Fukushima Daiichi Disaster
A tsunami caused by the Tohoku earthquake overwhelmed the plant's cooling systems, triggering three simultaneous reactor meltdowns.
Cause and Background
The 2011 Tohoku earthquake generated a massive tsunami that struck the Fukushima Daiichi plant. The 15-meter waves overwhelmed the seawalls and flooded the diesel generators needed to cool the reactors after shutdown, leading to a complete station blackout.
Reactor Meltdowns
Units 1, 2, and 3 suffered full meltdowns. Hydrogen gas build-up caused explosive damage to reactor buildings. Radioactive water leaked into the ocean and groundwater, causing ongoing contamination concerns that persist to this day.
Evacuation and Health
About 154,000 residents were evacuated. No direct radiation deaths were confirmed, but approximately 2,200 evacuation-related deaths (from stress, interrupted medical care, and the physical toll of displacement) have been attributed to the disaster.
The Water Problem
Cooling the damaged reactors required continuous water injection. This contaminated water accumulated in over 1,000 storage tanks at the site. After extensive treatment, TEPCO began releasing the treated water (ALPS water) into the Pacific Ocean in 2023, a controversial decision that drew protests from neighboring countries.
Decommissioning Progress
Full decommissioning is estimated to take 30-40 years. Robotic systems are being used to examine and remove fuel debris. The project is unprecedented in scale and technical difficulty.
📅 Timeline
Magnitude 9.0 Tohoku earthquake strikes
Tsunami waves (14m) hit Fukushima Daiichi
Station blackout - all AC power lost
Unit 1 hydrogen explosion
Unit 3 hydrogen explosion
Unit 4 explosion and fire
Evacuation zone expanded, plant stabilized
TEPCO begins releasing treated water into the ocean