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Wylfa Newydd

Current status

ONR’s work on the assessment of a Horizon Nuclear Power’s nuclear site licence application for Wylfa Newydd is currently suspended. The regulatory resource previously deployed on this project has been diverted to other regulatory priorities within ONR. ONR will continue to engage with Horizon Nuclear Power to receive updates on its position and to understand the consequences for the Wylfa Newydd project.


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

At the time of site licence application, the UK ABWR design was undergoing assessment as part of ONR's Generic Design Assessment (GDA) process. ONR successfully completed that assessment in December 2017 and issued a Design Acceptance Confirmation for the design.

As part of ONR's licensing assessment, we were 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.  In addition we had started to examine Horizon's development of its organisational capability to discharge the obligations associated with holding a nuclear site licence. 

It was intended that our activities during the assessment phase would be published in a Project Assessment Report drawing together the views of ONR's cornerstone/topic stream leads on Horizon's readiness to become a nuclear site licence holder.

In January 2019, Horizon's parent company Hitachi announced the suspension of work on the Wylfa project, and ONR subsequently suspended its work on the site licence assessment.