Belgium’s nuclear power sector has entered an unusual period in which continued generation and permanent closure are taking place at the same time. Five commercial reactors have now stopped producing electricity, while the two youngest units, Doel 4 and Tihange 3, have received ten-year operating extensions.
The result is not a return to Belgium’s former seven-reactor system. It is a smaller nuclear programme built around approximately 2,056 megawatts of net capacity, supported by a new partnership between the Belgian state and energy company ENGIE.
At the same time, Belgium has removed the legal commitment that once required a complete nuclear phase-out. This has reopened the political and legal possibility of future nuclear construction, although no new commercial reactor is currently being built.
Belgian nuclear policy is therefore no longer defined by a simple choice between continued operation and complete withdrawal. The country is extending selected reactors, dismantling older units, transferring waste liabilities and deciding whether nuclear power should remain part of its energy system beyond 2035.
Belgium’s Seven-Reactor Fleet Has Been Reduced to Two
Commercial nuclear generation in Belgium developed around two sites. The Doel power station, near Antwerp and the Dutch border, operated four reactors. Tihange, beside the River Meuse in Wallonia, operated three.
The reactors were connected to the grid between the 1970s and the mid-1980s. Together, they once supplied a large part of Belgian electricity and gave the country one of Europe’s higher levels of nuclear dependence.
That fleet has now been substantially reduced. Doel 3 permanently closed in 2022, followed by Tihange 2 in 2023. Doel 1 closed in February 2025, Tihange 1 in September and Doel 2 in November. These closures left Doel 4 and Tihange 3 as Belgium’s only operating commercial power reactors.
Both remaining units are pressurised water reactors that first connected to the grid in 1985. Doel 4 has a net generating capacity of approximately 1,026 megawatts, while Tihange 3 provides about 1,030 megawatts.
The reduction has changed the position of nuclear power within the electricity market. In 2024, before the final three older reactors closed, Belgian nuclear plants supplied about 30.7 terawatt-hours of electricity. That represented more than 40% of the country’s reported electricity generation.
The two-reactor fleet cannot reproduce the output of the former system. Belgium must increasingly combine nuclear generation with offshore wind, solar power, natural gas plants, electricity imports, demand management and stronger regional grid connections. Nuclear energy remains important, but it no longer dominates the system to the same degree.
Doel 4 and Tihange 3 Received a Ten-Year Extension
Belgium adopted a nuclear phase-out law in 2003, setting a timetable under which reactors would close after 40 years of operation. The policy was amended several times as concerns about electricity supply, market conditions and replacement capacity changed.
The decisive shift came after the European energy crisis that followed Russia’s invasion of Ukraine. High gas prices and concerns about security of supply made the closure of all remaining reactors more difficult to defend. In 2022, the federal government decided to seek a ten-year extension for Doel 4 and Tihange 3.
The final arrangement was completed in March 2025 after approval from the European Commission. The reactors underwent major outages and technical work needed for long-term operation. Tihange 3 returned to service in July 2025, while Doel 4 reconnected to the grid in October.
Their revised operating period runs until 2035. Regulatory approval requires continued inspection, ageing management, equipment replacement and compliance with safety conditions established by Belgium’s Federal Agency for Nuclear Control.
Keeping the reactors open provides Belgium with approximately two gigawatts of low-carbon generating capacity. It also reduces the amount of gas-fired generation and electricity imports that may be needed when wind and solar output is low.
The extension does not guarantee uninterrupted output. Older reactors require maintenance and can experience unplanned outages. The electricity system must still maintain enough alternative capacity to cover periods when one or both units are unavailable.
The Belgian State Has Taken a Direct Financial Role
The life-extension agreement changed the ownership and financial structure of Belgian nuclear generation. Doel 4 and Tihange 3 were transferred to BE-NUC, a joint venture owned equally by the Belgian state and ENGIE.
This structure places the government directly inside the remaining commercial nuclear business rather than leaving the full operating and investment risk with a private utility. Strategic and operational decisions require agreement between the two shareholders.
The extension is supported by a contract-for-difference mechanism. This is designed to provide predictable revenue for nuclear generation while limiting exposure to large movements in wholesale electricity prices. The arrangement helps protect the investment required to extend the reactors, but it also transfers part of the long-term financial risk to the state.
Waste responsibilities formed another major part of the agreement. ENGIE agreed to make payments valued at €15 billion in 2022 money in exchange for the transfer of financial responsibility for specified nuclear waste and spent-fuel obligations to the Belgian state. ENGIE retains responsibilities connected to plant shutdown, dismantling, conditioning and on-site storage until the waste can be transferred under the agreed system.
This division of responsibility was necessary because nuclear liabilities continue long after electricity sales end. Belgium must finance waste storage, disposal and decommissioning over many decades, during which costs and technical requirements can change.
The agreement made continued operation commercially possible, but it also demonstrated that extending an ageing nuclear fleet is not simply an engineering decision. It requires a negotiated allocation of electricity-price risk, investment costs, waste liabilities and state responsibility.
Decommissioning Is Becoming a Major Nuclear Industry
While two reactors continue operating, five others are moving through the post-operation and decommissioning process. This involves much more than closing a plant and removing it from the grid.
Fuel must first be removed from the reactor and transferred to cooling or storage systems. Operational waste must be processed, contaminated systems must be cleaned, and detailed inventories must be prepared before large-scale dismantling can begin.
Electrabel remains responsible for safety at the sites during these activities. The Federal Agency for Nuclear Control and its technical subsidiary, Bel V, supervise the process, review licence applications and conduct inspections. Belgium’s radioactive waste organisation, ONDRAF/NIRAS, is responsible for the national waste-management framework.
Decommissioning will continue for many years and will create a sustained market for radiation protection, engineering, robotics, waste treatment, transport, storage and environmental monitoring. Belgium’s long history in nuclear research and operations gives it a workforce capable of supporting this work, but the scale of simultaneous closures will place pressure on specialist capacity.
The two sites will also remain complex because shutdown reactors are located beside operating units. At Doel, dismantling work must take place while Doel 4 continues generating electricity. The same applies to Tihange 3. Security, staffing and safety systems must therefore account for different stages of the nuclear life cycle on a single site.
The final objective is to remove radiological risks and eventually release areas for other uses. Reaching that point requires regulatory approval at each stage and a long period of controlled dismantling and waste management.
Belgium Has Abandoned a Fixed Nuclear Exit
The Belgian parliament removed the statutory nuclear phase-out in 2025. This did not automatically approve new reactors, but it ended the legal framework that treated complete withdrawal from nuclear power as a fixed national destination.
Belgium can now consider additional life extensions, large reactors or small modular reactors without first reversing a legal prohibition. However, the practical barriers remain substantial. New nuclear construction would require a site, technology selection, financing model, waste arrangements, grid planning and political agreement across Belgium’s divided federal and regional system.
Timing is also important. Doel 4 and Tihange 3 are currently scheduled to close in 2035. A large reactor project would need to advance quickly to replace them without a gap. Small modular reactors may offer another route, but commercial schedules, costs and licensing remain uncertain.
Belgium’s near-term nuclear future is therefore based on two existing reactors rather than a confirmed construction programme. The country has moved away from a complete exit, but it has not yet chosen the size or form of the system that might follow.
By extending Doel 4 and Tihange 3, Belgium has purchased additional time. That period must now be used to strengthen renewable generation and grids, manage five reactor closures, develop long-term waste solutions and decide whether nuclear power should continue beyond the remaining fleet.
