Japan's Self-Defense Force started dumping water on the damaged No. 3 reactor by helicopter following the plant's operator Tokyo Electric Power Co. (TEPCO) failing to cool it sufficiently on Wednesday and Thursday, Xinhua News Agency reported on Thursday.

A Japan Air Self-Defense Force CH-47 Chinook helicopter collects water from the ocean to drop on the reactors at the Fukushima Daiichi nuclear plant in Fukushima March 17, 2011.[Xinhua]

Yesterday Japanese Defense Ministry officials said the SDF dropped the plan to dump water from helicopters on the troubled No. 3 reactor of the Fukushima nuclear power plant due to the high radiation level around the plant.

But as the heat contiued to rise, the government decided the water drop by the helicopters would be the best way to deal with climbing hydrogen levels, according to Xinhua report.

The GSDF Ch-47 helicopters can carry up to 7.5 tons of water and have also started dumping water on the No. 4 reactor as well, Xinhua added.

Meanwhile, a Tokyo police unit  will use a water cannon truck to cool down a spent fuel rod pool in the No. 4 reactor at the quake-stricken Fukushima Daiichi nuclear power plant.

The police announced that the ground operation will involve spraying water from outside of the reactor and is due to start on Thursday morning.

Following Friday's devastating earthquake and tsunami in northeastern Japan, the temperature has been rising in the building that housing the No. 4 reactor and its spent fuel storage pool, as cooling systems failed, Xinhua reported.