Final answer:
A tsunami disabled the emergency generators cooling the Japanese nuclear plant.
Step-by-step explanation:
In March 2011, a powerful earthquake struck off the coast of Japan, triggering a massive tsunami. The F.u.k.u.s.hima Daiichi nuclear power plant was inundated by the tsunami, causing a catastrophic failure in its cooling system. The primary and backup power systems, crucial for cooling the reactors, were knocked out, leading to overheating and subsequent meltdowns in three of the plant's reactors.
The loss of cooling functionality resulted in the release of radioactive materials into the environment, prompting widespread evacuations and causing a significant nuclear disaster. This incident highlighted the vulnerability of nuclear power plants to natural disasters and spurred global discussions on nuclear safety measures and disaster preparedness.
Correct Answer: A tsunami