Nuclear capacity under construction
Reactor capacity being built worldwide, GW.
About this data
78 GW of nuclear capacity is under construction across 15 countries — one of the largest backlogs in thirty years. 2025 saw ten construction starts totalling 12.2 GW, of which nine were in China and one in Russia.
Nuclear capacity under construction
Reactor capacity being built worldwide, GW.
Data table
| gw | series | measure | source_ref | value_basis |
|---|---|---|---|---|
| 78 | under_construction | Total under construction | iea-ger-2026-nuclear | 78 GW of nuclear capacity under construction across 15 countries — among the highest backlogs in 30 years |
| 12.2 | under_construction | 2025 construction starts | iea-ger-2026-nuclear | Ten construction starts in 2025 (nine China, one Russia) totalling 12.2 GW |
Methodology & sources
Last updated: Aug 14, 2026Methodology
Counts capacity where construction has formally started — first structural concrete poured — not announcements, letters of intent, site options or memoranda. That distinction is the entire point of this index: SMR press activity is enormous and SMR construction is almost nil. Just two commercial SMRs are under construction anywhere: 125 MW in China and 300 MW in Russia. Note the unit change — the SMR chart is in MEGAWATTS while the capacity chart is in GIGAWATTS, because plotting them on one axis would render the SMR bars invisible. Combined, those two projects are 0.425 GW against 78 GW total under construction. CAVEAT: the IAEA projects SMRs at 24% of new capacity by 2050 in its high case and 5% in its low case. That is an unusually wide spread and reflects how little has actually been built, not disagreement about demand. Those projections are NOT seeded here — they are scenario outputs, not measurements. Context: half of all capacity under construction is in China, which expects ~100 GW installed by around 2030. Egypt, India and Türkiye each have roughly 5 GW under way. Re-verified 2026-08-10.
Sources
- IEA — Global Energy Review 2026: Nuclear ↗ IEA terms — attribution required
Comparisons are informative, not definitive. See each source for definitions and limits.