[1] http://www.youtube.com/watch?v=NX59-ZBO3mo
Edit: There was some kind of entrance tunnel connecting there : http://exposingthetruth.info/wp-content/uploads/2012/05/fuku...
Still not clear why they'd shop that.
Edit 2: this article has more details : http://translate.google.com/translate?sl=fr&tl=en&js...
It's the entrance of the tunnel from which fuel is normally loaded.
[1] http://www.youtube.com/watch?v=NX59-ZBO3mo