Radioactive substances from Japan travel around the world

Japanese scientists say most of the radioactive material released from the Fukushima nuclear power plant has fallen into the sea and circulated around the planet.

Reporters visited the Fukushima I nuclear power plant on November 12. (Photo: AP)

The nuclear crisis in Japan began after the Fukushima I nuclear power plant was devastated by earthquakes and tsunamis on March 11. A large amount of radioactivity has escaped the reactors cooled down by the system.

The Japan Meteorological Research Institute said that the majority of cesium radioactivity from the Fukushima I plant had fallen into oceans around the world, AFP reported.

'The remaining radiation falls to the mainland. That means the level of radioactive contamination of the ocean is greater than on land, ' said Hiroshi Takahashi, a researcher at the Meteorological Research Institute.

The latest data from the Meteorological Research Institute show that the level of radioactive contamination of oceans after a double disaster on March 11 is not large enough to threaten human health.

Takahashi said the radioactive material spread quite wide when they fell into the ocean. Computer models show that they initially flew northeast, across eastern Russia and the US state of Alaska. They then fell into the Pacific Ocean and reached the west coast of the United States around March 17.

'We believe that radioactive substances completed the first round-the-earth trip on March 24 , ' he said.