Which nuclear power plant suffered a meltdown after the 2011 Tōhoku earthquake and tsunami?

Fukushima Daiichi was the nuclear power plant that suffered meltdowns after the 2011 Tōhoku earthquake and tsunami.

On 11 March 2011, the magnitude 9.1 Tōhoku earthquake struck off northeastern Japan. Fukushima Daiichi’s operating reactors automatically shut down, but the tsunami that followed overtopped the plant’s seawalls and disabled emergency diesel generators and electrical equipment. Without reliable power, operators could not keep the reactors adequately cooled.

Partial meltdowns occurred in Units 1, 2, and 3 over the following days. Hydrogen generated by overheating fuel accumulated in reactor buildings, causing explosions in Units 1, 3, and 4. The accident released radioactive material and led to the evacuation of more than 160,000 local residents.

Fukushima Daini was a separate nuclear station farther south; it also faced the tsunami but avoided a meltdown. Kashiwazaki-Kariwa and Hamaoka are different Japanese plants. The Fukushima Daiichi accident was rated Level 7, the highest category on the International Nuclear Event Scale.