The Ground Self-Defense Forces ( GSDF) members have not been harmed by radiation after dumping seawater from helicopters on the troubled No. 3 reactor of the Fukushima No. 1 nuclear power plant, said Yoshifumi Hibako, chief of staff of the GSDF.

At a press conference, Hibako said the 10 GSDF members were exposed to levels of radiation lower than the upper allowable limit.

And no signs showed their health had been harmed, he said.

Earlier in the day, the GSDF dropped water on the damaged No. 3 reactor by helicopter after the plant's operator Tokyo Electric Power Co. (TEPCO) failed to cool it sufficiently on Wednesday and Thursday.

The plan was originally shelved as it was deemed too dangerous in light of the high levels of radiation, but following the rising heat of the reactor, the government decided the water drop by helicopter would be the best way to deal with climbing hydrogen levels.