Radioactive fallout hit oceans

Most of the radioactive fallout from the disaster at the Fukushima nuclear plant fell into the ocean, Japanese researchers say.

Up to 80 per cent of the caesium released after the March 11 disaster landed in the Pacific and made its way around the world, scientists at the Meteorological Research Institute said.

"The rest has fallen on land" in and around Fukushima.

Researchers say the radioactive materials were widely dispersed when they entered the oceans and each particle would measure less than one micrometre.