--- title: "Nuclear Construction & the SMR Reality Check" slug: nuclear-construction type: data-index sector: energy canonical_url: https://deepstoryresearch.com/data/nuclear-construction series: [under_construction, smr_reality] series_count: 2 data_point_count: 4 data_as_of: 2025 source_quality: curated_snapshot tier: free generated_at: 2026-08-11 --- # Nuclear Construction & the SMR Reality Check _The largest backlog in thirty years, and exactly two SMRs under construction_ > Deepstory Research context file · **Free tier** · > Self-contained AI briefing. Drop into an LLM window or RAG pipeline. ## AI research use contract - Treat this file as source-grounded context, not a live database. Quote `source_ref` and `data_as_of` when using numbers. - Separate `FACT`, `ESTIMATE`, `FORECAST`, `TARGET`, and `INFERENCE`. If a row basis is unclear, say it is unclear. - Prefer T1/T2 sources for hard facts; use T3/T4 sources as context that should be checked before money, legal, medical, operational, or policy decisions. - Keep answer structure clean: first say what the data says, then what you infer, then what would change the conclusion. ## Research upgrade checklist - Count concrete, not announcements; SMR press releases vastly outnumber construction starts. - Separate large-scale from small modular capacity in every total. - Note where construction starts are concentrated — nine of ten 2025 starts were in one country. - Add a prompt on the gap between IAEA high and low SMR cases and what would close it. ## TL;DR — index summary 78 GW of nuclear capacity is under construction across 15 countries — one of the largest backlogs in thirty years — with ten construction starts totalling 12.2 GW in 2025, nine of them in China. Against that, just two commercial small modular reactors are actually under construction anywhere: a 125 MW unit in China and a 300 MW unit in Russia. ## What this index covers Two series: nuclear capacity under construction, and commercial SMR capacity actually being built. **Series in this index:** - `under_construction` — Nuclear capacity being built worldwide. - `smr_reality` — Commercial SMR capacity actually under construction. **Entities tracked:** IAEA, IEA (data), China, Russia. ## Key findings - 78 GW under construction across 15 countries (iea-ger-2026-nuclear). - Ten construction starts totalling 12.2 GW in 2025; nine in China, one in Russia (iaea-ntr-2025). - Only two commercial SMRs under construction worldwide — 125 MW in China, 300 MW in Russia (iaea-ntr-2025). - IAEA projects SMRs at 24% of new capacity by 2050 in its high case, 5% in its low case (iaea-projections). ## Evidence basis map The free tables above show `source_ref` but not the row-level `value_basis`. This section mirrors the visible rows only, so AI tools can separate observed values from estimates, forecasts, targets, and derived values. | series | row | source_ref | value_basis | | --- | --- | --- | --- | | under_construction | measure=Total under construction; gw=78 | iea-ger-2026-nuclear | 78 GW of nuclear capacity under construction across 15 countries — among the highest backlogs in 30 years | | under_construction | measure=2025 construction starts; gw=12.2 | iea-ger-2026-nuclear | Ten construction starts in 2025 (nine China, one Russia) totalling 12.2 GW | | smr_reality | project=China (commercial SMR); mw=125 | iaea-ntr-2025 | One 125 MW commercial SMR under construction in China | | smr_reality | project=Russia (commercial SMR); mw=300 | iaea-ntr-2025 | One 300 MW commercial SMR under construction in Russia | ## The series (per-chart briefings) ### Under construction — hbar **Direct answer:** Nuclear capacity being built worldwide. **Time bracket:** current | measure | gw | source_ref | | --- | --- | --- | | Total under construction | 78 | iea-ger-2026-nuclear | | 2025 construction starts | 12.2 | iea-ger-2026-nuclear | **Read:** One of the largest backlogs in thirty years. ### SMR reality check — hbar **Direct answer:** Commercial SMR capacity actually under construction. **Time bracket:** current | project | mw | source_ref | | --- | --- | --- | | China (commercial SMR) | 125 | iaea-ntr-2025 | | Russia (commercial SMR) | 300 | iaea-ntr-2025 | **Read:** Two units. Nearly all nuclear being built today is large-scale, most above 1,000 MW. ## Cross-series synthesis — why this matters The two series are deliberately paired to separate a real build-out from a narrative