Are reactors taking longer to build?
The median build, from construction start to grid connection, took 3.5 years for units connected in the 1950s and 7.7 years for units connected in the 2020s.
Years from construction start to grid connection, for every unit with both dates, grouped by the decade it connected. This is a global median across every country and design at once; it can move because building itself changed, or because who is building shifted from one era to the next. See by country or a design's own page for a narrower cut of the same measure.
| Decade connected | Units | Median years | Fastest | Slowest |
|---|---|---|---|---|
| 1950s | 12 | 3.5 | 1.2 | 4.1 |
| 1960s | 70 | 5.0 | 2.5 | 10.0 |
| 1970s | 161 | 5.4 | 3.2 | 14.4 |
| 1980s | 221 | 7.3 | 3.0 | 20.2 |
| 1990s | 49 | 8.0 | 3.2 | 22.5 |
| 2000s | 28 | 6.8 | 4.2 | 24.6 |
| 2010s | 62 | 5.9 | 4.1 | 42.8 |
| 2020s | 33 | 7.7 | 4.6 | 36.0 |
A decade with few units (see the count) is a thin sample; treat its median cautiously.
Sources
- Global Nuclear Power Tracker, Global Energy Monitor, August 2026 release , CC BY 4.0 · retrieved 2026-09-06
How these sources are used, including the corrections applied on top of them and what is deliberately left blank · download the underlying data
Cite this page
NuclearChain. "Are reactors taking longer to build?." https://nuclearchain.net/build-times/. Accessed 2026. Built on the Global Nuclear Power Tracker, Global Energy Monitor, CC BY 4.0.
Free to reuse under CC BY 4.0 with that attribution. Download the data.