How many nuclear reactor meltdowns occurred during the 2011 tsunami and earthquake in Japan?

The correct answer is based on the events surrounding the Fukushima Daiichi nuclear disaster, which was triggered by the massive earthquake and tsunami that struck Japan on March 11, 2011. Following the natural disasters, three reactors at the Fukushima plant experienced meltdowns. These reactors were Unit 1, Unit 2, and Unit 3, which suffered core damage due to a loss of cooling caused by the impact of the tsunami.

Additionally, it's important to consider the condition of other reactors at the facility. While there were reactors that sustained critical damages and were compromised in safety, the term "meltdown" strictly refers to the core damage that occurred in specific units. Therefore, the count is primarily focused on those three reactors that underwent significant core damage due to overheating and subsequent meltdown conditions.

This understanding clarifies why the figure of seven is often mentioned when considering broader contexts, including various safety breaches and threats, but the specific term of "meltdown" is accurately associated with the three reactors that faced nuclear core damage during the incident, leading to the overall count linked to the disaster.