Feasibility Concern|Nuclear Capacity

Why this criterion? This criterion flags scenarios that assume a deployment of nuclear power-plant capacity that is inconsistent with near-term projections.

Near-term upper and lower capacity projections can be derived from existing capacities and from current project announcements and known project lead times. Robust upper projections can be made because projects take at least 5 years to plan and construct and therefore will not be operational by 2030 if not yet announced by today. Robust lower projections can be made based on exisiting capacities and because retirement rates can reasonably be assumed to be low.

Why this threshold? Data on nuclear power plants is published by the International Atomic Energy Agency (IAEA). This includes plant-level data of existing capacities (IAEA, 2026) and estimates until 2050 (IAEA, 2024).

The capacity data is published in three categories:
• Operational: in operation in 2024
• Construction: currently under construction
• Retired: inactive capacity that has been retired

Based on this capacity data, we assume the following global thresholds for 2030:
• Lower threshold, high concern: 0.0 GW to account for the fact that nuclear energy could, in principle, be phased out quickly, as observed in a few countries (e.g. Germany).
• Lower threshold, medium concern: 15% less than capacities operational in 2026, as reported by the IAEA (2026).
• Upper, medium concern: 5% more than capacities operational plus 5% more than inactive capacities in Japan (which we assume can be brought back online) plus 79% of plants under construction in 2026, as reported by the IAEA (2026).
• Upper threshold, high concern: 10% more than the highest estimate for 2030 (461 GW) published by the IAEA (2024).

Moreover, we assume the following regional thresholds for 2030:
• Lower, medium concern: 52% less than capacities operational in 2026, as reported by the IAEA (2026).
• Upper, medium concern: 40% more than capacities operational plus 40% more than inactive capacities in Japan (which we assume can be brought back online) plus 40% more than plants under construction in 2026, as reported by the IAEA (2026).

WorldGeneric regionsModel-native regions

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R5R9R10

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AIM 3.0C3IAM 3.0CGEM-ESM 1.0COFFEE 1.6GCAM 9.1GEM-E3 V2026IMACLIM 2.0IMAGE 3.4MEESA v1.4MESSAGEix-GLOBIOM 2.1-R12MINES 0.1.0OPEN-PROM 2.2POLES 2.4REMIND-MAgPIE 3.7-4.14WITCH 6.0

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Reference data

Dataset	Source	Description
`IAEA-PRIS-2026-high-proj`	IAEA (2026)	Custom projections based on IAEA (2026) with details documented in the description of the `Feasibility Concern\|Nuclear Capacity` criterion.
`IAEA-PRIS-2026-low-proj`	IAEA (2026)	Custom projections based on IAEA (2026) with details documented in the description of the `Feasibility Concern\|Nuclear Capacity` criterion.

Sources

Identifier	Bibliographic information	Links
`IAEA-E50-2024`	IAEA. Energy, Electricity and Nuclear Power Estimates for the Period up to 2050. Reference Data Series No. 1. International Atomic Energy Agency, Vienna, Austria, 44th edition, 2024. ISBN 978-92-0-123424-7.	DOI PDF
`IAEA-PRIS-2026`	IAEA. Power Reactor Information System. International Atomic Energy Agency, Vienna, Austria, jun 2026.	URL