BWR-4
The BWR-4 is a Generation II boiling water reactor from GE Vernova Hitachi Nuclear Energy. 17 units are operating and 0 are under construction, out of 31 on record.
The most-built BWR generation, a BWR-3 with a higher power density in the same vessel. Browns Ferry, Peach Bottom, Hatch, Brunswick, Limerick, Fermi 2 and most of the Japanese fleet are BWR-4s. Fukushima Daiichi Units 2 to 5 were BWR-4s. The Mark I containment they usually sit in is a small inverted light bulb over a torus, and its size relative to the core is the reason overpressure protection dominates their accident analysis.
| Vendor | GE Vernova Hitachi Nuclear Energy |
|---|---|
| Reactor type | Boiling water reactor (BWR) |
| Generation | II |
| Capacity range | 600–1200 MWe gross |
| Also recorded as | BWR-4 (Mark 1) BWR-4 (Mark 2)in the source tracker |
| Coolant | Light water |
| Typical enrichment | 3–5% U-235 |
| United States | 20 units, 17 operating |
|---|---|
| Japan | 7 units |
| Taiwan | 2 units |
| Switzerland | 1 unit |
| Italy | 1 unit |
How long it took to build
Years from construction start to grid connection, for units with both dates on record. The median across 30 finished units is 6.1 years.
All BWR-4 units
Sources
- BWR-4, vendor documentation
- 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