Shortly after an explosion rocked the stricken nuclear plant at Fukushima last year, blanketing the plant and nearby towns in radioactive material, Masao Yoshida, the plant’s chief manager, rallied his men. “I fear we are in acute danger,” he said. “But let’s calm down a little. Let’s all take a deep breath. Inhale, exhale.”

That moment, as some of Japan’s worst fears were coming true, was captured in 150 hours of videos released by the plant’s operator last week under public and media pressure. The videos, spanning the accident’s early days, offer the first minute-by-minute account of the last-ditch effort to avert what would become the worst nuclear calamity since the Chernobyl disaster in 1986.

Although incomplete, the footage from a concrete bunker at the plant confirms what many had long suspected: that the Tokyo Electric Power Co., the plant’s operator, knew from the early hours of the crisis that multiple meltdowns were likely despite its repeated attempts in the weeks that followed to deny such a probability.

It also suggests that the government, during one of the bleakest moments, ordered the company not to share information with the public, or even local officials trying to decide if more people should evacuate.

Above all, the videos depict mayhem at the plant, a lack of preparedness so profound that too few buses were on hand to carry workers away in the event of an evacuation. They also paint a close-up portrait of the man at the centre of the crisis, Yoshida, who galvanizes his team of engineers as they defy explosions and fires – and sometimes battle their own superiors.

The footage is especially poignant because Yoshida, 57, is now fighting for his life after being found to have esophageal cancer and suffering a brain hemorrhage last month – illnesses that several experts in the US say are almost surely not a result of radiation exposure from the accident, given how quickly they came on.

At one point in the videos, as conditions at Reactor No. 3 are deteriorating, raising fears of an explosion, Yoshida sends a team of workers out from the bunker with this message: “I’m truly sorry. Please proceed with the utmost care.” He later suggests that if the situation does not improve soon, he and some older workers will consider “a suicide mission” to pump water into the reactor, a decision officials at headquarters said they would leave to him.

Despite the close-up view of the disaster, the videos – which also capture teleconferences with executives in Tokyo – leave many questions unresolved, in good part because only 50 of 150 hours include audio. The company blamed technical problems for the lack of audio.

The 50 hours with sound cover the third and fourth days of the disaster, starting in the wake of a first devastating hydrogen explosion and cataloging workers’ efforts to prevent a second blast even as nuclear fuel overheated after the breakdown of crucial cooling systems. The soundless videos start about four hours after a magnitude-9.0 earthquake struck off Japan’s Pacific coast on the afternoon of March 11, 2011, setting off a tsunami that overwhelmed the seaside plant. The sound goes on starting around midnight on March 13, and soon after, Yoshida is shown warning his bosses in Tokyo of a crippling shortage of water and gasoline.

Cooling systems

Over loudspeakers, a manager can be heard urging plant workers to bring batteries from their cars to see if they can be hooked up to provide power for the cooling systems, since poorly protected backup generators were swamped in the giant wave. The manager then apologetically asks workers to lend the plant money so it can send out a team to buy water, food and fuel.

There is a chilling reference to rising radiation levels, with an announcement made over loudspeakers that asks people to “please understand” they are being exposed to levels far above normal. Some workers did leave the plant in the first several days, and Yoshida is clearly worried such announcements will cause more to flee. “Our mission comes first,” he tells his crews.

But the situation was fast deteriorating. As the No. 3 unit shows signs of overheating, workers have trouble using fire pumps to flood it with water because of growing pressure inside the vessel housing the fuel rods. As dawn breaks, Yoshida expresses concern for the first time that the pools where used fuel rods are stored are also heating up. “We have neither water, nor ideas,” he says.

Soon after, an announcement over the loudspeakers states bluntly what the government and the company will refuse to confirm for weeks despite increasing alarm from outside experts: “The fuel has been exposed for some time now, so there is a possibility of a fuel meltdown,” it says. “Repeat, there is a possibility of a fuel meltdown.”

Even as the plant slides into chaos, top management at Tokyo Electric, or Tepco, plays down the accident. Tsunehisa Katsumata, then the company’s chairman, can be heard assuring a company adviser at headquarters that further hydrogen explosions are unlikely.

“I think possibility-wise, it’s extremely small, so do we really want to scare the public?” Katsumata says. “If we’re asked at our next press conference, we’ll deny it. We’ll say it’s impossible.”

Masataka Shimizu, then Tepco’s president, also makes sporadic appearances, barking out orders via teleconference. “Gasoline before food!” he shouts at one point to workers organizing a supply run. Both Katsumata and Shimizu have since resigned.

The videos also document frequent questions and interventions from the office of Naoto Kan, then the prime minister, many of them appearing to distract Yoshida from the rescue effort. Earlier, Yoshida ignored orders from Kan’s office to stop injecting seawater into Reactor 1, a move that could have caused further havoc.

By the morning of March 14, officials estimate the melting of 25 per cent of the core in Unit 3, and warn that water levels are falling. Yoshida decides to pull his men back from the area near the reactors, issuing an evacuation order that initially leads to news reports that Tepco had abandoned the plant. But the videos show that Yoshida and his crew stayed put at the bunker, and the workers were sent back out soon afterward.

With conditions deteriorating, an official at Tokyo headquarters says he has just received “strict orders” from the prime minister’s office that Kan wants nothing in the media about the state of reactor No. 3. Officials at the plant push back, asking what they will tell local officials pressuring them for information. But headquarters says the orders should be followed. Those orders soon became moot, when Unit 3 exploded, sending up clouds of smoke that were captured by television cameras trained on the plant.