02 November 2011, Tokyo Electric Power Company announced that melt down has re-started in Fukushima Daiichi Reactor 2.

TEPCo detected radioactive xenon-133 and xenon-135, in the reactor’s containment vessel on 02 November.  They are produced during nuclear fission.  TEPCo poured a boric acid solution into Reactor 2 to suppress the nuclear fission (melt down).

Analysts are speculating that the other reactors at Fukushima Daiichi could also go critical.  Professor Okamoto Koji, of the University of Tokyo Graduate School, says the presence of xenon in the reactors leaves open the possibility that localized and temporary fission could still occur.

TEPCo claims that using the boric acid has cooled down the reactor.