Masao Yoshida, who managed Japan’s Fukushima Daiichi nuclear power during its meltdown in 2011 and was considering a hero for his crucial decisions to contain the accident, has died of esophageal cancer, reports Business Insider.

He was 58.

Because his condition worsened so quickly, some were skeptical of experts who said Yoshida’s cancer was not linked to the nuclear meltdown.

Yoshida’s status as a national hero is based predominantly on his decision to use seawater to cool fuel rods that were overheating when the plant’s cooling systems were compromised by powerful earthquake and tsunami.

Yoshida famously rejected requests from both Prime Minister Naoto Kan and senior officials from the plant’s operator on the day after the accident to stop injecting seawater into the reactors.

The requests were based on the belief that seawater might cause fission chain reaction, but Yoshida's plan proved those fears to be unfounded and he was never reprimanded for his disobedience.

“If Yoshida wasn’t there, the disaster could have been much worse,” said Reiko Hachisuka, a member of a panel that investigated the accident.

Former Prime Minister Naoto Kan also tweeted a tribute, saying, “I bow in respect for his leadership and decision-making.”