Office for Nuclear Regulation

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Wylfa Newydd

Current status

On Tuesday 17 January 2019, Hitachi announced that they will suspend work on the Wylfa Newydd project.

Horizon Nuclear Power intended to construct and operate two Hitachi-GE Advanced Boiling Water Reactors (ABWR) at the Wylfa site and in March 2017, submitted its nuclear site licence application to ONR.

ONR will continue to engage with Horizon Nuclear Power to receive updates on its position and to understand the consequential impact on the strategy for the Wylfa Newydd project.

The regulatory resource currently deployed in relation to Horizon will now be diverted to other regulatory priorities within ONR.

ONR activity

Horizon Nuclear Power applied for a nuclear site licence to construct and operate two Hitachi-GE Advanced Boiling Water Reactors (ABWR) at Wylfa Newydd on Anglesey in March 2017.  Before a new nuclear power station can be built, Horizon must obtain a number of site specific permissions from the regulators and Government, including a nuclear site licence and relevant consents, environmental permits and planning permission (Development Consent Order).

The UK ABWR design is currently undergoing assessment as part of ONR's Generic Design Assessment (GDA) process. As part of ONR's licensing assessment, we are considering Horizon's plans for adapting the generic design to local conditions at the Wylfa site - for example the geology and interactions with the adjacent nuclear site - and for developing a site-specific safety case.  We are also focusing on Horizon's development of its organisational capability to discharge the obligations associated with holding a nuclear site licence.  This means that we seek confidence that Horizon is putting in place appropriate governance arrangements, resources, competencies and arrangements to manage its activities safely and securely.

ONR has developed a strategy for engaging with Horizon during our assessment of its site licence application. The strategy sets out how we will plan and manage our work and the areas that we will focus on during this assessment period.


Horizon has submitted its application for a nuclear site licence for Wylfa Newydd.  Horizon's current intention is to target licence grant date of late 2018 and we are confident that we can complete our assessment of the application within this timescale, subject to a good quality licence application, informed by continued early ONR engagement.  

We will now commence formal assessment of Horizon's application for a site licence, a process that will culminate in a recommendation to the ONR Chief Nuclear Inspector as to whether a nuclear site licence should be granted to Horizon. Our publication Licensing Nuclear Installations provides guidance on the licensing process and the factors that we may take into account when reviewing an application for a nuclear site licence. 

We have already engaged with Horizon in the period leading up to its application, providing advice on the licensing process and outlining our expectations of a licensee.  This strategy identifies our approach to the assessment phase and will ensure that regulatory interactions and decisions are managed effectively and efficiently.  It identifies a number of key areas that we will focus on during our assessment of the application. Assessment activities will be undertaken in accordance with our guidance provided in the Licensing of Nuclear Installations document and ONR's Safety Assessment Principles, Technical Assessment Guides and Technical Inspection Guides.

The overall outcome of our activities during the assessment phase will be a Project Assessment Report which draws together the views of ONR's cornerstone/topic stream leads on Horizon's readiness to become a nuclear site licence holder.  

Publication of reports

ONR is committed to being an open and transparent body. We have already published ONR's intervention strategy for engagement during assessment and will publish on this website the following material:

Useful links