The following are events related to the crisis at Tokyo Electric Power Co.’s six-reactor Fukushima No. 1 nuclear plant, triggered by the March 11, 2011, megaquake and tsunami.
March 11, 2011 — Magnitude 9.0 earthquake and tsunami cripple plant, cutting off power to the entire site. Government declares nuclear emergency, directing residents in a 3-km radius of the plant to evacuate.
March 12 — Prime Minister Naoto Kan inspects the plant. Hydrogen explosion occurs at reactor 1 building. Government expands evac zone to 10-km radius.
March 14 — Reactor 3 building suffers hydrogen explosion.
March 15 — Reactor 4 building hit by hydrogen explosion from gas from reactor 3.
March 20 — Reactors 5 and 6 achieve cold shutdown.
April 12 — Government raises nuclear crisis severity level to 7, highest on international scale, on par with 1986 Chernobyl disaster.
April 22 — Government designates 20-km radius of plant as no-go zone.
June 6 — The Nuclear and Industrial Safety Agency releases assessment that reactors 1, 2 and 3 had core meltdowns.
June 27 — Tepco starts cooling damaged reactors using water decontaminated through new water treatment system.
Sept. 28 — Temperatures at bottom of pressure vessels of reactors 1 to 3 fall below 100.
Dec. 16 — Government declares state of cold shutdown achieved at plant.
Dec. 21 — Government and Tepco announce plan to scrap reactors 1 to 4 in 30 to 40 years.
Feb. 28, 2012 — Private-sector panel says in report that Kan’s response to nuclear crisis created unnecessary confusion.
March 11 — Tepco President Toshio Nishizawa issues statement on first anniversary, apologizing again for disaster and vowing to continue efforts to keep plant under control.
March 30 — The government revises its designation of evacuation zones in municipalities near the plant.
April 19 — Reactors 1 to 4 declared defunct, leaving Japan with 50 operable commercial reactors.
May 5 — The last of Japan’s commercial reactors goes offline.
June 27 — Tepco Chairman Tsunehisa Katsumata and President Toshio Nishizawa step down, succeeded by lawyer Kazuhiko Shimokobe and Tepco Managing Director Naomi Hirose, respectively.
July 1 — A reactor at Kansai Electric Power Co.’s Oi nuclear power plant in Fukui Prefecture becomes the first to be restarted. Another Oi reactor is restarted on July 18.
July 5 — Diet-appointed panel investigating the Fukushima crisis releases a report saying the disaster was “man-made.”
July 18-19 — Tepco finishes trial removal of two unused nuclear fuel assemblies from teetering reactor 4 spent-fuel pool.
July 23 — A government-appointed panel probing the Fukushima disaster releases final report saying Tepco mishandled response to crisis.
July 31 — Tepco receives a ¥1 trillion capital injection from a state-backed bailout fund, falling under effective state control.
Aug. 6 — Tepco discloses to the media part of the video recordings of its teleconferences in the first days of the crisis.
Sept. 19 — Japan launches new Nuclear Regulation Authority, replacing NISA.
Jan. 1, 2013 — Tepco sets up Fukushima headquarters to deal with issues stemming from the disaster.
March 11 — Japan marks second anniversary of 3/11.