@farmerman,
They are also spraying water canons from fire trucks at it.
From NHK:
SDF begins efforts to cool down nuclear plant
Two helicopters from Japan's Self-Defense Forces are dropping water on the Number Three building at the quake-damaged Fukushima Daiichi nuclear power plant.
The helicopters began dousing the damaged reactor-housing building at 9:48 AM on Thursday.
The SDF has dispatched two CH-47 helicopters equipped with a device for dropping 7.5 tons of water.
They're being accompanied by another helicopter that is measuring radiation levels above the plant. The first water-dropping operation was completed at around 10:15 AM.
Fears of radiation leaks are rising for the plant's two reactors, where water in the pool for spent nuclear fuel is believed to be vaporizing due to the failure of the cooling system.
This could expose the fuel rods, possibly causing them to melt and discharge radioactive material into the air. The government's emergency task force has asked the SDF and the police to cool down the reactor buildings by refilling the pool.
The SDF is also sending 11 high-pressure fire trucks from their bases across Japan to spray water on the reactor buildings.
A high-pressure fire truck from the Tokyo Metropolitan Police Department is also set to begin spraying water onto the Number Four reactor building.
Thursday, March 17, 2011 10:34 +0900 (JST)