About a year after taking office in 2010, Naoto Kan, the prime minister of Japan at the time, had his worst nuclear nightmare.

Once the Great East Japan Earthquake hit, a tsunami followed and led to the meltdown of the Fukushima Daiichi nuclear plant.

Kan detailed his reaction to the meltdown and the reasons behind his drastic change in position — from strong support of nuclear power to opposing its use — at a packed Statler Auditorium on Tuesday.

While Japanese politicians have extensive experience responding to earthquakes and tsunamis, no one knew how to respond to an accident of this scale and the response mechanism was underprepared, Kan said.

“Not a single person could shed light on what its consequences might be,” he said in Japanese at Tuesday’s lecture, a transcript of which was provided to The Sun.

While the Nuclear and Industrial Safety Agency was built to equip the prime minister with specialized knowledge of nuclear disasters, Kan was surprised to learn that the director-general of NISA was a Tokyo University graduate with a degree in economics.

“How can we fathom the appointment of an economist to be director-general of an agency charged with responding to nuclear accidents?” Kan asked.

What was clear to Kan, however, having majored in applied physics at the Tokyo Institute of Technology, was that it would quickly become an unprecedented disaster.

“I knew that if the cooling systems were disabled, a meltdown would occur,” he said.

Realizing that even the electricity company known as Tokyo Electric Power Company that was responsible for the power plant did not have a grasp on the exact situation, Kan braced the dangers and made a personal visit to the disaster site himself on the morning after the incident.

“I went to Fukushima because I felt that I would need to have an accurate knowledge of the situation at the power plant to determine the radius of evacuation,” he said.

The week following the disaster, a series of accidents occurred: Three reactors had experienced hydrogen explosions.

Goshi Hosono, his special advisor, informed Kan about multiple “worst-case scenarios” — including the need for a forced evacuation within a 170-kilometer radius of the site and a voluntary evacuation within 250 kilometers.

Tokyo was within that range.

That plan involved the evacuation of an unprecedented 50 million people.

“Unimaginable hardship and confusion would ensue,” he said. “Yet there was nothing imaginary about this forecast. We were a hair’s breadth away from this actuality.”

While Japan had lost about 30 of its firefighters at the site during the week, Kan was shocked by TEPCO’s simultaneous request to let its employees leave the Fukushima site.

“Abandoning the reactors would mean that the situation would worsen in a matter of hours,” he said. “If the 10 reactors and 11 spent fuel pools were abandoned, Japan itself would be decimated. My own view was that to abandon the site was unthinkable.”

Kan saw TEPCO as responsible for the accident and, without TEPCO’s technicians, the situation was impossible to keep in control. He demanded that TEPCO remain on site, even if that meant putting lives at risk.

To hold TEPCO accountable, Kan established the Integrated Response Center, which facilitated communication between TEPCO and the Japanese government. This coordination allowed helicopters to pump water into the Unit 2 reactor as a measure against spreading radioactivity.

“Had venting of the Unit 2 reactor been delayed and pressure risen within its containment vessel, explosions would have erupted that shattered the entire reactor like a rubber balloon and we would have confronted my worst-case scenario,” Kan said.

Kan credited the success of avoiding the “worst case scenario” to TEPCO, Self-Defense Force members, firefighters, the police and some luck.

But, reflecting on the root cause of the accident, Kan placed part of the blame on TEPCO, claiming “TEPCO courted disaster by never formulating a contingency plan.”

Evaluating Japan’s current nuclear energy use plan, Kan was critical of the Liberal Democratic Party’s continued support for restoring nuclear power plants.

While Kan, before his resignation, had proposed reaching zero dependence on nuclear energy by 2030, the LDP chose to restore 44 reactors to operation, he said.

“However, the Japanese population at large is against this policy,” Kan said.

Under Kan’s leadership, Japan was able to deflect the worst-case scenario, but the former prime minister was quick to admit that the water contaminated by radiation from the vessels has been leaking.

Kan maintained doubt of TEPCO’s ability to complete incineration of the radioactive debris in 40 years.

“My guess is that at Fukushima the process will take more than 100 years,” he said.

Kan’s personal experience in Fukushima led him to advocate for using renewable sources — solar power, wind power and biomass — instead of relying on nuclear power and fossil fuels.

“I took my last months as Prime Minister proposing to the Diet [the Japanese parliament] a bill for the establishment of the FIT system,” he said. “Since the introduction of the FIT system, the use of renewable energy and especially solar power has grown in Japan.”

More specifically, Kan promoted combining agriculture with supplying renewable energy.

“Sunlight can be shared between crops and solar panels,” he said. “If this practice spreads, Japan could supply over half its energy supply from farmlands.”

Kan called on nations to reduce use of nuclear energy and invest in renewable energy.

“The use of renewable, natural energy and the end of reliance on nuclear energy and fossil fuels, can open a path to a peaceful world,” Kan said. “It is my intention to continue to commit myself without respite toward the achievement of this goal.”