Definitions of capacity categories
The following assessments assign nuclear capacity to 2050 in each county for each of the following categories:
60-year operation
The capacity that would be delivered if all operable reactors as of 1 November 2025 operate for up to 60 years. This is assumed for all currently operable reactors except 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).
80-year operation
The additional capacity that would be delivered if those reactors that would exceed 60 years of operations before 2050 continue to operate for up to 80 years.
Under construction
The capacity that would be delivered by those reactors under construction as of 1 November 2025. Start-up dates are estimated based on latest announcements, where available, or World’s Nuclear Association’s assessment.
Planned
The capacity that would be delivered by those reactors that, on 1 November 2025, are categorized as planned, according to the World Nuclear Association definition of a reactor with approvals, funding or commitment in place, and mostly expected to be in operation within the next 15 years.
To estimate potential start-up dates, the first planned reactors are considered to become operable no earlier than 2035, with construction of all reactors to have been completed by 2040, in line with the definition’s 15-year timeframe. Exceptions include those planned reactors that either already have construction start-up dates or grid-connected dates specified, or for countries with active build programmes, where the first reactors are estimated to start operation in 2030, consistent with construction starting in the coming months and 5–6-year build times being achieved, as is regularly the case in China.
Proposed
The capacity that would be delivered by reactors categorized as proposed by World Nuclear Association, as of 1 November 2025.
The proposed categorization represents those reactors for which there are specific programmes or site proposals, but the timing of construction and operation is very uncertain. For the purposes of this report, the first of these proposed reactors are assumed to start coming online from 2040, and for all proposed reactors to have entered operation by 2050. Exceptions apply if construction starts or grid-connection starts have been specified that indicate grid connection would take place ahead of 2040. Additionally, for countries with active build programmes, the first proposed reactors are estimated to be grid connected from 2036.
Potential
The ‘Potential’ categorization has not previously used by World Nuclear Association. This represents the capacity that would be delivered by reactors that have been announced, but where those announcements are not sufficiently advanced to be categorized as planned or proposed by World Nuclear Association. For example, the India country assessment includes as potential capacity the series of Bharat Small Reactors announced by its finance minister in the 2024 Budget speech.
Government target
This represents the capacity that would be delivered if the targets for nuclear capacity in 2050 announced by governments are met. Where government targets are to be met before 2050 that target is assumed to still apply 2050 if no later target has been announced.
Where a government target sets an overall capacity target it is assumed that part of this target capacity will be met by those reactors that would have less than 60 years of operations by 2050, those reactors operating in 2050 if they have not yet reached 80 years of operation, and the additional capacity of those reactors defined, as of 1 November 2025, as under construction, planned, proposed or potential, unless the target has been specified as being additional.