Masao Yoshida (nuclear engineer)

Masao Yoshida (February 17, 1955 – July 9, 2013) was a Japanese nuclear engineer who served as the plant manager of the Fukushima Daiichi Nuclear Power Plant during the March 2011 Tōhoku earthquake and tsunami. He is widely credited with averting a potentially catastrophic outcome at the plant following the disaster, due in part to his decisive and sometimes controversial decisions made during the crisis.

Yoshida graduated from the Tokyo Institute of Technology with a degree in metallurgical engineering and joined Tokyo Electric Power Company (TEPCO) in 1979. He rose through the ranks, becoming an expert in nuclear reactor safety.

During the Fukushima Daiichi accident, Yoshida played a critical role in managing the response to the multiple reactor meltdowns and hydrogen explosions. He defied orders from TEPCO headquarters on several occasions, most notably when he authorized the injection of seawater into Reactor 1 to cool the core and prevent a complete meltdown, a decision that was initially resisted by executives. This action, while potentially damaging to the reactor, was considered essential to prevent a runaway nuclear reaction and a larger release of radioactive materials.

Yoshida's leadership during the crisis was praised by many, including government officials and nuclear safety experts, who recognized his courage and determination in the face of overwhelming adversity. He provided crucial information to the government and the public during the early days of the crisis.

After the disaster, Yoshida cooperated with investigations into the causes of the accident. He was diagnosed with esophageal cancer in 2011, which he attributed to stress from the crisis, although TEPCO maintained it was unrelated to radiation exposure. He died in July 2013 at the age of 58. His death was mourned throughout Japan, and he is remembered as a hero who helped prevent a far greater nuclear disaster. Several books and documentaries have been made about his role in the Fukushima Daiichi accident.