Masao Yoshida (nuclear engineer)

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Masao Yoshida
Born(1955-02-17)February 17, 1955
DiedJuly 9, 2013(2013-07-09) (aged 58)

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.[1] According to nuclear physicist Dr. Michio Kaku, the decision to use seawater arguably prevented a much greater disaster.[2] 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.[3] 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.[4]

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.[5][6] [7] 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".[8]

See also[edit]


  1. ^ "In Nuclear Crisis, Crippling Mistrust". New York Times. 12 June 2011.
  2. ^ "Physicist Michio Kaku: We came close to losing northern Japan". CNN. 1 June 2011.
  3. ^ "Physicist Michio Kaku: We came close to losing northern Japan". CNN. 1 June 2011.
  4. ^ "Seismic Damage Information(the 19th Release)" (PDF). Nuclear and Industrial Safety Agency. 13 March 2011. Archived from the original (PDF) on 28 January 2013. Retrieved 12 April 2011.
  5. ^ "Ex-chief of Japan nuclear plant has cancer". Google News. Agence France-Presse. 9 December 2011. Retrieved 9 December 2011.
  6. ^ Tabuchi, Hiroko (9 August 2012). "Videos Shed Light on Chaos at Fukushima as a Nuclear Crisis Unfolded". New York Times. Retrieved 12 August 2012.
  7. ^ According to the recent book 「死の淵を見た男」(門田隆将、PHP研究所, Dec. 4th, 2012 ISBN 978-4-569-80835-2)
  8. ^ "Masao Yoshida, Nuclear Engineer and Chief at Fukushima Plant, Dies at 58". New York Times. Retrieved 10 July 2013.

External links[edit]