Japanese fisher groups have opposed the plan for fear it will further damage to the reputation of their seafood. Groups in China and South Korea have also raised concerns, making it a political and diplomatic issue.
But the Japanese government and Tepco say the water must be released to make room for the plant’s decommissioning and to prevent accidental leaks. They say the treatment and dilution will make the wastewater safer than international standards and its environmental impact will be negligibly small. But some scientists say the long-term impact of the low-dose radioactivity that remains in the water needs attention.
The water release begins more than 12 years after the March 2011 nuclear meltdowns, caused by a massive earthquake and tsunami. It marks a milestone for the plant’s battle with an ever-growing radioactive water stockpile Tepco and the government say has hampered the daunting task of removing the fatally toxic melted debris from the reactors.
The pump activated Thursday afternoon sent the first batch of the diluted, treated water from a mixing pool to a secondary pool 10 minutes later. It then moves through a connected undersea tunnel to go out one kilometre off the coast. Officials said the water moves at a walking speed and will take about 30 minutes to exit from the tunnel.
The operator checked data and the progress on a set of four monitors that show the water volume, pump conditions and any alerts.
Tepco executive Junichi Matsumoto said Thursday’s release was planned start small in order to ensure safety.
The wastewater is collected and partly recycled as cooling water after treatment, with the rest stored in around 1,000 tanks, which are already filled to 98 per cent of their 1.37-million-tonne capacity. Those tanks, which cover much of the plant complex, must be freed up to build the new facilities needed for the decommissioning process, officials said.
Final preparation for the release began on Tuesday, when just one tonne of treated water was sent from a tank for dilution with 1,200 tonnes of seawater, and the mixture was kept in the primary pool for two days for final sampling to ensure safety, Matsumoto said. A batch of 460 tonnes was to be sent to the mixing pool on Thursday for the actual discharge.
Fukushima’s fisheries, tourism and economy — which are still recovering from the disaster — worry the release could be the beginning of a new hardship.
Fukushima’s current fish catch is only about one-fifth its pre-disaster level, in part due to a decline in the fishing population. China has tightened radiation testing on Japanese products from Fukushima and nine other prefectures, halting exports at customs for weeks, Fisheries Agency officials said.
Prime Minister Fumio Kishida said the release is indispensable and and could not be postponed. He noted an experimental removal of a small amount of the melted debris from the No. 2 reactor is set for later this year, using a remote-controlled giant robotic arm.
In 2021, the Japanese government announced plans to release the treated water to the sea. Then, on Sunday, Kishida made a rushed visit to the plant before meeting with fisheries representatives and pledging to support their livelihoods until the release ends.
The hurried timeline raised scepticism that it was made to fit Kishida’s busy political schedule in September. But Economy and Industry Ministry officials say they wanted the release to start as early as possible and have good safety records ahead of the fall fishing season.
The March 2011 earthquake and tsunami destroyed the plant’s cooling systems, causing three reactors to melt. Highly contaminated cooling water applied to the damaged reactors has leaked continuously to building basements and mixed with groundwater.
Tepco plans to release 31,200 tonnes of the treated water by the end of March 2024, which would empty only 10 tanks because of the contaminated production of wastewater at the plant, though the pace will later pick up.
