Assessment of overall global nuclear capacity

4.1 Overall assessment of global nuclear capacity for 2050

Global nuclear capacity would reach 1446 GWe if national government targets for nuclear capacity by 2050 are met, including those targets that would in part be met by reactors classified by World Nuclear Association as under construction, planned, proposed and potential as of 1 November 2025, and reactors currently operable continuing to operate to 2050, unless specified in the country assessments.

If achieved, this would exceed the approximately 1200 GWe global target set in the Declaration to Triple Nuclear Energy, first announced at the United Nations COP28 climate change meeting.

In 2050, 189 GWe of reactors operable in 2025 would have been in operation for less than 60 years. A minimum 60 years of operation is assumed for all currently operable reactors, except for those scheduled to be shut down as part of a phase-out policy (e.g. Spain’s nuclear reactors) or because of specific technical limitations (e.g. the UK’s AGR reactors).

An additional 213 GWe of reactors operable in 2025 would still be in operation in 2050 if their operation were extended to up to 80 years, with approximately two-thirds reaching 60-70 years of operation and one-third 70-80 years.

All 76 GWe of nuclear capacity under construction as of 1 November 2025 is assumed to be in operation by 2050.

A total capacity of 107 GWe is assumed for reactors considered as planned, according to the World Nuclear Association definition.

A total of 294 GWe is assigned to reactors categorized as proposed by World Nuclear Association. Reactors with the categorization of ‘potential’ represent 24 GWe of nuclear capacity in 2050.

The 542 GWe capacity assigned to the government target category is a summation of national capacity targets set by governments minus any part of that national capacity target that would be met by reactors in the categories above.

The chart above shows the global capacities for reactors in each category based on the combined capacity trajectories proposed for each country.

With almost all operating reactors assumed to continue operating, the increase in nuclear capacity to 2030 comes primarily from the completion of reactors currently under construction, with capacity reaching 502 GWe.

Planned reactors contribute the largest component of additional generation to 2035, with total capacity reaching 615 GWe.

Beyond 2035 proposed and potential reactors as well as capacity assigned to the additional programme of build required to reach government targets contribute to the growth in global capacity. A growing proportion of reactors operable in 2025 only continues to operate if operating lifetimes are extended beyond 60 years.

Total global capacity would reach 861 GWe in 2040 under this scenario, before reaching 1119 GWe in 2045 and 1446 GWe in 2050.

Out of the projected total global nuclear capacity of 1446 GWe in 2050, 1289 GWe is in countries where nuclear reactors already operate. This 1289 GWe capacity alone would be sufficient to meet the Declaration to Triple Nuclear Energy capacity goal.

The capacity targets for countries with operable reactors in 2025 are dominated by just five countries, with China, France, India, Russia and USA having a total of 980 GWe of nuclear reactors in 2050.

New entrant countries, including those countries with their first reactors under construction in 2025, see their total nuclear capacity reaching 157 GWe by 2050.

4.2 Analysis of potential for extended operations

According to the analysis set out above, the 189 GWe of reactors that would have operated for less than 60 years, and 213 GWe that would have operated for 60-80 years would make up just under one-third of the global capacity meeting that target.

Extending the operating lifetimes of nuclear power plants is among the most cost-effective ways of securing additional low-carbon generation, according to the International Energy Agency. ii

In 2025 the mean age of the world’s operable nuclear power reactors was 32 years. As of June 2025, there were 43 operable reactors that commenced operation more than 50 years ago, representing around 10% of currently operable reactors.

Analysis carried out for the World Nuclear Performance Report has shown that there is no overall trend suggesting an age-related decline in capacity factor, with those reactors that have operated for 40 years or more continuing to perform well.

Additionally, the average age at which nuclear reactors have been permanently shut down has been steadily increasing over time. In 2024 the average age of those reactors permanently shut down was 48 years.

Over the ten years from 2015 to 2024, the average age of reactors being permanently shut down increased by 5.5 years, continuing a trend that has been ongoing for several decades. There is no indication of a tailing off or ceiling on reactor operating lifetime being reached.

In the USA almost all operable reactors have applied to extend their operating licences from 40 to 60 years, and more than half have either applied, or intend to apply for subsequent licence extensions to operate for up to 80 years.

A limited number of reactors would not be suitable to extended operation to 2050, for example the four AGRs operating in the UK, where cracking of the graphite moderator bricks is expected to result in the closure of those reactors in the coming decade.iii

However, it is not only technical challenges that will determine the length of operation of existing nuclear reactors.

Politically-motivated phase-outs have resulted in high performing reactors closing prematurely. Germany decided to shut its reactors, despite excellent performance and the potential for decades more operation, with some reactors having operated for only 35 years. Continued operation would have had many benefits, including helping to speed the transition away from fossil fuels for electricity generation and lowering the cost of electricity in Germany for both individual, commercial and industrial users.

Spain plans to close all its reactors by 2035, with four reactors closing in 2030. Following a February 2025 plenary session of the Spanish Congress that voted in favour of calling on the government to reverse the phase-out decision, and the April 28 2025 Iberian Peninsula black-out, the conversations among all relevant stakeholders have started and there is some potential for this decision to be reversed. iv

To maximize the use of existing reactors, governments will need to continue to support their operation, in energy policy and through equitable treatment in electricity markets.

