Tokyo Electric has collected nearly 1.2 million tonnes of contaminated water from cooling pipes used to keep fuel cores from melting since the plant was devastated by the earthquake and tsunami which hit eastern Japan in 2011.
The water, containing 62 radioactive elements, is stored in huge tanks on the site of the now disabled power plant, but Tokyo Electric has said it will run out of room to store the water by 2022.
The water has been treated and Tokyo Electric said it is able to remove all radioactive particles from the water to levels not harmful to humans, except tritium, an isotope of hydrogen which is more difficult to separate from water.
A panel of experts working for Japan’s economy and industry ministry concluded that letting the water run into the sea was the best option after looking at other proposals. The only other viable option considered was to let the water evaporate.
In Friday’s proposal, the ministry said the controlled release to the sea is superior because its route is predictable and easier to sample and monitor.
“Compared to evaporation, ocean release can be done more securely,” the committee said, pointing to common practice around the world where nuclear power stations operating under normal conditions routinely release water containing tritium into the sea.
But the decision will alarm neighbouring countries and comes ahead of Japan’s hosting of the 2020 Olympic Games, with some events due to be held less than 60km away from the Fukushima site.
Fishermen and residents also fear health effects from releasing the radioactive water as well as harm to the region’s image and farm industries.
Neighbouring South Korea has retained a ban on imports of seafood from Japan’s Fukushima region imposed after the nuclear disaster and summoned a senior Japanese embassy official last year to explain how the Fukushima water would be dealt with, Reuters reported.
South Korean athletes are planning to bring their own radiation detectors and food to the Games.
Experts say there is no established method to fully separate tritium from water, but it is not a problem in small amounts. Government officials also say tritium is routinely released from existing nuclear power plants around the world.
The report acknowledges the water releases would harm industries that still face reluctant consumers despite safety checks. It promised to reinforce monitoring of tritium levels and food safety checks to address safety concerns.