Follow latest updates at twitter.com and www.facebook.com The situation at the Fukushima nuclear plant in Japan worsens as a second explosion is reported, intensifying fears of the possibility of nuclear meltdown triggered by last week’s huge earthquake. At least seven are missing with several others hurt after the blast - which is not however believed to have pierced the structure containing the reactor's core. Meanwhile crews are fighting to cool down the overheated radioactive fuel rods at the plant to avert a catastrophic nuclear meltdown. Christopher Simons, a professor at a Tokyo university, explains how an explosion might occur, and what the worst-case scenario could mean for local residents...