one. Nuclear construction is genuinely at a thirty-year high — and almost none of it is the small modular technology that dominates coverage. The IAEA's own 5%-to-24% spread for SMRs by 2050 reflects how little has been built, not disagreement about whether demand exists. Read against ai-power-demand: SMRs are frequently proposed as the answer to data-centre load, but with two units under construction the earliest meaningful contribution sits well outside the horizon on which that load is arriving. ## Entities & relationships | Entity | What they do | Key stat | Relationship | | --- | --- | --- | --- | | China | Dominant builder | 9 of 10 construction starts in 2025 | Also the SMR construction leader, with one unit | | IAEA | Data authority | Nuclear Technology Review; 5–24% SMR projection spread | Source of both the reality check and the projection range | ## Timeline of key events & decisions - **2025** — Ten construction starts, 12.2 GW, nine in China → the concentration of the build-out - **current** — 78 GW under construction across 15 countries → the thirty-year-high backlog ## Cross-industry ripple - **Data centres:** SMRs are widely proposed for the load in ai-power-demand, but construction reality puts contribution far out. _(inference)_ - **Grid planning:** A large-unit-dominated backlog means lumpy, long-lead capacity additions rather than modular ones. _(inference)_ - **Nuclear supply chain:** Concentration of starts in one country concentrates component and fuel supply capability there too. _(inference)_ ## Non-obvious reads (interpretation) _This section is interpretation, not sourced fact — each item names the observation it is built on and a confidence level._ - **Observation:** A thirty-year construction high coexists with two SMRs under construction. **Read:** The nuclear revival is real and is happening with conventional large reactors, which means the sector's actual bottleneck is large-project execution, not modular design maturity — the opposite of the assumption behind most SMR investment theses. _(confidence: medium)_ ## Glossary / key terms - **SMR** — Small modular reactor, typically under 300 MW, designed for factory fabrication. - **Construction start** — First safety-related concrete pour. The standard milestone for counting. - **GW / MW** — Gigawatt / megawatt of capacity. 1 GW = 1,000 MW. ## How to use this with AI Paste this file into an LLM context window (or a RAG store) and ask cross-series questions. The tables carry a `source_ref` per row; the source registry below maps each ref to a named source and a trust tier. ### Suggested prompts (multi-series) ```text Using under_construction and smr_reality, assess how much of the nuclear revival narrative is SMR-driven versus conventional. ``` ```text Explain what would have to happen for the IAEA high case (24% by 2050) rather than the low case (5%) to be realised. ``` ## Sources & trust | ref | source | trust tier | url | | --- | --- | --- | --- | | iea-ger-2026-nuclear | IEA — Global Energy Review 2026: Nuclear | T3 · Reputable press / research org / OWID | https://www.iea.org/reports/global-energy-review-2026/technology-nuclear | | iaea-projections | IAEA — Raises nuclear power projections for fifth consecutive year | T3 · Reputable press / research org / OWID | https://www.iaea.org/newscenter/pressreleases/iaea-raises-nuclear-power-projections-for-fifth-consecutive-year | | iaea-ntr-2025 | IAEA — Nuclear Technology Review 2025 | T3 · Reputable press / research org / OWID | https://www.iaea.org/sites/default/files/gc/gc69-inf9.pdf | ## Caveats & what this index cannot answer - Completion dates, cost, or schedule performance. - Announced or planned SMRs — this counts construction only. - Operating fleet capacity or retirements. - Estimates and forward targets are labelled in the working dataset; never read a labelled estimate or forecast as a settled figure. - This is an observational data index, not investment, legal, or medical advice. ## Data freshness & methodology - **Last updated:** 2026-08-11 - **Data as of:** 2025 - **What changed most recently:** 2025 saw ten construction starts totalling 12.2 GW, nine of them in China. **Methodology (as seeded):** > 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. --- _Free tier. The full row-level dataset and per-source detail live on the live page and in the working file. Canonical: . Deepstory Research · https://deepstoryresearch.com_