective of development.

There are no river-based nuclear power station sites currently operating in the UK, so the development of safety cases and other consents documentation could be more problematic and time-consuming than for coastal or estuarine sites, for which precedents already exist in the UK.

In addition, exacerbated by the potential effects of climate change, there is a risk over the lifetime of a station there would be periods when river flow rates decrease such that the station would need to shut down because of a lack of sufficient water to operate. This means that river based sites may prove less reliable in achieving security of energy supply which is a key aim of the Nuclear National Policy Statement, and it is more difficult for a developer to plan adaptability over their lifetime. The Appraisal of Sustainability for Owston Ferry finds that during the long operational life of the site climate change is likely to have an increasing influence. Impacts due to climate change are likely in this respect to be more pronounced at Owston Ferry than at sites located on the coast.

If any proposal for a UK river based site came forward the Nuclear Installations Inspectorate would need to consider whether the cooling provided either directly by the river, or indirectly via forced or natural draught cooling towers was adequately reliable to address the demands of safety under all operating and shutdown conditions. Looking at river based sites overseas, except for the very largest rivers, indirect cooling (i.e. cooling towers) is used worldwide, with natural and/or forced draught systems providing the necessary cooling⁴⁹.

Natural and forced draft cooling systems are likely to increase the cost of a station, and cooling towers can reduce the efficiency. Depending on the different types of cooling tower used, it is estimated that indirect cooling can be within 0.5 and 2% less efficient than direct cooling, which reduces the net output of a station.

The combination of reduced efficiency from cooling towers plus potential periodic closures due to river flow amounts to significant potential economic loss. These issues do not arise at coastal and estuarine sites such as those nominated (apart from Oldbury) predominantly because of the availability of very substantially greater volumes of water and the use of the sea as a much more effective heat sink.

Footnotes

49. It should be noted that for all but one of the sites that were nominated for SSA, the expectation of the nominators was that the cooling for any reactor on the site would be direct, rather than employing cooling towers. The exception is Oldbury, where the nominator believes that cooling towers are likely to be needed.