TOKYO — The command center at Japan’s stricken nuclear plant shook violently when hydrogen exploded at one reactor, and the plant chief shouted, ‘‘This is serious! This is serious!’’ videos taken during last year’s crisis reveal.
Tokyo Electric Power Co. initially refused to release the footage, but the company is now under state control and was ordered to do so.
The videos, seen Monday, are mainly of teleconferences between company headquarters in Tokyo and staff at the Fukushima Daiichi nuclear plant after the March 11, 2011, tsunami critically damaged its reactors.
In the videos, then-plant chief Masao Yoshida can be heard complaining about phone calls to the prime minister’s office not getting through and expressing frustration over interference from government nuclear safety officials whose technical advice didn’t fit conditions at the stricken plant.
In footage taken around 11 a.m. on March 15, Yoshida screams to utility officials: ‘‘Headquarters! This is serious, this is serious! The No. 3 unit. I think this is a hydrogen explosion. We just had an explosion.’’
‘‘I can’t see anything from here because of heavy smoke.’’
In the background, officials can be heard shouting questions about radiation levels and other data. The massive earthquake and tsunami that hit northeast Japan had knocked out the cooling systems that kept the reactors’ nuclear material stable, and the cores of three reactors had melted, releasing large amounts of radiation.
As workers struggled to assess the situation, they fell behind media reports. A voice from an off-site emergency center says he saw the explosion on television news.
The structures housing three of the reactors suffered hydrogen explosions after gas filled the unvented buildings, and the blasts spewed radiation and delayed repair work. In trying to halt the explosions, the videos show, officials even considered dropping a hammer from a helicopter to make a hole in the ceiling, but they scrapped the idea because it was too dangerous.
The footage shows communication problems between the plant and the government as well as workers’ lack of knowledge of emergency procedures and delays in informing outsiders about the risks of leaking radiation.
Just after the Unit 3 explosion, plant officials and executives with the electric power company discussed extensively whether to call it a hydrogen explosion. The videos also show that they failed to notify officials outside the electric power company and residents about the March 14 meltdown at another unit, No. 2, or even provide data crucial for evacuation.
The Unit 2 reactor was the most critical in the first few days.
‘‘Radiation levels are extremely high,’’ Yoshida said. ‘‘You don’t understand because you’re not here, but it’s really a skin-tight situation. [The workers] can go in only a short while, and they have to rotate.’’
The 150 hours of footage were heavily edited, with workers’ faces obscured and beeps masking voices and other sound.
In addition, Tokyo Electric Power Co. made a 90-minute video of selected clips available for download.