Masao Yoshida: Nuclear engineer who fought the tsunami meltdowns

Masao Yoshida, who led the life-risking battle at Japan's crippled nuclear power plant when it was spiralling into meltdown following the 2011 tsunami, died yesterday of cancer of the oesophagus at the age of 58. Officials at the Tokyo Electric Power Company said his illness was unrelated to radioactive exposure.

Yoshida led efforts to stabilise the Fukushima Dai-ichi nuclear power plant after the 11 March 2011 earthquake and tsunami knocking out its power and cooling systems, causing triple meltdowns and massive radiation leaks. "There were several instances when I thought we were all going to die here," he later recalled.

Yoshida, an outspoken, tall man with a loud voice who wasn't afraid of talking back to higher-ups, was also known as a caring figure to his workers. Even then-Prime Minister Naoto Kan, who was extremely frustrated by Tepco's's initial lack of information and slow handling, said after meeting him that Yoshida could be trusted.

On 12 March, after Unit 1 reactor building exploded following a meltdown, Yoshida kept pumping in sea water into the reactor to cool it, ignoring an order from the Tepco HQ headquarters to stop doing so.

He was initially reprimanded but later praised for his judgment. Kunio Yanagida, a former member of a government-commissioned accident probe panel who interviewed Yoshida for 10 hours, said his death is a major loss for future investigations into the disaster at the plant, which has not yet been fully examined due to high levels of radiation.

Yoshida studied nuclear engineering at Tokyo Institute of Technology and joined Tepco in 1979. He stepped down as plant chief Fukushima in December 2011, citing his cancer, after workers had begun to bring it under control.

Masao Yoshida, nuclear engineer: born Osaka 17 February 1955; died 9 July 2013.