The water level in a spent nuclear fuel pool at Fukushima No. 1 plant has dropped, creating the possibility of a meltdown, the container of the No. 3 reactor has possibly been damaged and the fuel in the No. 1, 2 and 3 reactors is no longer fully covered with coolant, The Mainichi Daily said on Thursday.
It warned that if no effective countermeasures are implemented, the fuel will melt which could result in a radiation leak.
Up to 64 tons of water was dumped by helicopters and fire trucks on the No. 3 unit, Kyodo said earlier in the day.
However, no major changes were seen in radioactive levels at the plant immediately afterward.
Temperatures are rising in the spent fuel rod pools of the No.3 and No.4 reactors, where a massive radiation leakage is feared.
The government's Nuclear and Industrial Safety Agency said white smoke was billowing from the No. 2 unit, suggesting that a spent nuclear fuel pool in the facility may also be boiling.
The buildings housing the No. 1, No. 3 and No. 4 reactors have been severely damaged by apparent hydrogen blasts, and the No. 2 reactor's containment vessel suffered damage to its pressure-suppression chamber at the bottom.
A series of blasts and fires damaged four of Fukushima's six reactors after a 9.0-magnitude earthquake struck off the northeast coast of Japan last week, sparking a powerful tsunami and killing thousands.
MOSCOW, March 17 (RIA Novosti)