4.3 Analysis of new capacity requirements

Table 4.1 displays the five-year average for new grid connected capacity required each year to meet the global capacity targets shown in figure 4.1. The table also shows the five-year average annual capacity required to meet those targets additional to the capacity categorised as under construction, planned, proposed or potential, as of 1 November 2025, represented as ‘Government targets’ in figure 4.1.

Table 4.1 Five-year average grid connection requirements

	2026-2030	2031-2035	2036-2040	2041-2045	2046-2050
Average annual new grid connections capacity required (GWe/year)	14.4	22.3	49.2	51.6	65.3
Average annual new grid connections capacity required in addition to capacity represented by under construction, planned, proposed and potential categories (GWe/year)	1.4	6.5	17.5	30.2	52.8

A 65.3 GWe annual increase in nuclear capacity in 2046-2050 would be approximately double the peak historic capacity increase achieved in the mid-1980s.

The assumptions set out in this report are that, for most countries, planned reactors are deployed between 2035 and 2040 and proposed reactors are deployed between 2040 and 2050. The exception to this assumption is for countries with on-going construction programmes, where deployment is expected to happen around 5 years earlier. China has an ongoing new build programme, and also more planned and proposed reactors than any other country, with 48 GWe of 104 GWe of reactors planned globally, and 180 GWe of the 298 GWe reactors proposed globally.

The effect of assuming earlier construction of planned and proposed reactors in China is to bring forward a significant proportion of the reactor construction in these categories, with the consequence that there is a slowdown in the modelled deployment of planned and proposed reactors from the mid-2040s. It is in the final 5 to 10-year period that the share of new nuclear capacity assigned to additional capacity associated with government targets increases most rapidly.

The 542 GWe of additional capacity associated with government targets beyond projects assessed as planned, proposed or potential is not yet supported by identified projects, and the level of commitment through policy or other governmental measures varies significantly from country to country.

Several national targets rely heavily on an expansion of nuclear capacity where there is currently little or no ongoing construction, or identified reactors planned or proposed for deployment. This includes the 293 GWe of new nuclear capacity required to meeting USA’s 400 GWe target. Based on the assumptions in this study, nuclear capacity in the USA would need to rise from 250 GWe to 400 GWe between 2045 and 2050. In comparison, the largest global increase in nuclear capacity over a similar time period occurred between 1983 to 1988, when just over 100 GWe of capacity was added.

4.4 Concluding remarks

National nuclear capacity goals to 2050 exceed the global tripling target and reflect strong alignment between national objectives and global decarbonization needs. Achieving these ambitions will require unprecedented construction rates, strategic lifetime extension of existing reactors, and significant policy and market reforms. If nations deliver on their commitments, nuclear power would play a critical role in ensuring secure, affordable, and net zero-compatible energy for a rapidly expanding and electrified global economy.

A substantial share of the required capacity growth depends not only on reactors already under construction or formally planned, but also on large-scale programmes for proposed, potential, and government-targeted capacity that are not yet supported by firm investment decisions. Bridging the gap between stated ambitions and practical implementation will require sustained political will, timely regulatory approvals, financial innovation, and a coordinated effort between governments, industry, and the financial sector.

The continuation of existing reactors is shown to be an essential element in achieving 2050 goals. Ensuring that these reactors remain in operation—where safe and practical—will relieve pressure on new-build programmes and reduce overall system costs. However, this will require governments to adopt consistent and long-term policy positions, avoiding abrupt or politically motivated phase-outs that undermine energy security and increase dependence on fossil fuels. Reactors scheduled for closure for non-technical reasons represent a lost opportunity both for emissions reductions and for moderating the scale of new construction that would otherwise be required.

For new capacity additions, the magnitude and pace of construction implied by national targets exceed historical experience, meaning that the nuclear industry must undergo a major transformation in capability, scale, and global coordination. Without such changes, the sector risks facing bottlenecks in manufacturing, skills, regulatory review, and fuel cycle infrastructure. At the same time, emerging nuclear nations will require expanded international cooperation, including technology transfer, skills development, and financing frameworks that can support first-of-a-kind deployments in new markets.

Financial institutions, both public and private, will have an increasingly important role in enabling nuclear growth at the required scale. The alignment of climate finance mechanisms with nuclear investment, and the adoption of technology-neutral or explicitly inclusive financing policies, will be critical to ensuring that capital can flow to nuclear projects on terms compatible with large-scale deployment. Multilateral institutions will also need to expand their participation, particularly to support new-entrant countries and facilitate the construction of both small modular reactors and large gigawatt-scale facilities.

If governments uphold their stated ambitions, if regulatory and market frameworks are adapted to support both existing and new reactors, and if the nuclear industry expands its capacity to deliver at scale, the world’s nuclear fleet can more than triple by 2050. This would not only meet but exceed the declaration made at COP28, placing nuclear energy at the core of the global strategy for climate mitigation, energy security, and economic development. Failure to act, however, would leave a significant gap in global decarbonization pathways, increasing reliance on fossil fuels and raising the long-term cost and difficulty of achieving net zero emissions.

In summary, national goals for nuclear capacity growth represent a coherent and ambitious vision for the future of low-carbon energy. Realizing this vision will require collective commitment, long-term planning, and international cooperation on a scale not previously seen in the nuclear sector. If these conditions are met, nuclear power can deliver sustained, large-scale, and reliable low-carbon electricity, and contribute significantly to meeting the energy needs of a rapidly changing world.