Onagawa 2 is Tohoku Electric's 796 MWe (net) BWR, the closest plant to the 2011 quake epicentre. In October 2024 it became the first boiling water reactor in Japan to restart after Fukushima, following upgrades including a 29-metre seawall; it is operating.
Background: Palisades fuel loading: Holtec restart timeline and what comes next · NRC reactor licensing process, explained
Current state
| Status | Restarted |
| Country | Japan |
| Location | Onagawa and Ishinomaki, Miyagi Prefecture |
| Plant | Onagawa |
| Unit | 2 |
| Operator | Tohoku Electric Power |
| Reactor type | BWR |
| Net capacity (MWe) | 796 |
| Restart type | Post-Fukushima restart |
| Shut down | 2010-11-06 |
| Restarted | 2024-10-29 |
| Years offline | 14 |
| Regulator | NRA conformity approval 2020-02-26 |
| Local consent | Miyagi governor consented 2020-11-11 after prefectural assembly approval in October 2020 |
| Cost estimate | JPY 340bn |
Notes
cost estimate is Tohoku's ~JPY340bn estimate for safety countermeasures (seismic reinforcement, 29 m x 800 m seawall) as reported by WNN in 2020, not a final cost. Power generation resumed 2024-11-15 after a brief November halt (JAIF).
Timeline
- 2010-11-06 — Onagawa 2 entered an outage; it was in startup when the March 2011 earthquake struck. (source)
- 2013-12-27 — Tohoku applied for the NRA conformity review. (source)
- 2020-02-26 — The NRA approved the final screening report. (source)
- 2020-11-11 — Miyagi Governor Murai Yoshihiro gave consent to restart. (source)
- 2024-10-29 — Tohoku restarted Onagawa 2, the first Japanese BWR restart. (source)
- 2024-12-26 — The unit resumed commercial operation. (source)
- 2026-06-09 — Onagawa 2 restarted commercial operation after a periodic inspection. (source)
The timeline is append-only: corrections are added as new entries. Stated targets appear in the current-state table, never as milestones.
Related units
- Genkai Unit 3 Restarted · Japan
- Genkai Unit 4 Restarted · Japan
- Hamaoka Unit 3 Cancelled · Japan
- Hamaoka Unit 4 Cancelled · Japan
- Higashidori Unit 1 (Tohoku Electric) Under review · Japan
- Ikata Unit 3 Restarted · Japan
- Kashiwazaki-Kariwa Unit 6 Restarted · Japan
- Kashiwazaki-Kariwa Unit 7 Approved · Japan
See all 45 units in the Nuclear Plant Restarts Tracker →
Sources
- Current Status of Nuclear Power Plants in Japan as of August 7, 2026 — Japan Atomic Industrial Forum (JAIF) (primary), checked 2026-10-11
- Current Status of Nuclear Power Plants in Japan as of March 14, 2019 — Japan Atomic Industrial Forum (JAIF) (primary), checked 2026-10-11
- Nuclear Power in Japan — World Nuclear Association, checked 2026-10-11
- Local consent clears way for restart of Onagawa 2 — World Nuclear News, checked 2026-10-11
- Shimane 2 restarts after 13 years being offline — World Nuclear News, checked 2026-10-11
- Onagawa-2 restart brings number of nuclear reactors online to 13 — NucNet, checked 2026-10-11