Horizon Nuclear Power
British nuclear development company established to plan new nuclear power stations at Wylfa and Oldbury.
Last updated August 24, 2026
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Overview
Horizon Nuclear Power was a British nuclear development company created in 2009 to pursue a major programme of new nuclear generation in the United Kingdom. It began as a joint venture between E.ON UK and RWE npower, at a time when the UK was seeking to replace aging nuclear and fossil-fuel generation and expand low-carbon electricity capacity. Horizon identified two principal development sites: Wylfa on Anglesey in North Wales and Oldbury in Gloucestershire, both adjacent to existing nuclear power stations. Its initial ambition was to develop approximately 6,000 megawatts of new capacity across the sites. During its early period, Horizon assessed several reactor technologies, including Areva's European Pressurised Reactor and Westinghouse's AP1000. In 2012, E.ON and RWE put the company up for sale as a going concern. Hitachi subsequently agreed to acquire Horizon for £696 million, completing the transaction in November 2012. Under Hitachi ownership, the company adopted a plan based on Hitachi-GE's Advanced Boiling Water Reactor, or ABWR. The proposal contemplated two or three reactors at each site, subject to regulatory approval, financing, commercial agreements and planning consent. A central stage in the programme was the United Kingdom's Generic Design Assessment process for the ABWR. The assessment began in 2013 and reached its third stage in 2014 before being completed successfully in December 2017. Horizon also developed its proposed delivery and operating arrangements. In 2016, Hitachi established Hitachi Nuclear Energy Europe to lead a proposed engineering, procurement and construction arrangement involving Bechtel and JGC Corporation, while Horizon continued to work on regulatory consents, site development and commercial matters. In 2017, Horizon engaged Exelon to provide specialist personnel to support development of its prospective nuclear operating model. The projects nevertheless faced substantial financing challenges. Hitachi explored government support, including Contracts for Difference and alternative financing structures, after concluding that a fully private-sector model similar to the arrangement used for Hinkley Point C might not be suitable for subsequent projects. Discussions also considered public equity participation and debt support. Although the UK government indicated willingness to consider extensive assistance for Wylfa, Hitachi concluded that the proposed support package did not provide a sufficiently compelling economic basis for a private investment by the parent company. On 17 January 2019, Horizon suspended its UK nuclear development programme following a decision by Hitachi. Most of its approximately 380 employees were made redundant, while a small number remained involved in site maintenance and discussions about possible future financing. In September 2020, Hitachi withdrew from the Wylfa and Oldbury projects, citing the lack of progress after the suspension and the difficult investment environment associated with the COVID-19 pandemic. Horizon then began closing down its development activities while cooperating with the UK government and other stakeholders on possible future uses of the sites. In 2024, Great British Nuclear acquired the Wylfa and Oldbury sites, but this did not represent a revival of Horizon's original development programme.
History
Horizon Nuclear Power was formed in 2009 by E.ON UK and RWE npower as a joint venture dedicated to developing new nuclear generation in the United Kingdom. The company selected Wylfa in North Wales and Oldbury in Gloucestershire as its principal locations, both of which were associated with existing nuclear power stations. Its initial programme targeted roughly 6,000 megawatts of new capacity. The company initially considered Areva EPR and Westinghouse AP1000 reactors and anticipated that construction could begin during the 2010s, with generation in the following decade. In March 2012, the joint-venture owners placed Horizon on the market. Hitachi agreed to purchase the company for £696 million in October 2012, and the transaction closed in November. Following the acquisition, Hitachi selected its Advanced Boiling Water Reactor as the preferred technology. The plan contemplated two or three 1,350-megawatt units at each site. Before construction could proceed, the design had to pass the UK's Generic Design Assessment, administered by the Office for Nuclear Regulation with other regulators. The assessment started in 2013, reached its third stage in 2014 and concluded successfully in December 2017. Horizon also worked on the proposed delivery structure. Hitachi established Hitachi Nuclear Energy Europe in 2016 to lead a possible engineering, procurement and construction joint venture with Bechtel and JGC Corporation. Horizon itself retained responsibility for regulatory consents, site development and commercial arrangements. In 2017, it engaged Exelon to provide specialist staff for the design of a future operating organisation. The schedule changed repeatedly as regulatory work and financing discussions progressed. Earlier plans for site work at Wylfa in 2015 and construction in 2018 were deferred while the reactor assessment and commercial framework remained unresolved. Financing became the decisive obstacle. Hitachi considered electricity price support through Contracts for Difference and discussed alternative structures with the UK government. The company also examined arrangements in which outside investors would finance the first project and Hitachi would hold only a minority interest. In late 2018, Hitachi reported difficulty in finding investors for Wylfa. In January 2019, the UK government indicated that it was prepared to consider an equity stake of up to one-third, debt support and a long-term electricity price arrangement. Hitachi nevertheless concluded that the package did not provide adequate economic justification for proceeding as a private enterprise. Horizon announced the suspension of its UK development programme on 17 January 2019. Hitachi had spent nearly £2 billion on Horizon since acquiring it, while the proposed Wylfa ABWR development was expected to cost approximately £15 billion. Most of the company's workforce was subsequently dismissed, leaving a small group to maintain the sites and engage with government on possible financing or future options. Debate continued over whether a Regulated Asset Base model could provide a more suitable way to finance large nuclear projects than a fully private Contracts for Difference structure. In 2020, reports described discussions about restarting or selling the programme, including speculation about possible Chinese interest. Horizon said its focus remained on securing conditions for a possible restart. In September, however, Hitachi withdrew from Wylfa and Oldbury, citing the lack of progress since suspension and adverse investment conditions following the pandemic. Horizon began winding down its development activities while assisting government and other stakeholders. Great British Nuclear later bought the Wylfa and Oldbury sites in 2024. The acquisition created a new institutional context for the sites, but Horizon's original Hitachi-led programme had ended.
