Pacific Ocean radiation back near normal after Fukushima: study

Radiation levels across the Pacific Ocean are rapidly returning to normal five years after a meltdown at the Fukushima nuclear plant spewed gases and liquids into the sea, a study shows. Japan shut down dozens of reactors after a magnitude 9.0 earthquake-generated tsunami on March 11, 2011 triggered one of the largest ever dumps of nuclear material into the world’s oceans. In the days following the quake and explosions at Fukushima, seawater meant to cool the nuclear reactors instead carried radioactive elements back into the Pacific, with currents dispersing it widely. Five years on a review by the Scientific Committee on Oceanic Research, which brings together ocean experts from across the world, said radioactive material had been carried as far as the United States.

As an example, in 2011 about half of fish samples in coastal waters off Fukushima contained unsafe levels of radioactive material. However, by 2015 that number had dropped to less than one percent above the limit.

Pere Masque, co-author of the review

But after analysing data from 20 studies of radioactivity associated with the plant, it found radiation levels in the Pacific were rapidly returning to normal after being tens of millions of times higher than usual following the disaster. The research examined radioactive caesium levels measured off Japan’s coast across the Pacific to North America. Caesium is a by-product of nuclear power and is highly soluble in water, making it ideal for measuring the release of radioactive material into the ocean, it said. Although no one is recorded as having died as a direct result of the nuclear accident, tens of thousands of people were uprooted, with many still unable to return home because of persistent contamination.

Fukushima