White smoke started spewing from the stricken No. 3 reactor at the Fukushima No. 1 nuclear power plant around 8:30 a.m. Wednesday.
There is the possibility that water in the pool where nuclear fuel rods are stored may be boiling.
High levels of radiation were measured near the Fukushima plant Wednesday morning. There are growing concerns that the high radiation levels are due to damage to the core containment vessel at the No. 2 reactor.
Radiation levels of 10,000 microsieverts (10 millisieverts) per hour were recorded at the main entrance to the Fukushima plant at about 10:40 a.m.
Referring to the smoke billowing from the No. 3 reactor, Chief Cabinet Secretary Yukio Edano said at a news conference around 11 a.m. Wednesday: "We have received a report that steam is being emitted from the containment vessel of the No. 3 reactor. The temporarily high radiation levels may have been due to the steam (that contains radiation)."