This video from Japan says about itself:
22 October 2011
Syunsuke Yamaoka, representative of Access Journal, entered the site of Fukushima Daiichi Nuclear Power Plant illegally with a helping hand of the worker there and found Yakuza gangs arranged jobs there, especially jobs inside the buildings which would make the workers’ life get at stake and that the relationship between Yakuza gangs and TEPCO had got closer than before the accident.
And he wrote a book ‘Fukushima Daiichi Genpatu Sennyuki(Book of Infiltration into Fukushima Daiichi Nuke Plant)’ about that with interviews with three workers working there.
From the Japan Times: Tokyo Electric Power Co. turned down requests in 2009 by the nuclear safety agency to consider concrete steps against tsunami waves at the Fukushima No. 1 nuclear power plant, which suffered a tsunami-triggered disaster two years later, government documents showed Friday.
Tepco admits they concealed the fact of meltdown: here.