- 2024
Great British Nuclear acquires the sites
[1]Great British Nuclear purchases the Wylfa and Oldbury sites, which had been central to Horizon's development programme.
- 2020
Hitachi withdraws from both projects
[1]Hitachi ends its involvement in the Wylfa and Oldbury developments and Horizon begins winding down its development activities.
- 2019
UK nuclear development programme is suspended
[1]Hitachi suspends Horizon's Wylfa and Oldbury programme after failing to establish an acceptable investment and financing structure.
- 2017
ABWR design assessment is completed
[1]The ABWR completes the UK's Generic Design Assessment, allowing the project to proceed to other development hurdles.
- 2016
Hitachi organizes a proposed delivery consortium
[1]Hitachi Nuclear Energy Europe is established to lead a proposed engineering, procurement and construction arrangement involving Bechtel and JGC Corporation.
- 2013
ABWR regulatory assessment begins
[1]The proposed Hitachi-GE Advanced Boiling Water Reactor enters the UK's Generic Design Assessment process.
- 2012
Hitachi agrees to acquire Horizon
[1]Hitachi agrees to buy Horizon for £696 million, completing the acquisition later that year.
- 2009
Horizon Nuclear Power is established
[1]E.ON UK and RWE npower form Horizon as a joint venture to develop new nuclear power stations in the United Kingdom.
Products and positioning
A British new-nuclear development company focused on delivering large-scale low-carbon electricity projects through site development, reactor licensing, financing and commercial planning.
Nuclear power project
Wylfa Newydd
A proposed new nuclear power station at Wylfa on Anglesey in North Wales. Under Hitachi, Horizon planned to use two Advanced Boiling Water Reactors, each with a proposed capacity of approximately 1,350 megawatts. The project progressed through the UK reactor design assessment and extensive commercial and regulatory preparation, but it was suspended in 2019 and abandoned by Hitachi in 2020 because financing and investment conditions remained unresolved.
Nuclear power project
Oldbury new nuclear project
A proposed nuclear development adjacent to the existing Oldbury nuclear site in Gloucestershire. Horizon's broader plan envisaged multiple ABWR units across Oldbury and Wylfa, although the detailed project did not reach construction. Hitachi withdrew from Oldbury in 2020, after which Horizon closed down its development activities and the site was later acquired by Great British Nuclear.
Reactor technology development
Advanced Boiling Water Reactor programme
Horizon selected Hitachi-GE's Advanced Boiling Water Reactor as the technology for its post-2012 development strategy. The proposed reactor design had to complete the UK's Generic Design Assessment before project-specific approvals and construction could advance. The assessment was completed successfully in December 2017, but technology approval did not resolve the separate financing and investment barriers affecting the planned stations.
Brand decisions
2020
Hitachi withdraws from Wylfa and OldburyStrategyBackground
The projects had remained suspended for 20 months, while financing remained difficult and the pandemic further weakened the investment environment.
Action taken
Hitachi ended its participation in both sites and directed Horizon to close down its development activities while supporting discussions about future options.
Aftermath
The Hitachi-led development programme ended, leaving the sites available for consideration by future public or private nuclear developers.
2019
Hitachi suspends the Horizon programmeStrategyBackground
The proposed Wylfa development faced difficulty attracting investors and required a financing structure capable of supporting a project expected to cost approximately £15 billion.
Action taken
Hitachi suspended Horizon's UK nuclear development programme on 17 January 2019.
Aftermath
Most of Horizon's workforce was made redundant and only a small residual operation remained for site maintenance and discussions with government about possible future funding.
Estimated Wylfa ABWR development cost. Approximately £15 billion (2019 project estimate)
2013
Horizon adopts the ABWR development planOtherBackground
After Hitachi's acquisition, the company needed to select a reactor platform and obtain UK regulatory approval before progressing toward construction.
Action taken
Horizon pursued Hitachi-GE's Advanced Boiling Water Reactor, with plans for two or three units at each of the Wylfa and Oldbury sites.
Aftermath
The reactor design entered the Generic Design Assessment and completed the process in 2017.
2012
Hitachi acquires Horizon Nuclear PowerM&ABackground
E.ON UK and RWE npower decided to sell their joint venture as a going concern while the UK was developing a new nuclear construction programme.
Action taken
Hitachi agreed to purchase Horizon for £696 million and completed the transaction in November 2012.
Aftermath
Hitachi replaced the original German-owned joint venture as Horizon's parent and shifted the proposed reactor technology toward the ABWR.
Acquisition price. £696 million (2012)
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