Masao Yoshida (吉田 昌郎, Yoshida Masao,
17 February 1955 – 9 July 2013) was born
in Osaka, Japan and was a General Manager
in the Nuclear Asset Management Department
of the Tokyo Electric Power Co., Inc.
(TEPCO), Japan.
He was the plant manager during the Fukushima
Daiichi nuclear disaster, where he played
a critical role by disobeying corporate headquarters
orders to stop using seawater to cool the
reactors.
According to nuclear physicist, Dr. Michio
Kaku, the decision to use seawater arguably
prevented a much greater disaster.
Without the last ditch effort to use seawater
to cool the reactor, a much greater catastrophe
that could have contaminated much of northern
Japan may have occurred.
Yoshida managed to gain the trust of Prime
Minister Naoto Kan, whom he met the day after
the tsunami on a plant tour.
They had both attended the Tokyo Institute
of Technology.
On 12 March 2011, about 28 hours after the
tsunami struck, Yoshida and other TEPCO executives
had ordered workers to start injecting seawater
into Reactor No. 1 to keep the reactor from
overheating and going into meltdown.
But 21 minutes later, they ordered Yoshida
to suspend the operation.
Yoshida chose to ignore the order and ordered
the plant workers to continue.
At 20:05 JST that night, the Japanese government
again ordered seawater to be injected into
Unit 1.The week of 7 June 2011, TEPCO gave
Yoshida a verbal reprimand for defying the
order and not reporting it earlier.
Yoshida was diagnosed with esophageal cancer,
which was determined by TEPCO to be unrelated
to the nuclear accident, due to the rapidness
of its onset.
He retired as plant manager in early December
2012.
He underwent an operation for the cancer and
later suffered a non-fatal stroke.
Yoshida died on 9 July 2013.
He was 58 and is survived by his wife, Yoko,
and three sons.
"If Yoshida wasn’t there, the disaster could
have been much worse”, said Reiko Hachisuka,
head of a business group in Okuma town.
Former Prime Minister Naoto Kan tweeted a
tribute, “I bow in respect for his leadership
and decision-making".
== 
See also ==
Radiation effects from Fukushima Daiichi nuclear
disaster
Lists of nuclear disasters and radioactive
incidents
Fukushima 50
