The Institute for Radiological Protection and Nuclear Safety said the amount of the isotope that flowed into the ocean from the Fukushima Daiichi nuclear plant between March 21 and mid-July reached an estimated 27.1 quadrillion becquerels. A quadrillion is equivalent to 1,000 trillion.
Of the amount, 82 percent had flowed into the sea by April 8, according to the study, which noted that the amount released as a result of the disaster triggered by the March 11 earthquake and tsunami was unprecedented.
The report also said the Pacific was polluted at an exceptional speed because the plant stands in a coastal area with strong currents, though it said the impact of the contamination on marine life in remote waters is likely to wane from autumn.
But the institute warned that a significant degree of pollution would remain in waters off the coast of Fukushima Prefecture, northeast of Tokyo. Radioactive cesium-137 has a half life of around 30 years. Source