Ohi Unit 4

Ohi 4 is a 1,127 MWe (net) Kansai Electric PWR. After running in 2012-2013 it was the last Japanese reactor operating when it shut on 15 September 2013, and it restarted under the new NRA rules in May 2018; it is operating.

Background: Palisades fuel loading: Holtec restart timeline and what comes next · NRC reactor licensing process, explained

Current state

Notes

shut down is the September 2013 shutdown after the 2012 interim restart. Local consent per WNN's Ohi 3 article (Nov 2017).

Timeline

• 2013-09-15 — Ohi 4 entered a periodic outage inspection, leaving Japan with no operating reactors. (source)
• 2017-05-24 — The NRA officially approved Ohi 3 and 4. (source)
• 2018-05-09 — Kansai restarted Ohi 4. (source)
• 2018-06-05 — The unit resumed commercial operation. (source)
• 2026-06-22 — Ohi 4 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

1. Current Status of Nuclear Power Plants in Japan as of August 7, 2026 — Japan Atomic Industrial Forum (JAIF) (primary), checked 2026-10-11
2. Nuclear Power in Japan — World Nuclear Association, checked 2026-10-11
3. Schedule of Ohi Unit No. 4 Reactor Startup and Power Control Operation — Kansai Electric Power (primary), checked 2026-10-11
4. Japan's Ohi 4 restarts — Nuclear Engineering International, checked 2026-10-11
5. Ohi 3 reaches critical milestone in restart — World Nuclear News, checked 2026-10-11