Tokyo Electric Power Company Holdings submitted the plan in December, based on the government’s decision to release wastewater as a necessary step to clean and deactivate the ongoing plant last year.
A massive earthquake and tsunami in 2011 destroyed the cooling systems of the Fukushima plant, melting three reactors and emitting large amounts of radiation. The water that has been used to cool the cores of the three damaged reactors, which are highly radioactive, has since leaked but has been collected and stored in tanks.
Tritium – a by-product of nuclear power generation and a potentially high level of carcinogenic wastewater discharge – has potential health risks in the community and neighboring countries.
The government and TEPCO say that more than 60 isotopes selected for treatment could be reduced to meet safety standards without tritium, but it is safe to dilute. Scientists say the long-term effects of short-doses are unknown to the environment and humans, and that tritium can have a greater impact on humans when eating fish than on water.
Toyoshi Phuketa, chairman of Japan’s Atomic Energy Authority, said the plan was designed to be “conservative” so that the effects of radiation on the environment could still be considered legal.
Under the plan, TEPCO will transport purified water from the tank through a pipeline below the discharge level to a coastal facility, where the water is mixed with seawater.
From there, the water will enter an underwater tunnel for drainage at a point about 1 kilometer (0.6 miles) from the plant to ensure safety and reduce impact on local fishing and the environment, according to TEPCO.
The plan will become official after a 30-day public review, a formality that is not expected to overturn approval.
The green light came as International Atomic Energy Agency (IAEA) director Mariano Grossi arrived in Japan for a meeting with top officials to discuss the plan, which has garnered international attention.
Phuketa will meet with Grosi on Friday after the IAEA director visited the Fukushima plant on Thursday and met with other Japanese officials.
The government and TEPCO plan to gradually release purified water in the spring of 2023
Contaminated water is being stored in about 1,000 tanks at the damaged plant, which officials say needs to be removed so that facilities can be created to disable it. The tanks are expected to reach 1.37 million tons next year – slower than previously estimated by the end of this year.
Japan has sought the assistance of the IAEA to ensure that water emissions meet international safety standards and to reassure local fishermen and other communities as well as neighboring countries who have strongly criticized the plan.
A team of IAEA experts visited the plant in February and March for meetings with Japanese government and TEPCO officials. The task force said in a report released in late April that Japan was making “significant progress” on the plan and was taking appropriate steps toward a planned evacuation.